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Hyperoxia Signs of pulmonary (lung) oxygen toxicity begin with slight irritation in the trachea. A mild cough usually ensues, followed by greater irritation and a worse cough until breathing becomes quite painful and the cough becomes uncontrollable. If supplementation of oxygen is continued, the individual will notice... | https://en.wikipedia.org/wiki?curid=2281441 |
Hyperoxia Breathing nitrox can lead to hyperoxia due to the high partial pressure of oxygen if used too deep or for too long. Protocols for the safe use of raised oxygen partial pressure in diving are well established and used routinely by recreational scuba divers, military combat divers and professional saturation di... | https://en.wikipedia.org/wiki?curid=2281441 |
Closet flange In plumbing, a closet flange (also known as a toilet flange) is a pipe fitting (specifically, a type of flange) that both mounts a toilet to the floor and connects the toilet drain to a drain pipe. The name comes from the term "water closet", the traditional name for a toilet. A typical closet flange is c... | https://en.wikipedia.org/wiki?curid=2282257 |
Endohedral fullerene Endohedral fullerenes, also called endofullerenes, are fullerenes that have additional atoms, ions, or clusters enclosed within their inner spheres. The first lanthanum C complex was synthesized in 1985 and called La@C. The @ (at sign) in the name reflects the notion of a small molecule trapped ins... | https://en.wikipedia.org/wiki?curid=2283222 |
Endohedral fullerene Doping fullerenes with electropositive metals takes place in an arc reactor or via laser evaporation. The metals can be transition metals like scandium, yttrium as well as lanthanides like lanthanum and cerium. Also possible are endohedral complexes with elements of the alkaline earth metals like b... | https://en.wikipedia.org/wiki?curid=2283222 |
Endohedral fullerene In most cases it is between 2 and 3 charge units, in the case of the La@C however it can be even about 6 electrons such as in ScN@C which is better described as [ScN]@[C]. These anionic fullerene cages are very stable molecules and do not have the reactivity associated with ordinary empty fullerene... | https://en.wikipedia.org/wiki?curid=2283222 |
Endohedral fullerene Martin Saunders in 1993 produced endohedral complexes He@C and Ne@C by pressurizing C to ca. 3 bar in a noble-gas atmosphere. Under these conditions about one out of every 650,000 C cages was doped with a helium atom. The formation of endohedral complexes with helium, neon, argon, krypton and xenon... | https://en.wikipedia.org/wiki?curid=2283222 |
Endohedral fullerene Atomic or ion traps are of great interest since particles are present free from (significant) interaction with their environment, allowing unique quantum mechanical phenomena to be explored. For example, the compression of the atomic wave function as a consequence of the packing in the cage could b... | https://en.wikipedia.org/wiki?curid=2283222 |
Endohedral fullerene The following formula, describing the dependence of Δα on n, has been proposed: Δ"α" = "α"(2"e"−1). It describes the DFT-calculated mean polarizabilities of Ng@C endofullerenes with sufficient accuracy. The calculated data allows using C fullerene as a Faraday cage, which isolates the encapsulated ... | https://en.wikipedia.org/wiki?curid=2283222 |
Regenerative medicine is a branch of translational research in tissue engineering and molecular biology which deals with the "process of replacing, engineering or regenerating human or animal cells, tissues or organs to restore or establish normal function". This field holds the promise of engineering damaged tissues a... | https://en.wikipedia.org/wiki?curid=2285007 |
Regenerative medicine One paragraph had "Regenerative Medicine" as a bold print title and stated, "A new branch of medicine will develop that attempts to change the course of chronic disease and in many instances will regenerate tired and failing organ systems." The term was brought into the popular culture in 1999 by ... | https://en.wikipedia.org/wiki?curid=2285007 |
Regenerative medicine Later, Haseltine would go on to explain that regenerative medicine acknowledges the reality that most people, regardless of which illness they have or which treatment they require, simply want to be restored to normal health. Designed to be applied broadly, the original definition includes cell an... | https://en.wikipedia.org/wiki?curid=2285007 |
