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Malathion In jurisdictions which spray malathion for pest control, it is often recommended to keep windows closed and air conditioners turned off while spraying is taking place, in an attempt to minimize entry of malathion into the closed environment of residential homes. In 1981, B. T. Collins, director of the Califor... | https://en.wikipedia.org/wiki?curid=745387 |
Malathion This classification was based on the occurrence of liver tumors at excessive doses in mice and female rats and the presence of rare oral and nasal tumors in rats that occurred following exposure to very large doses. Researchers conducted a study involving participants from six Canadian provinces and found tha... | https://en.wikipedia.org/wiki?curid=745387 |
Malathion They found that a combination of five widely used insecticides (carbaryl, chlorpyrifos, diazinon, endosulfan, and malathion) in concentrations far below the limits set by the EPA killed 99% of leopard frog tadpoles. | https://en.wikipedia.org/wiki?curid=745387 |
Free-radical addition is an addition reaction in organic chemistry involving free radicals. The addition may occur between a radical and a non-radical, or between two radicals. The basic steps with examples of the free-radical addition (also known as radical chain mechanism) are: Free-radical reactions depend on a reag... | https://en.wikipedia.org/wiki?curid=745701 |
Free-radical addition As an example a nitrate radical is generated by photolysis of CAN which reacts with an alkyne to generate first a very reactive vinyl radical and then via a 1,5-hydrogen atom transfer (HAT) and 5-exo-trig ring-closure a ketyl radical. The ketyl dislodges a nitrite radical which is not reactive eno... | https://en.wikipedia.org/wiki?curid=745701 |
Bioreactor A bioreactor refers to any manufactured device or system that supports a biologically active environment. In one case, a bioreactor is a vessel in which a chemical process is carried out which involves organisms or biochemically active substances derived from such organisms. This process can either be aerobi... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor It can be applied to basically all types of biocatalysis including enzymes, cellular organelles, animal and plant cells. Immobilization is useful for continuously operated processes, since the organisms will not be removed with the reactor effluent, but is limited in scale because the microbes are only prese... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor Since oxygen is relatively insoluble in water (the basis of nearly all fermentation media), air (or purified oxygen) must be added continuously. The action of the rising bubbles helps mix the fermentation medium and also "strips" out waste gases, such as carbon dioxide. In practice, bioreactors are often pre... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor Virtually any translucent container could be called a PBR, however the term is more commonly used to define a closed system, as opposed to an open storage tank or pond. Photobioreactors are used to grow small phototrophic organisms such as cyanobacteria, algae, or moss plants. These organisms use light throu... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor Many cells and tissues, especially mammalian ones, must have a surface or other structural support in order to grow, and agitated environments are often destructive to these cell types and tissues. Higher organisms, being auxotrophic, also require highly specialized growth media. This poses a challenge when ... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor The emergence of "Biochemical engineering" is of recent origin. Processing of biological materials using biological agents such as cells, enzymes or antibodies are the major pillars of biochemical engineering. Applications of biochemical engineering cover major fields of civilization such as agriculture, foo... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor Finally, the material produced in the bioreactor must be further processed in the downstream section to convert it into more useful form. The downstream process mainly consists of physical separation operations which includes, solid liquid separation, adsorption, liquid-liquid extraction, distillation, dryin... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor , "Rate of Mass In – Rate of Mass Out + Rate of Generation = Accumulation" d(Vx)/dt = Fx – Fx + Vr (2) Where r is the rate of cell generation. Dividing both sides of the above equation by V, we obtain dx/dt = (F/V)x – (F/V)x + r (3) In the chemical reaction engineering, F/V is called space velocity(s) and V/... | https://en.wikipedia.org/wiki?curid=746495 |
Bioreactor The following equation is used to represent the net rate of cell mass growth: r = "μx (10)" "where μ" is the specific growth rate or specific growth rate coefficient(s). Here, "μ" is analogous to first order rate constant k but however, "μ" is not a constant. In biochemical engineering, yield is defined as t... | https://en.wikipedia.org/wiki?curid=746495 |
