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Opal | Sources | Andamooka in South Australia is also a major producer of matrix opal, crystal opal, and black opal. Another Australian town, Lightning Ridge in New South Wales, is the main source of black opal, opal containing a predominantly dark background (dark gray to blue-black displaying the play of color), collected from the Gr... |
Opal | Sources | Ethiopia It has been reported that Northern African opal was used to make tools as early as 4000 BC. The first published report of gem opal from Ethiopia appeared in 1994, with the discovery of precious opal in the Menz Gishe District, North Shewa Province. The opal, found mostly in the form of nodules, was of volcanic... |
Opal | Sources | Virgin Valley, Nevada The Virgin Valley opal fields of Humboldt County in northern Nevada produce a wide variety of precious black, crystal, white, fire, and lemon opal. The black fire opal is the official gemstone of Nevada. Most of the precious opal is partial wood replacement. The precious opal is hosted and found i... |
Opal | Sources | Mexico Fire opal is a transparent to translucent opal with warm body colors of yellow to orange to red. Although fire opals don't usually show any play of color, they occasionally exhibit bright green flashes. The most famous source of fire opals is the state of Querétaro in Mexico; these opals are commonly called Mexi... |
Opal | Sources | The oldest mine in Querétaro is Santa Maria del Iris. This mine was opened around 1870 and has been reopened at least 28 times since. At the moment there are about 100 mines in the regions around Querétaro, but most of them are now closed. The best quality of opals came from the mine Santa Maria del Iris, followed by L... |
Opal | Sources | In 1957, Alfonso Ramirez (of Querétaro) accidentally discovered the first opal mine in Jalisco: La Unica, located on the outer area of the volcano of Tequila, near the Huitzicilapan farm in Magdalena. By 1960 there were around 500 known opal mines in this region alone. Other regions of the country that also produce opa... |
Opal | Sources | Other locations Another source of white base opal or creamy opal in the United States is Spencer, Idaho. A high percentage of the opal found there occurs in thin layers.
Other significant deposits of precious opal around the world can be found in the Czech Republic, Canada, Slovakia, Hungary, Turkey, Indonesia, Brazil ... |
Opal | Synthetic opal | Opals of all varieties have been synthesized experimentally and commercially. The discovery of the ordered sphere structure of precious opal led to its synthesis by Pierre Gilson in 1974. The resulting material is distinguishable from natural opal by its regularity; under magnification, the patches of color are seen to... |
Opal | Synthetic opal | Opals which have been created in a laboratory are often termed "lab-created opals", which, while classifiable as man-made and synthetic, are very different from their resin-based counterparts which are also considered man-made and synthetic. The term "synthetic" implies that a stone has been created to be chemically an... |
Opal | Synthetic opal | Other research in macroporous structures have yielded highly ordered materials that have similar optical properties to opals and have been used in cosmetics. Synthetic opals are also deeply investigated in photonics for sensing and light management purposes. |
Opal | Local atomic structure of opals | The lattice of spheres of opal that cause interference with light is several hundred times larger than the fundamental structure of crystalline silica. As a mineraloid, no unit cell describes the structure of opal. Nevertheless, opals can be roughly divided into those that show no signs of crystalline order (amorphous ... |
Opal | Local atomic structure of opals | The structure of low-pressure polymorphs of anhydrous silica consists of frameworks of fully corner bonded tetrahedra of SiO4. The higher temperature polymorphs of silica cristobalite and tridymite are frequently the first to crystallize from amorphous anhydrous silica, and the local structures of microcrystalline opal... |
Opal | Local atomic structure of opals | Microcrystalline opal Microcrystalline opal or Opal-CT has been interpreted as consisting of clusters of stacked cristobalite and tridymite over very short length scales. The spheres of opal in microcrystalline opal are themselves made up of tiny nanocrystalline blades of cristobalite and tridymite. Microcrystalline op... |
Opal | Local atomic structure of opals | Noncrystalline opal Two broad categories of noncrystalline opals, sometimes just referred to as "opal-A" ("A" stands for "amorphous"), have been proposed. The first of these is opal-AG consisting of aggregated spheres of silica, with water filling the space in between. Precious opal and potch opal are generally varieti... |
Opal | Local atomic structure of opals | Noncrystalline silica in siliceous sediments is reported to gradually transform to opal-CT and then opal-C as a result of diagenesis, due to the increasing overburden pressure in sedimentary rocks, as some of the stacking disorder is removed.
