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The structure of a transcriptional factory directly relates to its function. Transcription is made more efficient because of the clustered nature of the transcription factory. All the necessary proteins: RNA polymerase, transcription factors and other co-regulators are present in the transcription factory that allows for faster RNA polymerisation when the DNA template reaches the factory, it also allows for a number of genes to be transcribed at the same time. | 1 | Applied and Interdisciplinary Chemistry |
A cryoprotectant is a substance used to protect biological tissue from freezing damage (i.e. that due to ice formation). Arctic and Antarctic insects, fish and amphibians create cryoprotectants (antifreeze compounds and antifreeze proteins) in their bodies to minimize freezing damage during cold winter periods. Cryoprotectants are also used to preserve living materials in the study of biology and to preserve food products.
For years, glycerol has been used in cryobiology as a cryoprotectant for blood cells and bull sperm, allowing storage in liquid nitrogen at temperatures around −196 °C. However, glycerol cannot be used to protect whole organs from damage. Instead, many biotechnology companies are researching the development of other cryoprotectants more suitable for such uses. A successful discovery may eventually make possible the bulk cryogenic storage (or "banking") of transplantable human and xenobiotic organs. A substantial step in that direction has already occurred. Twenty-First Century Medicine has vitrified a rabbit kidney to -135 °C with their proprietary vitrification cocktail. Upon rewarming, the kidney was successfully transplanted into a rabbit, with complete functionality and viability, able to sustain the rabbit indefinitely as the sole functioning kidney. | 1 | Applied and Interdisciplinary Chemistry |
Recent study proposed that the citrate–malate shuttle may contribute to sustaining cancer cells through a β-oxidation-citrate–malate shuttle metabolic pathway. In normal cells, β-oxidation produces acetyl-CoA which enters the Krebs cycle to produce ATP, and β-oxidation cannot continue if the Krebs cycle is impaired and acetyl-CoA accumulates. However, cancer cells may carry out continuous β-oxidation by connecting it to the citrate–malate shuttle. The new metabolic pathway consists of mitochondrial transport proteins and several enzymes, including ATP-citrate lyase (ACLY) and malate dehydrogenases 1 and 2 (MDH1 and MDH2). The proposed metabolic pathway may explain the Warburg effect – that cancer cells produce energy through a suboptimal pathway – and hypoxia in cancer.
The energy efficiency of this pathway is 3.76 times less than the normal β-oxidation Krebs cycle pathway, only producing 26 moles instead of 98 moles of ATP from 1 mole of palmitate.
It is still unsure whether this pathway exists in cancer cells. Factors preventing this pathway from occurring includes lipotoxicity of palmitate and stearate. | 1 | Applied and Interdisciplinary Chemistry |
Agricultures role in developed countries has drastically changed in the last century due to many factors, including refrigeration. Statistics from the 2007 census gives information on the large concentration of agricultural sales coming from a small portion of the existing farms in the United States today. This is a partial result of the market created for the frozen meat trade by the first successful shipment of frozen sheep carcasses coming from New Zealand in the 1880s. As the market continued to grow, regulations on food processing and quality began to be enforced. Eventually, electricity was introduced into rural homes in the United States, which allowed refrigeration technology to continue to expand on the farm, increasing output per person. Today, refrigerations use on the farm reduces humidity levels, avoids spoiling due to bacterial growth, and assists in preservation. | 0 | Theoretical and Fundamental Chemistry |
A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions to take place. In a chain reaction, positive feedback leads to a self-amplifying chain of events.
Chain reactions are one way that systems which are not in thermodynamic equilibrium can release energy or increase entropy in order to reach a state of higher entropy. For example, a system may not be able to reach a lower energy state by releasing energy into the environment, because it is hindered or prevented in some way from taking the path that will result in the energy release. If a reaction results in a small energy release making way for more energy releases in an expanding chain, then the system will typically collapse explosively until much or all of the stored energy has been released.
A macroscopic metaphor for chain reactions is thus a snowball causing a larger snowball until finally an avalanche results ("snowball effect"). This is a result of stored gravitational potential energy seeking a path of release over friction. Chemically, the equivalent to a snow avalanche is a spark causing a forest fire. In nuclear physics, a single stray neutron can result in a prompt critical event, which may finally be energetic enough for a nuclear reactor meltdown or (in a bomb) a nuclear explosion.
Numerous chain reactions can be represented by a mathematical model based on Markov chains. | 0 | Theoretical and Fundamental Chemistry |
In fluid mixing, one often wishes to homogenize a species, that can be characterized by its concentration field q. Often, the species can be considered as a passive tracer that does not modify the flow. The species can be for example a dye to be mixed.
The evolution of a concentration field obeys the advection-diffusion equation, also called convection–diffusion equation:
Compared to the simple diffusion equation, the term proportional to the velocity field represents the effect of advection.
When mixing a spot of tracer, the advection term dominates the evolution of the concentration field at the beginning of the mixing process. Chaotic advection transforms the spot into a bundle of thin filaments. The width of a dye filament decreases exponentially with time, until an equilibrium scale is reached, at which the effect of diffusion starts to be significant. This scale is called the Batchelor scale. It is defined as the square root of the ratio between the diffusion coefficient and the Lyapunov exponent
where is the Lyapunov exponent and D is the diffusion coefficient.
This scale measures the balance between stretching and diffusion on the evolution of the concentration field: stretching tends to decrease the width of a filament, while diffusion tends to increase it. The Batchelor scale is the smallest length scale that can be observed in the concentration field, since diffusion smears out quickly any finer detail.
When most dye filaments reach the Batchelor scale, diffusion begins to decrease significantly the contrast of concentration between the filament and the surrounding domain. The time at which a filament reaches the Batchelor scale is therefore called its mixing time. The resolution of the advection–diffusion equation shows that after the mixing time of a filament, the decrease of the concentration fluctuation due to diffusion is exponential, resulting in fast homogenization with the surrounding fluid. | 1 | Applied and Interdisciplinary Chemistry |
A key characteristic of amorphous brazing foils (ABFs) is their relatively low melting points, which typically range from 830 to 1200°C. This attribute is crucial for their application as filler metals in brazing. Due to their ductility and flexibility, ABFs present a viable alternative to filler metals in paste or powder form. This substitution offers notable advantages, such as the elimination of soot formation, a common drawback associated with residual organic solvents in paste-based fillers. Additionally, ABFs help minimize the formation of surface oxides, an issue frequently encountered with gas-atomized powder fillers, thereby enhancing the quality and integrity of the brazed joint. | 1 | Applied and Interdisciplinary Chemistry |
Extended aeration agitates all incoming waste in the sludge from a single clarifier. The combined sludge starts with a higher concentration of inert solids than typical secondary sludge and the longer mixing time required for digestion of primary solids in addition to dissolved organics produces aged sludge requiring greater mixing energy input per unit of waste oxidized. | 1 | Applied and Interdisciplinary Chemistry |
Proxenin is the precursor to xenin. It is a 35-amino acid polypeptide. Like xenin, its amino acid sequence exactly matches the N-terminus of coatomer subunit alpha. | 1 | Applied and Interdisciplinary Chemistry |
Nuclear reactions may be shown in a form similar to chemical equations, for which invariant mass must balance for each side of the equation, and in which transformations of particles must follow certain conservation laws, such as conservation of charge and baryon number (total atomic mass number). An example of this notation follows:
To balance the equation above for mass, charge and mass number, the second nucleus to the right must have atomic number 2 and mass number 4; it is therefore also helium-4. The complete equation therefore reads:
or more simply:
Instead of using the full equations in the style above, in many situations a compact notation is used to describe nuclear reactions. This style of the form A(b,c)D is equivalent to A + b producing c + D. Common light particles are often abbreviated in this shorthand, typically p for proton, n for neutron, d for deuteron, α representing an alpha particle or helium-4, β for beta particle or electron, γ for gamma photon, etc. The reaction above would be written as Li(d,α)α. | 0 | Theoretical and Fundamental Chemistry |
While a hydrogel's mechanical properties can be tuned and modified through crosslink concentration and additives, these properties can also be enhanced or optimized for various applications through specific processing techniques. These techniques include electro-spinning, 3D/4D printing, self-assembly, and freeze-casting. One unique processing technique is through the formation of multi-layered hydrogels to create a spatially-varying matrix composition and by extension, mechanical properties. This can be done by polymerizing the hydrogel matrixes in a layer by layer fashion via UV polymerization. This technique can be useful in creating hydrogels that mimic articular cartilage, enabling a material with three separate zones of distinct mechanical properties.
Another emerging technique to optimize hydrogel mechanical properties is by taking advantage of the Hofmeister series. Due to this phenomenon, through the addition of salt solution, the polymer chains of a hydrogel aggregate and crystallize, which increases the toughness of the hydrogel. This method, called "salting out", has been applied to poly(vinyl alcohol) hydrogels by adding a sodium sulfate salt solution. Some of these processing techniques can be used synergistically with each other to yield optimal mechanical properties. Directional freezing or freeze-casting is another method in which a directional temperature gradient is applied to the hydrogel is another way to form materials with anisotropic mechanical properties. Utilizing both the freeze-casting and salting-out processing techniques on poly(vinyl alcohol) hydrogels to induce hierarchical morphologies and anisotropic mechanical properties. Directional freezing of the hydrogels helps to align and coalesce the polymer chains, creating anisotropic array honeycomb tube-like structures while salting out the hydrogel yielded out a nano-fibril network on the surface of these honeycomb tube-like structures. While maintaining a water content of over 70%, these hydrogels' toughness values are well above those of water-free polymers such as polydimethylsiloxane (PDMS), Kevlar, and synthetic rubber. The values also surpass the toughness of natural tendon and spider silk. | 0 | Theoretical and Fundamental Chemistry |
Like conventional thermite, super thermite reacts at very high temperature and is difficult to extinguish. The reaction produces dangerous ultra-violet (UV) light, requiring that the reaction not be viewed directly or that special eye protection (for example, a welder's mask) be worn.
