The process turns "an endothermic heart into an ectothermic one," Dr. Seymour said.
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He took out Mei's endothermic blasters and started firing off icicles toward Liviere.
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For close-quarters engagements, there are few better Overwatch weapons than Mei's Endothermic Blaster.
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Because this is a rather "endothermic" process right now, you need other sources of income.
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This means that their thermoregulation processes are very different from warm-blooded, or endothermic, organisms.
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That happens because of an endothermic reaction that pulls heat from the snow to the salt.
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Crocodiles are also members of the wider archosaur lineage, a group that includes endothermic pterosaurs, dinosaurs and birds.
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While he largely agrees with the research, Dr. Seymour is more measured on whether early crocodyliforms were properly endothermic.
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It's not yet known whether dinosaurs in general, and T. rex in particular, were ectothermic (cold-blooded) or endothermic (warm-blooded).
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It's now the first example of fossilized ichthyosaur blubber in the scientific literature, pointing to ichthyosaurs as warm-blooded, or endothermic, organisms.
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The warmer climate of the Late Triassic Period and Early Jurassic Period may have helped boost the metabolism of early crocodile relatives without requiring a fully endothermic metabolism.
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Many researchers took these features to mean that the (thoroughly ectothermic) modern crocodiles are a relic of the transition from older coldblooded reptiles to endothermic dinosaurs and birds, a point of view that strengthened as paleontologists began accepting the idea of warmblooded dinosaurs.
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Here's a classic example with an OP Roadhog up against four players doing their best to take him down: While some games like the one above allow the fighters to respawn and keep fighting, others only give the fighters one life each to take down the boss, which can make for really interesting dynamics and team compositions focused on stopping the boss with things like Mei's Endothermic Blaster and Ana's Sleep Dart.
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Evaporation is an endothermic process, in that heat is absorbed during evaporation.
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These endothermic insects are better described as regional heterotherms because they are not uniformly endothermic. When heat is being produced, different temperatures are maintained in different parts of their bodies, for example, moths generate heat in their thorax prior to flight but the abdomen remains relatively cool.
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Although hydrogenation is endothermic, this energy can easily be applied by the reaction temperature (about 700 K).
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As an endothermic species, the giant cicada has the ability to live in a wide range of environments.
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As water is heated with starch granules, gelatinization occurs, involving an endothermic reaction. The initiation of gelatinization is called the T-onset. T-peak is the position where the endothermic reaction occurs at the maximum. T-conclusion is when all the starch granules are fully gelatinized and the curve remains stable.
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Calcium ammonium nitrate is hygroscopic. Its dissolution in water is endothermic, leading to its use in some instant cold packs.
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For instance, common endothermic building materials include calcium silicate board, concrete and gypsum wallboard. During fire testing of concrete floor slabs, water can be seen to boil out of a slab. Gypsum wall board typically loses all its strength during a fire. The use of endothermic materials is established and proven to be sound engineering practice.
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The reaction of chromium with molecular hydrogen is endothermic. 380 nm or greater wavelength radiation is required to procure photochemically generated CrH2.
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Since almost all detachments (require +) an amount of energy listed on the table, those detachment reactions are endothermic, or ΔE(detach) > 0. ::.
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The dissolution of calcium nitrate tetrahydrate is highly endothermic (cooling). For this reason, calcium nitrate tetrahydrate is sometimes used for regenerable cold packs.
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When these pairs of components are mixed, the process is endothermic reaction as weaker intermolecular forces are formed so that ΔmixH is positive.
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This process is endothermic, meaning that it absorbs thermal energy from its surroundings, which decreases the temperature of the surroundings, further inhibiting the fire.
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Homeotherms are not necessarily endothermic. Some homeotherms may maintain constant body temperatures through behavioral mechanisms alone, i.e., behavioral thermoregulation. Many reptiles use this strategy.
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Reacting two hydrogen atoms releases 103.3 kcal/mol, and so HgH2 formation from hydrogen molecules and Hg gas is endothermic at 24.2 kcal/mol.
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Sustained energy output of an endothermic animal (mammal) and an ectothermic animal (reptile) as a function of core temperature This image shows the difference between endotherms and ectotherms. The mouse is endothermic and regulates its body temperature through homeostasis. The lizard is ectothermic and its body temperature is dependent on the environment. Many endotherms have a larger number of mitochondria per cell than ectotherms.
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The first reaction, between incandescent coke and steam, is strongly endothermic, producing carbon monoxide (CO), and hydrogen (water gas in older terminology). When the coke bed has cooled to a temperature at which the endothermic reaction can no longer proceed, the steam is then replaced by a blast of air. The second and third reactions then take place, producing an exothermic reaction—forming initially carbon dioxide and raising the temperature of the coke bed—followed by the second endothermic reaction, in which the latter is converted to carbon monoxide, CO. The overall reaction is exothermic, forming "producer gas" (older terminology). Steam can then be re-injected, then air etc.
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However, the respiratory tract participates in osmoregulation through evaporative water loss. Since common ravens are endothermic and have high rates of ventilation, respiratory water loss is inevitable.
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In nonelectrolyte solutions, heat effects are usually endothermic and much smaller, often about 100 calories, when roughly equal parts are mixed to form 100 grams of mixture.
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Typical examples of exothermic reactions are precipitation and crystallization, in which ordered solids are formed from disordered gaseous or liquid phases. In contrast, in endothermic reactions, heat is consumed from the environment. This can occur by increasing the entropy of the system, often through the formation of gaseous reaction products, which have high entropy. Since the entropy increases with temperature, many endothermic reactions preferably take place at high temperatures.
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Whether a reaction can occur spontaneously depends not only on the enthalpy change but also on the entropy change (∆S) and absolute temperature T. If a reaction is a spontaneous process at a certain temperature, the products have a lower Gibbs free energy G = H - TS than the reactants (an exergonic reaction), even if the enthalpy of the products is higher. Thus, an endothermic process usually requires a favorable entropy increase (∆S > 0) in the system that overcomes the unfavorable increase in enthalpy so that still ∆G < 0\. While endothermic phase transitions into more disordered states of higher entropy, e.g. melting and vaporization, are common, spontaneous chemical reactions at moderate temperatures are rarely endothermic.
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Chemical exothermic reactions are generally more spontaneous than their counterparts, endothermic reactions. In a thermochemical reaction that is exothermic, the heat may be listed among the products of the reaction.
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SOEC modules can operate in three different modes: thermoneutral, exothermic and endothermic. In exothermic mode, the stack temperature increases during operation due to heat accumulation, and this heat is used for inlet gas preheating. Therefore, an external heat source is not needed while the electrical energy consumption increases. In the endothermic stack operation mode, there is an increment in heat energy consumption and a reduction in electrical energy consumption and hydrogen production because the average current density also decreases.
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Rescuing the tapinocephalids from a life of diluvian swamp-wallowing, Bakker (1975, 1986) argued that bone histology, geographic distribution, and predator-prey relationships showed that these were active, fully terrestrial and at least partially endothermic animals, midway between the ectothermic pelycosaurs and the fully endothermic theriodonts. Others like McNab and Geist suggest that the tapinocephalids were better considered inertial homeotherms, with the large barrel-like body and short tail being the most efficient surface for conserving heat.
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Restoration showing partial feathering As of 2014, it is not clear if Tyrannosaurus was endothermic (“warm-blooded”). Tyrannosaurus, like most dinosaurs, was long thought to have an ectothermic ("cold-blooded") reptilian metabolism. The idea of dinosaur ectothermy was challenged by scientists like Robert T. Bakker and John Ostrom in the early years of the "Dinosaur Renaissance", beginning in the late 1960s. T. rex itself was claimed to have been endothermic ("warm- blooded"), implying a very active lifestyle.
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Even if Tyrannosaurus rex does exhibit evidence of homeothermy, it does not necessarily mean that it was endothermic. Such thermoregulation may also be explained by gigantothermy, as in some living sea turtles.
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This is thermodynamically an endothermic reaction and creates a viscosity jump. Both characteristics cause this phase transition to play an important role in geodynamical models. Cold downwelling material might pond on this transition.
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During the hibernation season, this animal shows strongly reduced metabolism each day during the rest phase while it reverts to endothermic metabolism during its active phase, leading to normal euthermic body temperatures (around 38 °C). Larger mammals (e.g. ground squirrels) and bats show multi-day torpor bouts during hibernation (up to several weeks) in winter. During these multi-day torpor bouts, body temperature drops to ~1 °C above ambient temperature and metabolism may drop to about 1% of the normal endothermic metabolic rate.
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These considerations, as well as tooth oxygen isotopic data and the need for higher burst swimming speeds in macropredators of endothermic prey than ectothermy would allow, imply that otodontids, including megalodon, were probably regional endotherms.
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After studying saltwater crocodiles, Seymour found that even if their large sizes could provide stable and high body temperatures, during activity the crocodile's ectothermic metabolism provided less aerobic abilities and generate only 14% of the total muscle power of a similar sized endothermic mammal before full fatigue. Seymour reasoned that dinosaurs would have needed to be endothermic since they would have needed better aerobic abilities and higher power generation to compete with and dominate over mammals as active land animals throughout the Mesozoic era.
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Because of historical accident, students encounter a source of possible confusion between the terminology of physics and biology. Whereas the thermodynamic terms "exothermic" and "endothermic" respectively refer to processes that give out heat energy and processes that absorb heat energy, in biology the sense is effectively inverted. The metabolic terms "ectothermic" and "endothermic" respectively refer to organisms that rely largely on external heat to achieve a full working temperature, and to organisms that produce heat from within as a major factor in controlling their bodily temperature.
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The solubility of a given solute in a given solvent is function of temperature. Depending on the change in Gibbs free energy (ΔG) of the dissolution reaction, i.e., on the endothermic (ΔG > 0) or exothermic (ΔG < 0) character of the dissolution reaction, the solubility of a given compound may increase or decrease with temperature. The van 't Hoff equation relates the change of solubility equilibrium constant (Ksp) to temperature change and to reaction enthalpy change (ΔH). For most solids and liquids, their solubility increases with temperature because their dissolution reaction is endothermic (ΔG > 0).
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Because both modern crocodilians and birds have four-chambered hearts (albeit modified in crocodilians), it is likely that this is a trait shared by all archosaurs, including all dinosaurs. While all modern birds have high metabolisms and are "warm-blooded" (endothermic), a vigorous debate has been ongoing since the 1960s regarding how far back in the dinosaur lineage this trait extends. Scientists disagree as to whether non- avian dinosaurs were endothermic, ectothermic, or some combination of both. After non-avian dinosaurs were discovered, paleontologists first posited that they were ectothermic.
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This enables them to generate heat by increasing the rate at which they metabolize fats and sugars. Accordingly, to sustain their higher metabolism, endothermic animals typically require several times as much food as ectothermic animals do, and usually require a more sustained supply of metabolic fuel. In many endothermic animals, a controlled temporary state of hypothermia conserves energy by permitting the body temperature to drop nearly to ambient levels. Such states may be brief, regular circadian cycles called torpor, or they might occur in much longer, even seasonal, cycles called hibernation.
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Small insectivorous mammals eat prodigious amounts for their size. A rare exception, the naked mole-rat produces little metabolic heat, so it is considered an operational poikilotherm. Birds are also endothermic, so endothermy is not unique to mammals.
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The brain regulates endothermic and circulatory system, including a four-chambered heart. Mammals encompass some 5,500 species (including Humans), distributed in about 1,200 genera, 152 families and up to 46 orders, though this varies with the classification scheme.
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Outside Araceae, the sacred lotus (Nelumbo nucifera) is thermogenic and endothermic, able to regulate its flower temperature to a certain range, an ability shared by at least one species in the non- photosynthetic parasitic genus Rhizanthes, Rhizanthes lowii.
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This suggests that Azendohsaurus may then have been ancestrally endothermic. By contrast, the related allokotosaur Trilophosaurus was previously found to not have any fibrolamellar bone tissue in its limb bones and so was inferred to have grown slowly.
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This discontinuity is generally linked to the transition from ringwoodite to bridgmanite and periclase. This is thermodynamically an endothermic reaction and creates a viscosity jump. Both characteristics cause this phase transition to play an important role in geodynamical models.
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Certain lamnid sharks, tuna and billfishes are also endothermic. In common parlance, endotherms are characterized as "warm-blooded". The opposite of endothermy is ectothermy, although in general, there is no absolute or clear separation between the nature of endotherms and ectotherms.
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Faust carried out analyses of the mineral, and found amongst others that in differential thermal analysis huntite showed two endothermic peaks, which could be attributed to the dissociation of MgCO3 and CaCO3 respectively. Chemical analyses showed huntite to consist of Mg3Ca(CO3)4.
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The main reaction in this plant is the conversion of ethylbenzene to styrene. It is a dehydrogenation reaction because two hydrogen atoms are removed from ethylbenzene to give styrene. The reaction is endothermic. The heat to drive this reaction is provided by steam.
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1,3,5-Triazido-2,4,6-trinitrobenzene forms yellow crystalline solids that melt at 131 °C. The crystals are monoclinic with space group P21/c. Its formation is highly endothermic, with an enthalpy of formation of 765.8 kJ/mol and an enthalpy of combustion of 3200 kJ/mol.
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University of Cambridge, Material Science and Metallurgy. www.msm.cam.ac.uk/phase-trans/2002/Thermal1.pdf This differential temperature is then plotted against time, or against temperature (DTA curve, or thermogram). Changes in the sample, either exothermic or endothermic, can be detected relative to the inert reference.
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Brown was the original whistleblower of the Thermo-Lag 330-1 scandal,NRC treatise on the subject which involved an endothermic material manufactured by Thermal Science Inc., also doing business as Nu-Chem, Inc. and later as TS Holdings Inc. of St. Louis, Missouri.
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The basic principle underlying this technique is that when the sample undergoes a physical transformation such as phase transitions, more or less heat will need to flow to it than the reference to maintain both at the same temperature. Whether less or more heat must flow to the sample depends on whether the process is exothermic or endothermic. For example, as a solid sample melts to a liquid, it will require more heat flowing to the sample to increase its temperature at the same rate as the reference. This is due to the absorption of heat by the sample as it undergoes the endothermic phase transition from solid to liquid.
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Consequently, KrF2 is a good source of the extremely reactive and oxidizing atomic fluorine. It is thermally unstable, with a decomposition rate of 10% per hour at room temperature. Krypton difluoride is endothermic, with a heat of formation of 14.4 ± 0.8 kcal/mol measured at 93 °C.
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This expansion occurred in both therocephalians and the related cynodonts, indicating that the two groups were convergently acquiring mammalian characteristics in the Permian and Triassic. Although therocephalians died out by the Middle Triassic, cynodonts continued to diversify, giving rise to fully endothermic mammals in the Late Triassic.
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Nitroethylene is a very electron deficient molecule. As a result, nitroethylene usually acts as the electrophile in reactions. Nitroethylene is capable of reacting spontaneously at temperatures as low as -100 °C, often as endothermic reactions. Common reactions for this molecule are cycloadditions, radical additions, and nucleophilic additions.
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This indicates that some cynodonts had high respiratory rates and therefore endothermic metabolic status as seen in eucynodonts. Therefore, all of the adaptations needed for endothermy could already be present in Triassic cynodonts.Rodrigues, Pablo Gusmão Endotermia em cinodontes não- mamalianos: a busca por evidências osteológicas. / Pablo Gusmão Rodrigues.
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In addition, the differences of the SCN between endothermic and ectothermic vertebrates suggest that the neuronal organization of the temperature-resistant SCN in endotherms is responsible for driving thermoregulatory behaviors in those animals differently from those of ectotherms, since they rely on external temperature for engaging in certain behaviors.
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Dehydrogenation processes are used extensively to produce aromatics in the petrochemical industry. Such processes are highly endothermic and require temperatures of 500 °C and above. Dehydrogenation also converts saturated fats to unsaturated fats. One of the largest scale dehydrogenation reactions is the production of styrene by dehydrogenation of ethylbenzene.
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The chemically bound water inside these materials sublimes. During this process, the unexposed side cannot exceed the boiling point of water. Once the hydrates are spent, the temperature on the unexposed side of an endothermic fire barrier tends to rise rapidly. Too much water can be a problem, however.
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This can be a concern when raw materials have high economic costs or environmental costs in extraction. In addition, increasing the temperature can also increase the yield of some endothermic reactions, but at the expense of consuming more energy. Hence this may not be attractive methods as well.
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Both processes are endothermic and are driven towards the alkene at high temperatures by entropy. Catalytic synthesis of higher α-alkenes (of the type RCH=CH2) can also be achieved by a reaction of ethylene with the organometallic compound triethylaluminium in the presence of nickel, cobalt, or platinum.
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Homeothermy and poikilothermy refer to how stable an organism's deep-body temperature is. Most endothermic organisms are homeothermic, like mammals. However, animals with facultative endothermy are often poikilothermic, meaning their temperature can vary considerably. Most fish are ectotherms, as most of their heat comes from the surrounding water.
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Retrieved 14 May 2015. This is different from "warm blooded" in the sense of birds and mammals and is not the first fish discovered with this ability. It may be the most completely endothermic fish. Other species of fish also possess this ability, such as tuna and some sharks.
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Bothrops asper is a diet generalist and is known to prey on a remarkably wide range of animals. A generalized ontogenetic diet shift occurs, with a higher percentage of ectothermic prey in juveniles, changing to a greater percentage of endothermic prey in adults, particularly small mammals. However both juveniles and adults, regardless of size or age, are known to opportunistically prey on ectothermic and endothermic species. Reports of invertebrate and insect remains in the digestive tracts along with frog and lizard remains are believed to represent secondary ingestion, however the dissection of several specimens containing only insect remains such as beetles (Coleoptera), and bugs (Hemiptera) are believed to reflect insects as primary prey too.
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After converting part of this energy to work, the heat engine rejects the remaining energy as heat. Almost all of this heat rejection can be absorbed by the endothermic reduction reaction occurring in the reducer. This arrangement requires the redox reactions to be exothermic and endothermic respectively, but this is normally the case for most metals. Some additional heat exchange with the environment is required to satisfy the second law; theoretically, for a reversible process, the heat exchange is related to the standard state entropy change, ΔSo, of the primary hydrocarbon oxidation reaction as follows: :Qo = ToΔSo However, for most hydrocarbons, ΔSo is a small value and, as a result, an engine of high overall efficiency is theoretically possible.
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Iron powder Most, if not all, metals can be sintered. This applies especially to pure metals produced in vacuum which suffer no surface contamination. Sintering under atmospheric pressure requires the use of a protective gas, quite often endothermic gas. Sintering, with subsequent reworking, can produce a great range of material properties.
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From the storage hoppers, the green beans are conveyed to the roaster. Initially, the process is endothermic (absorbing heat), but at around it becomes exothermic (giving off heat).Raemy A, Lambelet P. A calorimetric study of self-heating in coffee and chicory. Int J Food Sci & Tech, 1982;17(4):451–460.
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McGraw-Hill, 2002, Reactions of barium hydroxide with ammonium salts are strongly endothermic. The reaction of barium hydroxide octahydrate with ammonium chlorideEndothermic Solid-Solid Reactions or ammonium thiocyanate is often used as a classroom chemistry demonstration, producing temperatures cold enough to freeze water and enough water to dissolve the resulting mixture.
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Part of a wing. Albrecht Dürer, c. 1500–1512 Birds are tetrapods but though their hind limbs are used for walking or hopping, their front limbs are wings covered with feathers and adapted for flight. Birds are endothermic, have a high metabolic rate, a light skeletal system and powerful muscles.
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Tianyulong from China appears to preserve filamentous integument which has been interpreted to be a variant of the proto-feathers found in some theropods. These filaments include a crest along its tail. The presence of this filamentous integument has been used to suggest that both ornithischians and saurischians were endothermic.
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Steller sea lion with white sturgeon All pinnipeds are carnivorous and predatory. As a whole, they mostly feed on fish and cephalopods, followed by crustaceans and bivalves, and then zooplankton and endothermic ("warm-blooded") prey like sea birds.Riedman, pp. 144–145. While most species are generalist and opportunistic feeders, a few are specialists.
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Dissociation is an endothermic process, hence reducing the amount of energy released in a detonation or the maximum amount of work that can be obtained from the FJ cycle. Exothermic reactions are encouraged when increasing the initial pressure of the system, hence, increasing the amount of work generated during the FJ cycle.
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Many experts believe that the processes of daily torpor and hibernation form a continuum and utilize similar mechanisms. The equivalent during the summer months is aestivation. Hibernation functions to conserve energy when sufficient food is unavailable. To achieve this energy saving, an endothermic animal decreases its metabolic rate and thereby its body temperature.
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Around 80% of styrene is produced by the dehydrogenation of ethylbenzene. This is achieved using superheated steam (up to 600 °C) over an iron(III) oxide catalyst. The reaction is highly endothermic and reversible, with a typical yield of 88–94%. :500px The crude ethylbenzene/styrene product is then purified by distillation.
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Paul (1988a), p. 122–123, 211 Robert T. Bakker's The Dinosaur Heresies (1986) accurately predicted the presence of feathers on dromaeosaurids and contended that all dinosaurs were endothermic, yet did not incorporate feathers in its illustration of Ornitholestes.Bakker (1986), p. 99, 310 In 1996, the primitive coelurosaur Sinosauropteryx was discovered in China.
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At room temperatures, has a high vapor pressure, making it useful in the gaseous diffusion process to separate the rare uranium-235 from the common uranium-238 isotope. This compound can be prepared from uranium dioxide and uranium hydride by the following process: : + 4 HF → + 2 (500 °C, endothermic) : + → (350 °C, endothermic) The resulting , a white solid, is highly reactive (by fluorination), easily sublimes (emitting a vapor that behaves as a nearly ideal gas), and is the most volatile compound of uranium known to exist. One method of preparing uranium tetrachloride () is to directly combine chlorine with either uranium metal or uranium hydride. The reduction of by hydrogen produces uranium trichloride () while the higher chlorides of uranium are prepared by reaction with additional chlorine.
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In Robert L. Forward's science fiction novel Camelot 30K, oxygen difluoride was used as a biochemical solvent by fictional life forms living in the solar system's Kuiper belt. While would be a solid at 30 K, the fictional alien lifeforms were described as endothermic, maintaining elevated body temperatures and liquid blood by radiothermal heating.
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Animal records. New York: Sterling The Java mouse-deer is endothermic and homoeothermic, and has an average basal metabolic rate of about 4.883 watts. It also has the smallest red blood cells (erythrocytes) of any mammal, and about 12.8% of the cells have pits on them. The pits range in diameter from 68 to 390 nanometres.