Opal surface chemical groups The surface of opal in contact with water is cov... |
Opal | Etymology | The word 'opal' is adapted from the Latin term opalus. The origin of this word in turn is a matter of debate, but most modern references suggest it is adapted from the Sanskrit word úpala meaning ‘precious stone’.References to the gem are made by Pliny the Elder. It is suggested to have been adapted from Ops, the wife ... |
Opal | Etymology | Another common claim that the term is adapted from the Ancient Greek word, opallios. This word has two meanings, one is related to "seeing" and forms the basis of the English words like "opaque"; the other is "other" as in "alias" and "alter". It is claimed that opalus combined these uses, meaning "to see a change in c... |
Opal | Historical superstitions | In the Middle Ages, opal was considered a stone that could provide great luck because it was believed to possess all the virtues of each gemstone whose color was represented in the color spectrum of the opal. It was also said to grant invisibility if wrapped in a fresh bay leaf and held in the hand. As a result, the op... |
Opal | Examples | The Olympic Australis, the world's largest and most valuable gem opal, found in Coober Pedy The Andamooka Opal, presented to Queen Elizabeth II, also known as the Queen's Opal The Addyman Plesiosaur from Andamooka, "the finest known opalised skeleton on Earth" The Burning of Troy, the now-lost opal presented to Joséphi... |
Trophic level | Trophic level | The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with prima... |
Trophic level | Trophic level | The word trophic derives from the Greek τροφή (trophē) referring to food or nourishment. |
Trophic level | History | The concept of trophic level was developed by Raymond Lindeman (1942), based on the terminology of August Thienemann (1926): "producers", "consumers", and "reducers" (modified to "decomposers" by Lindeman). |
Trophic level | Overview | The three basic ways in which organisms get food are as producers, consumers, and decomposers. |
Trophic level | Overview | Producers (autotrophs) are typically plants or algae. Plants and algae do not usually eat other organisms, but pull nutrients from the soil or the ocean and manufacture their own food using photosynthesis. For this reason, they are called primary producers. In this way, it is energy from the sun that usually powers the... |
Trophic level | Overview | Consumers (heterotrophs) are species that cannot manufacture their own food and need to consume other organisms. Animals that eat primary producers (like plants) are called herbivores. Animals that eat other animals are called carnivores, and animals that eat both plants and other animals are called omnivores. |
Trophic level | Overview | Decomposers (detritivores) break down dead plant and animal material and wastes and release it again as energy and nutrients into the ecosystem for recycling. Decomposers, such as bacteria and fungi (mushrooms), feed on waste and dead matter, converting it into inorganic chemicals that can be recycled as mineral nutrie... |
Trophic level | Overview | Level 1 Plants and algae make their own food and are called producers.
Level 2 Herbivores eat plants and are called primary consumers.
Level 3 Carnivores that eat herbivores are called secondary consumers.
Level 4 Carnivores that eat other carnivores are called tertiary consumers.
