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The mean wall shear stress in a pipe or open channel is expressed in terms of the Darcy–Weisbach friction factor as
The wall shear stress has the SI unit of pascals (Pa). | 1 | Applied and Interdisciplinary Chemistry |
Standards and handbooks are mainly concerned with plates. In these, the leading edge is sharp and free of burrs and the cylindrical section of the orifice is short, either because the entire plate is thin or because the downstream edge of the plate is bevelled. Exceptions include the or orifice, which has a fully rounded leading edge and no cylindrical section, and the or plate which has a bevelled leading edge and a very short cylindrical section. The orifices are normally concentric with the pipe (the orifice is a specific exception) and circular (except in the specific case of the or orifice, in which the plate obstructs just a segment of the pipe). Standards and handbooks stipulate that the upstream surface of the plate is particularly flat and smooth. Sometimes a small drain or vent hole is drilled through the plate where it meets the pipe, to allow condensate or gas bubbles to pass along the pipe. | 1 | Applied and Interdisciplinary Chemistry |
The isolobal analogy can also be used with isoelectronic fragments having the same coordination number, which allows charged species to be considered. For example, Re(CO) is isolobal with CH and therefore, [Ru(CO)] and [Mo(CO)] are also isolobal with CH. Any 17-electron metal complex would be isolobal in this example.
In a similar sense, the addition or removal of electrons from two isolobal fragments results in two new isolobal fragments. Since Re(CO) is isolobal with CH, [Re(CO)] is isolobal with . | 0 | Theoretical and Fundamental Chemistry |
* Stalin Prize first degree (1943) - for research in the field of organometallic compounds, the results of which were published in 1941 and 1942 in a series of articles: “On the interaction of diazoacetic ether with tin chloride and ferric chloride”, “From the field of organomercuric compounds ”, “On the reaction of nitroso compounds with nitric oxide” and in the monograph “Synthetic methods in the field of organometallic compounds of mercury” (1942)
* Lenin Prize (1966) - for a cycle of research in the field of organoelement compounds
* Twice Hero of Socialist Labour (1969, 1979)
* Gold medal named after D. I. Mendeleev (1977) - for a series of works in the field of organometallic compounds and obtaining food from non-traditional sources
* V Mendeleev Reader
* Large Gold Medal named after M. V. Lomonosov Academy of Sciences of the Soviet Union (1962)
* Seven Orders of Lenin (11/04/1944; 06/10/1945; 09/19/1953; 09/08/1959; 04/27/1967; 03/13/1969; 09/07/1979)
* Order of the October Revolution (09/13/1974)
* Order of the Red Banner of Labour (09/14/1949)
* Silver medal of the World Peace Council (1959) | 0 | Theoretical and Fundamental Chemistry |
Thorium has been linked to liver cancer. In the past, thoria (thorium dioxide) was used as a contrast agent for medical X-ray radiography but its use has been discontinued. It was sold under the name Thorotrast. | 0 | Theoretical and Fundamental Chemistry |
A carbamoyl chloride is the functional group with the formula RNC(O)Cl. The parent carbamoyl chloride, HNCOCl is unstable, but many N-substituted analogues are known. Most examples are moisture sensitive, colourless, and soluble in nonpolar organic solvents. An example is dimethylcarbamoyl chloride (m.p. −90 °C and b.p. 93 °C). Carbamoyl chlorides are used to prepare a number of pesticides, e.g. carbofuran and aldicarb. | 0 | Theoretical and Fundamental Chemistry |
The term tephrochronology appears to have been used by Sigurdur Thórarinsson as early as 1944. A key point in the establishment of this scientific field of study with what evolved to be a unique geoscientific method was in 1961 after a proposal supported by him led by Japanese researchers including Professor Kunio Kobayashi resulted in the establishment of an international scientific group. Much work had preceded this, but was limited by the techniques available at the time in geology. This had resulted in tephra formations not being linked and inaccurate timings that could not be related to events say with worldwide traces.
What would now be known as cryptotephra studies occurred in sea floor samples in the 1940s but Christer Persson in Scandinavia, was the first to publish articles in this field in the 1960s. Andrew Dugmore in 1989 was the first to use modern systematic methodology. Since then researchers have targeted stratigraphic archives of peat, lake sediment, ice cores, marine sediments, loess, floors of caves and rock shelters or stalagmites as well as contemporary eruption deposits.
Early tephra horizons were identified with the Saksunarvatn tephra (Icelandic origin, cal. ka BP), forming a horizon in the late Pre-Boreal of Northern Europe, the Vedde ash (also Icelandic in origin, c. 12.0 cal. ka BP) and the Laacher See tephra (in the Eifel volcanic field, c. 12.9 cal. ka BP). Major volcanoes which have been used in tephrochronological studies include Vesuvius, Hekla and Santorini. Minor volcanic events may also leave their fingerprint in the geological record: Hayes Volcano is responsible for a series of six major tephra layers in the Cook Inlet region of Alaska. Tephra horizons provide a synchronous check against which to correlate the palaeoclimatic reconstructions that are obtained from terrestrial records, like fossil pollen studies (palynology), from varves in lake sediments or from marine deposits and ice-core records, and to extend the limits of carbon-14 dating.
A pioneer in the use of tephra layers as marker horizons to establish chronology was Sigurdur Thorarinsson, who began by studying the layers he found in his native Iceland. Since the late 1990s, techniques developed by Chris S. M. Turney (QUB, Belfast; now University of Exeter) and others for extracting tephra horizons invisible to the naked eye ("cryptotephra") have revolutionised the application of tephrochronology. This technique relies upon the difference between the specific gravity of the microtephra shards and the host sediment matrix. It has led to the first discovery of the Vedde ash on the mainland of Britain, in Sweden, in the Netherlands, in the Swiss Lake Soppensee and in two sites on the Karelian Isthmus of Baltic Russia.
It has also revealed previously undetected ash layers, such as the Borrobol Tephra first discovered in northern Scotland, dated to c. 14.4 cal. ka BP, the microtephra horizons of equivalent geochemistry from southern Sweden, dated at 13,900 Cariaco varve yrs BP and from northwest Scotland, dated at 13.6 cal. ka BP.
Since 2010 Bayesian age modelling built around ever-improving 14C-calibration curves and other age-related data,such as zircon double dating continues to better define tephrochronology. | 0 | Theoretical and Fundamental Chemistry |
When considering wind effects on dynamically sensitive structures such as suspension bridges it is sometimes necessary to simulate the combined effect of the vibrating mass of the structure with the fluctuating force of the wind. In such cases, the Froude number should be respected.
Similarly, when simulating hot smoke plumes combined with natural wind, Froude number scaling is necessary to maintain the correct balance between buoyancy forces and the momentum of the wind. | 1 | Applied and Interdisciplinary Chemistry |
Many coastal mosses were initiated by the process of glaciation, which sheared rock formations to a generally level terrain, while also gouging moderate sized craters that would pond. This description fits the fundamental situation of Portlethen Moss, where sphagnum would have flourished over millennia of evaporation, further intensifying the soil acidity, fueled by organic matter decaying, with little drainage outlet. A layer of sphagnum moss would have developed at the benthic level of the bog, and additional sphagnum layers floated in mats atop the bog.
At an intermediate level of evolution, thick peat layers formed from decay and carbonisation of the rotting sphagnum. Generations of Carex and Juncus flourished, leading to further decay of these materials and eventual heightening of the organic mass. Finally, secondary vegetation took root in the spongy sphagnum mats adding greater biomass to the bog. In some cases the heavy saturated organic layers could actually rupture, spilling large volumes of mud and organic debris to surrounding fields, thus enabling a bed for further spatial expansion of the entire bog. Ultimately the colour of the moss waters became blood red, from the successive organic decay and stagnation. Only in times associated with cattle grazing and significant human presence (probably the late Iron Age), would this process reverse and the bog reduce in size. | 1 | Applied and Interdisciplinary Chemistry |
Losartan, valsartan, candesartan, irbesartan, telmisartan and olmesartan all contain a biphenyl-methyl group.
Losartan is partly metabolized to its 5-carboxylic acid metabolite EXP 3174, which is a more potent AT receptor antagonist than its parent compound
and has been a model for the continuing development of several other ARBs.
Valsartan, candesartan and irbesartan were all developed in 1990.
Valsartan, first marketed by Novartis, is a nonheterocyclic ARB, where the imidazole of losartan has been replaced by an acylated amino acid.
Irbesartan was developed by Sanofi Research and is longer acting than valsartan and losartan and it has an imidazolinone ring where a carbonyl group functions as a hydrogen bond acceptor instead of the hydroxymethyl group in losartan. Irbesartan is a non-competitive inhibitor.
Candesartan cilexetil (TCV 116) is a benzimidazole which was developed at Takeda and is an ester carbonate prodrug. In vivo, it is rapidly converted to the much more potent corresponding 7-carboxylic acid, candesartan. In the interaction of candesartan with AT receptor the carboxyl group of the benzimidazole ring plays an important role. Candesartan and its prodrug have stronger blood pressure lowering effects than EXP 3174 and losartan.
Telmisartan, which was discovered and developed in 1991 by Boehringer Ingelheim, has carboxylic acid as the biphenyl acidic group. It has the longest elimination half-life of the ARBs or about 24 hours.
Olmesartan medoxomil was developed by Sankyo in 1995 and is the newest ARB on the market, marketed in 2002. It is an ester prodrug like candesartan cilexetil. In vivo, the prodrug is completely and rapidly hydrolyzed to the active acid form, olmesartan (RNH-6270). It has a hydroxyisopropyl group connected to the imidazole ring in addition to the carboxyl group. | 1 | Applied and Interdisciplinary Chemistry |
* Superelastic nitinol finds a variety of applications in civil structures such as bridges and buildings. One such application is Intelligent Reinforced Concrete (IRC), which incorporates NiTi wires embedded within the concrete. These wires can sense cracks and contract to heal macro-sized cracks.
* Another application is active tuning of structural natural frequency using nitinol wires to damp vibrations. | 1 | Applied and Interdisciplinary Chemistry |
The process of casting in bronze and brass is known as cire perdue, and is the most primitive and most commonly employed through the centuries, having been described in by the monk Theophilus, and also by Benvenuto Cellini. Briefly, it is as follows: a core, roughly representing the size and form of the object to be produced, is made of pounded brick, plaster or other similar substance and thoroughly dried. Upon this the artist overlays his wax, which he models to the degree required in his finished work. Passing from the core through the wax and projecting beyond are metal rods. The modelling being completed, called lost-wax casting, the outer covering which will form the mould has to be applied; this is a liquid formed of clay and plaster sufficiently thin to find its way into every detail of the wax model. Further coatings of liquid are applied, so that there is, when dry, a solid outer coating and a solid inner core held together by the metal rods, with the work of art modelled in wax between. Heat is applied and the wax melts and runs out, and the molten metal is poured in and occupies every detail which the wax had filled. When cool, the outer casing is carefully broken away, the core raked out as far as possible, the projecting rods are removed and the object modelled in wax appears in bronze. If further finish is required, it is obtained by tooling. | 1 | Applied and Interdisciplinary Chemistry |
PB-1 is used in pressure piping systems for hot and cold potable water, pre-insulated district heating networks, and surface heating and cooling systems. Key properties are weldability, temperature resistance, flexibility and high hydrostatic pressure resistance. One standard type, PB 125, has a minimum required strength (MRS) of 12.5 MPa. It also has low noise transmission, low linear thermal expansion, no corrosion and calcification.