Silicon on sapphire (SOS) is a hetero-epitaxial process for metal-oxide-semiconductor (MOS) integrated circuit (IC) manufacturing that consists of a thin layer (typically thinner than 0.6 µm) of silicon grown on a sapphire (AlO) wafer. SOS is part of the silicon-on-insulator (SOI) family of CMOS (complementary MOS) tec... | https://en.wikipedia.org/wiki?curid=747222 |
Silicon on sapphire Robinson at RCA Laboratories fabricated a MOSFET (metal-oxide-semiconductor field-effect transistor) using the silicon-on-sapphire process. SOS was first used in aerospace and military applications because of its inherent resistance to radiation. More recently, patented advancements in SOS processin... | https://en.wikipedia.org/wiki?curid=747222 |
Silicon on sapphire These RFICs are designed for commercial RF applications such as mobile handsets and cellular infrastructure, broadband consumer and DTV, test and measurement, and industrial public safety, as well as rad-hard aerospace and defense markets. Hewlett Packard originally used SOS integrated circuits on t... | https://en.wikipedia.org/wiki?curid=747222 |
Silicon on insulator In semiconductor manufacturing, silicon on insulator (SOI) technology is fabrication of silicon semiconductor devices in a layered silicon–insulator–silicon substrate, to reduce parasitic capacitance within the device, thereby improving performance. SOI-based devices differ from conventional silico... | https://en.wikipedia.org/wiki?curid=747290 |
Silicon on insulator The threshold voltage of the transistor depends on the history of operation and applied voltage to it, thus making modeling harder. The primary barrier to SOI implementation is the drastic increase in substrate cost, which contributes an estimated 10–15% increase to total manufacturing costs. An SO... | https://en.wikipedia.org/wiki?curid=747290 |
Silicon on insulator The limitation of the depletion charge by the BOX induces a suppression of the depletion capacitance and therefore a substantial reduction of the subthreshold swing allowing FD SOI MOSFETs to work at lower gate bias resulting in lower power operation. The subthreshold swing can reach the minimum th... | https://en.wikipedia.org/wiki?curid=747290 |
Silicon on insulator The same year, Electrotechnical Laboratory researchers Toshihiro Sekigawa and Yutaka Hayashi fabricated a double-gate MOSFET, demonstrating that short-channel effects can be significantly reduced by sandwiching a fully depleted SOI device between two gate electrodes connected together. In 1986, Jea... | https://en.wikipedia.org/wiki?curid=747290 |
Silicon on insulator Dennard fabricated the first sub-100 nanometer SOI CMOS devices. In 1998, a team of Hitachi, TSMC and UC Berkeley researchers demonstrated the FinFET (fin field-effect transistor), which is a non-planar, double-gate MOSFET built on an SOI substrate. In early 2001, Shahidi used SOI to developed a lo... | https://en.wikipedia.org/wiki?curid=747290 |
Silicon on insulator Competitive offerings from Intel however continue to use conventional bulk CMOS technology for each process node, instead focusing on other venues such as HKMG and tri-gate transistors to improve transistor performance. In January 2005, Intel researchers reported on an experimental single-chip sili... | https://en.wikipedia.org/wiki?curid=747290 |
Styrene-butadiene or styrene-butadiene rubber (SBR) describe families of synthetic rubbers derived from styrene and butadiene (the version developed by Goodyear is called Neolite). These materials have good abrasion resistance and good aging stability when protected by additives. In 2012, more than 5.4 million tonnes o... | https://en.wikipedia.org/wiki?curid=749071 |
Styrene-butadiene In this way, various additives can be removed from the polymer. Solution-SBR is produced by an anionic polymerization process. Polymerization is initiated by alkyl lithium compounds. Water is strictly excluded. The process is homogeneous (all components are dissolved), which provides greater control o... | https://en.wikipedia.org/wiki?curid=749071 |
Styrene-butadiene In the latter application, it offers better durability, reduced shrinkage and increased flexibility, as well as being resistant to emulsification in damp conditions. SBR is often used as part of cement based substructural (basement)waterproofing systems where as a liquid it is mixed with water to form... | https://en.wikipedia.org/wiki?curid=749071 |
Raschig hydroxylamine process The Raschig process for the production of hydroxylamine is one of three chemical processes developed by German chemist Friedrich Raschig. The main step in this process, patented by Raschig in 1887, is the reduction of nitrite with bisulfite towards hydroxylamine disulfonate, which is hydro... | https://en.wikipedia.org/wiki?curid=749833 |