Apex predator By definition, healthy a... |
Trophic level | Overview | In real-world ecosystems, there is more than one food chain for most organisms, since most organisms eat more than one kind of food or are eaten by more than one type of predator. A diagram that sets out the intricate network of intersecting and overlapping food chains for an ecosystem is called its food web. Decompose... |
Trophic level | Biomass transfer efficiency | In general, each trophic level relates to the one below it by absorbing some of the energy it consumes, and in this way can be regarded as resting on, or supported by, the next lower trophic level. Food chains can be diagrammed to illustrate the amount of energy that moves from one feeding level to the next in a food c... |
Trophic level | Evolution | Both the number of trophic levels and the complexity of relationships between them evolve as life diversifies through time, the exception being intermittent mass extinction events. |
Trophic level | Fractional trophic levels | Food webs largely define ecosystems, and the trophic levels define the position of organisms within the webs. But these trophic levels are not always simple integers, because organisms often feed at more than one trophic level. For example, some carnivores also eat plants, and some plants are carnivores. A large carniv... |
Trophic level | Fractional trophic levels | The fisheries scientist Daniel Pauly sets the values of trophic levels to one in plants and detritus, two in herbivores and detritivores (primary consumers), three in secondary consumers, and so on. The definition of the trophic level, TL, for any consumer species is: TLi=1+∑j(TLj⋅DCij) where TLj is the fractional tro... |
Trophic level | Fractional trophic levels | In the case of marine ecosystems, the trophic level of most fish and other marine consumers takes a value between 2.0 and 5.0. The upper value, 5.0, is unusual, even for large fish, though it occurs in apex predators of marine mammals, such as polar bears and orcas.In addition to observational studies of animal behavio... |
Trophic level | Mean trophic level | In fisheries, the mean trophic level for the fisheries catch across an entire area or ecosystem is calculated for year y as: TLy=∑i(TLi⋅Yiy)∑iYiy where Yiy is the annual catch of the species or group i in year y, and TLi is the trophic level for species i as defined above.Fish at higher trophic levels usually have a ... |
Trophic level | FiB index | Since biomass transfer efficiencies are only about 10%, it follows that the rate of biological production is much greater at lower trophic levels than it is at higher levels. Fisheries catch, at least, to begin with, will tend to increase as the trophic level declines. At this point the fisheries will target species lo... |
Trophic level | FiB index | The FiB index is stable (zero) over periods of time when changes in trophic levels are matched by appropriate changes in the catch in the opposite direction. The index increases if catches increase for any reason, e.g. higher fish biomass, or geographic expansion. Such decreases explain the "backward-bending" plots of ... |
Trophic level | Tritrophic and other interactions | One aspect of trophic levels is called tritrophic interaction. Ecologists often restrict their research to two trophic levels as a way of simplifying the analysis; however, this can be misleading if tritrophic interactions (such as plant–herbivore–predator) are not easily understood by simply adding pairwise interactio... |
Cetrimonium bromide | Cetrimonium bromide | Cetrimonium bromide ([(C16H33)N(CH3)3]Br; cetyltrimethylammonium bromide; hexadecyltrimethylammonium bromide; CTAB) is a quaternary ammonium surfactant. |
Cetrimonium bromide | Cetrimonium bromide | It is one of the components of the topical antiseptic cetrimide. The cetrimonium (hexadecyltrimethylammonium) cation is an effective antiseptic agent against bacteria and fungi. It is also one of the main components of some buffers for the extraction of DNA. It has been widely used in synthesis of gold nanoparticles (e... |
Cetrimonium bromide | Cetrimonium bromide | As with most surfactants, CTAB forms micelles in aqueous solutions. At 303 K (30 °C) it forms micelles with aggregation number 75-120 (depending on method of determination; average ~95) and degree of ionization, α = 0.2–0.1 (fractional charge; from low to high concentration). The binding constant (K°) of Br− counterion... |
Cetrimonium bromide | Applications | Biological Cell lysis is a convenient tool to isolate certain macromolecules that exist primarily inside of the cell. Cell membranes consist of hydrophilic and lipophilic endgroups. Therefore, detergents are often used to dissolve these membranes since they interact with both polar and nonpolar endgroups. CTAB has emer... |
Cetrimonium bromide | Applications | Medical CTAB has been shown to have potential use as an apoptosis-promoting anticancer agent for head and neck cancer (HNC). In vitro, CTAB interacted additively with γ radiation and cisplatin, two standard HNC therapeutic agents. CTAB exhibited anticancer cytotoxicity against several HNC cell lines with minimal effect... |
Cetrimonium bromide | Applications | Protein electrophoresis Glycoproteins form broad, fuzzy bands in SDS-PAGE (Laemmli-electrophoresis) because of their broad distribution of negative charges. Using positively charged detergents such as CTAB will avoid issues associated with glycoproteins. Proteins can be blotted from CTAB-gels in analogy to western blot... |