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Nearly all mammals are endothermic ("warm-blooded"). Most mammals also have hair to help keep them warm. Like birds, mammals can forage or hunt in weather and climates too cold for ectothermic ("cold-blooded") reptiles and insects. Endothermy requires plenty of food energy, so mammals eat more food per unit of body weight than most reptiles.
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For example: :Fe2O3 \+ 6 HCl Fe2Cl6\+ 3 H2O ΔHrxn > 0 (endothermic) The sample of iron(III) oxide is maintained at 1000 °C, and the product is grown at 750 °C. HCl is the transport agent. Crystals of hematite are reportedly observed at the mouths of volcanoes because of chemical transport reactions whereby volcanic hydrogen chloride volatilizes iron(III) oxides.
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Marine otters mainly feed on crustaceans and fish. Pinnipeds mostly feed on fish and cephalopods, followed by crustaceans and bivalves, and then zooplankton and warm-blooded prey (like sea birds). Most species are generalist feeders, but a few are specialists. They typically hunt non-schooling fish, slow-moving or immobile invertebrates or endothermic prey when in groups.
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Steam reforming is a hydrogen production process from natural gas. This method is currently the cheapest source of hydrogen. The process consists of heating the gas to between 700–1100 °C in the presence of steam and a nickel catalyst. The resulting endothermic reaction breaks up the methane molecules and forms carbon monoxide CO and hydrogen H2.
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Adjusting dinosaur rates upwards by a factor of two, D'Emic found dinosaurs to grow similarly to mammals, and thus were likely endothermic. However, sensitivity to seasonal variation in resources should be true for all vertebrates. If all vertebrate taxa were similarly adjusted, the relative differences in rates does not change. Dinosaurs remain intermediate growers and good candidates for mesothermy.
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Glanosuchus may have been one of the first therapsids to achieve endothermy, or warm-bloodedness. Endothermy is seen today in mammals, the only living group of therapsids. Reptiles, the closest living relatives of mammals, are cold-blooded ectotherms with lower metabolic rates. Endothermic animals likely evolved from more primitive ectothermic synapsids sometime in the Permian or Triassic.
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The molarity of lithium sulfate also plays a role in the electrical conductivity; optimal conductivity is achieved at 2M and then decreases.Angel C.; Sobron F.; Jose I. Density, Viscosity, and Electrical Conductivity of Aqueous Solutions of Lithium Sulfate. J. Chem. Eng. 1995, 40, 987-991 When solid lithium sulfate is dissolved in water it has an endothermic disassociation.
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But bony fish that breathe through their skin or lungs evolved into living vertebrates, and are more closely related to terrestrial vertebrates than to sharks and other cartilaginous fish. Another example is thermo-regulation in reptilia and birds. Reptilia are ectothermic (coldblooded) and birds are endothermic (warmblooded). This is plesiomorphic for birds and plesiomorphic for reptiles.
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However consider another example: in the contact process for the production of sulfuric acid, the second stage is a reversible reaction: :2SO2(g) + O2(g) ⇌ 2SO3(g) The forward reaction is exothermic and the reverse reaction is endothermic. Viewed by Le Chatelier's principle a larger amount of thermal energy in the system would favor the endothermic reverse reaction, as this would absorb the increased energy; in other words the equilibrium would shift to the reactants in order to remove the stress of added heat. For similar reasons, lower temperatures would favor the exothermic forward reaction, and produce more products. This works in this case, since due to loss of entropy the reaction becomes less exothermic as temperature increases; however reactions that become more exothermic as temperature increases would seem to violate this principle.
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Useful reactions of this diene are cycloadditions, such as the Diels-Alder reaction.Sanjeeva Rao Guppi, George A. O'Doherty, "1,3-Cyclohexadiene" Encyclopedia of Reagents for Organic Synthesis, 2008 John Wiley & Sons. Conversion of cyclohexa-1,3-diene to benzene + hydrogen is exothermic by about 25 kJ/mol in the gas phase.US National Institute of Standards and Technology, NIST Chemistry WebBook 1,3-Cyclohexadiene BenzeneJ. Sherman The heats of hydrogenation of unsaturated hydrocarbons Journal of the American Oil Chemists' Society; Volume 16, Number 2 / February, 1939 :cyclohexane → cyclohexa-1,3-diene + 2 H2 (ΔH = +231.5 kJ/mol; endothermic) :cyclohexane → benzene + 3 H2 (ΔH = +205 kJ/mol; endothermic) :cyclohexa-1,3-diene → benzene + H2 (ΔH = -26.5 kJ/mol; exothermic) Compared with its isomer cyclohexa-1,4-diene, cyclohexa-1,3-diene is about 1.6 kJ/mol more stable.
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Steam reforming or steam methane reforming is a method for producing syngas (hydrogen and carbon monoxide) by reaction of hydrocarbons with water. Commonly natural gas is the feedstock. The main purpose of this technology is hydrogen production. The reaction is represented by this equilibrium: :CH4 \+ H2O ⇌ CO + 3 H2 The reaction is strongly endothermic (consumes heat, ΔHr= 206 kJ/mol).
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Vancleavea and Euparkeria, which show slower growth rates compared to Erythrosuchus, lived after the climatic stabilization. Early crown archosaurs possessed increased growth rates, which were retained by ornithodirans. Ornithosuchians and poposaurs are stem- crocodilians that show high growth rates similar to those of basal archosauriforms. Developmental, physiological, anatomical and palaeontological lines of evidence indicate that crocodilians evolved from endothermic ancestors.
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Bergmann's rule establishes that among endothermic animals of the same species, body size increases with latitude. Studies have tested whether this rule also applies to social insects. L. acervorum workers were counted in a sample of colonies from Erlangen and Karelia. The worker size was significantly larger in the Karelian population, with the average thorax length being 1.15 mm ± 0.07 mm.
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Schematic potential energy diagram showing the effect of a catalyst in an endothermic chemical reaction. The presence of a catalyst opens a different reaction pathway (in red) with a lower activation energy. The final result and the overall thermodynamics are the same. Solid heterogeneous catalysts are plated on meshes in ceramic catalytic converters in order to maximize their surface area.
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See pages 137–8 of Society, Cornell (1907). In statistical mechanics, temperature is the measure of the average kinetic energy stored in a particle. The methods of storing this energy are dictated by the degrees of freedom of the particle itself (energy modes). Kinetic energy added (endothermic process) to gas particles by way of collisions produces linear, rotational, and vibrational motion.
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It has been suggested that eager would be a more intuitive term in this context. More generally, the terms exergonic and endergonic relate to the free energy change in any process, not just chemical reactions. By contrast, the terms exothermic and endothermic relate to an enthalpy change in a closed system during a process, usually associated with the exchange of heat.
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Endothermic gas is a gas that inhibits or reverses oxidation on the surfaces it is in contact with. This gas is the product of incomplete combustion in a controlled environment. An example is hydrogen gas (H2), nitrogen gas (N2), and carbon monoxide (CO). The hydrogen and carbon monoxide are reducing agents, so they work together to shield surfaces from oxidation.
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Compared with its sister species, the Palawan stink badger is also slightly smaller, with larger teeth and longer fur. Females have six teats. Like all members of the mammalia class, the Palawan stink badgers are endothermic, wherein they use metabolically generated heat to regulate body temperature independently of ambient temperature. Another interesting physical feature, is that they are bilaterally symmetric.
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Glanosuchus is a genus of scylacosaurid therocephalian from the Late Permian of South Africa. The type species G. macrops was named by Robert Broom in 1904. Glanosuchus had a middle ear structure that was intermediate between that of early therapsids and mammals. Ridges in the nasal cavity of Glanosuchus suggest it had an at least partially endothermic metabolism similar to modern mammals.
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Combined reforming is a combination of partial oxidation and steam reforming and is the last reaction that is used for hydrogen production. The general equation is given below: and are the stoichiometric coefficients for steam reforming and partial oxidation, respectively. The reaction can be both endothermic and exothermic determined by the conditions, and combine both the advantages of steam reforming and partial oxidation.
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Generic potential energy diagram showing the effect of a catalyst in a hypothetical endothermic chemical reaction. The presence of the catalyst opens a new reaction pathway (shown in red) with a lower activation energy. The final result and the overall thermodynamics are the same. A catalyst is a substance that alters the rate of a chemical reaction but it remains chemically unchanged afterwards.
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This exits the furnace and passes through cooling drums before being milled, screened and sent to product storage facilities. The process involves intermediate formation of sodium bisulfate, an exothermic reaction that occur at room temperature: :NaCl + H2SO4 → HCl + NaHSO4 The second step of the process is endothermic, requiring energy input: :NaCl + NaHSO4 → HCl + Na2SO4 Temperatures in the range 600-700 °C are required.
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Ornithischian dinosaurs also showed evidence of homeothermy, while varanid lizards from the same formation did not. Even if T. rex does exhibit evidence of homeothermy, it does not necessarily mean that it was endothermic. Such thermoregulation may also be explained by gigantothermy, as in some living sea turtles. Similar to contemporary alligators, dorsotemporal fenestra in Tyrannosaurus's skull may have aided thermoregulation.
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About 700 living species of cephalopods have been identified. The nervous system of cephalopods is the most complex of all the invertebrates and their brain-to-body-mass ratio falls between that of endothermic and ectothermic vertebrates. The brain is protected in a cartilaginous cranium. The possibility that non-human animals may be capable of perceiving pain has a long history.
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In water solution, the indium ion forms a complex with water and sulfate, examples being In(H2O)5(SO4)+ and In(H2O)4(SO4)2−. Indium is unusual in forming a sulfate complex. The effect on the sulfate ion is revealed in the Raman spectrum. The proportion of sulfate complex increases with temperature showing the reaction that forms it is endothermic.
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The benefit of a low resting metabolism is that it requires far less fuel to sustain bodily functions. By using temperature variations in their surroundings, or by remaining cold when they do not need to move, reptiles can save considerable amounts of energy compared to endothermic animals of the same size.Campbell, N.A. & Reece, J.B. (2006): Outlines & Highlights for Essential Biology. Academic Internet Publishers.
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It dissolves in water to give a mildly alkaline solution. It is insoluble in acetone and alcohols. Ammonium bicarbonate decomposes above about 36 °C into ammonia, carbon dioxide, and water in an endothermic process and so causes a drop in the temperature of the water: :NH4HCO3 → NH3 \+ H2O + CO2. When treated with acids, ammonium salts are also produced: :NH4HCO3 \+ HCl → NH4Cl + CO2 \+ H2O.
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Most bony fishes are ectothermic, or cold-blooded, but this species, much like the related tunas, is endothermic and is able to raise its body temperature to achieve a degree of thermoregulation. It has a brain heater organ derived from the lateral rectus eye muscle, which is distinct from that of the billfishes, whose heater is derived from their superior rectus muscles.
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Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion or other chemical reactions.
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An oasis contains moisture from a water source and/or plants. When that water evaporates or transpirates, heat from the surroundings is used to convert liquid to gas in an endothermic reaction, which results in cooler local temperatures. Moreover, vegetation has a higher albedo than bare ground, and reflects more sunlight, leading to lower land temperatures, lower air temperatures, and a cooler local microclimate.
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Traditionally, acetaldehyde was produced by the partial dehydrogenation of ethanol: : CH3CH2OH → CH3CHO + H2 In this endothermic process, ethanol vapor is passed at 260–290 °C over a copper-based catalyst. The process was once attractive because of the value of the hydrogen coproduct,Eckert, Marc et al. (2007) "Acetaldehyde" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. but in modern times is not economically viable.
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Guerrini debuted as a driver in the FIA Alternative Energies Cup, reserved for hybrid and endothermic vehicles, in 2009, together with co-driver Andrea Gnaldi Coleschi. Brillante Performance delle auto di Sansepolcro all'Ecorally San Marino-Vaticano. ArezzoNotizie, 2009-09-21. In 2010, Guerrini obtained 3rd place in the Italian championship standings and 5th place in the world championship won by the French driver Raymond Durand.
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Endothermic bony fishes are all in the suborder Scombroidei and include the butterfly mackerel, a species of primitive mackerel. Mackerel are strong swimmers. Atlantic mackerel can swim at a sustained speed of 0.98 m/sec with a burst speed of 5.5 m/sec, while chub mackerel can swim at a sustained speed of 0.92 m/sec with a burst speed of 2.25 m/sec.
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The purpose is to control heat below the critical level. To achieve this, one can create an endothermic environment, produce non- combustible products, or add chemicals that would remove fire-propagating radicals (H and OH), to name a few. These specific chemicals can be added into the polymer molecules permanently (see Intrinsically Fire-Resistant Polymers) or as additives and fillers (see Flame-Retardant Additives and Fillers).
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However, objections have been raised against this argument. Nasal turbinates are absent or very small in some birds, such as ratites, Procellariiformes and Falconiformes. They are also absent or very small in some mammals, such as anteaters, bats, elephants, whales and most primates, although these animals are fully endothermic and in some cases very active. Furthermore, ossified turbinate bones have been identified in the ankylosaurid dinosaur Saichania.
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This implies that the reaction is exothermic. The converse is also true; the standard enthalpy of reaction is positive for an endothermic reaction. This calculation has a tacit assumption of ideal solution between reactants and products where the enthalpy of mixing is zero. For example, for the combustion of methane, CH4 \+ 2 O2 → CO2 \+ 2 H2O: :ΔrH⦵ = [ΔfH⦵(CO2) + 2 ΔfH⦵(H2O)] − [ΔfH⦵(CH4) + 2 ΔfH⦵(O2)].
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Radiofrequency ablation (RFA) is used when a patient has relatively few metastases. In RFA, a needle is inserted into the center of the lesion and current is applied to generate heat; the tumor cells are killed by cooking. Cryoablation is similar to RFA; an endothermic substance is injected into the tumors to kill by freezing. Cryoablation has been less successful for GEP-NETs than RFA.
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Common mole-rats are endothermic, having the ability to generate their own heat and keep their body temperature above ambient temperature. In arid environments they have lower individual body masses; this reduces their need for food and improves energy conservation. These mole-rats also have long sensory hairs called vibrissae that stand out from the pelage (fur covering) over their body and hind legs.
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Additionally, an erect posture demands precise balance, the result of a rapidly functioning neuromuscular system. This suggests endothermic metabolism, because an ectothermic animal would be unable to walk or run, and thus to evade predators, when its core temperature was lowered. Other evidence for endothermy includes limb length (many dinosaurs possessed comparatively long limbs) and bipedalism, both found today only in endotherms.Fastovsky & Weishampel 2009, p.251.
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This transition from amorphous solid to crystalline solid is an exothermic process, and results in a peak in the DSC signal. As the temperature increases the sample eventually reaches its melting temperature (Tm). The melting process results in an endothermic peak in the DSC curve. The ability to determine transition temperatures and enthalpies makes DSC a valuable tool in producing phase diagrams for various chemical systems.
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Public Library of Science Pathogens 1: 38. It was also predicted that since Griphobilharzia amoena originated in ectotherms and then inhabited endothermic avian species, which is where they exist today. Brant and Loker used endothermy as a key factor in the diversification of schistosomes. However, upon analysis it was discovered that Griphobilharzia amoena is actually more closely related to spirorchiids from freshwater turtles rather than to schistosomes.
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Although it is not a nitrogen hydride, hydroxylamine (NH2OH) is similar in properties and structure to ammonia and hydrazine as well. Hydrazine is a fuming, colourless liquid that smells similarly to ammonia. Its physical properties are very similar to those of water (melting point 2.0 °C, boiling point 113.5 °C, density 1.00 g/cm3). Despite it being an endothermic compound, it is kinetically stable.
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From another point of view, sit-and-wait predation may require very long periods of unproductive waiting. Endotherms cannot, in general, afford such long periods without food, but suitably adapted ectotherms can wait without expending much energy. Endothermic vertebrate species are therefore less dependent on the environmental conditions and have developed a higher variability (both within and between species) in their daily patterns of activity.
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They naturally had a metabolism that was partially or completely endothermic. They were thought to be driven out by relatives such as mammals competing for the same ecological niches. Another reason that this animal could have gone extinct was due to new plant development. Some flowering plants, or angiosperms, could have been detrimental to these animals since they may not have been used to eating new plants.
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In general, the reaction is exothermic, but, e.g., the formation of mercuric oxide (HgO) is endothermic. The charge of the resulting ions is a major factor in the strength of ionic bonding, e.g. a salt C+A− is held together by electrostatic forces roughly four times weaker than C2+A2− according to Coulombs law, where C and A represent a generic cation and anion respectively.
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A consensus of paleontologists agrees that birds evolved from theropod dinosaurs. The scenario for this hypothesis is that early theropod dinosaurs were endothermic, and evolved simple filamentous feathers for insulation. These feathers later increased in size and complexity and then adapted to aerodynamic uses. Ample evidence for this hypothesis has been found in the fossil record, specifically for such dinosaurs as Kulindadromeus, Sinosauropteryx, Caudipteryx, Microraptor and many others.
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Another anomaly is found in the solubility of residual H2S in liquid sulfur as a function of temperature. Ordinarily the solubility of a gas decreases with increasing temperature but with H2S it is the opposite. This means that toxic and explosive H2S gas can build up in the headspace of any cooling liquid sulfur reservoir. The explanation for this anomaly is the endothermic reaction of sulfur with H2S to polysulfanes H2Sx.
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A fossil of Casineria, which may have been the earliest amniote. Reptiles arose about 310–320 million years ago during the Carboniferous period. Reptiles, in the traditional sense of the term, are defined as animals that have scales or scutes, lay land-based hard-shelled eggs, and possess ectothermic metabolisms. So defined, the group is paraphyletic, excluding endothermic animals like birds and mammals that are descended from early reptiles.
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The large differences among endothermic (warm-blooded) mammalian and ectothermic (cold-blooded) teleost leptins raised the question of whether the energy homeostatic functions of the teleost leptins are conserved. Initial phylogenetic analysis has revealed that amino acid conservation with other vertebrate Lep orthologues is low, with only 13.2% sequence identity between torafugu and human LEP. Subsequent investigations have confirmed the low amino acid identity of teleost leps compared to mammalian LEP.
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Power: devoted to the generation and transmission of power, Volume 26 1906 p.685-688 Available from Google books. The Lowe process is endothermic, and cools the generator and checker work, so the process has to alternate between air blast for heating and steam blast for gas production. The process spurred on the industry of gas manufacturing, and gasification plants were established quickly along the Eastern seaboard of the United States.
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More recently, the discovery of hair remnants in Permian coprolites possibly vindicates the status of dicynodonts as endothermic animals. As these coprolites come from carnivorous species and digested dicynodont bones are abundant, it has been suggested that at least some of these hair remnants come from dicynodont prey. A new chemical study seemed to suggest that cynodonts and dicynodonts both developed warm blood independently before the Permian extinction using chemical analysis.
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In addition to their sweetness, some sugar alcohols can produce a noticeable cooling sensation in the mouth when highly concentrated, for instance in sugar-free hard candy or chewing gum. This happens, for example, with the crystalline phase of sorbitol, erythritol, xylitol, mannitol, lactitol and maltitol. The cooling sensation is due to the dissolution of the sugar alcohol being an endothermic (heat- absorbing) reaction, one with a strong heat of solution.
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Dicynodonts, including Eosimops, have been suspected for some time to be endothermic. In a histological study of the closely related Diictodon, another pylaecephalid, rapid bone growth is shown to be part of their early ontogeny. Continued growth during adult stages was also observed. This rapid growth as well as moderately vascularized bones suggests that Diictodon could have been an endotherm, and that Eosimops could have been as well.
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Gaseous solutes exhibit more complex behavior with temperature. As the temperature is raised, gases usually become less soluble in water (exothermic dissolution reaction related to their hydration) (to minimum, which is below 120 °C for most permanent gases), but more soluble in organic solvents (endothermic dissolution reaction related to their solvatation). The chart shows solubility curves for some typical solid inorganic salts (temperature is in degrees Celsius i.e. kelvins minus 273.15).
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Chain branching is an additional positive feedback mechanism which may also cause temperature to skyrocket because of rapidly increasing reaction rate. Chemical reactions are either endothermic or exothermic, as expressed by their change in enthalpy. Many reactions are highly exothermic, so many industrial-scale and oil refinery processes have some level of risk of thermal runaway. These include hydrocracking, hydrogenation, alkylation (SN2), oxidation, metalation and nucleophilic aromatic substitution.
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Pycnofibers grew in several forms, from simple filaments to branching down feathers. These are possibly homologous to the down feathers found on both avian and some non-avian dinosaurs, suggesting that early feathers evolved in the common ancestor of pterosaurs and dinosaurs, possibly as insulation. In life, pterosaurs would have had smooth or fluffy coats that did not resemble bird feathers. They were warm-blooded (endothermic) active animals.
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Since the 1990s, pterosaur finds and histological and ultraviolet examination of pterosaur specimens have provided incontrovertible proof: pterosaurs had pycnofiber coats. Sordes pilosus (which translates as "hairy demon") and Jeholopterus ninchengensis show pycnofibers on the head and body. Jeholopterus The presence of pycnofibers strongly indicates that pterosaurs were endothermic (warm- blooded). They aided thermoregulation, as is common in warm-blooded animals who need insulation to prevent excessive heat-loss.
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The chemical composition of syngas varies based on the raw materials and the processes. Syngas produced by coal gasification generally is a mixture of 30 to 60% carbon monoxide, 25 to 30% hydrogen, 5 to 15% carbon dioxide, and 0 to 5% methane. It also contains lesser amount of other gases. The main reaction that produces syngas, steam reforming, is an endothermic reaction with 206 kJ/mol methane needed for conversion.
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The invading strand is a sequence of single-stranded DNA (ssDNA) which is complementary to the original strand . The toehold regions initiate the process of TMSD by allowing the complementary invading strand to hybridize with the original strand, creating a DNA complex composed of three strands of DNA . This initial endothermic step is rate limiting and can be tuned by varying the strength (length and sequence composition e.g.
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In the canonical ensemble, amount of substance (N), volume (V) and temperature (T) are conserved. It is also sometimes called constant temperature molecular dynamics (CTMD). In NVT, the energy of endothermic and exothermic processes is exchanged with a thermostat. A variety of thermostat algorithms are available to add and remove energy from the boundaries of an MD simulation in a more or less realistic way, approximating the canonical ensemble.
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A fusion process that produces nuclei lighter than iron-56 or nickel-62 will generally release energy. These elements have relatively small mass per nucleon and large binding energy per nucleon. Fusion of nuclei lighter than these releases energy (an exothermic process), while fusion of heavier nuclei results in energy retained by the product nucleons, and the resulting reaction is endothermic. The opposite is true for the reverse process, nuclear fission.
