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Life extension The approach is based on parabiosis studies such as Irina Conboy do on mice, but Conboy says young blood does not reverse aging (even in mice) and that those who offer those treatments have misunderstood her research. Neuroscientist Tony Wyss-Coray, who also studied blood exchanges on mice as recently as... | https://en.wikipedia.org/wiki?curid=183290 |
Thermodynamic activity In chemical thermodynamics, activity (symbol ) is a measure of the "effective concentration" of a species in a mixture, in the sense that the species' chemical potential depends on the activity of a real solution in the same way that it would depend on concentration for an ideal solution. The ter... | https://en.wikipedia.org/wiki?curid=183324 |
Thermodynamic activity Two examples serve to illustrate this point: The relative activity of a species , denoted , is defined as: where is the (molar) chemical potential of the species under the conditions of interest, is the (molar) chemical potential of that species under some defined set of standard conditions, is t... | https://en.wikipedia.org/wiki?curid=183324 |
Thermodynamic activity Alternatively, it is also possible to define an "absolute activity", , which is written as: The activity coefficient , which is also a dimensionless quantity, relates the activity to a measured amount fraction (or in the gas phase), molality , mass fraction , amount concentration or mass concentr... | https://en.wikipedia.org/wiki?curid=183324 |
Thermodynamic activity By historical convention, fugacities have the dimension of pressure, so the dimensionless activity is given by: where is the dimensionless fugacity coefficient of the species, is its fraction in the gaseous mixture ( for a pure gas) and is the total pressure. The value is the standard pressure: i... | https://en.wikipedia.org/wiki?curid=183324 |
Thermodynamic activity Molalities are often preferred as the volumes of non-ideal mixtures are not strictly additive and are also temperature-dependent: molalities do not depend on volume, whereas amount concentrations do. The activity of the solute is given by: When the solute undergoes ionic dissociation in solution ... | https://en.wikipedia.org/wiki?curid=183324 |
Thermodynamic activity For non-volatile components, such as sucrose or sodium chloride, this approach will not work since they do not have measurable vapor pressures at most temperatures. However, in such cases it is possible to measure the vapor pressure of the "solvent" instead. Using the Gibbs–Duhem relation it is p... | https://en.wikipedia.org/wiki?curid=183324 |
Thermodynamic activity The value of the mean ionic activity coefficient of ions in solution can also be estimated with the Debye–Hückel equation, the Davies equation or the Pitzer equations. The prevailing view that single ion activities are unmeasurable, or perhaps even physically meaningless, has its roots in the wor... | https://en.wikipedia.org/wiki?curid=183324 |
Thermodynamic activity Chemical activities should be used to define chemical potentials, where the chemical potential depends on the temperature , pressure and the activity according to the formula: where is the gas constant and is the value of under standard conditions. Note that the choice of concentration scale affe... | https://en.wikipedia.org/wiki?curid=183324 |
Kerogen is solid, insoluble organic matter in sedimentary rocks. Consisting of an estimated 10 tons of carbon, it is the most abundant source of organic compounds on earth, exceeding the total organic content of living matter by 10,000 fold. It is insoluble in normal organic solvents and it does not have a specific che... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen , proteins and carbohydrates in the original organic matter decompose partially or completely. This breakdown process can be viewed as the reverse of photosynthesis.. These resulting units can then polycondense to form geopolymers. The formation of geopolymers in this way accounts for the large molecular weight... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen During the process of thermal maturation, kerogen breaks down in high-temperature pyrolysis reactions to form lower-molecular-weight products including bitumen, oil, and gas. The extent of thermal maturation controls the nature of the product, with lower thermal maturities yielding mainly bitumen/oil and higher... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen is insoluble in normal organic solvents in part because of its high molecular weight of its component compounds. The soluble portion is known as bitumen. When heated to the right temperatures in the earth's crust, ("oil window" c. 50–150 °C, "gas window" c. 150–200 °C, both depending on how quickly the source r... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen The first-order Raman spectra of kerogen comprises two principal peaks; a so-called G band ("graphitic") attributed to in-plane vibrational modes of well-ordered "sp" carbon and a so-called D band ("disordered") from symmetric vibrational modes of "sp" carbon associated with lattice defects and discontinuities.... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen It is found that the oxygen content of kerogen decreases during thermal maturation (as has also been observed by elemental analysis), with relatively little observable change in oxygen speciation. Similarly, sulfur speciation can be investigated with X-ray absorption near edge structure (XANES) spectroscopy, wh... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen X-ray and neutron diffraction studies have examined the spacing between carbon atoms in kerogen, revealing during thermal maturation a shortening of carbon-carbon distances in covalently bonded carbons (related to the transition from primarily aliphatic to primarily aromatic bonding) but a lengthening of carbon... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen Heterogeneity between kerogen particles may also arise from local variations in catalysis of pyrolysis reactions due to the nature of the minerals surrounding different particles. Measurements performed with atomic force microscopy coupled to infrared spectroscopy (AFM-IR) and correlated with organic petrograph... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen This classification was developed originally for coal (a sedimentary rock that is rich in organic matter of terrestrial origin) but is now applied to the study of other kerogen-rich sedimentary deposits. The Van Krevelen diagram is one method of classifying kerogen by 'types', where kerogens form distinct group... | https://en.wikipedia.org/wiki?curid=183950 |
Kerogen Type III kerogens are characterized by low initial H/C ratios and high initial O/C ratios. Type III kerogens are derived from terrestrial plant matter, specifically from precursor compounds including cellulose, lignin (a non-carbohydrate polymer formed from phenyl-propane units that binds the strings of cellulo... | https://en.wikipedia.org/wiki?curid=183950 |
Lysocline The lysocline is the depth in the ocean dependent upon the calcite compensation depth (CCD), usually around 3.5 km, below which the rate of dissolution of calcite increases dramatically because of a pressure effect. While the lysocline is the upper bound of this transition zone of calcite saturation, the CCD ... | https://en.wikipedia.org/wiki?curid=183965 |
Lysocline The equation Ω = Ca + CO/K' expresses the CaCO saturation state of seawater. The calcite saturation horizon is where Ω =1; dissolution proceeds slowly below this depth. The lysocline is the depth that this dissolution impacts is again notable, also known as the inflection point with sedimentary CaCO versus va... | https://en.wikipedia.org/wiki?curid=183965 |
Infinitesimal strain theory In continuum mechanics, the infinitesimal strain theory is a mathematical approach to the description of the deformation of a solid body in which the displacements of the material particles are assumed to be much smaller (indeed, infinitesimally smaller) than any relevant dimension of the bo... | https://en.wikipedia.org/wiki?curid=184011 |
Infinitesimal strain theory formula_1, it is possible to perform a "geometric linearization" of any one of the (infinitely many possible) strain tensors used in finite strain theory, e.g. the Lagrangian strain tensor formula_2, and the Eulerian strain tensor formula_3. In such a linearization, the non-linear or second-... | https://en.wikipedia.org/wiki?curid=184011 |
Infinitesimal strain theory , formula_1, we have The normal strain in the formula_23-direction of the rectangular element is defined by and knowing that formula_25, we have Similarly, the normal strain in the formula_27-direction, and formula_28-direction, becomes The engineering shear strain, or the change in angle be... | https://en.wikipedia.org/wiki?curid=184011 |
Infinitesimal strain theory formula_65, we have Similarly, for formula_67 and formula_68 we can find the normal strains formula_69 and formula_70, respectively. Therefore, the diagonal elements of the infinitesimal strain tensor are the normal strains in the coordinate directions. If we choose an orthonormal coordinate... | https://en.wikipedia.org/wiki?curid=184011 |
Infinitesimal strain theory If we are given the components of the strain tensor in an arbitrary orthonormal coordinate system, we can find the principal strains using an eigenvalue decomposition determined by solving the system of equations This system of equations is equivalent to finding the vector formula_85 along w... | https://en.wikipedia.org/wiki?curid=184011 |
Infinitesimal strain theory The normal strain on an octahedral plane is given by A scalar quantity called the equivalent strain, or the von Mises equivalent strain, is often used to describe the state of strain in solids. Several definitions of equivalent strain can be found in the literature. A definition that is comm... | https://en.wikipedia.org/wiki?curid=184011 |