PB-1 piping systems are no longer sold in North America. Market share in Europe and Asia is small but steadily growing. In some markets, e.g. Kuwait, UK, Korea and Spain, PB-1 has a strong position. | 1 | Applied and Interdisciplinary Chemistry |
Reticular synthesis was used by Yaghi and coworkers in 2005 to construct the first two COFs reported in the literature: COF-1, using a dehydration reaction of benzenediboronic acid (BDBA), and COF-5, via a condensation reaction between hexahydroxytriphenylene (HHTP) and BDBA. These framework scaffolds were interconnected through the formation of boroxine and boronate linkages, respectively, using solvothermal synthetic methods. | 0 | Theoretical and Fundamental Chemistry |
Increase in temperature shifts the oxygen dissociation curve to the right. When temperature is increased keeping the oxygen concentration constant, oxygen saturation decreases as the bond between oxygen and iron gets denatured. Additionally, with increased temperature, the partial pressure of oxygen increases as well. So, one will have a lesser amount of hemoglobin saturated for the same oxygen concentration but at a higher partial pressure of oxygen. Thus, any point in the curve will shift rightwards (due to increased partial pressure of oxygen) and downwards (due to weakened bond), hence, the rightward shift of the curve. | 1 | Applied and Interdisciplinary Chemistry |
Iminium derivatives are common in biology. Pyridoxal phosphate reacts with amino acids to give iminium derivatives. Many iminium salts are encountered in synthetic organic chemistry. | 0 | Theoretical and Fundamental Chemistry |
2 Laboratories:
*LCPM: Laboratoire de Chimie Physique des Réactions (Polymer Science and Macromolecular Physical Chemistry)
*LRGP : Laboratoire de Réactions et Génie des Procédés | 1 | Applied and Interdisciplinary Chemistry |
Within statistical mechanics, inexact differentials are often denoted with a bar through the differential operator, đ. In LaTeX the command "\rlap{\textrm{d}}{\bar{\phantom{w}}}" is an approximation or simply "\dj" for a dyet character, which needs the T1 encoding. | 0 | Theoretical and Fundamental Chemistry |
Enzyme mimic (or Artificial enzyme) is a branch of biomimetic chemistry, which aims at imitating the function of natural enzymes. An enzyme mimic is a small molecule complex that models the molecular structure, spectroscopic properties, or reactivity of an enzyme, sometimes called bioinspired complexes. | 0 | Theoretical and Fundamental Chemistry |
The Science Based Targets initiative was established in 2015 to help companies to set emission reduction targets in line with climate sciences and Paris Agreement goals. It is funded by IKEA Foundation, Amazon, Bezos Earth Fund, We Mean Business coalition, Rockefeller Brothers Fund and UPS Foundation. In October 2021, SBTi developed and launched the worlds first net zero standard, providing the framework and tools for companies to set science-based net zero targets and limit global temperature rise above pre-industrial levels to 1.5 °C. Best practice as identified by SBTi is for companies to adopt transition plans covering scope 1, 2 and 3 emissions, set out short-term milestones, ensure effective board-level governance and link executive compensation to the companys adopted milestones. | 1 | Applied and Interdisciplinary Chemistry |
For smaller, mesoscopic, systems (for example, with only thousands of particles), the ground state term can be more explicitly approximated by adding in an actual discrete level at energy ε=0 in the grand potential:
which gives instead . Now, the behaviour is smooth when crossing the critical temperature, and z approaches 1 very closely but does not reach it.
This can now be solved down to absolute zero in temperature. Figure 1 shows the results of the solution to this equation for α=3/2, with k=ε=1 which corresponds to a gas of bosons in a box. The solid black line is the fraction of excited states 1-N/N for N =10,000 and the dotted black line is the solution for N =1000. The blue lines are the fraction of condensed particles N/N The red lines plot values of the
negative of the chemical potential μ and the green lines plot the corresponding values of z . The horizontal axis is the normalized temperature τ defined by
It can be seen that each of these parameters become linear in τ in the limit of low temperature and, except for the chemical potential, linear in 1/τ in the limit of high temperature. As the number of particles increases, the condensed and excited fractions tend towards a discontinuity at the critical temperature.
The equation for the number of particles can be written in terms of the normalized temperature as:
For a given N and τ, this equation can be solved for τ and then a series solution for z can be found by the method of inversion of series, either in powers of τ or as an asymptotic expansion in inverse powers of τ. From these expansions, we can find the behavior of the gas near T =0 and in the Maxwell–Boltzmann as T approaches infinity. In particular, we are interested in the limit as N approaches infinity, which can be easily determined from these expansions.
This approach to modelling small systems may in fact be unrealistic, however, since the variance in the number of particles in the ground state is very large, equal to the number of particles. In contrast, the variance of particle number in a normal gas is only the square-root of the particle number, which is why it can normally be ignored. This high variance is due to the choice of using the grand canonical ensemble for the entire system, including the condensate state. | 0 | Theoretical and Fundamental Chemistry |
Where the high temperatures and sources of ignition required by hot cutting are not desirable, air- or hydraulically-powered pipe cutting machines are used. These comprise a clamshell or chain-mounted cutting head holding a tool steel and feed mechanism which advances the tool a set amount per revolution round the pipe. Tools may be styled to cut and/or prepare the bevel for welding in a single or multiple passes.
Popular in offshore, pipe processing, ship building, pressure vessel, structural and mechanical contracting manufacturing because of the complex cuts and profiles typical required in their respective industries. Some common pipe cutting applications are: pipe work, offshore jackets, industrial steel structures, stadiums, cranes, nozzles, and pipe laying stingers. | 1 | Applied and Interdisciplinary Chemistry |
In physics, a Fano resonance is a type of resonant scattering phenomenon that gives rise to an asymmetric line-shape. Interference between a background and a resonant scattering process produces the asymmetric line-shape. It is named after Italian-American physicist Ugo Fano, who in 1961 gave a theoretical explanation for the scattering line-shape of inelastic scattering of electrons from helium; however, Ettore Majorana was the first to discover this phenomenon. Fano resonance is a weak coupling effect meaning that the decay rate is so high, that no hybridization occurs. The coupling modifies the resonance properties such as spectral position and width and its line-shape takes on the distinctive asymmetric Fano profile. Because it is a general wave phenomenon, examples can be found across many areas of physics and engineering. | 0 | Theoretical and Fundamental Chemistry |
Indicators that make the human impact measurable and quantitatively assessable are: artificial water surface ratio, artificial water surface density ratio, disruption of longitudinal connectivity ratio, artificial river ratio, sinuosity of artificial cutoff, channelization ratio, artificial levee ratio, road along river ratio, artificial sediment transport ratio and the integrated river structure impact index. | 1 | Applied and Interdisciplinary Chemistry |
nanorod polymers were isolated from CuI-P complexes using low temperature treatment.
Red/brown phosphorus was shown to be stable in air for several weeks and have properties distinct from those of red phosphorus. Electron microscopy showed that red/brown phosphorus forms long, parallel nanorods with a diameter between 3.4 Å and 4.7 Å. | 0 | Theoretical and Fundamental Chemistry |
Anti-Ro/SSA can target Ro52 and Ro60 proteins. Most Anti-Ro/SSA activity occurs on the cell surface, wherein Ro proteins are expressed on the cell membrane and extracellular Anti-Ro/SSAs bind to Ro. There is some evidence that the IgG isotype of anti-Ro/SSA antibody can enter the cell.
* Anti-Ro autoantibodies are typically IgA, IgM, and IgG isotypes, though most is known about the five IgG subclasses. The antibody is inducible via immunization using Ro peptide.
The mechanism that induces Anti-Ro/SSA production in autoimmune disorders remains under study. Some proposed factors that may stimulate production are viral infection, treatment of cells with TNF-α, cellular apoptosis, and exposure to UV irradiation.
* Anti-Ro/SSA is produced in the cytoplasm of cells in the epidermal layer of the skin following UV irradiation. Ro antigens are simultaneously upregulated on the cell surface, resulting in the Anti-Ro/SSA antibody marking cells for destruction. Anti-Ro52 antibodies in particular have been tied to elevated photosensitivity.
Certain alleles of the human major histocompatibility complex (MHC II, called HLA II in humans) have been associated with the presence of Anti-Ro antibodies and the spread of the immune response. Anti-Ro/SSA associates with the HLA II alleles HLA-DR3 and HLA-DR2, as well as some HLA-DQ alleles. The T-cell response plays a role in the formation of Anti-Ro/SSA antibodies due to T-cell affinity for MHC class II. | 1 | Applied and Interdisciplinary Chemistry |
Selectfluor is synthesized by the N-alkylation of [[DABCO|diazabicyclo[2.2.2]octane (DABCO)]] with dichloromethane, followed by ion exchange with sodium tetrafluoroborate (replacing the chloride counterion for the tetrafluoroborate). The resulting salt is treated with elemental fluorine and sodium tetrafluoroborate:
The cation is often depicted with one skewed ethylene ((CH)) group. In fact, these pairs of CH groups are eclipsed so that the cation has idealized C symmetry. | 0 | Theoretical and Fundamental Chemistry |
In the early days, chromosome walking from genetically linked DNA markers was used to identify and clone disease genes. However, the large molecular distance between known markers and the gene of interest was complicating the cloning process. In 1987, a human chromosome jumping library was constructed to clone the cystic fibrosis gene. Cystic fibrosis is an autosomal recessive disease affecting 1 in 2000 Caucasians. This was the first disease in which the usefulness of the jumping libraries was demonstrated. Met oncogene was a marker tightly linked to the cystic fibrosis gene on human chromosome 7, and the library was screened for a jumping clone starting at this marker. The cystic fibrosis gene was determined to localize 240kb downstream of the met gene. Chromosome jumping helped reduce the mapping "steps" and bypass the highly repetitive regions in the mammalian genome. Chromosome jumping also allowed the production of probes required for faster diagnosis of this and other diseases. | 1 | Applied and Interdisciplinary Chemistry |
In the 1960s and 1970s, GFP, along with the separate luminescent protein aequorin (an enzyme that catalyzes the breakdown of luciferin, releasing light), was first purified from the jellyfish Aequorea victoria and its properties studied by Osamu Shimomura. In A. victoria, GFP fluorescence occurs when aequorin interacts with Ca ions, inducing a blue glow. Some of this luminescent energy is transferred to the GFP, shifting the overall color towards green. However, its utility as a tool for molecular biologists did not begin to be realized until 1992 when Douglas Prasher reported the cloning and nucleotide sequence of wtGFP in Gene. The funding for this project had run out, so Prasher sent cDNA samples to several labs. The lab of Martin Chalfie expressed the coding sequence of wtGFP, with the first few amino acids deleted, in heterologous cells of E. coli and C. elegans, publishing the results in Science in 1994. Frederick Tsuji's lab independently reported the expression of the recombinant protein one month later. Remarkably, the GFP molecule folded and was fluorescent at room temperature, without the need for exogenous cofactors specific to the jellyfish. Although this near-wtGFP was fluorescent, it had several drawbacks, including dual peaked excitation spectra, pH sensitivity, chloride sensitivity, poor fluorescence quantum yield, poor photostability and poor folding at .
