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The simplest test to evaluate whether a coal is suitable for production of coke is the free swelling index test. This involves heating a small sample of coal in a standardised crucible to around 800 degrees Celsius (1500 °F).<br>
After heating for a specified time, or until all volatiles are driven off, a small coke button remains in the crucible. The cross sectional profile of this coke button compared to a set of standardised profiles determines the Free Swelling Index. | 0 | Theoretical and Fundamental Chemistry |
Sociedad Española de Construcciones Electromecánicas (abbreviated as SECEM), colloquially known as "electro", was a Spanish company in the non-ferrous metals industry that operated between 1917 and 1978. Throughout its existence it was one of the most important Spanish companies in the copper sector, having its main activity in Córdoba. Among its products were copper products, brass, electrical transformers, etc. | 1 | Applied and Interdisciplinary Chemistry |
As it is the precise mixture of minerals dissolved in the water, together with water's pH and temperature, that determine the behaviour of the hardness, a single-number scale does not adequately describe hardness. However, the United States Geological Survey uses the following classification for hard and soft water:
Seawater is considered to be very hard due to various dissolved salts. Typically seawater's hardness is in the area of 6,570; ppm (6.57 grams per litre). In contrast, freshwater has a hardness in the range of 15 to 375 ppm; generally around 600 mg/L. | 0 | Theoretical and Fundamental Chemistry |
Autoreceptor inhibition leads to increase respective neurotransmitter release. Major autoreceptor which clinically important are alpha 2(adrenergic receptor subtype 2), H 3(histamine receptor subtype 3), 5 HT 1(serotonin receptor subtype 1). In which respective drugs act are Clonidine on alpha 2 as Agonist used in hypertension which reduce release of norepinephrine and epinephrine from presynaptic neurons. Tizanidine used as centrally acting skeletal muscle relaxant is also act on alpha 2. 5 HT 1A is target of Buspirone which act as a partial Agonist and used as Atypical non sedative anxiolytic.5HT 1B/1D receptor Agonist are Triptans and Ergot alkaloids which used in treatment of migraine. 5 HT 1F receptor subtype Agonist drug lesmiditan also used in treatment of migraine. H 3 receptor antagonist Pitolisant used in narcolepsy. As an example, norepinephrine released from sympathetic neurons may interact with the alpha-2A and alpha-2C adrenoreceptors to inhibit further release of norepinephrine. Similarly, acetylcholine released from parasympathetic neurons may interact with M and M receptors to inhibit further release of acetylcholine. An atypical example is given by the β-adrenergic autoreceptor in the sympathetic peripheral nervous system, which acts to increase transmitter release.
The D2sh autoreceptor has been shown recently to interact with the trace amine-assorted receptor 1 (TAAR1), a G-Coupled Protein Receptor GPCR, to regulate monoaminergic systems in the brain. Active TAAR1 opposes the autoreceptor's activity by inactivating the dopamine transporter (DAT). In their review of TAAR1 in monoaminergic systems, Xie and Miller proposed this schematic: synaptic dopamine binds to the dopamine autoreceptor, which activates the DAT. Dopamine enters the presynaptic cells and binds to TAAR1, which increases adenylyl cyclase activity. This eventually allows for the translation of trace amines in the cytoplasm and activation of cyclic nucleotide-gated ion channels, which further activate TAAR1 and dump dopamine into the synapse. Through a series of phosphorylation events related to PKA and PKC, active TAAR1 inactivates DAT, preventing uptake of dopamine from the synapse. The presence of two Postsynaptic receptors with opposite abilities to regulate monoamine transporter function allows for regulation of the monoaminergic system.
Autoreceptor activity may also decrease paired-pulse facilitation (PPF). A feedback cell is activated by the (partially) depolarized post-synaptic neuron. The feedback cell releases a neurotransmitter to which the autoreceptor of the presynaptic neuron is receptive. The autoreceptor causes the inhibition of calcium channels (slowing calcium ion influx) and the opening of potassium channels (increasing potassium ion efflux) in the presynaptic membrane. These changes in ion concentration effectively diminish the amount of the original neurotransmitter released by the presynaptic terminal into the synaptic cleft. This causes a final depression on the activity of the postsynaptic neuron. Thus the feedback cycle is complete. | 1 | Applied and Interdisciplinary Chemistry |
The discovery of the internucleosomal fragmentation of genomic DNA to regular repeating oligonucleosomal fragments generated by Ca/Mg-dependent endonuclease is accepted as one of the best-characterized biochemical markers of apoptosis (programmed cell death).
In 1970, described that cytoplasmic DNA isolated from mouse liver cells after culture was characterized by DNA fragments with a molecular weight consisting of multiples of 135 kDa. This finding was consistent with the hypothesis that these DNA fragments were a specific degradation product of nuclear DNA. In 1972, , , and coined the term apoptosis and distinguished this type of cell death from necrosis based on morphological features. In 1973, and , during the study of subchromatin structure, found that chromatin is accessible to the Ca/Mg endonuclease, resulting in the formation of a digestion product with a regular series of molecular weight similar to the one previously described by Williamson (1970). In 1974, , , and , using cells exposed to widely differing types of trauma, found that during cell death, degraded DNA in "every case had a modal value of between 10(x6) and 10(x7) Dalton and cellular metabolism is required to produce degradation of DNA". However, this observation was without indication of "whether the incision attack on the DNA molecule was a random or rather at a particular site, that have structural or functional meaning". In 1976, , , and described internucleosomal fragmentation of irradiated lymphoid chromatin DNA in vivo.
Six years passed from 1972 to 1978/1980 until the discovery and evaluation of internucleosomal fragmentation of DNA during apoptotic cell death as a hallmark of apoptosis. Since 1972 (, , and ), it is accepted that glucocorticoid-induced death of lymphocytes is a form of apoptosis. In 1978, and presented a paper revealing that glucocorticoid-induced DNA degradation in rat lymphoid tissue, thymus, and spleen occurred in a specific pattern producing fragments of DNA that were electrophoretically similar to those observed after treatment of chromatin with microccoccal nuclease, which indicated internucleosomal cleavage pattern of DNA degradation occurred during apoptosis. Thus, the first link between programmed cell death/apoptosis and internucleosomal fragmentation of chromatin DNA was discovered and soon became as a specific feature of apoptosis.
In 1980, reported additional evidence for an internucleosomal DNA cleavage pattern as a specific feature of glucocorticoid-treated thymocytes undergoing apoptosis. The internucleosomal DNA cleavage pattern was observed as a specific feature of apoptosis in 1978/1980 and has become a recognised hallmark of programmed cell death since then. In 1992 Gorczyca et al. and Gavrieli et al. independently described the DNA fragmentation assay based on the use of the terminal deoxynucleotidyl transferase (TUNEL) which become one of the standard methods to detect and identify apoptotic cells. | 1 | Applied and Interdisciplinary Chemistry |
The Mayo–Lewis equation or copolymer equation in polymer chemistry describes the distribution of monomers in a copolymer. It was proposed by Frank R. Mayo and Frederick M. Lewis.
The equation considers a monomer mix of two components and and the four different reactions that can take place at the reactive chain end terminating in either monomer ( and ) with their reaction rate constants :
The reactivity ratio for each propagating chain end is defined as the ratio of the rate constant for addition of a monomer of the species already at the chain end to the rate constant for addition of the other monomer.
The copolymer equation is then:
with the concentrations of the components in square brackets. The equation gives the relative instantaneous rates of incorporation of the two monomers. | 0 | Theoretical and Fundamental Chemistry |
NF-Y is a heterotrimeric complex composed of NF-YA, NF-YB, and NF-YC subunits. The key structural feature of the NF-Y/DNA complex is the minor-groove interaction of its DNA binding domain-containing subunit NF-YA, which induces an ~80° bend in the DNA. NF-YB and NF-YC interact with DNA through non-specific histone-fold domain-DNA contacts. NF-YAs unique DNA-binding mode and NF-YB/NF-YCs nucleosome-like properties of non-specific DNA binding impose sufficient spatial constraints to induce flanking nucleosomes to slide outward, making nearby recognition sites for other transcription factors accessible. | 1 | Applied and Interdisciplinary Chemistry |
Hillhouse was gay, although he did not come out openly in his professional career until later in his life. In his career as a teacher and mentor, he served as a role model for younger LGBTQ+ chemists. | 0 | Theoretical and Fundamental Chemistry |
The Systems Biology Ontology (SBO) is a set of controlled, relational vocabularies of terms commonly used in systems biology, and in particular in computational modeling. | 1 | Applied and Interdisciplinary Chemistry |
Tramadol induces analgesic effects through a variety of different targets on the noradrenergic system, serotoninergic system, and opioid receptors system. Tramadol exists as a racemic mixture, the positive enantiomer inhibits serotonin reuptake while the negative enantiomer inhibits noradrenaline re-uptake, by binding to and blocking the transporters. Tramadol has also been shown to act as a serotonin releasing agent. Both enantiomers of tramadol are agonists of the μ-opioid receptor and its M1 metabolite, O-desmetramadol, is also a μ-opioid receptor agonist but is 6 times more potent than tramadol itself. All these effects work synergistically to induce analgesia.
Tramadol has been found to possess these actions:
* Agonist of the μ-opioid receptor (MOR) and to a far lesser extent of the δ-opioid receptor (DOR) and κ-opioid receptor (KOR)
* Serotonin reuptake inhibitor (SRI) and norepinephrine reuptake inhibitor; hence, an SNRI
* Serotonin 5-HT receptor antagonist
* M and M muscarinic acetylcholine receptor antagonist
* α7 nicotinic acetylcholine receptor antagonist
* NMDA receptor antagonist (very weak)
* TRPA1 inhibitor
Tramadol acts on the opioid receptors through its major active metabolite desmetramadol, which has as much as 700-fold higher affinity for the MOR relative to tramadol. Moreover, tramadol itself has been found to possess no efficacy in activating the MOR in functional activity assays, whereas desmetramadol activates the receptor with high intrinsic activity (E equal to that of morphine). As such, desmetramadol is exclusively responsible for the opioid effects of tramadol. Both tramadol and desmetramadol have pronounced selectivity for the MOR over the DOR and KOR in terms of binding affinity.
Tramadol is well-established as an SRI. In addition, a few studies have found that it also acts as a serotonin releasing agent (1–10 μM), similar in effect to fenfluramine. The serotonin releasing effects of tramadol could be blocked by sufficiently high concentrations of the serotonin reuptake inhibitor 6-nitroquipazine, which is in accordance with other serotonin releasing agents such as fenfluramine and MDMA. However, two more recent studies failed to find a releasing effect of tramadol at respective concentrations up to 10 and 30 μM. In addition to serotonergic activity, tramadol is also a norepinephrine reuptake inhibitor. It is not a norepinephrine releasing agent. Tramadol does not inhibit the reuptake or induce the release of dopamine.
A positron emission tomography imaging study found that single oral 50-mg and 100-mg doses of tramadol to human volunteers resulted in 34.7% and 50.2% respective mean occupation of the serotonin transporter (SERT) in the thalamus. The estimated median effective dose (ED) for SERT occupancy hence was 98.1 mg, which was associated with a plasma tramadol level of about 330 ng/ml (1,300 nM). The estimated maximum daily dosage of tramadol of 400 mg (100 mg ) would result in as much as 78.7% occupancy of the SERT (in association with a plasma concentration of 1,220 ng/ml or 4,632 nM). This is close to that of SSRIs, which occupy the SERT by 80% or more.
