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In contrast to elution chromatography, solutes separated in displacement mode form sharp-edged zones rather than spreading peaks. Zone boundaries in displacement chromatography are self-sharpening: if a molecule for some reason gets ahead of its band, it enters a zone in which it is more strongly retained, and will then run more slowly until its zone catches up. Furthermore, because displacement chromatography takes advantage of the non-linearity of the isotherms, loadings are deliberately high; more material can be separated on a given column, in a given time, with the purified components recovered at significantly higher concentrations. Retention conditions can still be adjusted, but the displacer controls the migration rate of the solutes. The displacer is selected to have higher affinity for the stationary phase than does any of the solutes being separated, and its concentration is set to approach saturation of the stationary phase and to give the desired migration rate of the concentration wave. High-retention conditions can be employed without gradient operation, because the displacer ensures removal of all solutes of interest in the designed run time.
Because of the concentrating effect of loading the column under high-retention conditions, displacement chromatography is well suited to purify components from dilute feed streams. However, it is also possible to concentrate material from a dilute stream at the head of a chromatographic column and then switch conditions to elute the adsorbed material in conventional isocratic or gradient modes. Therefore, this approach is not unique to displacement chromatography, although the higher loading capacity and less dilution allow greater concentration in displacement mode.
A disadvantage of displacement chromatography is that non-idealities always give rise to an overlap zone between each pair of components; this mixed zone must be collected separately for recycle or discard to preserve the purity of the separated materials. The strategy of adding spacer molecules to form zones between the components (sometimes termed "carrier displacement chromatography") has been investigated and can be useful when suitable, readily removable spacers are found. Another disadvantage is that the raw chromatogram, for instance a plot of absorbance or refractive index vs elution volume, can be difficult to interpret for contiguous zones, especially if the displacement train is not fully developed. Documentation and troubleshooting may require additional chemical analysis to establish the distribution of a given component. Another disadvantage is that the time required for regeneration limits throughput.
According to John C. Fords article in the Encyclopedia of Chromatography', theoretical studies indicate that at least for some systems, optimized overloaded elution chromatography offers higher throughput than displacement chromatography, though limited experimental tests suggest that displacement chromatography is superior (at least before consideration of regeneration time). | 0 | Theoretical and Fundamental Chemistry |
Cellulose dissolves in aqueous solutions of , and zinc-cellulose complexes have been detected. Cellulose also dissolves in molten hydrate and carboxylation and acetylation performed on the cellulose polymer. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, an imidic acid is any molecule that contains the -C(=NH)-OH functional group. It is the tautomer of an amide and the isomer of an oxime.
The term "imino acid" is an obsolete term for this group that should not be used in this context because it has a different molecular structure.
Imidic acids can be formed by metal-catalyzed dehydrogenation of geminal amino alcohols. For example, methanolamine, the parent compound of the amino alcohols, can be dehydrogenated to methanimidic acid, the parent compound of the imidic acids.
:HNCHOH → HNCHOH + H (tautomer of formamide)
Geminal amino alcohols with side chains similarly form imidic acids with the same side chains:
:HNCHROH → HNCROH + H
Another way to form imidic acids is the reaction of carboxylic acids with azanone. For example, the reaction for carbamic acid:
:HNCOOH + HNO → HNCNHOH + O (tautomer of urea)
And the general reaction for substituted imidic acids:
:RCOOH + RNO → RCNROH + O
Another mechanism is the reaction of carboxylic acids with diazene or other azo compounds, forming azanone.
:RCOOH + HNNH → RCNHOH + HNO
Imidic acids tautomerize to amides by a hydrogen shift from the oxygen to the nitrogen atom. Amides are more stable in an environment with oxygen or water, whereas imidic acids dominate the equilibrium in solution with ammonia or methane.
:HNCHOH ⇌ HCONH
:RNCROH ⇌ RCONHR | 0 | Theoretical and Fundamental Chemistry |
* Dvornic, Petar R., and Jacovic S. Milhailo. "The Viscosity Effect on Autoacceleration of the Rate of Free Radical Polymerization". Wiley InterScience. 6 December 2007. | 0 | Theoretical and Fundamental Chemistry |
The relatively low intensity of the ionizing VUV radiation guarantees one-photon processes, in other words only one, fixed energy photon will be responsible for photoionization. The energy balance of photoionization comprises the internal energy and the adiabatic ionization energy of the neutral as well as the photon energy, the kinetic energy of the photoelectron and of the photoion. Because only threshold electrons are considered and the conservation of momentum holds, the last two terms vanish, and the internal energy of the photoion is known:
Scanning the photon energy corresponds to shifting the internal energy distribution of the parent ion. The parent ion sits in a potential energy well, in which the lowest energy exit channel often corresponds to the breaking of the weakest chemical bond, resulting in the formation of a fragment or daughter ion. A mass spectrum is recorded at every photon energy, and the fractional ion abundances are plotted to obtain the breakdown diagram. At low energies no parent ion is energetic enough to dissociate, and the parent ion corresponds to 100% of the ion signal. As the photon energy is increased, a certain fraction of the parent ions (in fact according to the cumulative distribution function of the neutral internal energy distribution) still has too little energy to dissociate, but some do. The parent ion fractional abundances decrease, and the daughter ion signal increases. At the dissociative photoionization threshold, E, all parent ions, even the ones with initially 0 internal energy, can dissociate, and the daughter ion abundance reaches 100% in the breakdown diagram.
If the potential energy well of the parent ion is shallow and the complete initial thermal energy distribution is broader than the depth of the well, the breakdown diagram can also be used to determine adiabatic ionization energies. | 0 | Theoretical and Fundamental Chemistry |
Myocardial perfusion imaging (MPI) is a form of functional cardiac imaging, used for the diagnosis of ischemic heart disease. The underlying principle is, under conditions of stress, diseased myocardium receives less blood flow than normal myocardium. MPI is one of several types of cardiac stress test. As a nuclear stress test, the average radiation exposure is 9.4 mSv, which when compared with a typical 2 view chest X-ray (.1 mSv) is equivalent to 94 Chest X-rays.
Several radiopharmaceuticals and radionuclides may be used for this, each giving different information. In the myocardial perfusion scans using Tc, the radiopharmaceuticals Tc-tetrofosmin (Myoview, GE Healthcare) or Tc-sestamibi (Cardiolite, Bristol-Myers Squibb) are used. Following this, myocardial stress is induced, either by exercise or pharmacologically with adenosine, dobutamine or dipyridamole(Persantine), which increase the heart rate or by regadenoson(Lexiscan), a vasodilator. (Aminophylline can be used to reverse the effects of dipyridamole and regadenoson). Scanning may then be performed with a conventional gamma camera, or with SPECT/CT. | 0 | Theoretical and Fundamental Chemistry |
Biological nitrogen fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by a nitrogenase enzyme. The overall reaction for BNF is:
The process is coupled to the hydrolysis of 16 equivalents of ATP and is accompanied by the co-formation of one equivalent of . The conversion of into ammonia occurs at a metal cluster called FeMoco, an abbreviation for the iron-molybdenum cofactor. The mechanism proceeds via a series of protonation and reduction steps wherein the FeMoco active site hydrogenates the substrate. In free-living diazotrophs, nitrogenase-generated ammonia is assimilated into glutamate through the glutamine synthetase/glutamate synthase pathway. The microbial nif genes required for nitrogen fixation are widely distributed in diverse environments.
For example, decomposing wood, which generally has a low nitrogen content, has been shown to host a diazotrophic community. The bacteria enrich the wood substrate with nitrogen through fixation, thus enabling deadwood decomposition by fungi.
Nitrogenases are rapidly degraded by oxygen. For this reason, many bacteria cease production of the enzyme in the presence of oxygen. Many nitrogen-fixing organisms exist only in anaerobic conditions, respiring to draw down oxygen levels, or binding the oxygen with a protein such as leghemoglobin. | 1 | Applied and Interdisciplinary Chemistry |
Installation effects such as insufficient straight pipe, exceptional pipe roughness or smoothness, elbows, valves, tees and reducers causes the flow conditions within the pipe to vary from the reference conditions. How these installation effects impact the meter is very important since devices which create upstream installation effects are common components of any standard metering design. Flow Conditioning refers to the process of artificially generating a reference, fully developed flow profile and is essential to enable accurate measurement while maintaining a cost-competitive meter standard design. The meter calibration factors are valid only of geometric and dynamic similarity exists between the metering and calibration conditions. In fluid mechanics, this is commonly referred to as the Law of Similarity. | 1 | Applied and Interdisciplinary Chemistry |
Even if there is no oxygen present, glycolysis can continue to generate ATP. However, for glycolysis to continue to produce ATP, there must be NAD+ present, which is responsible for oxidizing glucose. This is achieved by recycling NADH back to NAD+. When NAD+ is reduced to NADH, the electrons from NADH are eventually transferred to a separate organic molecule, transforming NADH back to NAD+. This process of renewing the supply of NAD+ is called fermentation, which falls into two categories. | 1 | Applied and Interdisciplinary Chemistry |
A study from the Albert Einstein College of Medicine, where researchers deleted gD-2 from the herpes virus, which is responsible for HSV microbes entering in and out of cells showed as of May 1, 2018 the same vaccine can be used in a modified way to contain hemagglutinin and invoke a special ADCC immune response.
The Washington University School of Medicine in St. Louis and the Icahn School of Medicine in Mount Sinai in New York are using the glycoprotein neuraminidase as a targeted antigen in their research. Three monoclonal antibodies (mAB) were sampled from a patient infected with influenza A H3N2 virus. The antibodies were able to bind to the neuraminidase active site neutralizing the virus across multiple strains. The site remains the same with minimal variability across most of the flu strains. In trials using mice all three antibodies were effective across multiple strains, one antibody was able to protect the mice from all 12 strains tested including human and non-human flu viruses. All mice used in the experiments survived even if the antibody was not administered until 72 hours after the time of infection.
Simultaneously the NIAID is working on a peptide vaccine that is starting human clinical trials in the 2019 flu season. The study will include 10,000 participants who will be monitored for two flu seasons. The vaccine will show efficacy if it is able to reduce the number of influenza cases in all strains.
There have been some clinical trials of the M-001 and H1ssF_3928 universal influenza vaccine candidates. As of August 2020, all seven M-001 trials are completed. Each one of these studies resulted in the conclusion that M-001 is safe, tolerable, and immunogenic. Their pivotal PhaseIII study with 12,400 participants was completed and results of the data analysis were published in October 2020, indicating that the vaccine did not show any statistical difference from the placebo group in reduction of flu illness and severity.
In 2019–2020, a vaccine candidate from Peter Palese's group at Mount Sinai Hospital emerged from a phase 1 clinical trial with positive results. By vaccinating twice with hemagglutinins that have different "heads" but the same membrane-proximal "stalk", the immune system is directed to focus its attention on the conserved stalk. | 1 | Applied and Interdisciplinary Chemistry |
The method was originally investigated by Otto Rosenheim while examining and improving on the methods by German British chemist Otto Hehner
(1853–1924) that was used to detect formaldehyde in milk by adding sulphuric acid, which produced a blue ring. Acree noticed the reaction's similarities with the Adamkiewicz reaction and the reaction noticeably higher in casein. Based on this 1906 research, Acree investigated the reaction in 1907 in the general context of formaldehyde reactions with all forms of protein and was the first to find the importance of the tryptophan group in the reaction, which can be extracted from casein in milk. | 0 | Theoretical and Fundamental Chemistry |
Many ancient cultures, including those in Australia, China, Egypt, Greece and India, independently discovered the useful properties of fungi and plants in treating infections. These treatments often worked because many organisms, including many species of mould, naturally produce antibiotics. However, ancient practitioners could not precisely identify or isolate the active components in these organisms.
In England in 1640, the idea of using mould as a form of medical treatment was recorded by apothecaries such as the botanist John Parkinson, who documented the use of moulds to treat infections in his book on pharmacology. In 17th-century Poland, wet bread was mixed with spider webs (which often contained fungal spores) to treat wounds. The technique was mentioned by Henryk Sienkiewicz in his 1884 novel With Fire and Sword.