Cetrimonium bromide | Applications | DNA extraction CTAB serves as an important surfactant in the DNA extraction buffer system to remove membrane lipids and promote cell lysis. Separation is also successful when the tissue contains high amounts of polysaccharides. CTAB binds to the polysaccharides when the salt concentration is high, thus removing polysac... |
Cetrimonium bromide | Nanoparticle synthesis | Surfactants play a key role in nanoparticle synthesis by adsorbing to the surface of the forming nanoparticle and lowering its surface energy. Surfactants also help to prevent aggregation (e.g. via DLVO mechanisms). |
Cetrimonium bromide | Nanoparticle synthesis | Au nanoparticle synthesis Gold (Au) nanoparticles are interesting to researchers because of their unique properties that can be used in applications such as catalysis, optics, electronics, sensing, and medicine. Control of nanoparticle size and shape is important in order to tune its properties. CTAB has been a widely ... |
Cetrimonium bromide | Nanoparticle synthesis | Some of this control originates from the reaction of CTAB with other reagents in the gold nanoparticle synthesis. For example, in aqueous gold nanoparticle syntheses, chlorauric acid (HAuCl4) may react with CTAB to create a CTA+-AuCl−4 complex. The gold complex is then reacted with ascorbic acid to produce hydrochloric... |
Cetrimonium bromide | Nanoparticle synthesis | Mesoporous materials CTAB is used as the template for the first report of ordered mesoporous materials. Microporous and mesoporous inorganic solids (with pore diameters of ≤20 Å and ~20–500 Å respectively) have found great utility as catalysts and sorption media because of their large internal surface area. Typical mic... |
Cetrimonium bromide | Toxicity | CTAB has been used for applications from nanoparticle synthesis to cosmetics. Due to its use in human products, along with other applications, it is essential to be made aware of the hazards this agent contains. The Santa Cruz Biotechnology, Inc. offers a comprehensive MSDS for CTAB and should be referred to for additi... |
Lithium ion manganese oxide battery | Lithium ion manganese oxide battery | A lithium ion manganese oxide battery (LMO) is a lithium-ion cell that uses manganese dioxide, MnO2, as the cathode material. They function through the same intercalation/de-intercalation mechanism as other commercialized secondary battery technologies, such as LiCoO2. Cathodes based on manganese-oxide components are e... |
Lithium ion manganese oxide battery | Compounds | Spinel LiMn2O4 One of the more studied manganese oxide-based cathodes is LiMn2O4, a cation ordered member of the spinel structural family (space group Fd3m). In addition to containing inexpensive materials, the three-dimensional structure of LiMn2O4 lends itself to high rate capability by providing a well connected fra... |
Lithium ion manganese oxide battery | Compounds | Layered Li2MnO3 Li2MnO3 is a lithium rich layered rocksalt structure that is made of alternating layers of lithium ions and lithium and manganese ions in a 1:2 ratio, similar to the layered structure of LiCoO2. In the nomenclature of layered compounds it can be written Li(Li0.33Mn0.67)O2. Although Li2MnO3 is electroche... |
Lithium ion manganese oxide battery | Compounds | Layered LiMnO2 The layered manganese oxide LiMnO2 is constructed from corrugated layers of manganese/oxide octahedra and is electrochemically unstable. The distortions and deviation from truly planar metal oxide layers are a manifestation of the electronic configuration of the Mn(III) Jahn-Teller ion. A layered variant... |
Lithium ion manganese oxide battery | Compounds | Layered Li2MnO2 The layered manganese oxide Li2MnO2 is structurally related to Li2MnO3 and LiCoO2 with similar transition metal oxide layers separated by a layer containing two lithium cations occupying the available two tetrahedral sites in the lattice rather the one octahedral site. The material is typically made by ... |
Lithium ion manganese oxide battery | Compounds | x Li2MnO3 • y Li1+aMn2-aO4 • z LiMnO2 composites One of the main research efforts in the field of lithium-manganese oxide electrodes for lithium-ion batteries involves developing composite electrodes using structurally integrated layered Li2MnO3, layered LiMnO2, and spinel LiMn2O4, with a chemical formula of x Li2MnO3 ... |
L(R) | L(R) | In set theory, L(R) (pronounced L of R) is the smallest transitive inner model of ZF containing all the ordinals and all the reals. |
L(R) | Construction | It can be constructed in a manner analogous to the construction of L (that is, Gödel's constructible universe), by adding in all the reals at the start, and then iterating the definable powerset operation through all the ordinals. |
L(R) | Assumptions | In general, the study of L(R) assumes a wide array of large cardinal axioms, since without these axioms one cannot show even that L(R) is distinct from L. But given that sufficient large cardinals exist, L(R) does not satisfy the axiom of choice, but rather the axiom of determinacy. However, L(R) will still satisfy the... |
L(R) | Results | Given the assumptions above, some additional results of the theory are: Every projective set of reals – and therefore every analytic set and every Borel set of reals – is an element of L(R).
