text
stringlengths 105
4.44k
| label
int64 0
9
| label_text
stringclasses 10
values |
|---|---|---|
Although research is ongoing, treatment options are currently limited; vitamins are frequently prescribed, though the evidence for their effectiveness is limited.
Pyruvate has been proposed in 2007 as a treatment option. N-acetyl cysteine reverses many models of mitochondrial dysfunction. In the case of mood disorders, specifically bipolar disorder, it is hypothesized that N-acetyl-cysteine (NAC), acetyl-L-carnitine (ALCAR), S-adenosylmethionine (SAMe), coenzyme Q10 (CoQ10), alpha-lipoic acid (ALA), creatine monohydrate (CM), and melatonin could be potential treatment options. | 1 | Biochemistry |
Owing to the presence of covalently bonded fluorine, halothane absorbs in the atmospheric window and is therefore a greenhouse gas. However, it is much less potent than most other chlorofluorocarbons and bromofluorocarbons due to its short atmospheric lifetime, estimated at only one year vis-à-vis over 100 years for many perfluorocarbons. Despite its short lifespan, halothane still has a global warming potential 47 times that of carbon dioxide, although this is over 100 times smaller than the most abundant fluorinated gases, and about 800 times smaller than the GWP of sulfur hexafluoride over 500 years. Halothane is believed to make a negligible contribution to global warming. | 4 | Stereochemistry |
The amount of water vapor in an atmosphere is constrained by the restrictions of partial pressures and temperature. Dew point temperature and relative humidity act as guidelines for the process of water vapor in the water cycle. Energy input, such as sunlight, can trigger more evaporation on an ocean surface or more sublimation on a chunk of ice on top of a mountain. The balance between condensation and evaporation gives the quantity called vapor partial pressure.
The maximum partial pressure (saturation pressure) of water vapor in air varies with temperature of the air and water vapor mixture. A variety of empirical formulas exist for this quantity; the most used reference formula is the Goff-Gratch equation for the SVP over liquid water below zero degrees Celsius:
where , temperature of the moist air, is given in units of kelvin, and is given in units of millibars (hectopascals).
The formula is valid from about −50 to 102 °C; however there are a very limited number of measurements of the vapor pressure of water over supercooled liquid water. There are a number of other formulae which can be used.
Under certain conditions, such as when the boiling temperature of water is reached, a net evaporation will always occur during standard atmospheric conditions regardless of the percent of relative humidity. This immediate process will dispel massive amounts of water vapor into a cooler atmosphere.
Exhaled air is almost fully at equilibrium with water vapor at the body temperature. In the cold air the exhaled vapor quickly condenses, thus showing up as a fog or mist of water droplets and as condensation or frost on surfaces. Forcibly condensing these water droplets from exhaled breath is the basis of exhaled breath condensate, an evolving medical diagnostic test.
Controlling water vapor in air is a key concern in the heating, ventilating, and air-conditioning (HVAC) industry. Thermal comfort depends on the moist air conditions. Non-human comfort situations are called refrigeration, and also are affected by water vapor. For example, many food stores, like supermarkets, utilize open chiller cabinets, or food cases, which can significantly lower the water vapor pressure (lowering humidity). This practice delivers several benefits as well as problems. | 2 | Environmental Chemistry |
Carbon tetrachloride was widely used as a dry cleaning solvent, as a refrigerant, and in lava lamps. In the last case, carbon tetrachloride is a key ingredient that adds weight to the otherwise buoyant wax.
One speciality use of carbon tetrachloride was in stamp collecting, to reveal watermarks on postage stamps without damaging them. A small amount of the liquid is placed on the back of a stamp, sitting in a black glass or obsidian tray. The letters or design of the watermark can then be seen clearly. Today, this is done on lit tables without using carbon tetrachloride. | 2 | Environmental Chemistry |
The technique for RFLP analysis is, however, slow and cumbersome. It requires a large amount of sample DNA, and the combined process of probe labeling, DNA fragmentation, electrophoresis, blotting, hybridization, washing, and autoradiography can take up to a month to complete. A limited version of the RFLP method that used oligonucleotide probes was reported in 1985. The results of the Human Genome Project have largely replaced the need for RFLP mapping, and the identification of many single-nucleotide polymorphisms (SNPs) in that project (as well as the direct identification of many disease genes and mutations) has replaced the need for RFLP disease linkage analysis (see SNP genotyping). The analysis of VNTR alleles continues, but is now usually performed by polymerase chain reaction (PCR) methods. For example, the standard protocols for DNA fingerprinting involve PCR analysis of panels of more than a dozen VNTRs.
