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Blue MX-R or Reactive Blue 4 has a formula of CHClNOS and a molecular weight of 637.4 g/mol. It contains dichlorotriazine ring to the chromophore unlike Cibacron Blue F3GA. For a large scale protein purification, Blue MX-R can be used to purify protein such as lactate dehydrogenase (LDH). In fast-protein liquid chromatography (FPLC) using Blue MX-R immobilized on poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads, it was seen to separate lysozyme and bovine serum albumin (BSA), purified lysozyme from chicken albumin.
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Theoretical and Fundamental Chemistry
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In addition to his joint recognition for the discovery of oxygen, Scheele is argued to have been the first to discover other chemical elements such as barium (1772), manganese (1774), molybdenum (1778), and tungsten (1781), as well as several chemical compounds, including citric acid, lactic acid, glycerol, hydrogen cyanide (also known, in aqueous solution, as prussic acid), hydrogen fluoride, and hydrogen sulfide (1777). In addition, he discovered a process similar to pasteurization, along with a means of mass-producing phosphorus (1769), leading Sweden to become one of the world's leading producers of matches.
Scheele made one other very important scientific discovery in 1774, arguably more revolutionary than his isolation of oxygen. He identified lime, silica, and iron in a specimen of pyrolusite (impure manganese dioxide) given to him by his friend, Johann Gottlieb Gahn, but could not identify an additional component (this was the manganese, which Scheele recognized was present as a new element, but could not isolate). When he treated the pyrolusite with hydrochloric acid over a warm sand bath, a yellow-green gas with a strong odor was produced. He found that the gas sank to the bottom of an open bottle and was denser than ordinary air. He also noted that the gas was not soluble in water. It turned corks a yellow color and removed all color from wet, blue litmus paper and some flowers. He called this gas with bleaching abilities, "dephlogisticated muriatic acid" (dephlogisticated hydrochloric acid, or oxidized hydrochloric acid). Eventually, Sir Humphry Davy named the gas chlorine, with reference to its pale green colour.
Chlorine's bleaching properties were eventually turned into an industry by Berzelius, and became the foundation of a second industry of disinfection and deodorization of putrefied tissue and wounds (including wounds in living humans) in the hands of Labarraque, by 1824.
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Applied and Interdisciplinary Chemistry
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TSE or Tris/Saline/EDTA, is a buffer solution containing a mixture of Tris base, Sodium chloride and EDTA.
In molecular biology, TSE buffers are often used in procedures involving nucleic acids. Tris-acid solutions are effective buffers for slightly basic conditions, which keep DNA deprotonated and soluble in water. The concentration of tris in the solution is kept near 25 mM. EDTA is a chelator of divalent cations, particularly of magnesium (Mg). As these ions are necessary co-factors for many enzymes, including contaminant nucleases, the role of the EDTA is to protect the nucleic acids against enzymatic degradation. But since Mg is also a co-factor for many useful DNA-modifying enzymes such as restriction enzymes and DNA polymerases, its concentration in TSE buffers is generally kept low (typically at around 2.5 mM). The sodium chloride is generally kept at a concentration of 0.05 M.
| 1 |
Applied and Interdisciplinary Chemistry
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In polymers, such as plastics, thermal degradation refers to a type of polymer degradation where damaging chemical changes take place at elevated temperatures, without the simultaneous involvement of other compounds such as oxygen. Simply put, even in the absence of air, polymers will begin to degrade if heated high enough. It is distinct from thermal-oxidation, which can usually take place at less elevated temperatures.
The onset of thermal degradation dictates the maximum temperature at which a polymer can be used. It is an important limitation in how the polymer is manufactured and processed. For instance, polymers become less viscous at higher temperatures which makes injection moulding easier and faster, but thermal degradation places a ceiling temperature on this. Polymer devolatilization is similarly effected.
At high temperatures, the components of the long chain backbone of the polymer can break (chain scission) and react with one another (cross-link) to change the properties of the polymer. These reactions result in changes to the molecular weight (and molecular weight distribution) of the polymer and can affect its properties by causing reduced ductility and increased embrittlement, chalking, scorch, colour changes, cracking and general reduction in most other desirable physical properties.
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Theoretical and Fundamental Chemistry
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In bionanotechnology, intrinsic properties of the clusters (for example, fluorescence) can be made available for bionanotechnological applications by linking them with biomolecules through the process of bioconjugation. The protected gold particles' stability and fluorescence makes them efficient emitters of electromagnetic radiation that can be tuned by varying the cluster size and the type of ligand used for protection. The protective shell can function (have functional groups added) in a way that selective binding (for example, as a complementary protein receptor of DNA-DNA-interaction) qualifies them for the use as biosensors.
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Theoretical and Fundamental Chemistry
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*[[9-Borabicyclo(3.3.1)nonane|9-Borabicyclo[3.3.1]nonane]] (9-BBN).
* Thexylborane ((1,1,2-trimethylpropyl)borane, ThxBH), a primary borane obtained by hydroboration of tetramethylethylene.
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Theoretical and Fundamental Chemistry
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Protide, deuteride and tritide are used to describe ions or compounds that contain enriched hydrogen-1, deuterium or tritium, respectively.
In the classic meaning, hydride refers to any compound hydrogen forms with other elements, ranging over groups 1–16 (the binary compounds of hydrogen). The following is a list of the nomenclature for the hydride derivatives of main group compounds according to this definition:
*alkali and alkaline earth metals: metal hydride
*boron: borane, BH
*aluminium: alumane, AlH
*gallium: gallane, GaH
*indium: indigane, InH
*thallium: thallane, TlH
*carbon: alkanes, alkenes, alkynes, and all hydrocarbons
*silicon: silane
*germanium: germane
*tin: stannane
*lead: plumbane
*nitrogen: ammonia ("azane" when substituted), hydrazine
*phosphorus: phosphine (note "phosphane" is the IUPAC recommended name)
*arsenic: arsine (note "arsane" is the IUPAC recommended name)
*antimony: stibine (note "stibane" is the IUPAC recommended name)
*bismuth: bismuthine (note "bismuthane" is the IUPAC recommended name)
*helium: helium hydride (only exists as an ion)
According to the convention above, the following are "hydrogen compounds" and not "hydrides":
*oxygen: water ("oxidane" when substituted; synonym: hydrogen oxide), hydrogen peroxide
*sulfur: hydrogen sulfide ("sulfane" when substituted)
*selenium: hydrogen selenide ("selane" when substituted)
*tellurium: hydrogen telluride ("tellane" when substituted)
*polonium: hydrogen polonide ("polane" when substituted)
*halogens: hydrogen halides
Examples:
*nickel hydride: used in NiMH batteries
*palladium hydride: electrodes in cold fusion experiments
*lithium aluminium hydride: a powerful reducing agent used in organic chemistry
*sodium borohydride: selective specialty reducing agent, hydrogen storage in fuel cells
*sodium hydride: a powerful base used in organic chemistry
*diborane: reducing agent, rocket fuel, semiconductor dopant, catalyst, used in organic synthesis; also borane, pentaborane and decaborane
*arsine: used for doping semiconductors
*stibine: used in semiconductor industry
*phosphine: used for fumigation
*silane: many industrial uses, e.g. manufacture of composite materials and water repellents
*ammonia: coolant, fuel, fertilizer, many other industrial uses
*hydrogen sulfide: component of natural gas, important source of sulfur
*Chemically, even water and hydrocarbons could be considered hydrides.
All metalloid hydrides are highly flammable. All solid non-metallic hydrides except ice are highly flammable. But when hydrogen combines with halogens it produces acids rather than hydrides, and they are not flammable.
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Theoretical and Fundamental Chemistry
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In a cylindrical vessel stirred by a central rotating paddle, turbine or propeller, the characteristic dimension is the diameter of the agitator . The velocity is where is the rotational speed in rad per second. Then the Reynolds number is:
The system is fully turbulent for values of above .
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Applied and Interdisciplinary Chemistry
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From the beginning, the cyclol reaction was considered as a covalent analog of the hydrogen bond. Therefore, it was natural to consider hybrid models with both types of bonds. This was the subject of Wrinch's fourth paper on the cyclol model (1936), written together with Dorothy Jordan Lloyd, who first proposed that globular proteins are stabilized by hydrogen bonds. A follow-up paper was written in 1937 that referenced other researchers on hydrogen bonding in proteins, such as Maurice Loyal Huggins and Linus Pauling.
Wrinch also wrote a paper with William Astbury, noting the possibility of a keto-enol isomerization of the >CH and an amide carbonyl group >C=O, producing a crosslink >C-C(OH)< and again converting the oxygen to a hydroxyl group. Such reactions could yield five-membered rings, whereas the classic cyclol hypothesis produces six-membered rings. This keto-enol crosslink hypothesis was not developed much further.
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Applied and Interdisciplinary Chemistry
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In the spinodal region of the phase diagram, the free energy can be lowered by allowing the components to separate, thus increasing the relative concentration of a component material in a particular region of the material. The concentration will continue to increase until the material reaches the stable part of the phase diagram. Very large regions of material will change their concentration slowly due to the amount of material that must be moved. Very small regions will shrink away due to the energy cost of maintaining an interface between two dissimilar component materials.
To initiate a homogeneous quench a control parameter, such as temperature, is abruptly and globally changed. For a binary mixture of -type and -type materials, the Landau free-energy
is a good approximation of the free energy near the critical point and is often used to study homogeneous quenches. The mixture concentration is the density difference of the mixture components, the control parameters which determine the stability of the mixture are and , and the interfacial energy cost is determined by .
Diffusive motion often dominates at the length-scale of spinodal decomposition. The equation of motion for a diffusive system is
where is the diffusive mobility, is some random noise such that , and the chemical potential is derived from the Landau free-energy:
We see that if , small fluctuations around have a negative effective diffusive mobility and will grow rather than shrink. To understand the growth dynamics, we disregard the fluctuating currents due to , linearize the equation of motion around and perform a Fourier transform into -space. This leads to
which has an exponential growth solution:
Since the growth rate is exponential, the fastest growing angular wavenumber
will quickly dominate the morphology. We now see that spinodal decomposition results in domains of the characteristic length scale called the spinodal length:
The growth rate of the fastest-growing angular wave number is
where is known as the spinodal time.
The spinodal length and spinodal time can be used to nondimensionalize the equation of motion, resulting in universal scaling for spinodal decomposition.
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Theoretical and Fundamental Chemistry
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In chemistry, fine chemicals are complex, single, pure chemical substances, produced in limited quantities in multipurpose plants by multistep batch chemical or biotechnological processes. They are described by exacting specifications, used for further processing within the chemical industry and sold for more than $10/kg (see the comparison of fine chemicals, commodities and specialties). The class of fine chemicals is subdivided either on the basis of the added value (building blocks, advanced intermediates or active ingredients), or the type of business transaction, namely standard or exclusive products.
