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mtDNA can be obtained from such material as hair shafts and old bones/teeth. Control mechanism based on interaction point with data. This can be determined by tooled placement in sample. | 1 | Applied and Interdisciplinary Chemistry |
The G1 algorithm produces a numerical derivative that has the shape of a bell curve, this derivative obeys to certain laws, for example the G1 derivative of a cyclic voltammogram is mirrored at the abscissa as long as the electrochemical reaction is diffusion controlled, the planar diffusion approximation can be applied to the electrode geometry and ohmic drop distortion is minimal. The FWHM of the curve is approximately 100 mV for a system that behaves in the described manner. The maximum is found at the value of the formal potential, this is equivalent to the 1.5th order semiderivative hitting the abscissa at this potential. Moreover the semiderivative scales linearly with the scanrate, while the current scales linearly with the square root of the scanrate (Randles–Sevcik equation). Plotting the semiderivatives produced at different scanrates gives a family of curves that are linearly related by the scanrate quotient in an ideal system. | 0 | Theoretical and Fundamental Chemistry |
Xing received Chinese traditional private education in his childhood. In 1933, he graduated from Fu Jen Catholic University with a diploma in Chemistry. Xing did his postgraduate work at University of Illinois at Urbana–Champaign under Roger Adamss guidance and obtained a doctorate degree in 1936. Later he went to University of Munich, conducting research on bufotoxins at Wielands laboratory. | 0 | Theoretical and Fundamental Chemistry |
An action potential is a spike of both positive and negative ionic discharge that travels along the membrane of a cell. The creation and conduction of action potentials represents a fundamental means of communication in the nervous system. Action potentials represent rapid reversals in voltage across the plasma membrane of axons. These rapid reversals are mediated by voltage-gated ion channels found in the plasma membrane.
The action potential travels from one location in the cell to another, but ion flow across the membrane occurs only at the nodes of Ranvier. As a result, the action potential signal jumps along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath. The clustering of voltage-gated sodium and potassium ion channels at the nodes permits this behavior. | 1 | Applied and Interdisciplinary Chemistry |
The International Deep Drawing Research Group ([http://www.iddrg.com IDDRG]) focuses on sheet metal research in industry and academia. It was started 1957 as an organization of national groups. The original focus was on the fabrication of cups hence the name Deep Drawing Research Group. At the initial meeting the purpose was enlarged to do cooperative research on tests, materials, and processes. Such work included for example, methods for determining the strain hardening exponent n, the anisotropy-values (lankford coefficient), as well as other tests for sheet metal formability and, later, forming limit diagrams.
Starting in 1960, a schedule was established for working group meetings every year with open Congresses in every second, even numbered years. The working group meetings were closed sessions made up of delegations from the National Groups that comprised the IDDRG. The reason for these closed sessions was to allow experts to informally review critical issues related to materials, tests, and processes.
As some of the initial technical issues were resolved, the working groups became progressively more informal, and over the years became mini conferences. By 1998, it had become obvious that the former format of the IDDRG has to be changed. This evolution took time, but starting in 2003, the meeting schedule shifted to yearly Conferences with both regular papers and poster presentations that are included in conference proceedings. | 1 | Applied and Interdisciplinary Chemistry |
Huizenga was elected to the National Academy of Sciences in 1976 and the American Academy of Arts and Sciences (Fellow) in 1992. He was a 1966 recipient of the Ernest Orlando Lawrence Award bestowed by the United States Atomic Energy Commission. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, a thiyl radical has the formula RS, sometimes written RS to emphasize that they are free radicals. R is typically an alkyl or aryl substituent. Because S–H bonds are about 20% weaker than C–H bonds, thiyl radicals are relatively easily generated from thiols RSH. Thiyl radicals are intermediates in the thiol-ene reaction, which is the basis of some polymeric coatings and adhesives. They are generated by hydrogen-atom abstraction from thiols using initiators such as AIBN:
:RN=NR → 2 R + N
:R + R′SH → R′S + RH
Thiyl radicals are also invoked as intermediates in some biochemical reactions. | 0 | Theoretical and Fundamental Chemistry |
GC-VUV can be used for bulk compositional analysis because compounds share spectral shape characteristics within a class. Proprietary software applies fitting procedures to quickly determine the relative contribution of each compound category present in a sample. Retention index information is used to limit the amount of VUV library searching and fitting performed for each analyte, enabling the automated data processing routine to be completed quickly. Compound class or specific compound concentrations can be reported as either mass or volume percent.
GC-VUV bulk compound characterization was first applied to the analysis of paraffin, isoparaffin, olefin, naphthene, and aromatic (PIONA) hydrocarbons in gasoline streams. It is suitable for use with finished gasoline, reformate, reformer feed, FCC, light naphtha, and heavy naphtha samples. A typical chromatographic analysis is displayed in Figure 7. The inset shows how the analyte spectral response is fit with VUV library spectra for the selected time slice. A report detailing the carbon number breakdown within each PIONA compound class, as well as the relative mass or volume percent of classes, is shown. A table with mass % and carbon number data from a gasoline sample can be seen in Figure 8. Compound class characterization utilizes a method known as time interval deconvolution (TID), which has recently been applied to the analysis of terpenes. | 0 | Theoretical and Fundamental Chemistry |
The pharmaceutical industry is an industry in medicine that discovers, develops, produces, and markets pharmaceutical drugs for use as medications to be administered to patients (or self-administered), with the aim to cure and prevent diseases, or alleviate symptoms. Pharmaceutical companies may deal in generic or brand medications and medical devices. They are subject to a variety of laws and regulations that govern the patenting, testing, safety, efficacy using drug testing and marketing of drugs. The global pharmaceuticals market produced treatments worth $1,228.45 billion in 2020 and showed a compound annual growth rate (CAGR) of 1.8%. | 1 | Applied and Interdisciplinary Chemistry |
The main reaction of sulfur dioxide promoted by transition metals is its reduction by hydrogen sulfide. Known as the Claus process, this reaction is conducted on a large scale as a way to remove hydrogen sulfide that arises in hydrotreating processes in refineries. | 0 | Theoretical and Fundamental Chemistry |
Prior to founding the Center for Biomedical Mass Spectrometry at Boston University School of Medicine in 1994, Costello was a senior research scientist and the associate director of the National Institutes of Health Research Resource for Mass Spectrometry at Massachusetts Institute of Technology for 20 years. She is a William Fairfield Warren Distinguished Professor and the director of the Center for Biomedical Mass Spectrometry at the Boston University School of Medicine.
Costello served as the president of the American Society for Mass Spectrometry (2002–2004), the Human Proteome Organization (2011–2012), and the International Mass Spectrometry Foundation (2014–2018). She currently serves on the board of directors of the US Human Proteome Organization, and the editorial board of Clinical Proteomics. | 1 | Applied and Interdisciplinary Chemistry |
One of the first documented cases of using electricity to melt a metal occurred in the late 1700s and is credited to Martin van Marum who melted 70 feet of metal wire with 64 Leyden Jars as a capacitor. Van Marum's generator was built in 1784, and is now located in the Teylers Museum in the Netherlands. Years later, Benjamin Franklin vaporized thin gold leaf to burn images onto paper. While neither Marum nor Franklin actually incited the exploding wire phenomenon, they were both important steps towards its discovery.
Edward Nairne was the first to note the existence of the exploding wire method in 1774 with silver and copper wire. Subsequently, Michael Faraday used EWM to deposit thin gold films through the solidification of vaporized metal on adjacent surfaces. Then, vapor deposits of metal gas as a result of EWM were studied by August Toepler during the 1800s. Spectrography investigation of the process, led by J.A. Anderson, became widespread in the 1900s. The spectrography experiments enabled a better understanding and subsequently the first glimpses of practical application. The mid 20th century saw experiments with EWM as a light source and for the production of nanoparticles in aluminum, uranium and plutonium wires. Congruently, Luis Álvarez and Lawrence H. Johnston of the Manhattan Project found use for EWM in the development of nuclear detonators.
Current day research focuses on utilizing EWM to produce nanoparticles as well as better understanding specifics of the mechanism such as the effects of the system environment on the process. | 0 | Theoretical and Fundamental Chemistry |
Drug delivery strategies of inorganic nanoparticles are dependent on material properties. The active targeting of inorganic nanoparticle drug carriers is often achieved by surface functionalization with specific ligands of nanoparticles. For example, the inorganic multifunctional nanovehicle (5-FU/Fe3O4/αZrP@CHI-FA-R6G) is able to accomplish tumor optical imaging and therapy simultaneously. It can be directed to the location of cancer cells with sustained release behavior.
Studies have also been done on gold nanoparticle responses to local near-infrared (NIR) light as a stimuli for drug release. In one study, gold nanoparticles functionalized with double-stranded DNA encapsulated with drug molecules, were irradiated with NIR light. The particles generated heat and denatured the double-stranded DNA, which triggered the release of drugs at the target site.
Studies also suggest that a porous structure is beneficial to attain a sustained or pulsatile release. Porous inorganic materials demonstrate high mechanical and chemical stability within a range of physiological conditions. The well-defined surface properties, such as high pore volume, narrow pore diameter distribution, and high surface area allow the entrapment of drugs, proteins and other biogenic molecules with predictable and reproducible release patterns. | 0 | Theoretical and Fundamental Chemistry |
A graphical presentation of this model clearly shows that there is no single rank order of acid or base strength, a point often overlooked, and emphasizes that the magnitude of acid and base interactions requires two parameters (E & C) to account for the interactions.
The EC equation from the ECW Model
can be rearranged into a form which can be plotted as a straight line.