RFLP is still used in marker-assisted selection. Terminal restriction fragment length polymorphism (TRFLP or sometimes T-RFLP) is a technique initially developed for characterizing bacterial communities in mixed-species samples. The technique has also been applied to other groups including soil fungi. TRFLP works by PCR amplification of DNA using primer pairs that have been labeled with fluorescent tags. The PCR products are then digested using RFLP enzymes and the resulting patterns visualized using a DNA sequencer. The results are analyzed either by simply counting and comparing bands or peaks in the TRFLP profile, or by matching bands from one or more TRFLP runs to a database of known species. A number of different software tools have been developed to automate the process of band matching, comparison and data basing of TRFLP profiles.
The technique is similar in some aspects to temperature gradient or denaturing gradient gel electrophoresis (TGGE and DGGE).
The sequence changes directly involved with an RFLP can also be analyzed more quickly by PCR. Amplification can be directed across the altered restriction site, and the products digested with the restriction enzyme. This method has been called Cleaved Amplified Polymorphic Sequence (CAPS). Alternatively, the amplified segment can be analyzed by allele-specific oligonucleotide (ASO) probes, a process that can often be done by a simple dot blot. | 1 | Biochemistry |
Since the Civil War, North Alabama became one of the countrys leading iron and steel manufacturers. The Birmingham District was particularly well positioned to be an iron-and-steel production centre in the southern United States. The development of Alabamas iron and steel industry was primarily stimulated by the abundance of raw materials; coal, iron ore, limestone, and dolomite. The most powerful and profitable companies in North Alabama were those which had direct control over mines, as well as other facilities necessary for extracting and assembling raw materials, such as blast furnaces. Being dependent on raw materials and relevant infrastructural facilities, iron and steel makers expanded the furnaces in Alabama. Those manufacturers also attempted to incorporate new charging machines to increase the overall production of iron. Since iron and steel production was a resource-intensive industry this required powerful iron and steel manufacturing enterprises to hold a control over the regional railroads in Alabama. A typical example was the Woodward Iron Company whose holdings were mostly linked by a company-owned railroad. This railroad originally measured 12 miles in length but the company extended it outward from its blast furnaces, to its quarries of limestone and dolomite, and further to its coal mines and ore mines. | 8 | Metallurgy |
Many free radical-based syntheses show large kinetic solvent effects that can reduce the rate of reaction and cause a planned reaction to follow an unwanted pathway. | 7 | Physical Chemistry |
Queen's Metal, an alloy of nine parts tin and one each of antimony, lead, and bismuth, is intermediate in hardness between pewter and britannia metal. It was developed by English pewtersmiths in the 16th century; the recipe was initially a secret and was reserved for pieces made for the English royal family. | 8 | Metallurgy |
Deaths have resulted from accidental exposure to fumigation materials containing aluminium phosphide or phosphine. It can be absorbed either by inhalation or transdermally. As a respiratory poison, it affects the transport of oxygen or interferes with the utilization of oxygen by various cells in the body. Exposure results in pulmonary edema (the lungs fill with fluid). Phosphine gas is heavier than air so it stays near the floor.
Phosphine appears to be mainly a redox toxin, causing cell damage by inducing oxidative stress and mitochondrial dysfunction. Resistance in insects is caused by a mutation in a mitochondrial metabolic gene.
