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RANKL is a member of the TNF superfamily of ligands. Through binding to the RANK receptor it activates various molecules, like NF-kappa B, MAPK, NFAT and PI3K52. The RANKL/RANK signaling pathway regulates osteoclastogenesis, as well as, the survival and activation of osteoclasts. | 0 | Theoretical and Fundamental Chemistry |
Under physiological conditions, ptaquiloside readily liberates glucose to produce the ptaquilodienone. The alkylation of amino acids with the dienone mostly takes place at the thiol group in cysteine, glutathione and methionine. The alkylation at the carboxylate group of each amino acid, forming the corresponding ester, is also observed to a small extent based on the previously reported literature. The dienone reacts with both adenine (majorly at N-3) and guanine (majorly at N-7) residues of DNA to form the DNA adducts. The alkylation induces spontaneous depurination and cleavage of DNA at adenine base site. In a model reaction with a deoxytetranucleotide (as shown on the right), a covalent adduct is found at a guanine residue and the N-glycosidic bond breaks to release the adduct. In 1998, Prakash, Smith and co-workers showed that the alkylation of adenine by ptaquiloside in codon 61 followed by depurination and error in the DNA synthesis resulted in the activation of H-ras proto-oncogene in the ileum of calves fed bracken. | 0 | Theoretical and Fundamental Chemistry |
Epicillin (INN) is a penicillin antibiotic. It is not approved by the FDA for use in the United States.
It is an aminopenicillin. | 0 | Theoretical and Fundamental Chemistry |
Ductile iron pipe is sized according to a dimensionless term known as the Pipe Size or Nominal Diameter (known by its French abbreviation, DN). This is roughly equivalent to the pipe's internal diameter in inches or millimeters. However, it is the external diameter of the pipe that is kept constant between changes in wall thickness, in order to maintain compatibility in joints and fittings. Consequently, the internal diameter varies, sometimes significantly, from its nominal size.
Pipe dimensions are standardised to the mutually incompatible AWWA C151 (US Customary Units) in the United States, ISO 2531 / EN 545/598 (metric) in Europe, and AS/NZS 2280 (metric) in Australia and New Zealand. Although both metric, European and Australian are not compatible and pipes of identical nominal diameters have quite different dimensions. | 1 | Applied and Interdisciplinary Chemistry |
Although ELPs generally form reversible spherical aggregates due to their proline and glycine content, there is a possibility that, under certain conditions such as exceedingly high temperatures, ELPs will form amyloids, or irreversible aggregates of insoluble protein. It is also believed that changes in the ELP backbone leading to a reduction in the proline and glycine content may lead to ELPs with a greater propensity for the amyloid state. As amyloids are implicated in the progression of Alzheimer's disease as well as in prion-based diseases, such as Creutzfeldt-Jakob disease (CJD), modeling of ELP amyloid formation may be useful from a biomedical standpoint. | 0 | Theoretical and Fundamental Chemistry |
Triphenyltin hydride is the organotin compound with the formula (CH)SnH. It is a white distillable oil that is soluble in organic solvents. It is often used as a source of "H·" to generate radicals or cleave carbon-oxygen bonds. | 0 | Theoretical and Fundamental Chemistry |
One way the eudysmic ratio is computed is by dividing the EC or the IC of the eutomer by the same measurement of the distomer. Whether one chooses to use the EC or IC depends on the drug in question. | 0 | Theoretical and Fundamental Chemistry |
Chemically induced dimerization (CID) is a biological mechanism in which two proteins bind only in the presence of a certain small molecule, enzyme or other dimerizing agent. Genetically engineered CID systems are used in biological research to control protein localization, to manipulate signalling pathways and to induce protein activation. | 1 | Applied and Interdisciplinary Chemistry |
* Acellular Dermis. An acellular dermis is made by removing the cells (epidermis and dermal fibroblasts) from split-thickness skin. It has two sides: one side has a basal lamina suitable for the epithelial cells, and the other is suitable for fibroblast infiltration because it has intact vessel channels. It is durable, able to keep its structure and does not trigger immune reactions (non-immunogenic).
* Amniotic Membrane. The amniotic membrane, the inner part of the placenta, has a thick basement membrane of collagen type IV and laminin and avascular connective tissue. | 1 | Applied and Interdisciplinary Chemistry |
CdS and CdSe form solid solutions with each other. Increasing amounts of cadmium selenide, gives pigments verging toward red, for example CI pigment orange 20 and CI pigment red 108.<br />Such solid solutions are components of photoresistors (light dependent resistors) sensitive to visible and near infrared light. | 0 | Theoretical and Fundamental Chemistry |
Sono-Seq (Sonication of Cross-linked Chromatin Sequencing) is a method in molecular biology used for determining the sequences of those DNA regions in the genome near regions of open chromatin of expressed genes. It is also known as "Input" in the Chip-Seq protocol, since it follows the same steps except it doesn't require immunoprecipitation. | 1 | Applied and Interdisciplinary Chemistry |
Statins are a class of drugs used to treat cardiovascular disease by lowering lipid levels, specifically LDL-C levels. Statins have shown to reduce new cardiovascular events by 30-40%. However, complications may still arise even after taking the drug and some patients are statin-intolerant. Lipoprotein apheresis therapy is another nonsurgical treatment for reducing LDL-C concentrations.
PCSK9 inhibitors are a new drug that can replace statins and lipoprotein apheresis therapy. For patients that are statin-intolerant, PCSK9 inhibitors can provide a therapeutic alternative. | 1 | Applied and Interdisciplinary Chemistry |
Lichens can show intense antioxidant activity. Secondary metabolites are often deposited as crystals in the apoplast. Secondary metabolites are thought to play a role in preference for some substrates over others. | 1 | Applied and Interdisciplinary Chemistry |
The stem serves as a connector from the actuator to the inside of the valve and transmits this actuation force. Stems are either smooth for actuator controlled valves or threaded for manual valves. The smooth stems are surrounded by packing material to prevent leaking material from the valve. This packing is a wearable material and will have to be replaced during maintenance. With a smooth stem the ends are threaded to allow connection to the plug and the actuator. The stem must not only withstand a large amount of compression force during valve closure, but also have high tensile strength during valve opening. In addition, the stem must be very straight, or have low run out, in order to ensure good valve closure. This minimum run out also minimizes wear of the packing contained in the bonnet, which provides the seal against leakage. The stem may be provided with a shroud over the packing nut to prevent foreign bodies entering the packing material, which would accelerate wear. | 1 | Applied and Interdisciplinary Chemistry |
Before 1960, virtually all measurements of photoelectron kinetic energies were for electrons emitted from metals and other solid surfaces. In about 1956, Kai Siegbahn developed X-ray photoelectron spectroscopy (XPS) for surface chemical analysis. This method uses x-ray sources to study energy levels of atomic core electrons, and at the time had an energy resolution of about 1 eV (electronvolt).
The ultraviolet photoelectron spectroscopy (UPS) was pioneered by Feodor I. Vilesov, a physicist at St. Petersburg (Leningrad) State University in Russia (USSR) in 1961 to study the photoelectron spectra of free molecules in the gas phase. The early experiments used monochromatized radiation from a hydrogen discharge and a retarding potential analyzer to measure the photoelectron energies.
The PES was further developed by David W. Turner, a physical chemist at Imperial College in London and then at Oxford University, in a series of publications from 1962 to 1967. As a photon source, he used a helium discharge lamp which emits a wavelength of 58.4 nm (corresponding to an energy of 21.2 eV) in the vacuum ultraviolet region. With this source, Turner's group obtained an energy resolution of 0.02 eV. Turner referred to the method as "molecular photoelectron spectroscopy", now usually "ultraviolet photoelectron spectroscopy" or UPS. As compared to XPS, UPS is limited to energy levels of valence electrons, but measures them more accurately. After 1967, commercial UPS spectrometers became available. One of the latest commercial devices was the Perkin Elmer PS18. For the last twenty years, the systems have been homemade. One of the latest in progress - Phoenix II - is that of the laboratory of Pau, IPREM developed by Dr. Jean-Marc Sotiropoulos. | 0 | Theoretical and Fundamental Chemistry |
According to this law, which is based on linearized shallow water equations, the spatial variations of the wave height (twice the amplitude for sine waves, equal to the amplitude for a solitary wave) for travelling waves in water of mean depth and width (in case of an open channel) satisfy
where is the fourth root of Consequently, when considering two cross sections of an open channel, labeled 1 and 2, the wave height in section 2 is:
with the subscripts 1 and 2 denoting quantities in the associated cross section. So, when the depth has decreased by a factor sixteen, the waves become twice as high. And the wave height doubles after the channel width has gradually been reduced by a factor four. For wave propagation perpendicular towards a straight coast with depth contours parallel to the coastline, take a constant, say 1 metre or yard.
For refracting long waves in the ocean or near the coast, the width can be interpreted as the distance between wave rays. The rays (and the changes in spacing between them) follow from the geometrical optics approximation to the linear wave propagation. In case of straight parallel depth contours this simplifies to the use of Snell's law.
Green published his results in 1838, based on a method – the Liouville–Green method – which would evolve into what is now known as the WKB approximation. Green's law also corresponds to constancy of the mean horizontal wave energy flux for long waves:
where is the group speed (equal to the phase speed in shallow water), is the mean wave energy density integrated over depth and per unit of horizontal area, is the gravitational acceleration and is the water density. | 1 | Applied and Interdisciplinary Chemistry |
In 1979 teams at Harvard and Caltech extended the basic idea of making DNA copies of mRNAs in vitro to amplifying a library of such in bacterial plasmids. In 1982–1983, the idea of selecting random or semi-random clones from such a cDNA library for sequencing was explored by Greg Sutcliffe and coworkers. and Putney et al. who sequenced 178 clones from a rabbit muscle cDNA library. In 1991 Adams and co-workers coined the term expressed sequence tag (EST) and initiated more systematic sequencing of cDNAs as a project (starting with 600 brain cDNAs). The identification of ESTs proceeded rapidly, millions of ESTs now available in public databases (e.g. GenBank).