Zinc chloride is the name of chemical compounds with the formula ZnCl and its hydrates. Zinc chlorides, of which nine crystalline forms are known, are colorless or white, and are highly soluble in water. ZnCl itself is hygroscopic and even deliquescent. Samples should therefore be protected from sources of moisture, in... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride Molten ZnCl has a high viscosity at its melting point and a comparatively low electrical conductivity, which increases markedly with temperature. A Raman scattering study of the melt indicated the presence of polymeric structures, and a neutron scattering study indicated the presence of tetrahedral {ZnCl}... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride "Caulton's reagent", VCl(thf)ZnCl is an example of a salt containing Zn. The compound CsZnCl contains tetrahedral Zn and Cl anions. No compounds containing the Zn ion have been characterized. Whilst zinc chloride is very soluble in water, solutions cannot be considered to contain simply solvated Zn ions a... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride Sorel later went on to investigate the related magnesium oxychloride cement, which bears his name. When hydrated zinc chloride is heated, one obtains a residue of Zn(OH)Cl e.g. The compound ZnCl·HCl·HO may be prepared by careful precipitation from a solution of ZnCl acidified with HCl. It contains a polym... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride For example, solutions prepared from any of the polymorphs of ZnCl, as well as other halides (bromide, iodide), and the sulfate can often be used interchangeably for the preparation of other zinc compounds. Illustrative is the preparation of zinc carbonate: has the ability to react with metal oxides (MO) ... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride At the melting point of ZnCl (283 °C), the reaction has a Δ"G" = −1090 kJ/mol and can be idealised as The discoverers of this reaction rationalized it as involving condensation of methylene units followed by complete Friedel-Crafts methylation of the resulting benzene ring with chloromethane generated "in... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride is also a useful starting reagent for the synthesis of many organozinc reagents, such as those used in the palladium catalyzed Negishi coupling with aryl halides or vinyl halides. In such cases the organozinc compound is usually prepared by transmetallation from an organolithium or a Grignard reagent, for... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride Spraying with a zinc chloride solution forms a 1:1 complex RP:ZnCl(HO), which is more readily detected as it fluoresces better than Ruhemann's purple. Historically, a dilute aqueous solution of zinc chloride was used as a disinfectant under the name "Burnett's Disinfecting Fluid". has been used in alterna... | https://en.wikipedia.org/wiki?curid=752048 |
Zinc chloride Decontamination of the gastrointestinal tract after oral uptake of zinc compounds is mostly unnecessary, since patients usually vomit sufficiently. Milk may be administered to decrease absorption of the metal. Zinc levels may be normalized with EDTA salts. is extremely detrimental to the lungs, and pulmon... | https://en.wikipedia.org/wiki?curid=752048 |
Drying oil A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air. The oil hardens through a chemical reaction in which the components crosslink (and hence, polymerize) by the action of oxygen (not through the evaporation of water or other solvents). Drying oils are a key component... | https://en.wikipedia.org/wiki?curid=752713 |
Drying oil This polymerization results in stable films that, while somewhat elastic, do not flow or deform readily. Diene-containing fatty acid derivatives, such as those derived from linoleic acid, are especially prone to this reaction because they generate pentadienyl radicals. Monounsaturated fatty acids, such as ol... | https://en.wikipedia.org/wiki?curid=752713 |
Drying oil Carboxyl groups in the polymers of the stationary phase ionize, becoming negatively charged and form complexes with metal cations present in the pigment. The original network, with its nonpolar, covalent bonds, is replaced by an ionomeric structure, held together by ionic interactions. The structure of these... | https://en.wikipedia.org/wiki?curid=752713 |
Drying oil Drying oils consist of glycerol triesters of fatty acids. These esters are characterized by high levels of polyunsaturated fatty acids, especially alpha-linolenic acid. One common measure of the "siccative" (drying) property of oils is iodine number, which is an indicator of the number of double bonds in the... | https://en.wikipedia.org/wiki?curid=752713 |
Drying oil Linseed oil-soaked rags were the cause of the big fire in the One Meridian Plaza 38-storey office building resulting in severe structural damage, after which a decision was made to demolish the building. Although spontaneous combustion has been said to occur with rags soaked in paint thinners, this is not tr... | https://en.wikipedia.org/wiki?curid=752713 |
Bosch reaction The is a chemical reaction between carbon dioxide and hydrogen that produces elemental carbon (graphite), water, and a 10% return of invested heat. It is named after the German chemist Carl Bosch. This reaction requires the introduction of iron as a catalyst and requires a temperature level of 530-730 de... | https://en.wikipedia.org/wiki?curid=752861 |