The first reported crystal structure of a GFP was that of the S65T mutant by the Remington group in Science in 1996. One month later, the Phillips group independently reported the wild-type GFP structure in Nature Biotechnology. These crystal structures provided vital background on chromophore formation and neighboring residue interactions. Researchers have modified these residues by directed and random mutagenesis to produce the wide variety of GFP derivatives in use today. Further research into GFP has shown that it is resistant to detergents, proteases, guanidinium chloride (GdmCl) treatments, and drastic temperature changes. | 1 | Applied and Interdisciplinary Chemistry |
Imbibition is a special type of diffusion that takes place when liquid is absorbed by solids-colloids causing an increase in volume. Water surface potential movement takes place along a concentration gradient; some dry materials absorb water. A gradient between the absorbent and the liquid is essential for imbibition. For a substance to imbibe a liquid, there must first be some attraction between them. Imbibition occurs when a wetting fluid displaces a non-wetting fluid, the opposite of drainage in which a non-wetting phase displaces the wetting fluid. The two processes are governed by different mechanisms. Imbibition is also a type of diffusion since water movement is along the concentration gradient. Seeds and other such materials have almost no water hence they absorb water easily. Water potential gradient between the absorbent and liquid imbibed is essential for imbibition. | 0 | Theoretical and Fundamental Chemistry |
AR-BD1 (also known as HxAR) is expressed by Halorubrum xinjiangense. The organism was first isolated from Xiao-Er-Kule Lake in Xinjiang, China. | 0 | Theoretical and Fundamental Chemistry |
The injection valve is a motorized valve which links the mixer and sample loop to the column. Typically the valve has three positions for loading the sample loop, for injecting the sample from the loop into the column, and for connecting the pumps directly to the waste line to wash them or change buffer solutions. The injection valve has a sample loading port through which the sample can be loaded into the injection loop, usually from a hypodermic syringe using a Luer-lock connection. | 0 | Theoretical and Fundamental Chemistry |
The thermodynamic limit is essentially a consequence of the central limit theorem of probability theory. The internal energy of a gas of N molecules is the sum of order N contributions, each of which is approximately independent, and so the central limit theorem predicts that the ratio of the size of the fluctuations to the mean is of order 1/N. Thus for a macroscopic volume with perhaps the Avogadro number of molecules, fluctuations are negligible, and so thermodynamics works. In general, almost all macroscopic volumes of gases, liquids and solids can be treated as being in the thermodynamic limit.
For small microscopic systems, different statistical ensembles (microcanonical, canonical, grand canonical) permit different behaviours. For example, in the canonical ensemble the number of particles inside the system is held fixed, whereas particle number can fluctuate in the grand canonical ensemble. In the thermodynamic limit, these global fluctuations cease to be important.
It is at the thermodynamic limit that the additivity property of macroscopic extensive variables is obeyed. That is, the entropy of two systems or objects taken together (in addition to their energy and volume) is the sum of the two separate values. In some models of statistical mechanics, the thermodynamic limit exists, but depends on boundary conditions. For example, this happens in six vertex model: the bulk free energy is different for periodic boundary conditions and for domain wall boundary conditions. | 0 | Theoretical and Fundamental Chemistry |
Optical contact bonding is a glueless process whereby two closely conformal surfaces are joined, being held purely by intermolecular forces. | 0 | Theoretical and Fundamental Chemistry |
SedDB was developed, operated and maintained by a joint team of disciplinary scientists, data scientists, data managers and information technology developers at the Lamont–Doherty Earth Observatory as part of the Integrated Earth Data Applications ([http://www.iedadata.org/ IEDA]) Research Group funded by the US National Science Foundation. SedDB was built collaboratively by researchers and information technologists at the Lamont–Doherty Earth Observatory, Oregon State University, Boston University, and Boise State University. | 0 | Theoretical and Fundamental Chemistry |
French chemists Jean-Baptiste Dumas and Eugene Peligot, after determining methanols chemical structure, introduced "methylene" from the Greek methy "wine" and hȳlē' "wood, patch of trees" with the intention of highlighting its origins, "alcohol made from wood (substance)". The term "methyl" was derived in about 1840 by back-formation from "methylene", and was then applied to describe "methyl alcohol" (which since 1892 is called "methanol").
Methyl is the IUPAC nomenclature of organic chemistry term for an alkane (or alkyl) molecule, using the prefix "meth-" to indicate the presence of a single carbon. | 0 | Theoretical and Fundamental Chemistry |
When molecules or atoms come in contact with a surface, they adsorb onto it, minimizing their energy by forming a bond with the surface. The binding energy varies with the combination of the adsorbate and surface. If the surface is heated, at one point, the energy transferred to the adsorbed species will cause it to desorb. The temperature at which this happens is known as the desorption temperature. Thus TPD shows information on the binding energy. | 0 | Theoretical and Fundamental Chemistry |
The colored bubble solution uses special dyes called leuco dyes. For instance, the purple bubble uses a chemical called crystal violet lactone. After the bubble pops, the colored splatter disappears with friction, water or exposure to air.
In a normal soap bubble, surfactants reduce the surface tension of the water and allow the bubble to form. To create a colored bubble, dye molecules must bond to the surfactants. Each dye molecule in Zubbles is a structure known as a lactone ring. When the ring is closed, the molecule absorbs all visible light except for the color of the bubble. However, subjecting the lactone ring to air, water, or pressure causes the ring to open. This changes the molecule's structure to a straight chain which absorbs no visible light.
Lactone rings can be produced whenever a long chain molecule contains acid functionality on one end, and alcohol functionality at the other. The two ends of the molecule react in a condensation reaction, ejecting a water molecule. To drive the reaction back towards the long chain, pressure, heat or an excess of water must be added. | 0 | Theoretical and Fundamental Chemistry |
NASA used additive manufacturing to synthesize an alloy they termed GRX-810, which survived temperatures over . The alloy also featured improved strength, malleability, and durability. The printer dispersed oxide particles uniformly throughout the metal matrix. The alloy was identified using 30 simulations of thermodynamic modeling. | 1 | Applied and Interdisciplinary Chemistry |
A feature of the LHPG technique is its high convection speed in the liquid phase due to Marangoni convection. It is possible to see that it spins very fast. Even when it appears to be standing still, it is in fact spinning fast on its axis. | 0 | Theoretical and Fundamental Chemistry |
Sphere packing in a cylinder is a three-dimensional packing problem with the objective of packing a given number of identical spheres inside a cylinder of specified diameter and length. For cylinders with diameters on the same order of magnitude as the spheres, such packings result in what are called columnar structures.
These problems are studied extensively in the context of biology, nanoscience, materials science, and so forth due to the analogous assembly of small particles (like cells and atoms) into cylindrical crystalline structures.
The book "Columnar Structures of Spheres: Fundamentals and Applications" serves as a notable contributions to this field of study. Authored by Winkelmann and Chan, the book reviews theoretical foundations and practical applications of densely packed spheres within cylindrical confinements. | 0 | Theoretical and Fundamental Chemistry |
* Hoerr, John P. And the Wolf Finally Came: The Decline of the American Steel Industry (1988) [https://www.amazon.com/Wolf-Finally-Came-American-Industry/dp/0822953986/ excerpt and text search]
* Hogan, William T. Economic History of the Iron and Steel Industry in the United States (5 vol 1971) monumental detail
* Ingham, John N. The Iron Barons: A Social Analysis of an American Urban Elite, 1874-1965 (1978)
* Krass, Peter. Carnegie (2002). .
* Livesay, Harold C. Andrew Carnegie and the Rise of Big Business, 2nd Edition (1999). .
* Misa, Thomas J. A Nation of Steel: The Making of Modern America, 1865–1925 (1995) Chapter 1 "[http://www.tc.umn.edu/~tmisa//NOS/1.1_intro.html The Dominance of Rails]"
* Nasaw, David. Andrew Carnegie (The Penguin Press, 2006).
* Paskoff, Paul F. Iron and Steel in the Nineteenth Century (Encyclopedia of American Business History and Biography) (1989) 385 pp; biographies and brief corporate histories
* Rogers, Robert P. An Economic History of the American Steel Industry (2009) [https://www.amazon.com/Economic-American-Industry-Routledge-Explorations/dp/0415777607/ excerpt and text search]
* Scamehorn, H. Lee. Mill & Mine: The Cf&I in the Twentieth Century University of Nebraska Press, 1992
* Scheuerman, William. The Steel Crisis: The Economics and Politics of a Declining Industry (1986)
* Skrabec Jr, Quentin R. The Carnegie Boys: The Lieutenants of Andrew Carnegie that Changed America (McFarland, 2012).
* Seely, Bruce E., ed The Iron and Steel Industry in the 20th Century (1994) (Encyclopedia of American Business History and Biography)
* Temin, Peter. Iron and Steel in Nineteenth-Century America, An Economic Inquiry (1964)
* Wall, Joseph Frazier. Andrew Carnegie (1989). .
* Warren, Kenneth, Big Steel: The First Century of the United States Steel Corporation, 1901–2001. (University of Pittsburgh Press, 2001) [https://web.archive.org/web/20070211162744/http://eh.net/bookreviews/library/0558.shtml online review]
* Warren, Kenneth. Bethlehem Steel: Builder and Arsenal of America (2010) [https://www.amazon.com/gp/reader/0822960672/ excerpt and text search]
* Warren, Kenneth. The American Steel Industry, 1850–1970: A Geographical Interpretation (1973) ()
* Whaples, Robert. "Andrew Carnegie", EH.Net Encyclopedia of Economic and Business History [https://web.archive.org/web/20061216082029/http://eh.net/encyclopedia/article/Whaples.Carnegie online]
* [https://web.archive.org/web/20110717180737/http://www.ussteel.com/corp/about.htm#The%20History%20of%20United%20States%20Steel U.S. Steel's History of U.S. Steel]
* Urofsky, Melvin I. Big Steel and the Wilson Administration: A Study in Business-Government Relations (1969) | 1 | Applied and Interdisciplinary Chemistry |
Receptors can be activated by either endogenous agonists (such as hormones and neurotransmitters) or exogenous agonists (such as drugs), resulting in a biological response. A physiological agonist is a substance that creates the same bodily responses but does not bind to the same receptor.
* An endogenous agonist for a particular receptor is a compound naturally produced by the body that binds to and activates that receptor. For example, the endogenous agonist for serotonin receptors is serotonin, and the endogenous agonist for dopamine receptors is dopamine.
* Full agonists bind to and activate a receptor with the maximum response that an agonist can elicit at the receptor. One example of a drug that can act as a full agonist is isoproterenol, which mimics the action of adrenaline at β adrenoreceptors. Another example is morphine, which mimics the actions of endorphins at μ-opioid receptors throughout the central nervous system. However, a drug can act as a full agonist in some tissues and as a partial agonist in other tissues, depending upon the relative numbers of receptors and differences in receptor coupling.
* A co-agonist works with other co-agonists to produce the desired effect together. NMDA receptor activation requires the binding of both glutamate, glycine and D-serine co-agonists. Calcium can also act as a co-agonist at the IP3 receptor.
* A selective agonist is selective for a specific type of receptor. E.g. buspirone is a selective agonist for serotonin 5-HT1A.