In 1995, the idea of reducing the tag length from 100 to 800 bp down to tag length of 10 to 22 bp helped reduce the cost of mRNA surveys. In this year, the original SAGE protocol was published by Victor Velculescu at the Oncology Center of Johns Hopkins University. Although SAGE was originally conceived for use in cancer studies, it has been successfully used to describe the transcriptome of other diseases and in a wide variety of organisms. | 1 | Applied and Interdisciplinary Chemistry |
Conductive measurements began as early as the 18th century, when Andreas Baumgartner noticed that salt and mineral waters from Bad Gastein in Austria conducted electricity. As such, using conductometry to determine water purity, which is often used today to test the effectiveness of water purification systems, began in 1776. Friedrich Kohlrausch further developed conductometry in the 1860s when he applied alternating current to water, acids, and other solutions. It was also around this time when Willis Whitney, who was studying the interactions of sulfuric acid and chromium sulfate complexes, found the first conductometric endpoint. These finding culminated into potentiometric titrations and the first instrument for volumetric analysis by Robert Behrend in 1883 while titrating chloride and bromide with HgNO. This development allowed for testing the solubility of salts and hydrogen ion concentration, as well as acid/base and redox titrations. Conductometry was further improved with the development of the glass electrode, which began in 1909. | 0 | Theoretical and Fundamental Chemistry |
Hückel's rule can also be applied to molecules containing other atoms such as nitrogen or oxygen. For example pyridine (CHN) has a ring structure similar to benzene, except that one -CH- group is replaced by a nitrogen atom with no hydrogen. There are still six π electrons and the pyridine molecule is also aromatic and known for its stability. | 0 | Theoretical and Fundamental Chemistry |
Thiourea is a planar molecule. The C=S bond distance is 1.71 Å. The C-N distances average 1.33 Å. The weakening of the C-S bond by C-N pi-bonding is indicated by the short C=S bond in thiobenzophenone, which is 1.63 Å.
Thiourea occurs in two tautomeric forms, of which the thione form predominates in aqueous solutions. The equilibrium constant has been calculated as K is . The thiol form, which is also known as an isothiourea, can be encountered in substituted compounds such as isothiouronium salts. | 0 | Theoretical and Fundamental Chemistry |
There are a number of correlations for slip ratio.
For homogeneous flow, S = 1 (i.e. there is no slip).
The Chisholm correlation is:
The Chisholm correlation is based on application of the simple annular flow model and equates the frictional pressure drops in the liquid and the gas phase.
The slip ratio for two-phase cross-flow horizontal tube bundles may be determined using the following correlation:
where the Richardson and capillary numbers are defined as and .
For enhanced surfaces bundles the slip ratio can be defined as:
Where:
* S – slip ratio, dimensionless
* P – tube centerline pitch
* D – tube diameter
* Subscript – liquid phase
* Subscript – gas phase
* g– gravitational acceleration
* – minimum distance between the tubes
* G-mass flux (mass flow per unit area)
* – dynamic viscosity
* – surface tension
* – thermodynamic quality
* – void fraction | 1 | Applied and Interdisciplinary Chemistry |
In a system with two spin-1/2 particlesfor example the proton and electron in the ground state of hydrogenmeasured on a given axis, each particle can be either spin up or spin down so the system has four basis states in all
using the single particle spins to label the basis states, where the first arrow and second arrow in each combination indicate the spin direction of the first particle and second particle respectively.
More rigorously
where and are the spins of the two particles, and and are their projections onto the z axis. Since for spin-1/2 particles, the basis states span a 2-dimensional space, the basis states span a 4-dimensional space.
Now the total spin and its projection onto the previously defined axis can be computed using the rules for adding angular momentum in quantum mechanics using the Clebsch–Gordan coefficients. In general
substituting in the four basis states
returns the possible values for total spin given along with their representation in the basis. There are three states with total spin angular momentum 1:
which are symmetric and a fourth state with total spin angular momentum 0:
which is antisymmetric. The result is that a combination of two spin-1/2 particles can carry a total spin of 1 or 0, depending on whether they occupy a triplet or singlet state. | 0 | Theoretical and Fundamental Chemistry |
Aluminium granules are manufactured by the melting of primary or secondary aluminium and blown in air or vacuum, or are cast in sand and then sieved off. Other methods include casting of molten aluminium in water. | 1 | Applied and Interdisciplinary Chemistry |
: Backcrossing is crossing an F1 with its parents to transfer a limited number of loci (e.g. transgene, disease resistance loci, etc.) from one genetic background to another. Usually the recipient of such genes is a cultivar that is already well performing - except for the gene that is to be transferred. So we want to keep the genetic background of the recipient genotypes, which is done by 4-6 rounds of repeated backcrosses while selecting for the gene of interest. | 1 | Applied and Interdisciplinary Chemistry |
Several towns in the Netherlands bear names ending in "dam," indicating their origin at the site of a dam in a tidal river. Prominent examples include Amsterdam (located at a dam in the Amstel) and Rotterdam (situated at a dam in the Rotte). However, some locations, like Maasdam, have less clear origins. Maasdam, a village situated at the site of a dam on the Maas dating back to before 1300, was the site of the construction of the Grote Hollandse Waard, which was subsequently lost during the devastating St. Elizabeth's Flood of 1421. However, presently the Maas river is far away from the village of Maasdam.
One technique widely employed in historical closures was known as (English: sinking up). This method involved sinking fascine mattresses, filling them with sand, and stabilising them with ballast stone. Successive sections were then sunk on top until the dam reached a height where no further mattresses could be placed. This process effectively reduced the flow, allowing the completion of the dam with sand and clay. For instance, the construction of the Sloedam in 1879, as part of the railway to Middelburg, utilised this technique.
Early observations revealed that during closures, the flow velocity within the closure gap increased, leading to soil erosion. Consequently, measures such as bottom protection around the closing gap were implemented, guided primarily by experiential knowledge rather than precise calculations. Until 1953, closing dike breaches in tidal areas posed challenges due to high current velocities. In such instances, new dikes were constructed further inland, albeit a lengthier process, to mitigate closure difficulties. An extreme example occurred after the devastating North Sea flood of 1953, necessitating the closure of breaches at Schelphoek, marking the last major closure in the Netherlands. | 1 | Applied and Interdisciplinary Chemistry |
The key elements of the NeSSI Generation II Specification are as follows.
* Adoption of a digital communication bus (NeSSI-bus) that is specifically tailored for process analytics and intended to replace 4-20 mA systems. This bus can handle up to 30 devices. (This bus would be equivalent to a plug-and-play USB bus on a personal computer but with special requirements.)
* For electrical equipment in hazardous areas, classifying the interior of an enclosure handling hazardous (flammable) fluids (e.g. hydrogen and ethylene) as Division 1/Zone 1 rather than Division/Zone 2.
* Adopting the use of a safe low energy, globally accepted method of electrical protection called intrinsic safety for the NeSSI-bus.
* Adopting the use of miniature smart/automated electronic devices including sensors (flow, pressure temperature), on/off and proportional actuators and enclosure heater controls.
* A move away from the use of local indicating devices such as gauges and rotameters in order to reduce labor-intensive manual checking (rounds).
* A move away from centralized control (automation) model to a local/field control model which is represented by a small computing device called the Sensor Actuator Manager (SAM).
* Adopting the concept of portable, commercially available software smart applets for the purpose of automating specific sample system functions. These applets would be resident in the SAM.
* Employing an Ethernet network between the SAM, the DCS and the Operator & Maintenance (O & M) user station. (NeSSI refers to this bus as the ANLAN)
* Introduction of a Graphical User Interface (GUI) for better visualization of physically compact sampling systems.
The first prototype of a multi node/miniature Generation II system was demonstrated by Siemens Process Analytics in 2006. Siemens has adapted an existing bus system called IC to operate in an intrinsically safe mode. This work was undertaken once it was determined that existing intrinsically safe capable digital communication systems such as Foundation Fieldbus and Profibus could not meet the requirements of reduced physical size as well as the lower cost and power draw defined by the NeSSI-bus. Whether or not this bus will go into wide commercial production is unknown at this time.
A nonprofit organization, CAN in Automation (CiA) released a 2007 Draft Standard Proposal (DSP-103), that specifies the physical layer of an intrinsically safe bus. [CAN = Controller Area Network] The specification has been developed by members of the CiA organization among them ABB, Pepperl+Fuchs, Texas Instruments, and Siemens. By using a lower voltage (9.5 V) for its power supply, this bus can provide more current (up to 1,000 mA) to power multiple devices in a hazardous environment. This group has standardized upon the 5-pin M8 pico connector for providing both power and signal to the devices. A commercial implementation of a process analytical system using this bus has yet to be demonstrated.
An interim development called Generation 1.5 uses both conventional 4-20 mA analogue sensors and discrete signals to actuate valves. A Programmable Logic Controller (PLC) is used as the Sensor Actuator Manager (SAM). | 1 | Applied and Interdisciplinary Chemistry |
* EPA. [http://www.epa.gov/volunteer/stream/vms511.html "Monitoring and Assessing Water Quality: Fecal Bacteria."] | 0 | Theoretical and Fundamental Chemistry |
Moexipril was an angiotensin converting enzyme inhibitor (ACE inhibitor) used for the treatment of hypertension and congestive heart failure. Moexipril can be administered alone or with other antihypertensives or diuretics.
It works by inhibiting the conversion of angiotensin I to angiotensin II.
