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Because bacteria use the Pho regulon to maintain homeostasis of Pi, it has the added effect of being used to control other genes. Many of the other genes activated or repressed by the Pho regulon cause virulence in bacterial pathogens. Three ways that this regulon effects virulence and pathogenicity are toxin production, biofilm formation, and acid tolerance. | 1 | Applied and Interdisciplinary Chemistry |
In humans, pyrimidine rings (C, T, U) can be degraded completely to CO and NH (urea excretion). That having been said, purine rings (G, A) cannot. Instead, they are degraded to the metabolically inert uric acid which is then excreted from the body. Uric acid is formed when GMP is split into the base guanine and ribose. Guanine is deaminated to xanthine which in turn is oxidized to uric acid. This last reaction is irreversible. Similarly, uric acid can be formed when AMP is deaminated to IMP from which the ribose unit is removed to form hypoxanthine. Hypoxanthine is oxidized to xanthine and finally to uric acid. Instead of uric acid secretion, guanine and IMP can be used for recycling purposes and nucleic acid synthesis in the presence of PRPP and aspartate (NH donor). | 1 | Applied and Interdisciplinary Chemistry |
Jean Charles Galissard de Marignac was born in Geneva on 24 April 1817, to Jacob Galissard de Marignac, a judge, and Susanne Le Royer, a sister of well-known chemist and physiologist Elie Le Royer. Le Royer's pharmacy was in the same building as their home.
Marignac attended the École polytechnique in Paris with the intention of becoming a mining engineer. From 1837 to 1839, he studied at the École des mines.
The following year was spent traveling and visiting well-known scientists. Marignac worked briefly with Justus von Liebig, and with Alexandre Brongniart in the Sèvres porcelain factory. He also may have been influenced by Jöns Jacob Berzelius.
On his return, Marignac became in 1841 a professor of chemistry at the Academy of Geneva. In 1845 he was appointed professor of mineralogy as well. He held both chairs until 1878, when he resigned due to poor health. He was able to continue working in a laboratory at his house until 1884, when he became so debilitated that he could no longer work. Marignac died at Geneva on 15 April 1894.
Marignacs name is well known for the careful and exact determinations of atomic weights. Whenever possible, he used at least two independent methods to assess a sample. He carried these out for long-identified elements and for newly proposed elements. In undertaking this work he had, like Belgian chemist Jean Stas, the purpose of testing Prouts hypothesis, the idea that atomic weights are multiples of hydrogen. However, he remained more disposed than the Belgian chemist to consider the possibility that it may have some degree of validity. By establishing well-defined values for a wide variety of elements, he seriously contributed to the underlying basis of inorganic chemistry.
Throughout his life he paid great attention to the rare earths and the problem of separating and distinguishing them. In 1878 Marignac extracted ytterbium from what was supposed to be pure erbia.
In 1880 he found gadolinium and samarium in the samarskite earths.
In 1858, he pointed out the isomorphism of the fluostannates and the fluosilicates, thus settling the then vexed question of the composition of silicic acid. This research helped him to confirm the atomic weights of zirconium and titanium.
Subsequently Marignac studied the fluorides of boron, tungsten, and other elements. He prepared silicotungstic acid, one of the first examples of the complex inorganic acids.
Marignac discovered that niobium and tantalum could be separated by fractional crystallization separation of potassium heptafluorotantalate from potassium oxypentafluoroniobate monohydrate, a process which was used commercially until displaced by solvent extraction separation of the same fluorides starting in the 1950s.
In physical chemistry, he carried out extensive research on the nature and process of solutions, investigating in particular the thermal effects produced by the dilution of saline solutions, the variation of the specific heat of saline solutions with temperature and concentration, and the phenomena of liquid diffusion.
Galissard de Marignac is buried with his wife Marie, née Dominicé, and their son Edouard (1849-1871) at the Cimetière des Rois, which is considered the Pantheon of Geneva. | 1 | Applied and Interdisciplinary Chemistry |
Reduction of TaCl under an atmosphere of CO gives the salts of [Ta(CO)]. These same anions can be obtained by carbonylation of tantalum arene complexes.
A number of tantalum isocyanide complexes are also known. | 0 | Theoretical and Fundamental Chemistry |
The two-state model is a simple linear model to describe the interaction between a ligand and its receptor, but also the active receptor (R). The model uses an equilibrium dissociation constant to describe the interaction between ligand and receptor. It proposes that ligand binding results in a change in receptor state from an inactive to an active state based on the receptors conformation. A receptor in its active state will ultimately elicit its biological response. It was first described by Black and Leff in 1983 as an alternative model of receptor activation. Similar to the receptor occupancy model, the theory originated from earlier work by del Castillo & Katz on observations relating to ligand-gated ion channels. In this model, agonists and inverse agonists are thought to have selective binding affinity for the pre-existing resting and active states or can induce a conformational change to a different receptor state. Whereas antagonists have no preference in their affinity for a receptor state. The fact that receptor conformation (state) would affect binding affinity of a ligand was used to explain a mechanism of partial agonism of receptors by del Castillo & Katz in 1957 was based on their work on the action of acetylcholine at the motor endplate build on similar work by Wyman & Allen in 1951 on conformational-induced changes in hemoglobins oxygen binding affinity occurring as a result of oxygen binding. The del Castillo-Katz mechanism divorces the binding step (that can be made by agonists as well as antagonists) from the receptor activation step (that can be only exerted by agonists), describing them as two independent events. | 1 | Applied and Interdisciplinary Chemistry |
LDH is often measured in HIV patients as a non-specific marker for pneumonia due to Pneumocystis jirovecii (PCP). Elevated LDH in the setting of upper respiratory symptoms in a HIV patient suggests, but is not diagnostic for, PCP. However, in HIV-positive patients with respiratory symptoms, a very high LDH level (>600 IU/L) indicated histoplasmosis (9.33 times more likely) in a study of 120 PCP and 30 histoplasmosis patients. | 1 | Applied and Interdisciplinary Chemistry |
Research Activities in the following fields:
*Thermodynamics
*Fluid mechanics
*Chemical reaction engineering
*Chemical kinetics and catalysis
*Separation processes
*Transport phenomena
*Characterisation and synthesis of polymers
*Modelling and process control
*Chemical engineering in rheologically complex media
*Formulation and product engineering
*Bioorganic chemistry, biotechnology and bioengineering
*Photochemistry and photophysics
*Safety, health, energy and environment
*Micro- and nanotechnology | 1 | Applied and Interdisciplinary Chemistry |
Characterization of plant root exometabolites to determine how exometabolites affect Plant-growth promoting rhizobacteria.
Metabolic footprinting of yeast strains for identification of yeast strains optimal for enhancing fermentation performance and positive attributes in wine. | 1 | Applied and Interdisciplinary Chemistry |
*Alchemical elements – Primarily the four Classical elements of:
** Fire (classical element)
** Water (classical element)
** Earth (classical element)
** Air (classical element)
** For variations see: Wu Xing • Mahābhūta • Five elements (Japanese philosophy)
*Alchemy in art and entertainment
*Alkahest
*Anima mundi
*Chrysopoeia
*Filius philosophorum
*Takwin
**Homunculus
*Philosopher's stone
**Cintamani
**Elixir of life
**Panacea
*Prima materia
**Yliaster
*Septenary of the seven metals and Classical planets in Western alchemy
** Lead • tin • copper • iron • mercury • silver • gold
** Saturn • Jupiter • Venus • Mars • Mercury • Moon • Sun
*Tria Prima (three primes)
** Salt • mercury • sulfur
** Body • soul • spirit
*Unity of opposites or coincidentia oppositorum
**Hieros Gamos
**Rebis | 1 | Applied and Interdisciplinary Chemistry |
If the gene for proteorhodopsin is inserted into E. coli and retinal is given to these modified bacteria, then they will incorporate the pigment into their cell membrane and will pump H+ in the presence of light. A deep purple is representative of clearly transformed colonies, due to light absorption. Proton gradients can be used to power other membrane protein structures or used to acidify a vesicle type organelle. It was further demonstrated that the proton gradient generated by proteorhodopsin could be used to generate ATP. | 0 | Theoretical and Fundamental Chemistry |
In clinical pharmacology, a potentiator is a drug, herb, or chemical that intensifies the effects of a given drug. For example, hydroxyzine or dextromethorphan is used to get more pain relief and anxiolysis out of an equal dose of an opioid medication. The potentiation can take place at any part of the liberation, absorption, distribution, metabolism and elimination of the drug. | 0 | Theoretical and Fundamental Chemistry |
* Gold-Headed Cane Award, University of California Medical School, 1946, presented to the graduating senior who most fully personifies the qualities of a "true physician."
* Modern Medicine Award, 1954, for outstanding contributions to heart disease research.
* The Lyman Duff Lectureship Award of the American Heart Association in 1965, for research in atherosclerosis and coronary heart disease; lecture published in 1966 as "Ischemic Heart Disease, Atherosclerosis, and Longevity," in Circulation 34: 679–697.
* The Stouffer Prize (shared) 1972, for outstanding contributions to research in arteriosclerosis.
* American College of Cardiology, 1974; selection as one of twenty-five leading researchers in cardiology of the past quarter-century.
* University of California, Berkeley, Bancroft Library, 1988; announcement of the "Gofman Papers" established in the History of Science and Technology Special Collection (October 1988, Bancroftiana, No. 97: 10–11).
* Right Livelihood Award, 1992
* Honored Speaker for the Meeting of the Arteriosclerosis Section of the American Heart Association, 1993 | 0 | Theoretical and Fundamental Chemistry |
In materials science and colloidal chemistry, the term colloidal particle refers to a small amount of matter having a size typical for colloids and with a clear phase boundary. The dispersed-phase particles have a diameter between approximately 1 and 1000 nanometers. Colloids are heterogeneous in nature, invisible to the naked eye, and always move in a random zig-zag-like motion known as Brownian motion. The scattering of light by colloidal particles is known as Tyndall effect. | 0 | Theoretical and Fundamental Chemistry |
The G6P is then converted to 6-phosphogluconolactone in the presence of enzyme glucose-6-phosphate dehydrogenase (an oxido-reductase) with the presence of co-enzyme nicotinamide adenine dinucleotide phosphate (NADP). which will be reduced to nicotinamide adenine dinucleotide phosphate hydrogen along with a free hydrogen atom H. | 1 | Applied and Interdisciplinary Chemistry |
NETA has antigonadotropic effects via its progestogenic activity and can dose-dependently suppress gonadotropin and sex hormone levels in women and men. The ovulation-inhibiting dose of NETA is about 0.5 mg/day in women. In healthy young men, NETA alone at a dose of 5 to 10 mg/day orally for 2 weeks suppressed testosterone levels from ~527 ng/dL to ~231 ng/dL (–56%). | 1 | Applied and Interdisciplinary Chemistry |
The bioavailability of levonorgestrel is approximately 95% (range 85 to 100%). The plasma protein binding of levonorgestrel is about 98%. It is bound 50% to albumin and 48% to SHBG. Levonorgestrel is metabolized in the liver, via reduction, hydroxylation, and conjugation (specifically glucuronidation and sulfation). Oxidation occurs primarily at the C2α and C16β positions, while reduction occurs in the A ring. 5α-Dihydrolevonorgestrel is produced as an active metabolite of levonorgestrel by 5α-reductase. The elimination half-life of levonorgestrel is 24 to 32 hours, although values as short as 8 hours and as great as 45 hours have been reported. About 20 to 67% of a single oral dose of levonorgestrel is eliminated in urine and 21 to 34% in feces. | 0 | Theoretical and Fundamental Chemistry |
Just as cavitation bubbles form on a fast-spinning boat propeller, they may also form on the tails and fins of aquatic animals. This primarily occurs near the surface of the ocean, where the ambient water pressure is low.
