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Relief from chronic pain remains a recognized unmet medical need. Consequently, the search for new analgesic agents is being intensively studied by the pharmaceutical industry. The TRPV1 receptor is a ligand gated ion channel that has been implicated in mediation of many types of pain and therefore studied most extensively. The first competitive antagonist, capsazepine, was first described in 1990; since then, several TRPV1 antagonists have entered clinical trials as analgesic agents. Should these new chemical entities relieve symptoms of chronic pain, then this class of compounds may offer one of the first novel mechanisms for the treatment of pain in many years. | 1 | Applied and Interdisciplinary Chemistry |
Natural isotopic variations amongst the noble gases result from both radiogenic and nucleogenic production processes. Because of their unique properties, it is useful to distinguish them from the conventional radiogenic isotope systems described above. | 0 | Theoretical and Fundamental Chemistry |
The application of the term "paludiculture" is debated as it is contingent on whether different peatland agricultural practices are considered sustainable. In terms of greenhouse gas emissions, how sustainable a paludiculture practice is deemed to be depends on the greenhouse gas measured, the species of plant and the water table level of the peatland. "Paludiculture" been used to refer to cultivating native and non-native crops on intact or re-wetted peatlands. In the EU's Common Agricultural Policy, it is defined as the productive land use of wet and rewetted peatlands that preserves the peat soil and thereby minimizes CO emissions and subsidence. A recent review of tropical peatland paludiculture from the National University of Singapore evaluated wet and re-wetted management pathways in terms of greenhouse gas emissions and carbon sequestration and concluded that commercial paludiculture is only suited to re-wetted peatlands, where it is carbon negative or neutral, as opposed to intact peatlands, where it increases emissions. After decades of re-wetting, can still contribute to global warming to a greater extent than intact peatlands. Exceptions where paludiculture on intact peatlands may be sustainable are some traditions of cultivating native crops semi-wild in intact peat swamp forest, or gathering peatland products without active cultivation. The review also suggests that, to be sustainable, paludiculture should only use native vegetation to restore peatlands whilst producing biomass, as opposed to any wetland plants which have the possibility of surviving. This is because using non-native species may create negative peatland conditions for other native plants, and non-native plants tend to have a lower yield and lifespan in undrained or re-wetted peatlands than when grown in their native habitats or drained wetlands. | 1 | Applied and Interdisciplinary Chemistry |
An important contraindication to MRI (magnetic resonance imaging) is having metal objects anywhere near, and most especially inside the field of, the MRI scanner. Not only does this entail that people with implanted metal plates, bone screws (internal fixation), or syndesmotic screws often cannot undergo MRI, it also entails that many everyday objects, including jewelry, belt buckles, wallets, purses, security guards' weapons, and so on, must be kept out of the MRI area. | 1 | Applied and Interdisciplinary Chemistry |
Climate change, rising levels of carbon dioxide in Earth's atmosphere, excess nutrients, and pollution in many forms are altering global oceanic geochemistry. Rates of change for some aspects greatly exceed those in the historical and recent geological record. Major trends include an increasing acidity, reduced subsurface oxygen in both near-shore and pelagic waters, rising coastal nitrogen levels, and widespread increases in mercury and persistent organic pollutants. Most of these perturbations are tied either directly or indirectly to human fossil fuel combustion, fertilizer, and industrial activity. Concentrations are projected to grow in coming decades, with negative impacts on ocean biota and other marine resources.
One of the most striking features of this is ocean acidification, resulting from increased CO uptake of the oceans related to higher atmospheric concentration of CO and higher temperatures, because it severely affects coral reefs, mollusks, echinoderms and crustaceans (see coral bleaching).
Seawater is a means of transportation throughout the world. Everyday plenty of ships cross the ocean to deliver goods to various locations around the world. Seawater is a tool for countries to efficiently participate in international commercial trade and transportation, but each ship exhausts emissions that can harm marine life, air quality of coastal areas. Seawater transportation is one of the fastest growing human generated greenhouse gas emissions. The emissions released from ships pose significant risks to human health in nearing areas as the oil and gas released from the operation of merchant ships decreases the air quality and causes more pollution both in the seawater and surrounding areas.
Another human use of seawater that has been considered is the use of seawater for agricultural purposes. In areas with higher regions of sand dunes, such as Israel, the use of seawater for irrigation of plants would eliminate substantial costs associated with fresh water when it is not easily accessible. Although it is not typical to use salt water as a means to grow plants as the salt gathers and ruins the surrounding soil, it has been proven to be successful in sand and gravel soils. Large-scale desalination of seawater is another factor that would contribute to the success of agriculture farming in dry, desert environments. One of the most successful plants in salt water agriculture is the halophyte. The halophyte is a salt tolerant plant whose cells are resistant to the typically detrimental effects of salt in soil. The endodermis forces a higher level of salt filtration throughout the plant as it allows for the circulation of more water through the cells. The cultivation of halophytes irrigated with salt water were used to grow animal feed for livestock; however, the animals that were fed these plants consumed more water than those that did not. Although agriculture from use of saltwater is still not recognized and used on a large scale, initial research has shown that there could be an opportunity to provide more crops in regions where agricultural farming is not usually feasible. | 0 | Theoretical and Fundamental Chemistry |
Given the importance of glycan-protein interactions, there is an ongoing research dedicated to the a) creation of new tools to detect glycan-protein interactions and b) using those tools to decipher the so-called sugar code. | 1 | Applied and Interdisciplinary Chemistry |
To attach the upper body of the NanoKid to the lower body, the two components were added to a solution of bis(triphenylphosphine)palladium(II) dichloride, copper(I) iodide, TEA, and THF. This resulted in the final structure of the NanoKid. | 1 | Applied and Interdisciplinary Chemistry |
For sum-frequency generation to occur efficiently, phase-matching conditions must be satisfied:
where are the angular wavenumbers of the three waves as they travel through the medium. (Note that the equation resembles the equation for conservation of momentum.) As this condition is satisfied more and more accurately, the sum-frequency generation becomes more and more efficient. | 0 | Theoretical and Fundamental Chemistry |
The EDM process is most widely used by the mold-making, tool, and die industries, but is becoming a common method of making prototype and production parts, especially in the aerospace, automobile and electronics industries in which production quantities are relatively low. In sinker EDM, a graphite, copper tungsten, or pure copper electrode is machined into the desired (negative) shape and fed into the workpiece on the end of a vertical ram. | 1 | Applied and Interdisciplinary Chemistry |
The level of reducing sugars in wine, juice, and sugarcane are indicative of the quality of these food products, and monitoring the levels of reducing sugars during food production has improved market quality. The conventional method for doing so is the Lane-Eynon method, which involves titrating the reducing sugar with copper(II) in Fehling's solution in the presence of methylene blue, a common redox indicator. However, it is inaccurate, expensive, and sensitive to impurities. | 0 | Theoretical and Fundamental Chemistry |
Liquid marbles were first reported by P. Aussillous and D. Quere in 2001, who described a new method to construct portable water droplets in the atmospheric environment with hydrophobic coating on their surface to prevent the contact between water and the solid ground (Figure 1). Liquid marbles provide a new approach to transport liquid mass on the solid surface, which sufficiently transform the inconvenient glass containers into flexible, user-specified hydrophobic coating composed of powders of hydrophobic materials. Since then, the applications of liquid marbles in no-loss mass transport, microfluidics and microreactors have been extensively investigated. However, liquid marbles only reflect the water behavior at the solid-air interface, while there is no report on the water behavior at the liquid-liquid interface, as a result of the so-called coalescence cascade phenomenon.
When a water droplet is in contact with a water reservoir, it will quickly pinch off from the reservoir and form a smaller daughter droplet, while this daughter droplet will continue to go through a similar contact-pinch off-splitting process until completed coalescence into the reservoir, the combination or summary of these self-similar coalescence processes is called coalescence cascade. The underlying mechanism of coalescence cascade has been studied in detail but there has been mere attempt to control and make use of it. Until recently, Liu et al. has filled this void by proposing a new method to control coalescence cascade by using nanostructured coating at the liquid-liquid interface, —the interfacial liquid marbles.
Similar to liquid marbles at the solid-air interface, the interfacial liquid marbles are constructed on the hexane/water interface using water droplets with a surface coating composed of nanoscale materials with special wettability (Figure 2). To realize interfacial water marbles at hexane/water interface, the individual particle size of the surface coating layer should be as small as possible, so that the contact line between the particles and the water reservoir can be minimized; special wettability with mixed hydrophobicity and hydrophilicity is also preferred for the interfacial water marble formation. The interfacial water marble can be fabricated by firstly coating a water droplet with nanomaterials with special wettability, e.g. hybrid carbon nanowires, graphene oxide. Afterwards a secondary coating layer of polyvinylidene fluoride (PVDF) is applied onto the coated water droplet. The doubly-coated water droplet is then cast into the hexane/water mixture and eventually settled at the hexane/water interface to form the interfacial water marble. During this process, the PVDF coating quickly diffused into hexane to balance the hydrophobic interaction between hexane and the water droplet, while the nanomaterials quickly self-assembled into a nanostructured protective layer on the droplet surface through the Marangoni effect.
The interfacial water marble can completely resist coalescence cascade and exist nearly permanently at the hexane/water interface, providing that the hexane phase is not depleted by vaporization. The interfacial water marbles can also realize a series of stimuli-responsive motions by integrating the functional materials into the surface coating layer. Due to their uniqueness in both form and behavior, the interfacial water marbles are speculated to have remarkable applications in microfluidics, microreactors and mass-transport. | 0 | Theoretical and Fundamental Chemistry |
In many condensation polymers, the repeat unit contains two structural units related to the comonomers which have been polymerized. For example, in polyethylene terephthalate (PET or "polyester"), the repeat unit is -CO-CH-CO-O-CH-CH-O-. The polymer is formed by the condensation reaction of the two monomers terephthalic acid (HOOC-CH-COOH) and ethylene glycol (HO-CH-CH-OH), or their chemical derivatives. The condensation involves loss of water, as an H is lost from each HO- group in the glycol, and an OH from each HOOC- group in the acid. The two structural units in the polymer are then considered to be -CO-CH-CO- and -O-CH-CH-O-. | 0 | Theoretical and Fundamental Chemistry |
It has been found that the F number linearly correlates with the log k' value (logarithm of the retention factor) in aqueous reversed-phase liquid chromatography. This relationship can be used to understand the significance of different aspects of molecular architecture on their separation using different stationary phases. This size analysis is complementary to the length-to-breadth (L/B) ratio, which classifies molecules according to their "rodlike" or "squarelike" shape. | 0 | Theoretical and Fundamental Chemistry |
Utilizing sandbags and a significant workforce represents another unique closure method. This approach was employed during the construction of the dam across the Feni river in Bangladesh. At low tide, the riverbed at the closure site was almost completely exposed.
Twelve depots, each containing 100,000 sandbags, were established along the 1,200 m wide closure gap. On the day of the closure, 12,000 workers deployed these bags into the gap over a span of six hours, outpacing the rising tide. By the days end, the tidal inlet was sealed, albeit only to the water levels typical of neap tides. In the ensuing days, the dam was further augmented with sand to withstand spring tides and, over the next three months, reinforced to resist storm surges up to 10 metres above the dams base. | 1 | Applied and Interdisciplinary Chemistry |
Placebo is the opening word of the antiphon of vespers in the Office of the Dead, used as a name for the service as a whole. The full sentence, from the Vulgate, is I will please the Lord in the land of the living, from Psalm 116:9. To sing placebo at a funeral came to mean to falsely claim a connection to the deceased to get a share of the funeral meal, and hence a flatterer, and so a deceptive act to please. | 1 | Applied and Interdisciplinary Chemistry |
The 43S preinitiation complex (43S PIC) is a ribonucleoprotein complex that exists during an early step of eukaryotic translation initiation. The 43S PIC contains the small ribosomal subunit (40S) bound by the initiation factors eIF1, eIF1A, eIF3, and the eIF2-Met-tRNA-GTP ternary complex (eIF2-TC). | 1 | Applied and Interdisciplinary Chemistry |
In biochemistry and molecular biology, saline-sodium citrate (SSC) buffer is used as a hybridization buffer, to control stringency for washing steps in protocols for Southern blotting, in situ hybridization, DNA Microarray or Northern blotting. 20X SSC may be used to prevent drying of agarose gels during a vacuum transfer.