It was patented in 1980 and approved for medical use in 1995. Moexipril is available from Schwarz Pharma under the trade name Univasc. | 0 | Theoretical and Fundamental Chemistry |
* Washington Accord
*International Professional Engineers Agreement (IPEA)
*Federation of Engineering Institutions of Asia and the Pacific (FEIAP)
*Federation of Engineering Institutions of Islamic Countries (FEIIC)
*Network of Accreditation Bodies for Engineering Education in Asia (NABEEA) | 1 | Applied and Interdisciplinary Chemistry |
Blanco initially wanted to study medicine after high school and become a neurosurgeon. However, she decided against this path after witnessing a surgery during a vocational internship and having a negative reaction to the sight of blood. She chose to pursue chemical engineering after shadowing a chemical engineer at a Venezuelan chemical company.
Blanco earned her bachelor's degree in Chemical Engineering from Universidad Simón Bolívar in Venezuela.
She moved to the United States in 2017 to attend New York University. Blanco has discussed initially feeling "so behind and so out of place" at NYU because, due to a lack of funding, the university she previously attended in Venezuela didn't have the up-to-date laboratory equipment and technology that the NYU research labs had.
Blanco earned her PhD in chemical engineering from New York University in 2020. | 1 | Applied and Interdisciplinary Chemistry |
For density matrices and on a Hilbert space, the quantum relative entropy from to is defined to be
In quantum information science the minimum of over all separable states can also be used as a measure of entanglement in the state . | 0 | Theoretical and Fundamental Chemistry |
Shadow enhancers are groups of two or more enhancers that control the same target gene and drive overlapping spatiotemporal expression patterns. Shadow enhancers are found in a wide range of organisms, from insects to plants to mammals, particularly in association with developmental genes. While seemingly redundant, the individual enhancers of a shadow enhancer group have been shown to be critical for proper gene expression in the face of both environmental and genetic perturbations. Such perturbations may exacerbate fluctuations in upstream regulators. | 1 | Applied and Interdisciplinary Chemistry |
Measurements (performed using a soy bean SCS) indicate an optimal temperature of 37 °C and an optimal pH of 7.0-8.0. | 1 | Applied and Interdisciplinary Chemistry |
Mono Lake is a vital resting and eating stop for migratory shorebirds and has been recognized as a site of international importance by the Western Hemisphere Shorebird Reserve Network.
Nearly 2,000,000 waterbirds, including 35 species of shorebirds, use Mono Lake to rest and eat for at least part of the year. Some shorebirds that depend on the resources of Mono Lake include American avocets, killdeer, and sandpipers. One to two million eared grebes and phalaropes use Mono Lake during their long migrations.
Late every summer tens of thousands of Wilson's phalaropes and red-necked phalaropes arrive from their nesting grounds, and feed until they continue their migration to South America or the tropical oceans respectively.
In addition to migratory birds, a few species spend several months to nest at Mono Lake. Mono Lake has the second largest nesting population of California gulls, Larus californicus, second only to the Great Salt Lake in Utah. Since abandoning the landbridged Negit Island in the late 1970s, California gulls have moved to some nearby islets and have established new, if less protected, nesting sites. Cornell University and Point Blue Conservation Science have continued the study of nesting populations on Mono Lake that was begun 35 years ago. Snowy plovers also arrive at Mono Lake each spring to nest along the northern and eastern shores. | 1 | Applied and Interdisciplinary Chemistry |
This equation represents flow to a pumping well (a sink of strength G), located at the origin. Both this equation and the Cartesian version above are the fundamental equation in groundwater flow, but to arrive at this point requires considerable simplification. Some of the main assumptions which went into both these equations are:
* the aquifer material is incompressible (no change in matrix due to changes in pressure — aka subsidence),
* the water is of constant density (incompressible),
* any external loads on the aquifer (e.g., overburden, atmospheric pressure) are constant,
* for the 1D radial problem the pumping well is fully penetrating a non-leaky aquifer,
* the groundwater is flowing slowly (Reynolds number less than unity), and
* the hydraulic conductivity (K) is an isotropic scalar.
Despite these large assumptions, the groundwater flow equation does a good job of representing the distribution of heads in aquifers due to a transient distribution of sources and sinks. | 1 | Applied and Interdisciplinary Chemistry |
Common cutting agents:
* Sugar: Brix refractometers are used to determine sugar content. Traditional handheld refractometers are cheap and can be used to measure whole percentages. Digital handheld refractometers are used to determine percentages in decimal values. | 0 | Theoretical and Fundamental Chemistry |
Immunoglobulin-like receptors are members of the immunoglobulin superfamily and have one or more 70-110 residue immunoglobulin domains (Ig) in their extracellular region, typically multiple such domains in tandem. Many of the genes encoding these proteins occur in the leukocyte receptor complex (LRC), a large gene cluster on human chromosome 19. Members of this group found in the human genome include:
* The killer-cell immunoglobulin-like receptor (KIR) family contains proteins with 2-3 extracellular Ig domains and long (inhibitory) or short (activating) cytoplasmic regions. Typically expressed in NK and some T cells, they interact with MHC class I. This gene family located in the LRC is highly polymorphic and there is individual variation in both alleles and copy number, as well as in alternative splicing. This family has undergone significant diversification in primate lineages.
* The leukocyte immunoglobulin-like receptors (LILR) family contains 13 genes, including two pseudogenes. They have 2-4 Ig domains. One member, LILRA3, lacks a transmembrane region and is a soluble protein; others may be expressed in soluble form through alternative splicing. Like the similar KIR family, LILR genes are found in the LRC and are polymorphic, though less so than KIR. LILR proteins are broadly expressed in immune cells and have very diverse ligands.
* The paired type 2 immunoglobulin like receptor (PILR) family contains two genes, PILRA (inhibiting) and PILRB (activating). They have a single extracellular Ig domain with a siglec-like structure.
* The signal regulatory protein (SIRP) family contains three genes, SIRPA (inhibiting), SIRPB1 (activating), and SIRPG (non-signaling), with the more distantly related SIRPD and SIRPB2 not yet well characterized. SIRPA interacts with CD47, a regulator of phagocytosis. This family also interacts with surfactant protein D.
* The carcinoembryonic antigen-related cell adhesion (CEACAM) family contains 12 genes with one or more Ig domains. They are expressed broadly, especially in endothelium and epithelium and have roles in cell-cell recognition. They have been extensively studied for their role in cancer and have been used as cancer biomarkers.
* The siglec family contains 15 genes divided into two evolutionarily related groups. This family has three members with activating motifs, Siglec-14, Siglec-15, and Siglec-16. These proteins bind sialic acids, and are often targeted by pathogens.
* TIGIT (T cell immunoreceptor with Ig and ITIM domains) is an inhibitory receptor that forms a nonhomologous but functional pair with DNAM1 (CD226). | 1 | Applied and Interdisciplinary Chemistry |
Membrane bioreactors were introduced in the late 1960s, shortly after commercial-scale ultrafiltration and microfiltration membranes became available. The original designs were introduced by Dorr-Oliver Inc. and combined the use of an activated sludge bioreactor with a cross-flow membrane filtration loop. The flat sheet membranes used in this process were polymeric and featured pore sizes ranging from 0.003 to 0.01 μm. Although the idea of replacing the settling tank of the conventional activated sludge process was attractive, it was difficult to justify the use of such a process because of the high cost of membranes, the low economic value of the product (tertiary effluent) and sometimes rapid losses of performance due to membrane fouling. As a result, the initial design focus was on the attainment of high fluxes, and it was, therefore, necessary to pump the mixed liquor and its suspended solids at high cross-flow velocity at significant energy demand (of the order 10 kWh/m product) to reduce fouling. Because of the poor economics of the first-generation devices, they only found applications in niche areas with special needs such as isolated trailer parks or ski resorts.
The next breakthrough for the membrane bioreactor came in 1989 with the introduction of submerged membrane bioreactor configurations. Until then, membrane bioreactors were designed with a separation device located external to the reactor (side stream membrane bioreactors) and relied on high trans-membrane pressure to maintain filtration. The submerged configuration takes advantage of coarse bubble aeration to produce mixing and limit fouling. The energy demand of the submerged system can be up to 2 orders of magnitude lower than that of the side stream systems and submerged systems operate at a lower flux, demanding more membrane area. In submerged configurations, aeration is considered as one of the major parameters in process performance both hydraulic and biological. Aeration maintains solids in suspension, scours the membrane surface, and provides oxygen to the biomass, leading to better biodegradability and cell synthesis. Submerged membrane bioreactor systems became preferred to side stream configurations, especially for domestic wastewater treatment.
The next key steps in membrane bioreactor development were the acceptance of modest fluxes (25 percent or less of those in the first generation) and the idea to use two-phase (bubbly) flow to control fouling. The lower operating cost obtained with the submerged configuration along with the steady decrease in the membrane cost led to an exponential increase in membrane bioreactor plant installations from the mid-1990s. Since then, further improvements in membrane bioreactor design and operation have been introduced and incorporated into larger plants. While earlier devices were operated at solid retention times as high as 100 days with mixed liquor suspended solids up to 30 g/L, the recent trend is to apply lower solid retention times (around 10–20 days), resulting in more manageable suspended solids levels (10 to 15 g/L). Thanks to these new operating conditions, the oxygen transfer and the pumping cost in the reactors have tended to decrease and the overall maintenance has been simplified. There is now a range of membrane bioreactor systems available commercially, most of which use submerged membranes although some side stream modules are available; these side stream systems also use two-phase flow for fouling control. Typical hydraulic retention times range between 3 and 10 hours. For the most part, hollow fiber and flat sheet membrane configurations are utilized in membrane bioreactor applications.
