A closely related concept is molar absorptivity. They are quantitatively related by :(mass attenuation coefficient) × (molar mass) = (molar absorptivity).
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In addition, c-BN consists of only light elements and has low X-ray absorptivity, capable of reducing the X-ray absorption background.
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The molar attenuation coefficient is also known as the molar extinction coefficient and molar absorptivity, but the use of these alternative terms has been discouraged by the IUPAC.
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Liang, H.J.W. Müller-Kirsten and D.H. Tchrakian, Phys. Lett. B282 (1992) 105. # Derivation of S-matrix and absorptivity for the singular potential 1/r^4 (cf. modified Mathieu equation) and application to string theory.
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There is a fundamental relationship (Gustav Kirchhoff's 1859 law of thermal radiation) that equates the emissivity of a surface with its absorption of incident radiation (the "absorptivity" of a surface). Kirchhoff's Law explains why emissivities cannot exceed 1, since the largest absorptivity - corresponding to complete absorption of all incident light by a truly black object - is also 1. Mirror-like, metallic surfaces that reflect light will thus have low emissivities, since the reflected light isn't absorbed. A polished silver surface has an emissivity of about 0.02 near room temperature.
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It has an absorptivity coefficient about 3400. That means very small amounts of chromium can be detected; 25 micrograms in 25 mL of solution are too dark to read on a spectral device, so concentrations well below that can be detected.
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In slightly different terms, the emissive power of an arbitrary opaque body of fixed size and shape at a definite temperature can be described by a dimensionless ratio, sometimes called the emissivity: the ratio of the emissive power of the body to the emissive power of a black body of the same size and shape at the same fixed temperature. With this definition, Kirchhoff's law states, in simpler language: In some cases, emissive power and absorptivity may be defined to depend on angle, as described below. The condition of thermodynamic equilibrium is necessary in the statement, because the equality of emissivity and absorptivity often does not hold when the material of the body is not in thermodynamic equilibrium. Kirchhoff's law has another corollary: the emissivity cannot exceed one (because the absorptivity cannot, by conservation of energy), so it is not possible to thermally radiate more energy than a black body, at equilibrium.
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His proof intended to show that the ratio was independent of the nature of the non-ideal body, however partly transparent or partly reflective it was. His proof first argued that for wavelength and at temperature , at thermal equilibrium, all perfectly black bodies of the same size and shape have the one and the same common value of emissive power , with the dimensions of power. His proof noted that the dimensionless wavelength-specific absorptivity of a perfectly black body is by definition exactly 1. Then for a perfectly black body, the wavelength-specific ratio of emissive power to absorptivity is again just , with the dimensions of power.
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Schwarzschild's equation can be derived from Kirchhoff's law of thermal radiation, which states that absorptivity must equal emissivity at a given wavelength. (Like Schwarzschild's equation, Kirchhoff's law only applies to media in LTE.) Given a thin slab of atmosphere of incremental thickness ds, by definition its absorptivity is dIa/I, where I is the incident radiation and dIa is radiation absorbed by the slab. According to Beer's Law: : dI_a/I = n\sigma_\lambda \, ds Also by definition, emissivity is equal to dIe/Bλ(T), where dIe is the radiation emitted by the slab and Bλ(T) is the maximum radiation any object in LTE can emit. Setting absorptivity equal to emissivity affords: : dI_e/B_\lambda(T) = n\sigma_\lambda \, ds : dI_e = n\sigma_\lambda B_\lambda(T) \, ds The total change in radiation, dI, passing through the slab is given by: : dI = dI_e - dI_a = n\sigma_\lambda B_\lambda(T) \, ds - n\sigma_\lambda I \, ds Schwarzschild's equation has also been derived from Einstein coefficients by assuming a Maxwell–Boltzmann distribution of energy between a ground and excited state (LTE).
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Polyphenols are molecules owing their UV/Vis absorptivity to aromatic structures with large conjugated systems of pi electron configurations; they also have autofluorescence properties, especially lignin and the phenolic part of suberin.Force A, See to Act.FLUORESCENCE AND POLYPHENOLS retrieved 31 July 2013. They are reactive species toward oxidation.
