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The premise behind these skimmers is that a high pressure pump combined with a venturi, can be used to introduce the bubbles into the water stream. The tank water is pumped through the venturi, in which fine bubbles are introduced via pressure differential, then enters the skimmer body. This method was popular due to its compact size and high efficiency for the time but venturi designs are now outdated and surpassed by more efficient needle-wheel designs. | 0 | Theoretical and Fundamental Chemistry |
The collective–amoeboid transition (CMT) is a process by which collective multicellular groups dissociate into amoeboid single cells following the down-regulation of integrins. CMTs contrast with epithelial–mesenchymal transitions (EMT) which occur following a loss of E-cadherin. Like EMTs, CATs are involved in the invasion of tumor cells into surrounding tissues, with amoeboid movement more likely to occur in soft extracellular matrix (ECM) and mesenchymal movement in stiff ECM. Although once differentiated, cells typically do not change their migration mode, EMTs and CMTs are highly plastic with cells capable of interconverting between them depending on intracelluar regulatory signals and the surrounding ECM.
CATs are the least common transition type in invading tumor cells, although they are noted in melanoma explants. | 1 | Applied and Interdisciplinary Chemistry |
The reason for the dot product is as follows. The only volume flowing through the cross-section is the amount normal to the area, that is, parallel to the unit normal. This amount is
where is the angle between the unit normal and the velocity vector of the substance elements. The amount passing through the cross-section is reduced by the factor . As increases less volume passes through. Substance which passes tangential to the area, that is perpendicular to the unit normal, does not pass through the area. This occurs when and so this amount of the volumetric flow rate is zero:
These results are equivalent to the dot product between velocity and the normal direction to the area. | 1 | Applied and Interdisciplinary Chemistry |
Electrohydrodynamic droplet deformation is a phenomenon that occurs when liquid droplets suspended in a second immiscible liquid are exposed to an oscillating electric field. Under these conditions, the droplet will periodically deform between prolate and oblate ellipsoidal shapes. The characteristic frequency and magnitude of the deformation is determined by a balance of electrodynamic, hydrodynamic, and capillary stresses acting on the droplet interface. This phenomenon has been studied extensively both mathematically and experimentally because of the complex fluid dynamics that occur. Characterization and modulation of electrodynamic droplet deformation is of particular interest for engineering applications because of the growing need to improve the performance of complex industrial processes(e.g. two-phase cooling, crude oil demulsification). The primary advantage of using oscillatory droplet deformation to improve these engineering processes is that the phenomenon does not require sophisticated machinery or the introduction of heat sources. This effectively means that improving performance via oscillatory droplet deformation is simple and in no way diminishes the effectiveness of the existing engineering system. | 1 | Applied and Interdisciplinary Chemistry |
It is possible to determine how much carbamino is formed through the techniques of electron ionization and mass spectrometry. In determining the amount of product by mass spectrometry, a careful set of instructions are followed which allows for the carbamino adducts to be transferred to a vacuum for mass spectrometry. With the separation of the carbamino adducts in the ion sampling process, it should be that the pH does not change. Hence, mass spectrometry and electron ionization are a way to measure how much carbamino adduct there is in comparison to concentration of peptide in a solution. | 0 | Theoretical and Fundamental Chemistry |
Gillian Reid (born 1964) is a British chemist who is Professor of Inorganic Chemistry and former Head of the Department of Chemistry at the University of Southampton. Her research considers coordination chemistry, inorganic semiconductors and metal fluoride scaffolds. In 2020, she was appointed the President-elect of the Royal Society of Chemistry, becoming President in 2022. | 0 | Theoretical and Fundamental Chemistry |
Electromigrated nanogaps are gaps formed in metallic bridges formed by the process of electromigration. A nanosized contact formed by electromigration acts like a waveguide for electrons. The nanocontact essentially acts like a one-dimensional wire with a conductance of . The current in a wire is the velocity of the electrons multiplied by the charge and number per unit length, or . This gives a conductance of . In nano scale bridges the conductance falls in discrete steps of multiples of the quantum conductance .
Electromigrated Nanogaps have shown great promise as electrodes in use in molecular scale electronics. Researchers have used feedback controlled electromigration to investigate the magnetoresistance of a quantum spin valve. | 0 | Theoretical and Fundamental Chemistry |
The zone plate microscope uses a zone plate (that acts roughly like as a classical lens) instead of a pinhole to focus the atom beam into a small focal spot. This means that the beam width equation changes significantly (see below).
Here, is the zone plate magnification and is the width of the smallest zone. Note the presence of chromatic aberrations (). The approximation sign indicates the regime in which the distance between the zone plate and the skimmer is much bigger than its focal length.
The first term in this equation is similar to the geometric contribution in the pinhole case: a bigger zone plate (taken all parameters constant) corresponds to a bigger focal spot size. The third term differs from the pinhole configuration optics as it includes a quadratic relation with the skimmer size (which is imaged through the zone plate) and a linear relation with the zone plate magnification, which will at the same time depend on its radius.
The equation to maximise, the intensity, is the same as the pinhole case with the substitution . By substitution of the magnification equation:
where is the average de-Broglie wavelength of the beam. Taking a constant , which should be made equal to the smallest achievable value, the maxima of the intensity equation with respect to the zone plate radius and the skimmer-zone plate distance can be obtained analytically. The derivative of the intensity with respect to the zone plate radius can be reduced the following cubic equation (once it has been set equal to zero):
Here some groupings are used: is a constant that gives the relative size of the smallest aperture of the zone plate compared with the average wavelength of the beam and is the modified beam width, which is used through the derivation to avoid explicitly operating with the constant airy term: .
This cubic equation is obtained under a series of geometrical assumptions and has a closed-form analytical solution that can be consulted in the original paper or obtained through any modern-day algebra software. The practical consequence of this equation is that zone plate microscopes are optimally designed when the distances between the components are small, and the radius of the zone plate is also small. This goes in line with the results obtained for the pinhole configuration, and has as its practical consequence the design of smaller scanning helium microscopes. | 0 | Theoretical and Fundamental Chemistry |
The formation of new blood capillaries is an important component of pathological tissue repair in response to ischemia. The angiogenic process is complex and involves endothelial cell (EC) movement and proliferation.
SFRP1 has been shown to have a role in new vascularization after an ischemic event and as a potent angiogenic factor. In vitro SFRP1 modulated the EC angiogenic response (migration, differentiation) and in vivo SFRP1 stimulated neovascularization in plug or tumor models. The directed movements of EC during de novo vessel formation are coordinated through cellular adhesion mechanisms, cytoskeletal reorganization and by association with elevated expression of angiogenic factors such as, the key factor, vascular endothelial growth factor. The regulation of the EC cytoskeleton is critical to EC spreading and motility. SFRP1 was found to have a major role in mediating EC spreading by regulating reorganization of the actin network and focal contact formations.
In vivo data supports a critical role for SFRP1 in ischemia-induced angiogenesis in adults. Using adenovirus-expressing SFRP1, impaired the canonical Wnt/Fzd pathway in the early phase of ischemia and as a result reduced vascular cell proliferation and delayed vessel formation. When SFRP1 was induced specifically in ECs along the kinetics of ischemia repair, a biphasic response was seen: a delay in capillary formation until day 15 and then an increase in vascular formation at day 25. This indicates that SFRP1 can fine tune the outcome of Wnt/Fzd signaling at different steps in the course of neovessel formation. | 1 | Applied and Interdisciplinary Chemistry |
A linear biochemical pathway is a chain of enzyme-catalyzed reaction steps. The figure below shows a three step pathway, with intermediates, and . In order to sustain a steady-state, the boundary species and are fixed.
At steady-state the rate of reaction is the same at each step. This means there is an overall flux from X_o to X_1.
Linear pathways possess some well-known properties:
# Flux control is biased towards the first few steps of the pathway. Flux control shifts more to the first step as the equilibrium constants become large.
# Flux control is small at reactions close to equilibrium.
# Assuming reversibly, flux control at a given step is proportional to the product of the equilibrium constants. For example, flux control at the second step in a three step pathway is proportional to the product of the second and third equilibrium constants.
In all cases, a rationale for these behaviors is given in terms of how elasticities transmit changes through a pathway. | 1 | Applied and Interdisciplinary Chemistry |
Flickering analysis of cellular or membranous structures is a widespread technique for measuring the bending modulus and other properties from the power spectrum of thermal fluctuations.
First demonstrated theoretically by Brochard and Lennon in 1975, flickering spectroscopy has become a widespread technique due to its simplicity and lack of specialised equipment beyond a brightfield microscope. It is used in structures such as red blood cells, giant unilamellar vesicles and other cell-like structures. | 0 | Theoretical and Fundamental Chemistry |
These drugs fall into two groups:
*Non-depolarizing blocking agents: These agents constitute the majority of the clinically relevant neuromuscular blockers. They act by competitively blocking the binding of ACh to its receptors, and in some cases, they also directly block the ionotropic activity of the ACh receptors.
*Depolarizing blocking agents: These agents act by depolarizing the sarcolemma of the skeletal muscle fiber. This persistent depolarization makes the muscle fiber resistant to further stimulation by ACh. | 1 | Applied and Interdisciplinary Chemistry |
Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold.
Hyperpolarization is often caused by efflux of K (a cation) through K channels, or influx of Cl (an anion) through Cl channels. On the other hand, influx of cations, e.g. Na through Na channels or Ca through Ca channels, inhibits hyperpolarization. If a cell has Na or Ca currents at rest, then inhibition of those currents will also result in a hyperpolarization. This voltage-gated ion channel response is how the hyperpolarization state is achieved. In neurons, the cell enters a state of hyperpolarization immediately following the generation of an action potential. While hyperpolarized, the neuron is in a refractory period that lasts roughly 2 milliseconds, during which the neuron is unable to generate subsequent action potentials. Sodium-potassium ATPases redistribute K and Na ions until the membrane potential is back to its resting potential of around –70 millivolts, at which point the neuron is once again ready to transmit another action potential. | 0 | Theoretical and Fundamental Chemistry |
Terahertz spectroscopy detects and controls properties of matter with electromagnetic fields that are in the frequency range between a few hundred gigahertz and several terahertz (abbreviated as THz). In many-body systems, several of the relevant states have an energy difference that matches with the energy of a THz photon. Therefore, THz spectroscopy provides a particularly powerful method in resolving and controlling individual transitions between different many-body states. By doing this, one gains new insights about many-body quantum kinetics and how that can be utilized in developing new technologies that are optimized up to the elementary quantum level.