In 1871, Sir John Scott Burdon-Sanderson reported that culture fluid covered with mould would produce no bacterial growth. Joseph Lister, an English surgeon and the father of modern antisepsis, observed in November 1871 that urine samples contaminated with mould also did not permit the growth of bacteria. He also described the antibacterial action on human tissue of Penicillium glaucum but did not publish his results. In 1875 John Tyndall demonstrated to the Royal Society the antibacterial action of the Penicillium fungus.
In 1876, German biologist Robert Koch discovered that a bacterium (Bacillus anthracis) was the causative pathogen of anthrax, which became the first demonstration that a specific bacterium caused a specific disease and the first direct evidence of germ theory of diseases. In 1877, French biologists Louis Pasteur and Jules Francois Joubert observed that cultures of anthrax bacilli, when contaminated with other bacteria, could be successfully inhibited. Reporting in the Comptes Rendus de lAcadémie des Sciences', they concluded:
The phenomenon was described by Pasteur and Koch as antibacterial activity and was named antibiosis by French biologist Jean Paul Vuillemin in 1877. (The term antibiosis, meaning against life, was adopted as antibiotic by American biologist and later Nobel laureate Selman Waksman in 1947.) However, Paul de Kruifs 1926 Microbe Hunters' notes that Pasteur believed that this was contamination by other bacteria rather than by mould. In 1887, Swiss physician Carl Garré developed a test method using glass plate to see bacterial inhibition and found similar results. Using his gelatin-based culture plate, he grew two different species of bacteria and found that their growths were inhibited differently, as he reported:
In 1895, Vincenzo Tiberio, an Italian physician at the University of Naples, published research on moulds initially found in a water well in Arzano; from his observations, he concluded that these moulds contained soluble substances having antibacterial action. Two years later, Ernest Duchesne at École du Service de Santé Militaire in Lyon independently discovered the healing properties of a P. glaucum mould, even curing infected guinea pigs of typhoid. He published his results in a dissertation in 1897. Duchesne was using a discovery made earlier by Arab stable boys, who used moulds to cure sores on horses. He did not claim that the mould contained any antibacterial substance, only that the mould somehow protected the animals. Penicillin does not cure typhoid and so it remains unknown which substance might have been responsible. A Pasteur Institute scientist, Costa Rican Clodomiro Picado Twight, similarly recorded the antibiotic effect of Penicillium in 1923. In these early stages of penicillin research, most species of Penicillium were non-specifically referred to as P. glaucum, so that it is impossible to know the exact species and that it was really penicillin that prevented bacterial growth.
Andre Gratia and Sara Dath at the Free University of Brussels studied the effects of mould samples on bacteria. In 1924, they found that dead Staphylococcus aureus cultures were contaminated by a mould, a streptomycete. Upon further experimentation, they showed that the mould extract could kill not only S. aureus, but also Pseudomonas aeruginosa, Mycobacterium tuberculosis and Escherichia coli. Gratia called the antibacterial agent "mycolysate". The next year they found another killer mould that could inhibit B. anthracis. Reporting in , they identified the mould as P. glaucum. But these findings received little attention as the antibacterial agent and its medical value were not fully understood, and Gratia's samples were lost. | 1 | Applied and Interdisciplinary Chemistry |
CRISPR-associated transposons are similar to the Tn7 transposon which functions with a cut and paste mechanism. It contains a heteromeric transposase consisting of TnsA and TnsB proteins, and a regulator protein TnsC. Structural analysis has shown binding of the TnsB protein and sequence specific motifs on the ends of the transposon which allows for excision and mobility. Targeting for integration is done by the TnsD or TnsE proteins which preferentially target safe sites within the host chromosome or mobile elements (plasmids or bacteriophages), respectively. TnsE is not found in CASTs but a TnsD homolog, TniQ, is present and functions to bridge the gap between the transposase and CRISPR-Cas. Multiple CRISPR types have been found to associate with transposons with two of the most studied being Type I-F, which makes use of a multi-subunit effector (Cascade), and Type V-K, which makes use of a single Cas12k effector. In both cases, Tn7 transposons have evolved to make use of these effectors to create R loops for site-specific integration. While TnsA is present in Type I-F systems, it is notably absent in Type V-K systems which showed higher off-target integrations during initial characterization. | 1 | Applied and Interdisciplinary Chemistry |
There are two main assaying techniques: heterogeneous and homogeneous. If two lanthanide chelates are used in the analysis one after the other—it is called heterogeneous assaying. The first analyte is linked to a specific binding agent on a solid support such as a polymer and then another reaction couples the first poorly luminescent lanthanide complex with a new better one. This tedious method is used because the second more luminescent compound would not bind without the first analyte already present. Subsequent time resolved detection of the metal-centered luminescent probe yields the desired signal. Antigens, steroids and hormones are routinely assayed with heterogeneous techniques. Homogeneous assays rely on direct coupling of the lanthanide label with an organic acceptor.
The relaxation of excited molecules states often occurs by the emission of light which is called fluorescence. There are two ways of measuring this emitted radiation: as a function of frequency (inverse to wavelength) or time. Conventionally the fluorescence spectrum shows the intensity of fluorescence at different wavelengths, but since lanthanides have relatively long fluorescence decay times (ranging from one microsecond to one millisecond), it is possible to record the fluorescence emission at different decay times from the given excitation energy at time zero. This is called time resolved fluorescence spectroscopy. | 1 | Applied and Interdisciplinary Chemistry |
The GFP bestows several annual or biennial awards, alone or jointly with the [https://www.societechimiquedefrance.fr/Polymeres-et-materiaux.html SCF] or the SFP:
* Polymer Thesis Award of the Education Commission of the GFP (annual)
* Polymer Division Award, jointly awarded with the SCF, recognizing an early career scientist (less than 40 years old) for significant scientific results or original techniques in polymer chemistry (biennial, since 1992)
* Polymer Division Award, jointly awarded with the SFP, recognizing an early career scientist (less than 40 years old) for significant scientific results or original techniques in polymer physics (biennial, since 2004)
* Grand Prix of the GFP, recognizing the career or the complete works of a French or international researcher in polymer science (biennial, since 2003)
* Prix d'Honneur of the GFP, recognizing a scientific career dedicated to polymer science (annual, since 2017) | 1 | Applied and Interdisciplinary Chemistry |
Chloromethyl methyl ether (CMME) is a compound with formula CHOCHCl. A colorless liquid, it is a chloroalkyl ether. It is used as an alkylating agent. In organic synthesis, it is used for introducing the methoxymethyl ether (MOM) protecting group, and is thus often called MOM-Cl or MOM chloride. It also finds application as a chloromethylating agent in some variants of the Blanc chloromethylation. | 0 | Theoretical and Fundamental Chemistry |
Assuming that and Taylor expanding the second exact perturbation theory expression to the second order, one gets the approximation
Note that the first term is the expected value of the energy difference, while the second is essentially its variance. | 0 | Theoretical and Fundamental Chemistry |
Photoexcitation is the mechanism of electron excitation by photon absorption, when the energy of the photon is too low to cause photoionization. The absorption of the photon takes place in accordance with Planck's quantum theory.
Photoexcitation plays role in photoisomerization. Photoexcitation is exploited in dye-sensitized solar cells, photochemistry, luminescence, optically pumped lasers, and in some photochromic applications. | 0 | Theoretical and Fundamental Chemistry |
Carbon-carbon bond activation reactions have numerous applications in organic synthesis, materials science, and pharmaceuticals. In organic synthesis, these reactions are used to construct complex molecules in a highly efficient and selective manner. For example, in 2021 Dong Group described the first enantioselective total synthesis of the natural product penicibilaenes using a late-stage carbon-carbon bond activation strategy. There are also a lot of other examples highlighting the potential of carbon-carbon bond activation strategies in the total synthesis of complex natural products with high stereocontrol. | 0 | Theoretical and Fundamental Chemistry |
Plastic Pipes are classified by their ring stiffness. The preferred stiffness classes as described in several product standards are: SN2, SN4, SN8 and SN16, where SN is Nominal Stiffness (kN/m2). Stiffness of pipes is important if they are to withstand external loadings during installation. The higher the figure, the stiffer the pipe.
After correct installation, pipe deflection remains limited but it will continue to some extent for a while. In relation to the soil in which it is embedded, the plastic pipe behaves in a flexible way. This means that further deflection in time depends on the settlement of the soil around the pipe.
Basically, the pipe follows the soil movement or settlement of the backfill, as technicians call it. This means that good installation of pipes will result in good soil settlement. Further deflection will remain limited.
For flexible pipes, the soil loading is distributed and supported by the surrounding soil. Stresses and strains caused by the deflection of the pipe will occur within the pipe wall. However, the induced stresses will never exceed the allowed limit values.
The thermoplastic behavior of the pipe material is such that the induced stresses are relaxing to a low level. It has to be noted that induced strains are far below the allowable levels.
This flexible behaviour means that the pipe will not fail. It will exhibit only more deflection while keeping its function without breaking.
However, rigid pipes by their very nature are not flexible and will not follow ground movements. They will bear all the ground loadings, whatever the soil settlement. This means that when a rigid pipe is subject to excessive loading, it will reach the limit for stress values more quickly and break.
It can therefore be concluded that the flexibility of plastic pipes offers an extra dimension of safety. Buried Pipes need flexibility. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, AD-mix is a commercially available mixture of reagents that acts as an asymmetric catalyst for various chemical reactions, including the Sharpless asymmetric dihydroxylation of alkenes. The two letters AD, stand for asymmetric dihydroxylation. The mix is available in two variations, "AD-mix α" and "AD-mix β" following ingredient lists published by Barry Sharpless.
The mixes contain:
* Potassium osmate KOsO(OH) as the source of Osmium tetroxide
* Potassium ferricyanide KFe(CN), which is the re-oxidant in the catalytic cycle
* Potassium carbonate
* A chiral ligand:
**AD-mix α contains (DHQ)PHAL, the phthalazine adduct with dihydroquinine
:*AD-mix β contains (DHQD)PHAL, the phthalazine adduct with dihydroquinidine | 0 | Theoretical and Fundamental Chemistry |
* US/NATO Military specification - MIL-H-8446
* Boeing Seattle - BMS3-11
* Boeing Long Beach - DMS2014
* Boeing Long Island - CDS5478
* Lockheed - LAC C-34-1224
* Airbus Industrie - NSA307110
* British Aerospace - BAC M.333.B
* Bombardier - BAMS 564-003
* SAE - Ac974
* SAE - AS1241
* Skydrol | 1 | Applied and Interdisciplinary Chemistry |
The Teck Cominco smelter, also known as the Teck Cominco Lead-Zinc Smelter, Cominco Smelter, and Trail smelter located in Trail, British Columbia, Canada, is the largest integrated lead-zinc smelter of its kind in the world. It is situated approximately north of the border between British Columbia, Canada and Washington, in the United States, on the Columbia River. It is owned and operated by Vancouver, British Columbia-based Teck Cominco Metals Ltd—renamed Teck Resources.
Since 1896, there has been a copper and gold smelting operation in the area. The original company, Consolidated Mining and Smelting Company of Canada, was founded in 1906 through a merger of several entities then under the control of the Canadian Pacific Railway (CPR). In July 2001, Cominco and Tech Resources merged and in 2008, Teck Cominco renamed itself as Teck. By 2018, the Teck Cominco smelter complex had been in operation for over a century. It provided 1,400 jobs in 2018, making it the largest employer in the small city of Trail, with a population of 7800. In 2017, the smelter produced more than 230,000 tons of zinc, which is used in rustproofing both iron and steel. Teck reported that they had invested CA$525 million in the late 2010s to "improve efficiency and performance at its Trail Operations" and that they intend to invest an added CA$150 million. The Trail Operations contributed CA$169 million to Teck Resources CA$3.3-billion gross profit in 2017. | 1 | Applied and Interdisciplinary Chemistry |
The stability of the Keggin structure allows the metals in the anion to be readily reduced. Depending on the solvent, acidity of the solution and the charge on the α-Keggin anion, it can be reversibly reduced in one- or multiple-electron steps. For example, the silicotungstate anion can be reduced a −20 state. Some anions such as silicotungstic acid are strong enough as an acid as sulfuric acid and can be used in its place as an acid catalyst. | 0 | Theoretical and Fundamental Chemistry |
In its basic form, mounds are constructed by piling logs, branches, plant waste, compost and additional soil directly on the ground. The pile has the form of a pyramid. (Note—Wheaton suggests piling the wood higglety-pigletty rather than in a neat stack as shown, for structural engineering of the steep slope, or perpendicular to the spine of the mound.) The sides of the two slopes both have a grade of between 65 and 80 degrees. The beds are usually about in area and about high. However, this height reduces as decomposition progresses.