A 20X stock solution consists of 3 M sodium chloride and 300 mM trisodium citrate (adjusted to pH 7.0 with HCl). | 1 | Applied and Interdisciplinary Chemistry |
An experimental device working according to thermogravitational cycle principle was developed in a laboratory of the University of Bordeaux and patented in France. Such thermogravitational electric generator is based on inflation and deflation cycles of an elastic bag made of nitrile elastomer cut from a glove finger. The bag is filled with a volatile working fluid that has low chemical affinity for the elastomer such as perfluorohexane (CF). It is attached to a strong NdFeB spherical magnet that acts both as a weight and for transducing the mechanical energy into voltage. The glass cylinder is filled with water acting as transporting fluid. It is heated at the bottom by a hot circulating water-jacket, and cooled down at the top by a cold water bath. Due to its low boiling point temperature (56 °C), the perfluorohexane drop contained in the bag vaporizes and inflates the balloon. Once its density is lower than the water density, the balloon raises according to Archimedes’ principle. Cooled down at the column top, the balloon deflates partially until its gets effectively denser than water and starts to fall down. As seen from the videos, the cyclic motion has a period of several seconds. These oscillations can last for several hours and their duration is limited only by leaks of the working fluid through the rubbery membrane. Each time the magnet goes through the coil produces a variation in the magnetic flux. An electromotive force is created and detected through an oscilloscope. It has been estimated that the average power of this machine is 7 μW and its efficiency is 4.8 x 10. Although these values are very small, this experiment brings a proof of principle of renewable energy device for harvesting electricity from a weak waste heat source without need of other external energy supply, e.g. for a compressor in a regular heat engine. The experiment was successfully reproduced by undergraduate students in preparatory classes of the Lycée Hoche in Versailles.
Several other applications based on the thermogravitational cycles could be found in the literature. For example:
* In solar balloons, heat from the sun is absorbed which causes a balloon filled with air to rise and convert its movement in an electric signal.
* In a gravity driven organic Rankine cycle, gravity is used instead of a pump to pressurize a working fluid. In literature, different authors have studied the working fluid characteristics best suited to optimize their efficiency for gravity-driven ORC devices.
* In a version of a magnetic fluid generator, a refrigerant fluid is vaporized at the bottom of a column by an external heat source, and its bubbles move across a magnetized ferrofluid, thereby producing electric voltage via a linear generator.
* In a conceptual hybrid of several patents, solar or geothermal energy is harnessed by means of a modified organic Rankine cycle with high columns of water below ground | 0 | Theoretical and Fundamental Chemistry |
The Ruhrchemie/Rhone–Poulenc process (RCRPP) relies on a rhodium catalyst with water-soluble TPPTS as ligand (Kuntz Cornils catalyst) for the hydroformylation of propene. The tri-sulfonation of triphenylphosphane ligand provides hydrophilic properties to the organometallic complex. The catalyst complex carries nine sulfonate-groups and is highly soluble in water (about 1 kg L), but not in the emerging product phase. The water-soluble TPPTS is used in about 50-fold excess, whereby the leaching of the catalyst is effectively suppressed. Reactants are propene and syngas consisting of hydrogen and carbon monoxide in a ratio of 1.1:1. A mixture of butyraldehyde and isobutyraldehyde in the ratio 96:4 is generated with few by-products such as alcohols, esters and higher boiling fractions. The Ruhrchemie/Rhone-Poulenc-process is the first commercially available two-phase system in which the catalyst is present in the aqueous phase.
In the progress of the reaction an organic product phase is formed which is separated continuously by means of phase separation, wherein the aqueous catalyst phase remains in the reactor.
The process is carried out in a stirred tank reactor where the olefin and the syngas are entained from the bottom of the reactor through the catalyst phase under intensive stirring. The resulting crude aldehyde phase is separated at the top from the aqueous phase. The aqueous catalyst-containing solution is re-heated via a heat exchanger and pumped back into the reactor. The excess olefin and syngas is separated from the aldehyde phase in a stripper and fed back to the reactor. The generated heat is used for the generation of process steam, which is used for subsequent distillation of the organic phase to separate into butyraldehyde and isobutyraldehyde. Potential catalyst poisons coming from the synthesis gas migrate into the organic phase and removed from the reaction with the aldehyde. Thus there is no accumulation of catalyst poisons, and the elaborate fine purification of the syngas can be omitted.
A plant was built in Oberhausen in 1984, which was debottlenecked in 1988 and again in 1998 up to a production capacity of 500,000 t/a butanal. The conversion rate of propene is 98% and the selectivity to n-butanal is high. During the life time of a catalyst batch in the process less than 1 ppb rhodium is lost. | 0 | Theoretical and Fundamental Chemistry |
Unsealed sources are sources that are not in a permanently sealed container, and are used extensively for medical purposes. They are used when the source needs to be dissolved in a liquid for injection into a patient or ingestion by the patient. Unsealed sources are also used in industry in a similar manner for leak detection as a Radioactive tracer. | 0 | Theoretical and Fundamental Chemistry |
Yeast fungi, being facultative anaerobes, can either produce energy through ethanol fermentation or aerobic respiration. When the O concentration is low, the two pyruvate molecules formed through glycolysis are each fermented into ethanol and carbon dioxide. While only 2 ATP are produced per glucose, this method is utilized under anaerobic conditions because it oxidizes the electron shuttle NADH into NAD for another round of glycolysis and ethanol fermentation.
If the concentration of oxygen increases, pyruvate is instead converted to acetyl CoA, used in the citric acid cycle, and undergoes oxidative phosphorylation. Per glucose, 10 NADH and 2 FADH are produced in cellular respiration for a significant amount of proton pumping to produce a proton gradient utilized by ATP Synthase. While the exact ATP output ranges based on considerations like the overall electrochemical gradient, aerobic respiration produces far more ATP than the anaerobic process of ethanol fermentation. The increased ATP and citrate from aerobic respiration allosterically inhibit the glycolysis enzyme phosphofructokinase 1 because less pyruvate is needed to produce the same amount of ATP.
Despite this energetic incentive, Rosario Lagunas has shown that yeast continue to partially ferment available glucose into ethanol for many reasons. First, glucose metabolism is faster through ethanol fermentation because it involves fewer enzymes and limits all reactions to the cytoplasm. Second, ethanol has bactericidal activity by causing damage to the cell membrane and protein denaturing, allowing yeast fungus to outcompete environmental bacteria for resources. Third, partial fermentation may be a defense mechanism against environmental competitors depleting all oxygen faster than the yeast's regulatory systems could fully switch from aerobic respiration to ethanol fermentation. | 1 | Applied and Interdisciplinary Chemistry |
Jean Ruel was the dean of the Faculty of Medicine and physician to King Francis I of France. He perfected the Latin translation of the Materia Medica directly from the "princeps" edition. He tried to develop a translation joining philology, botany and medicine. This work, printed in 1516 by Henri Estienne/Stephano, became very popular, having 20 editions during the 16th century. He published editions until 1537, printed by Simon de Colines.
From this point, Latin was the preferred language for presenting De Materia Medica, and Ruel's editions became the basis from which many other important authors would start to create their own Materia Medica. Ruel was also teacher of two great De Materia Medica authors: Michel de Villeneuve and Andres Laguna. | 1 | Applied and Interdisciplinary Chemistry |
Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so. The volatile aldehydes have pungent odors.
Aldehydes can be identified by spectroscopic methods. Using IR spectroscopy, they display a strong ν band near 1700 cm. In their H NMR spectra, the formyl hydrogen center absorbs near δ 9.5 to 10, which is a distinctive part of the spectrum. This signal shows the characteristic coupling to any protons on the α carbon with a small coupling constant typically less than 3.0 Hz. The C NMR spectra of aldehydes and ketones gives a suppressed (weak) but distinctive signal at δ 190 to 205. | 0 | Theoretical and Fundamental Chemistry |
Ferrous oxalate (iron(II) oxalate) are inorganic compound with the formula FeCO(HO) where x is 0 or 2. These are orange compounds, poorly soluble in water. | 0 | Theoretical and Fundamental Chemistry |
PDRC coatings or paints tend to be advantageous for their direct application to surfaces, simplifying preparation processes and reducing costs, although not all PDRC coatings are inexpensive. Coatings generally offer "strong operability, convenient processing, and low cost, which have the prospect of large-scale utilization," as per Dong et al. PDRC coatings have been developed in colors other than white while still demonstrating high solar reflectance and heat emissivity.
Coatings must be durable and resistant to soiling, which can be achieved with porous PDRCs or hydrophobic topcoats that can withstand cleaning, although hydrophic coatings use polytetrafluoroethylene or other similar compounds to be water-resistant. Negative environmental impacts can be mitigated by limiting use of other toxic solvents common in paints, such as acetone. Non-toxic or water-based paints have been developed. More research and development is needed.
Porous Polymers Coating (PPC) exhibit excellent PDRC performance. These polymers have a high concentration of tiny pores, which scatter light effectively at the boundary between the polymer and the air. This scattering enhances both solar reflectance (reflecting more than 96% of sunlight) and thermal emittance (emitting 97% of heat), resulting in a surface temperature that is six degrees cooler than the surroundings at noon in Phoenix. Additionally, this process is solution-based and can be easily scaled up. A new design for PPC coloring is discovered. The dye of desired color is coated on the porous polymer. Comparing to traditional dye in porous polymer, which the dye is mixed in the polymer, the new design can have a higher refractive index of infrared and heat.
The cost of PDRC coatings was significantly lowered with a 2018 study by Atiganyanun et al. which demonstrated how "photonic media, when properly randomized to minimize the photon transport mean free path, can be used to coat a black substrate and reduce its temperature by radiative cooling." This coating could "outperform commercially available solar-reflective white paint for daytime cooling" without using expensive manufacturing steps or materials.
PDRC coatings that are described as scalable and low-cost include:
* Li et al. (2019), aluminum phosphate coating, solar reflectance 97%, heat emittance 90%, daytime air temperature ~4.2 °C lower than ambient temperature (~4.8 °C lower than commercial heat insulation coating), predicted estimated cost by Dong et al. at $1.2/m2, tested in Guangzhou (daytime humidity 41%), selective emitter (SE).
* Li et al. (2021), ultrawhite Barium sulfate| paint with 60% volume concentration, solar reflectance 98.1%, heat emittance 95%, daytime air temperature ~4.5 °C lower than ambient, "providing great reliability, convenient paint form, ease of use, and compatibility with the commercial paint fabrication process."
* Weng et al. (2021), porous PDMS (Polydimethylsiloxane) sponge emitter template method for coatings, solar reflectance 95%, heat emittance 96.5%, daytime air temperature ~8 °C lower than ambient, avoids hazardous etching agents (e.g., hydrofluoric acid, hydrogen peroxide, acetic acid) or VOCs (e.g., acetone, dimethylformamide, tetrahydrofuran, hexane), "compatibility with large-scale production," tested in Hangzhou (daytime humidity ~61%).
* Wang et al. (2022), waterborne thermochromic coating free of ecotoxic and carcinogenic titanium dioxide, solar reflectance 96%, heat emittance 94%, daytime air temperature ~7.1 °C lower than ambient, and "can be produced at a large scale and conveniently coated on various substrates through traditional drop casting, spraying, roller painting, or spin-coating methods" and "switchable [between] solar heating and radiative cooling," tested in Shanghai (daytime humidity ~28%).
* Dong et al. (2022), Barium sulphate|, Calcium carbonate|, and Silicon dioxide| particles coating, solar reflectance 97.6%, heat emittance 89%, daytime air temperature ~8.3 °C lower than ambient (~5.5 °C lower than commercial white paints), described "for large-scale commercial production" with a predicted estimated cost of $0.5/m2, tested in Weihai (daytime humidity 40%).