In addition, super thermites are very sensitive to electrostatic discharge (ESD). Surrounding the metal oxide particles with carbon nanofibers may make nanothermites safer to handle. | 0 | Theoretical and Fundamental Chemistry |
Aluminium and its alloys are difficult to solder due to the formation of the passivation layer of aluminium oxide. The flux has to be able to disrupt this layer and facilitate wetting by solder. Salts or organic complexes of some metals can be used; the salt has to be able to penetrate the cracks in the oxide layer. The metal ions, more noble than aluminium, then undergo a redox reaction, dissolve the surface layer of aluminium and form a deposit there. This intermediate layer of another metal then can be wetted with a solder.
One example of such flux is a composition of triethanolamine, fluoroboric acid, and cadmium fluoroborate. More than 1% magnesium in the alloy impairs the flux action, however, as the magnesium oxide layer is more refractory. Another possibility is an inorganic flux composed of zinc chloride or tin(II) chloride, ammonium chloride, and a fluoride (e.g. sodium fluoride). Presence of silicon in the alloy impairs the flux effectivity, as silicon does not undergo the exchange reaction aluminium does. | 1 | Applied and Interdisciplinary Chemistry |
Catalysts based on synthetic metalloporphyrins have been extensively investigated, although few or no applications exist. Due to their distinctive redox properties, Co(II)–porphyrin-based systems are radical initiators. Some complexes emulate the action of various heme enzymes such as cytochrome P450, lignin peroxidase. Metalloporphyrins are also studied as catalysts for water splitting, with the purpose of generating molecular hydrogen and oxygen for fuel cells.
In addition, porous organic polymers based on porphyrins, along with metal oxide nanoparticles, | 1 | Applied and Interdisciplinary Chemistry |
For all organic matter to be completely oxidized, an excess amount of potassium dichromate (or any oxidizing agent) must be present. Once oxidation is complete, the amount of excess potassium dichromate must be measured to ensure that the amount of Cr can be determined with accuracy. To do so, the excess potassium dichromate is titrated with ferrous ammonium sulfate (FAS) until all of the excess oxidizing agent has been reduced to Cr. Typically, the oxidation-reduction indicator ferroin is added during this titration step as well. Once all the excess dichromate has been reduced, the ferroin indicator changes from blue-green to a reddish brown. The amount of ferrous ammonium sulfate added is equivalent to the amount of excess potassium dichromate added to the original sample. Note: Ferroin indicator is bright red from commercially prepared sources, but when added to a digested sample containing potassium dichromate it exhibits a green hue. During the titration the color of the indicator changes from a green hue to a bright blue hue to a reddish brown upon reaching the endpoint. Ferroin indicator changes from red to pale blue when oxidized. | 0 | Theoretical and Fundamental Chemistry |
Rab27 is a member of the Rab subfamily of GTPases. Rab27 is post translationally modified by the addition of two geranylgeranyl groups on the two C-terminal cysteines. | 1 | Applied and Interdisciplinary Chemistry |
Laser-based bioprinting can be split into two major classes: those based on cell transfer technologies or photo-polymerization. In cell transfer laser printing, a laser stimulates the connection between energy-absorbing material (e.g. gold, titanium, etc.) and the bioink. This donor layer vaporizes under the laser's irradiation, forming a bubble from the bioink layer which gets deposited from a jet. Photo-polymerization techniques rather use photoinitiated reactions to solidify the ink, moving the beam path of a laser to induce the formation of a desired construct. Certain laser frequencies paired with photopolymerization reactions can be carried out without damaging cells in the material. | 1 | Applied and Interdisciplinary Chemistry |
Fischer carbenes are used with alkynes as the starting reagents for the Wulff–Dötz reaction, forming phenols. | 0 | Theoretical and Fundamental Chemistry |
Adsorption of molecules onto polymer surfaces is central to a number of applications, including development of non-stick coatings and in various biomedical devices. Polymers may also be adsorbed to surfaces through polyelectrolyte adsorption. | 0 | Theoretical and Fundamental Chemistry |
Light-dependent reactions are certain photochemical reactions involved in photosynthesis, the main process by which plants acquire energy. There are two light dependent reactions: the first occurs at photosystem II (PSII) and the second occurs at photosystem I (PSI).
PSII absorbs a photon to produce a so-called high energy electron which transfers via an electron transport chain to cytochrome bf and then to PSI. The then-reduced PSI, absorbs another photon producing a more highly reducing electron, which converts NADP to NADPH. In oxygenic photosynthesis, the first electron donor is water, creating oxygen (O) as a by-product. In anoxygenic photosynthesis, various electron donors are used.
Cytochrome bf and ATP synthase work together to produce ATP (photophosphorylation) in two distinct ways. In non-cyclic photophosphorylation, cytochrome bf uses electrons from PSII and energy from PSI to pump protons from the stroma to the lumen. The resulting proton gradient across the thylakoid membrane creates a proton-motive force, used by ATP synthase to form ATP. In cyclic photophosphorylation, cytochrome bf uses electrons and energy from PSI to create more ATP and to stop the production of NADPH. Cyclic phosphorylation is important to create ATP and maintain NADPH in the right proportion for the light-independent reactions.
The net-reaction of all light-dependent reactions in oxygenic photosynthesis is:
:2 + 2 + 3ADP + 3P → + 2 H + 2NADPH + 3ATP
PSI and PSII are light-harvesting complexes. If a special pigment molecule in a photosynthetic reaction center absorbs a photon, an electron in this pigment attains the excited state and then is transferred to another molecule in the reaction center. This reaction, called photoinduced charge separation, is the start of the electron flow and transforms light energy into chemical forms. | 0 | Theoretical and Fundamental Chemistry |
Ouabain is a highly toxic compound, however, it has a low bioavailability and is absorbed poorly from the alimentary tract as so much of the oral dose is destroyed. Intravenous administration results in greater available concentrations. After intravenous administration, the onset of action occurs within 2–10 minutes in humans with the maximum effect enduring for 1.5 hours.
Ouabain is eliminated by renal excretion, largely unchanged. | 0 | Theoretical and Fundamental Chemistry |
Stabilized decomposed granite is a mixture of a non-resin binder and aggregate (decomposed granite). The binder, which may include color, is mixed with the decomposed granite and the mixture is moistened either before it is put in place or after. Stabilized decomposed granite provides a strong and durable surface that is suitable for pedestrian and vehicular traffic in applications such as pathways, driveways, car parks and access roads. The surface is ADA compliant and can be painted on.. | 1 | Applied and Interdisciplinary Chemistry |
In thermodynamics, the Massieu function (sometimes called Massieu–Gibbs function, Massieu potential, or Gibbs function, or characteristic (state) function in its original terminology), symbol (Psi), is defined by the following relation:
where for every system with degree of freedom one may choose variables, e.g. to define a coordinate system, where and are extensive and intensive variables, respectively, and where at least one extensive variable must be within this set in order to define the size of the system. The -th variable, , is then called the Massieu function.
The Massieu function was introduced in the 1869 paper "On the Characteristic Functions of Various Fluids" by French engineer François Massieu (1832-1896). The name "Gibbs function" is the eponym of American physicist Willard Gibbs (1839-1903), who cited Massieu in his 1876 On the Equilibrium of Heterogeneous Substances. Massieu, as discussed in the first footnote to the abstract of Gibbs Equilibrium, “appears to have been the first to solve the problem of representing all the properties of a body of invariable composition which are concerned in reversible processes by means of a single function.” Massieus 1869 paper seems to be the source for the generalized mathematical conception of the energy of a system being equal to summations of the products of pairs of conjugate variables. | 0 | Theoretical and Fundamental Chemistry |
The ubiquitin-proteasome system (UPS) figures prominently in protein degradation. The 26S proteasome consists of a catalytic subunit (the 20S core particle), and a regulatory subunit (the 19S cap). Poly-ubiquitin chains tag proteins for degradation by the proteasome, which causes hydrolysis of tagged proteins into smaller peptides.
Physiologically, PI31 attacks 20S catalytic domain of 26S Proteasome that results in decreased proteasome activity. (ADP-ribosyl)transferase Tankyrase (TNKS) causes ADP-ribosylation of PI31 which in turn increases the proteasome activity. Inhibition of TNKs further shows the reduced 26S Proteasome assembly. Therefore, ADP-ribosylation promotes 26S Proteasome activity in both Drosophila and human cells. | 1 | Applied and Interdisciplinary Chemistry |
The process produces a quantity of fluoride waste: perfluorocarbons and hydrogen fluoride as gases, and sodium and aluminium fluorides and unused cryolite as particulates. This can be as small as 0.5 kg per tonne of aluminium in the best plants in 2007, up to 4 kg per tonne of aluminium in older designs in 1974. Unless carefully controlled, hydrogen fluorides tend to be very toxic to vegetation around the plants.
The Soderberg process which bakes the Anthracite/pitch mix as the anode is consumed, produces significant emissions of polycyclic aromatic hydrocarbons as the pitch is consumed in the smelter.
The linings of the pots end up contaminated with cyanide-forming materials; Alcoa has a process for converting spent linings into aluminium fluoride for reuse and synthetic sand usable for building purposes and inert waste. | 1 | Applied and Interdisciplinary Chemistry |
* [http://www.elsevier.com/wps/find/journaldescription.cws_home/522751/description#description Ecological Engineering] since 1992, with a general description of the field.
* [https://archive.today/20130203002409/http://www.springerlink.com/content/112761/ Landscape and Ecological Engineering] since 2005.
