text
stringlengths 105
4.57k
| label
int64 0
1
| label_text
stringclasses 2
values |
|---|---|---|
Pockels was born in Venice, Austrian Empire, in 1862. At the time, Venice was under Austrian rule, and Pockels' father served in the Austrian Army. When he fell sick, the family moved in 1871 to Brunswick, which was part of the nascent German Empire. There, Pockels attended the Municipal High School for Girls. Agnes was interested in chemistry as a child. However, women were not allowed to enter universities to study. Pockels stated that "I had a passionate interest in natural science, especially physics, and would have liked to study.“ (Agnes Pockels, as translated by Giles from Autobiographical Notes in W. Ostwald, 1932.)
As a child, Pockels was interested in science, especially physics. In those days, women in Germany had no access to universities. Pockels studied science at home while caring for her parents. Pockels' younger brother Friedrich Carl Alwin Pockels studied physics at the University of Göttingen, completing his degree there. Friedrich shared textbooks from the university with Agnes Pockels in order to help her study from home. He later shared academic literature with Agnes Pockels to advance her studies. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, a vinyl sulfone is a functional group consisting of a vinyl group bonded to a sulfone group. Specific compounds containing this functional group are divinyl sulfone, phenyl vinyl sulfone, methyl vinyl sulfone, and ethyl vinyl sulfone.
The sulfone makes the vinyl group electrophilic, allowing it to be used as a pharmacophore for binding to the thiol of cysteine residues. This same reactive nature is responsible for their major industrial use in vinyl sulfone dyes. | 1 | Applied and Interdisciplinary Chemistry |
GaN nanotubes and nanowires are proposed for applications in nanoscale electronics, optoelectronics and biochemical-sensing applications. | 0 | Theoretical and Fundamental Chemistry |
Over the almost 12 years it took the two groups to reach their goal, both Woodward and Eschenmoser periodically reported on the stage of the collaborative project in lectures, some of them appearing in print. Woodward discussed the A/B approach in lectures published in 1968, and 1971, culminating in the announcement of the "Total Synthesis of Vitamin B" in New Delhi in February 1972 published in 1973. This publication, and lectures with the same title Woodward delivered in the later part of the year 1972 are confined to the A/B approach of the synthesis and do not discuss the ETH A/D approach.
Eschenmoser had discussed the ETH contributions to the A/B approach in 1968 at the 22nd Robert A. Welch Foundation conference in Houston, as well as in his 1969 RSC Centenary Lecture "Roads to Corrins", published in 1970. He presented the ETH photochemical A/D approach to the B synthesis at the 23rd IUPAC Congress in Boston in 1971. The Zürich group announced the accomplishment of the synthesis of cobyric acid by the photochemical A/D-approach in two lectures delivered by PhD students Maag and Fuhrer at the Swiss Chemical Society Meeting in April 1972, Eschenmoser presented a lecture "Total Synthesis of Vitamin B: the Photochemical Route" for the first time as Wilson Baker Lecture at the University of Bristol, Bristol/UK on May 8, 1972.
As a joint full publication of the syntheses by the Harvard and ETH groups (announced in and expected in) had not appeared by 1977, an article describing the final version of the photochemical A/D approach already accomplished in 1972 was published 1977 in Science. This article is an extended English translation of one that had already appeared 1974 in Naturwissenschaften, based on a lecture given by Eschenmoser on January 21, 1974, at a meeting of the Zürcher Naturforschende Gesellschaft. Four decades later, in 2015, the same author finally published a series of six full papers describing the work of the ETH group on corrin synthesis. Part I of the series contains a chapter entitled "The Final Phase of the Harvard/ETH Collaboration on the Synthesis of Vitamin B", in which the contributions of the ETH group to the collaborative work on the synthesis of vitamin B between 1965 and 1972 are recorded.
The entire ETH work is documented in full experimental detail in publicly accessible Ph.D. theses, almost 1,900 pages, all in German. Contributions of the 14 postdoctoral ETH researchers involved in the cobyric acid syntheses are mostly integrated in these theses. The detailed experimental work at Harvard was documented in reports by the 77 postdoctoral researchers involved, with a total volume of more than 3,000 pages.
Representative reviews of the two approaches to the chemical synthesis of vitamin B have been published in detail by A. H. Jackson and K. M. Smith, T. Goto, R. V. Stevens, K. C. Nicolaou & E. G. Sorensen, summarized by J. Mulzer & D. Riether, and G. W. Craig, besides many other publications where these epochal syntheses are discussed. | 0 | Theoretical and Fundamental Chemistry |
The Imd pathway is a broadly-conserved NF-κB immune signalling pathway of insects and some arthropods that regulates a potent antibacterial defence response. The pathway is named after the discovery of a mutation causing severe immune deficiency (the gene was named "Imd" for "immune deficiency"). The Imd pathway was first discovered in 1995 using Drosophila fruit flies by Bruno Lemaitre and colleagues, who also later discovered that the Drosophila Toll gene regulated defence against Gram-positive bacteria and fungi. Together the Toll and Imd pathways have formed a paradigm of insect immune signalling; as of September 2, 2019, these two landmark discovery papers have been cited collectively over 5000 times since publication on Google Scholar.
The Imd pathway responds to signals produced by Gram-negative bacteria. Peptidoglycan recognition proteins (PGRPs) sense DAP-type peptidoglycan, which activates the Imd signalling cascade. This culminates in the translocation of the NF-κB transcription factor Relish, leading to production of antimicrobial peptides and other effectors. Insects lacking Imd signalling either naturally or by genetic manipulation are extremely susceptible to infection by a wide variety of pathogens and especially bacteria. | 1 | Applied and Interdisciplinary Chemistry |
Pressure-driven flow is a method to displace liquids in a capillary or microfluidic channel with pressure. The pressure is typically generated pneumatically by compressed air or other gases (nitrogen, carbon dioxide, etc) or by electrical and magnetical fields or gravitation. | 1 | Applied and Interdisciplinary Chemistry |
Finished products destined for export were transported by lorry to the Port de la Lave, where they were loaded onto cargo ships. Two methods were used for this:
*A la chenille, packed in bags as general cargo via a conveyor belt.
*A la palanquée, packed in sacks as general cargo by crane over a ramp. | 1 | Applied and Interdisciplinary Chemistry |
In tissue engineering, neo-organ is the final structure of a procedure based on transplantation consisting of endogenous stem/progenitor cells grown ex vivo within predesigned matrix scaffolds. Current organ donation faces the problems of patients waiting to match for an organ and the possible risk of the patient's body rejecting the organ. Neo-organs are being researched as a solution to those problems with organ donation. Suitable methods for creating neo-organs are still under development. One experimental method is using adult stem cells, which use the patients own stem cells for organ donation. Currently this method can be combined with decellularization, which uses a donor organ for structural support but removes the donors cells from the organ. Similarly, the concept of 3-D bioprinting organs has shown experimental success in printing bioink layers that mimic the layer of organ tissues. However, these bioinks do not provide structural support like a donor organ. Current methods of clinically successful neo-organs use a combination of decellularized donor organs, along with adult stem cells of the organ recipient to account for both the structural support of a donor organ and the personalization of the organ for each individual patient to reduce the chance of rejection. | 1 | Applied and Interdisciplinary Chemistry |
Usually binucleating ligands feature bridging ligands, such as phenoxide, pyrazolate, or pyrazine, as well as other donor groups that bind to only one of the two metal ions. Some ligands
binucleating ligands are symmetrical, which facilitates the formation of homobimetallic complexes. Other binucleating ligands, where the binding compartments are dissimilar, facilitate the formation of heterobimetallic complexes. | 0 | Theoretical and Fundamental Chemistry |
Communist party Chairman Mao Zedong disdained the cities and put his faith in the Chinese peasantry for a Great Leap Forward. Mao saw steel production as the key to overnight economic modernization, promising that within 15 years China's steel production would surpass that of Britain. In 1958 he decided that steel production would double within the year, using backyard steel furnaces run by inexperienced peasants. The plan was a fiasco, as the small amounts of steel produced were of very poor quality, and the diversion of resources out of agriculture produced a massive famine in 1959–61 that killed millions.
With economic reforms brought in by Deng Xiaoping, who led China from 1978 to 1992, China began to develop a modern steel industry by building new steel plants and recycling scrap metal from the United States and Europe. As of 2013 China produced 779 million metric tons of steel each year, making it by far the largest steel producing country in the world. This is compared to 165 for the European Union, 110 for Japan, 87 for the United States and 81 for India. China's 2013 steel production was equivalent to an average of 3.14 cubic meters of steel per second. | 1 | Applied and Interdisciplinary Chemistry |
Spath and Mamoli first synthesized anabaseine in 1936. The researchers reacted benzoic anhydride with δ-valerolactam to yield N-benzoylpiperidone. Then, N-benzoylpiperidone is reacted with nicotinic acid ethyl ester to produce α-nicotinoyl-N-benzoyl-2-piperidone. This product then is decarboxylated, undergoes a ring closure, and amide hydrolysis to form anabaseine.
Additional synthetic strategies have since been developed by Bloom, Zoltewicz, Smith, and Villemin. | 1 | Applied and Interdisciplinary Chemistry |
Lift and drag properties of golf balls are customized by the manipulation of dimples along the surface of the ball, allowing for the golf ball to travel further and faster in the air. The data from turbulent-flow phenomena has been used to model different transitions in fluid flow regimes, which are used to thoroughly mix fluids and increase reaction rates within industrial processes. | 1 | Applied and Interdisciplinary Chemistry |
In 2017, a new method to purify processing bodies was published. Hubstenberger et al. used fluorescence-activated particle sorting (a method based on the ideas of fluorescence-activated cell sorting) to purify processing bodies from human epithelial cells. From these purified processing bodies they were able to use mass spectrometry and RNA sequencing to determine which proteins and RNAs are found in processing bodies, respectively. This study identified 125 proteins that are significantly associated with processing bodies. Notably this work provided the most compelling evidence up to this date that P-bodies might not be the sites of degradation in the cell and instead used for storage of translationally repressed mRNA. This observation was further supported by single molecule imaging of mRNA by the Chao group in 2017.
In 2018, Youn et al. took a proximity labeling approach called BioID to identify and predict the processing body proteome. They engineered cells to express several processing body-localized proteins as fusion proteins with the BirA* enzyme. When the cells are incubated with biotin, BirA* will biotinylate proteins that are nearby, thus tagging the proteins within processing bodies with a biotin tag. Streptavidin was then used to isolate the tagged proteins and mass spectrometry to identify them. Using this approach, Youn et al. identified 42 proteins that localize to processing bodies. | 1 | Applied and Interdisciplinary Chemistry |
The strength, , of dislocation is dependent on the shear modulus, G, the magnitude of the Burgers vector, b, and the dislocation density, :
where is the intrinsic strength of the material with low dislocation density and is a correction factor specific to the material.