* Zhai et al. (2022), α-Bismuth(III) oxide| colored coating, solar reflectance 99%, heat emittance 97%, daytime air temperature ~2.31 °C (average cooling power 68 Wm-2), uses "low cost of raw oxide materials, and simple preparation process," tested in Nanjing (daytime humidity 54%). | 0 | Theoretical and Fundamental Chemistry |
*Acetyl-CoA
*fatty acyl-CoA (activated form of all fatty acids; only the CoA esters are substrates for important reactions such as mono-, di-, and triacylglycerol synthesis, carnitine palmitoyl transferase, and cholesterol esterification)
**Propionyl-CoA
**Butyryl-CoA
**Myristoyl-CoA
**Crotonyl-CoA
*Acetoacetyl-CoA
*Coumaroyl-CoA (used in flavonoid and stilbenoid biosynthesis)
*Benzoyl-CoA
*Phenylacetyl-CoA
* Acyl derived from dicarboxylic acids
**Malonyl-CoA (important in chain elongation in fatty acid biosynthesis and polyketide biosynthesis)
**Succinyl-CoA (used in heme biosynthesis)
**Hydroxymethylglutaryl-CoA (used in isoprenoid biosynthesis)
**Pimelyl-CoA (used in biotin biosynthesis) | 1 | Applied and Interdisciplinary Chemistry |
Thalidomide was originally released in the Federal Republic of Germany (West Germany) under the label of Contergan on October 1, 1957, by Chemie Grünenthal (now Grünenthal). The drug was primarily prescribed as a sedative or hypnotic, but it was also used as an antiemetic for morning sickness in pregnant women. The drug was banned in 1961 after its teratogenic properties were observed. The problems with thalidomide were, aside from the teratogenic side effects, both high incidence of other adverse reactions along with poor solubility in water and absorption from the intestines. Adverse reactions include peripheral neuropathy in large majority of patients, constipation, thromboembolism along with dermatological complications.
Four years after thalidomide was withdrawn from the market for its ability to induce severe birth defects, its anti-inflammatory properties were discovered when patients with erythema nodosum leprosum (ENL) used thalidomide as a sedative and it reduced both the clinical signs and symptoms of the disease. Thalidomide was discovered to inhibit tumour necrosis factor-alpha (TNF-α) in 1991 (5a Sampaio, Sarno, Galilly Cohn and Kaplan, JEM 173 (3) 699–703, 1991) . TNF-α is a cytokine produced by macrophages of the immune system, and also a mediator of inflammatory response. Thus the drug is effective against some inflammatory diseases such as ENL (6a Sampaio, Kaplan, Miranda, Nery..... JID 168 (2) 408-414 2008). In 1994 Thalidomide was found to have anti-angiogenic activity and anti-tumor activity which propelled the initiation of clinical trials for cancer including multiple myeloma. The discovery of the anti-inflammatory, anti-angiogenic and anti-tumor activities of thalidomide increased the interest of further research and synthesis of safer analogs.
Lenalidomide is the first analog of thalidomide which is marketed. It is considerably more potent than its parent drug with only two differences at a molecular level, with an added amino group at position 4 of the phthaloyl ring and removal of a carbonyl group from the phthaloyl ring.
Development of lenalidomide began in the late 1990s and clinical trials of lenalidomide began in 2000. In October 2001 lenalidomide was granted orphan status for the treatment of MM. In mid-2002 it entered phase II and by early 2003 phase III. In February 2003 FDA granted fast-track status to lenalidomide for the treatment of relapsed or refractory MM.
In 2006 it was approved for the treatment of MM along with dexamethasone and in 2007 by European Medicines Agency (EMA). In 2008, phase II trial observed efficacy in treating Non-Hodgkin's lymphoma.
Pomalidomide (3-aminothalidomide) was the second thalidomide analog to enter the clinic being more potent than both of its predecessors.
First reported in 2001, pomalidomide was noted to directly inhibit myeloma cell proliferation and thus inhibiting MM both on the tumor and vascular compartments. This dual activity of pomalidomide makes it more efficacious than thalidomide both in vitro and in vivo. This effect is not related to TNF-α inhibition since potent TNF-α inhibitors such as rolipram and pentoxifylline did not inhibit myeloma cell growth nor angiogenesis. Upregulation of interferon gamma, IL-2 and IL-10 have been reported for pomalidomide and may contribute to its anti-angiogenic and anti-myeloma activities. | 1 | Applied and Interdisciplinary Chemistry |
Military activity is a source of uranium, especially at nuclear or munitions testing sites. Depleted uranium (DU) is a byproduct of uranium enrichment that is used for defensive armor plating and armor-piercing projectiles. Uranium contamination has been found at testing sites in the UK, in Kazakhstan, and in several countries as a result of DU munitions used in the Gulf War and the Yugoslav wars. During a three-week period of conflict in 2003 in Iraq, 1,000 to 2,000 tonnes of DU munitions were used.
Combustion and impact of DU munitions can produce aerosols that disperse uranium metal into the air and water where it can be inhaled or ingested by humans. A United Nations Environment Programme (UNEP) study has expressed concerns about groundwater contamination from these munitions. Studies of DU aerosol exposure suggest that uranium particles would quickly settle out of the air, and thus should not affect populations more than a few kilometres from target areas. | 0 | Theoretical and Fundamental Chemistry |
Non exhaustive list of microorganisms.
Bacteria (Gram-positive and -negative)
*Acinetobacter spp.
*Aeromonas hydrophila
*Bacillus brevis
*Bacillus cereus
*Bacillus megaterium
*Bacillus subtilis
*Burkholderia cepacia
*Campylobacter jejuni
*Capnocytophaga ochracea
*Corynebacterium xerosis
*Enterobacter cloacae
*Escherichia coli
*Haemophilus influenzae
*Helicobacter pylori
*Klebsiella oxytoca
*Klebsiella pneumoniae
*Legionella spp.
*Listeria monocytogenes
*Micrococcus luteus
*Mycobacterium smegmatis
*Mycobacterium abscessus
*Neisseria spp.
*Pseudomonas aeruginosa
*Pseudomonas pyocyanea
*Salmonella spp.
*Selenomonas sputigena
*Shigella sonnei
*Staphylococcus aerogenes
*Staphylococcus aureus
*Streptococcus agalactiae
*Streptococcus faecalis
*Streptococcus mutans
*Wolinella recta
*Xanthomonas campestris
*Yersinia enterocolitica
Viruses
*Echovirus 11
*Herpes simplex virus, HSV
*Influenza virus
*Human immunodeficiency virus, HIV
*Respiratory syncytial virus, RSV
Yeasts and moulds
*Aspergillus niger
*Botryodiplodia theobromae
*Byssochlamys fulva
*Candida albicans
*Colletotrichum gloeosporioide
*Colletotrichum musae
*Fusarium monoliforme
*Fusarium oxysporum
*Rhodotula rubra
*Sclerotinia spp. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, vinylene (also or 1,2-ethenediyl) is a divalent functional group (a part of a molecule) with formula −CH=CH−; namely, two carbons, each connected to the other by a double bond, to an hydrogen atom by a single bond, and to the rest of the molecule by another single bond.
This group can be viewed as a molecule of ethene (ethylene, HC=CH) with an hydrogen removed from each carbon; or a vinyl group −CH=CH with one hydrogen removed from the terminal carbon. It should not be confused with the vinylidene group =C=CH or >C=CH.
A vinylene unit attached to two distinct atoms other than hydrogen (namely R−CH=CH−R') is a source of cis-trans isomerism.
The vinylene group is the repeating unit in polyacetylene and in polyenes. | 0 | Theoretical and Fundamental Chemistry |
After a library is created, the genome of an organism can be sequenced to elucidate how genes affect an organism or to compare similar organisms at the genome-level. The aforementioned genome-wide association studies can identify candidate genes stemming from many functional traits. Genes can be isolated through genomic libraries and used on human cell lines or animal models to further research. Furthermore, creating high-fidelity clones with accurate genome representation and no stability issues would contribute well as intermediates for shotgun sequencing or the study of complete genes in functional analysis. | 1 | Applied and Interdisciplinary Chemistry |
Many secondary amines react with carbon disulfide and sodium hydroxide to form dithiocarbamate salts:
Ammonia reacts with CS similarly:
:2 NH + CS → HNCSNH
Dithiocarbamate salts are pale colored solids that are soluble in water and polar organic solvents. | 0 | Theoretical and Fundamental Chemistry |
The electrochemist John Bockris proposed the words electronation and deelectronation to describe reduction and oxidation processes, respectively, when they occur at electrodes. These words are analogous to protonation and deprotonation. They have not been widely adopted by chemists worldwide, although IUPAC has recognized the terms electronation and de-electronation. | 0 | Theoretical and Fundamental Chemistry |
One unique property of xDNA is its inherent fluorescence. Natural bases can be bound directly to fluorophores for use in microarrays, in situ hybridization, and polymorphism analysis. However, these fluorescent natural bases often fail as a result of self-quenching, which diminishes their fluorescent intensity and reduces their applicability as visual DNA tags. The pi interactions between the rings in x-nucleobases result in an inherent fluorescence in the violet-blue range, with a Stokes shift between 50 and 80 nm. They also have a quantum yield in the range of 0.3–0.6. xC has the greatest fluorescent emission. | 1 | Applied and Interdisciplinary Chemistry |
* [https://www.bio.vu.nl/thb/deb/deblab/add_my_pet/index.html Add my pet (AmP)] project is a collection of DEB models for over 1000 species, and explores patterns in parameter values across taxa. Routines for parameter exploration are available in [https://www.bio.vu.nl/thb/deb/deblab/add_my_pet/AmPtool.html AmPtool] .
* Models based on DEB theory can be linked to more traditional bioenergetic models without deviating from the underlying assumptions. This allows comparison and testing of model performance .
* A DEB-module (physiological model based on DEB theory) was successfully applied to reconstruct and predict physiological responses of individuals under environmental constraints
* A DEB-module is also featured in the eco-toxicological mechanistic models ([http://www.debtox.info/software.html DEBtox implementation]) for modeling the sublethal effects of toxicants (e.g., change in reproduction or growth rate)
* Generality of the approach and applicability of the same mathematical framework to organisms of different species and life stages enables inter- and intra-species comparisons on the basis of parameter values, and theoretical/empirical exploration of patterns in parameter values in the evolutionary context, focusing for example on development, energy utilization in a specific environment, reproduction, comparative energetics, and toxicological sensitivity linked to metabolic rates.
* Studying patterns in body size scaling relationships: The assumptions of the model quantify all energy and mass fluxes in an organism (including heat, dioxygen, carbon dioxide, ammonia) while avoiding using the allometric relationships. In addition, same parameters describe same processes across species: for example, heating costs of endotherms (proportional to surface area) are regarded separate to volume-linked metabolic costs of both ectotherms and endotherms, and cost of growth, even though they all contribute to metabolism of the organism. Rules for the co-variation of parameter values across species are implied by model assumptions, and the parameter values can be directly compared without dimensional inconsistencies which might be linked to allometric parameters. Any eco-physiological quantity that can be written as function of DEB parameters which co-vary with size can, for this reason, also be written as function of the maximum body size.
* DEB theory provides constraints on the metabolic organisation of sub-cellular processes. Together with rules for interaction between individuals (competition, syntrophy, prey-predator relationships), it also provides a basis to understand population and ecosystem dynamics.
Many more examples of applications have been published in scientific literature. | 1 | Applied and Interdisciplinary Chemistry |
From the equality of the flow parameters on two different days , measured values on one day can be corrected to those that would be measured on a standard day so,
where are measured values and 519 degR and 14.7lb/sq in are the standard day temperature and pressure.
The temperature and pressure correction factors are and , so
For speed the corrected value is
Example: An engine is running at 100% speed and 107 lb of air is entering the compressor every second, and the day conditions are 14.5 psia and 30 deg F (490 deg R).
On a standard day the airflow would be which is 105.2 lb/sec. The speed would be which is 103%. These corrected values are what would appear on the compressor map for this particular engine.
This example shows that a compressor runs aerodynamically faster on a cold day and would be slower on a hot day. Since the day conditions are those at entry to the compressor an extremely hot day is produced artificially by the ram temperature rise at high Mach numbers. The aerodynamic speed is low enough, despite the engine running at its 100% rated mechanical speed, to get into the rotating stall region on the map so an engine operating at these Mach numbers needs the appropriate features. The General Electric J93 had variable inlet guide vanes and stators. The Pratt & Whitney J58 had inter-stage bleed from the compressor and 2-position inlet guide vanes. The Tumansky R-15 had pre-compressor cooling to reduce the air temperature and avoid low corrected speeds. | 0 | Theoretical and Fundamental Chemistry |
#"Walter, Filip Neriusz", in Stanley S. Sokol, The Polish Biographical Dictionary, Bolchazy-Carducci Publishers, 1992.