Cavitation may limit the maximum swimming speed of powerful swimming animals like dolphins and tuna. Dolphins may have to restrict their speed because collapsing cavitation bubbles on their tail are painful. Tuna have bony fins without nerve endings and do not feel pain from cavitation. They are slowed down when cavitation bubbles create a vapor film around their fins. Lesions have been found on tuna that are consistent with cavitation damage.
Some sea animals have found ways to use cavitation to their advantage when hunting prey. The pistol shrimp snaps a specialized claw to create cavitation, which can kill small fish. The mantis shrimp (of the smasher variety) uses cavitation as well in order to stun, smash open, or kill the shellfish that it feasts upon.
Thresher sharks use tail slaps to debilitate their small fish prey and cavitation bubbles have been seen rising from the apex of the tail arc. | 1 | Applied and Interdisciplinary Chemistry |
As some carotenoids can be converted into vitamin A, attempts have been made to determine how much of them in the diet is equivalent to a particular amount of retinol, so that comparisons can be made of the benefit of different foods. The situation can be confusing because the accepted equivalences have changed over time.
For many years, a system of equivalencies in which an international unit (IU) was equal to 0.3 μg of retinol (~1 nmol), 0.6 μg of β-carotene, or 1.2 μg of other provitamin-A carotenoids was used. This relationship was alternatively expressed by the retinol equivalent (RE): one RE corresponded to 1 μg retinol, to 2 μg β-carotene dissolved in oil, to 6 μg β-carotene in foods, and to 12 μg of either α-carotene, γ-carotene, or β-cryptoxanthin in food.
Newer research has shown that the absorption of provitamin-A carotenoids is only half as much as previously thought. As a result, in 2001 the US Institute of Medicine recommended a new unit, the retinol activity equivalent (RAE). Each μg RAE corresponds to 1 μg retinol, 2 μg of β-carotene in oil, 12 μg of "dietary" beta-carotene, or 24 μg of the three other dietary provitamin-A carotenoids.
Animal models have shown that at the enterocyte cell wall, β-carotene is taken up by the membrane transporter protein scavenger receptor class B, type 1 (SCARB1). Absorbed β-carotene is converted to retinal and then retinol. The first step of the conversion process consists of one molecule of β-carotene cleaved by the enzyme
β-carotene-15, 15'-monooxygenase, which in humans and other mammalian species is encoded by the BCM01 gene, into two molecules of retinal. When plasma retinol is in the normal range, gene expression for SCARB1 and BC01 are suppressed, creating a feedback loop that suppresses β-carotene absorption and conversion. Absorption suppression is not complete, as receptor 36 is not downregulated. | 1 | Applied and Interdisciplinary Chemistry |
The absorption of dietary iron is a variable and dynamic process. The amount of iron absorbed compared to the amount ingested is typically low, but may range from 5% to as much as 35% depending on circumstances and type of iron. The efficiency with which iron is absorbed varies depending on the source. Generally, the best-absorbed forms of iron come from animal products. Absorption of dietary iron in iron salt form (as in most supplements) varies somewhat according to the body's need for iron, and is usually between 10% and 20% of iron intake. Absorption of iron from animal products, and some plant products, is in the form of heme iron, and is more efficient, allowing absorption of from 15% to 35% of intake. Heme iron in animals is from blood and heme-containing proteins in meat and mitochondria, whereas in plants, heme iron is present in mitochondria in all cells that use oxygen for respiration.
Like most mineral nutrients, the majority of the iron absorbed from digested food or supplements is absorbed in the duodenum by enterocytes of the duodenal lining. These cells have special molecules that allow them to move iron into the body. To be absorbed, dietary iron can be absorbed as part of a protein such as heme protein or iron must be in its ferrous Fe form. A ferric reductase enzyme on the enterocytes brush border, duodenal cytochrome B (Dcytb), reduces ferric Fe to Fe. A protein called divalent metal transporter 1 (DMT1), which can transport several divalent metals across the plasma membrane, then transports iron across the enterocytes cell membrane into the cell. If the iron is bound to heme, it is instead transported across the apical membrane by heme carrier protein 1 (HCP1). Heme is then catabolized by microsomal heme oxygenase into biliverdin, releasing Fe.
These intestinal lining cells can then either store the iron as ferritin, which is accomplished by Fe binding to apoferritin (in which case the iron will leave the body when the cell dies and is sloughed off into feces), or the cell can release it into the body via the only known iron exporter in mammals, ferroportin. Hephaestin, a ferroxidase that can oxidize Fe to Fe and is found mainly in the small intestine, helps ferroportin transfer iron across the basolateral end of the intestine cells. Upon release into the bloodstream, Fe binds transferrin and circulates to tissues. In contrast, ferroportin is post-translationally repressed by hepcidin, a 25-amino acid peptide hormone. The body regulates iron levels by regulating each of these steps. For instance, enterocytes synthesize more Dcytb, DMT1 and ferroportin in response to iron deficiency anemia. Iron absorption from diet is enhanced in the presence of vitamin C and diminished by excess calcium, zinc, or manganese.
The human body's rate of iron absorption appears to respond to a variety of interdependent factors, including total iron stores, the extent to which the bone marrow is producing new red blood cells, the concentration of hemoglobin in the blood, and the oxygen content of the blood. The body also absorbs less iron during times of inflammation, in order to deprive bacteria of iron. Recent discoveries demonstrate that hepcidin regulation of ferroportin is responsible for the syndrome of anemia of chronic disease. | 1 | Applied and Interdisciplinary Chemistry |
Here a throwing motion acts on the sample. The vertical throwing motion is overlaid with a slight circular motion which results in distribution of the sample amount over the whole sieving surface. The particles are accelerated in the vertical direction (are thrown upwards). In the air they carry out free rotations and interact with the openings in the mesh of the sieve when they fall back. If the particles are smaller than the openings, they pass through the sieve. If they are larger, they are thrown. The rotating motion while suspended increases the probability that the particles present a different orientation to the mesh when they fall back again, and thus might eventually pass through the mesh.
Modern sieve shakers work with an electro-magnetic drive which moves a spring-mass system and transfers the resulting oscillation to the sieve stack. Amplitude and sieving time are set digitally and are continuously observed by an integrated control-unit. Therefore, sieving results are reproducible and precise (an important precondition for a significant analysis). Adjustment of parameters like amplitude and sieving time serves to optimize the sieving for different types of material. This method is the most common in the laboratory sector. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry and pharmacology, functional analogs are chemical compounds that have similar physical, chemical, biochemical, or pharmacological properties. Functional analogs are not necessarily structural analogs with a similar chemical structure. An example of pharmacological functional analogs are morphine, heroin and fentanyl, which have the same mechanism of action, but fentanyl is structurally quite different from the other two with significant variance in dosage. | 1 | Applied and Interdisciplinary Chemistry |
Classical variables that do not change upon time reversal include:
:, position of a particle in three-space
:, acceleration of the particle
:, force on the particle
:, energy of the particle
:, electric potential (voltage)
:, electric field
:, electric displacement
:, density of electric charge
:, electric polarization
:Energy density of the electromagnetic field
:, Maxwell stress tensor
:All masses, charges, coupling constants, and other physical constants, except those associated with the weak force. | 0 | Theoretical and Fundamental Chemistry |
Acquired conditions in which mitochondrial dysfunction has been involved are:
* diabetes
* Huntington's disease
* cancer
* Alzheimer's disease,
* Parkinson's disease
* bipolar disorder, schizophrenia, aging and senescence, anxiety disorders
* cardiovascular disease
* sarcopenia
* chronic fatigue syndrome
* ALS
The body, and each mutation, is modulated by other genome variants; the mutation that in one individual may cause liver disease might in another person cause a brain disorder. The severity of the specific defect may also be great or small. Some defects include exercise intolerance. Defects often affect the operation of the mitochondria and multiple tissues more severely, leading to multi-system diseases.
It has also been reported that drug tolerant cancer cells have an increased number and size of mitochondria, which suggested an increase in mitochondrial biogenesis. Interestingly, a recent study in Nature Nanotechnology has reported that cancer cells can hijack the mitochondria from immune cells via physical tunneling nanotubes.
As a rule, mitochondrial diseases are worse when the defective mitochondria are present in the muscles, cerebrum, or nerves, because these cells use more energy than most other cells in the body.
Although mitochondrial diseases vary greatly in presentation from person to person, several major clinical categories of these conditions have been defined, based on the most common phenotypic features, symptoms, and signs associated with the particular mutations that tend to cause them.
An outstanding question and area of research is whether ATP depletion or reactive oxygen species are in fact responsible for the observed phenotypic consequences.
Cerebellar atrophy or hypoplasia has sometimes been reported to be associated. | 1 | Applied and Interdisciplinary Chemistry |
Once actuated, compressed air enters into the tube at one end of the piston and imparts force on the piston. Consequently, the piston becomes displaced. | 1 | Applied and Interdisciplinary Chemistry |
Polymer morphology generally describes the arrangement and microscale ordering of polymer chains in space. The macroscopic physical properties of a polymer are related to the interactions between the polymer chains.
* Disordered polymers: In the solid state, atactic polymers, polymers with a high degree of branching and random copolymers form amorphous (i.e. glassy structures). In melt and solution, polymers tend to form a constantly changing "statistical cluster", see freely-jointed-chain model. In the solid state, the respective conformations of the molecules are frozen. Hooking and entanglement of chain molecules lead to a "mechanical bond" between the chains. Intermolecular and intramolecular attractive forces only occur at sites where molecule segments are close enough to each other. The irregular structures of the molecules prevent a narrower arrangement.
* Linear polymers with periodic structure, low branching and stereoregularity (e. g. not atactic) have a semi-crystalline structure in the solid state. In simple polymers (such as polyethylene), the chains are present in the crystal in zigzag conformation. Several zigzag conformations form dense chain packs, called crystallites or lamellae. The lamellae are much thinner than the polymers are long (often about 10 nm). They are formed by more or less regular folding of one or more molecular chains. Amorphous structures exist between the lamellae. Individual molecules can lead to entanglements between the lamellae and can also be involved in the formation of two (or more) lamellae (chains than called tie molecules). Several lamellae form a superstructure, a spherulite, often with a diameter in the range of 0.05 to 1 mm.