When positioned on sloped terrain, the beds need to be placed on contour, or put at an angle to the hillside (rather than having them parallel to it). This makes sure the beds do not receive unequal amounts of water. In most cases, it is useful to have the beds positioned against the prevailing wind direction.
The raised bed can form light-duty swales, circles and mazes. Mounds may also be made from alternating layers of wood, sod, compost, straw, and soil. Although their construction is straightforward, planning is necessary to prevent steep slopes that would result in erosion.
In his book Desert or Paradise: Restoring Endangered Landscapes Using Water Management, Including Lake and Pond Construction, Holzer describes a method of constructing Hügelkultur which incorporates rubbish such as cardboard, clothes and kitchen waste. He recommends building mounds that are wide and any length. Mounds are built in a trench in sandy soil, and without a trench if the ground is wet. | 1 | Applied and Interdisciplinary Chemistry |
Converting a mixture of H and CO into aliphatic products is a multi-step reaction with several intermediate compounds. The growth of the hydrocarbon chain may be visualized as involving a repeated sequence in which hydrogen atoms are added to carbon and oxygen, the C–O bond is split and a new C–C bond is formed.
For one –CH– group produced by CO + 2 H → (CH) + HO, several reactions are necessary:
* Associative adsorption of CO
* Splitting of the C–O bond
* Dissociative adsorption of 2 H
* Transfer of 2 H to the oxygen to yield HO
* Desorption of HO
* Transfer of 2 H to the carbon to yield CH
The conversion of CO to alkanes involves hydrogenation of CO, the hydrogenolysis (cleavage with H) of C–O bonds, and the formation of C–C bonds. Such reactions are assumed to proceed via initial formation of surface-bound metal carbonyls. The CO ligand is speculated to undergo dissociation, possibly into oxide and carbide ligands. Other potential intermediates are various C fragments including formyl (CHO), hydroxycarbene (HCOH), hydroxymethyl (CHOH), methyl (CH), methylene (CH), methylidyne (CH), and hydroxymethylidyne (COH). Furthermore, and critical to the production of liquid fuels, are reactions that form C–C bonds, such as migratory insertion. Many related stoichiometric reactions have been simulated on discrete metal clusters, but homogeneous Fischer–Tropsch catalysts are of no commercial importance.
Addition of isotopically labelled alcohol to the feed stream results in incorporation of alcohols into product. This observation establishes the facility of C–O bond scission. Using C-labelled ethylene and propene over cobalt catalysts results in incorporation of these olefins into the growing chain. Chain growth reaction thus appears to involve both olefin insertion as well as CO-insertion. | 0 | Theoretical and Fundamental Chemistry |
Hypothermia has played a major role in the success or failure of many military campaigns, from Hannibals loss of nearly half his men in the Second Punic War (218 B.C.) to the near destruction of Napoleons armies in Russia in 1812. Men wandered around confused by hypothermia, some lost consciousness and died, others shivered, later developed torpor, and tended to sleep. Others too weak to walk fell on their knees; some stayed that way for some time resisting death. The pulse of some was weak and hard to detect; others groaned; yet others had eyes open and wild with quiet delirium. Deaths from hypothermia in Russian regions continued through the first and second world wars, especially in the Battle of Stalingrad.
Civilian examples of deaths caused by hypothermia occurred during the sinkings of the RMS Titanic and RMS Lusitania, and more recently of the MS Estonia.
Antarctic explorers developed hypothermia; Ernest Shackleton and his team measured body temperatures "below 94.2°, which spells death at home", though this probably referred to oral temperatures rather than core temperature and corresponded to mild hypothermia. One of Scott's team, Atkinson, became confused through hypothermia.
Nazi human experimentation during World War II amounting to medical torture included hypothermia experiments, which killed many victims. There were 360 to 400 experiments and 280 to 300 subjects, indicating some had more than one experiment performed on them. Various methods of rewarming were attempted: "One assistant later testified that some victims were thrown into boiling water for rewarming". | 1 | Applied and Interdisciplinary Chemistry |
Phenolic compounds are mostly found in vascular plants (tracheophytes) i.e. Lycopodiophyta (lycopods), Pteridophyta (ferns and horsetails), Angiosperms (flowering plants or Magnoliophyta) and Gymnosperms (conifers, cycads, Ginkgo and Gnetales).
In ferns, compounds such as kaempferol and its glucoside can be isolated from the methanolic extract of fronds of Phegopteris connectilis or kaempferol-3-O-rutinoside, a known bitter-tasting flavonoid glycoside, can be isolated from the rhizomes of Selliguea feei. Hypogallic acid, caffeic acid, paeoniflorin and pikuroside can be isolated from the freshwater fern Salvinia molesta.
In conifers (Pinophyta), phenolics are stored in polyphenolic parenchyma cells, a tissue abundant in the phloem of all conifers.
The aquatic plant Myriophyllum spicatum produces ellagic, gallic and pyrogallic acids and (+)-catechin. | 0 | Theoretical and Fundamental Chemistry |
The Bradford assay, a colorimetric protein assay, is based on an absorbance shift of the dye Coomassie brilliant blue G-250. The Coomassie brilliant blue G-250 dye exists in three forms: anionic (blue), neutral (green), and cationic (red). Under acidic conditions, the red form of the dye is converted into its blue form, binding to the protein being assayed. If theres no protein to bind, then the solution will remain brown. The dye forms a strong, noncovalent complex with the proteins carboxyl group by van der Waals force and amino group through electrostatic interactions. During the formation of this complex, the red form of Coomassie dye first donates its free electron to the ionizable groups on the protein, which causes a disruption of the proteins native state, consequently exposing its hydrophobic pockets. These pockets in the proteins tertiary structure bind non-covalently to the non-polar region of the dye via the first bond interaction (van der Waals forces) which position the positive amine groups in proximity with the negative charge of the dye. The bond is further strengthened by the second bond interaction between the two, the ionic interaction. When the dye binds to the protein, it causes a shift from 465 nm to 595 nm, which is why the absorbance readings are taken at 595 nm.
The cationic (unbound) form is green / red and has an absorption spectrum maximum historically held to be at 465 nm. The anionic bound form of the dye which is held together by hydrophobic and ionic interactions, has an absorption spectrum maximum historically held to be at 595 nm. The increase of absorbance at 595 nm is proportional to the amount of bound dye, and thus to the amount (concentration) of protein present in the sample.
Unlike other protein assays, the Bradford protein assay is less susceptible to interference by various chemical compounds such as sodium, potassium or even carbohydrates like sucrose, that may be present in protein samples. An exception of note is elevated concentrations of detergent. Sodium dodecyl sulfate (SDS), a common detergent, may be found in protein extracts because it is used to lyse cells by disrupting the membrane lipid bilayer and to denature proteins for SDS-PAGE. While other detergents interfere with the assay at high concentration, the interference caused by SDS is of two different modes, and each occurs at a different concentration. When SDS concentrations are below critical micelle concentration (known as CMC, 0.00333%W/V to 0.0667%) in a Coomassie dye solution, the detergent tends to bind strongly with the protein, inhibiting the protein binding sites for the dye reagent. This can cause underestimations of protein concentration in solution. When SDS concentrations are above CMC, the detergent associates strongly with the green form of the Coomassie dye, causing the equilibrium to shift, thereby producing more of the blue form. This causes an increase in the absorbance at 595 nm independent of protein presence.
Other interference may come from the buffer used when preparing the protein sample. A high concentration of buffer will cause an overestimated protein concentration due to depletion of free protons from the solution by conjugate base from the buffer. This will not be a problem if a low concentration of protein (subsequently the buffer) is used.
In order to measure the absorbance of a colorless compound a Bradford assay must be performed. Some colorless compounds such as proteins can be quantified at an Optical Density of 280 nm due to the presence of aromatic rings such as Tryptophan, Tyrosine and Phenylalanine but if none of these amino acids are present then the absorption cannot be measured at 280 nm. | 0 | Theoretical and Fundamental Chemistry |
The development of the Isa Process tank house technology at CRL eliminated the whole process and cost of producing the starter sheets by using stainless-steel permanent cathodes. It also included substantial automation of the process of inserting the permanent cathodes into the electrolytic cells and their subsequent removal and stripping of the sheets of deposited cathode copper. The labour force required to operate a refinery using the IsaKidd technology has been estimated at 60–70% less of that required for refineries using starter sheets.
MIM Holdings began marketing the Isa Process technology in 1980, as a result of demand from other refinery operators.
Falconbridge subsequently independently developed a similar process to improve operations at its Kidd Creek copper refinery, near Timmins, Ontario. The initial development of permanent cathodes was for internal use, but marketing of the Kidd Process was initiated in 1992 after requests from other refinery operators.
The two technologies were brought together as the IsaKidd Technology in 2006, when Xstrata bought Falconbridge.
The IsaKidd Technology now dominates global copper refining. It has been licensed to 102 users and Xstrata Technology, which markets the technology, reports on its website a total installed capacity of some 12 million tonnes per year (“t/y”) of copper production, as of October 2011. This is about 60% of the estimated 2011 global refined copper production of 19.7 million tonnes.
The development of the IsaKidd technology allowed increased productivity, reduced operating costs and the production of consistent, high-quality cathode copper. | 1 | Applied and Interdisciplinary Chemistry |
Magnesium oxalate has been found naturally near Mill of Johnston, which is located close to Insch in northeast Scotland. This naturally occurring magnesium oxalate is called glushinskite and occurs at the lichen/rock interface on serpentinite as a creamy white layer mixed in with the hyphae of the lichen fungus. A scanning electron micrograph of samples taken showed that the crystals had a pyramidal structure with both curved and striated faces. The size of these crystals ranged from 2 to 5 μm. | 0 | Theoretical and Fundamental Chemistry |
The FDA Table of Pharmacogenomic Biomarkers in Drug Labeling lists FDA-approved drugs with pharmacogenomic information found in the drug labeling. "Biomarkers in the table include but are not limited to germline or somatic gene variants (polymorphisms, mutations), functional deficiencies with a genetic etiology, gene expression differences, and chromosomal abnormalities; selected protein biomarkers that are used to select treatments for patients are also included." | 1 | Applied and Interdisciplinary Chemistry |
Alkenyl- and alkynylaluminates are most commonly generated through the addition of n-butyllithium to the alkenylalane. The alkenyl and alkynyl groups, which are better able to stabilize negative charge, are transferred in preference to the alkyl group. When these intermediates react with alkyl halides, functionalized olefins are produced.
Treatment of alkenylaluminates with halogen electrophiles such as N-bromosuccinimide (NBS) and iodine leads to the formation of halogenated olefins. These products are useful for cross-coupling reactions.
Zirconium-catalyzed carboalumination of alkynes by trimethylalane is a convenient method for accessing substituted alkenylalanes stereoselectively. Upon exposure to aldehydes and ketones, alkenylalanes form secondary or tertiary allylic alcohols. Formaldehyde is a useful reagent in this context for the introduction of a hydroxymethyl unit.
Alkynylalanes are primarily used in place of the corresponding alkali metal acetylides when the latter reagents are ineffective. The coupling of an acetylide and tertiary alkyl halide is an example of a reaction that cannot be accomplished with alkali metal acetylides, which displace halides in an S2 fashion. The corresponding alkynylalanes are able to couple to tertiary halides via an S1-like mechanism.
Alkynyl- and alkenylalanes add in a conjugate fashion to enones in the s-cis conformation without nucleophilic activation. Enones locked in an s-trans conformation, such as cyclohexenone, are unreactive. The coordination of oxygen to aluminium is believed to be necessary for this reaction.