* [https://jeed.pubpub.org/ Journal of Ecological Engineering Design] Officially launched in 2021, this journal offers a diamond open access format (free to the reader, free to the authors). This is the official journal of the American Ecological Engineering Society with production support from the University of Vermont Libraries. | 1 | Applied and Interdisciplinary Chemistry |
Species containing AFPs may be classified as
Freeze avoidant: These species are able to prevent their body fluids from freezing altogether. Generally, the AFP function may be overcome at extremely cold temperatures, leading to rapid ice growth and death.
Freeze tolerant: These species are able to survive body fluid freezing. Some freeze tolerant species are thought to use AFPs as cryoprotectants to prevent the damage of freezing, but not freezing altogether. The exact mechanism is still unknown. However, it is thought AFPs may inhibit recrystallization and stabilize cell membranes to prevent damage by ice. They may work in conjunction with ice nucleating proteins (INPs) to control the rate of ice propagation following freezing. | 1 | Applied and Interdisciplinary Chemistry |
The serotonin created by the brain comprises around 10% of total body serotonin. The majority (80-90%) is found in the gastrointestinal (GI) tract. It travels around the brain along the medial forebrain bundle and acts on serotonin receptors. In the peripheral nervous system (such as in the gut wall) serotonin regulates vascular tone. | 1 | Applied and Interdisciplinary Chemistry |
In the technique of horizontal stone closures, stone is deployed from both sides into the closing gap. The stone must be heavy enough to counter the increased velocity that results from the reduced flow profile. An added complication is the creation of turbulent eddies, which lead to further scouring of the seabed. It is therefore critical to lay a foundation of stone prior to commencing the closure. The closure of the Zuiderzee in 1932, as depicted in the attached photograph, vividly illustrates the downstream turbulence at the closing gap. Notably, during the Afsluitdijk closure, boulder clay was utilised in a manner akin to stone, which circumvented the need for costly imports of armourstone.
In the Netherlands, horizontal stone closures have been relatively uncommon due to the high costs associated with armourstone and the prerequisite soil protection. Conversely, in countries where stone is more affordable and soils are less prone to erosion, horizontal stone closures are more frequently employed. A notable instance of this method was the closure of the Saemangeum estuary in South Korea, where a scarcity of heavy stone led to the innovative use of stone packed in steel nets as dumping material. The logistical challenges of transporting and deploying stone, especially within the constraints of a tight timeframe to prevent excessive bottom erosion, often pose significant challenges. | 1 | Applied and Interdisciplinary Chemistry |
Suppose an analyst is determining the concentration of silver in samples of waste solution in photographic film by atomic absorption spectroscopy. Using the calibration curve method, the analyst can calibrate the spectrometer with a pure silver aqueous solutions, and use the calibration graph to determine the amount of silver present in the waste samples. This method, however, assumes the pure aqueous solution of silver and a photographic waste sample have the same matrix and therefore the waste samples are free of matrix effect.
Matrix effects occur even with methods such as plasma spectrometry, which have a reputation for being relatively free from interferences. As such, analyst would use standard additions in this case.
For standard additions, equal volumes of the sample solutions are taken, and all are separately spiked with varying amounts of the analyte – 0, 1, 2, 3, 4, 5 mL, where 0 mL addition is a pure test sample solution. All solutions are then diluted to the same volume of 25 mL, by using the same solvent as the one used to prepare the spiking solutions. Each prepared solution is then analyzed using an atomic absorption spectrometer. The resulting signals and corresponding spiked silver concentrations are plotted, with concentration on the x-axis and the signal on the y-axis. A regression line is calculated through least squares analysis and the x-intercept of the line is determined by the ratio of the y-intercept and the slope of the regression line. This x-intercept represents the silver concentration of the test sample where there is no standard solution added. | 0 | Theoretical and Fundamental Chemistry |
For more details on this topic, see flow cytometry
Since the optical identity of each microsphere is known, the quantification of target samples hybridized to the microspheres can be achieved by comparing the relative intensity of target markers in one set of microspheres to target markers in another set of microspheres using flow cytometry. Microspheres can be sorted based using both their unique optical properties and level of hybridization to the target sequence. | 1 | Applied and Interdisciplinary Chemistry |
The National Standard Examination in Chemistry or NSEC is an examination in chemistry for higher secondary school students in India, usually conducted in the end of November. The examination is organized by the Indian Association of Chemistry Teachers. Over 30,000 students, mainly from Standard 12, sit for this examination. | 1 | Applied and Interdisciplinary Chemistry |
In the late 1960s, John Vane of the Royal College of Surgeons of England was working on mechanisms by which the body regulates blood pressure. He was joined by Sérgio Henrique Ferreira of Brazil, who had been studying the venom of a Brazilian pit viper, the jararaca (Bothrops jararaca), and brought a sample of the vipers venom. Vanes team found that one of the venom's peptides selectively inhibited the action of angiotensin-converting enzyme (ACE), which was thought to function in blood pressure regulation; the snake venom functions by severely depressing blood pressure. During the 1970s, ACE was found to elevate blood pressure by controlling the release of water and salts from the kidneys.
Captopril, an analog of the snake venom's ACE-inhibiting peptide, was first synthesized in 1975 by three researchers at the U.S. drug company E.R. Squibb & Sons Pharmaceuticals (now Bristol-Myers Squibb): Miguel Ondetti, Bernard Rubin, and David Cushman. Squibb filed for U.S. patent protection on the drug in February 1976, which was granted in September 1977, and captopril was approved for medical use in 1980. It was the first ACE inhibitor developed and was considered a breakthrough both because of its mechanism of action and also because of the development process. In the 1980s, Vane received the Nobel prize and was knighted for his work and Ferreira received the National Order of Scientific Merit from Brazil.
The development of captopril was among the earliest successes of the revolutionary concept of structure-based drug design. The renin–angiotensin–aldosterone system had been extensively studied in the mid-20th century, and this system presented several opportune targets in the development of novel treatments for hypertension. The first two targets that were attempted were renin and ACE. Captopril was the culmination of efforts by Squibb's laboratories to develop an ACE inhibitor.
Ondetti, Cushman, and colleagues built on work that had been done in the 1960s by a team of researchers led by John Vane at the Royal College of Surgeons of England. The first breakthrough was made by Kevin K.F. Ng in 1967, when he found the conversion of angiotensin I to angiotensin II took place in the pulmonary circulation instead of in the plasma. In contrast, Sergio Ferreira found bradykinin disappeared in its passage through the pulmonary circulation. The conversion of angiotensin I to angiotensin II and the inactivation of bradykinin were thought to be mediated by the same enzyme.
In 1970, using bradykinin potentiating factor (BPF) provided by Sergio Ferreira, Ng and Vane found the conversion of angiotensin I to angiotensin II was inhibited during its passage through the pulmonary circulation. BPF was later found to be a peptide in the venom of a lancehead viper (Bothrops jararaca), which was a “collected-product inhibitor” of the converting enzyme. Captopril was developed from this peptide after it was found via QSAR-based modification that the terminal sulfhydryl moiety of the peptide provided a high potency of ACE inhibition.
Captopril gained FDA approval on April 6, 1981. The drug became a generic medicine in the U.S. in February 1996, when the market exclusivity held by Bristol-Myers Squibb for captopril expired. | 0 | Theoretical and Fundamental Chemistry |
Other equations now exist that refine the original Hammett equation: the Swain–Lupton equation, the Taft equation, the Grunwald–Winstein equation, and the Yukawa–Tsuno equation. An equation that addresses stereochemistry in aliphatic systems has also been developed. | 0 | Theoretical and Fundamental Chemistry |
The primary sources of jet noise for a high-speed air jet (meaning when the exhaust velocity exceeds about 100 m/s; 360 km/h; 225 mph) are "jet mixing noise" and, for supersonic flow, shock associated noise. Acoustic sources within the "jet pipe" also contribute to the noise, mainly at lower speeds, which include combustion noise, and sounds produced by interactions of a turbulent stream with fans, compressors, and turbine systems.
The jet mixing sound is created by the turbulent mixing of a jet with the ambient fluid, in most cases, air. The mixing initially occurs in an annular shear layer, which grows with the length of the nozzle. The mixing region generally fills the entire jet at four or five diameters from the nozzle. The high-frequency components of the sound are mainly stationed close to the nozzle, where the dimensions of the turbulence eddies are small. Further down the jet, where the eddy size is similar to the jet diameter, is where lower frequency begins.
In Supersonic, or choked jets there are cells through which the flow continuously expands and contracts. Several of these "shock cells" can be seen extending up to ten jet diameters from the nozzle and are responsible for two additional components of jet noise, screech tones, and broadband shock associated noises. Screech is produced by a feedback mechanism in which a disturbance convecting in the shear layer generates sound as it traverses the standing system of shock waves in the jet. Even though screech is a side effect of the jet's flight, it can be suppressed by an appropriate design for a nozzle.
Aircraft noise is also sometimes called jet noise when emanating from jet aircraft, regardless of the mechanism of noise production. | 1 | Applied and Interdisciplinary Chemistry |
When LCA is included in a production simulation model, there is a bigger need for output information to perform the calculations. To be able to allocate environmental load that origins from the facilities the product that used the facility need to be traced. Environmental load that origin form the maintenance needs to be allocated based on the machines use of the maintenance. Machines that use other resources as compressed air or other supporting machines needs to be associated to trace the usage of those resources to be able to allocate the environmental load to the products that used the machine.