#Stefan Sękowski, Stefan Szostkiewicz, Serce i retorta (The Heart and the Retort), Warsaw, Wiedza Powszechna, 1957.
#Aleksander Jełowicki, Wspomnienia (Memoirs), Paris, 1839.
#Stanisław Wodzicki, Wspomnienia z przeszłości (Memoirs of the Past). Kraków, 1873.
#Adolphe Wurz, Historia poglądów chemicznych (A History of Chemical Views), Warsaw, 1886. | 0 | Theoretical and Fundamental Chemistry |
The tool has a crucial part to creation of the final product. The tool consists of two main functions:
# Localized heating
# Material flow
The tool at its most simplest form consist of a shoulder, a small cylinder with a diameter of 50 mm, and a pin, a small threaded cylinder similar to a drill. The tool itself has been modified to reduce displaced volume of the metals as they merged. Recently two new pin geometries have arisen:
# Flared-Triflute – introducing flutes (large carving vertically on the pin)
#A-skew – the pin axis being inclined to the axis of the spindle. | 1 | Applied and Interdisciplinary Chemistry |
Two methods to extract the Gibbs free energy based on the value of CMC and exist; Phillips method based on the law of mass action and the pseudo-phase separation model. The law of mass action postulates that the micelle formation can be modeled as a chemical equilibrium process between the micelles and its constituents, the surfactant monomers, :
where is the average number of surfactant monomers in solution that associate into a micelle, commonly denoted the aggregation number.
The equilibrium is characterized by an equilibrium constant defined by , where and are the concentrations of micelles and free surfactant monomers, respectively. In combination with the law of conservation of mass, the system is fully specified by: , where is the total surfactant concentration. Phillips defined the CMC as the point corresponding to the maximum change in gradient in an ideal property-concentration ( against ) relationship =0. By implicit differentiation of three times with respect to and equating to zero it can be shown that the micellization constant is given by for . According to Phillips method the Gibbs free energy change of micellization is therefore given by:
The pseudo-phase separation model was originally derived on its own basis, but it has later been shown that it can be interpreted as an approximation to the mass-action model for large . That is, for micelles behaving in accordance with the law of mass-action, the pseudo-phase phase separation model is only an approximation and will only become asymptotically equal to the mass-action model as the micelle becomes a true macroscopic phase i.e. for →∞. However, the approximation that the aggregation number is large is in most cases sufficient: | 0 | Theoretical and Fundamental Chemistry |
Alloy systems that are liquid at room temperature have thermal conductivity far superior to ordinary non-metallic liquids, allowing liquid metal to efficiently transfer energy from the heat source to the liquid. They also have a higher electrical conductivity that allows the liquid to be pumped more efficiently, by electromagnetic pumps. This results in the use of these materials for specific heat conducting and/or dissipation applications.
Another advantage of liquid alloy systems is their inherent high densities. | 1 | Applied and Interdisciplinary Chemistry |
Chemistry in Australia is a magazine published by the RACI monthly. It contains news, reviews of books and chemical software, as well as reports and stories aimed at a broad chemical audience. It is free to read online, and also available as a hard copy for members. It was established in 1934 as the Journal and Proceedings of the Australian Chemical Institute.
The Chemical Education Division publishes the Australian Journal of Education in Chemistry (). It was formally called Chemeda: The Australian Journal of Chemical Education. It includes articles on chemical education at all levels in schools and universities, including experiments from the Australasian Chemistry Enhanced Laboratory Learning (ACELL) Project. | 1 | Applied and Interdisciplinary Chemistry |
Uniporters work to transport molecules or ions by passive transport across a cell membrane down its concentration gradient.
Upon binding and recognition of a specific substrate molecule on one side of the uniporter membrane, a conformational change is triggered in the transporter protein. This causes the transporter protein to change its three-dimensional shape, which ensures the substrate molecule is captured within the transporter proteins structure. The conformational change leads to the translocation of the substrate across the membrane onto the other side. On the other side of the membrane, the uniporter undergoes another conformational change in the release of the substrate molecule. The uniporter returns to its original conformation to bind another molecule for transport.
Unlike symporters and antiporters, uniporters transport one molecule/ion in a single direction based on the concentration gradient. The entire process depends on the substrate's concentration difference across the membrane to be the driving force for the transport by uniporters. Cellular energy in the form of ATP is not required for this process. | 1 | Applied and Interdisciplinary Chemistry |
Methyl phenyldiazoacetate is the organic compound with the formula CHC(N)COMe. It is a diazo derivative of methyl phenylacetate. Colloguially referred to as "phenyldiazoacetate", it is generated and used in situ after isolation as a yellow oil.
Methyl phenyldiazoacetate and many related derivatives are precursors to donor-acceptor carbenes, which can be used for cyclopropanation or to insert into C-H bonds of organic substrates. These reactions are catalyzed by dirhodium tetraacetate or related chiral complexes. Methyl phenyldiazoacetate is prepared by treating methyl phenylacetate with p-acetamidobenzenesulfonyl azide in the presence of base. | 0 | Theoretical and Fundamental Chemistry |
Phycobilisomes can be used in [https://store-7fikt.mybigcommerce.com/product_images/uploaded_images/J_Fluorescence_PBXL_Detection.pdf prompt fluorescence], flow cytometry, Western blotting and protein microarrays. Some phycobilisomes have an absorption and emission profile similar to Cy5, allowing them to be used in many of the same applications. They can also be up to 200 times brighter and with a larger Stokes shift, providing a larger signal per binding event. This property allows the detection of low-level target molecules or rare events. | 0 | Theoretical and Fundamental Chemistry |
Mini-bulk tests are conducted with 1-100t of samples on industrial scale sensor-based ore sorters. The size fraction intervals to be treated are prepared using screen classifications. Full capacity is established then with each fraction and multiple cut-points are programmed in the sorting software. After creating multiple sorting fractions in rougher, scavenger and cleaner steps these weighed are sent for assays. The resulting data delivers all input for flow-sheet development. Since the tests are conducted on industrial scale equipment, there is no scale-up factor involved when designing a flow-sheet and installation of sensor-based ore sorting. | 0 | Theoretical and Fundamental Chemistry |
Dendrimers have potential applications in sensors. Studied systems include proton or pH sensors using poly(propylene imine), cadmium-sulfide/polypropylenimine tetrahexacontaamine dendrimer composites to detect fluorescence signal quenching, and poly(propylenamine) first and second generation dendrimers for metal cation photodetection amongst others. Research in this field is vast and ongoing due to the potential for multiple detection and binding sites in dendritic structures. | 0 | Theoretical and Fundamental Chemistry |
The eluent or eluant is the "carrier" portion of the mobile phase. It moves the analytes through the chromatograph. In liquid chromatography, the eluent is the liquid solvent; in gas chromatography, it is the carrier gas. | 0 | Theoretical and Fundamental Chemistry |
In special situations, some ligands participate in substitution reactions leading to associative pathways. These ligands can adopt multiple motifs for binding to the metal, each of which involves a different number of electrons "donated." A classic case is the indenyl effect in which an indenyl ligand reversibly "slips' from pentahapto (η) coordination to trihapto (η). Other pi-ligands behave in this way, e.g. allyl (η to η) and naphthalene (η to η). Nitric oxide typically binds to metals to make a linear MNO arrangement, wherein the nitrogen oxide is said to donate 3e linear NO ligand to a 1e bent NO ligand. | 0 | Theoretical and Fundamental Chemistry |
The basis of a sigma hole interaction is an energetically stabilizing interaction between a positively charged site (sigma hole) and a negatively charged site (lone pair) on different atoms. The positive site is produced by a covalent sigma bond between the atom hosting the sigma hole and a neighboring atom. The presence of the bond results in the distortion of the electron density around the host atom, with the density increasing equatorially (with respect to the bond) about the atom but decreasing along the extension of the bond. Through this mechanism, a region of positive electrostatic potential, termed a sigma hole, can be localized onto the surface of an atom bearing a sigma bond. This sigma hole could then engage in electrostatic interactions with a lone pair associated with a negative electrostatic potential.
In addition to the electrostatic interaction described above, dispersive forces are also thought to play a role in the overall interaction. Studies have found electrostatic and dispersive contributions to be roughly comparable in magnitude, and for the dominant contributor to vary from system to system.
Alternatively, sigma hole pair interactions can be conceptualized in terms of the mixing of molecular orbitals. The occupied sigma bonding orbital associated with the bond would give rise to a corresponding unoccupied sigma antibonding orbital lying on the opposite face of the atom. Mixing between the antibonding orbital and the occupied orbital associated with a lone pair would be expected to result in energetic stabilization.
Several atoms, including those which are relatively electronegative (such as Chlorine, Oxygen, and even Fluorine) can act as positive sites in sigma hole pair interactions. Counterintuitively, this can occur even when the atom acting as the positive site has an overall negative partial charge. The solution to this apparent contradiction lies in the anisotropy in the electron cloud introduced by the presence of the sigma bond. If the electronic charge is not evenly distributed around the nucleus, it remains possible for a positive partial charge to develop opposite the sigma bond in the region of electron depletion. This partial positive charge coexists with a partial negative charge of larger magnitude associated with the more electron-rich regions of the atomic surface, which results in an overall negative partial charge. | 0 | Theoretical and Fundamental Chemistry |
Biohydrometallurgy is a technique in the world of metallurgy that utilizes biological agents (bacteria) to recover and treat metals such as copper. Modern biohydrometallurgy advances started with the bioleaching of copper more efficiently in the 1950's | 1 | Applied and Interdisciplinary Chemistry |
There are a few known ways that tetrose sugars are used in nature. Some are seen in metabolic pathways and others are known to affect certain enzymes. | 1 | Applied and Interdisciplinary Chemistry |
pIII is the protein that determines the infectivity of the virion. pIII is composed of three domains (N1, N2 and CT) connected by glycine-rich linkers. The N2 domain binds to the F pilus during virion infection freeing the N1 domain which then interacts with a TolA protein on the surface of the bacterium. Insertions within this protein are usually added in position 249 (within a linker region between CT and N2), position 198 (within the N2 domain) and at the N-terminus (inserted between the N-terminal secretion sequence and the N-terminus of pIII). However, when using the BamHI site located at position 198 one must be careful of the unpaired Cysteine residue (C201) that could cause problems during phage display if one is using a non-truncated version of pIII.
An advantage of using pIII rather than pVIII is that pIII allows for monovalent display when using a phagemid (plasmid derived from Ff phages) combined with a helper phage. Moreover, pIII allows for the insertion of larger protein sequences (>100 amino acids) and is more tolerant to it than pVIII. However, using pIII as the fusion partner can lead to a decrease in phage infectivity leading to problems such as selection bias caused by difference in phage growth rate or even worse, the phage's inability to infect its host. Loss of phage infectivity can be avoided by using a phagemid plasmid and a helper phage so that the resultant phage contains both wild type and fusion pIII.
cDNA has also been analyzed using pIII via a two complementary leucine zippers system, Direct Interaction Rescue or by adding an 8-10 amino acid linker between the cDNA and pIII at the C-terminus. | 1 | Applied and Interdisciplinary Chemistry |
In materials science and engineering, there is often interest in understanding the forces or stresses involved in the deformation of a material. For instance, if the material were a simple spring, the answer would be given by Hookes law, which says that the force experienced by a spring is proportional to the distance displaced from equilibrium. Stresses which can be attributed to the deformation of a material from some rest state are called elastic stresses. In other materials, stresses are present which can be attributed to the deformation rate over time. These are called viscous stresses. For instance, in a fluid such as water the stresses which arise from shearing the fluid do not depend on the distance the fluid has been sheared; rather, they depend on how quickly' the shearing occurs.
Viscosity is the material property which relates the viscous stresses in a material to the rate of change of a deformation (the strain rate). Although it applies to general flows, it is easy to visualize and define in a simple shearing flow, such as a planar Couette flow.
In the Couette flow, a fluid is trapped between two infinitely large plates, one fixed and one in parallel motion at constant speed (see illustration to the right). If the speed of the top plate is low enough (to avoid turbulence), then in steady state the fluid particles move parallel to it, and their speed varies from at the bottom to at the top. Each layer of fluid moves faster than the one just below it, and friction between them gives rise to a force resisting their relative motion. In particular, the fluid applies on the top plate a force in the direction opposite to its motion, and an equal but opposite force on the bottom plate. An external force is therefore required in order to keep the top plate moving at constant speed.