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These animals, due to lack of appendages, use their bodies to generate propulsive force. These movements are sometimes referred to as "slithering" or "crawling", although neither are formally used in the scientific literature and the latter term is also used for some animals moving on all four limbs. All limbless animals come from cold-blooded groups; there are no endothermic limbless animals, i.e. there are no limbless birds or mammals.
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Speakman, J.R. and Krol, E (2010) Maximal heat dissipation capacity and hyperthermia risk: neglected key factors in the ecology of endotherms Journal of Animal Ecology 79: 726-746 The idea is claimed to have wide implications for our understanding of many aspects of ecophysiology and ecology – such as limits on range distributions, maximum possible sizes of endothermic animals e.g. dinosaurs, Bergmann’s rule, effects of climate change etc.Gremillet et a.
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House sparrow, Passer domesticus The following outline is provided as an overview of and topical guide to birds: Birds (class Aves) – winged, bipedal, endothermic (warm-blooded), egg-laying, vertebrate animals. There are around 10,000 living species, making them the most varied of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic, to the Antarctic. Extant birds range in size from the bee hummingbird to the ostrich.
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At low operating temperature of CFBG, a longer residence time of solid can be achieved leading to a higher gasification yield.The Importance of Fluidized Bed Gasification Technology, Robert Giglio and Mani Seshamani,2011, The Importance of Fluidized Bed Gasification Technology, pp. 1–9 CFBG process is more energy efficient as it is an endothermic process. Only the required heat will be generated to maintain the process at the optimum temperature.
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For both herbivores and carnivores, island size, the degree of island isolation and the size of the ancestral continental species appear not to be of major direct importance to the degree of dwarfing. However, when considering only the body masses of recent top herbivores and carnivores, and including data from both continental and island land masses, the body masses of the largest species in a land mass were found to scale to the size of the land mass, with slopes of about 0.5 log(body mass/kg) per log(land area/km2). There were separate regression lines for endothermic top predators, ectothermic top predators, endothermic top herbivores and (on the basis of limited data) ectothermic top herbivores, such that food intake was 7 to 24-fold higher for top herbivores than for top predators, and about the same for endotherms and ectotherms of the same trophic level (this leads to ectotherms being 5 to 16 times heavier than corresponding endotherms).
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Black-bellied fruit bats are endothermic but are poor thermoregulators. Ambient temperature plays a role in determining their body temperature. They are thermally neutral from 28 to 33 degrees Celsius, from 28 to 16 degrees Celsius the bats body temperature drops about 3 degrees and oxygen consumption increases by 2 cm^3/(g.hr). They have a basal rate metabolism of only 74% of what is expected for a mammal of its size.
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Silver nitride is an explosive chemical compound with symbol Ag3N. It is a black, metallic-looking solid which is formed when silver oxide or silver nitrate, is dissolved in concentrated solutions of ammonia, causing formation of the diammine silver complex which subsequently breaks down to Ag3N. The standard free energy of the compound is about +315 kJ/mol, making it an endothermic compound which decomposes explosively to metallic silver and nitrogen gas.
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The gaseous mixture is introduced in a scrubber and treated with an ammonia solution (producing ammonium cyanide) allowing the other gaseous components: H2, CH4, and N2 to pass through. In a second step the HCN is released by acidification of the solution, followed by a final distillation of the hydrogen cyanide. Because of the highly endothermic reaction, the BMA process is of lower importance for the production of HCN compared to the Andrussow process.
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The temperature change for the titration of very weak acids such as oleic acid by 0.1 mol/L KOH in propan-2-ol is too small to yield an accurate endpoint. In this procedure, a small amount of paraformaldehyde as a fine powder is added to the titrand before the titration. At the endpoint, the first excess of hydroxyl ions catalyzes the depolymerization of paraformaldehyde. The reaction is strongly endothermic and yields a sharp inflection.
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A fire retardant is a substance that is used to slow down or stop the spread of fire or reduce its intensity. This is commonly accomplished by chemical reactions that reduce the flammability of fuels or delay their combustion.Coford Glossary "Fire Retardant" Fire retardants may also cool the fuel through physical action or endothermic chemical reactions. Fire retardants are available as powder, to be mixed with water, as fire-fighting foams and fire-retardant gels.
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At this flow rate, about 40 ml of O2 is brought to the chamber and the entire volume of air in the chamber is exchanged within 5 minutes. For other smaller animals, chamber volumes can be much smaller and flow rates would be adjusted down as well. Note that for warm-blooded or endothermic animals (birds and mammals), chamber sizes and or flow rates would be selected to accommodate their higher metabolic rates.
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The high temperature of annealing may result in oxidation of the metal's surface, resulting in scale. If scale must be avoided, annealing is carried out in a special atmosphere, such as with endothermic gas (a mixture of carbon monoxide, hydrogen gas, and nitrogen gas). Annealing is also done in forming gas, a mixture of hydrogen and nitrogen. The magnetic properties of mu-metal (Espey cores) are introduced by annealing the alloy in a hydrogen atmosphere.
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With a wide liquid range between -39 °C (melting point) and 390 °C (boiling point) and a hydrogen storage density of 6.2 wt% dibenzyltoluene is ideally suited as LOHC material. Formic acid has been suggested as a promising hydrogen storage material with a 4.4wt% hydrogen capacity. Cycloalkanes reported as LOHC include cyclohexane, methyl- cyclohexane and decalin. The dehydrogenation of cycloalkanes is highly endothermic (63-69 kJ/mol H2), which means this process requires high temperature.
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S4N4 is stable to air. It is, however, unstable in the thermodynamic sense with a positive enthalpy of formation of +460 kJ mol−1. This endothermic enthalpy of formation originates in the difference in energy of S4N4 compared to its highly stable decomposition products: :2 S4N4 → 4 N2 \+ S8 Because one of its decomposition products is a gas, S4N4 can be used as an explosive. Purer samples tend to be more explosive.
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They are capable of considerable speed, due to a highly streamlined body and retractable fins. Some members of the family, in particular the tunas, are notable for being partially endothermic (warm-blooded), a feature that also helps them to maintain high speed and activity. Other adaptations include a large amount of red muscle, allowing them to maintain activity over long periods. Scombrids like the yellowfin tuna can reach speeds of 22 km/hr (14 mph).
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One of the very few known endothermic sharks, it is seldom found in waters colder than 16 °C (61 °F). In the western Atlantic, it can be found from Argentina and the Gulf of Mexico to Browns Bank off of Nova Scotia. In Canadian waters, these sharks are neither abundant nor rare. Swordfish are good indicators of shortfin mako populations, as the former are a source of food and prefer similar environmental conditions.
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Carbon fixation is an endothermic redox reaction. In general outline, photosynthesis is the opposite of cellular respiration: while photosynthesis is a process of reduction of carbon dioxide to carbohydrate, cellular respiration is the oxidation of carbohydrate or other nutrients to carbon dioxide. Nutrients used in cellular respiration include carbohydrates, amino acids and fatty acids. These nutrients are oxidized to produce carbon dioxide and water, and to release chemical energy to drive the organism's metabolism.
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The sign convention is the same as for enthalpy of reaction: when the enthalpy of mixing is positive, mixing is endothermic while negative enthalpy of mixing signifies exothermic mixing. In ideal mixtures the enthalpy of mixing is null. In non-ideal mixtures the thermodynamic activity of each component is different from its concentration by multiplying with the activity coefficient. One approximation for calculating the heat of mixing is Flory–Huggins solution theory for polymer solutions.
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It may then have been one of the first herbivores to fill the high-browsing role that only large sauropodomorphs were thought to occupy during the Triassic, expanding the known ecological diversity of herbivorous archosauromorphs outside of dinosaurs in the Triassic Period. Azendohsaurus is also significant as it may be one of the earliest endothermic archosauromorphs known, and suggests that a warm-blooded metabolism was ancestral to the later archosaurs, including the dinosaurs.
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A class of endothermic organisms known as homeotherms maintain internal temperatures with minimal metabolic regulation within a range of ambient temperatures called the thermal neutral zone (TNZ). Within the TNZ the basal rate of heat production is equal to the rate of heat loss to the environment. Homeothermic organisms adjust to the temperatures within the TNZ through different responses requiring little energy. Environmental temperatures can cause fluctuations in a homeothermic organism’s metabolic rate.
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The former behaviour is typical when hunting non-schooling fish, slow-moving or immobile invertebrates or endothermic prey. When large amounts of prey are available, whales such as certain mysticetes hunt cooperatively in small groups. Some cetaceans may forage with other kinds of animals, such as other species of whales or certain species of pinnipeds. Large whales, such as mysticetes, are not usually subject to predation, but smaller whales, such as monodontids or ziphiids, are.
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In the gasification process, fuel will be gasified at 850 °C in the presence of steam to produce a nitrogen-free and clean synthetic gas. Charcoal will be burnt with air in the Figure 2: Showing Gasification Process Schematic Diagramcombustion chamber to provide the heating for the gasification process as it is an endothermic process. Thermal transfer will take place between the gasification and combustion chamber. The illustrated gasification process is presented in Figure 2.
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Burning the char off the spent shale produces oil shale ash. Spent shale and shale ash can be used as ingredients in cement or brick manufacture. The composition of the oil shale may lend added value to the extraction process through the recovery of by- products, including ammonia, sulfur, aromatic compounds, pitch, asphalt, and waxes. Heating the oil shale to pyrolysis temperature and completing the endothermic kerogen decomposition reactions require a source of energy.
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It melts at −51.0 °C and boils at −35.1 °C. It is an endothermic compound that can exothermically dissociate at room temperature, although the process is very slow unless a catalyst is present: the reaction between hydrogen and iodine at room temperature to give hydrogen iodide does not proceed to completion. The H–I bond dissociation energy is likewise the smallest of the hydrogen halides, at 295 kJ/mol.Greenwood and Earnshaw, pp.
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Both steam reforming and dry reforming are carried out in this reformer; therefore, it is possible to configure the H2/CO ratio by adjusting the H2O/CO2 ratio in the reduction chamber. The reforming reaction is a very specific elementary reaction; all carbon atoms on the left are reformed into carbon monoxide and all hydrogen atoms are reduced to hydrogen gas. The mixture of two product gases is called syngas. These reforming reactions are an endothermic reduction reaction.
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Podogymnura truei, which are endothermic species, are medium- sized ground dwellers that typically range from 130–150 mm in body length. Their body is narrow, which may have been an adaptation for burrowing through narrow crevices and have bilateral symmetry. These mammals also have long soft fur that is typically gray mixed with coarser reddish brown hairs on the dorsal side. On the ventral side the hairs have a grayish white tone with some brown mixed in.
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Self- heating field rations for up to 18 soldiers For critical vaccines, insulated shipping containers are passive packaging to help control the temperatures fluctuations seen even with a controlled cold chain. In addition, gel packs are often used to keep the temperature of the contents within specified acceptable temperature ranges. Some newer packages have the ability to heat or cool the product for the consumer. These have segregated compartments where exothermic or endothermic reactions provide the desired effect.
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They are also thought to influence the dynamics of mantle convection in that the exothermic transitions reinforce flow across the phase boundary, whereas the endothermic reaction hampers it. The pressure at which these phase transitions occur depends on temperature and iron content. At , the pure magnesium end member, forsterite, transforms to wadsleyite at and to ringwoodite at pressures above . Increasing the iron content decreases the pressure of the phase transition and narrows the wadsleyite stability field.
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For example, in an exothermic reaction the transition state is closer in energy to the reactants than to the products. Therefore, the transition state will be more geometrically similar to the reactants than to the products. In contrast, however, in an endothermic reaction the transition state is closer in energy to the products than to the reactants. So, according to Hammond’s postulate the structure of the transition state would resemble the products more than the reactants.
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Since the reactants are higher in energy, the transition state appears to be right after the reaction starts. An example of the “late” transition state is bromination. Bromination favors the reactants because it is an endothermic reaction, which means that the reactants are lower in energy than the products. Since the transition state is hard to observe, the postulate of bromination helps to picture the “late” transition state (see the representation of the "late" transition state).
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Those of the pitvipers are the more advanced, having a suspended sensory membrane as opposed to a simple pit structure. Within the family Viperidae, the pit organ is seen only in the subfamily Crotalinae: the pitvipers. The organ is used extensively to detect and target endothermic prey such as rodents and birds, and it was previously assumed that the organ evolved specifically for that purpose. However, recent evidence shows that the pit organ may also be used for thermoregulation.
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Examples include the crabeater seal, which primarily eats krill, the ringed seal, which eats mainly crustaceans, the Ross seal and southern elephant seal, which specialize on squid, and the bearded seal and walrus, which feed on clams and other bottom- dwelling invertebrates. Pinnipeds may hunt solitarily or cooperatively. The former behavior is typical when hunting non-schooling fish, slow-moving or immobile invertebrates or endothermic prey. Solitary foraging species usually exploit coastal waters, bays and rivers.
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For example, in an exothermic reaction the transition state is closer in energy to the reactants than to the products. Therefore, the transition state will be more geometrically similar to the reactants than to the products. In contrast, however, in an endothermic reaction the transition state is closer in energy to the products than to the reactants. So, according to Hammond's postulate the structure of the transition state would resemble the products more than the reactants.
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Since the reactants are higher in energy, the transition state appears to be right after the reaction starts. An example of the “late” transition state is bromination. Bromination favors the reactants because it is an endothermic reaction, which means that the reactants are lower in energy than the products. Since the transition state is hard to observe, the postulate of bromination helps to picture the “late” transition state (see the representation of the "late" transition state).
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Since the process requires additional energy, it is an endothermic change. The enthalpy of sublimation (also called heat of sublimation) can be calculated by adding the enthalpy of fusion and the enthalpy of vaporization. Comparison of phase diagrams of carbon dioxide (red) and water (blue) showing the carbon dioxide sublimation point (middle-left) at 1 atmosphere. As dry ice is heated, it crosses this point along the bold horizontal line from the solid phase directly into the gaseous phase.
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Basal metabolic rate (BMR) is the rate of energy expenditure per unit time by endothermic animals at rest. It is reported in energy units per unit time ranging from watt (joule/second) to ml O2/min or joule per hour per kg body mass J/(h·kg). Proper measurement requires a strict set of criteria be met. These criteria include being in a physically and psychologically undisturbed state, in a thermally neutral environment, while in the post-absorptive state (i.e.
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The corresponding saturated compound is thereby formed, which can be stored or transported under ambient conditions. If the hydrogen is needed again, the now hydrogenated, hydrogen-rich form of the LOHC is dehydrogenated, with the hydrogen being released again from the LOHC. This reaction is endothermic and takes place at elevated temperatures (250-320°C) again in the presence of a catalyst. Before the hydrogen can be used, it may have to be cleaned of LOHC steam.
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Cephalopods have large, well-developed brains, and their brain-to-body mass ratio is the largest among the invertebrates, falling between that of endothermic and ectothermic vertebrates. The nervous system of cephalopods is the most complex of all invertebrates. The giant nerve fibers of the cephalopod mantle have been widely used for many years as experimental material in neurophysiology; their large diameter (due to lack of myelination) makes them relatively easy to study compared with other animals.
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Common interest in the creature was sparked first in the 1890s. After several sightings, an enterprise of locals was founded to catch the monster, even drawing the support from King Oscar II. Since then hundreds of monster sightings have been made. No scientific results have been made, but the supporters have never lost their faith. In August 2008, a film crew claimed to have captured Storsjöodjuret on film, reporting that infrared cameras showed an endothermic mass in the lake.
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When mixed with oxygen, it burns with a pale yellowish-green flame. Ignition occurs when chlorine is passed into ammonia, forming nitrogen and hydrogen chloride; if chlorine is present in excess, then the highly explosive nitrogen trichloride (NCl3) is also formed. ;Decomposition: At high temperature and in the presence of a suitable catalyst, ammonia is decomposed into its constituent elements. Decomposition of ammonia is slightly endothermic process requiring 5.5 kcal/mol of ammonia, and yields hydrogen and nitrogen gas.
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The two species of this genus can keep their blood temperature higher above that of the water surrounding them than other cartilaginous fish, with temperature differences recorded up to 15.6 °C.Abstract for S. D. Anderson, K. J. Goldman: “Temperature Measurements from Salmon Sharks, Lamna ditropis, in Alaskan Waters”, Copeia, Vol. 2001, No. 3, 2001-08-06C. Larsen, H. Malte, R. E. Weber: “ATP-induced Reverse Temperature Effect in Isohemoglobins from the Endothermic Porbeagle Shark”, Journal of Biological Chemistry vol.
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Standard state does not strictly specify a temperature, but expressions for enthalpy generally reference the standard heat of formation at . For endothermic processes, the change is a positive value, and is negative in exothermic (heat-releasing) processes. The enthalpy of an ideal gas is independent of its pressure, and depends only on its temperature, which correlates to its internal energy. Real gases at common temperatures and pressures often closely approximate this behavior, which simplifies practical thermodynamic design and analysis.
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The mode takes place on the smaller Ecopoint: Antarctica map, introduced in the previous months for standard deathmatch play. Six players each play Mei, but where her Endothermic Blaster, which normally fires a stream of damaging cold, can only fire a single snowball. Players must find a snowball pile scattered around the map to reload the weapon. Further, her Ultimate ability allows her to fire a machine- gun-like string of snowballs for a brief period.
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Upon condensing to a liquid, nitric oxide dimerizes to dinitrogen dioxide, but the association is weak and reversible. The N–N distance in crystalline NO is 218 pm, nearly twice the N–O distance. Since the heat of formation of ·NO is endothermic, NO can be decomposed to the elements. Catalytic converters in cars exploit this reaction: : 2 NO → O2 \+ N2. When exposed to oxygen, nitric oxide converts into nitrogen dioxide: : 2 NO + O2 → 2 NO2.
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IMC accomplishes this dynamic analysis by measuring and recording vs. elapsed time the net rate of heat flow (μJ/sec = μW) to or from the specimen ampoule, and the cumulative amount of heat (J) consumed or produced. IMC is a powerful and versatile analytical tool for four closely related reasons: # All chemical and physical processes are either exothermic or endothermic—produce or consume heat. # The rate of heat flow is proportional to the rate of the process taking place.
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The most common industrial use of huntite is as a natural mixture with hydromagnesite as a flame retardant or fire retardant additive for polymers. The heat of a fire will cause huntite to decompose releasing carbon dioxide into the flames. This helps to slow the spread of the fire. The release of carbon dioxide is endothermic, meaning that it takes in heat, this action helps to cool the burning material, again slowing the spread of the fire.
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In 1847, Carl Bergmann published his observations that endothermic body size (i.e. mammals) increased with increasing latitude, commonly known as Bergmann's rule. His rule postulated that selection favored within species individuals with larger body sizes in cooler temperatures because the total heat loss would be diminished through lower surface area to volume ratios. However, ectothermic individuals thermoregulate and allow their internal body temperature to fluctuate with environmental temperature whereas endotherms maintain a constant internal body temperature.
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Even in these deep hibernators, the long periods of torpor is interrupted by bouts of endothermic metabolism, called arousals (typically lasting between 4–20 hours). These metabolic arousals cause body temperature to return to euthermic levels 35-37 °C. Most of the energy spent during hibernation is spent in arousals (70-80%), but their function remains unresolved. Shallow hibernation patterns without arousals have been described in large mammals (like the black bear,) or under special environmental circumstances.
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The opah is the newest addition to the list of regionally endothermic fish (warm-blooded), with a rete mirabile in its gill tissue structure. Other fish like the tunas, billfish and Lamnid sharks also possess this ability. This was first described in the opah in 2015 as exhibiting counter-current heat exchange in which the arteries, carrying warm blood, from the heart, warm the veins in the gills carrying cold blood."Warm Blood Makes Opah an Agile Predator".
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A thermographic image of an ectothermic snake wrapping around the hand of an endothermic human Information about the direct neuronal regulation of metabolic processes and circadian rhythm-controlled behaviors is not well known among either endothermic or ectothermic vertebrates, although extensive research has been done on the SCN in model animals such as the mammalian mouse and ectothermic reptiles, in particular, lizards. The SCN is known to be involved not only in photoreception through innervation from the retinohypothalamic tract but also in thermoregulation of vertebrates capable of homeothermy, as well as regulating locomotion and other behavioral outputs of the circadian clock within ectothermic vertebrates. The behavioral differences between both classes of vertebrates, when compared to the respective structures and properties of the SCN and various other nuclei proximate to the hypothalamus, provide insight into how these behaviors are the consequence of differing circadian regulation. Ultimately, many neuroethological studies must be done to completely ascertain the direct and indirect roles of the SCN on circadian- regulated behaviors of vertebrates.
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Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. Some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. Understanding chemical changes is a major part of the science of chemistry.
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The dragon was a stony grey-black color. It was obviously carnivorous and, as stated in the film, warm-blooded. Its endothermic nature combined with breathing out fire was its only serious fault because it needed to stay in cooler areas to keep from suffering from heat stroke or exhaustion, so it kept near the air conditioning vents in the facility. This would also explain why the reptile was living in England in the Middle Ages, a relatively cold place.
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Since the products are higher in energy, the transition state appears to be right before the reaction is complete. One other useful interpretation of the postulate often found in textbooks of organic chemistry is the following: :Assume that the transition states for reactions involving unstable intermediates can be closely approximated by the intermediates themselves. This interpretation ignores extremely exothermic and endothermic reactions which are relatively unusual and relates the transition state to the intermediates which are usually the most unstable.
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The synthesis of XeF2 is an endothermic process which results in a white powder which sublimes at low pressures. (P < 4 Torr) The low vapor pressure allowed early researchers and engineers to use it in comparatively simple set ups. Modern vapour etch tools are more sophisticated and are characterized by the way the gas is feed into the etch chamber. In pulsed systems the etchant is expanded, feed into the reaction chamber and remains there until it has been consumed by the reaction.
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Because of energy limitations, oxygen and nitrogen do not react at ambient temperatures. But at high temperatures, they undergo an endothermic reaction producing various oxides of nitrogen. Such temperatures arise inside an internal combustion engine or a power station boiler, during the combustion of a mixture of air and fuel, and naturally in a lightning flash. In atmospheric chemistry, the term denotes the total concentration of NO and since the conversion between these two species is rapid in the stratosphere and troposphere.
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Since the products are higher in energy, the transition state appears to be right before the reaction is complete. One other useful interpretation of the postulate often found in textbooks of organic chemistry is the following: :Assume that the transition states for reactions involving unstable intermediates can be closely approximated by the intermediates themselves. This interpretation ignores extremely exothermic and endothermic reactions which are relatively unusual and relates the transition state to the intermediates which are usually the most unstable.