Every set of reals in L(R) is Lebesgue measurable (in fact, universally measurable) and has the property of Baire and the perfect... |
Viruses of the Mind | Viruses of the Mind | "Viruses of the Mind" is an essay by British evolutionary biologist Richard Dawkins, first published in the book Dennett and His Critics: Demystifying Mind (1993). Dawkins originally wrote the essay in 1991 and delivered it as a Voltaire Lecture on 6 November 1992 at the Conway Hall Humanist Centre. The essay discusses... |
Viruses of the Mind | Content | Dawkins defines the "symptoms" of being infected by the "virus of religion", providing examples for most of them, and tries to define a connection between the elements of religion and its survival value (invoking Zahavi's handicap principle of sexual selection, applied to believers of a religion). Dawkins also describe... |
Viruses of the Mind | Content | Dawkins suggests that religious belief in the "faith-sufferer" typically shows the following elements: It is impelled by some deep, inner conviction that something is true, or right, or virtuous: a conviction that doesn't seem to owe anything to evidence or reason, but which, nevertheless, the believer feels as totally... |
Viruses of the Mind | Content | The internal sensations of the 'faith-sufferer' may be reminiscent of those more ordinarily associated with sexual love.Dawkins stresses his claim that religious beliefs do not spread as a result of evidence in their support, but typically by cultural transmission, in most cases from parents or from charismatic individ... |
Viruses of the Mind | Critical reactions | Alister McGrath, a Christian theologian, has commented critically on Dawkins' analysis, suggesting that "memes have no place in serious scientific reflection", that there is strong evidence that such ideas are not spread by random processes, but by deliberate intentional actions, that "evolution" of ideas is more Lamar... |
Carbyl sulfate | Carbyl sulfate | Carbyl sulfate is an organosulfur compound. The white solid is the product of the reaction of sulfur trioxide and ethylene. It is used in preparation of some dyes and other organosulfur compounds. Carbyl sulfate is a colorless, crystalline, hygroscopic substance although commercial product can appear as a liquid. Becau... |
Carbyl sulfate | Production | Regnault and Heinrich Gustav Magnus reported first in the years 1838 to 1839 on the compound as reaction product of anhydrous ethanol and anhydrous sulfuric acid.
Carbyl sulfate is produced in the highly exothermic (about 800 kcal/kg) reaction of ethylene and sulfur trioxide in the vapor phase in nearly quantitative yi... |
Carbyl sulfate | Production | Disulfuric acid and chlorosulfuric acid can also be used as a sulfonating agent, replacing sulfur trioxide. Instead of ethylene, ethylene-forming agents can be used, e.g. ethanol or diethyl ether.The product of industrial processes is a water-clear liquid which has - in accordance with D.S. Breslow (107.5 to 109 °C) - ... |
Carbyl sulfate | Reactions and use | As a cyclic sulfate ester, it is an alkylating agent. Hydrolysis affords ethionic acid, which retains one sulfate ester group. Ethionic acid undergoes further hydrolysis to isethionic acid: Carbyl sulfate is used as precursor for vinylsulfonic acid and sodium vinyl sulfonate, which are important activated alkenes and a... |
Carbyl sulfate | Safety | The material is highly reactive. It can decompose explosively when heated above 170 °C. |
Wharton's jelly | Wharton's jelly | Wharton's jelly (substantia gelatinea funiculi umbilicalis) is a gelatinous substance within the umbilical cord, largely made up of mucopolysaccharides (hyaluronic acid and chondroitin sulfate). It acts as a mucous connective tissue containing some fibroblasts and macrophages, and is derived from extra-embryonic mesode... |
Wharton's jelly | Umbilical cord occlusion | As a mucous connective tissue, it is rich in proteoglycans, and protects and insulates umbilical blood vessels. Wharton's jelly, when exposed to temperature changes, collapses structures within the umbilical cord and thus provides a physiological clamping of the cord, typically three minutes after birth. |
