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The internal heating within stars is so great that (after an initial phase of gravitational contraction) they ignite and sustain thermonuclear reaction of hydrogen (with itself) to form helium, and can make heavier elements (see Stellar nucleosynthesis). The Sun for example has a core temperature of 13,600,000 K. The more massive and older the stars are, the more internal heating they have. During the end of its lifecycle, the internal heating of a star increases dramatically, caused by the change of composition of the core as successive fuels for fusion are consumed, and the resulting contraction (accompanied by faster consumption of the remaining fuel). Depending upon the mass of the star, the core may become hot enough to fuse helium (forming carbon and oxygen and traces of heavier elements), and for sufficiently massive stars even large quantities of heavier elements. Fusion to produce elements heavier than iron and nickel no longer produces energy, and since stellar cores massive enough to attain the temperatures required to produce these elements are too massive to form stable white dwarf stars, a core collapse supernova results, producing a neutron star or a black hole, depending upon the mass. Heat generated by the collapse is trapped within a neutron star and only escapes slowly, due to the small surface area; heat cannot be conducted out of a black hole at all (however, see Hawking radiation). | 0 | Theoretical and Fundamental Chemistry |
DksA is a 17-kDa protein, its structure is similar to GreA and GreB, which are well-characterized transcriptional elongation factors. GreA and GreB bind directly to RNAP rather than DNA and act by inserting their N-terminal coiled-coil finger domain through the RNAP secondary channel. Two conserved acidic residues at the tip of the finger domain are necessary to induce RNAP's intrinsic ability to cleave backtracked RNA. DksA also possesses two acidic residues at its finger tip, but it does not induce nucleolytic cleavage activity. Instead, these residues are proposed to stabilize ppGpp binding to RNAP by mutual coordination of an Mg2+ ion that is crucial for polymerization. | 1 | Applied and Interdisciplinary Chemistry |
Tannins are used in the tanning industry.
Some natural phenols can be used as biopesticides. Furanoflavonoids like karanjin or rotenoids are used as acaricide or insecticide.
Enological tannins are important elements in the flavor of wine.
Some phenols are sold as dietary supplements. Phenols have been investigated as drugs. For instance, Crofelemer (USAN trade name Fulyzaq) is a drug under development for the treatment of diarrhea associated with anti-HIV drugs. Additionally, derivatives have been made of phenolic compound, combretastatin A-4, an anticancer molecule, including nitrogen or halogens atoms to increase the efficacy of the treatment. | 0 | Theoretical and Fundamental Chemistry |
Functions can be binding motifs that bind another macromolecule or small compound, that induce a covalent modification of minimotif, or are involved in the protein trafficking of the protein containing the minimotif. The basic premise of Minimotif Miner is that is a short peptide sequence is known to have a function in one protein, may have a similar function in another query protein. The current release of the MnM 3.0 database has ~300,000 minimotifs and can be searched at the website.
There are two workflows that are of interest to scientists that use Minimotif Miner 1) Entering any query protein into Minimotif Miner returns a table with a list of minimotif sequence and functions that have a sequence pattern match with the protein query sequence. These provide potential new functions in the protein query. 2) By using the view single nucleotide polymorphism (SNP) function, SNPs from dbSNP are mapped in the sequence window. A user can select any set of the SNPs and then identify any minimotif that is introduced or eliminated by the SNP or mutation. This helps to identify minimotifs involved in generating organism diversity or those that may be associated with a disease.
Typical results of MnM predict more than 50 new minimotifs for a protein query. A major limitation in this type of analysis is that the low sequence complexity of short minimotifs produces false positive predictions where the sequence occurs in a protein by random chance and not because it contains the predicted function. MnM 3.0 introduces a library of advanced heuristics and filters, which enable vast reduction of false positive predictions. These filters use minimotif complexity, protein surface location, molecular processes, cellular processes, protein-protein interactions, and genetic interactions. We recently combined all of these heuristics into a single, compound filter which makes significant progress toward solving this problem with high accuracy of minimotif prediction as measured by a performance benchmarking study which evaluated both sensitivity and specificity. | 1 | Applied and Interdisciplinary Chemistry |
Indirect DNA damage occurs when a UV-photon is absorbed in the human skin by a chromophore that does not have the ability to convert the energy into harmless heat very quickly. Molecules that do not have this ability have a long-lived excited state. This long lifetime leads to a high probability for reactions with other molecules—so-called bimolecular reactions. Melanin and DNA have extremely short excited state lifetimes in the range of a few femtoseconds (10s). The excited state lifetime of compounds used in sunscreens such as menthyl anthranilate, avobenzone or padimate O is 1,000 to 1,000,000 times longer than that of melanin, and therefore they may cause damage to living cells that come in contact with them.
The molecule that originally absorbs the UV-photon is called a "chromophore". Bimolecular reactions can occur either between the excited chromophore and DNA or between the excited chromophore and another species, to produce free radicals and reactive oxygen species. These reactive chemical species can reach DNA by diffusion and the bimolecular reaction damages the DNA (oxidative stress). It is important to note that, unlike direct DNA damage which causes sunburn, indirect DNA damage does not result in any warning signal or pain in the human body.
The bimolecular reactions that cause the indirect DNA damage are illustrated in the figure:
O is reactive harmful singlet oxygen: | 0 | Theoretical and Fundamental Chemistry |
The energy used to heat the feedwater is usually derived from steam extracted between the stages of the steam turbine. Therefore, the steam that would be used to perform expansion work in the turbine (and therefore generate power) is not utilized for that purpose. The percentage of the total cycle steam mass flow used for the feedwater heater is termed the extraction fraction and must be carefully optimized for maximum power plant thermal efficiency since increasing this fraction causes a decrease in turbine power output.
Feedwater heaters can also be "open" or "closed"  heat exchangers. An open heat exchanger is one in which extracted steam is allowed to mix with the feedwater. This kind of heater will normally require a feed pump at both the feed inlet and outlet since the pressure in the heater is between the boiler pressure and the condenser pressure. A deaerator is a special case of the open feedwater heater which is specifically designed to remove non-condensable gases from the feedwater.
Closed feedwater heaters are typically shell and tube heat exchangers where the feedwater passes throughout the tubes and is heated by turbine extraction steam. These do not require separate pumps before and after the heater to boost the feedwater to the pressure of the extracted steam as with an open heater. However, the extracted steam (which is most likely almost fully condensed after heating the feedwater) must then be throttled to the condenser pressure, an isenthalpic process that results in some entropy gain with a slight penalty on overall cycle efficiency:
Many power plants incorporate a number of feedwater heaters and may use both open and closed components. Feedwater heaters are used in both fossil- and nuclear-fueled power plants. | 1 | Applied and Interdisciplinary Chemistry |
The bond valence method is a development of Paulings rules. In 1930, Lawrence Bragg showed that Paulings electrostatic valence rule could be represented by electrostatic lines of force emanating from cations in proportion to the cation charge and ending on anions. The lines of force are divided equally between the bonds to the corners of the coordination polyhedron.
Starting with Pauling in 1947 a correlation between cation–anion bond length and bond strength was noted. It was shown later that if bond lengths were included in the calculation of bond strength, its accuracy was improved, and this revised method of calculation was termed the bond valence. These new insights were developed by later workers culminating in the set of rules termed the bond valence model. | 0 | Theoretical and Fundamental Chemistry |
Abu Bakarr Kanu is a Sierra Leonean analytical chemist who is a professor at Winston-Salem State University. His research considers separation-type instrumentation for the rapid analysis of chemical and biological compounds. Kanu is also involved with education and outreach programmes, and works to bring hands-on chemistry lessons to young people in Sierra Leone. | 0 | Theoretical and Fundamental Chemistry |
Alkylation occurs when a molecule replaces a hydrogen atom with an alkyl group that generally comes from an organic molecule. Alkyl groups that are found naturally occurring in the environment are organometallic compounds. Organometallic compounds generally contain a methyl, ethyl, or butyl derivative which is the alkyl group that replaces the hydrogen. Other organic compounds, such as methanol, can provide alkyl groups for alkylation. Methanol is found naturally in the environment in small concentrations, and has been linked to the release from biological decomposition of waste and even a byproduct of vegetation. The following reactions are alkylations of soluble compounds found in creosote preservatives with methanol. | 0 | Theoretical and Fundamental Chemistry |
Plasmid preparation can be divided into five main categories based on the scale of the preparation: minipreparation, midipreparation, maxipreparation, megapreparation, and gigapreparation. The choice of which method to use will depend on the amount of plasmid DNA required, as well as the specific application for which it will be used.
Kits are available from varying manufacturers to purify plasmid DNA, which are named by size of bacterial culture and corresponding plasmid yield. In increasing order they are: miniprep, midiprep, maxiprep, megaprep, and gigaprep. The plasmid DNA yield will vary depending on the plasmid copy number, type and size, the bacterial strain, the growth conditions, and the kit. | 1 | Applied and Interdisciplinary Chemistry |
The American biochemist George Wald and others had outlined the visual cycle by 1958. For his work, Wald won a share of the 1967 Nobel Prize in Physiology or Medicine with Haldan Keffer Hartline and Ragnar Granit. | 1 | Applied and Interdisciplinary Chemistry |
Tribromoisocyanuric acid (CBrNO) is a chemical compound used as a reagent for bromination in organic synthesis. It is a white crystalline powder with a strong bromine odour. It is similar to trichloroisocyanuric acid. | 0 | Theoretical and Fundamental Chemistry |
A number of blocking agents maybe employed but a common one is Methylethyl ketone oxime (MEKO). Caprolactam is also used.
When blocked, there is no isocyanate (NCO) functionality, so it is much easier to disperse the species in water if the desire is to produce waterborne resins. One of the key reasons different blocking agents are used apart from chemical properties is that they unblock at different temperatures. MEKO has a fairly low unblocking temperature and is thus in fairly common usage. A mixture of blocking agents maybe used to optimize properties. | 0 | Theoretical and Fundamental Chemistry |
Values of Henrys law constants for aqueous solutions depend on the composition of the solution, i.e., on its ionic strength and on dissolved organics. In general, the solubility of a gas decreases with increasing salinity ("salting out"). However, a "salting in" effect has also been observed, for example for the effective Henrys law constant of glyoxal. The effect can be described with the Sechenov equation, named after the Russian physiologist Ivan Sechenov (sometimes the German transliteration "Setschenow" of the Cyrillic name Се́ченов is used). There are many alternative ways to define the Sechenov equation, depending on how the aqueous-phase composition is described (based on concentration, molality, or molar fraction) and which variant of the Henry's law constant is used. Describing the solution in terms of molality is preferred because molality is invariant to temperature and to the addition of dry salt to the solution. Thus, the Sechenov equation can be written as
where is the Henrys law constant in pure water, is the Henrys law constant in the salt solution, is the molality-based Sechenov constant, and is the molality of the salt. | 0 | Theoretical and Fundamental Chemistry |
The Mars 2020 rover, which launched in 2020, is intended to investigate an astrobiologically relevant ancient environment on Mars, investigate its surface geological processes and history, including the assessment of its past habitability, the possibility of past life on Mars, and potential for preservation of biosignatures within accessible geological materials. In addition, it will cache the most interesting samples for possible future transport to Earth. | 1 | Applied and Interdisciplinary Chemistry |
A British Approved Name (BAN) is the official, non-proprietary, or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia (BP). The BAN is also the official name used in some countries around the world, because starting in 1953, proposed new names were evaluated by a panel of experts from WHO in conjunction with the BP commission to ensure naming consistency worldwide (an effort leading to the International Nonproprietary Name system). There is also a British Approved Name (Modified) (BANM). | 1 | Applied and Interdisciplinary Chemistry |
LOV domains have been found to control gene expression through DNA binding and
to be involved in redox-dependent regulation, like e.g. in the bacterium Rhodobacter sphaeroides. Notably, LOV-based optogenetic tools have been gaining wide popularity in recent years to control a myriad of cellular events, including cell motility, subcellular organelle distribution, formation of membrane contact sites, microtubule dynamics, transcription, and protein degradation. | 1 | Applied and Interdisciplinary Chemistry |
The Standard Model hypothesises a field called the Higgs field (symbol: ), which has the unusual property of a non-zero amplitude in its ground state (zero-point) energy after renormalization; i.e., a non-zero vacuum expectation value. It can have this effect because of its unusual "Mexican hat" shaped potential whose lowest "point" is not at its "centre". Below a certain extremely high energy level the existence of this non-zero vacuum expectation spontaneously breaks electroweak gauge symmetry which in turn gives rise to the Higgs mechanism and triggers the acquisition of mass by those particles interacting with the field. The Higgs mechanism occurs whenever a charged field has a vacuum expectation value. This effect occurs because scalar field components of the Higgs field are "absorbed" by the massive bosons as degrees of freedom, and couple to the fermions via Yukawa coupling, thereby producing the expected mass terms. The expectation value of in the ground state (the vacuum expectation value or VEV) is then , where . The measured value of this parameter is approximately . It has units of mass, and is the only free parameter of the Standard Model that is not a dimensionless number.