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Yellow chlorine dioxide (ClO2) gas above a yellow chlorine dioxide solution. Solutions of pure chlorine dioxide are dark green: this solution is yellow due to impurities produced from its photodecomposition. Structure of dichlorine heptoxide, Cl2O7, the most stable of the chlorine oxides The chlorine oxides are well-studied in spite of their instability (all of them are endothermic compounds). They are important because they are produced when chlorofluorocarbons undergo photolysis in the upper atmosphere and cause the destruction of the ozone layer.
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Firestopping and fireproofing products can be ablative in nature. This can mean endothermic materials, or merely materials that are sacrificial and become "spent" over time while exposed to fire, such as silicone firestop products. Given sufficient time under fire or heat conditions, these products char away, crumble, and disappear. The idea is to put enough of this material in the way of the fire that a level of fire-resistance rating can be maintained, as demonstrated in a fire test.
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One consequence of geometric strain on both the boron and the porphyrin moieties is unique reactivity. The Brothers group was able to demonstrate reductive coupling, wherein two BX2 units inside the porphyrin pocket become X-B-B-X, only occurs with X=Br and when the substrates are within the porphyrin pocket. DFT calculations show that for X=Cl or F, the reaction is endothermic and non-spontaneous. However, for X=Br, the reduction is spontaneous, which was consistent with experimental findings.
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Ancient Egyptian hieroglyphs show a snow-filled vessel next to fruit juice. There are Tang dynasty records of a chilled dessert made with flour, camphor and water buffalo milk and recipes for snow-chilled sweets are included in a 1st-century Roman recipe book. There are Persian records from the 2nd century AD for sweetened chilled drinks with ice made by freezing water in the desert at night. Ice cream was made possible only by the discovery of the endothermic effect.
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The term is often confused with exergonic reaction, which IUPAC defines as "... a reaction for which the overall standard Gibbs energy change ΔG⚬ is negative." A strongly exothermic reaction will usually also be exergonic because ΔH⚬ makes a major contribution to ΔG⚬. Most of the spectacular chemical reactions that are demonstrated in classrooms are exothermic and exergonic. The opposite is an endothermic reaction, which usually takes up heat and is driven by an entropy increase in the system.
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Thermal decomposition of concrete produces water vapor and carbon dioxide, which may further react with the metals in the melt, oxidizing the metals, and reducing the gases to hydrogen and carbon monoxide. The decomposition of the concrete and volatilization of its alkali components is an endothermic process. Aerosols released during this phase are primarily based on concrete-originating silicon compounds; otherwise volatile elements, for example, caesium, can be bound in nonvolatile insoluble silicates. Several reactions occur between the concrete and the corium melt.
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Thermal image of an ectothermic tarantula on an endothermic human hand A tarantula's blood is unique (not only in appearance); an oxygen-transporting protein is present (the copper-based hemocyanin), but not enclosed in blood cells such as the erythrocytes of mammals. A tarantula's blood is not true blood, but rather a liquid called haemolymph, or hemolymph. At least four types of hemocytes, or hemolymph cells, are known. The tarantula's heart is a long, slender tube located along the top of the opisthosoma.
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The deuterium and tritium then fuse to produce helium, one neutron, and 17.59 MeV of free energy in the form of gamma rays, kinetic energy, etc. The helium is an inert byproduct. Before the Castle Bravo nuclear weapons test in 1954, it was thought that only the less common isotope 6Li would breed tritium when struck with fast neutrons. The Castle Bravo test showed (accidentally) that the more plentiful 7Li also does so under extreme conditions, albeit by an endothermic reaction.
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CNBs can engage in cycloaddiiton reactions and easily form the chemical bonds capable of attaching molecules with complex structures. this can be explained by a greater availability of CNB surface to the reactants the presence of π-conjugated structures, and having 5-atom rings with excess pirimidization energy. Formation energy indicated that preparation of CNBs is endothermic, meaning that it is not favorable to create. All CNBs are conducting, regardless of whether the single walled CNT is a metallic or semiconducting base.
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To maintain normal levels of oxygen transport in these conditions, they have developed unique blood respiratory properties. The oxygen carrying capacity in southern bluefin tuna is high, due to the high hemoglobin (Hb) concentration. The blood affinity for oxygen is also elevated. Normally, blood affinity for oxygen would change with changes in temperature experienced at gills (in comparison to warmer adjacent tissues); however, Hb in southern bluefin tuna shows insensitivity to temperature, and a reverse temperature effect between (Hb-O2 binding is endothermic).
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The dehydroxylation of kaolin to metakaolin is an endothermic process due to the large amount of energy required to remove the chemically bonded hydroxyl ions. Above the temperature range of dehydroxylation, kaolinite transforms into metakaolin, a complex amorphous structure which retains some long-range order due to layer stacking. Much of the aluminum of the octahedral layer becomes tetrahedrally and pentahedrally coordinated. In order to produce a pozzolan (supplementary cementitious material) nearly complete dehydroxylation must be reached without overheating, i.e.
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Foraging activity is therefore restricted to the day time (diurnal activity patterns) in most vertebrate ectotherms. In lizards, for instance, only a few species are known to be nocturnal (e.g. many geckos) and they mostly use 'sit and wait' foraging strategies that may not require body temperatures as high as those necessary for active foraging. Endothermic vertebrate species are therefore less dependent on the environmental conditions and have developed a high variability (both within and between species) in their diurnal activity patterns.
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180 He theorized that big-eyed Ornitholestes might have been specialized for nocturnal hunting, while Coelurus may have focused on those prey species that were active during the day. Foster noted, however, that this hypothesis was largely speculative; a lack of preserved skull material from Coelurus makes it impossible to verify whether its eyes were proportionally smaller than those of Ornitholestes.Foster (2007), p. 180–181 Paul (1988) estimated that a endothermic Ornitholestes would have a daily dietary requirement of about of flesh.
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An experiment describing catalytic decomposition of hydrogen peroxide. A concentrated hydrogen peroxide solution can be easily decomposed to water and oxygen. An example of a spontaneous (without addition of an external energy source) decomposition is that of hydrogen peroxide which slowly decomposes into water and oxygen (see video at right): : 2 H2O2 → 2 H2O + O2 This reaction is one of the exceptions to the endothermic nature of decomposition reactions. Other reactions involving decomposition do require the input of external energy.
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MgH is the second most abundant magnesium containing gas (after atomic magnesium) in the deeper hotter parts of planets and brown dwarfs. Pages 1065-1068 concentrate on magnesium. The reaction of Mg atoms with H2 (dihydrogen gas) is actually endothermic and proceeds when magnesium atoms are excited electronically. The magnesium atom inserts into the bond between the two hydrogen atoms to create a temporary MgH2 molecule, which spins rapidly and breaks up into a spinning MgH molecule and a hydrogen atom.
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A large proportion of the creatures traditionally called "warm- blooded", like birds and mammals, fit all three of these categories (i.e., they are endothermic, homeothermic, and tachymetabolic). However, over the past 30 years, studies in the field of animal thermophysiology have revealed many species belonging to these two groups that do not fit all these criteria. For example, many bats and small birds are poikilothermic and bradymetabolic when they sleep for the night (or, in nocturnal species, for the day).
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Like all energy conversions, metabolism is rather inefficient, and around 60% of the available energy is converted to heat rather than to ATP. In most organisms, this heat is simply lost to the environment. However, endothermic homeotherms (the animals generally characterized as "warm-blooded") both produce more heat and have better ways to retain and regulate it than other animals. They have a higher basal metabolic rate, and also a greater capacity to increase their metabolic rate when engaged in strenuous activity.
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Due to Fry's script being dropped, production of some episodes of the second series had to be rescheduled, with "Fear Her" being produced alongside "The Idiot's Lantern". The majority of the episode, including exterior shots and the interior of Chloe's home, was filmed in the Tremorfa area of Cardiff from 24 to 31 January 2006. On 27 January, the Millennium Stadium in Cardiff was used for the Olympic Stadium. The cold temperatures experienced during filming were explained in the plot as part of the Isolus' endothermic nature.
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To illustrate, consider the alkoxy radical-catalyzed, anti- Markovnikov reaction of hydrogen bromide to an alkene. In this reaction, a catalytic amount of organic peroxide is needed to abstract the acidic proton from HBr and generate the bromine radical, however a full molar equivalent of alkene and acid is required for completion. 400px Note that the radical will be on the more substituted carbon. Free-radical addition does not occur with the molecules HCl or HI. Both reactions are extremely endothermic and are not chemically favored.
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Platypleura divisa (Germar, 1834), is an African cicada first described by Ernst Friedrich Germar, entomologist and professor of mineralogy at Halle, who also studied beetles. The genus Platypleura occurs widely across Africa and southern Asia. Some of the South African species are remarkable for their endothermic thermoregulation that enables crepuscular signalling, an adaptation that reduces risk of predation and enables a greater range for their calls. In field experiments their maximum body temperature while calling at dusk, was measured at 22 °C above ambient temperature.
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An absorption or release of nuclear energy occurs in nuclear reactions or radioactive decay; those that absorb energy are called endothermic reactions and those that release energy are exothermic reactions. Energy is consumed or liberated because of differences in the nuclear binding energy between the incoming and outgoing products of the nuclear transmutation. The best-known classes of exothermic nuclear transmutations are fission and fusion. Nuclear energy may be liberated by atomic fission, when heavy atomic nuclei (like uranium and plutonium) are broken apart into lighter nuclei.
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When conserving energy, the core body temperature can drop to match the surroundings. A great white shark's success in raising its core temperature is an example of gigantothermy. Therefore, the great white shark can be considered an endothermic poikilotherm or mesotherm because its body temperature is not constant but is internally regulated.White Shark Biological Profile from the Florida Museum of Natural History Great whites also rely on the fat and oils stored within their livers for long- distance migrations across nutrient-poor areas of the oceans.
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This structure forms an Al'-P-Al-P-Al' linkage nearly parallel to the c-axis, with the other distinct aluminium atom offset, and nearly vertically below a PO43− ion. Taranakite readily loses water when heated. Thermal gravimetric analysis shows two endothermic water loss events occurring in the ranges 80-140 °C and 140-300 °C corresponding to the sequential loss of five and thirteen water molecules to form francoanellite and a noncrystalline material. Heating to 500 °C results in complete dehydration to form K3Al5P8O29.
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Examining the oxygen-isotope ratio from the bones from different parts of an extinct animal's body should indicate which thermoregulation mode an animal used during its lifetime. An endothermic (warm-blooded) animal should maintain a very similar body temperature throughout its entire body (which is called homeothermy) and therefore there should be little variation in the oxygen-isotope ratio when measured in different bones. Alternatively, the oxygen-isotope ratio differs considerably when measured throughout the body of an organism with an ectothermic (cold- blooded) physiology.Martin, A.J. (2006).
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Thunnus are widely but sparsely distributed throughout the oceans of the world, generally in tropical and temperate waters at latitudes ranging between about 45° north and south of the equator. All tunas are able to maintain the temperature of certain parts of their body above the temperature of ambient seawater. For example, bluefin can maintain a core body temperature of , in water as cold as . However, unlike "typical" endothermic creatures such as mammals and birds, tuna do not maintain temperature within a relatively narrow range.
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Inside the chamber, the 3He is diluted as it flows from the concentrated phase through the phase boundary into the dilute phase. The heat necessary for the dilution is the useful cooling power of the refrigerator, as the process of moving the 3He through the phase boundary is endothermic and removes heat from the mixing chamber environment. The 3He then leaves the mixing chamber in the dilute phase. On the dilute side and in the still the 3He flows through superfluid 4He which is at rest.
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Mei wields an Endothermic Blaster that can either freeze enemies in place with a short-range ice beam or shoot a long-range icicle projectile. Mei can also use the Blaster to encase herself in a solid ice block that blocks damage and heals her injuries, as well as erect temporary walls of solid ice with many versatile uses, primarily for blocking the enemies. Her ultimate ability is Blizzard, which calls down her personal weather modification drone Snowball to freeze all enemies in a wide radius.
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Metabolism - Despite having only a partial fossil, it has been said that Scymnosaurs were likely not endothermic for the lack of a secondary palate. The higher metabolic load associated with endothermy is associated with characters such as fur, increased aerobic capacity and the development of a secondary palate, which allows for airflow independent of oral food processing. It is, however, still unclear as to the order acquired characters that allowed the development of faster metabolisms, which happened at least twice with birds and mammals.
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Formation of petroleum occurs from hydrocarbon pyrolysis in a variety of mainly endothermic reactions at high temperature or pressure, or both. These phases are described in detail below. ;Anaerobic decay: In the absence of plentiful oxygen, aerobic bacteria were prevented from decaying the organic matter after it was buried under a layer of sediment or water. However, anaerobic bacteria were able to reduce sulfates and nitrates among the matter to H2S and N2 respectively by using the matter as a source for other reactants.
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The maxilloturbinates may not have been preserved because they were either very thin or cartilaginous. The possibility has also been raised that these ridges are associated with an olfactory epithelium rather than turbinates. Nonetheless, the possible presence of maxilloturbinates suggests that Glanosuchus may have been able to rapidly breathe without drying out the nasal passage, and therefore could have been an endotherm. Glanosuchus is the earliest known therapsid to possess maxilloturbinates, but it shares features with reptiles that suggest it was not fully endothermic.
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Consequently, the deuterium-tritium fuel cycle requires the breeding of tritium from lithium using one of the following reactions: : + → + : + → + + The reactant neutron is supplied by the D-T fusion reaction shown above, and the one that has the greatest yield of energy. The reaction with 6Li is exothermic, providing a small energy gain for the reactor. The reaction with 7Li is endothermic but does not consume the neutron. At least some neutron multiplication reactions are required to replace the neutrons lost to absorption by other elements.
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Fusion reactions occur when two or more atomic nuclei come close enough for long enough that the nuclear force pulling them together exceeds the electrostatic force pushing them apart, fusing them into heavier nuclei. For nuclei lighter than iron-56, the reaction is exothermic, releasing energy. For nuclei heavier than iron-56, the reaction is endothermic, requiring an external source of energy. Hence, nuclei smaller than iron-56 are more likely to fuse while those heavier than iron-56 are more likely to break apart.
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A similar study was done by Tsuboi et al., shows clear evidence that the brain size is correlated with the gut size by controlling the effects of shared ancestral and ecological confounding variables. The study found that the evolution of a larger brain is closely related to the increase in reproductive investment into egg size and parental size. The result of the experiment concluded that the energy cost of encephalization might have involved in the evolution of brain size in both endothermic as well as ectothermic vertebrates.
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Because of historical accident, students encounter a source of possible confusion between the terminology of physics and biology. Whereas the thermodynamic terms "exothermic" and "endothermic" respectively refer to processes that give out heat energy and processes that absorb heat energy, in biology the sense is effectively reversed. The metabolic terms "ectotherm" and "endotherm" respectively refer to organisms that rely largely on external heat to achieve a full working temperature, and to organisms that produce heat from within as a major factor in controlling their body temperatures.
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A 1.8m southern black racer basking in the Inverness, Florida sunshine on a cool morning. Ectotherms rely largely on external heat sources such as sunlight to achieve their optimal body temperature for various bodily activities. Accordingly, they depend on ambient conditions to reach operational body temperatures. In contrast, endothermic animals maintain nearly constant high operational body temperatures largely by reliance on internal heat produced by metabolically active organs (liver, kidney, heart, brain, muscle) or even by specialized heat producing organs like brown adipose tissue (BAT).
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A 2011 publication suggested that selection for the expansion of skeletal muscle, rather than the evolution of flight, was the driving force for the emergence of this clade. Muscles became larger in prospectively endothermic saurians, according to this hypothesis, as a response to the loss of the vertebrate mitochondrial uncoupling protein, UCP1, which is thermogenic. In mammals, UCP1 functions within brown adipose tissue to protect newborns against hypothermia. In modern birds, skeletal muscle serves a similar function and is presumed to have done so in their ancestors.
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The removal of electrons from the cation is endothermic, raising the system's overall energy. There may also be energy changes associated with breaking of existing bonds or the addition of more than one electron to form anions. However, the action of the anion's accepting the cation's valence electrons and the subsequent attraction of the ions to each other releases (lattice) energy and, thus, lowers the overall energy of the system. Ionic bonding will occur only if the overall energy change for the reaction is favorable.
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In general, external temperature does not influence endothermic animal behavior or circadian rhythm because of the ability of these animals to keep their internal body temperature constant through homeostatic thermoregulation; however, peripheral oscillators (see Circadian rhythm) in mammals are sensitive to temperature pulses and will experience resetting of the circadian clock phase and associated genetic expression, suggesting how peripheral circadian oscillators may be separate entities from one another despite having a master oscillator within the SCN. Furthermore, when individual neurons of the SCN from a mouse were treated with heat pulses, a similar resetting of oscillators was observed, but when an intact SCN was treated with the same heat pulse treatment the SCN was resistant to temperature change by exhibiting an unaltered circadian oscillating phase. In ectothermic animals, particularly the ruin lizard Podacris sicula, temperature has been shown to affect the circadian oscillators within the SCN. This reflects a potential evolutionary relationship among endothermic and ectothermic vertebrates, in how ectotherms rely on environmental temperature to affect their circadian rhythms and behavior and endotherms have an evolved SCN to essentially ignore external temperature and use photoreception as a means for entraining the circadian oscillators within their SCN.
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The First Law of Thermodynamics is a statement of the conservation of energy; though it can be changed from one form to another, energy can be neither created nor destroyed. From the first law, a principle called Hess's Law arises. Hess’s Law states that the heat absorbed or evolved in a given reaction must always be constant and independent of the manner in which the reaction takes place. Although some intermediate reactions may be endothermic and others may be exothermic, the total heat exchange is equal to the heat exchange had the process occurred directly.
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Dimetrodon may have angled its sail away from the sun to cool off or restricted blood flow to the sail to maintain heat at night. In 1986, J. Scott Turner and C. Richard Tracy proposed that the evolution of a sail in Dimetrodon was related to the evolution of warm-bloodedness in mammal ancestors. They thought that the sail of Dimetrodon enabled it to be homeothermic, maintaining a constant, albeit low, body temperature. Mammals are also homeothermic, although they differ from Dimetrodon in being endothermic, controlling their body temperature internally through heightened metabolism.
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This hot added material cools down by conduction and convection of heat. At the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of subduction usually at an ocean trench. This subducted material sinks through the Earth's interior. Some subducted material appears to reach the lower mantle, while in other regions, this material is impeded from sinking further, possibly due to a phase transition from spinel to silicate perovskite and magnesiowustite, an endothermic reaction.
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At the high temperatures and pressures found at depth within the Earth the olivine structure is no longer stable. Below depths of about olivine undergoes an exothermic phase transition to the sorosilicate, wadsleyite and, at about depth, wadsleyite transforms exothermically into ringwoodite, which has the spinel structure. At a depth of about , ringwoodite decomposes into silicate perovskite ((Mg,Fe)SiO3) and ferropericlase ((Mg,Fe)O) in an endothermic reaction. These phase transitions lead to a discontinuous increase in the density of the Earth's mantle that can be observed by seismic methods.
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Common fireproofing methods for structural steel include intumescent, endothermic, and plaster coatings as well as drywall, calcium silicate cladding, and mineral wool insulating blankets.Best Practice Guidelines for Structural Fire Resistance Design of Concrete and Steel Buildings, NIST Technical Note 1681, L. T. Phan, J. L. Gross, and T. P. McAllister, 2010. (View report) Concrete building structures often meet code required fire-resistance ratings, as the concrete thickness over the steel rebar provides sufficient fire resistance. However, concrete can be subject to spalling, particularly if it has an elevated moisture content.
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Although additional fireproofing is not often applied to concrete building structures, it is sometimes used in traffic tunnels and locations where a hydrocarbon fuel fire is more likely, as flammable liquid fires provides more heat to the structural element as compared to a fire involving ordinary combustibles during the same fire period. Structural steel fireproofing materials include intumescent, endothermic and plaster coatings as well as drywall, calcium silicate cladding, and mineral or high temperature insulation wool blankets. Attention is given to connections, as the thermal expansion of structural elements can compromise fire-resistance rated assemblies.
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Reynolds prefers a method referred to as "paretic infusion", which involves firing a chemical projectile into the forehead of the zombie. This causes an endothermic reaction, freezing the zombie's brain and temporarily immobilizing it. When the paretic infusion method is tested on the zombie in the lab, it is only successful for a few moments, wearing off much faster than expected; the zombie breaks free and attacks a scientist, biting his fingers off before bashing his head against a wall, killing him. Infected by the zombie's bite, the scientist re-animates and attacks another technician.
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Cephalopods are widely regarded as the most intelligent of the invertebrates, and have well developed senses and large brains (larger than those of gastropods). The nervous system of cephalopods is the most complex of the invertebrates and their brain-to-body-mass ratio falls between that of endothermic and ectothermic vertebrates. Captive cephalopods have also been known to climb out of their aquaria, maneuver a distance of the lab floor, enter another aquarium to feed on the crabs, and return to their own aquarium.Raven, Peter et al. (2003).
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This is illustrated in the titration plot of EDTA with calcium and magnesium in sea water (Figure 14). Following the solution temperature curve, the breakpoint for the calcium content (red-tagged endpoint) is followed by a region of modest temperature rise due to competition between the heats of dilution of the titrant with the solution, and the endothermic reaction of Mg2+ and EDTA. The breakpoint for the consumption of Mg2+ (blue-tagged endpoint) by EDTA is revealed by upswing in temperature caused purely by the heat of dilution. Fig. 15.
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1988 The parameters that are measured are referred to as the glass transition value (Tg) and melting temperature (Tm). These values are measured over time and are comparable between an inert reference sample and the analyte. Changes in the (Tm) and (Tg) values evaluate phase changes (solid, liquid-gel, liquid, etc.) in which an endothermic or exothermic process occurs. This technique is useful for monitoring the phase changes in phospholipids by providing information such as the amount of heat released or absorbed and time for phase transitions to occur, etc.
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The carbon monoxide gas can then be passed with steam over iron oxide or other oxides and undergo a water gas shift reaction to obtain further quantities of H2. The downside to this process is that its major byproducts are CO, CO2 and other greenhouse gases. Depending on the quality of the feedstock (natural gas, rich gases, naphtha, etc.), one ton of hydrogen produced will also produce 9 to 12 tons of CO2. For this process high temperature (700–1100 °C) steam (H2O) reacts with methane (CH4) in an endothermic reaction to yield syngas.
