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In computer technology, dynamic random access memory (DRAM) "soft errors" were linked to alpha particles in 1978 in Intel's DRAM chips. The discovery led to strict control of radioactive elements in the packaging of semiconductor materials, and the problem is largely considered to be solved. | 0 | Theoretical and Fundamental Chemistry |
The turbine meter is available in various manufacturers configurations of a common theme; turbine blades and rotor configured devices. These devices are designed such that when a gas stream passes through them they will spin proportionally to the amount of gas passing over the blades in a repeatable fashion. Accuracy is then ensured by completion of a calibration, indicating the relationship between rotational speed and volume, at various Reynolds Numbers. The fundamental difference between the orifice meter and the turbine meter is the flow equation derivation. The orifice meter flow calculation is based on fluid flow fundamentals (a 1st Law of Thermodynamics derivation utilizing the pipe diameter and vena contracta diameters for the continuity equation). Deviations from theoretical expectation can be assumed under the Coefficient of Discharge. Thus, one can manufacture an orifice meter of known uncertainty with only the measurement standard in hand and access to a machine shop. The need for flow conditioning, and hence, a fully developed velocity flow profile is driven from the original determination of Cd which utilized fully developed or reference profiles' as explained above.
Conversely, the turbine meter operation is not rooted deeply in fundamentals of thermodynamics. This is not to say that the turbine meter is in any way an inferior device. There are sound engineering principles providing theoretical background. It is essentially an extremely repeatable device that is then assured accuracy via calibration. The calibration provides the accuracy. It is carried out in good flow conditions (flow conditions free of swirl and a uniform velocity flow profile) this is carried out for every meter manufactured. Deviations from the as-calibrated conditions would be considered installation effects, and the sensitivity of the turbine meter to these installation effects is of interest. The need for flow conditioning is driven from the sensitivity of the meter to deviations from as calibrated conditions of swirl and velocity profile.
Generally, recent research indicates that turbine meters are sensitive to swirl but not to the shape of the velocity profile. A uniform velocity profile is recommended, but no strict requirements for fully developed flow profiles are indicated. Also, no significant errors are evident when installing single or dual rotor turbine meters downstream of two elbows out-of-plane without flow conditioning devices. | 1 | Applied and Interdisciplinary Chemistry |
Amines are named in several ways. Typically, the compound is given the prefix "amino-" or the suffix "-amine". The prefix "N-" shows substitution on the nitrogen atom. An organic compound with multiple amino groups is called a diamine, triamine, tetraamine and so forth.
Lower amines are named with the suffix -amine.
Higher amines have the prefix amino as a functional group. IUPAC however does not recommend this convention, but prefers the alkanamine form, e.g. butan-2-amine. | 0 | Theoretical and Fundamental Chemistry |
Lichens come in many colors. Coloration is usually determined by the photosynthetic component. Special pigments, such as yellow usnic acid, give lichens a variety of colors, including reds, oranges, yellows, and browns, especially in exposed, dry habitats. In the absence of special pigments, lichens are usually bright green to olive gray when wet, gray or grayish-green to brown when dry. This is because moisture causes the surface skin (cortex) to become more transparent, exposing the green photobiont layer. Different colored lichens covering large areas of exposed rock surfaces, or lichens covering or hanging from bark can be a spectacular display when the patches of diverse colors "come to life" or "glow" in brilliant displays following rain.
Different colored lichens may inhabit different adjacent sections of a rock face, depending on the angle of exposure to light. Colonies of lichens may be spectacular in appearance, dominating much of the surface of the visual landscape in forests and natural places, such as the vertical "paint" covering the vast rock faces of Yosemite National Park.
Color is used in identification. The color of a lichen changes depending on whether the lichen is wet or dry. Color descriptions used for identification are based on the color that shows when the lichen is dry. Dry lichens with a cyanobacterium as the photosynthetic partner tend to be dark grey, brown, or black.
The underside of the leaf-like lobes of foliose lichens is a different color from the top side (dorsiventral), often brown or black, sometimes white. A fruticose lichen may have flattened "branches", appearing similar to a foliose lichen, but the underside of a leaf-like structure on a fruticose lichen is the same color as the top side. The leaf-like lobes of a foliose lichen may branch, giving the appearance of a fruticose lichen, but the underside will be a different color from the top side.
The sheen on some jelly-like gelatinous lichens is created by mucilaginous secretions. | 1 | Applied and Interdisciplinary Chemistry |
FRAP can also be used to monitor proteins outside the membrane. After the protein of interest is made fluorescent, generally by expression as a GFP fusion protein, a confocal microscope is used to photobleach and monitor a region of the cytoplasm, mitotic spindle, nucleus, or another cellular structure. The mean fluorescence in the region can then be plotted versus time since the photobleaching, and the resulting curve can yield kinetic coefficients, such as those for the proteins binding reactions and/or the proteins diffusion coefficient in the medium where it is being monitored. Often the only dynamics considered are diffusion and binding/unbinding interactions, however, in principle proteins can also move via flow, i.e., undergo directed motion, and this was recognized very early by Axelrod et al. This could be due to flow of the cytoplasm or nucleoplasm, or transport along filaments in the cell such as microtubules by molecular motors.
The analysis is most simple when the fluorescence recovery is limited by either the rate of diffusion into the bleached area or by rate at which bleached proteins unbind from their binding sites within the bleached area, and are replaced by fluorescent protein. Let us look at these two limits, for the common case of bleaching a GFP fusion protein in a living cell. | 1 | Applied and Interdisciplinary Chemistry |
Implantation of any foreign device or material through the means of surgery results in at least some degree of tissue trauma. Therefore, especially when removing a native heart valve either partially or completely, the tissue trauma will trigger a cascade of inflammatory responses and elicit acute inflammation. During the initial phase of acute inflammation, vasodilation occurs to increase blood flow to the wound site along with the release of growth factors, cytokines, and other immune cells. Furthermore, cells release reactive oxygen species and cytokines, which cause secondary damage to surrounding tissue. These chemical factors then proceed to promote the recruitment of other immune responsive cells such as monocytes or white blood cells, which help foster the formation of a blood clot and protein-rich matrix. | 1 | Applied and Interdisciplinary Chemistry |
The total molar hold up in the nth tray Mn is considered constant.
The imbalances in the input and output flows are taken into account for in the component and the heat balance equations. | 0 | Theoretical and Fundamental Chemistry |
Protein–protein interaction networks are an important ingredient for the system-level understanding of cellular processes.
Such networks can be used for filtering and assessing functional genomics data and for providing an intuitive platform for annotating structural, functional and evolutionary properties of proteins.
Exploring the predicted interaction networks can suggest new directions for future experimental research and provide cross-species predictions for efficient interaction mapping. | 1 | Applied and Interdisciplinary Chemistry |
Research centered on three plasma confinement designs; the stellarator headed by Lyman Spitzer at the Princeton Plasma Physics Laboratory, the toroidal pinch or Perhapsatron led by James Tuck at the Los Alamos National Laboratory and the magnetic mirror devices at the Livermore National Laboratory led by Richard F. Post. By June, 1954 a preliminary study had been completed for a full scale "Model D" stellarator that would be over long and produce 5,000 MW of electricity at a capital cost of $209 per kilowatt. However, each concept encountered unanticipated problems, in the form of plasma instabilities that prevented the requisite temperatures and pressures from being achieved, and it eventually became clear that sustained hydrogen fusion would not be developed quickly. Strauss left AEC in 1958 and his successor did not share Strauss' enthusiasm for fusion research. Consequently, Project Sherwood was relegated from a crash program to one that concentrated on basic research. | 0 | Theoretical and Fundamental Chemistry |
Fluorine-19 nuclear magnetic resonance spectroscopy (fluorine NMR or F NMR) is an analytical technique used to detect and identify fluorine-containing compounds. F is an important nucleus for NMR spectroscopy because of its receptivity and large chemical shift dispersion, which is greater than that for proton nuclear magnetic resonance spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
The biochemical systems equation is a compact equation of nonlinear differential equations for describing a kinetic model for any network of coupled biochemical reactions and transport processes.
The equation is expressed in the following form:
The notation for the dependent variable x varies among authors. For example, some authors use s, indicating species. x is used here to match the state space notation used in control theory but either notation is acceptable.
is the stoichiometry matrix which is an by matrix of stoichiometry coefficient. is the number of species and the number of biochemical reactions. The notation for is also variable. In constraint-based modeling the symbol tends to be used to indicate stoichiometry. However in biochemical dynamic modeling and sensitivity analysis, tends to be in more common use to indicate number. In the chemistry domain, the symbol used for the stoichiometry matrix is highly variable though the symbols S and N have been used in the past.
is an n-dimensional column vector of reaction rates, and is a p-dimensional column vector of parameters. | 1 | Applied and Interdisciplinary Chemistry |
Neurochemical Research is a monthly peer-reviewed scientific journal covering neurochemistry. It was established in 1976 and is published by Springer Science+Business Media. The editor-in-chief is Arne Schousboe (University of Copenhagen). | 1 | Applied and Interdisciplinary Chemistry |
Environmental engineering law is a profession that requires an expertise in both environmental engineering and law. This field includes professionals with both a legal and environmental engineering education. This dual educational requirement is typically satisfied through an ABET accredited degree in environmental engineering and an ABA accredited law degree. Likewise, this profession requires both licensure in professional environmental engineering and admittance to one bar.
