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When material is heated enough, it begins to break down into smaller compounds, including flammable or even explosive gas, typically hydrocarbons. This is called pyrolysis, and does not require oxygen. If oxygen is also provided, then the hydrocarbons can combust, starting a fire.
If material undergoing pyrolysis is later given sufficient oxygen, the hydrocarbons will ignite, and therefore, combustion takes place. | 0 | Theoretical and Fundamental Chemistry |
In the U.S. it is marketed as Zinacef by Covis Pharmaceuticals since the company acquired the U.S. rights to the product from GSK. GSK had continued marketing a pediatric oral suspension as Ceftin; however, this presentation was discontinued as of 24 June 2017.
In Bangladesh, it is available as Kilbac by Incepta, Axim by Aristopharma, Rofurox by Radiant and Xorimax by Sandoz. In India, it is available as Ceftum and "Cefuall" by Allencia Biosciences in tablet form and Supacef in injection form by GSK. In Poland, it is available as Zamur by Mepha, subsidiary of Teva Pharmaceutical Industries. In Australia, the "first generic" form of Cefuroxime axetil, Pharmacor Cefuroxime (tablets) from Pharmacor Pty Ltd, was registered on 27 March 2017, by the Therapeutic Goods Administration. Cefuroxime axetil is sold in tablet form in Turkey inder the brand names Aksef and Cefaks. Cefuroxime axetil is also available (in two strengths) as granules for oral suspension from Aspen Pharmacare Australia Pty Ltd under the brand name Zinnat cefuroxime. | 0 | Theoretical and Fundamental Chemistry |
Silver standards refer to the standards of millesimal fineness for the silver alloy used in the manufacture or crafting of silver objects. This list is organized from highest to lowest millesimal fineness, or purity of the silver.
* Fine silver has a millesimal fineness of 999. Also called pure silver, or three nines fine, fine silver contains 99.9% silver, with the balance being some trace amounts of impurities. This grade of silver is used to make bullion bars for international commodities trading and investment in silver. In the modern world, fine silver is understood to be too soft for general use.
* Britannia silver has a millesimal fineness of at least 958. The alloy is 95.84% pure silver and 4.16% copper or other metals. The Britannia standard was developed in Britain in 1697 to help prevent British sterling silver coins from being melted to make silver plate. It was obligatory in Britain between 1697 and 1720, when the sterling silver standard was restored. It became an optional standard thereafter.
* The French 1st standard has a milessimal fineness of 950. The French 1st alloy is 95% silver and 5% copper or other metals.
* 91 zolotnik Russian silver has a millesimal fineness of 947. The zolotnik (Russian золотник, from the Russian zoloto, or золото, meaning gold) was used in Russia as early as the 11th century to denote the weight of gold coins. In its earliest usage, the zolotnik was 1/96 of a pound, but it later was changed to represent 1/72 of a pound. Ninety-one (91) zolotniks have the equivalent millesimal fineness of 947[9]. Thus, the alloy contains 94.79% pure silver and 5.21% copper or other metals.
* Sterling silver has a millesimal fineness of 925. The sterling silver alloy is 92.5% pure silver and 7.5% copper or other metals. This alloy was used by the United Kingdom from the early 12th century, and Canada, Australia and other countries associated with the British Empire (and later Commonwealth) from the 19th century up to the mid-20th century when debasement took place; Sterling silver’s copper content means that it has a stronger tendency to tarnish than other alloys used in coins.
*Following a program of debasements in the early-to-mid 20th century, circulating Canadian coinage (with the exception of the nickel) had a millesimal fineness of 800 until 1968. The alloy used contained 80% silver and 20% copper.
* 88 zolotnik Russian silver has the equivalent millesimal fineness of 916[6]. The alloy contains 91.66% pure silver and 8.34% copper or other metals. (The description of the zolotnik is above.)
* Coin silver has a millesimal fineness of 900. The term "coin silver" was derived from the fact that much of it was made from melting down silver coins. It is important here to note that there are differences between the coin silver standard and the coin silver alloy, as actually used in making silver objects. The coin silver standard in the United States was 90% silver and 10% copper, as dictated by US FTC guidelines. However, in silversmithing, coins could come from other nations besides the United States, and thus coin silver objects could vary from 750 millesimal fineness (75% silver) to 900 (90% silver). Coins were used as a source of silver in the US until 1868, shortly after the discovery of the Comstock silver lodes in Nevada, which provided a significant source of silver. Around this time the sterling standard was adopted by the American silver industry.
* 84 zolotnik Russian silver has the equivalent millesimal fineness of 875. The alloy contains 87.5% pure silver and 12.5% copper or other metals. (See above for description of the zolotnik.)
* has a millesimal fineness of 830. The Scandinavian silver alloy contains 83% pure silver and 17% copper or other metals.
* German silver will be marked with a millesimal fineness of 800 or 835 (80% or 83.5% pure silver). Any items simply marked "German silver", "nickel silver" or "Alpaca" have no silver content at all, but are mere alloys of other base metals.
* Decoplata has the equivalent millesimal fineness of 720. The alloy contains 72% pure silver and 28% copper. It was used by a number of countries between the 19th century and the present, but it is most associated with coins made in Mexico and the Netherlands in the mid-20th Century. | 1 | Applied and Interdisciplinary Chemistry |
The first medical application of electroporation was used for introducing poorly permeant anticancer drugs into tumor nodules. Soon also gene electrotransfer became of special interest because of its low cost, easiness of realization and safety. Namely, viral vectors can have serious limitations in terms of immunogenicity and pathogenicity when used for DNA transfer.
Irreversible electroporation is being used and evaluated as cardiac ablation therapy to kill very small areas of heart muscle. This is done to treat irregularities of heart rhythm. A cardiac catheter delivers trains of high-voltage ultra-rapid electrical pulses that form irreversible pores in cell membranes, resulting in cell death. It is thought to allow better selectivity than the previous techniques, which used heat or cold to kill larger volumes of muscle.
A higher voltage of electroporation was found in pigs to irreversibly destroy target cells within a narrow range while leaving neighboring cells unaffected, and thus represents a promising new treatment for cancer, heart disease and other disease states that require removal of tissue. Irreversible electroporation (IRE) has since proven effective in treating human cancer, with surgeons at Johns Hopkins and other institutions now using the technology to treat pancreatic cancer previously thought to be unresectable.
Also first phase I clinical trial of gene electrotransfer in patients with metastatic melanoma was reported. Electroporation mediated delivery of a plasmid coding gene for interleukin-12 (pIL-12) was performed and safety, tolerability and therapeutic effect were monitored. Study concluded, that gene electrotransfer with pIL-12 is safe and well tolerated. In addition partial or complete response was observed also in distant non treated metastases, suggesting the systemic treatment effect. Based on these results they are already planning to move to Phase II clinical study. There are currently several ongoing clinical studies of gene electrotransfer where safety, tolerability and effectiveness of immunization with DNA vaccine, which is administered by the electric pulses is monitored.
Although the method is not systemic, but strictly local one, it is still the most efficient non-viral strategy for gene delivery. | 1 | Applied and Interdisciplinary Chemistry |
In general, the associated increased signal-to-noise and resolution has driven a move towards increasingly high field strengths. In limited cases, however, lower fields are preferred; examples are for systems in chemical exchange, where the speed of the exchange relative to the NMR experiment can cause additional and confounding linewidth broadening. Similarly, while avoidance of second order coupling is generally preferred, this information can be useful for elucidation of chemical structures. Using refocussing pulses placed between recording of successive points of the free induction decay, in an analogous fashion to the spin echo technique in MRI, the chemical shift evolution can be scaled to provide apparent low-field spectra on a high-field spectrometer. In a similar fashion, it is possible to upscale the effect of J-coupling relative to the chemical shift using pulse sequences that include additional J-coupling evolution periods interspersed with conventional spin evolutions. | 0 | Theoretical and Fundamental Chemistry |
In general, bulk flow in plant biology typically refers to the movement of water from the soil up through the plant to the leaf tissue through xylem, but can also be applied to the transport of larger solutes (e.g. sucrose) through the phloem. | 1 | Applied and Interdisciplinary Chemistry |
Lime production was sometimes carried out on an industrial scale. One example at Annery in North Devon, England, near Great Torrington, was made up of three kilns grouped together in an L shape and was situated beside the Torrington canal and the River Torridge to bring in the limestone and coal, and to transport away the calcined lime in the days before properly metalled roads existed.
Sets of seven kilns were common. A loading gang and an unloading gang would work the kilns in rotation through the week.
A rarely used kiln was known as a "lazy kiln". | 1 | Applied and Interdisciplinary Chemistry |
In Sisyphus cooling, the two hyperfine ground states of experience equal and opposite AC Stark shifts from the near-resonant counter-propagating beams. The beams also effect a polarization gradient, alternating between linear and circular polarizations. The potential energy maxima of one coincide with pure circular polarization, which optically pumps atoms to the other , which experiences its minima in the same location. Over time, the atoms expend their kinetic energy traversing the potential energy landscape and transferring the potential energy difference between the crests and troughs of the AC-Stark-shifted ground state levels to emitted photons.
In contrast, gray molasses only has one sinusoidally light-shifted ground state; optical pumping at the peaks of this potential energy landscape takes atoms to the dark state, which can selectively evolve to the bright state and re-enter the cycle with sufficient momentum. Sisyphus cooling is difficult to implement when the excited state manifold is poorly-resolved (i.e. whose hyperfine spacing is comparable to or less than the constituent linewidths); in these atomic species, the Raman-type gray molasses is preferable. | 0 | Theoretical and Fundamental Chemistry |
Lithium amides like the diisopropylamide (LDA) and the (tetramethylpiperidide (LiTMP)) generally work well for the deprotonation of all types of salts, providing that not too much LiOH is present in the n-butyllithium used to make the lithium amide. Titration of lithium amide can be used to determine the amount of hydroxide in solution. The deprotonation of precursor salts with metal hexamethyldisilazides works very cleanly for the deprotonation of all types of salts, except for unhindered formamidinium salts, where this base can act as a nucleophile to give a triaminomethane adduct. | 0 | Theoretical and Fundamental Chemistry |
In 2014, researchers at California NanoSystems Institute discovered using kesterite and perovskite improved electric power conversion efficiency for solar cells.