:The type and arrangement of (functional) residues of the repeat units effects or determines the crystallinity and strength of the secondary valence bonds. In isotactic polypropylene, the molecules form a helix. Like the zigzag conformation, such helices allow a dense chain packing. Particularly strong intermolecular interactions occur when the residues of the repeating units allow the formation of hydrogen bonds, as in the case of p-aramid. The formation of strong intramolecular associations may produce diverse folded states of single linear chains with distinct circuit topology. Crystallinity and superstructure are always dependent on the conditions of their formation, see also: crystallization of polymers. Compared to amorphous structures, semi-crystalline structures lead to a higher stiffness, density, melting temperature and higher resistance of a polymer.
* Cross-linked polymers: Wide-meshed cross-linked polymers are elastomers and cannot be molten (unlike thermoplastics); heating cross-linked polymers only leads to decomposition. Thermoplastic elastomers, on the other hand, are reversibly "physically crosslinked" and can be molten. Block copolymers in which a hard segment of the polymer has a tendency to crystallize and a soft segment has an amorphous structure are one type of thermoplastic elastomers: the hard segments ensure wide-meshed, physical crosslinking. | 0 | Theoretical and Fundamental Chemistry |
The following is a list of common functional groups. In the formulas, the symbols R and R' usually denote an attached hydrogen, or a hydrocarbon side chain of any length, but may sometimes refer to any group of atoms. | 0 | Theoretical and Fundamental Chemistry |
When exiting a reactor after a polymerization reaction, many polymers still contain undesired low-molecular weight components. These component may make the product unusable for further processing (for example, a polymer solution cannot directly be used for plastics processing), may be toxic, may cause bad sensory properties such as an unpleasant smell or worsen the properties of the polymer. It may also be desirable to recycle monomers and solvents to the process. Plastic recycling can also involve removal of water and volatile degradation products. | 1 | Applied and Interdisciplinary Chemistry |
If the concentration at the time t = 0 is different from above, the simplifications above are invalid, and a system of differential equations must be solved. However, this system can also be solved exactly to yield the following generalized expressions:
When the equilibrium constant is close to unity and the reaction rates very fast for instance in conformational analysis of molecules, other methods are required for the determination of rate constants for instance by complete lineshape analysis in NMR spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
The first is what one might call a practitioners perspective', wherein the individuals who are responsible for teaching chemistry (teachers, instructors, professors) are the ones who ultimately define chemistry education by their actions. | 1 | Applied and Interdisciplinary Chemistry |
It is important to find a fast and accurate system to discover new DPP-4 inhibitors with ideal therapeutic profiles. High throughput screening (HTS) usually gives low hit rates in identifying the inhibitors but virtual screening (VS) can give higher rates. VS has for example been used to screen for small primary aliphatic amines to identify fragments that could be placed in S1 and S2 sites of DPP-4. On the other hand, these fragments were not very potent and therefore identified as a starting point to design better ones.
Three-dimensional models can provide a useful tool for designing novel DPP-4 inhibitors. Pharmacophore models have been made based on key chemical features of compounds with DPP-4 inhibitory activity. These models can provide a hypothetical picture of the primary chemical feature responsible for inhibitory activity.
The first DPP-4 inhibitors were reversible inhibitors and came with bad side effects because of low selectivity. Researchers suspected that inhibitors with short half-lives would be preferred in order to minimize possible side effects. However, since clinical trials showed the opposite, the latest DPP-4 inhibitors have a long-lasting effect. One of the first reported DPP-4 inhibitor was P32/98 from Merck. It used thiazolidide as the P1-substitute and was the first DPP-4 inhibitor that showed effects in both animals and humans but it was not developed to a market drug due to side effects. Another old inhibitor is DPP-728 from Novartis, where 2-cyanopyrrolidine is used as the P1-substitute. The addition of the cyano group generally increases the potency. Therefore, researchers' attention was directed to those compounds. Usually, DPP-4 inhibitors are either substrate-like or non-substrate-like. | 1 | Applied and Interdisciplinary Chemistry |
The Raeapteek (; ) is a pharmacy in the center of Tallinn, Estonia.
Opposite the Town Hall, at 11 Raekoja plats, it is one of the oldest continuously running pharmacies in Europe, having always been in business in the same house since the early 15th century. It is also the oldest commercial enterprise and the oldest medical establishment in Tallinn.
The first known image of the Town-Hall Pharmacy is an oil painting by Gustav Adolph Oldekop, showing Tallinn's Town Hall Square in 1800. The first photos of the building date from 1889. | 1 | Applied and Interdisciplinary Chemistry |
The trend in artificial reef development has been toward the construction of designed artificial reefs, built from materials specifically designed to function as reefs. Designed systems (such as reef balls) can be modified to achieve a variety of goals. These include coral reef rehabilitation, fishery enhancement, snorkeling and diving trails, beach erosion protection, surfing enhancement, fish spawning sites, planters for mangrove replanting, enhancement of lobster fisheries, creation of oyster reefs, estuary rehabilitation, and even exotic uses such as deep water Oculina coral replanting. Designed systems can overcome many of the problems associated with "materials of opportunity" such as stability in storms, durability, biological fit, lack of potential pollution problems, availability, and reduction in long-term artificial reef costs.
Designed reefs have been developed specifically for coral reef rehabilitation, and can therefore be used in a more specific niche than materials of opportunity. Some examples of specialized adaptations which "designed reefs" can use include: specialized surface textures, coral planting attachment points, specialized pH-neutral surfaces (such as neutralized concrete, ceramics, or mineral accretion surfaces), fissures to create currents for corals, and avoidance of materials such as iron (which may cause algae to overgrow coral). Other types of designed systems can create aquaculture opportunities for lobsters, create oyster beds, or be used for a large variety of other specialized needs. | 1 | Applied and Interdisciplinary Chemistry |
In May 1963, Scheer and Maier-Borst were the first to introduce the use of Tc for medical applications.
In 1968, Philips-Duphar (later Mallinckrodt, today Covidien) marketed the first technetium-99m generator produced in Europe and distributed from Petten, the Netherlands. | 0 | Theoretical and Fundamental Chemistry |
k+-transporting ATPase - karyotype - KduI/IolB isomerase family - kilobase - kinase - Klenow fragment - Knock-down - knock-out - knock-out experiment - knockout - Kozak sequence | 1 | Applied and Interdisciplinary Chemistry |
Bismuth subhalides, such as BiBr and β-BiI, have been recently reported as topological insulators. Topological insulators have caught attention of physical inorganic chemists as well as condensed matter physicists due to the unique physicochemical properties emerging upon transition from bulk to surface states. Exhibiting an energy band gap of classic insulator, the edge/surface states of the material acquire dissipationless electric transport. The subject has been investigated by condensed matter physicists as well as mathematicians to provide a link between the experimental emerging properties and the modeled topology. Broadly, the materials physics pertains to the Quantum Hall effect relying upon two pillars: time-reversal symmetry and spin orbit coupling, the latter dependent on the elemental material composition. Bismuths heavy pnictogen nature yields a large spin-orbit coupling. Additionally, when bound to heavy halogens, bismuth subhalides give rise to a low-dimensional van der Waals bonded structure, exfoliatable into nanowires. | 0 | Theoretical and Fundamental Chemistry |
Bacteriophage P1 vectors can hold inserts 70 – 100kb in size. They begin as linear DNA molecules packaged into bacteriophage P1 particles. These particles are injected into an E. coli strain expressing Cre recombinase. The linear P1 vector becomes circularized by recombination between two loxP sites in the vector. P1 vectors generally contain a gene for antibiotic resistance and a positive selection marker to distinguish clones containing an insert from those that do not. P1 vectors also contain a P1 plasmid replicon, which ensures only one copy of the vector is present in a cell. However, there is a second P1 replicon- called the P1 lytic replicon- that is controlled by an inducible promoter. This promoter allows the amplification of more than one copy of the vector per cell prior to DNA extraction. | 1 | Applied and Interdisciplinary Chemistry |
Primary cilia, present in many types of mammalian cells, serve as cellular antennae. The motile function of these cilia is lost in favour of their sensory specialization. | 0 | Theoretical and Fundamental Chemistry |
Jannik Bjerrum (son of Niels Bjerrum) developed the first general method for the determination of stability constants of metal-ammine complexes in 1941. The reasons why this occurred at such a late date, nearly 50 years after Alfred Werner had proposed the correct structures for coordination complexes, have been summarised by Beck and Nagypál. The key to Bjerrum's method was the use of the then recently developed glass electrode and pH meter to determine the concentration of hydrogen ions in solution. Bjerrum recognised that the formation of a metal complex with a ligand was a kind of acid–base equilibrium: there is competition for the ligand, L, between the metal ion, M, and the hydrogen ion, H. This means that there are two simultaneous equilibria that have to be considered. In what follows electrical charges are omitted for the sake of generality. The two equilibria are
Hence by following the hydrogen ion concentration during a titration of a mixture of M and HL with base, and knowing the acid dissociation constant of HL, the stability constant for the formation of ML could be determined. Bjerrum went on to determine the stability constants for systems in which many complexes may be formed.
The following twenty years saw a veritable explosion in the number of stability constants that were determined. Relationships, such as the Irving-Williams series were discovered. The calculations were done by hand using the so-called graphical methods. The mathematics underlying the methods used in this period are summarised by Rossotti and Rossotti. The next key development was the use of a computer program, LETAGROP to do the calculations. This permitted the examination of systems too complicated to be evaluated by means of hand-calculations. Subsequently, computer programs capable of handling complex equilibria in general, such as SCOGS and MINIQUAD were developed so that today the determination of stability constants has almost become a "routine" operation. Values of thousands of stability constants can be found in two commercial databases. | 0 | Theoretical and Fundamental Chemistry |
The formal standard reduction potential can be defined as the measured reduction potential of the half-reaction at unity concentration ratio of the oxidized and reduced species (i.e.', when 1) under given conditions.
Indeed:
as, , when ,
: , when ,
because , and that the term is included in .
The formal reduction potential makes possible to more simply work with molar or molal concentrations in place of activities. Because molar and molal concentrations were once referred as formal concentrations, it could explain the origin of the adjective formal in the expression formal potential.
The formal potential is thus the reversible potential of an electrode at equilibrium immersed in a solution where reactants and products are at unit concentration. If any small incremental change of potential causes a change in the direction of the reaction, i.e. from reduction to oxidation or vice versa, the system is close to equilibrium, reversible and is at its formal potential. When the formal potential is measured under standard conditions (i.e. the activity of each dissolved species is 1 mol/L, T = 298.15 K = 25 °C = 77 °F, = 1 bar) it becomes de facto a standard potential. According to Brown and Swift (1949), "A formal potential is defined as the potential of a half-cell, measured against the standard hydrogen electrode, when the total concentration of each oxidation state is one formal".
The activity coefficients and are included in the formal potential , and because they depend on experimental conditions such as temperature, ionic strength, and pH, cannot be referred as an immuable standard potential but needs to be systematically determined for each specific set of experimental conditions.