Environmental engineering law is the professional application of law and engineering principles to improve the environment (air, water, and/or land resources), to provide healthy water, air, and land for human habitation and for other organisms, and to remediate polluted sites. Environmental engineering lawyers seek to promote the advancement of technical engineering knowledge in the legal profession and to enhance informed legal analysis of complex environmental matters. | 1 | Applied and Interdisciplinary Chemistry |
McIlvaine buffer is a buffer solution composed of citric acid and disodium hydrogen phosphate, also known as citrate-phosphate buffer. It was introduced in 1921 by the United States agronomist Theodore Clinton McIlvaine (1875–1959) from West Virginia University, and it can be prepared in pH 2.2 to 8 by mixing two stock solutions. | 1 | Applied and Interdisciplinary Chemistry |
The Embeden–Meyerhof pathway and the Krebs cycle are the centre of metabolism in nearly all bacteria and eukaryotes. They provide not only energy but also precursors for biosynthesis of macromolecules that make up living systems. | 1 | Applied and Interdisciplinary Chemistry |
The reactivity of chloroformates and acyl chlorides are similar. Representative reactions are:
* Reaction with amines to form carbamates:
:ROC(O)Cl + HNR → ROC(O)-N(H)R + HCl
* Reaction with alcohols to form carbonate esters:
:ROC(O)Cl + HOR → ROC(O)-OR + HCl
* Reaction with carboxylic acids to form mixed anhydrides:
Typically these reactions would be conducted in the presence of a base which serves to absorb the HCl.
Alkyl chloroformate esters degrate to give the alkyl chloride, with retention of configuration:
The reaction is proposed to proceed via a substitution nucleophilic internal mechanism. | 0 | Theoretical and Fundamental Chemistry |
FIDYST simulates the dynamics of elastic, line shaped objects in a very general way. Hence, there is a broad spectrum of different applications for FIDYST. Of particular importance are production processes of technical textiles
With FIDYST engineers simulate
* spunbond processes,
* meltblown processes, and
* airlay processes.
The simulations of the fiber dynamics are used to optimize the geometry of the production plant and the operating conditions. Goal of the optimization is an improved quality of the final product and reduced energy and raw material consumption at the same time.
FIDYST runs under Linux and Windows. | 1 | Applied and Interdisciplinary Chemistry |
A sculpture titled Bamboozle, by Jacobus Verhoeff and his son Tom Verhoeff, is in the form of a fragment of the Laves graph, with its vertices represented by multicolored interlocking acrylic triangles. It was installed in 2013 at the Eindhoven University of Technology. | 0 | Theoretical and Fundamental Chemistry |
Polypharmacology is the design or use of pharmaceutical agents that act on multiple targets or disease pathways.
Despite scientific advancements and an increase of global R&D spending, drugs are frequently withdrawn from markets. This is primarily due to their side effects or toxicities. Drug molecules often interact with multiple targets and the unintended drug-target interactions can cause side effects. Polypharmacology remains to be one of the major challenges in drug development, and it opens novel avenues to rationally design the next generation of more effective but less toxic therapeutic agents. Polypharmacology suggests that more effective drugs can be developed by specifically modulating multiple targets. It is generally thought that complex diseases such as cancer and central nervous system diseases may require complex therapeutic approaches. In this respect, a drug that "hits" multiple sensitive nodes belonging to a network of interacting targets offers the potential for higher efficacy and may limit drawbacks generally arising from the use of a single-target drug or a combination of multiple drugs. In contrast, chemical biology continues to be a reductionist discipline, still regarding chemical probes as highly selective small molecules that enable the modulation and study of one specific target. Chemical biology cannot continue to overlook the existence of polypharmacology and its urge to become a more holistic discipline that looks at the use of tool compounds from a systems perspective. The use of chemoproteomics offers strategies to develop a more holistic understanding of the proteome-wide range of targets a drug interacts with.
The primordial idea of polypharmacology was first proposed in 2004 by Bryan Roth. He reasoned that most common central nervous system disorders are polygenic in origin, and attempts to develop more effective treatments for diseases such as schizophrenia and depression by discovering drugs selective for single molecular targets (magic bullets) have been largely unsuccessful. He therefore proposed a proof of concept that designing selectively non-selective drugs (that is, magic shotguns) that interact with several molecular targets will lead to new and more effective medications for a variety of central nervous system disorders. A similar concept was independently proposed in the year of 2006 by Professor Zhiguo Wang who used the term single agent–multiple targets (SAMT) to describe the same principle as magic shotguns and his research team provided the very first experimental evidence for the feasibility, effectiveness and advantages of SAMT, specifically the complex decoy oligodeoxynucleotides technology cdODN attacking multiple target transcription factors, in the treatment of xenograft breast cancer in mice. Subsequently, Wangs team extended the SAMT to designing single agent that can act on multiple miRNAs targeting cancer cells and cardiac pacemaker channel genes and calcium channel genes as a new therapeutic approach. Wangs work is now categorized as Epigenetic Polypharmacology or Targeted Polypharmacology, a branch of Polypharmacology. In 2008, Professor Keven Shokat and his colleagues described a single compound that blocks the proliferation of tumor cells by direct inhibition of oncogenic tyrosine kinases and phosphatidylinositol-3-OH kinases and termed it multitargeted drug along with the concept of Polypharmacology. Since then, Polypharmacology has become a new branch of Pharmacology discipline and research field as well as one of the new direction and strategies for drug development. | 1 | Applied and Interdisciplinary Chemistry |
Since liquids often have different boiling points, mixtures or solutions of liquids or gases can typically be separated by distillation, using heat, cold, vacuum, pressure, or other means. Distillation can be found in everything from the production of alcoholic beverages, to oil refineries, to the cryogenic distillation of gases such as argon, oxygen, nitrogen, neon, or xenon by liquefaction (cooling them below their individual boiling points). | 0 | Theoretical and Fundamental Chemistry |
Some species release a volatile substance when attacked by a predator that can trigger flight (in aphids) or aggression (in ants, bees, termites, and wasps) in members of the same species. For example, Vespula squamosa use alarm pheromones to alert others to a threat. In Polistes exclamans, alarm pheromones are also used as an alert to incoming predators. Pheromones also exist in plants: Certain plants emit alarm pheromones when grazed upon, resulting in tannin production in neighboring plants. These tannins make the plants less appetizing to herbivores.
An alarm pheromone has been documented in a mammalian species. Alarmed pronghorn, Antilocapra americana flair their white rump hair and exposes two highly odoriferous glands that releases a compound described having the odor "reminiscent of buttered popcorn". This sends a message to other pronghorns by both sight and smell about a present danger. This scent has been observed by humans 20 to 30 meters downwind from alarmed animals. The major odour compound identified from this gland is 2-pyrrolidinone. | 1 | Applied and Interdisciplinary Chemistry |
The release of energy with the fusion of light elements is due to the interplay of two opposing forces: the nuclear force, a manifestation of the strong interaction, which holds protons and neutrons tightly together in the atomic nucleus; and the Coulomb force, which causes positively charged protons in the nucleus to repel each other. Lighter nuclei (nuclei smaller than iron and nickel) are sufficiently small and proton-poor to allow the nuclear force to overcome the Coulomb force. This is because the nucleus is sufficiently small that all nucleons feel the short-range attractive force at least as strongly as they feel the infinite-range Coulomb repulsion. Building up nuclei from lighter nuclei by fusion releases the extra energy from the net attraction of particles. For larger nuclei, however, no energy is released, because the nuclear force is short-range and cannot act across larger nuclei.
Fusion powers stars and produces virtually all elements in a process called nucleosynthesis. The Sun is a main-sequence star, and, as such, generates its energy by nuclear fusion of hydrogen nuclei into helium. In its core, the Sun fuses 620 million metric tons of hydrogen and makes 616 million metric tons of helium each second. The fusion of lighter elements in stars releases energy and the mass that always accompanies it. For example, in the fusion of two hydrogen nuclei to form helium, 0.645% of the mass is carried away in the form of kinetic energy of an alpha particle or other forms of energy, such as electromagnetic radiation.
It takes considerable energy to force nuclei to fuse, even those of the lightest element, hydrogen. When accelerated to high enough speeds, nuclei can overcome this electrostatic repulsion and be brought close enough such that the attractive nuclear force is greater than the repulsive Coulomb force. The strong force grows rapidly once the nuclei are close enough, and the fusing nucleons can essentially "fall" into each other and the result is fusion and net energy produced. The fusion of lighter nuclei, which creates a heavier nucleus and often a free neutron or proton, generally releases more energy than it takes to force the nuclei together; this is an exothermic process that can produce self-sustaining reactions.
Energy released in most nuclear reactions is much larger than in chemical reactions, because the binding energy that holds a nucleus together is greater than the energy that holds electrons to a nucleus. For example, the ionization energy gained by adding an electron to a hydrogen nucleus is —less than one-millionth of the released in the deuterium–tritium (D–T) reaction shown in the adjacent diagram. Fusion reactions have an energy density many times greater than nuclear fission; the reactions produce far greater energy per unit of mass even though individual fission reactions are generally much more energetic than individual fusion ones, which are themselves millions of times more energetic than chemical reactions. Only direct conversion of mass into energy, such as that caused by the annihilatory collision of matter and antimatter, is more energetic per unit of mass than nuclear fusion. (The complete conversion of one gram of matter would release of energy.) | 0 | Theoretical and Fundamental Chemistry |
In organoboron chemistry, the Brellochs reaction provides a way to generate the monocarboranes. The use of acetylenes to insert two carbons into boron hydrides is well established. The Brellochs method uses formaldehyde to insert single carbon atoms into boron hydrides.
Illustrative is the synthesis of CBH from commercially available decaborane.
:BH + CHO + 2 OH + HO → CBH + B(OH) + H
Oxidation of the arachno anion gives nido-6-CBH. Base degradation of the latter gives arachno-4-CBH. | 0 | Theoretical and Fundamental Chemistry |
The Folin–Wu and the Somogyi–Nelson methods are both based on the same principles. In the first step, glucose (or a reducing sugar) is oxidised using a solution of Cu(II) ion, which is reduced to Cu(I) by the process. In the second step, the Cu(I) ions are then oxidised back to Cu(II) using a colourless hetero-polymolybdate complex, which is, in the process, reduced to give the characteristic blue colour. Finally the absorption of the hetero-poly molybdenum blue is measured using a colorimeter and compared to standards prepared from reacting sugar solutions of known concentration, to determine the amount of reducing-sugar present. <br />
The Folin–Wu method uses a reagent that contains sodium tungstate. The exact nature of the blue complex in this procedure is not known.<br />
The Somogyi-Nelson method uses an arsenomolybdate complex formed by the reaction of ammonium molybdate, (NH) MoO, with sodium arsenate, NaHAsO. | 0 | Theoretical and Fundamental Chemistry |
At the end of the nozzle, the steam has very high velocity, but at less than atmospheric pressure, drawing in cold water which becomes entrained in the stream, where the steam condenses into droplets of water in a converging duct. | 1 | Applied and Interdisciplinary Chemistry |
Pneumatic bladders, known as dunnage bags, are used to stabilize cargo within a container.