Fine chemicals are produced in limited volumes (< 1000 tons/year) and at relatively high prices (> $10/kg) according to exacting specifications, mainly by traditional organic synthesis in multipurpose chemical plants. Biotechnical processes are gaining ground. Fine chemicals are used as starting materials for specialty chemicals, particularly pharmaceuticals, biopharmaceuticals and agrochemicals. Custom manufacturing for the life science industry plays a big role; however, a significant portion of the fine chemicals total production volume is manufactured in-house by large users. The industry is fragmented and extends from small, privately owned companies to divisions of big, diversified chemical enterprises. The term "fine chemicals" is used in distinction to "heavy chemicals", which are produced and handled in large lots and are often in a crude state.
Since the late 1970s, fine chemicals have become an important part of the chemical industry. Their global total production value of $85 billion is split about 60-40 between in-house production in the life-science industry—the products' main consumers—and companies producing them for sale. The latter pursue both a "supply push" strategy, whereby standard products are developed in-house and offered ubiquitously, and a "demand pull" strategy, whereby products or services determined by the customer are provided exclusively on a "one customer / one supplier" basis. The products are mainly used as building blocks for proprietary products. The hardware of the top tier fine chemical companies has become almost identical. The design, lay-out and equipment of the plants and laboratories have become practically the same globally. Most chemical reactions performed go back to the days of the dyestuff industry. Numerous regulations determine the way labs and plants must be operated, thereby contributing to the uniformity.
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Theoretical and Fundamental Chemistry
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An optical delay-line is implemented using a movable stage to vary the path length of one of the two beam paths. A delay stage uses a moving retroreflector to redirect the beam along a well-defined output path but following a delay. Movement of the stage holding the retroreflector corresponds to an adjustment of path length and consequently the time at which the terahertz detector is gated relative to the source terahertz pulse.
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Theoretical and Fundamental Chemistry
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Addition of an allylsilane to an aldehyde is used in an efficient synthesis of tagetol.
Iminium ions generated in situ may be trapped by intramolecular allysilanes. The cyclization below has been used in syntheses of isoretronecanol and epilupinine.
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Theoretical and Fundamental Chemistry
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It has been discovered that this protein has a catalytic activity, in other words, it has the ability to increase the speed of chemical reactions which would not occur so fast. It is known to catalysis the following reaction (which requires the following cofactor: Mg(2+)):
ATP + RNA(n) ⇄ diphosphate + RNA(n+1)
Depending on the surroundings the optimal pH varies from 8 in the cytoplasm to 8.3 in the nucleus.
| 1 |
Applied and Interdisciplinary Chemistry
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From the 1920s to the 1950s, there were a number of authors who discussed the concept of rate-limiting steps, also known as master reactions. Several authors have stated that the concept of the rate-limiting step is incorrect. Burton (1936) was one of the first to point out that: "In the steady state of reaction chains, the principle of the master reaction has no application". Hearon (1952) made a more general mathematical analysis and developed strict rules for the prediction of mastery in a linear sequence of enzyme-catalysed reactions. Webb (1963) was highly critical of the concept of the rate-limiting step and of its blind application to solving problems of regulation in metabolism. Waley (1964) made a simple but illuminating analysis of simple linear chains. He showed that provided the intermediate concentrations were low compared to the values of the enzymes, the following expression was valid:
where equals the pathway flux, and and are functions of the rate constants and intermediate metabolite concentrations. The terms are proportional to the limiting rate values of the enzymes. The first point to note from the above equation is that the pathway flux is a function of all the enzymes; there is no need for there to be a rate-limiting step. If, however, all the terms from to , are small relative to then the first enzyme will contribute the most to determining the flux and therefore, could be termed the rate-limiting step.
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Applied and Interdisciplinary Chemistry
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Cytoplasmic transfer was originally developed in the 1980s in the course of basic research conducted with mice to study the role that parts of the cell outside of the nucleus played in embryonic development. In this technique, cytoplasm, including proteins, messenger RNA (mRNA), mitochondria and other organelles, is taken from a donor egg and injected into the recipient egg, resulting in a mixture of mitochondrial genetic material. This technique started to be used in the late 1990s to "boost" the eggs of older women who were having problems conceiving and led to the birth of about 30 babies. Concerns were raised that the mixture of genetic material and proteins could cause problems with respect to epigenetic clashes, or differences in the ability of the recipient and donor materials to effect the development process, or due to the injection of the donor material. After three children born through the technique were found to have developmental disorders (two cases of Turner's syndrome and one case of pervasive developmental disorder (an autism spectrum disorder), the FDA banned the procedure until a clinical trial could prove its safety. As of 2015 that study had not been conducted, but the procedure was in use in other countries.
A related approach uses autologous mitochondria taken from healthy tissue to replace the mitochondria in damaged tissue. Transfer techniques include direct injection into damaged tissue and injection into vessels that supply blood to the tissue.
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Applied and Interdisciplinary Chemistry
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For a compressible fluid, with a barotropic equation of state, the unsteady momentum conservation equation
With the irrotational assumption, namely, the flow velocity can be described as the gradient of a velocity potential . The unsteady momentum conservation equation becomes
which leads to
In this case, the above equation for isentropic flow becomes:
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Applied and Interdisciplinary Chemistry
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Kodesomes are liposomes that have been decorated with FSL Kode constructs. These have been used to deposit FSL constructs onto microplates to create diagnostic assays. They also have the potential for therapeutic use.
| 1 |
Applied and Interdisciplinary Chemistry
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Neither SbOCl nor the latter compound occur naturally. However, onoratoite is a known Sb-O-Cl mineral, its composition being SbClO.
| 1 |
Applied and Interdisciplinary Chemistry
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Somatic tissue can be stored in vitro for short periods of time. This is done in a light and temperature controlled environment that regulates the growth of cells. As an ex situ conservation technique tissue culture is primary used for clonal propagation of vegetative tissue or immature seeds. This allows for the proliferation of clonal plants from a relatively small amount of parent tissue.
| 1 |
Applied and Interdisciplinary Chemistry
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Supramolecular chemistry has found many applications, in particular molecular self-assembly processes have been applied to the development of new materials. Large structures can be readily accessed using bottom-up synthesis as they are composed of small molecules requiring fewer steps to synthesize. Thus most of the bottom-up approaches to nanotechnology are based on supramolecular chemistry. Many smart materials are based on molecular recognition.
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Theoretical and Fundamental Chemistry
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A bioeffector is a viable microorganism or active natural compound which directly or indirectly affects plant performance (biofertilizer), and thus has the potential to reduce fertilizer and pesticide use in crop production.
| 1 |
Applied and Interdisciplinary Chemistry
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Cutting is a collection of processes wherein material is brought to a specified geometry by removing excess material using various kinds of tooling to leave a finished part that meets specifications. The net result of cutting is two products, the waste or excess material, and the finished part. In woodworking, the waste would be sawdust and excess wood. In cutting metals the waste is chips or swarf and excess metal.
Cutting processes fall into one of three major categories:
* Chip producing processes most commonly known as machining
* Burning, a set of processes wherein the metal is cut by oxidizing a kerf to separate pieces of metal
* Miscellaneous specialty process, not falling easily into either of the above categories
Drilling a hole in a metal part is the most common example of a chip producing process. Using an oxy-fuel cutting torch to separate a plate of steel into smaller pieces is an example of burning. Chemical milling is an example of a specialty process that removes excess material by the use of etching chemicals and masking chemicals.
There are many technologies available to cut metal, including:
*Manual technologies: saw, chisel, shear or snips
*Machine technologies: turning, milling, drilling, grinding, sawing
*Welding/burning technologies: burning by laser, oxy-fuel burning, and plasma
*Erosion technologies: by water jet, electric discharge, or abrasive flow machining.
*Chemical technologies: Photochemical machining
Cutting fluid or coolant is used where there is significant friction and heat at the cutting interface between a cutter such as a drill or an end mill and the workpiece. Coolant is generally introduced by a spray across the face of the tool and workpiece to decrease friction and temperature at the cutting tool/workpiece interface to prevent excessive tool wear. In practice there are many methods of delivering coolant.
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Applied and Interdisciplinary Chemistry
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For a redox reaction
R O + e, without mass-transfer limitation, the relationship between the current density and the electrode overpotential is given by the Butler–Volmer equation:
with
is the exchange current density and and are the symmetry factors.
The curve vs. is not a straight line (Fig. 1), therefore a redox reaction is not a linear system.
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Theoretical and Fundamental Chemistry
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Diphosphene is a type of organophosphorus compound that has a phosphorus–phosphorus double bond, denoted by R-P=P-R'. These compounds are not common but are of theoretical interest. Normally, compounds with the empirical formula RP exist as rings. However, like other multiple bonds between heavy main-group elements, P=P double bonds can be stabilized by a large steric hindrance from the substitutions. The first isolated diphosphene bis(2,4,6-tri-tert-butylphenyl)diphosphene was exemplified by Masaaki Yoshifuji and his coworkers in 1981, in which diphosphene is stabilized by two bulky phenyl group.
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Theoretical and Fundamental Chemistry
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The thermodynamic solubility constant is defined for large monocrystals. Solubility will increase with decreasing size of solute particle (or droplet) because of the additional surface energy. This effect is generally small unless particles become very small, typically smaller than 1 μm. The effect of the particle size on solubility constant can be quantified as follows:
where *K is the solubility constant for the solute particles with the molar surface area A, *K is the solubility constant for substance with molar surface area tending to zero (i.e., when the particles are large), γ is the surface tension of the solute particle in the solvent, A is the molar surface area of the solute (in m/mol), R is the universal gas constant, and T is the absolute temperature.
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Theoretical and Fundamental Chemistry
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* IMRET 1, Frankfurt, Germany, February 1997
* IMRET 2, New Orleans, United States, March 1998
* IMRET 3, Frankfurt, Germany, April 1999
* IMRET 4, Atlanta, United States, March 2000
* IMRET 5, Strasbourg, France, May 2001
* IMRET 6, New Orleans, United States, March 2002
* IMRET 7, Lausanne, Switzerland, September 2003
* IMRET 8, Atlanta, United States, April 2005
* IMRET 9, Potsdam, Germany, September 2006
* IMRET 10, New Orleans, United States, April 2008
* IMRET 11, Kyoto, Japan, March 2010
* IMRET 12, Lyon, France, February 2012
* IMRET 13, Budapest, Hungary, June 2014
* IMRET 14, Beijing, China, September 2016
* IMRET 15, Karlsruhe, Germany, October 2018
| 1 |
Applied and Interdisciplinary Chemistry
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While tubulin and related structural proteins also bind and hydrolyze GTP as part of their function to form intracellular tubules, these proteins utilize a distinct tubulin domain that is unrelated to the G domain used by signaling GTPases.