In a Cramer–Bopp plot for Lewis bases, the parameter R reflects the mode of bonding of a potential Lewis acid partner, from purely electrostatic interactions () to purely covalent interactions (). The parameter reflects the strength of the bonding interaction. The plot shown here allows comparison of three chosen Lewis bases: acetonitrile, ammonia, and dimethyl sulfide. The Lewis acid iodine () will interact most strongly with dimethyl sulfide and least strongly with acetonitrile, whereas triethylgallium () will interact most strongly with ammonia and least strongly with dimethyl sulfide. The plot also shows that ammonia is a stronger Lewis base than acetonitrile irrespective of its Lewis acid partner, whereas the relative strengths of ammonia and dimethyl sulfide as Lewis bases depends on the bonding characteristics of the Lewis acid, swapping order when . The Cramer–Bopp plot was developed as a visual tool for comparing Lewis base strength with the range of possible Lewis acid partners, and a similar plot can be constructed to examine selected Lewis acids against the range of possible Lewis bases. References 5, 8, 12, and 14 contain graphical presentations that define the ranking order of strength of many Lewis acids and bases. | 0 | Theoretical and Fundamental Chemistry |
Dry water was first patented in 1968 and quickly found use in the cosmetic industry. In 2006, new work with dry water from the University of Hull increased interest in its potential use in other fields.
Dry water can be made by blending a mixture of silicon dioxide dust with water. | 0 | Theoretical and Fundamental Chemistry |
A speciation calculation is one in which concentrations of all the species in an equilibrium system are calculated, knowing the analytical concentrations, T, T etc. of the reactants A, B etc. This means solving a set of nonlinear equations of mass-balance
for the free concentrations [A], [B] etc. When the pH (or equivalent e.m.f., E).is measured, the free concentration of hydrogen ions, [H], is obtained from the measured value as or </blockquote>and only the free concentrations of the other reactants are calculated. The concentrations of the complexes are derived from the free concentrations via the chemical model.
Some authors include the free reactant terms in the sums by declaring identity (unit) constants for which the stoichiometric coefficients are 1 for the reactant concerned and zero for all other reactants. For example, with 2 reagents, the mass-balance equations assume the simpler form.
In this manner, all chemical species, including the free reactants, are treated in the same way, having been formed from the combination of reactants that is specified by the stoichiometric coefficients.
In a titration system the analytical concentrations of the reactants at each titration point are obtained from the initial conditions, the burette concentrations and volumes. The analytical (total) concentration of a reactant R at the th titration point is given by
where R is the initial amount of R in the titration vessel, is the initial volume, [R] is the concentration of R in the burette and is the volume added. The burette concentration of a reactant not present in the burette is taken to be zero.
In general, solving these nonlinear equations presents a formidable challenge because of the huge range over which the free concentrations may vary. At the beginning, values for the free concentrations must be estimated. Then, these values are refined, usually by means of Newton–Raphson iterations. The logarithms of the free concentrations may be refined rather than the free concentrations themselves. Refinement of the logarithms of the free concentrations has the added advantage of automatically imposing a non-negativity constraint on the free concentrations. Once the free reactant concentrations have been calculated, the concentrations of the complexes are derived from them and the equilibrium constants.
Note that the free reactant concentrations can be regarded as implicit parameters in the equilibrium constant refinement process. In that context the values of the free concentrations are constrained by forcing the conditions of mass-balance to apply at all stages of the process. | 0 | Theoretical and Fundamental Chemistry |
Atmospheric methane is an important greenhouse gas with a global warming potential 25 times greater than carbon dioxide (averaged over 100 years), and methanogenesis in livestock and the decay of organic material is thus a considerable contributor to global warming. It may not be a net contributor in the sense that it works on organic material which used up atmospheric carbon dioxide when it was created, but its overall effect is to convert the carbon dioxide into methane which is a much more potent greenhouse gas.
Methanogenesis can also be beneficially exploited, to treat organic waste, to produce useful compounds, and the methane can be collected and used as biogas, a fuel. It is the primary pathway whereby most organic matter disposed of via landfill is broken down. | 1 | Applied and Interdisciplinary Chemistry |
Calcium carbide is used:
* in the desulfurization of iron (pig iron, cast iron and steel)
* as a fuel in steelmaking to extend the scrap ratio to liquid iron, depending on economics.
* as a powerful deoxidizer at ladle treatment facilities. | 1 | Applied and Interdisciplinary Chemistry |
A harmful algal bloom (HAB), or excessive algae growth, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Blooms can last from a few days to many months. After the bloom dies, the microbes that decompose the dead algae use up more of the oxygen, generating a "dead zone" which can cause fish die-offs. When these zones cover a large area for an extended period of time, neither fish nor plants are able to survive. Harmful algal blooms in marine environments are often called "red tides".
It is sometimes unclear what causes specific HABs as their occurrence in some locations appears to be entirely natural, while in others they appear to be a result of human activities. In certain locations there are links to particular drivers like nutrients, but HABs have also been occurring since before humans started to affect the environment. HABs are induced by eutrophication, which is an overabundance of nutrients in the water. The two most common nutrients are fixed nitrogen (nitrates, ammonia, and urea) and phosphate. The excess nutrients are emitted by agriculture, industrial pollution, excessive fertilizer use in urban/suburban areas, and associated urban runoff. Higher water temperature and low circulation also contribute.
HABs can cause significant harm to animals, the environment and economies. They have been increasing in size and frequency worldwide, a fact that many experts attribute to global climate change. The U.S. National Oceanic and Atmospheric Administration (NOAA) predicts more harmful blooms in the Pacific Ocean. Potential remedies include chemical treatment, additional reservoirs, sensors and monitoring devices, reducing nutrient runoff, research and management as well as monitoring and reporting.
Terrestrial runoff, containing fertilizer, sewage and livestock wastes, transports abundant nutrients to the seawater and stimulates bloom events. Natural causes, such as river floods or upwelling of nutrients from the sea floor, often following massive storms, provide nutrients and trigger bloom events as well. Increasing coastal developments and aquaculture also contribute to the occurrence of coastal HABs. Effects of HABs can worsen locally due to wind driven Langmuir circulation and their biological effects. | 0 | Theoretical and Fundamental Chemistry |
The use of electronic detectors such as X-ray CCD cameras, replacing traditional X-ray film, facilitates topography in many ways. CCDs achieve online readout in (almost) real-time, dispensing experimentalists of the need to develop films in a dark room. Drawbacks with respect to films are the limited dynamic range and, above all, the moderate spatial resolution of commercial CCD cameras, making the development of dedicated CCD cameras necessary for high-resolution imaging. A further, decisive advantage of digital topography is the possibility to record series of images without changing detector position, thanks to online readout. This makes it possible, without complicated image registration procedures, to observe time-dependent phenomena, to perform kinetic studies, to investigate processes of device degradation and radiation damage, and to realize sequential topography (see below). | 0 | Theoretical and Fundamental Chemistry |
Photodegradation of plastics and other materials can be inhibited with polymer stabilizers, which are widely used. These additives include antioxidants, which interrupt degradation processes. Typical antioxidants are derivatives of aniline. Another type of additive are UV-absorbers. These agents capture the photon and convert it to heat. Typical UV-absorbers are hydroxy-substituted benzophenones, related to the chemicals used in sunscreen. Restoration of yellowed plastic of old toys is nicknamed retrobright. | 0 | Theoretical and Fundamental Chemistry |
The time evolution equation of Reynolds stress is given by:
This equation is very complicated. If is traced, turbulence kinetic energy is obtained.
The last term is turbulent dissipation rate. All RANS models are based on the above equation. | 1 | Applied and Interdisciplinary Chemistry |
It is a flavoring ingredient and achieved a generally recognized as safe (GRAS) status in 1995 by the Flavor and Extract Manufacturers Association (FEMA). 2-Furoic acid has a distinct odor described as sweet, oily, herbaceous, and earthy.
2-Furoic acid helps sterilize and pasteurize many foods. It forms in situ from 2-furfural. 2-Furoic acid is also formed during coffee roasting, with up to 205 mg/kg. | 0 | Theoretical and Fundamental Chemistry |
As a result of the tremendous threats to life safety and economic disruptions caused by the 2004 and 2005 hurricane seasons, governmental organizations, such as the United States National Science Foundation, have recognized the need to better understand hurricane threats and further establish this discipline. In September 2006, the National Science Board released recommendations to the United States Congress calling for major new investments in hurricane science and engineering.
Accredited university engineering programs, such as the Louisiana State University civil engineering department and University of Notre Dame Department of Civil Engineering and Geological Sciences, are establishing programs to better understand these catastrophic storms and their interaction with the environment. The LSU Hurricane Center has begun to offer hurricane engineering courses with the focus of educating students on the unique threats caused by hurricanes.
The past two decades have witnessed exponential growth in damage due to hurricanes and the situation continues to deteriorate. The most vulnerable areas, coastal counties along the Gulf and Atlantic seaboards, are experiencing greater population growth and development than anyplace else in the country. If the trend of rapidly increasing losses caused by hurricanes is to be reversed, a whole new philosophy of understanding, planning, and preparedness is required. The Hurricane Engineering curriculum is the result of a multidisciplinary project aimed at giving engineering students a comprehensive understanding of the hazards associated with hurricanes:
*Extreme winds
*Windborne debris
*Storm surges
*River flooding
*Rain-induced landslides | 1 | Applied and Interdisciplinary Chemistry |
In the last decades, the thermal efficiency of Rankine cycles increased drastically, especially for large scale applications fueled by coal: for these power plants, the application of ultrasupercritical layouts was the main factor to achieve the goal, since the higher pressure ratio ensures higher cycle efficiencies.
The increment in thermal efficiency of power plants fueled by dirty fuels became crucial also in the reduction of the specific emissions of the plants, both in therms of greenhouse gas and for pollutant such as sulfur dioxide or NOx.
In large scale applications, ultrasupercritical Rankine cycles employ up to 10 feedwater heaters, five on the high pressure side and five on the low pressure side, including the deaerator, helping in the increment of the temperature at the inlet of the boiler up to 300°C, allowing a significant regenerative air preheating, thus reducing the fuel consumption. Studies on the best performant configurations of supercritical rankine cycles (300 bar of maximum pressure, 600°C of maximum temperature and two reheats) show that such layouts can achieve a cycle efficiency higher than 50%, about 6% higher than subcritical configurations. | 0 | Theoretical and Fundamental Chemistry |
Glomalin is hypothesized to improve soil aggregate stability and decrease soil erosion. However, since glomalin can not be adequate quantified in soil, studies usually analyze the GRSPs extract, which is a complex mixture including proteins and other substances.