As shown in Figure 1 and the equation above, work hardening has a half root dependency on the number of dislocations. The material exhibits high strength if there are either high levels of dislocations (greater than 10 dislocations per m) or no dislocations. A moderate number of dislocations (between 10 and 10 dislocations per m) typically results in low strength. | 1 | Applied and Interdisciplinary Chemistry |
Thermal composites is a term given to combinations of phase change materials (PCMs) and other (usually solid) structures. A simple example is a copper mesh immersed in paraffin wax. The copper mesh within paraffin wax can be considered a composite material, dubbed a thermal composite. Such hybrid materials are created to achieve specific overall or bulk properties (an example being the encapsulation of paraffin into distinct silicon dioxide nanospheres for increased surface area-to-volume ratio and, thus, higher heat transfer speeds ).
Thermal conductivity is a common property targeted for maximization by creating thermal composites. In this case, the basic idea is to increase thermal conductivity by adding a highly conducting solid (such as the copper mesh or graphite) into the relatively low-conducting PCM, thus increasing overall or bulk (thermal) conductivity. If the PCM is required to flow, the solid must be porous, such as a mesh.
Solid composites such as fiberglass or kevlar prepreg for the aerospace industry usually refer to a fiber (the kevlar or the glass) and a matrix (the glue, which solidifies to hold fibers and provide compressive strength). A thermal composite is not so clearly defined but could similarly refer to a matrix (solid) and the PCM, which is of course usually liquid and/or solid depending on conditions. They are also meant to discover minor elements in the earth. | 0 | Theoretical and Fundamental Chemistry |
The plasmon resonant frequency is highly sensitive to the refractive index of the environment; a change in refractive index results in a shift in the resonant frequency. As the resonant frequency is easy to measure, this allows LSP nanoparticles to be used for nanoscale sensing applications. Also, nanoparticles exhibiting strong LSP properties, such as gold nanorods, could enhance the signal in surface plasmon resonance sensing. Nanostructures exhibiting LSP resonances are used to enhance signals in modern analytical techniques based on spectroscopy. Other applications that rely on efficient light to heat generation in the nanoscale are heat-assisted magnetic recording (HAMR), photothermal cancer therapy, and thermophotovoltaics. So far, high efficiency applications using plasmonics have not been realized due to the high ohmic losses inside metals especially in the optical spectral range (visible and NIR)., Additionally surface plasmons have been used to create super lenses, invisibility cloaks, and to improve quantum computing. Another interesting area of research in plasmonics is the ability to turn plasmons "on" and "off" via modification of another molecule. The ability to turn plasmons on and off has important consequences for increasing sensitivity in detection methods. Recently, a supramolecular chromophore was coupled with a metal nanostructure. This interaction changed the localized surface plasmon resonance properties of the silver nanostructure by increasing the absorption intensity. | 0 | Theoretical and Fundamental Chemistry |
* [http://www.inderscience.com/jhome.php?jcode=ijhst International Journal of Hydrology Science and Technology]
* Hydrological Processes, (electronic) 0885-6087 (paper), John Wiley & Sons
* Hydrology Research, , IWA Publishing (formerly Nordic Hydrology)
* Journal of Hydroinformatics, , IWA Publishing
* Journal of Hydrologic Engineering, , ASCE Publication
* Journal of Hydrology
* Water Research
* Water Resources Research
* Hydrological Sciences Journal - Journal of the International Association of Hydrological Sciences (IAHS) (Print), (Online)
* Hydrology and Earth System Sciences
* Journal of Hydrometeorology | 1 | Applied and Interdisciplinary Chemistry |
Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum.
Spectroscopy, primarily in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of astronomy, chemistry, materials science, and physics, allowing the composition, physical structure and electronic structure of matter to be investigated at the atomic, molecular and macro scale, and over astronomical distances.
Historically, spectroscopy originated as the study of the wavelength dependence of the absorption by gas phase matter of visible light dispersed by a prism. Current applications of spectroscopy include biomedical spectroscopy in the areas of tissue analysis and medical imaging. Matter waves and acoustic waves can also be considered forms of radiative energy, and recently gravitational waves have been associated with a spectral signature in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO). | 0 | Theoretical and Fundamental Chemistry |
Even if it is not a common substrate for metabolism, benzene can be oxidized by both bacteria and eukaryotes. In bacteria, dioxygenase enzyme can add an oxygen to the ring, and the unstable product is immediately reduced (by NADH) to a cyclic diol with two double bonds, breaking the aromaticity. Next, the diol is newly reduced by NADH to catechol. The catechol is then metabolized to acetyl CoA and succinyl CoA, used by organisms mainly in the citric acid cycle for energy production.
The pathway for the metabolism of benzene is complex and begins in the liver. Several enzymes are involved. These include cytochrome P450 2E1 (CYP2E1), quinine oxidoreductase (NQ01 or DT-diaphorase or NAD(P)H dehydrogenase (quinone 1)), GSH, and myeloperoxidase (MPO). CYP2E1 is involved at multiple steps: converting benzene to oxepin (benzene oxide), phenol to hydroquinone, and hydroquinone to both benzenetriol and catechol. Hydroquinone, benzenetriol and catechol are converted to polyphenols. In the bone marrow, MPO converts these polyphenols to benzoquinones. These intermediates and metabolites induce genotoxicity by multiple mechanisms including inhibition of topoisomerase II (which maintains chromosome structure), disruption of microtubules (which maintains cellular structure and organization), generation of oxygen free radicals (unstable species) that may lead to point mutations, increasing oxidative stress, inducing DNA strand breaks, and altering DNA methylation (which can affect gene expression). NQ01 and GSH shift metabolism away from toxicity. NQ01 metabolizes benzoquinone toward polyphenols (counteracting the effect of MPO). GSH is involved with the formation of phenylmercapturic acid.
Genetic polymorphisms in these enzymes may induce loss of function or gain of function. For example, mutations in CYP2E1 increase activity and result in increased generation of toxic metabolites. NQ01 mutations result in loss of function and may result in decreased detoxification. Myeloperoxidase mutations result in loss of function and may result in decreased generation of toxic metabolites. GSH mutations or deletions result in loss of function and result in decreased detoxification. These genes may be targets for genetic screening for susceptibility to benzene toxicity. | 1 | Applied and Interdisciplinary Chemistry |
The concentration of malonyl-CoA depends on the balance between acetyl-CoA carboxylase (ACC) and malonyl-CoA decarboxylase (MCD). AMP-activated protein kinase (AMPK) is reported to phosphorylate and inactivate liver ACC. This in turn decreases malonyl-CoA concentrations which stimulates fatty acid oxidation and ketogenesis by glucagon in the liver. AMPK phosphorylates and inactivates ACC in the liver and other tissues. | 1 | Applied and Interdisciplinary Chemistry |
The direct approach measures the exposures to pollutants by monitoring the pollutant concentrations reaching the respondents. The pollutant concentrations are directly monitored on or within the person through point of contact, biological monitoring, or biomarkers. In a workplace setting, methods of workplace exposure monitoring are used.
The point of contact approach indicates the total concentration reaching the host, while biological monitoring and the use of biomarkers infer the dosage of the pollutant through the determination of the body burden. The respondents often record their daily activities and locations during the measurement of the pollutants to identify the potential sources, microenvironments, or human activities contributing the pollutant exposure. An advantage of the direct approach is that the exposures through multiple media (air, soil, water, food, etc.) are accounted for through one study technique. The disadvantages include the invasive nature of the data collection and associated costs. Point of contact is continuous measure of the contaminant reaching the target through all routes.
Biological monitoring is another approach to measuring exposure measures the amount of a pollutant within body tissues or fluids (such as blood or urine). Biological monitoring measures the body burden of a pollutant but not the source from whence it came. The substance measured may be either the contaminant itself or a biomarker which is specific to and indicative of an exposure to the contaminant. Biomarkers of exposure assessment is a measure of the contaminant or other proportionally related variable in the body.
Air sampling measures the contaminant in the air as concentration units of ppmv (parts per million by volume), mg/m (milligrams per cubic meter) or other mass per unit volume of air. Samplers can be worn by workers or researchers to estimate concentrations found in the breathing zone (personal) or samples collected in general areas can be used to estimate human exposure by integrating time and activity patterns. Validated and semi-validated air sampling methods are published by NIOSH, OSHA, ISO and other bodies.
Surface or dermal sampling measures of the contaminant on touchable surfaces or on skin. Concentrations are typically reported in mass per unit surface area such as mg/100 cm.
In general, direct methods tend to be more accurate but more costly in terms of resources and demands placed on the subject being measured and may not always be feasible, especially for a population exposure study.
Examples of direct methods include air sampling though a personal portable pump, split food samples, hand rinses, breath samples or blood samples. | 1 | Applied and Interdisciplinary Chemistry |
A reaction calorimeter is a calorimeter that measures the amount of energy released (exothermic) or absorbed (endothermic) by a chemical reaction. These measurements provide a more accurate picture of such reactions. | 1 | Applied and Interdisciplinary Chemistry |
Nanogeoscience deals with structures, properties and behaviors of nanoparticles in soils, aquatic systems and atmospheres. One of the key features of nanoparticles is the size-dependence of the nanoparticle stability and reactivity. This arises from the large specific surface area and differences in surface atomic structure of nanoparticles at small particle sizes. In general, the free energy of nanoparticles is inversely proportional to their particle size. For materials that can adopt two or more structures, size-dependent free energy may result in phase stability crossover at certain sizes. Free energy reduction drives crystal growth (atom-by-atom or by oriented attachment ), which may again drive the phase transformation due to the change of the relative phase stability at increasing sizes. These processes impact the surface reactivity and mobility of nanoparticles in natural systems.
Well-identified size-dependent phenomena of nanoparticles include:
* Phase stability reversal of bulk (macroscopic) particles at small sizes. Usually, a less stable bulk-phase at low temperature (and/or low pressure) becomes more stable than the bulk-stable phase as the particle size decreases below a certain critical size. For instance, bulk anatase (TiO) is metastable with respect to bulk rutile (TiO). However, in air, anatase becomes more stable than rutile at particle sizes below 14 nm. Similarly, below 1293 K, wurtzite (ZnS) is less stable than sphalerite (ZnS). In vacuum, wurtzite becomes more stable than sphalerite when the particle size is less than 7 nm at 300 K. At very small particle sizes, the addition of water to the surface of ZnS nanoparticles can induce a change in nanoparticle structure and surface-surface interactions can drive a reversible structural transformation upon aggregation/disaggregation. Other examples of size-dependent phase stability include systems of AlO, ZrO, C, CdS, BaTiO, FeO, CrO, MnO, NbO, YO, and Au-Sb.
* Phase transformation kinetics is size-dependent and transformations usually occur at low temperatures (less than several hundred degrees). Under such conditions, rates of surface nucleation and bulk nucleation are low due to their high activation energies. Thus, phase transformation occurs predominantly via interface nucleation that depends on contact between nanoparticles. As a consequence, the transformation rate is particle number (size)-dependent and it proceeds faster in densely packed (or highly aggregated) than in loosely packed nanoparticles. Complex concurrent phase transformation and particle coarsening often occur in nanoparticles.