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Principal Components of Endothermic Gas Generators : # Heating Chamber for supplying heat by electric heating elements of combustion, # Vertical cylindrical retorts, # Tiny, porous ceramic pieces that are saturated with nickel, which acts as a catalyst for the reaction, # Cooling heat exchanger in order to cool the products of the reaction as quickly as possible so that it reaches a particular temperature which stops any further reaction, # Control system which will help maintain the consistency of the temperature of the reaction which will help adjust the gas ratio, providing the wanted dew point.
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Homolactic fermentation breaks no carbon bonds and emits no gas; its overall equation is C6H12O6 (carbohydrate) → 2 CH3CHOHCOOH (lactic acid). It is a mildly endothermic reaction, emitting no energy; the fermentation vessel remains at ambient temperature. These are in marked contrast to decomposition, which emits the majority of its input carbon and energy within greenhouse gases (carbon dioxide and methane, in proportions determined by the method of decomposition) and as heat (in aerobic decomposition) Decomposition also loses the key plant nutrient nitrogen (in the potent greenhouse gas nitrous oxide and in ammonia.).
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Basic leaf-nosed bat body layout New World leaf-nosed bats are bilaterally symmetrical and endothermic mammals characterized by an elaborate outgrowth of skin on their noses, called a nose- leaf, which is believed to aid in echolocation. The nose-leaf can be adorned with a vertical leaf, a concave upward leaf, or multiple accessory leaves; varying by species. Leaf-nosed bats lack a tail, have triangular-shaped ears that can have pointed or rounded tips, range in body size from 4 cm to 13.5 cm, and a wingspan up to 90 cm or more.
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A reaction with a negative Q value is endothermic, i.e. requires a net energy input, since the kinetic energy of the final state is less than the kinetic energy of the initial state. Observe that a chemical reaction is exothermic when it has a negative enthalpy of reaction, in contrast a positive Q value in a nuclear reaction. The Q value can also be expressed in terms of the binding energies of the nuclear species as: Q=B_f- B_i Proof: Note that the count of nucleons is conserved in a nuclear reaction.
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Like the other oxygen fluorides, O3F2 is endothermic and decomposes at about 115 K with the evolution of heat, which is given by the following reaction: :2 O3F2 -> O2 + 2O2F2 O3F2 is safer to work with than ozone, and can be evaporated, or thermally decomposed, or exposed to electric sparks, without any explosions. But on contact with organic matter or oxidizable compounds, it can detonate or explode. Thus, the addition of even one drop of ozone difluoride to solid anhydrous ammonia will result in a mild explosion, when they are both at 90 K each.
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On thermal decomposition the alkali perchloratoborate salts form an alkali perchlorate, and boron trioxide as a solid residue, and gas containing dichlorine heptoxide, chlorine dioxide, chlorine, and oxygen. :2 M[B(ClO4)4] → 2 MClO4 \+ B2O3 \+ (3 Cl2O7 or 6 ClO2 \+ O2 or 6 Cl2 \+ O2) When the alkali perchloratoborates first start to decompose at the lower temperatures, the reaction is endothermic, and dichlorine heptoxide is formed. However, if caesium perchloratoborate is heated the decomposition becomes exothermic above 90 °C, and at 100 °C it explodes exothermically forming chlorine and oxygen.
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The fusion of two nuclei that create larger nuclei with lower atomic numbers than iron and nickel—a total nucleon number of about 60—is usually an exothermic process that releases more energy than is required to bring them together. It is this energy-releasing process that makes nuclear fusion in stars a self-sustaining reaction. For heavier nuclei, the binding energy per nucleon in the nucleus begins to decrease. That means fusion processes producing nuclei that have atomic numbers higher than about 26, and atomic masses higher than about 60, is an endothermic process.
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Erythritol has a strong cooling effect (endothermic, or positive heat of solution) when it dissolves in water, which is often compared with the cooling effect of mint flavors. The cooling effect is present only when erythritol is not already dissolved in water, a situation that might be experienced in an erythritol-sweetened frosting, chocolate bar, chewing gum, or hard candy. The cooling effect of erythritol is very similar to that of xylitol and among the strongest cooling effects of all sugar alcohols. Erythritol has a pKa of 13.903 at 18 °C.
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1,2-Dichloroethane, ClCH2CH2Cl (also known as ethylene dichloride, EDC), can be prepared by halogenation of ethane or ethylene, inexpensive starting materials. When EDC in gas phase is heated to 500 °C at 15–30 atm (1.5 to 3 MPa) pressure, it decomposes to produce vinyl chloride and anhydrous HCl. This production method is cheaper than preparing EDC from acetylene, which is why it has become the major route to vinyl chloride since the late 1950s. :ClCH2CH2Cl → CH2=CHCl + HCl The thermal cracking reaction is highly endothermic, and is generally carried out in a fired heater.
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One cycle of unidirectional rotation takes 4 reaction steps. The first step is a low temperature endothermic photoisomerization of the trans (P,P) isomer 1 to the cis (M,M) 2 where P stands for the right-handed helix and M for the left- handed helix. In this process, the two axial methyl groups are converted into two less sterically favorable equatorial methyl groups. By increasing the temperature to 20 °C these methyl groups convert back exothermally to the (P,P) cis axial groups (3) in a helix inversion.
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A reaction with ∆H°<0 is called exothermic reaction while one with ∆H°>0 is endothermic. Figure 8: Reaction Coordinate Diagrams showing favorable or unfavorable and slow or fast reactions The relative stability of reactant and product does not define the feasibility of any reaction all by itself. For any reaction to proceed, the starting material must have enough energy to cross over an energy barrier. This energy barrier is known as activation energy (∆G≠) and the rate of reaction is dependent on the height of this barrier.
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The timing of the porbeagle's reproductive cycle is unusual in that it is largely similar in both hemispheres, rather than being offset by six months. This suggests that its reproduction is not significantly affected by temperature or day length, perhaps owing to its endothermic physiology. Mating takes place mainly between September and November, though females with fresh mating scars have been reported as late as January off the Shetland Islands. The male bites at the female's pectoral fins, gill region, and flanks while courting and to hold on for copulation.
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The "thermoneutral zone" for the environment is around 25 °C (77 °F), at which point the metabolism needed to maintain body temperature is minimized. The echidna is endothermic, and can maintain body temperatures of around 32 °C.Augee, Gooden and Musser, p. 112. It can also reduce its metabolism and heart rate and body temperature.Augee, Gooden and Musser, p. 107. In addition to brief and light bouts of torpor throughout the year, the echidna enters periods during the Australian winter when it hibernates,Augee, Gooden and Musser, p. 108.
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The enthalpy of solution, enthalpy of dissolution, or heat of solution is the enthalpy change associated with the dissolution of a substance in a solvent at constant pressure resulting in infinite dilution. The enthalpy of solution is most often expressed in kJ/mol at constant temperature. The energy change can be regarded as being made of three parts, the endothermic breaking of bonds within the solute and within the solvent, and the formation of attractions between the solute and the solvent. An ideal solution has a null enthalpy of mixing.
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The reverse applies when the reaction is endothermic. When K has been determined at more than two temperatures, a straight line fitting procedure may be applied to a plot of \ln K against 1/T to obtain a value for \Delta H^\ominus . Error propagation theory can be used to show that, with this procedure, the error on the calculated \Delta H^\ominus value is much greater than the error on individual log K values. Consequently, K needs to be determined to high precision when using this method.
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Robert Thomas Bakker (born March 24, 1945) is an American paleontologist who helped reshape modern theories about dinosaurs, particularly by adding support to the theory that some dinosaurs were endothermic (warm-blooded). Along with his mentor John Ostrom, Bakker was responsible for initiating the ongoing "dinosaur renaissance" in paleontological studies, beginning with Bakker's article "Dinosaur Renaissance" in the April 1975 issue of Scientific American. His specialty is the ecological context and behavior of dinosaurs. Bakker has been a major proponent of the theory that dinosaurs were warm-blooded, smart, fast, and adaptable.
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The anatomical evidence suggested by Santa Luca was identified as adaptations for foraging; the robust and strong arms might have been used for digging up roots and breaking open insect nests. Most studies consider dinosaurs as endothermic (warm-blooded) animals, with an elevated metabolism comparable to that of today's mammals and birds. In a 2009 study, Herman Pontzer and colleagues calculated the aerobic endurance of various dinosaurs. Even at moderate running speeds, Heterodontosaurus would have exceeded the maximum aerobic capabilities possible for an ectotherm (cold-blooded) animal, indicating endothermy in this genus.
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More specifically, poly(dibutylstannane) for example showed an endothermic phase transition at ~0 °C from a rectangular to a pure nematic phase, as determined by X-ray diffraction.F. Choffat, S. Käser, P. Wolfer, D. Schmid, R. Mezzenga, P. Smith, W. Caseri, Macromolecules, 2007, 40, 7878. As expected, polystannanes were semi-conductive. Temperature-dependent, time-resolved pulse radiolysis microwave conductivity measurements of poly(dibutylstannane) yielded values of charge-carrier mobilities of 0.1 to 0.03 cm2 V−1 s−1, which are similar to those found for pi-bond-conjugated carbon-based polymers.
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Since all decomposition reactions break apart the bonds holding it together in order to produce into its simpler basic parts, the reactions would require some form of this energy in varying degrees. Because of this fundamental rule, it is known that most of these reactions are endothermic although exceptions do exist. The stability of a chemical compound is eventually limited when exposed to extreme environmental conditions such as heat, radiation, humidity, or the acidity of a solvent. Because of this chemical decomposition is often an undesired chemical reaction.
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Platypleura is a genus of cicadas that occurs widely across Africa and southern Asia. Some of the South African species are remarkable for their endothermic thermoregulation that enables crepuscular signalling, an adaptation that reduces risk of predation and enables a greater range for their calls. In field experiments their maximum body temperature while calling at dusk, was measured at 22 °C above ambient temperature. The Platypleurini are distributed from the Cape in South Africa, throughout sub-Saharan Africa and Madagascar, through India and south East Asia, to Japan.
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More than 30 such complexes have been synthesized and characterized. Whereas the xenon fluorides are well characterized, with the exception of dichloride XeCl2 and XeCl4, the other halides are not known. Xenon dichloride, formed by the high-frequency irradiation of a mixture of xenon, fluorine, and silicon or carbon tetrachloride, is reported to be an endothermic, colorless, crystalline compound that decomposes into the elements at 80 °C. However, may be merely a van der Waals molecule of weakly bound Xe atoms and molecules and not a real compound.
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As iron has one of the highest binding energies, reactions producing heavier elements are generally endothermic. Therefore significant amounts of heavier elements are not formed during stable periods of massive star evolution, but are formed in supernova explosions. Some lighter stars also form these elements in the outer parts of the stars over long periods of time, by absorbing energy from fusion in the inside of the star, by absorbing neutrons that are emitted from the fusion process. All of the elements heavier than iron have some potential energy to release, in theory.
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This radical reacts with the xanthate 2 to S-methyl-S-methyl dithiocarbonate 7 and the radical intermediate 5. The (CH3)3B.H2O complex 3 provides a hydrogen for recombining with this radical to the alkane 6 leaving behind diethyl borinic acid and a new methyl radical. Barton-McCombie deoxygenation reaction mechanism It is found by theoretical calculations that an O-H homolysis reaction in the borane-water complex is endothermic with an energy similar to that of the homolysis reaction in tributylstannane but much lower than the homolysis reaction of pure water.
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An instant cold pack is a device that consists of two bags; one containing water, inside a bag containing ammonium nitrate, calcium ammonium nitrate or urea. When the inner bag of water is broken by squeezing the package, it dissolves the solid in an endothermic reaction. This reaction absorbs heat from the surroundings, quickly lowering the pack's temperature. Instant cold packs are a convenient direct replacement for crushed ice used as first aid on sport injuries, and can be carried as first aid to remote or wilderness areas where ice is unavailable.
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Calcium carbide is produced industrially in an electric arc furnace from a mixture of lime and coke at approximately . This is an endothermic reaction requiring per moleCalculated from data in the CRC Handbook of Chemistry and Physics. and high temperatures to drive off the carbon monoxide. This method has not changed since its invention in 1892: :CaO + 3 C → CaC2 \+ CO The high temperature required for this reaction is not practically achievable by traditional combustion, so the reaction is performed in an electric arc furnace with graphite electrodes.
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Fig 2.CLC-SMR system for H2 production: (a) SMR reactor inside the reducer (fuel reactor) (b) SMR reactor inside the combustor (air reactor) Hydrogen and syngas are currently produced largely by steam methane reforming (SMR). The main reaction in SMR is: :CH4 \+ H2O → CO + 3H2 Steam can be further used to convert CO to H2 via the water-gas shift reaction (WGS): :H2O + CO → CO2 \+ H2 The SMR reaction is endothermic, which requires heat input. The state-of-art SMR system places the tubular catalytic reactors in a furnace, in which fuel gas is burned to provide the required heat.
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In either scheme, the combustion of metal oxide by air in the chemical looping system provides the heat source that sustains the endothermic SMR reactions. In the chemical looping system, natural gas and the recycled off-gas from the pressure swing adsorption (PSA) of the SMR process system are used as the feedstock for the CLC fuel reactor operation with CO2 and the steam as the reaction products. The CLC-SMR concepts have mainly been studied from the perspective of the process simulation. It is seen that both schemes do not engage directly the chemical looping system as a means for syngas production.
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This procedure is known as Computer-Aided Cooling Curve Thermal Analysis. Advanced techniques use differential curves to locate endothermic inflection points such as gas holes, and shrinkage, or exothermic phases such as carbides, beta crystals, inter crystalline copper, magnesium silicide, iron phosphide's and other phases as they solidify. Detection limits seem to be around 0.01% to 0.03% of volume. In addition, integration of the area between the zero curve and the first derivative is a measure of the specific heat of that part of the solidification which can lead to rough estimates of the percent volume of a phase.
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If catabolism of alcohol goes all the way to completion, then, we have a very exothermic event yielding some of energy. If the reaction stops part way through the metabolic pathways, which happens because acetic acid is excreted in the urine after drinking, then not nearly as much energy can be derived from alcohol, indeed, only . At the very least, the theoretical limits on energy yield are determined to be to . It is also important to note that step 1 on this reaction is endothermic, requiring of alcohol, or about 3 molecules of adenosine triphosphate (ATP) per molecule of ethanol.
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The structure, bonding and acidity of Sn-beta zeolite has been studied using periodic DFT and it has been demonstrated that incorporation of Sn in BEA framework reduces the cohesive energy and is an endothermic process. Computational study of hydrogen storage materials, like magnesium hydrides using Born Oppenheimer molecular dynamics has been made. In particular, study of hydrogen desorption and the effect of dopants, Al and Si has been made.S.Shetty, Sourav Pal, D. G. Kanhere and A. Goursot, (Structural, Electronic and Bonding properties of zeolite Sn-Beta: A periodic density functional theory study, Chemistry: A European Journal, 12, 518-523 (2006).
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Additionally, this increase in temperature leads to an increase in basal metabolic temperature. The fish is now able to split ATP at a higher rate and ultimately can swim faster. The opah utilizes retia mirabilia to conserve heat, making it the newest addition to the list of regionally endothermic fish. Blood traveling through capillaries in the gills must carry cold blood due to their exposure to cold water, but retia mirabilia in the opah's gills are able to transfer heat from warm blood in arterioles coming from the heart that heats this colder blood in arterioles leaving the gills.
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The quantity of heat absorbed or given off during transformation is called the heat of formation. Heats of formations for solids and gases found in explosive reactions have been determined for a temperature of 25 °C and atmospheric pressure, and are normally given in units of kilojoules per gram-molecule. A positive value indicates that heat is absorbed during the formation of the compound from its elements; such a reaction is called an endothermic reaction. In explosive technology only materials that are exothermic—that have a net liberation of heat and have a negative heat of formation—are of interest.
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Removing only one hydrogen atom from the water molecule requires less than 1/2 the energy required to remove both hydrogen atoms based on enthalpy of formation calculations. If this could be accomplished using high voltage pulsed partial electrolysis, then the hydrogen gas generated could theoretically be burned with atmospheric oxygen for net energy gain as postulated by Brian Glass in his YouTube explanation. The law of conservation of energy is maintained as the byproducts of the partial electrolysis will ultimately be passed on to the environment and there will be an endothermic reaction with environmental molecules.
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The BMA process or Degussa process is a chemical process developed by the German chemical company Degussapatent literature for the production of hydrogen cyanide from methane and ammonia in presence of a platinum catalyst. Hydrogen cyanide is used in the chemical industry for the production of intermediate chemicals like acrylonitrile, methyl methacrylate, and adiponitrile. The name is abbreviated from Blausäure (hydrogen cyanide) from Methan (methane) and Ammoniak (ammonia) in German. The reaction equation is analog to the steam methane reforming (SMR) reaction of methane and water: :CH4 \+ NH3 -> HCN + 3 H2, ΔHR = 251 kJ / mol The reaction is extremely endothermic.
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Like all primary and secondary perfluoroalcohols, trifluoromethanol eliminates hydrogen fluoride in an endothermic reaction and forms carbonyl fluoride. : ⇌ + (I) At temperatures in the range of -120 °C, trifluoromethanol can be prepared from trifluoromethoxy chloride and hydrogen chloride: : + → + (II) In this reaction, the recombination of a partially positively charged chlorine atom (in trifluoromethoxy chloride) with a partially negatively charged chlorine atom (in hydrogen chloride) is used as elemental chlorine. The undesired products, by-products chlorine, hydrogen chloride, and chlorotrifluoromethane, can be removed by evaporation at -110 °C. Trifluoromethanol has a melting point of -82 °C and a calculated boiling point of about -20 °C.
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Simple Benson model of isobutylbenzene As stated above, BGIT can be used to calculate heats of formation, which are important in understanding the strengths of bonds and entire molecules. Furthermore, the method can be used to quickly estimate whether a reaction is endothermic or exothermic. These values are for gas-phase thermodynamics and typically at 298 K. Benson and coworkers have continued collecting data since their 1958 publication and have since published even more group increments, including strained rings, radicals, halogens, and more.S. W. Benson, Thermochemical Kinetics: Methods for the Estimation of Thermochemical Data and Rate Parameters 2d ed.
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There are only two known ways to permanently kill a zombie. One is completely burning the body (as seen in the cremation scene from The Return of the Living Dead), though burning the body releases Trioxin-laced smoke into the air, which can combine with clouds to create Trioxin-laced rain. Another way is electrocuting the undead until they cease to move or squirm (see Return of the Living Dead Part II). In the third film scientists invented an endothermic chemical dart that freezes the brain, incapacitating the zombie, but its effective duration is wildly unpredictable.
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The deepest portion of the solid experiencing heat transfer melts and begins phase transition from solid to gas in a foam zone. The gaseous propellant decomposes into simpler molecules in a surrounding fizz zone. Endothermic transformations in the foam zone and fizz zone require energy initially provided by the primer and subsequently released in a luminous outer flame zone where the simpler gas molecules react to form conventional combustion products like steam and carbon monoxide. The heat transfer rate of smokeless propellants increases with pressure; so the rate of gas generation from a given grain surface area increases at higher pressures.
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A study published in 2016 by T. Lyn Harrell, Alberto Pérez-Huerta and Celina Suarez showed that mosasaurs were endothermic. The study contradicted findings published in 2010 indicating mosasaurs were ectothermic. The 2010 study did not use warm-blooded animals for comparison but analogous groups of common marine animals. Based on comparisons with modern warm-blooded animals and fossils of known cold-blooded animals from the same time period, the 2016 study found mosasaurs likely had body temperatures similar to those of contemporary seabirds and were able to internally regulate their temperatures to remain warmer than the surrounding water.
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Tyrannosaurus, like most dinosaurs, was long thought to have an ectothermic ("cold-blooded") reptilian metabolism but was challenged by scientists like Robert T. Bakker and John Ostrom in the early years of the "Dinosaur Renaissance", beginning in the late 1960s. Tyrannosaurus rex itself was claimed to have been endothermic ("warm-blooded"), implying a very active lifestyle. Since then, several paleontologists have sought to determine the ability of Tyrannosaurus to regulate its body temperature. Histological evidence of high growth rates in young T. rex, comparable to those of mammals and birds, may support the hypothesis of a high metabolism.
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Scientific opinion about the life-style, metabolism and temperature regulation of dinosaurs has varied over time since the discovery of dinosaurs in the mid-19th century. The activity of metabolic enzymes varies with temperature, so temperature control is vital for any organism, whether endothermic or ectothermic. Organisms can be categorized as poikilotherms (poikilo – changing), which are tolerant of internal temperature fluctuations, and homeotherms (homeo – same), which must maintain a constant core temperature. Animals can be further categorized as endotherms, which regulate their temperature internally, and ectotherms, which regulate temperature by the use of external heat sources.
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Many bipedal dinosaurs possessed gracile leg bones with a short thigh relative to calf length. This is generally an adaptation to frequent sustained running, characteristic of endotherms which, unlike ectotherms, are capable of producing sufficient energy to stave off the onset of anaerobic metabolism in the muscle.Fastovsky & Weishampel 2009, p.252. Bakker and Ostrom both pointed out that all dinosaurs had erect hindlimbs and that all quadrupedal dinosaurs had erect forelimbs; and that among living animals only the endothermic ("warm-blooded") mammals and birds have erect limbs (Ostrom acknowledged that crocodilians' occasional "high walk" was a partial exception).
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Because endothermy allows refined neuromuscular control, and because brain matter requires large amounts of energy to sustain, some speculate that increased brain size indicates increased activity and, thus, endothermy. The encephalization quotient (EQ) of dinosaurs, a measure of brain size calculated using brain endocasts, varies on a spectrum from bird-like to reptile-like. Using EQ alone, coelosaurs appear to have been as active as living mammals, while theropods and ornithopods fall somewhere between mammals and reptiles, and other dinosaurs resemble reptiles. A study published by Roger Seymour in 2013 added more support to the idea that dinosaurs were endothermic.
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The species is endothermic, maintaining its body temperature at about 32 °C (90 °F), lower than most mammals, even while foraging for hours in water below 5 °C (41 °F). Dives normally last around 30 seconds, but can last longer, although few exceed the estimated aerobic limit of 40 seconds. Recovery at the surface between dives commonly takes from 10 to 20 seconds. When not in the water, the platypus retires to a short, straight resting burrow of oval cross- section, nearly always in the riverbank not far above water level, and often hidden under a protective tangle of roots.