The Higgs mechanism is a type of superconductivity which occurs in the vacuum. It occurs when all of space is filled with a sea of particles which are charged and thus the field has a nonzero vacuum expectation value. Interaction with the vacuum energy filling the space prevents certain forces from propagating over long distances (as it does in a superconducting medium; e.g., in the Ginzburg–Landau theory). | 0 | Theoretical and Fundamental Chemistry |
Particles close to a surface do not move along with a flow when adhesion is stronger than cohesion.
At the fluid-solid interface, the force of attraction between the fluid particles and solid particles (adhesive forces) is greater than that between the fluid particles (cohesive forces). This force imbalance causes the fluid velocity to be zero adjacent to the solid surface, with the velocity approaching that of the stream as distance from the surface increases.
The no-slip condition is only defined for viscous flows and where the continuum concept is valid. | 1 | Applied and Interdisciplinary Chemistry |
The book begins by discussing the history of parasites in human knowledge, from the earliest writings about them in ancient cultures, up through modern times. The focus comes to rest extensively on the views and experiments conducted by scientists in the 17th, 18th, and 19th centuries, such as those done by Antonie van Leeuwenhoek, Japetus Steenstrup, Friedrich Küchenmeister, and Ray Lankester. Among them, Leeuwenhoek was the first to ever physically view cells through a microscope, Steenstrup was the first to explain and confirm the multiple stages and life cycles of parasites that are different from most other living organisms, and Küchenmeister, through his religious beliefs and his views on every creature having a place in the natural order, denied the ideas of his time and proved that all parasites are a part of active evolutionary niches and not biological dead ends by conducting morally ambiguous experiments on prisoners. Lankester is given a specific focus and repeated discussion throughout the book due to his belief that parasites are examples of degenerative evolution, especially in regards to Sacculina, and Zimmer's repeated refutation of this idea.
Several chapters are taken to discuss various types of parasites and how they infect and control their hosts, along with the biochemistry involved in their take-over or evasion of their hosts immune system, eventually leading to their dispersal into their next form and life cycle. An extended time is also given on the workings of immunology and how the immune systems of living beings respond to parasite infection, along with the methods that bodily functions use to counteract and potentially kill invading microorganisms. Woven into this discussion are several specific sites that Zimmer visited during his writing of Parasite Rex' and the scientists he worked with to understand different biosystems and all the parasites that live within them, including human sleeping sickness infections in Sudan from the tsetse fly, the parasites of frogs in Costa Rica, primarily showcased by filarial worms that infect humans and a variety of species, and the USDA National Parasite Collection based out of Maryland.
The final chapters focus on an overall effect parasites have had on the evolution of life and the theory that it is due to parasitic infection that sexual reproduction evolved to become dominant, in contrast to previous asexual reproduction methods, due to the increased genetic variety and thus potential parasitic resistance that this would confer. This research was showcased by W. D. Hamilton and his theories on the evolution of sex, along with the Red Queen hypothesis and the idea of an evolutionary arms race between parasites and their hosts. Zimmer then discusses a final time the wide variety of parasites that evolved to have humans as their primary hosts and our attempts through scientific advancement to eradicate them. The closing chapter considers the positive benefits of parasites and how humans have used them to improve agriculture and medical technology, but also how ill-considered usage of parasites could also destroy various habitats by having them act as invasive species. In the end, Zimmer ponders whether humanity counts as a parasite on the planet and what the effects of this relationship could be. | 1 | Applied and Interdisciplinary Chemistry |
In May, the FDA approved onasemnogene abeparvovec (Zolgensma) for treating spinal muscular atrophy in children under two years of age. The list price of Zolgensma was set at per dose, making it the most expensive drug ever.
In May, the EMA approved betibeglogene autotemcel (Zynteglo) for treating beta thalassemia for people twelve years of age and older.
In July, Allergan and Editas Medicine announced phase I/II clinical trial of AGN-151587 for the treatment of Leber congenital amaurosis 10. This is the first study of a CRISPR-based in vivo human gene editing therapy, where the editing takes place inside the human body. The first injection of the CRISPR-Cas System was confirmed in March 2020. | 1 | Applied and Interdisciplinary Chemistry |
This large and diverse class of steroids are biosynthesized from isoprenoids and structurally resemble cholesterol. Mammalian steroid hormones can be grouped into five groups by the receptors to which they bind: glucocorticoids, mineralocorticoids, androgens, estrogens, and progestogens. | 1 | Applied and Interdisciplinary Chemistry |
Since 2006, China releases more than any other country. Researchers in China are focusing on increasing efficiency of burning coal so they can get more power out of less coal. It is estimated that new high efficiency power plants could reduce emission by 7% because they won't have to burn as much coal to get the same amount of power. | 1 | Applied and Interdisciplinary Chemistry |
Harmful algal blooms in marine ecosystems have been observed to cause adverse effects to a wide variety of aquatic organisms, most notably marine mammals, sea turtles, seabirds and finfish. The impacts of HAB toxins on these groups can include harmful changes to their developmental, immunological, neurological, or reproductive capacities. The most conspicuous effects of HABs on marine wildlife are large-scale mortality events associated with toxin-producing blooms. For example, a mass mortality event of 107 bottlenose dolphins occurred along the Florida panhandle in the spring of 2004 due to ingestion of contaminated menhaden with high levels of brevetoxin. Manatee mortalities have also been attributed to brevetoxin but unlike dolphins, the main toxin vector was endemic seagrass species (Thalassia testudinum) in which high concentrations of brevetoxins were detected and subsequently found as a main component of the stomach contents of manatees.
Additional marine mammal species, like the highly endangered North Atlantic right whale, have been exposed to neurotoxins by preying on highly contaminated zooplankton. With the summertime habitat of this species overlapping with seasonal blooms of the toxic dinoflagellate Alexandrium fundyense, and subsequent copepod grazing, foraging right whales will ingest large concentrations of these contaminated copepods. Ingestion of such contaminated prey can affect respiratory capabilities, feeding behavior, and ultimately the reproductive condition of the population.
Immune system responses have been affected by brevetoxin exposure in another critically endangered species, the loggerhead sea turtle. Brevetoxin exposure, from inhalation of aerosolized toxins and ingestion of contaminated prey, can have clinical signs of increased lethargy and muscle weakness in loggerhead sea turtles causing these animals to wash ashore in a decreased metabolic state with increases of immune system responses upon blood analysis.
Examples of common harmful effects of HABs include:
# the production of neurotoxins which cause mass mortalities in fish, seabirds, sea turtles, and marine mammals
# human illness or death from consumption of seafood contaminated by toxic algae
# mechanical damage to other organisms, such as disruption of epithelial gill tissues in fish, resulting in asphyxiation
# oxygen depletion of the water column (hypoxia or anoxia) from cellular respiration and bacterial degradation | 0 | Theoretical and Fundamental Chemistry |
pRb has also been implicated in regulating metabolism through interactions with components of cellular metabolic pathways. RB1 mutations can cause alterations in metabolism, including reduced mitochondrial respiration, reduced activity in the electron transport chain, and changes in flux of glucose and/or glutamine. Particular forms of pRb have been found to localize to the outer mitochondrial membrane and directly interacts with Bax to promote apoptosis. | 1 | Applied and Interdisciplinary Chemistry |
Hot isostatic pressing (HIP) is a manufacturing process, used to reduce the porosity of metals and increase the density of many ceramic materials. This improves the material's mechanical properties and workability.
The process can be used to produce waste form classes. Calcined radioactive waste (waste with additives) is packed into a thin walled metal canister. The adsorbed gases are removed with high heat and the remaining material compressed to full density using argon gas during the heat cycle. This process can shrink steel canisters to minimize space in disposal containers and during transport. It was invented in the 1950s at the Battelle Memorial Institute and has been used to prepare nuclear fuel for submarines since the 1960s. It is used to prepare inactive ceramics as well, and the Idaho National Laboratory has validated it for the consolidation of radioactive ceramic waste forms. ANSTO (Australian Nuclear Science and Technology Organisation) is using HIP as part of a process to immobilize waste radionuclides from molybdenum-99 production.
The HIP process subjects a component to both elevated temperature and isostatic gas pressure in a high pressure containment vessel. The pressurizing gas most widely used is argon. An inert gas is used so that the material does not chemically react. The choice of metal can minimize negative effects of chemical reactions. Nickel, stainless or mild steel, or other metals can be chosen depending on the desired redox conditions. The chamber is heated, causing the pressure inside the vessel to increase. Many systems use associated gas pumping to achieve the necessary pressure level. Pressure is applied to the material from all directions (hence the term "isostatic").
For processing castings, metal powders can also be turned to compact solids by this method, the inert gas is applied between and , with being most common. Process soak temperatures range from for aluminium castings to for nickel-based superalloys. When castings are treated with HIP, the simultaneous application of heat and pressure eliminates internal voids and microporosity through a combination of plastic deformation, creep, and diffusion bonding; this process improves fatigue resistance of the component. Primary applications are the reduction of microshrinkage, the consolidation of powder metals, ceramic composites and metal cladding. Hot isostatic pressing is thus also used as part of a sintering (powder metallurgy) process and for fabrication of metal matrix composites,
often being used for postprocessing in additive manufacturing. | 1 | Applied and Interdisciplinary Chemistry |
Consider a simple branched pathway with all three steps irreversible. Such a pathway will admit two elementary modes which are indicated in thicked (or red) reaction lines.
Because both and are irreversible, and elementary mode lying on both these reactions is not possible since it would mean one reactions going against its thermodynamic direction. Each mode in this system satisfies the three conditions described above. The first condition is steady state, that is for each mode , it has to be true that .
Algebraically the two modes are given by:
By substituting each of these vectors into , it is easy to show that condition one is satisfied. For condition two we must ensure that all reactions that are irreversible have positive entries in the corresponding elements of the elementary modes. Since all three reactions in the branch are irreversible and all entries in the elementary modes are positive, condition two is satisfied.