Andersson, J et al. (2012) proposed to model the machines and resources in a hierarchy. The approach is based on that all product types have attributes with weight and size. The attributes is used together with the time the product has been in each resources to allocate the environmental load to all products using the resource at the same time. A product that is using a machine is also using the machines and facilities in the upper hierarchy. The approach supports increasingly detailed modeling. The modeler increase the level of detail by model each box in greater detail in a lower lever in the hierarchy. The modeler can in other nodes stay at a brief level with less dynamics. | 1 | Applied and Interdisciplinary Chemistry |
Ferrotitanium is a ferroalloy, an alloy of iron and titanium with between 10 and 20% iron and 45–75% titanium and sometimes a small amount of carbon. It is used in steelmaking as a cleansing agent for iron and steel; the titanium is highly reactive with sulfur, carbon, oxygen, and nitrogen, forming insoluble compounds and sequestering them in slag, and is therefore used for deoxidizing, and sometimes for desulfurization and denitrogenation. In steelmaking, the addition of titanium yields metal with finer grain structure. Ferrotitanium can be manufactured by mixing titanium sponge and scrap with iron and melting them together in an induction furnace. Ferrotitanium powder can be also used as a fuel in some pyrotechnic compositions. | 1 | Applied and Interdisciplinary Chemistry |
The process efficiency of sensor-based ore sorting is described in detail by C. Robben in 2014. The total process efficiency is subdivided into the following sub-process efficiencies; Platform efficiency, preparation efficiency, presentation efficiency, detection efficiency and separation efficiency. All the sub-process contribute to the total process efficiency, of course in combination with the liberation characteristics of the bulk material that the technology is applied to. The detailed description of the sib-processes and their contribution to the total process efficiency can be found in the literature. | 0 | Theoretical and Fundamental Chemistry |
As the size of a compact flange increases it becomes relatively increasingly heavy and complex resulting in high procurement, installation and maintenance costs.
Large flange diameters in particular are difficult to work with, and inevitably require more space and have a more challenging handling and installation procedure, particularly on remote installations such as oil rigs.
The design of the flange face includes two independent seals. The first seal is created by application of seal seating stress at the flange heel, but it is not straight forward to ensure the function of this seal.
Theoretically, the heel contact will be maintained for pressure values up to 1.8 times the flange rating at room temperature.
Theoretically, the flange also remains in contact along its outer circumference at the flange faces for all allowable load levels that it is designed for.
The main seal is the IX seal ring. The seal ring force is provided by the elastic stored energy in the stressed seal ring. Any heel leakage will give internal pressure acting on the seal ring inside intensifying the sealing action. This however requires the IX ring to be retained in the theoretical location in the ring groove which is difficult to ensure and verify during installation.
The design aims at preventing exposure to oxygen and other corrosive agents. Thus, this prevents corrosion of the flange faces, the stressed length of the bolts and the seal ring. This however depends on the outer dust rim to remain in satisfactory contact and that the inside fluid is not corrosive in case of leaking into the bolt circle void. | 1 | Applied and Interdisciplinary Chemistry |
More precise measurement techniques developed in the late 1990s have allowed for a good understanding of how dissolved organic carbon is distributed in marine environments both vertically and across the surface. It is now understood that dissolved organic carbon in the ocean spans a range from very labile to very recalcitrant (refractory). The labile dissolved organic carbon is mainly produced by marine organisms and is consumed in the surface ocean, and consists of sugars, proteins, and other compounds that are easily used by marine bacteria. Recalcitrant dissolved organic carbon is evenly spread throughout the water column and consists of high molecular weight and structurally complex compounds that are difficult for marine organisms to use such as the lignin, pollen, or humic acids. As a result, the observed vertical distribution consists of high concentrations of labile DOC in the upper water column and low concentrations at depth.
In addition to vertical distributions, horizontal distributions have been modeled and sampled as well. In the surface ocean at a depth of 30 meters, the higher dissolved organic carbon concentrations are found in the South Pacific Gyre, the South Atlantic Gyre, and the Indian Ocean. At a depth of 3,000 meters, highest concentrations are in the North Atlantic Deep Water where dissolved organic carbon from the high concentration surface ocean is removed to depth. While in the northern Indian Ocean high DOC is observed due to high fresh water flux and sediments. Since the time scales of horizontal motion along the ocean bottom are in the thousands of years, the refractory dissolved organic carbon is slowly consumed on its way from the North Atlantic and reaches a minimum in the North Pacific. | 1 | Applied and Interdisciplinary Chemistry |
Common examples of RATs or RADTs include:
* COVID-19 testing-related rapid tests
* Rapid strep tests (for streptococcal antigens)
* Rapid influenza diagnostic tests (RIDTs) (for influenza virus antigens)
* Malaria antigen detection tests (for Plasmodium antigens) | 1 | Applied and Interdisciplinary Chemistry |
Lysophosphatidylinositol (LPI, lysoPI), or -α-lysophosphatidylinositol, is an endogenous lysophospholipid and endocannabinoid neurotransmitter. LPI, along with its 2-arachidonoyl- derivative, 2-arachidonoyl lysophosphatidylinositol (2-ALPI), have been proposed as the endogenous ligands of GPR55. | 1 | Applied and Interdisciplinary Chemistry |
A host–guest complex, also known as a donor–acceptor complex, may be formed from a Lewis base, B, and a Lewis acid, A. The host may be either a donor or an acceptor. In biochemistry host–guest complexes are known as receptor-ligand complexes; they are formed primarily by non-covalent bonding. Many host–guest complexes has 1:1 stoichiometry, but many others have more complex structures. The general equilibrium can be written as
:p A + q B AB
The study of these complexes is important for supramolecular chemistry and molecular recognition. The objective of these studies is often to find systems with a high binding selectivity of a host (receptor) for a particular target molecule or ion, the guest or ligand. An application is the development of chemical sensors. Finding a drug which either blocks a receptor, an antagonist which forms a strong complex the receptor, or activate it, an agonist, is an important pathway to drug discovery. | 0 | Theoretical and Fundamental Chemistry |
The name "katal" has been used for decades. The first proposal to make it an SI unit came in 1978, and it became an official SI unit in 1999. The name comes from the Ancient Greek κατάλυσις (katalysis), meaning "dissolution"; the word "catalysis" itself is a Latinized form of the Greek word. | 0 | Theoretical and Fundamental Chemistry |
Another evidence of quantum spin liquid was observed in a 2-dimensional material in August 2015. The researchers of Oak Ridge National Laboratory, collaborating with physicists from the University of Cambridge, and the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, measured the first signatures of these fractional particles, known as Majorana fermions, in a two-dimensional material with a structure similar to graphene. Their experimental results successfully matched with one of the main theoretical models for a quantum spin liquid, known as a Kitaev honeycomb model. | 0 | Theoretical and Fundamental Chemistry |
A simple nitrite test can be performed by adding 4 M sulfuric acid to the sample until acidic, and then adding 0.1 M iron(II) sulfate to the solution. A positive test for nitrite is indicated by a dark brown solution, arising from the iron-nitric oxide complex ion. This test is related to the brown ring test for the nitrate ion, which forms the same complex in a ring. In contrast, nitrites turn the whole solution brown and therefore interfere with that test. | 0 | Theoretical and Fundamental Chemistry |
Inversion of tetrahedra occurs widely in organic and main group chemistry. The Walden inversion illustrates the stereochemical consequences of inversion at carbon. Nitrogen inversion in ammonia also entails transient formation of planar . | 0 | Theoretical and Fundamental Chemistry |
This chemogenetic technique can be used for remote manipulation of cells, in particular excitable cells like neurons, both in vitro and in vivo with the administration of specific ligands. Similar techniques in this field include thermogenetics and optogenetics, the control of neurons with temperature or light, respectively.
Viral expression of DREADD proteins, both in-vivo enhancers and inhibitors of neuronal function, have been used to bidirectionally control behaviors in mice (e.g odor discrimination). Due to their ability to modulate neuronal activity, DREADDs are used as a tool to evaluate both the neuronal pathways and behaviors associated with drug-cues and drug addiction. | 1 | Applied and Interdisciplinary Chemistry |
The Frozen Ark is a charitable frozen zoo project created jointly by the Zoological Society of London, the Natural History Museum and University of Nottingham. The project aims to preserve the DNA and living cells of endangered species to retain the genetic knowledge for the future. The Frozen Ark collects and stores samples taken from animals in zoos and those threatened with extinction in the wild. Its current director is Michael W. Bruford (Cardiff University). The Frozen Ark was a finalist for the Saatchi & Saatchi Award for World Changing Ideas in 2006.