Regenerative medicine , and other leading researchers founded "E-Biomed: The Journal of Regenerative Medicine". The peer-reviewed journal facilitated discourse around regenerative medicine by publishing innovative research on stem cell therapies, gene therapies, tissue engineering, and biomechanical prosthetics. The So... | https://en.wikipedia.org/wiki?curid=2285007 |
Regenerative medicine In 2009, the SENS Foundation was launched, with its stated aim as "the application of regenerative medicine – defined to include the repair of living cells and extracellular material in situ – to the diseases and disabilities of ageing". In 2012, Professor Paolo Macchiarini and his team improved u... | https://en.wikipedia.org/wiki?curid=2285007 |
Regenerative medicine Widespread interest and funding for research on regenerative medicine has prompted institutions in the United States and around the world to establish departments and research institutes that specialize in regenerative medicine including: The Department of Rehabilitation and Regenerative Medicine ... | https://en.wikipedia.org/wiki?curid=2285007 |
Regenerative medicine Cord blood has been studied as a treatment for diabetes. However, apart from blood disorders, the use of cord blood for other diseases is not a routine clinical modality and remains a major challenge for the stem cell community. Along with cord blood, Wharton's jelly and the cord lining have been ... | https://en.wikipedia.org/wiki?curid=2285007 |
Mixed oxide In chemistry, a mixed oxide is a somewhat informal name for an oxide that contains cations of more than one chemical element or cations of a single element in several states of oxidation. The term is usually applied to solid ionic compounds that contain the oxide anion O and two or more element cations. Typ... | https://en.wikipedia.org/wiki?curid=2285301 |
Mixed oxide minerals are plentiful in nature. Synthetic mixed oxides are components of many ceramics with remarkable properties and important advanced technological applications, such as strong magnets, fine optics, lasers, semiconductors, piezoelectrics, superconductors, catalysts, refractories, gas mantles, nuclear f... | https://en.wikipedia.org/wiki?curid=2285301 |
Lithium nitride is a compound with the formula LiN. It is the only stable alkali metal nitride. The solid is a reddish-pink color and has a high melting point. is prepared by direct combination of elemental lithium with nitrogen gas: Instead of burning lithium metal in an atmosphere of nitrogen, a solution of lithium i... | https://en.wikipedia.org/wiki?curid=2286239 |
Lithium nitride Reacting lithium nitride with carbon dioxide results in amorphous carbon nitride (CN), a semiconductor, and lithium cyanamide (LiCN), a precursor to fertilizers, in an exothermic reaction. | https://en.wikipedia.org/wiki?curid=2286239 |
Superbase A superbase is a compound that has a high affinity for protons. Superbases are valuable in organic chemistry, which abounds in very weak acids. Reactions involving superbases often require special techniques since they're easily destroyed by water, atmospheric carbon dioxide, and, often, oxygen. A common supe... | https://en.wikipedia.org/wiki?curid=2286395 |
Superbase Superbases have been described and used since the 1850s. Organic superbases are almost always charge-neutral, amine-containing species. Despite enormous proton affinity, some organosuperbases exhibit low nucleophilicity. Increasingly important in organic synthesis, these include the phosphazenes, amidines, an... | https://en.wikipedia.org/wiki?curid=2286395 |
Superbase Superbases are used in organocatalysis. The list of the strongest superbases as ranked by their calculated gas phase basicity (proton affinity) is given below. | https://en.wikipedia.org/wiki?curid=2286395 |
Salt bridge A salt bridge, in electrochemistry, is a laboratory device used to connect the oxidation and reduction half-cells of a galvanic cell (voltaic cell), a type of electrochemical cell. It maintains electrical neutrality within the internal circuit, preventing the cell from rapidly running its reaction to equili... | https://en.wikipedia.org/wiki?curid=2286508 |
Salt bridge The other type of salt bridge consists of a filter paper, also soaked with a relatively inert electrolyte, a few common examples of which include potassium nitrate, potassium chloride, and sodium chloride. No gelification agent is required as the filter paper provides a solid medium for conduction. Conducti... | https://en.wikipedia.org/wiki?curid=2286508 |