Bosch reaction One problem is that the production of elemental carbon tends to foul the catalyst's surface, which is detrimental to the reaction's efficiency. | https://en.wikipedia.org/wiki?curid=752861 |
Circulation (fluid dynamics) In fluid dynamics, circulation is the line integral of the velocity field, around a closed curve. Circulation is normally denoted Γ (Greek uppercase gamma). Circulation was first used independently by Frederick Lanchester, Martin Kutta and Nikolai Zhukovsky. If V is the fluid velocity on a ... | https://en.wikipedia.org/wiki?curid=753962 |
Circulation (fluid dynamics) When an airfoil is generating lift the circulation around the airfoil is finite, and is related to the vorticity of the boundary layer. Outside the boundary layer the vorticity is zero everywhere and therefore the circulation is the same around every circuit, regardless of the length of the... | https://en.wikipedia.org/wiki?curid=753962 |
Permeability (electromagnetism) In electromagnetism, permeability is the measure of the resistance of a material against the formation of a magnetic field, otherwise known as distributed inductance in transmission line theory. Hence, it is the degree of magnetization that a material obtains in response to an applied ma... | https://en.wikipedia.org/wiki?curid=754487 |
Permeability (electromagnetism) In electromagnetism, the auxiliary magnetic field H represents how a magnetic field B influences the organization of magnetic dipoles in a given medium, including dipole migration and magnetic dipole reorientation. Its relation to permeability is where the permeability, "μ", is a scalar ... | https://en.wikipedia.org/wiki?curid=754487 |
Permeability (electromagnetism) The product "μ"H thus has dimensions inductance times current per unit area (H⋅A/m). But inductance is magnetic flux per unit current, so the product has dimensions magnetic flux per unit area, that is, magnetic flux density. This is the magnetic field B, which is measured in webers (vol... | https://en.wikipedia.org/wiki?curid=754487 |
Permeability (electromagnetism) "Diamagnetism" is the property of an object which causes it to create a magnetic field in opposition of an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their nuclei, thus chang... | https://en.wikipedia.org/wiki?curid=754487 |
Permeability (electromagnetism) Even in the presence of the field, there is only a small "induced" magnetization because only a small fraction of the spins will be oriented by the field. This fraction is proportional to the field strength and this explains the linear dependency. The attraction experienced by ferromagne... | https://en.wikipedia.org/wiki?curid=754487 |
Permeability (electromagnetism) A useful tool for dealing with high frequency magnetic effects is the complex permeability. While at low frequencies in a linear material the magnetic field and the auxiliary magnetic field are simply proportional to each other through some scalar permeability, at high frequencies these ... | https://en.wikipedia.org/wiki?curid=754487 |
Permeability (Earth sciences) Permeability in fluid mechanics and the Earth sciences (commonly symbolized as "k") is a measure of the ability of a porous material (often, a rock or an unconsolidated material) to allow fluids to pass through it. The permeability of a medium is related to the porosity, but also to the sh... | https://en.wikipedia.org/wiki?curid=754488 |
Permeability (Earth sciences) The concept of permeability is of importance in determining the flow characteristics of hydrocarbons in oil and gas reservoirs, and of groundwater in aquifers . For a rock to be considered as an exploitable hydrocarbon reservoir without stimulation, its permeability must be greater than ap... | https://en.wikipedia.org/wiki?curid=754488 |
Permeability (Earth sciences) Given the value of hydraulic conductivity for a subsurface system, the permeability can be calculated as follows: formula_10 Permeability is typically determined in the lab by application of Darcy's law under steady state conditions or, more generally, by application of various solutions t... | https://en.wikipedia.org/wiki?curid=754488 |
Permeability (Earth sciences) 1 μm at standard temperature and pressure). See also Knudsen diffusion and constrictivity. For example, measurement of permeability through sandstones and shales yielded values from 9.0×10 m to 2.4×10 m for water and between 1.7×10 m to 2.6×10 m for nitrogen gas. Gas permeability of reserv... | https://en.wikipedia.org/wiki?curid=754488 |
C12H22O11 The molecular form CHO (molar mass: 342.29 g/mol, exact mass : 342.116212) may refer to: | https://en.wikipedia.org/wiki?curid=754708 |
Working fluid For fluid power, a working fluid is a gas or liquid that primarily transfers force, motion, or mechanical energy. In hydraulics, water or hydraulic fluid transfers force between hydraulic components such as hydraulic pumps, hydraulic cylinders, and hydraulic motors that are assembled into hydraulic machin... | https://en.wikipedia.org/wiki?curid=755268 |
Working fluid Examples without phase change include air or hydrogen in hot air engines such as the Stirling engine, air or gases in gas-cycle heat pumps, etc. (Some heat pumps and heat engines use "working solids", such as rubber bands, for elastocaloric refrigeration or thermoelastic cooling and nickel titanium in a p... | https://en.wikipedia.org/wiki?curid=755268 |