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It is the word "released" within the definition "energy released" that supplies the negative sign to ΔE. Confusion arises in mistaking Eea for a change in energy, ΔE, in which case the positive values listed in tables would be for an endo- not exo- thermic process. The relation between the two is Eea = −ΔE(attach). However, if the value assigned to Eea is negative, the negative sign implies a reversal of direction, and energy is required to attach an electron. In this case, the electron capture is an endothermic process and the relationship, Eea = −ΔE(attach) is still valid.
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In both cases the change is endothermic, meaning that the system absorbs energy. For example, when water evaporates, energy is required for the water molecules to overcome the forces of attraction between them, the transition from water to vapor requires an input of energy. If the vapor then condenses to a liquid on a surface, then the vapor's latent energy absorbed during evaporation is released as the liquid's sensible heat onto the surface. The large value of the enthalpy of condensation of water vapor is the reason that steam is a far more effective heating medium than boiling water, and is more hazardous.
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The cooling and fizzing sensation results from the endothermic reaction between sodium carbonate and a weak acid, commonly citric acid, releasing carbon dioxide gas, which occurs when the sherbet is moistened by saliva. In China, it is used to replace lye-water in the crust of traditional Cantonese moon cakes, and in many other Chinese steamed buns and noodles. In cooking, it is sometimes used in place of sodium hydroxide for lyeing, especially with German pretzels and lye rolls. These dishes are treated with a solution of an alkaline substance to change the pH of the surface of the food and improve browning.
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Concrete cannot, by itself, withstand severe hydrocarbon fires. In the Channel Tunnel that connects the United Kingdom and France, an intense fire broke out and reduced the concrete lining in the undersea tunnel down to about 50 mm. In ordinary building fires, concrete typically achieves excellent fire-resistance ratings, unless it is too wet, which can cause it to crack and explode. For unprotected concrete, the sudden endothermic reaction of the hydrates and unbound humidity inside the concrete generates pressure high enough to spall off the concrete, which falls in small pieces on the floor of the tunnel.
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Micro-Vett Electric Porter The company from Imola continues the production of Rascal, but, given the lack of involvement of the vehicle manufacturer, approached Piaggio with which, starting from 1994, launches a collaboration for the electrification of Porter. This vehicle, thanks to purchasing incentives, meets a great success in the Italian market and it was manufactured from 1994 to 2003 in about 5,000 units. The lead-acid batteries provide a range of 60 km and a top speed of 65 km/h. Piaggio delivers the vehicles without endothermic engine to Micro-Vett and here they're converted into electric.
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Endothermic/homeothermic animals can be optimally active at more times during the diurnal cycle in places of sharp temperature variations between day and night and during more of the year in places of great seasonal differences of temperature. This is accompanied by the need to expend more energy to maintain the constant internal temperature and a greater food requirement. Endothermy may be important during reproduction, for example, in expanding the thermal range over which a species can reproduce, as embryos are generally intolerant of thermal fluctuations that are easily tolerated by adults. Endothermy may also provide a protection against fungal infection.
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Endothermic animals mostly use internal heat production through metabolic active organs and tissues (liver, kidney, heart, brain, muscle) or specialized heat producing tissues like brown adipose tissue (BAT). In general, endotherms therefore have higher metabolic rates than ectotherms at a given body mass. As a consequence they would also need higher food intake rates, which may limit abundance of endotherms more than ectotherms. Because ectotherms depend on environmental conditions for body temperature regulation, they typically are more sluggish at night and in the morning when they emerge from their shelters to heat up in the first sunlight.
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Painter's Putty is typically a linseed oil-based product used for filling holes, minor cracks and defacements in wood only. Putties can also be made intumescent, in which case they are used for firestopping as well as for padding of electrical outlet boxes in fire-resistance rated drywall assemblies. In the latter case, hydrates in the putty produce an endothermic reaction to mitigate heat transfer to the unexposed side. In woodworking, water-based putties are more commonly used, as these emit very little odour, are more easily cleaned up and are compatible with water-based and latex sealers.
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This sequence of reactions can be understood by thinking of the two interacting carbon nuclei as coming together to form an excited state of the 24Mg nucleus, which then decays in one of the five ways listed above. The first two reactions are strongly exothermic, as indicated by the large positive energies released, and are the most frequent results of the interaction. The third reaction is strongly endothermic, as indicated by the large negative energy indicating that energy is absorbed rather than emitted. This makes it much less likely, yet still possible in the high-energy environment of carbon burning.
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This exemplifies a fundamental difference between germanium and the other Group 14 elements carbon and silicon (carbon dioxide and silicon dioxide do not exhibit the same catalytic properties). 2Ge2H6 \+ 7O2 → 4GeO2 \+ 6H2O In liquid ammonia, digermane undergoes disproportionation. Ammonia acts as a weakly basic catalyst. Products of the reaction are hydrogen, germane, and a solid polymeric germanium hydride. Pyrolysis of digermane is proposed to follow multiple steps: :Ge2H6 → 2GeH3 :GeH3 \+ Ge2H6 → GeH4 \+ Ge2H5 :Ge2H5 → GeH2 \+ GeH3 :GeH2 → Ge + H2 :2GeH2 → GeH4 \+ Ge :nGeH2 → (GeH2)n This pyrolysis has been found to be more endothermic than the pyrolysis of disilane.
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Being endothermic they may have needed it for thermoregulation, but fossil evidence of their fur (or lack thereof) has been elusive. Modern mammals have Harderian glands secreting lipids to coat their fur, but the telltale imprint of this structure is only found from the primitive mammal Morganucodon and onwards. Nonetheless, recent studies on Permian synapsid coprolites show that more basal therapsids had fur, and at any rate fur was already present in Mammaliaformes such as Castorocauda and Megaconus. Marks in the upper and lower jaw of cynodonts have been interpreted as channels that supplied blood vessels and nerves to whiskers.
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Assuming it was endothermic, Ankylosaurus would have eaten of ferns per day, similar to the amount of dry vegetation a large elephant would consume. The requirements for nutrition could have been more effectively met if Ankylosaurus ate fruit, which its small, cusp-like teeth and the shape of its beak seem well adapted for, compared to for example Euoplocephalus. Certain invertebrates, which the small teeth may have been adapted for handling, could also have provided supplemental nutrition. Fossils of Ankylosaurus teeth exhibit wear on the face of the crown rather than on the tip of the crown, as in nodosaurid ankylosaurs.
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They found that color in dinosaurs seem to be slightly connected with their physiology. While some species of living reptiles (lizards or crocodiles, which are ectothermic) have less diversity in the shape of melanosomes and darker color ranges, some maniraptorans, birds and mammals (which are endothermic) have an increased diversity of melanosome shapes and more vivid colors. The examined specimen of Beipaosaurus, BMNHC PH000911, preserves feather impressions which are located in the neck area. These are filamentous/sparse in structure and the sampled melanosomes were sphere-shaped and inferred to had a brownish colouration like those in modern reptiles which fall within the range of dark brownish colourations.
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In India, mammals comprise 410 species, 186 genera, 45 families and 13 orders of which nearly 89 species are listed as threatened in the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Animals (IUCN 2006). This includes two species that are locally extinct from India viz. Acinonyx jubatus and Rhinoceros sondaicus. The mammals are the class of vertebrate animals characterized by the presence of mammary glands, which in females produce milk for the nourishment of young; the presence of hair or fur; specialized teeth; the presence of a neocortex region in the brain; and endothermic or "warm-blooded" bodies.
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Perovskite are mixed metal oxide with a well-defined cubic structure and a general formula of ABO3, where A is an alkaline earth or lanthanide element and B is a transition metal. These materials are attractive for CO2 separation because of the tunability of the metal sites as well as their stabilities at elevated temperatures. The separation of CO2 from N2 was investigated with an α-alumina membrane impregnated with BaTiO3. It was found that adsorption of CO2 was favorable at high temperatures due to an endothermic interaction between CO2 and the material, promoting mobile CO2 that enhanced CO2 adsorption-desorption rate and surface diffusion.
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Unlike roughly contemporary environments in Europe and Asia, North America appeared to lack very small carnivorous dinosaurs. In modern ecosystems dominated by endothermic mammals, small animal species outnumber larger ones. Since dinosaurs are also presumed to have been endotherms, the lack of small species and great number of known large species in North America was unusual. Hesperonychus helped to fill that gap, especially since, given the number of fragmentary remains and claws that have been collected (representing at least ten distinct specimens, compared to thirty of the contemporary Saurornitholestes and two of Dromaeosaurus), it appears to have been a very common feature of the Dinosaur Park Formation environment.
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Dye-sub printing is a digital printing technology using full color artwork that works with polyester and polymer-coated substrates. Also referred to as digital sublimation, the process is commonly used for decorating apparel, signs and banners, as well as novelty items such as cell phone covers, plaques, coffee mugs, and other items with sublimation-friendly surfaces. The process uses the science of sublimation, in which heat and pressure are applied to a solid, turning it into a gas through an endothermic reaction without passing through the liquid phase. In sublimation printing, unique sublimation dyes are transferred to sheets of “transfer” paper via liquid gel ink through a piezoelectric print head.
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It prefers indigenous forests, where undergrowth is sparse and trees are more than 4m tall, but may also be found in stands of Quercus robur, Populus deltoides, pine and eucalyptus. It is also unusually found in dense riverine bushes in KwaZulu-Natal and Eastern Cape. Males usually call from a position a few meters above the ground on a shady limb of a tree, with a good view of the immediate surroundings and potential predators. Males often sing in chorus to attract mates, particularly at dusk and dawn, enabled to do this by an endothermic metabolism which rises to more than 22 °C above ambient temperature.
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The relationship between the molar lattice energy and the molar lattice enthalpy is given by the following equation: :\Delta U=\Delta H -p\Delta V_m, where \Delta U is the molar lattice energy, \Delta H the molar lattice enthalpy and \Delta V_m the change of the volume per mole. Therefore, the lattice enthalpy further takes into account that work has to be performed against an outer pressure p. Some textbooks and the commonly used CRC Handbook of Chemistry and Physics define lattice energy (and enthalpy) with the opposite sign, i.e. as the energy required to convert the crystal into infinitely separated gaseous ions in vacuum, an endothermic process.
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The reaction is given as: Steam reforming is a good source for production of hydrogen, but the reaction is endothermic. The reaction can be carried out over a copper-based catalyst, but the reaction mechanism is dependent on the catalyst. For a copper-based catalyst two different reaction mechanisms have been proposed, a decomposition-water-gas shift sequence and a mechanism that proceeds via methanol dehydrogenation to methyl formate. The first mechanism aims at methanol decomposition followed by the WGS reaction and has been proposed for the Cu/ZnO/Al2O3: The mechanism for the methyl format reaction can be dependent of the composition of the catalyst.
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Growth can be reconstructed based on the inner bone structure. The first such study on Confuciusornis, presented by Fucheng Zhang and colleagues in 1998, used scanning electron microscopy to analyze a femur in cross section. Because the bone was well vascularized (contained many blood vessels) and showed only a single line of arrested growth (growth ring), these authors determined that growth must have been fast and continuous as in modern birds, and that Confuciusornis must have been endothermic. Zhang and colleagues corroborated this claim in a subsequent paper, stating that the bone structure was unlike that of a modern ectothermic alligator but similar to the feathered non-avian dinosaur Beipiaosaurus.
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The rate coefficients and products of many high-temperature gas-phase reactions change if an inert gas is added to the mixture; variations on this effect are called fall-off and chemical activation. These phenomena are due to exothermic or endothermic reactions occurring faster than heat transfer, causing the reacting molecules to have non-thermal energy distributions (non- Boltzmann distribution). Increasing the pressure increases the heat transfer rate between the reacting molecules and the rest of the system, reducing this effect. Condensed-phase rate coefficients can also be affected by pressure, although rather high pressures are required for a measurable effect because ions and molecules are not very compressible.
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If ΔS and/or T are small, the condition ΔG < 0 may imply that ΔH < 0, which would indicate an exothermic reaction. However, this is not required; endothermic reactions can proceed spontaneously if the TΔS term is large enough. Moreover, the slopes of the derivatives of ΔG and ΔH converge and are equal to zero at T = 0\. This ensures that ΔG and ΔH are nearly the same over a considerable range of temperatures and justifies the approximate empirical Principle of Thomsen and Berthelot, which states that the equilibrium state to which a system proceeds is the one that evolves the greatest amount of heat, i.e.
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Tantalum capacitors are, under some conditions, prone to self-destruction by thermal runaway. The capacitor typically consists of a sintered tantalum sponge acting as the anode, a manganese dioxide cathode, and a dielectric layer of tantalum pentoxide created on the tantalum sponge surface by anodizing. It may happen that the tantalum oxide layer has weak spots that undergo dielectric breakdown during a voltage spike. The tantalum sponge then comes into direct contact with the manganese dioxide, and increased leakage current causes localized heating; usually, this drives an endothermic chemical reaction that produces manganese(III) oxide and regenerates (self-heals) the tantalum oxide dielectric layer.
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Masonry walls have an endothermic effect of its hydrates, as in chemically bound water, unbound moisture from the concrete block, and the poured concrete if the hollow cores inside the blocks are filled. Masonry can withstand temperatures up to 1,000ºF and it can withstand direct exposure to fire for up to 4 hours. In addition to that, concrete masonry keeps fires contained to their room of origin 93% of the time. For those reasons, concrete masonry units hold the highest fire class flame spread classification, a Class A. Masonry buildings can also be built to increase safety by reducing fire damage, such as the use of fire cuts during construction.
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With the help of her robotic assistant Snowball, Mei works to get a signal out to let someone know of her survival and rescue her before she freezes to death, constructing an Endothermic Blaster in the process. She intercepts Winston's recall message and commits herself to the cause, beginning her journey with Snowball back to civilization. Honor and Glory debuted at BlizzCon 2017 on November 3, 2017. The animation focuses on Reinhardt, showing him remembering his time as part of the Crusaders, when he helped to defend a German town from an army of Omnics under his commander, Balderich von Adler, whom had just been selected to join the Overwatch team.
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In this context, the survival of other endothermic animals, such as some birds and mammals, could be due, among other reasons, to their smaller needs for food, related to their small size at the extinction epoch. Whether the extinction occurred gradually or suddenly has been debated, as both views have support from the fossil record. A study of 29 fossil sites in Catalan Pyrenees of Europe in 2010 supports the view that dinosaurs there had great diversity until the asteroid impact, with more than 100 living species. More recent research indicates that this figure is obscured by taphonomic biases and the sparsity of the continental fossil record.
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Ammonium nitrate is used in some instant cold packs, as its dissolution in water is highly endothermic. It also was used, in combination with independently explosive "fuels" such as guanidine nitrate,Airbag Compound Has Vexed Takata for Years – The New York Times as a cheaper (but less stable) alternative to 5-aminotetrazole in the inflators of airbags manufactured by Takata Corporation, which were recalled as unsafe after killing 14 people.A Cheaper Airbag, and Takata's Road to a Deadly Crisis. – The New York Times A solution of ammonium nitrate with nitric acid called Cavea-b showed promise for use in spacecraft as a more energetic alternative to the common monopropellant hydrazine.
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Assigning the efficiency of syngas production in the integrated cycle a value equal to a regular syngas production efficiency through steam-methane reforming (some part of methane is combusted to drive endothermic reforming), the net-power generation efficiency (with accounting for the consumed electricity required to separate air) can reach levels higher than 60% at a maximum temperature in the cycle (at the gas turbine inlet) of about 1300 °C. The natural gas integrated cycle with adiabatic catalytic reactor was firstly proposed at Chemistry Department of Moscow State Lomonosov University (Russia) in Prof. M. Safonov (late) group by M. Safonov, M. Granovskii, and S. Pozharskii in 1993.
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Closed systems containing substances undergoing a reversible chemical reaction can also exhibit negative feedback in accordance with Le Chatelier's principle which shift the chemical equilibrium to the opposite side of the reaction in order to reduce a stress. For example, in the reaction : N2 \+ 3 H2 ⇌ 2 NH3 \+ 92 kJ/mol If a mixture of the reactants and products exists at equilibrium in a sealed container and nitrogen gas is added to this system, then the equilibrium will shift toward the product side in response. If the temperature is raised, then the equilibrium will shift toward the reactant side which, because the reverse reaction is endothermic, will partially reduces the temperature.
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Polonium hydride is a more covalent compound than most metal hydrides because polonium straddles the border between metals and metalloids and has some nonmetallic properties. It is intermediate between a hydrogen halide like hydrogen chloride and a metal hydride like stannane. It should have properties similar to that of hydrogen selenide and hydrogen telluride, other borderline hydrides. It is very unstable at room temperature and must be stored at freezer temperatures to prevent reversion to elemental polonium and hydrogen; this is because it is an endothermic compound, like the lighter hydrogen telluride and hydrogen selenide, and decomposes into its constituent elements, releasing heat in the process.
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The "spent" catalyst then flows into a fluidized-bed regenerator where air (or in some cases air plus oxygen) is used to burn off the coke to restore catalyst activity and also provide the necessary heat for the next reaction cycle, cracking being an endothermic reaction. The "regenerated" catalyst then flows to the base of the riser, repeating the cycle. The gasoline produced in the FCC unit has an elevated octane rating but is less chemically stable compared to other gasoline components due to its olefinic profile. Olefins in gasoline are responsible for the formation of polymeric deposits in storage tanks, fuel ducts and injectors.
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Throughout its history, Micro-Vett implemented many electric- powered prototypes, including the bus Albatros in collaboration with the local public transport company of Rimini, a Ducato Hybrid Bimodal Camper by Micro- Vett with endothermic engine on the front axle and electric motor on the rear axle in partnership with Al-Ko, a three-wheels motorcycle, a bimodal hearse, an all-electric excavator in collaboration with Venieri, a bimodal boat for carrying 70 people, etc.. Micro-Vett also developed CHAdeMO protocols for rapid charging of its vehicles at 50 kW; moreover the company also attended many national and European projects, including Green eMotion under the 7th European framework program.
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If Giraffatitan was endothermic (warm-blooded), it would have taken an estimated ten years to reach full size, if it were instead poikilothermic (cold- blooded), then it would have required over 100 years to reach full size. As a warm-blooded animal, the daily energy demands of Giraffatitan would have been enormous; it would probably have needed to eat more than ~182 kg (400 lb) of food per day. If Giraffatitan was fully cold-blooded or was a passive bulk endotherm, it would have needed far less food to meet its daily energy needs. Some scientists have proposed that large dinosaurs like Giraffatitan were gigantotherms.
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In combination with entropy determinations, it is also used to predict whether a reaction is spontaneous or non-spontaneous, favorable or unfavorable. Endothermic reactions absorb heat, while exothermic reactions release heat. Thermochemistry coalesces the concepts of thermodynamics with the concept of energy in the form of chemical bonds. The subject commonly includes calculations of such quantities as heat capacity, heat of combustion, heat of formation, enthalpy, entropy, free energy, and calories. The world's first ice-calorimeter, used in the winter of 1782–83, by Antoine Lavoisier and Pierre-Simon Laplace, to determine the heat evolved in various chemical changes; calculations which were based on Joseph Black’s prior discovery of latent heat.
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An endotherm (from Greek ἔνδον endon "within" and θέρμη thermē "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat set free by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly an incidental product of the animal's routine metabolism, but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production. Examples include special- function muscular exertion such as shivering, and uncoupled oxidative metabolism such as within brown adipose tissue. Only birds and mammals are extant universally endothermic groups of animals.
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It is thought that the evolution of endothermia was crucial in the development of eutherian mammalian species diversity in the Mesozoic period. Endothermia gave the early mammals the capacity to be active during night time while maintaining small body sizes. Adaptations in photoreception and the loss of UV protection characterizing modern eutherian mammals are understood as adaptations for an originally nocturnal lifestyle, suggesting that the group went through an evolutionary bottle neck (the nocturnal bottleneck hypothesis). This could have avoided predator pressure from diurnal reptiles and dinosaurs, although some predatory dinosaurs, being equally endothermic, might have adapted a nocturnal lifestyle in order to prey on those mammals.
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SOFCs can also be fueled by externally reforming heavier hydrocarbons, such as gasoline, diesel, jet fuel (JP-8) or biofuels. Such reformates are mixtures of hydrogen, carbon monoxide, carbon dioxide, steam and methane, formed by reacting the hydrocarbon fuels with air or steam in a device upstream of the SOFC anode. SOFC power systems can increase efficiency by using the heat given off by the exothermic electrochemical oxidation within the fuel cell for endothermic steam reforming process. Additionally, solid fuels such as coal and biomass may be gasified to form syngas which is suitable for fueling SOFCs in integrated gasification fuel cell power cycles.
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They used their incisors to help dig and unearth buried plants. The way they ate and the shape of their teeth demonstrate that Tritylodons were probably primarily herbivorous (though some tritylodontids show evidence of more omnivorous diets, and modern analogues like rodents tend to be more omnivorous than their dentitions lead on). Any of the Tritylodonts including Tritylodon were warm-blooded or endothermic. Like most non-placental mammalimorphs, it had epipubic bones, aiding in its erect gait but preventing the expansion of the abdomen, making it unable to go through prolonged pregnancy and instead give birth to larval young like modern marsupials and monotremes.
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Further information would be needed in order to predict the structure or characteristics of the transition state. Case (c) depicts the potential diagram for an endothermic reaction, in which, according to the postulate, the transition state should more closely resemble that of the intermediate or the product. Another significance of Hammond’s postulate is that it permits us to discuss the structure of the transition state in terms of the reactants, intermediates, or products. In the case where the transition state closely resembles the reactants, the transition state is called “early” while a “late” transition state is the one that closely resembles the intermediate or the product. An example of the “early” transition state is chlorination.
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Night monkeys also benefit from a nocturnal life style as activity in the night provides a degree of protection from the heat of the day and the thermoregulation difficulties associated. Although night monkey, like all primates are endothermic, meaning they are able to produce their own heat, night monkeys undergo behavioural thermoregulation in order to minimize energy expenditure. During the hottest points of the day, night monkeys are resting and therefore expending less energy in the form of heat. As they carefully construct their nests, night monkeys also benefit from the shade provided by the forest canopy which enables them to cool their bodies through the act of displacing themselves into a shady area.
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Unlike a sponge, foams from this process are closed-cell, meaning it's waterproof and resists mold, mildew and bacteria from entering the material. It is also cross-linked, which means that the cells are connected in a way that makes the foam strong and durable with high tear and tensile strength. All polyolefin elastomers are also resistant to most chemicals, which allow the products to not only be used in a chemical environment, but also very cleanable with most household cleaners. The process itself is known to be very interesting, because the injected compound is not foam, until an endothermic reaction in a hot mold activates the blowing agents, resulting in an expanded foam part.