Different electronic excitations within semiconductors are already widely used in lasers, electronic components and computers. At the same time, they constitute an interesting many-body system whose quantum properties can be modified, e.g., via a nanostructure design. Consequently, THz spectroscopy on semiconductors is relevant in revealing both new technological potentials of nanostructures as well as in exploring the fundamental properties of many-body systems in a controlled fashion. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms reactant and reagent are often used interchangeably, but reactant specifies a substance consumed in the course of a chemical reaction. Solvents, though involved in the reaction mechanism, are usually not called reactants. Similarly, catalysts are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrates. | 0 | Theoretical and Fundamental Chemistry |
A helical wheel is a type of plot or visual representation used to illustrate the properties of alpha helices in proteins.
The sequence of amino acids that make up a helical region of the protein's secondary structure are plotted in a rotating manner where the angle of rotation between consecutive amino acids is 100°, so that the final representation looks down the helical axis. | 1 | Applied and Interdisciplinary Chemistry |
A research group led by Professor Lars Berglund from Swedish KTH University along with a University of Maryland research group led by Professor Liangbing Hu have developed a method to remove the color and some chemicals from small blocks of wood, followed by adding polymers, such as poly(methyl methacrylate) (PMMA) and epoxy, at the cellular level, thereby rendering them transparent.
As soon as released in between 2015 and 2016, see-through wood had a large press reaction, with articles in ScienceDaily, Wired, The Wall Street Journal, and The New York Times.
Actually those research groups rediscovered a work from Siegfried Fink, a German Researcher, from as early as 1992: with a process very similar to Berglunds and Hus, the German Researcher turned wood transparent to reveal specific cavities of the wood structure for analytical purpose.
In 2021 researchers reported a way to manufacture transparent wood lighter and stronger than glass that requires substantially smaller amounts of chemicals and energy than methods used before. The thin wood produced with "solar-assisted chemical brushing" is claimed to be lighter and about 50 times stronger than wood treated with previous processes. | 0 | Theoretical and Fundamental Chemistry |
The Gilchrist–Thomas process or Thomas process is a historical process for refining pig iron, derived from the Bessemer converter. It is named after its inventors who patented it in 1877: Percy Carlyle Gilchrist and his cousin Sidney Gilchrist Thomas. By allowing the exploitation of phosphorous iron ore, the most abundant, this process allowed the rapid expansion of the steel industry outside the United Kingdom and the United States.
The process differs essentially from the Bessemer process in the refractory lining of the converter. The latter, being made of dolomite fired with tar, is basic, whereas the Bessemer lining, made of packed sand, is acidic. Phosphorus, by migrating from iron to slag, allows both the production of a metal of satisfactory quality, and of phosphates sought after as fertilizer, known as "Thomas meal". The disadvantages of the basic process includes larger iron loss and more frequent relining.
After having favored the spectacular growth of the Lorraine iron and steel industry, the process progressively faded away in front of the Siemens-Martin open hearth, which also used the benefit of basic refractory lining, before disappearing in the mid-1960s: with the development of gas liquefaction, the use of pure oxygen became economically viable. Even if modern pure oxygen converters all operate with a basic medium, their performance and operation have little to do with their ancestor. | 1 | Applied and Interdisciplinary Chemistry |
Marine carbonate ooids are formed in warm, supersaturated, shallow, highly agitated marine water intertidal environments, and their presence in geological records provides a key role in paleoclimatic and paleogeographic reconstructions. Huang et al. (2017), for example, based on the distribution of Permian ooids and glaciomarine diamictites, have repositioned the Baoshan Block in southwestern China, with respect to other Gondwana continents. | 0 | Theoretical and Fundamental Chemistry |
The National Poisons Information Service is an information service commissioned by Public Health England on behalf of the UK health departments. Poisoning accounts for 1% of NHS admissions. Pesticides used in agriculture (particularly organophosphorus insecticides) are extremely toxic, but 87% of around 120,000 annual poisoning cases in the UK take place in the home. | 1 | Applied and Interdisciplinary Chemistry |
Trichlorofluoromethane, also called freon-11, CFC-11, or R-11, is a chlorofluorocarbon (CFC). It is a colorless, faintly ethereal, and sweetish-smelling liquid that boils around room temperature. CFC-11 is a Class 1 ozone-depleting substance which allegedly damages Earth's protective stratospheric ozone layer. | 1 | Applied and Interdisciplinary Chemistry |
Xenin is a 25-amino acid polypeptide. The amino acid sequence of xenin is identical to the N-terminal end of cytoplasmic coatomer subunit alpha, from which xenin can be cleaved by aspartic proteases. Xenin is structurally related to the amphibian peptide xenopsin and to the neuropeptide neurotensin.
Surpassed by insulin, xenin reflects the second highest degree of homology traced along the evolutionary tree among the regulatory peptides, indicating its prominent structural conservatism. | 1 | Applied and Interdisciplinary Chemistry |
Transfer stations are intermediary drop off locations often used where treatment facilities are located too far away from population centers to make direct disposal feasible. In other locations, traffic concerns or local truck bans during daylight hours may make transfer stations feasible. In addition, municipalities where a significant percentage of homes cannot be accessed by tanker truck should utilize transfer stations. Transfer stations are used if:
* More than 5% of the homes are inaccessible by a vacuum truck;
* The treatment plant is too far away from the homes for transport in one haul to be practical;
* Trucks are not permitted on the streets during the day; or
* Heavy traffic during daylight hours impedes the movement of vacuum trucks. | 1 | Applied and Interdisciplinary Chemistry |
The journal is abstracted and indexed by:
*Cambridge Structural Database
*Chemical Abstracts Service
*Current Contents/Physical, Chemical & Earth Sciences
*Index Medicus/MEDLINE/PubMed
*Inspec
*PASCAL
*Science Citation Index Expanded
*Scopus
*VINITI Database RAS
According to the Journal Citation Reports, the journal has a 2021 impact factor of 3.520. | 0 | Theoretical and Fundamental Chemistry |
In 1942, the Metallurgical Laboratory at the University of Chicago was building the worlds first nuclear reactor called Chicago Pile-1' as part of the Manhattan Project. This would have required an enormous number of graphite blocks and uranium pellets. At the time, there was a limited source of pure uranium. Frank Spedding of Iowa State University was able to produce only two short tons of pure uranium. However, a larger quantity of additional uranium metal was required for the pile to go critical.
Around that time, Westinghouse Lamp Plant was able to supply a small amount of pure uranium metal. By 1941, there was an order for the uranium metal of 10 kilograms which was considered an enormous amount. The plant ramped up the production using makeshift equipment including metal garbage cans from a local market to use in the process. The order was fulfilled within a couple of months. By early 1942, there was another order from Arthur H. Compton of the Metallurgical Laboratory for three short tons of the uranium metal for the Chicago Pile-1.
The project was done in secrecy by not revealing any connection of the work there to the ongoing research on the nuclear reaction. To avoid leaking of information about the project at the plant, it was covered with the program called Tuballoy which was the codename for uranium in programs related to the Manhattan Project, taken from the British atomic weapons effort "Tube Alloys" which had been folded into Manhattan. Due to inadequate equipment and space, the refinement process was done in an ad hoc fashion having some operations done in the basement and some on the roof on a building at the plant. To maintain the confidentiality of the program, many workers who worked on the chemical processes were not familiar with it. Most of them did not know that their work was related to the creation of an atomic weapon.
Although the material and the processes were kept secret, the workers there knew they worked as part of the World War II efforts. They were led to believe that they worked on making conventional bombs. During the height of the production in 1942, there was a war production drive at the plant under the auspices of the labor-management committee to increase its production and warned workers against sabotage. The streets at the plant were renamed to MacArthur Avenue and MacArthur Plaza to promote patriotism.
Finally, the required amount of uranium metal was delivered to Chicago by the Army with containers clearly marked "URANIUM". The Chicago Pile-1 had gone to self-sustaining reaction on December 2, 1942, with the majority of uranium metal from the plant. After that, the plant continued to play a major role in supplying the uranium metal for the Manhattan Project until October 1943 when a better and more economical process was done elsewhere. During the contract, the plant produced 69 short tons of uranium metal in total. | 1 | Applied and Interdisciplinary Chemistry |
The radioisotope carbon-14 is constantly formed from nitrogen-14 (N) in the higher atmosphere by incoming cosmic rays which generate neutrons. These neutrons collide with N to produce C which then combines with oxygen to form CO. This radioactive CO spreads through the lower atmosphere and the oceans where it is absorbed by the plants and the animals that eat the plants. The radioisotope C thus becomes part of the biosphere so that all living organisms contain a certain amount of C. Nuclear testing caused a rapid increase in atmospheric C (see figure), since the explosion of an atomic bomb also creates neutrons which collide again with N and produce C. Since the ban on nuclear testing in 1963, atmospheric C relative concentration is slowly decreasing at a pace of 4% annually. This continuous decrease permits scientists to determine among others the age of deceased people and allows them to study cell activity in tissues. By measuring the amount of C in a population of cells and comparing that to the amount of C in the atmosphere during or after the bomb pulse, scientists can estimate when the cells were created and how often they've turned over since then. | 0 | Theoretical and Fundamental Chemistry |
The Couette flow orientation system is the most widely used method of sample orientation for UV LD. It has a number of characteristics which make it highly suitable as a method of sample alignment. Couette flow is currently the only established means of orientating molecules in the solution phase. This method also requires only very small amounts of analysis sample ( 20 - 40 µl) in order to generate an LD spectrum. The constant recirculation of sample is another useful property of the system, allowing many repeat measurements to be taken of each sample, decreasing the effect of noise on the final recorded spectrum.