Peak plasma concentrations during treatment with clinical dosages of tramadol have generally been found to be in the range of 70 to 592 ng/ml (266–2,250 nM) for tramadol and 55 to 143 ng/ml (221–573 nM) for desmetramadol. The highest levels of tramadol were observed with the maximum oral daily dosage of 400 mg per day divided into one 100-mg dose every 6 hours (i.e., four 100-mg doses evenly spaced out per day). Some accumulation of tramadol occurs with chronic administration; peak plasma levels with the maximum oral daily dosage (100 mg ) are about 16% higher and the area-under-the-curve levels 36% higher than following a single oral 100-mg dose. Positron emission tomography imaging studies have reportedly found that tramadol levels are at least four-fold higher in the brain than in plasma. Conversely, brain levels of desmetramadol "only slowly approach those in plasma". The plasma protein binding of tramadol is only 4–20%; hence, almost all tramadol in circulation is free, thus bioactive. | 0 | Theoretical and Fundamental Chemistry |
Ionic relaxation comprises ionic conductivity and interfacial and space charge relaxation. Ionic conductivity predominates at low frequencies and introduces only losses to the system. Interfacial relaxation occurs when charge carriers are trapped at interfaces of heterogeneous systems. A related effect is Maxwell-Wagner-Sillars polarization, where charge carriers blocked at inner dielectric boundary layers (on the mesoscopic scale) or external electrodes (on a macroscopic scale) lead to a separation of charges. The charges may be separated by a considerable distance and therefore make contributions to the dielectric loss that are orders of magnitude larger than the response due to molecular fluctuations. | 0 | Theoretical and Fundamental Chemistry |
DNA adenine methyltransferase identification, often abbreviated DamID, is a molecular biology protocol used to map the binding sites of DNA- and chromatin-binding proteins in eukaryotes. DamID identifies binding sites by expressing the proposed DNA-binding protein as a fusion protein with DNA methyltransferase. Binding of the protein of interest to DNA localizes the methyltransferase in the region of the binding site. Adenine methylation does not occur naturally in eukaryotes and therefore adenine methylation in any region can be concluded to have been caused by the fusion protein, implying the region is located near a binding site. DamID is an alternate method to ChIP-on-chip or ChIP-seq. | 1 | Applied and Interdisciplinary Chemistry |
A number of organic compounds form charge-transfer complex, which are often described as electron-donor-acceptor complexes (EDA complexes). Typical acceptors are nitrobenzenes or tetracyanoethylene (TCNE). The strength of their interaction with electron donors correlates with the ionization potentials of the components. For TCNE, the stability constants (L/mol) for its complexes with benzene derivatives correlates with the number of methyl groups: benzene (0.128), 1,3,5-trimethylbenzene (1.11), 1,2,4,5-tetramethylbenzene (3.4), and hexamethylbenzene (16.8).
1,3,5-Trinitrobenzene and related polynitrated aromatic compounds, being electron-deficient, form charge-transfer complexes with many arenes. Such complexes form upon crystallization, but often dissociate in solution to the components. Characteristically, these CT salts crystallize in stacks of alternating donor and acceptor (nitro aromatic) molecules, i.e. A-B-A-B. | 0 | Theoretical and Fundamental Chemistry |
The fundamental resolution equation is used in chromatography to help relate adjustable chromatographic parameters to resolution, and is as follows:
R = [N/4][(α-1)/α][k/(1+k)], where
N = Number of theoretical plates
α = Selectivity Term = k/k
The [N/4] term is the column factor, the [(α-1)/α] term is the thermodynamic factor, and the [k/(1+k)] term is the retention factor. The 3 factors are not completely independent, but they are very close, and can be treated as such.
So what does this mean? It means that to increase resolution of two peaks on a chromatogram, one of the three terms of the equation need to be modified.
1) N can be increased by lengthening the column (least effective, as doubling the column will get a 2 or 1.44x increase in resolution).
2) Increasing k' also helps. This can be done by lowering the column temperature in G.C., or by choosing a weaker mobile phase in L.C. (moderately effective)
3) Changing α is the most effective way of increasing resolution. This can be done by choosing a stationary phase that has a greater difference between k and k. It can also be done in L.C. by using pH to invoke secondary equilibria (if applicable).
The fundamental resolution equation is derived as follows:
For two closely spaced peaks, ω = ω, and σ = σ
so R = (t - t)/ω = (t - t)/4σ
Where t and t are the retention times of two separate peaks.
Since N = [(t)/σ], then σ = t/ N
Using substitution, R = N[(t - t)/4t] = (N/4)(1 - t/t)
Now using the following equations and solving for t and t
k = (t - t)/t ; t = t(k + 1)
k = (t - t)/t ; t = t(k + 1)
Substituting again and you get:
R = [N/4][1 - (k + 1)/(k + 1] = [N/4][(k - k)/(1 + k')]
And finally substituting once more α = k/k and you get the Fundamental Resolution Equation:
R = [N/4][(α-1)/α][k/(1+k)] | 0 | Theoretical and Fundamental Chemistry |
Blanco co-founded Sunthetics, along with fellow NYU graduate, Myriam Sbeiti, and NYU professor of Chemical and Biomolecular Engineering, Miguel Modestino.
The idea for Sunthetics was born while Blanco was a PhD student at NYU working on her PhD thesis. Her goal was to find a way to efficiently power chemical reactions using electricity rather than heat which relies on the burning of fossil fuels. She was initially focused on applying this idea to part of the development process for the widely used material, nylon. When faced with a lack of interest from Nylon manufacturing companies, the Sunthetic's co-founders decided to pivot their companies focus to the Artificial Intelligence (AI) algorithms behind the process. The AI tools that had been developed were the key to making the renewable energy driven chemical reactions as efficient as possible. Blanco also found there was significantly more interest in the AI technology she and the Sunthetics team had developed and it was this technology that could be applied to many different industries. Sunthetics now focuses on further developing and perfecting that AI-driven machine learning platform. As of 2022, Sunthetics has six employees. | 1 | Applied and Interdisciplinary Chemistry |
* 2014 – 2017 Corbion, Corbion Thermophiles. Prime investigator €530k
* 2010-2013 Purac, Competence in industrial Bacillus strains. Prime investigator €420k
* 2004 – 2007 DSM Bakery Ingredients B.V. Sense: Screening for protein secretion using secretion stress indicators. Prime investigator €640k
* 2001 – 2005 Frico + DSM Directing Starters Together 2 (several partners). Prime investigator €554k
* 2000 – 2006 Intervet International B.V. Expression of heterologous proteins in Bacillus. Prime investigator €433k | 0 | Theoretical and Fundamental Chemistry |
Transformation and annealing twinning takes place when a cooling crystal experiences a displacive polymorphic transition. For example, leucite has an isometric crystal structure above about , but becomes tetragonal below this temperature. Any one of the three original axes of a crystal can become the long axis when this phase change takes place. Twinning results when different parts of the crystal break their isometric symmetry along a different choice of axis. This is typically polysynthetic twinning, which enables the crystal to maintain its isometric shape by averaging out the displacement in each direction. This produces a pseudomorphic crystal that appears to have isometric symmetry. Potassium feldspar likewise experiences polysynthetic twinning as it transforms from a monoclinic structure (orthoclase) to a triclinic structure (microcline) on slow cooling. | 0 | Theoretical and Fundamental Chemistry |
The first monosaccharide attached in the synthesis of O-linked glycans is N-acetyl-galactosamine. After this, several different pathways are possible. A Core 1 structure is generated by the addition of galactose. A Core 2 structure is generated by the addition of N-acetyl-glucosamine to the N-acetyl-galactosamine of the Core 1 structure. Core 3 structures are generated by the addition of a single N-acetyl-glucosamine to the original N-acetyl-galactosamine. Core 4 structures are generated by the addition of a second N-acetyl-glucosamine to the Core 3 structure. Other core structures are possible, though less common.
Images:
https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=glyco.figgrp.561 : Core 1 and Core 2 generation. White square = N-acetyl-galactosamine; black circle = galactose; Black square = N-acetyl-glucosamine. Note: There is a mistake in this diagram. The bottom square should always be white in each image, not black.
https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=glyco.figgrp.562 : Core 3 and Core 4 generation.
A common structural theme in O-linked glycans is the addition of polylactosamine units to the various core structures. These are formed by the repetitive addition of galactose and N-acetyl-glucosamine units. Polylactosamine chains on O-linked glycans are often capped by the addition of a sialic acid residue (similar to neuraminic acid). If a fucose residue is also added, to the next to penultimate residue, a Sialyl-Lewis X (SLex) structure is formed. | 0 | Theoretical and Fundamental Chemistry |
Rollover (also known as flameover) is a stage of a structure fire when fire gases in a room or other enclosed area ignite. Since heated gases, the product of pyrolysis, rise to the ceiling, this is where a rollover phenomenon is most often witnessed. Visually, this may be seen as flames "rolling" across the ceiling, radiating outward from the seat of the fire to the extent of gas spread.
Rollover is not the same as flashover, although it may precede it, and the terms may be confused. In the case of rollover, only gases present in the room, not the room contents, ignite. | 0 | Theoretical and Fundamental Chemistry |
For historical reasons discussed below, a few types of carbon-containing compounds, such as carbides, carbonates (excluding carbonate esters), simple oxides of carbon (for example, CO and carbon dioxide|) and cyanides are generally considered inorganic compounds. Different forms (allotropes) of pure carbon, such as diamond, graphite, fullerenes and carbon nanotubes are also excluded because they are simple substances composed of a single element and so not generally considered chemical compounds.
The word "organic" in this context does not mean "natural". | 0 | Theoretical and Fundamental Chemistry |
Computers & Chemical Engineering is an international, peer-reviewed scientific journal in the field of process systems engineering. The journal accepts general papers on process systems engineering, as well as emerging new areas and topics for new developments in the application of computing and systems technology to chemical engineering problems. The journal was founded in 1977 and is published 12 times a year. The journals current Editor-in-Chief is Efstratios N. Pistikopoulos, and editors are J. H. Lee, A.B. Póvoa, and Fengqi You. Computers & Chemical Engineering' offers authors two choices to publish their research: Gold Open Access and Subscription. Its impact factor is 4.000 in 2019. | 1 | Applied and Interdisciplinary Chemistry |
The main function of the DREAM complex is to repress G1/S and G2/M gene expression during quiescence (G). Entry into the cell cycle dissociates p130 from the complex and leads to subsequent recruitment of activating E2F proteins. This allows for the expression of E2F regulated late G1 and S phase genes. BMYB (MYBL2), which is repressed by the DREAM complex during G is also able to be expressed at this time, and binds to MuvB during S phase to promote the expression of key G/M phase genes such as CDK1 and CCNB1. FOXM1 is then recruited in G to further promote gene expression (e.g. AURKA). During late S phase BMYB is degraded via CUL1 (SCF complex), while FOXM1 is degraded during mitosis by the APC/C. Near the end of the cell cycle, the DREAM complex is re-assembled by DYRK1A to repress G1/S and G2/M genes. | 1 | Applied and Interdisciplinary Chemistry |
De la Pirotechnia is considered to be one of the first printed books on metallurgy to have been published in Europe. It was written in Italian and first published in Venice in 1540. The author was Vannoccio Biringuccio, a citizen of Siena, Italy, who died before it was published. Further editions were published in 1550, 1558, 1559, and 1678, with a (sloppy) French translation by Jacques Vincent being published in 1556, 1572, and 1627. Parts were translated into Latin (by Georgius Agricola), English (Richard Eden; Peter Whitehorn) and Spanish (Bernardo Perez de Vargas) at various times in the 1550s and 1560s, generally without acknowledgement.