In December 2022, it was reported that MIT researchers had developed ultralight fabric solar cells. These cells offer a weight one-hundredth that of traditional panels while generating 18 times more power per kilogram. Thinner than a human hair, these cells can be laminated onto various surfaces, such as boat sails, tents, tarps, or drone wings, to extend their functionality. Using ink-based materials and scalable techniques, researchers coat the solar cell structure with printable electronic inks, completing the module with screen-printed electrodes. Tested on high-strength fabric, the cells produce 370 watts-per-kilogram, representing an improvement over conventional solar cells. | 0 | Theoretical and Fundamental Chemistry |
On January 21, 2015, Nick Goldman from the European Bioinformatics Institute (EBI), one of the original authors of the 2013 Nature paper, announced the Davos Bitcoin Challenge at the World Economic Forum annual meeting in Davos. During his presentation, DNA tubes were handed out to the audience, with the message that each tube contained the private key of exactly one bitcoin, all coded in DNA. The first one to sequence and decode the DNA could claim the bitcoin and win the challenge. The challenge was set for three years and would close if nobody claimed the prize before January 21, 2018.
Almost three years later on January 19, 2018, the EBI announced that a Belgian PhD student, Sander Wuyts, of the University of Antwerp and Vrije Universiteit Brussel, was the first one to complete the challenge. Next to the instructions on how to claim the bitcoin (stored as a plain text and PDF file), the logo of the EBI, the logo of the company that printed the DNA (CustomArray), and a sketch of James Joyce were retrieved from the DNA. | 1 | Applied and Interdisciplinary Chemistry |
AMPP administers accreditation programs for contractors working in the protective coatings and linings industries. "QP" stands for "Qualification Procedure", a reference to the technical standard that underlies each program.
*QP 1, Field Application to Complex Industrial and Marine Structures
*QP 2, Field Removal of Hazardous Coatings
*QP 3, Shop Painting (QP 3 is a joint standard also used by AISC for their sophisticated paint endorsement.)
*QP 5, Coating and Lining Inspection Companies
*QP 6, Metallizing
*QP 7, Painting Contractor Introductory Program
*QP 8, Installation of Polymer Coatings and Surfacings on Concrete and Other Cementitious Surfaces
*QP 9, Commercial Painting and Coating Contractors
*QN 1, Nuclear Coating Supplement
*QS 1, Advanced Quality Management System (ISO 9001-compliant) | 1 | Applied and Interdisciplinary Chemistry |
Yamamoto et al. in 2012 demonstrated that BNA-based antisense therapeutics inhibited hepatic PCSK9 expression, resulting in a strong reduction of the serum LDL-C levels of mice. The findings supported the hypothesis that PCSK9 is a potential therapeutic target for hypercholesterolemia and the researchers were able to show that BNA-based antisense oligonucleotides (AONs) induced cholesterol-lowering action in hypercholesterolemic mice. A moderate increase of aspartate aminotransferase, ALT, and blood urea nitrogen levels was observed whereas the histopathological analysis revealed no severe hepatic toxicities. The same group, also in 2012, reported that the 2,4-BNA[NMe] analog when used in antisense oligonucleotides showed significantly stronger inhibitory activities which is more pronounced in shorter (13- to 16mer) oligonucleotides. Their data led the researchers to conclude that the 2,4-BNA[NMe] analog may be a better alternative to conventional LNAs. | 1 | Applied and Interdisciplinary Chemistry |
Also in 1989, Peko Mines, then a division of North Broken Hill Peko Limited, also engaged Jameson to undertake test work in its Warrego concentrator near Tennant Creek in Australias Northern Territory. The objective was to determine the Jameson Cells performance in cleaning copper concentrate to improve its grade by removing gangue minerals, including pyrite, magnetite, hematite and quartz. Peko Mines personnel also tested a conventional flotation column for comparison. Following the test work, Peko Mines installed two full-scale, 1.4 m diameter Jameson Cells in the concentrator, each with three downcomers.
Peko Mines' decision was based on:
* metallurgical performance during pilot plant test work
* lower capital expenditure and installation costs
* shorter construction and installation times
* ease of operation and lower expected maintenance costs.
Peko Mines reported a payback on the investment in the Cells of two months. | 1 | Applied and Interdisciplinary Chemistry |
The use of injectors (or ejectors) in various industrial applications has become quite common due to their relative simplicity and adaptability. For example:
* To inject chemicals into the boiler drums of small, stationary, low pressure boilers. In large, high-pressure modern boilers, usage of injectors for chemical dosing is not possible due to their limited outlet pressures.
* In thermal power stations, they are used for the removal of the boiler bottom ash, the removal of fly ash from the hoppers of the electrostatic precipitators used to remove that ash from the boiler flue gas, and for drawing a vacuum pressure in steam turbine exhaust condensers.
* Jet pumps have been used in boiling water nuclear reactors to circulate the coolant fluid.
* For use in producing a vacuum pressure in steam jet cooling systems.
* For expansion work recovery in air conditioning and refrigeration systems.
* For enhanced oil recovery processes in the oil & gas Industry.
* For the bulk handling of grains or other granular or powdered materials.
* The construction industry uses them for pumping turbid water and slurries.
* Eductors are used in ships to pump residual ballast water, or cargo oil which cannot be removed using centrifugal pumps due to loss of suction head and may damage the centrifugal pump if run dry, which may be caused due to trim or list of the ship.
* Eductors are used on-board ships to pump out bilges, since using centrifugal pump would not be feasible as the suction head may be lost frequently.
* Some aircraft (mostly earlier designs) use an ejector attached to the fuselage to provide vacuum for gyroscopic instruments such as an attitude indicator (artificial horizon).
* Eductors are used in aircraft fuel systems as transfer pumps; fluid flow from an engine-mounted mechanical pump can be delivered to a fuel tank-mounted eductor to transfer fuel from that tank.
* Aspirators are vacuum pumps based on the same operating principle and are used in laboratories to create a partial vacuum and for medical use in suction of mucus or bodily fluids.
* Water eductors are water pumps used for dredging silt and panning for gold, they're used because they can handle the highly abrasive mixtures quite well.
* To create vacuum system in vacuum distillation unit (oil refinery).
* Vacuum autoclaves use an ejector to pull a vacuum, generally powered by the cold water supply to the machine.
* Low weight jet pumps can be made out of paper mache. | 1 | Applied and Interdisciplinary Chemistry |
The Portland Press Excellence in Science Award was an annual award instituted in 1964 to recognize notable research in any branch of biochemistry undertaken in the UK or Republic of Ireland. It was initially called the CIBA Medal and Prize, then the Novartis Medal and Prize. The prize consists of a medal and a £3000 cash award. The winner is invited to present a lecture at a Society conference and submit an article to one of the Society's publications. Notable recipients include the Nobel laureates John E. Walker, Paul Nurse, Sydney Brenner, César Milstein, Peter D. Mitchell, Rodney Porter, and John Cornforth.
The Novartis Medal and Prize was last presented in 2019 and will be replaced from 2021 by the Portland Press Excellence in Science Award. Portland Press is the publishing arm of the Biochemical Society. | 1 | Applied and Interdisciplinary Chemistry |
Isolated photosystems and sub-cellular photosynthetic fractions may be able to directly reduce the anode if the biological redox components are close enough to the electrode for electron transfer to occur. In contrast to organisms such as dissimilatory metal reducing bacteria, algae and cyanobacteria are poorly adapted for extracellular electron export - no molecular mechanisms enabling direct reduction of an insoluble extracellular electron acceptor have been conclusively identified. Nevertheless, a low rate of anode reduction has been observed from whole photosynthetic organisms without the addition of exogenous redox-active compounds. It has been speculated that electron transfer occurs through the release of low concentrations of endogenous redox mediator compounds. Improving the electron export activity of cyanobacteria for use in biological photovoltaic systems is a topic of current research. | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, Couette flow is the flow of a viscous fluid in the space between two surfaces, one of which is moving tangentially relative to the other. The relative motion of the surfaces imposes a shear stress on the fluid and induces flow. Depending on the definition of the term, there may also be an applied pressure gradient in the flow direction.
The Couette configuration models certain practical problems, like the Earth's mantle and atmosphere, and flow in lightly loaded journal bearings. It is also employed in viscometry and to demonstrate approximations of reversibility.
It is named after Maurice Couette, a Professor of Physics at the French University of Angers in the late 19th century. | 1 | Applied and Interdisciplinary Chemistry |
Examples of studies involving putative genes include the discovery of 30 putative receptor genes found in rat vomeronasal organ (VNO) and the identification of 79 putative TATA boxes found in many plant genomes. | 1 | Applied and Interdisciplinary Chemistry |
Although the classification of tumor suppressor genes into these categories is helpful to the scientific community, the potential role of many genes cannot be reliably identified as the functions of many genes are rather ill-defined. In some contexts, genes exhibit discrete caretaker function while in other situations gatekeeper characteristics are recognized. An example of one such gene is p53. Patients with Li-Fraumeni syndrome, for example, have mutations in the p53 gene that suggest caretaker function. p53 has an identified role, however, in regulating the cell cycle as well, which is an essential gatekeeper function. | 1 | Applied and Interdisciplinary Chemistry |
In the field of bioinformatics and computational biology, many statistical methods have been proposed and used to analyze codon usage bias. Methods such as the frequency of optimal codons (Fop), the relative codon adaptation (RCA) or the codon adaptation index (CAI) are used to predict gene expression levels, while methods such as the effective number of codons (Nc) and Shannon entropy from information theory are used to measure codon usage evenness. Multivariate statistical methods, such as correspondence analysis and principal component analysis, are widely used to analyze variations in codon usage among genes. There are many computer programs to implement the statistical analyses enumerated above, including CodonW, GCUA, INCA, etc. Codon optimization has applications in designing synthetic genes and DNA vaccines. Several software packages are available online for this purpose (refer to external links). | 1 | Applied and Interdisciplinary Chemistry |
A chemical garden is a set of complex biological-looking structures created by mixing inorganic chemicals. This experiment in chemistry is usually performed by adding metal salts, such as copper sulfate or cobalt(II) chloride, to an aqueous solution of sodium silicate (otherwise known as waterglass). This results in the growth of plant-like forms in minutes to hours.