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Again, the ratio of emitting power to absorptivity is a dimensioned quantity, with the dimensions of emitting power. In a second report made in 1859, Kirchhoff announced a new general principle or law for which he offered a theoretical and mathematical proof, though he did not offer quantitative measurements of radiation powers. His theoretical proof was and still is considered by some writers to be invalid. His principle, however, has endured: it was that for heat rays of the same wavelength, in equilibrium at a given temperature, the wavelength- specific ratio of emitting power to absorptivity has one and the same common value for all bodies that emit and absorb at that wavelength.
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Laser absorption can occur at the surface of plastics or during transmission through thickness. The amount of laser energy absorbed by a polymer is a function of the laser wavelength, polymer absorptivity, polymer crystallinity, and additives (i.e. composite reinforcements, pigments, etc.). The absorption at surface has two possible ways, photolytic and pyrolytic.
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Near-infrared spectroscopy is based on molecular overtone and combination vibrations. Such transitions are forbidden by the selection rules of quantum mechanics. As a result, the molar absorptivity in the near-IR region is typically quite small. One advantage is that NIR can typically penetrate much further into a sample than mid infrared radiation.
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In contrast, the absorptivity of GaAs is so high that only a few micrometers of thickness are needed to absorb all of the light. Consequently, GaAs thin films must be supported on a substrate material.Single-Crystalline Thin Film. US Department of Energy Silicon is a pure element, avoiding the problems of stoichiometric imbalance and thermal unmixing of GaAs.
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To increase corrosion resistance, the surface may be oiled, lacquered, or waxed. It is also used as a pre-treatment for painting or enamelling. The surface finish is usually satin, but it can be turned glossy by coating in a clear high-gloss enamel. On a microscopic scale dendrites form on the surface finish, which trap light and increase absorptivity.
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Amorphous plastics are generally optically clear and can transmit almost all incident IR radiation. For this reason they are commonly used in TTIr. Semi-crystalline plastics can diffuse incident IR radiation between the amorphous and crystalline boundaries, reducing the transmittance and increasing the absorbance of the material. The higher absorptivity results in more heat generation for a given IR source.
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Solid thermal mass (e.g., concrete, masonry, stone, etc.) should be relatively thin, no more than about 4 in (100 mm) thick. Thermal masses with large exposed areas and those in direct sunlight for at least part of the day (2 hour minimum) perform best. Medium-to-dark, colors with high absorptivity, should be used on surfaces of thermal mass elements that will be in direct sunlight.
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Direct laser welding of polymers Similar to laser welding of metals, in direct laser welding the surface of the polymer is heated to create a melt zone that joins two components together. This approach can be used to create butt joints and lap joints with complete penetration. Laser wavelengths between 2 and 10.6μm are used for this process due to their high absorptivity in polymers.
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Glazed systems usually have a transparent top sheet and insulated side and back panels to minimize heat loss to ambient air. The absorber plates in modern panels can have absorptivity of more than 93%. Glazed Solar Collectors (recirculating types that are usually used for space heating). Air typically passes along the front or back of the absorber plate while scrubbing heat directly from it.
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Coatings are the simplest and least expensive of the TCS techniques. A coating may be paint or a more sophisticated chemical applied to the surfaces of the spacecraft to lower or increase heat transfer. The characteristics of the type of coating depends on their absorptivity, emissivity, transparency, and reflectivity. The main disadvantage of coating is that it degrades quickly due to the operating environment.
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Latitudinal circulation is a result of the highest solar radiation per unit area (solar intensity) falling on the tropics. The solar intensity decreases as the latitude increases, reaching essentially zero at the poles. Longitudinal circulation, however, is a result of the heat capacity of water, its absorptivity, and its mixing. Water absorbs more heat than does the land, but its temperature does not rise as greatly as does the land.
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In vaporization cutting the focused beam heats the surface of the material to boiling point and generates a keyhole. The keyhole leads to a sudden increase in absorptivity quickly deepening the hole. As the hole deepens and the material boils, vapor generated erodes the molten walls blowing ejecta out and further enlarging the hole. Non melting material such as wood, carbon and thermoset plastics are usually cut by this method.