Pneumatic bladders are used in medical research.
Leading edge inflatable kites use pneumatic bladders restrained by a fabric case; the bladder is selected slightly larger than the case, so that at operational inflation the bladder is not stressed while the case defines the final shape of the leading edge. Many of the wing's airfoil ribs are similarly bladdered. | 1 | Applied and Interdisciplinary Chemistry |
Audio compact cassettes use magnetic tape of three major types which differ in fundamental magnetic properties, the level of bias applied during recording, and the optimal time constant of replay equalization. Specifications of each type were set in 1979 by the International Electrotechnical Commission (IEC): Type I (IEC I, ferric or normal tapes), Type II (IEC II, or chrome tapes), Type III (IEC III, ferrichrome or ferrochrome), and Type IV (IEC IV, or metal tapes). Type 0 was a non-standard designation for early compact cassettes that did not conform to IEC specification.
By the time the specifications were introduced, Type I included pure gamma ferric oxide formulations, Type II included ferricobalt and chromium(IV) oxide formulations, and Type IV included metal particle tapes—the best-performing, but also the most expensive. Double-layer Type III tape formulations, advanced by Sony and BASF in the 1970s, never gained substantial market presence.
In the 1980s the lines between three types blurred. Panasonic developed evaporated metal tapes that could be made to match any of the three IEC types. Metal particle tapes migrated to Type II and Type I, ferricobalt formulations migrated to Type I. By the end of the decade performance of the best Type I ferricobalt tapes (superferrics) approached that of Type IV tapes; performance of entry-level Type I tapes gradually improved until the very end of compact cassette production. | 0 | Theoretical and Fundamental Chemistry |
Since their discovery in the 1970s aryl onium salts, more specifically iodonium and sulfonium salts, have received much attention and have found many industrial applications. Other less common onium salts include ammonium and phosphonium salts.
A typical onium compound used as a photoinitiator contains two or three arene groups for iodonium and sulfonium respectively. Onium salts generally absorb short wavelength light in the UV region spanning from 225300 nm. One characteristic that is crucial to the performance of the onium photoinitiators is that the counter anion is non-nucleophilic. Since the Brønsted acid generated during the initiation step is considered the active initiator for polymerization, there is a termination route where the counter ion of the acid could act as the nucleophile instead of a functional groups on the oligomer. Common counter anions include , , and . There is an indirect relationship between the size of the counter ion and percent conversion. | 0 | Theoretical and Fundamental Chemistry |
A 1995 review study found that there is no clinical benefit to the use of CoQ in the treatment of periodontal disease. | 1 | Applied and Interdisciplinary Chemistry |
In 1965, a paper was published by two researchers of the Scientific Laboratory at the Ford Motor Company, P. D. Maker and R. W. Terhune, in which the CARS phenomenon was reported for the first time. Maker and Terhune used a pulsed ruby laser to investigate the third order response of several materials. They first passed the ruby beam of frequency ω through a Raman shifter to create a second beam at ω-ω, and then directed the two beams simultaneously onto the sample. When the pulses from both beams overlapped in space and time, the Ford researchers observed a signal at ω+ω, which is the blue-shifted CARS signal. They also demonstrated that the signal increases significantly when the difference frequency ω between the incident beams matches a Raman frequency of the sample. Maker and Terhune called their technique simply three wave mixing experiments. The name coherent anti-Stokes Raman spectroscopy was assigned almost ten years later, by Begley et al. at Stanford University in 1974. Since then, this vibrationally sensitive nonlinear optical technique has been commonly known as CARS. | 0 | Theoretical and Fundamental Chemistry |
Knowledge of which genes (when non-functional) cause which disorders will simplify diagnosis of patients and provide insights into the functional characteristics of the mutation. The advent of modern-day high-throughput sequencing technologies combined with insights provided from the growing field of genomics is resulting in more rapid disease gene identification, thus allowing scientists to identify more complex mutations. | 1 | Applied and Interdisciplinary Chemistry |
At thermodynamic equilibrium, the negative-one-third of the trace of the Cauchy stress tensor is often identified with the thermodynamic pressure,
which depends only on equilibrium state variables like temperature and density (equation of state). In general, the trace of the stress tensor is the sum of thermodynamic pressure contribution and another contribution which is proportional to the divergence of the velocity field. This coefficient of proportionality is called volume viscosity. Common symbols for volume viscosity are and .
Volume viscosity appears in the classic Navier-Stokes equation if it is written for compressible fluid, as described in most books on general hydrodynamics and acoustics.
where is the shear viscosity coefficient and is the volume viscosity coefficient. The parameters and were originally called the first and bulk viscosity coefficients, respectively. The operator is the material derivative. By introducing the tensors (matrices) , and (where e is a scalar called dilation, and is the identity tensor), which describes crude shear flow (i.e. the strain rate tensor), pure shear flow (i.e. the deviatoric part of the strain rate tensor, i.e. the shear rate tensor) and compression flow (i.e. the isotropic dilation tensor), respectively,
the classic Navier-Stokes equation gets a lucid form.
Note that the term in the momentum equation that contains the volume viscosity disappears for an incompressible flow because there is no divergence of the flow, and so also no flow dilation e to which is proportional:
So the incompressible Navier-Stokes equation can be simply written:
In fact, note that for the incompressible flow the strain rate is purely deviatoric since there is no dilation (e=0).
In other words, for an incompressible flow the isotropic stress component is simply the pressure:
and the deviatoric (shear) stress is simply twice the product between the shear viscosity and the strain rate (Newton's constitutive law):
Therefore, in the incompressible flow the volume viscosity plays no role in the fluid dynamics.
However, in a compressible flow there are cases where , which are explained below. In general, moreover, is not just a property of the fluid in the classic thermodynamic sense, but also depends on the process, for example the compression/expansion rate. The same goes for shear viscosity. For a Newtonian fluid the shear viscosity is a pure fluid property, but for a non-Newtonian fluid it is not a pure fluid property due to its dependence on the velocity gradient. Neither shear nor volume viscosity are equilibrium parameters or properties, but transport properties. The velocity gradient and/or compression rate are therefore independent variables together with pressure, temperature, and other state variables. | 1 | Applied and Interdisciplinary Chemistry |
The mechanisms of carcinogenesis are not completely clear in humans. NMOR and its metabolites may induce DNA damage by directly forming reactive oxygen species or compounds which crosslink DNA. In a rat model in 2013, it was observed that NMOR is hydroxylated, probably by a P450 enzyme, alpha to the N-nitroso moiety. This then decomposes into a diazonium-containing aldehyde which is capable of crosslinking DNA.
Endogenous synthesis from morpholine in the digestive system is observed. NMOR can be generated from N-nitrosating species formed by salivary nitrite and stomach acid, potentially leading to more damage in individuals with acid reflux. H. pylori does not induce NMOR formation in vitro, though this has yet to be confirmed in vivo.
NMOR is in fact used to generate liver cancer models in rats. Along with N-diethylnitrosamine, it is the gold standard for producing hepatocarcinoma with 100% lung metastasis. | 0 | Theoretical and Fundamental Chemistry |
According to a 2014 review in the New England Journal of Medicine stated that a ferritin level below 30 ng/mL indicates iron deficiency, while a level below 10 ng/mL indicates iron-deficiency anemia. A 2020 World Health Organization guideline states that ferritin indicates iron deficiency below 12 ng/mL in apparently-healthy children under 5 and 15 ng/mL in apparently-healthy individuals of 5 and over.
Some studies suggest that women with fatigue and ferritin below 50 ng/mL see reduced fatigue after iron supplementation.
In the setting of anemia, low serum ferritin is the most specific lab finding for iron-deficiency anemia. However it is less sensitive, since its levels are increased in the blood by infection or any type of chronic inflammation, and these conditions may convert what would otherwise be a low level of ferritin from lack of iron, into a value in the normal range. For this reason, low ferritin levels carry more information than those in the normal range. A falsely low blood ferritin (equivalent to a false positive test) is very uncommon, but can result from a hook effect of the measuring tools in extreme cases.
Low ferritin may also indicate hypothyroidism, vitamin C deficiency or celiac disease.
Low serum ferritin levels are seen in some patients with restless legs syndrome, not necessarily related to anemia, but perhaps due to low iron stores short of anemia.
Vegetarianism is not a cause of low serum ferritin levels, according to the American Dietetic Association's position in 2009: "Incidence of iron-deficiency anemia among vegetarians is similar to that of non-vegetarians. Although vegetarian adults have lower iron stores than non-vegetarians, their serum ferritin levels are usually within the normal range." | 1 | Applied and Interdisciplinary Chemistry |
The syndrome primarily affects young males. Preliminary studies suggest that prevalence may be 1.8 per 10,000 live male births. 50% of those affected do not live beyond 25 years of age, with deaths attributed to the impaired immune function. | 1 | Applied and Interdisciplinary Chemistry |
In May the FDA approved Vyjuvek for the treatment of wounds in patients with dystrophic epidermolysis bullosa (DEB) which is applied as a topical gel that delivers a herpes-simplex virus type 1 (HSV-1) vector encoding the collagen type VII alpha 1 chain (COL7A1) gene that is dysfunctional on those affected by DEB . One trial found 65% of the Vyjuvek-treated wounds completely closed while only 26% of the placebo-treated at 24 weeks. It has been also reported its use as a eyedrops for a patient with DEB that had vision loss due to the widespread blistering with good results.