* Size-dependent adsorption on nanoparticles and oxidation of nanominerals.
These size-dependent properties highlight the importance of the particle size in nanoparticle stability and reactivity. | 0 | Theoretical and Fundamental Chemistry |
Radiocarbon dating has been used since 1946 to determine the age of organic material as old as 50,000 years. As the organism dies, the exchange of C with the environment ceases and the incorporated C decays. Given the steady decay of radioisotopes (the half-life of C is about 5,730 years), the relative amount of C left in the dead organism can be used to calculate how long ago it died. Bomb pulse dating should be considered a special form of carbon dating. As discussed above and in the Radiolab episode, Elements (section Carbon), in bomb pulse dating the slow absorption of atmospheric C by the biosphere, can be considered as a chronometer. Starting from the pulse around the years 1963 (see figure), atmospheric radiocarbon relative abundance decreased by about 4% a year. So in bomb pulse dating it is the relative amount of C in the atmosphere that is decreasing and not the amount of C in a dead organisms, as is the case in classical radiocarbon dating. This decrease in atmospheric C can be measured in cells and tissues and has permitted scientists to determine the age of individual cells and of deceased people. These applications are very similar to the experiments conducted with pulse-chase analysis in which cellular processes are examined over time by exposing the cells to a labeled compound (pulse) and then to the same compound in an unlabeled form (chase). Radioactivity is a commonly used label in these experiments. An important difference between pulse-chase analysis and bomb-pulse dating is the absence of the chase in the latter.
Around the year 2030 the bomb pulse will die out. Every organism born after this will not bear detectable bomb pulse traces and their cells cannot be dated in this way. Radioactive pulses cannot ethically be administered to people just to study the turnover of their cells so the bomb pulse results may be considered as a useful side effect of nuclear testing. | 0 | Theoretical and Fundamental Chemistry |
Another form of translational regulation in eukaryotes comes from unique elements on the 5′ UTR called upstream open reading frames (uORF). These elements are fairly common, occurring in 35–49% of all human genes. A uORF is a coding sequence located in the 5′ UTR located upstream of the coding sequences initiation site. These uORFs contain their own initiation codon, known as an upstream AUG (uAUG). This codon can be scanned for by ribosomes and then translated to create a product, which can regulate the translation of the main protein coding sequence or other uORFs that may exist on the same transcript.
The translation of the protein within the main ORF after a uORF sequence has been translated is known as reinitiation. The process of reinitiation is known to reduce the translation of the ORF protein. Control of protein regulation is determined by the distance between the uORF and the first codon in the main ORF. A uORF has been found to increase reinitiation with the longer distance between its uAUG and the start codon of the main ORF, which indicates that the ribosome needs to reacquire translation factors before it can carry out translation of the main protein. For example, ATF4 regulation is performed by two uORFs further upstream, named uORF1 and uORF2, which contain three amino acids and fifty-nine amino acids, respectively. The location of uORF2 overlaps with the ATF4 ORF. During normal conditions, the uORF1 is translated, and then translation of uORF2 occurs only after eIF2-TC has been reacquired. Translation of the uORF2 requires that the ribosomes pass by the ATF4 ORF, whose start codon is located within uORF2. This leads to its repression. However, during stress conditions, the 40S ribosome will bypass uORF2 because of a decrease in concentration of eIF2-TC, which means the ribosome does not acquire one in time to translate uORF2. Instead, ATF4 is translated. | 1 | Applied and Interdisciplinary Chemistry |
In practice, simple idealized thermodynamic cycles are usually made out of four thermodynamic processes. Any thermodynamic processes may be used. However, when idealized cycles are modeled, often processes where one state variable is kept constant, such as:
* adiabatic (constant heat)
* isothermal (constant temperature)
* isobaric (constant pressure)
* isochoric (constant volume)
* isentropic (constant entropy)
* isenthalpic (constant enthalpy)
Some example thermodynamic cycles and their constituent processes are as follows: | 0 | Theoretical and Fundamental Chemistry |
Fluorescent nanoparticles are highly sought after. They have broad applications, but their use in macroscopic arrays allows them efficient in applications of plasmonics, photonics, and quantum communications. While there are many methods in assembling nanoparticles array, especially gold nanoparticles, they tend to be weakly bonded to their substrate so they can't be used for wet chemistry processing steps or lithography. Nanodiamonds allow for greater variability in access that can subsequently be used to couple plasmonic waveguides to realize quantum plasmonic circuitry.
Nanodiamonds can be synthesized by employing nanoscale carbonaceous seeds created in a single step by using a mask-free electron beam-induced position technique to add amine groups. This assembles nanodiamonds into an array. The presence of dangling bonds at the nanodiamond surface allows them to be functionalized with a variety of ligands. The surfaces of these nanodiamonds are terminated with carboxylic acid groups, enabling their attachment to amine-terminated surfaces through carbodiimide coupling chemistry. This process affords a high yield that relies on covalent bonding between the amine and carboxyl functional groups on amorphous carbon and nanodiamond surfaces in the presence of EDC. Thus unlike gold nanoparticles, they can withstand processing and treatment, for many device applications. | 0 | Theoretical and Fundamental Chemistry |
The tangential stress and the normal stress on the scraper due to pressure and viscous forces are
The same scraper stress if resolved according to Cartesian coordinates (parallel and perpendicular to the lower plate i.e. ) are
As noted earlier, all the stresses become infinite at , because the velocity gradient is infinite there. In real life, there will be a huge pressure at the point, which depends on the geometry of the contact. The stresses are shown in the figure as given in the Taylor's original paper.
The stress in the direction parallel to the lower wall decreases as increases, and reaches its minimum value at . Taylor says: "The most interesting and perhaps unexpected feature of the calculations is that does not change sign in the range . In the range the contribution to due to normal stress is of opposite sign to that due to tangential stress, but the latter is the greater. The palette knives used by artists for removing paint from their palettes are very flexible scrapers. They can therefore only be used at such an angle that is small and as will be seen in the figure this occurs only when is nearly . In fact artists instinctively hold their palette knives in this position." Further he adds "A plasterer on the other hand holds a smoothing tool so that is small. In that way he can get the large values of which are needed in forcing plaster from protuberances to hollows." | 1 | Applied and Interdisciplinary Chemistry |
Zinc is one of the most common metal ions in biological systems. Small molecule sensors for it include:
*ZX1, a compound comprizing a dipicolylamine (DPA) Zinc binding subunit that has greater affinity for Zinc than other species found in solution such as Ca and Mg.
*Zinpyr-1 (ZP1), a compound containing a dichlorofluorescein fluorescent compound bound to two 2-picolamine (DPA) species that bind Zn(II). ZP1 is part of a family of zinc sensors known as the Zinpyr series, the members of which are variants on ZP1 to enable specific affinities and fluorescence profiles.
*ZnAF-1 sensors that comprise an aryl donor and a xanthenone acceptor and have a large change in fluorescence upon binding Zn(II). They have been used to study uptake of Zn(II) in CA3 pyramidal neurons. | 0 | Theoretical and Fundamental Chemistry |
Many low-valent and electron-rich transition metals effect stoichiometric dehalogenation. The reaction achieves practical interest in the context of organic synthesis, e.g. Cu-promoted Ullmann coupling.
The reaction is mainly conducted as stoichiometrically. Some metalloenzymes Vitamin B12 and coenzyme F430 are capable of dehalogenations catalytically. Of great interest are hydrodehalogenations, especially for chlorinated precursors: | 0 | Theoretical and Fundamental Chemistry |
No adverse effects other than carotenemia have been reported for consumption of β-carotene rich foods. Supplementation with β-carotene does not cause hypervitaminosis A. Two large clinical trials (ATBC and CARET) were conducted in tobacco smokers to see if years of β-carotene supplementation at 20 or 30 mg/day in oil-filled capsules would reduce the risk of lung cancer. These trials were implemented because observational studies had reported a lower incidence of lung cancer in tobacco smokers who had diets higher in β-carotene. Unexpectedly, this high-dose β-carotene supplementation resulted in a higher incidence of lung cancer and of total mortality. Taking this and other evidence into consideration, the U.S. Institute of Medicine decided not to set a Tolerable Upper Intake Level (UL) for β-carotene. The European Food Safety Authority, acting for the European Union, also decided not to set a UL for β-carotene. | 1 | Applied and Interdisciplinary Chemistry |
Lord Rayleigh studied the stability of the problem with inviscid assumption i.e., perturbing Euler equations. The criterion states that in the absence of viscosity the necessary and sufficient condition for distribution of azimuthal velocity to be stable is
everywhere in the interval; and, further, that the distribution is unstable if should decrease anywhere in the interval. Since represents angular momentum per unit mass, of a fluid element about the axis of rotation, an alternative way of stating the criterion is: a stratification of angular momentum about an axis is stable if and if only it increases monotonically outward.
Applying this criterion to the Taylor-Couette flow indicates that the flow is stable if , i.e., for stability, the outer cylinder must rotate (in the same sense) with an angular speed greater than -times that of the inner cylinder. The Rayleighs criterion is violated () throughout the whole fluid when . On the other hand, when the cylinders rotate in opposite directions, i.e., when , Rayleighs criterion is violated only in the inner region, i.e., for where . | 1 | Applied and Interdisciplinary Chemistry |
Submarine groundwater discharge (SGD) is a hydrological process which commonly occurs in coastal areas. It is described as submarine inflow of fresh-, and brackish groundwater from land into the sea. Submarine Groundwater Discharge is controlled by several forcing mechanisms, which cause a hydraulic gradient between land and sea. Considering the different regional settings the discharge occurs either as (1) a focused flow along fractures in karst and rocky areas, (2) a dispersed flow in soft sediments, or (3) a recirculation of seawater within marine sediments. Submarine Groundwater Discharge plays an important role in coastal biogeochemical processes and hydrological cycles such as the formation of offshore plankton blooms, hydrological cycles, and the release of nutrients, trace elements and gases. It affects coastal ecosystems and has been used as a freshwater resource by some local communities for millennia. | 0 | Theoretical and Fundamental Chemistry |
Alsevers solution is a saline liquid used to prevent coagulation of blood. It is composed of 2.05% dextrose, 0.8% sodium citrate, 0.055% citric acid, and 0.42% sodium chloride. For usage, an equal volume of blood is gently, but thoroughly, mixed with the solution. This solution is used to study in vitro' anti-inflammatory activity of crude drugs by the human red blood cell stabilization method. It is also used to preserve blood cells from other sources.
The test was invented in 1941 by the American Hematologist, John Bellows Alsever (1908–1978). | 1 | Applied and Interdisciplinary Chemistry |
Quartz crystal microbalance (QCM) is an acoustic sensor built around a disk shaped quartz crystal. It makes use of the converse piezoelectric effect. QCM, and extended versions such as QCM-D, has been widely used for protein adsorption studies, especially, real time monitoring of label-free protein adsorption. In addition to the adsorption studies, QCM-D also provides information regarding elastic moduli, viscosity, and conformational changes | 1 | Applied and Interdisciplinary Chemistry |
Campo de Cartagena is a natural region (comarca) located in the Region of Murcia, in Spain. For administrative purposes, it is also known as Comarca del Campo de Cartagena or Comarca de Cartagena. It is located in the southeast of the Iberian Peninsula, forming a plain which extends from the Sierra de Carrascoy to the Mediterranean. The capital city is Cartagena, the most important Naval Base of the Spanish Navy in the Mediterranean Sea.