The chemical garden was first observed and described by Johann Rudolf Glauber in 1646. In its original form, the chemical garden involved the introduction of ferrous chloride (FeCl) crystals into a solution of potassium silicate (KSiO). | 1 | Applied and Interdisciplinary Chemistry |
Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.
Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, molecules begin to vibrate and move more, usually creating more distance between themselves. Substances which contract with increasing temperature are unusual, and only occur within limited temperature ranges (see examples below).
The relative expansion (also called strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. As energy in particles increases, they start moving faster and faster, weakening the intermolecular forces between them and therefore expanding the substance. | 0 | Theoretical and Fundamental Chemistry |
A single-acting cylinder (SAC) has one port, which allows compressed air to enter and for the rod to move in one direction only. The high pressure of the compressed air causes the rod to extend as the cylinder chamber continues to fill. When the compressed air leaves the cylinder through the same port the rod is returned to its original position. | 1 | Applied and Interdisciplinary Chemistry |
In the Burke-Schumann limit, the flame is considered as a thin reaction sheet outside which both fuel and oxygen cannot exist together, i.e., . The reaction sheet itself is located by the stoichiometric surface where , in other words, where
where is the stoichiometric mixture fraction. The reaction sheet separates fuel and oxidizer region. The inner structure of the reaction sheet is described by Liñán's equation. On the fuel side of the reaction sheet ()
and on the oxidizer side ()
For given values of (or, ) and , the flame shape is given by the condition , i.e.,
When (), the flame extends from the mouth of the inner tube and attaches itself to the outer tube at a certain height (under-ventilated case) and when (), the flame starts from the mouth of the inner tube and joins at the axis at some height away from the mouth (over-ventilated case). In general, the flame height is obtained by solving for in the above equation after setting for the under-ventilated case and for the over-ventilated case.
Since flame heights are generally large for the exponential terms in the series to be negligible, as a first approximation flame height can be estimated by keeping only the first term of the series. This approximation predicts flame heights for both cases as follows
where | 1 | Applied and Interdisciplinary Chemistry |
Quasicrystalline substances have potential applications in several forms.
Metallic quasicrystalline coatings can be applied by Thermal spraying or magnetron sputtering. A problem that must be resolved is the tendency for cracking due to the materials' extreme brittleness. The cracking could be suppressed by reducing sample dimensions or coating thickness. Recent studies show typically brittle quasicrystals can exhibit remarkable ductility of over 50% strains at room temperature and sub-micrometer scales (<500 nm).
An application was the use of low-friction Al–Cu–Fe–Cr quasicrystals as a coating for frying pans. Food did not stick to it as much as to stainless steel making the pan moderately non-stick and easy to clean; heat transfer and durability were better than PTFE non-stick cookware and the pan was free from perfluorooctanoic acid (PFOA); the surface was very hard, claimed to be ten times harder than stainless steel, and not harmed by metal utensils or cleaning in a dishwasher; and the pan could withstand temperatures of without harm. However, after an initial introduction the pans were a chrome steel, probably because of the difficulty of controlling thin films of the quasicrystal.
The Nobel citation said that quasicrystals, while brittle, could reinforce steel "like armor". When Shechtman was asked about potential applications of quasicrystals he said that a precipitation-hardened stainless steel is produced that is strengthened by small quasicrystalline particles. It does not corrode and is extremely strong, suitable for razor blades and surgery instruments. The small quasicrystalline particles impede the motion of dislocation in the material.
Quasicrystals were also being used to develop heat insulation, LEDs, diesel engines, and new materials that convert heat to electricity. Shechtman suggested new applications taking advantage of the low coefficient of friction and the hardness of some quasicrystalline materials, for example embedding particles in plastic to make strong, hard-wearing, low-friction plastic gears. The low heat conductivity of some quasicrystals makes them good for heat insulating coatings. One of the special properties of quasicrystals is their smooth surface, which despite the irregular atomic
structure, the surface of quasicrystals can be smooth and flat.
Other potential applications include selective solar absorbers for power conversion, broad-wavelength reflectors, and bone repair and prostheses applications where biocompatibility, low friction and corrosion resistance are required. Magnetron sputtering can be readily applied to other stable quasicrystalline alloys such as Al–Pd–Mn. | 0 | Theoretical and Fundamental Chemistry |
The compounds nitryl fluoride, , and nitryl chloride, , are not nitronium salts but molecular compounds, as shown by their low boiling points (−72 °C and −6 °C respectively) and short nitrogen–halogen bond lengths (N–F 135 pm, N–Cl 184 pm).
Addition of one electron forms the neutral nitryl radical, ; in fact, this is fairly stable and known as the compound nitrogen dioxide.
The related negatively charged species is , the nitrite ion. | 0 | Theoretical and Fundamental Chemistry |
Claire Vallance is a professor of Physical Chemistry at the University of Oxford, Tutorial Fellow in Physical Chemistry at Hertford College, and past President of the Faraday Division of the Royal Society of Chemistry. In collaboration with professor Mark Brouard and others, she created the PImMS (Pixel Imaging Mass Spectrometry) sensor, used for time-of-flight particle imaging and recently featured in the Royal Society of Chemistrys Research Frontiers report. She is co-founder of the spin-out company Oxford HighQ, which is developing next-generation chemical and nanoparticle sensors based on optical microcavity technology. Vallances research spans chemical reaction dynamics, optical microcavity spectroscopy, and applications of spectroscopy and imaging in medical diagnostics. She is also an accomplished musician and triathlete. | 0 | Theoretical and Fundamental Chemistry |
Terpenes and terpenoids of many kinds are found in resinous plants such as the conifers. They are aromatic and serve to repel herbivores. Their scent makes them useful in essential oils, whether for perfumes such as rose and lavender, or for aromatherapy. Some have had medicinal uses: thymol is an antiseptic and was once used as a vermifuge (anti-worm medicine). | 1 | Applied and Interdisciplinary Chemistry |
Thermometric titrations employing sodium salts of ethylenediaminetetra-acetic acid (EDTA) have been demonstrated for the determination of a range of metal ions. Reaction enthalpies are modest, so titrations are normally carried out with titrant concentrations of 1 mol/L. This necessitates the use of the tetra-sodium salt of EDTA rather than the more common di-sodium salt which is saturated at a concentration of only approximately 0.25 mol/L.
An excellent application is the sequential determination of calcium and magnesium. Although calcium reacts exothermically with EDTA (heat of chelation ~-23.4 kJ/mol), magnesium reacts endothermically with a heat of chelation of ~+20.1 kJ/mol. This is illustrated in the titration plot of EDTA with calcium and magnesium in sea water (Figure 14). Following the solution temperature curve, the breakpoint for the calcium content (red-tagged endpoint) is followed by a region of modest temperature rise due to competition between the heats of dilution of the titrant with the solution, and the endothermic reaction of Mg and EDTA. The breakpoint for the consumption of Mg (blue-tagged endpoint) by EDTA is revealed by upswing in temperature caused purely by the heat of dilution.
Direct EDTA titrations with metal ions are possible when reaction kinetics are fast, for example zinc, copper, calcium and magnesium. However, with slower reaction kinetics such as those exhibited by cobalt and nickel, back-titrations are used. Titrations for cobalt and nickel are carried out in an ammoniacal environment; buffered with ammonia:ammonium chloride solution. An excess of EDTA is added, and is back-titrated with Cu(II) solution. It is postulated that the breakpoint is revealed by the difference in reaction enthalpies between the formation of the Cu-EDTA complex, and that for the formation of the Cu-amine complex.
A catalyzed endpoint procedure to determine trace amounts of metal ions in solution (down to approximately 10 mg/L) employs 0.01 mol/L EDTA. This has been applied to the determination of low level Cu(II) in specialized plating baths, and to the determination of total hardness in water. The reaction enthalpies of EDTA with most metal ions are often quite low, and typically titrant concentrations around 1 mol/L are employed with commensurately high amounts of titrand in order to obtain sharp, reproducible endpoints. Using a catalytically indicated endpoint, very low EDTA titrant concentrations can be used. A back-titration is used. An excess of EDTA solution is added. The excess of EDTA is back-titrated with a suitable metal ion such as Mn or Cu. At the endpoint, the first excess of metal ion catalyzes a strongly exothermic reaction between a polyhydric phenol (such as resorcinol) and hydrogen peroxide. | 0 | Theoretical and Fundamental Chemistry |
Imidoyl halides are synthesized by combining amides and halogenating agents. The structure of the carboxylic acid amides plays a role in the outcome of the synthesis. Imidoyl chloride can be prepared by treating a monosubstituted carboxylic acid amide with phosgene.
:RC(O)NHR’ + COCl → RC(NR’)Cl + HCl + CO
Thionyl chloride is also used.
Imidoyl chlorides are generally colorless liquids or low-melting solids that are sensitive to both heat and especially moisture. In their IR spectra these compounds exhibit a characteristic ν band near 1650–1689 cm. Although both the syn and anti configurations are possible, most imidoyl chlorides adopt the anti configuration. | 0 | Theoretical and Fundamental Chemistry |
Carbaminohemoglobin is a compound that bind to hemoglobin in the blood. Hemoglobin is a protein that is found in red blood cells and it Is crucial for transporting oxygen from the lungs to tissues and organs. Hemoglobin also plays an important role in transporting carbon dioxide from the tissues back to the lungs for exhalation.
The structure of carbaminohemoglobin can be described as the binding of carbon dioxide to the amino groups of the global chains of hemoglobin. The process of carbon dioxide binding to hemoglobin is generally known as carbamino formation. This is the source from where the protein gets its name, as it is a combination of carbamino and hemoglobin. | 1 | Applied and Interdisciplinary Chemistry |
Two families of naturally occurring products feature the diazo group: kinamycin and lomaiviticin. These molecules are DNA-intercalators, with diazo functionality as their "warheads". Loss of N, induced reductively, generates a DNA-cleaving fluorenyl radical. | 0 | Theoretical and Fundamental Chemistry |
Ipaktschi is known for the use of ethereal solutions of lithium perchlorate as a medium for organic reactions and organometallic chemistry. | 0 | Theoretical and Fundamental Chemistry |
In engineering science and other technical aspects, the term galling is widespread. The influence of acceleration in the contact zone between materials has been mathematically described and correlated to the exhibited friction mechanism found in the tracks during empiric observations of the galling phenomenon. Due to problems with previous incompatible definitions and test methods, better means of measurements in coordination with a greater understanding of the involved frictional mechanisms have led to the attempt to standardize or redefine the term galling to enable a more generalized use.