In June the FDA gave an accelerated approval to Elevidys for Duchenne muscular dystrophy (DMD) only for boys 4 to 5 years old as they are more likely to benefit from the therapy which consists of one-time intravenous infusion of a virus (AAV rh74 vector) that delivers a functioning “microdystrophin” gene (138 kDa) into the muscle cells to act in place of the normal dystrophin (427 kDa) that is found mutated in this disease.
In July it was reported that it had been developed a new method to affect genetic expressions through direct current. | 1 | Applied and Interdisciplinary Chemistry |
Pempidine is a ganglion-blocking drug, first reported in 1958 by two research groups working independently, and introduced as an oral treatment for hypertension. | 0 | Theoretical and Fundamental Chemistry |
The essential components of a spectroradiometric system are as follows:
*Input optics that gather the electromagnetic radiation from the source (Diffusers, Lenses, Fiber optic light guides)
*An entrance slit, determines how much light will enter the spectrometer. A smaller slit with have greater resolution, but less overall sensitivity
*Order sorting filters for reduction of second-order effects
*Collimator directs the light to the Grating or prism
*A grating or prism for dispersion of the light
*Focusing optics to align the light onto the Detector
*A detector, CMOS sensor or CCD array
*A control and logging system to define data and store it. | 0 | Theoretical and Fundamental Chemistry |
Agmatine, also known as 4-aminobutyl-guanidine, was discovered in 1910 by Albrecht Kossel. It is a chemical substance which is naturally created from the amino acid arginine. Agmatine has been shown to exert modulatory action at multiple molecular targets, notably: neurotransmitter systems, ion channels, nitric oxide (NO) synthesis and polyamine metabolism and this provides bases for further research into potential applications. | 1 | Applied and Interdisciplinary Chemistry |
* Cry1 and Cry2 – Cryptochromes are a class of blue light sensitive flavoproteins found in plants and animals. Cry1 and Cry2 code for the proteins CRY1 and CRY2. In Drosophila, CRY1 and CRY2 bind to TIM, a circadian gene that is a component of the transcription-translation negative feedback loop, in a light dependent fashion and blocks its function. In mammals, CRY1 and CRY2 are light independent and function to inhibit the CLOCK-BMAL1 dimer of the circadian clock which regulates cycling of Per1 transcription.
* Bmal1 – Bmal1 also known as ARNTL or Aryl hydrocarbon receptor nuclear translocator-like, encodes a protein that forms a heterodimer with the CLOCK protein. This heterodimer binds to E-box enhancers found in the promoter regions of many genes such as Cry1 and Cry2 and Per1-3, thereby activating transcription. The resulting proteins translocate back into the nucleus and act as negative regulators by interacting with CLOCK and/or BMAL1 inhibiting transcription.
* Clock – Clock, also known as Circadian Locomotor Output Cycles Kaput, is a transcription factor in the circadian pacemaker of mammals. It affects both the persistence and period of circadian rhythms by its interactions with the gene Bmal1. For more information, refer to Bmal1.
* Per genes – There are three different per genes, also known as Period genes, (per 1, per 2, and per 3) that are related by sequence in mice. Transcription levels for mPer1 increase in the late night before subjective dawn and is followed by increases in the levels of mPer3 and then by mPer2. mPer1 peaks at CT 4-6, mPer3 at CT 4 and 8 and mPer2 at CT 8. mPer1 is necessary for phase shifts induced by light or glutamate release. mPer 2 and mPer3 are involved in resetting the circadian clock to environmental light cues. | 1 | Applied and Interdisciplinary Chemistry |
At water-current speeds exceeding one foot per second, the pneumatic barrier no longer functions effectively, limiting deployable sites. | 1 | Applied and Interdisciplinary Chemistry |
In order to derive the Rayleigh–Kuo criterion, some assumptions are made on the fluids properties. We consider a nondivergent, two-dimensional barotropic fluid. The fluid has a mean zonal flow direction which can vary in the meridional direction. On this mean flow, some small perturbations are imposed in both the zonal and meridional direction: and . The perturbations need to be small in order to linearize the vorticity equation. Vertical motion and divergence and convergence of the fluid are neglected. When taking into account these factors, a similar result would have been obtained with only a small shift in the position of the criterion within the velocity profile.
The derivation of the Kuo criterion will be done within the domain . On the northern and southern boundary of this domain, the meridional fluid is zero. | 1 | Applied and Interdisciplinary Chemistry |
The International Institute of Refrigeration (IIR) (also known, in French, as the Institut International du Froid (IIF)), is an independent intergovernmental science and technology-based organization which promotes knowledge of refrigeration and associated technologies and applications on a global scale that improve quality of life in a cost-effective and environmentally sustainable manner, including:
* Food quality and safety from farm to consumer
* Comfort in homes and commercial buildings
* Health products and services
* Low temperature technology and liquefied gas technology
* Energy efficiency
* Use of non-ozone-depleting and low global warming refrigerants in a safe manner.
Its scientific and technical activities are coordinated by ten commissions which are divided into five distinct sections. | 0 | Theoretical and Fundamental Chemistry |
CellCognition (Version 1.0.1) was first released in December 2009 by scientists from the Gerlich Lab and the Buhmann group at the Swiss Federal Institute of Technology Zürich and the Ellenberg Lab at the European Molecular Biology Laboratory Heidelberg. The latest release is 1.6.1 and the software is developed and maintained by the Gerlich Lab at the Institute of Molecular Biotechnology. | 1 | Applied and Interdisciplinary Chemistry |
Color–flavor locking (CFL) is a phenomenon that is expected to occur in ultra-high-density strange matter, a form of quark matter. The quarks form Cooper pairs, whose color properties are correlated with their flavor properties in a one-to-one correspondence between three color pairs and three flavor pairs. According to the Standard Model of particle physics, the color-flavor-locked phase is the highest-density phase of three-flavor colored matter. | 0 | Theoretical and Fundamental Chemistry |
One class of example is the iodine clock reactions, in which an iodine species is mixed with redox reagents in the presence of starch. After a delay, a dark blue color suddenly appears due to the formation of a triiodide-starch complex.
Additional reagents can be added to some chemical clocks to build a chemical oscillator. For example, the Briggs–Rauscher reaction is derived from an iodine clock reaction by adding perchloric acid, malonic acid and manganese sulfate. | 0 | Theoretical and Fundamental Chemistry |
Buoyant density of the majority of DNA is 1.7g/cm which is equal to the density of 6M CsCl solution. Buoyant density of DNA changes with its GC content. The term "satellite DNA" refers to small bands of repetitive DNA sequences with distinct base composition floating above (A+T rich) or below (G+C rich) the main component DNA. | 0 | Theoretical and Fundamental Chemistry |
In the UK, the Pharmaceutical Price Regulation Scheme is intended to ensure that the National Health Service is able to purchase drugs at reasonable prices. The prices are negotiated between the Department of Health, acting with the authority of Northern Ireland and the UK Government, and the representatives of the Pharmaceutical industry brands, the Association of the British Pharmaceutical Industry (ABPI). For 2017 this payment percentage set by the PPRS will be 4,75%. | 1 | Applied and Interdisciplinary Chemistry |
Most conventional polymers such as polyethylene are electrical insulators, but the development of polymers containing π-conjugated bonds has led to a wealth of polymer-based semiconductors, such as polythiophenes. This has led to many applications in the field of organic electronics. | 0 | Theoretical and Fundamental Chemistry |
An increased thyroxine-binding globulin results in an increased total thyroxine and total triiodothyronine without an actual increase in hormonal activity of thyroid hormones.
Reference ranges: | 1 | Applied and Interdisciplinary Chemistry |
Inverted cucurbiturils or iCB[x] are CB analogues with one glycoluril repeating unit inverted. In this unit the methine protons actually point into the cavity and this makes the cavity less spacious. Inverted cucurbiturils form as a side-product in CB-forming reactions, with yields between 2 and 0.4%. Isolation of this type of CB compound is possible because it is more difficult to form inclusion compounds that ordinarily form with regular CBs. Inverted cucurbiturils are believed to be the kinetically controlled reaction products because the heating of iCB[6] in acidic medium results in a mixture of CB[5], CB[6] and CB[7] in a 24:13:1 ratio.
A cucurbituril cut in half along the equator is called a hemicucurbituril. | 0 | Theoretical and Fundamental Chemistry |
The conductivity of a solution is highly temperature dependent, so it is important either to use a temperature compensated instrument, or to calibrate the instrument at the same temperature as the solution being measured. Unlike metals, the conductivity of common electrolytes typically increases with increasing temperature.
Over a limited temperature range, the way temperature affects the conductivity of a solution can be modeled linearly using the following formula:
where
:T is the temperature of the sample,
:T is the calibration temperature,
:σ is the electrical conductivity at the temperature T,
:σ,
:α is the temperature compensation gradient of the solution.
The temperature compensation gradient for most naturally occurring samples of water is about 2%/°C; however it can range between 1 and 3%/°C. The compensation gradients for some common water solutions are listed in the table below. | 0 | Theoretical and Fundamental Chemistry |
Johan August Arfwedson (12 January 1792 – 28 October 1841) was a Swedish chemist who discovered the chemical element lithium in 1817 by isolating it as a salt. | 1 | Applied and Interdisciplinary Chemistry |
In some cases it is desirable to soften hard water. Most detergents contain ingredients that counteract the effects of hard water on the surfactants. For this reason, water softening is often unnecessary. Where softening is practised, it is often recommended to soften only the water sent to domestic hot water systems to prevent or delay inefficiencies and damage due to scale formation in water heaters. A common method for water softening involves the use of ion-exchange resins, which replace ions like Ca by twice the number of mono cations such as sodium or potassium ions.