GRSPs, the mixture of proteins and humic substances, are a significant component of soil organic matter and act to bind mineral particles together, improving soil quality. GRSPs have been investigated for its carbon and nitrogen storing properties, including as a potential method of carbon sequestration. Sampled GRSP takes 7–42 years to biodegrade and is thought to contribute up to 30 percent of the soil carbon where mycorrhizal fungi is present. The highest levels of GRSP were found in volcanic soils of Hawaii and Japan. Concentrations of glomalin in soil were correlated with the primary productivity of an ecosystem. A strong correlation has been found between GRSP and soil aggregate water stability in a wide variety of soils where organic material is the main binding agent, although the mechanism is not known. | 0 | Theoretical and Fundamental Chemistry |
The coefficient lies always in range values equal to 0 or 1), value 1 indicates ideal equal-spreading of the spots, for example (0.25,0.5,0.75) for three solutes, or (0.2,0.4,0.6,0.8) for four solutes.
This coefficient was proposed as an alternative to earlier approaches, such as delta-Rf, delta-Rf product or MRF (Multispot Response Function). Besides its stable range, the advantage is a stable distribution as a random variable, regardless of compounds investigated.
In contrast to the similar concept called Retention uniformity, R is sensitive to R values close to 0 or 1, or close to themselves. If two values are not separated, it is equal to 0. For example, the R values (0,0.2,0.2,0.3) (two compounds not separated at 0.2 and one at the start ) result in R equal to 0, but R equal to 0.3609. When some distance from 0 and spots occurs, the value is larger, for example R values (0.1,0.2,0.25,0.3) give R = 0.4835, R = 0.4066. | 0 | Theoretical and Fundamental Chemistry |
Nephelometers are also used for measurement of visibility with simple one-wavelength nephelometers used throughout the world by many EPAs. Nephelometers, through the measurement of light scattering, can determine visibility in distance through the application of a conversion factor called Koschmieder's formula. | 0 | Theoretical and Fundamental Chemistry |
With a specific gravity greater than 1 (denser than water), trichloroethylene can be present as a dense non-aqueous phase liquid (DNAPL) if sufficient quantities are spilt in the environment.
The first known report of TCE in groundwater was given in 1949 by two English public chemists who described two separate instances of well contamination by industrial releases of TCE. Based on available federal and state surveys, between 9% and 34% of the drinking water supply sources tested in the US may have some TCE contamination, though EPA has reported that most water supplies comply with the maximum contaminant level (MCL) of 5 ppb.
Generally, atmospheric levels of TCE are highest in areas of concentrated industry and population. Atmospheric levels tend to be lowest in rural and remote regions. Average TCE concentrations measured in air across the United States are generally between 0.01 ppb and 0.3 ppb, although mean levels as high as 3.4 ppb have been reported. TCE levels in the low parts per billion range have been measured in food; however, levels as high as 140 ppb were measured in a few samples of food. TCE levels above background have been found in homes undergoing renovation. | 1 | Applied and Interdisciplinary Chemistry |
Over the past two decades, iron oxide nanoparticles for biomedical use had increased dramatically, largely due to its ability of non-invasive imaging, targeting and triggering drug release, or cancer therapy. Stem or immune cell could be marked with iron oxide nanoparticles to be detected by Magnetic resonance imaging (MDR). However, the concentration of iron oxide nanoparticles needs to be high enough to enable the significant detection by MDR. Due to the limited understanding of physicochemical nature of iro oxide nanoparticles in biological systems, more research is needed to ensure nanoparticles can be controlled under certain conditions for medical usage without posing harm to human. | 0 | Theoretical and Fundamental Chemistry |
Residues from the oil and gas industry often contain radium and its daughters. The sulfate scale from an oil well can be very radium rich. The water inside an oil field is often very rich in strontium, barium and radium while seawater is very rich in sulfate so if water from an oil well is discharged into the sea or mixed with seawater the radium is likely to be brought out of solution by the barium/strontium sulfate which acts as a carrier precipitate. | 0 | Theoretical and Fundamental Chemistry |
The Wimley–White whole residue hydrophobicity scales are significant for two reasons. First, they include the contributions of the peptide bonds as well as the sidechains, providing absolute values. Second, they are based on direct, experimentally determined values for transfer free energies of polypeptides.
Two whole-residue hydrophobicity scales have been measured:
* One for the transfer of unfolded chains from water to the bilayer interface (referred to as the Wimley–White interfacial hydrophobicity scale).
* One for the transfer of unfolded chains into octanol, which is relevant to the hydrocarbon core of a bilayer.
The Stephen H. White website provides an example of whole residue hydrophobicity scales showing the free energy of transfer ΔG(kcal/mol) from water to POPC interface and to n-octanol. These two scales are then used together to make Whole residue hydropathy plots. The hydropathy plot constructed using ΔG − ΔG shows favorable peaks on the absolute scale that correspond to the known TM helices. Thus, the whole residue hydropathy plots illustrate why transmembrane segments prefer a transmembrane location rather than a surface one. | 0 | Theoretical and Fundamental Chemistry |
Examples include the absorption of water by seeds and dry wood. If there is no pressure due to imbibition, seedlings would not be able to emerge from soil. | 0 | Theoretical and Fundamental Chemistry |
Plants also have receptors that can cause a response to chitin, namely chitin elicitor receptor kinase 1 and chitin elicitor-binding protein. The first chitin receptor was cloned in 2006. When the receptors are activated by chitin, genes related to plant defense are expressed, and jasmonate hormones are activated, which in turn activate systemic defenses. Commensal fungi have ways to interact with the host immune response that, , were not well understood.
Some pathogens produce chitin-binding proteins that mask the chitin they shed from these receptors. Zymoseptoria tritici is an example of a fungal pathogen that has such blocking proteins; it is a major pest in wheat crops. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, a variety of synthetic procures are particularly useful in closing carbocyclic and other rings; these are termed ring-closing reactions. Examples include:
* alkyne trimerisation;
* the Bergman cyclization of an enediyne;
* the Diels–Alder, between a conjugated diene and a substituted alkene, and other cycloaddition reactions;
* the Nazarov cyclization reaction, originally being the cyclization of a divinyl ketone;
* various radical cyclizations;
* ring-closing metathesis reactions, which also can be used to accomplish a specific type of polymerization;
* the Ruzicka large ring synthesis, in which two carboxyl groups combine to form a carbonyl group with loss of and ;
* the Wenker synthesis converting a beta amino alcohol to an aziridine
* other reactions, such as an amino group reacting with a hydroxy group, as in the biosynthesis of solanine | 0 | Theoretical and Fundamental Chemistry |
Lanthipeptides are characterized by the presence lanthionine (Lan) and 3-methyllanthionine (MeLan) residues. Lan residues are formed from a thioether bridge between Cys and Ser, while MeLan residues are formed from the linkage of Cys to a Thr residue. The biosynthetic enzymes responsible for Lan and MeLan installation first dehydrate Ser and Thr to dehydroalanine (Dha) and dehydrobutyrine (Dhb), respectively. Subsequent thioether crosslinking occurs through a Michael-type addition by Cys onto Dha or Dhb.
Four classes of lanthipeptide biosynthetic enzymes have been designated. Class I lanthipeptides have dedicated lanthipeptide dehydratases, called LanB enzymes, though more specific designations are used for particular lanthipeptides (e.g. NisB is the nisin dehydratase). A separate cyclase, LanC, is responsible for the second step in Lan and MeLan biosynthesis. However, class II, III, and IV lanthipeptides have bifunctional lanthionine synthetases in their gene clusters, meaning a single enzyme carries out both dehydration and cyclization steps. Class II synthetases, designated LanM synthetases, have N-terminal dehydration domains with no sequence homology to other lanthipeptide biosynthetic enzymes; the cyclase domain has homology to LanC. Class III (LanKC) and IV (LanL) enzymes have similar N-terminal lyase and central kinase domains, but diverge in C-terminal cyclization domains: the LanL cyclase domain is homologous to LanC, but the class III enzymes lack Zn-ligand binding domains. | 1 | Applied and Interdisciplinary Chemistry |
Dialkyl peroxides, e.g., dicumyl peroxide, are synthesized by addition of hydrogen peroxide to alkenes or by O-alkylation of hydroperoxides.
Diacyl peroxides are typically prepared by treating hydrogen peroxide with acid chlorides or acid anhydrides in the presence of base:
The reaction competes with hydrolysis of the acylating agent but the hydroperoxide anion is a superior nucleophile relative to hydroxide. Unsymmetrical diacyl peroxides can be produced by treating acyl chlorides with the peroxy acid.