The second book on metallurgy, De re metallica, was written in Latin by Georgius Agricola, and published in 1556.
Mining was typically left to professionals, craftsmen and experts who were not eager to share their knowledge. Much experiential knowledge had been accumulated over the course of time. This knowledge was consecutively handed down orally within a small group of technicians and mining overseers. In the Middle Ages these people held the same leading role as the master builders of the great cathedrals, or perhaps also alchemists. It was a small, cosmopolitan elite within which existing knowledge was passed on and further developed but not shared with the outside world. Only a few writers from that time wrote anything about mining itself. Partly, that was because this knowledge was very difficult to access. Most writers also found it simply not worth the effort to write about it. Only after the middle ages did this perception begin to change. With the improved transport and the invention of the printing press knowledge spread much more easily and faster than before. In 1500, the first printed book dedicated to mining engineering, called the Nutzlich Bergbuchleyn (The Useful Little Mining Book") by Ulrich Rulein von Calw, was published. Both De la pirotechnia and De re metallica were translated into English in the 20th century. The translation of Pirotechnia was by Cyril Stanley Smith, a senior chemist on the Manhattan Project, and Martha Teach Gnudi. Both books were illustrated with extensive, beautiful woodcuts.
The majority of the work is devoted to the more technical aspects of metalworking (such as the mining, assaying and smelting of ores), but Biringuccio also provides insights into the humanistic philosophy of the Italian Renaissance. Alchemy is also discussed. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, cryptands are a family of synthetic, bicyclic and polycyclic, multidentate ligands for a variety of cations. The Nobel Prize for Chemistry in 1987 was given to Donald J. Cram, Jean-Marie Lehn, and Charles J. Pedersen for their efforts in discovering and determining uses of cryptands and crown ethers, thus launching the now flourishing field of supramolecular chemistry. The term cryptand implies that this ligand binds substrates in a crypt, interring the guest as in a burial. These molecules are three-dimensional analogues of crown ethers but are more selective and strong as complexes for the guest ions. The resulting complexes are lipophilic. | 0 | Theoretical and Fundamental Chemistry |
Urbain led the laboratories of the Compagnie Générale d’Electricité from 1899 to 1904. Among the topics he studied was the use of rare earth oxides to manufacture arc lamps. Next he became a teacher at the École de Physique et Chimie (1905-1906) and the Sorbonne (1906, 1908). In 1907 Urbain joined the Commission Internationale des Poids Atomiques.
During World War I Urbain served in the Ministry of War as a laboratory director and technical advisor for artillery and explosives.
Following the war he taught at the École Centrale des Arts et Manufactures. In 1928 he accepted the chair of general chemistry at the Sorbonne, in addition to serving as Director of Chemistry at the Institute of Biologie. Urbain was also appointed head of the Chemistry Section of the Palais de la Découverte, director of the Chemical Treatment laboratory of Thiais, and president of the École Pratique des Hautes Etudes (2nd section). | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a hydrogen bond (or H-bond) is primarily an electrostatic force of attraction between a hydrogen (H) atom which is covalently bonded to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Such an interacting system is generally denoted , where the solid line denotes a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond. The most frequent donor and acceptor atoms are the period 2 elements nitrogen (N), oxygen (O), and fluorine (F).
Hydrogen bonds can be intermolecular (occurring between separate molecules) or intramolecular (occurring among parts of the same molecule). The energy of a hydrogen bond depends on the geometry, the environment, and the nature of the specific donor and acceptor atoms and can vary between 1 and 40 kcal/mol. This makes them somewhat stronger than a van der Waals interaction, and weaker than fully covalent or ionic bonds. This type of bond can occur in inorganic molecules such as water and in organic molecules like DNA and proteins. Hydrogen bonds are responsible for holding materials such as paper and felted wool together, and for causing separate sheets of paper to stick together after becoming wet and subsequently drying.
The hydrogen bond is also responsible for many of the physical and chemical properties of compounds of N, O, and F that seem unusual compared with other similar structures. In particular, intermolecular hydrogen bonding is responsible for the high boiling point of water (100 °C) compared to the other group-16 hydrides that have much weaker hydrogen bonds. Intramolecular hydrogen bonding is partly responsible for the secondary and tertiary structures of proteins and nucleic acids. | 0 | Theoretical and Fundamental Chemistry |
Carbonate in marine sediments predominantly comes from calcifying organisms, with a minor contribution from diagenesis and precipitation. Biogenic calcium carbonate has two polymorphs; calcite by foraminifera and coccolith and aragonite by corals and pteropods. While the distribution of foraminifera is generally global, that of corals is subtropical to tropical. Hence the distribution of fossil corals is commonly used as proxy for paleolatitudes. Kiessling et al. (1999) have compiled a database for the “Phanerozoic reefs” including their paleopostions for paleoclimatological reconstructions Maillet et al. (2021), based on the distribution of Carboniferous coral reefs demonstrated the warm paleoclimatic conditions during the Mississippian, characterized by the wide spread of coral reefs on the supercontinent of Pangea, and this is followed by early Pennsylvanian cooling, marked by rare occurrence of coral reefs. | 0 | Theoretical and Fundamental Chemistry |
The inside of the V (of total opening 39° as indicated above) is filled with transverse curved waves, each of which resembles an arc of a circle centered at a point lying on the path at a distance twice that of the arc to the wake source. This part of the pattern is independent of the speed and size of the wake source over a significant range of values.
However, at higher speeds (specifically, at large Froude number) other parts of the pattern come into play. At the tips of the transverse wave arcs their crests turn around and continue inside the V cone and towards the source, forming an overlapping pattern of narrower waves directed outside of the cone. As the sources speed increases, these shorter waves begin to dominate and form a second V within the pattern, which grows narrower as the increased speed of the source emphasizes the shorter waves that are closer to the sources path.
The angles in this pattern are not intrinsic properties of merely water: Any isentropic and incompressible liquid with low viscosity will exhibit the same phenomenon. Furthermore, this phenomenon has nothing to do with turbulence. Everything discussed here is based on the linear theory of an ideal fluid, cf. Airy wave theory.
Parts of the pattern may be obscured by the effects of propeller wash, and tail eddies behind the boat's stern, and by the boat being a large object and not a point source. The water need not be stationary, but may be moving as in a large river, and the important consideration then is the velocity of the water relative to a boat or other object causing a wake. | 1 | Applied and Interdisciplinary Chemistry |
Process requirements may change causing compressor conditions to vary. The compressor may be driven by a variable speed or constant speed machine. If driven by a constant speed electric motor it may be controlled with variable inlet guide vanes or suction and discharge throttling. Welch shows the effect of variable vane angle on the flow for a centrifugal compressor. | 0 | Theoretical and Fundamental Chemistry |
Spegatrine is an α- and α-adrenergic receptor antagonist isolated from Rauvolfia verticillata. Its dimer dispegatrine has greater antagonist affinity for α-adrenergic receptors. | 0 | Theoretical and Fundamental Chemistry |
Under certain hydrological parameters, some aquifers are more prone to contamination than other aquifers. The parameters that are taken into consideration when calculating the vulnerability of aquifers to contamination are: depth to water (factor d), net recharge (factor r), aquifer media (factor a), soil media (factor s), topography (factor t), impact of the vadose zone (factor i), and the hydraulic conductivity (factor c), which together spell out DRASTIC. Furthermore, there is a weighting factor associated with each of the parameters that can range from one to five. In addition, the lower the numbers for the DRASTIC index after the assessment of the aquifer, than the lower the risk of aquifer contamination in that area. These seven parameters derive DRASTIC summary index score, which determines which are more prone to contamination than other. The significance of the DRASTIC summary index score is that it shows areas that are more prone; as a result, the state or local authorities depending on the scale will place necessary measures in place that would prevent or mitigate contamination of the water supply.
Using GIS, a map was developed for the seven counties (Hillsborough, Polk, Manatee, Hardee, Sarasota, DeSoto, and Charlotte) in Florida, which shows the DRASTIC summary index score for the Floridan Aquifer System, Surficial Aquifer System, and Other Rocks aquifer. The developed map is a combination of multiple layers that are stacked on top of each other as shown in Figure 1. | 1 | Applied and Interdisciplinary Chemistry |
The common names of acyl groups are derived typically by replacing the -ic acid suffix of the corresponding carboxylic acid's common name with -yl (or -oyl), as shown in the table below.
In the IUPAC nomenclature of organic chemistry, the systematic names of acyl groups are derived exactly by replacing the -yl suffix of the corresponding hydrocarbyl groups systemic name (or the -oic acid suffix of the corresponding carboxylic acids systemic name) with -oyl, as shown in the table below.
The acyls are between the hydrocarbyls and the carboxylic acids.
The hydrocarbyl group names that end in -yl are not acyl groups, but alkyl groups derived from alkanes (methyl, ethyl, propyl, butyl), alkenyl groups derived from alkenes (propenyl, butenyl), or aryl groups (benzyl). | 0 | Theoretical and Fundamental Chemistry |
The ecosan approach has been criticized for being overly focused on reuse in agriculture, whilst neglecting some of the other criteria for sustainable sanitation. In fact, ecosan systems can be "unsustainable", for example, if there is too little user acceptance or if the costs of the system are too high for a given target group of users, making the system financially unsustainable in the longer term.
Some proponents of ecosan have been criticized as being too dogmatic, with an over-emphasis on environmental resource protection rather than a focus on public health protection and provision of sanitation at a very low cost (for example UDDTs, which some people call "ecosan toilets", may be more expensive to build than pit latrines, even if in the longer term they are cheaper to maintain).
The safety of ecosan systems in terms of pathogen destruction during the various treatment processes is a continuous topic of debate between proponents and opponents of ecosan systems. However, the publication of the WHO Guidelines on Reuse, with its multiple barrier concept, has gone a long way in establishing a common framework for safe reuse. Nevertheless, the question remains whether ecosan systems can ever be scaled up to reach millions of people and how they can be made sufficiently safe to operate. The initial excitement in the early 2000s by the ecosan pioneers has changed into a realization that changing attitudes and behaviors in sanitation takes a lot of patience.
Acknowledgement for ecosan came with the awarding of the Stockholm Water Prize in 2013 to Peter Morgan, a pioneer of handpumps and ventilated pit latrines (VIPs) in addition to ecosan-type toilets (the Arborloo, the Skyloo and the Fossa alterna). Peter Morgan is renowned as one of the leading creators and proponents of ecological sanitation solutions, which enable the safe reuse of human excreta to enhance soil quality and crop production. His ecosan-type toilets are now in use in countries across the globe, centred on converting a sanitary problem into a productive resource.