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Further information would be needed in order to predict the structure or characteristics of the transition state. Case (c) depicts the potential diagram for an endothermic reaction, in which, according to the postulate, the transition state should more closely resemble that of the intermediate or the product. Another significance of Hammond's postulate is that it permits us to discuss the structure of the transition state in terms of the reactants, intermediates, or products. In the case where the transition state closely resembles the reactants, the transition state is called “early” while a “late” transition state is the one that closely resembles the intermediate or the product. An example of the “early” transition state is chlorination.
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Cannibalism has been reported in both captive and wild juveniles and the species is known to scavenge on dead frogs and rodents. Just a few of the documented ectothermic prey items include: centipedes (Scolopendra), beetles (Coleoptera), grasshoppers (Orthoptera), crayfish, eels (Synbranchus); caecilians (Dermophis), frogs (Eleutherodactylus, Leptodactylus, Smilisca), toads (Rhinella), amphisbaenians (Amphisbaena), lizards (Ameiva, Anolis, Ctenosaura), and snakes (Bothrops, Erythrolamprus, Ninia). Endothermic prey species include: bay wren (Cantorchilus nigricapillus), grey-headed tanager (Eucometis penicillata), wren (Troglodytes), blue-black grassquit (Volatinia jacarina), Central American woolly opossum (Caluromys derbianus), common opossum (Didelphis marsupialis), Desmarest's spiny pocket mouse (Heteromys desmarestianus), dusky rice rat (Melanomys caliginosus), Rothschild's porcupine (Coendou rothschildi), Brazilian cottontail (Sylvilagus brasiliensis), and least shrew (Cryptotis parva).
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Dark green crystals of nickelocene, sublimed and freshly deposited on a cold finger Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. Sublimation is an endothermic process that occurs at temperatures and pressures below a substance's triple point in its phase diagram, which corresponds to the lowest pressure at which the substance can exist as a liquid. The reverse process of sublimation is deposition or desublimation, in which a substance passes directly from a gas to a solid phase. Sublimation has also been used as a generic term to describe a solid-to-gas transition (sublimation) followed by a gas-to-solid transition (deposition).
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Triple-alpha process Beryllium-8 is unbound with respect to alpha emission by 92 keV; it is a resonance having a width of 6 eV. The nucleus of helium-4 is particularly stable, having a doubly magic configuration and larger binding energy per nucleon than 8Be. As the total energy of 8Be is greater than that of two alpha particles, the decay into two alpha particles is energetically favorable, and the synthesis of 8Be from two 4He nuclei is endothermic. The decay of 8Be is facilitated by the structure of the 8Be nucleus; it is highly deformed, and is believed to be a molecule-like cluster of two alpha particles that are very easily separated.
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Depending on whether the reaction between the titrant and analyte is exothermic or endothermic, the temperature will either rise or fall during the titration. When all analyte has been consumed by reaction with the titrant, a change in the rate of temperature increase or decrease reveals the equivalence point and an inflection in the temperature curve can be observed. The equivalence point can be located precisely by employing the second derivative of the temperature curve. The software used in modern automated thermometric titration systems employ sophisticated digital smoothing algorithms so that "noise" resulting from the highly sensitive temperature probes does not interfere with the generation of a smooth, symmetrical second derivative "peak" which defines the endpoint.
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The final stage involves hydrolysis of the purified ketazine: :Me(Et)C=NN=C(Et)Me + 2 H2O → 2 Me(Et)C=O + N2H4 The hydrolysis of the azine is acid-catalyzed, hence the need to isolate the azine from the initial ammonia-containing reaction mixture. It is also endothermic,. and so requires an increase in temperature (and pressure) to shift the equilibrium in favour of the desired products: ketone (which is recycled) and hydrazine hydrate. The reaction is carried out by simple distillation of the azeotrope: typical conditions are a pressure of 8 bar and temperatures of 130 °C at the top of the column and 179 °C at the bottom of the column.
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Arsenic makes arsenic acid with concentrated nitric acid, arsenous acid with dilute nitric acid, and arsenic trioxide with concentrated sulfuric acid; however, it does not react with water, alkalis, or non-oxidising acids. Arsenic reacts with metals to form arsenides, though these are not ionic compounds containing the As3− ion as the formation of such an anion would be highly endothermic and even the group 1 arsenides have properties of intermetallic compounds. Like germanium, selenium, and bromine, which like arsenic succeed the 3d transition series, arsenic is much less stable in the group oxidation state of +5 than its vertical neighbors phosphorus and antimony, and hence arsenic pentoxide and arsenic acid are potent oxidizers.
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One of the adaptations that allow bluefin tunas to have large migratory patterns is their endothermic nature, whereby they conserve heat in their blood and prevent its loss to the environment. They maintain their body temperature above the ambient water temperature in order to improve their locomotor muscle efficiency, especially at high speeds and when pursuing prey below the thermocline region. It has been hypothesized that tunas can rapidly alter their whole-body thermal conductivity by at least two orders of magnitude. This is done by disengaging the heat exchangers to allow rapid warming as the tuna ascend from cold water into warmer surface waters, and are then reactivated to conserve heat when they return into the depths.
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It is possible that small dinosaurs (other than birds) did survive, but they would have been deprived of food, as herbivorous dinosaurs would have found plant material scarce and carnivores would have quickly found prey in short supply. The growing consensus about the endothermy of dinosaurs (see dinosaur physiology) helps to understand their full extinction in contrast with their close relatives, the crocodilians. Ectothermic ("cold- blooded") crocodiles have very limited needs for food (they can survive several months without eating), while endothermic ("warm-blooded") animals of similar size need much more food to sustain their faster metabolism. Thus, under the circumstances of food chain disruption previously mentioned, non- avian dinosaurs died out, while some crocodiles survived.
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Cross-section through the trunk of a porbeagle (orientation is belly-up); note the central red muscles. Like other members of its family, the porbeagle is endothermic; metabolic heat generated by its red muscles is conserved within the body by specialized systems of blood vessels called retia mirabilia (Latin for "wonderful nets"; singular rete mirabile), that act as highly efficient countercurrent heat exchangers. The porbeagle has several rete mirabile systems: the orbital retia accessing its brain and eyes, the lateral cutaneous retia accessing its swimming muscles, the suprahepatic rete accessing its viscera, and the kidney rete. Among sharks, the porbeagle's capacity for elevating body temperature is second only to the salmon shark's.
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The Hammond–Leffler postulate states that the structure of the transition state more closely resembles either the products or the starting material, depending on which is higher in enthalpy. A transition state that resembles the reactants more than the products is said to be early, while a transition state that resembles the products more than the reactants is said to be late. Thus, the Hammond–Leffler Postulate predicts a late transition state for an endothermic reaction and an early transition state for an exothermic reaction. A dimensionless reaction coordinate that quantifies the lateness of a transition state can be used to test the validity of the Hammond–Leffler postulate for a particular reaction.
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Asbestos was one material historically used for fireproofing, either on its own, or together with binders such as cement, either in sprayed form or in pressed sheets, or as additives to a variety of materials and products, including fabrics for protective clothing and building materials. Because the material was later proven to cause cancer in the long run, a large removal-and-replacement industry has been established. Endothermic materials have also been used to a large extent and are still in use today, such as gypsum, concrete and other cementitious products. More highly evolved versions of these are used in aerodynamics, intercontinental ballistic missiles (ICBMs) and re-entry vehicles, such as the space shuttles.
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Sublimation (phase transition) is the transition of a substance directly from the solid to the gas phase without passing through an intermediate liquid phase. Sublimation is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point in its phase diagram. In this case, ink is transferred to a base layer, fibreglass for example, through heat and pressure, the result is a full color graphic that will not come off as easily as the more common heat transfers. This application is often found with bamboo boards and composite construction longboards where fibreglass can allow for various degrees of flex or stiffness depending on the ride you're looking for, cruising and carving versus slalom and downhill.
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FloSafe is an air flow technology that helps in protection against extreme heat; HydroSafe also helps with heat dissipation, but the primary role is in protecting against salt and fresh water contact and immersion; DataCast is an endothermic insulation technology using "trapped water molecules" and is a primary heat protection layer. In July 2008, ioSafe selected Fujitsu 2.5 inch hard disk drives (HDD) for its ioSafe 3.5 series, the first "disaster protected internal 3.5 inch SATA HDD". The company added its patented rugged case and configured the drives to be used in 3.5 inch HDD hardware bays. The following year, 2009, the company introduced the ioSafe Solo, a ruggedized external hard drive using an internal hard drive as its storage medium.
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Bergmann’s rule states that endothermic animal subspecies living in colder climates have larger bodies than that of the subspecies living in warmer climates. Individuals with larger bodies are better suited for colder climates because larger bodies produce more heat due to having more cells, and have a smaller surface area to volume ratio compared to smaller individuals, which reduces heat loss. A study by Frederick Foster and Mark Collard found that Bergmann’s rule can be applied to humans when the latitude and temperature between groups differ widely. Allen’s rule is a biological rule that says the limbs of endotherms are shorter in cold climates and longer in hot climates. Limb length affects the body’s surface area, which helps with thermoregulation.
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Solid oxide electrolyzer cells operate at temperatures which allow high-temperature electrolysisA reversible planar solid oxide fuel-assisted electrolysis cell to occur, typically between 500 and 850 °C. These operating temperatures are similar to those conditions for an SOFC. The net cell reaction yields hydrogen and oxygen gases. The reactions for one mole of water are shown below, with oxidation of water occurring at the anode and reduction of water occurring at the cathode. Anode: O2− → 1/2O2 \+ 2e− Cathode: H2O + 2e− → H2 \+ O2− Net Reaction: H2O → H2 \+ 1/2O2 Electrolysis of water at 298 K (25 °C) requires 285.83 kJ of energy per mole in order to occur,Electrolysis of Water and the reaction is increasingly endothermic with increasing temperature.
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The first commercial thermoplastic LSZH material for cable jacketing was invented by Richard Skipper in 1979 and patented by Raychem Corporation.United States Patent 4322575 This invention resolved the challenge of incorporating sufficient inorganic filler, aluminium trihydrate (ALTH), into an appropriate thermoplastic matrix to suppress the fire and allow a char to be formed, which reduced emission of poisonous carbon gases and also smoke and carbon particles, whilst maintaining electrical insulation properties and physical properties required by the end application. The preferred inorganic filler to achieve flame retardation continues to be aluminium trihydrate (ALTH). In the event of a fire this material undergoes an endothermic chemical reaction that absorbs heat energy and releases steam when the compound reaches a certain temperature.
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The independent loss of the pineal foramen in advanced therocephalians and cynodonts across the Permo-Triassic boundary has been suggested to be a consequence of developing endothermic (i.e. warm blooded) metabolisms, something inferred not to have occurred in the contemporary dicynodonts or gorgonopsians. The independent loss of the pineal foramen in Thliptosaurus and other kistecephalian dicynodonts may support an alternative hypothesis for the loss of the pineal foramen in therapsids. It's possible that changing global environmental conditions at the end of the Permian, such as global warming and the movement of the continents towards the equator, meant that less control was needed over thermoregulation in therapsids like Thliptosaurus, decreasing the need for the pineal foramen until it was ultimately lost.
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A recalculation, using corrected formulae, resulted in a speed of half a metre per second (1.8 km/h) for a cold-blooded plesiosaur and one and a half metres per second (5.4 km/h) for an endothermic plesiosaur. Even the highest estimate is about a third lower than the speed of extant Cetacea. Massare also tried to compare the speeds of plesiosaurs with those of the two other main sea reptile groups, the Ichthyosauria and the Mosasauridae. She concluded that plesiosaurs were about twenty percent slower than advanced ichthyosaurs, which employed a very effective tunniform movement, oscillating just the tail, but five percent faster than mosasaurids, which were assumed to swim with an inefficient anguilliform, eel-like, movement of the body.
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The second way to produce hydrogen from methanol is by methanol decomposition: As the enthalpy shows, the reaction is endothermic and this can be taken further advantage of in the industry. This reaction is the opposite of the methanol synthesis from syngas, and the most effective catalysts seems to be Cu, Ni, Pd and Pt as mentioned before. Often, a Cu/ZnO-based catalyst is used at temperatures between 200 and 300 °C but a production of by-product as dimethyl ether, methyl format, methane and water is common. The reaction mechanism is not fully understood and there are two possible mechanism proposed (2002) : one producing CO2 and H2 by decomposition of formate intermediates and the other producing CO and H2 via a methyl formate intermediate.
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In the context of chemistry, energy is an attribute of a substance as a consequence of its atomic, molecular or aggregate structure. Since a chemical transformation is accompanied by a change in one or more of these kinds of structure, it is invariably accompanied by an increase or decrease of energy of the substances involved. Some energy is transferred between the surroundings and the reactants of the reaction in the form of heat or light; thus the products of a reaction may have more or less energy than the reactants. A reaction is said to be exothermic or exergonic if the final state is lower on the energy scale than the initial state; in the case of endothermic reactions the situation is the reverse.
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The regenerator operates at a temperature of about 715 °C and a pressure of about 2.41 bar, hence the regenerator operates at about 0.7 bar higher pressure than the reactor. The combustion of the coke is exothermic and it produces a large amount of heat that is partially absorbed by the regenerated catalyst and provides the heat required for the vaporization of the feedstock and the endothermic cracking reactions that take place in the catalyst riser. For that reason, FCC units are often referred to as being 'heat balanced'. The hot catalyst (at about 715 °C) leaving the regenerator flows into a catalyst withdrawal well where any entrained combustion flue gases are allowed to escape and flow back into the upper part to the regenerator.
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There are limits both of heat and cold that an endothermic animal can bear and other far wider limits that an ectothermic animal may endure and yet live. The effect of too extreme a cold is to decrease metabolism, and hence to lessen the production of heat. Both catabolic and anabolic pathways share in this metabolic depression, and, though less energy is used up, still less energy is generated. The effects of this diminished metabolism become telling on the central nervous system first, especially the brain and those parts concerning consciousness; both heart rate and respiration rate decrease; judgment becomes impaired as drowsiness supervenes, becoming steadily deeper until the individual loses consciousness; without medical intervention, death by hypothermia quickly follows.
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At temperatures close to 1000 °C, the mixed-valence compound forms. Higher temperatures give MnO. Hot concentrated sulfuric acid reduces the to manganese(II) sulfate: :2 + 2 → 2 + + 2 The reaction of hydrogen chloride with was used by Carl Wilhelm Scheele in the original isolation of chlorine gas in 1774: : + 4 HCl → + + 2 As a source of hydrogen chloride, Scheele treated sodium chloride with concentrated sulfuric acid. ::E ~~o~~ ((s) + 4 + 2 e− Mn2+ \+ 2 ) = +1.23 V ::E ~~o~~ ((g) + 2 e− 2 Cl−) = +1.36 V The standard electrode potentials for the half reactions indicate that the reaction is endothermic at pH = 0 (1 M []), but it is favoured by the lower pH as well as the evolution (and removal) of gaseous chlorine.
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However, the 24Mg produced in this reaction is the only magnesium left in the core when the carbon-burning process ends, as 23Mg is radioactive. The last reaction is also very unlikely since it involves three reaction products, as well as being endothermic — think of the reaction proceeding in reverse, it would require the three products all to converge at the same time, which is less likely than two-body interactions. The protons produced by the second reaction can take part in the proton-proton chain reaction, or the CNO cycle, but they can also be captured by 23Na to form 20Ne plus a 4He nucleus. In fact, a significant fraction of the 23Na produced by the second reaction gets used up this way.
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Born–Haber cycles are used primarily as a means of calculating lattice energy (or more precisely enthalpyThe difference between energy and enthalpy is very small and the two terms are interchanged freely in this article.), which cannot otherwise be measured directly. The lattice enthalpy is the enthalpy change involved in the formation of an ionic compound from gaseous ions (an exothermic process), or sometimes defined as the energy to break the ionic compound into gaseous ions (an endothermic process). A Born–Haber cycle applies Hess's law to calculate the lattice enthalpy by comparing the standard enthalpy change of formation of the ionic compound (from the elements) to the enthalpy required to make gaseous ions from the elements. This latter calculation is complex.
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A major industrial source of CO is producer gas, a mixture containing mostly carbon monoxide and nitrogen, formed by combustion of carbon in air at high temperature when there is an excess of carbon. In an oven, air is passed through a bed of coke. The initially produced CO2 equilibrates with the remaining hot carbon to give CO. The reaction of CO2 with carbon to give CO is described as the Boudouard reaction. Above 800 °C, CO is the predominant product: :CO2 \+ C → 2 CO (ΔH = 170 kJ/mol) Another source is "water gas", a mixture of hydrogen and carbon monoxide produced via the endothermic reaction of steam and carbon: :H2O + C → H2 \+ CO (ΔH = +131 kJ/mol) Other similar "synthesis gases" can be obtained from natural gas and other fuels.
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Transport reactions are classified according to the thermodynamics of the reaction between the solid and the transporting agent. When the reaction is exothermic, then the solid of interest is transported from the cooler end (which can be quite hot) of the reactor to a hot end, where the equilibrium constant is less favorable and the crystals grow. The reaction of molybdenum dioxide with the transporting agent iodine is an exothermic process, thus the MoO2 migrates from the cooler end (700 °C) to the hotter end (900 °C): :MoO2 \+ I2 MoO2I2 ΔHrxn < 0 (exothermic) Using 10 milligrams of iodine for 4 grams of the solid, the process requires several days. Alternatively, when the reaction of the solid and the transport agent is endothermic, the solid is transported from a hot zone to a cooler one.
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A reaction is said to be exothermic if the reaction releases heat to the surroundings; in the case of endothermic reactions, the reaction absorbs heat from the surroundings. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy. The speed of a chemical reaction (at given temperature T) is related to the activation energy E, by the Boltzmann's population factor e^{-E/kT} – that is the probability of a molecule to have energy greater than or equal to E at the given temperature T. This exponential dependence of a reaction rate on temperature is known as the Arrhenius equation. The activation energy necessary for a chemical reaction to occur can be in the form of heat, light, electricity or mechanical force in the form of ultrasound.
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Like other sauropods, Brachiosaurus was probably homeothermic (maintaining a stable internal temperature) and endothermic (controlling body temperature through internal means) at least while growing, meaning that it could actively control its body temperature ("warm-blooded"), producing the necessary heat through a high basic metabolic rate of its cells. Russel (1989) used Brachiosaurus as an example of a dinosaur for which endothermy is unlikely, because of the combination of great size (leading to overheating) and great caloric needs to fuel endothermy. Sander (2010) found that these calculations were based on incorrect body mass estimates and faulty assumptions on the available cooling surfaces, as the presence of large air sacs was unknown at the time of the study. These inaccuracies resulted in the overestimation of heat production and the underestimation of heat loss.
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The preheated feed mixture is then totally vaporized and heated to the reaction temperature (495–520 °C) before the vaporized reactants enter the first reactor. As the vaporized reactants flow through the fixed bed of catalyst in the reactor, the major reaction is the dehydrogenation of naphthenes to aromatics (as described earlier herein) which is highly endothermic and results in a large temperature decrease between the inlet and outlet of the reactor. To maintain the required reaction temperature and the rate of reaction, the vaporized stream is reheated in the second fired heater before it flows through the second reactor. The temperature again decreases across the second reactor and the vaporized stream must again be reheated in the third fired heater before it flows through the third reactor.
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Like other mammals, monotremes are endothermic with a high metabolic rate (though not as high as other mammals; see below); have hair on their bodies; produce milk through mammary glands to feed their young; have a single bone in their lower jaw; and have three middle-ear bones. In common with reptiles and marsupials, monotremes lack the connective structure (corpus callosum) which in placental mammals is the primary communication route between the right and left brain hemispheres. The anterior commissure does provide an alternate communication route between the two hemispheres, though, and in monotremes and marsupials it carries all the commissural fibers arising from the neocortex, whereas in placental mammals the anterior commissure carries only some of these fibers. Platypus Long-beaked echidna Diagram of a Monotreme Egg.
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Growth curves indicate that, as in mammals and birds, T. rex growth was limited mostly to immature animals, rather than the indeterminate growth seen in most other vertebrates. It has been indicated that the temperature difference may have been no more than 4 to 5 °C (7 to 9 °F) between the vertebrae of the torso and the tibia of the lower leg. This small temperature range between the body core and the extremities was claimed by paleontologist Reese Barrick and geochemist William Showers to indicate that T. rex maintained a constant internal body temperature (homeothermy) and that it enjoyed a metabolism somewhere between ectothermic reptiles and endothermic mammals. Later they found similar results in Giganotosaurus specimens, who lived on a different continent and tens of millions of years earlier in time.
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The negative value means that heat is produced and the system is exothermic. Endothermic: A + B + Heat → C, ΔH > 0 Exothermic: A + B → C + Heat, ΔH < 0 Since enthalpy is a state function, the ΔH given for a particular reaction is only true for that exact reaction. Physical states (of reactants or products) matter, as do molar concentrations. This matter of ΔH being dependent on physical state and molar concentration means that thermochemical equations must be stoichiometrically correct. If one agent of the equation is changed through multiplication, then all agents must be proportionally changed, including ΔH. (See Manipulating Thermochemical Equations, below.) Thermochemical equation’s multiplicative property is largely due to the First Law of Thermodynamics, which says that energy can be neither created nor destroyed, a concept commonly known as the conservation of energy.
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In the case of neutrons carrying most of the practical energy, as is the case in the D-T fuel, this neutron energy is normally captured in a "blanket" of lithium that produces more tritium that is used to fuel the reactor. Due to various exothermic and endothermic reactions, the blanket may have a power gain factor MR. MR is typically on the order of 1.1 to 1.3, meaning it produces a small amount of energy as well. The net result, the total amount of energy released to the environment and thus available for energy production, is referred to as PR, the net power output of the reactor. The blanket is then cooled and the cooling fluid used in a heat exchanger driving conventional steam turbines and generators.
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As a regional endotherm, Cretoxyrhina may have possessed red muscles closer to its body axis like this porbeagle shark. Cretoxyrhina represents one of the earliest forms and possible origins of endothermy in mackerel sharks. Possessing regional endothermy (also known as mesothermy), it may have possessed a build similar to modern regionally endothermic sharks like members of the thresher shark and lamnid families, where red muscles are closer to the body axis compared to ectothermic sharks (whose red muscles are closer to the body circumference), and a system of specialized blood vessels called rete mirabile (Latin for "wonderful nets") is present, allowing metabolic heat to be conserved and exchanged to vital organs. This morphological build allows the shark to be partially warm-blooded,John K. Carlson, Kenneth J. Goldman, and Christopher G. Lowe. (2004).