Finally, to satisfy condition three, we must ask whether we can decompose the two elementary modes into other paths that can sustain a steady state while using the same non-zero entries in the elementary mode. In this example, it is impossible to decompose the elementary modes any further without disrupting the ability to sustain a steady state. Therefore, with all three conditions satisfied, we can conclude that the two vectors shown above are elementary modes.
All possible flows through a network can be constructed from linear combinations of the elementary modes, that is:
such that the entire space of flows through a network can be described. must be greater than or equal to zero to ensure that irreversible steps aren't inadvertently made to go in the reverse direction. For example, the following is a possible steady-state flow in the branched pathway.
If one of the outflow steps in the simple branched pathway is made reversible, an additional elementary mode becomes available, representing the flow between the two outflow branches. An additional mode emerges because, with only the first two modes, it is impossible to represent a flow between the two branches because the scaling factor, , cannot be negative (which would be required to reverse the flow). | 1 | Applied and Interdisciplinary Chemistry |
Glycosylation is the process by which a carbohydrate is covalently attached to a target macromolecule, typically proteins and lipids. This modification serves various functions. For instance, some proteins do not fold correctly unless they are glycosylated. In other cases, proteins are not stable unless they contain oligosaccharides linked at the amide nitrogen of certain asparagine residues. The influence of glycosylation on the folding and stability of glycoprotein is twofold. Firstly, the highly soluble glycans may have a direct physicochemical stabilisation effect. Secondly, N-linked glycans mediate a critical quality control check point in glycoprotein folding in the endoplasmic reticulum. Glycosylation also plays a role in cell-to-cell adhesion (a mechanism employed by cells of the immune system) via sugar-binding proteins called lectins, which recognize specific carbohydrate moieties. Glycosylation is an important parameter in the optimization of many glycoprotein-based drugs such as monoclonal antibodies. Glycosylation also underpins the ABO blood group system. It is the presence or absence of glycosyltransferases which dictates which blood group antigens are presented and hence what antibody specificities are exhibited. This immunological role may well have driven the diversification of glycan heterogeneity and creates a barrier to zoonotic transmission of viruses. In addition, glycosylation is often used by viruses to shield the underlying viral protein from immune recognition. A significant example is the dense glycan shield of the envelope spike of the human immunodeficiency virus.
Overall, glycosylation needs to be understood by the likely evolutionary selection pressures that have shaped it. In one model, diversification can be considered purely as a result of endogenous functionality (such as cell trafficking). However, it is more likely that diversification is driven by evasion of pathogen infection mechanism (e.g. Helicobacter attachment to terminal saccharide residues) and that diversity within the multicellular organism is then exploited endogenously.
Glycosylation can also module the thermodynamic and kinetic stability of the proteins. | 0 | Theoretical and Fundamental Chemistry |
An indeterminate sample simply takes the element name. For example a sample of carbon (which could be diamond, graphite etc or a mixture) would be named carbon. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, Blasius theorem states that the force experienced by a two-dimensional fixed body in a steady irrotational flow is given by
and the moment about the origin experienced by the body is given by
Here,
* is the force acting on the body,
* is the density of the fluid,
* is the contour flush around the body,
* is the complex potential ( is the velocity potential, is the stream function),
* is the complex velocity ( is the velocity vector),
* is the complex variable ( is the position vector),
* is the real part of the complex number, and
* is the moment about the coordinate origin acting on the body.
The first formula is sometimes called Blasius–Chaplygin formula.
The theorem is named after Paul Richard Heinrich Blasius, who derived it in 1911. The Kutta–Joukowski theorem directly follows from this theorem. | 1 | Applied and Interdisciplinary Chemistry |
Removing atoms by sputtering with an inert gas is called ion milling or ion etching.
Sputtering can also play a role in reactive-ion etching (RIE), a plasma process carried out with chemically active ions and radicals, for which the sputtering yield may be enhanced significantly compared to pure physical sputtering. Reactive ions are frequently used in secondary ion mass spectrometry (SIMS) equipment to enhance the sputter rates. The mechanisms causing the sputtering enhancement are not always well understood, although the case of fluorine etching of Si has been modeled well theoretically.
Sputtering observed to occur below the threshold energy of physical sputtering is also often called chemical sputtering. The mechanisms behind such sputtering are not always well understood, and may be hard to distinguish from chemical etching. At elevated temperatures, chemical sputtering of carbon can be understood to be due to the incoming ions weakening bonds in the sample, which then desorb by thermal activation. The hydrogen-induced sputtering of carbon-based materials observed at low temperatures has been explained by H ions entering between C-C bonds and thus breaking them, a mechanism dubbed swift chemical sputtering. | 0 | Theoretical and Fundamental Chemistry |
Chemaxon Products include tools for visualization and drawing of molecules, chemical database searching and management, and for drug discovery. Products are licensed free of charge for academic use.
Chemaxon’s desktop applications include Marvin which is free chemistry software for drawing and visualizing chemical structures, and Instant JChem, a desktop application for end user scientists; JChem for Excel which integrates the structure handling capabilities of JChem and Marvin within a Microsoft Excel environment.
The software can be used to predict pK values and logP values.
The company developed Markush structure storage and search capabilities (without enumeration), with Markush structures from Thomson Reuters Derwent World Patents Index (DWPISM) database.
Pearson Education uses Chemaxon's JChem, MarvinSketch, and MarvinView as the chemistry tools in many of Pearson MasteringChemistry courses. | 1 | Applied and Interdisciplinary Chemistry |
Lanthanum oxide is used as an additive to develop certain ferroelectric materials, such as La-doped bismuth titanate ( - BLT).
Lanthanum oxide is used in optical materials; often the optical glasses are doped with to improve the glass' refractive index, chemical durability, and mechanical strength.
The addition of the to the glass melt leads to a higher glass transition temperature from 658 °C to 679 °C. The addition also leads to a higher density, microhardness, and refractive index of the glass. | 0 | Theoretical and Fundamental Chemistry |
As with all flavonoids, anthoxanthins have antioxidant properties and are important for nutrition. They are sometimes used as food additives to add color or flavor to foods. One of the most well-known anthoxanthins is quercetin, which is found in many fruits and vegetables, including capers, red onions, and kale.
In addition to their use as food additives, anthoxanthins are also used in the production of dyes and pigments. Anthoxanthins can also be used to create yellow, orange, or red dyes for use in textiles, cosmetics, and other products. | 1 | Applied and Interdisciplinary Chemistry |
The following unsourced paragraph about a similarly named piece of equipment was previously put in the summary of this article:
In some countries hydrants in streets are below ground level. Fire trucks carry standpipes and key, and there are pry bars on the truck. The bar is used to lift a cover in the road, exposing the hydrant. The standpipe is then "sunk" into the hydrant, and the hose is connected to the exposed ends of the standpipe. The bar is then combined with the key, and is used to turn the hydrant on and off. | 1 | Applied and Interdisciplinary Chemistry |
Within the host matrix, the rotation and translation of the guest particle is usually inhibited. Therefore, the matrix isolation technique may be used to simulate a spectrum of a species in the gas phase without rotational and translational interference. The low temperatures also help to produce simpler spectra, since only the lower electronic and vibrational quantum states are populated.
Especially infrared (IR) spectroscopy, which is used to investigate molecular vibration, benefits from the matrix isolation technique. For example, in the gas-phase IR spectrum of fluoroethane some spectral regions are very difficult to interpret, as vibrational quantum states heavily overlap with multiple rotational-vibrational quantum states. When fluoroethane is isolated in argon or neon matrices at low temperatures, the rotation of the fluoroethane molecule is inhibited. Because rotational-vibrational quantum states are quenched in the matrix isolation IR spectrum of fluoroethane, all vibrational quantum states can be identified. This is especially useful for the validation of simulated infrared spectra that can be obtained from computational chemistry. | 0 | Theoretical and Fundamental Chemistry |
Hydrogen cyanide, discovered in the late 18th century, was used in the 1880s for the fumigation of citrus trees in California. Its use spread to other countries for the fumigation of silos, goods wagons, ships, and mills. Its light weight and rapid dispersal meant its application had to take place under tents or in enclosed areas. Research by Fritz Haber of the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry led to the founding in 1919 of Deutsche Gesellschaft für Schädlingsbekämpfung mbH (Degesch), a state-controlled consortium formed to investigate military use of the chemical. Chemists at Degesch added a cautionary eye irritant to a less volatile cyanide compound which reacted with water in the presence of heat to become hydrogen cyanide. The new product was marketed as the pesticide Zyklon (cyclone). As a similar formula had been used as a weapon by the Germans during World War I, Zyklon was soon banned.
Deutsche Gold- und Silber-Scheideanstalt (German Gold and Silver Refinery; Degussa) became sole owners of Degesch in 1922. There, beginning in 1922, , Bruno Tesch, and others worked on packaging hydrogen cyanide in sealed canisters along with a cautionary eye irritant and adsorbent stabilizers such as diatomaceous earth. The new product was also labelled as Zyklon, but it became known as Zyklon B to distinguish it from the earlier version. Heerdt was named the inventor of Zyklon B in the Degesch patent application (number DE 438818) dated 20 June 1922. The Deutsches Patent- und Markenamt awarded the patent on 27 December 1926. Beginning in the 1920s, Zyklon B was used at U.S. Customs facilities along the Mexican border to fumigate the clothing of border crossers. | 1 | Applied and Interdisciplinary Chemistry |
Copper(II) glycinate (IUPAC suggested name: bis(glycinato)copper(II)) refers to the coordination complex of copper(II) with two equivalents of glycinate, with the formula [Cu(glycinate)(HO)] where x = 1 (monohydrate) or 0 (anhydrous form). The complex was first reported in 1841, and its chemistry has been revisited many times, particularly in relation to the isomerisation reaction between the cis and trans forms which was first reported in 1890.
All forms are blue solids, with varying degrees of water solubility. A practical application of the compound is as a source of dietary copper in animal feeds. | 0 | Theoretical and Fundamental Chemistry |
Oxidation originally implied a reaction with oxygen to form an oxide. Later, the term was expanded to encompass substances that accomplished chemical reactions similar to those of oxygen. Ultimately, the meaning was generalized to include all processes involving the loss of electrons or the increase in the oxidation state of a chemical species. Substances that have the ability to oxidize other substances (cause them to lose electrons) are said to be oxidative or oxidizing, and are known as oxidizing agents, oxidants, or oxidizers. The oxidant removes electrons from another substance, and is thus itself reduced. Because it "accepts" electrons, the oxidizing agent is also called an electron acceptor. Oxidants are usually chemical substances with elements in high oxidation states (e.g., , , , , ), or else highly electronegative elements (e.g. O, F, Cl, Br, I) that can gain extra electrons by oxidizing another substance.