Working fluid In reality however this can only be done if the process is reversible. If not, the changes in property are represented as a dotted line on a property diagram. This issue does not really affect thermodynamic analysis since in most cases it is the end states of a process which are sought after. The working ... | https://en.wikipedia.org/wiki?curid=755268 |
Working fluid If we consider the case where we have a constant pressure process then the work is simply given by Depending on the application, various types of working fluids are used. In a thermodynamic cycle it may be the case that the working fluid changes state from gas to liquid or vice versa. Certain gases such a... | https://en.wikipedia.org/wiki?curid=755268 |
Working fluid Different working fluids have different properties and in choosing one in particular the designer must identify the major requirements. In refrigeration units, high latent heats are required to provide large refrigeration capacities. The following table gives typical applications of working fluids and exa... | https://en.wikipedia.org/wiki?curid=755268 |
Settling basin A settling basin, settling pond or decant pond is an earthen or concrete structure using sedimentation to remove settleable matter and turbidity from wastewater. The basins are used to control water pollution in diverse industries such as agriculture, aquaculture, and mining. Turbidity is an optical prop... | https://en.wikipedia.org/wiki?curid=757300 |
Settling basin If impairment occurs in any of these functions, this might have a great impact on pond performance, which could lead to damaging the effectiveness of the process. Wastewater produced by mining industries contribute to the acidity, suspended material and dissolved heavy metal ions in the aquatic environme... | https://en.wikipedia.org/wiki?curid=757300 |
Settling basin There are two types of settling basins, based on the method of removing solids. With one type, the solids are removed mechanically (after the free water has drained away), usually with a front-end or skid-steer loader. The other type uses hydraulic (pump) removal of the solids. Typically, pumping is init... | https://en.wikipedia.org/wiki?curid=757300 |
Settling basin Usually, it can only remove particles ranging from sand (2mm in diameter) to silt (0.002mm in diameter). Wastewater enters the basin and very fine particles in the water are separated by means of gravity. The water must be in the basin long enough for the desired particle size to be removed. Smaller part... | https://en.wikipedia.org/wiki?curid=757300 |
Settling basin Settling basins with overflow structures near the entrance points may hold a large volume of stagnant water while newly admitted water rapidly reaches the overflow point before settling can occur. Effective surface area for settling seldom extends perpendicularly more than a tenth the distance of a flow ... | https://en.wikipedia.org/wiki?curid=757300 |
Fosinopril is an angiotensin converting enzyme (ACE) inhibitor used for the treatment of hypertension and some types of chronic heart failure. is the only phosphinate-containing ACE inhibitor marketed, by Bristol-Myers Squibb under the trade name Monopril. It was patented in 1980 and approved for medical use in 1991. I... | https://en.wikipedia.org/wiki?curid=757705 |
Fosinopril In heart failure patients, fosinopril increases exercise tolerance and lowers the frequency of events associated with worsening heart failure, such as dyspnea, the need for supplemental diuretics, fatigue, and hospitalizations. Unlike other ACE inhibitors that are primarily excreted by the kidneys, fosinopri... | https://en.wikipedia.org/wiki?curid=757705 |
Aaron Klug Sir (11 August 1926 – 20 November 2018) was a Lithuanian-born, South African-educated, British biophysicist, and winner of the 1982 Nobel Prize in Chemistry for his development of crystallographic electron microscopy and his structural elucidation of biologically important nucleic acid-protein complexes. Klu... | https://en.wikipedia.org/wiki?curid=758556 |
Aaron Klug Over the following decade Klug used methods from X-ray diffraction, microscopy and structural modelling to develop crystallographic electron microscopy in which a sequence of two-dimensional images of crystals taken from different angles are combined to produce three-dimensional images of the target. He stud... | https://en.wikipedia.org/wiki?curid=758556 |
Aaron Klug His certificate of election to the Royal Society reads: In 2005 he was awarded South Africa's Order of Mapungubwe (gold) for exceptional achievements in medical science. He was elected a Fellow of the Academy of Medical Sciences (FMedSci). In 2013, Israel's Ben-Gurion University of the Negev dedicated their ... | https://en.wikipedia.org/wiki?curid=758556 |
Didymium () is a mixture of the elements praseodymium and neodymium. It is used in safety glasses for glassblowing and blacksmithing, especially with a gas (propane)-powered forge, where it provides a filter that selectively blocks the yellowish light at 589 nm emitted by the hot sodium in the glass, without having a d... | https://en.wikipedia.org/wiki?curid=758637 |