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Ultraviolet-visible absorption (UV-Vis) spectroelectrochemistry is a technique that studies the absorption of electromagnetic radiation in the UV-Vis regions of the spectrum, providing molecular information related to the electronic levels of molecules. It provides qualitative as well as quantitative information. UV-Vis spectroelectrochemistry helps to characterize compounds and materials, determines concentrations and different parameters such as absorptivity coefficients, diffusion coefficients, formal potentials or electron transfer rates.
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Curve fitting can be used in two distinct ways. # The line shapes and parameters p_0 and w of the individual component curves have been obtained experimentally. In this case the curve may be decomposed using a linear least squares process simply to determine the concentrations of the components. This process is used in analytical chemistry to determine the composition of a mixture of the components of known molar absorptivity spectra.
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Fabrication techniques include electron beam lithography, nanostructuring with a focused ion beam and interference lithography. In 2014 a polarization-insensitive metamaterial prototype was demonstrated to absorb energy over a broad band (a super-octave) of infrared wavelengths. The material displayed greater than 98% measured average absorptivity that it maintained over a wide ±45° field-of-view for mid- infrared wavelengths between 1.77 and 4.81 μm. One use is to conceal objects from infrared sensors.
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Small organic dyes usually are less than 1 kDa, and have been modified to increase photostability and brightness, and reduce self-quenching. Quantum dots have very sharp wavelengths, high molar absorptivity and quantum yield. Both organic dyes and quantum dyes do not have the ability to recognize the protein of interest without the aid of antibodies, hence they must use immunolabeling. Fluorescent proteins are genetically encoded and can be fused to your protein of interest.
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A cool roof, or green roof in addition to a radiant barrier can help prevent your attic from becoming hotter than the peak summer outdoor air temperature (see albedo, absorptivity, emissivity, and reflectivity). Windows are a ready and predictable site for thermal radiation. Energy from radiation can move into a window in the day time, and out of the same window at night. Radiation uses photons to transmit electromagnetic waves through a vacuum, or translucent medium.
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However, it is typical in engineering to assume that a surface's spectral emissivity and absorptivity do not depend on wavelength so that the emissivity is a constant. This is known as the gray body assumption. 9-year WMAP image (2012) of the cosmic microwave background radiation across the universe. With non-black surfaces, the deviations from ideal black-body behavior are determined by both the surface structure, such as roughness or granularity, and the chemical composition.
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On the other hand, kinetic and thermodynamic information of the processes is obtained from the electrochemical signal. UV-Vis absorption SEC allows qualitative analysis, through the characterization of the different present compounds, and quantitative analysis, by determining the concentration of the analytes of interest. Furthermore, it helps to determine different electrochemical parameters such as absorptivity coefficients, standard potentials, diffusion coefficients, electronic transfer rate constants, etc. Throughout history, reversible processes have been studied with colored reagents or electrolysis products.
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Not all radiant energy is absorbed and turned into heat for welding. Some of the radiant energy is absorbed in the plasma created by vaporizing and then subsequently ionizing the gas. In addition, the absorptivity is affected by the wavelength of the beam, the surface composition of the material being welded, the angle of incidence, and the temperature of the material. Rosenthal point source assumption leaves an infinitely high temperature discontinuity which is addressed by assuming a Gaussian distribution instead.
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In ultra-high vacuum systems, some very odd leakage paths and outgassing sources must be considered. The water absorption of aluminium and palladium becomes an unacceptable source of outgassing, and even the absorptivity of hard metals such as stainless steel or titanium must be considered. Some oils and greases will boil off in extreme vacuums. The porosity of the metallic vacuum chamber walls may have to be considered, and the grain direction of the metallic flanges should be parallel to the flange face.
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In radiative transfer theory, one-way radiation is considered. For investigation of Kirchhoff's law of thermal radiation the notions of absorptivity and emissivity are necessary, and they rest on the idea of one- way radiation. These things are important for the study of the Einstein coefficients, which relies partly on the notion of thermodynamic equilibrium. For the thermodynamic stream of thinking, the notion of empirical temperature is coordinately presupposed in the notion of heat transfer for the definition of an adiabatic wall.Planck.