Infinitesimal strain theory In index notation, the compatibility equations are expressed as In real engineering components, stress (and strain) are 3-D tensors but in prismatic structures such as a long metal billet, the length of the structure is much greater than the other two dimensions. The strains associated with ... | https://en.wikipedia.org/wiki?curid=184011 |
Infinitesimal strain theory Note that the displacement gradient is small only if both the strain tensor and the rotation tensor are infinitesimal. A skew symmetric second-order tensor has three independent scalar components. These three components are used to define an axial vector, formula_124, as follows where formul... | https://en.wikipedia.org/wiki?curid=184011 |
Brookite is the orthorhombic variant of titanium dioxide, TiO, which occurs in many natural polymorphic forms (minerals with the same composition but different structure). The International Mineralogical Association (IMA) recognizes four forms; the others are akaogiite (monoclinic), anatase (tetragonal) and rutile (tet... | https://en.wikipedia.org/wiki?curid=184300 |
Brookite Crystals typically tabular, elongated and striated parallel to their length. They may also be pyramidal, pseudo-hexagonal or prismatic. and rutile may grow together in an epitaxial relationship. is usually brown in color, or sometimes yellowish or reddish brown, or even black. Beautiful, deep red crystals (see... | https://en.wikipedia.org/wiki?curid=184300 |
Brookite Associated minerals include its polymorphs anatase and rutile, and also titanite, orthoclase, quartz, hematite, calcite, chlorite and muscovite. The type locality is Twll Maen Grisial, Fron Olau, Prenteg, Gwynedd, Wales, UK, and in 2004 fine brookite crystals were found at Kharan, in Balochistan, Pakistan, tog... | https://en.wikipedia.org/wiki?curid=184300 |
Titanic acid is a general name for a family of chemical compounds of the elements titanium, hydrogen, and oxygen, with the general formula [TiO(OH)]. Various simple titanic acids have been claimed, mainly in the older literature. No crystallographic and little spectroscopic support exists for these materials. Some olde... | https://en.wikipedia.org/wiki?curid=184308 |
Naphtha ( or ) is a flammable liquid hydrocarbon mixture. Mixtures labelled "naphtha" have been produced from natural gas condensates, petroleum distillates, and the distillation of coal tar and peat. In different industries and regions "naphtha" may also be crude oil or refined products such as kerosene. Mineral spiri... | https://en.wikipedia.org/wiki?curid=184342 |
Naphtha is the root of the word naphthalene, and can also be recognised in the word phthalate, and the paint colour phthalo blue. In older usage, "naphtha" simply meant crude oil, but this usage is now obsolete in English. It was also used for mineral spirits (also known as "Stoddard Solvent"), originally the main acti... | https://en.wikipedia.org/wiki?curid=184342 |
Naphtha There is a hypothesis that the word is connected with the name of the Indo-Iranian god Apam Napat, which occurs in Vedic and in Avestic; the name means "grandson of (the) waters", and the Vedas describes him as emerging from water golden and shining "with bright rays", perhaps inspired by a burning seepage of n... | https://en.wikipedia.org/wiki?curid=184342 |
Naphtha One notable example is the Zippo lighter, which draws naphtha into a wick from a reservoir to be ignited using the flint and wheel. It is also a fuel for camping stoves and oil lanterns, naphtha’s low boiling point making it easy to ignite. is sometimes preferred over kerosene due to a lower incidence of fuel l... | https://en.wikipedia.org/wiki?curid=184342 |
Benedict's reagent (often called Benedict's qualitative solution or Benedict's solution) is a chemical reagent and complex mixture of sodium carbonate, sodium citrate and copper(II) sulfate pentahydrate. It is often used in place of Fehling's solution to detect the presence of reducing sugars. The presence of other red... | https://en.wikipedia.org/wiki?curid=184383 |
Benedict's reagent During a water bath, which is usually 4–10 minutes, the solution should progress through the colors of blue (with no reducing sugar present), orange, yellow, green, red, and then brick red precipitate or brown (if a high concentration of reducing sugar is present). A color change would signify the pr... | https://en.wikipedia.org/wiki?curid=184383 |
Benedict's reagent Glucosuria can be indicative of diabetes mellitus, but Benedict's test is not recommended or used for diagnosis of the aforementioned condition. This is due to the possibility of a reaction in which the presence of other reducing substances such as ascorbic acid, drugs (levodopa, contrast used in rad... | https://en.wikipedia.org/wiki?curid=184383 |
Benedict's reagent 3 g of copper sulfate (cupric sulfate) in 100 mL of distilled water. Afterwards, one should slowly stir the copper sulfate solution with 800 mL of sodium carbonate-citrate solution. Essentials of Practical Biochemistry Benedict's quantitative reagent contains potassium thiocyanate and is used to quan... | https://en.wikipedia.org/wiki?curid=184383 |