In many fluids, the flow velocity is observed to vary linearly from zero at the bottom to at the top. Moreover, the magnitude of the force, , acting on the top plate is found to be proportional to the speed and the area of each plate, and inversely proportional to their separation :
The proportionality factor is the dynamic viscosity of the fluid, often simply referred to as the viscosity. It is denoted by the Greek letter mu (). The dynamic viscosity has the dimensions , therefore resulting in the SI units and the derived units:
: <math>
[\mu]
= \frac {\rm kg} {\rm m{\cdot}s}
= \frac {\rm N} {\rm m^2}{\cdot}{\rm s}
= {\rm Pa{\cdot}s}
energy per unit volume multiplied by time.
The aforementioned ratio is called the rate of shear deformation or shear velocity, and is the derivative of the fluid speed in the direction parallel to the normal vector of the plates (see illustrations to the right). If the velocity does not vary linearly with , then the appropriate generalization is:
where , and is the local shear velocity. This expression is referred to as Newtons law of viscosity. In shearing flows with planar symmetry, it is what defines' . It is a special case of the general definition of viscosity (see below), which can be expressed in coordinate-free form.
Use of the Greek letter mu () for the dynamic viscosity (sometimes also called the absolute viscosity) is common among mechanical and chemical engineers, as well as mathematicians and physicists. However, the Greek letter eta () is also used by chemists, physicists, and the IUPAC. The viscosity is sometimes also called the shear viscosity. However, at least one author discourages the use of this terminology, noting that can appear in non-shearing flows in addition to shearing flows. | 1 | Applied and Interdisciplinary Chemistry |
Bents rule can be extended to rationalize the hybridization of nonbonding orbitals as well. On the one hand, a lone pair (an occupied nonbonding orbital) can be thought of as the limiting case of an electropositive substituent, with electron density completely polarized towards the central atom. Bents rule predicts that, in order to stabilize the unshared, closely held nonbonding electrons, lone pair orbitals should take on high s character. On the other hand, an unoccupied (empty) nonbonding orbital can be thought of as the limiting case of an electronegative substituent, with electron density completely polarized towards the ligand and away from the central atom. Bents rule predicts that, in order to leave as much s character as possible for the remaining occupied orbitals, unoccupied nonbonding orbitals should maximize p character'.
Experimentally, the first conclusion is in line with the reduced bond angles of molecules with lone pairs like water or ammonia compared to methane, while the second conclusion accords with the planar structure of molecules with unoccupied nonbonding orbitals, like monomeric borane and carbenium ions. | 0 | Theoretical and Fundamental Chemistry |
The off-target activity of an active nuclease may lead to unwanted double-strand breaks and may consequently yield chromosomal rearrangements and/or cell death. Studies have been carried out to compare the relative nuclease-associated toxicity of available technologies. Based on these studies and the maximal theoretical distance between DNA binding and nuclease activity, TALEN constructs are believed to have the greatest precision of the currently available technologies. | 1 | Applied and Interdisciplinary Chemistry |
In multi-exponential fitting, the time-resolved curves are fitted with an exponential decay model to determine the decay constants. While this method is straightforward, it has low accuracy. | 0 | Theoretical and Fundamental Chemistry |
Vitrification is the progressive partial fusion of a clay, or of a body, as a result of a firing process. As vitrification proceeds, the proportion of glassy bond increases and the apparent porosity of the fired product becomes progressively lower. Vitreous bodies have open porosity, and may be either opaque or translucent. In this context, "zero porosity" may be defined as less than 1% water absorption. However, various standard procedures define the conditions of water absorption. An example is by ASTM, who state "The term vitreous generally signifies less than 0.5% absorption, except for floor and wall tile and low-voltage electrical insulators, which are considered vitreous up to 3% water absorption."
Pottery can be made impermeable to water by glazing or by vitrification. Porcelain, bone china, and sanitaryware are examples of vitrified pottery, and are impermeable even without glaze. Stoneware may be vitrified or semi-vitrified; the latter type would not be impermeable without glaze. | 1 | Applied and Interdisciplinary Chemistry |
In the first system, a wild-type Moloney Murine Leukemia Virus (M-MLV) reverse transcriptase was fused to the Cas9 H840A nickase C-terminus. Detectable editing efficiencies were observed. | 1 | Applied and Interdisciplinary Chemistry |
British chemist Henry Cavendish, the discoverer of hydrogen in 1766, discovered that air is composed of more gases than nitrogen and oxygen. He recorded these findings in 1784 and 1785; among them, he found a then-unidentified gas less reactive than nitrogen. Helium was first reported in 1868; the report was based on the new technique of spectroscopy; some spectral lines in light emitted by the Sun did not match those of any of the known elements. Mendeleev was not convinced by this finding since variance of temperature led to change of intensity of spectral lines and their location on the spectrum; this opinion was held by some other scientists of the day. Others believed the spectral lines could belong to an element that occurred on the Sun but not on Earth; some believed it was yet to be found on Earth.
In 1894, British chemist William Ramsay and British physicist Lord Rayleigh isolated argon from air and determined that it was a new element. Argon, however, did not engage in any chemical reactions and was—highly unusually for a gas—monatomic; it did not fit into the periodic law and thus challenged the very notion of it. Not all scientists immediately accepted this report; Mendeleev's original response was that argon was a triatomic form of nitrogen rather than an element of its own. While the notion of a possibility of a group between that of halogens and that of alkali metals had existed (some scientists believed that several atomic weight values between halogens and alkali metals were missing, especially since places in this half of group VIII remained vacant), argon did not easily match the position between chlorine and potassium because its atomic weight exceeded those of both chlorine and potassium. Other explanations were proposed; for example, Ramsay supposed argon could be a mixture of different gases. For a while, Ramsay believed argon could be a mixture of three gases of similar atomic weights; this triad would resemble the triad of iron, cobalt, and nickel, and be similarly placed in group VIII. Certain that shorter periods contain triads of gases at their ends, Ramsay suggested in 1898 the existence of a gas between helium and argon with an atomic weight of 20; after its discovery later that year (it was named neon), Ramsay continued to interpret it as a member of a horizontal triad at the end of that period.
In 1896, Ramsay tested a report of American chemist William Francis Hillebrand, who found a stream of an unreactive gas from a sample of uraninite. Wishing to prove it was nitrogen, Ramsay analyzed a different uranium mineral, cleveite, and found a new element, which he named krypton. This finding was corrected by British chemist William Crookes, who matched its spectrum to that of the Suns helium. Following this discovery, Ramsay, using fractional distillation to separate the components air, discovered several more such gases in 1898: metargon, krypton, neon, and xenon; detailed spectroscopic analysis of the first of these demonstrated it was argon contaminated by a carbon-based impurity. Ramsay was initially skeptical about the existence of gases heavier than argon, and the discovery of krypton and xenon came as a surprise to him; however, Ramsay accepted his own discovery, and the five newly discovered inert gases (now noble gases) were placed in a single column in the periodic table. Although Mendeleevs table predicted several undiscovered elements, it did not predict the existence of such inert gases, and Mendeleev originally rejected those findings as well. | 1 | Applied and Interdisciplinary Chemistry |
D-luciferin is the substrate for firefly luciferases bioluminescence reaction, while L-luciferin is the substrate for luciferyl-CoA synthetase activity. Both reactions are inhibited by the substrates enantiomer: L-luciferin and D-luciferin inhibit the bioluminescence pathway and the CoA-ligase pathway, respectively. This shows that luciferase can differentiate between the isomers of the luciferin structure.
L-luciferin is able to emit a weak light even though it is a competitive inhibitor of D-luciferin and the bioluminescence pathway. Light is emitted because the CoA synthesis pathway can be converted to the bioluminescence reaction by hydrolyzing the final product via an esterase back to D-luciferin.
Luciferase activity is additionally inhibited by oxyluciferin and allosterically activated by ATP. When ATP binds to the enzymes two allosteric sites, luciferases affinity to bind ATP in its active site increases. | 1 | Applied and Interdisciplinary Chemistry |
The deep ocean harbors more than 98% of the dissolved inorganic carbon pool, along with a rapid sedimentation rate that results in low particulate organic carbon inputs. It is yet to be resolved what effect microbes have on the global carbon cycle. Studies show that microbes in the deep ocean are not dormant, but are metabolically active and must be participating in nutrient cycling by not only heterotrophs but by autotrophs as well. There is a mismatch from the microbial carbon demand in the deep ocean and the carbon export from the surface ocean. Dissolved inorganic carbon fixation is on similar orders of magnitude as heterotrophic microbes in the surface ocean. Model-based data reveal that dissolved inorganic carbon fixation ranges from 1 mmol C m d to 2.5 mmol C m d. | 0 | Theoretical and Fundamental Chemistry |
Local contamination from radium-based radioluminescent paints having been improperly disposed of is not unknown. | 0 | Theoretical and Fundamental Chemistry |
Levoketoconazole, sold under the brand name Recorlev, is a steroidogenesis inhibitor that is used for the treatment of Cushing's syndrome. Levoketoconazole was approved for medical use in the United States in December 2021.
Levoketoconazole is the levorotatory or (2S,4R) enantiomer of ketoconazole, and it is an inhibitor of the enzymes CYP11B1 (11β-hydroxylase), CYP17A1 (17α-hydroxylase/17,20-lyase), and CYP21A2 (21-hydroxylase). It inhibits glucocorticoid biosynthesis and hence circulating levels of glucocorticoids, thereby treating Cushing's syndrome. In addition to its increased potency, the drug is 12-fold less potent than racemic ketoconazole in inhibiting CYP7A1 (cholesterol 7α-hydroxylase), theoretically resulting in further reduced interference with bile acid production and metabolite elimination and therefore less risk of hepatotoxicity. Levoketoconazole has also been found to inhibit CYP11A1 (cholesterol side-chain cleavage enzyme) and CYP51A1 (lanosterol-14α-demethylase), similarly but more potently relative to ketoconazole. | 0 | Theoretical and Fundamental Chemistry |
Methyl yellow, or C.I. 11020, is an organic compound with the formula CHNCHN(CH). It is an azo dye derived from dimethylaniline. It is a yellow solid. According to X-ray crystallography, the CN core of the molecule is planar.
It is used as a dye for plastics and may be used as a pH indicator. In aqueous solution at low pH, methyl yellow appears red. Between pH 2.9 and 4.0, methyl yellow undergoes a transition, to become yellow above pH 4.0. | 0 | Theoretical and Fundamental Chemistry |
Current scRNA-Seq protocols involve the following steps: isolation of single cell and RNA, reverse transcription (RT), amplification, library generation and sequencing. Single cells are either mechanically separated into microwells (e.g., BD Rhapsody, Takara ICELL8, Vycap Puncher Platform, or CellMicrosystems CellRaft) or encapsulated in droplets (e.g., 10x Genomics Chromium, Illumina Bio-Rad ddSEQ, 1CellBio InDrop, Dolomite Bio Nadia). Single cells are labeled by adding beads with barcoded oligonucleotides; both cells and beads are supplied in limited amounts such that co-occupancy with multiple cells and beads is a very rare event. Once reverse transcription is complete, the cDNAs from many cells can be mixed together for sequencing; transcripts from a particular cell are identified by each cell's unique barcode. Unique molecular identifier (UMIs) can be attached to mRNA/cDNA target sequences to help identify artifacts during library preparation.
Challenges for scRNA-Seq include preserving the initial relative abundance of mRNA in a cell and identifying rare transcripts. The reverse transcription step is critical as the efficiency of the RT reaction determines how much of the cells RNA population will be eventually analyzed by the sequencer. The processivity of reverse transcriptases and the priming strategies used may affect full-length cDNA production and the generation of libraries biased toward the 3’ or 5 end of genes.
In the amplification step, either PCR or in vitro transcription (IVT) is currently used to amplify cDNA. One of the advantages of PCR-based methods is the ability to generate full-length cDNA. However, different PCR efficiency on particular sequences (for instance, GC content and snapback structure) may also be exponentially amplified, producing libraries with uneven coverage. On the other hand, while libraries generated by IVT can avoid PCR-induced sequence bias, specific sequences may be transcribed inefficiently, thus causing sequence drop-out or generating incomplete sequences.