The comarca contains 393,598 inhabitants (2019) in an area of 1,481.8 km, making up the metropolitan area of Cartagena, a center for tourism, culture, industry and nature, with more than 18,500 protected hectares, among places like the Calblanque, Monte de las Cenizas y Peña del Águila Natural Park; the Sierra de la Muela, Cabo Tiñoso and Roldán Natural Park; Salinas y Arenales de San Pedro del Pinatar or Islas e Islotes del Litoral Mediterráneo (Islands and Islets of the Mediterranean Shore), among others. Beside those places, it must be added much of the marine environment, highlighting the Mar Menor, the Marine Reserve of Cabo de Palos e Islas Hormigas, and the Cape Tiñoso surroundings. | 1 | Applied and Interdisciplinary Chemistry |
The principle of Solvent Impregnated Resins was first shown in 1971 by Abraham Warshawsky. This first venture was aimed at the extraction of metals. Ever since then, SIRs have been mainly used for metal extraction, be it heavy metals or specifically radioactive metals. Much research on SIRs has been done by J.L Cortina and e.g. N. Kabay, K. Jerabek or J. Serarols. However, lately investigations also go towards using SIRs for the separation of natural compounds, and even for separation of biotechnological products. | 0 | Theoretical and Fundamental Chemistry |
Receptor uncoupling/phosphorylation is the most rapid form of desensitization that happens within a cell, as its effects are seen within seconds to minutes of agonist application. The ß adrenergic receptor was the first to have its desensitization studied and characterized. The mechanism of desensitization involves the action of a specific GRK, denoted ßARK, and also ß-arrestins. The ß-arrestins show high affinity for receptors that are both phosphorylated and activated, but are still able to bind non-phosphorylated receptors with a lower affinity. Additionally, ß-arrestins are better at inactivating ßARK-phosphorylated receptors rather than protein kinase A-phosphorylated receptors, which suggests that the arrestins preferentially mediate homologous desensitization.
The mechanism of homologous desensitization for the β receptor is as follows:
# Agonist binds and activates the receptor, which changes to an active conformational state.
# Beta adrenergic receptor kinase (βARK), a cytoplasmic kinase is activated and phosphorylates the C-terminus of the β receptor.
# This phosphorylation increases the affinity of β-arrestin for the receptor, resulting in uncoupling of the α subunit of the heterotrimeric G-protein from the receptor, producing desensitization. | 1 | Applied and Interdisciplinary Chemistry |
The Journal of Physical Chemistry C publishes scientific articles reporting research on several subdisciplines of physical chemistry:
*Nanoparticles and nanostructures
*surfaces, interfaces, and catalysis
*Electron transport, optical and electronic devices
*Energy conversion and storage
It was created in 2007 when The Journal of Physical Chemistry B was split in two, largely due to the recent growth in the area of nanotechnology. The journal is published weekly, with the first issue on January 11, 2007. Like The Journal of Physical Chemistry A and B, it is published by the American Chemical Society.
The journal is indexed in: Chemical Abstracts Service (CAS) and British Library. According to the Journal Citation Reports, the journal had a 2022 impact factor of 3.7. | 0 | Theoretical and Fundamental Chemistry |
The porous medium equation name originates from its use in describing the flow of an ideal gas in a homogeneous porous medium. We require three equations to completely specify the mediums density , flow velocity field , and pressure : the continuity equation for conservation of mass; Darcys law for flow in a porous medium; and the ideal gas equation of state. These equations are summarized below:<math display="block">\begin{aligned}
\varepsilon {\partial \rho\over{\partial t}} &= -\nabla \cdot (\rho {\bf v}) & (\text{Conservation of mass}) \\
{\bf v} &= -{k\over{\mu}}\nabla p & (\text{Darcy's law}) \\
p &= p_{0}\rho^{\gamma} & (\text{Equation of state})
\end{aligned} is the porosity, is the permeability of the medium, is the dynamic viscosity, and is the polytropic exponent (equal to the heat capacity ratio for isentropic processes). Assuming constant porosity, permeability, and dynamic viscosity, the partial differential equation for the density is:where and . | 1 | Applied and Interdisciplinary Chemistry |
* Several in-vitro experiments suggest that ISWI remodelers organize nucleosome into proper bundle form and create equal spacing between nucleosomes, whereas SWI/SNF remodelers disorder nucleosomes.
* The ISWI-family remodelers have been shown to play central roles in chromatin assembly after DNA replication and maintenance of higher-order chromatin structures.
* INO80 and SWI/SNF-family remodelers participate in DNA double-strand break (DSB) repair and nucleotide-excision repair (NER) and thereby plays crucial role in TP53 mediated DNA-damage response.
* NuRD/Mi-2/CHD remodeling complexes primarily mediate transcriptional repression in the nucleus and are required for the maintenance of pluripotency of embryonic stem cells. | 1 | Applied and Interdisciplinary Chemistry |
Conformational equilibrium is the tendency to favor the conformation where cyclohexane is the most stable. This equilibrium depends on the interactions between the molecules in the compound and the solvent. Polarity and nonpolarity are the main factors in determining how well a solvent interacts with a compound. Cyclohexane is considered nonpolar, meaning that there is no electronegative difference between its bonds and its overall structure is symmetrical. Due to this, when cyclohexane is immersed in a polar solvent, it will have less solvent distribution, which signifies a poor interaction between the solvent and solute. This produces a limited catalytic effect. Moreover, when cyclohexane comes into contact with a nonpolar solvent, the solvent distribution is much greater, showing a strong interaction between the solvent and solute. This strong interaction yields a heighten catalytic effect. | 0 | Theoretical and Fundamental Chemistry |
The first antiandrogen was discovered in the 1960s. Antiandrogens antagonise the androgen receptor (AR) and thereby block the biological effects of testosterone and dihydrotestosterone (DHT). Antiandrogens are important for men with hormonally responsive diseases like prostate cancer, benign prostatic hyperplasia (BHP), acne, seborrhea, hirsutism and androgen alopecia. Antiandrogens are mainly used for the treatment of prostate diseases. Research from 2010 suggests that ARs could be linked to the disease progression of triple-negative breast cancer and salivary duct carcinoma and that antiandrogens can potentially be used to treat it.
antiandrogens are small molecules and can be either steroidal or nonsteroidal depending on ligand chemistry. Steroidal antiandrogens share a similar steroid structure, while nonsteroidal antiandrogens (NSAAs) may have structurally distinctive pharmacophores. Only a limited number of compounds are available for clinical use despite the fact that a very large variety of antiandrogen compounds have been discovered and researched. | 1 | Applied and Interdisciplinary Chemistry |
The protein binding principles in EBA are the same as in classical column chromatography and the common ion-exchange, hydrophobic interaction and affinity chromatography ligands can be used. After the adsorption step is complete, the fluidized bed is washed to flush out any remaining particulates. Elution of the adsorbed proteins was commonly performed with the eluent flow in the reverse direction; that is, as a conventional packed bed, in order to recover the adsorbed solutes in a smaller volume of eluent. However, a new generation of EBA columns has been developed, which maintain the bed in the expanded state during this phase, producing high-purity, high yields of e.g. MAbs [monoclonal antibodies] in even smaller volumes of eluent. Process duration at manufacturing scale has also been cut considerably (under 7 hours in some cases).
EBA may be considered to combine both the "Removal of Insolubles" and the "Isolation" steps of the 4-step downstream processing heuristic. The major limitations associated with EBA technology is biomass interactions and aggregations onto adsorbent during processing.
Where classical column chromatography uses a solid phase made by a packed bed, EBA uses particles in a fluidized state, ideally expanded by a factor of 2. Expanded bed adsorption is, however, different from fluidised bed chromatography in essentially two ways: one, the EBA resin contains particles of varying size and density which results in a gradient of particle size when expanded; and two, when the bed is in its expanded state, local loops are formed. Particles such as whole cells or cell debris, which would clog a packed bed column, readily pass through a fluidized bed. EBA can therefore be used on crude culture broths or slurries of broken cells, thereby bypassing initial clearing steps such as centrifugation and filtration, which is mandatory when packed beds are used. In older EBA column designs, the feed flow rate is kept low enough that the solid packing remains stratified and does not fluidize completely. Hence EBA can be modelled as frontal adsorption in a packed bed, rather than as a well-mixed, continuous-flow adsorber. | 1 | Applied and Interdisciplinary Chemistry |
Molecular breeding is the application of molecular biology tools, often in plant breeding and animal breeding. In the broad sense, molecular breeding can be defined as the use of genetic manipulation performed at the level of DNA to improve traits of interest in plants and animals, and it may also include genetic engineering or gene manipulation, molecular marker-assisted selection, and genomic selection. More often, however, molecular breeding implies molecular marker-assisted breeding (MAB) and is defined as the application of molecular biotechnologies, specifically molecular markers, in combination with linkage maps and genomics, to alter and improve plant or animal traits on the basis of genotypic assays.
The areas of molecular breeding include:
* QTL mapping or gene discovery
* Marker assisted selection and genomic selection
* Genetic engineering
* Genetic transformation | 1 | Applied and Interdisciplinary Chemistry |
Silver bromate can be used as an oxidant for the transformation of tetrahydropyranyl ethers to carbonyl compounds. | 0 | Theoretical and Fundamental Chemistry |
Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO. Sodium bisulfite in fact is not a real compound, but a mixture of salts that dissolve in water to give solutions composed of sodium and bisulfite ions. It appears in form of white or yellowish-white crystals with an odor of sulfur dioxide. Regardless of its ill-defined nature, sodium bisulfite is used in many different industries such as a food additive with E number E222 in the food industry, a reducing agent in the cosmetic industry, and a decomposer of residual hypochlorite used in the bleaching industry. | 0 | Theoretical and Fundamental Chemistry |
Although the passage of food into the gastrointestinal tract results in increased blood flow to the stomach and intestines, this is achieved by diversion of blood primarily from skeletal muscle tissue and by increasing the volume of blood pumped forward by the heart each minute. The flow of oxygen and blood to the brain is extremely tightly regulated by the circulatory system and does not drop after a meal. | 1 | Applied and Interdisciplinary Chemistry |
The Patterson function is used to solve the phase problem in X-ray crystallography. It was introduced in 1935 by Arthur Lindo Patterson while he was a visiting researcher in the laboratory of Bertram Eugene Warren at MIT.
The Patterson function is defined as
It is essentially the Fourier transform of the intensities rather than the structure factors. The Patterson function is also equivalent to the electron density convolved with its inverse:
Furthermore, a Patterson map of N points will have peaks, excluding the central (origin) peak and any overlap.