The project was founded by Ann Clarke, her husband Bryan Clarke and Dame Anne McLaren. Since Bryan Clarkes death in 2014, the Frozen Arks interim director has been Mike Bruford. | 1 | Applied and Interdisciplinary Chemistry |
Moissan was born in Paris on 28 September 1852, the son of a minor officer of the eastern railway company, Francis Ferdinand Moissan, and a seamstress, Joséphine Améraldine (née Mitel). His mother was of Jewish descent, his father was not. In 1864 they moved to Meaux, where he attended the local school. During this time, Moissan became an apprentice clockmaker. However, in 1870, Moissan and his family moved back to Paris due to war against Prussia. Moissan was unable to receive the grade universitaire necessary to attend university. After spending a year in the army, he enrolled at the Ecole Superieure de Pharmacie de Paris. | 0 | Theoretical and Fundamental Chemistry |
The polyhedral symbol is sometimes used in coordination chemistry to indicate the approximate geometry of the coordinating atoms around the central atom. One or more italicised letters indicate the geometry, e.g. TP-3 which is followed by a number that gives the coordination number of the central atom. The polyhedral symbol can be used in naming of compounds, in which case it is followed by the configuration index. | 0 | Theoretical and Fundamental Chemistry |
Arabic al-kīmiyaʾ or al-khīmiyaʾ ( or ), according to some, is thought to derive from the Koine Greek word khymeia () meaning "the art of alloying metals, alchemy"; in the manuscripts, this word is also written khēmeia () or kheimeia (), which is the probable basis of the Arabic form. According to Mahn, the Greek word χυμεία khumeia originally meant "cast together", "casting together", "weld", "alloy", etc. (cf. Gk. kheein () "to pour"; khuma (), "that which is poured out, an ingot"). Assuming a Greek origin, chemistry is defined as follows:
:Chemistry, from the Greek word (khēmeia) meaning "cast together" or "pour together", is the science of matter at the atomic to molecular scale, dealing primarily with collections of atoms, such as molecules, crystals, and metals. | 1 | Applied and Interdisciplinary Chemistry |
The CBP of this type consists in three domains:
* N-terminal NTPase binding domain
* Central Helix-Turn-Helix (HTH) domain
* C-terminal dimer-domain | 1 | Applied and Interdisciplinary Chemistry |
* Four mobile barriers are constructed at the lagoon inlets (two at the Lido inlet, one at Malamocco and one at Chioggia)
* The project has a total of of mobile barriers
* There are of linear worksites on land and at sea
* MOSE has a total of 78 gates
* The smallest gate is (Lido–Treporti row)
* The largest gate is (Malamocco row)
* One lock for large shipping at the Malamocco inlet enables port activities to continue when the gates are in operation
* Three small locks (two at Chioggia and one at Lido-Treporti) allow the transit of fishing boats and other smaller vessels when the gates are in operation
* There are 156 hinges, two for each gate and a number of reserve elements
* Each hinge weighs 42 tons
* The gates are designed to withstand a maximum tide (to date, the highest tide has been )
* MOSE is designed to cope with a rise in sea level
* 30 minutes are required to raise the gates
* 15 minutes are required to lower the gates back into their housing structures
* During a tidal event, the inlets remain closed for 4 to 5 hours, including barrier raising and lowering times
* The site currently employs 4,000 people directly or indirectly | 1 | Applied and Interdisciplinary Chemistry |
Abnormal basal metabolic rate refers to a high or low basal metabolic rate (BMR). It has numerous causes, both physiological (part of the body's normal function) and pathological (associated with disease). | 1 | Applied and Interdisciplinary Chemistry |
Carbon-14 can also be produced by other neutron reactions, including in particular Carbon-13|(n,γ) and Oxygen-17|(n,α) with thermal neutrons, and Nitrogen-15|(n,d) and Oxygen-16|(n,) with fast neutrons. The most notable routes for production by thermal neutron irradiation of targets (e.g., in a nuclear reactor) are summarized in the table.
Carbon-14 may also be radiogenic (cluster decay of , , ). However, this origin is extremely rare. | 0 | Theoretical and Fundamental Chemistry |
Recently, functional experiments have revealed many novel functional roles of RNA modifications. Most of the RNA modifications are found on transfer-RNA and ribosomal-RNA, but also eukaryotic mRNA has been shown to be modified with multiple different modifications. 17 naturally occurring modifications on mRNA have been identified, from which the N6-methyladenosine is the most abundant and studied. mRNA modifications are linked to many functions in the cell. They ensure the correct maturation and function of the mRNA, but also at the same time act as part of cells immune system. Certain modifications like 2’O-methylated nucleotides has been associated with cells ability to distinguish own mRNA from foreign RNA. For example, mA has been predicted to affect protein translation and localization, mRNA stability, alternative polyA choice and stem cell pluripotency. Pseudouridylation of nonsense codons suppresses translation termination both in vitro and in vivo', suggesting that RNA modification may provide a new way to expand the genetic code. 5-methylcytosine on the other hand has been associated with mRNA transport from the nucleus to the cytoplasm and enhancement of translation. These functions of mC are not fully known and proven but one strong argument towards these functions in the cell is the observed localization of mC to translation initiation site. Importantly, many modification enzymes are dysregulated and genetically mutated in many disease types. For example, genetic mutations in pseudouridine synthases cause mitochondrial myopathy, sideroblastic anemia (MLASA) and dyskeratosis congenital.
Compared to the modifications identified from other RNA species like tRNA and rRNA, the amount of identified modifications on mRNA is very small. One of the biggest reasons why mRNA modifications are not so well known is missing research techniques. In addition to the lack of identified modifications, the knowledge of associated proteins is also behind other RNA species. Modifications are results of specific enzyme interactions with the RNA molecule. Considering mRNA modifications most of the known related enzymes are the writer enzymes that add the modification on the mRNA. The additional groups of enzymes readers and erasers are for most of the modifications either poorly known of not known at all. For these reasons there has been during the past decade huge interest in studying these modifications and their function. | 1 | Applied and Interdisciplinary Chemistry |
The release of radioactivity from the used fuel is greatly controlled by the volatility of the elements. At Chernobyl much of the xenon and iodine was released while much less of the zirconium was released. The fact that only the more volatile fission products are released with ease will greatly retard the release of radioactivity in the event of an accident which causes serious damage to the core. Using two sources of data it is possible to see that the elements which were in the form of gases, volatile compounds or semi-volatile compounds (such as CsI) were released at Chernobyl while the less volatile elements which form solid solutions with the fuel remained inside the reactor fuel.
According to the OECD NEA report on Chernobyl (ten years on), the following proportions of the core inventory were released. The physical and chemical forms of the release included gases, aerosols and finely fragmented solid fuel. According to some research the ruthenium is very mobile when the nuclear fuel is heated with air. This mobility has been more evident in reprocessing, with related releases of ruthenium, the most recent being the airborne radioactivity increase in Europe in autumn 2017, as with the ionizing radiation environment of spent fuel and the presence of oxygen, radiolysis-reactions can generate the volatile compound ruthenium(VIII) oxide, which has a boiling point of approximately and is a strong oxidizer, reacting with virtually any fuel/hydrocarbon, that are used in PUREX.
Some work on TRISO fuel heated in air, with the respective encapsulation of nuclides, has been published. | 0 | Theoretical and Fundamental Chemistry |
The Ro52 gene is officially termed TRIM21, as it is a member of the tripartite motif protein (TRIM) family, qualified by its RING and B-box domains. The protein is typically located in the cytoplasm, though it can move to the nucleus in the presence of pro-inflammatory signals, and it can also be expressed on the cell surface. There is evidence that Ro52 itself is a cytosolic Fc receptor. Ro52 is a regulatory protein, and negatively moderates inflammatory response, such as the secretion of pro-inflammatory cytokines in the interleukin and INF families. Ro52 can both regulate and be induced by INF cytokines. Loss of function or blockage of Ro52 results in uncontrolled inflammation at the onset of injury or disease. Patients with SLE and SS not only show elevated levels of Anti-Ro antibodies, but also elevated levels of Ro52.
Ro52 has one primary epitope to which anti-Ro/SSA binds, independent of the autoimmune disease. The most common domain anti-Ro52 targets is the coiled coil (cc) domain, as well as the RING and B-box domains.
Ro52 does not bind to small cytoplasmic non-coding RNA strands (hY-RNA). The notion that Ro52 formed a complex with Y RNA resulted from studies that suggesting that Ro52 and Ro60 formed a complex together.
Ro52 may impact the pathogenesis of autoimmune disease: patients with SLE and SS have been shown to express high levels of Ro52 transcripts. Though Ro52 and Ro60 are often seen in elevated levels together in patients with autoimmune disease, Ro52 manifests without Ro60 in SS. Additionally, Anti-Ro52 antibody has been identified at elevated levels in patients with interstitial lung disease, as well as in autoimmune hepatitis type 1. | 1 | Applied and Interdisciplinary Chemistry |
The different reactivity of halogens as compared to OH and ozone has broad impacts on atmospheric chemistry. These include near complete removal and deposition of mercury, alteration of oxidation fates for organic gases, and export of bromine into the free troposphere. The deposition of reactive gaseous mercury (RGM) in snow from oxidation by enhanced halogens increases the bioavailability of mercury. Recent changes in the climate of the Arctic and state of the Arctic sea ice cover are likely to have strong effects on halogen activation and ozone depletion events. Human-induced climate change affects the quantity of snow and ice cover in the Arctic, altering the intensity of nitrogen oxide emissions. Increment in background levels of nitrogen oxide apparently strengthens the consumption of ozone and the enhancement of halogens. | 1 | Applied and Interdisciplinary Chemistry |
Tin-silver-copper (Sn-Ag-Cu, also known as SAC), is a lead-free (Pb-free) alloy commonly used for electronic solder. It is the main choice for lead-free surface-mount technology (SMT) assembly in the industry, as it is near eutectic, with adequate thermal fatigue properties, strength, and wettability. Lead-free solder is gaining much attention as the environmental effects of lead in industrial products is recognized, and as a result of Europe's RoHS legislation to remove lead and other hazardous materials from electronics. Japanese electronics companies have also looked at Pb-free solder for its industrial advantages.