ASTM International has formulated and established a common definition for the technical aspect of the galling phenomenon in the ASTM G40 standard: "Galling is a form of surface damage arising between sliding solids, distinguished by microscopic, usually localized, roughening and creation of protrusions (e.g., lumps) above the original surface".
When two metallic surfaces are pressed against each other, the initial interaction and the mating points are the asperities, or high points, found on each surface. An asperity may penetrate the opposing surface if there is a converging contact and relative movement. The contact between the surfaces initiates friction or plastic deformation and induces pressure and energy in a small area called the contact zone.
The elevation in pressure increases the energy density and heat level within the deformed area. This leads to greater adhesion between the surfaces, which initiates the material transfer, galling build-up, lump growth, and creation of protrusions above the original surface.
If the lump (or protrusion of transferred material to one surface) grows to a height of several micrometers, it may penetrate the opposing surface oxide-layer and cause damage to the underlying material. Damage in the bulk material is a prerequisite for plastic flow found in the deformed volume surrounding the lump. The geometry and speed of the lump define how the flowing material will be transported, accelerated, and decelerated around the lump. This material flow is critical when defining the contact pressure, energy density, and developed temperature during sliding. The mathematical function describing acceleration and deceleration of flowing material is thereby defined by the geometrical constraints, deduced or given by the lump's surface contour.
If the right conditions are met, such as geometric constraints of the lump, an accumulation of energy can cause a clear change in the material's contact and plastic behavior, increasing the friction force required for adhesion and further movement.
In sliding friction, increased compressive stress is proportionally equal to a rise in potential energy and temperature within the contact zone. The energy accumulation during sliding can reduce energy loss from the contact zone due to a small surface area on the surface boundary, thus, low heat conductivity. Another reason is the energy continuously forced into the metals, which is a product of acceleration and pressure. In cooperation, these mechanisms allow constant energy accumulation, causing increased energy density and temperature in the contact zone during sliding.
The process and contact can be compared to cold welding or friction welding because cold welding is not truly cold, and the fusing points exhibit an increase in temperature and energy density derived from applied pressure and plastic deformation in the contact zone. | 0 | Theoretical and Fundamental Chemistry |
A DTA consists of a sample holder, thermocouples, sample containers and a ceramic or metallic block; a furnace; a temperature programmer; and a recording system. The key feature is the existence of two thermocouples connected to a voltmeter. One thermocouple is placed in an inert material such as AlO, while the other is placed in a sample of the material under study. As the temperature is increased, there will be a brief deflection of the voltmeter if the sample is undergoing a phase transition. This occurs because the input of heat will raise the temperature of the inert substance, but be incorporated as latent heat in the material changing phase. It consist of inert environment with inert gases which will not react with sample and reference. Generally helium or argon is used as inert gas. | 0 | Theoretical and Fundamental Chemistry |
miR-324-5p first appeared in literature in a paper published by John Kim et al. in early 2004 that identified 32 entirely new miRNAs from cultured rat cortical neurons using miRNA cloning and RNA analysis. The miRNA quickly gained traction in scientific literature, appearing in articles about the evolutionary conservation of microRNAs, HIV, cancer, and other topics within a few years. Today, the functions and roles of miR-324-5p are still not yet fully characterized. | 1 | Applied and Interdisciplinary Chemistry |
The reddish color typical of tholins is characteristic of many Trans-Neptunian objects, including plutinos in the outer Solar System such as 28978 Ixion. Spectral reflectances of Centaurs also suggest the presence of tholins on their surfaces. The New Horizons exploration of the classical Kuiper belt object 486958 Arrokoth revealed reddish color at its surface, suggestive of tholins. | 0 | Theoretical and Fundamental Chemistry |
Adhesion GPCRs are found in fungi. They are believed to have evolved from the cAMP receptor family, arising approximately 1275 million years ago before the split of Unikonts from a common ancestor. Several fungi have novel adhesion GPCRs that have both short, 2–66 amino acid residues, and long, 312–4202 amino acid residues. Analysis of fungi showed that there were no secretin receptor family GPCRs, which suggests that they evolved from adhesion GPCRs in a later organism.
Genome analysis of the Teleost Takifugu rubripes has revealed that it has only two adhesion GPCRs that showed homology to Ig-hepta/GPR116. While the Fugu genome is relatively compact and limited with the number of adhesion GPCRs, Tetraodon nigroviridis, another species of puffer fish, has considerably more, totaling 29 adhesion GPCRs. | 1 | Applied and Interdisciplinary Chemistry |
Frémy's salt is prepared from hydroxylaminedisulfonic acid. Oxidation of the conjugate base gives the purple dianion:
:HON(SOH) → [HON(SO)] + 2 H
:2 [HON(SO)] + PbO → 2 [ON(SO)] + PbO + HO
The synthesis can be performed by combining nitrite and bisulfite to give the hydroxylaminedisulfonate. Oxidation is typically conducted at low-temperature, either chemically or by electrolysis.
Other reactions:
: HNO + 2 → + HO
: 3 + + H → 3 + MnO + 2 HO
: 2 + 4 K → K[ON(SO)] | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, umpolung () or polarity inversion is the chemical modification of a functional group with the aim of the reversal of polarity of that group. This modification allows secondary reactions of this functional group that would otherwise not be possible. The concept was introduced by D. Seebach (hence the German word for reversed polarity) and E.J. Corey. Polarity analysis during retrosynthetic analysis tells a chemist when umpolung tactics are required to synthesize a target molecule. | 0 | Theoretical and Fundamental Chemistry |
Many methods have been developed for the restriction of microbial corrosion. The primary challenge has been finding ways to prevent or stop microbial growth without negatively impacting the surrounding environment. The list below provides an overview of some of the tactics that have been used or that are in development.
* Using biocide (any chemical that inhibits life) to kill microorganisms. Because biofilms are so resistant, a lot of biocide must be used. This is expensive, has negative effects on the surrounding environment, and can actually cause more corrosion of the surface due to its toxicity. Biocides and other chemical treatments against microbes also tend to be dangerous for the people preparing and applying them.
Rao and Mulky developed an extensive list of methods to limit the growth of microbes and therefore microbial corrosion.
* Plant products could aid in restricting microbial growth. These would be biodegradable and safe for the people applying them, but have not yet been widely tested.
* Surfactants, specifically ones generated by organisms as secondary metabolites. They’re useful because they get between the corrosive liquid and the surface and keep them apart.
* Putting a superhydrophobic coating on a surface. This keeps a biofilm from being able to develop, but is sensitive and can easily lose its superhydrophobic qualities.
* Using self-healing surfaces can prevent corrosion in cracks or faults. This could be used with a superhydrophobic surface, to mitigate its sensitivity.
* Using hydrophilic surfaces to create a region that deters the development of proteins into a film covering a surface.
* Using synthetically-created substances that deter corrosion because of their chemical structures. This may have a smaller negative effect on the environment than other options.
* Using biofilms that are grown intentionally to inhibit microbial corrosion. This is done by growing a biofilm on a surface made of a bacteria that can release compounds that kill other microbes and that prevent corrosion.
* Using essential oils. The effectiveness of essential oils against microbial corrosion has not been widely tested.
* Coating a surface with various nanomaterials or ozone to prevent microbial corrosion. | 1 | Applied and Interdisciplinary Chemistry |
It is generally believed that the mechanical and other properties of the crystal are also pertinent to the subject matter, and that crystal morphology provides the missing link between growth kinetics and physical properties. The necessary thermodynamic apparatus was provided by Josiah Willard Gibbs study of heterogeneous equilibrium. He provided a clear definition of surface energy, by which the concept of surface tension is made applicable to solids as well as liquids. He also appreciated that an anisotropic surface free energy implied a non-spherical equilibrium shape, which should be thermodynamically defined as the shape which minimizes the total surface free energy'.
It may be instructional to note that whisker growth provides the link between the mechanical phenomenon of high strength in whiskers and the various growth mechanisms which are responsible for their fibrous morphologies. (Prior to the discovery of carbon nanotubes, single-crystal whiskers had the highest tensile strength of any materials known). Some mechanisms produce defect-free whiskers, while others may have single screw dislocations along the main axis of growth—producing high strength whiskers.
The mechanism behind whisker growth is not well understood, but seems to be encouraged by compressive mechanical stresses including mechanically induced stresses, stresses induced by diffusion of different elements, and thermally induced stresses. Metal whiskers differ from metallic dendrites in several respects. Dendrites are fern-shaped like the branches of a tree, and grow across the surface of the metal. In contrast, whiskers are fibrous and project at a right angle to the surface of growth, or substrate. | 0 | Theoretical and Fundamental Chemistry |
DNA circularization depends on both the axial (bending) stiffness and torsional (rotational) stiffness of the molecule. For a DNA molecule to successfully circularize it must be long enough to easily bend into the full circle and must have the correct number of bases so the ends are in the correct rotation to allow bonding to occur. The optimum length for circularization of DNA is around 400 base pairs (136 nm), with an integral number of turns of the DNA helix, i.e., multiples of 10.4 base pairs. Having a non integral number of turns presents a significant energy barrier for circularization, for example a 10.4 x 30 = 312 base pair molecule will circularize hundreds of times faster than 10.4 x 30.5 ≈ 317 base pair molecule.
The bending of short circularized DNA segments is non-uniform. Rather, for circularized DNA segments less than the persistence length, DNA bending is localised to 1-2 kinks that form preferentially in AT-rich segments. If a nick is present, bending will be localised to the nick site. | 0 | Theoretical and Fundamental Chemistry |
This is the conclusion of the previous section: in a constant magnetic field B along z axis the transverse magnetization M rotates around this axis in clockwise direction with angular frequency ω. If the observer were rotating around the same axis in clockwise direction with angular frequency Ω, M it would appear to her or him rotating with angular frequency ω - Ω. Specifically, if the observer were rotating around the same axis in
clockwise direction with angular frequency ω, the transverse magnetization M would appear to her or him stationary.