Wharton's jelly | Stem cells | Cells in Wharton's jelly express several stem cell genes, including telomerase. They can be extracted, cultured, and induced to differentiate into mature cell types such as neurons. Wharton's jelly is therefore a potential source of adult stem cells, often collected from cord blood. Wharton's jelly-derived mesenchymal ... |
Wharton's jelly | Etymology | It is named for the English physician and anatomist Thomas Wharton (1614–1673) who first described it in his publication Adenographia, or "The Description of the Glands of the Entire Body", first published in 1656. |
GPR156 | GPR156 | GPR156 (G protein-coupled receptor 156), is a human gene which encodes a G protein-coupled receptor belonging to metabotropic glutamate receptor subfamily. By sequence homology, this gene was proposed as being a possible GABAB receptor subunit, however when expressed in cells alone or with other GABAB subunits, no resp... |
Bastnäsite | Bastnäsite | The mineral bastnäsite (or bastnaesite) is one of a family of three carbonate-fluoride minerals, which includes bastnäsite-(Ce) with a formula of (Ce, La)CO3F, bastnäsite-(La) with a formula of (La, Ce)CO3F, and bastnäsite-(Y) with a formula of (Y, Ce)CO3F. Some of the bastnäsites contain OH− instead of F− and receive ... |
Bastnäsite | Bastnäsite | Bastnäsite was first described by the Swedish chemist Wilhelm Hisinger in 1838. It is named for the Bastnäs mine near Riddarhyttan, Västmanland, Sweden.
Bastnäsite also occurs as very high-quality specimens at the Zagi Mountains, Pakistan.
Bastnäsite occurs in alkali granite and syenite and in associated pegmatites. It... |
Bastnäsite | Composition | Bastnäsite has cerium, lanthanum and yttrium in its generalized formula but officially the mineral is divided into three minerals based on the predominant rare-earth element. There is bastnäsite-(Ce) with a more accurate formula of (Ce, La)CO3F. There is also bastnäsite-(La) with a formula of (La, Ce)CO3F. And finally ... |
Bastnäsite | Composition | Bastnäsite is closely related to the mineral series parisite. The two are both rare-earth fluorocarbonates, but parisite's formula of Ca(Ce, La, Nd)2(CO3)3F2 contains calcium (and a small amount of neodymium) and a different ratio of constituent ions. Parisite could be viewed as a formula unit of calcite (CaCO3) added ... |
Bastnäsite | Name | Bastnäsite gets its name from its type locality, the Bastnäs Mine, Riddarhyttan, Västmanland, Sweden. Ore from the Bastnäs Mine led to the discovery of several new minerals and chemical elements by Swedish scientists such as Jöns Jakob Berzelius, Wilhelm Hisinger and Carl Gustav Mosander. Among these are the chemical e... |
Bastnäsite | Occurrence | Although a scarce mineral and never in great concentrations, it is one of the more common rare-earth carbonates. Bastnäsite has been found in karst bauxite deposits in Hungary, Greece and the Balkans region. Also found in carbonatites, a rare carbonate igneous intrusive rock, at the Fen Complex, Norway; Bayan Obo, Mong... |
Bastnäsite | Occurrence | The formation of hydroxylbastnasite (NdCO3OH) can also occur via the crystallization of a rare-earth bearing amorphous precursor. With increasing temperature, the habit of NdCO3OH crystals changes progressively to more complex spherulitic or dendritic morphologies. The development of these crystal morphologies has been... |
Bastnäsite | Mining history | In 1949, the huge carbonatite-hosted bastnäsite deposit was discovered at Mountain Pass, San Bernardino County, California. This discovery alerted geologists to the existence of a whole new class of rare earth deposit: the rare earth containing carbonatite. Other examples were soon recognized, particularly in Africa an... |
Bastnäsite | Ore technology | At Mountain Pass, bastnäsite ore was finely ground, and subjected to flotation to separate the bulk of the bastnäsite from the accompanying barite, calcite, and dolomite. Marketable products include each of the major intermediates of the ore dressing process: flotation concentrate, acid-washed flotation concentrate, ca... |
Bastnäsite | Ore technology | Extraction of rare-earth metals Bastnäsite ore is typically used to produce rare-earth metals. The following steps and process flow diagram detail the rare-earth-metal extraction process from the ore.
After extraction, bastnasite ore is typically used in this process, with an average of 7% REO (rare-earth oxides).