Its mode of operation is very simple, with the sample sandwiched between a spinning tube and a stationary rod. As the sample is spun inside the cell, the light beam is shone through the sample, the parallel absorbance calculated from horizontally polarised light, the perpendicular absorbance from the vertically polarised light.
Couette flow UV LD is currently the only commercially available means of LD orientation. | 0 | Theoretical and Fundamental Chemistry |
Atomic electron transitions cause the emission or absorption of photons. Their statistics are Poissonian, and the time between jumps is exponentially distributed. The damping time constant (which ranges from nanoseconds to a few seconds) relates to the natural, pressure, and field broadening of spectral lines. The larger the energy separation of the states between which the electron jumps, the shorter the wavelength of the photon emitted.
In an ion trap, quantum jumps can be directly observed by addressing a trapped ion with radiation at two different frequencies to drive electron transitions. This requires one strong and one weak transition to be excited (denoted and respectively in the figure to the right). The electron energy level, , has a short lifetime, which allows for constant emission of photons at a frequency which can be collected by a camera and/or photomultiplier tube. State has a relatively long lifetime which causes an interruption of the photon emission as the electron gets shelved in state through application of light with frequency The ion going dark is a direct observation of quantum jumps. | 0 | Theoretical and Fundamental Chemistry |
The first estimate of a nuclear charge radius was made by Hans Geiger and Ernest Marsden in 1909, under the direction of Ernest Rutherford at the Physical Laboratories of the University of Manchester, UK. The famous experiment involved the scattering of α-particles by gold foil, with some of the particles being scattered through angles of more than 90°, that is coming back to the same side of the foil as the α-source. Rutherford put an upper limit on the radius of the gold nucleus of 34 femtometres.
Later studies found an empirical relation between the charge radius and the mass number, A, for heavier nuclei (A > 20):
:R ≈ rA
where the empirical constant r of 1.2–1.5 fm can be interpreted as the Compton wavelength of the proton. This gives a charge radius for the gold nucleus (A = 197) of about 7.69 fm. | 0 | Theoretical and Fundamental Chemistry |
It is still unclear the ecological effects of lactonase but it has been proposed that since bacteria mostly coexist with other microorganisms in the environment, some bacteria strains could have evolved its feeding strategies and utilize AHLs as their main resource for energy and nitrogen. | 1 | Applied and Interdisciplinary Chemistry |
The Bolzano process is a means to reduce magnesium to metallic form. "Dolomite-ferrosilicon briquettes are stacked on a special charge support system through which internal electric heating is conducted to the charge. A complete reaction takes 20 to 24 hours at 1,200 °C."
In 2014, Brazilian operations produced 10-15 kilotons of Mg by this process.
Also in 2014, Nevada Clean Magnesium announced its Tami-Mosi plan to create a ASTM B-92 pilot plant. The mineral resource is estimated at 412 billion tons of 12.3% grade Mg. The company produced its first ingot from a pilot plant in December 2018. | 1 | Applied and Interdisciplinary Chemistry |
In addition to the traditional line-by-line spectroscopic absorption parameters, the HITRAN database contains information on absorption cross-sections where the line-by-line parameters are absent or incomplete. Typically HITRAN includes absorption cross-sections for heavy polyatomic molecules (with low-lying vibrational modes) which are difficult for detailed analysis due to the high density of the spectral bands/lines, broadening effects, isomerization, and overall modeling complexity. There are 327 molecular species in the current edition of the database provided as cross-section files. The cross-section files are provided in the HITRAN format described on the official HITRAN website (http://hitran.org/docs/cross-sections-definitions/). | 0 | Theoretical and Fundamental Chemistry |
# Craddock P., 1995, Early Metal Mining and Production, Edinburgh University Press Ltd, Edinburgh
# Hauptmann A., T. Rehren & Schmitt-Strecker S., 2003, Early Bronze Age copper metallurgy at Shahr-i Sokhta (Iran), reconsidered, T. Stollner, G. Korlin, G. Steffens & J. Cierny, Eds., Man and mining, studies in honour of Gerd Weisgerber on occasion of his 65th birthday, Deutsches Bergbau Museum, Bochum
# Martinon-Torres M. & Rehren Th., 2009, Post Medieval crucible Production and Distribution: A Study of Materials and Materialities, Archaeometry Vol.51 No.1 pp49–74
# O. Faolain S., 2004, Bronze Artefact Production in Late Bronze Age Ireland: A Survey, British Archaeological Report, British Series 382, Archaeopress, Oxford
# Rehren, Th. and Papakhristu, O., 2000, Cutting Edge Technology – The Ferghana Process of Medieval crucible steel Smelting, Metalla, Bochum, 7(2) pp55–69
# Rehren T. & Thornton C. P, 2009, A truly refractory crucible from fourth millennium Tepe Hissar, Northeast Iran, Journal of Archaeological Science, Vol. 36, pp2700–2712
# Rehren Th., 1999, Small Size, Large Scale Roman brass Production in Germania Inferior, Journal of Archaeological Science, Vol. 26, pp 1083–1087
# Rehren Th., 2003, Crucibles as Reaction Vessels in Ancient Metallurgy, Ed in P. Craddock & J. Lang, Mining and Metal Production Through the Ages, British Museum Press, London pp207–215
# Roberts B. W., Thornton C. P. & Pigott V. C., 2009, Development of Metallurgy in Eurasia, Antiquity Vol. 83 pp 1012–1022
# Scheel B., 1989, Egyptian Metalworking and Tools, Shire Egyptology, Bucks
# Vavelidis M. & Andreou S., 2003, Gold and Gold working in Later Bronze Age Northern Greece, Naturwissenschaften, Vol. 95, pp 361–366
# Zwicker U., Greiner H., Hofmann K. & Reithinger M., 1985, Smelting, Refining and Alloying of copper and copper Alloys in Crucible Furnaces During Prehistoric up to Roman Times, P. Craddock & M. Hughes, Furnaces and Smelting Technology in Antiquity, British Museum, London | 0 | Theoretical and Fundamental Chemistry |
cDNA libraries are commonly used when reproducing eukaryotic genomes, as the amount of information is reduced to remove the large numbers of non-coding regions from the library. cDNA libraries are used to express eukaryotic genes in prokaryotes. Prokaryotes do not have introns in their DNA and therefore do not possess any enzymes that can cut it out during transcription process. cDNA does not have introns and therefore can be expressed in prokaryotic cells. cDNA libraries are most useful in reverse genetics where the additional genomic information is of less use. Additionally, cDNA libraries are frequently used in functional cloning to identify genes based on the encoded protein's function. When studying eukaryotic DNA, expression libraries are constructed using complementary DNA (cDNA) to help ensure the insert is truly a gene. | 1 | Applied and Interdisciplinary Chemistry |
Ye became interested in science fiction as a child. She was particularly interested in a story by Ye Yonglie that included a castle made from diamond. Ye learned that photocatalysis could split water into hydrogen and oxygen. She then became inspired by Jules Vernes The Mysterious Island', She studied chemistry at the Zhejiang University. After completing her undergraduate degree, she moved to Japan, where she joined the University of Tokyo. After earning her doctorate in 1990, she joined Osaka University as a research associate. | 0 | Theoretical and Fundamental Chemistry |
Bis(chloromethyl) ether has been extensively used in chemical synthesis, primarily as a crosslinking agent in the manufacture of ion-exchange resins and in the textile industry. It was also used as a linker in the synthesis of certain nerve agent antidotes (asoxime chloride, obidoxime).
Bis(chloromethyl) was also effective for chloromethylation of aromatic substrates. | 0 | Theoretical and Fundamental Chemistry |
Stem loop structures can sometimes be found in introns. mA residues located in these stem-loops weaken base-pairing interactions within the stem, thus altering the structure of the mRNA. This phenomenon is known as mA-Switch. The mA mark has an important role in alternative splicing, since it increases the accessibility of hnRNPC to its binding site. The heterogeneous nuclear ribonucleoprotein C (hnRNPC) is a RNA-binding protein that complexes with both heterogeneous nuclear RNA (hnRNA) and pre-mRNA to participate in pre-mRNA processing. hnRNPC binds to a uridine-rich region in introns that can usually form stem-loops. The destabilization of the stem-loop exposes the hnRNPC binding site, which increases the accessibility of the protein to the region. Because hnRNPC must be bound to pre-mRNA in order to fulfill its function, increased accessibility means higher activity of hnRNPC. Therefore, mA residues located in stem-loops of introns enhance the activity of hnRNPC, which results in increased alternative splicing. Evidence supporting this claim identified that decreased mA levels in the transcriptome lead to significantly reduced hnRNPC binding.
mA also has additional roles in alternative splicing by acting as the binding site for YTHDC1 (YTHDC1 binds to mA residues located in alternative exons). YTHDC1 has a double role in alternative splicing. First of all, it recruits the serine and arginine-rich splicing factor 3 (SRSF3), which promotes exon inclusion. In addition, YTHDC1 blocks binding of SRSF10, a protein involved in exon-skipping.
Due to the role of mA in alternative splicing, pre-mRNAs have higher levels of mA than mature mRNAs. Moreover, mA is more abundant in mRNAs that undergo alternative splicing compared to genes that code a single isoform. This is because alternatively spliced mRNAs are enriched in METTL3 binding sites. Splicing is affected in Mettl3 knock-out mice, resulting in increased frequency of exon skipping and intron retention. However, mA is not a general unspecific splicing factor, it only participates in the alternative splicing of certain mRNAs and lncRNAs. | 1 | Applied and Interdisciplinary Chemistry |
Dextrorphan was under development for the treatment of stroke, and reached phase II clinical trials for this indication, but development was discontinued. | 0 | Theoretical and Fundamental Chemistry |
Drug checking or pill testing is a way to reduce the harm from drug consumption by allowing users to find out the content and purity of substances that they intend to consume. This enables users to make safer choices: to avoid more dangerous substances, to use smaller quantities, and to avoid dangerous combinations.