Formal reduction potentials are applied to simplify results interpretations and calculations of a considered system. Their relationship with the standard reduction potentials must be clearly expressed to avoid any confusion. | 1 | Applied and Interdisciplinary Chemistry |
Alkali salts are soluble hydroxides of alkali metals and alkaline earth metals, of which common examples are:
* Sodium hydroxide (NaOH) – often called "caustic soda"
* Potassium hydroxide (KOH) – commonly called "caustic potash"
* Lye – generic term for either of two previous salts or their mixture
* Calcium hydroxide (Ca(OH)) – saturated solution known as "limewater"
* Magnesium hydroxide (Mg(OH)) – an atypical alkali since it has low solubility in water (although the dissolved portion is considered a strong base due to complete dissociation of its ions) | 0 | Theoretical and Fundamental Chemistry |
"TGF" (Transforming Growth Factor) is a family of proteins that includes 33 members that encode dimeric, secreted polypeptides that regulate development. Many developmental processes are under its control including gastrulation, axis symmetry of the body, organ morphogenesis, and tissue homeostasis in adults. All TGF-β ligands bind to either Type I or Type II receptors, to create heterotetramic complexes. | 1 | Applied and Interdisciplinary Chemistry |
JCAMP-DX are text-based file formats created by JCAMP for storing spectroscopic data. It started as a file format for Infrared spectroscopy. It was later expanded to cover Nuclear magnetic resonance spectroscopy, mass spectrometry, electron magnetic resonance and circular dichroism spectroscopy. Later extensions for good laboratory practice were added to cover contract laboratories needs. Despite all efforts to create an easy to comprehend standards, most vendor implementations differ slightly. An open source implementation exists in Java. | 0 | Theoretical and Fundamental Chemistry |
Methyllysine is derivative of the amino acid residue lysine where the sidechain ammonium group has been methylated one or more times.
Such methylated lysines play an important role in epigenetics; the methylation of specific lysines of certain histones in a nucleosome alters the binding of the surrounding DNA to those histones, which in turn affects the expression of genes on that DNA. The binding is affected because the effective radius of the positive charge is increased (methyl groups are larger than the hydrogen atoms they replace), reducing the strongest potential electrostatic attraction with the negatively charged DNA.
It is thought that the methylation of lysine (and arginine) on histone tails does not directly affect their binding to DNA. Rather, such methyl marks recruit other proteins that modulate chromatin structure.
In Protein Data Bank files, methylated lysines are indicated by the MLY or MLZ acronyms. | 1 | Applied and Interdisciplinary Chemistry |
Carbon-based life originates from carboxylation that couples atmospheric carbon dioxide to a sugar. The process is usually catalysed by the enzyme RuBisCO. Ribulose-1,5-bisphosphate carboxylase/oxygenase, the enzyme that catalyzes this carboxylation, is possibly the single most abundant protein on Earth.
Many carboxylases, including Acetyl-CoA carboxylase, Methylcrotonyl-CoA carboxylase, Propionyl-CoA carboxylase, and Pyruvate carboxylase require biotin as a cofactor. These enzymes are involved in various biogenic pathways. In the EC scheme, such carboxylases are classed under EC 6.3.4, "Other Carbon—Nitrogen Ligases".
Another example is the posttranslational modification of glutamate residues, to γ-carboxyglutamate, in proteins. It occurs primarily in proteins involved in the blood clotting cascade, specifically factors II, VII, IX, and X, protein C, and protein S, and also in some bone proteins. This modification is required for these proteins to function. Carboxylation occurs in the liver and is performed by γ-glutamyl carboxylase (GGCX). GGCX requires vitamin K as a cofactor and performs the reaction in a processive manner. γ-carboxyglutamate binds calcium, which is essential for its activity. For example, in prothrombin, calcium binding allows the protein to associate with the plasma membrane in platelets, bringing it into close proximity with the proteins that cleave prothrombin to active thrombin after injury. | 0 | Theoretical and Fundamental Chemistry |
Also well studied is the sea pansy, Renilla reniformis. In this organism, the luciferase (Renilla-luciferin 2-monooxygenase) is closely associated with a luciferin-binding protein as well as a green fluorescent protein (GFP). Calcium triggers release of the luciferin (coelenterazine) from the luciferin binding protein. The substrate is then available for oxidation by the luciferase, where it is degraded to coelenteramide with a resultant release of energy. In the absence of GFP, this energy would be released as a photon of blue light (peak emission wavelength 482 nm). However, due to the closely associated GFP, the energy released by the luciferase is instead coupled through resonance energy transfer to the fluorophore of the GFP, and is subsequently released as a photon of green light (peak emission wavelength 510 nm). The catalyzed reaction is:
* coelenterazine + O → coelenteramide + CO + photon of light | 1 | Applied and Interdisciplinary Chemistry |
Brian Scarlett (11 July 1938–2 September 2004) was a British academic noted for his contributions to particle technology | 1 | Applied and Interdisciplinary Chemistry |
The Henry volatility can also be expressed as the dimensionless ratio between the gas-phase concentration of a species and its aqueous-phase concentration
In chemical engineering and environmental chemistry, this dimensionless constant is often called the air–water partitioning coefficient | 0 | Theoretical and Fundamental Chemistry |
Stereoisomerism about double bonds arises because rotation about the double bond is restricted, keeping the substituents fixed relative to each other. If the two substituents on at least one end of a double bond are the same, then there is no stereoisomer and the double bond is not a stereocenter, e.g. propene, CHCH=CH where the two substituents at one end are both H.
Traditionally, double bond stereochemistry was described as either cis (Latin, on this side) or trans (Latin, across), in reference to the relative position of substituents on either side of a double bond. A simple example of cis-trans isomerism is the 1,2-disubstituted ethenes, like the dichloroethene (CHCl) isomers shown below.
Molecule I is cis-1,2-dichloroethene and molecule II is trans-1,2-dichloroethene. Due to occasional ambiguity, IUPAC adopted a more rigorous system wherein the substituents at each end of the double bond are assigned priority based on their atomic number. If the high-priority substituents are on the same side of the bond, it is assigned Z (Ger. zusammen, together). If they are on opposite sides, it is E (Ger. entgegen, opposite). Since chlorine has a larger atomic number than hydrogen, it is the highest-priority group. Using this notation to name the above pictured molecules, molecule I is (Z)-1,2-dichloroethene and molecule II is (E)-1,2-dichloroethene. It is not the case that Z and cis or E and trans are always interchangeable. Consider the following fluoromethylpentene:
The proper name for this molecule is either trans-2-fluoro-3-methylpent-2-ene because the alkyl groups that form the backbone chain (i.e., methyl and ethyl) reside across the double bond from each other, or (Z)-2-fluoro-3-methylpent-2-ene because the highest-priority groups on each side of the double bond are on the same side of the double bond. Fluoro is the highest-priority group on the left side of the double bond, and ethyl is the highest-priority group on the right side of the molecule.
The terms cis and trans are also used to describe the relative position of two substituents on a ring; cis if on the same side, otherwise trans. | 0 | Theoretical and Fundamental Chemistry |
From the late 1950s through 1977, Westinghouse Electric used PCBs in the manufacture of capacitors in its Bloomington, Indiana, plant. Reject capacitors were hauled and dumped in area salvage yards and landfills, including Bennetts Dump, Neals Landfill and Lemon Lane Landfill. Workers also dumped PCB oil down factory drains, which contaminated the city sewage treatment plant. The City of Bloomington gave away the sludge to area farmers and gardeners, creating anywhere from 200 to 2,000 sites, which remain unaddressed.
Over 2 million pounds of PCBs were estimated to have been dumped in Monroe and Owen counties. Although federal and state authorities have been working on the sites' environmental remediation, many areas remain contaminated. Concerns have been raised regarding the removal of PCBs from the karst limestone topography, and regarding the possible disposal options. To date, the Westinghouse Bloomington PCB Superfund site case does not have a Remedial Investigation/Feasibility Study (RI/FS) and Record of Decision (ROD), although Westinghouse signed a US Department of Justice Consent Decree in 1985. The 1985 consent decree required Westinghouse to construct an incinerator that would incinerate PCB-contaminated materials. Because of public opposition to the incinerator, however, the State of Indiana passed a number of laws that delayed and blocked its construction. The parties to the consent decree began to explore alternative remedies in 1994 for six of the main PCB contaminated sites in the consent decree. Hundreds of sites remain unaddressed as of 2014. Monroe County will never be PCB-free, as noted in a 2014 Indiana University program about the local contamination.
On February 15, 2008, Monroe County approved a plan to clean up the three remaining contaminated sites in the City of Bloomington, at a cost of $9.6 million to CBS Corp., the successor of Westinghouse. In 1999, Viacom bought CBS, so they are current responsible party for the PCB sites. | 1 | Applied and Interdisciplinary Chemistry |
Spoil tips may be conical in shape, and can appear as conspicuous features of the landscape, or they may be much flatter and eroded, especially if vegetation has established itself. In Loos-en-Gohelle, in the former mining area of Pas-de-Calais, France, are a series of five very perfect cones, of which two rise from the plain. | 1 | Applied and Interdisciplinary Chemistry |
Xi Zhenfeng (; born April 2, 1963, in Henan) is a Chinese organic chemist.
Xi received his B.S. degree from Xiamen University in 1983, and his M.S. degree from Nanjing University, Zhengzhou University and Henan Institute of Chemistry in 1989. He joined Professor Tamotsu Takahashi's group at the Institute for Molecular Sciences, Japan, as a Ph.D. course student in 1993 and obtained a Ph.D. degree in 1996.
He took an assistant professor position at Hokkaido University, Japan, in 1997, after he worked as a postdoctoral research fellow with Professor Takahashi at Catalyst Research Centre, Hokkaido University. In 1998, he joined the Department of Chemistry, Peking University, China, as an associate professor and was promoted to professor in 1999. He is a Chang Jiang Scholar Distinguished Professor (since 2001) of Peking University. In 2015, he became the academician of Chinese Academy of Sciences.
His research interests are focused on organometallic chemistry and organic synthesis, including development of synthetic methodologies based on selective cleavage of C–H, C–C and C–X bonds mediated by organometallic compounds, development of organometallic reagents, study on mechanisms of reactions involving reactive organometallic intermediates, and synthesis of functional structures.
He is now serving as editor or consultant for several international academic journals, including:
* Applied Organometallic Chemistry (John-Wiley), Associate Editor (since 2008).
* Tetrahedron and Tetrahedron Letters (Elsevier), Board of Consulting Editors (since 2008).
* Synlett and Synthesis (Thieme), Advisory Board (since 2009).
* Asian Journal of Organic Chemistry (John-Wiley), Editorial Board (since 2012).
* Organic Letters (ACS), Associate Editor (since 2013).