There are also GTP-hydrolyzing proteins that use a P-loop from a superclass other than the G-domain-containg one. Examples include the NACHT proteins of its own superclass and McrB protein of the AAA+ superclass.
| 1 |
Applied and Interdisciplinary Chemistry
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Potassium thioacetate, which is commercially available, can be prepared by combining acetyl chloride and potassium hydrogen sulfide:
It arises also by the neutralization of thioacetic acid with potassium hydroxide.
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Theoretical and Fundamental Chemistry
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As of 2006, the most precise measurement of R had been obtained by measuring the speed of sound c(P, T) in argon at the temperature T of the triple point of water at different pressures P, and extrapolating to the zero-pressure limit c(0, T). The value of R is then obtained from the relation:
where:
*γ is the heat capacity ratio ( for monatomic gases such as argon);
*T is the temperature, T = 273.16 K by the definition of the kelvin at that time;
*A(Ar) is the relative atomic mass of argon and M = as defined at the time.
However, following the 2019 redefinition of the SI base units, R now has an exact value defined in terms of other exactly defined physical constants.
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Theoretical and Fundamental Chemistry
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Lanthanum cuprate usually refers to the inorganic compound with the formula CuLaO. The name implies that the compound consists of a cuprate (CuO]) salt of lanthanum (La). In fact it is a highly covalent solid. It is prepared by high temperature reaction of lanthanum oxide and copper(II) oxide follow by annealing under oxygen.
The material adopts a tetragonal structure related to potassium tetrafluoronickelate (KNiF), which is orthorhombic. Replacement of some lanthanum by barium gives the quaternary phase CuLaBaO, called lanthanum barium copper oxide. That doped material displays superconductivity at , which at the time of its discovery was a high temperature. This discovery initiated research on cuprate superconductors and was the basis of a Nobel Prize in Physics to Georg Bednorz and K. Alex Müller.
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Theoretical and Fundamental Chemistry
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In the eighth chapter, Kanada dwells on nature of cognition and reality, arguing that cognition is a function of the object (substance) and subject. Some sutras are unclear, such as one on Artha, which Kanada states is applicable only to "substance, quality and action" per his chapter one.
| 1 |
Applied and Interdisciplinary Chemistry
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To generate a nonthermal plasma at atmospheric pressure, a working gas (molecular or inert gas, e.g. air, nitrogen, argon, helium) is passed through an electric field. Electrons originating from ionization processes can be accelerated in this field to trigger impact ionization processes. If more free electrons are produced during this process than are lost, a discharge can build up. The degree of ionization in technically used plasmas is usually very low, typically a few per mille or less. The electrical conductivity generated by these free charge carriers is used to couple in electrical power. When colliding with other gas atoms or molecules, the free electrons can transfer their energy to them and thus generate highly reactive species that act on the material to be treated (gaseous, liquid, solid). The electron energy is sufficient to split covalent bonds in organic molecules. The energy required to split single bonds is in the range of about 1.5 - 6.2 eV, for double bonds in the range of about 4.4 - 7.4 eV and for triple bonds in the range of 8.5 - 11.2 eV . For gases that can also be used as process gases, dissociation energies are e.g. 5.7 eV (O2) and 9.8 eV (N2)
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Theoretical and Fundamental Chemistry
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C5a is a powerful inflammatory mediator, and seems to be a key factor in the development of pathology of many inflammatory diseases involving the complement system such as sepsis, rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythemotosis, psoriasis. The inhibitor of C5a that can block its effects would be helpful in medical applications.
Another candidate is PMX53 or PMX205 that is highly specific for CD88 and effectively reduces inflammatory response. C5a has been identified as a key mediator of neutrophil dysfunction in sepsis, with antibody blockade of C5a improving outcomes in experimental models. This has also been shown in humans, with C5a-mediated neutrophil dysfunction predicting subsequent nosocomial infection and death from sepsis. Recent data demonstrates that C5a not only impairs phagocytosis by neutrophils but also impairs phagosomal maturation, inducing a marked alteration in the neutrophil phosphoproteomic response to bacterial targets. C5a binding to C5aR1 and C5aR2 (C5L2) mediates the formation of neutrophil extracellular traps and release of cytotoxic histones to the extracellular space, which is believed to act as a pathogenetic process of acute respiratory distress syndrome (ARDS) and promote tumor growth and metastasis.
| 1 |
Applied and Interdisciplinary Chemistry
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A glycinergic agent (or drug) is a chemical which functions to directly modulate the glycine system in the body or brain. Examples include glycine receptor agonists, glycine receptor antagonists, and glycine reuptake inhibitors.
| 1 |
Applied and Interdisciplinary Chemistry
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The journal is run by an Ownership Board, on which all the member societies have equal representation. The eighteen participating societies are:
* Canadian Society for Chemistry
* Deutsche Bunsen-Gesellschaft für Physikalische Chemie (Germany)
* Institute of Chemistry of Ireland
* Israel Chemical Society
* Kemian Seurat (Finland)
* Kemisk Forening (Denmark)
* Koninklijke Nederlandse Chemische Vereniging (Netherlands)
* Korean Chemical Society
* New Zealand Institute of Chemistry
* Norsk Kjemisk Selskap (Norway)
* Polskie Towarzystwo Chemiczne (Poland)
* Real Sociedad Española de Química (Spain)
* Royal Australian Chemical Institute
* Royal Society of Chemistry (United Kingdom)
* Società Chimica Italiana (Italy)
* Svenska Kemisamfundet (Sweden)
* Swiss Chemical Society
* Türkiye Kimya Dernegi (Turkey)
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Theoretical and Fundamental Chemistry
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*[http://www.epa.gov/ttn/chief/ap42/index.html AP 42, Compilation of Air Pollutant Emission Factors] US Environmental Protection Agency
*[https://web.archive.org/web/20080328084843/http://reports.eea.europa.eu/EMEPCORINAIR5/en/page002.html EMEP/CORIMAIR 2007 Emission Inventory Guidebook].
*[https://web.archive.org/web/20060904125610/http://files.harc.edu/Projects/AirQuality/Projects/H005.2002/H5FinalReport.pdf Fugitive emissions leaks from ethylene and other chemical plants].
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Applied and Interdisciplinary Chemistry
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To make a solder connection, a chemical flux is applied to the inner sleeve of a joint and the pipe is inserted. The joint is then heated, typically by using a propane or MAPP gas torch, although electrically heated soldering tools are sometimes used. Once the fitting and pipe have reached sufficient temperature, solder is applied to the heated joint, and the molten solder is drawn into the joint by capillary action as the flux vaporizes. "Sweating" is a term sometimes used to describe the soldering of pipe joints.
Where many connections must be made in a short period (such as plumbing of a new building), soldering is quicker and less expensive joinery than compression or flare fittings. A degree of skill is needed to make several reliable soldered joints quickly. If flux residue is thoroughly cleaned, soldering can produce a long-lasting connection at a low cost. However, using an open flame for heating joints can present fire and health hazards to building occupants and requires adequate ventilation.
| 1 |
Applied and Interdisciplinary Chemistry
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Plenty of radioactive ruthenium-103, ruthenium-106, and stable ruthenium are formed by the fission process. The ruthenium in PUREX raffinate can become oxidized to form volatile ruthenium tetroxide which forms a purple vapour above the surface of the aqueous liquor. The ruthenium tetroxide is very similar to osmium tetroxide; the ruthenium compound is a stronger oxidant which enables it to form deposits by reacting with other substances. In this way the ruthenium in a reprocessing plant is very mobile, difficult to stabilize, and can be found in odd places. It has been called extremely troublesome and has a notorious reputation as an especially difficult product to handle during reprocessing. Voloxidation combined with cold trap collection of the flue gases could recover the volatile ruthenium tetroxide before it can become a nuisance in further processing. After the radioactive isotopes have had time to decay, recovered ruthenium could be sold at its relatively high market value.
In addition, the ruthenium in PUREX raffinate forms a large number of nitrosyl complexes which makes the chemistry of the ruthenium very complex. The ligand exchange rate at ruthenium and rhodium tends to be long, hence it can take a long time for a ruthenium or rhodium compound to react.
At Chernobyl, during the fire, the ruthenium became volatile and behaved differently from many of the other metallic fission products. Some of the particles which were emitted by the fire were very rich in ruthenium.
As the longest-lived radioactive isotope ruthenium-106 has a half-life of only 373.59 days, it has been suggested that the ruthenium and palladium in PUREX raffinate should be used as a source of the metals after allowing the radioactive isotopes to decay. After ten half life cycles have passed over 99.96% of any radioisotope is stable. For Ru-106 this is 3,735.9 days or about 10 years.
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Theoretical and Fundamental Chemistry
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Atoms in molecules analysis of ((Dipp)P)Ge suggests that there is a double bond between P1-Ge. Bond order can be assessed by measuring the ellipticity, a measure of anisotropic electron density, at the bond critical point. For example, butane, ethylene, and ethyne have a bond ellipticity of 0.01, 0.30, and 0.00 respectively, which correspond to a single, double, and a triple bond. A bond critical point between P1-Ge with ρ=0.091 and ellipticity 0.297 was observed in ((Dipp)P)Ge, consistent with a double bond. . This contrasts ρ=0.083 and ellipticity 0.064 at the bond critical point of P2-Ge in ((Dipp)P)Ge. Delocalization index (DI) was also used to predict the bond order of ((Dipp)P)Ge. DI values for P1-Ge and P2-Ge were determined to be 1.275 and 0.843, consistent with a P1-Ge double bond and Wiberg bond indices calculated.
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Theoretical and Fundamental Chemistry
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the US National Institutes of Health state there is insufficient evidence to recommend for or against using vitamin D supplementation to prevent or treat COVID-19. The UK National Institute for Health and Care Excellence (NICE) does not recommend to offer a vitamin D supplement to people solely to prevent or treat COVID-19. Both organizations included recommendations to continue the previous established recommendations on vitamin D supplementation for other reasons, such as bone and muscle health, as applicable. Both organizations noted that more people may require supplementation due to lower amounts of sun exposure during the pandemic.
Several systematic reviews and meta-analyses of multiple studies have described the associations of vitamin D deficiency with adverse outcomes in COVID-19. In the largest analysis, with data from 76 observational studies including almost two million adults, vitamin D deficiency or insufficiency significantly increased the susceptibility to becoming infected with COVID-19 and having severe COVID-19, with odds ratios of 1.5 and 1.9 respectively, but these findings had high risk of bias and heterogeneity. A two-fold greater mortality was found, but this analysis was less robust. These findings confirm smaller, earlier analyses, one of which, in reporting that people with COVID-19 tend to have lower 25(OH)D levels than healthy subjects, stated that the trend for associations with health outcomes was limited by the low quality of the studies and by the possibility of reverse causality mechanisms.