Drug checking services have developed over the last twenty-five years in twenty countries and are being considered in more countries, although attempts to implement them in some countries have been hindered by local laws. Drug checking initially focused on MDMA users in electronic dance music events but the services have broadened as drug use has become more complex. These developments have been strongly affected by local laws and culture, resulting in a diverse range of services, both for mobile services that attend events and festivals and fixed sites in town centres and entertainment districts. For instance, staff may or may not be able to handle illegal substances, which limits the use of testing techniques to those where the staff are not legally in possession of those substances.
People intending to take drugs provide a small sample to the testing service (often less than a single dose). Test results may be provided immediately, after a short waiting period, or later. Drug checking services use this time to discuss health risks and safe behaviour with the service users. The services also provide public health information about drug use, new psychoactive substances and trends at a national level. | 0 | Theoretical and Fundamental Chemistry |
First flush is the initial surface runoff of a rainstorm. During this phase, water pollution entering storm drains in areas with high proportions of impervious surfaces is typically more concentrated compared to the remainder of the storm. Consequently, these high concentrations of urban runoff result in high levels of pollutants discharged from storm sewers to surface waters. | 1 | Applied and Interdisciplinary Chemistry |
Superfluids, such as helium-4 below the lambda point, exhibit many unusual properties. A superfluid acts as if it were a mixture of a normal component, with all the properties of a normal fluid, and a superfluid component. The superfluid component has zero viscosity and zero entropy. Application of heat to a spot in superfluid helium results in a flow of the normal component which takes care of the heat transport at relatively high velocity (up to 20 cm/s) which leads to a very high effective thermal conductivity. | 1 | Applied and Interdisciplinary Chemistry |
Carbon tetrachloride was widely used as a dry cleaning solvent, as a refrigerant, and in lava lamps. In the last case, carbon tetrachloride is a key ingredient that adds weight to the otherwise buoyant wax.
One speciality use of carbon tetrachloride was in stamp collecting, to reveal watermarks on postage stamps without damaging them. A small amount of the liquid is placed on the back of a stamp, sitting in a black glass or obsidian tray. The letters or design of the watermark can then be seen clearly. Today, this is done on lit tables without using carbon tetrachloride. | 1 | Applied and Interdisciplinary Chemistry |
Some organic matter not already in the soil comes from groundwater. When the groundwater saturates the soil or sediment around it, organic matter can freely move between the phases. Groundwater has its own sources of natural organic matter including:
* organic matter deposits, such as kerogen and coal.
* soil and sediment organic matter.
* organic matter infiltrating into the subsurface from rivers, lakes, and marine systems."
Organisms decompose into organic matter, which is then transported and recycled. Not all biomass migrates, some is rather stationary, turning only over the course of millions of years. | 0 | Theoretical and Fundamental Chemistry |
A nanolattice is a synthetic porous material consisting of nanometer-size members patterned into an ordered lattice structure, like a space frame. The nanolattice is a newly emerged material class that has been rapidly developed over the last decade. Nanolattices redefine the limits of the material property space. Despite being composed of 50-99% of air, nanolattices are very mechanically robust because they take advantage of size-dependent properties that we generally see in nanoparticles, nanowires, and thin films. The most typical mechanical properties of nanolattices include ultrahigh strength, damage tolerance, and high stiffness. Thus, nanolattices have a wide range of applications.
Driven by the evolution of 3D printing techniques, nanolattices aiming to exploit beneficial material size effects through miniaturized lattice designs were first developed in the mid-2010s,. Nanolattices are the smallest man-made lattice truss structures and a class of metamaterials that derive their properties from both their geometry (general metamaterial definition) and the small size of their elements. Therefore, they can possess effective properties not found in nature, and that may not be achieved with larger-scale lattices of the same geometry. | 0 | Theoretical and Fundamental Chemistry |
Especially for molecules exhibiting slowly relaxing (T) signals, the technique spin saturation transfer (SST) provides information on chemical exchange reactions. The method is widely applicable to fluxional molecules. This magnetization transfer technique provides rates, provided that they exceed 1/T. | 0 | Theoretical and Fundamental Chemistry |
Current muscle tissue engineering trends lead towards the development of skeletal muscle regeneration techniques over smooth muscle or cardiac muscle regeneration. A current trend found throughout literature is the treatment of Volumetric Muscle Loss (VML) using muscle tissue engineering techniques. VML is the result of abrupt loss of skeletal muscle due to surgical resection, trauma, or combat injuries. It has been observed that tissue grafts, the current treatment plan, do not restore full functionality or aesthetic integrity to the site of injury. Muscle tissue engineering offers an optimistic possibility for patients, as in situ, in vivo, and in vitro techniques have been proven to restore functionality to muscle tissue in the wound site. Methods being explored include acellular scaffold implantation, cell-seeded scaffold implantation, and in vitro fabrication of muscle grafts. Preliminary data from each of these methods promises a solution for patients suffering from VML.
Beyond specific technological advances in the field of muscle tissue engineering, researchers are working to establish a connection with the larger umbrella that is tissue engineering. | 1 | Applied and Interdisciplinary Chemistry |
Vesicular monoamine transporter 1 (VMAT1) also known as chromaffin granule amine transporter (CGAT) or solute carrier family 18 member 1 (SLC18A1) is a protein that in humans is encoded by the SLC18A1 gene. VMAT1 is an integral membrane protein, which is embedded in synaptic vesicles and serves to transfer monoamines, such as norepinephrine, epinephrine, dopamine, and serotonin, between the cytosol and synaptic vesicles. SLC18A1 is an isoform of the vesicular monoamine transporter. | 1 | Applied and Interdisciplinary Chemistry |
In the United States, Occupational Safety and Health Administration regulations recommend following American Society of Mechanical Engineers Standard A13.1-2015 - Scheme for the Identification of Piping Systems.
The standard states that labels should be placed where easily viewed by a person standing near the pipe at any of the following points:
* Valves and flanges.
* Approximately every to on straight sections.
* A pipe passes through a wall or floor.
* Any pipe direction changes, such bends or junctions. | 1 | Applied and Interdisciplinary Chemistry |
Analogous to 18-crown-6, 15-crown-5 binds to sodium ions. Thus, when treated with this complexing agent, sodium salts often become soluble in organic solvents.
First-row transition metal dications fit snugly inside the cavity of 15-crown-5. They are too small to be included in 18-crown-6. The binding of transition metal cations results in multiple hydrogen-bonded interactions from both equatorial and axial aqua ligands, such that highly crystalline solid-state supramolecular polymers can be isolated. Metal salts isolated in this form include Co(ClO), Ni(ClO), Cu(ClO), and Zn(ClO). Seven coordinate species are most common for transition metal ions complexes of 15-crown-5, with the crown ether occupying the equatorial plane, along with 2 axial aqua ligands.
15-crown-5 has also been used to isolate salts of oxonium ions. For example, from a solution of tetrachloroauric acid, the oxonium ion has been isolated as the salt . Neutron diffraction studies revealed a sandwich structure, which shows a chain of water with remarkably long O-H bond (1.12 Å) in the acidic proton, but with a very short OH•••O distance (1.32 Å).
A derivative of 15-crown-5, benzo-15-crown-5, has been used to produce anionic complexes of carbido ligands as their salts: | 0 | Theoretical and Fundamental Chemistry |
High light increases leaf thickness, either because of an increase in the number of cell layers within the leaf, and/or because of an increase in the cell size within a cell layer. The density of a leaf increases as well, and so does the leaf dry mass per area (LMA). There are also more stomata per mm2. | 0 | Theoretical and Fundamental Chemistry |
Many parameters and measurements in the physical sciences and engineering are expressed as a concrete number—a numerical quantity and a corresponding dimensional unit. Often a quantity is expressed in terms of several other quantities; for example, speed is a combination of length and time, e.g. 60 kilometres per hour or 1.4 kilometres per second. Compound relations with "per" are expressed with division, e.g. 60 km/h. Other relations can involve multiplication (often shown with a centered dot or juxtaposition), powers (like m for square metres), or combinations thereof.
A set of base units for a system of measurement is a conventionally chosen set of units, none of which can be expressed as a combination of the others and in terms of which all the remaining units of the system can be expressed. For example, units for length and time are normally chosen as base units. Units for volume, however, can be factored into the base units of length (m), thus they are considered derived or compound units.
Sometimes the names of units obscure the fact that they are derived units. For example, a newton (N) is a unit of force, which may be expressed as the product of mass (with unit kg) and acceleration (with unit m⋅s). The newton is defined as . | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, Taylor scraping flow is a type of two-dimensional corner flow occurring when one of the wall is sliding over the other with constant velocity, named after G. I. Taylor. | 1 | Applied and Interdisciplinary Chemistry |
Often in non-Newtonian or pseudoplastic fluids, such as a digester with high solids concentration, it does make sense to use coarse bubble diffusers rather than fine bubble diffusers, due to the larger bubbles' ability to shear through more viscous wastewater.
However, over the past two decades, coarse bubble diffusers have been used less frequently, primarily due to the ever increasing cost of energy and the availability of more reliable, highly efficient fine bubble diffusers. Manufacturers of diffused aeration systems claim that converting from coarse bubble to fine bubble system should yield a 50 percent energy cost savings. Specifically, in aeration tanks, a system that utilizes coarse bubble diffusers requires 30 to 40 percent more process air than a fine bubble diffused air system to provide the same level of treatment. The exception would be in secondary treatment (or side processing) phases. In these processing tanks, floc particles, sediment and carbonate buildup tend to plug or clog the small air release openings on the fine bubble diffusers. Because of their small air openings, fine bubble diffusers cease to have an advantage. Currently, coarse bubble diffusers are the mainstay solution.
These diffusers are typically made in the shape of a perforated rectangular pipe called a wide band, or a cap of in diameter with an elastomeric membrane. Other varieties of coarse bubble diffusers exist, though it is generally accepted that all of them perform similarly with respect to mass oxygen transfer. When comparing disc-shaped diffusers, the majority fail to withstand specific challenges, beyond 1 or 2 years, which include: clogging, blowing off and cracking. Any coarse bubble diffuser that eliminates these problems would deliver a huge cost-savings, not only in product replacement, but in system downtime to facilitate their exchange. This is a motivating factor considered by budget-sensitive operators at municipal waste water treatment processing plants. | 1 | Applied and Interdisciplinary Chemistry |
The main borate anions are:
* tetrahydroxyborate , found in sodium tetrahydroxyborate .