Washing soda (sodium carbonate, NaCO) is easily obtained and has long been used as a water softener for domestic laundry, in conjunction with the usual soap or detergent.
Water that has been treated by a water softening may be termed softened water. In these cases, the water may also contain elevated levels of sodium or potassium and bicarbonate or chloride ions. | 0 | Theoretical and Fundamental Chemistry |
LFTs derive from paper chromatography, which was developed in 1943 by Martin and Synge, and elaborated in 1944 by Consden, Gordon and Martin. There was an explosion of activity in this field after 1945. The ELISA technology was developed in 1971. A set of LFT patents, including the litigated US 6,485,982 described below, were filed by Armkel LLC starting in 1988. | 1 | Applied and Interdisciplinary Chemistry |
A variety of evaporation pans are used throughout the world. There are formulas for converting from one type of pan to another and to measures representative of the environment. Also, research has been done about the installation practices of evaporation pans so that they can make more reliable and repeatable measurements. | 1 | Applied and Interdisciplinary Chemistry |
The alkoxide ion and its salts react with primary alkyl halides in an S2 reaction to form an ether via the Williamson Ether Synthesis. | 0 | Theoretical and Fundamental Chemistry |
As early as 1913, Bohr's research on electronic structure led physicists such as Johannes Rydberg to extrapolate the properties of undiscovered elements heavier than uranium. Many agreed that the next noble gas after radon would most likely have the atomic number 118, from which it followed that the transition series in the seventh period should resemble those in the sixth. Although it was thought that these transition series would include a series analogous to the rare-earth elements, characterized by filling of the 5f shell, it was unknown where this series began. Predictions ranged from atomic number 90 (thorium) to 99, many of which proposed a beginning beyond the known elements (at or beyond atomic number 93). The elements from actinium to uranium were instead believed to form part of a fourth series of transition metals because of their high oxidation states; accordingly, they were placed in groups 3 through 6.
In 1940, neptunium and plutonium were the first transuranic elements to be discovered; they were placed in sequence beneath rhenium and osmium, respectively. However, preliminary investigations of their chemistry suggested a greater similarity to uranium than to lighter transition metals, challenging their placement in the periodic table. During his Manhattan Project research in 1943, American chemist Glenn T. Seaborg experienced unexpected difficulties in isolating the elements americium and curium, as they were believed to be part of a fourth series of transition metals. Seaborg wondered if these elements belonged to a different series, which would explain why their chemical properties, in particular the instability of higher oxidation states, were different from predictions. In 1945, against the advice of colleagues, he proposed a significant change to Mendeleev's table: the actinide series.
Seaborgs actinide concept of heavy element electronic structure proposed that the actinides form an inner transition series analogous to the rare-earth series of lanthanide elements—they would comprise the second row of the f-block (the 5f series), in which the lanthanides formed the 4f series. This facilitated chemical identification of americium and curium, and further experiments corroborated Seaborgs hypothesis; a spectroscopic study at the Los Alamos National Laboratory by a group led by American physicist Edwin McMillan indicated that 5f orbitals, rather than 6d orbitals, were indeed being filled. However, these studies could not unambiguously determine the first element with 5f electrons and therefore the first element in the actinide series; it was thus also referred to as the "thoride" or "uranide" series until it was later found that the series began with actinium.
In light of these observations and an apparent explanation for the chemistry of transuranic elements, and despite fear among his colleagues that it was a radical idea that would ruin his reputation, Seaborg nevertheless submitted it to Chemical & Engineering News and it gained widespread acceptance; new periodic tables thus placed the actinides below the lanthanides. Following its acceptance, the actinide concept proved pivotal in the groundwork for discoveries of heavier elements, such as berkelium in 1949. It also supported experimental results for a trend towards +3 oxidation states in the elements beyond americium—a trend observed in the analogous 4f series. | 1 | Applied and Interdisciplinary Chemistry |
In theoretical chemistry, Specific ion Interaction Theory (SIT theory) is a theory used to estimate single-ion activity coefficients in electrolyte solutions at relatively high concentrations. It does so by taking into consideration interaction coefficients between the various ions present in solution. Interaction coefficients are determined from equilibrium constant values obtained with solutions at various ionic strengths. The determination of SIT interaction coefficients also yields the value of the equilibrium constant at infinite dilution. | 0 | Theoretical and Fundamental Chemistry |
The protein targeting warhead, E3 ligase, and linker must all be considered for PROTAC development. Formation of a ternary complex between the protein of interest, PROTAC, and E3 ligase may be evaluated to characterize PROTAC activity because it often leads to ubiquitination and subsequent degradation of the targeted protein. A hook effect is commonly observed with high concentrations of PROTACs due to the bifunctional nature of the degrader.
Currently, pVHL and CRBN have been used in preclinical trials as E3 ligases. However, there still remains hundreds of E3 ligases to be explored, with some giving the opportunity for cell specificity. | 1 | Applied and Interdisciplinary Chemistry |
In humans, intergenic regions comprise about 50% of the genome, whereas this number is much less in bacteria (15%) and yeast (30%).
As with most other non-coding DNA, the GC-content of intergenic regions vary considerably among species. For example in Plasmodium falciparum, many intergenic regions have an AT content of 90%. | 1 | Applied and Interdisciplinary Chemistry |
Although it is a relatively immature area of research, it appears that heterotrimeric G-proteins may also take part in non-GPCR signaling. There is evidence for roles as signal transducers in nearly all other types of receptor-mediated signaling, including integrins, receptor tyrosine kinases (RTKs), cytokine receptors (JAK/STATs), as well as modulation of various other "accessory" proteins such as GEFs, guanine-nucleotide dissociation inhibitors (GDIs) and protein phosphatases. There may even be specific proteins of these classes whose primary function is as part of GPCR-independent pathways, termed activators of G-protein signalling (AGS). Both the ubiquity of these interactions and the importance of Gα vs. Gβγ subunits to these processes are still unclear. | 1 | Applied and Interdisciplinary Chemistry |
Biological processes that fractionate Cu isotopes are not well-understood, but play an important role in driving the δCu values of materials observed in the marine and terrestrial environments. The natural Cu/Cu varies according to coppers redox form and the ligand to which copper binds. Oxidized Cu preferentially coordinates with hard donor ligands (e.g., N- or O-containing ligands), while reduced Cu preferentially coordinates with soft donor ligands (e.g., S-containing ligands). As Cu is preferentially oxidized over Cu, these isotopes tend to coordinate with hard and soft donor ligands, respectively. Cu isotopes can fractionate upon Cu-bacteria interactions from processes that include Cu adsorption to cells, intracellular uptake, metabolic regulation and redox speciation. Fractionation of Cu isotopes upon adsorption to cellular walls appears to depend on the surface functional groups that Cu complexes with, and can span positive and negative values. Furthermore, bacteria preferentially incorporate the lighter Cu isotope intracellularly and into proteins. For example, E. coli, B. subtilis and a natural consortia of microbes sequestered Cu with apparent fractionations (εCu) ranging from ~-1.0 to -4.4‰. Additionally, fractionation of Cu upon incorporation into the apoprotein of azurin was ~-1‰ in P. aeruginosa, and -1.5‰ in E. coli', while εCu values of Cu incorporation into Cu-metallothionein and Cu-Zn-SOD in yeast were -1.7 and -1.2‰, respectively. | 0 | Theoretical and Fundamental Chemistry |
The radicle is the first part of a seedling (a growing plant embryo) to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil (the shoot emerges from the plumule) where it absorbs more water. Most part of the seed is stored energy so nutrients are not essential during the first days for the seedling. | 0 | Theoretical and Fundamental Chemistry |
In total, the other six LLFPs, in thermal reactor spent fuel, initially release only a bit more than 10% as much energy per unit time as Tc-99 for U-235 fission, or 25% as much for 65% U-235+35% Pu-239. About 1000 years after fuel use, radioactivity from the medium-lived fission products Cs-137 and Sr-90 drops below the level of radioactivity from Tc-99 or LLFPs in general. (Actinides, if not removed, will be emitting more radioactivity than either at this point.) By about 1 million years, Tc-99 radioactivity will have declined below that of Zr-93, though immobility of the latter means it is probably still a lesser hazard. By about 3 million years, Zr-93 decay energy will have declined below that of I-129.
Nuclear transmutation is under consideration as a disposal method, primarily for Tc-99 and I-129 as these both represent the greatest biohazards and have the greatest neutron capture cross sections, although transmutation is still slow compared to fission of actinides in a reactor. Transmutation has also been considered for Cs-135, but is almost certainly not worthwhile for the other LLFPs. Given that stable Caesium-133 is also produced in nuclear fission and both it and its neutron activation product are neutron poisons, transmutation of might necessitate isotope separation. is particularly attractive for transmutation not only due to the undesirable properties of the product to be destroyed and the relatively high neutron absorption cross section but also because rapidly beta decays to stable . Ruthenium has no radioactive isotopes with half lives much longer than a year and the price of ruthenium is relatively high, making the destruction of into a potentially lucrative source of producing a precious metal from an undesirable feedstock. | 0 | Theoretical and Fundamental Chemistry |
A quasi-static thermodynamic process can be visualized by graphically plotting the path of idealized changes to the system's state variables. In the example, a cycle consisting of four quasi-static processes is shown. Each process has a well-defined start and end point in the pressure-volume state space. In this particular example, processes 1 and 3 are isothermal, whereas processes 2 and 4 are isochoric. The PV diagram is a particularly useful visualization of a quasi-static process, because the area under the curve of a process is the amount of work done by the system during that process. Thus work is considered to be a process variable, as its exact value depends on the particular path taken between the start and end points of the process. Similarly, heat may be transferred during a process, and it too is a process variable. | 0 | Theoretical and Fundamental Chemistry |
Initiation factors are proteins that bind to the small subunit of the ribosome during the initiation of translation, a part of protein biosynthesis.