Gram per litre A gram per litre or gram per liter (g/L or g/l) is a unit of measurement of mass concentration that shows how many grams of a certain substance are present in one litre of a (usually liquid or gaseous) mixture. It is not an SI unit – the SI unit of mass concentration is kilogram per cubic metre, which is... | https://en.wikipedia.org/wiki?curid=2286590 |
Kaonic hydrogen is an exotic atom consisting of a negatively charged kaon orbiting a proton. Such particles were first identified, through their X-ray spectrum, at the KEK proton synchrotron in Tsukuba, Japan in 1997. More detailed studies have been performed at DAFNE in Frascati, Italy. has been created in very low en... | https://en.wikipedia.org/wiki?curid=2286702 |
Negative thermal expansion (NTE) is an unusual physicochemical process in which some materials contract upon heating, rather than expand as most other materials do. The most well-known material with NTE is water at 0~4 °C. Materials which undergo NTE have a range of potential engineering, photonic, electronic, and stru... | https://en.wikipedia.org/wiki?curid=2288927 |
Negative thermal expansion The following sufficient condition for potential giving rise to NTE behavior is proposed for the interatomic potential, formula_1, at the equilibrium distance formula_2: formula_3 Where formula_4 is shorthand for the third derivative of the interatomic potential at the equilibrium point: form... | https://en.wikipedia.org/wiki?curid=2288927 |
Negative thermal expansion 3 to 1050 K (at higher temperatures the material decomposes). Other materials that exhibit this behaviour include: other members of the family of materials (where A = or , M = or ) and and . In contrast to , it has to be noted that and exhibit NTE only in their high temperature phase starting... | https://en.wikipedia.org/wiki?curid=2288927 |
Negative thermal expansion Cubic Scandium trifluoride has this property which is explained by the quartic oscillation of the fluoride ions. The energy stored in the bending strain of the fluoride ion is proportional to the fourth power of the displacement angle, unlike most other materials where it is proportional to t... | https://en.wikipedia.org/wiki?curid=2288927 |
Negative thermal expansion for application in precision instruments. But also in everyday life materials with a CTE close to zero are required. Glass-ceramic cooktops like Ceran cooktops need to withstand large temperature gradients and rapid changes in temperature while cooking because only certain parts of the cookto... | https://en.wikipedia.org/wiki?curid=2288927 |
Hexol is the name for various salts of a coordination complex that has historical significance. The salts were the first synthetic non-carbon-containing chiral compounds. The sulfate salt has the formula {[Co(NH)(OH)]Co}(SO). Salts of hexol were first described by Jørgensen. The salt is prepared by heating [Co(NH)(HO)]... | https://en.wikipedia.org/wiki?curid=2289119 |
Zirconia light A zirconia light is an intensely brilliant chemical light produced by incandescent zirconia. It is similar in design to the Drummond light (limelight), but uses a block of zirconia instead of quicklime. Both have been replaced by the electric light. page 81 THE NEW ZIRCONIA-LIGHT. Three or four months ag... | https://en.wikipedia.org/wiki?curid=2289250 |
Zirconia light Quite recently one of the first zirconia lamps procurable for examination in this country reached London, and was sent by Mr. R. J. Fowler, the Parisian correspondent of the 'British Journal of Photography,' to Mr. John Traill Taylor, the editor of that journal, with the request that he and Mr. W. H. Har... | https://en.wikipedia.org/wiki?curid=2289250 |
Zirconia light The experimentalists then cut down a piece of lime till it equalled the zirconia in size, and the lime and zirconia were exposed in turn to the flame, the result being that the zirconia was found to emit a less white brilliant light than the lime under the same conditions, nor did variations in distance ... | https://en.wikipedia.org/wiki?curid=2289250 |
Zirconia light A few other experiments were tried, showing that soft lime and hard lime have to be placed at different distances from the blowpipe nozzle to get the maximum amount of light from each. Chemical composition, even more than hardness, varies the amount of whiteness of the light. Magnesia cylinders were foun... | https://en.wikipedia.org/wiki?curid=2289250 |
Electrodialysis reversal (EDR) is an electrodialysis reversal water desalination membrane process that has been commercially used since the early 1960s. An electric current migrates dissolved salt ions, including fluorides, nitrates and sulfates, through an electrodialysis stack consisting of alternating layers of cati... | https://en.wikipedia.org/wiki?curid=2289312 |