* orthoborate , found in trisodium orthoborate
* , found in the calcium yttrium borosilicate oxyapatite
* perborate , as in sodium perborate
* metaborate or its cyclic trimer , found in sodium metaborate
* diborate , found in magnesium diborate (suanite),
* triborate , found in calcium aluminium triborate (johachidolite),
* tetraborate , found in anhydrous borax
* tetrahydroxytetraborate , found in borax "decahydrate"
* tetraborate(6-) found in lithium tetraborate(6-)
* pentaborate or , found in sodium pentaborate
* octaborate found in disodium octaborate | 0 | Theoretical and Fundamental Chemistry |
Sialyl lewis x is important in ABO blood antigen determination.
SLex is also important to proper immune response. P-selectin release from Weibel-Palade bodies, on blood vessel endothelial cells, can be induced by a number of factors. One such factor is the response of the endothelial cell to certain bacterial molecules, such as peptidoglycan. P-selectin binds to the SLex structure that is present on neutrophils in the bloodstream and helps to mediate the extravasation of these cells into the surrounding tissue during infection.
O-linked glycans, in particular mucin, have been found to be important in developing normal intestinal microflora. Certain strains of intestinal bacteria bind specifically to mucin, allowing them to colonize the intestine.
Examples of O-linked glycoproteins are:
*Glycophorin, a protein in erythrocyte cell membranes
*Mucin, a protein in saliva involved in formation of dental plaque
*Notch, a transmembrane receptor involved in development and cell fate decisions
*Thrombospondin
*Factor VII
*Factor IX
*Urinary type plasminogen activator | 0 | Theoretical and Fundamental Chemistry |
Halogenation of silyl enol ethers gives haloketones.
Acyloins form upon organic oxidation with an electrophilic source of oxygen such as an oxaziridine or mCPBA.
In the Saegusa–Ito oxidation, certain silyl enol ethers are oxidized to enones with palladium(II) acetate. | 0 | Theoretical and Fundamental Chemistry |
β-Hydroxy β-methylglutaryl-CoA (HMG-CoA), also known as 3-hydroxy-3-methylglutaryl coenzyme A, is an intermediate in the mevalonate and ketogenesis pathways. It is formed from acetyl CoA and acetoacetyl CoA by HMG-CoA synthase. The research of Minor J. Coon and Bimal Kumar Bachhawat in the 1950s at University of Illinois led to its discovery.
HMG-CoA is a metabolic intermediate in the metabolism of the branched-chain amino acids, which include leucine, isoleucine, and valine. Its immediate precursors are β-methylglutaconyl-CoA (MG-CoA) and β-hydroxy β-methylbutyryl-CoA (HMB-CoA).
HMG-CoA reductase catalyzes the conversion of HMG-CoA to mevalonic acid, a necessary step in the biosynthesis of cholesterol. | 1 | Applied and Interdisciplinary Chemistry |
Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll a. They include other forms of this pigment, such as chlorophyll b in green algal and vascular ("higher") plant antennae, while other algae may contain chlorophyll c or d. In addition, there are many non-chlorophyll accessory pigments, such as carotenoids or phycobiliproteins, which also absorb light and transfer that light energy to photosystem chlorophyll. Some of these accessory pigments, in particular the carotenoids, also serve to absorb and dissipate excess light energy, or work as antioxidants. The large, physically associated group of chlorophylls and other accessory pigments is sometimes referred to as a pigment bed.
The different chlorophyll and non-chlorophyll pigments associated with the photosystems all have different absorption spectra, either because the spectra of the different chlorophyll pigments are modified by their local protein environment or because the accessory pigments have intrinsic structural differences. The result is that, in vivo, a composite absorption spectrum of all these pigments is broadened and flattened such that a wider range of visible and infrared radiation is absorbed by plants and algae. Most photosynthetic organisms do not absorb green light well, thus most remaining light under leaf canopies in forests or under water with abundant plankton is green, a spectral effect called the "green window". Organisms such as some cyanobacteria and red algae contain accessory phycobiliproteins that absorb green light reaching these habitats.
In aquatic ecosystems, it is likely that the absorption spectrum of water, along with gilvin and tripton (dissolved and particulate organic matter, respectively), determines phototrophic niche differentiation. The six shoulders in the light absorption of water between wavelengths 400 and 1100 nm correspond to troughs in the collective absorption of at least twenty diverse species of phototrophic bacteria. Another effect is due to the overall trend for water to absorb low frequencies, while gilvin and tripton absorb higher ones. This is why open ocean appears blue and supports yellow species such as Prochlorococcus, which contains divinyl-chlorophyll a and b. Synechococcus, colored red with phycoerythrin, is adapted to coastal bodies, while phycocyanin allows Cyanobacteria to thrive in darker inland waters. | 0 | Theoretical and Fundamental Chemistry |
Another useful imaging mode is differential interference contrast (DIC), which is usually obtained with a system designed by the Polish physicist Georges Nomarski. This system gives the best detail. DIC converts minor height differences on the plane-of-polish, invisible in BF, into visible detail. The detail in some cases can be quite striking and very useful. If an ST filter is used along with a Wollaston prism, color is introduced. The colors are controlled by the adjustment of the Wollaston prism, and have no specific physical meaning, per se. But, visibility may be better. | 1 | Applied and Interdisciplinary Chemistry |
In this part of the experiment, Tamm et al. transfected 293 cells with survivin and lysed them to obtain cell lysate. The lysates were incubated with different caspase forms and survivin was immunopercipitated with anti-survivin antibody. The idea behind this is that, if survivin binds physically with the caspase it is incubated with, it will be co-precipitated along with the survivin while everything else in the lysate is washed away. The immunoprecipitates were then run on SDS-PAGE and then immunoblotted for detection of the desired caspase. If the caspase of interest was detected, it meant that it was bound to survivin in the immunoprecipitation step implicating that survivin and the particular caspase had bound beforehand. Active caspase-3 and -7 coimmunoprecipitated with survivin. The inactive proforms of caspase-3 and -7 did not bind survivin. Survivin also does not bind to active caspase-8. Caspase-3 and -7 are effector proteases whereas caspase-8 is an initiator caspase that sits more upstream in the apoptotic pathway. These results demonstrate survivins capability to bind with particular caspases in vitro, but may not necessarily translate over to actual physiological conditions. Later, a 2001 study confirmed that human survivin tightly binds caspase-3 and -7 when expressed in E. coli'.
Further evidence to support the idea that survivin blocks apoptosis by directly inhibiting caspases was given by Tamm et al. 293 cells were transfected with either overexposed caspase-3 or -7 encoding plasmid and with survivin. They showed that survivin inhibited processing of these two caspases into their active forms. While survivin has been shown as mentioned above to bind to only the active forms of these caspases, it is likely here that survivin inhibits the active forms of the caspases resulting from cleaving and activating more of its own proforms. Thus, survivin acts possibly by preventing such a cascade of cleavage and activation amplification from happening resulting in decreased apoptosis.
In similar manner, looking at the mitochondrial pathway of apoptosis, cytochrome c was transiently expressed in 293 cells to look at the inhibitory effects survivin had on this pathway. Although the details are not here, survivin was shown to also inhibit cytochrome c and caspase-8-induced activation of caspases. | 1 | Applied and Interdisciplinary Chemistry |
The perilipins are considered to have their origins in a common ancestral gene which, during the first and second vertebrate genome duplication, gave rise to six types of PLIN genes. | 1 | Applied and Interdisciplinary Chemistry |
A/LCI combines low-coherence interferometry with angle-resolved scattering to solve the inverse problem of determining scatterer geometry based on far field diffraction patterns. Similar to optical coherence domain reflectometry (OCDR) and optical coherence tomography (OCT), a/LCI uses a broadband light source in an interferometry scheme in order to achieve optical sectioning with a depth resolution set by the coherence length of the source. Angle-resolved scattering measurements capture light as a function of the scattering angle, and invert the angles to deduce the average size of the scattering objects via a computational light scattering model such as Mie theory, which predicts angles based on the size of the scattering sphere. Combining these techniques allows construction of a system that can measure average scatter size at various depths within a tissue sample.
At present the most significant medical application of the technology is determining the state of tissue health based on measurements of average cell nuclei size. It has been found that as tissue changes from normal to cancerous, the average cell nuclei size increases. Several recent studies have shown that via cell nuclei measurements, a/LCI can detect the presence of low- and high-grade dysplasia with 91% sensitivity and distinguish between normal and dysplastic with 97% specificity. | 0 | Theoretical and Fundamental Chemistry |
Lectins is a generic name for proteins with carbohydrate-recognizing domains (CRD). Although it became almost synonymous with glycan-binding proteins, it does not include antibodies which also belong to the class.
Lectins found in plants and fungi cells have been extensively used in research as a tool to detect, purify, and analyze glycans. However, useful lectins usually have sub-optimal specificities. For instance, Ulex europaeus agglutinin-1 (UEA-1), a plant-extracted lectin capable of binding to human blood type O antigen, can also bind to unrelated glycans such as 2'-fucosyllactose, GalNAcα1-4(Fucα1-2)Galβ1-4GlcNAc, and Lewis-Y antigen. | 1 | Applied and Interdisciplinary Chemistry |
In humans, cAMP works by activating protein kinase A (PKA, cAMP-dependent protein kinase), one of the first few kinases discovered. It has four sub-units two catalytic and two regulatory. cAMP binds to the regulatory sub-units. It causes them to break apart from the catalytic sub-units. The catalytic sub-units make their way in to the nucleus to influence transcription. Further effects mainly depend on cAMP-dependent protein kinase, which vary based on the type of cell.
cAMP-dependent pathway is necessary for many living organisms and life processes. Many different cell responses are mediated by cAMP; these include increase in heart rate, cortisol secretion, and breakdown of glycogen and fat. cAMP is essential for the maintenance of memory in the brain, relaxation in the heart, and water absorbed in the kidney.