Several scRNA-Seq protocols have been published:
Tang et al.,
STRT,
SMART-seq,
CEL-seq,
RAGE-seq, Quartz-seq and C1-CAGE. These protocols differ in terms of strategies for reverse transcription, cDNA synthesis and amplification, and the possibility to accommodate sequence-specific barcodes (i.e. UMIs) or the ability to process pooled samples.
In 2017, two approaches were introduced to simultaneously measure single-cell mRNA and protein expression through oligonucleotide-labeled antibodies known as REAP-seq, and CITE-seq. | 1 | Applied and Interdisciplinary Chemistry |
It is thought that early scleraxis-expressing progenitor cells lead to the eventual formation of tendon tissue and other muscle attachments. Scleraxis is involved in mesoderm formation and is expressed in the syndetome (a collection of embryonic tissue that develops into tendon and blood vessels) of developing somites (primitive segments or compartments of embryos). | 1 | Applied and Interdisciplinary Chemistry |
For the stoichiometric reactions involving alkali metal or alkaline earth acetylides, work-up for the reaction requires liberation of the alcohol. To achieve this hydrolysis, aqueous acids are often employed.
Common solvents for the reaction include ethers, acetals, dimethylformamide, and dimethyl sulfoxide. | 0 | Theoretical and Fundamental Chemistry |
Most asymmetric Heck reactions employing chiral phosphines proceed by the cationic pathway, which does not require the dissociation of a phosphine ligand. Oxidative addition of an aryl perfluorosulfonate generates a cationic palladium aryl complex V. The mechanism then proceeds as in the neutral case, with the difference that an extra site of coordinative unsaturation exists on palladium throughout the process.
Thus, coordination of the alkene does not require ligand dissociation. Stoichiometric amounts of base are still required to reduce the palladium(II)-hydrido complex VIII back to palladium(0). Silver salts may be used to initiate the cationic pathway in reactions of aryl halides. | 0 | Theoretical and Fundamental Chemistry |
The Henderson–Hasselbach equation gives the pH of a solution relative to the pK of the acid–base pair. However the pK is dependent on ionic strength and temperature, and as it shifts so will the pH of a solution based on that acid–base pair. Because the doubly charged [HPO] is stabilized more by high ionic strength than is the singly-charged [HPO], their pK is somewhat dependent on ionic strength. The often-cited pK of ~7.2 is the value extrapolated to zero ionic strength, and is not applicable at physiological ionic strength.
Phillips et al. measured the pK at 10, 25, and 37 °C at various ionic strengths. For the latter two temperatures they report pK in Debye-Hückel equations (plotted in the accompanying figure for µ up to 0.5 M):<br>
at 25 °C: pKa = 7.18 − 1.52 sqrt(µ) + 1.96 µ <br>
at 37 °C: pKa = 7.15 − 1.56 sqrt(µ) + 1.22 µ
The pK is weakly dependent on temperature. Phillips et al. reported ∆H at 25 °C of 760 cal/mol (3180 J/mol) and a linear dependence of pK on 1/T (Van t Hoff equation). The positive ∆H results in an increase in K, and thus a decrease in pK with rising temperature, the change in pKa being 166 × the change in (1/T), which around 25 °C results in a change in pK of −0.00187 per degree. This applies strictly to the extrapolated thermodynamic pK' at infinite dilution, and as the figure shows, the temperature effect can be much larger at higher ionic strength. | 1 | Applied and Interdisciplinary Chemistry |
The term muscle tissue engineering, while it is a subset of the much larger discipline, tissue engineering, was first coined in 1988 when Herman Vandenburgh, a surgeon, cultured avian myotubes in collagen-coated culture plates. This started a new era of in vitro tissue engineering. The ideal was officially adopted in 1988 in Vandenburgh's publication titled Maintenance of Highly Contractile Tissue-Cultured Avian Skeletal Myotubes in Collagen Gel. In 1989, the same group determined that mechanical stimulation of myoblasts in vitro facilitates engineered skeletal muscle growth. | 1 | Applied and Interdisciplinary Chemistry |
Due to the cohesive forces, a molecule located away from the surface is pulled equally in every direction by neighboring liquid molecules, resulting in a net force of zero. The molecules at the surface do not have the same molecules on all sides of them and therefore are pulled inward. This creates some internal pressure and forces liquid surfaces to contract to the minimum area.
There is also a tension parallel to the surface at the liquid-air interface which will resist an external force, due to the cohesive nature of water molecules.
The forces of attraction acting between molecules of the same type are called cohesive forces, while those acting between molecules of different types are called adhesive forces. The balance between the cohesion of the liquid and its adhesion to the material of the container determines the degree of wetting, the contact angle, and the shape of meniscus. When cohesion dominates (specifically, adhesion energy is less than half of cohesion energy) the wetting is low and the meniscus is convex at a vertical wall (as for mercury in a glass container). On the other hand, when adhesion dominates (when adhesion energy is more than half of cohesion energy) the wetting is high and the similar meniscus is concave (as in water in a glass).
Surface tension is responsible for the shape of liquid droplets. Although easily deformed, droplets of water tend to be pulled into a spherical shape by the imbalance in cohesive forces of the surface layer. In the absence of other forces, drops of virtually all liquids would be approximately spherical. The spherical shape minimizes the necessary "wall tension" of the surface layer according to Laplace's law.
Another way to view surface tension is in terms of energy. A molecule in contact with a neighbor is in a lower state of energy than if it were alone. The interior molecules have as many neighbors as they can possibly have, but the boundary molecules are missing neighbors (compared to interior molecules) and therefore have higher energy. For the liquid to minimize its energy state, the number of higher energy boundary molecules must be minimized. The minimized number of boundary molecules results in a minimal surface area.
As a result of surface area minimization, a surface will assume a smooth shape. | 0 | Theoretical and Fundamental Chemistry |
Safranines are the azonium compounds of symmetrical 2,8-dimethyl-3,7-diaminophenazine. They are obtained by the joint oxidation of one molecule of a para-diamine with two molecules of a primary amine; by the condensation of para-aminoazo compounds with primary amines, and by the action of para-nitrosodialkylanilines with secondary bases such as diphenylmetaphenylenediamine. They are crystalline solids showing a characteristic green metallic lustre; they are readily soluble in water and dye red or violet. They are strong bases and form stable monacid salts. Their alcoholic solution shows a yellow-red fluorescence.
Phenosafranine is not very stable in the free state; its chloride forms green plates. It can be readily diazotized, and the diazonium salt when boiled with alcohol yields aposafranine or benzene induline, CHN. Friedrich Kehrmann showed that aposafranine could be diazotized in the presence of cold concentrated sulfuric acid, and the diazonium salt on boiling with alcohol yielded phenylphenazonium salts. Aposafranone, CHNO, is formed by heating aposafranine with concentrated hydrochloric acid. These three compounds are perhaps to be represented as ortho- or as para-quinones. The "safranine" of commerce is an ortho-tolusafranine. The first aniline dye-stuff to be prepared on a manufacturing scale was mauveine, which was obtained by Sir William Henry Perkin by heating crude aniline with potassium dichromate and sulfuric acid.
Mauveine was converted to parasafranine (1,8-dimethylsafranine) by Perkin in 1878 by oxidative/reductive loss of the 7N-para-tolyl group.
Another well known safranin is phenosafranine (C.I. 50200, 3,7-diamino-5-phenylphenazinium chloride) widely used as a histological dye, photosensitizer and redox probe. | 0 | Theoretical and Fundamental Chemistry |
Due to its relatively short turnover time of ~6 weeks in the human body, Cu serves as an important indicator of cancer and other diseases that rapidly evolve. The serum of cancer patients contains significantly higher levels of Cu than that of healthy patients due to copper chelation by lactate, which is produced via anaerobic glycolysis by tumor cells. These imbalances in Cu homeostasis are reflected isotopically in the serum and organ tissues of patients with various types of cancer, where the serum of cancer patients is generally Cu-depleted relative to the serum of healthy patients, while organ tumors are generally Cu-enriched. In one study, the blood components of patients with hepatocellular carcinomas (HCC) was found to be, on average, depleted in Cu by 0.4‰ relative to the blood of non-cancer patients. In particular, the δCu values of the serum in patients with HCC ranged from -0.66 to +0.47‰ (compared to serum δCu values of -0.39 to +0.38‰ in matched control patients), and the δCu values of the erythrocytes in the HCC patients ranged from -0.07 to +0.92‰ (compared to erythrocyte δCu values of +0.57 to +1.24‰ in matched control patients). The liver tumor tissues in the HCC patients were Cu-enriched relative to healthy liver tissue in the same patients (δCu = -0.02 to +0.43‰; δCu = -0.45 to -0.11‰), and the magnitude of Cu-enrichment mirrored that of the Cu-depletion observed in the cancer patients' serum. Though our understanding of how copper isotopes are fractionated during cancer physiologies is still limited, it is clear that copper isotope ratios may serve as a powerful biomarker of cancer presence and progression. | 0 | Theoretical and Fundamental Chemistry |
no large clinical trials of CoQ in cancer treatment had been conducted. The US's National Cancer Institute identified issues with the few, small studies that had been carried out, stating, "the way the studies were done and the amount of information reported made it unclear if benefits were caused by the CoQ or by something else". The American Cancer Society concluded, "CoQ may reduce the effectiveness of chemo and radiation therapy, so most oncologists would recommend avoiding it during cancer treatment." | 1 | Applied and Interdisciplinary Chemistry |
The timing electronics is needed to losslessly reconstruct the histogram of the distribution of time of flight of photons. This is done by using the technique of time-correlated single photon counting (TCSPC), where the individual photon arrival times are marked with respect to a start/stop signal provided by the periodic laser cycle. These time-stamps can then be used to build up histograms of photon arrival times.
The two main types of timing electronics are based on a combination of time-to-analog converter (TAC) and an analog-to-digital converter (ADC), and time-to-digital converter (TDC), respectively. In the first case, the difference between the start and the stop signal is converted into an analog voltage signal, which is then processed by the ADC. In the second method, the delay is directly converted into a digital signal. Systems based on ADCs generally have a better timing resolution and linearity while being expensive and the capability of being integrated. TDCs, on the other hand, can be integrated into a single chip and hence are better suited in multi-channel systems. However, they have a worse timing performance and can handle much lower sustained count-rates. | 0 | Theoretical and Fundamental Chemistry |
Cross-shelf transport, the exchange of water between coastal and offshore environments, is of particular interest for its role in delivering meroplanktonic larvae to often disparate adult populations from shared offshore larval pools. Several mechanisms have been proposed for the cross-shelf of planktonic larvae by internal waves. The prevalence of each type of event depends on a variety of factors including bottom topography, stratification of the water body, and tidal influences. | 1 | Applied and Interdisciplinary Chemistry |
Direct reduced iron (DRI), also called sponge iron, is produced from the direct reduction of iron ore (in the form of lumps, pellets, or fines) into iron by a reducing gas which either contains elemental carbon (produced from natural gas or coal) or hydrogen. When hydrogen is used as the reducing gas there are no greenhouse gases produced. Many ores are suitable for direct reduction.
Direct reduction refers to solid-state processes which reduce iron oxides to metallic iron at temperatures below the melting point of iron. Reduced iron derives its name from these processes, one example being heating iron ore in a furnace at a high temperature of in the presence of the reducing gas syngas, a mixture of hydrogen and carbon monoxide, or pure hydrogen. | 1 | Applied and Interdisciplinary Chemistry |
Geiger counter is a colloquial name for any hand-held radiation measuring device in civil defense, but most civil defense devices were ion-chamber radiological survey meters capable of measuring only high levels of radiation that would be present after a major nuclear event.
Most Geiger and ion-chamber survey meters were issued by governmental civil defense organizations in several countries from the 1950s in the midst of the Cold War in an effort to help prepare citizens for a nuclear attack.