* Partial agonists (such as buspirone, aripiprazole, buprenorphine, or norclozapine) also bind and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist, even at maximal receptor occupancy. Agents like buprenorphine are used to treat opiate dependence for this reason, as they produce milder effects on the opioid receptor with lower dependence and abuse potential.
* An inverse agonist is an agent that binds to the same receptor binding-site as an agonist for that receptor and inhibits the constitutive activity of the receptor. Inverse agonists exert the opposite pharmacological effect of a receptor agonist, not merely an absence of the agonist effect as seen with an antagonist. An example is the cannabinoid inverse agonist rimonabant.
* A superagonist is a term used by some to identify a compound that is capable of producing a greater response than the endogenous agonist for the target receptor. It might be argued that the endogenous agonist is simply a partial agonist in that tissue.
* An irreversible agonist is a type of agonist that binds permanently to a receptor through the formation of covalent bonds.
* A biased agonist is an agent that binds to a receptor without affecting the same signal transduction pathway. Oliceridine is a μ-opioid receptor agonist that has been described to be functionally selective towards G protein and away from β-arrestin2 pathways.
New findings that broaden the conventional definition of pharmacology demonstrate that ligands can concurrently behave as agonist and antagonists at the same receptor, depending on effector pathways or tissue type. Terms that describe this phenomenon are "functional selectivity", "protean agonism", or selective receptor modulators. | 1 | Applied and Interdisciplinary Chemistry |
Organometallic photosensitizers contain a metal atom chelated to at least one organic ligand. The photosensitizing capacities of these molecules result from electronic interactions between the metal and ligand(s). Popular electron-rich metal centers for these complexes include Iridium, Ruthenium, and Rhodium. These metals, as well as others, are common metal centers for photosensitizers due to their highly filled d-orbitals, or high d-electron counts, to promote metal to ligand charge transfer from pi-electron accepting ligands. This interaction between the metal center and the ligand leads to a large continuum of orbitals within both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) which allows for excited electrons to switch multiplicities via intersystem crossing.
While many organometallic photosensitizer compounds are made synthetically, there also exists naturally occurring, light-harvesting organometallic photosensitizers as well. Some relevant naturally occurring examples of organometallic photosensitizers include Chlorophyll A and Chlorophyll B. | 0 | Theoretical and Fundamental Chemistry |
Bridging carbido ligands can be subdivided into three classes:
*cumulenic ,
*metallocarbyne , and
*polar covalent .
Cumulenic compounds generally bridge two metal atoms of the same element and are symmetrical. However, there are exceptions to this.
In contrast, metallocarbyne compounds are generally constitutionally heterobimetallic, with complexes containing varying coordination geometries being common. These moieties have been able to serve as precursors to elaborate molecular scaffolds such as porphyrin derivatives.
The polar covalent class is distinguished from metallocarbynes by a very fine line. This carbide-metal interaction is considered labile in nature. Carbon here can be understood fundamentally as being similar to CO ligands, that is, dative (L-type). Although, this class has also been described to some extent being analogous to the behavior of Lewis acid adduct-forming terminal nitrido and oxo complexes e.g. (PMePh)Cl-Re≡N-BCl and tBu(CH)(Br)W=O-AlBr. | 0 | Theoretical and Fundamental Chemistry |
The story addresses a lot of recent scientific breakthroughs, and uses them as plot devices. For instance, The Human Genome Project, which documents all the genes and DNA in the human genetic makeup, is talked about when Dr. Wyatt explains his genetic testing to Eli for the first time. Scientific American recently published an article detailing the possible uses for the information gathered from the Human Genome Project. Modern advancements in gene studies currently can detect and, in some cases, even predict the presence of a genetic abnormality. In Double Helix, this ability to detect flaws before birth was used to genetically engineer a “more perfect son, devoid of flaws and with a proper chance to live free of Huntington’s.”
For some people, the biggest issue with genetic engineering is whether or not to seek out and act on knowledge about genetic flaws. Double Helix attempts to explore the life saving and life destroying aspects of genetic engineering. The book proposes that, while Elis life was saved by avoiding the Huntingtons disease gene, his concept of life and self were destroyed when he found out he was genetically engineered to be a certain way. | 1 | Applied and Interdisciplinary Chemistry |
Bioluminescence is produced by the dinoflagellate Pyrodinium bahamense, which glows blue when agitated. Although the phytoplankton responsible for the phenomenon of bioluminescence is found throughout the Antilles, Puerto Mosquito is one of the seven year-round bioluminescent bays in the Caribbean. The bioluminescence is the product of a number of factors: the water conditions and ecosystem created by the surrounding mangrove forest (mostly Rhizophora mangle), the complete lack of modern development in the lagoon, the temperature of the water and the depth of the bay. | 1 | Applied and Interdisciplinary Chemistry |
Grigory Moiseevich Mairanovsky (, 1899, Batumi – 1964) was a Soviet biochemist and poison developer. | 1 | Applied and Interdisciplinary Chemistry |
Due to the changes in magnetic properties that occur from a spin transition - the complex being less magnetic in a LS state and more magnetic in a HS state - magnetic susceptibility measurements are key to characterization of spin crossover compounds. The magnetic susceptibility as a function of temperature, (χT) is the principal technique used to characterize SCO complexes.
Another very useful technique for characterizing SCO complexes, especially iron complexes, is Fe Mössbauer spectroscopy. This technique is especially sensitive to magnetic effects. When spectra are recorded as a function of temperature, the areas under the curves of the absorption peaks are proportional to the fraction of HS and LS states in the sample.
SCO induces changes in metal-to-ligand bond distances due to the population or depopulation of the e orbitals that have a slight antibonding character. Consequently X-ray crystallography above and below transition temperatures will generally reveal changes in metal-ligand bond lengths. Transitions from a HS to a LS state cause a decrease in and a strengthening of the metal-ligand bond. These changes are also manifested in FT-IR and Raman spectra.
The spin crossover phenomenon is very sensitive to grinding, milling and pressure, but Raman spectroscopy has the advantage that the sample does not require further preparation, in contrast to Fourier Transform Infrared spectroscopy, FT-IR, techniques; highly colored samples may affect the measurements however. Raman spectroscopy is also advantageous because it allows perturbation of the sample with external stimuli to induce SCO. Thermally induced spin crossover is due to the higher electronic degeneracies of the LS form and lower vibrational frequencies of the HS form, thus increasing the entropy. The Raman spectrum of an iron(II) complex in the HS and LS state, emphasizing the changes in the M-L vibrational modes, where a shift from 2114 cm to 2070 cm corresponds to changes in the stretching vibrational modes of the thiocyanate ligand from a LS state to a HS state, respectively.
SCO behavior can be followed with UV-vis spectroscopy. In some cases, the absorption bands obscured due to the high intensity absorption bands caused by the Metal-to-Ligand Charge Transfer (MLCT) absorption bands. | 0 | Theoretical and Fundamental Chemistry |
The most-substantiated role for APP is in synaptic formation and repair; its expression is upregulated during neuronal differentiation and after neural injury. Roles in cell signaling, long-term potentiation, and cell adhesion have been proposed and supported by as-yet limited research. In particular, similarities in post-translational processing have invited comparisons to the signaling role of the surface receptor protein Notch.
APP knockout mice are viable and have relatively minor phenotypic effects including impaired long-term potentiation and memory loss without general neuron loss. On the other hand, transgenic mice with upregulated APP expression have also been reported to show impaired long-term potentiation.
The logical inference is that because Aβ accumulates excessively in Alzheimers disease its precursor, APP, would be elevated as well. However, neuronal cell bodies contain less APP as a function of their proximity to amyloid plaques. The data indicate that this deficit in APP results from a decline in production rather than an increase in catalysis. Loss of a neurons APP may affect physiological deficits that contribute to dementia. | 1 | Applied and Interdisciplinary Chemistry |
Leng grew up in Scarborough, North Yorkshire. She spent her childhood on the cliffs and beaches of the Lower Jurassic. Leng studied geology for GCSE and A Level. At Sixth Form College she took a field trip to Ravenscar and described finding an ammonite which hooked her into geology. She studied for a BSc in Earth Science at Oxford Polytechnic, gained her PhD at Aberystwyth University in 1990, then moved to the British Geological Survey to work in the isotope laboratory. | 0 | Theoretical and Fundamental Chemistry |
Michael Faraday provided the first description, in scientific terms, of the optical properties of nanometer-scale metals in his classic 1857 paper. In a subsequent paper, the author (Turner) points out that: "It is well known that when thin leaves of gold or silver are mounted upon glass and heated to a temperature that is well below a red heat (~500 °C), a remarkable change of properties takes place, whereby the continuity of the metallic film is destroyed. The result is that white light is now freely transmitted, reflection is correspondingly diminished, while the electrical resistivity is enormously increased." | 0 | Theoretical and Fundamental Chemistry |
A leukocidin is a type of cytotoxin created by some types of bacteria (Staphylococcus). It is a type of pore-forming toxin. The model for pore formation is step-wise. First, the cytotoxin’s “S” subunit recognizes specific protein-containing receptors, or an integrin on the host cell’s surface. The S subunit then recruits a second, “F” subunit, and the two subunits dimerize on the surface of the host’s cell. After dimerization, oligomerization occurs. Finally, the oligomers, consisting of alternating S and F subunits, undergo a significant structural change and form a beta-barrel, that pierces through the host cell’s lipid bilayer.
Leukocidins get their names by killing ("-cide") leukocytes. Leukocidins target phagocytes, natural killer cells, dendritic cells, and T lymphocytes and therefore targets both, innate and adaptive immune responses. Leukocidins fall into the category of bacterial invasin. Invasins are enzymatic secretions that help bacteria invade the host tissue to which they are attached. Although similar to exotoxins, invasins are different in two respects: they work through much less specific mechanisms than exotoxins, and their actions are generally more localized.
One type is Panton-Valentine leukocidin. | 1 | Applied and Interdisciplinary Chemistry |
High levels of aluminium occur near mining sites; small amounts of aluminium are released to the environment at the coal-fired power plants or incinerators. Aluminium in the air is washed out by the rain or normally settles down but small particles of aluminium remain in the air for a long time.
Acidic precipitation is the main natural factor to mobilize aluminium from natural sources and the main reason for the environmental effects of aluminium; however, the main factor of presence of aluminium in salt and freshwater are the industrial processes that also release aluminium into air. Plants grown in acid soils can experience a variety of stresses including aluminium (Al), hydrogen (H), and/or manganese (Mn) toxicity, as well as nutrient deficiencies of calcium (Ca) and magnesium (Mg).
Aluminium toxicity is the most widespread problem in acid soils. Aluminium is present in all soils to varying degrees, but dissolved Al is toxic to plants; Al is most soluble at low pH; above pH 5.0, there is little Al in soluble form in most soils. Aluminium is not a plant nutrient, and as such, is not actively taken up by the plants, but enters plant roots passively through osmosis. Aluminium can exist in many different forms and is a responsible agent for limiting growth in various parts of the world. Aluminium tolerance studies have been conducted in different plant species to see viable thresholds and concentrations exposed along with function upon exposure. Aluminium inhibits root growth; lateral roots and root tips become thickened and roots lack fine branching; root tips may turn brown. In the root, the initial effect of Al is the inhibition of the expansion of the cells of the rhizodermis, leading to their rupture; thereafter it is known to interfere with many physiological processes including the uptake and transport of calcium and other essential nutrients, cell division, cell wall formation, and enzyme activity.