Also many of the research projects that the Bill and Melinda Gates Foundation have been funding since about 2011 in sanitation are dealing with resource recovery – this might well be a legacy of the ecosan concept, even if the term "ecosan" is not used by these researchers. | 1 | Applied and Interdisciplinary Chemistry |
The concept of saturation can be described using various naming systems, formulas, and analytical tests. For instance, IUPAC nomenclature is a system of naming conventions used to describe the type and location of unsaturation within organic compounds. The "degree of unsaturation" is a formula used to summarize and diagram the amount of hydrogen that a compound can bind. Unsaturation can be determined by NMR, mass spectrometry, and IR spectroscopy, or by determining a compound's bromine number or iodine number. | 0 | Theoretical and Fundamental Chemistry |
Lidocaine, a local anesthetic, has multiple inhibitory actions on the receptor and analysis of the structure of lidocaine has identified the presence of a hydrophobic aromatic ring and a hydrophilic terminal amine. Diethylamine (DEA), a molecule that mimics the hydrophilic moiety of lidocaine by way of a positively charged amine, has been found to block the channel when the receptor is open restricting the flow of Na and K ions. 2,6-Dimethylaniline (DMA), a molecule that mimics the hydrophobic moiety of lidocaine, has been found to bind the receptor at inter-subunit crevices of the trans-membrane spanning domain thereby causing non-competitive inhibition and restricting the channel from opening.
Benzocaine and tetracaine are also local anesthetics that have an inhibitory effect on the muscle‐type nicotinic receptor. Benzocaine is a permanently uncharged species that inhibits the receptor by plugging the pore of the opened channel. Tetracaine is a permanently positively charged species. It can bind to the receptor at different sites in both the open and closed conformations. Both of these local anesthetics enhance nAChR desensitization. | 1 | Applied and Interdisciplinary Chemistry |
The concentrations of O, and O are indistinguishable between VSMOW and VSMOW2, and between SLAP and SLAP2. The specification sheet gives the standard errors in these measurements. The concentration of H is unchanged in VSMOW2 as well, but is slightly increased in SLAP2. The IAEA reports:
* = , (Compare −428‰ for SLAP.)
On 6 July 2007, the tritium concentration was TU in VSMOW2, and TU in SLAP2. | 0 | Theoretical and Fundamental Chemistry |
Suppose that trans-cis-trans-2,4,6-octatriene is converted to under thermal conditions. Since the substrate octatriene is a "4n + 2" molecule, the Woodward–Hoffmann rules predict that the reaction happens in a disrotatory mechanism.
Since thermal electrocyclic reactions occur in the HOMO, it is first necessary to draw the appropriate molecular orbitals. Next, the new carbon-carbon bond is formed by taking two of the p-orbitals and rotating them 90 degrees (see diagram). Since the new bond requires constructive overlap, the orbitals must be rotated in a certain way. Performing a disrotation will cause the two black lobes to overlap, forming a new bond. Therefore, the reaction with octatriene happens through a disrotatory mechanism.
In contrast, if a conrotation had been performed then one white lobe would overlap with one black lobe. This would have caused destructive interference and no new carbon-carbon bond would have been formed.
In addition, the cis/trans geometry of the product can also be determined. When the p-orbitals were rotated inwards it also caused the two methyl groups to rotate upwards. Since both methyls are pointing "up", then the product is . | 0 | Theoretical and Fundamental Chemistry |
In exterior of the disc of radius the Biot-Savart law
restores the velocity field which is induced by the vorticity with zero-circularity and given constant velocity at infinity.
No-slip condition for
leads to the relations for :
where
is the Kronecker delta, , are the cartesian coordinates of .
In particular, from the no-slip condition follows orthogonality the vorticity to the kernel of the Weber's transform : | 1 | Applied and Interdisciplinary Chemistry |
Studies for the use of ESL as an anticonvulsant for children are under way .
Like oxcarbazepine, ESL has potential uses for the treatment of trigeminal neuralgia and bipolar disorder. A 2015 assessment showed no statistical difference to placebo for the latter disorder. | 0 | Theoretical and Fundamental Chemistry |
The most basic mechanistic flow for RNA Silencing is as follows:
(For a more detailed explanation of the mechanism, refer to the RNAi:Cellular mechanism article.)
1: RNA with inverted repeats hairpin/panhandle constructs --> 2: dsRNA --> 3: miRNAs/siRNAs --> 4: RISC --> 5: Destruction of target mRNA
# It has been discovered that the best precursor to good RNA silencing is to have single stranded antisense RNA with inverted repeats which, in turn, build small hairpin RNA and panhandle constructs. The hairpin or panhandle constructs exist so that the RNA can remain independent and not anneal with other RNA strands.
# These small hairpin RNAs and/or panhandles then get transported from the nucleus to the cytosol through the nuclear export receptor called exportin-5, and then get transformed into a dsRNA, a double stranded RNA, which, like DNA, is a double stranded series of nucleotides. If the mechanism didn't use dsRNAs, but only single strands, there would be a higher chance for it to hybridize to other "good" mRNAs. As a double strand, it can be kept on call for when it is needed.
# The dsRNA then gets cut up by a Dicer into small (21-28 nt = nucleotides long) strands of miRNAs (microRNAs) or siRNAs (short interfering RNAs.) A Dicer is an endoribonuclease RNase, which is a complex of a protein mixed with strand(s) of RNA.
# Lastly, the double stranded miRNAs/siRNAs separate into single strands; the antisense RNA strand of the two will combine with another endoribonuclease enzyme complex called RISC (RNA-induced silencing complex), which includes the catalytic component Argonaute, and will guide the RISC to break up the "perfectly complementary" target mRNA or viral genomic RNA so that it can be destroyed.
# It means that based on a short sequence specific area, a corresponding mRNA will be cut. To make sure, it will be cut in many other places as well. (If the mechanism only worked with a long stretch, then there would be higher chance that it would not have time to match to its complementary long mRNA.) It has also been shown that the repeated-associated short interference RNAs (rasiRNA) have a role in guiding chromatin modification.
For an animated explanation of the mechanism of RNAi by Nature Reviews, see the External Links section below. | 1 | Applied and Interdisciplinary Chemistry |
For each equilibrium involving a host, H, and a guest G
the equilibrium constant, , is defined as
The values of the free concentrations, and are obtained by solving the equations of mass balance with known or estimated values for the stability constants.
Then, the concentrations of each complex species may also be calculated as . The relationship between a species' concentration and the measured quantity is specific for the measurement technique, as indicated in each section above. Using this relationship, the set of parameters, the stability constant values and values of properties such as molar absorptivity or specified chemical shifts, may be refined by a non-linear least-squares refinement process. For a more detailed exposition of the theory see Determination of equilibrium constants.
Some dedicated computer programs are listed at Implementations. | 0 | Theoretical and Fundamental Chemistry |
The protein CTCF plays a heavy role in repressing the insulin-like growth factor 2 gene, by binding to the H-19 imprinting control region (ICR) along with differentially-methylated region-1 (DMR1) and MAR3. | 1 | Applied and Interdisciplinary Chemistry |
Dry nylon-6 has a glass transition temperature of . Nylon-6,6 in the dry state has a glass transition temperature of about . Whereas polyethene has a glass transition range of
The above are only mean values, as the glass transition temperature depends on the cooling rate and molecular weight distribution and could be influenced by additives. For a semi-crystalline material, such as polyethene that is 60–80% crystalline at room temperature, the quoted glass transition refers to what happens to the amorphous part of the material upon cooling. | 0 | Theoretical and Fundamental Chemistry |
It has been noted that for every degeneracy along a reaction coordinate there is a molecular orbital crossing. Thus for the butadiene to cyclobutene conversion, the two Möbius (here conrotatory) and Hückel (here disrotatory) modes are shown in Figure 5. The starting MOs are depicted in the center of the correlation diagram with blue correlation lines connecting MOs. It is seen that for the Möbius mode the four electrons in MOs 1 and 2 end in the bonding MOs (i.e. σ and π) of cyclobutene. In contrast, for the Hückel mode, there is a degeneracy and thus an MO crossing leading to two electrons (drawn in red) are headed for an antibonding MO. Thus the Hückel mode is forbidden while the Möbius mode is allowed.
One further relevant point is that the first organic correlation diagrams were in a 1961 publication on carbanion rearrangements. It had been noted that when an occupied molecular orbital becomes antibonding the reaction is inhibited and this phenomenon was correlated with a series of rearrangements. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic, stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time. The satellite view of weather around Robinson Crusoe Islands illustrates one example. | 0 | Theoretical and Fundamental Chemistry |
After decades of research, EMPA researchers and others are experimenting with concentrated sodium hydroxide (NaOH) as the thermal storage or seasonal reservoir medium for power plants and domestic space-heating. If water is added to solid or concentrated sodium hydroxide (NaOH), heat is released. The dilution is exothermic – chemical energy is released in the form of heat. Conversely, by applying heat energy into a dilute sodium hydroxide solution the water will evaporate so that the solution becomes more concentrated and thus stores the supplied heat as latent chemical energy. | 0 | Theoretical and Fundamental Chemistry |
Kyle was born in Stirling, Scotland on 2 February 1838. He completed an apprenticeship with an Edinburgh pharmacy in 1854 and became assistant to Dr Stevenson Macadam, lecturer in chemistry to Surgeons' Hall, Edinburgh. He made his first scientific discovery at the age of 18. Moving to the field of industrial chemistry, he was head of the chemical laboratory of Glasgow University and then manager of an animal charcoal manufacturer in Greenock. He was a fellow of the Royal Society of Arts.
He emigrated to Argentina in July 1862. When President-Marshall Solano Lopez of Paraguay invaded Corrientes Province in 1865 there broke out the War of the Triple Alliance and Kyle joined the medical corps of the Argentine Army as a pharmacist with the rank of lieutenant. He participated in the siege of Uruguaiana (where the defenders were reduced to living on lump sugar), the three-day battle of the Boquerón and in the Battle of Tuyutí, the bloodiest international battle in the history of South America. He served on board the hospital ship Pavón and returned to Buenos Aires in December 1866 in charge of a convoy of wounded soldiers. His wartime experiences led him to take a foundational interest in the Argentine Red Cross Society, of which he was made an honorary member in 1896. | 0 | Theoretical and Fundamental Chemistry |
A number of techniques exist to quantitatively analyze metallographic specimens. These techniques are valuable in the research and production of all metals and alloys and non-metallic or composite materials.
Microstructural quantification is performed on a prepared, two-dimensional plane through the three-dimensional part or component. Measurements may involve simple metrology techniques, e.g., the measurement of the thickness of a surface coating, or the apparent diameter of a discrete second-phase particle, (for example, spheroidal graphite in ductile iron). Measurement may also require application of stereology to assess matrix and second-phase structures. Stereology is the field of taking 0-, 1- or 2-dimensional measurements on the two-dimensional sectioning plane and estimating the amount, size, shape or distribution of the microstructure in three dimensions. These measurements may be made using manual procedures with the aid of templates overlaying the microstructure, or with automated image analyzers. In all cases, adequate sampling must be made to obtain a proper statistical basis for the measurement. Efforts to eliminate bias are required.