Typical alloys are 3–4% silver, 0.5–0.7% copper, and the balance (95%+) tin. For example, the common "SAC305" solder is 3.0% silver and 0.5% copper. Cheaper alternatives with less silver are used in some applications, such as SAC105 and SAC0307 (0.3% silver, 0.7% copper), at the expense of a somewhat higher melting point. | 1 | Applied and Interdisciplinary Chemistry |
The ridges enhance the quantum reflection from the surface, reducing the effective constant of the van der Waals attraction of atoms to the surface. Such interpretation leads to the estimate of the reflectivity
where is width of the ridges, is distance between ridges, is grazing angle, and is wavenumber and is coefficient of reflection of atoms with wavenumber from a flat surface at the normal incidence. Such estimate predicts the enhancement of the reflectivity at the increase of period ; this estimate is valid at . See quantum reflection for the approximation (fit) of the function . | 0 | Theoretical and Fundamental Chemistry |
Member countries include: Australia, Austria, Belgium, Brazil, Canada, Czech Republic, China, Denmark, Finland, France, Germany, Hungary, Italy, Japan, Luxembourg, Netherlands, Norway, Portugal, Slovakia, Slovenia, South Korea, Spain, Sweden, Switzerland, and the United States. | 1 | Applied and Interdisciplinary Chemistry |
SIR4 is involved in scaffolding the assembly of silenced chromatin. It binds to DNA with high affinity, but low specificity. It is most stable when co-expressed with SIR2, but neither SIR2 nor SIR3 are required for it to operate at the telomeres. Each half of the SIR4 protein has distinct responsibilities in heterochromatin spreading. SIR4s N-terminus is required for telomeric silencing, but not for homothallic mating-type (HM) silencing. Conversely, its C-terminus supports HM but not telomeric repression. The N-terminus is positively charged and can be recruited to the telomeric repression site by SIR1 and YKU80. The C-terminus contains the coiled-coil region, which interacts with SIR3 in the heterotrimeric SIR complex and can also interact with RAP1 and YKU70 for recruitment to the telomeric region of the chromosome. The C-terminus also contains the SIR2-interacting domain (SID), where SIR4 can bind to the extended N-terminus of SIR2. SIR2 can catalyze reactions without being bound to SIR4, but SIR2s catalytic activity is enhanced when interacting with SIR4. | 1 | Applied and Interdisciplinary Chemistry |
Cytochemistry is the branch of cell biology dealing with the detection of cell constituents by means of biochemical analysis and visualization techniques. This is the study of the localization of cellular components through the use of staining methods. The term is also used to describe a process of identification of the biochemical content of cells. Cytochemistry is a science of localizing chemical components of cells and cell organelles on thin histological sections by using several techniques like enzyme localization, micro-incineration, micro-spectrophotometry, radioautography, cryo-electron microscopy, X-ray microanalysis by energy-dispersive X-ray spectroscopy, immunohistochemistry and cytochemistry, etc. | 1 | Applied and Interdisciplinary Chemistry |
*The first major phosgene-related incident happened in May 1928 when eleven tons of phosgene escaped from a war surplus store in central Hamburg. Three hundred people were poisoned, of whom ten died.
*In the second half of 20th century several fatal incidents implicating phosgene occurred in Europe, Asia and the US. Most of them have been investigated by authorities and the outcome made accessible to the public. For example, phosgene was initially blamed for the Bhopal disaster, but investigations proved methyl isocyanate to be responsible for the numerous poisonings and fatalities.
* Recent major incidents happened in January 2010 and May 2016. An accidental release of phosgene gas at a DuPont facility in West Virginia killed one employee in 2010. The US Chemical Safety Board released a video detailing the accident. Six years later, a phosgene leak occurred in a BASF plant in South Korea, where a contractor inhaled a lethal dose of phosgene.
*2023 Ohio train derailment: A freight train carrying vinyl chloride derailed and burned in East Palestine, Ohio, releasing phosgene and hydrogen chloride into the air and contaminating the Ohio River. | 0 | Theoretical and Fundamental Chemistry |
Targeted drug delivery, sometimes called smart drug delivery, is a method of delivering medication to a patient in a manner that increases the concentration of the medication in some parts of the body relative to others. This means of delivery is largely founded on nanomedicine, which plans to employ nanoparticle-mediated drug delivery in order to combat the downfalls of conventional drug delivery. These nanoparticles would be loaded with drugs and targeted to specific parts of the body where there is solely diseased tissue, thereby avoiding interaction with healthy tissue. The goal of a targeted drug delivery system is to prolong, localize, target and have a protected drug interaction with the diseased tissue. The conventional drug delivery system is the absorption of the drug across a biological membrane, whereas the targeted release system releases the drug in a dosage form. The advantages to the targeted release system is the reduction in the frequency of the dosages taken by the patient, having a more uniform effect of the drug, reduction of drug side-effects, and reduced fluctuation in circulating drug levels. The disadvantage of the system is high cost, which makes productivity more difficult, and the reduced ability to adjust the dosages.
Targeted drug delivery systems have been developed to optimize regenerative techniques. The system is based on a method that delivers a certain amount of a therapeutic agent for a prolonged period of time to a targeted diseased area within the body. This helps maintain the required plasma and tissue drug levels in the body, thereby preventing any damage to the healthy tissue via the drug. The drug delivery system is highly integrated and requires various disciplines, such as chemists, biologists, and engineers, to join forces to optimize this system. | 1 | Applied and Interdisciplinary Chemistry |
Dorenfeldt found her first job in 1920 as an assistant at the chemistry laboratory at Royal Frederick University (now University of Oslo). A few months later, she was promoted to a secretary-like position, from which she could perform research and teach. Soon she was investigating the atomic weight of chlorine while working with the radiochemist and associate professor Ellen Gleditsch, who had previously worked with Marie Curie in Paris. Dorenfeldt helped publish their results in English, German and French.
In 1922, the university granted Dorenfeldt a scholarship so she could study at the Collège de France in Paris. While there she met and married a fellow Norwegian and changed her name to Margot Dorenfeldt Holtan. She published research using her married name as well as her maiden name.
As a wife and mother of two, Margot attended to her family but continued working in the field as a part-time secretary and chemist and, according to her own records, she also published scientific work with her husband. Throughout her life, she remained close to her father and his business interests and she took a government position in 1946 and then became an association board member from which she could help protect the interests of his pulp and paper businesses. | 0 | Theoretical and Fundamental Chemistry |
* The reduction of nitrate to nitrogen in the presence of an acid (denitrification):
* The combustion of hydrocarbons, such as in an internal combustion engine, produces water, carbon dioxide, some partially oxidized forms such as carbon monoxide, and heat energy. Complete oxidation of materials containing carbon produces carbon dioxide.
* The stepwise oxidation of a hydrocarbon by oxygen, in organic chemistry, produces water and, successively: an alcohol, an aldehyde or a ketone, a carboxylic acid, and then a peroxide. | 0 | Theoretical and Fundamental Chemistry |
A potential challenge of aquasome-based drug delivery could be toxicity due to burst release of drugs if poorly absorbed on the carbohydrate coat. Aquasomes can also be expensive to formulate, particularly due to their step-by-step synthesis. Careful attention is needed during aquasome production to tune the thickness of each layer, and leaching and aggregation may occur during prolonged storage of aquasomes. A physiological challenge aquasomes present is that upon their entry into the bloodstream, they may be taken up nonspecifically, leading to opsonization and phagocytic clearance by the immune system. To prevent this, aquasome surfaces can be coated with polyethylene glycol (PEG) to block opsonin binding through steric hindrance; however, the effect of PEGylation on aquasome drug release has not been sufficiently explored to enable clinical applications. Polymer degradation in different physiological environments can change the stability and drug loading of aquasomes over time, as their surface properties directly impact drug release. Aquasomes may also be challenging to scale up and prepare as it is difficult to ensure consistent formulation quality. More research is needed to demonstrate both the efficiency and safety of aquasomes in clinical use. | 0 | Theoretical and Fundamental Chemistry |
An electrical synapse is an electrically conductive link between two abutting neurons that is formed at a narrow gap between the pre- and postsynaptic cells, known as a gap junction. At gap junctions, cells approach within about 3.5 nm of each other, rather than the 20 to 40 nm distance that separates cells at chemical synapses. As opposed to chemical synapses, the postsynaptic potential in electrical synapses is not caused by the opening of ion channels by chemical transmitters, but rather by direct electrical coupling between both neurons. Electrical synapses are faster than chemical synapses. Electrical synapses are found throughout the nervous system, including in the retina, the reticular nucleus of the thalamus, the neocortex, and in the hippocampus. While chemical synapses are found between both excitatory and inhibitory neurons, electrical synapses are most commonly found between smaller local inhibitory neurons. Electrical synapses can exist between two axons, two dendrites, or between an axon and a dendrite. In some fish and amphibians, electrical synapses can be found within the same terminal of a chemical synapse, as in Mauthner cells. | 1 | Applied and Interdisciplinary Chemistry |
Another important regulator of translation is the interaction between 3′ UTR and the 5′ UTR.