Peresters, an example being tert-Butyl peroxybenzoate, are produced by treating acid anhydrides or acid chlorides with hydroperoxides. | 0 | Theoretical and Fundamental Chemistry |
In general, most ingestions in children involve exploratory ingestions of small amounts of caustic substances, with the rare exception being cases of child abuse where larger amounts are often ingested. Caustic ingestions in adults usually involve larger amounts of ingested material during attempts of self harm. Due to the greater amount of material usually ingested; injuries are often more severe in the intentional ingestions of adolescents and adults as compared to those of children. Commonly ingested substances include ammonium hydroxide (found in general cleaner and grease remover), sodium hydroxide or potassium hydroxide (found in drain opener or oven cleaner), sodium hypochlorite (bleach), oxalic acid (metal polish) and hydrochloric acid (toilet bowl cleaner). Storage of caustic substances in water or drink containers is a risk factor for accidental ingestion of these materials, particularly in children. Boys of preschool age are at the greatest risk of accidental caustic ingestion. | 1 | Applied and Interdisciplinary Chemistry |
Water can be split into its constituent elements, hydrogen, and oxygen, by passing an electric current through it. This process is called electrolysis. The cathode half reaction is:
The anode half reaction is:
The gases produced bubble to the surface, where they can be collected or ignited with a flame above the water if this was the intention. The required potential for the electrolysis of pure water is 1.23 V at 25 °C. The operating potential is actually 1.48 V or higher in practical electrolysis. | 1 | Applied and Interdisciplinary Chemistry |
Even prior to the nucleic acid methods employed today, it was known that in the presence of chaotropic agents, such as sodium iodide or sodium perchlorate, DNA binds to silica, glass particles or to unicellular algae called diatoms which shield their cell walls with silica. This property was used to purify nucleic acid using glass powder or silica beads under alkaline conditions. This was later improved using guanidinium thiocyanate or guanidinium hydrochloride as the chaotropic agent. For ease of handling, the use of glass beads was later changed to silica columns. And to enable use of automated extraction instruments, there was development of silica-coated paramagnetic beads, more commonly referred to as "magnetic bead" extraction. | 1 | Applied and Interdisciplinary Chemistry |
PMCA was originally developed to, in vitro, mimic prion replication with a similar efficiency to the in vivo process, but with accelerated kinetics. PMCA is conceptually analogous to the polymerase chain reaction - in both systems a template grows at the expense of a substrate in a cyclic reaction, combining growing and multiplication of the template units. | 1 | Applied and Interdisciplinary Chemistry |
A battery-powered radio may be helpful to get reports of fallout patterns and clearance. However, radio and other electronic equipment may be disabled by electromagnetic pulse. For example, even at the height of the Cold War, EMP protection had been completed for only 125 of the approximately 2,771 radio stations in the United States Emergency Broadcast System. Also, only 110 of 3,000 existing Emergency Operating Centers had been protected against EMP effects. The Emergency Broadcast System has since been supplanted in the United States by the Emergency Alert System.
The reference Nuclear War Survival Skills includes the following supplies in a list of "Minimum Pre-Crisis Preparations": one or more shovels, a pick, a bow-saw with an extra blade, a hammer, and polyethylene film (also any necessary nails, wire, etc.); a homemade shelter-ventilating pump (a KAP); large containers for water; a plastic bottle of sodium hypochlorite bleach; one or two KFMs (Kearny fallout meters) and the knowledge to operate them; at least a 2-week supply of compact, nonperishable food; an efficient portable stove; wooden matches in a waterproof container; essential containers and utensils for storing, transporting, and cooking food; a hose-vented can, with heavy plastic bags for liners, for use as a toilet; tampons; insect screen and fly bait; any special medications needed by family members; pure potassium iodide, a bottle, and a medicine dropper; a first-aid kit and a tube of antibiotic ointment; long-burning candles (with small wicks) sufficient for at least 14 nights; an oil lamp; a flashlight and extra batteries; and a transistor radio with extra batteries and a metal box to protect it from electromagnetic pulse.
Inhabitants should have water on hand, per person per day. Water stored in bulk containers requires less space than water stored in smaller bottles. | 0 | Theoretical and Fundamental Chemistry |
Diglycerides are a minor component of many seed oils and are normally present at ~1–6%; or in the case of cottonseed oil as much as 10%. Industrial production is primarily achieved by a glycerolysis reaction between triglycerides and glycerol. The raw materials for this may be either vegetable oils or animal fats. | 1 | Applied and Interdisciplinary Chemistry |
Viruses in the sea surface microlayer, the so-called virioneuston, have recently become of interest to researchers as enigmatic biological entities in the boundary surface layers with potentially important ecological impacts. Given this vast air–water interface sits at the intersection of major air–water exchange processes spanning more than 70% of the global surface area, it is likely to have profound implications for marine biogeochemical cycles, on the microbial loop and gas exchange, as well as the marine food web structure, the global dispersal of airborne viruses originating from the sea surface microlayer, and human health.
Viruses are the most abundant biological entities in the water column of the world's oceans. In the free water column, the virioplankton typically outnumbers the bacterioplankton by one order of magnitude reaching typical bulk water concentrations of 10 viruses mL. Moreover, they are known as integral parts of global biogeochemical cycles to shape and drive microbial diversity and to structure trophic networks. Like other neuston members, the virioneuston likely originates from the bulk seawater. For instance, in 1977 Baylor et al. postulated adsorption of viruses onto air bubbles as they rise to the surface, or viruses can stick to organic particles also being transported to the SML via bubble scavenging.
Within the SML, viruses interacting with the bacterioneuston will probably induce the viral shunt, a phenomenon that is well known for marine pelagic systems. The term viral shunt describes the release of organic carbon and other nutritious compounds from the virus-mediated lysis of host cells, and its addition to the local dissolved organic matter (DOM) pool. The enriched and densely packed bacterioneuston forms an excellent target for viruses compared to the bacterioplankton populating the subsurface. This is because high host-cell numbers will increase the probability of host–virus encounters. The viral shunt might effectively contribute to the SML's already high DOM content enhancing bacterial production as previously suggested for pelagic ecosystems and in turn replenishing host cells for viral infections. By affecting the DOM pool, viruses in the SML might directly interfere with the microbial loop being initiated when DOM is microbially recycled, converted into biomass, and passed along the food web. In addition, the release of DOM from lysed host cells by viruses contributes to organic particle generation. However, the role of the virioneuston for the microbial loop has never been investigated. | 0 | Theoretical and Fundamental Chemistry |
To describe dynamics of the systems that obey the generalized mass action law, one has to represent the activities as functions of the concentrations c and temperature. For this purpose, use the representation of the activity through the chemical potential:
where μ is the chemical potential of the species under the conditions of interest, is the chemical potential of that species in the chosen standard state, R is the gas constant and T is the thermodynamic temperature.
The chemical potential can be represented as a function of c and T, where c is the vector of concentrations with components c. For the ideal systems, and : the activity is the concentration and the generalized mass action law is the usual law of mass action.
Consider a system in isothermal (T=const) isochoric (the volume V=const) condition. For these conditions, the Helmholtz free energy measures the “useful” work obtainable from a system. It is a functions of the temperature T, the volume V and the amounts of chemical components N (usually measured in moles), N is the vector with components N. For the ideal systems,
The chemical potential is a partial derivative: .
The chemical kinetic equations are
If the principle of detailed balance is valid then for any value of T there exists a positive point of detailed balance c:
Elementary algebra gives
where
For the dissipation we obtain from these formulas:
The inequality holds because ln is a monotone function and, hence, the expressions and have always the same sign.
Similar inequalities are valid for other classical conditions for the closed systems and the corresponding characteristic functions: for isothermal isobaric conditions the Gibbs free energy decreases, for the isochoric systems with the constant internal energy (isolated systems) the entropy increases as well as for isobaric systems with the constant enthalpy. | 0 | Theoretical and Fundamental Chemistry |
Sidney Gilchrist Thomas, a Londoner with a Welsh father, was an industrial chemist who decided to tackle the problem of phosphorus in iron, which resulted in the production of low grade steel. Believing that he had discovered a solution, he contacted his cousin, Percy Gilchrist, who was a chemist at the Blaenavon Ironworks. The manager at the time, Edward Martin, offered Sidney equipment for large-scale testing and helped him draw up a patent that was taken out in May 1878. Sidney Gilchrist Thomass invention consisted of using dolomite or sometimes limestone linings for the Bessemer converter rather than clay, and it became known as the basic Bessemer rather than the acid' Bessemer process. An additional advantage was that the processes formed more slag in the converter, and this could be recovered and used very profitably as a phosphate fertilizer. | 1 | Applied and Interdisciplinary Chemistry |
Optical flowmeters use light to determine flow rate. Small particles which accompany natural and industrial gases pass through two laser beams focused a short distance apart in the flow path in a pipe by illuminating optics. Laser light is scattered when a particle crosses the first beam. The detecting optics collects scattered light on a photodetector, which then generates a pulse signal. As the same particle crosses the second beam, the detecting optics collect scattered light on a second photodetector, which converts the incoming light into a second electrical pulse. By measuring the time interval between these pulses, the gas velocity is calculated as where is the distance between the laser beams and is the time interval.
Laser-based optical flowmeters measure the actual speed of particles, a property which is not dependent on thermal conductivity of gases, variations in gas flow or composition of gases. The operating principle enables optical laser technology to deliver highly accurate flow data, even in challenging environments which may include high temperature, low flow rates, high pressure, high humidity, pipe vibration and acoustic noise.
Optical flowmeters are very stable with no moving parts and deliver a highly repeatable measurement over the life of the product. Because distance between the two laser sheets does not change, optical flowmeters do not require periodic calibration after their initial commissioning. Optical flowmeters require only one installation point, instead of the two installation points typically required by other types of meters. A single installation point is simpler, requires less maintenance and is less prone to errors.
Commercially available optical flowmeters are capable of measuring flow from 0.1 m/s to faster than 100 m/s (1000:1 turn down ratio) and have been demonstrated to be effective for the measurement of flare gases from oil wells and refineries, a contributor to atmospheric pollution. | 1 | Applied and Interdisciplinary Chemistry |
In a gravitational field, liquids exert pressure on the sides of a container as well as on anything within the liquid itself. This pressure is transmitted in all directions and increases with depth. If a liquid is at rest in a uniform gravitational field, the pressure at depth is given by
where:
: is the pressure at the surface
: is the density of the liquid, assumed uniform with depth
: is the gravitational acceleration
For a body of water open to the air, would be the atmospheric pressure.
Static liquids in uniform gravitational fields also exhibit the phenomenon of buoyancy, where objects immersed in the liquid experience a net force due to the pressure variation with depth. The magnitude of the force is equal to the weight of the liquid displaced by the object, and the direction of the force depends on the average density of the immersed object. If the density is smaller than that of the liquid, the buoyant force points upward and the object floats, whereas if the density is larger, the buoyant force points downward and the object sinks. This is known as Archimedes' principle. | 0 | Theoretical and Fundamental Chemistry |
*CUT&RUN sequencing, antibody-targeted controlled cleavage by micrococcal nuclease for transcriptomic profiling.