He has been visiting professors for several universities/institutes in the worlds, including:
*Hokkaido University, Japan, 2006
*University of Rennes 1, France, 2007
*RIKEN, Japan, 2010 | 0 | Theoretical and Fundamental Chemistry |
In 2016, the ISCRE, Inc. Board of Directors will bestow the first Rutherford Aris Young Investigator Award for Excellence in Chemical Reaction Engineering. This award will recognize outstanding contributions in experimental and/or theoretical reaction engineering research of investigators in early stages of their career. The recipient must be less than 40 years of age at the end of the calendar year in which the award is presented. The Aris Award is generously supported by a grant from the UOP, L.L.C., a Honeywell Company. The award consists of a plaque, an honorarium of $3000, and up to $2000 in travel funds to present at an ISCRE/NASCRE conference and to present a lecture at UOP. This award complements ISCRE's other major honor, the Neal R. Amundson Award. Winners of the award include:
* 2016: Paul J. Dauenhauer, Professor - University of Minnesota, USA
* 2019: Yuriy Roman-Leschkov, Professor, MIT, USA.
* 2022: Announced at NASCRE-5 | 1 | Applied and Interdisciplinary Chemistry |
A closet flange (the drainpipe flange to which a flush toilet is attached) is a specialized flange designed to be flush with the floor, allowing a toilet to be installed above it. The flange must be mechanically strong to accommodate slight misalignments or movements and resist corrosion. | 1 | Applied and Interdisciplinary Chemistry |
The Hill reaction is the light-driven transfer of electrons from water to Hill reagents (non-physiological oxidants) in a direction against the chemical potential gradient as part of photosynthesis. Robin Hill discovered the reaction in 1937. He demonstrated that the process by which plants produce oxygen is separate from the process that converts carbon dioxide to sugars. | 0 | Theoretical and Fundamental Chemistry |
In contrast to benzene ring, pyridine efficiently supports several nucleophilic substitutions. The reason for this is relatively lower electron density of the carbon atoms of the ring. These reactions include substitutions with elimination of a hydride ion and elimination-additions with formation of an intermediate aryne configuration, and usually proceed at the 2- or 4-position.
Many nucleophilic substitutions occur more easily not with bare pyridine but with pyridine modified with bromine, chlorine, fluorine, or sulfonic acid fragments that then become a leaving group. So fluorine is the best leaving group for the substitution with organolithium compounds. The nucleophilic attack compounds may be alkoxides, thiolates, amines, and ammonia (at elevated pressures).
In general, the hydride ion is a poor leaving group and occurs only in a few heterocyclic reactions. They include the Chichibabin reaction, which yields pyridine derivatives aminated at the 2-position. Here, sodium amide is used as the nucleophile yielding 2-aminopyridine. The hydride ion released in this reaction combines with a proton of an available amino group, forming a hydrogen molecule.
Analogous to benzene, nucleophilic substitutions to pyridine can result in the formation of pyridyne intermediates as heteroaryne. For this purpose, pyridine derivatives can be eliminated with good leaving groups using strong bases such as sodium and potassium tert-butoxide. The subsequent addition of a nucleophile to the triple bond has low selectivity, and the result is a mixture of the two possible adducts. | 0 | Theoretical and Fundamental Chemistry |
Some spectroscopic curves can be approximated by the sum of a set of component curves. For example, when Beer's law
applies, the measured intensity, I, at wavelength λ, is a linear combination of the intensity due to the individual components, k, at concentration, c. ε is an extinction coefficient. In such cases the curve of experimental data may be decomposed into sum of component curves in a process of curve fitting. This process is also widely called deconvolution. Curve deconvolution and curve fitting are completely different mathematical procedures.
Curve fitting can be used in two distinct ways.
# The line shapes and parameters and of the individual component curves have been obtained experimentally. In this case the curve may be decomposed using a linear least squares process simply to determine the concentrations of the components. This process is used in analytical chemistry to determine the composition of a mixture of the components of known molar absorptivity spectra. For example, if the heights of two lines are found to be h and h, c = h / ε and c = h / ε.
# Parameters of the line shape are unknown. The intensity of each component is a function of at least 3 parameters, position, height and half-width. In addition one or both of the line shape function and baseline function may not be known with certainty. When two or more parameters of a fitting curve are not known the method of non-linear least squares must be used. The reliability of curve fitting in this case is dependent on the separation between the components, their shape functions and relative heights, and the signal-to-noise ratio in the data. When Gaussian-shaped curves are used for the decomposition of set of N spectra into N curves, the and parameters are common to all N spectra. This allows to calculated the heights of each Gaussian curve in each spectrum (N·N parameters) by a (fast) linear least squares fitting procedure, while the and w parameters (2·N parameters) can be obtained with a non-linear least-square fitting on the data from all spectra simultaneously, thus reducing dramatically the correlation between optimized parameters. | 0 | Theoretical and Fundamental Chemistry |
Skeletal muscle tremor is the most common adverse effect of beta-agonists, and is more likely to be seen after oral administration than after inhalation. Tremor results from an imbalance between fast- and slow-twitch muscle groups of the extremities, and its severity varies greatly between individuals. | 0 | Theoretical and Fundamental Chemistry |
The Institute of Physical Chemistry of the Polish Academy of Sciences (Polish Instytut Chemii Fizycznej Polskiej Akademii Nauk) is one of numerous institutes belonging to the Polish Academy of Sciences. As its name suggests, the institute's primary research interests are in the field of physical chemistry. The institute is subdivided into departments, including the Department of Soft Condensed Matter and Fluids, the Department of Physical Chemistry of Supramolecular Complexes, the Department of Photochemistry and Spectroscopy and the Department of Quantum Theory of Solids and Molecules, this is also known as the PIPC. | 0 | Theoretical and Fundamental Chemistry |
Electron-rich is jargon that is used in multiple related meanings with either or both kinetic and thermodynamic implications:
* with regards to electron-transfer, electron-rich species have low ionization energy and/or are reducing agents. Tetrakis(dimethylamino)ethylene is an electron-rich alkene because, unlike ethylene, it forms isolable radical cation. In contrast, electron-poor alkene tetracyanoethylene is an electron acceptor, forming isolable anions.
* with regards to acid-base reactions, electron-rich species have high pKa's and react with weak Lewis acids.
* with regards to nucleophilic substitution reactions, electron-rich species are relatively strong nucleophiles, as judged by rates of attack by electrophiles. For example, compared to benzene, pyrrole is more rapidly attacked by electrophiles. Pyrrole is therefore considered to be an electron-rich aromatic ring. Similarly, benzene derivatives with electron-donating groups (EDGs) are attacked by electrophiles faster than in benzene. The electron-donating vs electron-withdrawing influence of various functional groups have been extensively parameterized in linear free energy relationships.
* with regards to Lewis acidity, electron-rich species are strong Lewis bases. | 0 | Theoretical and Fundamental Chemistry |
Simmons was born on May 3, 1931. He attended Massachusetts Institute of Technology (MIT) in 1949. He became a metallurgist at the Allegheny Ludlum Steel corporation in Pittsburgh. He then worked for other steel companies before returning to become the chief executive of Allegheny, taking it public and then leading a management buyout. Having become wealthy, he then created a variety of endowments at MIT.
Simmons was also chairman of the Pittsburgh Symphony Orchestra between 1989 and 1997. He returned as chairman in 2003 until his retirement in 2015. | 1 | Applied and Interdisciplinary Chemistry |
In contrast with protein studies, where a primary protein structure is unambiguously defined by the sequence of nucleotides (the genetic code), the glycobiology still cannot explain how a certain "message" is encoded using carbohydrates or how it is "read" and "translated" by other biological entities.
An interdisciplinary effort, combining chemistry, biology, and biochemistry, studies glycan-protein interactions to see how different sequences of carbohydrates initiate different cellular responses. | 1 | Applied and Interdisciplinary Chemistry |
Examples of long-lived isotopes include iodine-129 and Tc-99, which have nuclear half-lives of 15 million and 200,000 years, respectively. | 0 | Theoretical and Fundamental Chemistry |
A gene product is the biochemical material, either RNA or protein, resulting from expression of a gene. A measurement of the amount of gene product is sometimes used to infer how active a gene is. Abnormal amounts of gene product can be correlated with disease-causing alleles, such as the overactivity of oncogenes which can cause cancer.
A gene is defined as "a hereditary unit of DNA that is required to produce a functional product". Regulatory elements include:
* Promoter region
* TATA box
* Polyadenylation sequences
* Enhancers
These elements work in combination with the open reading frame to create a functional product. This product may be transcribed and be functional as RNA or is translated from mRNA to a protein to be functional in the cell. | 1 | Applied and Interdisciplinary Chemistry |
During decay, if we neglect the triple correlation scalars, then the equations reduce to axially symmetric five-dimensional heat equations,
Solutions to these five-dimensional heat equation was solved by Chandrasekhar. The initial conditions can be expressed in terms of Gegenbauer polynomials (without loss of generality),
where are Gegenbauer polynomials. The required solutions are
where is the Bessel function of the first kind.
As the solutions become independent of
where | 1 | Applied and Interdisciplinary Chemistry |
Typical substrates are epoxides, diols, dienes, and carboxylic acid anhydrides.
One example is the conversion of cis-3,5-diacetoxycyclopentene to monoacetate. In this transformation, the plane of symmetry in the precursor is lost, and the product is asymmetric. The desymmetrisation itself is not usually considered useful. The enantioselective desymmetrisation however delivers a useful product. This particular conversion utilizes the enzyme cholinesterase.
In another example, a symmetrical cyclic imide is subjected to asymmetric deprotonation resulting in a chiral product with high enantioselectivity.
Transfer hydrogenation converts benzil (PhC(O)C(O)Ph) into one enantiomer of hydrobenzoin:
:PhC(O)C(O)Ph + 2 H → PhCH(OH)CH(OH)Ph
The precursor benzil has C symmetry, and the product is C symmetric.
Citric acid is also a symmetric molecule that can be desymmetrized by partial methylation. | 0 | Theoretical and Fundamental Chemistry |
Isocyanates can be converted to carbodiimides with loss of carbon dioxide:
:2 RN=C=O → (RN)C + CO
The reaction is catalyzed by phosphine oxides. This reaction is reversible. | 0 | Theoretical and Fundamental Chemistry |
Recording data and image processing is superior to real-time work because subtle anomalies often missed by the operator (especially in magnetically noisy areas) can be correlated between lines, shapes and clusters better defined. A range of sophisticated enhancement techniques can also be used. There is also a hard copy and need for systematic coverage. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, Stokes' law is an empirical law for the frictional force – also called drag force – exerted on spherical objects with very small Reynolds numbers in a viscous fluid. It was derived by George Gabriel Stokes in 1851 by solving the Stokes flow limit for small Reynolds numbers of the Navier–Stokes equations. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, the diazo group is an organic moiety consisting of two linked nitrogen atoms at the terminal position. Overall charge-neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes and are described by the general structural formula . The simplest example of a diazo compound is diazomethane, . Diazo compounds () should not be confused with azo compounds () or with diazonium compounds (). | 0 | Theoretical and Fundamental Chemistry |
The Alaskan Gyre and Western Subarctic Gyre are an iron-limited environment rather than a nitrogen or phosphorus limited environment. This region relies on dust blowing off the state of Alaska and other landmasses nearby to supply iron. Because it is limited by iron instead of nitrogen or phosphorus, it is known as high-nutrient, low-chlorophyll region. Iron limitation in high-nutrient, low-chlorophyll regions results in water that is rich in other nutrients because they have not been removed by the small populations of plankton that live there. | 1 | Applied and Interdisciplinary Chemistry |
Fetal alcohol spectrum disorder (FASD), formerly referred to as fetal alcohol syndrome, presents as craniofacial malformations, neurobehavioral disorders and mental disabilities, all attributed to exposing human embryos to alcohol during fetal development. The risk of FASD depends on the amount consumed, the frequency of consumption, and the points in pregnancy at which the alcohol is consumed. Ethanol is a known teratogen, i.e., causes birth defects. Ethanol is metabolized by alcohol dehydrogenase enzymes into acetaldehyde. The subsequent oxidation of acetaldehyde into acetate is performed by aldehyde dehydrogenase enzymes. Given that retinoic acid (RA) regulates numerous embryonic and differentiation processes, one of the proposed mechanisms for the teratogenic effects of ethanol is a competition for the enzymes required for the biosynthesis of RA from vitamin A. Animal research demonstrates that in the embryo, the competition takes place between acetaldehyde and retinaldehyde for aldehyde dehydrogenase activity. In this model, acetaldehyde inhibits the production of retinoic acid by retinaldehyde dehydrogenase. Ethanol-induced developmental defects can be ameliorated by increasing the levels of retinol, retinaldehyde, or retinaldehyde dehydrogenase. Thus, animal research supports the reduction of retinoic acid activity as an etiological trigger in the induction of FASD. | 1 | Applied and Interdisciplinary Chemistry |
There are several ways of reducing and preventing this form of corrosion.