Phosphine can be absorbed into the body by inhalation. The main target organ of phosphine gas is the respiratory tract. According to the 2009 U.S. National Institute for Occupational Safety and Health (NIOSH) pocket guide, and U.S. Occupational Safety and Health Administration (OSHA) regulation, the 8 hour average respiratory exposure should not exceed 0.3 ppm. NIOSH recommends that the short term respiratory exposure to phosphine gas should not exceed 1 ppm. The Immediately Dangerous to Life or Health level is 50 ppm. Overexposure to phosphine gas causes nausea, vomiting, abdominal pain, diarrhea, thirst, chest tightness, dyspnea (breathing difficulty), muscle pain, chills, stupor or syncope, and pulmonary edema. Phosphine has been reported to have the odor of decaying fish or garlic at concentrations below 0.3 ppm. The smell is normally restricted to laboratory areas or phosphine processing since the smell comes from the way the phosphine is extracted from the environment. However, it may occur elsewhere, such as in industrial waste landfills. Exposure to higher concentrations may cause olfactory fatigue. | 0 | Organic Chemistry |
Campylobacter is the common causative agent for bacterial infectious intestinal diseases, usually arising from undercooked poultry or unpasteurised milk. However, its epidemiology is poorly understood since outbreaks are rarely detected, so that the sources and transmission routes of outbreak are not easily traced. In addition, Campylobacter genomes are genetically diverse and unstable with frequent inter- and intragenomic recombination, together with phase variation, which complicates the interpretation of data from many typing methods. Until recently, with the application of MLST technique, Campylobacter typing has achieved a great success and added onto the MLST database. As at 1 May 2008, the Campylobacter MLST database contains 3516 isolates and about 30 publications that use or mention MLST in research on Campylobacter (http://pubmlst.org/campylobacter/). | 1 | Biochemistry |
There are many ways to install screen media into a screen box deck (shaker deck). Also, the type of attachment system has an influence on the dimensions of the media. | 8 | Metallurgy |
Long noncoding RNAs (lncRNAs) are large transcripts (more than 200 nucleotides long) that have similar mechanism of synthesis as that of mRNAs but unlike mRNAs, lncRNAs are not translated to a protein. lncRNA contains interactor elements and structural elements. Interactor elements directly interact with other nucleic acids or proteins while the structural elements indicate the ability of some lncRNAs to form secondary and/or tertiary structures. This ability of the lncRNAs to interact with nucleic acids using its interactor elements and its ability to interact with protein using its secondary structures allows it to function in a more diverse manner than other ncRNAs such as miRNA (microRNA). LncRNA has been established to play a role in gene regulation by influencing the ability of specific regions of the gene to bind to transcriptional elements and different epigenetic modifications. One such example can be seen in the case X inactive specific transcript (XIST). In humans, 46,XX females carry an extra X chromosome (155Mb of DNA) compared to 46,XY males. To overcome this dosage imbalance, one X chromosome is randomly inactivated in human females at around the 2-8 cell stage of embryo development. This inactivation is very stable across cell divisions due to epigenetic contributions both during the initial silencing and the subsequent maintenance of the inactive X chromosome (Xi). This inactivation is carried by the lncRNA, XIST. XIST is produced in cis and inactivates the X-chromosome that it has been generated from. The inactive X chromosome can be observed as a condensed heterochromatin structure called “Barr Body”.
A study in 2013 utilized this ability of XIST as a potential therapeutic approach for treatment of trisomy 21. Trisomy 21 is commonly known as down syndrome and is caused due to presence of an additional copy of chromosome 21. The study was one of its kind as no other studies have been able to incorporate the XIST gene into a chromosome due to its large size. The study incorporated the XIST into one of the chromosomes 21 in the cells gathered from patients with down syndrome. The study was able to observe the inactivation of one of chromosome 21 in the form of a condensed heterochromatin and labeled it as a chromosome 21 barr body. Such experiments have shown to work in cells in the lab setting although no lncRNA based therapeutics are in clinical trials. The implications of such work can bring trisomy 21 and other chromosomal disorders in the realm of consideration for future gene therapy research. | 1 | Biochemistry |
The Lydersen method is a group contribution method for the estimation of critical properties temperature (T), pressure (P) and volume (V). The Lydersen method is the prototype for and ancestor of many new models like Joback, Klincewicz,
Ambrose,
Gani-Constantinou and others.