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Other objects on which frost commonly forms are those with low specific heat or high thermal emissivity, such as blackened metals; hence the accumulation of frost on the heads of rusty nails. The apparently erratic occurrence of frost in adjacent localities is due partly to differences of elevation, the lower areas becoming colder on calm nights. Where static air settles above an area of ground in the absence of wind, the absorptivity and specific heat of the ground strongly influence the temperature that the trapped air attains.
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Appendix G. This high mobility allows the fabrication of higher-speed P-channel field effect transistors, which are required for CMOS logic. Because they lack a fast CMOS structure, GaAs circuits must use logic styles which have much higher power consumption; this has made GaAs logic circuits unable to compete with silicon logic circuits. For manufacturing solar cells, silicon has relatively low absorptivity for sunlight, meaning about 100 micrometers of Si is needed to absorb most sunlight. Such a layer is relatively robust and easy to handle.
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Pork five-flavor powder Jangjorim is known as a food that is well known for its good digestive power, which warms the body, strengthens the stomach, and cooks the pork, which is known as cold food. The color of pork is light pink, and young pigs are bluish white depending on age or area. Pork is rich in essential amino acids, thin muscle fibers, and high digestibility in soft digestion. The fat is white and hard, and the direction is good digestion and absorptivity.
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Thus, the chance of recombination is reduced and secondary reactions are promoted. Reactions may take place at higher temperatures that occur at a very low rate or not at all at lower temperatures. In the presence of sunlight the surface temperature of an object is usually considerably higher than the temperature of the air. Solar absorptivity is closely related to color, varying from about 20% for white materials to 90% for black materials; thus samples of different colors will reach different on-exposure temperatures.
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Two bodies, each with its own uniform temperature, in solely radiative connection, no matter how far apart, or what partially obstructive, reflective, or refractive, obstacles lie in their path of radiative exchange, not moving relative to one another, will exchange thermal radiation, in net the hotter transferring energy to the cooler, and will exchange equal and opposite amounts just when they are at the same temperature. In this situation, Kirchhoff's law of equality of radiative emissivity and absorptivity and the Helmholtz reciprocity principle are in play.
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When there is enough matter in a region to allow molecular collisions to occur very much more often than creation or annihilation of photons, for radiation one speaks of local thermodynamic equilibrium. In this case, Kirchhoff's law of equality of radiative absorptivity and emissivity holds.Milne, E.A. (1928). The effect of collisions on monochromatic radiative equilibrium, Monthly Notices of the Royal Astronomical Society 88: 493–502 Two bodies in radiative exchange equilibrium, each in its own local thermodynamic equilibrium, have the same temperature and their radiative exchange complies with the Stokes- Helmholtz reciprocity principle.
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Then, a 3D RI tomogram of the sample is reconstructed from these multiple 2D holographic images by inversely solving light scattering in the sample. The principle of HT is very similar to X-ray computed tomography (CT) or CT scan. CT scan measures multiple 2-D X-ray images of a human body at various illumination angles, and a 3-D tomogram (X-ray absorptivity) is then retrieved via the inverse scattering theory. Both the X-ray CT and laser HT shares the same governing equation – Helmholtz equation, the wave equation for a monochromatic wavelength.
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A shiny metal surface has low emissivity. The emissivity of a material is tremendously frequency dependent, and is related to absorptivity (of which shiny metal surfaces have very little). For most materials, the emissivity in the visible spectrum is similar to the emissivity in the infrared spectrum; however there are exceptions, notably certain metal oxides that are used as "selective surfaces". In a vacuum or in outer space, there is no convective heat transfer, thus in these environments, radiation is the only factor governing heat flow between the heat sink and the environment.