Frémy's salt is a chemical compound with the formula (K[ON(SO)]), sometimes written as (K[NO(SO)]). It a bright yellowish-brown solid, but its aqueous solutions are bright violet. The related sodium salt, i.e. disodium nitrosodisulfonate (NDS, NaON(SO), CAS RN 29554-37-8) is also referred to as Frémy's salt. Regardless... | https://en.wikipedia.org/wiki?curid=2289914 |
Ghost net Ghost nets are fishing nets that have been left or lost in the ocean by fishermen. These nets, often nearly invisible in the dim light, can be left tangled on a rocky reef or drifting in the open sea. They can entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatu... | https://en.wikipedia.org/wiki?curid=2290281 |
Ghost net Even balled-up fishing line can be deadly for a variety of creatures, including birds and marine mammals. Over time the nets become more and more tangled. In general, fish are less likely to be trapped in gear that has been down a long time. Fishermen sometimes abandon worn-out nets because it is often the ea... | https://en.wikipedia.org/wiki?curid=2290281 |
Ghost net In May 2016, the Australian Fisheries Management Authority (AFMA) recovered 10 tonnes of abandoned nets within the Australian Exclusive Economic Zone and Torres Strait protected zone perimeters. One protected turtle was rescued. Unlike synthetic fishing nets, biodegradable fishing nets decompose naturally und... | https://en.wikipedia.org/wiki?curid=2290281 |
Ghost net Net amnesty schemes such as Fishing for Litter incentivise the collection and responsible disposal of end of life fishing gear. These schemes address the root cause for many net abandonments which is the financial cost of their disposal. Fishing nets are often made from extremely high quality plastics to ensu... | https://en.wikipedia.org/wiki?curid=2290281 |
Luminophore A luminophore is an atom or functional group in a chemical compound that is responsible for its luminescent properties. Luminophores can be either organic or inorganic. Luminophores can be further classified as fluorophores or phosphors, depending on the nature of the excited state responsible for the emiss... | https://en.wikipedia.org/wiki?curid=2290742 |
Prochirality In stereochemistry, prochiral molecules are those that can be converted from achiral to chiral in a single step. An achiral species which can be converted to a chiral in two steps is called proproprochiral. If two identical substituents are attached to a sp-hybridized atom, the descriptors "pro"-R and "pro... | https://en.wikipedia.org/wiki?curid=2291162 |
Iodometry Iodometry, known as iodometric titration, is a method of volumetric chemical analysis, a redox titration where the appearance or disappearance of elementary iodine indicates the end point. Note that iodometry involves indirect titration of iodine liberated by reaction with the analyte, whereas iodimetry invol... | https://en.wikipedia.org/wiki?curid=2292030 |
Iodometry The triiodide ion solution is then titrated against standard thiosulfate solution to give iodide again using starch indicator: Together with reduction potential of thiosulfate: The overall reaction is thus: For simplicity, the equations will usually be written in terms of aqueous molecular iodine rather than ... | https://en.wikipedia.org/wiki?curid=2292030 |
Iodometry For prolonged titrations, it is advised to add dry ice to the titration mixture to displace air from the erlenmeyer flask so as to prevent the aerial oxidation of iodide to iodine. Standard iodine solution is prepared from potassium iodate and potassium iodide, which are both primary standards): Iodine in org... | https://en.wikipedia.org/wiki?curid=2292030 |
Iodometry Thus when a diluted but excess amount of standard iodine solution is added to known volume of sample, the sulfurous acid and sulfites present reduces iodine quantitatively: Although the sulfide content in sample can be determined straight forwardly as described for sulfites, the results are often poor and ina... | https://en.wikipedia.org/wiki?curid=2292030 |
Iodometry To drive the reaction to completion, an excess amount of zinc salt can be added to the reaction mixture containing potassium ions, which precipitates the hexacyanoferrate(II) ion quantitatively: The precipitation occurs in slightly acidic medium, thus avoids the problem of decomposition of iodide and thiosulf... | https://en.wikipedia.org/wiki?curid=2292030 |