The Lydersen method is based in case of the critical temperature on the Guldberg rule which establishes a relation between the normal boiling point and the critical temperature. | 7 | Physical Chemistry |
In humans, dietary starches are composed of glucose units arranged in long chains called amylose, a polysaccharide. During digestion, bonds between glucose molecules are broken by salivary and pancreatic amylase, resulting in progressively smaller chains of glucose. This results in simple sugars glucose and maltose (2 glucose molecules) that can be absorbed by the small intestine.
Lactase is an enzyme that breaks down the disaccharide lactose to its component parts, glucose and galactose. Glucose and galactose can be absorbed by the small intestine. Approximately 65 percent of the adult population produce only small amounts of lactase and are unable to eat unfermented milk-based foods. This is commonly known as lactose intolerance. Lactose intolerance varies widely by genetic heritage; more than 90 percent of peoples of east Asian descent are lactose intolerant, in contrast to about 5 percent of people of northern European descent.
Sucrase is an enzyme that breaks down the disaccharide sucrose, commonly known as table sugar, cane sugar, or beet sugar. Sucrose digestion yields the sugars fructose and glucose which are readily absorbed by the small intestine. | 1 | Biochemistry |
Kinetic relations have been observed in many systems and, since their conception, have gone by many terms, among which are the Meyer-Neldel effect or rule, the Barclay-Butler rule, the theta rule, and the Smith-Topley effect. Generally, chemists will talk about the isokinetic relation (IKR), from the importance of the isokinetic (or isoequilibrium) temperature, condensed matter physicists and material scientists use the Meyer-Neldel rule, and biologists will use the compensation effect or rule.
An interesting homework problem appears following Chapter 7: Structure-Reactivity Relationships in Kenneth Connorss textbook Chemical Kinetics: The Study of Reaction Rates':
:From the last four digits of the office telephone numbers of the faculty in your department, systematically construct pairs of "rate constants" as two-digit numbers times 10 s at temperatures 300 K and 315 K (obviously the larger rate constant of each pair to be associated with the higher temperature). Make a two-point Arrhenius plot for each faculty member, evaluating and . Examine the plot of against for evidence of an isokinetic relationship.
The existence of any real compensation effect has been widely derided in recent years and attributed to the analysis of interdependent factors and chance. Because the physical roots remain to be fully understood, it has been called into question whether compensation is a truly physical phenomenon or a coincidence due to trivial mathematical connections between parameters. The compensation effect has been criticized in other respects, namely for being the result of random experimental and systematic errors producing the appearance of compensation. The principal complaint lodged states that compensation is an artifact of data from a limited temperature range or from a limited range for the free energies.
In response to the criticisms, investigators have stressed that compensatory phenomena are real, but appropriate and in-depth data analysis is always needed. The F-test has been used to such an aim, and it minimizes the deviations of points constrained to pass through an isokinetic temperature to the deviation of the points from the unconstrained line is achieved by comparing the mean deviations of points. Appropriate statistical tests should be performed as well. W. Linert wrote in a 1983 paper:
:There are few topics in chemistry in which so many misunderstandings and controversies have arisen as in connection with the so-called isokinetic relationship (IKR) or compensation law. Up to date, a great many chemists appear to be inclined to dismiss the IKR as being accidental. The crucial problem is that the activation parameters are mutually dependent because of their determination from the experimental data. Therefore, it has been stressed repeatedly, the isokinetic plot (i.e., against ) is unfit in principle to substantiate a claim of an isokinetic relationship. At the same time, however, it is a fatal error to dismiss the IKR because of that fallacy.
Common among all defenders is the agreement that stringent criteria for the assignment of true compensation effects must be adhered to. | 7 | Physical Chemistry |
Surface roughness has a strong effect on the contact angle and wettability of a surface. The effect of roughness depends on if the droplet will wet the surface grooves or if air pockets will be left between the droplet and the surface.
If the surface is wetted homogeneously, the droplet is in Wenzel state. In Wenzel state, adding surface roughness will enhance the wettability caused by the chemistry of the surface. The Wenzel correlation can be written as
where is the measured contact angle, is the Young contact angle and is the roughness ratio. The roughness ratio is defined as the ratio between the actual and projected solid surface area.