Initiation factors can interact with repressors to slow down or prevent translation. They have the ability to interact with activators to help them start or increase the rate of translation. In bacteria, they are simply called IFs (i.e.., IF1, IF2, & IF3) and in eukaryotes they are known as eIFs (i.e.., eIF1, eIF2, eIF3). Translation initiation is sometimes described as three step process which initiation factors help to carry out. First, the tRNA carrying a methionine amino acid binds to the small ribosome, then binds to the mRNA, and finally joins together with the large ribosome. The initiation factors that help with this process each have different roles and structures. | 1 | Applied and Interdisciplinary Chemistry |
When the solute undergoes ionic dissociation in solution (for example a salt), the system becomes decidedly non-ideal and we need to take the dissociation process into consideration. One can define activities for the cations and anions separately ( and ).
In a liquid solution the activity coefficient of a given ion (e.g. Ca) isn't measurable because it is experimentally impossible to independently measure the electrochemical potential of an ion in solution. (One cannot add cations without putting in anions at the same time). Therefore, one introduces the notions of
;mean ionic activity
;mean ionic molality
;mean ionic activity coefficient
where represent the stoichiometric coefficients involved in the ionic dissociation process
Even though and cannot be determined separately, is a measurable quantity that can also be predicted for sufficiently dilute systems using Debye–Hückel theory. For electrolyte solutions at higher concentrations, Debye–Hückel theory needs to be extended and replaced, e.g., by a Pitzer electrolyte solution model (see external links below for examples). For the activity of a strong ionic solute (complete dissociation) we can write: | 0 | Theoretical and Fundamental Chemistry |
Although artificial pyroelectric materials have been engineered, the effect was first discovered in minerals such as tourmaline. The pyroelectric effect is also present in bone and tendon.
The most important example is gallium nitride, a semiconductor. The large electric fields in this material are detrimental in light emitting diodes (LEDs), but useful for the production of power transistors.
Progress has been made in creating artificial pyroelectric materials, usually in the form of a thin film, using gallium nitride (GaN), caesium nitrate (CsNO), polyvinyl fluorides, derivatives of phenylpyridine, and cobalt phthalocyanine. Lithium tantalate (LiTaO) is a crystal exhibiting both piezoelectric and pyroelectric properties, which has been used to create small-scale nuclear fusion ("pyroelectric fusion"). Recently, pyroelectric and piezoelectric properties have been discovered in doped hafnium oxide (HfO), which is a standard material in CMOS manufacturing. | 0 | Theoretical and Fundamental Chemistry |
Terrestrial igneous rocks commonly record crystallization at oxygen fugacities more oxidizing than the WM (wüstite-magnetite) buffer and more reduced than a log unit or so above the nickel-nickel oxide (NiNiO) buffer. Their oxidizing conditions thus are not far from those of the FMQ (fayalite-magnetite-quartz) redox buffer. Nonetheless, there are systematic differences that correlate with tectonic setting. Igneous rock emplaced and erupted in island arcs typically record oxygen fugacities 1 or more log units more oxidizing than those of the NiNiO buffer. In contrast, basalt and gabbro in non-arc settings typically record oxygen fugacities from about those of the FMQ buffer to a log unit or so more reducing than that buffer. | 0 | Theoretical and Fundamental Chemistry |
* CTDP1
* CTDSP1, CTDSP2, CTDSPL
* DULLARD
* EPM2A
* ILKAP
* MDSP
* PGAM5
* PHLPP1, PHLPP2
* PPEF1, PPEF2
* PPM1A, PPM1B, PPM1D, PPM1E, PPM1F, PPM1G, PPM1H, PPM1J, PPM1K, PPM1L, PPM1M, PPM1N
* PPTC7
* PTPMT1
* SSU72
* UBLCP1 | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, enolates are organic anions derived from the deprotonation of carbonyl () compounds. Rarely isolated, they are widely used as reagents in the synthesis of organic compounds. | 0 | Theoretical and Fundamental Chemistry |
Ductile iron pipe in the developed world is normally manufactured exclusively from recycled material including scrap steel and recycled iron. The pipe can be recycled after use.
In terms of environmental impact, several studies have compared ductile iron pipe's impact on the environment with that of other pipe materials. A study by Jeschar et al. in 1995 compared the energy use and carbon dioxide () emissions produced in manufacturing pipes of various materials including concrete, ductile iron, cast iron and PVC, based on pipes with nominal diameter of 100 mm to 500 mm. The energy consumed in manufacturing ductile iron pipe was 19.55 MJ per kg and volume of emissions released during manufacture was 1.430 kg per kg, compared to 68.30 MJ per kg of energy and 4.860 kg per kg emissions for PVC pipes, and 1.24 MJ per kg and 0.148 kg per kg for concrete pipes of the same diameter.
Another study the following year, by the Forschungsinstitut für Chemie und Umwelt, had similar findings. However, it also took the lifetime of pipes into account. This study found improved environmental performance for ductile iron pipe in terms of energy consumed and emissions produced during manufacture due to its longer life span. A more recent study, published August 2012, by Du et al., carried out a life cycle analysis on six types materials used for water and waste water pipes, including ductile iron, PVC, high-density polyethylene (HDPE) and concrete. They found that at diameters of ≤ 24 in, ductile iron pipe had the highest "global warming potential" based on emissions from manufacturing, transportation and installation. At larger diameters, ≥ 30 in, ductile iron pipe had a lower "global warming potential", while PVC had the highest.
According to a 2008 study by Koo et al., ductile iron pipe had the lowest impact on natural resource depletion, compared to HDPE pipe and PVC pipe.
In November 2012, ductile iron pipe manufactured in the United States received certification as a sustainable product from the Institute for Market Transformation to Sustainability. | 1 | Applied and Interdisciplinary Chemistry |
Sea foam, ocean foam, beach foam, or spume is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter (including proteins, lignins, and lipids) derived from sources such as the offshore breakdown of algal blooms. These compounds can act as surfactants or foaming agents. As the seawater is churned by breaking waves in the surf zone adjacent to the shore, the surfactants under these turbulent conditions trap air, forming persistent bubbles that stick to each other through surface tension.
Sea foam is a global phenomenon, and it varies depending on location and the potential influence of the surrounding marine, freshwater, and/or terrestrial environments. Due to its low density and persistence, foam can be blown by strong on-shore winds inland, towards the beach. Human activities, such as production, transport or spillage of petroleum products or detergents, can also contribute to the formation of sea foam. | 0 | Theoretical and Fundamental Chemistry |
Dark fermentation is the fermentative conversion of organic substrate to biohydrogen. It is a complex process manifested by diverse groups of bacteria, involving a series of biochemical reactions using three steps similar to anaerobic conversion. Dark fermentation differs from photofermentation in that it proceeds without the presence of light. | 1 | Applied and Interdisciplinary Chemistry |
Resistance to zanamivir has been low for both seasonal and pandemic viruses compare to oseltamivir. Molecular structure of zanamivir has a guanidino group, this group interacts with the E119 residue in the active center pocket. Resistance to zanamivir can be because of mutations that effect binding affinity between the enzyme and the inhibitor. Mutation at the E119 residue has been shown to reduce the inhibitors efficiency in vitro. | 1 | Applied and Interdisciplinary Chemistry |
The carbonate pump is sometimes referred to as the “hard tissue” component of the biological pump. Some surface marine organisms, like Coccolithophores, produce hard structures out of calcium carbonate, a form of particulate inorganic carbon, by fixing bicarbonate. This fixation of DIC is an important part of the oceanic carbon cycle.
:Ca + 2 → CaCO + CO + HO
While the biological carbon pump fixes inorganic carbon (CO) into particulate organic carbon in the form of sugar (CHO), the carbonate pump fixes inorganic bicarbonate and causes a net release of CO. In this way, the carbonate pump could be termed the carbonate counter pump. It works counter to the biological pump by counteracting the CO flux from the biological pump. | 0 | Theoretical and Fundamental Chemistry |
There are two factors that can change the temperature of a fluid during an adiabatic expansion: a change in internal energy or the conversion between potential and kinetic internal energy. Temperature is the measure of thermal kinetic energy (energy associated with molecular motion); so a change in temperature indicates a change in thermal kinetic energy. The internal energy is the sum of thermal kinetic energy and thermal potential energy. Thus, even if the internal energy does not change, the temperature can change due to conversion between kinetic and potential energy; this is what happens in a free expansion and typically produces a decrease in temperature as the fluid expands. If work is done on or by the fluid as it expands, then the total internal energy changes. This is what happens in a Joule–Thomson expansion and can produce larger heating or cooling than observed in a free expansion.
In a Joule–Thomson expansion the enthalpy remains constant. The enthalpy, , is defined as
where is internal energy, is pressure, and is volume. Under the conditions of a Joule–Thomson expansion, the change in represents the work done by the fluid (see the proof below). If increases, with constant, then must decrease as a result of the fluid doing work on its surroundings. This produces a decrease in temperature and results in a positive Joule–Thomson coefficient. Conversely, a decrease in means that work is done on the fluid and the internal energy increases. If the increase in kinetic energy exceeds the increase in potential energy, there will be an increase in the temperature of the fluid and the Joule–Thomson coefficient will be negative.
For an ideal gas, does not change during a Joule–Thomson expansion. As a result, there is no change in internal energy; since there is also no change in thermal potential energy, there can be no change in thermal kinetic energy and, therefore, no change in temperature. In real gases, does change.
The ratio of the value of to that expected for an ideal gas at the same temperature is called the compressibility factor, . For a gas, this is typically less than unity at low temperature and greater than unity at high temperature (see the discussion in compressibility factor). At low pressure, the value of always moves towards unity as a gas expands. Thus at low temperature, and will increase as the gas expands, resulting in a positive Joule–Thomson coefficient. At high temperature, and decrease as the gas expands; if the decrease is large enough, the Joule–Thomson coefficient will be negative.