The peaks' positions in the Patterson function are the interatomic distance vectors and the peak heights are proportional to the product of the number of electrons in the atoms concerned.
Because for each vector between atoms i and j there is an oppositely oriented vector of the same length (between atoms j and i), the Patterson function always has centrosymmetry. | 0 | Theoretical and Fundamental Chemistry |
The convergence of observed BD angles can be viewed as arising from the need to maximize overlap between the highest occupied molecular orbital (HOMO) of the nucleophile, and the lowest unoccupied molecular orbital (LUMO) of the unsaturated, trigonal center of the electrophile. (See, in comparison, the related inorganic chemistry concept of the angular overlap model.)
In the case of addition to a carbonyl, the HOMO is often a p-type orbital (e.g., on an amine nitrogen or halide anion), and the LUMO is generally understood to be the antibonding π* molecular orbital perpendicular to the plane containing the ketone C=O bond and its substituents (see figure at right above). The BD angle observed for nucleophilic attack is believed to approach the angle that would produce optimal overlap between HOMO and LUMO (based on the principle of the lowering of resulting new molecular orbital energies after such mixing of orbitals of similar energy and symmetry from the participating reactants). At the same time, the nucleophile avoids overlap with other orbitals of the electrophilic group that are unfavorable for bond formation (not apparent in image at right, above, because of the simplicity of the R=R'=H in formaldehyde). | 0 | Theoretical and Fundamental Chemistry |
When two solid bodies come in contact, such as A and B in Figure 1, heat flows from the hotter body to the colder body. From experience, the temperature profile along the two bodies varies, approximately, as shown in the figure. A temperature drop is observed at the interface between the two surfaces in contact. This phenomenon is said to be a result of a thermal contact resistance existing between the contacting surfaces. Thermal contact resistance is defined as the ratio between this temperature drop and the average heat flow across the interface.
According to Fourier's law, the heat flow between the bodies is found by the relation:
where is the heat flow, is the thermal conductivity, is the cross sectional area and is the temperature gradient in the direction of flow.
From considerations of energy conservation, the heat flow between the two bodies in contact, bodies A and B, is found as:
One may observe that the heat flow is directly related to the thermal conductivities of the bodies in contact, and , the contact area , and the thermal contact resistance, , which, as previously noted, is the inverse of the thermal conductance coefficient, . | 0 | Theoretical and Fundamental Chemistry |
Some turbofans have an intermediate pressure (IP) compressor located between the fan and the high pressure (HP) compressor to increase overall pressure ratio. US civil engines tend to mount the IP compressor on the LP shaft, directly behind the fan, whereas Rolls-Royce normally mount the IP compressor on a separate (i.e. IP) shaft, which is driven by an IP turbine. Either way, matching problems can arise.
The IP compressor outlet corrected flow must match the entry corrected flow of the HP compressor, which is decreasing as the engine is throttled back. At a certain IP compressor working line slope, the IP compressor outlet corrected flow remains constant. However, by adopting a shallower working line, the extra IP compressor pressure ratio at a given IP compressor entry corrected flow enables the IP compressor outlet corrected flow to decrease and match up with the falling HP compressor entry corrected flow. Unfortunately this can lead to a poor IP compressor surge margin at part flow.
Surge margin can be improved by adding variable stators to the IP compressor and/or adding a blow-off valve between the IP and HP compressors. The former makes the IP compressor surge line shallower, swinging it away from the shallow working line, thus improving IP compressor surge margin.
At a given IP compressor pressure ratio, opening the blow-off valve forces the IP compressor entry corrected flow to increase, to a point where the IP compressor surge margin tends to be better. Effectively, opening the blow-off valve lowers the IP compressor working line. Any flow surplus to that demanded by the HP compressor passes through the blow-off valve into the bypass duct. The blow-off valve is normally only opened at throttled conditions, since it wastes energy. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, volatility is a material quality which describes how readily a substance vaporizes. At a given temperature and pressure, a substance with high volatility is more likely to exist as a vapour, while a substance with low volatility is more likely to be a liquid or solid. Volatility can also describe the tendency of a vapor to condense into a liquid or solid; less volatile substances will more readily condense from a vapor than highly volatile ones. Differences in volatility can be observed by comparing how fast substances within a group evaporate (or sublimate in the case of solids) when exposed to the atmosphere. A highly volatile substance such as rubbing alcohol (isopropyl alcohol) will quickly evaporate, while a substance with low volatility such as vegetable oil will remain condensed. In general, solids are much less volatile than liquids, but there are some exceptions. Solids that sublimate (change directly from solid to vapor) such as dry ice (solid carbon dioxide) or iodine can vaporize at a similar rate as some liquids under standard conditions. | 0 | Theoretical and Fundamental Chemistry |
2A peptides are a class of 18–22 aa-long peptides, which can induce ribosomal skipping during translation of a protein in a biological cell. These peptides share a core sequence motif of , and are found in a wide range of viral families. 2A peptides can be introduced artificially to help generate polyproteins from a single ORF, by causing the ribosome to fail at making a peptide bond, and then resume translation.
The members of 2A peptides are named after the virus in which they have been first described. For example, F2A, the first described 2A peptide, is derived from foot-and-mouth disease virus. The name "2A" itself comes from the gene numbering scheme of this virus.
These peptides are also known as "self-cleaving" peptides, which is a known misnomer, because the missing peptide bond is never synthesized by the ribosome, and is thus not cleaved. | 1 | Applied and Interdisciplinary Chemistry |
Natural water reservoirs in Texas have been threatened by anthropogenic activities due to large petroleum refineries and oil wells (i.e. emission and wastewater discharge), massive agricultural activities (i.e. pesticide release) and mining extractions (i.e. toxic wastewater) as well as natural phenomena involving frequent HAB events. For the first time in 1985, the state of Texas documented the presence of the P. parvum (golden alga) bloom along the Pecos River. This phenomenon has affected 33 reservoirs in Texas along major river systems, including the Brazos, Canadian, Rio Grande, Colorado, and Red River, and has resulted in the death of more than 27 million fish and caused tens of millions of dollars in damage. | 0 | Theoretical and Fundamental Chemistry |
Wrackmeyer-type 1,1 carboboration is proposed to go through a zwitterionic intermediate, and this intermediate has been isolated and characterized in some cases. However, the mechanism can be highly substrate and reagent dependent.
In a borane, the compound typically adopts a trigonal planar molecular geometry, making the boron atom an electrophilic center. The substituents can affect the strength of the borane as a Lewis acid. Boranes which are stronger Lewis acids are better electrophiles and therefore better able to facilitate carboboration. Boranes can be optimized to work on less activated substrates. Tris(pentafluorophenyl)borane [B(CF)] is a strongly Lewis acidic borane which functions well in 1,1 carboborations with both activated and unactivated substrates, and it allows for the reaction to be facilitated with more mild conditions. An activated substrate such as an alkene or alkyne has an electron-withdrawing group directly attached to a carbon within the double or triple bond. Transition metal catalysts have been utilized to develop enantioselective 1,1 carboborations on unactivated alkenes. These reactions go through a catalytic cycle which may or may not go through a zwitterionic intermediate. | 0 | Theoretical and Fundamental Chemistry |
In chemical engineering, a cascade is a plant consisting of several similar stages with each processing the output from the previous stage. Cascades are most commonly used in isotope separation, distillation, flotation and other separation or purification processes. | 1 | Applied and Interdisciplinary Chemistry |
Batroxobin, is a serine protease found in snake venom produced by Bothrops atrox and Bothrops moojeni, venomous species of pit viper found east of the Andes in South America. It cleaves fibrinogen, similarly to thrombin. Batroxobin from B atrox is used as a drug called "Reptilase" that is used to stop bleeding, while batroxobin from B moojeni is a drug called "Defibrase", used to break up blood clots. It is also used in a system called "Vivostat", where a person's blood is taken just before surgery and exposed to batroxobin; the resulting clots are then harvested, and then dissolved, forming a fibrin glue that is then used on the person during the surgery. | 1 | Applied and Interdisciplinary Chemistry |
Thermodynamic adiabatic processes have no entropy change. Typically, an external control modifies
the state. A quantum version of an adiabatic process can be modeled by an externally controlled time dependent
Hamiltonian . If the system is isolated, the dynamics are unitary, and therefore, is
a constant. A quantum adiabatic process is defined by the energy entropy being constant.
The quantum adiabatic
condition is therefore equivalent to no net change in the population of the instantaneous energy levels.
This implies that the Hamiltonian should commute with itself at different times: .
When the adiabatic conditions are not fulfilled, additional work is required to reach the final control
value. For an isolated system, this work is recoverable, since the dynamics is unitary and can be reversed. In this case, quantum friction can be suppressed using shortcuts to adiabaticity as demonstrated in the laboratory using a unitary Fermi gas in a time-dependent trap.
The coherence stored in the off-diagonal elements of the density operator carry the required information
to recover the extra energy cost and reverse the dynamics. Typically, this energy is not recoverable, due
to interaction with a bath that causes energy dephasing. The bath, in this case, acts like a measuring
apparatus of energy. This lost energy is the quantum version of friction. | 0 | Theoretical and Fundamental Chemistry |
Over the decades that pheromone pest programs have been used several disadvantages have been argued when compared to the use of conventional pesticides. Most pheromones target a single species, so a specific mating disruption formulation controls only the species that uses that pheromone blend; whereas pesticides usually kill indiscriminately a plethora of species, including multiple species with a single application. Some synthetic pheromones have high developmental and production costs, causing the mating disruption technique to be too costly to be adopted by conventional commercial growers. Furthermore most commercial pheromone mating disruption formulations must be applied by hand, which can be an expensive and time consuming. Novel pheromone formulations recently developed to be mechanically applied provide long lasting mating disruption effects (e.g., depending on the target pest a single application of SPLAT controls the target pest for a complete reproductive cycle, or for the entire season. | 1 | Applied and Interdisciplinary Chemistry |
In order to launch his company, Alexis Moussalli also associated with Secor (Société d'exportation, commission, représentation), a French-American corporation, which was to field Tho-Radia products on the market. The brand was officially launched in 1932 for Paris and in 1933 for the rest of France. Tho-Radia creams got noticed through their recognisable advertising, designed by publicist Tony Burnand, depicting a young, blond woman lit from below by visible rays. This image, which became associated with the brand in the public consciousness, would serve into the 1950s. The success of Tho-Radia creams allowed Alexis Moussalli to start selling powder, toothpaste and soap, although the two later were sold as containing only thorium.
The first products by Tho-Radia did actually contain radium, as a July 1932 analysis by Colombes scientific research laboratory certified that 100 grams of cream contained "0,223 microgram of radium bromide".