If the surface is wetted heterogeneously, the droplet is in Cassie-Baxter state. The most stable contact angle can be connected to the Young contact angle. The contact angles calculated from the Wenzel and Cassie-Baxter equations have been found to be good approximations of the most stable contact angles with real surfaces. | 7 | Physical Chemistry |
In organic chemistry, the Graham reaction is an oxidation reaction that converts an amidine into a diazirine using a hypohalite reagent. The halide of the hypohalite oxidant, or another similar anionic additive to the reaction, is retained as a substituent on the diazirine product. The reaction was first reported in 1965. Various reaction mechanisms have been proposed.
Amidine substrates for the reaction can easily be formed from the corresponding nitriles via the Pinner reaction. The halide substituent in the diazirine product can be displaced by a various nucleophiles. | 0 | Organic Chemistry |
Mutations in fumarate hydratase are found among patients suffering from kidney cancers, and mutations in succinate dehydrogenase were found in patients with pheochromocytoma and paragangliomas. These mutations cause a disruption of the TCA cycle with the accumulation of fumarate or succinate, both of which can inhibit dioxygenases or prolyl hydrolases that mediate the degradation of HIF proteins. HIF-1 could be elevated under aerobic conditions downstream from activated PI3K, which stimulates the synthesis of HIF-1. Loss of the tumor suppressor VHL in kidney cancer also stabilizes HIF-1, permitting it to activate glycolytic genes, which are normally activated by HIF-1 under hypoxic conditions. HIF1 then would activate the pyruvate dehydrogenase kinase (PDKs), which inactivate the mitochondrial pyruvate dehydrogenase complex. It reduces the flow of glucose-derived pyruvate into the tricarboxylic acid (citric acid cycle or TCA cycle). This reduction in pyruvate flux into the TCA cycle decreases the rate of oxidative phosphorylation and oxygen consumption, reinforcing the glycolytic phenotype and sparing oxygen under hypoxic conditions. | 1 | Biochemistry |
The hydroxy group is pervasive in chemistry and biochemistry. Many inorganic compounds contain hydroxyl groups, including sulfuric acid, the chemical compound produced on the largest scale industrially.
Hydroxy groups participate in the dehydration reactions that link simple biological molecules into long chains. The joining of a fatty acid to glycerol to form a triacylglycerol removes the −OH from the carboxy end of the fatty acid. The joining of two aldehyde sugars to form a disaccharide removes the −OH from the carboxy group at the aldehyde end of one sugar. The creation of a peptide bond to link two amino acids to make a protein removes the −OH from the carboxy group of one amino acid. | 0 | Organic Chemistry |
The air transports viruses and other pathogens. Since viruses are smaller than other bioaerosols, they have the potential to travel further distances. In one simulation, a virus and a fungal spore were simultaneously released from the top of a building; the spore traveled only 150 meters while the virus traveled almost 200,000 horizontal kilometers.
In one study, aerosols (<5 μm) containing SARS-CoV-1 and SARS-CoV-2 were generated by an atomizer and fed into a Goldberg drum to create an aerosolized environment. The inoculum yielded cycle thresholds between 20 and 22, similar to those observed in human upper and lower respiratory tract samples. SARS-CoV-2 remained viable in aerosols for 3 hours, with a decrease in infection titre similar to SARS-CoV-1. The half-life of both viruses in aerosols was 1.1 to 1.2 hours on average. The results suggest that the transmission of both viruses by aerosols is plausible, as they can remain viable and infectious in suspended aerosols for hours and on surfaces for up to days. | 7 | Physical Chemistry |
The snRNPs are very long-lived, but are assumed to be eventually disassembled and degraded. Little is known about the degradation process. | 1 | Biochemistry |
When photosystem I absorbs light, an electron is excited to a higher energy level in the P700 chlorophyll. The resulting P700 with an excited electron is designated as P700*, which is a strong reducing agent due to its very negative redox potential of -1.2V . | 5 | Photochemistry |
The U.S. Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. See table. The
European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg.