This can be expressed mathematically in the following way:
* Let (x, y, z) the Cartesian coordinate system of the laboratory (or stationary) frame of reference, and
* (x′, y′, z′) = (x′, y′, z) be a Cartesian coordinate system that is rotating around the z axis of the laboratory frame of reference with angular frequency Ω. This is called the rotating frame of reference. Physical variables in this frame of reference will be denoted by a prime.
Obviously:
What is M′(t)? Expressing the argument at the beginning of this section in a mathematical way: | 0 | Theoretical and Fundamental Chemistry |
The SCCmec found in methicillin-resistant Staphylococcus aureus likely originated in coagulase-negative staphylococcal species and was acquired by S. aureus.
Staphylococcal strains isolated from pig farms were found to carry several different types of SCCmec, suggesting that they may serve as a reservoir of these elements. | 1 | Applied and Interdisciplinary Chemistry |
Another type of cellular glycan is the glycosaminoglycans (GAGs). These comprise 2-aminosugars linked in an alternating fashion with uronic acids, and include polymers such as heparin, heparan sulfate, chondroitin, keratan and dermatan. Some glycosaminoglycans, such as heparan sulfate, are found attached to the cell surface, where they are linked through a tetrasacharide linker via a xylosyl residue to a protein (forming a glycoprotein or proteoglycan). | 0 | Theoretical and Fundamental Chemistry |
Single-crystal X-ray crystallography has been used to determine its structure; as can be predicted by VSEPR theory, it adopts a T-shaped geometry about the central iodine atom. | 0 | Theoretical and Fundamental Chemistry |
Analysis of molecular variance (AMOVA), is a statistical model for the molecular algorithm in a single species, typically biological. The name and model are inspired by ANOVA. The method was developed by Laurent Excoffier, Peter Smouse and Joseph Quattro at Rutgers University in 1992.
Since developing AMOVA, Excoffier has written a program for running such analyses. This program, which runs on Windows, is called Arlequin and is freely available on Excoffier's website. There are also implementations in R language in the ade4 and the pegas packages, both available on CRAN (Comprehensive R Archive Network). Another implementation is in Info-Gen, which also runs on Windows. The student version is free and fully functional. Native language of the application is Spanish but an English version is also available.
An additional free statistical package, GenAlEx, is geared toward teaching as well as research and allows for complex genetic analyses to be employed and compared within the commonly used Microsoft Excel interface. This software allows for calculation of analyses such as AMOVA, as well as comparisons with other types of closely related statistics including F-statistics and Shannon's index, and more. | 1 | Applied and Interdisciplinary Chemistry |
where
*h = convection heat transfer coefficient
*G = mass flow rate of the fluid
* ρ = density of the fluid
*c = specific heat of the fluid
*u = velocity of the fluid
It can also be represented in terms of the fluid's Nusselt, Reynolds, and Prandtl numbers:
where
* Nu is the Nusselt number;
* Re is the Reynolds number;
* Pr is the Prandtl number.
The Stanton number arises in the consideration of the geometric similarity of the momentum boundary layer and the thermal boundary layer, where it can be used to express a relationship between the shear force at the wall (due to viscous drag) and the total heat transfer at the wall (due to thermal diffusivity). | 1 | Applied and Interdisciplinary Chemistry |
Radiation therapy (RT) is in itself painless. Many low-dose palliative treatments (for example, radiation therapy to bony metastases) cause minimal or no side effects, although short-term pain flare-up can be experienced in the days following treatment due to oedema compressing nerves in the treated area. Higher doses can cause varying side effects during treatment (acute side effects), in the months or years following treatment (long-term side effects), or after re-treatment (cumulative side effects). The nature, severity, and longevity of side effects depends on the organs that receive the radiation, the treatment itself (type of radiation, dose, fractionation, concurrent chemotherapy), and the patient. Serious radiation complications may occur in 5% of RT cases. Acute (near immediate) or sub-acute (2 to 3 months post RT) radiation side effects may develop after 50 Gy RT dosing. Late or delayed radiation injury (6 months to decades) may develop after 65 Gy.
Most side effects are predictable and expected. Side effects from radiation are usually limited to the area of the patient's body that is under treatment. Side effects are dose-dependent; for example, higher doses of head and neck radiation can be associated with cardiovascular complications, thyroid dysfunction, and pituitary axis dysfunction. Modern radiation therapy aims to reduce side effects to a minimum and to help the patient understand and deal with side effects that are unavoidable.
The main side effects reported are fatigue and skin irritation, like a mild to moderate sun burn. The fatigue often sets in during the middle of a course of treatment and can last for weeks after treatment ends. The irritated skin will heal, but may not be as elastic as it was before. | 0 | Theoretical and Fundamental Chemistry |
When the mud layer is exposed at the tidal fringe, mudflats result affording a unique ecotone that affords numerous shorebird species a safe feeding and resting habitat. Because the muds function much like quicksand, heavier mammalian predators not only cannot gain traction for pursuit, but would actually become trapped in the sinking muds. The muds are also an important substrate for primary marsh productivity including eelgrass, cordgrass and pickleweed. Furthermore, they are home to a large variety of molluscs and estuarine arthropods. Richardson Bay, for example, exposes one third of its areal extent as mudflat at low tide, which hosts a productive eelgrass expanse and also a large shorebird community.
Mammals such as the Harbor seal may use mudflats to haul out of estuary waters; however, larger mammals such as humpback whales may become accidentally stranded at low tides. Note that normally humpback whales do not frequent estuaries containing mudflats, but at least one errant whale, publicized by the media as Humphrey the humpback whale, became stuck on a mudflat in San Francisco Bay at Sierra Point in Brisbane, California. | 1 | Applied and Interdisciplinary Chemistry |
In chemical kinetics, isosbestic points are used as reference points in the study of reaction rates, as the absorbance at those wavelengths remains constant throughout the whole reaction.
Isosbestic points are used in medicine in a laboratory technique called oximetry to determine hemoglobin concentration, regardless of its saturation. Oxyhaemoglobin and deoxyhaemoglobin have (not exclusively) isosbestic points at 586 nm and near 808 nm.
Isosbestic points are also used in clinical chemistry, as a quality assurance method, to verify the accuracy in the wavelength of a spectrophotometer. This is done by measuring the spectra of a standard solution at two different pH conditions (above and below the pK of the substance). The standards used include potassium dichromate (isosbestic points at 339 and 445 nm), bromothymol blue (325 and 498 nm) and congo red (541 nm). The wavelength of the isosbestic point determined does not depend on the concentration of the substance used, and so it becomes a very reliable reference.
One example of the use of isosbestic points in organic synthesis is seen in the photochemical A/D-corrin cycloisomerization ring closure reaction, which was the key step in the Eschenmoser / ETH Zürich vitamin B total synthesis. The isosbestic points provide proof for a direct conversion of the seco-corrin complex to the metal-free corrin ligand without intermediary or side products (within the detection limits of UV/VIS spectroscopy). | 0 | Theoretical and Fundamental Chemistry |
It was first produced in 1878 by the German chemists August Michaelis (1847–1916) and Wilhelm La Coste (1854–1885). It is prepared by the reduction of diphenylarsinic acid with sulfur dioxide. An idealized equation is shown:
:PhAsOH + SO + HCl → PhAsCl + HSO
The process adopted by Edgewood Arsenal, the "sodium process", for the production of DA for chemical warfare purposes employed a reaction between chlorobenzene and arsenic trichloride in the presence of sodium.
The German process, used in the first war, applied at Hochstam-Main, used the Sandmeyer reaction between phenyldiazonium chloride and sodium arsenite. The acidified product was reduced and then neutralized. The salt was condensed again by the Sandmeyer reaction and reduced again, the final product was then acidified, resulting in DA.
The structure consists of pyramidal As centre. The As-Cl distance is 2.26 A and the Cl-As-C and C-As-C angles are 96 and 105°, respectively. | 1 | Applied and Interdisciplinary Chemistry |
Ensuring quality of sprayers by testing and setting of standards for application equipment is important to ensure users get value for money. Since most equipment uses various hydraulic nozzles, various initiatives have attempted to classify spray quality, starting with the BCPC system. | 1 | Applied and Interdisciplinary Chemistry |
Glycogenin is the initiator of the glycogen biosynthesis. This protein is a glycosyl transferase that have the ability of autoglycosilation using UDP-glucose, which helps in the growth of itself until forming an oligosaccharide made by 8 glucoses. Glycogenin is an oligomer, and it's capable of interacting with several proteins. In recent years, a family of proteins has been identified, the GNIPs (glycogenin-interacting protein), that interacts with glycogenin stimulating its autoglycolsilation activity. | 1 | Applied and Interdisciplinary Chemistry |
Thermal radiation is a phenomenon that can burn skin and ignite flammable materials. The time to a damage from exposure to thermal radiation is a function of the rate of delivery of the heat. Radiative heat flux and effects are given as follows: | 0 | Theoretical and Fundamental Chemistry |
Carbaminohemoglobin interacts with carbon dioxide in a process known as respiratory gas exchange. The interaction involves the binding of carbon dioxide to hemoglobin. Carbon dioxide binds to the protein chains of hemoglobin. The ability of hemoglobin to bind to both oxygen and carbon dioxide molecules is what makes it an important protein to the respiratory system in respiratory gas exchange.
The interactions between carbon dioxide and hemoglobin helps in the transport of carbon dioxide from the tissues to the lungs for eliminations. When carbon dioxide is transported from the tissues, it is produced as a waste product of a set of reactions known as cellular metabolism. Most importantly, the binding of carbon dioxide to hemoglobin plays a part in the buffering of blood pH by preventing the drop of pH due to the production of carbonic acid.