When alkynes and dialkylalanes are combined in a 2:1 ratio, 1,3-dienes result. The aluminium-carbon bond of the initially formed alkenylalane adds across a second molecule of alkyne, forming a conjugated dienylalane. Protonolysis provides the metal-free diene product.
Alkenyl- and alkynylalanes undergo transmetalation to a variety of metals, including boron, zirconium, and mercury. | 0 | Theoretical and Fundamental Chemistry |
A storm drain, storm sewer (United Kingdom, U.S. and Canada), surface water drain/sewer (United Kingdom), or stormwater drain (Australia and New Zealand) is infrastructure designed to drain excess rain and ground water from impervious surfaces such as paved streets, car parks, parking lots, footpaths, sidewalks, and roofs. Storm drains vary in design from small residential dry wells to large municipal systems.
Drains receive water from street gutters on most motorways, freeways and other busy roads, as well as towns in areas with heavy rainfall that leads to flooding, and coastal towns with regular storms. Even gutters from houses and buildings can connect to the storm drain. Many storm drainage systems are gravity sewers that drain untreated storm water into rivers or streams—so it is unacceptable to pour hazardous substances into the drains.
Storm drains sometimes cannot manage the quantity of rain that falls in heavy rains or storms. Inundated drains can cause basement and street flooding. Many areas require detention tanks inside a property that temporarily hold runoff in heavy rains and restrict outlet flow to the public sewer. This reduces the risk of overwhelming the public sewer. Some storm drains mix stormwater (rainwater) with sewage, either intentionally in the case of combined sewers, or unintentionally. | 1 | Applied and Interdisciplinary Chemistry |
Several of the isotope systems involved in radiometric dating depend on IRMS using thermal ionization of a solid sample loaded into the source of the mass spectrometer (hence thermal ionization mass spectrometry, TIMS). These methods include rubidium–strontium dating, uranium–lead dating, lead–lead dating and samarium–neodymium dating.
When these isotope ratios are measured by TIMS, mass-dependent fractionation occurs as species are emitted by the hot filament. Fractionation occurs due to the excitation of the sample and therefore must be corrected for accurate measurement of the isotope ratio.
There are several advantages of the TIMS method. It has a simple design, is less expensive than other mass spectrometers, and produces stable ion emissions. It requires a stable power supply, and is suitable for species with a low ionization potential, such as Strontium (Sr), and Lead (Pb).
The disadvantages of this method stem from the maximum temperature achieved in thermal ionization. The hot filament reaches a temperature of less than 2500 degrees Celsius, leading to the inability to create atomic ions of species with a high ionization potential, such as Osmium (Os), and Tungsten (Hf-W). Although the TIMS method can create molecular ions instead in this case, species with high ionization potential can be analyzed more effectively with MC-ICP-MS. | 0 | Theoretical and Fundamental Chemistry |
Another benefit of using conductive polymers as a coating for neural devices is the ease of synthesis and flexibility in processing. Conducting polymers can be directly "deposited onto electrode surfaces with precisely controlled morphologies". There are two current ways conducting polymers can be deposited onto electrode surfaces which are chemical polymerization and electrochemical polymerization. In the application for neural implants, electrochemical polymerization is used because of its ability to create thin films and the ease of synthesis. Films can be formed on the order of 20 nm. Electrochemical polymerization (electrochemical deposition) is performed using a three-electrode configuration in a solution of the monomer of the desired polymer, a solvent, and an electrolyte (dopant). In the case of depositing a polymer coating onto electrode a common dopant used is poly (styrene sulfonate) or PSS because of its stability and biocompatibility. Two common conductive polymers being investigated for coatings use PSS as a dopant to be electrochemically deposited onto the electrode surface (see sections below). | 0 | Theoretical and Fundamental Chemistry |
In general, industrial routes to carboxylic acids differ from those used on a smaller scale because they require specialized equipment.
* Carbonylation of alcohols as illustrated by the Cativa process for the production of acetic acid. Formic acid is prepared by a different carbonylation pathway, also starting from methanol.
* Oxidation of aldehydes with air using cobalt and manganese catalysts. The required aldehydes are readily obtained from alkenes by hydroformylation.
* Oxidation of hydrocarbons using air. For simple alkanes, this method is inexpensive but not selective enough to be useful. Allylic and benzylic compounds undergo more selective oxidations. Alkyl groups on a benzene ring are oxidized to the carboxylic acid, regardless of its chain length. Benzoic acid from toluene, terephthalic acid from para-xylene, and phthalic acid from ortho-xylene are illustrative large-scale conversions. Acrylic acid is generated from propene.
* Oxidation of ethene using silicotungstic acid catalyst.
* Base-catalyzed dehydrogenation of alcohols.
* Carbonylation coupled to the addition of water. This method is effective and versatile for alkenes that generate secondary and tertiary carbocations, e.g. isobutylene to pivalic acid. In the Koch reaction, the addition of water and carbon monoxide to alkenes or alkynes is catalyzed by strong acids. Hydrocarboxylations involve the simultaneous addition of water and CO. Such reactions are sometimes called "Reppe chemistry."
* Hydrolysis of triglycerides obtained from plant or animal oils. These methods of synthesizing some long-chain carboxylic acids are related to soap making.
* Fermentation of ethanol. This method is used in the production of vinegar.
* The Kolbe–Schmitt reaction provides a route to salicylic acid, precursor to aspirin. | 0 | Theoretical and Fundamental Chemistry |
It is hypothetically possible that two different conformers in equilibrium could react through transition states that are equal in energy. In this case, product selectivity would depend only on the distribution of ground-state conformers. In this case, both conformers would react at the same rate. | 0 | Theoretical and Fundamental Chemistry |
Atomic emission spectroscopy (AES) is a method of chemical analysis that uses the intensity of light emitted from a flame, plasma, arc, or spark at a particular wavelength to determine the quantity of an element in a sample. The wavelength of the atomic spectral line in the emission spectrum gives the identity of the element while the intensity of the emitted light is proportional to the number of atoms of the element. The sample may be excited by various methods. | 0 | Theoretical and Fundamental Chemistry |
The process of elongation is the synthesis of a copy of the DNA into messenger RNA. RNA Pol II matches complementary RNA nucleotides to the template DNA by Watson-Crick base pairing. These RNA nucleotides are ligated, resulting in a strand of messenger RNA.
Unlike DNA replication, mRNA transcription can involve multiple RNA polymerases on a single DNA template and multiple rounds of transcription (amplification of particular mRNA), so many mRNA molecules can be rapidly produced from a single copy of a gene.
Elongation also involves a proofreading mechanism that can replace incorrectly incorporated bases. In eukaryotes, this may correspond with short pauses during transcription that allow appropriate RNA editing factors to bind. These pauses may be intrinsic to the RNA polymerase or due to chromatin structure. | 1 | Applied and Interdisciplinary Chemistry |
The heat and mass analogy allows solutions for mass transfer problems to be obtained from known solutions to heat transfer problems. Its arises from similar non-dimensional governing equations between heat and mass transfer. | 1 | Applied and Interdisciplinary Chemistry |
The production of recombinant monoclonal antibodies involves repertoire cloning, CRISPR/Cas9, or phage display/yeast display technologies. Recombinant antibody engineering involves antibody production by the use of viruses or yeast, rather than mice. These techniques rely on rapid cloning of immunoglobulin gene segments to create libraries of antibodies with slightly different amino acid sequences from which antibodies with desired specificities can be selected. The phage antibody libraries are a variant of phage antigen libraries. These techniques can be used to enhance the specificity with which antibodies recognize antigens, their stability in various environmental conditions, their therapeutic efficacy and their detectability in diagnostic applications. Fermentation chambers have been used for large scale antibody production. | 1 | Applied and Interdisciplinary Chemistry |
In Amphipholis squamata, bioluminescence has been observed to come from the spines emanating from the arms from photocytes within the spinal ganglia. Acetylcholine has been found to be able to stimulate the photocytes to produce light. | 1 | Applied and Interdisciplinary Chemistry |
In common with recovery and recrystallisation, growth phenomena can be separated into continuous and discontinuous mechanisms. In the former the microstructure evolves from state A to B (in this case the grains get larger) in a uniform manner. In the latter, the changes occur heterogeneously and specific transformed and untransformed regions may be identified. Abnormal or discontinuous grain growth is characterised by a subset of grains growing at a high rate and at the expense of their neighbours and tends to result in a microstructure dominated by a few very large grains. In order for this to occur the subset of grains must possess some advantage over their competitors such as a high grain boundary energy, locally high grain boundary mobility, favourable texture or lower local second-phase particle density. | 1 | Applied and Interdisciplinary Chemistry |
On-water reactions are a group of organic reactions that take place as an emulsion in water and have an unusual reaction rate acceleration compared with (i) the same reaction in an organic solvent, or (ii) the corresponding dry media reaction. This effect has been known for many years but in 2005 researchers in the group of K. Barry Sharpless published a systematic study into this phenomenon.
The rate acceleration is found in certain Claisen rearrangements. In one typical example of this reaction at room temperature the chemical yield was found to be 100% on water after 120 h compared with 16% for the same reaction in toluene and 73% in the neat reaction.
Enhanced reactivity is also found in cycloadditions. The reaction of quadricyclane with DEAD is a 2σ + 2σ + 2π cycloaddition that on water takes place within 10 minutes at room temperature with 82% yield. The same reaction in toluene takes 24 hours at 80 °C with 70% yield. An emulsion reaction in fluorinated cyclohexane takes 36 hours and the neat reaction takes even longer (48 hours).
Other reactions with apolar reactants such as Ene reactions and Diels–Alder reactions also exhibit rate accelerations. An explanation is not available but it involves hydrogen bonding and the presence of a small amount of dissolved solute. This reaction type is of interest to green chemistry because it greatly reduces the usage of organic solvents, reaction product isolation is relatively easy, and it increases the yields and chemical purity with little extra expenditure, if not less. | 0 | Theoretical and Fundamental Chemistry |
The course of the action potential can be divided into five parts: the rising phase, the peak phase, the falling phase, the undershoot phase, and the refractory period. During the rising phase the membrane potential depolarizes (becomes more positive). The point at which depolarization stops is called the peak phase. At this stage, the membrane potential reaches a maximum. Subsequent to this, there is a falling phase. During this stage the membrane potential becomes more negative, returning towards resting potential. The undershoot, or afterhyperpolarization, phase is the period during which the membrane potential temporarily becomes more negatively charged than when at rest (hyperpolarized). Finally, the time during which a subsequent action potential is impossible or difficult to fire is called the refractory period, which may overlap with the other phases.
The course of the action potential is determined by two coupled effects. First, voltage-sensitive ion channels open and close in response to changes in the membrane voltage V. This changes the membranes permeability to those ions. Second, according to the Goldman equation, this change in permeability changes the equilibrium potential E, and, thus, the membrane voltage V. Thus, the membrane potential affects the permeability, which then further affects the membrane potential. This sets up the possibility for positive feedback, which is a key part of the rising phase of the action potential. A complicating factor is that a single ion channel may have multiple internal "gates" that respond to changes in V in opposite ways, or at different rates. For example, although raising V opens most gates in the voltage-sensitive sodium channel, it also closes the channels "inactivation gate", albeit more slowly. Hence, when V is raised suddenly, the sodium channels open initially, but then close due to the slower inactivation.
The voltages and currents of the action potential in all of its phases were modeled accurately by Alan Lloyd Hodgkin and Andrew Huxley in 1952, for which they were awarded the Nobel Prize in Physiology or Medicine in 1963. However, their model considers only two types of voltage-sensitive ion channels, and makes several assumptions about them, e.g., that their internal gates open and close independently of one another. In reality, there are many types of ion channels, and they do not always open and close independently. | 0 | Theoretical and Fundamental Chemistry |
The simple cubic Bravais lattice, with cubic primitive cell of side , has for its reciprocal a simple cubic lattice with a cubic primitive cell of side (or in the crystallographer's definition). The cubic lattice is therefore said to be self-dual, having the same symmetry in reciprocal space as in real space. | 0 | Theoretical and Fundamental Chemistry |
IUPAC has published a "Comprehensive definition of the term oxidation state (IUPAC Recommendations 2016)". It is a distillation of an IUPAC technical report "Toward a comprehensive definition of oxidation state" from 2014. The current IUPAC Gold Book definition of oxidation state is:
and the term oxidation number is nearly synonymous.