From 1937, regulation on radioactive materials changed, limiting their usage to medical prescription and mandating a red label with the mentions "Poison", or "Toxic" for products with internal use. Tho-Radia then changed its marketing, and on 23 April 1937, SECOR registered the Tho-Radia brand again, but leaving out any mention of radium and of Alfred Curie, only to keep the name of the now successful line of products. | 0 | Theoretical and Fundamental Chemistry |
In physics, the scallop theorem states that a swimmer that performs a reciprocal motion cannot achieve net displacement in a low-Reynolds number Newtonian fluid environment, i.e. a fluid that is highly viscous. Such a swimmer deforms its body into a particular shape through a sequence of motions and then reverts to the original shape by going through the sequence in reverse. It does not matter how fast or slow the swimmer executes the sequence. At low Reynolds number, time or inertia does not come into play, and the swimming motion is purely determined by the sequence of shapes that the swimmer assumes.
Edward Mills Purcell stated this theorem in his 1977 paper Life at Low Reynolds Number explaining physical principles of aquatic locomotion. The theorem is named for the motion of a scallop which opens and closes a simple hinge during one period. Such motion is not sufficient to create migration at low Reynolds numbers. The scallop is an example of a body with one degree of freedom to use for motion. Bodies with a single degree of freedom deform in a reciprocal manner and subsequently, bodies with one degree of freedom do not achieve locomotion in a highly viscous environment. | 1 | Applied and Interdisciplinary Chemistry |
This rule pertains to phosphorescence and similar phenomena. Electrons vibrate and resonate around molecules in different modes (electronic state), usually depending on the energy of the system of electrons. This law states that constant-energy flipping between two electronic states happens more readily when the vibrations of the electrons are preserved during the flip: any change in the spin of an electron is compensated by a change in its orbital motion (spin-orbit coupling).
Intersystem crossing (ISC) is a photophysical process involving an isoenergetic radiationless transition between two electronic states having different multiplicities. It often results in a vibrationally excited molecular entity in the lower electronic state, which then usually decays to its lowest molecular vibrational level. ISC is forbidden by rules of conservation of angular momentum. As a consequence, ISC generally occurs on very long time scales. However, the El-Sayed rule states that the rate of intersystem crossing, e.g. from the lowest singlet state to the triplet manifold, is relatively large if the radiationless transition involves a change of molecular orbital type. For example, a (π,π*) singlet could transition to a (n,π*) triplet state, but not to a (π,π*) triplet state and vice versa. Formulated by El-Sayed in the 1960s, this rule found in most photochemistry textbooks as well as the IUPAC Gold Book. The rule is useful in understanding phosphorescence, vibrational relaxation, intersystem crossing, internal conversion and lifetimes of excited states in molecules. | 1 | Applied and Interdisciplinary Chemistry |
They find use in coatings, adhesives, sealants and elastomers. Specific uses include industrial coatings, UV coating resins, floor coatings, hygiene coatings, wood coatings, adhesives, concrete coatings, automotive coatings, clear coatings and anticorrosive applications. They are also used in the design and manufacture of medical devices such as the polyurethane dressing, a liquid bandage based on polyurethane dispersion. To improve their functionality in flame retardant applications, products are being developed which have this feature built into the polymer molecule. They have also found use in general textile applications such as coating nonwovens. Leather coatings with antibacterial properties have also been synthesized using PUDs and silver nanoparticles. On a similar theme, recent (post 2020) innovations have included producing a waterborne polyurethane that has embedded silver particles to combat COVID. | 0 | Theoretical and Fundamental Chemistry |
The π orbitals of an alkene can stabilize a transition state by helping to delocalize the positive charge of the carbocation. For instance the unsaturated tosylate will react more quickly (10 times faster for aqueous solvolysis) with a nucleophile than the saturated tosylate.
The carbocationic intermediate will be stabilized by resonance where the positive charge is spread over several atoms. In the diagram below this is shown.
Here is a different view of the same intermediates.
Even if the alkene is more remote from the reacting center the alkene can still act in this way. For instance in the following alkyl benzenesulfonate the alkene is able to delocalise the carbocation. | 0 | Theoretical and Fundamental Chemistry |
Nitriles can be prepared by the dehydration of primary amides. Common reagents for this include phosphorus pentoxide () and thionyl chloride (). In a related dehydration, secondary amides give nitriles by the von Braun amide degradation. In this case, one C-N bond is cleaved. | 0 | Theoretical and Fundamental Chemistry |
There is an important shortcoming for DLTS: it cannot be used for insulating materials. (Note: an insulator can be considered as a very large bandgap semiconductor.) For insulating materials it is difficult or impossible to produce a device having a space region for which width could be changed by the external voltage bias and thus the capacitance measurement-based DLTS methods cannot be applied for the defect analysis. Basing on experiences of the thermally stimulated current (TSC) spectroscopy, the current transients are analyzed with the DLTS methods (I-DLTS), where the light pulses are used for the defect occupancy disturbance. This method in the literature is sometimes called the Photoinduced Transient Spectroscopy (PITS). I-DLTS or PITS are also used for studying defects in the i-region of a p-i-n diode. | 0 | Theoretical and Fundamental Chemistry |
Diffuse reflectance spectroscopy, or diffuse reflection spectroscopy, is a subset of absorption spectroscopy. It is sometimes called remission spectroscopy. Remission is the reflection or back-scattering of light by a material, while transmission is the passage of light through a material. The word remission implies a direction of scatter, independent of the scattering process. Remission includes both specular and diffusely back-scattered light. The word reflection often implies a particular physical process, such as specular reflection.
The use of the term remission spectroscopy is relatively recent, and found first use in applications related to medicine and biochemistry. While the term is becoming more common in certain areas of absorption spectroscopy, the term diffuse reflectance is firmly entrenched, as in diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and diffuse-reflectance ultraviolet–visible spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
ATP-gated channels open in response to binding the nucleotide ATP. They form trimers with two transmembrane helices per subunit and both the C and N termini on the intracellular side. | 1 | Applied and Interdisciplinary Chemistry |
The vertical axis is labeled E for the voltage potential with respect to the standard hydrogen electrode (SHE) as calculated by the Nernst equation. The "H" stands for hydrogen, although other standards may be used, and they are for room temperature only.
For a reversible redox reaction described by the following chemical equilibrium:
With the corresponding equilibrium constant :
The Nernst equation is:
sometimes formulated as:
or, more simply directly expressed numerically as:
where:
* volt is the thermal voltage or the "Nernst slope" at standard temperature
* λ = ln(10) ≈ 2.30, so that volt.
The horizontal axis is labeled pH for the −log function of the H ion activity.
The lines in the Pourbaix diagram show the equilibrium conditions, that is, where the activities are equal, for the species on each side of that line. On either side of the line, one form of the species will instead be said to be predominant.
In order to draw the position of the lines with the Nernst equation, the activity of the chemical species at equilibrium must be defined. Usually, the activity of a species is approximated as equal to the concentration (for soluble species) or partial pressure (for gases). The same values should be used for all species present in the system.
For soluble species, the lines are often drawn for concentrations of 1 M or 10 M. Sometimes additional lines are drawn for other concentrations.
If the diagram involves the equilibrium between a dissolved species and a gas, the pressure is usually set to P = 1 atm = , the minimum pressure required for gas evolution from an aqueous solution at standard conditions.
In addition, changes in temperature and concentration of solvated ions in solution will shift the equilibrium lines in accordance with the Nernst equation.
The diagrams also do not take kinetic effects into account, meaning that species shown as unstable might not react to any significant degree in practice.
A simplified Pourbaix diagram indicates regions of "immunity", "corrosion" and "passivity", instead of the stable species. They thus give a guide to the stability of a particular metal in a specific environment. Immunity means that the metal is not attacked, while corrosion shows that general attack will occur. Passivation occurs when the metal forms a stable coating of an oxide or other salt on its surface, the best example being the relative stability of aluminium because of the alumina layer formed on its surface when exposed to air. | 0 | Theoretical and Fundamental Chemistry |
Environmental temperature: Decomposition is accelerated by high atmospheric or environmental temperature, with putrefaction speed optimized between and , further sped along by high levels of humidity. This optimal temperature assists in the chemical breakdown of the tissue and promotes microorganism growth. Decomposition nearly stops below or above .
Moisture and air exposure: Putrefaction is ordinarily slowed by the body being submerged in water, due to diminished exposure to air. Air exposure and moisture can both contribute to the introduction and growth of microorganisms, speeding degradation. In a hot and dry environment, the body can undergo a process called mummification where the body is completely dehydrated and bacterial decay is inhibited.
Clothing: Loose-fitting clothing can speed up the rate of putrefaction, as it helps to retain body heat. Tight-fitting clothing can delay the process by cutting off blood supply to tissues and eliminating nutrients for bacteria to feed on.
Manner of burial: Speedy burial can slow putrefaction. Bodies within deep graves tend to decompose more slowly due to the diminished influences of changes in temperature. The composition of graves can also be a significant contributing factor, with dense, clay-like soil tending to speed putrefaction while dry and sandy soil slows it.
Light exposure: Light can also contribute indirectly, as flies and insects prefer to lay eggs in areas of the body not exposed to light, such as the crevices formed by the eyelids and nostrils. | 1 | Applied and Interdisciplinary Chemistry |
Another classification system for carboxypeptidases refers to their substrate preference.
* In this classification system, carboxypeptidases that have a stronger preference for those amino acids containing aromatic or branched hydrocarbon chains are called carboxypeptidase A (A for aromatic/aliphatic).
* Carboxypeptidases that cleave positively charged amino acids (arginine, lysine) are called carboxypeptidase B (B for basic).
A metallo-carboxypeptidase that cleaves a C-terminal glutamate from the peptide N-acetyl-L-aspartyl-L-glutamate is called "glutamate carboxypeptidase".
A serine carboxypeptidase that cleaves the C-terminal residue from peptides containing the sequence -Pro-Xaa (Pro is proline, Xaa is any amino acid on the C-terminus of a peptide) is called "prolyl carboxypeptidase". | 1 | Applied and Interdisciplinary Chemistry |
Expose-R (R stands for its mounting on the Russian module Zvezda) was mounted by Russian cosmonauts extravehicular activity on 11 March 2009 and the exposure to outer space conditions continued for 682 days until 21 January 2011, when it was brought back to Earth by the last Discovery Shuttle flight STS-133 on 9 March 2011. EXPOSE-R was equipped with three trays housing eight experiments and 3 radiation dosimeters. Each tray was loaded with a variety of biological organisms including plant seeds and spores of bacteria, fungi and ferns that were exposed to the harsh space environment for about one and a half years. The ROSE (Response of Organisms to Space Environment) group of experiments are under the coordination of the German Aerospace Center (DLR) and has been composed of scientists from different European countries, from United States and from Japan. In its 8 experiments of biological and chemical content, more than 1200 individual samples were exposed to solar ultraviolet (UV) radiations, vacuum, cosmic rays or extreme temperature variations. In their different experiments, the involved scientists are studying the question of lifes origin on Earth and the results of their experiments are contributing to different aspects of the evolution and distribution of life in the Universe.
The EXPOSE-R experiments are:
* AMINO, study of solar ultraviolet (UV) effects on amino acids and other organic compounds placed in terrestrial orbit.
* ORGANICS, study of the evolution of organic matter placed in outer space.