Although, the carbaminohemoglobin protein interacts with another protein (like hemoglobin) found in red blood cells, this interaction only takes place in the bloodstream and its products can be expelled. Carbaminohemoglobin does not interact with DNA since DNA is a molecule that is found in cell nucleus and its function is to carry genetic information. | 1 | Applied and Interdisciplinary Chemistry |
R.T. Sanderson has also noted the relationship between Mulliken electronegativity and atomic size, and has proposed a method of calculation based on the reciprocal of the atomic volume. With a knowledge of bond lengths, Sandersons model allows the estimation of bond energies in a wide range of compounds. Sandersons model has also been used to calculate molecular geometry, s-electron energy, NMR spin-spin coupling constants and other parameters for organic compounds. This work underlies the concept of electronegativity equalization, which suggests that electrons distribute themselves around a molecule to minimize or to equalize the Mulliken electronegativity. This behavior is analogous to the equalization of chemical potential in macroscopic thermodynamics. | 0 | Theoretical and Fundamental Chemistry |
RNA interference (also called "RNA-mediated interference", abbreviated RNAi) is a mechanism for RNA-guided regulation of gene expression in which double-stranded ribonucleic acid inhibits the expression of genes with complementary nucleotide sequences. | 1 | Applied and Interdisciplinary Chemistry |
When depositing particles repel each other, the deposition will stop by the time when enough particles have deposited. At one point, such a surface layer will repel any particles that may still make attempts to deposit. The surface is said to be saturated or blocked by the deposited particles. The blocking process can be described by the following equation
where is the surface blocking function. When there are no deposited particles, and . With increasing number density of deposited particles, the blocking function decreases. The surface saturates at and . The simplest blocking function is
and it is referred to as the Langmuir blocking function, as it is related to the Langmuir isotherm.
The blocking process has been studied in detail in terms of the random sequential adsorption (RSA) model. The simplest RSA model related to deposition of spherical particles considers irreversible adsorption of circular disks. One disk after another is placed randomly at a surface. Once a disk is placed, it sticks at the same spot, and cannot be removed. When an attempt to deposit a disk would result in an overlap with an already deposited disk, this attempt is rejected. Within this model, the surface is initially filled rapidly, but the more one approaches saturation the slower the surface is being filled. Within the RSA model, saturation is referred to as jamming. For circular disks, jamming occurs at a coverage of 0.547. When the depositing particles are polydisperse, much higher surface coverage can be reached, since the small particles will be able to deposit into the holes in between the larger deposited particles. On the other hand, rod like particles may lead to much smaller coverage, since a few misaligned rods may block a large portion of the surface.
Since the repulsion between particles in aqueous suspensions originates from electric double layer forces, the presence of salt has an important effect on surface blocking. For small particles and low salt, the diffuse layer will extend far beyond the particle, and thus create an exclusion zone around it. Therefore, the surface will be blocked at a much lower coverage than what would be expected based on the RSA model. At higher salt and for larger particles, this effect is less important, and the deposition can be well described by the RSA model. | 0 | Theoretical and Fundamental Chemistry |
The journal is abstracted and indexed in several databases including:
* Science Citation Index
* Web of Science
* Polymer Contents
According to the Journal Citation Reports, the journal has a 2022 impact factor of 11.2. | 0 | Theoretical and Fundamental Chemistry |
Recognition of its prevalence and consequences has led to governments and non-government organizations promoting vitamin A fortification of foods and creating programs that administer large bolus-size oral doses of vitamin A to young children every four to six months. In 2008, the World Health Organization estimated that vitamin A supplementation over a decade in 40 countries averted 1.25 million deaths due to vitamin A deficiency. A Cochrane review reported that vitamin A supplementation is associated with a clinically meaningful reduction in morbidity and mortality in children ages six month to five years of age. All-cause mortality was reduced by 14%, and incidences of diarrhea by 12%. However, a Cochrane review by the same group concluded there was insufficient evidence to recommend blanket vitamin A supplementation for infants one to six months of age, as it did not reduce infant mortality or morbidity. | 1 | Applied and Interdisciplinary Chemistry |
The triple-alpha steps are strongly dependent on the temperature and density of the stellar material. The power released by the reaction is approximately proportional to the temperature to the 40th power, and the density squared. In contrast, the proton–proton chain reaction produces energy at a rate proportional to the fourth power of temperature, the CNO cycle at about the 17th power of the temperature, and both are linearly proportional to the density. This strong temperature dependence has consequences for the late stage of stellar evolution, the red-giant stage.
For lower mass stars on the red-giant branch, the helium accumulating in the core is prevented from further collapse only by electron degeneracy pressure. The entire degenerate core is at the same temperature and pressure, so when its density becomes high enough, fusion via the triple-alpha process rate starts throughout the core. The core is unable to expand in response to the increased energy production until the pressure is high enough to lift the degeneracy. As a consequence, the temperature increases, causing an increased reaction rate in a positive feedback cycle that becomes a runaway reaction. This process, known as the helium flash, lasts a matter of seconds but burns 60–80% of the helium in the core. During the core flash, the star's energy production can reach approximately 10 solar luminosities which is comparable to the luminosity of a whole galaxy, although no effects will be immediately observed at the surface, as the whole energy is used up to lift the core from the degenerate to normal, gaseous state. Since the core is no longer degenerate, hydrostatic equilibrium is once more established and the star begins to "burn" helium at its core and hydrogen in a spherical layer above the core. The star enters a steady helium-burning phase which lasts about 10% of the time it spent on the main sequence (the Sun is expected to burn helium at its core for about a billion years after the helium flash).
For higher mass stars, carbon collects in the core, displacing the helium to a surrounding shell where helium burning occurs. In this helium shell, the pressures are lower and the mass is not supported by electron degeneracy. Thus, as opposed to the center of the star, the shell is able to expand in response to increased thermal pressure in the helium shell. Expansion cools this layer and slows the reaction, causing the star to contract again. This process continues cyclically, and stars undergoing this process will have periodically variable radius and power production. These stars will also lose material from their outer layers as they expand and contract. | 0 | Theoretical and Fundamental Chemistry |
Wet etching of GaAs industrially uses an oxidizing agent such as hydrogen peroxide or bromine water, and the same strategy has been described in a patent relating to processing scrap components containing GaAs where the is complexed with a hydroxamic acid ("HA"), for example:
:GaAs + + "HA" → "GaA" complex + + 4
This reaction produces arsenic acid. | 0 | Theoretical and Fundamental Chemistry |
Much organic carbon retained in many agricultural areas worldwide has been severely depleted due to intensive farming practices. Since the 1850s, a large proportion of the world's grasslands have been tilled and converted to croplands, allowing the rapid oxidation of large quantities of soil organic carbon. Methods that significantly enhance carbon sequestration in soil include no-till farming, residue mulching, cover cropping, and crop rotation, all of which are more widely used in organic farming than in conventional farming. | 0 | Theoretical and Fundamental Chemistry |
The department employs 34 full-time Professors and 11 Emeritus Professors including:
* David Procter, Head of Department, and Professor of Organic Chemistry.
* Nikolas Kaltsoyannis, Ex-Head of School, and Professor of Computational and Theoretical Chemistry.
* Richard Winpenny, Ex-Head of School, and Professor of Inorganic Chemistry.
* David Leigh, FRS, Sir Samuel Hall Chair of Chemistry
* Gareth A. Morris, FRS, Professor of Physical Chemistry | 1 | Applied and Interdisciplinary Chemistry |
In astronomy and atomic physics, doubly ionized oxygen is the ion O (O III in spectroscopic notation). Its emission forbidden lines in the visible spectrum fall primarily at the wavelength 500.7 nm, and secondarily at 495.9 nm. Before spectra of oxygen ions became known, these lines once led to a spurious identification of the substance as a new chemical element. Concentrated levels of O III are found in diffuse and planetary nebulae. Consequently, narrow band-pass filters that isolate the 500.7 nm and 495.9 nm wavelengths of light, that correspond to green-turquoise-cyan spectral colors, are useful in observing these objects, causing them to appear at higher contrast against the filtered and consequently blacker background of space (and possibly light-polluted terrestrial atmosphere) where the frequencies of [O III] are much less pronounced.
These emission lines were first discovered in the spectra of planetary nebulae in the 1860s. At that time, they were thought to be due to a new element which was named nebulium. In 1927, Ira Sprague Bowen published the current explanation identifying their source as doubly ionized oxygen.
Other transitions include the forbidden 88.4 μm and 51.8 μm transitions in the far infrared region.
Permitted lines of O III lie in the middle ultraviolet band and are hence inaccessible to terrestrial astronomy. | 0 | Theoretical and Fundamental Chemistry |
The Journal of Physical Organic Chemistry is a monthly peer-reviewed scientific journal, published since 1988 by John Wiley & Sons. It covers research in physical organic chemistry in its broadest sense and is available both online and in print. The current editor-in-chief is Rik Tykwinski (University of Alberta). | 0 | Theoretical and Fundamental Chemistry |
At the spinal cord, cannabinoids suppress noxious-stimulus-evoked responses of neurons in the dorsal horn, possibly by modulating descending noradrenaline input from the brainstem. As many of these fibers are primarily GABAergic, cannabinoid stimulation in the spinal column results in disinhibition that should increase noradrenaline release and attenuation of noxious-stimuli-processing in the periphery and dorsal root ganglion.
The endocannabinoid most researched in pain is palmitoylethanolamide. Palmitoylethanolamide is a fatty amine related to anandamide, but saturated and although initially it was thought that palmitoylethanolamide would bind to the CB1 and the CB2 receptor, later it was found that the most important receptors are the PPAR-alpha receptor, the TRPV receptor and the GPR55 receptor. Palmitoylethanolamide has been evaluated for its analgesic actions in a great variety of pain indications and found to be safe and effective.
Modulation of the endocannabinoid system by metabolism to N-arachidinoyl-phenolamine (AM404), an endogenous cannabinoid neurotransmitter, has been discovered to be one mechanism for analgesia by acetaminophen (paracetamol).
Endocannabinoids are involved in placebo induced analgesia responses. | 1 | Applied and Interdisciplinary Chemistry |
Casein kinase 1 epsilon has been suggested to play a role in phosphorylation of Disheveled in the Wnt signaling pathway. Casein kinase 1 alpha (CK1α) binds to and phosphorylates β‑catenin
In plants the phosphorylation of protein Jade-1 is regulated by casein kinase 1. In humans there are three casein kinase 1 gamma enzymes.
Xenopus casein kinase 1 gamma (CK1gamma) is associated with the cell membrane and binds to LRP. CK1gamma was found to be needed for Wnt signaling through LRP, and is both necessary and sufficient to transduce LRP6 signaling in vertebrates and Drosophila cells. Wnt binding to LRP causes a rapid increase in phosphorylation of the cytoplasmic domain of LRP by CK1gamma. Phosphorylation of LRP6 by CK1gamma promotes binding of axin to LRP and activation of the Wnt signaling pathway. | 1 | Applied and Interdisciplinary Chemistry |
Nowadays it is possible to solve the classical Streeter–Phelps equation numerically by use of computers. The differential equations are solved by integration. | 1 | Applied and Interdisciplinary Chemistry |
The potential of mean force is usually applied in the Boltzmann inversion method as a first guess for the effective pair interaction potential that ought to reproduce the correct radial distribution function in a mesoscopic simulation.