This pathway can activate enzymes and regulate gene expression. The activation of preexisting enzymes is a much faster process, whereas regulation of gene expression is much longer and can take up to hours. The cAMP pathway is studied through loss of function (inhibition) and gain of function (increase) of cAMP.
If cAMP-dependent pathway is not controlled, it can ultimately lead to hyper-proliferation, which may contribute to the development and/or progression of cancer. | 1 | Applied and Interdisciplinary Chemistry |
AMG 510 by Amgen is a KRAS p.G12C covalent inhibitor that has recently finished Phase I clinical trial. The drug elicited partial responses in half of evaluable patients with KRAS G12C-mutant non–small cell lung cancer, and led to stable disease in most evaluable patients with colorectal (or appendix) cancer. | 1 | Applied and Interdisciplinary Chemistry |
No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature.
This statement for N-coupled heat baths in steady state becomes
A dynamical version of the II-law can be proven, based on Spohn's inequality:
which is valid for any L-GKS generator, with a stationary state, .
Consistency with thermodynamics can be employed to verify quantum dynamical models of transport. For example, local models for networks where local L-GKS equations are connected through weak links have been thought to violate the second law of thermodynamics. In 2018 has been shown that, by correctly taking into account all work and energy contributions in the full system, local master equations are fully coherent with the second law of thermodynamics | 0 | Theoretical and Fundamental Chemistry |
Ligand-targeted liposomes are used for a variety of applications depending on the liposome, ligand, and liposome contents. Ligand-targeted liposomes can also be used for diagnostics through imaging. The liposomes can contain imaging agents to aid in visualization such as fluorescent dyes, labeling probes, and contrast agents. Commonly, a radioactive gamma-emitter, fluorescent marker, or magnetic resonance imaging (MRI) agent is encapsulated in the liposome for this application. The active targeting mechanism of LTLs allows the target tissue to retain the imaging agent while the remaining agent is cleared from circulation. The ligand-targeted liposomes increase the specificity and sensitivity of the images taken through positron emission tomography (PET), single-photon emission computed tomography (SPECT), and MRI techniques through the ligand localization to receptors of interest. Biotinylated liposomes containing [Ga] coupled with a later injection of avidin have been shown to reduce background signal and produce the needed contrast for imaging while reducing the circulation time of radioactive imaging agent. Molecular imaging of processes over time in vivo is also made possible using ligand-targeted nanoparticles. As of 2015, many ligand-targeted imaging agents such as MIP-1404, MIP-1405, MIP-1072, MIP-109, and F-DCFBC were undergoing clinical trials. The ability of a liposome to encapsulate these imaging agents and deliver them to specific regions through ligand targeting is helpful for precision detection.
Ligand-targeted liposomes are a promising method of drug delivery. These systems are efficient in delivering the drug to localized areas with low peripheral distribution, which minimizes the off-target effects. The favorable biodistribution to target tissue is an encouraging property of this drug delivery system. In addition to highly targeting tissue, the ligand-targeted liposomes have a short circulating half-life, so they can be quickly cleared from the bloodstream. Ligand-targeted liposomes can be used to deliver AuNRs for localized delivery of photo-thermal therapy in cancer treatment. Photodynamic therapy (PDT) is a non-invasive cancer therapy that relies on a photosensitizing (PS) pro-drug to interact with light and oxygen as a cancer therapeutic agent. PSs can be encapsulated in LTLs, allowing them to move through systemic circulation to the tumor site for ligand binding to specify the area of their effect. Using PDT causes damage to cancer cells and tumor microvasculature. There are many liposome-based products currently approved or undergoing clinical trials.
Aside from cancer therapies, ligand-targeted liposomes can also be used to target inflammation in the body that may be present due to rheumatoid arthritis, psoriasis, vascular inflammation, and organ transplantation. E-selectin is a cell-specific receptor expressed by inflamed endothelium that ligands can target.
LTLs also have the potential for localized treatment in fungal infections. AmBisome (L-AMB) is an LTL that contains Amphotericin B (AMPH-B), an anti-fungal treatment that is effective for a broad variety of fungal infections. AMPH-B can be toxic after prolonged exposure, making it a good candidate for the targeting and rapid clearing of systemic circulation of LTLs. AmBisome is also effective due to the inflammation in the area of fungal activity, which increases vascular permeation. | 1 | Applied and Interdisciplinary Chemistry |
Energy designs and manufactures custom welded hydraulic cylinders. It also designs and manufactures hydraulic valves, pumps, powerpacks and power systems. Energy's cylinders are used in construction, road machinery, forestry, man lift and hoist, industrial bailer, waste compacting, and agricultural industries. Energy manufactures a wide variety of hydraulic cylinders; welded, tie-rod, ram-type, rephasing, telescopic, and position-sensing. Energy has designed and manufactured hydraulic cylinders with bores from less than one inch (2.5 cm), up to 11 inches (28 cm). Cylinders have been manufactured with strokes up to 15 feet (4.5 cm). Energy has designed cylinders with working pressures as high as 10,000 psig (690 bar). | 1 | Applied and Interdisciplinary Chemistry |
Proteorhodopsin (PR or pRhodopsin) was first discovered in 2000 within a bacterial artificial chromosome from previously uncultivated marine Gammaproteobacteria, still only referred to by their ribotype metagenomic data, SAR86. More species of Gammaproteobacteria, both Gram-positive and Gram-negative, were found to express the protein. | 0 | Theoretical and Fundamental Chemistry |
About 600 regulatory sequences in promoters and about 800 regulatory sequences in enhancers appear to depend on double-strand breaks initiated by topoisomerase 2β (TOP2B) for activation. The induction of particular double-strand breaks is specific with respect to the inducing signal. When neurons are activated in vitro, just 22 TOP2B-induced double-strand breaks occur in their genomes. However, when contextual fear conditioning is carried out in a mouse, this conditioning causes hundreds of gene-associated DSBs in the medial prefrontal cortex and hippocampus, which are important for learning and memory.
Such TOP2B-induced double-strand breaks are accompanied by at least four enzymes of the non-homologous end joining (NHEJ) DNA repair pathway (DNA-PKcs, KU70, KU80 and DNA LIGASE IV) (see figure). These enzymes repair the double-strand breaks within about 15 minutes to 2 hours. The double-strand breaks in the promoter are thus associated with TOP2B and at least these four repair enzymes. These proteins are present simultaneously on a single promoter nucleosome (there are about 147 nucleotides in the DNA sequence wrapped around a single nucleosome) located near the transcription start site of their target gene.
The double-strand break introduced by TOP2B apparently frees the part of the promoter at an RNA polymerase–bound transcription start site to physically move to its associated enhancer. This allows the enhancer, with its bound transcription factors and mediator proteins, to directly interact with the RNA polymerase that had been paused at the transcription start site to start transcription.
Similarly, topoisomerase I (TOP1) enzymes appear to be located at many enhancers, and those enhancers become activated when TOP1 introduces a single-strand break. TOP1 causes single-strand breaks in particular enhancer DNA regulatory sequences when signaled by a specific enhancer-binding transcription factor. Topoisomerase I breaks are associated with different DNA repair factors than those surrounding TOP2B breaks. In the case of TOP1, the breaks are associated most immediately with DNA repair enzymes MRE11, RAD50 and ATR. | 1 | Applied and Interdisciplinary Chemistry |
Possibly the most common use of affinity chromatography is for the purification of recombinant proteins. Proteins with a known affinity are protein tagged in order to aid their purification. The protein may have been genetically modified so as to allow it to be selected for affinity binding; this is known as a fusion protein. Protein tags include hexahistidine (His), glutathione-S-transferase (GST), maltose binding protein (MBP), and the Colicin E7 variant CL7 tag. Histidine tags have an affinity for nickel, cobalt, zinc, copper and iron ions which have been immobilized by forming coordinate covalent bonds with a chelator incorporated in the stationary phase. For elution, an excess amount of a compound able to act as a metal ion ligand, such as imidazole, is used. GST has an affinity for glutathione which is commercially available immobilized as glutathione agarose. During elution, excess glutathione is used to displace the tagged protein. CL7 has an affinity and specificity for Immunity Protein 7 (Im7) which is commercially available immobilized as Im7 agarose resin. For elution, an active and site-specific protease is applied to the Im7 resin to release the tag-free protein. | 0 | Theoretical and Fundamental Chemistry |
The re-evaluation of single enantiomers not without problems. The chiral switches of fluoxetine and fenfluramine are classical examples. The development of (R )-fluoxetine was terminated after patients developed abnormal heart rhythms. The chiral switch of fenfluramine, dexfenfluramine was withdrawn from world marker due to pulmonary hypertension. The table below enumerates couple of chiral switches aborted or withdrawn due stereochemically engineered toxicity. | 0 | Theoretical and Fundamental Chemistry |
BCF is commercially synthesized in a two-step process from chloroform. Chloroform is fluorinated with hydrogen fluoride. The resulting chlorodifluoromethane is then reacted with elemental bromine at 400-600 °C, with reaction time limited to about 3 seconds. The overall yield is over 90%. | 1 | Applied and Interdisciplinary Chemistry |
Dexpramipexole is the (D)-enantiomer of pramipexole. Enantiopure dexpramipexole has essentially no dopamine agonist activity and shares no other pharmacologic similarity to pramipexole. In contrast, pramipexole the (S)-enantiomer is a dopamine agonist and is an approved drug (Mirapex) used in Parkinson’s disease.