The ... |
3DXRD | 3DXRD | Three-dimensional X-ray diffraction (3DXRD) is a microscopy technique using hard X-rays (with energy in the 30-100 keV range) to investigate the internal structure of polycrystalline materials in three dimensions. For a given sample, 3DXRD returns the shape, juxtaposition, and orientation of the crystallites ("grains")... |
3DXRD | 3DXRD | They can be used to investigate larger samples and to employ more complicated sample environments.
They enable to study how 3D grain structures evolve with time.
Since measurements do not alter the sample, different types of analysis can be made in sequence. |
3DXRD | Experimental setup | 3DXRD measurements are performed using various experimental geometries. The classical 3DXRD setup is similar to the conventional tomography setting used at synchrotrons: the sample, mounted on a rotation stage, is illuminated using quasi-parallel monochromatic X-ray beam. Each time a certain grain within the sample sat... |
3DXRD | Experimental setup | At present (April 2017), a 3DXRD microscope is installed at the Materials Science beamline of the ESRF. |
3DXRD | Software | To determine the crystallographic orientation of the grains in the considered sample, the following software packages are in use: Fable and GrainSpotter. Reconstructing the 3D shape of the grains is nontrivial and three approaches are available to do so, respectively based on simple back-projection, forward projection,... |
3DXRD | Applications | With 3DXRD, it is possible to study in situ the time evolution of materials under different conditions. Among others, the technique has been used to map the elastic strains and stresses in a pre-strained nickel-titanium wire. |
3DXRD | Related techniques | The scientists involved in developing 3DXRD contributed to the development of three other three-dimensional non-destructive techniques for the material sciences, respectively using electrons and neutrons as a probe: three-dimensional orientation mapping in the transmission electron microscope (3D-OMiTEM), time-of-fligh... |
SYBL1 | SYBL1 | Vesicle-associated membrane protein 7 (VAMP-7), is a protein that in humans is encoded by the VAMP7 gene also known as the or SYBL1 gene. |
SYBL1 | Function | VAMP-7 is a transmembrane protein that is a member of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family. VAMP-7 localizes to late endosomes and lysosomes and is involved in the fusion of transport vesicles to their target membranes. |
SYBL1 | Interactions | VAMP-7 has been shown to interact with SNAP23 and AP3D1. |
Blood–gas partition coefficient | Blood–gas partition coefficient | Blood–gas partition coefficient, also known as Ostwald coefficient for blood–gas, is a term used in pharmacology to describe the solubility of inhaled general anesthetics in blood. According to Henry's law, the ratio of the concentration in blood to the concentration in gas that is in contact with that blood, when the ... |
Blood–gas partition coefficient | Blood–gas partition coefficient | It is inversely related to induction rate. Induction rate is defined as the speed at which an agent produces anesthesia. The higher the blood:gas partition coefficient, the lower will be the induction rate. |
Blood–gas partition coefficient | Blood–gas partition coefficient | Newer anesthetics (such as desflurane) typically have smaller blood–gas partition coefficients than older ones (such as ether); this leads to faster onset of anesthesia and faster emergence from anesthesia once application of the anesthetic is stopped, which may be preferable in certain clinical scenarios. If an anesth... |
Blood–gas partition coefficient | Blood–gas partition coefficient | The potency of an anesthetic is associated with its lipid solubility, which is measured by its oil/gas partition coefficient.Minimum alveolar concentration (MAC) is defined as the alveolar concentration of anesthetic gas that prevents a movement response in half of subjects undergoing a painful (surgical) stimulus; sim... |
Old Nassau reaction | Old Nassau reaction | The Old Nassau reaction or Halloween reaction is a chemical clock reaction in which a clear solution turns orange and then black. This reaction was discovered by two undergraduate students at Princeton University researching the inhibition of the iodine clock reaction (or Landolt reaction) by Hg2+, resulting in the for... |
Old Nassau reaction | Chemical equation | The reactions involved are as follows: Na2S2O5 + H2O → 2 NaHSO3 IO3− + 3 HSO3− → I− + 3 SO42− + 3 H+ This reaction reduces iodate ions to iodide ions.
Hg2+ + 2 I− → HgI2 Orange mercury iodide solid is precipitated until the mercury is used up.
IO3− + 5 I− + 6 H+ → 3 I2 + 3 H2O The excess I− and IO3− undergo the iodide-... |
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