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A modular synthetic method to conjugated pentacene di-, tri- and tetramers (6–8) has been reported which is based on homo- and cross-coupling reactions of robust dehydropentacene intermediates. Non-conjugated oligomers 9–10 based on pentacene have been synthesized, including dendrimers 9–10 with up to 9 pentacene moieties per molecule with molar absorptivity for the most intense absorption > 2,000,000 M−1•cm−1. Dendrimers 11–12 were shown to have improved performance in devices compared to analogous pentacene-based polymers 4a–b in the context of photodetectors.
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In the [Mn(H2O)6]2+ metal complex, manganese has an oxidation state of +2, thus it is a d5 ion. H2O is a weak field ligand (spectrum shown below), and according to the Tanabe–Sugano diagram for d5 ions, the ground state is 6A1. Note that there is no sextet spin multiplicity in any excited state, hence the transitions from this ground state are expected to be spin-forbidden and the band intensities should be low. From the spectra, only very low intensity bands are observed (low molar absorptivity (ε) values on y-axis).
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The same phenomena makes the absorptivity of incoming radiation less than 1 and equal to emissivity (Kirchhoff's law). When radiation has not passed far enough through a homogenous medium for emission and absorption to reach thermodynamic equilibrium or when the medium changes with distance, Planck's Law and the Stefan-Boltzmann equation do not apply. This is often the case when dealing with atmospheres. If a medium is in Local Thermodynamic Equilibrium (LTE), then Schwarzschild's equation can be used to calculate how radiation changes as it travels through the medium.
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9 Design Graph for Heating and Cooling with Floor and Ceiling Panels, Panel Heating and Cooling, 2000 ASHRAE Systems and Equipment Handbook The emissivity, reflectivity and absorptivity of a floor surface are critical determinants of its heat exchange with the occupants and room. Unpolished flooring surface materials and treatments have very high emissivity's (0.85 to 0.95) and therefore make good heat radiators.Pedersen, C.O., Fisher, D.E., Lindstrom, P.C. (March, 1997), Impact of Surface Characteristics on Radiant Panel Output, ASHRAE 876 TRP With underfloor heating and cooling ("reversible floors") flooring surfaces with high absorbance and emissivity and low reflectivity are most desirable.
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Then stacked the containers horizontally behind an Equator- facing double glazing with the blackened bottoms facing outside. This water wall involves the same principles as the Trombe walls but employs a different storage material and different methods of containing that material. Like the dark colored thermal mass of the Trombe walls, the containers that store the water are also frequently painted with dark colors to increase their absorptivity, but it is also common to leave them transparent or translucent to allow some daylight to pass through. Another critical part of Trombe wall design is choosing the proper thermal mass material and thickness.
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If the absorptivity of the gas is high and the gas is present in a high enough concentration, the absorption bandwidth becomes saturated. In this case, there is enough gas present to completely absorb the radiated energy in the absorption bandwidth before the upper atmosphere is reached, and adding a higher concentration of this gas will have no additional effect on the energy budget of the atmosphere. The OLR is dependent on the temperature of the radiating body. It is affected by the Earth's skin temperature, skin surface emissivity, atmospheric temperature, water vapor profile, and cloud cover.
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In addition to the total hemispherical emissivities compiled in the table above, a more complex "directional spectral emissivity" can also be measured. This emissivity depends upon the wavelength and upon the angle of the outgoing thermal radiation. Kirchhoff's law actually applies exactly to this more complex emissivity: the emissivity for thermal radiation emerging in a particular direction and at a particular wavelength matches the absorptivity for incident light at the same wavelength and angle. The total hemispherical emissivity is a weighted average of this directional spectral emissivity; the average is described by textbooks on "radiative heat transfer".
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Educational pamphlets and school outreach has been an important way of marketing to young consumers during the twentieth century One common way that sanitary-product advertising avoids depicting menstruation is by pouring a blue, rather than red, liquid on the sanitary product to demonstrate its absorptivity. Historically, this has been due to strict censorship rules regarding menstrual product advertising. In 2010, the "Always" tampon brand created the first feminine hygiene ad to ever feature a tiny red spot, representing blood. The ad was created by intern and artist William Chyr who was working at Always' advertising agency, Leo Burnett.