Proton (H ion) stress can also limit plant growth. The proton pump, H-ATPase, of the plasmalemma of root cells works to maintain the near-neutral pH of their cytoplasm. A high proton activity (pH within the range 3.0–4.0 for most plant species) in the external growth medium overcomes the capacity of the cell to maintain the cytoplasmic pH and growth shuts down.
In soils with a high content of manganese-containing minerals, Mn toxicity can become a problem at pH 5.6 and lower. Manganese, like aluminium, becomes increasingly soluble as pH drops, and Mn toxicity symptoms can be seen at pH levels below 5.6. Manganese is an essential plant nutrient, so plants transport Mn into leaves. Classic symptoms of Mn toxicity are crinkling or cupping of leaves. | 0 | Theoretical and Fundamental Chemistry |
Obtaining samples for analysis is challenging. VOCs, even when at dangerous levels, are dilute, so preconcentration is typically required. Many components of the atmosphere are mutually incompatible, e.g. ozone and organic compounds, peroxyacyl nitrates and many organic compounds. Furthermore, collection of VOCs by condensation in cold traps also accumulates a large amount of water, which generally must be removed selectively, depending on the analytical techniques to be employed.
Solid-phase microextraction (SPME) techniques are used to collect VOCs at low concentrations for analysis. As applied to breath analysis, the following modalities are employed for sampling: gas sampling bags, syringes, evacuated steel and glass containers. | 0 | Theoretical and Fundamental Chemistry |
Kirchhoff's first law is that the algebraic sum of currents in a network of conductors meeting at a point (or node) is zero. The second law is that in a closed circuit, the directed sums of the voltages in the system is zero. | 1 | Applied and Interdisciplinary Chemistry |
In salt water that is free of air bubbles or suspended sediment, sound travels at about ( at , 10°C and 3% salinity by one method). The speed of sound in seawater depends on pressure (hence depth), temperature (a change of ~ ), and salinity (a change of 1‰ ~ ), and empirical equations have been derived to accurately calculate the speed of sound from these variables. Other factors affecting the speed of sound are minor. Since in most ocean regions temperature decreases with depth, the profile of the speed of sound with depth decreases to a minimum at a depth of several hundred metres. Below the minimum, sound speed increases again, as the effect of increasing pressure overcomes the effect of decreasing temperature (right). For more information see Dushaw et al.
An empirical equation for the speed of sound in sea water is provided by Mackenzie:
where
* T is the temperature in degrees Celsius;
* S is the salinity in parts per thousand;
* z is the depth in metres.
The constants a, a, ..., a are
with check value for , , . This equation has a standard error of for salinity between 25 and 40 ppt. See [http://resource.npl.co.uk/acoustics/techguides/soundseawater/] for an online calculator.
(Note: The Sound Speed vs. Depth graph does not correlate directly to the MacKenzie formula.
This is due to the fact that the temperature and salinity varies at different depths.
When T and S are held constant, the formula itself is always increasing with depth.)
Other equations for the speed of sound in sea water are accurate over a wide range of conditions, but are far more complicated, e.g., that by V. A. Del Grosso and the Chen-Millero-Li Equation. | 1 | Applied and Interdisciplinary Chemistry |
Vyacheslav Vasilyevich Lebedinsky (; 14 September 1888 – 12 December 1956) was a Russian and Soviet chemist who worked on platinum, rhodium and iridium, their extraction and use in catalysis. He also worked on complex compounds of rhodium and iridium. He was also a noted teacher and guided 20 doctoral students in inorganic chemistry.
Lebedinsky was born in Saint Petersburg. He graduated from high school in 1907 and went to St. Petersburg University. Graduating in 1913 with a thesis on anomalous rotatory dispersion he stayed on at the department of inorganic chemistry and studied under Lev Chugaev. He also examined complex metal chemistry and synthesized four forms of ammonium derivatives with trivalent rhodium. He became a professor in 1920 and moved to Moscow in 1935 to work at the Moscow Institute of Non-Ferrous Metals and Gold. He developed a method for the extraction of thee metals from copper-nickel sludge, for which he received the Stalin Prize in 1946. He studied platinum catalysis for disinfection of drinking water, and the treatment of waste water. He worked on rhodium extraction and purification and the synthesis of complex compounds of rhenium and ethylene diamine. | 0 | Theoretical and Fundamental Chemistry |
Neither Liebig nor Pasteur was completely right. However, each of their arguments led to more discoveries that created a lot of today's fields in science and medicine.
Berzelius had defined the word "ferment" as being an example of catalytic activity. Soon after, Schwann discovered pepsin was the substance responsible for albuminous digestion in the stomach. He believed this was what Berzelius defined as catalysts, or the force for chemical reactions of mineral, organic and living matter. Liebig opposed the idea by saying that the terms catalysts and pepsin are not supposed to be used as they are only representatives of an idea.
Charles Cagniard-Latour, Theodor Schwann and Friedrich Traugott Kützing identified independently yeast as a living organism that nourishes itself by the sugar it ferments, a process which referred to the ethanol fermentation (alcoholic fermentation). Liebig, Berzelius, and Wohler rejected the ideas of Schwann, Latour and Kutzing. In 1839, Liebig and Wohler published a paper on the role of yeast in alcoholic fermentation. In 1858, Liebig's student Moritz Traube enunciated the theorem, which was used for alcoholic fermentation, that all fermentations produced by living organisms are based on chemical reactions rather than a vital force itself.
The dispute between Liebig and Pasteur had, in a way, slowed down the advances of science and medicine in the area of fermentation, alcohol fermentation, and the enzymes. On the other hand, the conflicting ideas sped up the research in the area of fermentation and enzymes through other scientists and chemists. Through Büchner and his experiment in fermentation, the world of science and medicine went further as to pave ways in enzyme and fermentation studies and marked one of the critical points of the history of modern chemistry. | 1 | Applied and Interdisciplinary Chemistry |
Phylogenetic footprinting is a technique that utilizes multiple sequence alignments to determine locations of conserved sequences such as regulatory elements. Along with multiple sequence alignments, phylogenetic footprinting also requires statistical rates of conserved and non-conserved sequences. Using the information provided by multiple sequence alignments and statistical rates, one can identify the best conserved motifs in the orthologous regions of interest. | 1 | Applied and Interdisciplinary Chemistry |
Let and be two random variables, and be an arbitrary constant. Then the properties satisfied by Reynolds operators, for an operator include linearity and the averaging property:
: which implies
In addition the Reynolds operator is often assumed to commute with space and time translations:
Any operator satisfying these properties is a Reynolds operator. | 1 | Applied and Interdisciplinary Chemistry |
Fenfluramine is an indirect agonist of serotonin receptors. Fenfluramine binds to the serotonin transporter, blocking serotonin reuptake. However, fenfluramine also acts to induce non-exocytotic serotonin release; in a mechanism similar to that of methamphetamine in dopamine neurons, fenfluramine binds to VMAT2, disrupting the compartmentalization of serotonin into vesicles and increasing the concentration of cytoplasmic serotonin available for drug-induced release. | 1 | Applied and Interdisciplinary Chemistry |
Glowmatography is a laboratory technique for the separation of dyes present in solutions contained in glow sticks. The chemical components of such solutions can be chromatographically separated into polar and nonpolar components. Developed as a laboratory class experiment, it can be used to demonstrate chemistry concepts of polarity, chemical kinetics, and chemiluminescence. | 1 | Applied and Interdisciplinary Chemistry |
Geometric phase analysis is a method of digital signal processing used to determine crystallographic quantities such as d-spacing or strain from high-resolution transmission electron microscope images. The analysis needs to be performed using specialized computer program. | 0 | Theoretical and Fundamental Chemistry |
Nitriles occur naturally in a diverse set of plant and animal sources. Over 120 naturally occurring nitriles have been isolated from terrestrial and marine sources. Nitriles are commonly encountered in fruit pits, especially almonds, and during cooking of Brassica crops (such as cabbage, Brussels sprouts, and cauliflower), which release nitriles through hydrolysis. Mandelonitrile, a cyanohydrin produced by ingesting almonds or some fruit pits, releases hydrogen cyanide and is responsible for the toxicity of cyanogenic glycosides.
Over 30 nitrile-containing pharmaceuticals are currently marketed for a diverse variety of medicinal indications with more than 20 additional nitrile-containing leads in clinical development. The types of pharmaceuticals containing nitriles are diverse, from vildagliptin, an antidiabetic drug, to anastrozole, which is the gold standard in treating breast cancer. In many instances the nitrile mimics functionality present in substrates for enzymes, whereas in other cases the nitrile increases water solubility or decreases susceptibility to oxidative metabolism in the liver. The nitrile functional group is found in several drugs. | 0 | Theoretical and Fundamental Chemistry |
Figure 3 shows an impedance spectrum of a measurement series of a painted steel sample during water uptake (upper part in Figure 3). The symbols in the diagram represent the interpolation points (nodes) of the measurement, while the solid lines represent the theoretical values simulated according to an appropriate model. The interpolation points for the impedance were obtained by the Z-HIT reconstruction of the phase shift.
The bottom part of Figure 3 depicts the normalized error (Z − Z)/Z·100 of the impedance. For the error calculation, two different procedures are used to determine the "extrapolated impedance values":
* the "extrapolated impedance values" can be calculated from the "splined (=Z)" data of the impedance (magenta)
* the impedance values (blue) can be reconstructed by the Z-HIT (= Z) using the spline of the phase shift
The simulation according to the appropriate model is performed using the two different impedance curves. The corresponding residuals are calculated and depicted in the bottom part of the diagram in Figure (3).
Note: Error patterns as shown in the magenta bottom diagram in Figure (3) may be the motivation to extend an existing model by additional elements to minimize the fitting error. However, this is not possible in every case. The drift in the impedance spectrum mainly influences the low-frequency part by means of a changing system during the measurement. The spectrum in Figure 3 is caused by water penetrating into the pores of the lacquer, which reduces the impedance (resistance) of the coating. Therefore, the system behaves as if at each low-frequency measurement point the resistance of the coating was replaced by a further, smaller resistance due to the water uptake. However, there is no impedance element that exhibits such behavior. Therefore, any extension of the model would only result in a "smearing" of the error over a wider frequency range without reducing the error itself. Only the removal of the drift by reconstructing the impedance using Z-HIT leads to a significantly better compatibility between measurement and model.
Figure 4 shows a Bode plot of an impedance series measurement, performed on a fuel cell where the hydrogen of the fuel gas was deliberately poisoned by the addition of carbon monoxide. Due to the poisoning, active centers of the platinum catalyst are blocked, which severely impairs the performance of the fuel cell. Thereby, the blocking of the catalyst is depending on the potential, resulting in an alternating sorption and desorption of the carbon monoxide on the catalyst surface within the cell. This cyclical change of the active catalyst surface translates to pseudo-inductive behavior, which can be observed in the impedance spectrum of Figure 4 at low frequencies (< 3 Hz). The impedance curve was reconstructed by Z-HIT and is represented by the purple line, while the originally measured values are represented by the blue circles. The deviation in the low frequency part of the measurement can be clearly observed. Evaluation of the spectra shows significantly better agreement between model and measurement if the reconstructed Z-HIT impedances are used instead of the original data. | 0 | Theoretical and Fundamental Chemistry |
The PFT can be released in a variety of ways, depending on the application, and may be as simple as spraying into the air. Samples are then collected at set times and locations, and either taken to a laboratory for analysis, or analysed in the field.