For liquids, and for supercritical fluids under high pressure, increases as pressure increases. This is due to molecules being forced together, so that the volume can barely decrease due to higher pressure. Under such conditions, the Joule–Thomson coefficient is negative, as seen in the figure above.
The physical mechanism associated with the Joule–Thomson effect is closely related to that of a shock wave, although a shock wave differs in that the change in bulk kinetic energy of the gas flow is not negligible. | 0 | Theoretical and Fundamental Chemistry |
Progesterone, like pregnenolone and dehydroepiandrosterone (DHEA), belongs to an important group of endogenous steroids called neurosteroids. It can be metabolized within all parts of the central nervous system.
Neurosteroids are neuromodulators, and are neuroprotective, neurogenic, and regulate neurotransmission and myelination. The effects of progesterone as a neurosteroid are mediated predominantly through its interactions with non-nuclear PRs, namely the mPRs and PGRMC1, as well as certain other receptors, such as the σ and nACh receptors. | 0 | Theoretical and Fundamental Chemistry |
In certain situations, it is vital for the photosynthetic organism to recycle the electrons being transferred, resulting in the electron from the terminal iron-sulfur cluster F transferring back to the cytochrome b6f complex (adaptor between photosystems II and I). Utilizing the energy of P700, the cyclic pathway creates a proton gradient useful for the production of ATP, while no NADPH is produced, since the protein ferredoxin does not become reduced. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, catenation is the bonding of atoms of the same element into a series, called a chain. A chain or a ring shape may be open if its ends are not bonded to each other (an open-chain compound), or closed if they are bonded in a ring (a cyclic compound). The words to catenate and catenation reflect the Latin root catena, "chain". | 0 | Theoretical and Fundamental Chemistry |
The following tests are commonly used for geometallurgical modeling:
* Bond ball mill work index test
* Modified or comparative Bond ball mill index
* Bond rod mill work index and Bond low energy impact crushing work index
* SAGDesign test
* SMC test
* JK drop-weight test
* Point load index test
* Sag Power Index test (SPI(R))
* MFT test
* FKT, SKT, and SKT-WS tests | 1 | Applied and Interdisciplinary Chemistry |
Iminium salts hydrolyse to give the corresponding ketone or aldehyde:
Iminium cations are reduced to the amines, e.g. by sodium cyanoborohydride. Iminium cations are intermediates in the reductive amination of ketones and aldehydes.
Unsymmetrical iminium cations undergo cis-trans isomerization. The isomerization is catalyzed by nucleophiles, which add to the unsaturated carbon, breaking the C=N double bond. | 0 | Theoretical and Fundamental Chemistry |
In the field of energetics, an energy carrier is produced by human technology from a primary energy source. Only the energy sector uses primary energy sources. Other sectors of society use an energy carrier to perform useful activities (end-uses). The distinction between "Energy Carriers" (EC) and "Primary Energy Sources" (PES) is extremely important. An energy carrier can be more valuable (have a higher quality) than a primary energy source. For example 1 megajoule (MJ) of electricity produced by a hydroelectric plant is equivalent to 3 MJ of oil. Sunlight is a main source of primary energy, which can be transformed into plants and then into coal, oil and gas. Solar power and wind power are other derivatives of sunlight. Note that although coal, oil and natural gas are derived from sunlight, they are considered primary energy sources which are extracted from the earth (fossil fuels). Natural uranium is also a primary energy source extracted from the earth but does not come from the decomposition of organisms (mineral fuel). | 0 | Theoretical and Fundamental Chemistry |
The ancient name of the Étang de Berre was Stagnum Mastromela, according to Pliny the Elder (Book III [34]). | 1 | Applied and Interdisciplinary Chemistry |
The U.S. National Ambient Air Quality Standards (NAAQS, pronounced ) are limits on atmospheric concentration of six pollutants that cause smog, acid rain, and other health hazards. Established by the United States Environmental Protection Agency (EPA) under authority of the Clean Air Act (42 U.S.C. 7401 et seq.), NAAQS is applied for outdoor air throughout the country.
The six criteria air pollutants (CAP), or criteria pollutants, for which limits are set in the NAAQS are ozone (O), atmospheric particulate matter (PM/PM), lead (Pb), carbon monoxide (CO), sulfur oxides (SO), and nitrogen oxides (NO). These are typically emitted from many sources in industry, mining, transportation, electricity generation and agriculture. In many cases they are the products of the combustion of fossil fuels or industrial processes.
The National Emissions Standards for Hazardous Air Pollutants cover many other chemicals, and require the maximum achievable reduction that the EPA determines is feasible. | 1 | Applied and Interdisciplinary Chemistry |
The test relies upon a microbial ecosystem with enzymes capable of oxidizing the available organic material. Some waste waters, such as those from biological secondary sewage treatment, will already contain a large population of microorganisms acclimated to the water being tested. An appreciable portion of the waste may be utilized during the holding period prior to commencement of the test procedure. On the other hand, organic wastes from industrial sources may require specialized enzymes. Microbial populations from standard seed sources may take some time to produce those enzymes. A specialized seed culture may be appropriate to reflect conditions of an evolved ecosystem in the receiving waters. | 0 | Theoretical and Fundamental Chemistry |
Dimetcote is popular in the marine industry. The inorganic zinc coating of Dimetcote can protect metal components from moisture. | 1 | Applied and Interdisciplinary Chemistry |
In the case of the original Grätzel and O'Regan design, the cell has 3 primary parts. On top is a transparent anode made of fluoride-doped tin dioxide (SnO:F) deposited on the back of a (typically glass) plate. On the back of this conductive plate is a thin layer of titanium dioxide (TiO), which forms into a highly porous structure with an extremely high surface area. The (TiO) is chemically bound by a process called sintering. TiO only absorbs a small fraction of the solar photons (those in the UV). The plate is then immersed in a mixture of a photosensitive ruthenium-polypyridyl dye (also called molecular sensitizers) and a solvent. After soaking the film in the dye solution, a thin layer of the dye is left covalently bonded to the surface of the TiO. The bond is either an ester, chelating, or bidentate bridging linkage.
A separate plate is then made with a thin layer of the iodide electrolyte spread over a conductive sheet, typically platinum metal. The two plates are then joined and sealed together to prevent the electrolyte from leaking. The construction is simple enough that there are hobby kits available to hand-construct them. Although they use a number of "advanced" materials, these are inexpensive compared to the silicon needed for normal cells because they require no expensive manufacturing steps. TiO, for instance, is already widely used as a paint base.
One of the efficient DSSCs devices uses ruthenium-based molecular dye, e.g. [Ru(4,4-dicarboxy-2,2-bipyridine)(NCS)] (N3), that is bound to a photoanode via carboxylate moieties. The photoanode consists of 12 μm thick film of transparent 10–20 nm diameter TiO nanoparticles covered with a 4 μm thick film of much larger (400 nm diameter) particles that scatter photons back into the transparent film. The excited dye rapidly injects an electron into the TiO after light absorption. The injected electron diffuses through the sintered particle network to be collected at the front side transparent conducting oxide (TCO) electrode, while the dye is regenerated via reduction by a redox shuttle, I/I, dissolved in a solution. Diffusion of the oxidized form of the shuttle to the counter electrode completes the circuit. | 0 | Theoretical and Fundamental Chemistry |
The polyadenylation activity of GLD-2, as we previously mentioned, is stimulated by physical interaction with an RNA binding protein, GLD-3. To test whether GLD-3 might stimulate GLD-2 by recruiting it to RNA, some studies tethered C. elegans GLD-2 to mRNAs in Xenopus oocytes by using MS2 coat protein. Tethered GLD-2 adds poly(A) and stimulates translation of the mRNA, demonstrating that recruitment is sufficient to stimulate polyadenylation activity. PAP heterodimer in which GLD-2 contains the active site and GLD-3 provides RNA-binding specificity. MS2 coat protein was joined to GLD-2 to recruit it to an RNA.
Furthermore, GLD-2 activity is also important to maintain or up-regulate the abundance of many mRNAs, as the cytoplasmic polyadenylation has an essential role in activating maternal mRNA translation during early development. In vertebrates, the reaction requires CPEB, an RNA-binding protein and the poly(A) polymerase GLD-2.
The Xenopus enzyme, which exists in two closely related forms, polyadenylates RNAs to which it is tethered and enhances their translation. Likewise, it interacts with cytoplasmic polyadenylation factors, including Cleavage and polyadenylation specificity factor and CPEB, and with target mRNAs. These findings confirm and extend a recent report that a GLD-2 enzyme is the long-sought PAP responsible for cytoplasmic polyadenylation in oocytes.
In addition, the formation of long-term memory is believed to lack translational control of localized mRNAs. In mammals, dendrite mRNAs are kept in a repressed state and are activated upon repetitive stimulation. Several regulatory proteins required for translational control in early development are thought to be needed for memory formation, suggesting similar molecular mechanisms. In an experiment using Drosophila, it has been detected the enzyme responsible for poly(A) elongation in the brain and it has been demonstrated too that its activity is required specifically for long-term memory. These findings provide strong evidence that cytoplasmic polyadenylation is critical for memory formation, and that GLD2 is the responsible enzyme. | 1 | Applied and Interdisciplinary Chemistry |
The discovery of introns and the split gene architecture of the eukaryotic genes started a new era of eukaryotic biology. The question of why eukaryotic genes had fragmented genes prompted speculation and discussion almost immediately.
Ford Doolittle published a paper in 1978 in which he stated that most molecular biologists assumed that the eukaryotic genome arose from a ‘simpler’ and more ‘primitive’ prokaryotic genome rather like that of Escherichia coli. However, this type of evolution would require that introns be introduced into the coding sequences of bacterial genes. Regarding this requirement, Doolittle said, “It is extraordinarily difficult to imagine how informationally irrelevant sequences could be introduced into pre-existing structural genes without deleterious effects.” He stated “I would like to argue that the eukaryotic genome, at least in that aspect of its structure manifested as ‘genes in pieces’ is in fact the primitive original form.”