Dexpramipexole is a low molecular weight, orally bioavailable, water-soluble small molecule with linear pharmacokinetics and linear dose proportionality. | 0 | Theoretical and Fundamental Chemistry |
The gonadotropin receptors are a group of receptors that bind a group of pituitary hormones called gonadotropins. They include the:
* Follicle-stimulating hormone receptor (FSHR) - binds follicle-stimulating hormone (FSH)
* Luteinizing hormone receptor (LHR) - binds luteinizing hormone (LH) and human chorionic gonadotropin (hCG) | 1 | Applied and Interdisciplinary Chemistry |
Despite all the improvement in the waste and recovery processes there are still some challenges:
*Lack of incentive to recycle when inconvenient; opt-in and subscription models lead to low participation
*Rising material recovery facility fees and pressure from the waste management industry have caused some municipalities to remove glass from curbside recycling
*The lack of recycling mandates and high levels of contamination cause a significant portion of materials to be disposed of in landfills.
*Low landfill tip fees for many MRFs (material recovery facilities) incentivize sending glass to the landfill.
*The lack of capacity in certain areas hinders the ability to meet the market demand and reduces the incentive to invest in materials recovery facilities.
*In some regions, strong demand for cullet from other end markets reduces potential supply for glass containers.
*The distance between the sources of and markets for cullet requires long-haul shipping.
*Virgin materials are often cheaper than cullet, sometimes by as much as 20%. | 0 | Theoretical and Fundamental Chemistry |
Reaction bonded silicon carbide, also known as siliconized silicon carbide or SiSiC, is a type of silicon carbide that is manufactured by a chemical reaction between porous carbon or graphite with molten silicon. Due to the left over traces of silicon, reaction bonded silicon carbide is often referred to as siliconized silicon carbide, or its abbreviation SiSiC.
If bulk silicon carbide is produced by sintering of silicon carbide powder, it usually contains traces of chemicals called sintering aids, which are added to support the sintering process by allowing lower sintering temperatures. This type of silicon carbide is often referred to as sintered silicon carbide, or abbreviated to SSiC.
The silicon carbide powder is gained from silicon carbide produced as described in the article silicon carbide. | 1 | Applied and Interdisciplinary Chemistry |
Boron porphyrins are a variety of porphyrin, a common macrocycle used for photosensitization and metal trapping applications, that incorporate boron. The central four nitrogen atoms in a porphyrin macrocycle form a unique molecular pocket which is known to accommodate transition metals of various sizes and oxidation states. Due to the diversity of binding modes available to porphyrin, there is a growing interest in introducing other elements (i.e. main group elements) into this pocket.
Boron in particular has been shown to prefer binding to porphyrin in a 2:1 stoichiometry, primarily due to its small atomic radius, but the Group XIII element will bind in a 1:1 ratio with corrole, a macromolecule with a structure similar to porphyrin but with a smaller N pocket.
Boron porphyrins are of interest because of the unique geometric environment to which both boron and porphyrin are subjected upon B-N bond formation. These new geometric motifs lead to novel reactivity, one of the most surprising examples being sterically-induced reductive coupling. Possible applications for boron porphyrins include BNCT delivery agents and OLED devices.
Also of interest are molecules containing both boron and porphyrin moieties, but without B-N bonds. Examples include diketonate-porphyrin compounds and dyads (two-component molecules) containing the classic BODIPY dye. | 0 | Theoretical and Fundamental Chemistry |
The other context of agricultural issues involves the transport of agricultural chemicals (nitrates, phosphates, pesticides, herbicides, etc.) via surface runoff. This result occurs when chemical use is excessive or poorly timed with respect to high precipitation. The resulting contaminated runoff represents not only a waste of agricultural chemicals, but also an environmental threat to downstream ecosystems. Pine straws are often used to protect soil from soil erosion and weed growth. However, harvesting these crops may result in the increase of soil erosion. | 1 | Applied and Interdisciplinary Chemistry |
Many different amino acid side chains have been described as ADP-ribose acceptors. From a chemical perspective, this modification represents protein glycosylation: the transfer of ADP-ribose occurs onto amino acid side chains with a nucleophilic oxygen, nitrogen, or sulfur, resulting in N-, O-, or S-glycosidic linkage to the ribose of the ADP-ribose. Originally, acidic amino acids (glutamate and aspartate) were described as the main sites of ADP-ribosylation. However, many other ADP-ribose acceptor sites such as serine, arginine, cysteine, lysine, diphthamide, phosphoserine, and asparagine have been identified in subsequent works. | 1 | Applied and Interdisciplinary Chemistry |
In 1996, IUPAC held another meeting, reconsidered all names in hand, and accepted another set of recommendations; finally, it was approved and published in 1997 on the 39th IUPAC General Assembly in Geneva, Switzerland. Element 105 was named dubnium (Db), after Dubna in Russia, the location of the JINR; the American suggestions were used for elements 102, 103, 104, and 106. The name dubnium had been used for element 104 in the previous IUPAC recommendation. The American scientists "reluctantly" approved this decision. IUPAC pointed out that the Berkeley laboratory had already been recognized several times, in the naming of berkelium, californium, and americium, and that the acceptance of the names rutherfordium and seaborgium for elements 104 and 106 should be offset by recognizing JINR's contributions to the discovery of elements 104, 105, and 106.
The following names were agreed in 1997 on the 39th IUPAC General Assembly in Geneva, Switzerland:
Thus, the convention of the discoverer's right to name their elements was respected for elements 106 to 109, and the two disputed claims were "shared" between the two opponents. | 1 | Applied and Interdisciplinary Chemistry |
Evans married Tommie Johnson in 1967. They had two children. Evans died on March 24, 2001, in Chapel Hill. The Slayton A. Evans Jr. Memorial Lecture Fund and the Slayton Evans Research Award were both named in his honor post-humously. | 0 | Theoretical and Fundamental Chemistry |
"Redox" is a portmanteau of the words "reduction" and "oxidation". The term "redox" was first used in 1928.
The processes of oxidation and reduction occur simultaneously and cannot occur independently. In redox processes, the reductant transfers electrons to the oxidant. Thus, in the reaction, the reductant or reducing agent loses electrons and is oxidized, and the oxidant or oxidizing agent gains electrons and is reduced. The pair of an oxidizing and reducing agent that is involved in a particular reaction is called a redox pair. A redox couple is a reducing species and its corresponding oxidizing form, e.g., / .The oxidation alone and the reduction alone are each called a half-reaction because two half-reactions always occur together to form a whole reaction. | 0 | Theoretical and Fundamental Chemistry |
Rotary kilns started to be used for lime manufacture at the start of the 20th century and now account for a large proportion of new installations if energy costs are less important. The early use of simple rotary kilns had the advantages that a much wider range of limestone size could be used, from fines upwards, and undesirable elements such as sulfur can be removed. On the other hand, fuel consumption was relatively high because of poor heat exchange compared with shaft kilns, leading to excessive heat loss in exhaust gases. Old fashioned "long" rotary kilns operate at 7 to 10 MJ/kg. Modern installations partially overcome this disadvantage by adding a preheater, which has the same good solids/gas contact as a shaft kiln, but fuel consumption is still somewhat higher, typically in range of 4.5 to 6 MJ/kg. In the design shown, a circle of shafts (typically 8–15) is arranged around the kiln riser duct. Hot limestone is discharged from the shafts in sequence, by the action of a hydraulic "pusher plate". Kilns of 1000 tonnes per day output are typical. The rotary kiln is the most flexible of any lime kilns able to produce soft, medium, or hard burned as well as dead-burned lime or dolime. | 1 | Applied and Interdisciplinary Chemistry |
NETA has been studied for use as a potential male hormonal contraceptive in combination with testosterone in men. | 1 | Applied and Interdisciplinary Chemistry |
2-Furoic acid is an organic compound, consisting of a furan ring and a carboxylic acid side-group. Along with other furans, its name is derived from the Latin word furfur, meaning bran, from which these compounds were first produced. The salts and esters of furoic acids are known as furoates. 2-Furoic acid is most widely encountered in food products as a preservative and a flavouring agent, where it imparts a sweet, earthy flavour. | 0 | Theoretical and Fundamental Chemistry |
Proteins without signal peptides can also be secreted by unconventional mechanisms. E.g. Interleukin, Galectin. The process by which such secretory proteins gain access to the cell exterior is termed unconventional protein secretion (UPS). In plants, even 50% of secreted proteins can be UPS dependent. | 1 | Applied and Interdisciplinary Chemistry |
Many ylides react in sigmatropic reactions. The Sommelet-Hauser rearrangement is an example of a [2,3]-sigmatropic reaction. The Stevens rearrangement is a [1,2]-rearrangement.
A -sigmatropic reaction has been observed in certain phosphonium ylides. | 0 | Theoretical and Fundamental Chemistry |
The function of msDNA remains unknown even though many copies are present within cells. Knockout mutations that do not express msDNA are viable, so the production of msDNA is not essential to life under laboratory conditions. Over-expression of msDNA is mutagenic, apparently as a result of titrating out repair proteins by the mismatched base pairs that are typical of their structure. It has been suggested that msDNA may have some role in pathogenicity or the adaptation to stressful conditions. Sequence comparison of msDNAs from Myxococcus xanthus, Stigmatella aurantiaca, and many other bacteria reveal conserved and hypervariable domains reminiscent of conserved and hypervariable sequences found in allorecognition molecules. The major msDNAs of M. xanthus and S. aurantiaca, for instance, share 94% sequence homology except within a 19 base-pair domain that shares sequence homology of only 42%. The presence of such domains is significant because myxobacteria exhibit complex cooperative social behaviors including swarming and formation of fruiting bodies, while E. coli and other pathogenic bacteria form biofilms that exhibit enhanced antibiotic and detergent resistance. The sustainability of social assemblies that require significant individual investment of energy is generally dependent on the evolution of allorecognition mechanisms that enable groups to distinguish self versus non-self. | 1 | Applied and Interdisciplinary Chemistry |
Kubista was born to his medical doctor father in the former Czechoslovakia in 1961. His father received a scholarship and relocated to Sweden. At the age of 7 in 1968, Kubista went to Sweden to visit his father. However, on that very day, Russia invaded Czechoslovakia in the so called Warsaw Pact invasion of Czechoslovakia, and as a result, the family decided to stay making Sweden their new home. | 1 | Applied and Interdisciplinary Chemistry |
Förster resonance energy transfer (FRET)-based Cl indicators consist of two fluorescent proteins, Cyan fluorescent protein (CFP) and YFP connected via a polypeptide linker. This allows ratiometric Cl measurements based on the Cl sensitivity of YFP and Cl insensivity of CFP. Clomeleon and Cl Sensor are FRET-based Cl indicators that allow ratiometric non-invasive monitoring of chloride activity in living cells. | 0 | Theoretical and Fundamental Chemistry |
In 1966, Harry G. Hecht (with Wesley W. Wendlandt) published a book entitled "Reflectance Spectroscopy", because "unlike transmittance spectroscopy, there were no reference books written on the subject" of "diffuse reflectance spectroscopy", and "the fundamentals were only to be found in the old literature, some of which was not readily accessible". Hecht describes himself as a novice in the field at the time, and said that if he had known that Gustav Kortüm "a great pillar in the field" was in the process of writing a book on the subject, he "would not have undertaken the task". Hecht was asked to write a review of Kortüms book and their correspondence concerning it led to Hecht spending a year in Kortüms laboratories. Kortüm is the author most often cited in the book.