Docking (molecular) In the field of molecular modeling, docking is a method which predicts the preferred orientation of one molecule to a second when bound to each other to form a stable complex. Knowledge of the preferred orientation in turn may be used to predict the strength of association or binding affinity betwee... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) Molecular docking may be defined as an optimization problem, which would describe the “best-fit” orientation of a ligand that binds to a particular protein of interest. However, since both the ligand and the protein are flexible, a "“hand-in-glove”" analogy is more appropriate than "“lock-and-key”".... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) In this case, the receptor's molecular surface is described in terms of its solvent-accessible surface area and the ligand's molecular surface is described in terms of its matching surface description. The complementarity between the two surfaces amounts to the shape matching description that may he... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) The moves incorporate rigid body transformations such as translations and rotations, as well as internal changes to the ligand's structure including torsion angle rotations. Each of these moves in the conformation space of the ligand induces a total energetic cost of the system. Hence, the system's ... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) However, in practice with current computational resources, it is impossible to exhaustively explore the search space—this would involve enumerating all possible distortions of each molecule (molecules are dynamic and exist in an ensemble of conformational states) and all possible rotational and tran... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) Computational capacity has increased dramatically over the last decade making possible the use of more sophisticated and computationally intensive methods in computer-assisted drug design. However, dealing with receptor flexibility in docking methodologies is still a thorny issue. The main reason be... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) The various contributions to binding can be written as an additive equation: formula_1 The components consist of solvent effects, conformational changes in the protein and ligand, free energy due to protein-ligand interactions, internal rotations, association energy of ligand and receptor to form a ... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) The interdependence between sampling and scoring function affects the docking capability in predicting plausible poses or binding affinities for novel compounds. Thus, an assessment of a docking protocol is generally required (when experimental data is available) to determine its predictive capabili... | https://en.wikipedia.org/wiki?curid=2292623 |
Docking (molecular) For small molecules, several benchmark data sets for docking and virtual screening exist e.g. "Astex Diverse Set" consisting of high quality protein−ligand X-ray crystal structures or the "Directory of Useful Decoys" (DUD) for evaluation of virtual screening performance. An evaluation of docking pro... | https://en.wikipedia.org/wiki?curid=2292623 |
Lime sulfur In horticulture, lime sulfur (British spelling lime sulphur) is mainly a mixture of calcium polysulfides and thiosulfate (plus other reaction by-products as sulfite and sulfate) formed by reacting calcium hydroxide with elemental sulfur, used in pest control. It can be prepared by boiling in water a suspens... | https://en.wikipedia.org/wiki?curid=2293159 |
Lime sulfur The inverse comproportionation reaction is the reaction occurring in the Claus process used for desulfurisation of oil and gas crude products in the refining industry. Claus process: By rewriting the last reaction in the inverse direction one obtains a reaction consistent with what is observed in the lime s... | https://en.wikipedia.org/wiki?curid=2293159 |
Lime sulfur The presence of thiosulfate in the lime sulfur reaction can be accounted by the reaction between sulfite and elemental sulfur (or with sulfide and polysulfides) and that of sulfate by the complete oxidation of sulfite or thiosulfate following a more complex reaction scheme. More information on calcium thios... | https://en.wikipedia.org/wiki?curid=2293159 |
Lime sulfur Boil for an hour, stirring and adding small amounts of hot water to compensate for evaporation. is sold as a spray for deciduous trees to control fungi, bacteria and insects living or dormant on the surface of the bark. burns leaves and so cannot be sprayed on evergreen plants or on plants still bearing gre... | https://en.wikipedia.org/wiki?curid=2293159 |