Many of these same instruments are still in use today by some states, Texas amongst them, under the jurisdiction of the Texas Bureau of Radiation Control. They are regularly maintained, calibrated and deployed to fire departments and other emergency services. | 0 | Theoretical and Fundamental Chemistry |
Transactivation can be triggered either by endogenous cellular or viral proteins, also called transactivators. These protein factors act in trans (i.e., intermolecularly). HIV and HTLV are just two of the many viruses that encode transactivators to enhance viral gene expression. These transactivators can also be linked to cancer if they start interacting with, and increasing expression of, a cellular proto-oncogene. HTLV, for instance, has been associated with causing leukemia primarily through this process. Its transactivator, Tax, can interact with p40, inducing overexpression of interleukin 2, interleukin receptors, GM-CSF and the transcription factor c-Fos. HTLV infects T-cells and via the increased expression of these stimulatory cytokines and transcription factors, leads to uncontrolled proliferation of T-cells and hence lymphoma. | 1 | Applied and Interdisciplinary Chemistry |
Negative ion products are products which claim to release negative ions and create positive health effects, although these claims are unsupported. Many also claim to protect users from 5G radiation. These claims are likewise unsubstantiated. A market has developed for these products due to conspiracy theories about 5G. Many of these contain radioactive substances. In a test of these bracelets by the International Journal of Environmental Research and Public Health, samples were found to have a yearly dose of up to 1.22 millisieverts a year, well in excess of the 1 millisievert limit recommended by the International Commission on Radiological Protection. As a result, they were banned in the Netherlands. | 0 | Theoretical and Fundamental Chemistry |
The concept that individuals might have a "metabolic profile" that could be reflected in the makeup of their biological fluids was introduced by Roger Williams in the late 1940s, who used paper chromatography to suggest characteristic metabolic patterns in urine and saliva were associated with diseases such as schizophrenia. However, it was only through technological advancements in the 1960s and 1970s that it became feasible to quantitatively (as opposed to qualitatively) measure metabolic profiles. The term "metabolic profile" was introduced by Horning, et al. in 1971 after they demonstrated that gas chromatography-mass spectrometry (GC-MS) could be used to measure compounds present in human urine and tissue extracts. The Horning group, along with that of Linus Pauling and Arthur B. Robinson led the development of GC-MS methods to monitor the metabolites present in urine through the 1970s.
Concurrently, NMR spectroscopy, which was discovered in the 1940s, was also undergoing rapid advances. In 1974, Seeley et al. demonstrated the utility of using NMR to detect metabolites in unmodified biological samples. This first study on muscle highlighted the value of NMR in that it was determined that 90% of cellular ATP is complexed with magnesium. As sensitivity has improved with the evolution of higher magnetic field strengths and magic angle spinning, NMR continues to be a leading analytical tool to investigate metabolism. Recent efforts to utilize NMR for metabolomics have been largely driven by the laboratory of Jeremy K. Nicholson at Birkbeck College, University of London and later at Imperial College London. In 1984, Nicholson showed H NMR spectroscopy could potentially be used to diagnose diabetes mellitus, and later pioneered the application of pattern recognition methods to NMR spectroscopic data.
In 1994 and 1996, liquid chromatography mass spectrometry metabolomics experiments were performed by Gary Siuzdak while working with Richard Lerner (then president of the Scripps Research Institute) and Benjamin Cravatt, to analyze the cerebral spinal fluid from sleep deprived animals. One molecule of particular interest, oleamide, was observed and later shown to have sleep inducing properties. This work is one of the earliest such experiments combining liquid chromatography and mass spectrometry in metabolomics.
In 2005, the first metabolomics tandem mass spectrometry database, METLIN, for characterizing human metabolites was developed in the Siuzdak laboratory at the Scripps Research Institute. METLIN has since grown and as of December, 2023, METLIN contains MS/MS experimental data on over 930,000 molecular standards and other chemical entities, each compound having experimental tandem mass spectrometry data generated from molecular standards at multiple collision energies and in positive and negative ionization modes. METLIN is the largest repository of tandem mass spectrometry data of its kind. The dedicated academic journal Metabolomics first appeared in 2005, founded by its current editor-in-chief Roy Goodacre.
In 2005, the Siuzdak lab was engaged in identifying metabolites associated with sepsis and in an effort to address the issue of statistically identifying the most relevant dysregulated metabolites across hundreds of LC/MS datasets, the first algorithm was developed to allow for the nonlinear alignment of mass spectrometry metabolomics data. Called XCMS, it has since (2012) been developed as an online tool and as of 2019 (with METLIN) has over 30,000 registered users.
On 23 January 2007, the Human Metabolome Project, led by David S. Wishart, completed the first draft of the human metabolome, consisting of a database of approximately 2,500 metabolites, 1,200 drugs and 3,500 food components. Similar projects have been underway in several plant species, most notably Medicago truncatula and Arabidopsis thaliana for several years.
As late as mid-2010, metabolomics was still considered an "emerging field". Further, it was noted that further progress in the field depended in large part, through addressing otherwise "irresolvable technical challenges", by technical evolution of mass spectrometry instrumentation.
In 2015, real-time metabolome profiling was demonstrated for the first time. | 1 | Applied and Interdisciplinary Chemistry |
LC–MS is widely used in the field of bioanalysis and is specially involved in pharmacokinetic studies of pharmaceuticals. Pharmacokinetic studies are needed to determine how quickly a drug will be cleared from the body organs and the hepatic blood flow. MS analyzers are useful in these studies because of their shorter analysis time, and higher sensitivity and specificity compared to UV detectors commonly attached to HPLC systems. One major advantage is the use of tandem MS–MS, where the detector may be programmed to select certain ions to fragment. The measured quantity is the sum of molecule fragments chosen by the operator. As long as there are no interferences or ion suppression in LC–MS, the LC separation can be quite quick. | 0 | Theoretical and Fundamental Chemistry |
β-blockers' binding site to the receptor is the same as for endogenous catecholamines, such as noradrenaline and adrenaline. This binding is based on hydrogen bonds between the β-blocker and the receptor, and therefore not based on covalent bonds, which results in the reversibility of the binding. A significant step in the development of β adrenergic antagonists was the discovery that an oxymethylene bridge (—OCH—, figure 7) could be inserted into the arylethanolamine structure of pronethalol to produce propranolol. Propranolol is an aryloxypropanolamine, which are more potent β-blockers than arylethanolamines. Today, most of the β-blockers used clinically are aryloxypropanolamines. The length of the side chain is increased when an oxymethylene bridge is introduced. It has been shown that the side chains of aryloxypropanolamine can adopt a conformation that puts the hydroxyl and amine groups in more or less the same position as with beta blocker that do not have this group as a part of the side chain.
After the release of propranolol, relative lipophilicity of β-blockers as a significant factor in their varied and complex pharmacology, became an important factor. It was suspected that propranolols centrally induced side effects could be due to its high lipophilicity. Thus, it was focused on synthesizing analogues with hydrophilic moieties, favourably placed to see if the side effects would decrease. Selecting para-acylamino groups as the hydrophilic moiety, scientists synthesized a group of para-acylphenoxyethanol and propanolamines, and selected practolol for clinical trials. Practolol had one property not previously seen with β-blockers, it exhibited cardioselectivity (β selectivity). Studies from practolol showed that moving the acylamino group to meta or ortho positions, on the benzene ring, caused a loss of selectivity but not loss of the β-blockade itself. This illustrated the significance of para'-substitution for β selectivity of β-blockers.
Figure 8 shows the structure-activity relationship (SAR) for β-blockers. For the function of a β-blocker it's essential for the compound to contain an aromatic ring and a β-ethanolamine. The aromatic ring can either be benzoheterocyclic (such as indole) or heterocyclic (such as thiadiazole). This is mandatory. The side chains can be variable:
* The X part of the side chain can either be directly linked to the aromatic ring or linked through a —OCH— group
* When X is —CHCH—, —CH=CH—, —SCH— or —NCH—, there is little or no activity
* The R group can only be a secondary substitution and branched is the optimal choice
* Alkyl (—CH) substituents on the α, β or γ carbon (if X = —OCH—) lower beta blockade, especially at the α carbon
The general rule for aromatic substitution is: ortho > meta > para. This gives non-selective β-blockers. Large para-substituents usually decrease activity but large ortho-groups retain some activity. Polysubstitution on carbon 2 and 6 makes the compound inactive but when the substitution is on carbon 3 and 5 theres some activity. For the highest cardioselectivity, the substituents should be as following: para > meta > ortho. All the β-blockade is in one isomer, (S)-aryloxypropylamine and (R')-ethanolamine. | 1 | Applied and Interdisciplinary Chemistry |
Pomalidomide was submitted for FDA approval on April 26, 2012 and on 21 June it was announced that the drug would get standard FDA review. A marketing authorization application was filed to EMA 21 June 2012, where a decision could come as soon as early 2013. EMA has already granted pomalidomide an orphan designation for primary myelofibrosis, MM, systemic sclerosis, post-polycythaemia and post-essential thrombocythaemia myelofibrosis. | 1 | Applied and Interdisciplinary Chemistry |
Reduced frequency is the dimensionless number used in general for the case of unsteady aerodynamics and aeroelasticity. It is one of the parameters that defines the degree of unsteadiness of the problem.
For the case of flutter analysis, lift history for the motion obtained from the Wagner analysis (Herbert A. Wagner) with varying frequency of oscillation shows that magnitude of lift decreases and a phase lag develops between the aircraft motion and the unsteady aerodynamic forces. Reduced frequency can be used to explain the amplitude attenuation and the phase lag of the unsteady aerodynamic forces compared to the quasi steady analysis (which in theory assumes no phase lag).
Reduced frequency is denoted by the letter "k" and given by the expression
where:
* ω = circular frequency
* b = airfoil semi-chord
* V = flow velocity
The semi-chord is used instead of the chord due to its use in the derivation of unsteady lift based on thin airfoil theory. Based on the value of reduced frequency "k", we can roughly divide the flow into:
# Steady state aerodynamics – k=0
# Quasi-steady aerodynamics – 0≤k≤0.05
# Unsteady aerodynamics – k>0.05 [k>0.2 is considered highly unsteady] | 1 | Applied and Interdisciplinary Chemistry |
Some enzymes can function as electrocatalysts. Nitrogenase, an enzyme that contains a MoFe cluster, can be leveraged to fix atmospheric nitrogen, i.e. convert nitrogen gas into molecules such as ammonia. Immobilizing the protein onto an electrode surface and employing an electron mediator greatly improves the efficiency of this process. The effectiveness of bioelectrocatalysts generally depends on the ease of electron transport between the active site of the enzyme and the electrode surface. Other enzymes provide insight for the development of synthetic catalysts. For example, formate dehydrogenase, a nickel-containing enzyme, has inspired the development of synthetic complexes with similar molecular structures for use in CO reduction. Microbial fuel cells are another way that biological systems can be leveraged for electrocatalytic applications. Microbial-based systems leverage the metabolic pathways of an entire organism, rather than the activity of a specific enzyme, meaning that they can catalyze a broad range of chemical reactions. Microbial fuel cells can derive current from the oxidation of substrates such as glucose, and be leveraged for processes such as CO reduction. | 0 | Theoretical and Fundamental Chemistry |
A plug in sanitation is an object that is used to close a drainage outlet firmly.
The insertion of a plug into a drainage outlet allows the container to be filled with water or other fluids. In contrast to screw on caps, plugs are pushed into the hole and are not put over the hole.
Plugs are most commonly encountered in the bathroom or kitchen, for use in bathtubs, wash basins or sinks. | 1 | Applied and Interdisciplinary Chemistry |
Rgg-like transcriptional regulators can be found in a variety of gram-positive bacteria Where ropB regulates speB protease production in S. pyogenes, a roughly equivalent secretory control mechanism can be seen in Rggs regulation of gtfG glucosyltransferase production in S. gordonii, in the manner in which gadR regulates acid resistance in Lactococcus lactis, how lasX regulates expression of lantibiotic lactocin S in Lactobacillus sakei, and MutRs regulation of mutacin in S. mutans Sequentially, these genes are all localized contiguously to their respective subject of regulation and share promoters localized contiguously to inverted repeat regions. | 1 | Applied and Interdisciplinary Chemistry |
The NASBA technique has been used to develop rapid diagnostic tests for several pathogenic viruses with single-stranded RNA genomes, e.g. influenza A, zika virus, foot-and-mouth disease virus, severe acute respiratory syndrome (SARS)-associated coronavirus, human bocavirus (HBoV) and also parasites like Trypanosoma brucei.