Some of the most basic measurements include determination of the volume fraction of a phase or constituent, measurement of the grain size in polycrystalline metals and alloys, measurement of the size and size distribution of particles, assessment of the shape of particles, and spacing between particles.
Standards organizations, including ASTM International's Committee E-4 on Metallography and some other national and international organizations, have developed standard test methods describing how to characterize microstructures quantitatively.
For example, the amount of a phase or constituent, that is, its volume fraction, is defined in ASTM E 562; manual grain size measurements are described in ASTM E 112 (equiaxed grain structures with a single size distribution) and E 1182 (specimens with a bi-modal grain size distribution); while ASTM E 1382 describes how any grain size type or condition can be measured using image analysis methods. Characterization of nonmetallic inclusions using standard charts is described in ASTM E 45 (historically, E 45 covered only manual chart methods and an image analysis method for making such chart measurements was described in ASTM E 1122. The image analysis methods are currently being incorporated into E 45). A stereological method for characterizing discrete second-phase particles, such as nonmetallic inclusions, carbides, graphite, etc., is presented in ASTM E 1245. | 1 | Applied and Interdisciplinary Chemistry |
As of 2022, there have been five Nobel Prizes in Physics for superconductivity related subjects:
* Heike Kamerlingh Onnes (1913), "for his investigations on the properties of matter at low temperatures which led, inter alia, to the production of liquid helium".
* John Bardeen, Leon N. Cooper, and J. Robert Schrieffer (1972), "for their jointly developed theory of superconductivity, usually called the BCS-theory".
* Leo Esaki, Ivar Giaever, and Brian D. Josephson (1973), "for their experimental discoveries regarding tunneling phenomena in semiconductors and superconductors, respectively" and "for his theoretical predictions of the properties of a supercurrent through a tunnel barrier, in particular those phenomena which are generally known as the Josephson effects".
* Georg Bednorz and K. Alex Müller (1987), "for their important break-through in the discovery of superconductivity in ceramic materials".
* Alexei A. Abrikosov, Vitaly L. Ginzburg, and Anthony J. Leggett (2003), "for pioneering contributions to the theory of superconductors and superfluids". | 0 | Theoretical and Fundamental Chemistry |
Bridgman’s theorem restricts the type of function that can be used to define a physical quantity from general (dimensionally compounded) quantities to only products of powers of the quantities, unless some of the independent quantities are algebraically combined to yield dimensionless groups, whose functions are grouped together in the dimensionless numeric multiplying factor. This excludes polynomials of more than one term or transcendental functions not of that form.
Scalar arguments to transcendental functions such as exponential, trigonometric and logarithmic functions, or to inhomogeneous polynomials, must be dimensionless quantities. (Note: this requirement is somewhat relaxed in Siano's orientational analysis described below, in which the square of certain dimensioned quantities are dimensionless.)
While most mathematical identities about dimensionless numbers translate in a straightforward manner to dimensional quantities, care must be taken with logarithms of ratios: the identity , where the logarithm is taken in any base, holds for dimensionless numbers and , but it does not hold if and are dimensional, because in this case the left-hand side is well-defined but the right-hand side is not.
Similarly, while one can evaluate monomials () of dimensional quantities, one cannot evaluate polynomials of mixed degree with dimensionless coefficients on dimensional quantities: for , the expression makes sense (as an area), while for , the expression does not make sense.
However, polynomials of mixed degree can make sense if the coefficients are suitably chosen physical quantities that are not dimensionless. For example,
This is the height to which an object rises in time if the acceleration of gravity is 9.8 and the initial upward speed is 500 . It is not necessary for to be in seconds. For example, suppose = 0.01 minutes. Then the first term would be | 1 | Applied and Interdisciplinary Chemistry |
Paritaprevir (previously known as ABT-450) is an acylsulfonamide inhibitor of the NS3-4A serine protease manufactured by Abbott Laboratories that shows promising results as a treatment of hepatitis C. When given in combination with ritonavir and ribavirin for 12 weeks, the rate of sustained virologic response at 24 weeks after treatment has been estimated to be 95% for those with hepatitis C virus genotype 1. Resistance to treatment with paritaprevir is uncommon, because it targets the binding site, but has been seen to arise due to mutations at positions 155 and 168 in NS3.
Paritaprevir was a component of Viekira Pak and Technivie. In May 2018, the FDA announced that Technivie and Viekira were to be discontinued. The discontinuation was voluntary and not related to the safety, quality, or efficacy of the medicine. It was estimated that both medications would be available until January 1, 2019. | 1 | Applied and Interdisciplinary Chemistry |
Many modifications have been reported that influence the reactivity of this reagent. The compound adopts a complex cluster structure (the adjacent picture is a simplified cartoon), and additives that modify the cluster affect the reactivity of the reagent. For example, DMF, DMSO, hexamethylphosphoramide (HMPA), and 18-crown-6 interact with the potassium center, yielding solvent separated ion pairs such as K(DMSO) and tert-BuO. Whereas in benzene, on the other hand, the compound remains as a cluster structure, which is less basic. Even in polar solvents, it is not as strong as amide bases, e.g., lithium diisopropylamide, but stronger than potassium hydroxide. Its steric bulk inhibits the group from participating in nucleophilic addition, such as in a Williamson ether synthesis or related S2 reactions.
Substrates that are deprotonated by potassium t-butoxide include terminal acetylenes and active methylene compounds. It is useful in dehydrohalogenation reactions. Illustrating the latter behavior, potassium tert-butoxide reacts with chloroform yielding dichlorocarbene, which is useful for dichlorocyclopropanations. Potassium tert-butoxide can abstract a beta-proton from alkylammonium cations, leading to the Hofmann product via an elimination reaction. | 0 | Theoretical and Fundamental Chemistry |
Because of concerns over Peak oil, pollution and climate change, as well the oil price increases since 2003, non-petroleum alternatives have become more popular. This has led to the introduction of biobitumen alternatives that are more environmentally friendly and nontoxic.
For millions of people living in and around cities, heat islands are of growing concern. This phenomenon describes urban and suburban temperatures that are 1 to 6 °C (2 to 10 °F) hotter than nearby rural areas. Elevated temperatures can impact communities by increasing peak energy demand, air conditioning costs, air pollution levels, and heat-related illness and mortality. There are common-sense measures that communities can take to reduce the negative effects of heat islands, such as replacing conventional black asphalt road surfaces with the new pigmentable bitumen that gives lighter colors. | 0 | Theoretical and Fundamental Chemistry |
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Cleavage factors are two closely associated protein complexes involved in the cleavage of the 3' untranslated region of a newly synthesized pre-messenger RNA (mRNA) molecule in the process of gene transcription. The cleavage is the first step in adding a polyadenine tail to the pre-mRNA, which is one of the necessary post-transcriptional modifications necessary for producing a mature mRNA molecule.
In mammals, the two cleavage factors are known as CFIm and CFIIm. The proteins that constitute these complexes are recruited to the cleavage site by cleavage and polyadenylation specificity factor and cleavage stimulatory factor, and form a larger complex that also includes polyadenine polymerase, which performs the polyadenylation reaction. | 1 | Applied and Interdisciplinary Chemistry |
Sublimation is a direct phase transition from the solid phase to the gas phase, skipping the intermediate liquid phase. Because it does not involve the liquid phase, it is not a form of vaporization. | 0 | Theoretical and Fundamental Chemistry |
The slow but continuous production of hydrogen in deep low-permeability argillaceous formations could represent a problem for the long-term disposal of radioactive waste (Ortiz et al., 2001; Nagra, 2008; recent Nagra NTB reports). Indeed, a gas pressure build-up could occur if the rate of hydrogen production by the anaerobic corrosion of carbon-steel and by the subsequent transformation of green rust into magnetite should exceed the rate of diffusion of dissolved H in the pore water of the formation. The question is presently the object of many studies (King, 2008; King and Kolar, 2009; Nagra Technical Reports 2000–2009) in the countries (Belgium, Switzerland, France, Canada) envisaging the option of disposal in clay formation. | 1 | Applied and Interdisciplinary Chemistry |
Leslie Hicks is an American associate professor of analytical chemistry at the University of North Carolina at Chapel Hill. Her work primarily focuses on the study of proteomics and protein post-translational modifications using mass spectrometry, and identifying biologically active peptides in plants. | 0 | Theoretical and Fundamental Chemistry |
Imprelis is a selective herbicide created by DuPont. The active ingredient is aminocyclopyrachlor, a synthetic auxin. | 1 | Applied and Interdisciplinary Chemistry |
Co-translational and post-translational covalent modifications enable proteins to develop higher levels of complexity in cellular function, further adding diversity to the proteome. The addition of myristoyl-CoA to a protein can occur during protein translation or after. During co-translational addition of the myristoyl group, the N-terminal glycine is modified following cleavage of the N-terminal methionine residue in the newly forming, growing polypeptide. Post-translational myristoylation typically occurs following a caspase cleavage event, resulting in the exposure of an internal glycine residue, which is then available for myristic acid addition. | 1 | Applied and Interdisciplinary Chemistry |
A large class of drugs are enzyme inhibitors that bind to enzymes in the body and inhibit their activity. In this case it is the drug-target residence time (the length of time the drug stays bound to the target) that is of interest. Drugs with long residence times are desirable because they remain effective for longer and therefore can be used in lower doses. This residence time is determined by the kinetics of the interaction, such as how complementary the shape and charges of the target and drug are and whether outside solvent molecules are kept out of the binding site (thereby preventing them from breaking any bonds formed), and is proportional to the half-life of the chemical dissociation. One way to measure the residence time is in a preincubation-dilution experiment where a target enzyme is incubated with the inhibitor, allowed to approach equilibrium, then rapidly diluted. The amount of product is measured and compared to a control in which no inhibitor is added.
Residence time can also refer to the amount of time that a drug spends in the part of the body where it needs to be absorbed. The longer the residence time, the more of it can be absorbed. If the drug is delivered in an oral form and destined for the upper intestines, it usually moves with food and its residence time is roughly that of the food. This generally allows 3 to 8 hours for absorption. If the drug is delivered through a mucous membrane in the mouth, the residence time is short because saliva washes it away. Strategies to increase this residence time include bioadhesive polymers, gums, lozenges and dry powders. | 0 | Theoretical and Fundamental Chemistry |
Drugs from the same therapeutic or chemical class are usually given names with the same stem. Stems are mostly placed word-finally, but in some cases word-initial stems are used. They are collected in a publication informally known as the Stem Book.