Oxidizers are oxidants, but the term is mainly reserved for sources of oxygen, particularly in the context of explosions. Nitric acid is a strong oxidizer. | 0 | Theoretical and Fundamental Chemistry |
To address some of the problems with land-mines (see ), weapons manufacturers are now experimenting with area-denial weapons which need human command to operate. Such systems are usually envisioned as a combination of either explosives, pre-targeted artillery shelling or smartguns with remote sensing equipment (sound, vibration, sight/thermal). By not posing a long-term risk, and by having some level of IFF capability (automatic or human-decision-based), these systems aim to achieve compliance with the Ottawa Treaty, as for example the Metal Storm ADWS (Area Denial Weapons System). | 1 | Applied and Interdisciplinary Chemistry |
In contrast to the relatively early flowering of organotransition-metal chemistry (1955 to the present), the corresponding development of actinide organometallic chemistry has taken place largely within the past 15 or so years. During this period, 5f organometallic science has blossomed, and it is now apparent that the actinides have a rich, intricate, and highly informative organometallic chemistry. Intriguing parallels to and sharp differences from the d-block elements have emerged. Actinides can coordinate the organic active groups or bind to carbon by the covalent bonds. | 0 | Theoretical and Fundamental Chemistry |
Polyurethane dispersion, or PUD, is understood to be a polyurethane polymer resin dispersed in water, rather than a solvent, although some cosolvent maybe used. Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or nonionic hydrophiles like PEG (polyethylene glycol) incorporated into, or pendant from, the polymer backbone. Two component polyurethane dispersions are also available. | 0 | Theoretical and Fundamental Chemistry |
* Distinguished Service Award of the Society for Applied Spectroscopy (1985)
* Garvan Medal from the American Chemical Society (1986)
* Fisher Award in Analytical Chemistry from the American Chemical Society (1993)
* Wilfred R. and Ann Lee Konneker Award from Ohio University (2003)
* Founder's Citation Award from Ohio University (2003–2004)
* Great American Award from the Stan Hywet Foundation (2004)
* In Tribute to Public Service Award (2006)
* Leona Hughes Inspiration Award by the Women in Philanthropy of Ohio University (2010)
* President's Medal of Merit from the Republic of Hungary (2012)
* Lifetime Ambassador's Award from OneCommunity (2014)
* Alumni Association's Medal of Merit from Ohio University
* Alumna of the Year Award from Ohio University
* John C. Baker Founders Award from Ohio University | 0 | Theoretical and Fundamental Chemistry |
The color reaction between borates and curcumin is used for the spectrophotometric determination and quantification of boron present in food or materials. Curcumin is a yellow coloring natural pigment found in the root stocks of some Curcuma species, especially Curcuma longa (turmeric), in concentrations up to 3%. In the so-called curcumin method for boron quantification it serves as reaction partner for boric acid. The reaction is very sensitive and so the smallest quantities of boron can be detected. The maximum absorbance at 540 nm for rosocyanine is used in this colorimetric method. The formation of rosocyanine depends on the reaction conditions. The reaction is carried out preferentially in acidic solutions containing hydrochloric or sulfuric acid. The color reaction also takes place under different conditions; however, in alkaline solution, gradual decomposition is observed. The reaction might be disturbed at higher pH values, interfering with other compounds.
Rosocyanine is formed as a 2:1 complex from curcumin and boric acid in acidic solutions. The boron complexes formed with rosocyanine are dioxaborines (here a 1,3,2-dioxaborine). Curcumin possesses a 1,3-diketone structure and can therefore be considered as a chelating agent. Unlike the simpler 1,3-diketone–containing compound acetylacetone (which forms acetylacetonate complexes with metals), the entire skeleton of curcumin is in resonance with the 1,3-dicarbonyl section, making the backbone an extended conjugated system. Investigations of the structure have shown that the positive charge is distributed throughout the molecule. In rosocyanine, the two curcumin moieties are not coplanar but rather perpendicular relative to one another (as seen in the 3D model), as a result of the tetrahedral geometry of tetracoordinate boron. The same applies to rubrocurcumin.
In order to exclude the presence of other materials during the boron quantification using the curcumin method, a variant of the process was developed. In this process, 2,2-dimethyl-1,3-hexanediol or 2-ethyl-1,3-hexanediol are added, in addition to curcumin, to a neutral solution of the boron-containing solution. The complex formed between boron and the 1,3-hexanediol derivative is removed from the aqueous solution by extraction in an organic solvent. Acidification of the organic phase yields rubrocyanine, which can be detected by colorimetric methods. The reaction of curcumin with borates in presence of oxalic acid produces the coloring compound rubrocurcumin. | 0 | Theoretical and Fundamental Chemistry |
British Standard Pipe (BSP) is a set of technical standards for screw threads that has been adopted internationally for interconnecting and sealing pipes and fittings by mating an external (male) thread with an internal (female) thread. It has been adopted as standard in plumbing and pipe fitting, except in North America, where NPT and related threads are used. | 1 | Applied and Interdisciplinary Chemistry |
The homogeneous wave equation (i.e. Eq. () when is zero) has solutions for travelling waves of permanent form propagating in either the negative or positive -direction. For the inhomogeneous case, considering waves propagating in the positive -direction, Green proposes an approximate solution:
Then
Now the left-hand side of Eq. () becomes:
So the proposed solution in Eq. () satisfies Eq. (), and thus also Eq. () apart from the above two terms proportional to and , with The error in the solution can be made of order provided
This has the solution:
Using Eq. () and the transformation from to , the approximate solution for the surface elevation is
where the constant has been set to one, without loss of generality. Waves travelling in the negative -direction have the minus sign in the argument of function reversed to a plus sign. Since the theory is linear, solutions can be added because of the superposition principle. | 1 | Applied and Interdisciplinary Chemistry |
The term hard soap originates from the soap production process. During this process, the addition of salt (sodium chloride) to boiling soap mixed with a substantial amount of water causes the soap nucleus to separate and solidify, making it "harder" and allowing it to float on the surface. | 0 | Theoretical and Fundamental Chemistry |
Major developments: Large-calibre artillery weighing several thousand kg are produced in Europe during the early 15th century and spread to the Ottoman Empire. Modifiable two wheeled gun carts known as limbers and caissons appear, greatly improving the mobility of artillery. The matchlock arquebus, the first firearm with a trigger mechanism, appears in Europe by 1475. Rifled barrels also appear in the late 15th century. The term musket is used for the first time in 1499. Rocket launchers are used in battle by the Ming dynasty and the Korean kingdom of Joseon develops a mobile rocket launcher vehicle called the hwacha. Chinese style bombs are used in Japan by 1468 at the latest. | 1 | Applied and Interdisciplinary Chemistry |
The Indian Ocean Gyre, located in the Indian Ocean, is, like the South Atlantic Gyre, bordered by the Intertropical Convergence Zone in the north and the Antarctic Circumpolar Current to the south. The South Equatorial Current forms the northern boundary of the Indian Ocean Gyre as it flows west along the equator towards the east coast of Africa. At the coast of Africa, the South Equatorial Current is split by Madagascar into the Mozambique Current, flowing south through the Mozambique Channel, and the East Madagascar Current, flowing south along the east coast of Madagascar, both of which are western boundary currents. South of Madagascar the two currents join to form the Agulhas Current. The Agulhas Current flows south until it joins the Antarctic Circumpolar Current, which flows east at the southern edge of the Indian Ocean Gyre. Due to the African continent not extending as far south as the Indian Ocean Gyre, some of the water in the Agulhas Current "leaks" into the Atlantic Ocean, with potentially important effects for global thermohaline circulation. The gyre circulation is completed by the north flowing West Australian Current, which forms the eastern boundary of the gyre. | 1 | Applied and Interdisciplinary Chemistry |
Proline-, glutamic acid- and leucine-rich protein 1 (PELP1) also known as modulator of non-genomic activity of estrogen receptor (MNAR) and transcription factor HMX3 is a protein that in humans is encoded by the PELP1 gene. is a transcriptional corepressor for nuclear receptors such as glucocorticoid receptors and a coactivator for estrogen receptors.
Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1) is transcription coregulator and modulates functions of several hormonal receptors and transcription factors. PELP1 plays essential roles in hormonal signaling, cell cycle progression, and ribosomal biogenesis. PELP1 expression is upregulated in several cancers; its deregulation contributes to hormonal therapy resistance and metastasis; therefore, PELP1 represents a novel therapeutic target for many cancers. | 1 | Applied and Interdisciplinary Chemistry |
*Bailyn, M. (1994). A Survey of Thermodynamics, American Institute of Physics Press, New York, .
*Beattie, J.A., Oppenheim, I. (1979). Principles of Thermodynamics, Elsevier, Amsterdam, .
*Born, M. (1921). Kritische Betrachtungen zur traditionellen Darstellung der Thermodynamik, Physik. Zeitschr. 22: 218–224.
*Bryan, G.H. (1907). Thermodynamics. An Introductory Treatise dealing mainly with First Principles and their Direct Applications, B.G. Teubner, Leipzig.
*Buchdahl, H.A. (1957/1966). The Concepts of Classical Thermodynamics, Cambridge University Press, London.
*Callen, H.B. (1960/1985). Thermodynamics and an Introduction to Thermostatistics, second edition, John Wiley & Sons, New York, .
* A translation may be found [http://neo-classical-physics.info/uploads/3/0/6/5/3065888/caratheodory_-_thermodynamics.pdf here] . A partly reliable translation is to be found at Kestin, J. (1976). The Second Law of Thermodynamics, Dowden, Hutchinson & Ross, Stroudsburg PA.
*Haase, R. (1971). Survey of Fundamental Laws, chapter 1 of Thermodynamics, pages 1–97 of volume 1, ed. W. Jost, of Physical Chemistry. An Advanced Treatise, ed. H. Eyring, D. Henderson, W. Jost, Academic Press, New York, lcn 73–117081.
*Kirkwood, J.G., Oppenheim, I. (1961). Chemical Thermodynamics, McGraw–Hill, New York. | 0 | Theoretical and Fundamental Chemistry |
Many governments impose strict regulations regarding the maximum chemical oxygen demand allowed in waste water before they can be returned to the environment. For example, in Switzerland, a maximum oxygen demand between 200 and 1000 mg/L must be reached before waste water or industrial water can be returned to the environment [https://web.archive.org/web/20040310122559/http://www.csem.ch/corporate/Report2002/pdf/p56.pdf]. | 0 | Theoretical and Fundamental Chemistry |
The sub-tropical Northern Atlantic is known to have both cyclonic and anticyclonic eddies that are associated with high surface chlorophyll and low surface chlorophyll, respectively. The presence of chlorophyll and higher levels of chlorophyll allows this region to support higher biomass of phytoplankton, as well as, supported by areas of increased vertical nutrient fluxes and transportation of biological communities. This area of the Atlantic is also thought to be an ocean desert, which creates an interesting paradox due to it hosting a variety of large pelagic fish populations and apex predators.
These mesoscale eddies have shown to be beneficial in further creating ecosystem-based management for food web models to better understand the utilization of these eddies by both the apex predators and their prey. Gaube et al. (2018), used “Smart” Position or Temperature Transmitting tags (SPOT) and Pop-Up Satellite Archival Transmitting tags (PSAT) to track the movement and diving behavior of two female white sharks (Carcharodon carcharias) within the eddies. The eddies were defined using sea surface height (SSH) and contours using the horizontal speed-based radius scale. This study found that the white sharks dove in both cyclones but favored the anticyclone which had three times more dives as the cyclonic eddies. Additionally, in the Gulf Stream eddies, the anticyclonic eddies were 57% more common and had more dives and deeper dives than the open ocean eddies and Gulf Stream cyclonic eddies.
Within these anticyclonic eddies, the isotherm was displaced 50 meters downward allowing for the warmer water to penetrate deeper in the water column. This warmer water displacement may allow for the white sharks to make longer dives without the added energetic cost from thermal regulation in the cooler cyclones. Even though these anticyclonic eddies resulted in lower levels of chlorophyll in comparison to the cyclonic eddies, the warmer waters at deeper depths may allow for a deeper mixed layer and higher concentration of diatoms which in turn result in higher rates of primary productivity. Furthermore, the prey populations could be distributed more within these eddies attracting these larger female sharks to forage in this mesopelagic zone. This diving pattern may follow a diel vertical migration but without more evidence on the biomass of their prey within this zone, these conclusions cannot be made only using this circumstantial evidence.