Microbotics (or microrobotics) is the field of miniature robotics, in particular mobile robots with characteristic dimensions less than 1 mm. The term can also be used for robots capable of handling micrometer size components. Microbots were born thanks to the appearance of the microcontroller in the last decade of the... | https://en.wikipedia.org/wiki?curid=184570 |
Microbotics Indeed, much recent research has focused on microbot communication, including a 1,024 robot swarm at Harvard University that assembles itself into various shapes; and manufacturing microbots at SRI International for DARPA's "MicroFactory for Macro Products" program that can build lightweight, high-strength ... | https://en.wikipedia.org/wiki?curid=184570 |
Microbotics What microbots lack in brawn or computational power, they can make up for by using large numbers, as in swarms of microbots. The way microrobots move around is a function of their purpose and necessary size. At submicron sizes, the physical world demands rather bizarre ways of getting around. The Reynolds n... | https://en.wikipedia.org/wiki?curid=184570 |
Microbotics Examples include the use of electromagnetic fields , ultrasound and light to activate and control micro robots. | https://en.wikipedia.org/wiki?curid=184570 |
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer Another form of convection is forced convection. In this case the fluid is forced to flow by use of a pump, fan or other mechanical means. Thermal radiation occurs through a vacuum or any transparent medium (solid or fluid or gas). It is the transfer of energy by means of photons in electromagnetic waves ... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer This usage has its origin in the historical interpretation of heat as a fluid ("caloric") that can be transferred by various causes, and that is also common in the language of laymen and everyday life. The transport equations for thermal energy (Fourier's law), mechanical momentum (Newton's law for fluids... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer In other words, heat is transferred by conduction when adjacent atoms vibrate against one another, or as electrons move from one atom to another. Conduction is the most significant means of heat transfer within a solid or between solid objects in thermal contact. Fluids—especially gases—are less conductiv... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer An example of steady state conduction is the heat flow through walls of a warm house on a cold—inside the house is maintained at a high temperature, and outside the temperature stays low, so the transfer of heat per unit time stays near a constant rate determined by the insulation in the wall, and the spa... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer Bulk motion of fluid enhances heat transfer in many physical situations, such as (for example) between a solid surface and the fluid. Convection is usually the dominant form of heat transfer in liquids and gases. Although sometimes discussed as a third method of heat transfer, convection is usually used t... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer If heat conduction is too great, fluid moving down by convection is heated by conduction so fast that its downward movement will be stopped due to its buoyancy, while fluid moving up by convection is cooled by conduction so fast that its driving buoyancy will diminish. On the other hand, if heat conductio... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer Thermal radiation occurs through a vacuum or any transparent medium (solid or fluid or gas). It is the transfer of energy by means of photons in electromagnetic waves governed by the same laws. Thermal radiation is energy emitted by matter as electromagnetic waves, due to the pool of thermal energy in all... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer For example, the sunlight reflected from mirrors heats the PS10 solar power tower and during the day it can heat water to . The reachable temperature at the target is limited by the temperature of the hot source of radiation. (T-law lets the reverse-flow of radiation back to the source rise.) The (on its ... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer At standard atmospheric pressure and low temperatures, no boiling occurs and the heat transfer rate is controlled by the usual single-phase mechanisms. As the surface temperature is increased, local boiling occurs and vapor bubbles nucleate, grow into the surrounding cooler fluid, and collapse. This is "s... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer The amount of the heat is the same as that absorbed during vaporization at the same fluid pressure. There are several types of condensation: Melting is a thermal process that results in the phase transition of a substance from a solid to a liquid. The internal energy of a substance is increased, typically... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer System analysis by the lumped capacitance model is a common approximation in transient conduction that may be used whenever heat conduction within an object is much faster than heat conduction across the boundary of the object. This is a method of approximation that reduces one aspect of the transient con... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer methods are used in numerous disciplines, such as automotive engineering, thermal management of electronic devices and systems, climate control, insulation, materials processing, and power station engineering. Thermal insulators are materials specifically designed to reduce the flow of heat by limiting co... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer In the vacuum of space, satellites use multi-layer insulation, which consists of many layers of aluminized (shiny) Mylar to greatly reduce radiation heat transfer and control satellite temperature. A heat engine is a system that performs the conversion of a flow of thermal energy (heat) to mechanical ener... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer Common types of heat exchangers include shell and tube, double pipe, extruded finned pipe, spiral fin pipe, u-tube, and stacked plate. Each type has certain advantages and disadvantages over other types. A heat sink is a component that transfers heat generated within a solid material to a fluid medium, su... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface ... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer The normal temperature of the body is approximately 37 °C. occurs more readily when the temperature of the surroundings is significantly less than the normal body temperature. This concept explains why a person feels cold when not enough covering is worn when exposed to a cold environment. Clothing can be... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer Latent heat loss, also known as evaporative heat loss, accounts for a large fraction of heat loss from the body. When the core temperature of the body increases, the body triggers sweat glands in the skin to bring additional moisture to the surface of the skin. The liquid is then transformed into vapor wh... | https://en.wikipedia.org/wiki?curid=184726 |
Heat transfer 67 °F) of atomic and molecular samples to observe unique quantum effects that can only occur at this heat level. Magnetic evaporative cooling is a process for lowering the temperature of a group of atoms, after pre-cooled by methods such as laser cooling. Magnetic refrigeration cools below 0.3K, by making... | https://en.wikipedia.org/wiki?curid=184726 |
Potassium ferricyanide is the chemical compound with the formula K[Fe(CN)]. This bright red salt contains the octahedrally coordinated [Fe(CN)] ion. It is soluble in water and its solution shows some green-yellow fluorescence. It was discovered in 1822 by Leopold Gmelin, and was initially used in the production of ultr... | https://en.wikipedia.org/wiki?curid=184873 |
Potassium ferricyanide It is also used in black-and-white photography with sodium thiosulfate (hypo) to reduce the density of a negative or gelatin silver print where the mixture is known as Farmer's reducer; this can help offset problems from overexposure of the negative, or brighten the highlights in the print. The c... | https://en.wikipedia.org/wiki?curid=184873 |
Potassium ferricyanide is used in many amperometric biosensors as an electron transfer agent replacing an enzyme's natural electron transfer agent such as oxygen as with the enzyme glucose oxidase. It is used as this ingredient in many commercially available blood glucose meters for use by diabetics. is combined with p... | https://en.wikipedia.org/wiki?curid=184873 |
Reducing agent (also called a reductant or reducer) is an element or compound that loses (or "donates") an electron to an electron recipient (oxidizing agent) in a redox chemical reaction. A reducing agent is thus oxidized when it loses electrons in the redox reaction. Reducing agents "reduce" (or, are "oxidized" by) o... | https://en.wikipedia.org/wiki?curid=184881 |
Reducing agent For example, benzene is reduced to cyclohexane in the presence of a platinum catalyst: Consider the following reaction: The reducing agent in this reaction is ferrocyanide (). It donates an electron, becoming oxidized to ferricyanide (). Simultaneously, the oxidizer chlorine is reduced to chloride. Stron... | https://en.wikipedia.org/wiki?curid=184881 |
Reducing agent \text{Oxidizing agent} & \qquad \text{Reducing agent} & \hline \ce | https://en.wikipedia.org/wiki?curid=184881 |
Oxidizing agent In chemistry, an oxidizing agent (oxidant, oxidizer) is a substance that has the ability to oxidize other substances — in other words to accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxide and the halogens. In one sense, an oxidizing agent is a chemical species that undergoes a... | https://en.wikipedia.org/wiki?curid=184882 |