Examples are:
* -anib for angiogenesis inhibitors (e.g. pazopanib)
* -anserin for serotonin receptor antagonists, especially 5-HT antagonists (e.g. ritanserin and mianserin)
* -ant for various receptors antagonists (e.g. aticaprant and rimonabant)
* -arit for antiarthritic agents (e.g. lobenzarit)
* -ase for enzymes (e.g. alteplase)
* -azepam or -azolam for benzodiazepines (e.g. diazepam and alprazolam)
* -caine for local anaesthetics (e.g. procaine or cocaine)
* -cain- for class I antiarrhythmics (e.g. procainamide)
* -coxib for COX-2 inhibitors, a type of anti-inflammatory drugs (e.g. celecoxib)
* -mab for monoclonal antibodies (e.g. infliximab); see Nomenclature of monoclonal antibodies
*-- for cannabinoid receptor agonists (e.g. cannabidiol, dronabinol)
* for cannabinoid receptor antagonists
* -olol for beta blockers (e.g. atenolol)
* -pril for ACE inhibitors (e.g. captopril)
* -sartan for angiotensin II receptor antagonists (e.g. losartan)
* -tinib for tyrosine kinase inhibitors (e.g. imatinib)
* -vastatin for HMG-CoA reductase inhibitors, a group of cholesterol-lowering agents (e.g. simvastatin)
* -vir for antivirals (e.g. aciclovir or ritonavir)
** for antiretroviral protease inhibitors (e.g. darunavir)
* arte- for artemisinin antimalarials (e.g. artemether)
* cef- for cephalosporins (e.g. cefalexin)
* io- for iodine-containing radiopharmaceuticals (e.g. iobenguane)
* -vec for gene therapy vectors (e.g. alipogene tiparvovec)
* -meran for messenger RNA products (e.g. tozinameran) | 1 | Applied and Interdisciplinary Chemistry |
The Barber–Layden–Power effect (BLP effect or colloquially Bleep) is a blast wave phenomenon observed in the immediate aftermath of the successful functioning of air-delivered high-drag ordnance at the target. In common with a typical blast wave, the flow field can be approximated as a lead shock wave, followed by a self-similar subsonic flow field. The phenomenon appears to adhere to the basic principles of the Sedov solution. | 1 | Applied and Interdisciplinary Chemistry |
Environmental Toxicology and Chemistry is a monthly peer-reviewed scientific journal covering environmental toxicology and environmental chemistry. It was established in 1982 and is published by Wiley-Blackwell in conjunction with the Society of Environmental Toxicology and Chemistry. The founding editor-in-chief was C.H. Ward (Rice University), and the current one is G.A. Burton, Jr. (University of Michigan). According to the Journal Citation Reports, the journal has a 2021 impact factor of 4.218, ranking it 117th out of 279 journals in the category Environmental sciences and 29th out of 94 in the category Toxicology. | 1 | Applied and Interdisciplinary Chemistry |
Stable isotopes do not decay, and the heavy and light isotope masses affect how they partition within the environment. Any deviation from a random distribution of the light and heavy isotopes within the environment is called fractionation, and consistent fractionations as a result of a particular process or reaction are called "isotope effects." | 0 | Theoretical and Fundamental Chemistry |
The potential energy density
with ρ the fluid density, is one of the infinite number of invariants of the KdV equation. This can be seen by multiplying the KdV equation with the surface elevation η(x,t); after repeated use of the chain rule the result is:
which is in conservation form, and is an invariant after integration over the interval of periodicity—the wavelength for a cnoidal wave. The potential energy is not an invariant of the BBM equation, but ρg [η + h (∂ η)] is.
First the variance of the surface elevation in a cnoidal wave is computed. Note that η = −(1/λ) ∫ H cn(ξ/Δ|m) dx, cn(ξ/Δ|m) = cos ψ(ξ) and λ = 2 Δ K(m), so
The potential energy, both for the KdV and the BBM equation, is subsequently found to be
The infinitesimal wave-height limit (m → 0) of the potential energy is E = ρ g H, which is in agreement with Airy wave theory. The wave height is twice the amplitude, H = 2a, in the infinitesimal wave limit. | 1 | Applied and Interdisciplinary Chemistry |
Elastomerically bound recycled glass porous pavement consisting of bonding processed post-consumer glass with a mixture of resins, pigments, granite and binding agents. Approximately 75 percent of glass in the U.S. is disposed in landfills. | 1 | Applied and Interdisciplinary Chemistry |
The nucleosome contains over 120 direct protein-DNA interactions and several hundred water-mediated ones. Direct protein - DNA interactions are not spread evenly about the octamer surface but rather located at discrete sites. These are due to the formation of two types of DNA binding sites within the octamer; the α1α1 site, which uses the α1 helix from two adjacent histones, and the L1L2 site formed by the L1 and L2 loops. Salt links and hydrogen bonding between both side-chain basic and hydroxyl groups and main-chain amides with the DNA backbone phosphates form the bulk of interactions with the DNA. This is important, given that the ubiquitous distribution of nucleosomes along genomes requires it to be a non-sequence-specific DNA-binding factor. Although nucleosomes tend to prefer some DNA sequences over others, they are capable of binding practically to any sequence, which is thought to be due to the flexibility in the formation of these water-mediated interactions. In addition, non-polar interactions are made between protein side-chains and the deoxyribose groups, and an arginine side-chain intercalates into the DNA minor groove at all 14 sites where it faces the octamer surface.
The distribution and strength of DNA-binding sites about the octamer surface distorts the DNA within the nucleosome core. The DNA is non-uniformly bent and also contains twist defects. The twist of free B-form DNA in solution is 10.5 bp per turn. However, the overall twist of nucleosomal DNA is only 10.2 bp per turn, varying from a value of 9.4 to 10.9 bp per turn. | 1 | Applied and Interdisciplinary Chemistry |
The direct liquid-introduction (DLI) interface was developed in 1980. This interface was intended to solve the problem of evaporation of liquid inside the capillary inlet interface. In DLI, a small portion of the LC flow was forced through a small aperture or diaphragm (typically 10 μm in diameter) to form a liquid jet composed of small droplets that were subsequently dried in a desolvation chamber. The analytes were ionized using a solvent-assisted chemical ionization source, where the LC solvents acted as reagent gases. To use this interface, it was necessary to split the flow coming out of the LC column because only a small portion of the effluent (10 to 50 μl/min out of 1 ml/min) could be introduced into the source without raising the vacuum pressure of the MS system too high. Alternately, Henion at Cornell University had success with using micro-bore LC methods so that the entire (low) flow of the LC could be used. One of the main operational problems of the DLI interface was the frequent clogging of the diaphragm orifices. The DLI interface was used between 1982 and 1985 for the analysis of pesticides, corticosteroids, metabolites in horse urine, erythromycin, and vitamin B. However, this interface was replaced by the thermospray interface, which removed the flow rate limitations and the issues with the clogging diaphragms.
A related device was the particle beam interface (PBI), developed by Willoughby and Browner in 1984. Particle beam interfaces took over the wide applications of MBI for LC–MS in 1988. The PBI operated by using a helium gas nebulizer to spray the eluant into the vacuum, drying the droplets and pumping away the solvent vapour (using a jet separator) while the stream of monodisperse dried particles containing the analyte entered the source. Drying the droplets outside of the source volume, and using a jet separator to pump away the solvent vapour, allowed the particles to enter and be vapourized in a low-pressure EI source. As with the MBI, the ability to generate library-searchable EI spectra was a distinct advantage for many applications. Commercialized by Hewlett Packard, and later by VG and Extrel, it enjoyed moderate success, but has been largely supplanted by the atmospheric pressure interfaces such as electrospray and APCI which provide a broader range of compound coverage and applications. | 0 | Theoretical and Fundamental Chemistry |
Interactions between various objects were studied within the DH and PB models by many researchers. Some of the relevant results are summarized in the following.
Non-planar geometries: Objects of other than planar geometries can be treated within the Derjaguin approximation, provided their size is substantially larger than the Debye length. This approximation has been used to estimate the force between two charged colloidal particles as shown in the first figure of this article. The exponential nature of these repulsive forces and the fact that its range is given by the Debye length was confirmed experimentally by direct force measurements, including surface forces apparatus, colloidal probe technique, or optical tweezers. The interaction free energy involving two spherical particles within the DH approximation follows the Yukawa or screened Coulomb potential
where r is the center-to-center distance, Q is the particle charge, and a the particle radius. This expression is based on the superposition approximation and is only valid at large separations. This equation can be extended to more highly charged particles by reinterpreting the charge Q as an effective charge. To address the interactions in other situation, one must resort to numerical solutions of the DH or PB equation.
Non-uniform or patchy charge distribution: Interaction between surfaces with non-uniform and periodic charge distribution has been analyzed within the DH approximation. Such surfaces are referred to have a mosaic or patch-charge distribution. One important conclusion from these studies is that there is an additional attractive electrostatic contribution, which also decays exponentially. When the non-uniformities are arranged in a quadratic lattice with spacing b, the decay length q of this additional attraction can be expressed as
At high salt levels, this attraction is screened as the interaction between uniformly charged surfaces. At lower salt levels, however, the range of this attraction is related to the characteristic size of the surface charge heterogeneities.
Three-body forces: The interactions between weakly charged objects are pair-wise additive due to the linear nature of the DH approximation. On the PB level, however, attractive three-body forces are present. The interaction free energy between three objects 1, 2, and 3 can be expressed as
where F are the pair free energies and ΔF is the non-additive three-body contribution. These three-body contributions were found to be attractive on the PB level, meaning that three charged objects repel less strongly than what one would expect on the basis of pair-wise interactions alone. | 0 | Theoretical and Fundamental Chemistry |
A PV diagram plots the change in pressure P with respect to volume V for some process or processes. Typically in thermodynamics, the set of processes forms a cycle, so that upon completion of the cycle there has been no net change in state of the system; i.e. the device returns to the starting pressure and volume.
The figure shows the features of an idealized PV diagram. It shows a series of numbered states (1 through 4). The path between each state consists of some process (A through D) which alters the pressure or volume of the system (or both).
A key feature of the diagram is that the amount of energy expended or received by the system as work can be measured because the net work is represented by the area enclosed by the four lines.
In the figure, the processes 1-2-3 produce a work output, but processes from 3-4-1 require a smaller energy input to return to the starting position / state; so the net work is the difference between the two.
This figure is highly idealized, in so far as all the lines are straight and the corners are right angles. A diagram showing the changes in pressure and volume in a real device will show a more complex shape enclosing the work cycle. (). | 0 | Theoretical and Fundamental Chemistry |
The simplest type of foil is a flat plate. When set at an angle (the angle of attack) to the flow the plate will deflect the fluid passing over and under it, and this deflection will result in a lift force on the plate. However, while it does generate lift, it also generates a large amount of drag.
Since even a flat plate can generate lift, a significant factor in foil design is the minimization of drag. An example of this is the rudder of a boat or aircraft. When designing a rudder a key design factor is the minimization of drag in its neutral position, which is balanced with the need to produce sufficient lift with which to turn the craft at a reasonable rate.