Despite the more favorable energy usage of submerged membranes, there continued to be a market for the side stream configuration, particularly in smaller flow industrial applications. For ease of maintenance, side stream configurations can be installed on a lower level in a plant building, and thus membrane replacement can be undertaken without specialized lifting equipment. As a result, research and development has continued to improve the side stream configurations, and this has culminated in recent years with the development of low energy systems which incorporate more sophisticated control of the operating parameters coupled with periodic backwashes, which enable sustainable operation at energy usage as low as 0.3 kWh/m3 of product. | 1 | Applied and Interdisciplinary Chemistry |
In September researchers were able to give trichromatic vision to squirrel monkeys. In November 2009, researchers halted a fatal genetic disorder called adrenoleukodystrophy in two children using a lentivirus vector to deliver a functioning version of ABCD1, the gene that is mutated in the disorder. | 1 | Applied and Interdisciplinary Chemistry |
Particle size distribution can greatly affect the efficiency of any collection device.
Settling chambers will normally only collect very large particles, those that can be separated using sieve trays.
Centrifugal collectors will normally collect particles down to about 20 μm. Higher efficiency models can collect particles down to 10 μm.
Fabric filters are one of the most efficient and cost effective types of dust collectors available and can achieve a collection efficiency of more than 99% for very fine particles.
Wet scrubbers that use liquid are commonly known as wet scrubbers. In these systems, the scrubbing liquid (usually water) comes into contact with a gas stream containing dust particles. The greater the contact of the gas and liquid streams, the higher the dust removal efficiency.
Electrostatic precipitators use electrostatic forces to separate dust particles from exhaust gases. They can be very efficient at the collection of very fine particles.
Filter Press used for filtering liquids by cake filtration mechanism. The PSD plays an important part in the cake formation, cake resistance, and cake characteristics. The filterability of the liquid is determined largely by the size of the particles. | 0 | Theoretical and Fundamental Chemistry |
García Mancheño earned her bachelor's degree in 2001 from the Faculty of Sciences of the Autonomous University of Madrid in Madrid, Spain. She continued at the Autonomous University of Madrid to earn her Ph.D. in 2005 under the mentorship of Juan Carlos Carretero. She continued her training in organic chemistry as a postdoctoral researcher in the lab of Carsten Bolm at RWTH Aachen University in Aachen, Germany. She completed her habilitation at University of Münster mentored by Frank Glorius, and then worked in a temporary professorship at the University of Göttingen in the city of Göttingen, Germany before acquiring her first permanent faculty position. She was an assistant professor of organic chemistry at the University of Regensburg in Bavaria, Germany from 2013-2017. In 2017, García Mancheño became a professor of organic chemistry at the University of Münster, in Münster, North Rhine-Westphalia, Germany, where she also completed her habilitation. | 0 | Theoretical and Fundamental Chemistry |
A SSATM instrument is typically designed in a time-domain spectroscopy configuration in which a high power infrared laser beam is divided into two optical paths by a beamsplitter.
The first optical path often receives a greater fraction of the optical power of the laser to maximize the output power of generated THz light. THz light is often generated with a voltage-pulsed photoconductive antenna, collected with a hyper-hemispherical silicon lens, collimated using an off-axis parabolic mirror that is then passed through a THz polarizer, made circular by a THz quarter waveplate constructed of two planar mirrors and a right-angled high-resistivity silicon prism to form circularly polarized light. A second THz polarizer selects from the circularly polarized THz light the angle at which each measurement is made once the light reaches a sample located at a focal point of the beam and mounted in direct contact with an electro-optic crystal often made of either ZnTe or GaP.
The second optical path includes a retroreflector mirror mounted on a delay stage that adjusts the time-of-flight of the NIR beam to match the delay time, , of the THz light at the sample. The NIR beam is linearly polarized and chopped at a frequency suitable for detection, directed to the EO crystal to measure the change in its birefringence due to the degree of THz absorption by the sample. The NIR beam is reflected by the sample/EO crystal interface and directed to the detection module that often consists of an NIR quarter waveplate, a Wollaston prism that spatially selects perpendicular polarization states of the light toward two detectors in a balanced detector. The detected signal is a measure of the difference of the magnitude of the two perpendicular polarization states and corresponds to the degree of birefringence induced in the EO crystal by the THz light as-perturbed by the sample. | 0 | Theoretical and Fundamental Chemistry |
Half-metallic ferromagnets exhibit a metallic behavior in one spin channel and an insulating behavior in the other spin channel. The first example of Heusler half-metallic ferromagnets was first investigated by de Groot et al., with the case of NiMnSb. Half-metallicity leads to the full polarization of the conducting electrons. Half metallic ferromagnets are therefore promising for spintronics applications. | 1 | Applied and Interdisciplinary Chemistry |
In the process of bluing, an oxidizing chemical reaction on an iron surface selectively forms magnetite (FeO), the black oxide of iron (as opposed to rust, the red oxide of iron (FeO)). Black oxide provides some protection against corrosion if also treated with a water-displacing oil to reduce wetting and galvanic action. Bluing is often used with carbon steel and cast iron pans in conjunction with seasoning. | 0 | Theoretical and Fundamental Chemistry |
While most chloroplasts originate from that first set of endosymbiotic events, Paulinella chromatophora is an exception that acquired a photosynthetic cyanobacterial endosymbiont more recently. It is not clear whether that symbiont is closely related to the ancestral chloroplast of other eukaryotes. Being in the early stages of endosymbiosis, Paulinella chromatophora can offer some insights into how chloroplasts evolved. Paulinella cells contain one or two sausage-shaped blue-green photosynthesizing structures called chromatophores, descended from the cyanobacterium Synechococcus. Chromatophores cannot survive outside their host. Chromatophore DNA is about a million base pairs long, containing around 850 protein-encoding genes—far less than the three million base pair Synechococcus genome, but much larger than the approximately 150,000 base pair genome of the more assimilated chloroplast. Chromatophores have transferred much less of their DNA to the nucleus of their host. About 0.3–0.8% of the nuclear DNA in Paulinella is from the chromatophore, compared with 11–14% from the chloroplast in plants. | 0 | Theoretical and Fundamental Chemistry |
The fourth-century Chinese physician Ge Hongs book Zhouhou Beiji Fang () described Artemisia annua extract, called qinghao, as a treatment of malarial fever. Tu Youyou and her team were the first to investigate. In 1971 they found that their extract from the dried leaves (collected from Beijing) did not indicate any antimalarial activity. On careful reading of Ges description they changed their extraction method of using fresh leaves under low temperature. Ge explicitly describes the recipe as: "qinghao, one bunch, take two sheng [2 × 0.2 L] of water for soaking it, wring it out, take the juice, ingest it in its entirety". Following the findings of scientists at the Yunnan Institute of Pharmacology, they found that only the fresh plant specimen collected from Sichuan province would yield the active compound. They made the purified extract into tablets, which showed very low activity. They soon realized that the compound was very insoluble and made it in capsules instead. On 4 October 1971 they successfully treated malaria in experimental mice (infected with Plasmodium berghei) and monkeys (infected with Plasmodium cynomolgi) using the new extract.
In August 1972 they reported a clinical trial in which 21 malarial patients were cured. In 1973 the Yunnan scientists and those at the Shandong Institute of Pharmacology independently obtained the antimalarial compound in a crystalline form gave the name huanghaosu or huanghuahaosu, eventually renamed qinghaosu (yet later to be popularised as "artemisinin", after the botanical name). The same year Tu synthesized the compound dihydroartemisinin from the extract. This compound was more soluble and potent than the native compound. Other scientists subsequently synthesized other artemisinin derivatives, of which the most important are artemether and artesunate. All clinical trials by this time confirmed that artemisinins are more effective than the conventional antimalarial drugs, such as chloroquine and quinine. A group of scientists in Shanghai, including chemist Wu Yulin, determined artemisinin's chemical structure in 1975 and published it in 1977 when the secrecy rules lifted. The artemisinins became the most potent as well as the safest and most rapidly acting antimalarial drugs, recommended by the World Health Organization for the treatment of different types of malaria. | 1 | Applied and Interdisciplinary Chemistry |
Endohedral complexes He@C and Ne@C are prepared by pressurizing C to ca. 3 bar in a noble-gas atmosphere. Under these conditions about one out of every 650,000 C cages was doped with a helium atom.
The formation of endohedral complexes with helium, neon, argon, krypton and xenon as well as numerous adducts of the He@C compound was also demonstrated with pressures of 3 kbars and incorporation of up to 0.1% of the noble gases.
While noble gases are chemically very inert and commonly exist as individual atoms, this is not the case for nitrogen and phosphorus and so the formation of the endohedral complexes N@C, N@C and P@C is more surprising.
The nitrogen atom is in its electronic initial state (S) and is highly reactive. Nevertheless, N@C is sufficiently stable that exohedral derivatization from the mono- to the hexa adduct of the malonic acid ethyl ester is possible.
In these compounds no charge transfer of the nitrogen atom in the center to the carbon atoms of the cage takes place. Therefore, C-couplings, which are observed very easily with the endohedral metallofullerenes, could only be observed in the case of the N@C in a high resolution spectrum as shoulders of the central line.
The central atom in these endohedral complexes is located in the center of the cage. While other atomic traps require complex equipment, e.g. laser cooling or magnetic traps, endohedral fullerenes represent an atomic trap that is stable at room temperature and for an arbitrarily long time. Atomic or ion traps are of great interest since particles are present free from (significant) interaction with their environment, allowing unique quantum mechanical phenomena to be explored. For example, the compression of the atomic wave function as a consequence of the packing in the cage could be observed with ENDOR spectroscopy. The nitrogen atom can be used as a probe, in order to detect the smallest changes of the electronic structure of its environment.
Contrary to the metallo endohedral compounds, these complexes cannot be produced in an arc. Atoms are implanted in the fullerene starting material using gas discharge (nitrogen and phosphorus complexes) or by direct ion implantation. Alternatively, endohedral hydrogen fullerenes can be produced by opening and closing a fullerene by organic chemistry methods.
A recent example of endohedral fullerenes includes single molecules of water encapsulated in C.