The biomass in the mesopelagic zone is still understudied leading to the biomass of fish within this layer to potentially be underestimated. A more accurate measurement on this biomass may serve to benefit the commercial fishing industry providing them with additional fishing grounds within this region. Moreover, further understanding this region in the open ocean and how the removal of fish in this region may impact this pelagic food web is crucial for the fish populations and apex predators that may rely on this food source in addition to making better ecosystem-based management plans. | 1 | Applied and Interdisciplinary Chemistry |
An example of splicing aberration (exon skipping) caused by a mutation in the donor splice site in the exon 8 of MLH1 gene that led to colorectal cancer is given below. This example shows that a mutation in a splice site within a gene can lead to a profound effect in the sequence and structure of the mRNA, and the sequence, structure and function of the encoded protein, leading to disease. | 1 | Applied and Interdisciplinary Chemistry |
Hyrax middens contain well-preserved micro plant material including pollen, which is sealed in middens by hyraceum, protecting it from microbial activity and decay. The earliest study of fossil pollen from a hyrax midden was undertaken in the late 1950s by Pons and Quézel. in the Hoggar Massif of Algeria, whereas the first palynological analyses of southern African middens were undertaken during the late 1980s and early 1990s, and demonstrated that hyrax middens are very useful as pollen and microfossil traps. Subsequently, hyrax middens have been become an important archive for fossil pollen analysis in South Africa and Namibia. Studies of fossil pollen in hyrax middens have also been undertaken in Jordan Ethiopia, Yemen and Oman | 0 | Theoretical and Fundamental Chemistry |
The word patina comes from the Italian patina (shallow layer of deposit on a surface), derived from the Latin patĭna (pan, shallow dish). Figuratively, patina can refer to any fading, darkening, or other signs of age, which are felt to be natural or unavoidable (or both).
The chemical process by which a patina forms or is deliberately induced is called patination, and a work of art coated by a patina is said to be patinated. | 1 | Applied and Interdisciplinary Chemistry |
The ocean biological pump is the oceans biologically driven sequestration of carbon from the atmosphere and land runoff to the deep ocean interior and seafloor sediments. The biological pump is not so much the result of a single process, but rather the sum of a number of processes each of which can influence biological pumping. The pump transfers about 11 billion tonnes of carbon every year into the oceans interior. An ocean without the biological pump would result in atmospheric CO levels about 400 ppm higher than the present day.
Most carbon incorporated in organic and inorganic biological matter is formed at the sea surface where it can then start sinking to the ocean floor. The deep ocean gets most of its nutrients from the higher water column when they sink down in the form of marine snow. This is made up of dead or dying animals and microbes, fecal matter, sand and other inorganic material.
The biological pump is responsible for transforming dissolved inorganic carbon (DIC) into organic biomass and pumping it in particulate or dissolved form into the deep ocean. Inorganic nutrients and carbon dioxide are fixed during photosynthesis by phytoplankton, which both release dissolved organic matter (DOM) and are consumed by herbivorous zooplankton. Larger zooplankton - such as copepods, egest fecal pellets - which can be reingested, and sink or collect with other organic detritus into larger, more-rapidly-sinking aggregates. DOM is partially consumed by bacteria and respired; the remaining refractory DOM is advected and mixed into the deep sea. DOM and aggregates exported into the deep water are consumed and respired, thus returning organic carbon into the enormous deep ocean reservoir of DIC.
A single phytoplankton cell has a sinking rate around one metre per day. Given that the average depth of the ocean is about four kilometres, it can take over ten years for these cells to reach the ocean floor. However, through processes such as coagulation and expulsion in predator fecal pellets, these cells form aggregates. These aggregates have sinking rates orders of magnitude greater than individual cells and complete their journey to the deep in a matter of days.
About 1% of the particles leaving the surface ocean reach the seabed and are consumed, respired, or buried in the sediments. The net effect of these processes is to remove carbon in organic form from the surface and return it to DIC at greater depths, maintaining a surface-to-deep ocean gradient of DIC. Thermohaline circulation returns deep-ocean DIC to the atmosphere on millennial timescales. The carbon buried in the sediments can be subducted into the earth's mantle and stored for millions of years as part of the slow carbon cycle (see next section). | 0 | Theoretical and Fundamental Chemistry |
The MCD signal ΔA is derived via the absorption of the LCP and RCP light as
This signal is often presented as a function of wavelength λ, temperature T or magnetic field H. MCD spectrometers can simultaneously measure absorbance and ΔA along the same light path. This eliminates error introduced through multiple measurements or different instruments that previously occurred before this advent.
The MCD spectrometer example shown below begins with a light source that emits a monochromatic wave of light. This wave is passed through a Rochon prism linear polarizer, which separates the incident wave into two beams that are linearly polarized by 90 degrees. The two beams follow different paths- one beam (the extraordinary beam) traveling directly to a photomultiplier (PMT), and the other beam (the ordinary beam) passing through a photoelastic modulator (PEM) oriented at 45 degrees to the direction of the ordinary ray polarization. The PMT for the extraordinary beam detects the light intensity of the input beam. The PEM is adjusted to cause an alternating plus and minus 1/4 wavelength shift of one of the two orthogonal components of the ordinary beam. This modulation converts the linearly polarized light into circularly polarized light at the peaks of the modulation cycle. Linearly polarized light can be decomposed into two circular components with intensity represented as
The PEM will delay one component of linearly polarized light with a time dependence that advances the other component by 1/4 λ (hence, quarter-wave shift). The departing circularly polarized light oscillates between RCP and LCP in a sinusoidal time-dependence as depicted below:
The light finally travels through a magnet containing the sample, and the transmittance is recorded by another PMT. The schematic is given below:
The intensity of light from the ordinary wave that reaches the PMT is governed by the equation:
Here A and A are the absorbances of LCP or RCP, respectively; ω is the modulator frequency – usually a high acoustic frequency such as 50 kHz; t is time; and δ is the time-dependent wavelength shift.
This intensity of light passing through the sample is converted into a two-component voltage via a current/voltage amplifier. A DC voltage will emerge corresponding to the intensity of light passed through the sample. If there is a ΔA, then a small AC voltage will be present that corresponds to the modulation frequency, ω. This voltage is detected by the lock in amplifier, which receives its reference frequency, ω, directly from the PEM. From such voltage, ΔA and A can be derived using the following relations:
where V is the (DC) voltage measured by the PMT from the extraordinary wave, and V is the DC component of the voltage measured by the PMT for the ordinary wave (measurement path not shown in the diagram).
Some superconducting magnets have a small sample chamber, far too small to contain the entire optical system. Instead, the magnet sample chamber has windows on two opposite sides. Light from the source enters one side, interacts with the sample (usually also temperature controlled) in the magnetic field, and exits through the opposite window to the detector. Optical relay systems that allow the source and detector each to be about a meter from the sample are typically employed. This arrangement avoids many of the difficulties that would be encountered if the optical apparatus had to operate in the high magnetic field, and also allows for a much less expensive magnet. | 0 | Theoretical and Fundamental Chemistry |
A dusty plasma contains tiny charged particles of dust (typically found in space). The dust particles acquire high charges and interact with each other. A plasma that contains larger particles is called grain plasma. Under laboratory conditions, dusty plasmas are also called complex plasmas. | 0 | Theoretical and Fundamental Chemistry |
* Halliday, Alex N., Der-Chuen Lee, John N. Christensen, Mark Rehkämper, Wen Yi, Xiaozhong Luo, Chris M. Hall, Chris J. Ballentine, Thomas Pettke, and Claudine Stirling. "Applications of multiple collector-ICPMS to cosmochemistry, geochemistry, and paleoceanography." Geochimica et Cosmochimica Acta 62, no. 6 (1998): 919–940.
* Amelin, Yuri, Angela Kaltenbach, Tsuyoshi Iizuka, Claudine H. Stirling, Trevor R. Ireland, Michail Petaev, and Stein B. Jacobsen. "U–Pb chronology of the Solar System's oldest solids with variable 238U/235U." Earth and Planetary Science Letters 300, no. 3-4 (2010): 343–350.
* Stirling, Claudine H., Morten B. Andersen, Emma-Kate Potter, and Alex N. Halliday. "Low-temperature isotopic fractionation of uranium." Earth and Planetary Science Letters 264, no. 1-2 (2007): 208–225.
* Gutjahr, Marcus, Martin Frank, Claudine H. Stirling, Veronika Klemm, Tina Van de Flierdt, and Alex N. Halliday. "Reliable extraction of a deepwater trace metal isotope signal from Fe–Mn oxyhydroxide coatings of marine sediments." Chemical Geology 242, no. 3-4 (2007): 351–370.
* Rehkämper, Mark, Maria Schönbächler, and Claudine H. Stirling. "Multiple collector ICP‐MS: Introduction to instrumentation, measurement techniques and analytical capabilities." Geostandards Newsletter 25, no. 1 (2001): 23–40. | 0 | Theoretical and Fundamental Chemistry |
Electrometallurgy involves metallurgical processes that take place in some form of electrolytic cell. The most common types of electrometallurgical processes are electrowinning and electro-refining. Electrowinning is an electrolysis process used to recover metals in aqueous solution, usually as the result of an ore having undergone one or more hydrometallurgical processes. The metal of interest is plated onto the cathode, while the anode is an inert electrical conductor. Electro-refining is used to dissolve an impure metallic anode (typically from a smelting process) and produce a high purity cathode. Fused salt electrolysis is another electrometallurgical process whereby the valuable metal has been dissolved into a molten salt which acts as the electrolyte, and the valuable metal collects on the cathode of the cell. The fused salt electrolysis process is conducted at temperatures sufficient to keep both the electrolyte and the metal being produced in the molten state. The scope of electrometallurgy has significant overlap with the areas of hydrometallurgy and (in the case of fused salt electrolysis) pyrometallurgy. Additionally, electrochemical phenomena play a considerable role in many mineral processing and hydrometallurgical processes. | 1 | Applied and Interdisciplinary Chemistry |
An efficient way to synthesize protein-polymer hybrid nanoparticles is to take advantage of photoinitiated reversible addition−fragmentation chain transfer (RAFT) polymerization-induced self-assembly(PISA) by using multi-RAFT modified bovine serum albumin (BSA) as a macromolecular chain transfer agent. RAFT mediated growth of the PHPMA chains will graft from the BSA-RAFT, and increase the hydrophobicity of the star BSA−PHPMA conjugates. At the critical aggregation concentration, they form nanoparticles due to the hydrophobic interactions. The resulting nanoparticles show excellent encapsulation capability for both hydrophobic and hydrophilic molecules, such as cancer drugs and DNA.
A rather easy method to prepare protein-polymer hybrid nanoparticles is nanoprecipitation. Spherical nanoparticles composed of BSA-PMMA with diameters of around 100 nm were obtained and the water insoluble chemotherapeutic drug camptothecin was encapsulated within the hydrophobic core consisting of PMMA. Such protein-polymer hybrid nanoparticles possess tunable sizes and surface charges, have attractive bio-compatibilities and allow efficient cell uptake. Camptothecin-encapsulated BSA-PMMA nanoparticles revealed enhanced anti-tumor activity both in vitro and in animals.