* Electrically insulate the two metals from each other. If they are not in electrical contact, no galvanic coupling will occur. This can be achieved by using non-conductive materials between metals of different electropotential. Piping can be isolated with a spool of pipe made of plastic materials, or made of metal material internally coated or lined. It is important that the spool be a sufficient length to be effective. For reasons of safety, this should not be attempted where an electrical earthing system uses the pipework for its ground or has equipotential bonding.
* Metal boats connected to a shore line electrical power feed will normally have to have the hull connected to earth for safety reasons. However the end of that earth connection is likely to be a copper rod buried within the marina, resulting in a steel-copper "battery" of about 0.5 V. Additionally, the hull of each boat is connected to the hull of all other boats, resulting in further "batteries" between propellers (which may be made of bronze) and steel hulls, which may cause corrosion of the expensive propellers. For such cases, the use of a galvanic isolator is essential, typically two semiconductor diodes in series, in parallel with two diodes conducting in the opposite direction (antiparallel). This device is inserted in the protective earth connection between the hull and the shoreline protective conductor. This prevents any current in the protective conductor while the applied voltage is less than 1.4 V (i.e. 0.7 V per diode), but allows a full current in the case of an electrical fault. There will still be a very minor leakage of current through the diodes, which may result in slightly faster corrosion than normal.
* Ensure there is no contact with an electrolyte. This can be done by using water-repellent compounds such as greases, or by coating the metals with an impermeable protective layer, such as a suitable paint, varnish, or plastic. If it is not possible to coat both, the coating should be applied to the more noble, the material with higher potential. This is advisable because if the coating is applied only on the more active material, in case of damage to the coating there will be a large cathode area and a very small anode area, and for the exposed anodic area the corrosion rate will be correspondingly high.
* Using antioxidant paste is beneficial for preventing corrosion between copper and aluminium electrical connections. The paste consists of a lower nobility metal than aluminium or copper.
* Choose metals that have similar electropotentials. The more closely matched the individual potentials, the smaller the potential difference and hence the smaller the galvanic current. Using the same metal for all construction is the easiest way of matching potentials.
* Electroplating or other plating can also help. This tends to use more noble metals that resist corrosion better. Chrome, nickel, silver and gold can all be used. Galvanizing with zinc protects the steel base metal by sacrificial anodic action.
* Cathodic protection uses one or more sacrificial anodes made of a metal which is more active than the protected metal. Alloys of metals commonly used for sacrificial anodes include zinc, magnesium, and aluminium. This approach is commonplace in water heaters and many buried or immersed metallic structures.
* Cathodic protection can also be applied by connecting a direct current (DC) electrical power supply to oppose the corrosive galvanic current. (See .) | 1 | Applied and Interdisciplinary Chemistry |
The most common composition is iron thermite. The oxidizer used is usually either iron(III) oxide or iron(II,III) oxide. The former produces more heat. The latter is easier to ignite, likely due to the crystal structure of the oxide. Addition of copper or manganese oxides can significantly improve the ease of ignition.
The density of prepared thermite is often as low as 0.7 g/cm. This, in turn, results in relatively poor energy density (about 3 kJ/cm), rapid burn times, and spray of molten iron due to the expansion of trapped air. Thermite can be pressed to densities as high as 4.9 g/cm (almost 16 kJ/cm) with slow burning speeds (about 1 cm/s). Pressed thermite has higher melting power, i.e. it can melt a steel cup where a low-density thermite would fail. Iron thermite with or without additives can be pressed into cutting devices that have heat-resistant casing and a nozzle.
Oxygen balanced iron thermite 2Al + FeO has theoretical maximum density of 4.175 g/cm an adiabatic burn temperature of 3135 K or 2862 °C or 5183 °F (with phase transitions included, limited by iron, which boils at 3135 K), the aluminium oxide is (briefly) molten and the produced iron is mostly liquid with part of it being in gaseous form - 78.4 g of iron vapor per kg of thermite are produced. The energy content is 945.4 cal/g (3 956 J/g). The energy density is 16,516 J/cm.
The original mixture, as invented, used iron oxide in the form of mill scale. The composition was very difficult to ignite. | 0 | Theoretical and Fundamental Chemistry |
The third piece has a fractured top surface, which indicates that a fourth piece of the original pillar is missing. Klaus Roessler (1995) estimated the length of this piece at . Henry Cousens hypothesized that the fourth piece had a garuda figure (the Paramara royal emblem) or a trishula (trident) at the top. As Bhoja was a Shaivite king, R. Balasubramaniam analyzed Shaivite iconography to conclude that the top had a trishula.
Balasubramaniam also theorizes that an iron pillar in front of Mandus Jami Masjid might be a re-shaped version of the Dhar pillars missing piece. This pillar is called Allaudins Sang' (spear) after Alauddin Khalji. | 1 | Applied and Interdisciplinary Chemistry |
Enzymatic lysis, also called Lysozyme lysis, involves the use of enzymes to digest the cell wall and release the plasmid DNA. The most commonly used enzyme for this purpose is lysozyme, which breaks down the peptidoglycan in the cell wall of Gram-positive bacteria. Lysozyme is usually added to the bacterial culture, followed by heating and/or shaking the culture to release the plasmid DNA. | 1 | Applied and Interdisciplinary Chemistry |
The liver is a major organ of metabolism, and it is related to glycogen storage, decomposition of red blood cells, certain protein and hormone synthesis, and detoxification. Within these functions, its detoxification response is essential for new drug development and clinical trials. In addition, because of its multi-functions, the liver is prone to many diseases, and liver diseases have become a global challenge.
Liver-on-a-chip devices utilize microfluidic techniques to simulate the hepatic system by imitating complex hepatic lobules that involve liver functions. Liver-on-a-chip devices provide a good model to help researchers work on dysfunction and pathogenesis of the liver with relatively low cost. Researchers use primary rat hepatocytes and other nonparenchymal cells. This coculture method is extensively studied and is proved to be beneficial for extension of hepatocytes survival time and support the performance of liver-specific functions. Many liver-on-a-chip systems are made of poly(dimethylsiloxane) (PDMS) with multiple channels and chambers based on specific design and objective. PDMS is used and has become popular because it has relatively low price for raw materials, and it is also easily molded for microfluidic devices. But PDMS can absorb important signaling molecules including proteins and hormones. Other more inert materials such as polysulfone or polycarbonate are used in liver-chips.
A study by Emulate researchers assessed advantages of using liver-chips predicting drug-induced liver injury which could reduce the high costs and time needed in drug development workflows/pipelines, sometimes described as the pharmaceutical industry's "productivity crisis". Zaher Nahle subsequently outlined 12 "reasons why micro-physiological systems (MPS) like organ-chips are better at modeling human diseases".
One design from Kane et al. cocultures primary rat hepatocytes and 3T3-J2 fibroblasts in an 8*8 element array of microfluidic wells. Each well is separated into two chambers. The primary chamber contains rat hepatocytes and 3T3-J2 fibroblasts and is made of glass for cells adhesion. Each of primary chamber is connected to a microfluidic network that supply metabolic substrate and remove metabolic byproducts. A 100 µm thick membrane of PDMS separates the primary and secondary chamber, allowing the secondary chamber to be connected to another microfluidic network that perfuses 37 °C room air with 10% carbon dioxide, and producing air exchange for rat hepatocytes. The production of urea and steady-state protein proves the viability of this device for use in high-throughput toxicity studies.
Another design from Kang et al. cocultures primary rat hepatocytes and endothelial cells. A single-channel is made first. Hepatocytes and endothelial cells are then planted on the device and are separated by a thin Matrigel layer in between. The metabolic substrate and metabolic byproducts share this channel to be supplied or removed. Later, a dual-channel is made, and endothelial cells and hepatocytes cells have their own channels to supply the substrate or remove the byproduct. The production of urea and positive result on hepatitis B virus (HBV) replication test shows its potential to study hepatotropic viruses.
There are a few other applications on liver-on-a-chip. Lu et al. developed a liver tumor-on-a-chip model. The decellularized liver matrix (DLM)-gelatin methacryloyl (GelMA)-based biomimetic liver tumor-on-a-chip proved to be a suitable design for further anti-tumor studies. Zhou et al. analyzed alcohol injures on the hepatocytes and the signaling and recovery.
The liver-on-a-chip has shown its great potential for liver-related research. Future goals for liver-on-a-chip devices focus on recapitulating a more realistic hepatic environment, including reagents in fluids, cell types, extending survival time, etc. | 1 | Applied and Interdisciplinary Chemistry |
Levan is synthesized in archaea, fungi, bacteria, and a limited number of plant species. Fructans such as levan are synthesized from sucrose, a disaccharide containing glucose and fructose. In plants, the vacuole is where fructan production occurs. Sucrose:sucrose/fructan 6-fructosyltransferase is the fructosyltransferase in the vacuole which creates the beta 2,6 linkages to form the linear form of levan. Bacteria also use a fructosyltransferase known as levansucrase to form levan. These enzymes in bacteria form the 2,1 linkages in the linear basal chains of levan to allow for branching points to occur. Many bacteria produce levan in the cell exterior. This production can be sensitive to temperature, oxygen concentration, pH, and other factors. Levan production in bacteria is typically a sign of growth in population. There are also possible ways to produce by fracturing soybean mucilage.
Levans are produced by microbes during colonization of a food substrate. Erwinia amylovora exudes levan and amylovoran as part of its biofilm. Together they contribute to its pathogenicity. In 2016, Ua-Arak et al. developed a sourdough method with high levan output (among other exopolysaccharides). | 1 | Applied and Interdisciplinary Chemistry |
Due to their small genomes and limited number of encoded proteins, viruses exploit host proteins for entry, replication, and transmission. Identification of such host proteins, also termed host dependency factors (HDFs), is particularly important for identifying therapeutic targets. Over recent years, many groups have successfully used genome-wide CRISPR/Cas9 as a screening strategy for HDFs in viral infections.