The underlying principle is that the ionic charge is "the oxidation state of an atom, after ionic approximation of its bonds", where ionic approximation means, hypothesizing that all bonds are ionic. Several criteria were considered for the ionic approximation:
# Extrapolation of the bond's polarity;
# Assignment of electrons according to the atoms contribution to the bonding Molecular orbital (MO)/ the electrons allegiance in a LCAO–MO model.
In a bond between two different elements, the bonds electrons are assigned to its main atomic contributor/higher electronegativity; in a bond between two atoms of the same element, the electrons are divided equally. This is because most electronegativity scales depend on the atoms bonding state, which makes the assignment of the oxidation state a somewhat circular argument. For example, some scales may turn out unusual oxidation states, such as −6 for platinum in , for Pauling and Mulliken scales. The dipole moments would, sometimes, also turn out abnormal oxidation numbers, such as in CO and NO, which
are oriented with their positive end towards oxygen. Therefore, this leaves the atom's contribution to the
bonding MO, the atomic-orbital energy, and from quantum-chemical calculations of charges, as the only viable criteria with cogent values for ionic approximation. However, for a simple estimate for the ionic approximation, we can use Allen electronegativities, as only that electronegativity scale is truly independent of the oxidation state, as it relates to the average valence‐electron energy of the free atom: | 0 | Theoretical and Fundamental Chemistry |
Check dams are usually less than high. and the center of the dam should be at least lower than its edges. This criterion induces a weir effect, resulting in increased water surface level upstream for some, if not all flow conditions. | 1 | Applied and Interdisciplinary Chemistry |
Channel reconfiguration involves the physical modification of the stream. Depending on the scale of a project, a channel's cross-section can be modified, and meanders can be constructed through earthworks to achieve the target stream morphology. In the U.S., such work is frequently based on the Natural Channel Design (NCD), a method developed in the 1990s. This method involves a classification of the stream to be restored based on parameters such as channel pattern and geometry, topography, slope, and bed material. This classification is followed by a design phase based on the NCD method, which includes 8 phases and 40 steps. The method relies on the construction of the desired morphology, and its stabilization with natural materials such as boulders and vegetation to limit erosion and channel mobility. | 1 | Applied and Interdisciplinary Chemistry |
Primary energy sources should not be confused with the energy system components (or conversion processes) through which they are converted into energy carriers. | 0 | Theoretical and Fundamental Chemistry |
Most well-nourished people in industrialized countries have 4 to 5 grams of iron in their bodies (~38 mg iron/kg body weight for women and ~50 mg iron/kg body for men). Of this, about is contained in the hemoglobin needed to carry oxygen through the blood (around 0.5 mg of iron per mL of blood), and most of the rest (approximately 2 grams in adult men, and somewhat less in women of childbearing age) is contained in ferritin complexes that are present in all cells, but most common in bone marrow, liver, and spleen. The liver stores of ferritin are the primary physiologic source of reserve iron in the body. The reserves of iron in industrialized countries tend to be lower in children and women of child-bearing age than in men and in the elderly. Women who must use their stores to compensate for iron lost through menstruation, pregnancy or lactation have lower non-hemoglobin body stores, which may consist of , or even less.
Of the body's total iron content, about is devoted to cellular proteins that use iron for important cellular processes like storing oxygen (myoglobin) or performing energy-producing redox reactions (cytochromes). A relatively small amount (3–4 mg) circulates through the plasma, bound to transferrin. Because of its toxicity, free soluble iron is kept in low concentration in the body.
Iron deficiency first affects the storage of iron in the body, and depletion of these stores is thought to be relatively asymptomatic, although some vague and non-specific symptoms have been associated with it. Since iron is primarily required for hemoglobin, iron deficiency anemia is the primary clinical manifestation of iron deficiency. Iron-deficient people will suffer or die from organ damage well before their cells run out of the iron needed for intracellular processes like electron transport.
Macrophages of the reticuloendothelial system store iron as part of the process of breaking down and processing hemoglobin from engulfed red blood cells. Iron is also stored as a pigment called hemosiderin, which is an ill-defined deposit of protein and iron, created by macrophages where excess iron is present, either locally or systemically, e.g., among people with iron overload due to frequent blood cell destruction and the necessary transfusions their condition calls for. If systemic iron overload is corrected, over time the hemosiderin is slowly resorbed by the macrophages. | 1 | Applied and Interdisciplinary Chemistry |
The town of Cement was established in 1902 by the Pacific Portland Cement Company and was originally named after the large deposits of high-quality limestone rock deposits found in the area. This limestone was ideal for the lime that was needed for the production of Portland cement produced by the company at Cement.
Enormous conveyors, rock crushers, tube cement mills, and rotary kilns were created to process the raw quarried limestone.
The town also had its own open pit clay and gypsum mines with clay and gypsum being necessary components in the finished Portland cement the plant produced.
The establishment of the cement industry in Cement brought a large influx of workers to the area, and the town quickly grew into a thriving community of people with a strong economy. It became more populous than the three nearest cities combinedFairfield, Vacaville and Suisun City.
The cement industry was the lifeblood of Cement for many years, and the town prospered as a result. The population of the town grew steadily to 500 people, and businesses and services were established to support the needs of the growing community. This included the three-story Golden Gate Hotel, hospital, restaurant, bar, livery stable, post office, telephone exchange, park, baseball diamond, general store, fire station, churches, and a grade school. | 1 | Applied and Interdisciplinary Chemistry |
Enhanced growth and elevated photosynthetic amino acid is associated with plastidial adenylate kinase deficiency in Arabidopsis thaliana. | 1 | Applied and Interdisciplinary Chemistry |
Phenol–chloroform extraction is a liquid-liquid extraction technique in molecular biology used to separate nucleic acids from proteins and lipids. | 1 | Applied and Interdisciplinary Chemistry |
A large number of chemical compounds are known to exhibit one or several liquid crystalline phases. Despite significant differences in chemical composition, these molecules have some common features in chemical and physical properties. There are three types of thermotropic liquid crystals: discotic, conic (bowlic), and rod-shaped molecules. Discotics are disc-like molecules consisting of a flat core of adjacent aromatic rings, whereas the core in a conic LC is not flat, but is shaped like a rice bowl (a three-dimensional object). This allows for two dimensional columnar ordering, for both discotic and conic LCs. Rod-shaped molecules have an elongated, anisotropic geometry which allows for preferential alignment along one spatial direction.
*The molecular shape should be relatively thin, flat or conic, especially within rigid molecular frameworks.
*The molecular length should be at least 1.3 nm, consistent with the presence of long alkyl group on many room-temperature liquid crystals.
*The structure should not be branched or angular, except for the conic LC.
*A low melting point is preferable in order to avoid metastable, monotropic liquid crystalline phases. Low-temperature mesomorphic behavior in general is technologically more useful, and alkyl terminal groups promote this.
An extended, structurally rigid, highly anisotropic shape seems to be the main criterion for liquid crystalline behavior, and as a result many liquid crystalline materials are based on benzene rings. | 0 | Theoretical and Fundamental Chemistry |
In aerosol mass spectrometry, one of the ionization techniques consists in firing a laser to individual droplets. These systems are called single particle mass spectrometers (SPMS). The sample may optionally be mixed with a MALDI matrix prior to aerosolization. | 1 | Applied and Interdisciplinary Chemistry |
At the time of the Industrial Revolution, the fact that each state had its own system of weights and measures became increasingly problematic. Serious work on a "scientific" system was started in France under Louis XVI, and completed in 1799 (after the French Revolution) with its implementation. The French population, however, was initially unhappy with the new system. In 1812, Napoleon Bonaparte reintroduced some of the old measurements, but in a modified form that was defined with respect to the metric system. This was finally abolished in 1837 and became illegal in 1840.
Due to the large expansion of the First French Empire under Napoleon I, French metrication also affected what would be (parts of) France's neighbour countries after the Congress of Vienna.
The Netherlands were partially metricated when they were French, in the years 1810–1813. With full metrication, effective January 1821, the Netherlands reformed the . The apothecaries new pound was 375.00 g. Apart from rounding issues concerning the subdivisions, this corresponded exactly to the French . (The reform was not followed in the north German city of Lübeck, which continued to use the .) In Belgium, apothecaries weight was metricated effective 1856.
From 1803 to 1815, all German regions west of the River Rhine were French, organised in the Roer, Sarre, Rhin-et-Moselle, and Mont-Tonnerre. As a result of the Congress of Vienna these became part of various German states. A large part of the Palatinate fell to Bavaria, but having the metric system it was excepted from the Bavarian reform of weights and measures. | 1 | Applied and Interdisciplinary Chemistry |
Many valves are controlled manually with a handle attached to the stem. If the handle is turned ninety degrees between operating positions, the valve is called a quarter-turn valve. Butterfly, ball valves, and plug valves are often quarter-turn valves. If the handle is circular with the stem as the axis of rotation in the center of the circle, then the handle is called a handwheel. Valves can also be controlled by actuators attached to the stem. They can be electromechanical actuators such as an electric motor or solenoid, pneumatic actuators which are controlled by air pressure, or hydraulic actuators which are controlled by the pressure of a liquid such as oil or water. Actuators can be used for the purposes of automatic control such as in washing machine cycles, remote control such as the use of a centralised control room, or because manual control is too difficult such as when the valve is very large. Pneumatic actuators and hydraulic actuators need pressurised air or liquid lines to supply the actuator: an inlet line and an outlet line. Pilot valves are valves which are used to control other valves. Pilot valves in the actuator lines control the supply of air or liquid going to the actuators.
The fill valve in a toilet water tank is a liquid level-actuated valve. When a high water level is reached, a mechanism shuts the valve which fills the tank.
In some valve designs, the pressure of the flow fluid itself or pressure difference of the flow fluid between the ports automatically controls flow through the valve. | 1 | Applied and Interdisciplinary Chemistry |
In medicine, nephelometry is used to measure immune function. It is also used in clinical microbiology, for preparation of a standardized inoculum (McFarland suspension) for antimicrobial susceptibility testing. | 0 | Theoretical and Fundamental Chemistry |
Synthetic screen media is used where wear life is an issue. Large producers such as mines or huge quarries use them to reduce the frequency of having to stop the plant for screen deck maintenance. Rubber is also used as a very resistant high-impact screen media material used on the top deck of a scalper screen. To compete with rubber screen media fabrication, polyurethane manufacturers developed screen media with lower Shore Hardness. To compete with self-cleaning screen media that is still primarily available in tensioned cloth, synthetic screen media manufacturers also developed membrane screen panels, slotted opening panels and diamond opening panels. Due to the 7-degree demoulding angle, polyurethane screen media users can experience granulometry changes of product during the wear life of the panel. | 1 | Applied and Interdisciplinary Chemistry |
A sand bath is a common piece of laboratory equipment made from a container filled with heated sand. It is used to evenly heat another container, most often during a chemical reaction.
A sand bath is most commonly used in conjunction with a hot plate or heating mantle. A beaker is filled with sand or metal pellets (called shot) and is placed on the plate or mantle. The reaction vessel is then partially covered by sand or pellets. The sand or shot then conducts the heat from the plate to all sides of the reaction vessel.
This technique allows a reaction vessel to be heated throughout with minimal stirring, as opposed to heating the bottom of the vessel and waiting for convection to heat the remainder, cutting down on both the duration of the reaction and the possibility of side reactions that may occur at higher temperatures.
A variation on this theme is the water bath in which the sand is replaced with water. It can be used to keep a reaction vessel at the temperature of boiling water until all water is evaporated (see Standard enthalpy change of vaporization).