Lime sulfur reacts with strong acids (including stomach acid) to produce highly toxic hydrogen sulfide (rotten egg gas) and indeed usually has a distinct "rotten egg" odor to it. is not extremely flammable but combustion produces highly irritating sulfur dioxide gas. Safety goggles and impervious gloves must be worn wh... | https://en.wikipedia.org/wiki?curid=2293159 |
Petrochemical industry The petrochemical industry is concerned with the production and trade of petrochemicals. It directly interfaces with the petroleum industry, especially the downstream sector. A major part is constituted by the plastics (polymer) industry. The top ten global petrochemical companies based on the 20... | https://en.wikipedia.org/wiki?curid=2293201 |
Emil Kopp Charles-Émile Kopp (3 March 1817 – 30 November 1875), French chemist, was born at Wasselonne, Alsace. He became in 1847 a professor of toxicology and chemistry at the École supérieure de Pharmacie at Strasbourg. Because of his participation in the demonstration on "revolutionary day" 13 June 1849, he was forc... | https://en.wikipedia.org/wiki?curid=2293614 |
Tungsten(III) oxide (WO) is a compound of tungsten and oxygen. It has been reported (2006) as being grown as a thin film by atomic layer deposition at temperatures between 140 and 240 °C using W(N(CH)) as a precursor. It is not referred to in major textbooks. Some older literature refers to the compound WO but as the a... | https://en.wikipedia.org/wiki?curid=2295496 |
Rietveld refinement is a technique described by Hugo Rietveld for use in the characterisation of crystalline materials. The neutron and x-ray diffraction of powder samples results in a pattern characterised by reflections (peaks in intensity) at certain positions. The height, width and position of these reflections can... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement It employs the non-linear least squares method, and requires the reasonable initial approximation of many free parameters, including peak shape, unit cell dimensions and coordinates of all atoms in the crystal structure. Other parameters can be guessed while still being reasonably refined. In this w... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement Before exploring Rietveld refinement, it is necessary to establish a greater understanding of powder diffraction data and what information is encoded therein in order to establish a notion of how to create a model of a diffraction pattern, which is of course necessary in Rietveld refinement. A typic... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement Third, peak intensities determine space group symmetry and atomic coordination. Finally, the model is used to refine all crystallographic and peak shape function parameters. To do this successfully, there is a requirement for excellent data which means good resolution, low background, and a large an... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement As such, average crystallite size, τ, and microstrain, ε, effects on Bragg peak broadening, β (in radians), can be described as follows, where k is a constant: formula_4 and formula_5 Returning to the peak shape function, the goal is to correctly model the Bragg peaks which exist in the observed pow... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement The pseudo-Voigt function can be represented as: formula_19 Where formula_20 and formula_21 are the Gaussian and Lorentzian contributions, respectively. Thus, formula_22. Where: The pseudo-Voigt function, like the Gaussian and Lorentz functions, is a centrosymmetric function, and as such does not mo... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement If this distribution is assumed then the contribution of a given reflection to the profile y at position 2"θ" is: formula_41 where "H" is the full width at half peak height (full-width half-maximum), 2"θ" is the centre of the reflex, and I is the calculated intensity of the reflex (determined from t... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement In powder samples there is a tendency for plate- or rod-like crystallites to align themselves along the axis of a cylindrical sample holder. In solid polycrystalline samples the production of the material may result in greater volume fraction of certain crystal orientations (commonly referred to as ... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement The latter occurs when correlated parameters are being refined at the same time, which may result in divergence and instability of the minimization. This iterative nature also means that convergence to a solution does not occur immediately for the method is not exact. Each iteration depends on the r... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement Considering the peak shape functions and accounting for the overlapping of Bragg peaks because of the one-dimensionality of XRD data, the expanded form of the above equation for the case of a single phase measured with a single wavelength becomes: formula_70 Where, For a material that contains sever... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement It is advantageous to use single phase materials when interested in finding precise structural parameters of a material. However, since the scale factors of each phase are determined independently, of multi phase materials can quantitatively examine the mixing ratio of each phase in the material. Ge... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement It is worth noting that it is rarely possible to refine all relevant variables simultaneously from the beginning of a refinement, nor near the end since the least squares fitting will be destabilized or lead to a false minimum. It is important for the user to determine a stopping point for a given r... | https://en.wikipedia.org/wiki?curid=2296085 |
Rietveld refinement The most popular and conventional figure of merit used is the goodness of fit which should approach unity given a perfect fit, though this is rarely the case. In practice, the best way to assess quality is a visual analysis of the fit by plotting the difference between the observed and calculated da... | https://en.wikipedia.org/wiki?curid=2296085 |
Reactive distillation is a process where the chemical reactor is also the still. Separation of the product from the reaction mixture does not need a separate distillation step which saves energy (for heating) and materials. This technique can be useful for equilibrium-limited reactions such as esterification and ester ... | https://en.wikipedia.org/wiki?curid=2296175 |
Reactive distillation Hence, in a typical reactive distillation column that consists of both reactive and non-reactive zones, the heterogeneous azeotrope or a composition close to the azeotrope can be obtained as the distillate product. Moreover, the aqueous phase that forms after the condensation of the vapor is almos... | https://en.wikipedia.org/wiki?curid=2296175 |
Organic peroxide Organic peroxides are organic compounds containing the peroxide functional group (ROOR′). If the R′ is hydrogen, the compounds are called organic hydroperoxides. Peresters have general structure RC(O)OOR. The O−O bond easily breaks, producing free radicals of the form RO (the dot represents an unpaired... | https://en.wikipedia.org/wiki?curid=2296644 |
Organic peroxide The biosynthesis prostaglandins proceeds via an endoperoxide, a class of bicyclic peroxides. In firefly, oxidation of luciferins, which is catalyzed by luciferases, yields a peroxy compound 1,2-dioxetane. The dioxetane is unstable and decays spontaneously to carbon dioxide and excited ketones, which re... | https://en.wikipedia.org/wiki?curid=2296644 |
Organic peroxide In this method, the alkyl sulfate donates the alkyl group and the sulfate ion forms the leaving group: This method can also yield cyclic peroxides. The four-membered dioxetanes can be obtained by 2+2 cycloaddition of oxygen to alkenes. Organoperoxides can be reduced to alcohols with lithium aluminium h... | https://en.wikipedia.org/wiki?curid=2296644 |
Organic peroxide For example, the loss of blue color in leuco-methylene blue is selective for hydrogen peroxide. Quantitative analysis of hydroperoxides can be performed using potentiometric titration with lithium aluminium hydride. Another way to evaluate the content of peracids and peroxides is the volumetric titrati... | https://en.wikipedia.org/wiki?curid=2296644 |
Organic peroxide Commercial formulations occasionally consist of mixtures of organic peroxides, which may or may not be phlegmatized. Organic peroxides are useful in chemical synthesis due to their propensity to decompose. In doing so they generate useful radicals that can initiate polymerization to create polymers, mo... | https://en.wikipedia.org/wiki?curid=2296644 |
Organic peroxide For safety reasons, peroxidic compounds are stored in a cool, opaque container, as heating and illumination accelerate their chemical reactions. Small amounts of peroxides, which emerge from storage or reaction vessels are neutralized using reducing agents such as iron(II) sulfate. Safety measures in i... | https://en.wikipedia.org/wiki?curid=2296644 |