* ENDO (ROSE-1), study the effects of radiation on endolithic microorganisms (growing within cracks and pore spaces in rocks).
* OSMO (ROSE-2), study of the exposition of osmophilic microorganisms to space environment.
* SPORES (ROSE-3), study of spores placed inside artificial meteorites.
* PHOTO (ROSE-4), study of solar radiation effects on the genetic material of spores.
* SUBTIL (ROSE-5), study of mutagen effect of space environment on bacterial spores (Bacillus subtilis).
* PUR (ROSE-8), study of space environment effect on T7 phage, its DNA and of polycristalline uracil.
* IMBP (Institute of Biomedical Problems), this included bacterial spores, fungal spores, plant seeds, and eggs of lower crustacean and cryptobiotic larvae. | 1 | Applied and Interdisciplinary Chemistry |
In 1976, fermentation broths obtained from the soil bacterium Streptomyces cattleya were found to be active in a screen for inhibitors of peptidoglycan biosynthesis. Initial attempts to isolate the active compound proved difficult due to its chemical instability. After many attempts and extensive purification, the material was finally isolated in >90% purity, allowing for the structural elucidation of thienamycin in 1979.
Thienamycin was the first among the naturally occurring class of carbapenem antibiotics to be discovered and isolated. Carbapenems are similar in structure to their antibiotic “cousins” the penicillins. Like penicillins, carbapenems contain a β-lactam ring (cyclic amide) fused to a five-membered ring. Carbapenems differ in structure from penicillins in that within the five-membered ring a sulfur is replaced by a carbon atom (C1) and an unsaturation is present between C2 and C3 in the five-membered ring. | 0 | Theoretical and Fundamental Chemistry |
A dry cell is a type of electric battery, commonly used for portable electrical devices. Unlike wet cell batteries, which have a liquid electrolyte, dry cells use an electrolyte in the form of a paste, and are thus less susceptible to leakage.
The dry cell was developed in 1886 by the German scientist Carl Gassner, after development of wet zinc–carbon batteries by Georges Leclanché in 1866. A type of dry cell was also developed by the Japanese inventor Sakizō Yai in 1887. | 0 | Theoretical and Fundamental Chemistry |
Langerin consists of a relatively short intracellular domain and an extracellular domain which consists of a neck-region and a carbohydrate recognition domain (CRD). The intracellular part contains a proline-rich domain (PRD). The neck region consists of alpha-helixes and mediates a formation of langerin homotrimers via a coiled-coil interaction. The homotrimers formation increases avidity and specificity of the antigen.
The CRD of langerin is similar to CRDs of other C-type lectins. It contains an EPN motif – a Glu-Pro-Asn rich region. The CRD is divided into two lobes by 2 anti-parallel beta-sheets. The upper lobe creates the primary Ca2+ dependent carbohydrates binding site. In contrast to other lectins, for instance, DC-SIGN / DC-SIGNR and MBP, langerin has only one binding site for Ca2+. In the upper lobe, there have been discovered two other binding sites by a crystallization method. These sites are not dependent on Ca2+ and their relation to the primary binding site is not completely understood. All the binding sites are flanked by positively charged amino acids (K299 and K313) which enable binding of negatively charged sulphated carbohydrates. These amino acids are not present in DC-SIGN. | 1 | Applied and Interdisciplinary Chemistry |
The energy of the bulk component of a solid substrate is determined by the types of interactions that hold the substrate together. High-energy substrates are held together by bonds, while low-energy substrates are held together by forces. Covalent, ionic, and metallic bonds are much stronger than forces such as van der Waals and hydrogen bonding. High-energy substrates are more easily wetted than low-energy substrates. In addition, more complete wetting will occur if the substrate has a much higher surface energy than the liquid. | 0 | Theoretical and Fundamental Chemistry |
Myristoylation plays a vital role in membrane targeting and signal transduction in plant responses to environmental stress. In addition, in signal transduction via G protein, palmitoylation of the α subunit, prenylation of the γ subunit, and myristoylation is involved in tethering the G protein to the inner surface of the plasma membrane so that the G protein can interact with its receptor. | 1 | Applied and Interdisciplinary Chemistry |
The hydroxyl radical, HO, is the neutral form of the hydroxide ion (HO). Hydroxyl radicals are highly reactive and consequently short-lived; however, they form an important part of radical chemistry. Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water. It is also an important radical formed in radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments. Hydroxyl radicals are also produced during UV-light dissociation of HO (suggested in 1879) and likely in Fenton chemistry, where trace amounts of reduced transition metals catalyze peroxide-mediated oxidations of organic compounds.
In organic synthesis hydroxyl radicals are most commonly generated by photolysis of 1-Hydroxy-2(1H)-pyridinethione.
The hydroxyl radical is often referred to as the "detergent" of the troposphere because it reacts with many pollutants, often acting as the first step to their removal. It also has an important role in eliminating some greenhouse gases like methane and ozone. The rate of reaction with the hydroxyl radical often determines how long many pollutants last in the atmosphere, if they do not undergo photolysis or are rained out. For instance, methane, which reacts relatively slowly with hydroxyl radical, has an average lifetime of >5 years and many CFCs have lifetimes of 50+ years. Pollutants, such as larger hydrocarbons, can have very short average lifetimes of less than a few hours.
The first reaction with many volatile organic compounds (VOCs) is the removal of a hydrogen atom, forming water and an alkyl radical (R).
:HO + RH → HO + R
The alkyl radical will typically react rapidly with oxygen forming a peroxy radical.
:R + O → RO
The fate of this radical in the troposphere is dependent on factors such as the amount of sunlight, pollution in the atmosphere and the nature of the alkyl radical that formed it (See chapters 12 & 13 in External Links "University Lecture notes on Atmospheric chemistry) | 1 | Applied and Interdisciplinary Chemistry |
*Zelinsky did not patent the gas mask he invented, believing that one should not profit from human misfortunes, and Russia transferred the right to produce it to the Allies.
*The only surviving copy of the first gas mask is in Zelinsky's apartment.
*During an internship in Germany before the start of the war, Zelinsky synthesized chloropicrin for the first time, and became the first person to experience its toxic effects. Later, chloropicrin, discovered by Zelinsky, was widely used as a chemical warfare agent. | 0 | Theoretical and Fundamental Chemistry |
Praseodymium(III) oxalate can be prepared from the reaction of soluble praseodymium salts with oxalic acid: | 0 | Theoretical and Fundamental Chemistry |
One efficiency-focused research topic is improving the efficiency of photorespiration. Around 25% of the time RuBisCO incorrectly collects oxygen molecules instead of , creating and ammonia that disrupt the photosynthesis process. Plants remove these byproducts via photorespiration, requiring energy and nutrients that would otherwise increase photosynthetic output. In C3 plants photorespiration can consume 20-50% of photosynthetic energy. | 0 | Theoretical and Fundamental Chemistry |
The n-octanol-water partition coefficient, K is a partition coefficient for the two-phase system consisting of n-octanol and water. K is also frequently referred to by the symbol P, especially in the English literature. It is also called n-octanol-water partition ratio.
K serves as a measure of the relationship between lipophilicity (fat solubility) and hydrophilicity (water solubility) of a substance. The value is greater than one if a substance is more soluble in fat-like solvents such as n-octanol, and less than one if it is more soluble in water.
If a substance is present as several chemical species in the octanol-water system due to association or dissociation, each species is assigned its own K value. A related value, D, does not distinguish between different species, only indicating the concentration ratio of the substance between the two phases. | 0 | Theoretical and Fundamental Chemistry |
VAR is used most frequently in high value applications. It is an additional processing step to improve the quality of metal. Because it is time consuming and expensive, a majority of commercial alloys do not employ the process. Nickel, titanium, and specialty steels are materials most often processed with this method. The conventional path for production of titanium alloys includes single, double or even triple VAR processing. Use of this technique over traditional methods presents several advantages:
*The solidification rate of molten material can be tightly controlled. This allows a high degree of control over the microstructure as well as the ability to minimize segregation
*The gases dissolved in liquid metal during melting metals in open furnaces, such as nitrogen, oxygen and hydrogen are considered to be detrimental to the majority of steels and alloys. Under vacuum conditions these gases escape from liquid metal.
*Elements with high vapor pressure such as carbon, sulfur, and magnesium (frequently contaminants) are lowered in concentration.
*Centerline porosity and segregation are eliminated.
*Certain metals and alloys, such as Ti, cannot be melted in open air furnaces | 1 | Applied and Interdisciplinary Chemistry |
Aroa Biosurgery Limited first distributed OFM commercially in 2012 as Endoform™ Dermal Template (later Endoform™ Natural) through a distribution partnership with Hollister Incorporated (IL, USA). Endoform™ Natural and Endoform™ Antimicrobial (0.3% ionic silver w/w), are single layers of OFM is used in the treatment of acute and chronic wounds, including diabetic foot ulcers (DFU) and venous leg ulcers (VLU). Endoform™ Natural has been shown to accelerate wound healing of DFU. The wound product Symphony™ combines OFM and hyaluronic acid and is designed to support healing during the proliferative phase particularly in patients whose healing is severely impaired or compromised due to disease | 1 | Applied and Interdisciplinary Chemistry |
2-Iodophenol (o-iodophenol) is an aromatic organic compound with the formula ICHOH. It is a pale yellow solid that melts near room temperature. It undergoes a variety of coupling reactions in which the iodine substituent is replaced by a new carbon group ortho to the hydroxy group of the phenol, which can be followed by cyclization to form heterocycles.
It can be prepared by treatment of 2-chloromercuriphenol with iodine:
Direct reaction of phenol with iodine gives a mixture of 2- and 4-iodo derivatives. | 0 | Theoretical and Fundamental Chemistry |
As long as natural enemies have some potential to be omnivorous, plants can provide food resources to encourage their retention and increase the impact they have on herbivore populations. This potential, however, can hinge on a number of the insect's traits. For example, hemipteran predators can use their sucking mouthparts to make use of leaves, stems, and fruits, but spiders with chelicerae cannot. Still, insects widely considered to be purely carnivorous have been observed to diverge from expected feeding behavior. Some plants simply tolerate a low level of herbivory by natural enemies for the service they provide in ridding the plant of more serious herbivores. Others, however, have structures thought to serve no purpose other than attracting and provisioning natural enemies. These structures derive from a long history of coevolution between the first and third trophic levels. A good example is the extrafloral nectaries that many myrmecophytes and other angiosperms sport on leaves, bracts, stems, and fruits. Nutritionally, extrafloral nectaries are similar to floral nectaries, but they do not lead the visiting insect to come into contact with pollen. Their existence is therefore not the product of a pollinator–plant mutualism, but rather a tritrophic, defensive interaction. | 1 | Applied and Interdisciplinary Chemistry |
One method that used to cool molecules to temperatures near absolute zero is laser cooling. In the Doppler cooling process, lasers are used to remove energy from electrons of a given molecule to slow or cool the molecule down. This method has applications in quantum mechanics and is related to particle traps and the Bose–Einstein condensate. All of these methods use a "trap" consisting of lasers pointed at opposite equatorial angles on a specific point in space. The wavelengths from the laser beams eventually hit the gaseous atoms and their outer spinning electrons. This clash of wavelengths decreases the kinetic energy state fraction by fraction to slow or cool the molecules down. Laser cooling has also been used to help improve atomic clocks and atom optics. Ultracold studies are not usually focused on chemical interactions, but rather on fundamental chemical properties.