Noble gas endofullerenes are predicted to exhibit unusual polarizability. Thus, calculated values of mean polarizability of Ng@C do not equal to the sum of polarizabilities of a fullerene cage and the trapped atom, i.e. exaltation of polarizability occurs.,. The sign of the Δα polarizability exaltation depends on the number of atoms in a fullerene molecule: for small fullerenes (), it is positive; for the larger ones (), it is negative (depression of polarizability). The following formula, describing the dependence of Δα on n, has been proposed: Δα = α(2e−1). It describes the DFT-calculated mean polarizabilities of Ng@C endofullerenes with sufficient accuracy. The calculated data allows using C fullerene as a Faraday cage, which isolates the encapsulated atom from the external electric field. The mentioned relations should be typical for the more complicated endohedral structures (e.g., C@C and giant fullerene-containing "onions" ). | 0 | Theoretical and Fundamental Chemistry |
In humans the distribution of PDE5A1 and PDE5A2 isoforms is the same and can be found in the brain, lung tissue, heart, liver, kidneys, bladder, prostate, urethra, penis, uterus and skeletal muscles. PDE5A2 is more common than PDE5A1. PDE5A3 is not as widespread as the other two isoforms, and is only found in smooth muscle tissues, it is found in the heart, bladder, prostate, urethra, penis and uterus, Exact distribution of PDE5A4 isoform was not found in the literature. PDE5 enzyme in humans has also been reported in platelets, gastrointestinal epithelial cells, Purkinje cells of cerebellum, corpus cavernosum, pancreas, placenta and colon, clitoral corpus cavernosum as well as vaginal smooth muscle and epithelium. | 1 | Applied and Interdisciplinary Chemistry |
When gamma radiation breaks DNA molecules, a cell may be able to repair the damaged genetic material, within limits. However, a study of Rothkamm and Lobrich has shown that this repair process works well after high-dose exposure but is much slower in the case of a low-dose exposure. | 0 | Theoretical and Fundamental Chemistry |
Alcohols have a long history of myriad uses. For simple mono-alcohols, which is the focus on this article, the following are most important industrial alcohols:
* methanol, mainly for the production of formaldehyde and as a fuel additive
* ethanol, mainly for alcoholic beverages, fuel additive, solvent
* 1-propanol, 1-butanol, and isobutyl alcohol for use as a solvent and precursor to solvents
* C6–C11 alcohols used for plasticizers, e.g. in polyvinylchloride
* fatty alcohol (C12–C18), precursors to detergents
Methanol is the most common industrial alcohol, with about 12 million tons/y produced in 1980. The combined capacity of the other alcohols is about the same, distributed roughly equally. | 0 | Theoretical and Fundamental Chemistry |
Splicing is dependent on the presence of the 7-methylguanosine cap. A defect in splicing can occur as a result of mutation(s) in the guanylyltransferase, which can inhibit enzyme activity, preventing the formation of the cap. However the severity of the effect is dependent on the guanylyltransferase mutation. Furthermore, the guanylyltransferase relieves transcriptional repression mediated by NELF. NELF together with DSIF prevents transcription elongation. Thus, mutations in the enzyme can affect transcription elongation. | 1 | Applied and Interdisciplinary Chemistry |
In colloidal and surface chemistry, the critical micelle concentration (CMC) is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system will form micelles.
The CMC is an important characteristic of a surfactant. Before reaching the CMC, the surface tension changes strongly with the concentration of the surfactant. After reaching the CMC, the surface tension remains relatively constant or changes with a lower slope. The value of the CMC for a given dispersant in a given medium depends on temperature, pressure, and (sometimes strongly) on the presence and concentration of other surface active substances and electrolytes. Micelles only form above critical micelle temperature.
For example, the value of CMC for sodium dodecyl sulfate in water (without other additives or salts) at 25 °C, atmospheric pressure, is 8x10 mol/L. | 0 | Theoretical and Fundamental Chemistry |
The most important industrial application is the nickel-catalyzed synthesis of adiponitrile () synthesis from buta-1,3-diene (). Adiponitrile is a precursor to hexamethylenediamine (), which is used for the production of certain kinds of Nylon. The DuPont ADN process to give adiponitrile is shown below:
This process consists of three steps: hydrocyanation of butadiene to a mixture of 2-methyl-butene-3-nitrile (2M3BM) and pentene-3-nitrile (3PN), an isomerization step from 2M3BM (not desired) to 3PN and a second hydrocyanation (aided by a Lewis acid cocatalyst such as aluminium trichloride or triphenylboron) to adiponitrile. | 0 | Theoretical and Fundamental Chemistry |
The hardening of the protein component of insect cuticle has been shown to be due to the tanning action of an agent produced by oxidation of a phenolic substance forming sclerotin. In the analogous hardening of the cockroach ootheca, the phenolic substance concerned is 3:4-dihydroxybenzoic acid (protocatechuic acid).
Acetosyringone is produced by the male leaffooted bug (Leptoglossus phyllopus) and used in its communication system. Guaiacol is produced in the gut of Desert locusts, Schistocerca gregaria, by the breakdown of plant material. This process is undertaken by the gut bacterium Pantoea agglomerans. Guaiacol is one of the main components of the pheromones that cause locust swarming. Orcinol has been detected in the "toxic glue" of the ant species Camponotus saundersi. Rhynchophorus ferrugineus (red palm weevil) use 2-methoxy-4-vinylphenol for chemical signaling (pheromones). Other simple and complex phenols can be found in eusocial ants (such as Crematogaster) as components of venom. | 0 | Theoretical and Fundamental Chemistry |
The Smoluchowski factor, also known as von Smoluchowski's f-factor is related to inter-particle interactions. It is named after Marian Smoluchowski. | 0 | Theoretical and Fundamental Chemistry |
Vitamin D (cholecalciferol) is produced industrially by exposing 7-dehydrocholesterol to UVB and UVC light, followed by purification. The 7-dehydrocholesterol is a natural substance in fish organs, especially the liver, in wool grease (lanolin) from sheep and in some plants, like lichen (Cladonia rangiferina). Vitamin D (ergocalciferol) is produced in a similar way using ergosterol from yeast or mushrooms as a starting material. | 1 | Applied and Interdisciplinary Chemistry |
A defoliant is any herbicidal chemical sprayed or dusted on plants to cause their leaves to fall off. Defoliants are widely used for the selective removal of weeds in managing croplands and lawns. Worldwide use of defoliants, along with the development of other herbicides and pesticides, allowed for the Green Revolution, an increase in agricultural production in mid-20th century. Defoliants have also been used in warfare as a means to deprive an enemy of food crops and/or hiding cover, most notably by the United Kingdom during the Malayan Emergency and the United States in the Vietnam War. Defoliants were also used by Indonesian forces in various internal security operations. | 1 | Applied and Interdisciplinary Chemistry |
xDNA has many applications in chemical and biological research, including expanding upon applications of natural DNA, such as scaffolding. In order to create self-assembling nanostructures, a scaffold is needed as a sort of trellis to support the growth. DNA has been used as a means to this end in the past, but expanded scaffolds make larger scaffolds for more complex self-assembly an option. xDNAs electrical conduction properties also make it a prime candidate as a molecular wire, as its π-π interactions help it efficiently conduct electricity. Its 8-letter alphabet (A, T, C, G, xA, xT, xC, xG) gives it the potential to store 2 times more states per sequence than DNA, where n' is the number of bases in the sequence. For example, combining 6 nucleotides of with B-DNA yields 4096 possible sequences, whereas a combination of the same number of nucleotides created with xDNA yields 262,144 possible sequences. Additionally, xDNA can be used as a fluorescent probe at enzyme active sites, as was its original application by Leonard et al.
xDNA has also been applied to the study of protein-DNA interactions. Due to xDNA's natural fluorescing properties, it can easily be visualized in both lab and living conditions. xDNA is becoming more easy to create and oligomerize, and its high-affinity binding to complementary DNA and RNA sequences means that it can not only help locate these sequences floating around in the cell, but also when they are already interacting with other structures within the cell. xDNA also has potential applications in assays that employ TdT as it may improve reporters, and can be used as an affinity tag for interstrand bonding. | 1 | Applied and Interdisciplinary Chemistry |
Sex pheromones are pheromones released by an organism to attract an individual of the same species, encourage them to mate with them, or perform some other function closely related with sexual reproduction.
Sex pheromones specifically focus on indicating females for breeding, attracting the opposite sex, and conveying information on species, age, sex and genotype. Non-volatile pheromones, or cuticular contact pheromones, are more closely related to social insects as they are usually detected by direct contact with chemoreceptors on the antennae or feet of insects.
Insect sex pheromones have found uses in monitoring and trapping of pest insects. | 1 | Applied and Interdisciplinary Chemistry |
In oral rehydration therapy, electrolyte drinks containing sodium and potassium salts replenish the body's water and electrolyte concentrations after dehydration caused by exercise, excessive alcohol consumption, diaphoresis (heavy sweating), diarrhea, vomiting, intoxication or starvation. Athletes exercising in extreme conditions (for three or more hours continuously, e.g. a marathon or triathlon) who do not consume electrolytes risk dehydration (or hyponatremia).
A home-made electrolyte drink can be made by using water, sugar and salt in precise proportions. It is important to include glucose (sugar) to utilise the co-transport mechanism of sodium and glucose. Commercial preparations are also available for both human and veterinary use.