Beyond the nanoscale, protein-polymer conjugate could also be used as building blocks for constructing more complicated structures such as microcapsules through hydrophobic interactions. By performing pickering emulsion technique to process BSA–pNIPAm nanoconjugates into hollowed microcapsules consisting of a closely packed monolayer of conjugated protein–polymer building blocks (named proteinosomes). These proteinosomes exhibit protocellular properties such as guest molecule encapsulation, selective permeability, controllable mobilization, gene-directed protein synthesis and membrane-gated internalized enzyme catalysis.
Based on the above-mentioned method, a multi responsive microcapsule has been synthesized by incorporating photoswitchable spiropyran units and the thermoresponsive monomer N-isopropylacrylamide into the membrane. Stimuli responsive membrane exhibited advantages in the capture and release of different-molecular-weight products by opening and closing the photoresponsive spiropyran ligands, under body temperature, room temperature, UV, redox.
Another effective way to modulate the permeability of microcapsules was based on a self-sacrificing strategy. By selectively using lysozyme and BSA as building blocks as well as self-sacrificing components, the corresponding pores could be generated in the membrane, and then the permeability of the generated microcapsules could be increased from10 kDa to 22 kDa and then to 71 kDa. By loading FITC-Lys (14 kDa), RBITCdextran (70 kDa) and DNA (90 kDa) into the microcapsules, a programmed release of the encapsulants from low molecular weight to high molecular weight was realized.
Using similar strategy, pH-sensitive protein-polymer microcapsules were developed. Both doxycycline (DOX) and folic acid were incorporated onto the surface of protein covalently. The very low toxicity of polymer-protein nanoconjugates effectively avoided the high toxicity of DOX, which is expected to not only reduce toxic side effects, but also improve anticancer efficiency in vitro examinations. | 1 | Applied and Interdisciplinary Chemistry |
The distribution of the different laminin isoforms is tissue-specific. Laminin–111 is predominantly expressed in the embryonic epithelium, but can also be found in some adult epithelium such as the kidney, liver, testis, ovaries, and brain blood vessels. Different levels of expression of α chains have a large influence on the differential expression of laminin, thereby determining the isoform produced. From studying a mouse model, it was found that transcription factors present in the parietal endoderm regulate the expression of the α1 and large amounts of laminin-111 are produced. | 0 | Theoretical and Fundamental Chemistry |
Etiocholanolone glucuronide (ETIO-G) is an endogenous, naturally occurring metabolite of testosterone. It is formed in the liver from etiocholanolone by UDP-glucuronyltransferases. ETIO-G has much higher water solubility than etiocholanolone and is eventually excreted in the urine via the kidneys. Along with androsterone glucuronide, it is one of the major inactive metabolites of testosterone. | 1 | Applied and Interdisciplinary Chemistry |
Alexander Nikiforovich Popov ( 1840 – 18 August 1881) was a Russian organic chemist. He taught chemistry at the University of Kazan and at the University of Warsaw. He discovered what is now called Popovs Rule (or Popoffs Rule) which states that in the oxidation of an unsymmetrical ketone, the cleavage of the C−CO bond so that the smaller alkyl group is retained.
Popov was born in Vitebsk where his father was a military officer. He studied at Kazan University and attended the chemistry lectures of A.M. Butlerov. Graduating in 1865 he worked as a chemical lab assistant and in 1868 received a masters degree and became a professor at the University of Warsaw. In 1871 he went to work in Bonn with August Kekulé and E.K. Theodor Zinkce. It was during this period that he established the so-called Popovs Rule on the oxidation of benzene homologues being directed to the carbon atom bonded directly to the ring. He received a doctorate in 1872 for work on ketone oxidation. He identified an ordering of stability of radicals based on his examination of oxidation of asymmetric ketones which has been called Popov's rule. He served in the Russo-Turkish War (1877-1878). He introduced the use of potassium dichromate (KCrO) and sulphuric acid as oxidation reagent in organic analysis. | 0 | Theoretical and Fundamental Chemistry |
* 82 km north of Basra in Iraq at the town of Al-Qurnah is the confluence of the rivers Tigris and Euphrates, forming the Shatt al-Arab.
* At Devprayag in India, the Ganges River originates at the confluence of the Bhagirathi and the Alaknanda; see images above.
* Near Allahabad, India, the Yamuna flows into the Ganges. In Hinduism, this is a pilgrimage site for ritual bathing; during a Kumbh Mela event tens of millions of people visit the site. In Hindu belief the site is held to be a triple confluence (Triveni Sangam), the third river being the metaphysical (not physically present) Sarasvati.
*Karad, in Maharashtra, India, is the site of the Pritisangam (meaning: Lovely Confluence), a T-shaped confluence of Krishna River and Koyna River, where Koyna River mergers into Krishna River forming a T-shape and then the merged rivers flow to the east as Krishna River.
* Kuala Lumpur, the capital of Malaysia, is where the Gombak River (previously known as Sungai Lumpur, which means "muddy river") flows into the Klang River at the site of the Jamek Mosque. Recently, the Kolam Biru (Blue Pool), a pool with elaborate fountains, has been installed at the apex of the confluence.
*Both Taipei and New Taipei are where the Dahan and Xindian meet and flow into the Tamsui River.
* The Nam Khan River flows into the Mekong at Luang Prabang in Laos.
* The Jialing flows into the Yangtze at Chongqing in China. The confluence forms a focal point in the city, marked by Chaotianmen Square, built in 1998.
* In the Far East, the Amur forms the international boundary between China and Russia. The Ussuri, which also demarcates the border, flows into the Amur at a point midway between Fuyuan in China and Khabarovsk in Russia. The apex of the confluence is located in a rural area, part of China, where a commemorative park, Dongji Square, has been built; it features an enormous sculpture representing the Chinese character for "East". The Amur-Ussuri border region was the location of the Sino-Soviet border conflict of 1969; the borderline near the confluence was settled peacefully by treaty in 2008.
* In Georgia, in the town of Pasanauri on the southern slopes of the Caucasus Mountains, the Tetri Aragvi ("White Aragvi") is joined by the Shavi Aragvi ("Black Aragvi"). Together, these two rivers continue as the Aragvi River. The conflux is known for its dramatic visual contrast of the two rivers. | 1 | Applied and Interdisciplinary Chemistry |
The Falcon Concentrator is a type of gravity separation device for the recovery of valuable metals and minerals. There are three types of Falcon Concentrators: Falcon Semi-Batch (SB), Falcon Continuous (C) and Falcon Ultra-Fine (UF). All models of Falcon Concentrator rely on the creation of centrifugal forces by way of a rapidly rotating, vertical bowl in order to stratify and separate particles based on weight. The amount of gravitational force generated and the method of collecting these heavier particles differs for each model. | 1 | Applied and Interdisciplinary Chemistry |
The European Synchrotron Radiation Facility (ESRF) as well as many other synchrotron facilities as the three major synchrotron user facilities in the United States all have beamlines equipped with laser heating systems. The respective beamlines with laser heating systems are at the ESRF ID27, ID18, and ID24; at the Advanced Photon Source (APS), 13-ID-D GSECARS and 16-ID-B HP-CAT; at the National Synchrotron Light Source, X17B3; and at the Advanced Light Source, 12.2.2. Laser heating has become a routine technique in high-pressure science but the reliability of temperature measurement is still controversial. | 0 | Theoretical and Fundamental Chemistry |
PFE is calculated as the probability of gene-specific entropy being higher than times all other background set entropies individually. The variable is sampled from the Gamma distribution with shape 1 and rate 0.5. Also, as the last step, the expected value for the sum of gene-specific entropy probability for each background is reported as PFE. That probability is based on the Dirichlet distribution generated in the previous step. | 1 | Applied and Interdisciplinary Chemistry |
Sulfidation is relevant to the formation of sulfide minerals.
A large scale application of sulfidation is the conversion of molybdenum oxides to the corresponding sulfides. This conversion is a step in the preparation of catalysts for hydrodesulfurization wherein alumina impregnated with molybdate salts are converted to molybdenum disulfide by the action of hydrogen sulfide.
In organosulfur chemistry, sulfiding is often called thiation. The preparation of thioamides from amides involves thiation. A typical reagent is phosphorus pentasulfide (PS). The idealized equation for this conversion is:
:RC(O)NH + 1/4 PS → RC(S)NH + 1/4 PSO
This conversion where an oxygen atom in the amide function is replaced by a sulfur atom involves no redox reaction. | 0 | Theoretical and Fundamental Chemistry |
The relevant boundary conditions are, in case of the no-slip boundary conditions at the channel top and bottom and | 1 | Applied and Interdisciplinary Chemistry |
The FDA approved levomilnacipran for treating major depressive disorder. This approval was based on the results of five clinical trials. The trials included one 10-week phase II and four 8-week phase III. Four of the five trials demonstrated a statistically significant superiority to placebo as measured by the Montgomery–Åsberg Depression Rating Scale. Superiority to placebo was also demonstrated by improvement in the Sheehan Disability Scale. | 0 | Theoretical and Fundamental Chemistry |
Klyne met Barbara Clayton in 1947 while both were employed at the Medical Research Council; they married in 1949. | 0 | Theoretical and Fundamental Chemistry |
Hydrocarbon utilizing microorganisms, mostly Cladosporium resinae and Pseudomonas aeruginosa and sulfate reducing bacteria, colloquially known as "HUM bugs", are commonly present in jet fuel. They live in the water-fuel interface of the water droplets, form dark black/brown/green, gel-like mats, and cause microbial corrosion to plastic and rubber parts of the aircraft fuel system by consuming them, and to the metal parts by the means of their acidic metabolic products. They are also incorrectly called algae due to their appearance. FSII, is added to fuel as a growth retardant. There are about 250 kinds of bacteria that can live in jet fuel, but fewer than a dozen are meaningfully harmful. | 1 | Applied and Interdisciplinary Chemistry |
One example to build a library is a classified as a rare-cutting restriction endonuclease such as NotI. In order to construct and characterize a library based from NotI-digested human DNA, random clones were analyzed by restriction mapping. Due to the wide distribution of fragment sizes made by the complete digestion with NotI, the library was constructed into two fractions, low and high plasmid concentration. Clones that possessed unique end fragments were then analyzed by hybridization to Pulse Field Gradient (PFG) Southern blots. Examining the results gathered for single and double digests of human DNA with enzymes NotI, BssHII, and NruI, a restriction map with 850 kb was region containing the linking and jumping clones were created. Furthermore, NotI fragments of 250 and 350 kb jumps were evident in the two end clones derived corresponding to genetic distances of 0.25 and 0.35 cM. | 1 | Applied and Interdisciplinary Chemistry |
The Turner angle Tu, introduced by Ruddick(1983) and named after J. Stewart Turner, is a parameter used to describe the local stability of an inviscid water column as it undergoes double-diffusive convection. The temperature and salinity attributes, which generally determine the water density, both respond to the water vertical structure. By putting these two variables in orthogonal coordinates, the angle with the axis can indicate the importance of the two in stability. Turner angle is defined as:
where tan is the four-quadrant arctangent; α is the coefficient of thermal expansion; β is the equivalent coefficient for the addition of salinity, sometimes referred to as the "coefficient of saline contraction"; θ is potential temperature; and S is salinity. The relation between Tu and stability is as shown
* If −45° < Tu < 45°, the column is statically stable.
* If −90° < Tu < −45°, the column is unstable to diffusive convection.
* If 45° < Tu < 90°, the column is unstable to salt fingering.