Didymium Mosander wrongly believed didymium to be an element, under the impression that "ceria" (sometimes called cerite) isolated by Jöns Jakob Berzelius in 1803 was really a mixture of cerium, lanthanum and didymium. He was right about lanthanum's being an element, but not about didymium. Mosander did as well as coul... | https://en.wikipedia.org/wiki?curid=758637 |
Didymium Welsbach had decided to name his two new elements "praseodidymium" and "neodidymium" ("green didymium" and "new didymium"), but one syllable was soon dropped from each name. The name of "didymium" lived on in untruncated version, partly due to the use in glassblower's goggles. The name "didymium" also lived on... | https://en.wikipedia.org/wiki?curid=758637 |
Didymium Neodymium always dominates, which is why it got the "neo" appellation, being responsible for most of the color of the old didymium in its salts. Typically, in ores, neodymium is higher in relative abundance in monazite, as compared to the bastnäsite compositions, and the difference is noticeable when unseparat... | https://en.wikipedia.org/wiki?curid=758637 |
Didymium The earlier date of 1925 sometimes given for rare earth glass refers to an award for glass design, not glass composition. | https://en.wikipedia.org/wiki?curid=758637 |
George Andrew Olah (born Oláh György; May 22, 1927 – March 8, 2017) was a Hungarian and American chemist. His research involved the generation and reactivity of carbocations via superacids. For this research, Olah was awarded a Nobel Prize in Chemistry in 1994 "for his contribution to carbocation chemistry." He was als... | https://en.wikipedia.org/wiki?curid=758753 |
George Andrew Olah In 1965, he returned to academia at Case Western Reserve University in Cleveland, Ohio, chairing the Department of Chemistry from 1965 to 1969, and from 1967 through 1977 he was the C. F. Maybery Distinguished Professor of Research in Chemistry. In 1971, Olah became a naturalized citizen of the Unite... | https://en.wikipedia.org/wiki?curid=758753 |
George Andrew Olah Olah's studies of the cation with NMR spectroscopy provided more evidence suggesting that Winstein's model of the non-classical cation, "featuring a pair of [delocalized] electrons smeared between three carbon atoms," was correct. In 1997, the Olah family formed an endowment fund (the George A. Olah ... | https://en.wikipedia.org/wiki?curid=758753 |
Paul Ambrose Oliver (July 18, 1831 – May 17, 1912) was an American explosives inventor, American Civil War Union Army captain and staff officer who was appointed to the brevet grade of brigadier general and Medal of Honor recipient. He was born on the "Louisiana", his father's merchant ship, during one of its voyages i... | https://en.wikipedia.org/wiki?curid=758808 |
Amount of substance In chemistry, the amount of substance in a given sample of matter is defined as the number of discrete atomic-scale particles in it divided by the Avogadro constant "N". In a truly atomistic view, the amount of substance is simply the number of particles that constitute the substance. The particles ... | https://en.wikipedia.org/wiki?curid=759264 |
Amount of substance In chemistry, because of the law of multiple proportions, it is often much more convenient to work with amounts of substances (that is, number of moles or of molecules) than with masses (grams) or volumes (liters). For example, the chemical fact "1 molecule of oxygen () will react with 2 molecules o... | https://en.wikipedia.org/wiki?curid=759264 |
Amount of substance There are proposals to replace "amount of substance" with more easily-distinguishable terms, such as enplethy and stoichiometric amount. The IUPAC recommends that "amount of substance" should be used instead of "number of moles", just as the quantity mass should not be called "number of kilograms". ... | https://en.wikipedia.org/wiki?curid=759264 |
Amount of substance Likewise, 1 mol of solid silicon dioxide (), which has a three-dimensional covalent lattice structure, is understood to contain one mole of silicon atoms and two moles of oxygen atoms. For substances that normally exist in partially dissociated or polymerized form, the amount of substance usually re... | https://en.wikipedia.org/wiki?curid=759264 |
Amount of substance Another important derived quantity is the amount of substance concentration (also called "amount concentration", or "substance concentration" in clinical chemistry; which is defined as the amount of a specific substance in a sample of a solution (or some other mixture), divided by the volume of the ... | https://en.wikipedia.org/wiki?curid=759264 |
Amount of substance Confusingly, the amount concentration, or "molarity", should also be distinguished from "molar concentration", which should be the number of moles (molecules) of the substance of interest divided by the total number of moles (molecules) in the solution sample. This quantity is more properly called t... | https://en.wikipedia.org/wiki?curid=759264 |