A meta-analysis of three studies on the effect of oral vitamin D or calcifediol supplementation indicated a lower intensive care unit (ICU) admission rate (odds ratio: 0.36) compared to those without supplementation, but without a change in mortality. A Cochrane review, also of three studies, found the evidence for the effectiveness of vitamin D supplementation for the treatment of COVID-19 to be very uncertain. They found there was substantial clinical and methodological heterogeneity in the three studies that were included, mainly because of different supplementation strategies, vitamin D formulations (one using calcifediol), pre-treatment status and reported outcomes. Another meta-analysis stated that the use of high doses of vitamin D in people with COVID-19 is not based on solid evidence although calcifediol supplementation may have a protective effect on ICU admissions.
| 1 |
Applied and Interdisciplinary Chemistry
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Chiral auxiliaries are incorporated into synthetic routes to control the absolute configuration of stereogenic centers. David A. Evans' synthesis of the macrolide cytovaricin, considered a classic, utilizes oxazolidinone chiral auxiliaries for one asymmetric alkylation reaction and four asymmetric aldol reactions, setting the absolute stereochemistry of nine stereocenters.
A typical auxiliary-guided stereoselective transformation involves three steps: first, the auxiliary is covalently coupled to the substrate; second, the resulting compound undergoes one or more diastereoselective transformations; and finally, the auxiliary is removed under conditions that do not cause racemization of the desired products. The cost of employing stoichiometric auxiliary and the need to spend synthetic steps appending and removing the auxiliary make this approach appear inefficient. However, for many transformations, the only available stereoselective methodology relies on chiral auxiliaries. In addition, transformations with chiral auxiliaries tend to be versatile and very well-studied, allowing the most time-efficient access to enantiomerically pure products.
Furthermore, the products of auxiliary-directed reactions are diastereomers, which enables their facile separation by methods such as column chromatography or crystallization.
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Theoretical and Fundamental Chemistry
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Of the three common types of radiation given off by radioactive materials, alpha, beta and gamma, beta has the medium penetrating power and the medium ionising power. Although the beta particles given off by different radioactive materials vary in energy, most beta particles can be stopped by a few millimeters of aluminium. However, this does not mean that beta-emitting isotopes can be completely shielded by such thin shields: as they decelerate in matter, beta electrons emit secondary gamma rays, which are more penetrating than betas per se. Shielding composed of materials with lower atomic weight generates gammas with lower energy, making such shields somewhat more effective per unit mass than ones made of high-Z materials such as lead.
Being composed of charged particles, beta radiation is more strongly ionizing than gamma radiation. When passing through matter, a beta particle is decelerated by electromagnetic interactions and may give off bremsstrahlung x-rays.
In water, beta radiation from many nuclear fission products typically exceeds the speed of light in that material (which is 75% that of light in vacuum), and thus generates blue Cherenkov radiation when it passes through water. The intense beta radiation from the fuel rods of swimming pool reactors can thus be visualized through the transparent water that covers and shields the reactor (see illustration at right).
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Theoretical and Fundamental Chemistry
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The most critical aspect in biomass fermentation processes is related to its productivity. The ABE fermentation via Clostridium beijerinckii or Clostridium acetobutylicum for instance is characterized by product inhibition. This means that there is a product concentration threshold that cannot be overcome, resulting in a product stream highly diluted in water.
For this reason, in order to have a comparable productivity and profitability with respect to the petrochemical processes, cost and energy effective solutions for the product purification sections are required to provide a significant product recovery at the desired purity.
The main solutions adopted during the last decades have been as follows:
* The employment of less expensive raw materials, and in particular lignocellulosic waste or algae;
* The microorganisms modifications or the research of new strains less sensitive to the butanol concentration poisoning to increase productivity and selectivity towards the butanol species;
* The fermentation reactor optimization aimed at increasing the productivity;
* The reduction of the energy costs of the separation and purification downstream processing and, in particular, to carry out the separation in-situ in the reactor;
* The use of side products such as hydrogen and carbon dioxide, solid wastes and discharged microorganisms and carry out less expensive process wastewater treatments.
In the second half of the 20th century, these technologies allowed an increase in the final product concentration in the broth from 15 to 30 g/L, an increase in the final productivity from 0.46 to 4.6 g/(L*h) and an increase in the yield from 15 to 42%.
From a compound purification perspective, the main criticalities in the ABE/W product recovery are due to the water–alcohol mixture's non-ideal interactions leading to homogeneous and heterogeneous azeotropic species, as shown by the ternary equilibrium diagram.
This causes the separation by standard distillation to be particularly impractical but, on the other hand, allows the exploitation of the liquid–liquid demixing region both for analogous and alternative separation processes.
Therefore, in order to enhance the ABE fermentation yield, mainly in situ product recovery systems have been developed. These include gas stripping, pervaporation, liquid–liquid extraction, distillation via Dividing Wall Column, membrane distillation, membrane separation, adsorption, and reverse osmosis. Green Biologics Ltd. implemented many of these technologies at an industrial scale.
Moreover, differently from crude oil feedstocks, biomasses nature fluctuates over the years seasons and according to the geographical location. For this reasons, biorefinery operations need not only to be effective but also to be flexible and to be able to switch between two operating conditions rather quickly.[citation needed']
| 1 |
Applied and Interdisciplinary Chemistry
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In the mechanical stream of thinking about closed systems, heat transferred is defined as a calculated residual amount of energy transferred after the energy transferred as work has been determined, assuming for the calculation the law of conservation of energy, without reference to the concept of temperature. There are five main elements of the underlying theory.
*The existence of states of thermodynamic equilibrium, determinable by precisely one (called the non-deformation variable) more variable of state than the number of independent work (deformation) variables.
*That a state of internal thermodynamic equilibrium of a body have a well defined internal energy, that is postulated by the first law of thermodynamics.
*The universality of the law of conservation of energy.
*The recognition of work as a form of energy transfer.
*The universal irreversibility of natural processes.
*The existence of adiabatic enclosures.
*The existence of walls permeable only to heat.
Axiomatic presentations of this stream of thinking vary slightly, but they intend to avoid the notions of heat and of temperature in their axioms. It is essential to this stream of thinking that heat is not presupposed as being measurable by calorimetry. It is essential to this stream of thinking that, for the specification of the thermodynamic state of a body or closed system, in addition to the variables of state called deformation variables, there be precisely one extra real-number-valued variable of state, called the non-deformation variable, though it should not be axiomatically recognized as an empirical temperature, even though it satisfies the criteria for one.
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Theoretical and Fundamental Chemistry
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"Southwestern blot mapping" is a time-efficient way of identifying DNA-binding proteins and specific sites on the genomic DNA that they interact with.
# First, proteins are prepared with a mixture that exposes them to the denaturing sodium dodecyl sulfate (SDS) agent. This exposure not only converts the proteins from a folded conformation to an unfolded conformation but also establishes uniform charge among them as well contributing to the ease of separation on a size basis using polyacrylamide gel (PAGE).
# Second, in contrast to the previous step, proteins on the resulting gel are to be renatured by removal of SDS. This serves to bring the proteins back to the form that ideally maximizes interactions later on in the procedure.
# Third, blotting takes place onto nitrocellulose membranes using methods for and properties of diffusion.
# Fourth, shifting to probe creation, particular restriction enzymes are chosen and used on the region of DNA under study to produce fragments of appropriate but different sizes.
# Fifth, the fragments are radioactively labeled and given appropriate time for binding to previously prepared blots. Once this time has elapsed, the blots are washed to remove any DNA that was not able to bind.
# Finally, the specifically-bound DNA is eluted from each individual protein-DNA complex and analyzed by another application of polyacrylamide gel electrophoresis.
| 1 |
Applied and Interdisciplinary Chemistry
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Compacted oxide layers can form due to sliding at low temperatures and offer some wear protection, however, in the absence of heat as a driving force (either due to frictional heating or higher ambient temperature), they cannot sinter together to form more protective glaze layers.
| 1 |
Applied and Interdisciplinary Chemistry
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Also known as reductive Friedel–Crafts reaction, the Fischer–Hafner synthesis entails treatment of metal chlorides with arenes in the presence of aluminium trichloride and aluminium metal. The method was demonstrated in the 1950s with the synthesis of bis(benzene)chromium by Walter Hafner and his advisor E. O. Fischer. The method has been extended to other metals, e.g. [Ru(CMe)]. In this reaction, the AlCl serves to remove chloride from the metal precursor, and the Al metal functions as the reductant. The Fischer-Hafner synthesis is limited to arenes lacking sensitive functional groups.
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Theoretical and Fundamental Chemistry
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In 1994, Dunne was appointed as a Postdoctoral research associate in the Department of Mechanical Engineering, University of Manchester (UMIST), before being appointed a Research Fellowship at Hertford College, Oxford and the Department of Engineering Science, University of Oxford from 1996 until 2012. He became the dean of the department but moved to Imperial College London in 2012. He is an Emeritus Fellow of Hertford College, Oxford.
While in Oxford, Dune was part of the Materials for fusion & fission power program. He led the Micro-mechanical modelling techniques for forming texture, non-proportionality and failure in auto materials program at the Department of Engineering Science, University of Oxford between October 2011 and June 2012, when he moved the grant with him to the Department of Materials, Imperial College London from June 2012 until it ended in March 2015.
He also led the Heterogeneous Mechanics in Hexagonal Alloys across Length and Time Scales (HexMat) program, which was Engineering and Physical Sciences Research Council (EPSRC) funded at a value of £5 million between May 2013 and November 2018. Dunne was the director of the Rolls-Royce Nuclear University Technology Centre at Imperial College London. He is part of a £7.2 million program on Mechanistic understanding of Irradiation Damage in fuel Assemblies (MIDAS) that is funded by Engineering and Physical Sciences Research Council until April 2024
As of November 2022, Dunne is a Professor of Materials Science at Imperial College London and holds the Chair in Micromechanics and the Royal Academy of Engineering (RAEng)/Rolls-Royce Research Chair. He is also a Rolls-Royce consultant, and an Honorary Professor and co-director of the Beijing International Aeronautical Materials (BIAM).
Dunne's research focuses on computational crystal plasticity, discrete dislocation plasticity, and microstructure-sensitive nucleation and growth of short fatigue cracks in engineering materials, mainly Nickel, Titanium, and Zirconium alloys.
| 1 |
Applied and Interdisciplinary Chemistry
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One of the widely used ways to excite emission of excimer molecules is an electric discharge. There are a lot of discharge types used for pumping excimer lamps. Some examples are glow discharge, pulsed discharge, capacitive discharge, longitudinal and transverse discharges, volume discharge, spark discharge, and microhollow discharge.