Analysis of the samples typically involves three parts; preparation, chromatography and detection. Preparation involves removal of other impuries, for example, mixing with hydrogen then passing over a catalyst to convert oxygen to water, which is then removed with silica gel. The sample is then admitted to a gas chromatograph. This splits up the different PFTs, so a concentration value can be determined for each one.
There are two ways PFTs are then detected; using an electron capture detector or negative ion mass spectrometry. Both techniques involve bombarding the sample with electrons, and measuring the negative ions produced. Perfluorocarbons have a particularly high affinity for electrons, so are detected in low concentrations.
An alternative set up; the chromatograph can be omitted, and the different PFTs determined from their different masses in the mass spectrum.
PFTs can be detected in concentrations as low a 1 part in 10 by volume (1 femtolitre in a litre). | 1 | Applied and Interdisciplinary Chemistry |
Coenzyme A was identified by Fritz Lipmann in 1946, who also later gave it its name. Its structure was determined during the early 1950s at the Lister Institute, London, together by Lipmann and other workers at Harvard Medical School and Massachusetts General Hospital. Lipmann initially intended to study acetyl transfer in animals, and from these experiments he noticed a unique factor that was not present in enzyme extracts but was evident in all organs of the animals. He was able to isolate and purify the factor from pig liver and discovered that its function was related to a coenzyme that was active in choline acetylation. Work with Beverly Guirard, Nathan Kaplan, and others determined that pantothenic acid was a central component of coenzyme A. The coenzyme was named coenzyme A to stand for "activation of acetate". In 1953, Fritz Lipmann won the Nobel Prize in Physiology or Medicine "for his discovery of co-enzyme A and its importance for intermediary metabolism". | 1 | Applied and Interdisciplinary Chemistry |
In 1951 Callen and Welton proved the quantum fluctuation-dissipation theorem (FDT) which was originally formulated in classical form by Nyquist (1928) as an explanation for observed Johnson noise in electric circuits. Fluctuation-dissipation theorem showed that when something dissipates energy, in an effectively irreversible way, a connected heat bath must also fluctuate. The fluctuations and the dissipation go hand in hand; it is impossible to have one without the other. The implication of FDT being that the vacuum could be treated as a heat bath coupled to a dissipative force and as such energy could, in part, be extracted from the vacuum for potentially useful work. Such a theory has met with resistance: Macdonald (1962) and Harris (1971) claimed that extracting power from the zero-point energy to be impossible, so FDT could not be true. Grau and Kleen (1982) and Kleen (1986), argued that the Johnson noise of a resistor connected to an antenna must satisfy Plancks thermal radiation formula, thus the noise must be zero at zero temperature and FDT must be invalid. Kiss (1988) pointed out that the existence of the zero-point term may indicate that there is a renormalization problem—i.e., a mathematical artifact—producing an unphysical term that is not actually present in measurements (in analogy with renormalization problems of ground states in quantum electrodynamics). Later, Abbott et al. (1996) arrived at a different but unclear conclusion that "zero-point energy is infinite thus it should be renormalized but not the zero-point fluctuations'". Despite such criticism, FDT has been shown to be true experimentally under certain quantum, non-classical conditions. Zero-point fluctuations can, and do, contribute towards systems which dissipate energy. A paper by Armen Allahverdyan and Theo Nieuwenhuizen in 2000 showed the feasibility of extracting zero-point energy for useful work from a single bath, without contradicting the laws of thermodynamics, by exploiting certain quantum mechanical properties.
There have been a growing number of papers showing that in some instances the classical laws of thermodynamics, such as limits on the Carnot efficiency, can be violated by exploiting negative entropy of quantum fluctuations.
Despite efforts to reconcile quantum mechanics and thermodynamics over the years, their compatibility is still an open fundamental problem. The full extent that quantum properties can alter classical thermodynamic bounds is unknown | 0 | Theoretical and Fundamental Chemistry |
N-heterocyclic carbene (NHC) supported Cu complexes catalyze carboxylation of organoboronic esters. The catalyst forms in situ from CuCl, an NHC ligand, and KOBu. Copper tert-butoxide can transmetallate with the organoboronic ester to generate the Cu-C bond, which intermediate can insert into CO smoothly to get the respective carboxylate. Salt metathesis with KOBu releases product and regenerates catalyst (Scheme 2).
Apart from transmetallation, there are other approaches forming Cu-C bond. C-H functionalization is a straightforward and atom economic method. Base can help deprotonate acidic C-H protons and form Cu-C bond. [(Phenanthroline)Cu(PR)] catalyst effect C-H carboxylation on terminal alkynes together with CsCO. NHC-Cu-H species to deprotonate acidic proton to effect carboxylation of terminal alkynes. Cu-H species were generated from Cu-F and organosilanes. The carboxylate product was trapped by silyl fluoride to get silyl ether. For non-acidic C-H bonds, directed metalation with BuAl(TMP)Li is adopted followed by transmetallation with copper to get Cu-C bond. Allylic C-H bonds and phenyl C-H bonds got carboxylated with this approach by Hou and co-workers:
Carbometallation to alkynes and allenes using organozinc and organoaluminum reagents followed by transmetallation to copper is also a strategy to initiate carboxylation. Trimethylaluminium is able to insert into unbiased aliphatic internal alkynes with syn fashion directed by ether directing group. Vinyl copper complexes are formed by transmetallation and carboxylation is realized with a similar pathway giving tetrasubstituted aliphatic vinyl carboxylic acids. In this case, regioslectivity is controlled by the favor of six-membered aluminum ring formation. Furthermore, carboxylation can be achieved on ynamides and allenamides using less reactive dimethyl zinc via similar approach. | 0 | Theoretical and Fundamental Chemistry |
Without a universally valid description of turbulence, empirical information must be utilized when constructing and applying SGS models, supplemented with fundamental physical constraints such as Galilean invariance
Two classes of SGS models exist; the first class is functional models and the second class is structural models. Some models may be categorized as both. | 1 | Applied and Interdisciplinary Chemistry |
In 1827, Claus became involved, as an assistant of Eduard Friedrich Eversmann, in the botanical research of the steppes of the rivers Ural and Volga. He later used the collected data in his work Flora der Wolgagegenden (Flora of the Volga Region).
In 1834, while still studying at the University of Tartu, Claus went into another botanic trip to the trans-Volga steppes – this time with chemistry professor Gebel. The results of this expeditions were published in 1837–1838. | 1 | Applied and Interdisciplinary Chemistry |
Copper was probably the first metal mined and crafted by humans. It was originally obtained as a native metal and later from the smelting of ores. Earliest estimates of the discovery of copper suggest around 9000 BC in the Middle East. It was one of the most important materials to humans throughout the Chalcolithic and Bronze Ages. Copper beads dating from 6000 BC have been found in Çatalhöyük, Anatolia and the archaeological site of Belovode on the Rudnik mountain in Serbia contains the world's oldest securely dated evidence of copper smelting from 5000 BC. It was recognised as an element by Louis Guyton de Morveau, Antoine Lavoisier, Claude Berthollet, and Antoine-François de Fourcroy in 1787.
It is believed that lead smelting began at least 9,000 years ago, and the oldest known artifact of lead is a statuette found at the temple of Osiris on the site of Abydos dated around 3800 BC. It was recognised as an element by Guyton de Morveau, Lavoisier, Berthollet, and Fourcroy in 1787.
The earliest gold artifacts were discovered at the site of Wadi Qana in the Levant. Silver is estimated to have been discovered in Asia Minor shortly after copper and gold.
There is evidence that iron was known from before 5000 BC. The oldest known iron objects used by humans are some beads of meteoric iron, made in Egypt in about 4000 BC. The discovery of smelting around 3000 BC led to the start of the Iron Age around 1200 BC and the prominent use of iron for tools and weapons. It was recognised as an element by Guyton de Morveau, Lavoisier, Berthollet, and Fourcroy in 1787.
Tin was first smelted in combination with copper around 3500 BC to produce bronze (and thus giving place to the Bronze Age (except in some places which did not experience a significant Bronze Age, passing directly from the Neolithic Stone Age to the Iron Age)). Kestel, in southern Turkey, is the site of an ancient Cassiterite mine that was used from 3250 to 1800 BC. The oldest artifacts date from around 2000 BC. It was recognised as an element by Guyton de Morveau, Lavoisier, Berthollet, and Fourcroy in 1787. | 1 | Applied and Interdisciplinary Chemistry |
Commercially, GaN crystals can be grown using molecular beam epitaxy or metalorganic vapour phase epitaxy. This process can be further modified to reduce dislocation densities. First, an ion beam is applied to the growth surface in order to create nanoscale roughness. Then, the surface is polished. This process takes place in a vacuum. Polishing methods typically employ a liquid electrolyte and UV irradiation to enable mechanical removal of a thin oxide layer from the wafer. More recent methods have been developed which utilize solid-state polymer electrolytes which are solvent-free and require no radiation before polishing. | 0 | Theoretical and Fundamental Chemistry |
Tube bending is any metal forming processes used to permanently form pipes or tubing. Tube bending may be form-bound or use freeform-bending procedures, and it may use heat supported or cold forming procedures.
Form bound bending procedures like “press bending” or “rotary draw bending” are used to form the work piece into the shape of a die. Straight tube stock can be formed using a bending machine to create a variety of single or multiple bends and to shape the piece into the desired form. These processes can be used to form complex shapes out of different types of ductile metal tubing. Freeform-bending processes, like three-roll-pushbending, shape the workpiece kinematically, thus the bending contour is not dependent on the tool geometry.
Generally, round stock is used in tube bending. However, square and rectangular tubes and pipes may also be bent to meet job specifications. Other factors involved in the bending process are the wall thickness, tooling and lubricants needed by the pipe and tube bender to best shape the material, and the different ways the tube may be used (tube, pipe wires). | 1 | Applied and Interdisciplinary Chemistry |
Morpholinos have become a standard knockdown tool in animal embryonic systems, which have a broader range of gene expression than adult cells and can be strongly affected by an off-target interaction. Following initial injections into frog or fish embryos at the single-cell or few-cell stages, Morpholino effects can be measured up to five days later, after most of the processes of organogenesis and differentiation are past, with observed phenotypes consistent with target-gene knockdown. Control oligos with irrelevant sequences usually produce no change in embryonic phenotype, evidence of the Morpholino oligo's sequence-specificity and lack of non-antisense effects. The dose required for a knockdown can be reduced by coinjection of several Morpholino oligos targeting the same mRNA, which is an effective strategy for reducing or eliminating dose-dependent off-target RNA interactions.
mRNA rescue experiments can sometimes restore the wild-type phenotype to the embryos and provide evidence for the specificity of a Morpholino. In an mRNA rescue, a Morpholino is co-injected with an mRNA that codes for the morphlinos protein. However, the rescue mRNA has a modified 5-UTR (untranslated region) so that the rescue mRNA contains no target for the Morpholino. The rescue mRNAs coding region encodes the protein of interest. Translation of the rescue mRNA replaces production of the protein that was knocked down by the Morpholino. Since the rescue mRNA would not affect phenotypic changes due to the Morpholinos off-target gene expression modulation, this return to wild-type phenotype is further evidence of Morpholino specificity. In some cases, ectopic expression of the rescue RNA makes recovery of the wild-type phenotype impossible.