Anomer An anomer is a type of geometric variation found at certain atoms in carbohydrate molecules. An epimer is a stereoisomer that differs in configuration at any single stereogenic center. An anomer is an epimer at the hemiacetal/acetal carbon in a cyclic saccharide, an atom called the anomeric carbon. The anomeric ... | https://en.wikipedia.org/wiki?curid=760606 |
Anomer If the two oxygens are trans (on different sides) the anomer is β. Thus, the absolute configurations of the anomeric carbon and the reference atom are the same (both "R" or both "S") in the α anomer and opposite (one "R" and the other "S") in the β anomer. Anomerization is the process of conversion of one anomer... | https://en.wikipedia.org/wiki?curid=760606 |
Anomer Which side it attacks on determines whether the α- or β-anomer is formed. Anomerization of glycosides typically occurs under acidic conditions. Typically, anomerization occurs through protonation of the exocyclic acetal oxygen, ionization to form an oxocarbenium ion with release of an alcohol, and nucleophilic a... | https://en.wikipedia.org/wiki?curid=760606 |
Electron mobility In solid-state physics, the electron mobility characterises how quickly an electron can move through a metal or semiconductor, when pulled by an electric field. There is an analogous quantity for holes, called hole mobility. The term carrier mobility refers in general to both electron and hole mobilit... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility Almost always, higher mobility leads to better device performance, with other things equal. Semiconductor mobility depends on the impurity concentrations (including donor and acceptor concentrations), defect concentration, temperature, and electron and hole concentrations. It also depends on the elect... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility Quasi-ballistic transport is possible in solids if the electrons are accelerated across a very small distance (as small as the mean free path), or for a very short time (as short as the mean free time). In these cases, drift velocity and mobility are not meaningful. The electron mobility is defined by... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility Therefore, the electrical conductivity σ satisfies: This formula is valid when the conductivity is due entirely to electrons. In a p-type semiconductor, the conductivity is due to holes instead, but the formula is essentially the same: If "p" is the concentration of holes and μ is the hole mobility, t... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility It is one of the key material and semiconductor device properties that determine a device such as a transistor's ultimate limit of speed of response and frequency. This velocity saturation phenomenon results from a process called "optical phonon scattering". At high fields, carriers are accelerated en... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility Recall that by definition, mobility is dependent on the drift velocity. The main factor determining drift velocity (other than effective mass) is scattering time, i.e. how long the carrier is ballistically accelerated by the electric field until it scatters (collides) with something that changes its d... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility The amount of deflection depends on the speed of the carrier and its proximity to the ion. The more heavily a material is doped, the higher the probability that a carrier will collide with an ion in a given time, and the smaller the mean free time between collisions, and the smaller the mobility. When... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility A phonon can interact (collide) with an electron (or hole) and scatter it. At higher temperature, there are more phonons, and thus increased electron scattering, which tends to reduce mobility. Piezoelectric effect can occur only in compound semiconductor due to their polar nature. It is small in most... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility This can only happen in ternary or higher alloys as their crystal structure forms by randomly replacing some atoms in one of the sublattices (sublattice) of the crystal structure. Generally, this phenomenon is quite weak but in certain materials or circumstances, it can become dominant effect limiting... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility A simple model gives the approximate relation between scattering time (average time between scattering events) and mobility. It is assumed that after each scattering event, the carrier's motion is randomized, so it has zero average velocity. After that, it accelerates uniformly in the electric field, ... | https://en.wikipedia.org/wiki?curid=760994 |
Electron mobility This rule is not valid if the factors affecting the mobility depend on each other, because individual scattering probabilities cannot be summed unless they are independent of each other. The average free time of flight of a carrier and therefore the relaxation time is inversely proportional to the sca... | https://en.wikipedia.org/wiki?curid=760994 |
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