Sand baths are one of the oldest known pieces of laboratory equipment, having been used by the alchemists. In Arabic alchemy, a sand bath was known as a qadr. In Latin alchemy, a sand bath was called balneum siccum, balneum cineritium, or balneum arenosum. | 0 | Theoretical and Fundamental Chemistry |
Racemic tartaric acid can be prepared in a multistep reaction from maleic acid. In the first step, the maleic acid is epoxidized by hydrogen peroxide using potassium tungstate as a catalyst.
:HOCCHCOH + HO → OCH(COH)
In the next step, the epoxide is hydrolyzed.
:OCH(COH) + HO → (HOCH)(COH) | 0 | Theoretical and Fundamental Chemistry |
In second order reactions, the rate of reaction is proportional to the square of the concentration. By integrating this rate, it can be shown that the concentration of the reactant decreases following this formula:
We replace for in order to calculate the half-life of the reactant and isolate the time of the half-life ():This shows that the half-life of second order reactions depends on the initial concentration and rate constant. | 0 | Theoretical and Fundamental Chemistry |
Dale Raymond Corson (April 5, 1914 – March 31, 2012) was an American physicist and academic administrator who was the eighth president of Cornell University. | 1 | Applied and Interdisciplinary Chemistry |
SAMP can be prepared in six steps from (S)-proline, and RAMP can be prepared in six steps from (R)-glutamic acid.
<br /> | 0 | Theoretical and Fundamental Chemistry |
Structural considerations play an important role in the proper design of copper applications. The primary concern is about thermal effects: movement and stresses related to temperature variations. Thermal effects can be accommodated by preventing movement and resisting cumulative stresses or by allowing movement at predetermined locations, thereby relieving anticipated thermal stresses.
Wind resistance is an important structural consideration. Underwriters Laboratories (UL) conducted a series of tests on copper roof systems. A copper standing-seam roof with test panels was subjected to the UL 580, Uplift Resistance Test Protocol. The copper system did not exhibit unusual deformation, the cleats did not loosen from the structural deck, and the system passed UL 580 requirements. UL-90 designation was granted. | 1 | Applied and Interdisciplinary Chemistry |
Soil amendments such as fertilizers and manures can cause soil acidification. Sulfur based fertilizers can be highly acidifying, examples include elemental sulfur and iron sulfate while others like potassium sulfate have no significant effect on soil pH. While most nitrogen fertilizers have an acidifying effect, ammonium-based nitrogen fertilizers are more acidifying than other nitrogen sources. Ammonia-based nitrogen fertilizers include ammonium sulfate, diammonium phosphate, monoammonium phosphate, and ammonium nitrate. Organic nitrogen sources, such as urea and compost, are less acidifying. Nitrate sources which have little or no ammonium, such as calcium nitrate, magnesium nitrate, potassium nitrate, and sodium nitrate, are not acidifying. | 0 | Theoretical and Fundamental Chemistry |
The η-notation is encountered in many coordination compounds:
*Side-on bonding of molecules containing σ-bonds like H:
**W(CO)(PPr)(η-H)
*Side-on bonded ligands containing multiple bonded atoms, e.g. ethylene in Zeise's salt or with fullerene, which is bonded through donation of the π-bonding electrons:
**K[PtCl(η-CH)]HO
*Related complexes containing bridging π-ligands:
**(μ-η:η-CH)Co(CO) and (Cp*Sm)(μ-η:η-N)
**Dioxygen in bis{(trispyrazolylborato)copper(II)}(μ-η:η-O),
::Note that with some bridging ligands, an alternative bridging mode is observed, e.g. κ,κ, like in (MeSiCH)V(μ-N-κ(N),κ(N′))V(CHSiMe) contains a bridging dinitrogen molecule, where the molecule is end-on coordinated to the two metal centers (see hapticity vs. denticity).
*The bonding of π-bonded species can be extended over several atoms, e.g. in allyl, butadiene ligands, but also in cyclopentadienyl or benzene rings can share their electrons.
*Apparent violations of the 18-electron rule sometimes are explicable in compounds with unusual hapticities:
**The 18-VE complex (η-CH)Fe(η-CH)(CO) contains one η bonded cyclopentadienyl, and one η bonded cyclopentadienyl.
**Reduction of the 18-VE compound [Ru(η-CMe)] (where both aromatic rings are bonded in an η-coordination), results in another 18-VE compound: [Ru(η-CMe)(η-CMe)].
*Examples of polyhapto coordinated heterocyclic and inorganic rings: Cr(η-CHS)(CO) contains the sulfur heterocycle thiophene and Cr(η-BNMe)(CO) contains a coordinated inorganic ring (BN ring). | 0 | Theoretical and Fundamental Chemistry |
Highly malignant tumors rely heavily on anaerobic glycolysis (metabolism of glucose to lactic acid even under ample tissue oxygen; Warburg effect) and thus need to efflux lactic acid via MCTs to the tumor micro-environment to maintain a robust glycolytic flux and to prevent the tumor from being "pickled to death". The MCTs have been successfully targeted in pre-clinical studies using RNAi and a small-molecule inhibitor alpha-cyano-4-hydroxycinnamic acid (ACCA; CHC) to show that inhibiting lactic acid efflux is a very effective therapeutic strategy against highly glycolytic malignant tumors.
In some tumor types, growth and metabolism relies on the exchange of lactate between glycolytic and rapidly respiring cells. This is of particular importance during tumor cell development when cells often undergo anaerobic metabolism, as described by the Warburg effect. Other cells in the same tumor may have access to or recruit sources of oxygen (via angiogenesis), allowing it to undergo aerobic oxidation. The lactate shuttle could occur as the hypoxic cells anaerobically metabolize glucose and shuttle the lactate via MCT to the adjacent cells capable of using the lactate as a substrate for oxidation. Investigation into how MCT-mediated lactate exchange in targeted tumor cells can be inhibited, therefore depriving cells of key energy sources, could lead to promising new chemotherapeutics.
Additionally, lactate has been shown to be a key factor in tumor angiogenesis. Lactate promotes angiogenesis by upregulating HIF-1 in endothelial cells. Thus a promising target of cancer therapy is the inhibition of lactate export, through MCT-1 blockers, depriving developing tumors of an oxygen source. | 1 | Applied and Interdisciplinary Chemistry |
HRM analysis is performed on double stranded DNA samples. Typically the user will use polymerase chain reaction (PCR) prior to HRM analysis to amplify the DNA region in which their mutation of interest lies. In the sample tube there are now many copies of the DNA region of interest. This region that is amplified is known as the amplicon.
After the PCR process the HRM analysis begins. The process is simply a precise warming of the amplicon DNA from around 50 ˚C up to around 95 ˚C. At some point during this process, the melting temperature of the amplicon is reached and the two strands of DNA separate or "melt" apart.
The key to HRM is to monitor this separation of strands in real-time. This is achieved by using a fluorescent dye. The dyes that are used for HRM are known as intercalating dyes and have a unique property. They bind specifically to double-stranded DNA and when they are bound they fluoresce brightly. In the absence of double stranded DNA they have nothing to bind to and they only fluoresce at a low level.
At the beginning of the HRM analysis there is a high level of fluorescence in the sample because of the billions of copies of the amplicon. But as the sample is heated up and the two strands of the DNA melt apart, presence of double stranded DNA decreases and thus fluorescence is reduced. The HRM machine has a camera that watches this process by measuring the fluorescence. The machine then simply plots this data as a graph known as a melt curve, showing the level of fluorescence vs the temperature: | 1 | Applied and Interdisciplinary Chemistry |
One of the earliest steps towards atomic physics was the recognition that matter was composed
of atoms. It forms a part of the texts written in 6th century BC to 2nd century BC, such as those of Democritus or written by . This theory was later developed in the modern sense of the basic unit of a chemical element by the British chemist and physicist John Dalton in the 18th century. At this stage, it wasn't clear what atoms were, although they could be described and classified by their properties (in bulk). The invention of the periodic system of elements by Dmitri Mendeleev was another great step forward.
The true beginning of atomic physics is marked by the discovery of spectral lines and attempts to describe the phenomenon, most notably by Joseph von Fraunhofer. The study of these lines led to the Bohr atom model and to the birth of quantum mechanics. In seeking to explain atomic spectra, an entirely new mathematical model of matter was revealed. As far as atoms and their electron shells were concerned, not only did this yield a better overall description, i.e. the atomic orbital model, but it also provided a new theoretical basis for chemistry
(quantum chemistry) and spectroscopy.
Since the Second World War, both theoretical and experimental fields have advanced at a rapid pace. This can be attributed to progress in computing technology, which has allowed larger and more sophisticated models of atomic structure and associated collision processes. Similar technological advances in accelerators, detectors, magnetic field generation and lasers have greatly assisted experimental work. | 0 | Theoretical and Fundamental Chemistry |
Family-based, adoption, and twin studies have indicated that there is a strong (50%) heritable component to vulnerability to substance abuse addiction.
Especially among genetically vulnerable individuals, repeated exposure to a drug of abuse in adolescence or adulthood causes addiction by inducing stable downregulation or upregulation in expression of specific genes and microRNAs through epigenetic alterations. Such downregulation or upregulation has been shown to occur in the brain's reward regions, such as the nucleus accumbens. (See, for example, Epigenetics of cocaine addiction.) | 1 | Applied and Interdisciplinary Chemistry |
The vaporizing droplet (droplet vaporization) problem is a challenging issue in fluid dynamics. It is part of many engineering situations involving the transport and computation of sprays: fuel injection, spray painting, aerosol spray, flashing releases… In most of these engineering situations there is a relative motion between the droplet and the surrounding gas. The gas flow over the droplet has many features of the gas flow over a rigid sphere: pressure gradient, viscous boundary layer, wake. In addition to these common flow features one can also mention the internal liquid circulation phenomenon driven by surface-shear forces and the boundary layer blowing effect.
One of the key parameter which characterizes the gas flow over the droplet is the droplet Reynolds number based on the relative velocity, droplet diameter and gas phase properties. The features of the gas flow have a critical impact on the exchanges of mass, momentum and energy between the gas and the liquid phases and thus, they have to be properly accounted for in any vaporizing droplet model.
As a first step it is worth investigating the simple case where there is no relative motion between the droplet and the surrounding gas. It will provide some useful insights on the physics involved in the vaporizing droplet problem. In a second step models used in engineering situations where a relative motion between the droplet and the surrounding exists are presented. | 1 | Applied and Interdisciplinary Chemistry |
Alkyl-lithium compounds are stored under inert gas to prevent loss of activity and for reasons of safety. n-BuLi reacts violently with water:
:CHLi + HO → CH + LiOH
This is an exergonic and highly exothermic reaction. If oxygen is present the butane produced may ignite.
BuLi also reacts with CO to give lithium pentanoate:
:CHLi + CO → CHCOLi | 0 | Theoretical and Fundamental Chemistry |
A bow wave is the wave that forms at the bow of a ship when it moves through the water. As the bow wave spreads out, it defines the outer limits of a ship's wake. A large bow wave slows the ship down, is a risk to smaller boats, and in a harbor can damage shore facilities and moored ships. Therefore, ship hulls are generally designed to produce as small a bow wave as possible. | 1 | Applied and Interdisciplinary Chemistry |
Enantioselective benzylic functionalization methods use the complexed chromium tri(carbonyl) moiety essentially as a chiral auxiliary. Approach of the functionalizing reagent anti to the ----chromium tri(carbonyl) fragment leads to a single diastereomer of the product complex. After removal of the chromium group with light or an oxidizing agent such as iodine, a nearly enantiopure product remains. See the Scope and Limitations section below for several methods for diastereoselective benzylic functionalization. | 0 | Theoretical and Fundamental Chemistry |
By using the S&S algorithm, mutations and genes that cause many different forms of cancer have been discovered. For example, genes causing commonly occurring cancers including breast cancer, ovarian cancer, colorectal cancer, leukemia, head and neck cancers, prostate cancer, retinoblastoma, squamous cell carcinoma, gastrointestinal cancer, melanoma, liver cancer, Lynch syndrome, skin cancer, and neurofibromatosis have been found. In addition, splicing mutations in genes causing less commonly known cancers including gastric cancer, gangliogliomas, Li-Fraumeni syndrome, Loeys–Dietz syndrome, Osteochondromas (bone tumor), Nevoid basal cell carcinoma syndrome, and Pheochromocytomas have been identified.