Electrolytes are commonly found in fruit juices, sports drinks, milk, nuts, and many fruits and vegetables (whole or in juice form) (e.g., potatoes, avocados). | 0 | Theoretical and Fundamental Chemistry |
This term is used in chemistry contexts, e.g., for a chiral molecule lacking an asymmetric carbon atom, but possessing two non-coplanar rings that are each dissymmetric and which cannot easily rotate about the chemical bond connecting them: 2,2-dimethylbiphenyl is perhaps the simplest example of this case. Planar chirality is also exhibited by molecules like (E')-cyclooctene, some di- or poly-substituted metallocenes, and certain monosubstituted paracyclophanes. Nature rarely provides planar chiral molecules, cavicularin being an exception. | 0 | Theoretical and Fundamental Chemistry |
Traditional CRP measurement only detected CRP in the range of 10 to 1,000 mg/L, whereas high sensitivity CRP (hs-CRP) detects CRP in the range of 0.5 to 10 mg/L. hs-CRP can detect cardiovascular disease risk when in excess of 3 mg/L, whereas below 1 mg/L would be low risk. Traditional CRP measurement is faster and less costly than hs-CRP, and can be adequate for some applications, such as monitoring hemodialysis patients. | 1 | Applied and Interdisciplinary Chemistry |
Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body, and have not spread to other parts. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. A physician who practices in this subspecialty is a radiation oncologist.
Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of cancerous tissue leading to cellular death. To spare normal tissues (such as skin or organs which radiation must pass through to treat the tumor), shaped radiation beams are aimed from several angles of exposure to intersect at the tumor, providing a much larger absorbed dose there than in the surrounding healthy tissue. Besides the tumor itself, the radiation fields may also include the draining lymph nodes if they are clinically or radiologically involved with the tumor, or if there is thought to be a risk of subclinical malignant spread. It is necessary to include a margin of normal tissue around the tumor to allow for uncertainties in daily set-up and internal tumor motion. These uncertainties can be caused by internal movement (for example, respiration and bladder filling) and movement of external skin marks relative to the tumor position.
Radiation oncology is the medical specialty concerned with prescribing radiation, and is distinct from radiology, the use of radiation in medical imaging and diagnosis. Radiation may be prescribed by a radiation oncologist with intent to cure or for adjuvant therapy. It may also be used as palliative treatment (where cure is not possible and the aim is for local disease control or symptomatic relief) or as therapeutic treatment (where the therapy has survival benefit and can be curative). It is also common to combine radiation therapy with surgery, chemotherapy, hormone therapy, immunotherapy or some mixture of the four. Most common cancer types can be treated with radiation therapy in some way.
The precise treatment intent (curative, adjuvant, neoadjuvant therapeutic, or palliative) will depend on the tumor type, location, and stage, as well as the general health of the patient. Total body irradiation (TBI) is a radiation therapy technique used to prepare the body to receive a bone marrow transplant. Brachytherapy, in which a radioactive source is placed inside or next to the area requiring treatment, is another form of radiation therapy that minimizes exposure to healthy tissue during procedures to treat cancers of the breast, prostate, and other organs. Radiation therapy has several applications in non-malignant conditions, such as the treatment of trigeminal neuralgia, acoustic neuromas, severe thyroid eye disease, pterygium, pigmented villonodular synovitis, and prevention of keloid scar growth, vascular restenosis, and heterotopic ossification. The use of radiation therapy in non-malignant conditions is limited partly by worries about the risk of radiation-induced cancers. | 0 | Theoretical and Fundamental Chemistry |
Electromigration is the transport of material caused by the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms. The effect is important in applications where high direct current densities are used, such as in microelectronics and related structures. As the structure size in electronics such as integrated circuits (ICs) decreases, the practical significance of this effect increases. | 0 | Theoretical and Fundamental Chemistry |
A membrane brings many new elements for the separation. Amino acids has been separated by perstraction. Membranes did not only separate extractants and the primary solution but also were selective for amino acids. Charged membranes were used. So they selected amino acids by pKa. Besides the selectivity of a membrane is affected by its thickness, pore diameter and charge potential. The bigger pore is, the better amino acids permeate the membrane. The higher charge potential is, the bigger electrostatic rejection effects are. The thinner membrane, the less it is selective. | 0 | Theoretical and Fundamental Chemistry |
SRAS++ utilises SRAS imaging to provide the raw measurement of single grain velocity surfaces, this is input to a novel inverse solver that mitigates the problem of the inversion being very ill-conditioned, by simultaneously solving for multiple uniquely orientated grains at once in a brute-force approach. This allows simultaneous determination of the elastic constants and crystallographic orientation. Furthermore, this technique has the potential to work on polycrystalline materials with minimal preparation and is capable of high accuracy, with the potential to realise errors in the determination of elastic constants values of less than 1 GPa. | 0 | Theoretical and Fundamental Chemistry |
The journal is abstracted and indexed in:
According to the Journal Citation Reports, the journal has a 2020 impact factor of 0.946. | 0 | Theoretical and Fundamental Chemistry |
The organization is led by a steering committee elected from its members. The steering committee represents the EBF in international forums and sets the agenda for the closed and open meetings. | 0 | Theoretical and Fundamental Chemistry |
* Protein NMR Spectroscopy : Principles and Practice (1995) John Cavanagh, Wayne J. Fairbrother, Arthur G. Palmer III, Nicholas J. Skelton, Academic Press | 0 | Theoretical and Fundamental Chemistry |
In chemistry, a cavitand is a container-shaped molecule. The cavity of the cavitand allows it to engage in host–guest chemistry with guest molecules of a complementary shape and size. The original definition proposed by Cram includes many classes of molecules: cyclodextrins, calixarenes, pillararenes and cucurbiturils. However, modern usage in the field of supramolecular chemistry specifically refers to cavitands formed on a resorcinarene scaffold by bridging adjacent phenolic units. The simplest bridging unit is methylene (), although dimethylene (), trimethylene (), benzal, xylyl, pyridyl, 2,3-disubstituted-quinoxaline, o-dinitrobenzyl, dialkylsilylene, and phosphonates are known. Cavitands that have an extended aromatic bridging unit, or an extended cavity containing 3 rows of aromatic rings are referred to as deep-cavity cavitands and have broad applications in host-guest chemistry. These types of cavitands were extensively investigated by Rebek, and Gibb, among others. | 0 | Theoretical and Fundamental Chemistry |
In terms of dosage equivalence, norethisterone and NETA are typically used at respective dosages of 0.35 mg/day and 0.6 mg/day as progestogen-only contraceptives, and at respective dosages of 0.5–1 mg/day and 1–1.5 mg/day in combination with ethinylestradiol in combined oral contraceptives. Conversely, the two drugs have been used at about the same dosages in menopausal hormone therapy for the treatment of menopausal symptoms. NETA is of about 12% higher molecular weight than norethisterone due to the presence of its C17β acetate ester. Micronization of NETA has been found to increase its potency by several-fold in animals and women. The endometrial transformation dosage of micronized NETA per cycle is 12 to 14 mg, whereas that for non-micronized NETA is 30 to 60 mg. | 1 | Applied and Interdisciplinary Chemistry |
Pulse labelling is a biochemistry technique of identifying the presence of a target molecule by labeling a sample with a radioactive compound. This is mainly done to identify the stage at which the messenger RNA is being produced in a cell. | 1 | Applied and Interdisciplinary Chemistry |
Spectroscopic photo-reflectance employs a broad band probe light source, which may cover wavelengths from the infrared to the ultraviolet. By fitting spectroscopic photo-reflectance data with the conventional third derivative functional form, a comprehensive set of interband transition energies, amplitudes, and widths may be obtained, providing an essentially complete characterization of the electronic properties of the sample of interest. However, owing to the need to keep the probe light intensity to a minimum and to the practical necessity of phase-locked detection, spectroscopic photo-reflectance measurements must be made sequentially, i.e. probe one wavelength at a time.
This constraint limits the speed of spectroscopic photo-reflectance measurements, and coupled with the need for a careful fit procedure, renders spectroscopic photo-reflectance more suitable for analytical applications. Conversely, laser photo-reflectance employs a monochromatic light source, and hence is well suited for industrial applications. Moreover, in commonly encountered situations, the coherent wavefront of laser probe beam may be used to isolate the refractive component of the photo-reflectance signal, greatly simplifying the data analysis. | 0 | Theoretical and Fundamental Chemistry |
DEAD is toxic, shock and light sensitive; it can violently explode when its undiluted form is heated above 100 °C. Shipment by air of pure diethyl azodicarboxylate is prohibited in the United States and is carried out in solution, typically about 40% DEAD in toluene. Alternatively, DEAD is transported and stored on 100–300 mesh polystyrene particles at a concentration of about 1 mmol/g. The time-weighed average threshold limit value for exposure to DEAD over a typical 40-hour working week is 50 parts per million; that is, DEAD is half as toxic as, e.g., carbon monoxide. Safety hazards have resulted in rapid decline of DEAD usage and replacement with DIAD and other similar compounds. | 0 | Theoretical and Fundamental Chemistry |
RT is the product of the molar gas constant, R, and the temperature, T. This product is used in physics and chemistry as a scaling factor for energy values in macroscopic scale (sometimes it is used as a pseudo-unit of energy), as many processes and phenomena depend not on the energy alone, but on the ratio of energy and RT, i.e. E/RT. The SI units for RT are joules per mole (J/mol).
It differs from kT only by a factor of the Avogadro constant, N. Its dimension is energy or MLT, expressed in SI units as joules (J):
:kT = RT/N | 0 | Theoretical and Fundamental Chemistry |
Researchers at Boehringer Ingelheim also used the publicized information about the NAPAP-fIIa crystal structure, starting with the NAPAP structure that led to the discovery of dabigatran, which is a very polar compound and therefore not orally active. By masking the amidinium moiety as a carbamate-ester and turning the carboxylate into an ester they were able to make a prodrug called dabigatran etexilate, a highly lipophilic, gastrointestinally absorbed and orally bioavailable double prodrug such as ximelagatran, with the plasma half-life of approximately 12 hours. Dabigatran etexilate is rapidly absorbed, it lacks interaction with cytochrome P450 enzymes and with other food and drugs, there is no need for routine monitoring and it has a broad therapeutic index and a fixed-dose administration, which is excellent safety compared with warfarin. Unlike ximelagatran, a long-term treatment of dabigatran etexilate has not been linked with hepatic toxicity, seeing as how the drug is predominantly eliminated (>80%) by the kidneys. Dabigatran etexilate was approved in Canada and Europe in 2008 for the prevention of VTE in patients undergoing hip- and knee surgery. In October 2010 the US FDA approved dabigatran etexilate for the prevention of stroke in patients with atrial fibrillation (AF). Many pharmaceutical companies have attempted to develop orally bioavailable DTI drugs but dabigatran etexilate is the only one to reach the market.