The closed-loop structure inhibits translation. This has been observed in Xenopus laevis, in which eIF4E bound to the 5′ cap interacts with Maskin bound to CPEB on the 3′ UTR, creating translationally inactive transcripts. This translational inhibition is lifted once CPEB is phosphorylated, displacing the Maskin binding site, allowing for the polymerization of the PolyA tail, which can recruit the translational machinery by means of PABP. However, it is important to note that this mechanism has been under great scrutiny. | 1 | Applied and Interdisciplinary Chemistry |
Higher L1 copy numbers have been observed in the human brain compared to other organs. Studies of animal models and human cell lines have shown that L1s become active in neural progenitor cells (NPCs), and that experimental deregulation of or overexpression of L1 increases somatic mosaicism. This phenomenon is negatively regulated by Sox2, which is downregulated in NPCs, and by MeCP2 and methylation of the L1 5' UTR. Human cell lines modeling the neurological disorder Rett syndrome, which carry MeCP2 mutations, exhibit increased L1 transposition, suggesting a link between L1 activity and neurological disorders. Current studies are aimed at investigating the potential roles of L1 activity in various neuropsychiatric disorders including schizophrenia, autism spectrum disorders, epilepsy, bipolar disorder, Tourette syndrome, and drug addiction. L1s are also highly expressed in octopus brain, suggesting a convergent mechanism in complex cognition. | 1 | Applied and Interdisciplinary Chemistry |
The Beilby Medal and Prize recipients since 1930 are:
* 2023 – Charlotte Vogt
* 2022 – Sahika Inal
* 2021 – Pola Goldberg Oppenheimer
* 2020 – Jin Xuan
* 2019 – Prashant K. Jain
* 2014 – Javier Pérez-Ramírez
* 2009 – Zhenan Bao
* 2008 – Neil McKeown
* 2005 – Simon R. Biggs, Nilay Shah
* 2003 – Peter Bruce
* 2002 – No award
* 2001 – Alfred Cerezo
* 2000 – Zheng Xiao Guo
* 1999 – John T. S. Irvine, Anthony J. Ryan
* 1998 – Costos C. Pantelides
* 1997 – Richard A. Williams
* 1996 – Paul J. Luckham
* 1995 – Lynn F. Gladden
* 1993 – Howard A. Chase, David C. Sherrington
* 1992 – R. C. Brown
* 1991 – Geoffrey J. Ashwell
* 1990 – R. F. Dalton
* 1989 – No award
* 1988 – No award
* 1987 – G. E. Thompson
* 1986 – Malcolm Robert Mackley
* 1985 – George D. W. Smith
* 1984 – A. Grint
* 1981 – Derek John Fray, R. M. Nedderman
* 1980 – James Barrie Scuffham
* 1979 – Stephen F. Bush
* 1978 – John Christopher Scully
* 1977 – James E. Castle
* 1976 – Ian Fells
* 1975 – Peter Roland Swann
* 1973 – Julian Szekely, G. C. Wood
* 1972 – Frank Pearson Lees
* 1971 – John Howard Purnell
* 1970 – Albert R. C. Westwood
* 1969 – Raymond Edward Smallman
* 1968 – J. Mardon
* 1967 – Anthony Kelly
* 1966 – J. F. Davidson
* 1965 – J. A. Charles
* 1964 – Peter L. Pratt
* 1963 – Robert Honeycombe, R. W. B. Nurse
* 1961 – C. Edeleanu, John Nutting
* 1957 – B. E. Hopkins, Edmund C. Potter
* 1956 – R. W. Kear
* 1955 – F. D. Richardson, F. Wormwell
* 1954 – H. K. Hardy, Sir James Woodham Menter
* 1952 – T. V. Arden
* 1951 – Kenneth Henderson Jack, W. A. Wood
* 1950 – W. A. Baker, G. Whittingham
* 1949 – Frank R. N. Nabarro, C. E. Ransley,
* 1948 – A. Stuart C. Lawrence
* 1947 – Geoffrey Vincent Raynor, G. R. Rigby
* 1940 – F. M. Lea
* 1938 – Frank Philip Bowden, B. Jones
* 1937 – Bernard Scott Evans, William Harold Juggins Vernon
* 1934 – William Hume-Rothery, E. A. Rudge
* 1933 – Constance Tipper, Arthur Joseph Victor Underwood
* 1932 – Walter James Rees, W. R. Schoeller
* 1930 – , Ulick Richardson Evans | 1 | Applied and Interdisciplinary Chemistry |
Historically, there was a tidal bore on the Gulf of California in Mexico at the mouth of the Colorado River. It formed in the estuary about Montague Island and propagated upstream. It was once very strong, but diversions of the river for irrigation have weakened the flow of the river to the point the tidal bore has nearly disappeared. | 1 | Applied and Interdisciplinary Chemistry |
The eukaryotic genome is organized into a compact chromatin structure that allows only regulated access to DNA. The chromatin structure can be globally "open" and more transcriptionally permissive, or globally "condensed" and transcriptionally inactive. The former (euchromatin) is lightly packed and rich in genes under active transcription. The latter (heterochromatin) includes gene-poor regions such as telomeres and centromeres but also regions with normal gene density but transcriptionally silenced. Transcription can be silenced by histone modification (deacetylation and methylation), RNA interference, and/or DNA methylation.
The gene expression patterns that define cell identity are inherited through cell division. This process is called epigenetic regulation. DNA methylation is reliably inherited through the action of maintenance methylases that modify the nascent DNA strand generated by replication. In mammalian cells, DNA methylation is the primary marker of transcriptionally silenced regions. Specialized proteins can recognize the marker and recruit histone deacetylases and methylases to re-establish the silencing. Nucleosome histone modifications could also be inherited during cell division, however, it is not clear whether it can work independently without the direction by DNA methylation. | 1 | Applied and Interdisciplinary Chemistry |
Biocatalysis is used to produce a number of food products. More than five biilion tons of high fructose corn syrup are produced annually by the action of the immobilized enzyme glucose isomerase of corn-derived glucose. Emerging technologies are numerous, including enzymes for clarifying or debittering of fruit juices.
A variety of potentially useful chemicals are obtained by engineered plants. Bioremediation is a green route to biodegradation. | 1 | Applied and Interdisciplinary Chemistry |
Lithium's therapeutic effects are thought to be partially attributable to its interactions with several signal transduction mechanisms. The cyclic AMP secondary messenger system is shown to be modulated by lithium. Lithium was found to increase the basal levels of cyclic AMP but impair receptor coupled stimulation of cyclic AMP production. It is hypothesized that the dual effects of lithium are due to the inhibition of G-proteins that mediate cyclic AMP production. Over a long period of lithium treatment, cyclic AMP and adenylate cyclase levels are further changed by gene transcription factors. | 1 | Applied and Interdisciplinary Chemistry |
Transition metal acyl complexes describes organometallic complexes containing one or more acyl (RCO) ligands. Such compounds occur as transient intermediates in many industrially useful reactions, especially carbonylations. | 0 | Theoretical and Fundamental Chemistry |
In the field of fluid dynamics, a Rankine half body is a feature of fluid flow discovered by Scottish physicist and engineer William Rankine that is formed when a fluid source is added to a fluid undergoing potential flow. Superposition of uniform flow and source flow yields the Rankine half body flow. A practical example of this type of flow is a bridge pier or a strut placed in a uniform stream. The resulting stream function () and velocity potential () are obtained by simply adding the stream function and velocity potential for each individual flow. | 1 | Applied and Interdisciplinary Chemistry |
A micelle () or micella () ( or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloidal suspension (also known as associated colloidal system). A typical micelle in water forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle centre.
This phase is caused by the packing behavior of single-tail lipids in a bilayer. The difficulty in filling the volume of the interior of a bilayer, while accommodating the area per head group forced on the molecule by the hydration of the lipid head group, leads to the formation of the micelle. This type of micelle is known as a normal-phase micelle (or oil-in-water micelle). Inverse micelles have the head groups at the centre with the tails extending out (or water-in-oil micelle).
Micelles are approximately spherical in shape. Other shapes, such as ellipsoids, cylinders, and bilayers, are also possible. The shape and size of a micelle are a function of the molecular geometry of its surfactant molecules and solution conditions such as surfactant concentration, temperature, pH, and ionic strength. The process of forming micelles is known as micellisation and forms part of the phase behaviour of many lipids according to their polymorphism. | 0 | Theoretical and Fundamental Chemistry |
Hydrology has been subject to investigation and engineering for millennia. Ancient Egyptians were one of the first to employ hydrology in their engineering and agriculture, inventing a form of water management known as basin irrigation. Mesopotamian towns were protected from flooding with high earthen walls. Aqueducts were built by the Greeks and Romans, while history shows that the Chinese built irrigation and flood control works. The ancient Sinhalese used hydrology to build complex irrigation works in Sri Lanka, also known for the invention of the Valve Pit which allowed construction of large reservoirs, anicuts and canals which still function.
Marcus Vitruvius, in the first century BC, described a philosophical theory of the hydrologic cycle, in which precipitation falling in the mountains infiltrated the Earth's surface and led to streams and springs in the lowlands. With the adoption of a more scientific approach, Leonardo da Vinci and Bernard Palissy independently reached an accurate representation of the hydrologic cycle. It was not until the 17th century that hydrologic variables began to be quantified.
Pioneers of the modern science of hydrology include Pierre Perrault, Edme Mariotte and Edmund Halley. By measuring rainfall, runoff, and drainage area, Perrault showed that rainfall was sufficient to account for the flow of the Seine. Mariotte combined velocity and river cross-section measurements to obtain a discharge value, again in the Seine. Halley showed that the evaporation from the Mediterranean Sea was sufficient to account for the outflow of rivers flowing into the sea.
Advances in the 18th century included the Bernoulli piezometer and Bernoullis equation, by Daniel Bernoulli, and the Pitot tube, by Henri Pitot. The 19th century saw development in groundwater hydrology, including Darcys law, the Dupuit-Thiem well formula, and Hagen-Poiseuille's capillary flow equation.
Rational analyses began to replace empiricism in the 20th century, while governmental agencies began their own hydrological research programs. Of particular importance were Leroy Shermans unit hydrograph, the infiltration theory of Robert E. Horton, and C.V. Theis aquifer test/equation describing well hydraulics.
Since the 1950s, hydrology has been approached with a more theoretical basis than in the past, facilitated by advances in the physical understanding of hydrological processes and by the advent of computers and especially geographic information systems (GIS). (See also GIS and hydrology) | 1 | Applied and Interdisciplinary Chemistry |
Plants with CAM must control storage of and its reduction to branched carbohydrates in space and time.
At low temperatures (frequently at night), plants using CAM open their stomata, molecules diffuse into the spongy mesophylls intracellular spaces and then into the cytoplasm. Here, they can meet phosphoenolpyruvate (PEP), which is a phosphorylated triose. During this time, the plants are synthesizing a protein called PEP carboxylase kinase (PEP-C kinase), whose expression can be inhibited by high temperatures (frequently at daylight) and the presence of malate. PEP-C kinase phosphorylates its target enzyme PEP carboxylase (PEP-C). Phosphorylation dramatically enhances the enzymes capability to catalyze the formation of oxaloacetate, which can be subsequently transformed into malate by NAD malate dehydrogenase. Malate is then transported via malate shuttles into the vacuole, where it is converted into the storage form malic acid. In contrast to PEP-C kinase, PEP-C is synthesized all the time but almost inhibited at daylight either by dephosphorylation via PEP-C phosphatase or directly by binding malate. The latter is not possible at low temperatures, since malate is efficiently transported into the vacuole, whereas PEP-C kinase readily inverts dephosphorylation.