Because of the extremely low temperatures, diagnosing the chemical status is a major issue when studying low temperature physics and chemistry. The primary techniques in use today are optical - many types of spectroscopy are available, but these require special apparatus with vacuum windows that provide room temperature access to cryogenic processes. | 0 | Theoretical and Fundamental Chemistry |
Dry earth is a reasonably good thermal insulator, but over several weeks of habitation, a shelter will become dangerously hot. The simplest form of effective fan to cool a shelter is a wide, heavy frame with flaps that swing in the shelter's doorway and can be swung from hinges on the ceiling. The flaps open in one direction and close in the other, pumping air. (This is a Kearny air pump, or KAP, named after the inventor, Cresson Kearny.)
Unfiltered air is safe, since the most dangerous fallout has the consistency of sand or finely ground pumice. Such large particles are not easily ingested into the soft tissues of the body, so extensive filters are not required. Any exposure to fine dust is far less hazardous than exposure to the fallout outside the shelter. Dust fine enough to pass the entrance will probably pass through the shelter. Some shelters, however, incorporate NBC-filters for additional protection. | 0 | Theoretical and Fundamental Chemistry |
In the case of the murine leukemia viruses, a species of viruses capable of causing cancer in murines (mice), the viral life cycle can also be responsible for oncogenesis through a Gag-v-Onc fusion protein called "Mo-MuLV(src)", which is a Gag-v-Src protein capable of inducing oncogenesis in living mice. | 1 | Applied and Interdisciplinary Chemistry |
Cefapirin (INN, also spelled cephapirin) is an injectable, first-generation cephalosporin antibiotic. It is marketed under the trade name Cefadyl. Production for use in humans has been discontinued in the United States.
It also has a role in veterinary medicine as Metricure, an intrauterine preparation, and combined with prednisolone in Mastiplan, an intramammary preparation. Both are licensed in cattle. | 0 | Theoretical and Fundamental Chemistry |
Current research regarding Botrytis-induced kinase1 aims to determine how BIK1 interacts with MAPK pathway proteins as well as with the OXI1 kinase. Also, studies are being conducted to determine the relationship between BIK1 and the phosphorylizing homolog kinases PEPR1 and PEPR2. Though it is believed that PEPR1 and PEPR2 act as enzymes toward BIK1 and phosphorylate the kinase, research is still being done to examine the effects of the interaction on a broader scale. Previously published research suggests that PEPR1 and PEPR2 work with the ET signal pathway and Botrytis-induced kinase1 in order to amplify the defense mechanism in immune response. Additionally, future research may explore the mechanism that allows BIK1 and BAK1 to cooperate with the FLS2 receptor to initiate defense response. While it is known that the three work together and each is required for the process to occur efficiently, but the exact relationship between the three remains unknown and the specific binding residues for each component have yet to be determined in vivo. | 1 | Applied and Interdisciplinary Chemistry |
Gravimetric analysis, if methods are followed carefully, provides for exceedingly precise analysis. In fact, gravimetric analysis was used to determine the atomic masses of many elements in the periodic table to six figure accuracy. Gravimetry provides very little room for instrumental error and does not require a series of standards for calculation of an unknown. Also, methods often do not require expensive equipment. Gravimetric analysis, due to its high degree of accuracy, when performed correctly, can also be used to calibrate other instruments in lieu of reference standards. Gravimetric analysis is currently used to allow undergraduate chemistry/Biochemistry students to experience a grad level laboratory and it is a highly effective teaching tool to those who want to attend medical school or any research graduate school. | 0 | Theoretical and Fundamental Chemistry |
Energy recovery can reduce energy consumption by 50% or more. Much of the input energy can be recovered from the concentrate flow, and the increasing efficiency of energy recovery devices greatly reduces energy requirements. Devices used, in order of invention, are:
* Turbine or Pelton wheel: a water turbine driven by the concentrate flow, connected to the pump drive shaft provides part of the input power. Positive displacement axial piston motors have been used in place of turbines on smaller systems.
* Turbocharger: a water turbine driven by concentrate flow, directly connected to a centrifugal pump that boosts the output pressure, reducing the pressure needed from the pump and thereby its energy input, similar in construction principle to car engine turbochargers.
* Pressure exchanger: using the pressurized concentrate flow, via direct contact or a piston, to pressurize part of the membrane feed flow to near concentrate flow pressure. A boost pump then raises this pressure by typically 3 bar / 50 psi to the membrane feed pressure. This reduces flow needed from the high-pressure pump by an amount equal to the concentrate flow, typically 60%, and thereby its energy input. These are widely used on larger low-energy systems. They are capable of 3 kWh/m or less energy consumption.
* Energy-recovery pump: a reciprocating piston pump. The pressurized concentrate flow is applied to one side of each piston to help drive the membrane feed flow from the opposite side. These are the simplest energy recovery devices to apply, combining the high pressure pump and energy recovery in a single self-regulating unit. These are widely used on smaller low-energy systems. They are capable of 3 kWh/m or less energy consumption.
* Batch operation: RO systems run with a fixed volume of fluid (thermodynamically a closed system) do not suffer from wasted energy in the brine stream, as the energy to pressurize a virtually incompressible fluid (water) is negligible. Such systems have the potential to reach second-law efficiencies of 60%. | 0 | Theoretical and Fundamental Chemistry |
High-Mobility Group or HMG is a group of chromosomal proteins that are involved in the regulation of DNA-dependent processes such as
transcription, replication, recombination, and DNA repair. | 1 | Applied and Interdisciplinary Chemistry |
To describe the flow of geophysical fluids, equations are needed for conservation of momentum (or Newton's second law) and conservation of energy. The former leads to the Navier–Stokes equations which cannot be solved analytically (yet). Therefore, further approximations are generally made in order to be able to solve these equations. First, the fluid is assumed to be incompressible. Remarkably, this works well even for a highly compressible fluid like air as long as sound and shock waves can be ignored. Second, the fluid is assumed to be a Newtonian fluid, meaning that there is a linear relation between the shear stress and the strain , for example
where is the viscosity. Under these assumptions the Navier-Stokes equations are
The left hand side represents the acceleration that a small parcel of fluid would experience in a reference frame that moved with the parcel (a Lagrangian frame of reference). In a stationary (Eulerian) frame of reference, this acceleration is divided into the local rate of change of velocity and advection, a measure of the rate of flow in or out of a small region.
The equation for energy conservation is essentially an equation for heat flow. If heat is transported by conduction, the heat flow is governed by a diffusion equation. If there are also buoyancy effects, for example hot air rising, then natural convection, also known as free convection, can occur. Convection in the Earths outer core drives the geodynamo that is the source of the Earths magnetic field. In the ocean, convection can be thermal (driven by heat), haline (where the buoyancy is due to differences in salinity), or thermohaline, a combination of the two. | 1 | Applied and Interdisciplinary Chemistry |
Nesmeyanov, together with N.K. Kochetkov and M.I. Rybinskaya, developed a method for the synthesis of various five- and six-membered heterocycles, which is based on the high activity of carbonyl groups and the mobility of the β-substituent in compounds of the type RCOCH=CHX. The same group of scientists developed the method of "β-ketovinylation", which consists in introducing an RCOCH=CH group into the molecule. The reaction of β-substituted vinyl ketones with an azide ion made it possible to study the stereochemistry and propose a mechanism for nucleophilic substitution at the activated double bond.
In collaboration with other scientists, Nesmeyanov carried out a number of works in the field of radical telomerization and rearrangement radicals. In addition to studies of already known reactions, thermal telomerization of ethylene and propylene with silicon hydrides has been developed and other new telomerization reactions. Also, new routes for the synthesis of compounds containing groups such as CCl, CClCHCl, CClC=CH, CCl=CHX and others. The study of compounds containing the CCl-C=CCBr=CH to CCl=CClCHBr under ultraviolet illumination.
In continuation of the work related to the previously created diazo method, Nesmeyanov and L. G. Makarova investigated the mechanism of decomposition of aryldiazonium and diaryliodonium salts. This made it possible to synthesize new types of onium compounds - diphenylbromonium, diphenylchloronium and triphenyloxonium salts. Together with T. P. Tolstaya and other scientists, Nesmeyanov showed that double salts of diphenylbromonium and diphenylchloronium halides with heavy metal halides are decomposed by powders of the corresponding metals with the formation of organometallic compounds. Thus, the diazo method began to be used to obtain σ-aryl complexes of transition metals and other organometallic compounds. | 0 | Theoretical and Fundamental Chemistry |
After the discovery of HEPT and TIBO, compounds screening methods were used to develop BI-RG-587, the first NNRTI commonly known as nevirapine. Like HEPT and TIBO, nevirapine blocked viral RT activity by non-competitive inhibition (with respect to dNTP binding). This reinforced the idea that the new class of anti-HIV inhibitors was inhibiting the activity of RT but not at the active site. Several molecular families of NNRTIs have emerged following screening and evolution of many molecules.
Three NNRTI compounds of the first generation have been approved by the FDA for treating HIV-1 infection. Nevirapine was approved in 1996, delavirdine in 1997 and efavirenz in 1998 (table 1). Two of these drugs, nevirapine and efavirenz, are cornerstones of first line HAART while delavirdine is hardly used nowadays. The structure of these three drugs show the wide array of rings, substituents, and bonds that allow activity against HIV-1 RT. This diversity demonstrates why so many non-nucleosides have been synthesised but doesn't explain why only three drugs have reached the market. The main problem has been the potency of these compounds to develop resistance. | 1 | Applied and Interdisciplinary Chemistry |
Mathematically, the vorticity of a three-dimensional flow is a pseudovector field, usually denoted by , defined as the curl of the velocity field describing the continuum motion. In Cartesian coordinates:
In words, the vorticity tells how the velocity vector changes when one moves by an infinitesimal distance in a direction perpendicular to it.
In a two-dimensional flow where the velocity is independent of the -coordinate and has no -component, the vorticity vector is always parallel to the -axis, and therefore can be expressed as a scalar field multiplied by a constant unit vector :
The vorticity is also related to the flows circulation (line integral of the velocity) along a closed path by the (classical) Stokes theorem. Namely, for any infinitesimal surface element with normal direction and area , the circulation along the perimeter of is the dot product where is the vorticity at the center of . | 1 | Applied and Interdisciplinary Chemistry |
Emerin has been shown to interact with:
* ACTA1,
* ACTG2,
* BANF1,
* BCLAF1,
* CTNNB1,
* GMCL1,
* LMNA,
* PSME1,
* SYNE1,
* SYNE2,
* TMEM43, and
* YTHDC1. | 1 | Applied and Interdisciplinary Chemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.