*Hydrolysis of nucleic acids in crude cell-free extracts.
*Sequencing of RNA.
*Preparation of rabbit reticulocyte lysates.
*Studies of chromatin structure.
*Removal of nucleic acids from laboratory protein preparations allowing for protein folding and structure-function studies.
*Research on the mechanisms of protein folding. | 1 | Applied and Interdisciplinary Chemistry |
The majority of systems utilize two two-cylinder piston pumps, one for each buffer, combining the output of both in a mixing chamber. Some simpler systems use a single peristaltic pump which draws both buffers from separate reservoirs through a proportioning valve and mixing chamber. In either case the system allows the fraction of each buffer entering the column to be continuously varied. The flow rate can go from a few milliliters per minute in bench-top systems to liters per minute for industrial scale purifications. The wide flow range makes it suitable both for analytical and preparative chromatography. | 0 | Theoretical and Fundamental Chemistry |
A classic example of this process is the quinine sulfate fluorescence, which can be quenched by the use of various halide salts. The excited molecule can de-excite by increasing the thermal energy of the surrounding solvated ions.
Several natural molecules perform a fast internal conversion. This ability to transform the excitation energy of photon into heat can be a crucial property for photoprotection by molecules such as melanin. Fast internal conversion reduces the excited state lifetime, and thereby prevents bimolecular reactions. Bimolecular electron transfer always produces a reactive chemical species, free radicals. Nucleic acids (precisely the single, free nucleotides, not those bound in a DNA/RNA strand) have an extremely short lifetime due to a fast internal conversion.
Both melanin and DNA have some of the fastest internal conversion rates.
In applications that make use of bimolecular electron transfer the internal conversion is undesirable. For example, it is advantageous to have a long-lived excited state in Grätzel cells (Dye-sensitized solar cells). | 0 | Theoretical and Fundamental Chemistry |
The Escherichia coli-derived Tet-R repressor can be used in line with a conventional reporter gene and can be controlled by tetracycline or doxicycline (Tet-R inhibitors). Thus the expression of Tet-R is controlled by the standard two-hybrid system but the Tet-R in turn controls (represses) the expression of a previously mentioned reporter such as HIS3, through its Tet-R promoter. Tetracycline or its derivatives can then be used to regulate the sensitivity of a system utilising Tet-R.
Sensitivity may also be controlled by varying the dependency of the cells on their reporter genes. For example, this may be affected by altering the concentration of histidine in the growth medium for his3-dependent cells and altering the concentration of streptomycin for aadA dependent cells. Selection-gene-dependency may also be controlled by applying an inhibitor of the selection gene at a suitable concentration. 3-Amino-1,2,4-triazole (3-AT) for example, is a competitive inhibitor of the HIS3-gene product and may be used to titrate the minimum level of HIS3 expression required for growth on histidine-deficient media.
Sensitivity may also be modulated by varying the number of operator sequences in the reporter DNA. | 1 | Applied and Interdisciplinary Chemistry |
A new chemical entity (NCE) is, according to the U.S. Food and Drug Administration, a novel, small, chemical molecule drug that is undergoing clinical trials or has received a first approval (not a new use) by the FDA in any other application submitted under section 505(b) of the Federal Food, Drug, and Cosmetic Act.
A new molecular entity (NME) is a broader term that encompasses both an NCE or an NBE (New Biological Entity). | 1 | Applied and Interdisciplinary Chemistry |
Fusion fuels are fuels to use in hypothetical Fusion power reactors. They include deuterium (H) and tritium (H) as well as helium-3 (He). Many other elements can be fused together, but the larger electrical charge of their nuclei means that much higher temperatures are required. Only the fusion of the lightest elements is seriously considered as a future energy source. Fusion of the lightest atom, H hydrogen, as is done in the Sun and other stars, has also not been considered practical on Earth. Although the energy density of fusion fuel is even higher than fission fuel, and fusion reactions sustained for a few minutes have been achieved, utilizing fusion fuel as a net energy source remains only a theoretical possibility. | 0 | Theoretical and Fundamental Chemistry |
In the Gallagher–Hollander degradation (1946) pyruvic acid is removed from a linear aliphatic carboxylic acid yielding a new acid with two carbon atoms fewer. The original publication concerns the conversion of bile acid in a series of reactions: acid chloride (2) formation with thionyl chloride, diazoketone formation (3) with diazomethane, chloromethyl ketone formation (4) with hydrochloric acid, organic reduction of chlorine to methylketone (5), ketone halogenation to 6, elimination reaction with pyridine to enone 7 and finally oxidation with chromium trioxide to bisnorcholanic acid 8. | 0 | Theoretical and Fundamental Chemistry |
Surface conductivity is an additional conductivity of an electrolyte in the vicinity of the charged interfaces. Surface and volume conductivity of liquids correspond to the electrically driven motion of ions in an electric field. A layer of counter ions of the opposite polarity to the surface charge exists close to the interface. It is formed due to attraction of counter-ions by the surface charges. This layer of higher ionic concentration is a part of the interfacial double layer. The concentration of the ions in this layer is higher as compared to the ionic strength of the liquid bulk. This leads to the higher electric conductivity of this layer.
Smoluchowski was the first to recognize the importance of surface conductivity at the beginning of the 20th century.
There is a detailed description of surface conductivity by Lyklema in "Fundamentals of Interface and Colloid Science"
The Double Layer (DL) has two regions, according to the well established Gouy-Chapman-Stern model. The upper level, which is in contact with the bulk liquid is the diffuse layer. The inner layer that is in contact with interface is the Stern layer.
It is possible that the lateral motion of ions in both parts of the DL contributes to the surface conductivity.
The contribution of the Stern layer is less well described. It is often called "additional surface conductivity".
The theory of the surface conductivity of the diffuse part of the DL was developed by Bikerman. He derived a simple equation that links surface conductivity κ with the behaviour of ions at the interface. For symmetrical electrolyte and assuming identical ions diffusion coefficients D=D=D it is given in the reference:
where
:F is the Faraday constant
:T is the absolute temperature
:R is the gas constant
:C is the ionic concentration in the bulk fluid
:z is the ion valency
:ζ is the electrokinetic potential
The parameter m characterizes the contribution of electro-osmosis to the motion of ions within the DL:
The Dukhin number is a dimensionless parameter that characterizes the contribution of the surface conductivity to a variety of electrokinetic phenomena, such as, electrophoresis and electroacoustic phenomena. This parameter and, consequently, surface conductivity can be calculated from the electrophoretic mobility using appropriate theory. Electrophoretic instrument by Malvern and electroacoustic instruments by Dispersion Technology contain software for conducting such calculations. | 0 | Theoretical and Fundamental Chemistry |
The ability to form carbon-carbon, carbon-nitrogen, and carbon-oxygen bonds enantioselectively under mild conditions makes the Trost asymmetric allylic alkylation extremely appealing for the synthesis of complex molecules.
An example of this reaction is the synthesis of an intermediate in the combined total synthesis of galantamine and morphine with 1 mol% [pi-allylpalladium chloride dimer], 3 mol% (S,S) Trost ligand, and triethylamine in dichloromethane at room temperature. These conditions result in the formation of the (−)-enantiomer of the aryl ether in 72% chemical yield and 88% enantiomeric excess.
Another Tsuji–Trost reaction was used during the initial stages of the synthesis of (−)-neothiobinupharidine. This recent work demonstrates the ability of this reaction to give highly diastereoselective (10:1) and enantioselective (97.5:2.5) products from achiral starting material with only a small amount of catalyst (1%). | 0 | Theoretical and Fundamental Chemistry |
Chan is a current member of the Professional Teachers' Union (HK), Hong Kong Marine Biological Association, Society of Toxicology (SOT) in the US, American Fisheries Society, American Physiological Society, etc.
He is now chairman (elected) of the Teachers' Association of Chinese University (2011–12). He also serves as warden of Student Hostel 2 of Shaw College, member of the board of trustees of Shaw College, and member of the Assembly of Fellows, Shaw College, Chinese University. | 1 | Applied and Interdisciplinary Chemistry |
Deoxycytidine is a deoxyribonucleoside, a component of deoxyribonucleic acid. It is similar to the ribonucleoside cytidine, but with one hydroxyl group removed from the C2' position.
Deoxycytidine can be phosphorylated at C5' of the deoxyribose by deoxycytidine kinase, converting it to deoxycytidine monophosphate (dCMP), a DNA precursor. dCMP can be converted to dUMP and dTMP.
It can also be used as a precursor for 5-aza-2′-deoxycytidine, a treatment for MDS patients. This compound slows the cell cycle by interfering with the methylation of the P15/INK4B gene, increasing the expression of P15/INK4B protein which subdues the transformation of MDS to leukemia.
Deoxycytidine can also serve as a biomarker for tumor diagnosis. Deoxycytidine can be used as a biomarker for breast cancer patients and healthy individuals. 5-(Hydroxymethyl)-2′-deoxycytidine (5-hmdC), 5-(formyl)-2′-deoxycytidine (5-fodC), and 5-(carboxyl)-2′-deoxycytidine (5-cadC) are intermediates in the DNA demethylation pathway and can act as biomarkers. 5-hmdC levels were significantly reduced in urine samples of breast cancer patients, while 5-fodC and 5-cadC levels were elevated. | 1 | Applied and Interdisciplinary Chemistry |
The Saffman–Taylor instability, also known as viscous fingering, is the formation of patterns in a morphologically unstable interface between two fluids in a porous medium, described mathematically by Philip Saffman and G. I. Taylor in a paper of 1958. This situation is most often encountered during drainage processes through media such as soils. It occurs when a less viscous fluid is injected, displacing a more viscous fluid; in the inverse situation, with the more viscous displacing the other, the interface is stable and no instability is seen. Essentially the same effect occurs driven by gravity (without injection) if the interface is horizontal and separates two fluids of different densities, the heavier one being above the other: this is known as the Rayleigh-Taylor instability. In the rectangular configuration the system evolves until a single finger (the Saffman–Taylor finger) forms, whilst in the radial configuration the pattern grows forming fingers by successive tip-splitting.