One example is provided by Marceau et al. (2017), who aimed to dissect the host factors associated with dengue and hepatitis C (HCV) infection (two viruses in family Flaviviridae). ELAVL1, an RNA-binding protein encoded by the ELAVL1 gene, was found to be a critical receptor for HCV entry, and a remarkable divergence in host dependency factors was demonstrated between the two flaviviridae. | 1 | Applied and Interdisciplinary Chemistry |
Three nucleobases found in nucleic acids, cytosine (C), thymine (T), and uracil (U), are pyrimidine derivatives:
In DNA and RNA, these bases form hydrogen bonds with their complementary purines. Thus, in DNA, the purines adenine (A) and guanine (G) pair up with the pyrimidines thymine (T) and cytosine (C), respectively.
In RNA, the complement of adenine (A) is uracil (U) instead of thymine (T), so the pairs that form are adenine:uracil and guanine:cytosine.
Very rarely, thymine can appear in RNA, or uracil in DNA, but when the other three major pyrimidine bases are represented, some minor pyrimidine bases can also occur in nucleic acids. These minor pyrimidines are usually methylated versions of major ones and are postulated to have regulatory functions.
These hydrogen bonding modes are for classical Watson–Crick base pairing. Other hydrogen bonding modes ("wobble pairings") are available in both DNA and RNA, although the additional 2′-hydroxyl group of RNA expands the configurations, through which RNA can form hydrogen bonds. | 1 | Applied and Interdisciplinary Chemistry |
These are the various assumptions that go into developing potential flow panel methods:
* Inviscid
* Incompressible
* Irrotational
* Steady
However, the incompressible flow assumption may be removed from the potential flow derivation leaving:
* Potential flow (inviscid, irrotational, steady) | 1 | Applied and Interdisciplinary Chemistry |
Water distribution network is the term for the portion of a water distribution system up to the service points of bulk water consumers or demand nodes where many consumers are lumped together. The World Health Organization (WHO) uses the term water transmission system for a network of pipes, generally in a tree-like structure, that is used to convey water from water treatment plants to service reservoirs, and uses the term water distribution system for a network of pipes that generally has a loop structure to supply water from the service reservoirs and balancing reservoirs to consumers. | 1 | Applied and Interdisciplinary Chemistry |
Sutula, Chester Louis, Structure, molecular orientation and mechanically induced reorientation of molecules in multimolecular films of long-chain n-hydrocarbon derivatives, 155 (1959) | 0 | Theoretical and Fundamental Chemistry |
Notable members of The Electrochemical Society include numerous Nobel Prize laureates including the three co-winners of the 2019 Nobel Prize for Chemistry.
*Thomas Edison: Edison became a member on April 4, 1903. Early members recall attending a meeting at Edison's home in the Society’s early days. Edison is often credited for inventing the phonograph, the motion picture camera, and the electric light bulb.
*John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino, all long-time ECS members, shared the 2019 Nobel Prize in Chemistry “for the development of lithium-ion batteries”.
*Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura shared the 2014 Nobel Prize in Physics for “the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources”.
*Jack Kilby’s invention of the integrated circuit earned him half of the 2000 Nobel Prize in Physics "for basic work on information and communication technology".
*Steven Chu and William D. Phillips were co-recipients of the 1997 Nobel Prize in Physics “for the development of methods to cool and trap atoms with laser light”.
*Richard Smalley shared the 1996 Nobel Prize in Chemistry “for the discovery of fullerenes”.
*Rudolph A. Marcus won the 1992 Nobel Prize in Chemistry “for his contributions to the theory of electron transfer reactions in chemical systems".
*Jean-Marie Lehn, an early innovator in the field of supramolecular chemistry, shared the 1987 Nobel Prize in Chemistry “for the development and use of molecules with structure-specific interactions of high selectivity”.
*Gerd Binnig shared the 1986 Nobel Prize in Physics “for the design of the scanning tunneling microscope”.
*[https://www.electrochem.org/publications/leadership-collections Charles W. Tobias]: A pioneer in the field of electrochemical engineering, Tobias made a long-lasting and far-reaching impact on the field of electrochemical science by forming the Chemical Engineering Department at UC Berkeley in 1947. He served as ECS president from 1970-1971.
*Gordon E. Moore: The co-founder of Intel was known for his 1965 principle which made possible the delivery of more powerful and lower-costing semiconductor chips. This was later known as Moore's law.
*Norman Hackerman: The internationally known expert in metal corrosion served as ECS president from 1957-1958. Hackerman is most recognized for developing the electrochemistry of oxidation.
*Carl Wagner: Often referred to as the father of solid-state chemistry, Wagner's work on oxidation rate theory, counter diffusion of ions, and defect chemistry considerably advanced knowledge of how reactions proceed at the atomic level in the solid state. Wagner was the first recipient of the ECS Palladium Award in 1951.
*Irving Langmuir: received the 1932 Nobel Prize in Chemistry “for his discoveries and investigations in surface chemistry”.
*Edward Goodrich Acheson: The inventor of the Acheson process was a manufacturer of carborundum and graphite. The ECS Acheson Award was named in his honor in 1931.
*Theodore William Richards: Richards, whose research helped confirm the existence of isotopes, received the 1914 Nobel Prize in Chemistry, “in recognition of his accurate determinations of the atomic weight of a large number of chemical elements”.
*Willis R. Whitney: ECS president from 1911-1912, Whitney is most recognized among his many achievements for founding the research laboratory of the General Electric Company.
*Leo Baekeland: Baekland, who served as ECS president in 1909, is most famous for inventing Bakelite in 1907. His entrepreneurial genius and inventive nature made Baekeland one of the most important players in chemical technology.
*Herbert H. Dow: Among his most significant achievements, Dow founded the Dow Chemical Company in 1897. Dow Chemical funded the creation of the ECS Industrial Electrochemistry and Electrochemical Engineering Division H. H. Dow Memorial Student Achievement Award in his honor in 1990.
*Edward Weston: Noted for his achievements in electroplating, Weston developed the electrochemical cell – named the Weston cell, for the voltage standard.
*Charles Martin Hall: Hall, is best known for inventing an inexpensive process to produce aluminum, was one of the founders of Alcoa.
*Lawrence Addicks (1878-1964) served as president of The Electrochemical Society from 1915 to 1916. | 0 | Theoretical and Fundamental Chemistry |
The objective of the refinement process is to find equilibrium constant values that give the best fit to the experimental data. This is usually achieved by minimising an objective function, , by the method of non-linear least-squares. First the residuals are defined as
Then the most general objective function is given by
The matrix of weights, , should be, ideally, the inverse of the variance-covariance matrix of the observations. It is rare for this to be known. However, when it is, the expectation value of U is one, which means that the data are fitted within experimental error. Most often only the diagonal elements are known, in which case the objective function simplifies to
with when . Unit weights, , are often used but, in that case, the expectation value of is the root mean square of the experimental errors.
The minimization may be performed using the Gauss–Newton method. Firstly the objective function is linearised by approximating it as a first-order Taylor series expansion about an initial parameter set, .
The increments are added to the corresponding initial parameters such that is less than . At the minimum the derivatives , which are simply related to the elements of the Jacobian matrix,
where is the th parameter of the refinement, are equal to zero. One or more equilibrium constants may be parameters of the refinement. However, the measured quantities (see above) represented by are not expressed in terms of the equilibrium constants, but in terms of the species concentrations, which are implicit functions of these parameters. Therefore, the Jacobian elements must be obtained using implicit differentiation.
The parameter increments are calculated by solving the normal equations, derived from the conditions that at the minimum.
The increments are added iteratively to the parameters
where is an iteration number. The species concentrations and values are recalculated at every data point. The iterations are continued until no significant reduction in is achieved, that is, until a convergence criterion is satisfied. If, however, the updated parameters do not result in a decrease of the objective function, that is, if divergence occurs, the increment calculation must be modified. The simplest modification is to use a fraction, , of calculated increment, so-called shift-cutting.
In this case, the direction of the shift vector, , is unchanged. With the more powerful Levenberg–Marquardt algorithm, on the other hand, the shift vector is rotated towards the direction of steepest descent, by modifying the normal equations,
where is the Marquardt parameter and is an identity matrix. Other methods of handling divergence have been proposed.
A particular issue arises with NMR and spectrophotometric data. For the latter, the observed quantity is absorbance, , and the Beer–Lambert law can be written as
It can be seen that, assuming that the concentrations, c, are known, that absorbance, , at a given wavelength, , and path length , is a linear function of the molar absorbptivities, . With 1 cm path-length, in matrix notation
There are two approaches to the calculation of the unknown molar absorptivities
:(1) The values are considered parameters of the minimization and the Jacobian is constructed on that basis. However, the values themselves are calculated at each step of the refinement by linear least-squares:
:using the refined values of the equilibrium constants to obtain the speciation. The matrix
:is an example of a pseudo-inverse.
:Golub and Pereyra showed how the pseudo-inverse can be differentiated so that parameter increments for both molar absorptivities and equilibrium constants can be calculated by solving the normal equations.
:(2) The Beer–Lambert law is written as
:The unknown molar absorbances of all "coloured" species are found by using the non-iterative method of linear least-squares, one wavelength at a time. The calculations are performed once every refinement cycle, using the stability constant values obtaining at that refinement cycle to calculate species' concentration values in the matrix . | 0 | Theoretical and Fundamental Chemistry |
COX assembly in yeast are a complex process that is not entirely understood due to the rapid and irreversible aggregation of hydrophobic subunits that form the holoenzyme complex, as well as aggregation of mutant subunits with exposed hydrophobic patches. COX subunits are encoded in both the nuclear and mitochondrial genomes. The three subunits that form the COX catalytic core are encoded in the mitochondrial genome. Over 30 different nuclear-encoded chaperone proteins are required for COX assembly.
Cofactors, including hemes, are inserted into subunits I & II. The two heme molecules reside in subunit I, helping with transport to subunit II where two copper molecules aid with the continued transfer of electrons. Subunits I and IV initiate assembly. Different subunits may associate to form sub-complex intermediates that later bind to other subunits to form the COX complex. In post-assembly modifications, COX will form a homodimer. This is required for activity. Dimers are connected by a cardiolipin molecule, which has been found to play a key role in stabilization of the holoenzyme complex. The dissociation of subunits VIIa and III in conjunction with the removal of cardiolipin results in total loss of enzyme activity. Subunits encoded in the nuclear genome are known to play a role in enzyme dimerization and stability. Mutations to these subunits eliminate COX function.
Assembly is known to occur in at least three distinct rate-determining steps. The products of these steps have been found, though specific subunit compositions have not been determined.