Recently, NASBA reaction with fluoresce, dipstick and next generation sequencing readout has been developed for COVID-19 diagnosis. | 1 | Applied and Interdisciplinary Chemistry |
LEAPER (Leveraging endogenous ADAR for programmable editing of RNA) is a genetic engineering technique in molecular biology by which RNA can be edited. The technique relies on engineered strands of RNA to recruit native ADAR enzymes to swap out different compounds in RNA. Developed by researchers at Peking University in 2019, the technique, some have claimed, is more efficient than the CRISPR gene editing technique. Initial studies have claimed that editing efficiencies of up to 80%. | 1 | Applied and Interdisciplinary Chemistry |
In ancient Indian philosophy, preliminary instances of atomism are found in the works of Vedic sage Aruni, who lived in the 8th century BCE, especially his proposition that "particles too small to be seen mass together into the substances and objects of experience" known as kaṇa. Although kana refers to "particles" not atoms (paramanu). Some scholars such as Hermann Jacobi and Randall Collins have compared Aruni to Thales of Miletus in their scientific methodology, calling them both as "primitive physicists" or "proto-materialist thinkers". Later, the Charvaka, and Ajivika schools of atomism originated as early as the 7th century BCE. Bhattacharya posits that Charvaka may have been one of several atheistic, materialist schools that existed in ancient India. Kanada founded the Vaisheshika school of Indian philosophy that also represents the earliest Indian natural philosophy. The Nyaya and Vaisheshika schools developed theories on how kaṇas combined into more complex objects.
Several of these doctrines of atomism are, in some respects, "suggestively similar" to that of Democritus. McEvilley (2002) assumes that such similarities are due to extensive cultural contact and diffusion, probably in both directions.
The Nyaya–Vaisesika school developed one of the earliest forms of atomism; scholars date the Nyaya and Vaisesika texts from the 9th to 4th centuries BCE. Vaisesika atomists posited the four elemental atom types, but in Vaisesika physics atoms had 25 different possible qualities, divided between general extensive properties and specific (intensive) properties. The Nyaya–Vaisesika atomists had elaborate theories of how atoms combine. In Vaisesika atomism, atoms first combine into s (triads) and (dyad) before they aggregate into bodies of a kind that can be perceived. | 1 | Applied and Interdisciplinary Chemistry |
The quality of a given spectroradiometric system is a function of its electronics, optical components, software, power supply, and calibration. Under ideal laboratory conditions and with highly trained experts, it is possible to achieve small (a few tenths to a few percent) errors in measurements. However, in many practical situations, there is the likelihood of errors on the order of 10 percent Several types of error are at play when taking physical measurements. The three basic types of error noted as the limiting factors of accuracy of measurement are random, systematic, and periodic errors
* Random errors are variations about that mean. In the case of spectroradiometric measurements, this could be thought of as noise from the detector, internal electronics, or the light source itself. Errors of this type can be combated by longer integration times or multiple scans.
* Systematic errors are offsets to the predicted "correct" value. Systematic errors generally occur due to the human component of these measurements, the device itself, or the setup of the experiment. Things such as calibration errors, stray light, and incorrect settings, are all potential issues.
* Periodic errors arise from recurrent periodic or pseudo-periodic events. Variations in temperature, humidity, air-motion, or AC interference could all be categorized as periodic error.
In addition to these generic sources of error, a few of the more specific reasons for error in spectroradiometry include:
* The multidimensionality of the measurement. The output signal is dependent on several factors, including magnitude of measured flux, its direction, its polarization, and its wavelength distribution.
* The inaccuracy of measuring instruments, as well as the standards used to calibrate said instruments, cascaded to create a larger error throughout the entire measurement process, and
* The proprietary techniques for reducing multidimensionality and device instability error.
Gamma-scientific, a California-based manufacturer of light measurement devices, lists seven factors affecting the accuracy and performance of their spectroradiometers, due to either the system calibration, the software and power supply, the optics, or the measurement engine itself. | 0 | Theoretical and Fundamental Chemistry |
Important derivatives of tartaric acid include:
*Sodium ammonium tartrate, the first material separated into its enantiomers
*cream of tartar (potassium bitartrate), used in cooking
*Rochelle salt (potassium sodium tartrate), which has unusual optical properties
*tartar emetic (antimony potassium tartrate), a resolving agent. Diisopropyl tartrate is used as a co-catalyst in asymmetric synthesis.
Tartaric acid is a muscle toxin, which works by inhibiting the production of malic acid, and in high doses causes paralysis and death. The median lethal dose (LD) is about 7.5 grams/kg for a human, 5.3 grams/kg for rabbits, and 4.4 grams/kg for mice. Given this figure, it would take over to kill a person weighing with 50% probability, so it may be safely included in many foods, especially sour-tasting sweets. As a food additive, tartaric acid is used as an antioxidant with E number E334; tartrates are other additives serving as antioxidants or emulsifiers.
When cream of tartar is added to water, a suspension results which serves to clean copper coins very well, as the tartrate solution can dissolve the layer of copper(II) oxide present on the surface of the coin. The resulting copper(II)-tartrate complex is easily soluble in water. | 0 | Theoretical and Fundamental Chemistry |
The decay of RF-induced NMR spin polarization is characterized in terms of two separate processes, each with their own time constants. One process, called T, is responsible for the loss of resonance intensity following pulse excitation. The other process, called T, characterizes the width or broadness of resonances. Stated more formally, T is the time constant for the physical processes responsible for the relaxation of the components of the nuclear spin magnetization vector M parallel to the external magnetic field, B (which is conventionally designated as the z-axis). T relaxation affects the coherent components of M perpendicular to B. In conventional NMR spectroscopy, T limits the pulse repetition rate and affects the overall time an NMR spectrum can be acquired. Values of T range from milliseconds to several seconds, depending on the size of the molecule, the viscosity of the solution, the temperature of the sample, and the possible presence of paramagnetic species (e.g., O or metal ions). | 0 | Theoretical and Fundamental Chemistry |
The natural outdoor exposure in the United Kingdom ranges from 0.1 to 0.5 µSv/h with significant increase around known nuclear and contaminated sites. Natural exposure to gamma rays is about 1 to 2 mSv per year, and the average total amount of radiation received in one year per inhabitant in the USA is 3.6 mSv. There is a small increase in the dose, due to naturally occurring gamma radiation, around small particles of high atomic number materials in the human body caused by the photoelectric effect.
By comparison, the radiation dose from chest radiography (about 0.06 mSv) is a fraction of the annual naturally occurring background radiation dose. A chest CT delivers 5 to 8 mSv. A whole-body PET/CT scan can deliver 14 to 32 mSv depending on the protocol. The dose from fluoroscopy of the stomach is much higher, approximately 50 mSv (14 times the annual background).
An acute full-body equivalent single exposure dose of 1 Sv (1000 mSv), or 1 Gy, will cause mild symptoms of acute radiation sickness, such as nausea and vomiting; and a dose of 2.0–3.5 Sv (2.0–3.5 Gy) causes more severe symptoms (i.e. nausea, diarrhea, hair loss, hemorrhaging, and inability to fight infections), and will cause death in a sizable number of cases—about 10% to 35% without medical treatment. A dose of 5 Sv (5 Gy) is considered approximately the LD (lethal dose for 50% of exposed population) for an acute exposure to radiation even with standard medical treatment. A dose higher than 5 Sv (5 Gy) brings an increasing chance of death above 50%. Above 7.5–10 Sv (7.5–10 Gy) to the entire body, even extraordinary treatment, such as bone-marrow transplants, will not prevent the death of the individual exposed (see radiation poisoning). (Doses much larger than this may, however, be delivered to selected parts of the body in the course of radiation therapy.)
For low-dose exposure, for example among nuclear workers, who receive an average yearly radiation dose of 19 mSv, the risk of dying from cancer (excluding leukemia) increases by 2 percent. For a dose of 100 mSv, the risk increase is 10 percent. By comparison, risk of dying from cancer was increased by 32 percent for the survivors of the atomic bombing of Hiroshima and Nagasaki. | 0 | Theoretical and Fundamental Chemistry |
Hydrofluorocarbons are included in the Kyoto Protocol and are regulated under the Kigali Amendment to the Montreal Protocol due to their very high Global Warming Potential and the recognition of halocarbon contributions to climate change.
On September 21, 2007, approximately 200 countries agreed to accelerate the elimination of hydrochlorofluorocarbons entirely by 2020 in a United Nations-sponsored Montreal summit. Developing nations were given until 2030. Many nations, such as the United States and China, who had previously resisted such efforts, agreed with the accelerated phase out schedule. India successfully phased out HCFCs by 2020. | 1 | Applied and Interdisciplinary Chemistry |
Pollution led to more than 2.3 million premature deaths in India in 2019, according to a new Lancet study. Nearly 1.6 million deaths were due to air pollution alone, and more than 500,000 were caused by water pollution. India has developed instruments and regulatory powers to mitigate pollution sources but there is no centralized system to drive pollution control efforts and achieve substantial improvements," the study said adding that in 93% of the country, the amount of pollution remains well above the World Health Organization (WHO) guidelines. | 1 | Applied and Interdisciplinary Chemistry |
Sedimentation in potable water treatment generally follows a step of chemical coagulation and flocculation, which allows grouping particles together into flocs of a bigger size. This increases the settling speed of suspended solids and allows settling colloids. | 0 | Theoretical and Fundamental Chemistry |
European pipe is standardized to
ISO 2531 and its descendent specifications EN 545 (potable water) and EN 598 (sewage). European pipes are sized to approximately match the internal diameter of the pipe, following internal lining, to the nominal diameter. ISO 2531 maintains dimensional compatibility with older German cast iron pipes. Older British pipes, however, which used the incompatible imperial standard, BS 78, require adapter pieces when connecting to newly installed pipe. Coincidentally, the British harmonization with European pipe standards occurred at approximately the same time as its transition to ductile iron, so almost all cast iron pipe is imperial and all ductile pipe is metric.
Other European Standards give specifications on more dedicated products:
EN 15655:2009 – Ductile iron pipes, fittings and accessories – Internal polyurethane lining for pipes and fittings – Requirements and test methods
EN 877:1999/A1:2006 – Cast iron pipes and fittings, their joints and accessories for the evacuation of water from buildings – Requirements, test methods and quality assurance
CEN/TR 15545:2006 – Guide to the use of EN 545
CEN/TR 16017:2010 – Guide to the use of EN 598
EN 877:1999 – Cast iron pipes and fittings, their joints and accessories for the evacuation of water from buildings – Requirements, test methods and quality assurance
EN 877:1999/A1:2006/AC:2008 – Cast iron pipes and fittings, their joints and accessories for the evacuation of water from buildings – Requirements, test methods and quality assurance
EN 598:2007+A1:2009 – Ductile iron pipes, fittings, accessories and their joints for sewerage applications – Requirements and test methods
EN 12842:2012 – Ductile iron fittings for PVC-U or PE piping systems – Requirements and test methods
CEN/TR 16470:2013 – Environmental aspects of ductile iron pipe systems for water and sewerage applications
EN 14628:2005 – Ductile iron pipes, fittings and accessories – External polyethylene coating for pipes – Requirements and test methods
EN 15189:2006 – Ductile iron pipes, fittings and accessories – External polyurethane coating for pipes – Requirements and test methods
EN 14901:2014 – Ductile iron pipes, fittings and accessories – Epoxy coating (heavy duty) of ductile iron fittings and accessories – Requirements and test methods
EN 969:2009 – Ductile iron pipes, fittings, accessories and their joints for gas pipelines – Requirements and test methods
EN 15542:2008 – Ductile iron pipes, fittings and accessories – External cement mortar coating for pipes – Requirements and test methods
EN 545:2010 – Ductile iron pipes, fittings, accessories and their joints for water pipelines – Requirements and test methods
EN 14525:2004 – Ductile iron wide tolerance couplings and flange adaptors for use with pipes of different materials: ductile iron, Grey iron, Steel, PVC-U PE, Fibre-cement | 1 | Applied and Interdisciplinary Chemistry |
The Tufts Center for the Study of Drug Development is an independent, academic, non-profit research center at Tufts University in Boston, dedicated to researching drug development. It was established in 1976 by American physician Louis Lasagna. The Center develops and publishes information to help researchers, regulators, and policy makers in areas related to the pharmaceutical and biotechnology industries. In any given year, approximately 55% of Tufts CSDD's operating expenses are supported by grants from the private sector and 45% from the public sector. | 1 | Applied and Interdisciplinary Chemistry |
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