One of the features of the remission function emphasized by Hecht was the fact that
should yield the absorption spectrum displaced by . While the scattering coefficient might change with particle size, the absorption coefficient, which should be proportional to concentration of an absorber, would be obtainable by a background correction for a spectrum. However, experimental data showed the relationship did not hold in strongly absorbing materials. Many papers were published with various explanations for this failure of the Kubelka-Munk equation. Proposed culprits included: incomplete diffusion, anisotropic scatter ("the invalid assumption that radiation is returned equally in all directions from a given particle"), and presence of regular reflection. The situation resulted in a myriad of models and theories being proposed to correct these supposed deficiencies. The various alternative theories were evaluated and compared.
In his book, Hecht reported the mathematics of Stokes and Melamed formulas (which he called “statistical methods”). He believed the approach of Melamed, which “involve a summation over individual particles” was more satisfactory than summations over “plane parallel layers”. Unfortunately, Melamed's method failed as the refractive index of the particles approached unity, but he did call attention to the importance of using individual particle properties, as opposed to coefficients that represent averaged properties for a sample. E.L. Simmons used a simplified modification of the particle model to relate diffuse reflectance to fundamental optical constants without the use of the cumbersome equations. In 1975, Simmons evaluated various theories of diffuse reflectance spectroscopy and concluded that a modified particle model theory is probably the most nearly correct.
In 1976, Hecht wrote a lengthy paper comprehensively describing the myriad of mathematical treatments that had been proposed to deal with diffuse reflectance. In this paper, Hecht states that he assumed (as did Simmons) that in the plane-parallel treatment, the layers could not be made infinitesimally small, but should be restricted to layers of finite thickness interpreted as the mean particle diameter of the sample. This is also supported by the observation that the ratio of the Kubelka–Munk absorption and scattering coefficients is that of corresponding ratio of the Mie coefficients for a sphere. That factor can be rationalized by simple geometric considerations, recognizing that to a first approximation, the absorption is proportional to volume and the scatter is proportional to cross sectional surface area. This is entirely consistent with the Mie coefficients measuring absorption and scatter at a point, and the Kubelka–Munk coefficients measuring scatter by a sphere.
To correct this deficiency of the Kubelka–Munk approach, for the case of an infinitely thick sample, Hecht blended the particle and layer methods by replacing the differential equations in the Kubelka–Munk treatment by finite difference equations, and obtained the Hecht finite difference formula:
Hecht apparently did not know that this result could be generalized, but he realized that the above formula "represents an improvement … and shows the need to consider the particulate nature of scattering media in developing a more precise theory". | 0 | Theoretical and Fundamental Chemistry |
The N-methyl-D-aspartate receptor (NMDA receptor) – a type of ionotropic glutamate receptor – is a ligand-gated ion channel that is gated by the simultaneous binding of glutamate and a co-agonist (i.e., either D-serine or glycine). Studies show that the NMDA receptor is involved in regulating synaptic plasticity and memory.
The name "NMDA receptor" is derived from the ligand N-methyl-D-aspartate (NMDA), which acts as a selective agonist at these receptors. When the NMDA receptor is activated by the binding of two co-agonists, the cation channel opens, allowing Na and Ca to flow into the cell, in turn raising the cell's electric potential. Thus, the NMDA receptor is an excitatory receptor. At resting potentials, the binding of Mg or Zn at their extracellular binding sites on the receptor blocks ion flux through the NMDA receptor channel. "However, when neurons are depolarized, for example, by intense activation of colocalized postsynaptic AMPA receptors, the voltage-dependent block by Mg is partially relieved, allowing ion influx through activated NMDA receptors. The resulting Ca influx can trigger a variety of intracellular signaling cascades, which can ultimately change neuronal function through activation of various kinases and phosphatases". Ligands include:
* Primary endogenous co-agonists: glutamate and either D-serine or glycine
* Other agonists : aminocyclopropanecarboxylic acid; D-cycloserine; L-aspartate; quinolinate, etc.
* Partial agonists : N-methyl-D-aspartic acid (NMDA); NRX-1074; 3,5-dibromo-L-phenylalanine, etc.
* Antagonists: ketamine, PCP, dextropropoxyphene, ketobemidone, tramadol, kynurenic acid (endogenous), etc. | 1 | Applied and Interdisciplinary Chemistry |
Two drugs having different targets in unrelated pathways that ultimately result in the desired therapeutic result are considered to have additive effects with independent actions. For example, artemisinin and curcumin both exert antimalarial effects. Artemisinin works by being metabolized in the body into active metabolites. The metabolites would then create reactive oxygen species(ROS) that damage the parasites and kill them. The mechanism of action of curcumin remains largely unknown, but the antiparasitic effect is believed to be associated with the potentiation of innate and adaptive immunological responses. The combined effects of artemisinin and curcumin each contribute to the death of parasites via different mechanisms and the effect is shown to be additive by fractional inhibitory concentrations.
Drugs with the same target in different sites that produce additive effects are also considered as independent action. For example, doxorubicin and trabectedin can both produce anticancer effect. Doxorubicin is a DNA intercalator that prefers to bind to AT regions, while trabectedin forms guanine adduct in DNA to disrupt DNA repair system. A recent study has shown that doxorubicin and trabectedin do not hinder each other and could produce an additive anticancer effect. | 1 | Applied and Interdisciplinary Chemistry |
Methyl fluoroacetate is produced and used as a chemical reagent and it can be released to the environment through several waste streams. When it was used as a rodenticide, it was released directly to the environment where it would be broken down in the air. If released to air, an estimated vapor pressure of 31 mmHg at 25 °C indicates methyl fluoroacetate will exist solely as a vapor in the atmosphere. Vapor-phase methyl fluoroacetate will be degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals. The half-life for this reaction in air is estimated to be 98 days.
MFA does not contain chromophores that absorb at wavelengths > 290 nm and therefore it's not expected to be susceptible to direct photolysis by sunlight. | 1 | Applied and Interdisciplinary Chemistry |
Hybrid methods that rely on structural and ligand similarity were also developed to overcome the limitations of traditional VLS approaches. This methodologies utilizes evolution‐based ligand‐binding information to predict small-molecule binders and can employ both global structural similarity and pocket similarity. A global structural similarity based approach employs both an experimental structure or a predicted protein model to find structural similarity with proteins in the PDB holo‐template library. Upon detecting significant structural similarity, 2D fingerprint based Tanimoto coefficient metric is applied to screen for small-molecules that are similar to ligands extracted from selected holo PDB templates. The predictions from this method have been experimentally assessed and shows good enrichment in identifying active small molecules.
The above specified method depends on global structural similarity and is not capable of a priori selecting a particular ligand‐binding site in the protein of interest. Further, since the methods rely on 2D similarity assessment for ligands, they are not capable of recognizing stereochemical similarity of small-molecules that are substantially different but demonstrate geometric shape similarity. To address these concerns, a new pocket centric approach, PoLi, capable of targeting specific binding pockets in holo‐protein templates, was developed and experimentally assessed. | 1 | Applied and Interdisciplinary Chemistry |
Observations of specific gravity and buoyancy were recorded by ancient Chinese philosophers. In the 4th century BCE Mencius describes the weight of the gold is equivalent to the feathers. In 3rd century CE, Cao Chong describes the story of weighing the elephant by observing displacement of the boats loaded with different weights. | 1 | Applied and Interdisciplinary Chemistry |
Although the problem was first found in brass, any alloy containing copper will be susceptible to the problem. It includes copper itself (as used in pipe for example), bronzes and other alloys with a significant copper content. Like all problems with hairline cracks, detection in the early stages of attack is difficult, but the characteristic blue coloration may give a clue to attack. Microscopic inspection will often reveal the cracks, and x-ray analysis using the EDX facility on the scanning electron microscope or SEM should reveal the presence of elemental nitrogen from ammoniacal traces. | 1 | Applied and Interdisciplinary Chemistry |
A nitrate test is a chemical test used to determine the presence of nitrate ion in solution. Testing for the presence of nitrate via wet chemistry is generally difficult compared with testing for other anions, as almost all nitrates are soluble in water. In contrast, many common ions give insoluble salts, e.g. halides precipitate with silver, and sulfate precipitate with barium.
The nitrate anion is an oxidizer, and many tests for the nitrate anion are based on this property. However, other oxidants present in the analyte may interfere and give erroneous results.
Nitrate can also be detected by first reducing it to the more reactive nitrite ion and using one of many nitrite tests. | 0 | Theoretical and Fundamental Chemistry |
* National Science Foundation Career Award, 2007–2012
* Meade Endowment Honored Faculty, 2007–2008
* Eli Lilly Young Analytical Investigator Award, 2007
* American Chemical Society PROGRESS/Dreyfus Foundation Lectureship, 2008
* Camille Dreyfus Teacher-Scholar, 2010
* Society for Electroanalytical Chemistry, Young Investigator Award, 2011
* President Elect, International Society of Monitoring Molecules in vivo, 2018–2022
* Distinguished Researcher Award, American Chemical Society Virginia Section, 2020 | 0 | Theoretical and Fundamental Chemistry |
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