In daylight, plants using CAM close their guard cells and discharge malate that is subsequently transported into chloroplasts. There, depending on plant species, it is cleaved into pyruvate and either by malic enzyme or by PEP carboxykinase. is then introduced into the Calvin cycle, a coupled and self-recovering enzyme system, which is used to build branched carbohydrates. The by-product pyruvate can be further degraded in the mitochondrial citric acid cycle, thereby providing additional molecules for the Calvin Cycle. Pyruvate can also be used to recover PEP via pyruvate phosphate dikinase, a high-energy step, which requires ATP and an additional phosphate. During the following cool night, PEP is finally exported into the cytoplasm, where it is involved in fixing carbon dioxide via malate. | 0 | Theoretical and Fundamental Chemistry |
The coefficient lies always in range values equal to 0 or 1), value 1 indicates ideal equal-spreading of the spots, for example (0.25,0.5,0.75) for three solutes, or (0.2,0.4,0.6,0.8) for four solutes.
This coefficient was proposed as an alternative to earlier approaches, such as D (separation response), I (performance index) or S (informational entropy). Besides its stable range, the advantage is a stable distribution as a random variable, regardless of compounds investigated.
In contrast to the similar concept called Retention distance, R is insensitive to R values close to 0 or 1, or close to themselves. If two values are not separated, it still indicates some uniformity of chromatographic system. For example, the R values (0,0.2,0.2,0.3) (two compounds not separated at 0.2 and one at the start ) result in R equal to 0.3609. | 0 | Theoretical and Fundamental Chemistry |
Two formulations of different dispersing agents for oil spills, Dispersit and Omni-Clean, are shown below. A key difference between the two is that Omni-Clean uses ionic surfactants and Dispersit uses entirely non-ionic surfactants. Omni-Clean was formulated for little or no toxicity toward the environment. Dispersit, however, was designed as a competitor with Corexit. Dispersit contains non-ionic surfactants, which permit both primarily oil-soluble and primarily water-soluble surfactants. The partitioning of surfactants between the phases allows for effective dispersion. | 1 | Applied and Interdisciplinary Chemistry |
Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all pesticide use globally. Most pesticides are used as plant protection products (also known as crop protection products), which in general protect plants from weeds, fungi, or insects. In general, a pesticide is a chemical or biological agent (such as a virus, bacterium, or fungus) that deters, incapacitates, kills, or otherwise discourages pests. Target pests can include insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes (roundworms), and microbes that destroy property, cause nuisance, or spread disease, or are disease vectors. Along with these benefits, pesticides also have drawbacks, such as potential toxicity to humans and other species. | 1 | Applied and Interdisciplinary Chemistry |
A sized screen fraction with a size range coefficient (d95/d5) of 2-5 (optimal 2-3) is fed onto a vibratory feeder which has the function to create a mono-layer, by pre-accelerating the particles. A common misunderstanding in plant design is, that you can use the vibratory feeder to discharge from a buffer bunker but a separate units needs to be applied, since the feed distribution is very important to the efficiency of the sensor-based sorter and different loads on the feeder change its position and vibration characteristics. | 0 | Theoretical and Fundamental Chemistry |
Lymphocytes can enter mitosis when they are activated by mitogens or antigens. B cells specifically can divide when they encounter an antigen matching their immunoglobulin. T cells undergo mitosis when stimulated by mitogens to produce small lymphocytes that are then responsible for the production of lymphokines, which are substances that modify the host organism to improve its immunity. B cells, on the other hand, divide to produce plasma cells when stimulated by mitogens, which then produce immunoglobulins, or antibodies. Mitogens are often used to stimulate lymphocytes and thereby assess immune function. The most commonly used mitogens in clinical laboratory medicine are:
Lipopolysaccharide toxin from gram-negative bacteria is thymus-independent. They may directly activate B cells, regardless of their antigenic specificity. Plasma cells are terminally differentiated and, therefore, cannot undergo mitosis. Memory B cells can proliferate to produce more memory cells or plasma B cells. This is how the mitogen works, that is, by inducing mitosis in memory B cells to cause them to divide, with some becoming plasma cells. | 1 | Applied and Interdisciplinary Chemistry |
Sodium hydroxide is used in some cement mix plasticisers. This helps homogenise cement mixes, preventing segregation of sands and cement, decreases the amount of water required in a mix and increases workability of the cement product, be it mortar, render or concrete. | 0 | Theoretical and Fundamental Chemistry |
Another example is hematite on magnetite . The magnetite structure is based on close-packed oxygen anions stacked in an ABC-ABC sequence. In this packing the close-packed layers are parallel to (111) (a plane that symmetrically "cuts off" a corner of a cube). The hematite structure is based on close-packed oxygen anions stacked in an AB-AB sequence, which results in a crystal with hexagonal symmetry.
If the cations were small enough to fit into a truly close-packed structure of oxygen anions then the spacing between the nearest neighbour oxygen sites would be the same for both species. The radius of the oxygen ion, however, is only 1.36 Å and the Fe cations are big enough to cause some variations. The Fe radii vary from 0.49 Å to 0.92 Å, depending on the charge (2+ or 3+) and the coordination number (4 or 8). Nevertheless, the O spacings are similar for the two minerals hence hematite can readily grow on the (111) faces of magnetite, with hematite (001) parallel to magnetite (111). | 0 | Theoretical and Fundamental Chemistry |
Homogeneous catalysis is a major application of coordination compounds for the production of organic substances. Processes include hydrogenation, hydroformylation, oxidation. In one example, a combination of titanium trichloride and triethylaluminium gives rise to Ziegler–Natta catalysts, used for the polymerization of ethylene and propylene to give polymers of great commercial importance as fibers, films, and plastics.
Nickel, cobalt, and copper can be extracted using hydrometallurgical processes involving complex ions. They are extracted from their ores as ammine complexes. Metals can also be separated using the selective precipitation and solubility of complex ions. Cyanide is used chiefly for extraction of gold and silver from their ores.
Phthalocyanine complexes are an important class of pigments. | 0 | Theoretical and Fundamental Chemistry |
Continuous assays are most convenient, with one assay giving the rate of reaction with no further work necessary. There are many different types of continuous assays. | 1 | Applied and Interdisciplinary Chemistry |
Some assert that the dead zone threatens lucrative commercial and recreational fisheries in the Gulf of Mexico. "In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly three million recreational fishers further contributed about $10 billion to the Gulf economy, taking 22 million fishing trips." Scientists are not in universal agreement that nutrient loading has a negative impact on fisheries. Grimes makes a case that nutrient loading enhances the fisheries in the Gulf of Mexico. Courtney et al. hypothesize, that nutrient loading may have contributed to the increases in red snapper in the northern and western Gulf of Mexico.
In 2017, Tulane University offered a $1 million challenge grant for growing crops with less fertilizer. | 0 | Theoretical and Fundamental Chemistry |
This modeling technique compares the gene sequence of an unknown protein with sequences of proteins with known structures. Depending on the degree of similarity between the sequences, the structure of the known protein can be used as a model for solving the structure of the unknown protein. Highly accurate modeling is considered to require at least 50% amino acid sequence identity between the unknown protein and the solved structure. 30-50% sequence identity gives a model of intermediate-accuracy, and sequence identity below 30% gives low-accuracy models. It has been predicted that at least 16,000 protein structures will need to be determined in order for all structural motifs to be represented at least once and thus allowing the structure of any unknown protein to be solved accurately through modeling. One disadvantage of this method, however, is that structure is more conserved than sequence and thus sequence-based modeling may not be the most accurate way to predict protein structures. | 1 | Applied and Interdisciplinary Chemistry |
Ring-opening polymerization that involves β-alkyl elimination can be catalyzed by Ti, Zr, Pd-based catalyst, and some Lanthanide-based metallocene catalyst, where different polymerization patterns vary when catalysts are different. Examples of copolymerization with alkene or carbon monoxide were also reported. The key step of this kind of ROP is string-driven β-alkyl elimination, which provides linear polymer with unsaturation in the polymer chain. | 0 | Theoretical and Fundamental Chemistry |
FK962 is a compound which acts as an enhancer of somatostatin release. It stimulates nerve growth and neurite elongation, and has been researched in animal models for potential applications in the treatment of conditions such as Alzheimer's disease and retinal neuropathy. | 1 | Applied and Interdisciplinary Chemistry |
The society publishes "Chemistry & Chemical Industry" every month in a printed form, which is sent to the members of the society. The digital form of "Chemistry & Chemical Industry" is uploaded in the website of the society, and any member of the society can access the digital form. | 1 | Applied and Interdisciplinary Chemistry |
Ketosis induced by a ketogenic diet should not be pursued by people with pancreatitis because of the high dietary fat content. Ketosis is also contraindicated in pyruvate carboxylase deficiency, porphyria, and other rare genetic disorders of fat metabolism. | 1 | Applied and Interdisciplinary Chemistry |
The bulk properties of a polymer are those most often of end-use interest. These are the properties that dictate how the polymer actually behaves on a macroscopic scale. | 0 | Theoretical and Fundamental Chemistry |
Young's modulus quantifies the elasticity of the polymer. It is defined, for small strains, as the ratio of rate of change of stress to strain. Like tensile strength, this is highly relevant in polymer applications involving the physical properties of polymers, such as rubber bands. The modulus is strongly dependent on temperature. Viscoelasticity describes a complex time-dependent elastic response, which will exhibit hysteresis in the stress-strain curve when the load is removed. Dynamic mechanical analysis or DMA measures this complex modulus by oscillating the load and measuring the resulting strain as a function of time. | 0 | Theoretical and Fundamental Chemistry |
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