Other types of foils, both natural and man-made, seen both in air and water, have features that delay or control the onset of lift-induced drag, flow separation, and stall (see Bird flight, Fin, Airfoil, Placoid scale, Tubercle, Vortex generator, Canard (close-coupled), Blown flap, Leading edge slot, Leading edge slats), as well as Wingtip vortices (see Winglet). | 1 | Applied and Interdisciplinary Chemistry |
*5.B.1 The Phagocyte (gp91phox) NADPH Oxidase Family
*5.B.2 The Eukaryotic Cytochrome b561 (Cytb561) Family
*5.B.3 The Geobacter Nanowire Electron Transfer (G-NET) Family
*5.B.4 The Plant Photosystem I Supercomplex (PSI) Family
*5.B.5 The Extracellular Metal Oxido-Reductase (EMOR) Family
*5.B.6 The Transmembrane Epithelial Antigen Protein-3 Ferric Reductase (STEAP) Family
*5.B.7 The YedZ (YedZ) Family
*5.B.8 The Trans-Outer Membrane Electron Transfer Porin/Cytochrome Complex (ET-PCC) Family
*5.B.9 The Porin-Cytochrome c (Cyc2) Family | 1 | Applied and Interdisciplinary Chemistry |
The International Association for Sports Surface Sciences (ISSS) is the union of labs and experts in the field of sports surfaces. It was founded in 1985 in Switzerland. Its aims are the exchange of information and ideas regarding testing sports surfaces such as sports hall floors, synthetic surfaces of athletic tracks and artificial turf surfaces. Members are located all over the world.
The ISSS is officially related to the IAAF. The ISSS has a board of directors consisting of Hans J. Kolitzus (CH/D), Vic Watson (GB), Ties Joosten (NL) and Alastair Cox (GB)). The head office is located in Switzerland. The ISSS organizes regular Technical Meetings with experts from the industry to discuss issues of common interest. | 0 | Theoretical and Fundamental Chemistry |
Metalation (Alt. spelling: Metallation) is a chemical reaction that forms a bond to a metal. This reaction usually refers to the replacement of a halogen atom in an organic molecule with a metal atom, resulting in an organometallic compound. In the laboratory, metalation is commonly used to activate organic molecules during the formation of C—X bonds (where X is typically carbon, oxygen, or nitrogen), which are necessary for the synthesis of many organic molecules.
In synthesis, metallated reagents are typically involved in nucleophilic substitution, single-electron-transfer (SET), and redox chemistry with functional groups on other molecules (including but not limited to ketones, aldehydes and alkyl halides). Metallated molecules may also participate in acid-base chemistry, with one organometallic reagent deprotonating an organic molecule to create a new organometallic reagent.
The most common classes of metallated compounds are organolithium reagents and Grignard reagents. However, other organometallic compounds — such as organozinc compounds — also experience common use in both laboratory and industrial applications. | 0 | Theoretical and Fundamental Chemistry |
During barcode sequencing, high molecular weight DNA samples that contain the targeted DNA sequence, ranging from fifty to several hundred kilobases in size, are combined with gel beads containing unique barcodes, enzymes, and sequencing reagents. Microfluidic device can partition input DNA molecules into individual nanoliter-sized droplets of water-in-oil emulsion, called GEMs. Each GEM contains gel beads coated with the same barcode and primers, and a small amount of DNA. The primers are complementary to specific regions of the DNA molecule, allowing for amplification of the DNA in the droplets through PCR. The barcodes enable the identification and grouping of sequencing reads that originate from the same long fragment, which is crucial for downstream analysis. | 1 | Applied and Interdisciplinary Chemistry |
Seyferth was born in 1929 in Chemnitz, Saxony, Germany, and received his college education at the University of Buffalo. His PhD thesis dealt with main group chemistry under the mentorship of Eugene G. Rochow at Harvard. Seyferth spent his entire academic career at , focusing initially on organophosphorus, organosilicon, and organomercury chemistry. He also contributed to organocobalt chemistry and organoiron chemistry, e.g. the popularization of FeS(CO). He died on Saturday, June 6, 2020, due to complications from COVID-19 during the COVID-19 pandemic in Massachusetts.
Seyferth has been widely recognized, notably with the American Chemical Society Award in Organometallic Chemistry and election to the U.S. National Academy of Sciences. | 0 | Theoretical and Fundamental Chemistry |
When acidic solution of ephedrine or pseudoephedrine is mixed with copper sulfate and sodium hydroxide solutions, a violet color is formed. Upon shaking with ether, the organic phase turns red/purple and the aqueous phase turns blue. The staining is based on the formation of a coordination complex of two ephedrine molecules and a copper ion Cu
This works, because, in an alkaline solution, the hydroxyl and amine groups are de-protonated, leaving a negative charge on the central atoms. They can then form a coordination complex with the positively-charged cupric ions from the copper sulfate. Phenethylamines (and their derivatives) that have a β-ketone group will also react, but less predictably and dramatically (the carbonyl oxygen is less nucleophilic than the deprotonated hydroxyl group). They usually form a deeper blue color, and often a grey-ish precipitate. This includes the cathinones and presumably βK-2C-x compounds. | 0 | Theoretical and Fundamental Chemistry |
The following content uses protein primary structure single-letter location. A "[n]" prefix indicates the N-terminus and a "[c]" suffix indicates the C-terminus; sequences lacking either are found in the middle of the protein. | 1 | Applied and Interdisciplinary Chemistry |
An equation of state introduced by R. H. Cole
where is a reference density, is the adiabatic index, and is a parameter with pressure units. | 0 | Theoretical and Fundamental Chemistry |
If the flow is chaotic, then small initial errors, , in a
trajectory will diverge exponentially.
We are interested in calculating the stability—i.e., how fast do nearby
trajectories diverge?
The Jacobi matrix of the velocity field,
provides information about the local rate of divergence of
nearby trajectories or the local rate of stretching of
Lagrangian space.
We define the matrix H such that:
where I is the identity matrix. It follows that:
The finite-time Lyapunov exponents are defined as the time average of the logarithms
of the lengths of the principal components of the vector H over a time t:
where is the ith Lyapunov exponent
of the system, while is the ith principal component
of the matrix H.
If we start with a set of orthonormal initial error vectors,
then the matrix H will map them to a set
of final orthogonal error vectors of length .
The action of the system maps an infinitesimal sphere of
inititial points to an ellipsoid whose major axis is given by the
while the minor axis is given by ,
where N is the number of dimensions.
This definition of Lyapunov exponents is both more elegant and more appropriate
to real-world, continuous-time dynamical systems than the more usual definition based
on discrete function maps.
Chaos is defined as the existence of at least one positive Lyapunov exponent.
In a chaotic system, we call the Lyapunov exponent the asymptotic value of the greatest eigenvalue of H:
If there is any significant difference between the Lyapunov exponents then as an error vector evolves forward in time, any displacement in the direction of largest growth will tend to be magnified. Thus:
The Lyapunov exponent of a flow is a unique quantity, that characterizes the asymptotic separation of fluid particles in a given flow. It is often used as a measure of the
efficiency of mixing, since it measures how fast trajectories separate from each other because of chaotic advection. The Lyapunov exponent can be computed by different methods:
* by following one single trajectory for very long times and computing .
* or by following an ensemble of trajectories for a given period of time, and computing the ensemble average:
The equivalence of the two methods is due to the ergodicity of the chaotic system. | 1 | Applied and Interdisciplinary Chemistry |
Nuclear spins exhibit a magnetic dipole moment, which generates a magnetic field that interacts with the dipole moments of other nuclei (dipolar coupling). The magnitude of the interaction is dependent on the gyromagnetic ratio of the spin species, the internuclear distance r, and the orientation, with respect to the external magnetic field B, of the vector connecting the two nuclear spins (see figure). The maximum dipolar coupling is given by the dipolar coupling constant d,
where γ and γ are the gyromagnetic ratios of the nuclei, is the reduced Planck's constant, and is the vacuum permeability. In a strong magnetic field, the dipolar coupling depends on the angle θ between the internuclear vector and the external magnetic field B (figure) according to
D becomes zero for . Consequently, two nuclei with a dipolar coupling vector at an angle of θ = 54.7° to a strong external magnetic field have zero dipolar coupling. θ is called the magic angle. Magic angle spinning is typically used to remove dipolar couplings weaker than the spinning rate. | 0 | Theoretical and Fundamental Chemistry |
Annual Review of Physical Chemistry is a peer-reviewed scientific journal published by Annual Reviews. It covers all topics pertaining to physical chemistry. The editors are Todd J. Martínez (Stanford University) and Anne McCoy (University of Washington). As of 2023, Annual Review of Physical Chemistry is being published as open access, under the Subscribe to Open model. The journal is indexed in the Science Citation Index Expanded and Chemical Abstracts Service. As of 2023, Journal Citation Reports gives it a 2022 impact factor of 14.7. | 0 | Theoretical and Fundamental Chemistry |
KAP1 forms a complex with MDM2 (a ubiquitin E3 ligase) that binds to p53. The complex marks the bound p53 for degradation. p53 is a known precursor of apoptosis that facilitates the synthesis of proteins necessary for cell death so its degradation results in apoptosis inhibition. | 1 | Applied and Interdisciplinary Chemistry |
As an ACE inhibitor, moexipril causes a decrease in ACE. This blocks the conversion of angiotensin I to angiotensin II. Blockage of angiotensin II limits hypertension within the vasculature. Additionally, moexipril has been found to possess cardioprotective properties. Rats given moexipril one week prior to induction of myocardial infarction, displayed decreased infarct size. The cardioprotective effects of ACE inhibitors are mediated through a combination of angiotensin II inhibition and bradykinin proliferation. Increased levels of bradykinin stimulate in the production of prostaglandin E and nitric oxide, which cause vasodilation and continue to exert antiproliferative effects. Inhibition of angiotensin II by moexipril decreases remodeling effects on the cardiovascular system. Indirectly, angiotensin II stimulates of the production of endothelin 1 and 3 (ET1, ET3) and the transforming growth factor beta-1 (TGF-β1), all of which have tissue proliferative effects that are blocked by the actions of moexipril. The antiproliferative effects of moexipril have also been demonstrated by in vitro studies where moexipril inhibits the estrogen-stimulated growth of neonatal cardiac fibroblasts in rats. Other ACE inhibitors have also been found to produce these actions, as well. | 0 | Theoretical and Fundamental Chemistry |
Ores mined for their base metal content often contain precious metals, usually gold and silver. These have to be removed from the base metals as part of the refining processes used to purify the metals. In the case of copper electrolytic refining, the gold and silver fall to the bottom of the electrolytic refining cell as “slimes” that are subsequently treated to recover gold and silver as byproducts. In the case of lead refining, silver, gold, and other precious metals are typically removed using the Parkes process, in which zinc is added to the impure lead bullion to collect the silver, gold and other precious metals.
The BRM lead refinery at Northfleet in England uses the Parkes process followed by liquation and a vacuum induction retort to recover precious metals. The product of this process is a feed for the BBOC consisting of a mixture of lead, silver (60–75%), zinc (2–3%) and copper (2–3%), with trace amounts of gold. Prior to the development of the BBOC, BRM used cupellation in a 15 tonne (“t”) reverberatory cupellation furnace to recover the precious metals from this mixture. Three of these furnaces were used to produce 450 t of silver per year.
Cupellation works by exposing the mixture at high temperature to air or oxygen. The base metals, being less noble than silver and gold, react with the oxygen to form their oxides, which separate from the noble metals to form a slag that floats on the top of the residual metals (or “doré”). At BRM, the doré contains 99.7% silver.
To maximize the oxygen transfer from the blast air in the reverberatory furnace, a shallow bath is used, thus increasing the surface-area-to-volume ratio of the furnace.