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Capillary electrophoresis (CE)is emerging as the preferred analytical method for YTX analysis, as it has significant advantages over the other analytical techniques used, including high efficiency, a fast and simple separation procedure, a small sample volume required, and minimal reagent is required. The techniques used for YTX analysis include: CE with ultraviolet (UV) detection and CE coupled to mass spectrometry (MS). CEUV is a good method for YTX analysis, as its selectivity can easily differentiate between YTXs and DSP toxins. The sensitivity of these techniques can, however, be poor due to the low molar absorptivity of the analytes.
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The number densities n_2 spectrum and n_1 are set by the physical state of the gas in which the spectral line occurs, including the local spectral radiance (or, in some presentations, the local spectral radiant energy density). When that state is either one of strict thermodynamic equilibrium, or one of so- called "local thermodynamic equilibrium",Chandrasekhar, S. (1950), p. 7.Mihalas, D., Weibel-Mihalas, B. (1984), pp. 329–330. then the distribution of atomic states of excitation (which includes n_2 and n_1) determines the rates of atomic emissions and absorptions to be such that Kirchhoff's law of equality of radiative absorptivity and emissivity holds.
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The future challenges are being unable to create fully dense parts due to the processing of aluminum alloys.Aluminum powders are light-weight, have high reflectivity, high thermal conductivity, and low laser absorptivity in the range of wavelengths of the fiber lasers which are used in SLM. These challenges can be improved with doing more research in how the materials interact when being fused together. Also if more people understand the material properties and how they interact with specific heat (such as lasers) and different alloys, then there is a better chance we can understand how to avoid these defects and make this process more streamlined.
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However, because several aromatic amino acids exist, this method has low accuracy; in order to mitigate this issue, the desired protein must be pure, and its molar absorptivity is known. In addition, a protein without aromatic amino acids will not have an absorption maximum at approximately 280 nm. The presence of nucleic acids in the protein can further decrease the method's accuracy due to the presence of purine and pyrimidine rings, which have an absorption maximum at approximately 260 nm. Phenylalanine has a relatively weak absorbance in comparison to the other standard aromatic amino acids; its presence in a protein can only be detected if tryptophan and tyrosine are not present.
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Gustav Kirchhoff (18241887) In heat transfer, Kirchhoff's law of thermal radiation refers to wavelength-specific radiative emission and absorption by a material body in thermodynamic equilibrium, including radiative exchange equilibrium. A body at temperature radiates electromagnetic energy. A perfect black body in thermodynamic equilibrium absorbs all light that strikes it, and radiates energy according to a unique law of radiative emissive power for temperature , universal for all perfect black bodies. Kirchhoff's law states that: Here, the dimensionless coefficient of absorption (or the absorptivity) is the fraction of incident light (power) that is absorbed by the body when it is radiating and absorbing in thermodynamic equilibrium.
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Electrical gating and doping allows for adjustment of graphene's optical absorptivity. The application of electric fields transverse to staggered graphene bilayers generates a shift in Fermi energy and an artificial, non-zero band gap (equation 2 figure 1). Optical tunability of graphene under strong electric gating ;Equation 2: δD=Dt - Db where Dt = top electrical displacement field Db = bottom electrical displacement field Varying δD above or below zero(δD=0 denotes non-gated, neutral bilayers) allows electrons to pass through the bilayer without altering the gating-induced band gap. As shown in Figure 2, varying the average displacement field, ▁D, alters the bilayer's absorption spectra.
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Deoxypyridinoline, also called D-Pyrilinks, Pyrilinks-D, or deoxyPYD, is one of two pyridinium cross-links that provide structural stiffness to type I collagen found in bones. It is excreted unmetabolized in urine and is a specific marker of bone resorption and osteoclastic activity. It is measured in urine tests and is used along with other bone markers such as alkaline phosphatase, osteocalcin, and N-terminal telopeptide to diagnose bone diseases such as postmenopausal osteoporosis, bone metastasis, and Paget's disease, furthermore, it has been useful in monitoring treatments that contain bone- active agents such as estrogens and bisphosphonates. Certain studies have attempted to generate a standardization of Deoxypyridinoline via an individual molar absorptivity value at acid and neutrality pH.