, dielectric barrier discharge (DBD), a type of capacitive discharge, is the most common type used in commercial lamps. A benefit of the DBD excimer lamps is that the electrodes are not in direct contact with the active medium (plasma). Absence of interaction between the electrodes and the discharge eliminates electrode corrosion as well as contamination of the active medium by sputtered electrode material, which considerably increases the lifetime of DBD excimer lamps in comparison with others. Moreover, a dielectric barrier discharge ensures effective excitation of a gas mixture in a wide range of working pressures from a few torrs to more than one atmosphere. Excimer lamps can be made in any desired shape of the radiating surface, satisfying requirements of a specific task.
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Theoretical and Fundamental Chemistry
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TaqMan probe-based assays are widely used in quantitative PCR in research and medical laboratories:
*Gene expression assays
*Pharmacogenomics
*Human Leukocyte Antigen (HLA) genotyping
*Determination of viral load in clinical specimens (HIV, Hepatitis)
*Bacterial Identification assays
*DNA quantification
*SNP genotyping
*Verification of microarray results
| 1 |
Applied and Interdisciplinary Chemistry
|
The Ross Gyre is located in the Southern Ocean surrounding Antarctica, just outside of the Ross Sea. This gyre is characterized by a clockwise rotation of surface waters, driven by the combined influence of wind, the Earth's rotation, and the shape of the seafloor. The gyre plays a crucial role in the transport of heat, nutrients, and marine life in the Southern Ocean, affecting the distribution of sea ice and influencing regional climate patterns.
The Ross Sea, Antarctica, is a region where the mixing of distinct water masses and complex interactions with the cryosphere lead to the production and export of dense water, with global-scale impacts. which controls the proximity of the warm waters of the Antarctic Circumpolar Current to the Ross Sea continental shelf, where they may drive ice shelf melting and increase sea level. The deepening of sea level pressures over the Southeast Pacific/Amundsen-Bellingshausen Seas generates a cyclonic circulation cell that reduces sea surface heights north of the Ross Gyre via Ekman suction. The relative reduction of sea surface heights to the north facilitates a northeastward expansion of the outer boundary of the Ross Gyre. Further, the gyre is intensified by a westward ocean stress anomaly over its southern boundary. The ensuing southward Ekman transport anomaly raises sea surface heights over the continental shelf and accelerates the westward throughflow by increasing the cross-slope pressure gradient. The sea level pressure center may have a greater impact on the Ross Gyre transport or the throughflow, depending on its location and strength. This gyre has significant effects on interactions in the Southern Ocean between waters of the Antarctic margin, the Antarctic Circumpolar Current, and intervening gyres with a strong seasonal sea ice cover play a major role in the climate system.
The Ross Sea is the southernmost sea on Earth and holds the United States' McMurdo Station and Italian Zuchelli Station. Even though this gyre is located nearby two of the most prominent research stations in the world for Antarctic study, the Ross Gyre remains one of the least sampled gyres in the world.
| 1 |
Applied and Interdisciplinary Chemistry
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Photo-reflectance is an optical technique for investigating the material and electronic properties of thin films. Photo-reflectance measures the change in reflectivity of a sample in response to the application of an amplitude modulated light beam. In general, a photo-reflectometer consists of an intensity modulated "pump" light beam used to modulate the reflectivity of the sample, a second "probe" light beam used to measure the reflectance of the sample, an optical system for directing the pump and probe beams to the sample, and for directing the reflected probe light onto a photodetector, and a signal processor to record the differential reflectance. The pump light is typically modulated at a known frequency so that a lock-in amplifier may be used to suppress unwanted noise, resulting in the ability to detect reflectance changes at the ppm level.
The utility of photo-reflectance for characterization of semiconductor samples has been recognized since the late 1960s. In particular,
conventional photo-reflectance is closely related to electroreflectance in that the sample's internal electric field is modulated by the photo-injection of electron-hole pairs. The electro-reflectance response is sharply peaked near semiconductor interband transitions, which accounts for its usefulness in semiconductor characterization. Photo-reflectance spectroscopy has been used to determine semiconductor bandstructures, internal electric fields, and other material properties such as crystallinity, composition, physical strain, and doping concentration.
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Theoretical and Fundamental Chemistry
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Later in his life in 1900, Becquerel measured the properties of beta particles, and he realized that they had the same measurements as high speed electrons leaving the nucleus. In 1901 Becquerel made the discovery that radioactivity could be used for medicine. Henri made this discovery when he left a piece of radium in his vest pocket and noticed that he had been burnt by it. This discovery led to the development of radiotherapy which is now used to treat cancer. In 1908 Becquerel was elected president of Académie des Sciences, but he died on 25 August 1908, at the age of 55, in Le Croisic, France. He died of a heart attack, but it was reported that "he had developed serious burns on his skin, likely from the handling of radioactive materials."
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Theoretical and Fundamental Chemistry
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In B. anthracis, petrobactin is produced by a nonribosomal peptide synthetase independent siderophore (NIS) synthetase pathway. The enzyme sequences used are anthrax siderophore biosynthesis (Asb) A through F, in alphabetical order. These gene clusters are identical to those used in M. hydrocarbonclasticus biosynthesis of petrobactin. In A. macleodii only the first three gene clusters, AsbA through AsbC, are identical to B. anthracis; then a longer AsbD and AsbF is next, followed by two hypothetical protein domains and a PepSY domain-containing gene. A. macleodii ends its sequence with AsbE.
The biosynthesis of petrobactin in B. anthracis can progress in order AsbA-AsbB-AsbE-AsbE or AsbA-AsbE-AsbB-AsbE.
If the enzymation reactions in this pathway proceed generally, in domains AsbA and AsbB the phosphorylation of a carboxylic acid forms an acylphosphate intermediate, which is then dephosphorylated by a primary amine in spermidine. In domain AsbE the lone pair of electrons on a primary amine allows for a nucleophilic attack on the electrophilic hydroxyl carbon. The sulfur on AsbE is protonated to form a thiol and the amide nitrogen is deprotonated.
The dehydration of 3-dehydroshikimic acid might proceed as a modified, enzyme-catalyzed dienol benzene rearrangement and reduction, leading to aromatization of the ring.
| 1 |
Applied and Interdisciplinary Chemistry
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Microencapsulated pheromones (MECs) are small droplets of pheromone enclosed within polymer capsules. The capsules control the release rate of the pheromone into the surrounding environment. The capsules are small enough to be applied in the same method as used to spray insecticides. The effective field longevity of the microencapsulated pheromone formulations ranges from a few days to slightly more than a week, depending on climatic conditions, capsule size and chemical properties. Microcapsules in the pheromone formulations are usually kept above a prescribed diameter to avoid the risk of inhalation by humans.
| 1 |
Applied and Interdisciplinary Chemistry
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Microbiota-accessible carbohydrates (MACs) are carbohydrates that are resistant to digestion by a hosts metabolism, and are made available for gut microbes, as prebiotics, to ferment or metabolize into beneficial compounds, such as short chain fatty acids. The term, ‘‘microbiota-accessible carbohydrate’’ contributes to a conceptual framework for investigating and discussing the amount of metabolic activity that a specific food or carbohydrate can contribute to a hosts microbiota.
MACs may come from plants, fungi, animal tissues, or food-borne microbes, and must be metabolized by the microbiome. A significant quantity of the cellulose humans consume is not metabolized by gut microbes and therefore cannot be considered a MAC. The amount of dietary MACs found within a food source will differ for each individual, since which carbohydrates are metabolized depends upon the composition of each person's microbiota. For example, many Japanese individuals possess the genes for the consumption of the algal polysaccharide porphyran in their microbiomes, which are rarely found in North American and European individuals. For individuals who harbor such a porphyran-degrading strain, porphyran would be a MAC. However, porphyran would not be a MAC for those without a microbiota adaptation to seaweed. In similar fashion, germ-free mice without a microbiota might consume a diet with large quantities of potential MACs, but none of the carbohydrates would be considered MACs, since they would escape the digestive tract without being metabolized by microbes.
Lack of dietary MACs results in a microbiota reliant upon endogenous host-derived MACs, such as mucin glycans. Different host genotypes can influence the identity of MACs available to the microbiota in multiple ways. For example, a hosts genes may affect the level of mucus structures, such as the absence of alpha-1-2 fucose residues in the mucus of nonsecretor individuals who lack alpha-1-2- fucosyltransferase activity in the intestine. Similarly, a host may have genes that can determine the efficiency of digestion and absorption of carbohydrates in the small intestine. For example, lactose is accessible to the microbiota in people who are lactose intolerant, and should therefore be considered a MAC for those individuals. For nursing infants, dietary MACs that are naturally found in breast milk are known as human milk oligosaccharides (HMOs). For formula-fed infants, dietary MACs, such as galacto-oligosaccharides, are artificially added to formula. Therefore, the research, discussion and quantification of MACs and their impact on a hosts microbiota may be critical to determining their impact on human health.
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Theoretical and Fundamental Chemistry
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Thus, although many zinc salts have different formulas and different crystal structures, these salts behave very similarly in aqueous solution. For example, solutions prepared from any of the polymorphs of , 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:
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Theoretical and Fundamental Chemistry
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Superfluid helium-4 (helium II or He-II) is the superfluid form of helium-4, an isotope of the element helium. A superfluid is a state of matter in which matter behaves like a fluid with zero viscosity. The substance, which resembles other liquids such as helium I (conventional, non-superfluid liquid helium), flows without friction past any surface, which allows it to continue to circulate over obstructions and through pores in containers which hold it, subject only to its own inertia.
The formation of the superfluid is a manifestation of the formation of a Bose–Einstein condensate of helium atoms. This condensation occurs in liquid helium-4 at a far higher temperature (2.17 K) than it does in helium-3 (2.5 mK) because each atom of helium-4 is a boson particle, by virtue of its zero spin. Helium-3, however, is a fermion particle, which can form bosons only by pairing with itself at much lower temperatures, in a weaker process that is similar to the electron pairing in superconductivity.
| 1 |
Applied and Interdisciplinary Chemistry
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In population ecology, a regulating factor, also known as a limiting factor, is something that keeps a population at equilibrium (neither increasing nor decreasing in size over time). Common limiting factor resources are environmental features that limit the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem. The concept of limiting factors is based on Liebigs Law of the Minimum, which states that growth is controlled not by the total amount of resources available, but by the scarcest resource. In other words, a factor is limiting if a change in the factor produces increased growth, abundance, or distribution of an organism when other factors necessary to the organisms life do not. Limiting factors may be physical or biological.
Limiting factors are not limited to the condition of the species. Some factors may be increased or reduced based on circumstances. An example of a limiting factor is sunlight in the rain forest, where growth is limited to all plants on the forest floor unless more light becomes available. This decreases the number of potential factors that could influence a biological process, but only one is in effect at any one place and time. This recognition that there is always a single limiting factor is vital in ecology, and the concept has parallels in numerous other processes. The limiting factor also causes competition between individuals of a species population. For example, space is a limiting factor. Many predators and prey need a certain amount of space for survival: food, water, and other biological needs. If the population of a species is too high, they start competing for those needs. Thus the limiting factors hold down population in an area by causing some individuals to seek better prospects elsewhere and others to stay and starve. Some other limiting factors in biology include temperature and other weather related factors. Species can also be limited by the availability of macro- and micronutrients. There has even been evidence of co-limitation in prairie ecosystems. A study published in 2017 showed that sodium (a micronutrient) had no effect on its own, but when in combination with nitrogen and phosphorus (macronutrients), it did show positive effects, which is evidence of serial co-limitation.