In a 2012 meta-analysis dabigatran was associated with increased risk of myocardial infarction (MI) or ACS when tested against different controls in a broad spectrum of patients. | 1 | Applied and Interdisciplinary Chemistry |
The attenuation constant for an electromagnetic wave at normal incidence on a material is also proportional to the imaginary part of the materials refractive index n'. Using the above definition of (based on intensity) the following relationship holds:
where denotes the complex index of refraction, is the radian frequency of the radiation, c is the speed of light in vacuum and is the wavelength. Note that is very much a function of frequency, as is its imaginary part which is often not mentioned (it is essentially zero for transparent dielectrics). The complex refractive index of metals is also infrequently mentioned but has the same significance, leading to a penetration depth (or skin depth ) accurately given by a formula which is valid up to microwave frequencies.
Relationships between these and other ways of specifying the decay of an electromagnetic field can be expressed by mathematical descriptions of opacity.
This is only specifying the decay of the field which may be due to absorption of the electromagnetic energy in a lossy medium or may simply describe the penetration of the field in a medium where no loss occurs (or a combination of the two). For instance, a hypothetical substance may have a complex index of refraction . A wave will enter that medium without significant reflection and will be totally absorbed in the medium with a penetration depth (in field strength) of , where is the vacuum wavelength. A different hypothetical material with a complex index of refraction will also have a penetration depth of 16 wavelengths, however in this case the wave will be perfectly reflected from the material! No actual absorption of the radiation takes place, however the electric and magnetic fields extend well into the substance. In either case the penetration depth is found directly from the imaginary part of the material's refractive index as is detailed above. | 0 | Theoretical and Fundamental Chemistry |
As coral reefs decay, their residents will have to adapt or find new habitats on which to rely. Ocean acidification threatens the fundamental chemical balance of our oceans, creating conditions that eat away at essential minerals like calcium carbonate. A lack of aragonite and decreasing pH levels in ocean water makes it harder for calcifying organisms such as oysters, clams, lobsters, shrimp and coral reefs to build their shells and exoskeletons. Organisms have been found to be more sensitive to the effects of ocean acidification in early, larval or planktonic stages. Larval health and settlement of both calcifying and non-calcifying organisms can be harmed by ocean acidification.
A study published in the journal Global Change Biology developed a model for predicting the vulnerability of sharks and sting rays to climate change in the Great Barrier Reef. It was found that 30 of the 133 species were identified as moderately or highly vulnerable to climate change with the most vulnerable species being the freshwater whipray, porcupine ray, speartooth shark, and sawfish. Increasing temperature is also affecting the behavior and fitness of may reef species such as the common coral trout, a very important fish in sustaining the health of coral reefs. Not only can ocean acidification affect habitat and development, but it can also affect how organisms view predators and conspecifics. Studies on the effects of ocean acidification have not been performed on long enough time scales to see if organisms can adapt to these conditions. However, ocean acidification is predicted to occur at a rate that evolution cannot match. | 0 | Theoretical and Fundamental Chemistry |
Under euxinic conditions, some trace elements such as Mo, U, V, Cd, Cu, Tl, Ni, Sb, and Zn, become insoluble. This means that euxinic sediments would contain more of the solid form of these elements than the background seawater. For example, Molybdenum and other trace metals become insoluble in anoxic and sulfidic conditions, so over time the seawater becomes depleted of trace metals under conditions of persistent euxinia, and preserved sediments are relatively enriched with molybdenum and other trace elements. | 0 | Theoretical and Fundamental Chemistry |
Nucleophilic substitution at sp centres can proceed by the stereospecific S2 mechanism, causing only inversion, or by the non-specific S1 mechanism, the outcome of which can show a modest selectivity for inversion, depending on the reactants and the reaction conditions to which the mechanism does not refer. The choice of mechanism adopted by a particular reactant combination depends on other factors (steric access to the reaction centre in the substrate, nucleophile, solvent, temperature).
For example, tertiary centres react almost exclusively by the S1 mechanism whereas primary centres (except neopentyl centres) react almost exclusively by the S2 mechanism. When a nucleophilic substitution results in incomplete inversion, it is because of a competition between the two mechanisms, as often occurs at secondary centres, or because of double inversion (as when iodide is the nucleophile).
The addition of singlet carbenes to alkenes is stereospecific in that the geometry of the alkene is preserved in the product. For example, dibromocarbene and cis-2-butene yield cis-2,3-dimethyl-1,1-dibromocyclopropane, whereas the trans isomer exclusively yields the trans cyclopropane.
This addition remains stereospecific even if the starting alkene is not isomerically pure, as the products stereochemistry will match the reactants.
The disrotatory ring closing reaction of conjugated trienes is stereospecific in that isomeric reactants will give isomeric products. For example, trans,cis,trans-2,4,6-octatriene gives cis-dimethylcyclohexadiene, whereas the trans,cis,cis reactant isomer gives the trans product and the trans,trans,trans reactant isomer does not react in this manner. | 0 | Theoretical and Fundamental Chemistry |
*[https://www.bgc-jena.mpg.de/paleo-biogeochem/HallmannLab_%40_MPI-BGC_Jena/Home.html Organic Paleobiogeochemistry] (Christian Hallmann)
*[https://www.bgc-jena.mpg.de/index.php/BTM/Home?jahr=&id=&gruppe=KLEI&limit=limit Biospheric Theory and Modelling] (Axel Kleidon)
*[https://www.bgc-jena.mpg.de/bgp/index.php/EmeritusEDS/EmeritusEDS Carbon Balance and Ecosystem Research] (Ernst-Detlef Schulze)
*[https://www.bgc-jena.mpg.de/functionalbiogeography/index.php/Main/HomePage Functional Biogeography] (Christian Wirth & Jens Kattge) | 0 | Theoretical and Fundamental Chemistry |
Decantation can be used to separate immiscible liquids that have different densities. For example, when a mixture of water and oil is present in a beaker, after some time a distinct layer between the two liquids is formed, with the oil layer floating on top of the water layer. This separation can be done by pouring oil out of the container, leaving water behind. Generally, this technique gives an incomplete separation as it is difficult to pour off all of the top layer without pouring out some parts of the bottom layer.
A separatory funnel is an alternative apparatus for separating liquid layers. It has a valve at the bottom to allow draining off the bottom layer. It can give better separation between the two liquids. | 0 | Theoretical and Fundamental Chemistry |
* Furaneol (strawberry)
* 1-Hexanol (herbaceous, woody)
* cis-3-Hexen-1-ol (fresh cut grass)
* Menthol (peppermint) | 0 | Theoretical and Fundamental Chemistry |
Faulds studied forensic and analytical science at the University of Strathclyde, graduating with a BSc in 1998. She remained at Strathclyde for her doctoral studies and in 2003 received her PhD for research on the detection of drugs of substance abuse using surface-enhanced Raman spectroscopy (SERS). | 0 | Theoretical and Fundamental Chemistry |
The European Association of Geochemistry gives the following awards:
* The Urey Medal (European Association of Geochemistry) for outstanding contributions advancing geochemistry over a career.
* The Science Innovation Award for an important and innovative breakthrough in geochemistry.
* The Houtermans Award for exceptional contributions to geochemistry made by scientists under 35 years old.
* Geochemical Fellows – Awarded annually by the Geochemical Society and the European Association of Geochemistry to outstanding scientists who have, over some years, made a major contribution to the field of geochemistry. | 0 | Theoretical and Fundamental Chemistry |
Lignite-tar creosote is produced from lignite rather than bituminous coal, and varies considerably from coal-tar creosote. Also called "lignite oil", it has a very high content of tar acids, and has been used to increase the tar acids in normal creosote when necessary. When it has been produced, it has generally been applied in mixtures with coal-tar creosote or petroleum. Its effectiveness when used alone has not been established. In an experiment with southern yellow pine fence posts in Mississippi, straight lignite-tar creosote was giving good results after about 27 years exposure, although not as good as the standard coal-tar creosote used in the same situation. | 0 | Theoretical and Fundamental Chemistry |
Borate ions occur, alone or with other anions, in many borate and borosilicate minerals such as borax, boracite, ulexite (boronatrocalcite) and colemanite. Borates also occur in seawater, where they make an important contribution to the absorption of low frequency sound in seawater.
Borates also occur in plants, including almost all fruits. | 0 | Theoretical and Fundamental Chemistry |
James A. Shapiro argues that a superset of these examples should be classified as natural genetic engineering and are sufficient to falsify the central dogma. While Shapiro has received a respectful hearing for his view, his critics have not been convinced that his reading of the central dogma is in line with what Crick intended. | 1 | Applied and Interdisciplinary Chemistry |
Ionic imprinting, which involves metal ions, serves as an approach to enhance template molecule and functional monomer interaction in water. Typically, metal ions serve as a mediator during the imprinting process. Cross-linking polymers that are in the presence of a metal ion will form a matrix that is capable of metal binding. Metal ions can also mediate molecular imprinting by binding to a range of functional monomers, where ligands donate electrons to the outermost orbital of the metal ion. In addition to mediating imprinting, metal ions can be utilized in the direct imprinting. For example, a metal ion can serve as the template for the imprinting process. | 0 | Theoretical and Fundamental Chemistry |
Technetium-99 (Tc) is an isotope of technetium which decays with a half-life of 211,000 years to stable ruthenium-99, emitting beta particles, but no gamma rays. It is the most significant long-lived fission product of uranium fission, producing the largest fraction of the total long-lived radiation emissions of nuclear waste. Technetium-99 has a fission product yield of 6.0507% for thermal neutron fission of uranium-235.