* If −90° > Tu or Tu > 90°, the column is statically unstable to Rayleigh–Taylor instability. | 1 | Applied and Interdisciplinary Chemistry |
Other oxygenates are available as additives for gasoline including ethanol and other ethers such as ETBE.
Ethanol has been advertised as a safe alternative by agricultural and other interest groups in the U.S. and Europe. In 2003, California was the first U.S. state to start replacing MTBE with ethanol.
An alternative to ethanol is ETBE, which is manufactured from ethanol and isobutene. Its performance as an additive is similar to MTBE, but due to the higher price of ethanol compared to methanol, it is more expensive.
Higher quality gasoline is also an alternative, so that additives such as MTBE are unnecessary. Iso-octane itself is used. MTBE plants can be retrofitted to produce iso-octane from isobutylene. | 1 | Applied and Interdisciplinary Chemistry |
The technique was developed in Wallonia in present-day Belgium during the Middle Ages. The Walloon method consisted of making pig iron in a blast furnace, followed by refining it in a finery forge. The process was devised in the Liège region, and spread into France and thence from the Pays de Bray to England before the end of the 15th century. Louis de Geer took it to Roslagen in Sweden in the early 17th century, where he employed Walloon ironmakers. Iron made there by this method was known in England as oregrounds iron. | 1 | Applied and Interdisciplinary Chemistry |
BioModels Development has benefited from the funds of the European Molecular Biology Laboratory, the Biotechnology and Biological Sciences Research Council, the Innovative Medicines Initiative, the Seventh Framework Programme (FP7), the National Institute of General Medical Sciences, the DARPA, and the National Center for Research Resources. | 1 | Applied and Interdisciplinary Chemistry |
Another way of storing energy is with the use of hydrazine. This molecule is related to ammonia and has the potential to be equally as useful as ammonia. It can be created from ammonia and hydrogen peroxide or via chlorine based oxidations. This makes it an even denser energy storing fuel. The downside of hydrazine is that it is very toxic and that it will react with oxygen quite violently. This makes it an ideal fuel for oxygen low area's such as space. Recent launched Iridium NEXT satellites have hydrazine as their source of energy. However toxic, this fuel has great potential, because safety measures can be increased sufficiently to safely transport and convert hydrazine back into hydrogen and ammonia. Researchers discovered a way to decompose hydrazine with a photo catalysis system that works over the entire visible-light region. This means that sunlight can not only be used to produce hydrazine, but also to produce hydrogen from this fuel. The decomposition of hydrazine is done with a p-n bilayer consisting of fullerene (C), also known as "buckeyballs" which is a n-type semiconductor and zinc phthalocyanine (ZnPc) which is a p-type semiconductor creating an organic photo catalysis system. This system uses visible light irradiation to excite electrons to the n-type semiconductor creating an electric current. The holes created in the p-type semiconductor are forced in the direction of the so called Nafion part of the device, which oxidizes hydrazine to nitrogen gas and dissolved hydrogen ions. This was done in the first compartment of the fuel cell. The hydrogen ions travel through a salt bridge to another compartment to be reduced to hydrogen gas by the electrons, gained by the interaction with light, from the first compartment. Thus creating hydrogen, which can be used in fuel cells. This promising studies shows that hydrazine is a solar fuel that has great potential to become very useful in the energy transition.
A different approach to hydrazine are the direct fuel cells. The concepts for these cells have been developed since the 1960s. Recent studies provide much better direct hydrazine fuel cells, for example with the use of hydrogen peroxide as an oxidant. Making the anode basic and the cathode acidic increased the power density a lot, showing high peaks of around 1 W/cm at a temperature of 80 degrees Celsius. As mentioned earlier the main weakness of direct hydrazine fuel cells is the high toxicity of hydrazine and its derivatives. However hydrous hydrazine, which is a water-like liquid retains the high hydrogen density and can be stored and transported safely using the existing fuel infrastructure. Researchers also aim for self-powered fuel cells involving hydrazine. These fuel cells make use of hydrazine in two ways, namely as the fuel for a direct fuel cell and as the splitting target. This means that one only needs hydrazine to produce hydrogen with this fuel cell, so no external power is needed. This is done with the use of iron doped cobalt sulfide nanosheets. The doping with iron decreases the free-energy changes of hydrogen adsorption and hydrazine dehydrogenation. This method has a 20 hour stability and 98% Faradaic efficiency, which is comparable with the best reported claims of self-powered hydrogen generating cells. | 0 | Theoretical and Fundamental Chemistry |
Certain poisonous substances to the body can delay the process of putrefaction. They include:
*Carbolic acid (Phenol)
*Arsenic and antimony
*Strychnine
*Nux vomica (plant)
*Zinc chloride, ZnCl
*Morphine
*Aconitine | 1 | Applied and Interdisciplinary Chemistry |
Bernoulli developed his principle from observations on liquids, and Bernoullis equation is valid for ideal fluids: those that are incompressible, irrotational, inviscid, and subjected to conservative forces. It is sometimes valid for the flow of gases: provided that there is no transfer of kinetic or potential energy from the gas flow to the compression or expansion of the gas. If both the gas pressure and volume change simultaneously, then work will be done on or by the gas. In this case, Bernoullis equation—in its incompressible flow form—cannot be assumed to be valid. However, if the gas process is entirely isobaric, or isochoric, then no work is done on or by the gas (so the simple energy balance is not upset). According to the gas law, an isobaric or isochoric process is ordinarily the only way to ensure constant density in a gas. Also the gas density will be proportional to the ratio of pressure and absolute temperature; however, this ratio will vary upon compression or expansion, no matter what non-zero quantity of heat is added or removed. The only exception is if the net heat transfer is zero, as in a complete thermodynamic cycle or in an individual isentropic (frictionless adiabatic) process, and even then this reversible process must be reversed, to restore the gas to the original pressure and specific volume, and thus density. Only then is the original, unmodified Bernoulli equation applicable. In this case the equation can be used if the flow speed of the gas is sufficiently below the speed of sound, such that the variation in density of the gas (due to this effect) along each streamline can be ignored. Adiabatic flow at less than Mach 0.3 is generally considered to be slow enough.
It is possible to use the fundamental principles of physics to develop similar equations applicable to compressible fluids. There are numerous equations, each tailored for a particular application, but all are analogous to Bernoullis equation and all rely on nothing more than the fundamental principles of physics such as Newtons laws of motion or the first law of thermodynamics. | 1 | Applied and Interdisciplinary Chemistry |
Larry Hench and colleagues at the University of Florida first developed these materials in 1969 and they have been further developed by his research team at the Imperial College London and other researchers worldwide. Hench began development by submitting a proposal hypothesis to the United States Army Medial Research and Development command in 1968 based upon his theory of the body rejecting metallic or polymeric material unless it was able to form a coating of hydroxyapatite which is found in bone. Hench and his team received funding for one year, and began development on what would become the 45S5 composition. The name "Bioglass" was trademarked by the University of Florida as a name for the original 45S5 composition. It should therefore only be used in reference to the 45S5 composition and not as a general term for bioactive glasses.
Through use of a phase diagram, Hench chose a composition of 45% , 24.5% , 24.5% , and 6% to allow for a large amount of and some in a matrix. The glass was batched, melted, and cast into small rectangular implants to be inserted into the femoral bone of rats for six weeks as developed by Dr. Ted Greenlee of the University of Florida. After six weeks, Dr. Greenlee reported "These ceramic implants will not come out of the bone. They are bonded in place. I can push on them, I can shove them, I can hit them and they do not move. The controls easily slide out." These findings were the basis of the first paper on 45S5 bioactive glass in 1971 which summarized that in vitro experiments in a calcium and phosphate ion deficient solution showed a developed layer of hydroxyapatite similar to the observed hydroxyapatite later in vivo by Dr. Greenlee. | 0 | Theoretical and Fundamental Chemistry |
In particle physics, (; ) is electromagnetic radiation produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic nucleus. The moving particle loses kinetic energy, which is converted into radiation (i.e., photons), thus satisfying the law of conservation of energy. The term is also used to refer to the process of producing the radiation. has a continuous spectrum, which becomes more intense and whose peak intensity shifts toward higher frequencies as the change of the energy of the decelerated particles increases.
Broadly speaking, or braking radiation is any radiation produced due to the acceleration (positive or negative) of a charged particle, which includes synchrotron radiation (i.e., photon emission by a relativistic particle), cyclotron radiation (i.e. photon emission by a non-relativistic particle), and the emission of electrons and positrons during beta decay. However, the term is frequently used in the more narrow sense of radiation from electrons (from whatever source) slowing in matter.
Bremsstrahlung emitted from plasma is sometimes referred to as free–free radiation. This refers to the fact that the radiation in this case is created by electrons that are free (i.e., not in an atomic or molecular bound state) before, and remain free after, the emission of a photon. In the same parlance, bound–bound radiation refers to discrete spectral lines (an electron "jumps" between two bound states), while free–bound radiation refers to the radiative combination process, in which a free electron recombines with an ion.
This article uses SI units, along with the scaled single-particle charge . | 0 | Theoretical and Fundamental Chemistry |
A Lewis acid-base reaction occurs when a molecule with a lone electron pair, or a base, donates its electrons to an electron-pair acceptor, also known as an acid. This can be shown in a reaction with a curved arrow pointing from the nonbonding electron pair to the electron acceptor. In a reaction involving Brønsted-Lowry acids and bases, the arrows are used in the same manner, and they help to indicate the attacking proton. In a Brønsted-Lowry acid-base reaction the arrow will begin from the acid, the proton acceptor, to the base, the proton donor. | 0 | Theoretical and Fundamental Chemistry |
The eutectoid composition of austenite is approximately 0.8% carbon; steel with less carbon content (hypoeutectoid steel) will contain a corresponding proportion of relatively pure ferrite crystallites that do not participate in the eutectoid reaction and cannot transform into pearlite. Likewise steels with higher carbon content (hypereutectoid steels) will form cementite before reaching the eutectoid point. The proportion of ferrite and cementite forming above the eutectoid point can be calculated from the iron/iron—carbide equilibrium phase diagram using the lever rule.
Steels with pearlitic (eutectoid composition) or near-pearlitic microstructure (near-eutectoid composition) can be drawn into thin wires. Such wires, often bundled into ropes, are commercially used as piano wires, ropes for suspension bridges, and as steel cord for tire reinforcement. High degrees of wire drawing (logarithmic strain above 3) leads to pearlitic wires with yield strengths of several gigapascals. It makes pearlite one of the strongest structural bulk materials on earth.
Some hypereutectoid pearlitic steel wires, when cold wire drawn to true (logarithmic) strains above 5, can even show a maximal tensile strength above . Although pearlite is used in many engineering applications, the origin of its extreme strength is not well understood. It has been recently shown that cold wire drawing not only strengthens pearlite by refining the lamellae structure, but also simultaneously causes partial chemical decomposition of cementite, associated with an increased carbon content of the ferrite phase, deformation induced lattice defects in ferrite lamellae, and even a structural transition from crystalline to amorphous cementite. The deformation-induced decomposition and microstructural change of cementite is closely related to several other phenomena such as a strong redistribution of carbon and other alloy elements like silicon and manganese in both the cementite and the ferrite phase; a variation of the deformation accommodation at the phase interfaces due to a change in the carbon concentration gradient at the interfaces; and mechanical alloying.
Pearlite was first identified by Henry Clifton Sorby and initially named sorbite, however the similarity of microstructure to nacre and especially the optical effect caused by the scale of the structure made the alternative name more popular.