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Here, the emitting power denotes a dimensioned quantity, the total radiation emitted by a body labeled by index at temperature . The total absorption ratio of that body is dimensionless, the ratio of absorbed to incident radiation in the cavity at temperature . (In contrast with Balfour Stewart's, Kirchhoff's definition of his absorption ratio did not refer in particular to a lamp-black surface as the source of the incident radiation.) Thus the ratio of emitting power to absorptivity is a dimensioned quantity, with the dimensions of emitting power, because is dimensionless. Also here the wavelength-specific emitting power of the body at temperature is denoted by and the wavelength-specific absorption ratio by .
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Edward A. Milne, thinking about stars, gave a definition of 'local thermodynamic equilibrium' in terms of the thermal radiation of the matter in each small local 'cell'. He defined 'local thermodynamic equilibrium' in a 'cell' by requiring that it macroscopically absorb and spontaneously emit radiation as if it were in radiative equilibrium in a cavity at the temperature of the matter of the 'cell'. Then it strictly obeys Kirchhoff's law of equality of radiative emissivity and absorptivity, with a black body source function. The key to local thermodynamic equilibrium here is that the rate of collisions of ponderable matter particles such as molecules should far exceed the rates of creation and annihilation of photons.
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This type of magnetometer depends on the variation in helium absorptivity, when excited, polarized infrared light with an applied magnetic field.Triaxial Low Field Helium Magnetometer - Mariner 5 mission National Space Science Data Center, NASA A low field vector-helium magnetometer was equipped on the Mariner 4 spacecraft to Mars like the Venus probe a year earlier, no magnetic field was detected.Helium Magnetometer- Mariner 4 mission National Space Science Data Center, NASA Mariner 5 used a similar device For this experiment a low-field helium magnetometer was used to obtain triaxial measurements of interplanetary and Venusian magnetic fields. Similar in accuracy to the triaxial flux-gated magnetometers this device produced more reliable data.
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The dye has a pH color range of 6.7-8.7. This means that below a pH of 6.7 you see one color, in this case a red-pink, and at a pH higher than 8.7 you see a different color, in this case yellow, and you see a changing orange in between. The testing procedure is incredibly simple since all you have to do is expose the sol-gel to the air and monitor the color change. Sol-gels can also be formed into monoliths, or columns, which are larger structures of sol-gel, unlike the typical thin layer. These monoliths are shown to be better for sensing molecules with smaller molar absorptivity, which are molecules that don’t absorb into something very well.
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Specular reflection from metal spheres Diffuse reflection from a marble ball When light encounters a boundary of a material, it is affected by the optical and electronic response functions of the material to electromagnetic waves. Optical processes, which comprise reflection and refraction, are expressed by the difference of the refractive index on both sides of the boundary, whereas reflectance and absorption are the real and imaginary parts of the response due to the electronic structure of the material. The degree of participation of each of these processes in the transmission is a function of the frequency, or wavelength, of the light, its polarization, and its angle of incidence. In general, reflection increases with increasing angle of incidence, and with increasing absorptivity at the boundary.
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On a "per wavelength" basis, real objects in states of local thermodynamic equilibrium still follow Kirchhoff's Law: emissivity equals absorptivity, so that an object that does not absorb all incident light will also emit less radiation than an ideal black body; the incomplete absorption can be due to some of the incident light being transmitted through the body or to some of it being reflected at the surface of the body. In astronomy, objects such as stars are frequently regarded as black bodies, though this is often a poor approximation. An almost perfect black-body spectrum is exhibited by the cosmic microwave background radiation. Hawking radiation is the hypothetical black-body radiation emitted by black holes, at a temperature that depends on the mass, charge, and spin of the hole.