Chemical oxygen generator A chemical oxygen generator is a device that releases oxygen via a chemical reaction. The oxygen source is usually an inorganic superoxide, chlorate, or perchlorate; ozonides are a promising group of oxygen sources. The generators are usually ignited by a firing pin, and the chemical reaction ... | https://en.wikipedia.org/wiki?curid=2297168 |
Chemical oxygen generator The explosives in the percussion cap are a lead styphnate and tetrazene explosive mixture. The chemical reaction is exothermic and the exterior temperature of the canister will reach . It will produce oxygen for 12 to 22 minutes. The two-mask generator is approximately in diameter and long. Th... | https://en.wikipedia.org/wiki?curid=2297168 |
Chemical oxygen generator The key reaction is: Potassium and lithium chlorate, and sodium, potassium and lithium perchlorates can also be used in oxygen candles. An explosion caused by one of these candles killed two Royal Navy sailors on , a nuclear-powered submarine, under the Arctic on 21 March 2007. The candle had ... | https://en.wikipedia.org/wiki?curid=2297168 |
Decarburization (or decarbonization) is the process opposite to carburization, namely the reduction of carbon content. The term is typically used in metallurgy, describing the reduction of the content of carbon in metals (usually steel). occurs when the metal is heated to temperatures of 700 °C or above when carbon in ... | https://en.wikipedia.org/wiki?curid=2299119 |
Decarburization To prevent the atmospheric gases from reacting with the metal itself, electrical steel is annealed in an atmosphere of nitrogen, hydrogen, and water vapor, where oxidation of the iron is specifically prevented by the proportions of hydrogen and water vapor so that the only reacting substance is carbon b... | https://en.wikipedia.org/wiki?curid=2299119 |
Steinhart–Hart equation The is a model of the resistance of a semiconductor at different temperatures. The equation is where The equation is often used to derive a precise temperature of a thermistor, since it provides a closer approximation to actual temperature than simpler equations, and is useful over the entire wo... | https://en.wikipedia.org/wiki?curid=2299504 |
Steinhart–Hart equation Hart, a Senior Scientist at Woods Hole Oceanographic Institution since 1989 and fellow of the Geological Society of America, the American Geophysical Union, the Geochemical Society and the European Association of Geochemistry, was associated with Professor Steinhart at the Carnegie Institution o... | https://en.wikipedia.org/wiki?curid=2299504 |
Cobalt glass Cobalt glass—known as "smalt" when ground as a pigment—is a deep blue coloured glass prepared by including a cobalt compound, typically cobalt oxide or cobalt carbonate, in a glass melt. Cobalt is a very intense colouring agent and very little is required to show a noticeable amount of colour. plates are u... | https://en.wikipedia.org/wiki?curid=2299975 |
Cobalt glass In paintings, smalt has a tendency to lose its color over a long period, and is little used today. However, when used in ceramics for underglaze decoration, it keeps its colour well, and is the main blue used in blue and white pottery from a wide range of dates and areas, including Chinese blue and white p... | https://en.wikipedia.org/wiki?curid=2299975 |
Cobalt glass The process used for producing cobalt smalt glass at the Blaafarveværket industrial manufacturing center in Norway in the 19th century has been documented as smelting cobalt oxide together with quartz and potassium carbonate. The result was an intensely blue glass-like substance that was ground and sold to... | https://en.wikipedia.org/wiki?curid=2299975 |
Potassium peroxymonosulfate (also known as MPS, potassium monopersulfate, potassium caroate, the trade names Caroat and Oxone, and as non-chlorine shock in the pool and spa industry) is widely used as an oxidizing agent. It is the potassium salt of peroxymonosulfuric acid. The triple salt 2KHSO·KHSO·KSO (known by the t... | https://en.wikipedia.org/wiki?curid=2301644 |
Potassium peroxymonosulfate In particular, if the starting ketone is chiral then the epoxide may be generated enantioselectively, which forms the basis of the Shi epoxidation. can be used in swimming pools to keep the water clear, thus allowing chlorine in pools to work to sanitize the water rather than clarify the wat... | https://en.wikipedia.org/wiki?curid=2301644 |
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