Most experimental research on viscous fingering has been performed on Hele-Shaw cells, which consist of two closely spaced, parallel sheets of glass containing a viscous fluid. The two most common set-ups are the channel configuration, in which the less viscous fluid is injected at one end of the channel, and the radial configuration, in which the less viscous fluid is injected at the centre of the cell. Instabilities analogous to viscous fingering can also be self-generated in biological systems. | 1 | Applied and Interdisciplinary Chemistry |
The Grignard reaction () is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides (Grignard reagent) are added to the carbonyl groups of either an aldehyde or ketone under anhydrous conditions. This reaction is important for the formation of carbon–carbon bonds.
(R or R could be hydrogen) | 0 | Theoretical and Fundamental Chemistry |
The count of 251 known stable nuclides includes tantalum-180m, since even though its decay and instability is automatically implied by its notation of "metastable", this has still not yet been observed. All "stable" isotopes (stable by observation, not theory) are the ground states of nuclei, with the exception of tantalum-180m, which is a nuclear isomer or excited state. The ground state of this particular nucleus, tantalum-180, is radioactive with a comparatively short half-life of 8 hours; in contrast, the decay of the excited nuclear isomer is extremely strongly forbidden by spin-parity selection rules. It has been reported experimentally by direct observation that the half-life of Ta to gamma decay must be more than 10 years. Other possible modes of Ta decay (beta decay, electron capture, and alpha decay) have also never been observed. | 0 | Theoretical and Fundamental Chemistry |
There are a number of polyunsaturated fatty acids that can be reinforced by deuteration. They include (the names of the reinforced deuterated versions are separated by a slash):
* linoleic acid / D-linoleic acid (D2-Lin)
* α-linolenic acid / D-α-linolenic acid (D4-Lnn)
* arachidonic acid / D-arachidonic acid (D6-ARA)
* eicosapentaenoic acid / D-eicosapentaenoic acid (D8-EPA)
* docosahexaenoic acid / D-docosahexaenoic acid (D10-DHA) | 1 | Applied and Interdisciplinary Chemistry |
Atomitat (1962) was an underground bunker-home in Plainview, Texas, designed by architect Jay Swayze. The name of the home came from the combination of the words "atomic" and "habitat". It was the first home in the U.S. to meet civil defense specifications for a nuclear shelter. | 0 | Theoretical and Fundamental Chemistry |
A class of aliphatic acids (volatile fatty acids as a kind of carboxylic acid) was found in female rhesus monkeys that produced six types in the vaginal fluids. The combination of these acids is referred to as "copulins". One of the acids, acetic acid, was found in all of the sampled female's vaginal fluid. Even in humans, one-third of women have all six types of copulins, which increase in quantity before ovulation. Copulins are used to signal ovulation; however, as human ovulation is concealed it is thought that they may be used for reasons other than sexual communication. | 1 | Applied and Interdisciplinary Chemistry |
In order to reap the benefits of working in this small-angle regime, one must take into consideration:
* The characteristic length scale of the polymer, e.g.
* The wavelength of the scattered particles
The ratio will determine the available angular spectrum of this regime. To see this one may consider the case of elastic scattering (even approximately elastic ). If the scattering angle is , we may express as:
so the small-angle condition becomes , determining the relevant angles. | 0 | Theoretical and Fundamental Chemistry |
Applications of quorum quenching that have been exploited by humans include the use of AHL-degrading bacteria in aquacultures to limit the spread of diseases in aquatic populations of fish, mollusks and crustaceans. This technique has also been translated to agriculture, to restrict the spread of pathogenic bacteria that use quorum sensing in plants. Anti-biofouling is another process that exploits quorum quenching bacteria to mediate the dissociation of unwanted biofilms aggregating on wet surfaces, such as medical devices, transportation infrastructure and water systems. Quorum quenching is recently studied for the control of fouling and emerging contaminants in electro membrane bioreactors (eMBRs) for the advanced treatment of wastewater. Extracts of several traditional medicinal herbs display quorum quenching acivity, and have potential antibacterial applications. | 1 | Applied and Interdisciplinary Chemistry |
The empirical laws that led to the derivation of the ideal gas law were discovered with experiments that changed only 2 state variables of the gas and kept every other one constant.
All the possible gas laws that could have been discovered with this kind of setup are:
* Boyle's law ()
* Charles's law ()
* Avogadro's law ()
* Gay-Lussac's law ()
where P stands for pressure, V for volume, N for number of particles in the gas and T for temperature; where are constants in this context because of each equation requiring only the parameters explicitly noted in them changing.
To derive the ideal gas law one does not need to know all 6 formulas, one can just know 3 and with those derive the rest or just one more to be able to get the ideal gas law, which needs 4.
Since each formula only holds when only the state variables involved in said formula change while the others (which are a property of the gas but are not explicitly noted in said formula) remain constant, we cannot simply use algebra and directly combine them all. This is why: Boyle did his experiments while keeping N and T constant and this must be taken into account (in this same way, every experiment kept some parameter as constant and this must be taken into account for the derivation).
Keeping this in mind, to carry the derivation on correctly, one must imagine the gas being altered by one process at a time (as it was done in the experiments). The derivation using 4 formulas can look like this:
at first the gas has parameters
Say, starting to change only pressure and volume, according to Boyle's law (), then:
After this process, the gas has parameters
Using then equation () to change the number of particles in the gas and the temperature,
After this process, the gas has parameters
Using then equation () to change the pressure and the number of particles,
After this process, the gas has parameters
Using then Charles's law (equation 2) to change the volume and temperature of the gas,
After this process, the gas has parameters
Using simple algebra on equations (), (), () and () yields the result:
or where stands for the Boltzmann constant.
Another equivalent result, using the fact that , where n is the number of moles in the gas and R is the universal gas constant, is:
which is known as the ideal gas law.
If three of the six equations are known, it may be possible to derive the remaining three using the same method. However, because each formula has two variables, this is possible only for certain groups of three. For example, if you were to have equations (), () and () you would not be able to get any more because combining any two of them will only give you the third. However, if you had equations (), () and () you would be able to get all six equations because combining () and () will yield (), then () and () will yield (), then () and () will yield (), as well as would the combination of () and () as is explained in the following visual relation:
where the numbers represent the gas laws numbered above.
If you were to use the same method used above on 2 of the 3 laws on the vertices of one triangle that has a "O" inside it, you would get the third.
For example:
Change only pressure and volume first:
then only volume and temperature:
then as we can choose any value for , if we set , equation () becomes:
combining equations () and () yields , which is equation (), of which we had no prior knowledge until this derivation. | 0 | Theoretical and Fundamental Chemistry |
Physicians prescribed various forms of lead to heal ailments ranging from constipation to infectious diseases such as the plague. Lead was also used to preserve or sweeten wine. Lead arsenate is used in insecticides and herbicides. Some organic lead compounds are used as industrial biocides: thiomethyl triphenyllead is used as an antifungal agent, cotton preservative, and lubricant additive; thiopropyl triphenyllead as a rodent repellant; tributyllead acetate as a wood and cotton preservative; tributyllead imidazole as a lubricant additive and cotton preservative. | 1 | Applied and Interdisciplinary Chemistry |
This category includes articles relating to the topic clinical pharmacology, the science of drugs and their clinical use. | 1 | Applied and Interdisciplinary Chemistry |
Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms (- and -enantiomers), though only the -isomer exists naturally. The salts and esters of malic acid are known as malates. The malate anion is a metabolic intermediate in the citric acid cycle. | 1 | Applied and Interdisciplinary Chemistry |
Research has demonstrated that overexpression of CRBP-I increases the ability of RBP-ROH complex to phosphorylate STRA6 and, later, JAK2 and STAT5. Suppressing CRBP-I, on the other hand, led to decreased ability of RBP-ROH complex to phosphorylate STRA6 and signaling components. Similarly, reducing the expression of LRAT also decreased the ability of RBP-ROH complex to phosphorylate JAK2 and STAT5. Therefore, both CRBP-I and LRAT are necessary for the STRA6 signaling cascade upon the binding and transport of retinol. JAK2 is also conversely responsible for the activation of STRA6, after which apo-CRBP-I is recruited to the intercellular CBL of STRA6 and vitamin A might be transferred by the receptor to CRBP-I. Thus, both STRA6 signaling and STRA6 transport of vitamin A are dependent upon each other. Uptake of retinol is required for STRA6 signaling and JAK2 activation of STRA6 is necessary for retinol uptake. | 1 | Applied and Interdisciplinary Chemistry |
Capillary pressure is defined as:
where:
:is the capillary pressure
: is the pressure of the non-wetting phase
: is the pressure of the wetting phase
The wetting phase is identified by its ability to preferentially diffuse across the capillary walls before the non-wetting phase. The "wettability" of a fluid depends on its surface tension, the forces that drive a fluids tendency to take up the minimal amount of space possible, and it is determined by the contact angle of the fluid. A fluids "wettability" can be controlled by varying capillary surface properties (e.g. roughness, hydrophilicity). However, in oil-water systems, water is typically the wetting phase, while for gas-oil systems, oil is typically the wetting phase. Regardless of the system, a pressure difference arises at the resulting curved interface between the two fluids. | 1 | Applied and Interdisciplinary Chemistry |
In 1884, Jacobus van t Hoff proposed the Van t Hoff equation describing the temperature dependence of the equilibrium constant for a reversible reaction:
where ΔU is the change in internal energy, K is the equilibrium constant of the reaction, R is the universal gas constant, and T is thermodynamic temperature. Based on experimental work, in 1889, Svante Arrhenius proposed a similar expression for the rate constant of a reaction, given as follows:
Integration of this expression leads to the Arrhenius equation
where k is the rate constant. A was referred to as the frequency factor (now called the pre-exponential coefficient), and E is regarded as the activation energy. By the early 20th century many had accepted the Arrhenius equation, but the physical interpretation of A and E remained vague. This led many researchers in chemical kinetics to offer different theories of how chemical reactions occurred in an attempt to relate A and E to the molecular dynamics directly responsible for chemical reactions.