In embryos, Morpholinos can be tested in null mutants to check for unexpected RNA interactions, then used in a wild-type embryo to reveal the acute knockdown phenotype. The knockdown phenotype is often more extreme than the mutant phenotype; in the mutant, effects of losing the null gene can be concealed by genetic compensation.
Because of their completely unnatural backbones, Morpholinos are not recognized by cellular proteins. Nucleases do not degrade Morpholinos, nor are they degraded in serum or in cells.
Up to 18% of Morpholinos appear to induce nontarget-related phenotypes including cell death in the central nervous system and somite tissues of zebrafish embryos. Most of these effects are due to activation of p53-mediated apoptosis and can be suppressed by co-injection of an anti-p53 Morpholino along with the experimental Morpholino. Moreover, the p53-mediated apoptotic effect of a Morpholino knockdown has been phenocopied using another antisense structural type, showing the p53-mediated apoptosis to be a consequence of the loss of the targeted protein and not a consequence of the knockdown oligo type. It appears that these effects are sequence-specific; as in most cases, if a Morpholino is associated with non-target effects, the 4-base mismatch Morpholino will not trigger these effects.
A cause for concern in the use of Morpholinos is the potential for "off-target" effects. Whether an observed morphant phenotype is due to the intended knockdown or an interaction with an off-target RNA can often be addressed in embryos by running another experiment to confirm that the observed morphant phenotype results from the knockdown of the expected target. This can be done by recapitulating the morphant phenotype with a second, non-overlapping Morpholino targeting the same mRNA, by confirmation of the observed phenotypes by comparing with a mutant strain (though compensation will obscure a phenotype in some mutants), by testing the Morpholino in a null mutant background to detect additional phenotypic changes or by dominant-negative methods. As mentioned above, rescue of observed phenotypes by coinjecting a rescue mRNA is, when feasible, a reliable test of specificity of a Morpholino. | 1 | Applied and Interdisciplinary Chemistry |
Purines from turnover of cellular nucleic acids (or from food) can also be salvaged and reused in new nucleotides.
* The enzyme adenine phosphoribosyltransferase (APRT) salvages adenine.
* The enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) salvages guanine and hypoxanthine. (Genetic deficiency of HGPRT causes Lesch–Nyhan syndrome.) | 1 | Applied and Interdisciplinary Chemistry |
The major role of chemokines is to act as a chemoattractant to guide the migration of cells. Cells that are attracted by chemokines follow a signal of increasing chemokine concentration towards the source of the chemokine. Some chemokines control cells of the immune system during processes of immune surveillance, such as directing lymphocytes to the lymph nodes so they can screen for invasion of pathogens by interacting with antigen-presenting cells residing in these tissues. These are known as homeostatic chemokines and are produced and secreted without any need to stimulate their source cells. Some chemokines have roles in development; they promote angiogenesis (the growth of new blood vessels), or guide cells to tissues that provide specific signals critical for cellular maturation. Other chemokines are inflammatory and are released from a wide variety of cells in response to bacterial infection, viruses and agents that cause physical damage such as silica or the urate crystals that occur in gout. Their release is often stimulated by pro-inflammatory cytokines such as interleukin 1. Inflammatory chemokines function mainly as chemoattractants for leukocytes, recruiting monocytes, neutrophils and other effector cells from the blood to sites of infection or tissue damage. Certain inflammatory chemokines activate cells to initiate an immune response or promote wound healing. They are released by many different cell types and serve to guide cells of both innate immune system and adaptive immune system. | 1 | Applied and Interdisciplinary Chemistry |
Low-pressure mercury-vapor lamps generate primarily 254 nm UVC energy, and are most commonly used in disinfection applications. Operated at lower temperatures and with less voltage than medium-pressure lamps, they, like all UV sources, require shielding when operated to prevent excess exposure of skin and eyes. | 0 | Theoretical and Fundamental Chemistry |
It is possible to envision three-dimensional (3D) graphs showing three thermodynamic quantities. For example, for a single component, a 3D Cartesian coordinate type graph can show temperature (T) on one axis, pressure (p) on a second axis, and specific volume (v) on a third. Such a 3D graph is sometimes called a p–v–T diagram. The equilibrium conditions are shown as curves on a curved surface in 3D with areas for solid, liquid, and vapor phases and areas where solid and liquid, solid and vapor, or liquid and vapor coexist in equilibrium. A line on the surface called a triple line is where solid, liquid and vapor can all coexist in equilibrium. The critical point remains a point on the surface even on a 3D phase diagram.
An orthographic projection of the 3D p–v–T graph showing pressure and temperature as the vertical and horizontal axes collapses the 3D plot into the standard 2D pressure–temperature diagram. When this is done, the solid–vapor, solid–liquid, and liquid–vapor surfaces collapse into three corresponding curved lines meeting at the triple point, which is the collapsed orthographic projection of the triple line. | 0 | Theoretical and Fundamental Chemistry |
ASF/SF2, in the presence of elF4E, promotes the initiation of translation of ribosome-bound mRNA by suppressing the activity of 4E-BP and recruiting molecules for further regulation of translation. ASF/SF2 interacts with the nuclear export protein TAP in a regulated manner, controlling the export of mature mRNA from the nucleus. An increase in cellular ASF/SF2 also will increase the efficiency of nonsense-mediated mRNA decay (NMD), favoring NMD that occurs before mRNA release from the nucleus over NMD that occurs after mRNA export from the nucleus to the cytoplasm. This shift in NMD caused by increased ASF/SF2 is accompanied by overall enhancement of the pioneer round of translation, through elF4E-bound mRNA translation and subsequent translationally active ribosomes, increased association of pioneer translation initiation complexes with ASF/SF2, and increased levels of active TAP. | 1 | Applied and Interdisciplinary Chemistry |
The statins differ with respect to their ring structure and substituents. These differences in structure affect the pharmacological properties of the statins, such as:
*Affinity for the active site of the HMGR
*Rates of entry into hepatic and non-hepatic tissues
*Availability in the systemic circulation for uptake into non-hepatic tissues
*Routes and modes of metabolic transformation and elimination
Statins have sometimes been grouped into two groups of statins according to their structure.
Type 1 statins
Statins that have substituted decalin-ring structure that resemble the first statin ever discovered, mevastatin have often been classified as type 1 statins due to their structural relationship. Statins that belong to this group are:
*Lovastatin (Figure 2)
*Pravastatin
*Simvastatin
Type 2 statins
Statins that are fully synthetic and have larger groups linked to the HMG-like moiety are often referred to as type 2 statins. One of the main differences between the type 1 and type 2 statins is the replacement of the butyryl group of type 1 statins by the fluorophenyl group of type 2 statins. This group is responsible for additional polar interactions that causes tighter binding to the HMGR enzyme. Statins that belong to this group are:
*Fluvastatin (Figure 3)
*Cerivastatin
*Atorvastatin
*Rosuvastatin
Lovastatin is derived from a fungus source and simvastatin and pravastatin are chemical modifications of lovastatin and as a result do not differ much in structure from lovastatin. All three are partially reduced napthylene ring structures. Simvastatin and lovastatin are inactive lactones which must be metabolized to their active hydroxy-acid forms in order to inhibit HMGR. Type 2 statins all exist in their active hydroxy-acid forms. Fluvastatin has indole ring structure, while atorvastatin and rosuvastatin have pyrrole and pyrimidine based ring structure respectively. The lipophilic cerivastatin has a pyridine-based ring structure. | 1 | Applied and Interdisciplinary Chemistry |
Murray was the author or co-author of scientific publications about organic chemistry and lichens. Some of his most significant were:
* James Murray (1959) [https://paperspast.natlib.govt.nz/periodicals/TPRSNZ1960-88.2.6.5 Studies of New Zealand Lichens. I—The Coniocarpineae] Transactions of the Royal Society of New Zealand 88 (2) 177 - 195
* James Murray (1960) [https://paperspast.natlib.govt.nz/periodicals/TPRSNZ1960-88.2.6.6 Studies of New Zealand Lichens. II—The Teloschistaceae] Transactions of the Royal Society of New Zealand 88 (2) 197 - 210
* James Murray (1960) [https://paperspast.natlib.govt.nz/periodicals/TPRSNZ1960-88.2.8.4 Studies on New Zealand Lichens Part III.–The Family Peltigeraceae] Transactions of the Royal Society of New Zealand 88 (3) 381 - 399
* James Murray (1962) [https://nzetc.victoria.ac.nz/tm/scholarly/tei-Bio10Tuat03-t1-body-d2.html Keys to New Zealand lichens. Part 1.] Tuatara 10 (3) 120 - 128 (published posthumously)
* James Murray (1963) [https://nzetc.victoria.ac.nz/tm/scholarly/tei-Bio11Tuat01-t1-body-d8.html Keys to New Zealand lichens. Part 2.] Tuatara 11 (1) 46 - 56 (published posthumously)
* James Murray (1963) [https://nzetc.victoria.ac.nz/tm/scholarly/tei-Bio11Tuat02-t1-body-d9.html Keys to New Zealand lichens. Part 2.] Tuatara 11 (2) 98 - 109 (published posthumously) | 0 | Theoretical and Fundamental Chemistry |
Abiotic sources of hydrogen gas include water-rock and photochemical reactions. Exothermic serpentinization reactions between water and olivine minerals produce H in the marine or terrestrial subsurface. In the ocean, hydrothermal vents erupt magma and altered seawater fluids including abundant H, depending on the temperature regime and host rock composition. Molecular hydrogen can also be produced through photooxidation (via solar UV radiation) of some mineral species such as siderite in anoxic aqueous environments. This may have been an important process in the upper regions of early Earth's Archaean oceans. | 1 | Applied and Interdisciplinary Chemistry |
Piping corrosion circuit or Corrosion loop
/ Piping Circuitization and Corrosion Modelling, is carried out as part of either a Risk Based Inspection analysis (RBI) or Materials Operating Envelope analysis (MOE). It is the systematization of the piping components versus failure modes analysis into materials operating envelope. It groups piping materials / chemical make-up into systems / sub systems and assigns corrosion mechanisms. These are then monitored over the operating lifetime of the facility. This analysis is performed on circuit inspection results to determine and optimize circuit corrosion rates and measured thickness/dates for circuit components. Corrosion Circuits are utilized in the Integrity Management Plan (IMP) which forms a part of the overall Asset integrity management system and is an integral part of any RBI analysis. Many times a "system" will be a broad overview of the facilities process flow, broken by stream constituents, while a circuit level analysis breaks systems into smaller "circuits" that group common metallurgies, equal (or roughly equal) temperatures and pressures, and expected damage mechanisms. | 1 | Applied and Interdisciplinary Chemistry |
Toshiko Mayeda was born in Tacoma, Washington. She grew up in Yokkaichi, Mie, and Osaka. When the United States entered World War II after the Japanese attack on Pearl Harbor, she and her father Matsusaburo Kuki were sent to the Tule Lake War Relocation Center. Whilst there she met her future husband, Harry Mayeda. After the war, she graduated with a bachelor's degree in chemistry from the University of Chicago in 1949. | 0 | Theoretical and Fundamental Chemistry |
Zolghadr and co-workers presented a fluorescent two-hybrid system that uses two hybrid proteins that are fused to different fluorescent proteins as well as LacI, the lac repressor. The structure of the fusion proteins looks like this: FP2-LacI-bait and FP1-prey where the bait and prey proteins interact and bring the fluorescent proteins (FP1 = GFP, FP2=mCherry) in close proximity at the binding site of the LacI protein in the host cell genome. The system can also be used to screen for inhibitors of protein–protein interactions. | 1 | Applied and Interdisciplinary Chemistry |
Most successful early forms of self-propelled torpedoes used high-pressure compressed air, although this was superseded by internal or external combustion engines, steam engines (driven by the catalytic decomposition of hydrogen peroxide), or electric motors. | 1 | Applied and Interdisciplinary Chemistry |
1,1,1-Trichloroethane is generally considered a non-polar solvent. Owing to the good polarizability of the chlorine atoms, it is a superior solvent for organic compounds that do not dissolve well in hydrocarbons such as hexane. It is an excellent solvent for many organic materials and also one of the least toxic of the chlorinated hydrocarbons. Prior to the Montreal Protocol, it was widely used for cleaning metal parts and circuit boards, as a photoresist solvent in the electronics industry, as an aerosol propellant, as a cutting fluid additive, and as a solvent for inks, paints, adhesives, and other coatings. 1,1,1-Trichloroethane was used to dry-clean leather and suede. 1,1,1-Trichloroethane is also used as an insecticidal fumigant.