A problem with using reverberatory furnaces for cupellation is that the zinc oxidizes first, forming a crust across the top of the molten material. This crust prevents the penetration of oxygen to the rest of the material, and so it has to be manually broken up and removed using a rabble bar. This is both labor-intensive and also results in the loss of some of the silver. Similarly, the oxidized lead slag has to be removed when it forms to maintain the operation, and its removal also results in loss of silver.
The BBOC was developed by BRM personnel as a way of reducing these and other problems, such as low energy efficiency and low oxygen utilization, associated with the reverberatory cupellation process. | 1 | Applied and Interdisciplinary Chemistry |
C/EBPβ function is regulated by multiple mechanisms, including phosphorylation, acetylation, activation, autoregulation, and repression via other transcription factors, oncogenic elements, or chemokines. C/EBPβ can interact with CREB, NF-κB, and other proteins, leading to a trans-activation potential.
Phosphorylation of C/EBPβ can have an activation or a repression effect. For example, phosphorylation of threonine 235 in human C/EBPβ, or of threonine 188 in mouse and rat C/EBPβ, is important for C/EBPβ trans-activation capacity. Phosphorylation(s) of C/EBPβ in its regulatory domain can also modulate its function.
It was shown in C. elegans that multiple cis elements of cebp-1 mRNA 3UTR interact with mak-2' to upregulate expression of CEBP-1 in neuronal development. | 1 | Applied and Interdisciplinary Chemistry |
Inclusions are usually other minerals or rocks, but may also be water, gas or petroleum. Liquid or vapor inclusions are known as fluid inclusions. In the case of amber it is possible to find insects and plants as inclusions.
The analysis of atmospheric gas bubbles as inclusions in ice cores is an important tool in the study of climate change.
A xenolith is a pre-existing rock which has been picked up by a lava flow. Melt inclusions form when bits of melt become trapped inside crystals as they form in the melt. | 1 | Applied and Interdisciplinary Chemistry |
Temperature ranges are defined as room temperature for certain products and processes in industry, science, standards, and consumer goods. For instance, for the shipping and storage of pharmaceuticals, the United States Pharmacopeia-National Formulary (USP-NF) defines controlled room temperature as between , with excursions between allowed, provided the mean kinetic temperature does not exceed . The European Pharmacopoeia defines it as being simply , and the Japanese Pharmacopeia defines "ordinary temperature" as , with room temperature being . Merriam-Webster gives as a medical definition a range of as being suitable for human occupancy, and at which laboratory experiments are usually performed. | 1 | Applied and Interdisciplinary Chemistry |
Lowering photorespiration may not result in increased growth rates for plants. Photorespiration may be necessary for the assimilation of nitrate from soil. Thus, a lowering in photorespiration by genetic engineering or because of increasing atmospheric carbon dioxide may not benefit plants as has been proposed. Several physiological processes may be responsible for linking photorespiration and nitrogen assimilation. Photorespiration increases availability of NADH, which is required for the conversion of nitrate to nitrite. Certain nitrite transporters also transport bicarbonate, and elevated has been shown to suppress nitrite transport into chloroplasts. However, in an agricultural setting, replacing the native photorespiration pathway with an engineered synthetic pathway to metabolize glycolate in the chloroplast resulted in a 40 percent increase in crop growth.
Although photorespiration is much lower in C species, it is still an essential pathwaymutants without functioning 2-phosphoglycolate metabolism cannot grow in normal conditions. One mutant was shown to rapidly accumulate glycolate.
Although the functions of photorespiration remain controversial, it is widely accepted that this pathway influences a wide range of processes from bioenergetics, photosystem II function, and carbon metabolism to nitrogen assimilation and respiration. The oxygenase reaction of RuBisCO may prevent depletion near its active sites and contributes to the regulation of CO concentration in the atmosphere The photorespiratory pathway is a major source of hydrogen peroxide () in photosynthetic cells. Through production and pyrimidine nucleotide interactions, photorespiration makes a key contribution to cellular redox homeostasis. In so doing, it influences multiple signalling pathways, in particular, those that govern plant hormonal responses controlling growth, environmental and defense responses, and programmed cell death.
It has been postulated that photorespiration may function as a "safety valve", preventing the excess of reductive potential coming from an overreduced NADPH-pool from reacting with oxygen and producing free radicals (oxidants), as these can damage the metabolic functions of the cell by subsequent oxidation of membrane lipids, proteins or nucleotides. The mutants deficient in photorespiratory enzymes are characterized by a high redox level in the cell, impaired stomatal regulation, and accumulation of formate. | 0 | Theoretical and Fundamental Chemistry |
To 6.25 g (50 mmol) of 4,4-dimethyl-2-cyclohexen-1-one and 0.5 g (5.6 mmol) of cuprous cyanide in 400 mL of diethyl ether at –23° under argon was added 100 mL (~0.75 M in diethyl ether) of 5-trimethylsilyl-4-pentynylmagnesium iodide during 4 hours. Methyl chloroformate (8 mL, 100 mmol) was added and stirring continued for 1 hour at –23° and 0.5 hour at room temperature. Hydrochloric acid (100 mL, 2.0 M) then was added and the organic phase separated and dried with magnesium sulfate. The solvent was removed and the residue chromatographed on silica gel using 5% diethyl ether–petroleum ether to give methyl 3,3-dimethyl-6-oxo-2-[5-(trimethylsilyl)-4-pentynyl]cyclohexanecarboxylate, 9.66 g (60%). IR 2000, 2140, 1755, 1715, 1660, 1615, 1440, 1280, 1250, 1225, 1205, and 845 cm–1; 1H NMR ( CDCl) δ 0.13 (s, 9H), 0.93 (s, 3H), 1.02 (s, 3H), 1.2–2.3 (m, 11H), 3.74 (s, 3H). Anal. Calc. for CHOSi: C, 67.05; H, 9.4. Found: C, 67.1; H, 9.65. | 0 | Theoretical and Fundamental Chemistry |
Chlorprothixene's principal indications are the treatment of psychotic disorders (e.g. schizophrenia) and of acute mania occurring as part of bipolar disorders.
Other uses are pre- and postoperative states with anxiety and insomnia, severe nausea / emesis (in hospitalized patients), the amelioration of anxiety and agitation due to use of selective serotonin reuptake inhibitors for depression and, off-label, the amelioration of alcohol and opioid withdrawal. It may also be used cautiously to treat nonpsychotic irritability, aggression, and insomnia in pediatric patients.
An intrinsic antidepressant effect of chlorprothixene has been discussed, but not proven. Likewise, it is unclear if chlorprothixene has genuine (intrinsic) analgesic effects. However, chlorprothixene can be used as co-medication in severe chronic pain. Also, like most antipsychotics, chlorprothixene has antiemetic effects. | 0 | Theoretical and Fundamental Chemistry |
During the night, a plant employing CAM has its stomata open, allowing to enter and be fixed as organic acids by a PEP reaction similar to the pathway. The resulting organic acids are stored in vacuoles for later use, as the Calvin cycle cannot operate without ATP and NADPH, products of light-dependent reactions that do not take place at night. | 0 | Theoretical and Fundamental Chemistry |
Bone ash can be used alone as an organic fertilizer or it can be treated with sulfuric acid to form a "single superphosphate" fertilizer which is more water soluble:
:Ca(PO) + 2 HSO + 5 HO → 2 CaSO·2HO + Ca(HPO)·HO
Similarly, phosphoric acid can be used to form triple superphosphate, a more concentrated phosphorus fertilizer which excludes the gypsum content found in single superphosphate:
:Ca(PO) + 4 HPO → 3 Ca(HPO) | 0 | Theoretical and Fundamental Chemistry |
Ampicillin overdose can cause behavioral changes, confusion, blackouts, and convulsions, as well as neuromuscular hypersensitivity, electrolyte imbalance, and kidney failure. | 0 | Theoretical and Fundamental Chemistry |
Molecular recognition events mediated through orbital interactions are critical in a number of biological processes such as enzyme catalysis. Stabilizing interactions between proteins and carbohydrates in glycosylated proteins also exemplify the role of stereoelectronic effects in biomolecules. | 0 | Theoretical and Fundamental Chemistry |
After attending University High School, Melbourne (1939–42), Greenwood read Chemistry at the University of Melbourne and graduated with a BSc in 1945 and an MSc in 1948. In 1948, he was awarded the Exhibition of 1851 Scholarship to enable him to read for a PhD at Sidney Sussex College, Cambridge under the supervision of Harry Julius Emeléus. He received the PhD in 1951. | 0 | Theoretical and Fundamental Chemistry |
These groups may contain only two-fold axes, mirror planes, and/or an inversion center. These are the crystallographic point groups 1 and (triclinic crystal system), 2, m, and (monoclinic), and 222, , and mm2 (orthorhombic). (The short form of is mmm.) If the symbol contains three positions, then they denote symmetry elements in the x, y, z direction, respectively. | 0 | Theoretical and Fundamental Chemistry |
Reactive compatibilization is a procedure in which immiscible polymer blends are compatibilized by creating copolymers in the solution or melt state. Copolymers are formed when the proper functional groups in each component of the immiscible blend interact in the compatibilization process. These interactions include hydrogen, ionic or covalent bonding. The functional groups that cause these interactions can be the end groups that are already present in the blend polymers (e.g., carboxylic acids or alcohols on polyesters, or amine groups on nylons). Another approach is to add functional groups to the component chains by grafting. The many possible functional groups allow for many types of commercial polymer blends, including polyamide/polyalkene blend systems.
There are a number of advantages reactive compatibilization has over using the traditional block or graft copolymer as the compatibilizing agent. Unlike the latter approach, reactive compatibilization does not rely on diffusing pre-formed copolymers. Copolymers form at the interfaces of the two immiscible blends and do not need to be dispersed. In the traditional approach the system needs to be well mixed when adding the copolymers. Reactive compatibilization is also much more efficient than traditional compatibilization. This is because in reactive compatibilization, functional groups are either already present, or easily grafted on the blend components. In the traditional compatibilization, copolymers must be synthesized on a case-by-case basis for the components to blend. | 0 | Theoretical and Fundamental Chemistry |
While almost all foodstuffs are derived from the natural products of plants and animals, natural foods are often assumed to be foods that are not processed, or do not contain any food additives, or do not contain particular additives such as hormones, antibiotics, sweeteners, food colors, preservatives, or flavorings that were not originally in the food. In fact, many people (63%) when surveyed showed a preference for products labeled "natural" compared to the unmarked counterparts, based on the common belief (86% of polled consumers) that the term "natural" indicated that the food does not contain any artificial ingredients.
The term is variously misused on labels and in advertisements. The international Food and Agriculture Organizations Codex Alimentarius does not recognize the term natural' but does have a standard for organic foods. | 1 | Applied and Interdisciplinary Chemistry |
Nickel monosilicide can be prepared by depositing a nickel layer on silicon and subsequent annealing. In the case of Ni films with thicknesses above 4 nm, the normal phase transition is given by NiSi at 250 °C followed by NiSi at 350 °C and NiSi at approximately 800 °C. For films with an initial Ni thickness below 4 nm a direct transition from orthorhombic NiSi to epitaxial NiSi, skipping the nickel monosilicide phase, is observed. | 1 | Applied and Interdisciplinary Chemistry |
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