In 1910, French chemist René Marcelin introduced the concept of standard Gibbs energy of activation. His relation can be written as
At about the same time as Marcelin was working on his formulation, Dutch chemists Philip Abraham Kohnstamm, Frans Eppo Cornelis Scheffer, and Wiedold Frans Brandsma introduced standard entropy of activation and the standard enthalpy of activation. They proposed the following rate constant equation
However, the nature of the constant was still unclear. | 0 | Theoretical and Fundamental Chemistry |
Polyols may be classified according to their chemistry. Some of these chemistries are polyether, polyester, polycarbonate and also acrylic polyols. Polyether polyols may be further subdivided and classified as polyethylene oxide or polyethylene glycol (PEG), polypropylene glycol (PPG) and Polytetrahydrofuran or PTMEG. These have 2, 3 and 4 carbons respectively per oxygen atom in the repeat unit. Polycaprolactone polyols are also commercially available. There is also an increasing trend to use biobased (and hence renewable) polyols. | 0 | Theoretical and Fundamental Chemistry |
Particulate organic matter (POM) is a fraction of total organic matter operationally defined as that which does not pass through a filter pore size that typically ranges in size from 0.053 millimeters (53 μm) to 2 millimeters.
Particulate organic carbon (POC) is a closely related term often used interchangeably with POM. POC refers specifically to the mass of carbon in the particulate organic material, while POM refers to the total mass of the particulate organic matter. In addition to carbon, POM includes the mass of the other elements in the organic matter, such as nitrogen, oxygen and hydrogen. In this sense POC is a component of POM and there is typically about twice as much POM as POC. Many statements that can be made about POM apply equally to POC, and much of what is said in this article about POM could equally have been said of POC.
Particulate organic matter is sometimes called suspended organic matter, macroorganic matter, or coarse fraction organic matter. When land samples are isolated by sieving or filtration, this fraction includes partially decomposed detritus and plant material, pollen, and other materials. When sieving to determine POM content, consistency is crucial because isolated size fractions will depend on the force of agitation.
POM is readily decomposable, serving many soil functions and providing terrestrial material to water bodies. It is a source of food for both soil organisms and aquatic organisms and provides nutrients for plants. In water bodies, POM can contribute substantially to turbidity, limiting photic depth which can suppress primary productivity. POM also enhances soil structure leading to increased water infiltration, aeration and resistance to erosion. Soil management practices, such as tillage and compost/manure application, alter the POM content of soil and water. | 0 | Theoretical and Fundamental Chemistry |
Jupiter's atmosphere has 2.5 ± 0.5 times the solar abundance values for Xenon and similarly elevated argon and krypton (2.1 ± 0.5 and 2.7 ± 0.5 times solar values separately). These signals of enrichment are due to these elements coming to Jupiter in very cold (T<30K) icy planetesimals. | 0 | Theoretical and Fundamental Chemistry |
Natural products sometimes have pharmacological activity that can be of therapeutic benefit in treating diseases. Moreover, synthetic analogs of natural products with improved potency and safety can be prepared and therefore natural products are often used as starting points for drug discovery. Natural product constituents have inspired numerous drug discovery efforts that eventually gained approval as new drugs | 1 | Applied and Interdisciplinary Chemistry |
In Thomson scattering a charged particle emits radiation under incident light. The particle may be an ordinary atomic electron, so emission coefficients have practical applications.
If is the energy scattered by a volume element into solid angle between wavelengths and per unit time then the Emission coefficient is .
The values of in Thomson scattering can be predicted from incident flux, the density of the charged particles and their Thomson differential cross section (area/solid angle). | 0 | Theoretical and Fundamental Chemistry |
Outer sphere refers to an electron transfer (ET) event that occurs between chemical species that remain separate and intact before, during, and after the ET event. In contrast, for inner sphere electron transfer the participating redox sites undergoing ET become connected by a chemical bridge. Because the ET in outer sphere electron transfer occurs between two non-connected species, the electron is forced to move through space from one redox center to the other. | 0 | Theoretical and Fundamental Chemistry |
The diboron compound bis(pinacolato)diboron reacts with aromatic heterocycles or simple arenes to an arylboronate ester with iridium catalyst [IrCl(COD)] (a modification of Crabtree's catalyst) and base 4,4′-di-tert-butyl-2,2′-bipyridine in a C-H coupling reaction for example with benzene:
In one modification the arene reacts using only a stoichiometric equivalent rather than a large excess using the cheaper pinacolborane:
Unlike in ordinary electrophilic aromatic substitution (EAS) where electronic effects dominate, the regioselectivity in this reaction type is solely determined by the steric bulk of the iridium complex. This is exploited in a meta-bromination of m-xylene which by standard AES would give the ortho product: | 0 | Theoretical and Fundamental Chemistry |
The two major types of austenitic stainless steels are characterized by the oxide layer that forms on the steel surface: either chromia-forming or alumina-forming. Cr-forming stainless steel is the most common type. However, Cr-forming steels do not exhibit high creep resistance at high temperatures, especially in environments with water vapor. Exposure to water vapor at high temperatures can increase internal oxidation in Cr-forming alloys and rapid formation of volatile Cr (oxy)hydroxides, both of which can reduce durability and lifetime.
Al-forming austenitic stainless steels feature a single-phase matrix of austenite iron (FCC) with an Al-oxide at the surface of the steel. Al is more thermodynamically stable in oxygen than Cr. More commonly, however, precipitate phases are introduced to increase strength and creep resistance. In Al-forming steels, NiAl precipitates are introduced to act as Al reservoirs to maintain the protective alumina layer. In addition, Nb and Cr additions help form and stabilize Al by increasing precipitate volume fractions of NiAl.
At least 5 grades of alumina-forming austenitic (AFA) alloys, with different operating temperatures at oxidation in air + 10% water vapor have been realized:
* AFA Grade: (50-60)Fe-(20-25)Ni-(14-15)Cr-(2.5-3.5)Al-(1-3)Nb wt.% base
** 750-800 °C operating temperatures at oxidation in air + 10% water vapor
* Low Nickel AFA Grade: 63Fe-12Ni-14Cr-2.5Al-0.6Nb-5Mn3Cu wt.% base
** 650 °C operating temperatures at oxidation in air + 10% water vapor
* High Performance AFA Grade: (45-55)Fe-(25-30)Ni-(14-15)Cr(3.5-4.5)Al-(1-3)Nb-(0.02-0.1)Hf/Y wt.% base
** 850-900 °C operating temperatures at oxidation in air + 10% water vapor
* Cast AFA Grade: (35-50)Fe-(25-35)Ni-14Cr-(3.5-4)Al-1Nb wt.% base
** 750-1100 °C operating temperatures at oxidation in air + 10% water vapor, depending upon Ni wt.%
* AFA superalloy (40-50)Fe-(30-35)Ni-(14-19)Cr-(2.5-3.5)Al-3Nb
** 750-850 °C operating temperatures at oxidation in air + 10% water vapor
Operating temperatures with oxidation in air and no water vapor are expected to be higher. In addition, an AFA superalloy grade exhibits creep strength approaching that of nickel alloy UNS N06617. | 1 | Applied and Interdisciplinary Chemistry |
Giant tube worms use bacteria in their trophosome to fix carbon dioxide (using hydrogen sulfide as their energy source) and produce sugars and amino acids.
Some reactions produce sulfur:
:hydrogen sulfide chemosynthesis:
::18H + 6CO + 3 → CHO (carbohydrate) + 12H + 18
Instead of releasing oxygen gas while fixing carbon dioxide as in photosynthesis, hydrogen sulfide chemosynthesis produces solid globules of sulfur in the process. In bacteria capable of chemoautotrophy (a form a chemosynthesis), such as purple sulfur bacteria, yellow globules of sulfur are present and visible in the cytoplasm. | 1 | Applied and Interdisciplinary Chemistry |
Force tuning has recently proven its efficiency with a maximum error of 5% in comparison with standard finite element solvers in mechanics. Accurate validation of results can also be a tedious task since these methods are very different, common issues are:
* Meshes or lattice discretization
* Location of computed fields at elements or nodes
* Hidden information in softwares used for finite element analysis comparison
* Non-linear materials
* Steady state convergence for LBMS | 0 | Theoretical and Fundamental Chemistry |
These rules are based on empirical evidence and numerous "exceptions" are known. Examples include:
* cyclisations of cations
* reactions involving third-row atoms, such as sulfur
* Transition metal catalysis | 0 | Theoretical and Fundamental Chemistry |
AOAC Research Institute (AOAC RI) Performance Tested Methods program develops, improves, and validates proprietary kit-based food safety testing methods. | 0 | Theoretical and Fundamental Chemistry |
*Diagnostic test strips, developed by Helen Murray Free and Alfred Free at Miles Laboratories (now Bayer AG) in the 1950s
*Discovery of fullerenes by Richard Smalley, Robert Curl, James R. Heath, Sean O'Brien, and Harold Kroto at Rice University in 1985 | 1 | Applied and Interdisciplinary Chemistry |
The mature mRNA finds its way to a ribosome, where it gets translated. In prokaryotic cells, which have no nuclear compartment, the processes of transcription and translation may be linked together without clear separation. In eukaryotic cells, the site of transcription (the cell nucleus) is usually separated from the site of translation (the cytoplasm), so the mRNA must be transported out of the nucleus into the cytoplasm, where it can be bound by ribosomes. The ribosome reads the mRNA triplet codons, usually beginning with an AUG (adenine−uracil−guanine), or initiator methionine codon downstream of the ribosome binding site. Complexes of initiation factors and elongation factors bring aminoacylated transfer RNAs (tRNAs) into the ribosome-mRNA complex, matching the codon in the mRNA to the anti-codon on the tRNA. Each tRNA bears the appropriate amino acid residue to add to the polypeptide chain being synthesised. As the amino acids get linked into the growing peptide chain, the chain begins folding into the correct conformation. Translation ends with a stop codon which may be a UAA, UGA, or UAG triplet.