Lemkul et al. have used steered molecular dynamics simulations to calculate the potential of mean force to assess the stability of Alzheimer's amyloid protofibrils. Gosai et al. have also used umbrella sampling simulations to show that potential of mean force decreases between thrombin and its aptamer (a protein-ligand complex) under the effect of electrical fields. | 0 | Theoretical and Fundamental Chemistry |
Isaac Asimov, in a 1963 humorous essay entitled "You, too, can speak Gaelic", reprinted in the anthology Adding a Dimension among others, traces the etymology of each component of the chemical name "para-di-methyl-amino-benz-alde-hyde" (e.g. the syllable "-benz-" ultimately derives from the Arabic lubān jāwī (لبان جاوي, "frankincense from Java"). Asimov points out that the name can be pronounced to the tune of the familiar jig "The Irish Washerwoman", and relates an anecdote in which a receptionist of Irish descent, hearing him singing the syllables thus, mistook them for the original Gaelic words to the jig. This essay inspired Jack Carrolls 1963 filk song "The Chemists Drinking Song," (NESFA Hymnal Vol. 2 2nd ed. p. 65) set to the tune of that jig, which begins "Paradimethylaminobenzaldehyde, / Sodium citrate, ammonium cyanide, / ..." | 0 | Theoretical and Fundamental Chemistry |
In welding, equivalent carbon content (C.E) is used to understand how the different alloying elements affect hardness of the steel being welded. This is then directly related to hydrogen-induced cold cracking, which is the most common weld defect for steel, thus it is most commonly used to determine weldability. Higher concentrations of carbon and other alloying elements such as manganese, chromium, silicon, molybdenum, vanadium, copper, and nickel tend to increase hardness and decrease weldability. Each of these elements tends to influence the hardness and weldability of the steel to different magnitudes, however, making a method of comparison necessary to judge the difference in hardness between two alloys made of different alloying elements. There are two commonly used formulas for calculating the equivalent carbon content. One is from the American Welding Society (AWS) and recommended for structural steels and the other is the formula based on the International Institute of Welding (IIW).
The AWS states that for an equivalent carbon content above 0.40% there is a potential for cracking in the heat-affected zone (HAZ) on flame cut edges and welds. However, structural engineering standards rarely use CE, but rather limit the maximum percentage of certain alloying elements. This practice started before the CE concept existed, so just continues to be used. This has led to issues because certain high strength steels are now being used that have a CE higher than 0.50% that have brittle failures.
The other and most popular formula is the Dearden and O'Neill formula, which was adopted by IIW in 1967. This formula has been found suitable for predicting hardenability in a large range of commonly used plain carbon and carbon-manganese steels, but not to microalloyed high-strength low-alloy steels or low-alloy Cr-Mo steels. The formula is defined as follows:
For this equation the weldability based on a range of CE values can be defined as follows:
The Japanese Welding Engineering Society adopted the critical metal parameter (Pcm) for weld cracking, which was based on the work from Ito and Bessyo, is:
If some of the values are not available, the following formula is sometimes used:
The carbon equivalent is a measure of the tendency of the weld to form martensite on cooling and to suffer brittle fracture. When the carbon equivalent is between 0.40 and 0.60 weld preheat may be necessary. When the carbon equivalent is above 0.60, preheat is necessary, postheat may be necessary.
The following carbon equivalent formula is used to determine if a spot weld will fail in high-strength low-alloy steel due to excessive hardenability:
Where UTS is the ultimate tensile strength in ksi and h is the strip thickness in inches. A CE value of 0.3 or less is considered safe.
A special carbon equivalent was developed by Yurioka, which could determine the critical time in seconds Δt for the formation of martensitic in the Heat Affected Zone (HAZ) in low-carbon alloy steels. The equation is given as:
where:
Then the critical time length in seconds Δt can be determined as follows: | 1 | Applied and Interdisciplinary Chemistry |
Some coupling reagents omit the carbodiimide completely and incorporate the HOAt/HOBt moiety as an aminium/uronium or phosphonium salt of a non-nucleophilic anion (tetrafluoroborate or hexafluorophosphate). Examples of aminium/uronium reagents include HATU (HOAt), HBTU/TBTU (HOBt) and HCTU (6-ClHOBt). HBTU and TBTU differ only in the choice of anion. Phosphonium reagents include PyBOP (HOBt) and PyAOP (HOAt).
These reagents form the same active ester species as the carbodiimide activation conditions, but differ in the rate of the initial activation step, which is determined by nature of the carbon skeleton of the coupling reagent. Furthermore, aminium/uronium reagents are capable of reacting with the peptide N-terminus to form an inactive guanidino by-product, whereas phosphonium reagents are not. | 1 | Applied and Interdisciplinary Chemistry |
Cannulation requires installing a flanged rubber cylinder in the side of a cow, behind its 13th rib. The cylinder typically is fitted with a plastic, rubber, or metal cap to keep the rumen anaerobic.
The rubber cannula is surgically implanted while the cow is standing and awake, with local anesthetic. The cow is made to fast and refrain from drinking water for 24 hours in advance of the surgery. Then the veterinarian excises a small piece of the cow's skin, makes an incision through the rumen, and stitches the open sides of the rumen to the edges of skin, to prevent the contents of the rumen from leaking into the rest of the abdominal cavity. Finally, the inner flange of the cannula is pushed inside the rumen and capped. | 1 | Applied and Interdisciplinary Chemistry |
Enzymes that catalyse this reaction are termed aminases. Amination can occur in a number of ways including reaction with ammonia or another amine such as an alkylation, reductive amination and the Mannich reaction. | 0 | Theoretical and Fundamental Chemistry |
Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells (rods and cones) in the vertebrate retina. A photon is absorbed by a retinal chromophore (each bound to an opsin), which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve. | 1 | Applied and Interdisciplinary Chemistry |
Straight-chain azanes are sometimes indicated by the prefix n- (for normal) where a non-linear isomer exists. Although this is not strictly necessary, the usage is common in cases where there is an important difference in properties between the straight-chain and branched-chain isomers.
The members of the series (in terms of number of nitrogen atoms) are named as follows:
:azane (or ammonia), NH - one nitrogen and three hydrogen
:diazane (or hydrazine), - two nitrogen and four hydrogen
:triazane, - three nitrogen and five hydrogen
Azanes with three or more nitrogen atoms are named by adding the suffix -azane to the appropriate numerical multiplier prefix. Hence, triazane, ; tetrazane or tetraazane, ; pentazane or pentaazane, ; hexazane or hexaazane, ; etc. The prefix is generally Greek, with the exceptions of nonaazane which has a Latin prefix, and undecaazane and tridecaazane which have mixed-language prefixes. | 0 | Theoretical and Fundamental Chemistry |
dactinomycin - decarboxylation reaction - delta opioid receptor - denaturation (biochemistry) - dendrite - dendritic cell - dendritic spine - deoxyribonucleoprotein - deoxyribose - desmopressin - deuterium - developmental biology - dialysis (chemical) - diffusion - dimer - dinucleotide repeat - diploid - disaccharide - dissociation constant - disulfide bond - disulfide bridge - DNA - DNA fragmentation - DNA replication - DNA sequence - DNA topology - DNA transposable element - DNA virus - DNA-binding protein - dopamine D1 receptor - dopamine D2 receptor - dopamine receptor - double helix - Drosophila - drugs - dynorphin | 1 | Applied and Interdisciplinary Chemistry |
The yeast mediator complex is approximately as massive as a small subunit of a eukaryotic ribosome. The yeast mediator is composed of 25 subunits, while the mammalian mediator complexes are slightly larger. Mediator can be divided into 4 main parts: The head, middle, tail, and the transiently associated CDK8 kinase module.
Mediator subunits have many intrinsically disordered regions called "splines", which may be important to allow the structural changes of the mediator that change the function of the complex. The figure shows how the splines of the Med 14 subunit connect a large portion of the complex together while still allowing flexibility.
Mediator complexes that lack a subunit have been found or produced. These smaller mediators can still function normally in some activity, but lack other capabilities. This indicates a somewhat independent function of some of the subunits while being part of the larger complex.
Another example of structural variability is seen in vertebrates, in which 3 paralogues of subunits of the cyclin-dependent kinase module have evolved by 3 independent gene duplication events followed by sequence divergence. There is a report that mediator forms stable associations with a particular type of non-coding RNA, ncRNA-a. These stable associations have also been shown to regulate gene expression in vivo, and are prevented by mutations in MED12 that produce the human disease FG syndrome. Thus, the structure of a mediator complex can be augmented by RNA as well as proteinaceous transcription factors. | 1 | Applied and Interdisciplinary Chemistry |
Because converting RNA into cDNA, ligation, amplification, and other sample manipulations have been shown to introduce biases and artifacts that may interfere with both the proper characterization and quantification of transcripts, single molecule direct RNA sequencing has been explored by companies including Helicos (bankrupt), Oxford Nanopore Technologies, and others. This technology sequences RNA molecules directly in a massively-parallel manner. | 1 | Applied and Interdisciplinary Chemistry |
One important contribution during this period was the discovery of a means that allowed the administration of previously lethal doses of chemotherapy. The patients bone marrow was first harvested, the chemotherapy administered, and the harvested marrow then returned to patient a few days later. This approach, termed autologous bone marrow transplantation, was initially thought to be of benefit to a wide group of patients, including those with advanced breast cancer. However, rigorous studies have failed to confirm this benefit, and autologous transplantation is no longer widely used for solid tumors. The proven curative benefits of high doses of chemotherapy afforded by autologous bone marrow rescue are limited to both Hodgkins and selected non-Hodgkin's lymphoma patients who have failed therapy with conventional combination chemotherapy. Autologous transplantation continues to be used as a component of therapy for a number of other hematologic malignancies. | 1 | Applied and Interdisciplinary Chemistry |
Carbenes had first been postulated by Eduard Buchner in 1903 in cyclopropanation studies of ethyl diazoacetate with toluene. In 1912 Hermann Staudinger also converted alkenes to cyclopropanes with diazomethane and CH as an intermediate. Doering in 1954 demonstrated their synthetic utility with dichlorocarbene. | 0 | Theoretical and Fundamental Chemistry |
Fused quartz is normally transparent. The material can, however, become translucent if small air bubbles are allowed to be trapped within. The water content (and therefore infrared transmission) of fused quartz is determined by the manufacturing process. Flame-fused material always has a higher water content due to the combination of the hydrocarbons and oxygen fueling the furnace, forming hydroxyl [OH] groups within the material. An IR grade material typically has an [OH] content below 10 ppm. | 1 | Applied and Interdisciplinary Chemistry |
Alcohol and carboxylic acids react in the so-called Fischer esterification. The reaction usually requires a catalyst, such as concentrated sulfuric acid:
Other types of ester are prepared in a similar manner for example, tosyl (tosylate) esters are made by reaction of the alcohol with p-toluenesulfonyl chloride in pyridine. | 0 | Theoretical and Fundamental Chemistry |
Lewis Norman Mander, , FAA, FRS (8 September 1939 – 8 February 2020) was a New Zealand-born Australian organic chemist. He has widely explored the synthesis and chemistry of the gibberellin class of diterpenes over a 20-year period at the Australian National University (ANU). In particular, he studied the effect of these hormones on stem growth and on the reasons why plant undergo bolting during plant development. The July 2004 edition of the Australian Journal of Chemistry was dedicated to Mander on the occasion of his 65th birthday. He retired in 2002 but remained active at the ANU until 2014. In 2018 Mander was made a Companion in the General Division in the Order of Australia which "...is awarded for eminent achievement and merit of the highest degree in service to Australia or humanity at large".
