In essence the rules were (probabilistic) ones about how systems can carry information and how they can be combined and interconverted.
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Other pairs (such as CHFClBr) cannot be interconverted without breaking bonds, and therefore are different configurations.
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Additionally, crystal phases can sometimes be interconverted by varying factors such as temperature, such as in the transformation of anatase to rutile phases of titanium dioxide.
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Ozone–oxygen cycle in the ozone layer: 1\. Oxygen photolyzed to atomic oxygen 2\. Oxygen and ozone continuously interconverted. Solar UV breaks down oxygen; molecular and atomic oxygen combine to form Ozone. 3\.
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Adenine structure, with standard numbering of positions in red. Adenine forms several tautomers, compounds that can be rapidly interconverted and are often considered equivalent. However, in isolated conditions, i.e. in an inert gas matrix and in the gas phase, mainly the 9H-adenine tautomer is found.
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Vitamin B6 refers to a group of chemically similar compounds which can be interconverted in biological systems. Vitamin B6 is part of the vitamin B group of essential nutrients. Its active form, pyridoxal 5′-phosphate, serves as a coenzyme in some 100 enzyme reactions in amino acid, glucose, and lipid metabolism.
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976-7 However, this term is ambiguous and is discouraged by the IUPAC. Stereoisomers that are not enantiomers are called diastereomers. Some diastereomers may contain chiral center, some not. Some enantiomer pairs (such as those of trans-cyclooctene) can be interconverted by internal motions that change bond lengths and angles only slightly.
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Lutein is isomeric with zeaxanthin, differing only in the placement of one double bond. Lutein and zeaxanthin can be interconverted in the body through an intermediate called meso-zeaxanthin. The principal natural stereoisomer of lutein is (3R,3′R,6′R)-beta,epsilon- carotene-3,3′-diol. Lutein is a lipophilic molecule and is generally insoluble in water.
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Although ΔA is usually measured, for historical reasons most measurements are reported in degrees of ellipticity. Molar ellipticity is circular dichroism corrected for concentration. Molar circular dichroism and molar ellipticity, [θ], are readily interconverted by the equation: Elliptical polarized light (violet) is composed of unequal contributions of right (blue) and left (red) circular polarized light. : [\theta] = 3298.2\,\Delta \varepsilon.
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Adenosine monophosphate (AMP), also known as 5'-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine; it is an ester of phosphoric acid and the nucleoside adenosine. As a substituent it takes the form of the prefix adenylyl-. AMP plays an important role in many cellular metabolic processes, being interconverted to ADP and/or ATP.
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Besides uncompressed formats and lossless compression formats that can usually be interconverted without any loss of detail, there are compressed formats such as JPEG, which lose detail on nearly every compress. While a conversion from a compressed to an uncompressed format is in general without loss, this is not true the other way around. Even a compressed-uncompressed-compressed round trip without any image manipulation may encur some loss of detail.
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Reactions of acids are often generalized in the form HA H+ \+ A−, where HA represents the acid and A− is the conjugate base. This reaction is referred to as protolysis. The protonated form (HA) of an acid is also sometimes referred to as the free acid. Acid-base conjugate pairs differ by one proton, and can be interconverted by the addition or removal of a proton (protonation and deprotonation, respectively).
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Rotation about single bond of butane to interconvert one conformation to another. The gauche conformation on the right is a conformer, while the eclipsed conformation on the left is a transition state between conformers. Above: Newman projection; below: depiction of spatial orientation. In chemistry, conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted just by rotations about formally single bonds (refer to figure on single bond rotation).
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The different naturally occurring vitamers of vitamin E are not interconverted in the body and have different metabolic effects. Newly absorbed vitamers of vitamin E are transported to the liver. The liver recognizes and preferentially re-secretes α-tocopherol into circulation, making it the most abundant vitamer of vitamin E in the blood. While tocotrienols are present in lower concentrations, they have more potent antioxidant properties than α-tocopherol and can have metabolic impacts at low concentration.
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Previously, it was proposed that RPE65 exists in two, interconverted forms: membrane bound mRPE65 and soluble sRPE65. This theory suggested that the reversible conversion of sRPE65 to mRPE65 by palmitoylation at Cys231, Cys329, and Cys330 played a role in regulating the retinoid cycle and endowing mRPE65 with its membrane affinity. However, crystallographic studies of RPE65 have demonstrated that these residues are neither palmitoylated nor surface facing. New studies have also failed to confirm the presence of abundant soluble RPE65.