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Theoretical and Fundamental Chemistry
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5-methylcytosine, commonly abbreviated as "mC", is a chemical modification first identified in tRNA. Since its initial identification, 5-methylcytosine has been found in a variety of different cellular structures ranging from a variety of RNAs and even DNA. Two different kinds of RNA mC "writers" have been identified: NOP2/SUN RNA methyltransferase (NSUN) and DNA methyltransferase-2. It is important to note that DNMT-2 is a protein that falls under the DNMT family, which contains three other DNMTs (1, 3a, and 3b) known to demonstrate methylation activity in relation to the genome. Uniquely, DNMT-2 is the only DNMT that has been confirmed to methylate both DNA and RNA, although its overall DNA methylation function is significantly less than that of its counterparts. While these writers have been identified, as of now, there are no known mC "erasers"; in a broader sense, this means that reamination, or the conversion of 5-methylcytosine back into cytosine, has not been observed in RNA. 5-methylcytosine modifications are typically found approximately 100 nucleotides downstream of translation initiation sites. This may provide some insight into the purpose of these modifications; for instance, this may indicate that these modifications are important for controlling the fate of the RNA, such as whether it will be translated or not in the case of mRNA. However, the exact purpose of the methylation at specific cytosines in RNA is currently unknown. One possibility may be that mC may be associated with RNA transport, since the Aly/REF export factor is a known mC binding protein. On the other hand, mC modifications could possibly be associated with the regulation of genes involved in energy and lipid metabolism, through modulation of the overall RNA translational fate.
| 1 |
Applied and Interdisciplinary Chemistry
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In 1917, the purely scientific interest in the study of radium was replaced by the practical need to use it for military purposes - the military department and defense organizations received information that radium was used for the production of light compounds. The necessity of radium extraction from domestic raw materials became urgent. A large batch of radium-containing ore from the Tyuya-Muyun deposit was stored in the warehouse of a private commercial firm "Fergana Society for Rare Metals Mining". This organization, due to the lack of specialists-radiochemists in Russia, was preparing the raw material for shipment to Germany for technological extraction of the final product from it, but the war and then the February Revolution of 1917 prevented this.
The Congress for the Technical Defense of the State in October 1917 decided to organize a special radium plant under the direct control of the Academy of Sciences, but the October Socialist Revolution again removed this issue from the queue. In January 1918 V. G. Khlopin published an article "A Few Words on the Application of Radioactive Elements in Military Technology and on the Possible Future of the Radium Industry in Russia", in which he characterized the importance and prospective use of radium for military-strategic purposes. In the spring of the same year, the Presidium of the All-Russian Council of National Economy (RCNE) decided to sequester radioactive raw materials belonging to the "Fergana Society"; in April, the Chemical Department of the RCNE, headed by Prof. L. Ya. Karpov, entrusted the Academy of Sciences with the mission of organizing a plant for radium extraction from domestic uranium-vanadium ores and ensuring scientific control over production; at a meeting of specialists convened on 12 April by the Commission for the Study of the Natural Productive Forces of Russia (NPFR), headed by N. S. Kovalev. С. Kurnakov, V. G. Khlopin and L. I. Bogoyavlensky it was reported on the results of the work undertaken to obtain radium from the available raw materials; in July 1918 a special Commission, the Technical Council or later the Board for the organization of a radium plant at the Academy of Sciences was elected, which decided to organize a research laboratory, a special Radium Department (under the Commission) headed by V. I. Vernadsky was established under the chairmanship of A. E. Fersman, senior mineralogist of the Academy of Sciences, professor of the Higher Women's Courses. The secretary of the department, a specialist of the Radium Laboratory of the Academy, an assistant of the Department of General Chemistry of the Petrograd University, 28-year-old V. G. Khlopin, was appointed its commissioner for the organization of the radium plant. His thorough theoretical training and mastery of the methods of fine chemical analysis, his ability to solve practical problems effectively, and his experience in expeditions fully justified his involvement in such a responsible business. L. N. Bogoyavlensky, a specialist on this subject, was invited as the head of the plant.
"October 28, 1918.<br>Uralsovnarkhoz (Perm), Usolsk executive committee, Management of Berezniki soda plant.<br> «I order the Berezniki plant to immediately begin work on the organization of a radium plant according to the resolution of the Vysovnarkhoz. The necessary funds have been allocated by the Council of Peoples Commissars. The work should be carried out under the direction and responsibility of chemical engineer Bogoyavlensky, to whom I propose to render full assistance.<br> Chairman of the Council of People s Commissars Lenin»".
Lenin V. I. Complete Collected Works, vol. 50, p. 375.
In 1918, all radioactive residues that were in Petrograd were evacuated inland - first to the Berezniki soda plant in Perm province, and in May 1920, already by the new plant manager I. Ya. Bashilov, - to the Bondyuzhsky chemical plant of Khimosnov (now Khimzavod named after L. Y. Karpov in Mendeleevsk), where only in the fall of 1920 it became possible to put into operation a temporary pilot plant for radium extraction.
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Theoretical and Fundamental Chemistry
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The Sauter diameter (SD, also denoted D[3,2] or d_{32}) for a given particle is defined as:
where d is the so-called surface diameter and d is the volume diameter, defined as:
The quantities A and V are the ordinary surface area and volume of the particle, respectively.
The equation may be simplified further as:
This is usually taken as the mean of several measurements, to obtain the Sauter mean diameter (SMD):
This provides intrinsic data that help determine the particle size for fluid problems.
| 1 |
Applied and Interdisciplinary Chemistry
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For high energy photons it is useful to distinguish between small and large angle scattering. For large angles, where , the scatter ratio is large and
showing that the (large angle) differential cross section is inversely proportional to the photon energy.
The differential cross section has a constant peak in the forward direction:
independent of . From the large angle analysis it follows that this peak can only extend to about . The forward peak is thus confined to a small solid angle of approximately , and we may conclude that the total small angle cross section decreases with .
| 0 |
Theoretical and Fundamental Chemistry
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The primary UK legislation is the Food Safety Act 1990. All local authorities are required to appoint a Public Analyst, although there have always been fewer Public Analysts and their laboratories than local authorities, most being shared by a number of local authorities. On the UK mainland there has always been a mixture of public sector and private sector laboratories. This remains the case today - but they all provide an equivalent service, and avoidance of conflicts of interest are ensured by the statutory terms of appointment. There is a statutory qualification requirement for Public Analysts, known as the Mastership in Chemical Analysis (MChemA), awarded by the Royal Society of Chemistry. This is a specialist postgraduate qualification by examination that verifies knowledge and understanding of food and its potential defects, interpretation of food law, and the application and interpretation of chemical analysis for food law enforcement.
The Public Analysts’ laboratories must be third-party accredited to International Standard BS EN ISO/IEC 17025:2017.
In the mid 1980s there were some 40 Public Analyst Laboratories in the UK with over 100 appointed Public Analysts. By 1993 that had reduced to 34 Laboratories and around 80 Public Analysts, and by 2010 the number of Public Analyst Laboratories had reduced to 22 with only about 26 Public Analysts. As of 2022 there are 15 Public Analyst laboratories remaining in the UK. In part, the reduction in number of laboratories over the decades has been due to rationalisation and benefits from economies of scale; however, by a larger part, it has arisen due to lack of adequate funding. Although some of the remaining laboratories are larger than many that no longer exist, the overall capacity of the system is now far less than it used to be.
Enforcement of food law in the UK is done by local authorities, principally their environmental health officers and trading standards officers. Whilst these officers are empowered to take samples of food, the actual assessment in terms of chemical analysis or microbiological examination and subsequent interpretation that are necessary to determine whether a food complies with legislation, is carried out by Public Analysts and Food Examiners respectively, scientists whose qualifications and experience are specified by regulations.
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Applied and Interdisciplinary Chemistry
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Integrated discrete Multiple Organ Culture (IdMOC) is an in vitro, cell culture based experimental model for the study of intercellular communication. In conventional in vitro systems, each cell type is studied in isolation ignoring critical interactions between organs or cell types. IdMOC technology is based on the concept that multiple organs signal or communicate via the systemic circulation (i.e., blood).
The IdMOC plate consists of multiple inner wells within a large interconnecting chamber. Multiple cell types are first individually seeded in the inner wells and, when required, are flooded with an overlying medium to facilitate well-to-well communication. Test material can be added to the overlying medium and both media and cells can be analyzed individually. Plating of hepatocytes with other organ-specific cells allows evaluation of drug metabolism and organotoxicity.
The IdMOC system has numerous applications in drug development, such as the evaluation of drug metabolism and toxicity. It can simultaneously evaluate the toxic potential of a drug on cells from multiple organs and evaluate drug stability, distribution, metabolite formation, and efficacy. By modeling multiple-organ interactions, IdMOC can examine the pharmacological effects of a drug and its metabolites on target and off-target organs as well as evaluate drug-drug interactions by measuring cytochrome P450 (CYP) induction or inhibition in hepatocytes.
IdMOC can also be used for routine and high throughput screening of drugs with desirable ADME or ADME-Tox properties. In vitro toxicity screening using hepatocytes in conjunction with other primary cells such as cardiomyocytes (cardiotoxicity model), kidney proximal tubule epithelial cells (nephrotoxicity model), astrocytes (neurotoxicity model), endothelial cells (vascular toxicity model), and airway epithelial cells (pulmonary toxicity model) is invaluable to the drug design and discovery process.
The IdMOC was patented by Dr. Albert P. Li in 2004.
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Applied and Interdisciplinary Chemistry
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DNA profiling (also called DNA fingerprinting and genetic fingerprinting) is the process of determining an individual's deoxyribonucleic acid (DNA) characteristics. DNA analysis intended to identify a species, rather than an individual, is called DNA barcoding.
DNA profiling is a forensic technique in criminal investigations, comparing criminal suspects' profiles to DNA evidence so as to assess the likelihood of their involvement in the crime. It is also used in paternity testing, to establish immigration eligibility, and in genealogical and medical research. DNA profiling has also been used in the study of animal and plant populations in the fields of zoology, botany, and agriculture.
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Applied and Interdisciplinary Chemistry
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Members of the HNF1 subfamily contain a POU-homeodomain and bind to DNA as homodimers.