Oxidizing agent Notice that these species are all oxides. In some cases, these oxides can also serve as electron acceptors, as illustrated by the conversion of to , manganate. The dangerous materials definition of an oxidizing agent is a substance that can cause or contribute to the combustion of other material. By thi... | https://en.wikipedia.org/wiki?curid=184882 |
Reagent A reagent is a substance or compound added to a system to cause a chemical reaction, or added to test if a reaction occurs. The terms "reactant" and "reagent" are often used interchangeably—however, a reactant is more specifically a substance "consumed" in the course of a chemical reaction. "Solvents", though i... | https://en.wikipedia.org/wiki?curid=184897 |
Reagent For instance, reagent-quality water must have very low levels of impurities such as sodium and chloride ions, silica, and bacteria, as well as a very high electrical resistivity. Laboratory products which are less pure, but still useful and economical for undemanding work, may be designated as "technical", "pra... | https://en.wikipedia.org/wiki?curid=184897 |
Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. Particle motion results in charge-acceleration or dipole oscillation which produces electromagnetic radiation. Infrared radiation emitt... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation , protons and electrons, and kinetic interactions among matter particles result in charge-acceleration and dipole-oscillation. This results in the electrodynamic generation of coupled electric and magnetic fields, resulting in the emission of photons, radiating energy away from the body through its su... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation Due to reciprocity, absorptivity and emissivity for any particular wavelength are equal – a good absorber is necessarily a good emitter, and a poor absorber a poor emitter. The temperature determines the wavelength distribution of the electromagnetic radiation. For example, the white paint in the diag... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation At these lower frequencies, the atmosphere is largely opaque and radiation from Earth's surface is absorbed or scattered by the atmosphere. Though about 10% of this radiation escapes into space, most is absorbed and then re-emitted by atmospheric gases. It is this spectral selectivity of the atmospher... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation (In principle, any kind of lens can be used, but only the Fresnel lens design is practical for very large lenses.) Either method can be used to quickly vaporize water into steam using sunlight. For example, the sunlight reflected from mirrors heats the PS10 Solar Power Plant, and during the day it can... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation Nanostructures with spectrally selective thermal emittance properties offer numerous technological applications for energy generation and efficiency, e.g., for cooling photovoltaic cells and buildings. These applications require high emittance in the frequency range corresponding to the atmospheric tr... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation There are 4 main properties that characterize thermal radiation (in the limit of the far field): The general properties of thermal radiation as described by the Planck's law apply if the linear dimension of all parts considered, as well as radii of curvature of all surfaces are large compared with the... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation However, to take advantage of the surface-polariton-mediated near-field radiative heat transfer, the two objects need to be separated by ultra-narrow gaps on the order of microns or even nanometers. This limitation significantly complicates practical device designs. Another way to modify the object th... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation Radiation heat transfer is characteristically different from the other two in that it does not require a medium and, in fact it reaches maximum efficiency in a vacuum. Electromagnetic radiation has some proper characteristics depending on the frequency and wavelengths of the radiation. The phenomenon ... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation Planck claimed that quantities had different sizes and frequencies of vibration similarly to the wave theory. The energy E is found by the expression E = hν, where h is the Planck's constant and ν is the frequency. Higher frequencies are originated by high temperatures and create an increase of energy... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation An object is called a black body if, for all frequencies, the following formula applies: Reflectivity deviates from the other properties in that it is bidirectional in nature. In other words, this property depends on the direction of the incident of radiation as well as the direction of the reflection... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation ) Otherwise, body temperature is maintained from generated heat through internal metabolism. Human skin has an emissivity of very close to 1.0. Using the formulas below shows a human, having roughly in surface area, and a temperature of about 307 K, continuously radiates approximately 1000 watts. If p... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation Most household radiators are painted white, which is sensible given that they are not hot enough to radiate any significant amount of heat, and are not designed as thermal radiators at all – instead, they are actually convectors, and painting them matt black would make little difference to their effic... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation 8 μm) and near-infrared wavelengths, but opaque to mid- to far-wavelength infrared (approximately λ > 3 μm). Therefore, glass lets in radiation in the visible range, allowing us to be able to see through it, but does not let out radiation that is emitted from objects at or close to room temperature. T... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation "Low-emittance (low-E) coatings are microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface primarily to reduce the U-factor by suppressing radiative heat flow". By adding this coating we are limiting the amount of radiation that leav... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation power of a black body per unit area of radiating surface per unit of solid angle and per unit frequency formula_8 is given by Planck's law as: or instead of per unit frequency, per unit wavelength as This formula mathematically follows from calculation of spectral distribution of energy in quantized e... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation If it is taken as a constant, the resulting formula for the power output can be written in a way that contains formula_19 as a factor: This type of theoretical model, with frequency-independent emissivity lower than that of a perfect black body, is often known as a "grey body". For frequency-dependent... | https://en.wikipedia.org/wiki?curid=185239 |
Thermal radiation Formulas for radiative heat transfer can be derived for more particular or more elaborate physical arrangements, such as between parallel plates, concentric spheres and the internal surfaces of a cylinder. Thermal Infrared Remote Sensing: | https://en.wikipedia.org/wiki?curid=185239 |
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-binding protein domains although there may be up to 3000 human zinc metalloproteins. It is estimated t... | https://en.wikipedia.org/wiki?curid=185748 |
Metalloprotein The peptide backbone also provides donor groups; these include deprotonated amides and the amide carbonyl oxygen centers. Lead(II) binding in natural and artificial proteins has been reviewed. In addition to donor groups that are provided by amino acid residues, many organic cofactors function as ligands... | https://en.wikipedia.org/wiki?curid=185748 |
Metalloprotein It is now known that the diamagnetic nature of these species is because the iron(II) atom is in the low-spin state. In oxyhemoglobin the iron atom is located in the plane of the porphyrin ring, but in the paramagnetic deoxyhemoglobin the iron atom lies above the plane of the ring. This change in spin sta... | https://en.wikipedia.org/wiki?curid=185748 |
Metalloprotein Iron(II), on the other hand, can easily be oxidized to iron(III). This functionality is used in cytochromes, which function as electron-transfer vectors. The presence of the metal ion allows metalloenzymes to perform functions such as redox reactions that cannot easily be performed by the limited set of ... | https://en.wikipedia.org/wiki?curid=185748 |
Metalloprotein The trigonal plane of the pyramidal base is composed of two nitrogen atoms (N and N) from separate histidines and a sulfur (S) from a cysteine. Sulfur (S) from an axial methionine forms the apex. The distortion occurs in the bond lengths between the copper and sulfur ligands. The Cu−S contact is shorter ... | https://en.wikipedia.org/wiki?curid=185748 |
Metalloprotein Ceruloplasmin exhibits oxidase activity, which is associated with possible oxidation of Fe(II) into Fe(III), therefore assisting in its transport in the blood plasma in association with transferrin, which can carry iron only in the Fe(III) state. Osteopontin is involved in mineralization in the extracell... | https://en.wikipedia.org/wiki?curid=185748 |
Metalloprotein The catalytic cycle produces the bicarbonate ion and the hydrogen ion as the equilibrium favours dissociation of carbonic acid at biological pH values. The cobalt-containing Vitamin B (also known as cobalamin) catalyzes the transfer of methyl (−CH) groups between two molecules, which involves the breakin... | https://en.wikipedia.org/wiki?curid=185748 |
Metalloprotein This last is provided by a symbiotic relationship between the bacteria and a host plant, often a legume. The relationship is symbiotic because the plant supplies the energy by photosynthesis and benefits by obtaining the fixed nitrogen. The reaction may be written symbolically as where P stands for inorg... | https://en.wikipedia.org/wiki?curid=185748 |
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