Specific mutations in different splice sites in various genes causing breast cancer (e.g., BRCA1, PALB2), ovarian cancer (e.g., SLC9A3R1, COL7A1, HSD17B7), colon cancer (e.g., APC, MLH1, DPYD), colorectal cancer (e.g., COL3A1, APC, HLA-A), skin cancer (e.g., COL17A1, XPA, POLH), and Fanconi anemia (e.g., FANC, FANA) have been uncovered. The mutations in the donor and acceptor splice sites in different genes causing a variety of cancers that have been identified by S&S are shown in Table 1. | 1 | Applied and Interdisciplinary Chemistry |
Many metal alkoxides thermally decompose in the range ≈100–300 °C. Depending on process conditions, this thermolysis can afford nanosized powders of oxide or metallic phases. This approach is a basis of processes of fabrication of functional materials intended for aircraft, space, electronic fields, and chemical industry: individual oxides, their solid solutions, complex oxides, powders of metals and alloys active towards sintering. Decomposition of mixtures of mono- and heterometallic alkoxide derivatives has also been examined. This method represents a prospective approach possessing an advantage of capability of obtaining functional materials with increased phase and chemical homogeneity and controllable grain size (including the preparation of nanosized materials) at relatively low temperature (less than 500−900 °C) as compared with the conventional techniques. | 0 | Theoretical and Fundamental Chemistry |
When choosing a suitable sewage treatment process, decision makers need to take into account technical and economical criteria. Therefore, each analysis is site-specific. A life cycle assessment (LCA) can be used, and criteria or weightings are attributed to the various aspects. This makes the final decision subjective to some extent. A range of publications exist to help with technology selection.
In industrialized countries, the most important parameters in process selection are typically efficiency, reliability, and space requirements. In developing countries, they might be different and the focus might be more on construction and operating costs as well as process simplicity.
Choosing the most suitable treatment process is complicated and requires expert inputs, often in the form of feasibility studies. This is because the main important factors to be considered when evaluating and selecting sewage treatment processes are numerous. They include: process applicability, applicable flow, acceptable flow variation, influent characteristics, inhibiting or refractory compounds, climatic aspects, process kinetics and reactor hydraulics, performance, treatment residuals, sludge processing, environmental constraints, requirements for chemical products, energy and other resources; requirements for personnel, operating and maintenance; ancillary processes, reliability, complexity, compatibility, area availability.
With regards to environmental impacts of sewage treatment plants the following aspects are included in the selection process: Odors, vector attraction, sludge transportation, sanitary risks, air contamination, soil and subsoil contamination, surface water pollution or groundwater contamination, devaluation of nearby areas, inconvenience to the nearby population. | 1 | Applied and Interdisciplinary Chemistry |
Some semicarbazones, such as nitrofurazone, and thiosemicarbazones are known to have anti-viral and anti-cancer activity, usually mediated through binding to copper or iron in cells. Many semicarbazones are crystalline solids, useful for the identification of the parent aldehydes/ketones by melting point analysis.
A thiosemicarbazone is an analog of a semicarbazone which contains a sulfur atom in place of the oxygen atom. | 0 | Theoretical and Fundamental Chemistry |
The model was initially developed by Gross&Harris and Gormont, the basic idea is as follows:
The onset of dynamic stall is assumed to occur at
where is the critical AoA of dynamic stall, is static stall AoA and is given by
where is the time derivative of AoA, is the blade chord, and is the free-stream velocity. The function is empirical, depends on geometry and Mach number and is different for lift and pitching moment.
The airloads coefficients are constructed from static data using an equivalent angle of attack derived from Theodorsen's theory at the appropriate reduced frequency of the forcing and a reference angle as follows:
, , , where is the center point of rotation.
A comprehensive analysis of a helicopter rotor using this model is presented in the reference. | 1 | Applied and Interdisciplinary Chemistry |
As an example, in a typical pump-probe experimental apparatus, an attosecond (XUV-SXR) pulse and an intense ( W/cm) low-frequency infrared pulse with a time duration of few to tens femtoseconds are collinearly focused on the studied sample.
At this point, by varying the delay of the attosecond pulse, which could be pump/probe depending on the experiment, with respect to the IR pulse (probe/pump), the desired physical observable is recorded.
The subsequent challenge is to interpret the collected data and retrieve fundamental information on the hidden dynamics and quantum processes occurring in the sample. This can be achieved with advanced theoretical tools and numerical calculations.
By exploiting this experimental scheme, several kinds of dynamics can be explored in atoms, molecules and solids; typically light-induced dynamics and out-of-equilibrium excited states within attosecond time-resolution. | 0 | Theoretical and Fundamental Chemistry |
The mitochondrial permeability transition pore (mPTP or MPTP; also referred to as PTP, mTP or MTP) is a protein that is formed in the inner membrane of the mitochondria under certain pathological conditions such as traumatic brain injury and stroke. Opening allows increase in the permeability of the mitochondrial membranes to molecules of less than 1500 daltons in molecular weight. Induction of the permeability transition pore, mitochondrial membrane permeability transition (mPT or MPT), can lead to mitochondrial swelling and cell death through apoptosis or necrosis depending on the particular biological setting. | 1 | Applied and Interdisciplinary Chemistry |
When there is a stimulus, the CRP level can increase 10,000-fold from less than 50 μg/L to more than 500 mg/L. Its concentration can increase to 5 mg/L by 6 hours and peak at 48 hours. The plasma half-life of CRP is 19 hours, and is constant in all medical conditions. Therefore, the only factor that affects the blood CRP concentration is its production rate, which increases with inflammation, infection, trauma, necrosis, malignancy, and allergic reactions. Other inflammatory mediators that can increase CRP are TGF beta 1, and tumor necrosis factor alpha. In acute inflammation, CRP can increase as much as 50 to 100 mg/L within 4 to 6 hours in mild to moderate inflammation or an insult such as skin infection, cystitis, or bronchitis. It can double every 8 hours and reaches its peak at 36 to 50 hours following injury or inflammation. CRP between 100 and 500 mg/L is considered highly predictive of inflammation due to bacterial infection. Once inflammation subsides, CRP level falls quickly because of its relatively short half-life. | 1 | Applied and Interdisciplinary Chemistry |
Amoxicillin is an antibiotic medication belonging to the aminopenicillin class of the penicillin family. The drug is used to treat bacterial infections such as middle ear infection, strep throat, pneumonia, skin infections, odontogenic infections, and urinary tract infections. It is taken by mouth, or less commonly by injection.
Common adverse effects include nausea and rash. It may also increase the risk of yeast infections and, when used in combination with clavulanic acid, diarrhea. It should not be used in those who are allergic to penicillin. While usable in those with kidney problems, the dose may need to be decreased. Its use in pregnancy and breastfeeding does not appear to be harmful. Amoxicillin is in the β-lactam family of antibiotics.
Amoxicillin was discovered in 1958 and came into medical use in 1972. Amoxil was approved for medical use in the United States in 1974, and in the United Kingdom in 1977. It is on the (WHO) World Health Organization's List of Essential Medicines. It is one of the most commonly prescribed antibiotics in children. Amoxicillin is available as a generic medication. In 2021, it was the 38th most commonly prescribed medication in the United States, with more than 16million prescriptions. | 0 | Theoretical and Fundamental Chemistry |
Of primary interest among the intracellular components are microbial enzymes: catalase, amylase, protease, pectinase, cellulase, hemicellulase, lipase, lactase, streptokinase and many others. Recombinant proteins, such as insulin, hepatitis B vaccine, interferon, granulocyte colony-stimulating factor, streptokinase and others are also made this way. The largest difference between this process and the others is that the cells must be ruptured (lysed) at the end of fermentation, and the environment must be manipulated to maximize the amount of the product. Furthermore, the product (typically a protein) must be separated from all of the other cellular proteins in the lysate to be purified. | 1 | Applied and Interdisciplinary Chemistry |
The Gaia hypothesis (), also known as the Gaia theory, Gaia paradigm, or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet.
The Gaia hypothesis was formulated by the chemist James Lovelock and co-developed by the microbiologist Lynn Margulis in the 1970s. Following the suggestion by his neighbour, novelist William Golding, Lovelock named the hypothesis after Gaia, the primordial deity who personified the Earth in Greek mythology. In 2006, the Geological Society of London awarded Lovelock the Wollaston Medal in part for his work on the Gaia hypothesis.
Topics related to the hypothesis include how the biosphere and the evolution of organisms affect the stability of global temperature, salinity of seawater, atmospheric oxygen levels, the maintenance of a hydrosphere of liquid water and other environmental variables that affect the habitability of Earth.
The Gaia hypothesis was initially criticized for being teleological and against the principles of natural selection, but later refinements aligned the Gaia hypothesis with ideas from fields such as Earth system science, biogeochemistry and systems ecology. Even so, the Gaia hypothesis continues to attract criticism, and today many scientists consider it to be only weakly supported by, or at odds with, the available evidence. | 0 | Theoretical and Fundamental Chemistry |
Initiation of translation in bacteria involves the assembly of the components of the translation system, which are: the two ribosomal subunits (50S and 30S subunits); the mature mRNA to be translated; the tRNA charged with N-formylmethionine (the first amino acid in the nascent peptide); guanosine triphosphate (GTP) as a source of energy, and the three prokaryotic initiation factors IF1, IF2, and IF3, which help the assembly of the initiation complex. Variations in the mechanism can be anticipated.
The ribosome has three active sites: the A site, the P site, and the E site. The A site is the point of entry for the aminoacyl tRNA (except for the first aminoacyl tRNA, which enters at the P site). The P site is where the peptidyl tRNA is formed in the ribosome. And the E site which is the exit site of the now uncharged tRNA after it gives its amino acid to the growing peptide chain. | 1 | Applied and Interdisciplinary Chemistry |
The MONIAC Computer built in 1949 was a fluid-based analogue computer used for teaching economic principles as it could recreate complex simulations that digital computers could not at the time. Twelve to fourteen were built and acquired by businesses and teaching establishments.
The FLODAC Computer was built in 1964 as a proof of concept fluid-based digital computer.
Fluidic components appear in some hydraulic and pneumatic systems, including some automotive automatic transmissions. As electronic digital logic has become more accepted in industrial control, the role of fluidics in industrial control has declined.
In the consumer market, fluidically controlled products are increasing in both popularity and presence, installed in items ranging from toy spray guns through shower heads and hot tub jets; all provide oscillating or pulsating streams of air or water. Logic-enabled textiles for applications in wearable technology has also been researched.
Fluid logic can be used to create a valve with no moving parts such as in some anaesthetic machines.
Fluidic oscillators were used in the design of pressure-triggered, 3D printable, emergency ventilators for the COVID-19 pandemic.
Fluidic amplifiers are used to generate ultrasound for non-destructive testing by quickly switching pressurized air from one outlet to another.
Fluidic injection is being researched for use in aircraft to control direction, in two ways: circulation control and thrust vectoring. In both, larger more complex mechanical parts are replaced by fluidic systems, in which larger forces in fluids are diverted by smaller jets or flows of fluid intermittently, to change the direction of vehicles. In circulation control, near the trailing edges of wings, aircraft flight control systems such as ailerons, elevators, elevons, flaps, and flaperons are replaced by openings, usually rows of holes, or elongated slots, which emit fluid flows. In thrust vectoring, in jet engine nozzles, swiveling parts are replaced by openings which inject fluid flows into jets. Such systems divert thrust via fluid effects. Tests show that air forced into a jet engine exhaust stream can deflect thrust up to 15 degrees. In such uses, fluidics is desirable for lower: mass, cost (up to 50% less), drag (up to 15% less during use), inertia (for faster, stronger control response), complexity (mechanically simpler, fewer or no moving parts or surfaces, less maintenance), and radar cross section for stealth. This will likely be used in many unmanned aerial vehicles (UAVs), 6th generation fighter aircraft, and ships.