* HNF1α/TCF1/MODY3 (related disease: MODY 3)
* HNF1β/TCF2/MODY5 (related disease: MODY 5)
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Applied and Interdisciplinary Chemistry
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Contrary to form-based restoration, which consists of improving a streams conditions by modifying its structure, process-based restoration focuses on restoring the hydrological and geomorphological processes (or functions) that contribute to the streams alluvial and ecological dynamics. This type of stream restoration has gained in popularity since the mid-1990s, as a more ecosystem-centered approach. Process-based restoration includes restoring lateral connectivity (between the stream and its floodplain), longitudinal connectivity (along the stream) and water and/or sediment fluxes, which might be impacted by hydro-power dams, grade control structures, erosion control structures and flood protection structures. Valley Floor Resetting epitomises process-based restoration by infilling the river channel and allowing the stream to carve its anastomosed channel anew, matching [http://stagezeroriverrestoration.com/index.html Stage Zero] on the Stream Evolution Model. In general, process-based restoration aims to maximize the resilience of the system and minimize maintenance requirements. In some instances, form-based restoration methods might be coupled with process-based restoration to restore key structures and achieve quicker results while waiting for restored processes to ensure adequate conditions in the long term.
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Applied and Interdisciplinary Chemistry
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The hybrid difference scheme is a method used in the numerical solution for convection–diffusion problems. It was introduced by Spalding (1970). It is a combination of central difference scheme and upwind difference scheme as it exploits the favorable properties of both of these schemes.
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Applied and Interdisciplinary Chemistry
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Sedimentation velocity experiments render the shape and molar mass of the analytes, as well as their size-distribution. The size resolution of this method scales approximately with the square of the particle radii, and by adjusting the rotor speed of the experiment size-ranges from 100 Da to 10 GDa can be covered. Sedimentation velocity experiments can also be used to study reversible chemical equilibria between macromolecular species, by either monitoring the number and molar mass of macromolecular complexes, by gaining information about the complex composition from multi-signal analysis exploiting differences in each components spectroscopic signal, or by following the composition dependence of the sedimentation rates of the macromolecular system, as described in Gilbert-Jenkins theory.
The experiment aims to monitor the sedimentation behavior at a fixed angular speed.
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Applied and Interdisciplinary Chemistry
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In geochemistry, a version of Henry's law applies to the solubility of a noble gas in contact with silicate melt. One equation used is
where
:C is the number concentrations of the solute gas in the melt and gas phases,
:β = 1/kT, an inverse temperature parameter (k is the Boltzmann constant),
:µ is the excess chemical potentials of the solute gas in the two phases.
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Theoretical and Fundamental Chemistry
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The word placebo was used in a medicinal context in the late 18th century to describe a "commonplace method or medicine" and in 1811 it was defined as "any medicine adapted more to please than to benefit the patient". Although this definition contained a derogatory implication, it did not necessarily imply that the remedy had no effect.
Placebos have featured in medical use until well into the twentieth century. In 1955 Henry K. Beecher published an influential paper entitled The Powerful Placebo which proposed idea that placebo effects were clinically important. Subsequent re-analysis of his materials, however, found in them no evidence of any "placebo effect".
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Applied and Interdisciplinary Chemistry
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It is believed he became a naturalised English citizen in 1662. He was elected a Fellow of the Royal Society (FRS) on 20 May 1663.
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Applied and Interdisciplinary Chemistry
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Being a widely available reagent, TsCl has been heavily examined from the perspective of reactivity. It is used in dehydrations to make nitriles, isocyanides and diimides. In an unusual reaction focusing on the sulfur center, zinc reduces TsCl to the sulfinate, CHCHSONa.
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Theoretical and Fundamental Chemistry
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Transfer of genes makes possible the horizontal transfer of genes from one organism to another. Thus plants can receive genes from humans or algae or any other organism. This provides limitless opportunities in breeding crop plants.
| 1 |
Applied and Interdisciplinary Chemistry
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This effect is significantly less common in ceramics which are typically more resilient to chemical attack. Although phase changes are common in ceramics under stress these usually result in toughening rather than failure (see Zirconium dioxide). Recent studies have shown that the same driving force for this toughening mechanism can also enhance oxidation of reduced cerium oxide, resulting in slow crack growth and spontaneous failure of dense ceramic bodies.
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Applied and Interdisciplinary Chemistry
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Due to the similarity with polyketide synthases (PKS), many secondary metabolites are, in fact, fusions of NRPs and polyketides. In essence, this occurs when PK modules follow NRP modules, and vice versa. Although there is high degree of similarity between the Carrier (PCP/ACP) domains of both types of synthetases, the mechanism of condensation is different from a chemical standpoint:
* PKS, carbon-carbon bond formation through Claisen condensation reaction
* NRPs, the C domain catalyzes the amide bond formation between the amino acid it adds to the chain (on the PCP of one module) and the nascent peptide(on the PCP of the next module).
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Applied and Interdisciplinary Chemistry
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There are several ways to target integrase but strand transfer inhibition is the most intuitively obvious and readily pursued to date. Other targets include, for example, the protein domains beyond the active site of IN. The domains interact with viral or host DNA and are important for binding to the enzyme. It is possible to hamper functions of the enzyme by disrupting or removing these bindings. PIC is a multimeric protein structure inside the host cell, composed of both viral and host proteins. Integrase is a part of PICs viral component. PICs viral and host proteins are believed to modulate intrinsic activity of the enzyme, shuttle PIC to the nucleus and direct integration of viral DNA into a transcriptionally active region of the host genome. If it were possible to exclude certain proteins from the PIC it would block the ability of the virus to integrate into the host genome. The process where the retroviral RNA is transcribed to DNA and then integrated into the host cell's genome is shown in figure 2.
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Applied and Interdisciplinary Chemistry
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Different types of corrosion inhibitor exist. Among them, oxidizing species such as chromate () and nitrite () were the first used to re-establish the state of passivation in the protective oxide layer. In the specific case of steel, the cation being a relatively soluble species, it contributes to favor the dissolution of the oxide layer which so loses its passivity. To restore the passivity, the principle simply consists to prevent the dissolution of the oxide layer by converting the soluble divalent cation into the much less soluble trivalent cation. This approach is also at the basis of the chromate conversion coating used to passivate steel, aluminium, zinc, cadmium, copper, silver, titanium, magnesium, and tin alloys.
As hexavalent chromate is a known carcinogen, its aqueous effluents can no longer be freely discharged into the environment and its maximum concentration acceptable in water is very low.
Nitrite is also an oxidizing species and has been used as corrosion inhibitor since the 1950's.
Under the basic conditions prevailing in concrete pore water nitrite converts the relatively soluble ions into the much less soluble ions, and so protects the carbon-steel reinforcement bars by forming a new and denser layer of γ- as follows:
Corrosion inhibitors, when present in sufficient amount, can provide protection against pitting. However, too low level of them can aggravate pitting by forming local anodes.
| 1 |
Applied and Interdisciplinary Chemistry
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In 1995, Smith and his co-workers reported the second total synthesis of (-)-discodermolide. Smith adapted the triply convergent strategy of the Schreiber synthesis. In Smith's strategy, all three fragments shared a common precursor, which was the product of a highly efficient 50g scale five-step conversion from 3-hydroxy-2-methylpropionate with 59% yield. An Evans syn aldol reaction was utilized to obtain the desired stereochemical outcome.
The synthesis of fragment A, alkyl iodide, applied the Evans' acyl oxazolidinone method. After hydroxyl protection and reductive removal of the chiral auxiliary, an iodination was carried out to afford fragment A. The preparation of fragment B began with TBS protection and DIBAL reduction. The resulting aldehyde can be converted to desired Z-trisubstituted vinyl halide with 6:1 selectivity. The key feature of the synthesis of fragment C was the addition of the anion derived from dithiane to benzyl glycidyl ether.
Palladium(0)-mediated crosscoupling of vinyl iodide with the organozinc derivative of alkyl iodide afford product in 66% yield. After a two-step conversion to the corresponding phosphonium salt, Wittig union of phosphonium salt with aldehyde, fragment C, proceeded in 76% yield and good selectivity. The last feature of this synthesis was the titanium-mediated installation of the diene. The smith synthesis of (-)-discodermolide has an overall yield of 2.0% with a longest linear sequence of 29 steps and 42 total steps.
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Theoretical and Fundamental Chemistry
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Water vapor is the most important greenhouse gas overall, being responsible for 41–67% of the greenhouse effect, but its global concentrations are not directly affected by human activity. While local water vapor concentrations can be affected by developments such as irrigation, it has little impact on the global scale due to its short residence time of about nine days. Indirectly, an increase in global temperatures cause will also increase water vapor concentrations and thus their warming effect, in a process known as water vapor feedback. It occurs because Clausius–Clapeyron relation establishes that more water vapor will be present per unit volume at elevated temperatures. Thus, local atmospheric concentration of water vapor varies from less than 0.01% in extremely cold regions and up to 3% by mass in saturated air at about 32 °C.
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Applied and Interdisciplinary Chemistry
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Self-assembled rolled-up micro coils with diameters down to 50 µm have been developed for NMR microscopy.
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Theoretical and Fundamental Chemistry
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Tritium is an important fuel for controlled nuclear fusion in both magnetic confinement and inertial confinement fusion reactor designs. The National Ignition Facility (NIF) uses deuterium–tritium fuel, and the experimental fusion reactor ITER will also do so. The deuterium–tritium reaction is favorable since it has the largest fusion cross section (about 5.0 barns) and it reaches this maximum cross section at the lowest energy (about 65 keV center-of-mass) of any potential fusion fuel. As tritium is very rare on earth, concepts for fusion reactors often include the breeding of tritium. During the operation of envisioned breeder fusion reactors, Breeding blankets, often containing lithium as part of ceramic pebbles, are subjected to neutron fluxes to generate tritium to complete the fuel cycle.
The Tritium Systems Test Assembly (TSTA) was a facility at the Los Alamos National Laboratory dedicated to the development and demonstration of technologies required for fusion-relevant deuterium–tritium processing.
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Theoretical and Fundamental Chemistry
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Hydrolysis of DNA occurs at a significant rate in vivo. For example, it is estimated that in each human cell 2,000 to 10,000 DNA purine bases turn over every day due to hydrolytic depurination, and that this is largely counteracted by specific rapid DNA repair processes. Hydrolytic DNA damages that fail to be accurately repaired may contribute to carcinogenesis and ageing.
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Theoretical and Fundamental Chemistry
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In March 1951, the British Tabulating Machine Company (BTM) sent a team to Andrew Booths workshop. They then used his design to create the Hollerith Electronic Computer 1 (HEC 1) before the end of 1951. The computer was a direct copy of Andrew Booths circuits with extra Input/output interfaces. The HEC 2 was the HEC 1 with smarter metal casings and was built for the Business Efficiency Exhibition in 1953. A slightly modified version of the HEC 2 was then marketed as HEC2M and 8 were sold. The HEC2M was succeeded by the HEC4. Around 100 HEC4s were sold in the late 1950s.