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The body energy expenditure of ectothermic animals is about 1/13 of that of endotherms but the energy expenditure of the brains of both ectothermic and endothermic animals are similar. Other high brain percentage (2.6–3.7 % of the body mass) animals exist such as bats, swallows, crows and sparrows but these due to their endothermy also have high body energy metabolism. The unusual high brain energy consumption percentage of mormyrinae fish is thus due to them having the unusual combination of a large brain in a low energy consuming body. The actual energy consumption per unit mass of its brain is not in fact particularly high and indeed lower (2.02 mg g1 h1) than that in some other fish such as Salmonidae (2.20 mg g−1 h−1).
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The acid dissociation constant for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. The value of the pKa changes with temperature and can be understood qualitatively based on Le Châtelier's principle: when the reaction is endothermic, Ka increases and pKa decreases with increasing temperature; the opposite is true for exothermic reactions. The value of pKa also depends on molecular structure of the acid in many ways. For example, Pauling proposed two rules: one for successive pKa of polyprotic acids (see Polyprotic acids below), and one to estimate the pKa of oxyacids based on the number of =O and −OH groups (see Factors that affect pKa values below).
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Allen's rule predicts that endothermic animals with the same body volume should have different surface areas that will either aid or impede their heat dissipation. Because animals living in cold climates need to conserve as much heat as possible, Allen's rule predicts that they should have evolved comparatively low surface area-to- volume ratios to minimize the surface area by which they dissipate heat, allowing them to retain more heat. For animals living in warm climates, Allen's rule predicts the opposite: that they should have comparatively high ratios of surface area to volume. Because animals with low surface area-to- volume ratios would overheat quickly, animals in warm climates should, according to the rule, have high surface area-to-volume ratios to maximize the surface area through which they dissipate heat.
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Thin sections from the ulna and radius of the holotype specimen DNHM D2885 indicate that the bones are devoid of secondary osteons, or osteons formed through bone remodeling. Seasonal bone growth is apparent through the thin sections; three lines of arrested growth (LAGs) separate the cortical bone into four distinct zones within the radius, indicating that the individual was at least four years of age when it died. (There appear to only be two LAGs within the ulna.) These estimates were to considered to be lower bounds, because expansion of the medullary cavity within the bone could have obliterated additional LAGs. The seasonal growth may have been triggered by periods of low temperature; a similar phenomenon is observed among modern animals living in cold climates, including even endothermic mammals.
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Immersion should be avoided for an unconscious person, but if there is no alternative, the person's head must be held above water. Immersion in very cold water was once thought to be counterproductive by reducing blood flow to the skin and thereby preventing heat from escaping the body core. However, this hypothesis has been challenged in experimental studies, as well as by systematic reviews of the clinical data, indicating that cutaneous vasoconstriction and shivering thermogenesis do not play a dominant role in the decrease in core body temperature brought on by cold water immersion. This can be seen in the effect of submersion hypothermia, where the body temperature decrease is directly related to environmental temperature, and though bodily defenses slow the decrease in temperature for a time, they ultimately fail to maintain endothermic homeostasis.
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He then enrolled at Rhodes University for his PhD study on the thermo physio- ecology of the white shark under the supervision of Dr. Paul Cowley from SAIAB and Ryan Johnson. At the same time he and three other marine researchers (Johnson, Stephen Swanson and Toby Keswick) decided to create a private marine research institute focused on marine top predator called the Oceans Research. At present Gennari is researching for his PhD in Mossel Bay trying to disclose the secrets behind the endothermic ability of the great white shark to elevate parts of its body warmer than the external water temperature. In 2008 Gennari, as a member of Oceans Research, initiated a great white shark research internship program that allows students from around the world to gain practical research skills.
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Mei, full name Mei-Ling Zhou (), is a Chinese climatologist and adventurer from Xi'an. She wields an Endothermic Blaster that can either freeze enemies in place with a short-range spray or shoot a long-range icicle projectile, and she can also use it to Cryo-Freeze herself in a solid ice block to shield herself from damage and heal injuries, as well as erect Ice Walls with many versatile uses, primarily for blocking the enemies. Her ultimate ability is Blizzard, which calls down Snowball, her personal weather modification drone, to freeze all enemies in a wide radius. Mei was employed by Overwatch to help discover the cause for the planet's changing climate, which had been variously blamed on industry, the increasing Omnic population, and increased consumption of natural resources.
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The reversible reaction N2O4(g) ⇌ 2NO2(g) is endothermic, so the equilibrium position can be shifted by changing the temperature. When heat is added and the temperature increases, the reaction shifts to the right and the flask turns reddish brown due to an increase in NO2. This demonstrates Le Chatelier's principle: the equilibrium shifts in the direction that consumes energy. When heat is removed and the temperature decreases, the reaction shifts to the left and the flask turns colorless due to an increase in N2O4: again, according to Le Chatelier's principle. The effect of changing the temperature in the equilibrium can be made clear by 1) incorporating heat as either a reactant or a product, and 2) assuming that an increase in temperature increases the heat content of a system.
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In designing a circulating fluidized bed, with constant temperature distribution for either endothermic or exothermic reactions, in order to determine the appropriate design for cooling or heating of the circulating fluidized bed reactors, a good approximation of heat transfer rates are necessary for better control so that the reactor can change its performance for different operating conditions.World's Largest Circulating Fluidized Bed Boiler Begins Commercial Operation, Giglio, 2009, World's Largest Circulating Fluidized Bed Boiler Begins Commercial Operation, Business and Technology for the Global Generation Industry, Electric Power For highly exothermic reactor, it is recommended to keep the conversion of material low and recycle any possible cooled reactants. It is also recommended to separate the components in order of decreasing percentage of material in feed. This will help in reducing the cost of maintenance for the next separation process.
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When the reaction is exothermic (ΔH is negative and energy is released), heat is included as a product, and when the reaction is endothermic (ΔH is positive and energy is consumed), heat is included as a reactant. Hence, whether increasing or decreasing the temperature would favor the forward or the reverse reaction can be determined by applying the same principle as with concentration changes. Take, for example, the reversible reaction of nitrogen gas with hydrogen gas to form ammonia: :N2(g) + 3 H2(g) ⇌ 2 NH3(g) ΔH = -92 kJ mol−1 Because this reaction is exothermic, it produces heat: :N2(g) + 3 H2(g) ⇌ 2 NH3(g) + heat If the temperature were increased, the heat content of the system would increase, so the system would consume some of that heat by shifting the equilibrium to the left, thereby producing less ammonia.
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More ammonia would be produced if the reaction were run at a lower temperature, but a lower temperature also lowers the rate of the process, so, in practice (the Haber process) the temperature is set at a compromise value that allows ammonia to be made at a reasonable rate with an equilibrium concentration that is not too unfavorable. In exothermic reactions, an increase in temperature decreases the equilibrium constant, K, whereas in endothermic reactions, an increase in temperature increases K. Le Chatelier's principle applied to changes in concentration or pressure can be understood by giving K a constant value. The effect of temperature on equilibria, however, involves a change in the equilibrium constant. The dependence of K on temperature is determined by the sign of ΔH. The theoretical basis of this dependence is given by the Van 't Hoff equation.
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However, kleptothermy can happen between different species that share the same habitat, and can also happen in pre-hatching life where embryos are able to detect thermal changes in the environment. This process requires two major conditions: the thermal heterogeneity created by the presence of a warm organism in a cool environment in addition to the use of that heterogeneity by another animal to maintain body temperatures at higher (and more stable) levels than would be possible elsewhere in the local area. The purpose of this behaviour is to enable these groups to increase its thermal inertia, retard heat loss and/or reduce the per capita metabolic expenditure needed to maintain stable body temperatures. Kleptothermy is seen in cases where ectotherms regulate their own temperatures and exploit the high and constant body temperatures exhibited by endothermic species.
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The ability to maintain homeostasis at varying temperatures is the most important characteristic in defining an endothermic eurytherm, whereas other, thermoconforming eurytherms like tardigrades are simply able to endure significant shifts in their internal body temperature that occur with ambient temperature changes. Eurythermic animals can be either conformers or regulators, meaning that their internal physiology can either vary with the external environment or maintain consistency regardless of the external environment, respectively. It is important to note that endotherms do not solely rely on internal thermogenesis for all parts of homeostasis or comfort; in fact, in many ways, they are equally as reliant upon behavior to regulate body temperature as ectotherms are. Reptiles are ectotherms, and therefore rely upon positive thermotaxis, basking (heliothermy), burrowing, and crowding with members of their species in order to regulate their body temperature within a narrow range and even to produce fevers to fight infection.
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The discovery of many gastroliths (gizzard stones) in some ornithomimids indicate the presence of a gastric mill, and therefore point towards a herbivorous diet, as these are used to grind food of animals that lack the necessary chewing apparatus. Barrett also calculated that a Gallimimus would have needed between of food per day, depending on whether it had an endothermic or an ectothermic ("warm" or "cold"-blooded) metabolism, an intake which he found to be unfeasible if it was a filter feeder. He also found that ornithomimids were abundant not only in formations that represented mesic environments, but also in arid environments where there would be insufficient water to sustain a diet based on filter feeding. In 2007, palaeontologist Espen M. Knutsen wrote that the beak shape of ornithomimids, when compared to those of modern birds, was consistent with omnivory or high-fibre herbivory.
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The ribs were connected to the dorsal (trunk) vertebrae with two joints, acting together as a simple hinge joint, which has allowed researchers to reconstruct the inhaled and exhaled positions of the ribcage. The difference in volume between these two positions defines the air exchange volume (the amount of air moved with each breath), determined to be approximately 20 L for a P. engelhardti individual estimated to have weighed 690 kg, or 29 mL/kg bodyweight. This is a typical value for birds, but not for mammals, and indicates that Plateosaurus probably had an avian-style flow-through lung, although indicators for postcranial pneumaticity (air sacs of the lung invading the bones to reduce weight) can be found on the bones of only a few individuals, and were only recognised in 2010. Combined with evidence from bone histology this indicates that Plateosaurus was endothermic.
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Additionally, endothermic (warm-blooded) vertebrates need to use a significantly greater amount of energy just to stay warm whereas ectothermic (cold-blooded) plants or insects do not. An index which can be used as a measure is the Efficiency of conversion of ingested food to body substance: for example, only 10% of ingested food is converted to body substance by beef cattle, versus 19–31% by silkworms and 44% by German cockroaches. Studies concerning the house cricket (Acheta domesticus) provide further evidence for the efficiency of insects as a food source. When reared at 30 °C or more and fed a diet of equal quality to the diet used to rear conventional livestock, crickets showed a food conversion twice as efficient as pigs and broiler chicks, four times that of sheep, and six times higher than steers when losses in carcass trim and dressing percentage are counted.
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Temperatures as high as are used in industrial calcination, but at these temperatures γ-anhydrite begins to form. The heat energy delivered to the gypsum at this time (the heat of hydration) tends to go into driving off water (as water vapor) rather than increasing the temperature of the mineral, which rises slowly until the water is gone, then increases more rapidly. The equation for the partial dehydration is: : CaSO4 · 2 H2O -> CaSO4 · H2O + H2O↑ The endothermic property of this reaction is relevant to the performance of drywall, conferring fire resistance to residential and other structures. In a fire, the structure behind a sheet of drywall will remain relatively cool as water is lost from the gypsum, thus preventing (or substantially retarding) damage to the framing (through combustion of wood members or loss of strength of steel at high temperatures) and consequent structural collapse.
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The thermonuclear burn would produce (like the fission fuel in the primary) pulsations (generations) of high-energy neutrons with an average temperature of 14 MeV through Jetter's cycle. The cycle is a combination of endothermic and exothermic neutronic reactions involving lithium and deuterium/tritium. The reaction's neutronicity was estimated at ≈0.885 (for a Lawson criterion of ≈1.5). These figures do not count the Li isotope, where the LiD has a neutronicity of ≈0.835 and, along with the cross-sections, were given as group averages from about 2.40 to approximately 2.55 MeV and from 14.0 to 14.1 MeV; the small power group is not statistically present (see also Nuclear fusion). As SHRIMP, along with the RUNT I and ALARM CLOCK were to be high-yield shots required to assure the thermonuclear “emergency capability”, their fusion fuel may have been spiked with additional tritium, in the form of LiT.
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However, even for superacidic solutions, protons in the condensed phase are far from being unbound. For instance, in fluoroantimonic acid, they are bound to one or more molecules of hydrogen fluoride. Though hydrogen fluoride is normally regarded as an exceptionally weak proton acceptor (though a somewhat better one than the SbF6– anion), dissociation of its protonated form, the fluoronium ion H2F+ to HF and the truly naked H+ is still a highly endothermic process (ΔG° = +113 kcal/mol), and imagining the proton in the condensed phase as being "naked" or "unbound", like charged particles in a plasma, is highly inaccurate and misleading. More recently, carborane acids have been prepared as single component superacids that owe their strength to the extraordinary stability of the carboranate anion, a family of anions stabilized by three- dimensional aromaticity, as well as by electron-withdrawing group typically attached thereto.
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When considering whether a specific nuclear transmutation, a reaction or a decay, is energetically allowed, one only needs to sum the masses of the initial nucleus/nuclei and subtract from that value the sum of the masses of the product particles. If the result, or Q-value, is positive, then the transmutation is allowed, or exothermic because it releases energy, and if the Q-value is a negative quantity, then it is endothermic as at least that much energy must be added to the system before the transmutation may proceed. For example, to determine if 12C, the most common isotope of carbon, can undergo proton emission to 11B, one finds that about 16 MeV must be added to the system for this process to be allowed. While Q-values can be used to describe any nuclear transmutation, for particle decay, the particle separation energy quantity S, is also used, and it is equivalent to the negative of the Q-value.
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Water oxidation is a more complex chemical reaction than proton reduction. In nature, the oxygen- evolving complex performs this reaction by accumulating reducing equivalents (electrons) in a manganese-calcium cluster within photosystem II (PS II), then delivering them to water molecules, with the resulting production of molecular oxygen and protons: :2 H2O → O2 \+ 4 H+ \+ 4e− Without a catalyst (natural or artificial), this reaction is very endothermic, requiring high temperatures (at least 2500 K). The exact structure of the oxygen-evolving complex has been hard to determine experimentally. As of 2011, the most detailed model was from a 1.9 Å resolution crystal structure of photosystem II. The complex is a cluster containing four manganese and one calcium ions, but the exact location and mechanism of water oxidation within the cluster is unknown. Nevertheless, bio-inspired manganese and manganese-calcium complexes have been synthesized, such as [Mn4O4] cubane-type clusters, some with catalytic activity.
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It was pointed out in 1976 that, because of their height, many dinosaurs had minimum blood pressures within the endothermic range, and that they must have had four-chambered hearts to separate the high pressure circuit to the body from the low pressure circuit to the lungs. It was not clear whether these dinosaurs had high blood pressure simply to support the blood column or to support the high blood flow rates required by endothermy or both. Foramen blood flow index, derived from the size of the nutrient foramen of the femurs of mammals, reptiles and dinosaurs However, recent analysis of the tiny holes in fossil leg bones of dinosaurs provides a gauge for blood flow rate and hence metabolic rate. The holes are called nutrient foramina, and the nutrient artery is the major blood vessel passing through to the interior of the bone, where it branches into tiny vessels of the Haversian canal system.
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In 2019, thin slices were cut from the humerus, femur and tibia of specimens attributed to A. laaroussii for histological examination of the microscopic bone structure to try and determine the rate of growth in Azendohsaurus. The vascular density (the density of blood vessels in the bone tissue) in all three limb bones was found to be comparable to those of fast- growing birds and mammals, and the types of bone tissue identified—particularly energy-consuming fibrolamellar bone tissue—were interpreted as indicating a high resting metabolic rate that was in the range of living birds and mammals. It was inferred then that, like birds and mammals, Azendohsaurus would also likewise have been endothermic, or "warm- blooded". High resting metabolic rates similar to those of Azendohsaurus had been identified in other more derived archosauromorphs (such as Prolacerta), and analyses suggested that endothermy may then have been ancestrally present in archosauromorphs as far back as their common ancestor with allokotosaurs.
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In one specimen, the isotope ratios in bones from different parts of the body indicated a temperature difference of no more than 4 to 5 °C (7 to 9 °F) between the vertebrae of the torso and the tibia of the lower leg. This small temperature range between the body core and the extremities was claimed by paleontologist Reese Barrick and geochemist William Showers to indicate that T. rex maintained a constant internal body temperature (homeothermy) and that it enjoyed a metabolism somewhere between ectothermic reptiles and endothermic mammals. Other scientists have pointed out that the ratio of oxygen isotopes in the fossils today does not necessarily represent the same ratio in the distant past, and may have been altered during or after fossilization (diagenesis). Barrick and Showers have defended their conclusions in subsequent papers, finding similar results in another theropod dinosaur from a different continent and tens of millions of years earlier in time (Giganotosaurus).
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Urea plant using ammonium carbamate briquettes, Fixed Nitrogen Research Laboratory, ca. 1930 The basic process, developed in 1922, is also called the Bosch–Meiser urea process after its discoverers. Various commercial urea processes are characterized by the conditions under which urea forms and the way that unconverted reactants are further processed. The process consists of two main equilibrium reactions, with incomplete conversion of the reactants. The first is carbamate formation: the fast exothermic reaction of liquid ammonia with gaseous carbon dioxide (CO2) at high temperature and pressure to form ammonium carbamate (H2N-COONH4): :2 NH3 \+ CO2 H2N-COONH4 (ΔH= -117kJ/mol at 110 atm and 160°C) The second is urea conversion: the slower endothermic decomposition of ammonium carbamate into urea and water: :H2N-COONH4 (NH2)2CO + H2O (ΔH= +15.5 kJ/mol at 160-180°C) The overall conversion of NH3 and CO2 to urea is exothermic, the reaction heat from the first reaction driving the second.
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Ayaks uses thermochemical reactors (TCRs): the heating energy from air friction is used to increase the heat capacity of the fuel, by cracking the fuel with a catalytic chemical reaction. The aircraft has double shielding between which water and ordinary, cheap kerosene circulates in hot parts of the airframe. The energy of surface heating is absorbed through heat exchangers to trigger a series of chemical reactions in presence of a nickel catalyzer, called hydrocarbon steam reforming. Kerosene and water spits into a new fuel reformate: methane (70–80% in volume) and carbon dioxide (20–30%) in a first stage: ::CnHm \+ H2O \rightleftharpoons CH4 \+ CO2 Then methane and water reform in their turn in a second stage into hydrogen, a new fuel of better quality, in a strong endothermic reaction: ::CH4 \+ H2O \rightleftharpoons CO + 3H2 ::CO + H2O \rightleftharpoons CO2 \+ H2 Thus, the heating capacity of the fuel increases, and the surface of the aircraft cools down.
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Endothermic ProductsNRC: Thermal Science Monetary Penalties The latest iteration of Thermo-Lag related issues involving a Thermo-Lag overlay over top of existing Thermo-Lag was USNRC Information Notice 2018-09USNRC Information Notice 2018-09, informing USNRC licensees of the occurrence of "an electrical arc flash initiated by intrusion of foreign material into a switchgear cubicle", where elemental carbon from the fabrication of a Thermo-Lag fabric caused an explosion, which damaged an adjacent fire door., which indicated that during the fabrication of an overlay of the existing fireproofing, on 18. March 2017, elemental carbon, from a fabric that was part of the overlay, was being cut and fabricated and as a result, debris from this fabric entered the electrical cabinet, which caused the arc flash. The importance of firestopping of nuclear facilities was manifested in the Browns Ferry Nuclear Power Plant fire, a fire resulted from combustion of extremely flammable polyurethane foam.
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Such engines were used on the Viking program landers in the 1970s as well as the Phoenix lander and Curiosity rover which landed on Mars in May 2008 and August 2012, respectively. In all hydrazine monopropellant engines, the hydrazine is passed over a catalyst such as iridium metal supported by high-surface-area alumina (aluminium oxide), which causes it to decompose into ammonia, nitrogen gas, and hydrogen gas according to the following reactions: 1) N2H4 -> N2 + 2H2 2) 3N2H4 -> 4 NH3 + N2 3) 4NH3 + N2H4 -> 3 N2 + 8 H2 The first two reactions are extremely exothermic (the catalyst chamber can reach 800°C in a matter of milliseconds,) and they produce large volumes of hot gas from a small volume of liquid, making hydrazine a fairly efficient thruster propellant with a vacuum specific impulse of about 220 seconds. Reaction 2 is the most exothermic, but produces a smaller number of molecules than that of reaction 1. Reaction 3 is endothermic and reverts the effect of reaction 2 back to the same effect as reaction 1 alone (lower temperature, greater number of molecules).
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232Th is a primordial nuclide, having existed in its current form for over ten billion years; it was forged in the cores of dying stars through the r-process and scattered across the galaxy by supernovae and neutron star mergers. The letter "r" stands for "rapid neutron capture", and occurs in core-collapse supernovae, where heavy seed nuclei such as 56Fe rapidly capture neutrons, running up against the neutron drip line, as neutrons are captured much faster than the resulting nuclides can beta decay back toward stability. Neutron capture is the only way for stars to synthesise elements beyond iron because of the increased Coulomb barriers that make interactions between charged particles difficult at high atomic numbers and the fact that fusion beyond 56Fe is endothermic. Because of the abrupt loss of stability past 209Bi, the r-process is the only process of stellar nucleosynthesis that can create thorium and uranium; all other processes are too slow and the intermediate nuclei alpha decay before they capture enough neutrons to reach these elements.
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The formation of an alkali metal nitride would consume the ionisation energy of the alkali metal (forming M+ ions), the energy required to break the triple bond in N2 and the formation of N3− ions, and all the energy released from the formation of an alkali metal nitride is from the lattice energy of the alkali metal nitride. The lattice energy is maximised with small, highly charged ions; the alkali metals do not form highly charged ions, only forming ions with a charge of +1, so only lithium, the smallest alkali metal, can release enough lattice energy to make the reaction with nitrogen exothermic, forming lithium nitride. The reactions of the other alkali metals with nitrogen would not release enough lattice energy and would thus be endothermic, so they do not form nitrides at standard conditions. Sodium nitride (Na3N) and potassium nitride (K3N), while existing, are extremely unstable, being prone to decomposing back into their constituent elements, and cannot be produced by reacting the elements with each other at standard conditions.. 'Elusive Binary Compound Prepared' Chemical & Engineering News 80 No. 20 (20 May 2002) Steric hindrance forbids the existence of rubidium or caesium nitride.
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