The mRNA does not contain all the information for specifying the nature of the mature protein. The nascent polypeptide chain released from the ribosome commonly requires additional processing before the final product emerges. For one thing, the correct folding process is complex and vitally important. For most proteins it requires other chaperone proteins to control the form of the product. Some proteins then excise internal segments from their own peptide chains, splicing the free ends that border the gap; in such processes the inside "discarded" sections are called inteins. Other proteins must be split into multiple sections without splicing. Some polypeptide chains need to be cross-linked, and others must be attached to cofactors such as haem (heme) before they become functional. | 1 | Applied and Interdisciplinary Chemistry |
Collagen is the primary component of the extracellular matrix. Collagen scaffolds efficiently support fibroblast growth, which in turn allows keratinocytes to grow nicely into multilayers. Collagen (mainly collagen type I) is often used as a scaffold because it is biocompatible, non-immunogenic and available. However, collagen biodegrades relatively rapidly and is not good at withstanding mechanical forces. Improved characteristics can be created by cross-linking collagen-based matrices: this is an effective method to correct the instability and mechanical properties. | 1 | Applied and Interdisciplinary Chemistry |
Areas that have limited surface water or groundwater may choose to desalinate. RO is an increasingly common method, because of its relatively low energy consumption.
Energy consumption is around , with the development of more efficient energy recovery devices and improved membrane materials. According to the International Desalination Association, for 2011, RO was used in 66% of installed desalination capacity (0.0445 of 0.0674 km/day), and nearly all new plants. Other plants use thermal distillation methods: multiple-effect distillation, and multi-stage flash.
Sea-water RO (SWRO) desalination requires around 3 kWh/m, much higher than those required for other forms of water supply, including RO treatment of wastewater, at 0.1 to 1 kWh/m. Up to 50% of the seawater input can be recovered as fresh water, though lower recovery rates may reduce membrane fouling and energy consumption.
Brackish water reverse osmosis (BWRO) is the desalination of water with less salt than seawater, usually from river estuaries or saline wells. The process is substantially the same as SWRO, but requires lower pressures and less energy. Up to 80% of the feed water input can be recovered as fresh water, depending on feed salinity.
The Ashkelon desalination plant in Israel is the world's largest.
The typical single-pass SWRO system consists of:
* Intake
* Pretreatment
* High-pressure pump (if not combined with energy recovery)
* Membrane assembly
* Energy recovery (if used)
* Remineralisation and pH adjustment
* Disinfection
* Alarm/control panel | 0 | Theoretical and Fundamental Chemistry |
TAD locations are defined by applying an algorithm to Hi-C data. For example, TADs are often called according to the so-called "directionality index". The directionality index is calculated for individual 40kb bins, by collecting the reads that fall in the bin, and observing whether their paired reads map upstream or downstream of the bin (read pairs are required to span no more than 2Mb). A positive value indicates that more read pairs lie downstream than upstream, and a negative value indicates the reverse. Mathematically, the directionality index is a signed chi-square statistic.
The development of specialized genome browsers and visualization tools such as Juicebox, HiGlass/HiPiler, The 3D Genome Browser, 3DIV, 3D-GNOME, and TADKB have enabled us to visualize the TAD organization of regions of interest in different cell types. | 1 | Applied and Interdisciplinary Chemistry |
ST2-PT (Single Transition-to-single Transition Polarization Transfer) is a method of sensitivity enhancement in NMR spectroscopy, developed by K.V. Pervushin, G. Wider, and K. Wüthrich in 1998.
This method affords a sensitivity enhancement for kinetically stable amide 15N–1H groups in proteins. | 0 | Theoretical and Fundamental Chemistry |
Once the fatty acid is inside the mitochondrial matrix, beta-oxidation occurs by cleaving two carbons every cycle to form acetyl-CoA. The process consists of 4 steps.
# A long-chain fatty acid is dehydrogenated to create a trans double bond between C2 and C3. This is catalyzed by acyl CoA dehydrogenase to produce trans-delta 2-enoyl CoA. It uses FAD as an electron acceptor and it is reduced to FADH.
# Trans-delta 2-enoyl CoA is hydrated at the double bond to produce L-3-hydroxyacyl CoA by enoyl-CoA hydratase.
# L-3-hydroxyacyl CoA is dehydrogenated again to create 3-ketoacyl CoA by 3-hydroxyacyl CoA dehydrogenase. This enzyme uses NAD as an electron acceptor.
# Thiolysis occurs between C2 and C3 (alpha and beta carbons) of 3-ketoacyl CoA. Thiolase enzyme catalyzes the reaction when a new molecule of coenzyme A breaks the bond by nucleophilic attack on C3. This releases the first two carbon units, as acetyl CoA, and a fatty acyl CoA minus two carbons. The process continues until all of the carbons in the fatty acid are turned into acetyl CoA.
This acetyl-CoA then enters the mitochondrial tricarboxylic acid cycle (TCA cycle). Both the fatty acid beta-oxidation and the TCA cycle produce NADH and FADH, which are used by the electron transport chain to generate ATP.
Fatty acids are oxidized by most of the tissues in the body. However, some tissues such as the red blood cells of mammals (which do not contain mitochondria) and cells of the central nervous system do not use fatty acids for their energy requirements, but instead use carbohydrates (red blood cells and neurons) or ketone bodies (neurons only).
Because many fatty acids are not fully saturated or do not have an even number of carbons, several different mechanisms have evolved, described below. | 1 | Applied and Interdisciplinary Chemistry |
For a heuristic argument, consider a thin airfoil of chord and infinite span, moving through air of density . Let the airfoil be inclined to the oncoming flow to produce an air speed on one side of the airfoil, and an air speed on the other side. The circulation is then
The difference in pressure between the two sides of the airfoil can be found by applying Bernoulli's equation:
so the downward force on the air, per unit span, is
and the upward force (lift) on the airfoil is
A differential version of this theorem applies on each element of the plate and is the basis of thin-airfoil theory. | 1 | Applied and Interdisciplinary Chemistry |
A combination tee (combo tee, combo wye, tee-wye, long-sweep wye, or combi) is a tee with a gradually curving central connecting joint: a wye plus an additional 1/8 bend (45°), combined in one 90° unit. It is used in drains for a smooth, gradually curving path to reduce the likelihood of clogs, to ease the pushing of a plumber's snake through a drain system and to encourage water flow in the direction of the drain. | 1 | Applied and Interdisciplinary Chemistry |
Transcriptional regulation is one of the most common ways for an organism to alter gene expression. The use of activation and coactivation allows for greater control over when, where and how much of a protein is produced. This enables each cell to be able to quickly respond to environmental or physiological changes and helps to mitigate any damage that may occur if it were otherwise unregulated. | 1 | Applied and Interdisciplinary Chemistry |
Neurochemistry International is a peer-reviewed scientific journal covering research in neurochemistry, including molecular and cellular neurochemistry, neuropharmacology and genetic aspects of central nervous system function, neuroimmunology, metabolism as well as the neurochemistry of neurological and psychiatric disorders of the CNS. It is published by Elsevier and the editor-in-chief is Michael Robinson (Childrens Hospital of Philadelphia). According to the Journal Citation Reports', the journal has a 2021 impact factor of 4.297. | 1 | Applied and Interdisciplinary Chemistry |
The Autonomous Landing Hazard Avoidance Technology used in NASAs Project Morpheus lunar lander to automatically find a safe landing place contains a lidar Doppler velocimeter that measures the vehicles altitude and velocity. The AGM-129 ACM cruise missile uses laser doppler velocimeter for precise terminal guidance. | 1 | Applied and Interdisciplinary Chemistry |
The reaction occurring between double bonds and ozone is known as ozonolysis when one molecule of the gas reacts with the double bond:
The immediate result is formation of an ozonide, which then decomposes rapidly so that the double bond is cleaved. This is the critical step in chain breakage when polymers are attacked. The strength of polymers depends on the chain molecular weight or degree of polymerization: The higher the chain length the greater the mechanical strength (such as tensile strength). By cleaving the chain, the molecular weight drops rapidly and there comes a point when it has little strength whatsoever, and a crack forms. Further attack occurs in the freshly exposed crack surfaces and the crack grows steadily until it completes a circuit and the product separates or fails. In the case of a seal or a tube, failure occurs when the wall of the device is penetrated.
The carbonyl end groups that are formed are usually aldehydes or ketones, which can oxidise further to carboxylic acids. The net result is a high concentration of elemental oxygen on the crack surfaces, which can be detected using EDX in the ESEM. For example, two EDX spectra were obtained during an investigation into ozone cracking of diaphragm seals in a semiconductor fabrication factory. The EDX spectrum of the crack surface shows the high-oxygen peak compared with a constant sulfur peak. In contrast, the EDX spectrum of the unaffected elastomer surface spectrum shows a relatively low-oxygen peak compared with the sulfur peak. | 0 | Theoretical and Fundamental Chemistry |
Usually when describing a space geometrically, a coordinate system is used which consists of a choice of origin and a basis of linearly independent, non-coplanar basis vectors , where is the dimension of the space being described. With reference to this coordinate system, each point in the space can be specified by coordinates (a coordinate -tuple). The origin has coordinates and an arbitrary point has coordinates . The position vector is then,
In -dimensions, the lengths of the basis vectors are denoted and the angles between them . However, most cases in crystallography involve two- or three-dimensional space in which the basis vectors are commonly displayed as with their lengths and angles denoted by and respectively. | 0 | Theoretical and Fundamental Chemistry |
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