The HEC used standard punched cards; the HEC 4 had a printer, too, and it featured several instructions (such as divide) and registers not found on the APEXC.
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Theoretical and Fundamental Chemistry
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Resin acids are protectants and wood preservatives that are produced by parenchymatous epithelial cells that surround the resin ducts in trees from temperate coniferous forests. The resin acids are formed when two-carbon and three-carbon molecules couple with isoprene building units to form monoterpenes (volatile), sesquiterpenes (volatile), and diterpenes (nonvolatile) structures.
Pines contain numerous vertical and radial resin ducts scattered throughout the entire wood. The accumulation of resin in the heartwood and resin ducts causes a maximum concentration in the base of the older trees. Resin in the sapwood, however, is less at the base of the tree and increases with height.
In 2005, as an infestation of the Mountain pine beetle (Dendroctonus ponderosae) and blue stain fungus devastated the Lodgepole Pine forests of northern interior British Columbia, Canada, resin acid levels three to four times greater than normal were detected in infected trees, prior to death. These increased levels show that a tree uses the resins as a defense. Resins are both toxic to the beetle and the fungus and also can entomb the beetle in diterpene remains from secretions. Increasing resin production has been proposed as a way to slow the spread of the beetle in the "Red Zone" or the wildlife urban interface.
| 1 |
Applied and Interdisciplinary Chemistry
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For steel, the first step will be the volatilization of the inhibitor into the airspace. This may entail simple evolution of the molecule or the chemical may dissociate first and then volatilize. The molecules will then diffuse through the enclosed airspace until some of the molecules reach the metallic surface to be protected. There are two likely paths once the molecules reach the metallic surface. First the molecule may adsorb onto the metal surface thereby forming a barrier to aggressive ions and displacing any condensed water.
The second path involves the condensed water layer that has been shown to exist on the metallic surface. The VCI molecules will dissolve into the condensed water layer, raising the pH. An alkaline pH has been shown to have a beneficial effect on the corrosion resistance for steel.
The mechanism for copper begins the same as for steel, evolution of the inhibitor. Once at the copper surface however, the inhibitor will form a copper benzotriazole complex which is protective.
Vapor pressure is critical parameter in VCI effectiveness. The most favorable range of pressure is 10 to 10 Pa at room temperature. Insufficient pressure leads to the slow establishment of the protective layer; if the pressure is too high, VCI effectiveness is limited to a short time.
| 1 |
Applied and Interdisciplinary Chemistry
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For each amino acid in a gene, the weight of each of its codons represented by a parameter termed relative adaptiveness (), is computed from a reference sequence set, as the ratio between the observed frequency of the codon and the frequency of the most frequent synonymous codon for that amino acid.
The CAI of a gene is simply defined as the geometric mean of the weight associated to each codon over the length () of the gene sequence (measured in codons).
| 1 |
Applied and Interdisciplinary Chemistry
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The salt balances are calculated for each reservoir separately. They are based on their water balances, using the salt concentrations of the incoming and outgoing water. Some concentrations must be given as input data, like the initial salt concentrations of the water in the different soil reservoirs, of the irrigation water and of the incoming ground water in the aquifer.
The concentrations are expressed in terms of electric conductivity (EC in dS/m). When the concentrations are known in terms of g salt/L water, the rule of thumb: 1 g/L -> 1.7 dS/m can be used. Usually, salt concentrations of the soil are expressed in ECe, the electric conductivity of an extract of a saturated soil paste (saturation extract). In Saltmod, the salt concentration is expressed as the EC of the soil moisture when saturated under field conditions. As a rule, one can use the conversion rate EC : ECe = 2 : 1.<br>
Salt concentrations of outgoing water (either from one reservoir into the other or by subsurface drainage) are computed on the basis of salt balances, using different leaching or salt mixing efficiencies to be given with the input data. The effects of different leaching efficiencies can be simulated by varying their input value.
If drain or well water is used for irrigation, the method computes the salt concentration of the mixed irrigation water in the course of the time and the subsequent effect on the soil and ground water salinities, which again influences the salt concentration of the drain and well water. By varying the fraction of used drain or well water (to be given in the input data), the long-term effect of different fractions can be simulated.
The dissolution of solid soil minerals or the chemical precipitation of poorly soluble salts is not included in the computation method, but to some extent it can be accounted for through the input data, e.g. by increasing or decreasing the salt concentration of the irrigation water or of the incoming water in the aquifer.
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Theoretical and Fundamental Chemistry
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In addition to RNA, proteins can undergo splicing. Although the biomolecular mechanisms are different, the principle is the same: parts of the protein, called inteins instead of introns, are removed. The remaining parts, called exteins instead of exons, are fused together.
Protein splicing has been observed in a wide range of organisms, including bacteria, archaea, plants, yeast and humans.
| 1 |
Applied and Interdisciplinary Chemistry
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Liquid is the primary component of hydraulic systems, which take advantage of Pascal's law to provide fluid power. Devices such as pumps and waterwheels have been used to change liquid motion into mechanical work since ancient times. Oils are forced through hydraulic pumps, which transmit this force to hydraulic cylinders. Hydraulics can be found in many applications, such as automotive brakes and transmissions, heavy equipment, and airplane control systems. Various hydraulic presses are used extensively in repair and manufacturing, for lifting, pressing, clamping and forming.
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Theoretical and Fundamental Chemistry
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Laser Doppler velocimetry can be useful in automation, which includes the flow examples above. It can also be used to measure the speed of solid objects, like conveyor belts. This can be useful in situations where attaching a rotary encoder (or a different mechanical speed measurement device) to the conveyor belt is impossible or impractical.
| 1 |
Applied and Interdisciplinary Chemistry
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The development, differentiation and growth of cells and tissues require precisely regulated patterns of gene expression. Enhancers work as cis-regulatory elements to mediate both spatial and temporal control of development by turning on transcription in specific cells and/or repressing it in other cells. Thus, the particular combination of transcription factors and other DNA-binding proteins in a developing tissue controls which genes will be expressed in that tissue. Enhancers allow the same gene to be used in diverse processes in space and time.
| 1 |
Applied and Interdisciplinary Chemistry
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In fluid dynamics, aerodynamic potential flow codes or panel codes are used to determine the fluid velocity, and subsequently the pressure distribution, on an object. This may be a simple two-dimensional object, such as a circle or wing, or it may be a three-dimensional vehicle.
A series of singularities as sources, sinks, vortex points and doublets are used to model the panels and wakes. These codes may be valid at subsonic and supersonic speeds.
| 1 |
Applied and Interdisciplinary Chemistry
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High performance liquid chromatography (HPLC) and electron ionization mass spectrometry (EIMS) are two analytical techniques that, in principle, seem to be incompatible. However, because these two approaches share a great deal of applications in the analysis of suitable molecules, typically less than 1000 u, a large effort has been devoted by the scientific community to develop a reliable, easy-to-use, and flawless interface. The first successful and commercially available device to combine EI and HPLC was designed by Willoughby and Browner in 1984. It was based on the conversion of the solute into a beam of particles, after the formation of spray droplets and the elimination of the solvent vapors through a multi-stage momentum separator. Although its efficient interfacing mechanism and a unique trait, particle beam performance was sometimes inadequate to an increasing number of new, demanding applications and was quickly replaced by a family of atmospheric pressure ionization-based interfaces (API) when they became commercially available. However, the possibility to record an EI spectrum from an HPLC application remained a challenge for a long time. The first Direct-EI prototype was first presented in 2002 and proposed an innovative approach that improved interfacing performance compared to that of particle beam and opened new opportunities for LC-MS applications.
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Theoretical and Fundamental Chemistry
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The search for antifungal agents with acceptable toxicity profiles led first to the discovery of ketoconazole, the first azole-based oral treatment of systemic fungal infections, in the early 1980s. Later, triazoles fluconazole and itraconazole, with a broader spectrum of antifungal activity and improved safety profile were developed. In order to overcome limitations such as sub-optimal spectra of activity, drug-drug interactions, toxicity, development of resistance and unfavorable pharmacokinetics, analogues were developed. Second-generation triazoles, including voriconazole, posaconazole and ravuconazole, are more potent and more active against resistant pathogens.
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Theoretical and Fundamental Chemistry
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Approval by an Institutional Review Board (IRB), or Independent Ethics Committee (IEC), is necessary before all but the most informal research can begin. In commercial clinical trials, the study protocol is not approved by an IRB before the sponsor recruits sites to conduct the trial. However, the study protocol and procedures have been tailored to fit generic IRB submission requirements. In this case, and where there is no independent sponsor, each local site investigator submits the study protocol, the consent(s), the data collection forms, and supporting documentation to the local IRB. Universities and most hospitals have in-house IRBs. Other researchers (such as in walk-in clinics) use independent IRBs.
The IRB scrutinizes the study both for medical safety and for protection of the patients involved in the study, before it allows the researcher to begin the study. It may require changes in study procedures or in the explanations given to the patient. A required yearly "continuing review" report from the investigator updates the IRB on the progress of the study and any new safety information related to the study.
| 1 |
Applied and Interdisciplinary Chemistry
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Many glycan binding proteins (GBPs) are oligomeric and typically contain multiple sites for glycan binding (also called carbohydrate-recognition domains). The ability to form multivalent protein-ligand interactions significantly enhances the strength of binding: while values for individual CRD-glycan interactions may be in the mM range, the overall affinity of GBP towards glycans may reach nanomolar or even picomolar ranges. The overall strength of interactions is described as avidity (in contrast with an affinity which describes single equilibrium). Sometimes the avidity is also called an apparent to emphasize the non-equilibrium nature of the interaction.
Common oligomerization structures of lectins are shown below. For example, galectins are usually observed as dimers, while intelectins form trimers and pentraxins assemble into pentamers. Larger structures, like hexameric Reg proteins, may assemble into membrane penetrating pores. Collectins may form even more bizarre complexes: bouquets of trimers or even cruciform-like structures (e.g. in SP-D).
| 1 |
Applied and Interdisciplinary Chemistry
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The Stark effect is the shifting and splitting of spectral lines of atoms and molecules due to the presence of an external electric field. It is the electric-field analogue of the Zeeman effect, where a spectral line is split into several components due to the presence of the magnetic field. Although initially coined for the static case, it is also used in the wider context to describe the effect of time-dependent electric fields. In particular, the Stark effect is responsible for the pressure broadening (Stark broadening) of spectral lines by charged particles in plasmas. For most spectral lines, the Stark effect is either linear (proportional to the applied electric field) or quadratic with a high accuracy.
The Stark effect can be observed both for emission and absorption lines. The latter is sometimes called the inverse Stark effect, but this term is no longer used in the modern literature.
| 0 |
Theoretical and Fundamental Chemistry
|
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