Bainite is a similar structure with lamellae much smaller than the wavelength of visible light and thus lacks this pearlescent appearance. It is prepared by more rapid cooling. Unlike pearlite, whose formation involves the diffusion of all atoms, bainite grows by a displacive transformation mechanism.
The transformation of pearlite to austenite takes place at lower critical temperature of . At this temperature pearlite changes to austenite because of nucleation process. | 1 | Applied and Interdisciplinary Chemistry |
The Philadelphia College of Pharmacy (PCP), modeled—at least in concept—after the Collége de pharmacie in Paris, was aided by European talent in its early, formative years. Elias Durand, who had served as "pharmacien of the Grand Army of Napoleon I," set up shop in Philadelphia in 1825, and "...in connection with the Philadelphia College of Pharmacy, immediately exerted a strong foreign influence on American pharmacy." According to William Procter, Jr., Durand "directly and indirectly had much to do with the introduction of scientific pharmacy into Philadelphia." Without teaching at the college, Durand still had a big impact by spreading new findings about medicinal plants, making "medicinal chemicals" never before created in the U.S., by training apprentices, like Augustine Duhamel, who went on to make important contributions and publish in the college journal, and by serving as a role model for foundational figures like Procter.
Hunsberger cites the founding of the Philadelphia College of Pharmacy (PCP) as "the first step forward in the development of a system of pharmaceutical practice in the United States," with the 1821 "meeting of apothecaries...held in Carpenters Hall" (where the Continental Association had been signed) to set up the first formal college of pharmacy and first pharmacists association (the Philadelphia College of Pharmacy) in North America the seminal founding event. On March 13, 1821, "Sixty-eight pharmacists signed the Constitution of the first pharmaceutical association in the United States," with the symbolism of the Carpenters' Hall backdrop undeniable: American pharmacy would have a constitution, following in the footsteps of the Founding Fathers and their constitutional framework. The PCP constitution included a strict code of ethics that would expel anyone from the college who "adulterated" medications or knowingly sold "articles of that character," and provided for a "committee of inspection" to verify the purity, safety and effectiveness of medicines, and a "committee of equity" to arbitrate disputes between member pharmacists.
The college, which was founded as an association to advance the discipline of pharmacy not just a university, quickly became a game-changer: in 1824 they published "carefully determined formulas" for the fabrication of (formerly) "secret-formula" patent medicines previously imported from the UK, an essential step toward self-sufficient pharmaceutical manufacturing in the U.S.
The Philadelphia College of Pharmacy also aided the rise of the American Pharmaceutical Association (APhA), which formed at a founding convention congregated in the Hall of the College, October 6 to 8, 1852. Daniel B. Smith, who had long been the PCPs president—ultimately from 1829 to 1854—was elected the APhAs first president at the founding convention, and William Procter, Jr. the first secretary. | 1 | Applied and Interdisciplinary Chemistry |
To promote maximum gas–liquid surface area and residence time, a number of wet scrubber designs have been used, including spray towers, venturis, plate towers, and mobile packed beds. Because of scale buildup, plugging, or erosion, which affect FGD dependability and absorber efficiency, the trend is to use simple scrubbers such as spray towers instead of more complicated ones. The configuration of the tower may be vertical or horizontal, and flue gas can flow concurrently, countercurrently, or crosscurrently with respect to the liquid. The chief drawback of spray towers is that they require a higher liquid-to-gas ratio requirement for equivalent removal than other absorber designs.
FGD scrubbers produce a scaling wastewater that requires treatment to meet U.S. federal discharge regulations. However, technological advancements in ion-exchange membranes and electrodialysis systems has enabled high-efficiency treatment of FGD wastewater to meet recent EPA discharge limits. The treatment approach is similar for other highly scaling industrial wastewaters. | 1 | Applied and Interdisciplinary Chemistry |
Frequently the primary structure encodes motifs that are of functional importance. Some examples of sequence motifs are: the C/D
and H/ACA boxes
of snoRNAs, Sm binding site found in spliceosomal RNAs such as U1, U2, U4, U5, U6, U12 and U3, the Shine-Dalgarno sequence,
the Kozak consensus sequence
and the RNA polymerase III terminator. | 1 | Applied and Interdisciplinary Chemistry |
Ketosis can improve markers of metabolic syndrome through reduction in serum triglycerides, elevation in high-density lipoprotein (HDL) as well as increased size and volume of low-density lipoprotein (LDL) particles. These changes are consistent with an improved lipid profile despite potential increases in total cholesterol level. | 1 | Applied and Interdisciplinary Chemistry |
Main feed into a sinter plant is base mix, which consists of iron ore fines, coke fines and flux (limestone) fines. In addition to base mix, coke fines, flux fines, sinter fines, iron dust (collected from plant de-dusting system & ESP) and plant waste are mixed in proportion (by weight) in a rotary drum, often called mixing and nodulizing drum. Calcined lime is used as binder of the mixed material along with water (all in particular proportion by weight) to form feed-sinter of about 5 to 7 mm in size. This sinter globules are fed to sintering machine and burnt therein to produce blast furnace feed sinter. | 1 | Applied and Interdisciplinary Chemistry |
The Toda chain equations of motion, in the continuous limit in which the distance between neighbors goes to zero, become the Korteweg–de Vries equation (KdV) equation. Here the index labeling the particle in the chain becomes the new spatial coordinate.
In contrast, the Toda field theory is achieved by introducing a new spatial coordinate which is independent of the chain index label. This is done in a relativistically invariant way, so that time and space are treated on equal grounds. This means that the Toda field theory is not a continuous limit of the Toda chain. | 0 | Theoretical and Fundamental Chemistry |
Following the initial synthesis of phosphaethyne, it was realized that the same compound can be prepared more expeditiously via the flash pyrolysis of methyldichlorophosphine (CHPCl), resulting in the loss of two equivalents of hydrogen chloride. This methodology has been utilized to synthesize numerous substituted phosphaalkynes, including the methyl, vinyl, chloride, and fluoride derivatives. Fluoromethylidynephosphane (F-C≡P) can also be prepared via the potassium hydroxide promoted dehydrofluorination of trifluoromethylphosphine (CFPH). It is speculated that these reactions generally proceed via an intermediate phosphaethylene with general structure RClC=PH. This hypothesis has found experimental support in the observation of FC=PH by P NMR spectroscopy during the synthesis of F-C≡P. | 0 | Theoretical and Fundamental Chemistry |
The prosperity of Cement was not to last. As the limestone deposits were depleted, the industry in Cement began to decline, and the town's economy began to suffer.
Over time, the population of Cement continued to drop, and many of the towns businesses and services were forced to close. The town was finally sold off in 1927 for only a few thousand dollars. The once-thriving town became a shadow of its former self, and today it is a ghost town. The ruins of the town, including remnants of the old cement mill and the foundations of abandoned homes and buildings, stand as a testament to the once-prosperous community that was a center of the cement industry in California. The most prominent and visible concrete ruin on Cements hillside is large and referred to locally as "The Castle." The Castle can be seen all the way from Interstate 80 in Fairfield. | 1 | Applied and Interdisciplinary Chemistry |
The most commonly seen environmental sensitivity in hydrogels is a response to temperature. Many polymers/hydrogels exhibit a temperature dependent phase transition, which can be classified as either an upper critical solution temperature (UCST) or lower critical solution temperature (LCST). UCST polymers increase in their water-solubility at higher temperatures, which lead to UCST hydrogels transitioning from a gel (solid) to a solution (liquid) as the temperature is increased (similar to the melting point behavior of pure materials). This phenomenon also causes UCST hydrogels to expand (increase their swell ratio) as temperature increases while they are below their UCST. However, polymers with LCSTs display an inverse (or negative) temperature-dependence, where their water-solubility decreases at higher temperatures. LCST hydrogels transition from a liquid solution to a solid gel as the temperature is increased, and they also shrink (decrease their swell ratio) as the temperature increases while they are above their LCST.
Applications can dictate for diverse thermal responses. For example, in the biomedical field, LCST hydrogels are being investigated as drug delivery systems due to being injectable (liquid) at room temp and then solidifying into a rigid gel upon exposure to the higher temperatures of the human body. There are many other stimuli that hydrogels can be responsive to, including: pH, glucose, electrical signals, light, pressure, ions, antigens, and more. | 0 | Theoretical and Fundamental Chemistry |
An antibubble is a droplet of liquid surrounded by a thin film of gas, as opposed to a gas bubble, which is a sphere of gas surrounded by a liquid. Antibubbles are formed when liquid drops or flows turbulently into the same or another liquid. They can either skim across the surface of a liquid such as water, in which case they are also called water globules, or they can be completely submerged into the liquid to which they are directed. | 1 | Applied and Interdisciplinary Chemistry |
Tailings deposits tend to be located in rural areas or near marginalized communities, such as indigenous communities. The Global Industry Standard on Tailings Management recommends that "a human rights due diligence process is required to identify and address those that are most at risk from a tailings facility or its potential failure." | 1 | Applied and Interdisciplinary Chemistry |
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive. The term is also used more generally to characterize any type of exponential (or, rarely, non-exponential) decay. For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time.
The original term, half-life period, dating to Ernest Rutherfords discovery of the principle in 1907, was shortened to half-life in the early 1950s. Rutherford applied the principle of a radioactive elements half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206.
Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for the exponential decay equation. The accompanying table shows the reduction of a quantity as a function of the number of half-lives elapsed. | 0 | Theoretical and Fundamental Chemistry |
The Latin word traces to the Proto-Indo-European root *gʷet- "pitch"; see that link for other cognates.
The expression "bitumen" originated in the Sanskrit, where we find the words "jatu", meaning "pitch", and "jatu-krit", meaning "pitch creating", "pitch producing" (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally "gwitu-men" (pertaining to pitch), and by others, "pixtumens" (exuding or bubbling pitch), which was subsequently shortened to "bitumen", thence passing via French into English. From the same root is derived the Anglo Saxon word "cwidu" (Mastix), the German word "Kitt" (cement or mastic) and the old Norse word "kvada".
The word "ašphalt" is claimed to have been derived from the Accadian term "asphaltu" or "sphallo," meaning "to split." It was later adopted by the Homeric Greeks in the form of the adjective ἄσφαλἤς, ἐς signifying "firm," "stable," "secure," and the corresponding verb ἄσφαλίξω, ίσω meaning "to make firm or stable," "to secure".
The word "asphalt" is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek (ásphaltos, ásphalton), a word meaning "asphalt/bitumen/pitch", which perhaps derives from , "not, without", i.e. the alpha privative, and (sphallein), "to cause to fall, baffle, (in passive) err, (in passive) be balked of".
The first use of asphalt by the ancients was as a cement to secure or join various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.
From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt"). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads. | 0 | Theoretical and Fundamental Chemistry |
Change in intracellular Ca levels is used as a signature for diverse responses towards mechanical stimuli, osmotic and salt treatments, and cold and heat shocks. Different root cell types show a different Ca response to osmotic and salt stresses and this implies the cellular specificities of Ca patterns. In response to external stress CaM activates glutamate decarboxylase (GAD) that catalyzes the conversion of -glutamate to GABA. A tight control on the GABA synthesis is important for plant development and, hence, increased GABA levels can essentially affect plant development. Therefore, external stress can affect plant growth and development and CaM are involved in that pathway controlling this effect. | 1 | Applied and Interdisciplinary Chemistry |
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