It was also the standard cleaner for photographic film (movie/slide/negatives, etc.). Other commonly available solvents damage emulsion and base (acetone will severely damage triacetate base on most films), and thus are not suitable for this application. The standard replacement, Forane 141 is much less effective, and tends to leave a residue. 1,1,1-Trichloroethane was used as a thinner in correction fluid products such as liquid paper. Many of its applications previously used carbon tetrachloride (which was banned in US consumer products in 1970). In turn, 1,1,1-trichloroethane itself is now being replaced by other solvents in the laboratory. | 1 | Applied and Interdisciplinary Chemistry |
The Stieglitz Award was established in 1940 using funds from the memorial legacy of Professor Julius Stieglitz, who worked at the University of Chicago from 1892 to his death in 1937. The lecture was presented alternatively by the University of Chicago Chemistry department and the Chicago Section of the American Chemical Society in consecutive years until 1994. There was a pause in presentation from 1994 until 1999 until the funds built up to a level where they were sufficient to support a stipend of $1000 plus expenses for each year. | 1 | Applied and Interdisciplinary Chemistry |
If we consider a line source and a line sink at a distance d we can reuse the results above and the stream function will be
The last approximation is to the first order in d.
Given
It remains
The velocity is then
And the potential instead | 1 | Applied and Interdisciplinary Chemistry |
Matrix enhancement and suppression is frequently observed in modern analytical routines, such as GC, HPLC, and ICP.
Matrix effect is quantitated by the use of the following formula:
where
A(extract) is the peak area of analyte, when diluted with matrix extract.
A(standard) is the peak area of analyte in the absence of matrix.
The concentration of analyte in both standards should be the same. A matrix effect value close to 100 indicates absence of matrix influence. A matrix effect value of less than 100 indicates suppression, while a value larger than 100 is a sign of matrix enhancement.
An alternative definition of matrix effect utilizes the formula:
The advantages of this definition are that negative values indicates suppression, while positive values are a sign of matrix enhancement. Ideally, a value of 0 is related to the absence of matrix effect. | 0 | Theoretical and Fundamental Chemistry |
Between 1936 and 1940, Japanese chemist and lichenologist Yasuhiko Asahina published a series of papers in the Journal of Japanese Botany detailing the microcrystallization technique. This simple and rapid method allowed for the identification of major metabolites in hundreds of lichen species, contributing significantly to taxonomic research. The technique was introduced to western lichenologists in a 1943 publication by Alexander Evans, and was used regularly until more advanced techniques such as thin-layer chromatography and high-performance liquid chromatography were introduced and integrated into laboratories. Decades of research on the secondary metabolites of lichens culminated in the publication of Identification of Lichen Substances, a 1996 work by Siegfried Huneck and Isao Yoshimura, that summarized analytical data for hundreds of lichen molecules, including images of microcrystals. Ultimately, the microcrystallization method had limitations, as it was unable to detect minor components or analyze complex mixtures of lichen substances. Despite these drawbacks, microcrystallization played a crucial role in the study of correlations between lichen chemistry, morphology, and geographic distribution. | 0 | Theoretical and Fundamental Chemistry |
Any process that results in the production of methane and its release into the atmosphere can be considered a "source". The known sources of methane are predominantly located near the Earth's surface. Two main processes that are responsible for methane production include microorganisms anaerobically converting organic compounds into methane (methanogenesis), which are widespread in aquatic ecosystems, and ruminant animals. Other natural sources include melting permafrost, wetlands, plants, and methane clathrates. | 1 | Applied and Interdisciplinary Chemistry |
With a theoretical decomposition energy of about 5 kJ/g, hydroxylamine is an explosive, and aqueous solutions above 80% can be easily detonated by detonator or strong heating under confinement. At least two factories dealing in hydroxylamine have been destroyed since 1999 with loss of life. It is known, however, that ferrous and ferric iron salts accelerate the decomposition of 50% solutions. Hydroxylamine and its derivatives are more safely handled in the form of salts.
It is an irritant to the respiratory tract, skin, eyes, and other mucous membranes. It may be absorbed through the skin, is harmful if swallowed, and is a possible mutagen. | 0 | Theoretical and Fundamental Chemistry |
Nucleation can be either homogeneous, without the influence of foreign particles, or heterogeneous, with the influence of foreign particles. Generally, heterogeneous nucleation takes place more quickly since the foreign particles act as a scaffold for the crystal to grow on, thus eliminating the necessity of creating a new surface and the incipient surface energy requirements.
Heterogeneous nucleation can take place by several methods. Some of the most typical are small inclusions, or cuts, in the container the crystal is being grown on. This includes scratches on the sides and bottom of glassware. A common practice in crystal growing is to add a foreign substance, such as a string or a rock, to the solution, thereby providing nucleation sites for facilitating crystal growth and reducing the time to fully crystallize.
The number of nucleating sites can also be controlled in this manner. If a brand-new piece of glassware or a plastic container is used, crystals may not form because the container surface is too smooth to allow heterogeneous nucleation. On the other hand, a badly scratched container will result in many lines of small crystals. To achieve a moderate number of medium-sized crystals, a container which has a few scratches works best. Likewise, adding small previously made crystals, or seed crystals, to a crystal growing project will provide nucleating sites to the solution. The addition of only one seed crystal should result in a larger single crystal. | 0 | Theoretical and Fundamental Chemistry |
The runoff footprint is the stormwater equivalent to the carbon/energy footprint. When homeowners or business owners complete an energy audit or carbon footprint, they understand how they are consuming energy and learn how this consumption can be reduced through energy efficiency measures. Correspondingly, the runoff footprint allows someone to calculate their baseline annual runoff and assess what the impact of ideal stormwater green solutions would be for their site. Since the passage of the Clean Water Act in 1972, the EPA has monitored and regulated stormwater issues in urban areas. Municipalities across the United States are now required to upgrade sanitary and stormwater systems to meet EPA mandates. The total cost for these upgrades across the United States exceeds $3000 billion. The stormwater runoff from every property in an area can contribute to the overall stormwater issues including overflows and water pollution. Stormwater runoff carries nonpoint source pollution which is a leading cause of water quality issues.
By completing a runoff footprint, homeowners and business owners can consider how stormwater green solutions can reduce runoff on-site. Stormwater green solutions (also called green infrastructure) use "vegetation, soils, and natural processes to manage water and create healthier urban environments. At the scale of a city or county, green infrastructure refers to the patchwork of natural areas that provides habitat, flood protection, cleaner air, and cleaner water. At the scale of a neighborhood or site, green infrastructure refers to stormwater management systems that mimic nature by soaking up and storing water". Stormwater green solutions include bioswales (directional rain gardens), cisterns, green roofs, permeable pavement, rain barrels, and rain gardens. According to the EPA, onsite stormwater green solutions or low-impact developments (LIDs) can significantly reduce runoff and costly stormwater/sewer infrastructure upgrades.
Stormwater green solutions can also reduce energy consumption. Treating and pumping water is an energy-intensive activity. According to the River Network, the U.S. consumes at least 521 million MWh a year for water-related purposes which is the equivalent to 13% of the nation’s electricity consumption Potable water must be treated and then pumped to the consumer. Wastewater is treated before being discharged. In areas with combined sewer systems or old separate sewer systems with high inflow and infiltration, stormwater is also treated at the wastewater treatment facilities. By capturing stormwater runoff onsite in rain barrels and cisterns, the consumption of potable water for irrigation and its corresponding energy impact can be reduced. The reduction of runoff from all types of stormwater green solutions reduces the stormwater that may end up at the wastewater treatment facility in areas with combined sewer systems or old separate sewers. | 1 | Applied and Interdisciplinary Chemistry |
A suitable setup for automated thermometric titrimetry comprises the following:
* Precision fluid dispensing devices – "burettes" – for adding titrants and dosing of other reagents
* Thermistor-based thermometric sensor
* Titration vessel
* Stirring device, capable of highly efficient stirring of vessel contents without splashing
* Computer with thermometric titration operating system
* Thermometric titration interface module – this regulates the data flow between the burettes, sensors and the computer
Figure 6 illustrates a modern automated thermometric titration system based on the Metrohm 859 Titrotherm interface module with Thermoprobe sensor, Metrohm 800 Dosino dispensing devices and a computer running the operational software.
Figure 7 is a schematic of the relationship between components in automated thermometric titration system.
A = dosing device <br>
B = thermometric sensor <br>
C = stirring device <br>
D = thermometric titration interface module <br>
E = computer | 0 | Theoretical and Fundamental Chemistry |
The hormonal contribution to several categories of breast cancer subtypes was recognized during this time, leading to the development of pharmacological modulators (e.g. of oestrogen) such as tamoxifen. | 1 | Applied and Interdisciplinary Chemistry |
Phreds approach to base calling and calculating quality scores was outlined by Ewing et al.'. To determine quality scores, Phred first calculates several parameters related to peak shape and peak resolution at each base. Phred then uses these parameters to look up a corresponding quality score in huge lookup tables. These lookup tables were generated from sequence traces where the correct sequence was known, and are hard coded in Phred; different lookup tables are used for different sequencing chemistries and machines. An evaluation of the accuracy of Phred quality scores for a number of variations in sequencing chemistry and instrumentation showed that Phred quality scores are highly accurate.
Phred was originally developed for "slab gel" sequencing machines like the ABI373. When originally developed, Phred had a lower base calling error rate than the manufacturers base calling software, which also did not provide quality scores. However, Phred was only partially adapted to the capillary DNA sequencers that became popular later. In contrast, instrument manufacturers like ABI continued to adapt their base calling software changes in sequencing chemistry, and have included the ability to create Phred-like quality scores. Therefore, the need to use Phred for base calling of DNA sequencing traces has diminished, and using the manufacturers current software versions can often give more accurate results. | 1 | Applied and Interdisciplinary Chemistry |
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