Synthesis and assembly of COX subunits I, II, and III are facilitated by translational activators, which interact with the 5’ untranslated regions of mitochondrial mRNA transcripts. Translational activators are encoded in the nucleus. They can operate through either direct or indirect interaction with other components of translation machinery, but exact molecular mechanisms are unclear due to difficulties associated with synthesizing translation machinery in-vitro. Though the interactions between subunits I, II, and III encoded within the mitochondrial genome make a lesser contribution to enzyme stability than interactions between bigenomic subunits, these subunits are more conserved, indicating potential unexplored roles for enzyme activity. | 1 | Applied and Interdisciplinary Chemistry |
Milk fat globule membrane (MFGM) is a complex and unique structure composed primarily of lipids and proteins that surrounds milk fat globule secreted from the milk producing cells of humans and other mammals. It is a source of multiple bioactive compounds, including phospholipids, glycolipids, glycoproteins, and carbohydrates that have important functional roles within the brain and gut.
Preclinical studies have demonstrated effects of MFGM-derived bioactive components on brain structure and function, intestinal development, and immune defense. Similarly, pediatric clinical trials have reported beneficial effects on cognitive and immune outcomes. In populations ranging from premature infants to preschool-age children, dietary supplementation with MFGM or its components has been associated with improvements in cognition and behavior, gut and oral bacterial composition, fever incidence, and infectious outcomes including diarrhea and otitis media.
MFGM may also play a role in supporting cardiovascular health by modulating cholesterol and fat uptake. Clinical trials in adult populations have shown that MFGM could positively affect markers associated with cardiovascular disease including lowering serum cholesterol and triacylglycerol levels as well as blood pressure. | 1 | Applied and Interdisciplinary Chemistry |
Directed overflow is a special case of damage pre-emption, where excess of a normal, but reactive metabolite could lead to toxic products. Preventing this excess is thus pre-emption of potential damage.
The first two intermediates in riboflavin biosynthesis are highly reactive and can spontaneously break down to 5-phosphoribosylamine and Maillard reaction products, which are highly reactive and harmful. The enzyme COG3236 hydrolyzes these two first intermediates into two less harmful products, thus preventing the harm they would otherwise cause. | 1 | Applied and Interdisciplinary Chemistry |
Robert François Laugier (1722–1793) was a French pharmacologist. He is known for his book "Institutiones pharmaceuticae sive philosophia pharmaceutica" and for his work on the alembic. | 1 | Applied and Interdisciplinary Chemistry |
Base calling is the process of assigning nucleobases to chromatogram peaks, light intensity signals, or electrical current changes resulting from nucleotides passing through a nanopore. One computer program for accomplishing this job is Phred, which is a widely used base calling software program by both academic and commercial DNA sequencing laboratories because of its high base calling accuracy.
Base callers for Nanopore sequencing use neural networks trained on current signals obtained from accurate sequencing data. | 1 | Applied and Interdisciplinary Chemistry |
The basic components of a rotary kiln are the shell, the refractory lining, support tyres (riding rings) and rollers, drive gear and internal heat exchangers. | 1 | Applied and Interdisciplinary Chemistry |
A series of treatment processes is utilized to maintain water quality in intensive fish farming operations. These steps are often done in order or sometimes in tandem. After leaving the vessel holding fish the water is first treated for solids before entering a biofilter to convert ammonia, next degassing and oxygenation occur, often followed by heating/cooling and sterilization. Each of these processes can be completed by using a variety of different methods and equipment, but regardless all must take place to ensure a healthy environment that maximizes fish growth and health. | 1 | Applied and Interdisciplinary Chemistry |
Mutai's doctoral research involved studying parasitic worms and neglected tropical diseases. Her subsequent research interests have included treatments for neglected tropical diseases. | 1 | Applied and Interdisciplinary Chemistry |
The Australian cattle industry is responsible for producing 3.9% of world beef productivity and due to 60% of the nation's entire beef production being exported, Australia operates alongside America and Brazil as one of the largest beef exporters worldwide. Slaughter rates in the Australian feedlot sector tend to increase during drought periods which can last for a number of years. This is due to the limited availability of grain which the onset of drought brings with it, meaning that feedlots are generally lacking in activity during this time. The Southern rangelands typically operate their feedlots by running smaller herds via more intense operations compared to the Northern rangeland sector.
The vast majority of Australian feedlot production falls in Queensland and the Northern Territory. The use of these feedlots has grown substantially since 1980 and the industry is currently able to feed over 1 million cattle in feedlots at once. The increasing use of feedlots in Australia is due to a consumerist demand for grass fed beef. Feedlot sectors are typically characterised by climates where crops and pastures are able to survive and typically consist of vegetation where short term crops such as wheat, oats and barley and long term crops such as clover can survive Australia's subterranean climate where conditions will endure for over 5 months. Further, this also encompasses those months where the ratio of rainfall and evaporation exceeds 1 cm and where the average monthly temperature exceeds 7 degrees. | 1 | Applied and Interdisciplinary Chemistry |
It is the analysis of the time-dependent interaction of hydrodynamic and elastic structural forces. Vibration of floating and submerged ocean structures/vessels encompasses this field of naval architecture. | 1 | Applied and Interdisciplinary Chemistry |
Selenols are usually prepared by the reaction of organolithium reagents or Grignard reagents with elemental Se. For example, benzeneselenol is generated by the reaction of phenylmagnesium bromide with selenium followed by acidification:
Another preparative route to selenols involves the alkylation of selenourea, followed by hydrolysis. Selenols are often generated by reduction of diselenides followed by protonation of the resulting selenolate:
Dimethyl diselenide can be easily reduced to methaneselenol within cells. | 0 | Theoretical and Fundamental Chemistry |
Cracks can be formed in many different elastomers by ozone attack, and the characteristic form of attack of vulnerable rubbers is known as ozone cracking. The problem was formerly very common, especially in tires, but is now rarely seen in those products owing to preventive measures.
However, it does occur in many other safety-critical items such as fuel lines and rubber seals, such as gaskets and O-rings, where ozone attack is considered unlikely. Only a trace amount of the gas is needed to initiate cracking, and so these items can also succumb to the problem. | 0 | Theoretical and Fundamental Chemistry |
Pervaporation (or pervaporative separation) is a processing method for the separation of mixtures of liquids by partial vaporization through a non-porous or porous membrane. | 0 | Theoretical and Fundamental Chemistry |
Current research in microfluidics is focused on developing point-of-care diagnostics and cell sorting techniques (see lab-on-a-chip), and understanding cell behavior (e.g. cell growth, cell aging). In the field of diagnostics, the lateral flow test is a common microfluidic device platform that utilizes capillary forces to drive fluid transport through a porous membrane. The most famous lateral flow test is the take home pregnancy test, in which bodily fluid initially wets and then flows through the porous membrane, often cellulose or glass fiber, upon reaching a capture line to indicate a positive or negative signal. An advantage to this design, and several other microfluidic devices, is its simplicity (for example, its lack of human intervention during operation) and low cost. However, a disadvantage to these tests is that capillary action cannot be controlled after it has started, so the test time cannot be sped up or slowed down (which could pose an issue if certain time-dependent processes are to take place during the fluid flow).
Another example of point-of-care work involving a capillary pressure-related design component is the separation of plasma from whole blood by filtration through porous membrane. Efficient and high-volume separation of plasma from whole blood is often necessary for infectious disease diagnostics, like the HIV viral load test. However, this task is often performed through centrifugation, which is limited to clinical laboratory settings. An example of this point-of-care filtration device is a packed-bed filter, which has demonstrated the ability to separate plasma and whole blood by utilizing asymmetric capillary forces within the membrane pores. | 1 | Applied and Interdisciplinary Chemistry |
Until the latter half of the 20th century, smelting sulfide ores was almost the sole means of producing copper metal from mined ores (primary copper production). As of 2002, 80% of global primary copper production was from copper–iron–sulfur minerals, and the vast majority of these were treated by smelting.
Copper was initially recovered from sulfide ores by directly smelting the ore in a furnace. The smelters were initially located near the mines to minimize the cost of transport. This avoided the prohibitive costs of transporting the waste minerals and the sulfur and iron present in the copper-containing minerals. However, as the concentration of copper in the ore bodies decreased, the energy costs of smelting the whole ore also became prohibitive, and it became necessary to concentrate the ores first.
Initial concentration techniques included hand-sorting and gravity concentration. These resulted in high losses of copper. Consequently, the development of the froth flotation process was a major step forward in mineral processing. It made the development of the giant Bingham Canyon mine in Utah possible.
In the twentieth century, most ores were concentrated before smelting. Smelting was initially undertaken using sinter plants and blast furnaces, or with roasters and reverberatory furnaces. Roasting and reverberatory furnace smelting dominated primary copper production until the 1960s.
Copper smelting technology gave rise to the Copper Age, aka Chalcolithic Age, and then the Bronze Age. The Bronze Age would not have been possible without the development of smelting technology.
The modern froth flotation process was independently invented in the early 1900s in Australia by C.V Potter and around the same time by G. D. Delprat. | 1 | Applied and Interdisciplinary Chemistry |
CORROSION es una banda de Thrash metal Paraguaya ceada en 1992 en Asunción
con partes de los integrantes de la Banda de Thrash Rawhide.Tiene como influencias a las tipicas bandas de metal como Slayer,Mettalica,Dorsal Atlantica,etc
La banda Se creo en 1992 con las cenizas de Rawhide,Lanzaron un Demo + Bonus tracks Y un LP album de studio(Report of Explotation) Despues de su ultima gira en 1995 en varios escenarios de Paraguay y Sao paulo y entre eso se disolvieron por problemas personales.
Luego en 2013 volvieron haciendo un concierto en el estadio de Sol de America con varios grupos de Thrash Muy conocidos...
En 2021 Lanzaron un Boxset de Report of Explotation.
En 1992 lanzaron un demo + Bonus tracks llamado Reinos Depredados,luego Grabaron el Famoso album de Studio como LP Report of Explotation en 1993 Grabado en brazil en el estudio de Nas Nuvens de Río de Janeiro y fue lanzado bajo el sello de Dynamo brazil.
# Reinos Depredados
# Aventon de la muerte
# Escucha tu Conciencia
# Corrosion
# Freneticos
Bonus tracks
# Reinos Depredados (estudio demo)
# Intro - Aventón de la Muerte (en vivo)
# Reinos Depredados (en vivo)
# For Whom the Bell Tolls (Metallica Cover) (live)
# Noema (live)
# Escucha a Tu Conciencia (live)
# Frenéticos (live)
# Himno a la Alegría (live)
# Huellas de Corrosión (live)
# Skeletons of Society (Slayer cover) (live)
# Reinos Depredados [Bis] (live)
# Aventón de la Muerte [Bis] (live)
# Letragia Ancestral (studio version)
Duracion:
# Zeitgeist
# Genesis of Terror
# Deforested Kingdoms
# Castle of sir jan
B Side
# Listen to your conciensce
# Noema
# Hitch-Hicking Death
# Signs Of Corrosion
# Tesay Ro
# Letergia Ancestral
# Letergia Ancestral
# Reinos depredados
# Escucha Tu Conciencia
# Deforested Kingdoms
# Signs of corrosion | 1 | Applied and Interdisciplinary Chemistry |
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