, at least two countries are known to be researching fluidic control. In Britain, BAE Systems has tested two fluidically controlled unmanned aircraft, one starting in 2010 named Demon, and another starting in 2017 named MAGMA, with the University of Manchester. In the United States, the Defense Advanced Research Projects Agency (DARPA) program named Control of Revolutionary Aircraft with Novel Effectors (CRANE) seeks "... to design, build, and flight test a novel X-plane that incorporates active flow control (AFC) as a primary design consideration. ... In 2023, the aircraft received its official designation as X-65." In winter 2024, construction began, at Boeing subsidiary Aurora Flight Sciences. In summer 2025, flight testing is to start.
Octobot, a 2016 proof of concept soft-bodied autonomous robot containing a microfluidic logic circuit, has been developed by researchers at Harvard University's Wyss Institute for Biologically Inspired Engineering. | 1 | Applied and Interdisciplinary Chemistry |
Custom capture panels tailored to specific cancer types or personalized selectors were utilized in EPIC-seq. The capture panels targeted transcription start site regions of genes of interest. Enrichment for EPIC-seq was performed following established laboratory protocols. Subsequently, hybridization captures were pooled, and the pooled samples underwent sequencing using short read sequencing. | 1 | Applied and Interdisciplinary Chemistry |
* Methanethiol – CHSH [methyl mercaptan]
* Ethanethiol – CHSH [ethyl mercaptan]
* 1-Propanethiol – CHSH [n-propyl mercaptan]
* 2-Propanethiol – CHCH(SH)CH [2C3 mercaptan]
* Allyl mercaptan CH=CHCHSH [2-propenethiol]
* Butanethiol – CHSH [n-butyl mercaptan]
* tert-Butyl mercaptan – (CH)CSH [t-butyl mercaptan]
* Pentanethiols – CHSH [pentyl mercaptan]
* Thiophenol – CHSH
* Dimercaptosuccinic acid
* Thioacetic acid
* Coenzyme A
* Glutathione
* Metallothionein
* Cysteine
* 2-Mercaptoethanol
* Dithiothreitol/dithioerythritol (an epimeric pair)
* 2-Mercaptoindole
* Grapefruit mercaptan
* Furan-2-ylmethanethiol
* 3-Mercaptopropane-1,2-diol
* 3-Mercapto-1-propanesulfonic acid
* 1-Hexadecanethiol
* Pentachlorobenzenethiol | 0 | Theoretical and Fundamental Chemistry |
Common adverse drug reactions (ADRs) associated with pseudoephedrine therapy include central nervous system stimulation, insomnia, nervousness, excitability, dizziness and anxiety. Infrequent ADRs include tachycardia or palpitations. Rarely, pseudoephedrine therapy may be associated with mydriasis (dilated pupils), hallucinations, arrhythmias, hypertension, seizures and ischemic colitis; as well as severe skin reactions known as recurrent pseudo-scarlatina, systemic contact dermatitis, and nonpigmenting fixed drug eruption. Pseudoephedrine, particularly when combined with other drugs including narcotics, may also play a role in the precipitation of episodes of paranoid psychosis. It has also been reported that pseudoephedrine, among other sympathomimetic agents, may be associated with the occurrence of stroke. | 0 | Theoretical and Fundamental Chemistry |
Combining plants and fish in a RAS is referred to as aquaponics. In this type of system ammonia produced by the fish is not only converted to nitrate but is also removed by the plants from the water. In an aquaponics system fish effectively fertilize the plants, this creates a closed looped system where very little waste is generated and inputs are minimized. Aquaponics provides the advantage of being able to harvest and sell multiple crops. Contradictory views exist on the suitability and safety of RAS effluents to sustain plant growth under aquaponics condition. Future conversions, rather ‘upgrades’, of operational RAS farms to semi-commercial Aquaponic ventures should not be deterred by nutrient insufficiency or nutrient safety arguments. Incentivizing RAS farm wastes through semi-commercial aquaponics is encouraged. Nutrients locked in RAS wastewater and sludge have sufficient and safe nutrients to sustain plant growth under aquaponics condition. | 1 | Applied and Interdisciplinary Chemistry |
ClSOH reacts violently with water to yield sulfuric acid and hydrogen chloride, commonly seen as vapors fuming from the liquid:
:ClSOH + HO → HSO + HCl
Precautions should be taken, such as proper ventilation associated with HCl. | 0 | Theoretical and Fundamental Chemistry |
Edwin "Ed" Vedejs was born in Riga, Latvia to Velta (nee Robežnieks) and Nikolajs Vedējs. Not long after his birth, the German occupation of Latvia during World War II occurred followed by the Soviet re-occupation of Latvia in 1944. These events forced his family to settle in the Fischbach Displaced Persons camp in Germany for six years. In 1950, they emigrated to the United States and first settled in Fort Atkinson, WI. They eventually moved to Grand Rapids, MI.
He attended Grand Rapids Junior College for a few years before transferring to the University of Michigan where he received a BS degree in 1962. He moved to the University of Wisconsin and joined the group of Professor for his Ph.D. studies (Progress toward the total synthesis of terramycin), which he completed in 1966. From 1966–67, he did post-doctoral research on the total synthesis of prostaglandins at Harvard University in the laboratory of Nobel Laureate Professor E. J. Corey. | 0 | Theoretical and Fundamental Chemistry |
Any protein that can be split into two parts and reconstituted non-covalently to form a functional protein may be used in a PCA. The two fragments however have low affinity for each other and must be brought together by other interacting proteins fused to them (often called "bait" and "prey" since the bait protein can be used to identify a prey protein, see figure). The protein that produces a detectable readout is called "reporter". Usually enzymes which confer resistance to nutrient deprivation or antibiotics, such as dihydrofolate reductase or beta-lactamase respectively, or proteins that give colorimetric or fluorescent signals are used as reporters. When fluorescent proteins are reconstituted the PCA is called Bimolecular fluorescence complementation assay. The following proteins have been used in split protein PCAs:
*Beta-lactamase
*Dihydrofolate reductase (DHFR)
*Focal adhesion kinase (FAK)
*Gal4, a yeast transcription factor (as in the classical yeast two-hybrid system)
*GFP (split-GFP), e.g. EGFP (enhanced green fluorescent protein)
*Horseradish peroxidase
*Infrared fluorescent protein IFP1.4, an engineered chromophore-binding domain (CBD) of a bacteriophytochrome from Deinococcus radiodurans
*LacZ (beta-galactosidase)
*Luciferase, including ReBiL (recombinase enhanced bimolecular luciferase) and Gaussia princeps luciferase. Commercial products using luciferase include NanoLuc and NanoBIT. A modification has also been developed for lipid droplet-associated interactions.
*TEV (Tobacco etch virus protease)
*Ubiquitin | 1 | Applied and Interdisciplinary Chemistry |
Museomics is the study of genomic data obtained from ancient DNA (aDNA) and historic DNA (hDNA) specimens in museum collections.
Early research in this area focused on short sequences of DNA from mitochondrial genes, but sequencing of whole genomes has become possible.
Next-generation sequencing (NGS) and high-throughput sequencing (HTS) methods can be applied to the analysis of genetic datasets extracted from collections materials. Such techniques have been described as a "third revolution in sequencing technology". Like radiocarbon dating, the techniques of museomics are a transformative technology. Results are revising and sometimes overturning previously accepted theories about a wide variety of topics such as the domestication of the horse.
Museum collections contain unique resources such as natural history specimens, which can be used for genome-scale examinations of species, their evolution, and their responses to environmental change. Ancient DNA provides a unique window into genetic change over time. It enables scientists to directly study evolutionary and ecological processes, comparing ancient and modern populations, identifying distinct populations, and revealing patterns of change such as extinctions and migrations. Research may be used to identify isolated populations and inform conservation priorities.
However, museum specimens can be poorly preserved and are subject to degradation and contamination. Genomic analyses face considerable challenges as a result of the highly degraded DNA typical of museum specimens. DNA from such samples is often subject to post-mortem nucleotide damage such as the hydrolytic deamination of cytosine (C) to uracil (U) residues. PCR amplification of damaged templates can further substitute uracils with thymine (T), completing a C to T substitution path. Such errors tend to occur towards the ends of molecules, accumulate with time, and can be significant in specimens a century-old or later. Robust genomic and statistical techniques are needed to rigorously detect and avoid errors and genotyping uncertainties when carrying out analyses based on museum collections. Optimal methods for working with hDNA and aDNA can differ as a result of differences in their DNA degradation history.
Museomics also involves destructive sampling, irreversibly removing parts of sometimes rare specimens to obtain DNA. This can be contentious for curators and collection staff, involving a variety of ethical issues around the handling and destruction of objects, colonial acquisition and repatriation practices, and present-day social and political implications of research. Museums, universities and journals are increasingly developing ethics statements, best practices and guidelines for such work. | 0 | Theoretical and Fundamental Chemistry |
A report of leaks above the project was released in January 2011 by an advocacy group on behalf of owners of land above the project. They reported ponds fizzing with bubbles, dead animals found near those ponds, sounds of explosions which they attributed to gas blowing out holes in the walls of a quarry. The report said that carbon dioxide levels in the soil averaged about 23,000 parts per million, several times higher than is normal for the area. "The ... source of the high concentrations of CO2 in the soils of the Kerr property is clearly the anthropogenic CO2 injected into the Weyburn reservoir... The survey also demonstrates that the overlying thick cap rock of anhydrite over the Weyburn reservoir is not an impermeable barrier to the upward movement of light hydrocarbons and CO2 as is generally thought." said the report.
The PTRC posted an extensive rebuttal of the Petro-Find report, stating that the isotopic signatures of the , claimed by Mr. Lafleur to be indicative of the manmade being injected into the reservoir, were in fact, according to studies of conducted by the British Geological Survey and two other European Union geological groups prior to being injected at Weyburn, occurring naturally in several locations near the Kerr farm. Subsequent soil surveys after injection in 2002 to 2005 found levels dropped in these same regions. In addition, prior to injection occurring into the oil field, these samplings were found to be as high as 125,000 parts per million and averaging 25,000 ppm across the region, even more than the average and largest readings from the Kerrs property that were being claimed as unusually high. The report also questions, based on seismic imaging conducted over ten years, that any active faults exist or that the caprock is compromised to allow pathways for the to reach the surface. The PTRC acknowledged that they do not monitor the entire site for leaks, rather primarily above the part of the Weyburn field where is injected and key locations outside it, but the organization did monitor the Kerrs well between 2002 and 2006, finding no appreciable difference in water quality. They have also acknowledged that PTRC is a research organisation rather than a regulator, and manage the IEA GHG Weyburn-Midale Monitoring and Storage Project on behalf of the International Energy Agency's Greenhouse Gas R&D Programme, which includes some 30 international research groups. | 1 | Applied and Interdisciplinary Chemistry |
A gooseneck (or goose neck) is a 180° pipe fitting at the top of a vertical pipe that prevents entry of water. Common implementations of goosenecks are ventilator piping or ducting for bathroom and kitchen exhaust fans, ship holds, landfill methane vent pipes, or any other piping implementation exposed to the weather where water ingress would be undesired. It is so named because the word comes from the similarity of pipe fitting to the bend in a goose's neck.
Gooseneck may also refer to a style of kitchen or bathroom faucet with a long vertical pipe terminating in a 180° bend.
To avoid hydrocarbon accumulation, a thermosiphon should be installed at the low point of the gooseneck.
Gooseneck, Lead (pigtail)
Leaded goosenecks are short sections of lead pipe (1’ to 2’ long) used during the early 1900s up to World War Two in supplying water to a customer. These lead tubes could be easily bent, and allowed for a flexible connection between rigid service piping. The bent segments of pipe often took the shape of a goose's neck, and are referred to as “lead goosenecks.” Lead is no longer permitted in new water systems or new building construction.
Goosenecks (also referred to as pigtails) are in-line components of a water service (i.e. piping, valves, fittings, tubing, and accessories) running from the distribution system water main to a meter or building inlet. The valve used to connect a small-diameter service line to a water main is called a corporation stop (also called a tap, or corp stop). One gooseneck joins the corporation stop to the water service pipe work. A second gooseneck links the supply pipeline to a water meter located outside the building. | 1 | Applied and Interdisciplinary Chemistry |
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