James Darnell expressed similar views in 1978. He stated, “The differences in the biochemistry of messenger RNA formation in eukaryotes compared to prokaryotes are so profound as to suggest that sequential prokaryotic to eukaryotic cell evolution seems unlikely. The recently discovered non-contiguous sequences in eukaryotic DNA that encode messenger RNA may reflect an ancient, rather than a new, distribution of information in DNA and that eukaryotes evolved independently of prokaryotes.”
However, in an apparent attempt to reconcile with the idea that RNA preceded DNA in evolution, and with the concept of the three evolutionary lineages of archea, bacteria and eukarya, both Doolittle and Darnell deviated from their original speculation in a joint paper in 1985. They suggested that the ancestor of all three groups of organisms, the ‘progenote,’ had a genes-in-pieces structure, from which all three lineages evolved. They speculated that the precellular stage had primitive RNA genes which had introns, which were reverse transcribed into DNA and formed the progenote. Bacteria and archea evolved from the progenote by losing introns, and ‘urkaryote’ evolved from it by retaining introns. Later, the eukaryote evolved from the urkaryote by evolving a nucleus and absorbing mitochondria from bacteria. Multicellular organisms then evolved from the eukaryote.
These authors predicted that the distinctions between the prokaryote and the eukaryote were so profound that the prokaryote to eukaryote evolution was not tenable, and had different origins. However, other than the speculations that the precellular RNA genes must have had introns, they did not address the key questions of intron origin. No explanations described why exons were short and introns were long, how the splice junctions originated, what the structure and sequence of the splice junctions meant, and why eukaryote genomes were large.
Around the same time that Doolittle and Darnell suggested that introns in eukaryotic genes could be ancient, Colin Blake and Walter Gilbert published their views on intron origins independently. In their view, introns originated as spacer sequences that enabled convenient recombination and shuffling of exons that encoded distinct functional domains in order to evolve new genes. Thus, new genes were assembled from exon modules that coded for functional domains, folding regions, or structural elements from preexisting genes in the genome of an ancestral organism, thereby evolving genes with new functions. They did not specify how exons or introns originated. In addition, even after many years, extensive analysis of thousands of proteins and genes showed that only extremely rarely do genes exhibit the supposed exon shuffling phenomenon. Furthermore, molecular biologists questioned the exon shuffling proposal, from a purely evolutionary view for both methodological and conceptual reasons, and, in the long run, this theory did not survive. | 1 | Applied and Interdisciplinary Chemistry |
Dielectric relaxation as a whole is the result of the movement of dipoles (dipole relaxation) and electric charges (ionic relaxation) due to an applied alternating field, and is usually observed in the frequency range 10-10 Hz. Relaxation mechanisms are relatively slow compared to resonant electronic transitions or molecular vibrations, which usually have frequencies above 10 Hz. | 0 | Theoretical and Fundamental Chemistry |
3-Butyn-1-ol was reacted with methanesulfonyl chloride and triethanolamine to produce its mesylate. The mesylate was displaced to make thiolacetate. The thiol was coupled with 3,5-dibromo(trimethylsilylethynyl)benzene to create a free alkyne. The resulting product, 3,5-(4’-thiolacetyl-1’-butynyl)-1-(trimethylsilylethynyl)-benzene, had its trimethylsilyl group removed using tetra-n-butylammonium fluoride (TBAF) and AcOH/AcO in THF. The free alkyne was then coupled with the upper body product from the earlier synthesis. This resulted in a NanoKid with protected thiol feet.
To make the NanoKid “stand’, the acetyl protecting groups were removed through the use of ammonium hydroxide in THF to create the free thiols. A gold-plated substrate was then dipped into the solution and incubated for four days. Ellipsometry was used to determine the resulting thickness of the compound, and it was determined that the NanoKid was upright on the substrate. | 1 | Applied and Interdisciplinary Chemistry |
The Bray–Liebhafsky reaction is a chemical clock first described by W. C. Bray in 1921 with the oxidation of iodine to iodate:
:5 HO + I → 2 + 2 H + 4 HO
and the reduction of iodate back to iodine:
:5 HO + 2 + 2 H → I + 5 O + 6 HO | 1 | Applied and Interdisciplinary Chemistry |
Synapses can be classified by the type of cellular structures serving as the pre- and post-synaptic components. The vast majority of synapses in the mammalian nervous system are classical axo-dendritic synapses (axon synapsing upon a dendrite), however, a variety of other arrangements exist. These include but are not limited to axo-axonic, dendro-dendritic, axo-secretory, axo-ciliary, somato-dendritic, dendro-somatic, and somato-somatic synapses.
In fact, the axon can synapse onto a dendrite, onto a cell body, or onto another axon or axon terminal, as well as into the bloodstream or diffusely into the adjacent nervous tissue. | 1 | Applied and Interdisciplinary Chemistry |
Annonins are a group of chemical compounds classified as acetogenins. They are found in the extracts of Annona seeds (A. squamosa and A. muricata). Annonin-based bioinsecticides are used to control Coleoptera (beetle) pests commonly found in stored organic cereal and beans in the country of Brazil. Other different types of annonin-based insecticides, derived from A. mucosa, fight off lepidopteran (moth) pests that infest cabbage leaves, also found in the tropical climates of Brazil. The benefit of using these bioinsecticides is their relatively low cost and no phytotoxicity. These annonin molecules act as overpowering inhibitors of complex I (NADH: ubiquinone oxidoreductase) in the electron-transport chain in the mitochondria of quarry pests. In cell membranes of these same pests, annonins also inhibit coenzyme NADH, causing these arthropods to die. | 1 | Applied and Interdisciplinary Chemistry |
Anionic surfactants contain anionic functional groups at their head, such as sulfate, sulfonate, phosphate, and carboxylates.
Prominent alkyl sulfates include ammonium lauryl sulfate, sodium lauryl sulfate (sodium dodecyl sulfate, SLS, or SDS), and the related alkyl-ether sulfates sodium laureth sulfate (sodium lauryl ether sulfate or SLES), and sodium myreth sulfate.
Others include:
* Alkylbenzene sulfonates
* Docusate (dioctyl sodium sulfosuccinate)
* Perfluorooctanesulfonate (PFOS)
* Perfluorobutanesulfonate
* Alkyl-aryl ether phosphates
* Alkyl ether phosphates
Carboxylates are the most common surfactants and comprise the carboxylate salts (soaps), such as sodium stearate. More specialized species include sodium lauroyl sarcosinate and carboxylate-based fluorosurfactants such as perfluorononanoate, perfluorooctanoate (PFOA or PFO). | 0 | Theoretical and Fundamental Chemistry |
SNIF-NMR is the official method of the OIV to determine the authentication of wine origin. It is the only method to detect C3 sugar addition (like beet sugar).
The isotopic parameters of both water and ethanol are related to the humidity and temperature of the growing region of the plant. Therefore, considerations of meteorological data of the region and of the year help to make a diagnosis. In the case of wine and fruits, the isotopic parameters of ethanol have been shown to respond even to subtle environmental variations and they efficiently characterize the region of production,.
Since 1991, an isotopic data bank is built in the Joint Research Centre of the European Commission (EC-JRC) concerning wines of all European members. The database contains several thousand entries for European wines and is maintained and updated every year. This database is accessible for all official public laboratories. Private companies involved in food and beverage controls have also collected authentic samples and built up specific data banks.
Thus, by comparing the specific natural isotope fractionation corresponding to each site of a molecule of ethanol of wine with that of a molecule known and referenced in a database. The geographical origin, botany and method of production of the ethanol molecule and thus the authenticity of wine can be checked. | 0 | Theoretical and Fundamental Chemistry |
Sulfoquinovose is rarely found in its free form in nature; rather it occurs predominantly as a glycoside, SQDG. SQDG can be deacylated to form lyso-SQDG and sulfoquinovosylglycerol (SQGro). Sulfoquinovose is obtained from SQ glycosides by the action of sulfoquinovosidases, which are glycoside hydrolases that can hydrolyse the glycosidic linkage in SQDG, or its deacylated form, sulfoquinovosyl glycerol (SQGro).
There are two main classes of sulfoquinovosidases. The first are classical glycoside hydrolases (which belong to CAZy family GH31), and is exemplified by the sulfoquinovosidase YihQ from Escherichia coli. Family GH31 sulfoquinovosidases cleave SQ glycosides with retention of configuration, initially forming α-sulfoquinovose. YihQ sulfoquinovosidase exhibits a preference for the naturally occurring 2’R-SQGro. The second class of sulfoquinovosidases are NAD-dependent enzymes (which belong to CAZy family GH188) that use an oxidoreductive mechanism to cleave both α- and β-glycosides of sulfoquinovose.
Sulfoglycolysis encoding operons often contain gene sequences encoding aldose-1-epimerases that act as sulfoquinovose mutarotases, catalyzing the interconversion of the α and β anomers of sulfoquinovose. | 1 | Applied and Interdisciplinary Chemistry |
Many solvents can lead to a sudden loss of consciousness if inhaled in large amounts. Solvents like diethyl ether and chloroform have been used in medicine as anesthetics, sedatives, and hypnotics for a long time. Many solvents (e.g. from gasoline or solvent-based glues) are abused recreationally in glue sniffing, often with harmful long-term health effects such as neurotoxicity or cancer. Fraudulent substitution of 1,5-pentanediol by the psychoactive 1,4-butanediol by a subcontractor caused the Bindeez product recall.
Ethanol (grain alcohol) is a widely used and abused psychoactive drug. If ingested, the so-called "toxic alcohols" (other than ethanol) such as methanol, 1-propanol, and ethylene glycol metabolize into toxic aldehydes and acids, which cause potentially fatal metabolic acidosis. The commonly available alcohol solvent methanol can cause permanent blindness or death if ingested. The solvent 2-butoxyethanol, used in fracking fluids, can cause hypotension and metabolic acidosis. | 1 | Applied and Interdisciplinary Chemistry |
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