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Each provides its characteristic or fundamental equation, for example , that by itself contains all thermodynamic information about the system. The fundamental equations for the two cardinal functions can in principle be interconverted by solving, for example, for , to get . In contrast, Legendre transforms are necessary to derive fundamental equations for other thermodynamic potentials and Massieu functions. The entropy as a function only of extensive state variables is the one and only cardinal function of state for the generation of Massieu functions.
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The Spectronic 20 measures the absorbance of light at a pre-determined concentration, and the concentration is calculated from the Beer-Lambert relationship. The absorbance of the light is the base 10 logarithm of the ratio of the Transmittance of the pure solvent to the transmittance of the sample, and so the two absorbance and transmittance can be interconverted. Either transmittance or absorbance can therefore be plotted versus concentration using measurements from the Spectronic 20. Plotting a curve using percent transmittance of light yields an exponential curve.
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Adenosine diphosphate (ADP), also known as adenosine pyrophosphate (APP), is an important organic compound in metabolism and is essential to the flow of energy in living cells. ADP consists of three important structural components: a sugar backbone attached to adenine and two phosphate groups bonded to the 5 carbon atom of ribose. The diphosphate group of ADP is attached to the 5’ carbon of the sugar backbone, while the adenosine attaches to the 1’ carbon. ADP can be interconverted to adenosine triphosphate (ATP) and adenosine monophosphate (AMP).
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Fuchter has also developed novel molecular photoswitches – molecules that can be cleanly and reversibly interconverted between two states using light – with a focus on heteroaromatic versions of azobenzene. The arylazopyrazole switches developed by Fuchter out perform the ubiquitous azobenzene switches, demonstrating complete photoswitching in both directions and thermal half-lives of the Z isomer of up to 46 years. Fuchter continues to apply these switches to a range of photoaddressable applications from photopharmacology to energy storage. Alongside his work on functional material discovery, Fuchter works in medicinal chemistry and develops small molecule ligands that can either inhibit or stimulate the activity of disease relevant proteins.
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The double-helical configuration of DNA strands makes them difficult to separate, which is required by helicase enzymes if other enzymes are to transcribe the sequences that encode proteins, or if chromosomes are to be replicated. In circular DNA, in which double- helical DNA is bent around and joined in a circle, the two strands are topologically linked, or knotted. Otherwise identical loops of DNA, having different numbers of twists, are topoisomers, and cannot be interconverted without the breaking of DNA strands. Topoisomerases catalyze and guide the unknotting or unlinking of DNA by creating transient breaks in the DNA using a conserved tyrosine as the catalytic residue.
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The elimination half-life of raloxifene after a single dose is 27.7 hours (1.2 days), whereas its half-life at steady state at a dosage of 60 mg/day is 15.8 to 86.6 hours (0.7–3.6 days), with an average of 32.5 hours (1.4 days). The extended half-life of raloxifene is attributed to enterohepatic recirculation and its high plasma protein binding. Raloxifene and its glucuronide conjugates are interconverted by reversible metabolism and enterohepatic recycling, which prolongs the elimination half-life of raloxifene with oral administration. The medication is deconjugated into its active form in a variety of tissues, including liver, lungs, spleen, bone, uterus, and kidneys.
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There are two different definitions of a time-constructible function. In the first definition, a function f is called time-constructible if there exists a positive integer n0 and Turing machine M which, given a string 1n consisting of n ones, stops after exactly f(n) steps for all n ≥ n0. In the second definition, a function f is called time-constructible if there exists a Turing machine M which, given a string 1n, outputs the binary representation of f(n) in O(f(n)) time (a unary representation may be used instead, since the two can be interconverted in O(f(n)) time). There is also a notion of a fully time-constructible function.
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For instance, the synthesis of tetrakis(t-butyl)cyclopentadienone from the tris(t-butyl)bromocyclopentadienone (itself synthesized with much difficulty) required over 50 attempts before working conditions could be found. The synthesis was described as requiring "astonishing persistence and experimental skill" in one retrospective of the work. In a classic reference work on stereochemistry, the authors remark that "the relatively straightforward scheme shown [...] conceals both the limited availability of the starting material and the enormous amount of work required in establishing the proper conditions for each step." :Tetra-tert-butyl-tetrahedrane synthesis 1978 Eventually, a more scalable synthesis was conceived, in which the last step was the photolysis of a cyclopropenyl-substituted diazomethane, which affords the desired product through the intermediacy of tetra(tert- butyl)cyclobutadiene: This approach took advantage of the observation that the tetrahedrane and the cyclobutadiene could be interconverted (uv irradiation in the forward direction, heat in the reverse direction).
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