In an interview he gave after winning his award, Mander said that his goal was to improve the efficiency of extracting food from plants with the possibility of reducing food shortages in the future. | 0 | Theoretical and Fundamental Chemistry |
When Eric Cornell and Carl Wieman produced a Bose–Einstein condensate from rubidium atoms in 1995, there naturally arose the prospect of creating a similar sort of condensate made from fermionic atoms, which would form a superfluid by the BCS mechanism. However, early calculations indicated that the temperature required for producing Cooper pairing in atoms would be too cold to achieve. In 2001, Murray Holland at JILA suggested a way of bypassing this difficulty. He speculated that fermionic atoms could be coaxed into pairing up by subjecting them to a strong magnetic field.
In 2003, working on Holland's suggestion, Deborah Jin at JILA, Rudolf Grimm at the University of Innsbruck, and Wolfgang Ketterle at MIT managed to coax fermionic atoms into forming molecular bosons, which then underwent Bose–Einstein condensation. However, this was not a true fermionic condensate. On December 16, 2003, Jin managed to produce a condensate out of fermionic atoms for the first time. The experiment involved 500,000 potassium-40 atoms cooled to a temperature of 5×10 K, subjected to a time-varying magnetic field. | 0 | Theoretical and Fundamental Chemistry |
There have been reports of large magnetoelectric coupling at room-temperature in type-I multiferroics such as in the "diluted" magnetic perovskite (PbZrTiO)–(PbFeTaO) (PZTFT) in certain Aurivillius phases. Here, strong ME coupling has been observed on a microscopic scale using PFM under magnetic field among other techniques. Organic-inorganic hybrid multiferroics have been reported in the family of metal-formate perovskites, as well as molecular multiferroics such as [(CH)NH][Ni(HCOO)], with elastic strain-mediated coupling between the order parameters. | 0 | Theoretical and Fundamental Chemistry |
22-Dihydroergocalciferol is a form of vitamin D, also known as vitamin D. It has the systematic name (5Z,7E)-(3S)-9,10-seco-5,7,10(19)-ergostatrien-3-ol.
Vitamin D is found in certain mushrooms, being produced from ergosta-5,7-dienol (22,23-dihydroergosterol) instead of ergosterol. | 1 | Applied and Interdisciplinary Chemistry |
c-Src is a gene that codes for proto-oncogene tyrosine-protein kinase Src, a protein important for normal mitotic cycling. It is phosphorylated and dephosphorylated to turn signaling on and off. Proto-oncogene tyrosine-protein kinase Src must be localized to the plasma membrane in order to phosphorylate other downstream targets; myristoylation is responsible for this membrane targeting event. Increased myristoylation of c-Src can lead to enhanced cell proliferation and be responsible for transforming normal cells into cancer cells. Activation of c-Src can lead to the so-called "hallmarks of cancer", among them upregulation of angiogenesis, proliferation, and invasion. | 1 | Applied and Interdisciplinary Chemistry |
Compounds begin to break down as soon as they enter the body. The majority of small-molecule drug metabolism is carried out in the liver by redox enzymes, termed cytochrome P450 enzymes. As metabolism occurs, the initial (parent) compound is converted to new compounds called metabolites. When metabolites are pharmacologically inert, metabolism deactivates the administered dose of parent drug and this usually reduces the effects on the body. Metabolites may also be pharmacologically active, sometimes more so than the parent drug (see prodrug). | 1 | Applied and Interdisciplinary Chemistry |
The starting material for this route is a β-(Δ-cyclopentenyl)-ethane derivative with a good leaving group on the terminal carbon of the ethane group. Electron density from the π bond of the alkene moiety is donated into the σ* anti-bond between the terminal carbon and the leaving group (see Figure 8c).
For example, the major product of the acetolysis of β-(Δ-cyclopentenyl)-ethyl nosylate (p-nitrobenzenesulfonate) is 2-exo-norbornyl acetate. The dearth of β-(Δ-cyclopentenyl)-ethyl acetate present after the reaction is explained by the greater stability of the norbornyl system over the decorated cyclopentenyl system.
This route is only effective if the cyclopentenyl olefin is isolated from any larger π-bonded system. The reaction rate significantly decreases if the involved double bond forms a six-membered aromatic ring as it does in 2-indanylethyl nosylate. Alkyl substitutions on the olefins have been seen to increase the reaction rate by stabilizing the resulting carbocation. | 0 | Theoretical and Fundamental Chemistry |
NSTX, and other PSTs, are produced by several species of marine dinoflagellates (eukaryotes) and freshwater cyanobacteria, blue-green algae (prokaryotes), which can form extensive blooms around the world. Under special conditions, during harmful algal blooms (HAB) or red tide, all these toxins may build up in filter-feeding shellfish, such as mussels, clams and oysters, and can produce an outbreak of Paralytic Shellfish Poisoning (PSP).
Saxitoxin analogues associated to PSP can be divided into three categories:
* Carbamate compounds, including saxitoxin, neosaxitoxin and gonyautoxins 1–4.
* N-sulfocarbamoyl compounds, including C and B toxins.
* Decarbamoyl compounds with respect to the presence or absence of 1-N-hydroxyl, 11-hydroxysulfate, and 21-N-sulfocarbamoyl substitutions as well as epimerization at the C-11 position. | 1 | Applied and Interdisciplinary Chemistry |
*Class I ARE elements, like the c-fos gene, have dispersed AUUUA motifs within or near U-rich regions.
*Class II elements, like the GM-CSF gene, have overlapping AUUUA motifs within or near U-rich regions.
*Class III elements, like the c-jun gene, are a much less well-defined class—they have a U-rich region but no AUUUA repeats.
No real ARE consensus sequence has been determined yet, and these categories are based neither on the same biological functions, nor on the homologous proteins. | 1 | Applied and Interdisciplinary Chemistry |
The first assumption is that the channel is much wider than it is deep, and the equations can be solved as if the channel were infinitely wide. This means that side-wall effects can be ignored, and that the hydraulic radius, , can be assumed to be equal to the channel depth, .
where is the cross sectional area of flow and is wetted perimeter. For a semicircular channel, the hydraulic radius would simply be the true radius.
For an approximately rectangular channel (for simplicity in the mathematics of the explanation of the assumption),
where is the width (breadth) of the channel, and
For b>>h,
and therefore
Formally, this assumption can generally be held to hold when the width is greater than about 20 times the height; the exact amount of error accrued can be found by comparing the height to the hydraulic radius. For channels with a lower width-to-depth ratio, a better solution can be found by using the hydraulic radius instead of the above simplification. | 1 | Applied and Interdisciplinary Chemistry |
While arsenic presents no radiological hazard, it is extremely chemically toxic. If it is desired to get rid of arsenic (no matter its origin), thermal neutron irradiation of the only stable isotope will yield short lived which quickly decays to stable . If Arsenic is irradiated with sufficient fast neutrons to cause notable "knockout" (n,2n) or even (n,3n) reactions, Isotopes of germanium will be produced instead. | 0 | Theoretical and Fundamental Chemistry |
Surface bodies of water provide environments able to dry out and be rewetted. Continued wet-dry cycles allow the concentration of prebiotic compounds and condensation reactions to polymerise macromolecules. Moreover, lake and ponds on land allow for detrital input from the weathering of continental rocks which contain apatite, the most common source of phosphates needed for nucleotide backbones. The amount of exposed continental crust in the Hadean is unknown, but models of early ocean depths and rates of ocean island and continental crust growth make it plausible that there was exposed land. Another line of evidence for a surface start to life is the requirement for UV for organism function. UV is necessary for the formation of the U+C nucleotide base pair by partial hydrolysis and nucleobase loss. Simultaneously, UV can be harmful and sterilising to life, especially for simple early lifeforms with little ability to repair radiation damage. Radiation levels from a young Sun were likely greater, and, with no ozone layer, harmful shortwave UV rays would reach the surface of Earth. For life to begin, a shielded environment with influx from UV-exposed sources is necessary to both benefit and protect from UV. Shielding under ice, liquid water, mineral surfaces (e.g. clay) or regolith is possible in a range of surface water settings. While deep sea vents may have input from raining down of surface exposed materials, the likelihood of concentration is lessened by the ocean's open system. | 0 | Theoretical and Fundamental Chemistry |
Flow focusing may be applied in the food, medicine, pharmaceutical, cosmetic, photographic and environmental industry, among other potential uses. The production of compound particles is an important field: drug encapsulation, dye-labeled particles and multiple-core particles can be cited. Other applications include flow cytometry and microfluidic circuits. Contrast agent such as droplets and Microbubbles can be produced in flow focusing microfluidics device. | 1 | Applied and Interdisciplinary Chemistry |
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