The metastable technetium-99m (Tc) is a short-lived (half-life about 6 hours) nuclear isomer used in nuclear medicine, produced from molybdenum-99. It decays by isomeric transition to technetium-99, a desirable characteristic, since the very long half-life and type of decay of technetium-99 imposes little further radiation burden on the body. | 0 | Theoretical and Fundamental Chemistry |
The pharmaceutical company Eli Lilly has formalized collaborative efforts with various 3rd parties aimed at conducting phenotypic screening of selected small molecules. | 1 | Applied and Interdisciplinary Chemistry |
Critical fission reactors are the most common type of nuclear reactor. In a critical fission reactor, neutrons produced by fission of fuel atoms are used to induce yet more fissions, to sustain a controllable amount of energy release. Devices that produce engineered but non-self-sustaining fission reactions are subcritical fission reactors. Such devices use radioactive decay or particle accelerators to trigger fissions.
Critical fission reactors are built for three primary purposes, which typically involve different engineering trade-offs to take advantage of either the heat or the neutrons produced by the fission chain reaction:
*power reactors are intended to produce heat for nuclear power, either as part of a generating station or a local power system such as a nuclear submarine.
*research reactors are intended to produce neutrons and/or activate radioactive sources for scientific, medical, engineering, or other research purposes.
*breeder reactors are intended to produce nuclear fuels in bulk from more abundant isotopes. The better known fast breeder reactor makes Pu (a nuclear fuel) from the naturally very abundant U (not a nuclear fuel). Thermal breeder reactors previously tested using Th to breed the fissile isotope U (thorium fuel cycle) continue to be studied and developed.
While, in principle, all fission reactors can act in all three capacities, in practice the tasks lead to conflicting engineering goals and most reactors have been built with only one of the above tasks in mind. (There are several early counter-examples, such as the Hanford N reactor, now decommissioned).
As of 2019, the 448 nuclear power plants worldwide provided a capacity of 398 GWE, with about 85% being light-water cooled reactors such as pressurized water reactors or boiling water reactors. Energy from fission is transmitted through conduction or convection to the nuclear reactor coolant, then to a heat exchanger, and the resultant generated steam is used to drive a turbine or generator. | 0 | Theoretical and Fundamental Chemistry |
Sodium orthovanadate is the inorganic compound with the chemical formula . It forms a dihydrate . Sodium orthovanadate is a salt of the oxyanion. It is a colorless, water-soluble solid. | 0 | Theoretical and Fundamental Chemistry |
Nucleotides can be synthesized by a variety of means, both in vitro and in vivo.
In vitro, protecting groups may be used during laboratory production of nucleotides. A purified nucleoside is protected to create a phosphoramidite, which can then be used to obtain analogues not found in nature and/or to synthesize an oligonucleotide.
In vivo, nucleotides can be synthesized de novo or recycled through salvage pathways. The components used in de novo nucleotide synthesis are derived from biosynthetic precursors of carbohydrate and amino acid metabolism, and from ammonia and carbon dioxide. Recently it has been also demonstrated that cellular bicarbonate metabolism can be regulated by mTORC1 signaling. The liver is the major organ of de novo synthesis of all four nucleotides. De novo synthesis of pyrimidines and purines follows two different pathways. Pyrimidines are synthesized first from aspartate and carbamoyl-phosphate in the cytoplasm to the common precursor ring structure orotic acid, onto which a phosphorylated ribosyl unit is covalently linked. Purines, however, are first synthesized from the sugar template onto which the ring synthesis occurs. For reference, the syntheses of the purine and pyrimidine nucleotides are carried out by several enzymes in the cytoplasm of the cell, not within a specific organelle. Nucleotides undergo breakdown such that useful parts can be reused in synthesis reactions to create new nucleotides. | 1 | Applied and Interdisciplinary Chemistry |
The molar ionic strength, I, of a solution is a function of the concentration of all ions present in that solution.
where one half is because we are including both cations and anions, c is the molar concentration of ion i (M, mol/L), z is the charge number of that ion, and the sum is taken over all ions in the solution. For a 1:1 electrolyte such as sodium chloride, where each ion is singly-charged, the ionic strength is equal to the concentration. For the electrolyte MgSO, however, each ion is doubly-charged, leading to an ionic strength that is four times higher than an equivalent concentration of sodium chloride:
Generally multivalent ions contribute strongly to the ionic strength. | 0 | Theoretical and Fundamental Chemistry |
Opening the vector product brackets in the Bloch equations leads to:
The above form is further simplified assuming
where i = . After some algebra one obtains:
where
is the complex conjugate of M. The real and imaginary parts of M correspond to M and M respectively.
M is sometimes called transverse nuclear magnetization. | 0 | Theoretical and Fundamental Chemistry |
Circle-Throw Vibrating Equipment is a shaker or a series of shakers as to where the drive causes the whole structure to move. The structure extends to a maximum throw or length and then contracts to a base state. A pattern of springs are situated below the structure to where there is vibration and shock absorption as the structure returns to the base state.
This type of equipment is used for very large particles, sizes that range from pebble size on up to boulder size material. It is also designed for high volume output. As a scalper, this shaker will allow oversize material to pass over and fall into a crusher such a cone crusher, jaw crusher, or hammer mill. The material that passes the screen by-passes the crusher and is conveyed and combined with the crush material.
Also this equipment is used in washing processes, as material passes under spray bars, finer material and foreign material is washed through the screen. This is one example of wet screening. | 1 | Applied and Interdisciplinary Chemistry |
Setting up for transcription in mammals is regulated by many cis-regulatory elements, including core promoter and promoter-proximal elements that are located near the transcription start sites of genes. Core promoters combined with general transcription factors are sufficient to direct transcription initiation, but generally have low basal activity. Other important cis-regulatory modules are localized in DNA regions that are distant from the transcription start sites. These include enhancers, silencers, insulators and tethering elements. Among this constellation of elements, enhancers and their associated transcription factors have a leading role in the initiation of gene transcription. An enhancer localized in a DNA region distant from the promoter of a gene can have a very large effect on gene transcription, with some genes undergoing up to 100-fold increased transcription due to an activated enhancer.
Enhancers are regions of the genome that are major gene-regulatory elements. Enhancers control cell-type-specific gene transcription programs, most often by looping through long distances to come in physical proximity with the promoters of their target genes. While there are hundreds of thousands of enhancer DNA regions, for a particular type of tissue only specific enhancers are brought into proximity with the promoters that they regulate. In a study of brain cortical neurons, 24,937 loops were found, bringing enhancers to their target promoters. Multiple enhancers, each often at tens or hundred of thousands of nucleotides distant from their target genes, loop to their target gene promoters and can coordinate with each other to control transcription of their common target gene.
The schematic illustration in this section shows an enhancer looping around to come into close physical proximity with the promoter of a target gene. The loop is stabilized by a dimer of a connector protein (e.g. dimer of CTCF or YY1), with one member of the dimer anchored to its binding motif on the enhancer and the other member anchored to its binding motif on the promoter (represented by the red zigzags in the illustration). Several cell function specific transcription factors (there are about 1,600 transcription factors in a human cell) generally bind to specific motifs on an enhancer and a small combination of these enhancer-bound transcription factors, when brought close to a promoter by a DNA loop, govern level of transcription of the target gene. Mediator (a complex usually consisting of about 26 proteins in an interacting structure) communicates regulatory signals from enhancer DNA-bound transcription factors directly to the RNA polymerase II (pol II) enzyme bound to the promoter.
Enhancers, when active, are generally transcribed from both strands of DNA with RNA polymerases acting in two different directions, producing two enhancer RNAs (eRNAs) as illustrated in the Figure. An inactive enhancer may be bound by an inactive transcription factor. Phosphorylation of the transcription factor may activate it and that activated transcription factor may then activate the enhancer to which it is bound (see small red star representing phosphorylation of transcription factor bound to enhancer in the illustration). An activated enhancer begins transcription of its RNA before activating transcription of messenger RNA from its target gene. | 1 | Applied and Interdisciplinary Chemistry |
The high stereospecificity and stereoselectivity inherent in many TMM cycloaddition reactions is a significant advantage; for instance, the trans ring junction in TMM cycloaddition adduct 2 was carried through in a synthesis of (+)-brefeldin A. | 0 | Theoretical and Fundamental Chemistry |
Prehistoric man inhabited the Portlethen Moss area as evidenced by well preserved Iron Age stone circles and other excavated artifacts nearby. Obviously only the outcrops and ridge areas would have been habitable, but the desirability of primitive habitation would have been enhanced by proximity to the sea and natural defensive protection of the moss to impede intruders. From Tacitus accounts of the Roman general Agricola, it is known that the Romans were daunted by Portlethen Moss, Netherley Red Moss, Cookney Moss and other local bogs that hindered travel. This is also evidenced by the Roman Camp of Raedykes having been established immediately south of this cluster of mosses; the Romans not being able to progress further north, turned inland toward Netherley.The Portlethen Moss is near the Grampian Mountains.
The ancient Causey Mounth passage specifically connected the Bridge of Dee to the town of Stonehaven. This route was used to access the historic meeting of the Covenanters at Muchalls Castle in the year 1638 AD as they opposed the Bishops of Aberdeen. The route was also that taken by the William Keith, 7th Earl Marischal and James Graham, 1st Marquess of Montrose when they led a Covenanter army of 9000 men in the biggest battle of the Bishops' Wars in 1639
Further to the east of Portlethen Moss lie three original coastal fishing villages: Findon, Portlethen Village and Downies. In the period 1960 to 2005, Portlethen has developed as a dormitory town to Aberdeen and a location for retail superstores. | 1 | Applied and Interdisciplinary Chemistry |
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