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Window radiation from cloud tops arises at altitudes where the air temperature is low, but as seen from those altitudes, the water vapor content of the air above is much lower than that of the air at the land-sea surface. Moreover, the water vapour continuum absorptivity, molecule for molecule, decreases with pressure decrease. Thus water vapour above the clouds, besides being less concentrated, is also less absorptive than water vapour at lower altitudes. Consequently, the effective window as seen from the cloud-top altitudes is more open, with the result that the cloud tops are effectively strong sources of window radiation; that is to say, in effect the clouds obstruct the window only to a small degree (see another opinion about this, proposed by Ahrens (2009) on page 43).
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When an isosbestic plot is constructed by the superposition of the absorption spectra of two species (whether by using molar absorptivity for the representation, or by using absorbance and keeping the same molar concentration for both species), the isosbestic point corresponds to a wavelength at which these spectra cross each other. A pair of substances can have several isosbestic points in their spectra. When a 1-to-1 (one mole of reactant gives one mole of product) chemical reaction (including equilibria) involves a pair of substances with an isosbestic point, the absorbance of the reaction mixture at this wavelength remains invariant, regardless of the extent of reaction (or the position of the chemical equilibrium). This occurs because the two substances absorb light of that specific wavelength to the same extent, and the analytical concentration remains constant.
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Kirchhoff considered, successively, thermal equilibrium with the arbitrary non-ideal body, and with a perfectly black body of the same size and shape, in place in his cavity in equilibrium at temperature . He argued that the flows of heat radiation must be the same in each case. Thus he argued that at thermal equilibrium the ratio was equal to , which may now be denoted , a continuous function, dependent only on at fixed temperature , and an increasing function of at fixed wavelength , at low temperatures vanishing for visible but not for longer wavelengths, with positive values for visible wavelengths at higher temperatures, which does not depend on the nature of the arbitrary non-ideal body. (Geometrical factors, taken into detailed account by Kirchhoff, have been ignored in the foregoing.) Thus Kirchhoff's law of thermal radiation can be stated: For any material at all, radiating and absorbing in thermodynamic equilibrium at any given temperature , for every wavelength , the ratio of emissive power to absorptivity has one universal value, which is characteristic of a perfect black body, and is an emissive power which we here represent by .
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In the early 1970s, before the Arab Oil Embargo and the spike in oil prices, Northrup became interested in the commercialization of solar thermal systems, particularly for heating potable water and swimming pools. Such systems had already been commercialized in other countries where climatic conditions were favorable, energy costs were high, and there was a tradition of scientific innovation notably solar power in Israel. Work in the United States had been limited to academia and a few companies in Arizona, Texas, and California. Northrup began experimenting with solar collectors to heat air, using finned heat exchangers, and engaged solar pioneer Professor John Yellott as a consultant on the absorptivity and emissivity or various surfaces and configurations, and on the transparency of various glasses and glazing material that exhibit the "greenhouse effect" - transparent to incoming solar radiation, but opaque to the re-radiation of infrared from the heated surface - hence a thermal trap or collector that exhibits the "greenhouse effect". Additionally, he hired Maria Telkes, an expert on phase change materials, particularly molten salts, as a way to store thermal energy, and consulted with Israeli solar thermal pioneer Harry Tabor on surface coatings, including “black chrome” for solar panels.
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A major stimulus for the project was Friedwardt Winterberg's inertial confinement fusion drive concept,F. Winterberg, "Rocket propulsion by thermonuclear microbombs ignited with intense relativistic electron beams", Raumfahrtforschung 15, 208-217 (1971). for which he received the Hermann Oberth gold medal award.Winterberg is Hermann Oberth Gold Medalist, Physics Today, December 1979 This velocity is well beyond the capabilities of chemical rockets or even the type of nuclear pulse propulsion studied during Project Orion. According to Dr. Tony Martin, controlled-fusion engine and the nuclear–electric systems have very low thrust, equipment to convert nuclear energy into electrical has a large mass, which results in small acceleration, which would take a century to achieve the desired speed; thermodynamic nuclear engines of the NERVA type require a great quantity of fuel, photon rockets have to generate power at a rate of 3 W per kg of vehicle mass and require mirrors with absorptivity of less than 1 part in 106, interstellar ramjet's problems are tenuous interstellar medium with a density of about 1 atom/cm3, a large diameter funnel, and high power required for its electric field.
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