Because of concerns of long-term adverse side effects such as calcification of arteries and kidney stones, the IOM and EFSA both set Tolerable Upper Intake Levels (ULs) for the combination of dietary and supplemental calcium. From the IOM, people ages 9–18 years are not supposed to exceed 3,000 mg/day; for ages 19–50 not to exceed 2,500 mg/day; for ages 51 and older, not to exceed 2,000 mg/day. The EFSA set UL at 2,500 mg/day for adults but decided the information for children and adolescents was not sufficient to determine ULs. | 1 | Biochemistry |
Ratsimamanga was a pacifist and politically active, and during his years of study, he forged close relationships with French intellectual and political circles. While in France, he co-founded the association of Malagasy Students in France and the Democratic Movement for Malagasy Renovation (MDRM) in 1946 with Jacques Rabemananjara, Joseph Raseta and Joseph Ravoahangy Andrianavalona. MDRM led the protests against the bloody repression of the Malagasy Uprising of 1947. However, MDRM was known to be dominated by Hova elites, who had been politically prominent in the former Merina royal court and wanted to regain the political dominance of the Merina upon independence. Jacques Rabemananjara, Joseph Raseta and Joseph Ravoahangy Andrianavalona were later sentenced to life in prison but were granted amnesty in 1958. Ratsimamanga claimed that he was unaware of the uprising and, thus, was not involved. Later in 1949, Ratsimamanga created the Malagasy National Council, a Government in exile. It was a failure.
On 26 August 1948, Ratsimamanga represented Madagascar at the World Congress of Intellectuals in Defence of Peace, which took place between the 25 to 28 August 1948 of August at Wrocław University of Science and Technology, Poland, and played a role in the framing of the communist powers as supporters of peace, and on the opposite side, portraying the West as a threat to peace.
Ratsimamanga was a member of the delegation that negotiated Madagascars independence from France. 77% of Malagasy voted for independence in the 1958 referendum, and after the independence, Ratsimamanga was appointed the Malagasy Republic ambassador to France from 1960 to 1972. After the 1972 Coup détat, on 14 December 1972, he was appointed the first Ambassador of the Malagasy Republic to China and the Soviet Union. He later established embassies in West Germany, North Korea, and Sierra Leone.
Furthermore, Ratsimamanga represents the Malagasy Republic at the European Economic Community, UNESCO, and Food and Agriculture Organization. He also became UNESCO Vice-chairman of the Executive Council. | 1 | Biochemistry |
Formol titration is one of the methods used in winemaking to measure yeast assimilable nitrogen needed by wine yeast in order to successfully complete fermentation. | 1 | Biochemistry |
Organometallic Fe–S clusters include the sulfido carbonyls with the formula FeS(CO), HFeS(CO), and FeS(CO). Compounds are also known that incorporate cyclopentadienyl ligands, such as (CH)FeS. | 7 | Physical Chemistry |
For ammonia, NH, the symmetric bending vibration is observed as two branches near 930 cm and 965 cm. This so-called inversion doubling arises because the symmetric bending vibration is actually a large-amplitude motion known as inversion, in which the nitrogen atom passes through the plane of the three hydrogen atoms, similar to the inversion of an umbrella. The potential energy curve for such a vibration has a double minimum for the two pyramidal geometries, so that the vibrational energy levels occur in pairs which correspond to combinations of the vibrational states in the two potential minima. The two v = 1 states combine to form a symmetric state (1) at 932.5 cm above the ground (0) state and an antisymmetric state (1) at 968.3 cm.
The vibrational ground state (v = 0) is also doubled although the energy difference is much smaller, and the transition between the two levels can be measured directly in the microwave region, at ca. 24 Ghz (0.8 cm). This transition is historically significant and was used in the ammonia maser, the fore-runner of the laser. | 7 | Physical Chemistry |
In lone-pair-active multiferroics, the ferroelectric displacement is driven by the A-site cation, and the magnetism arises from a partially filled d shell on the B site. Examples include bismuth ferrite, BiFeO, BiMnO (although this is believed to be anti-polar), and PbVO. In these materials, the A-site cation (Bi, Pb) has a so-called stereochemically active 6s lone-pair of electrons, and off-centering of the A-site cation is favoured by an energy-lowering electron sharing between the formally empty A-site 6p orbitals and the filled O 2p orbitals. | 7 | Physical Chemistry |
Hydroxamic acids are usually prepared from either esters or acid chlorides by a reaction with hydroxylamine salts. For the synthesis of benzohydroxamic acid ( or , where Ph is phenyl group), the overall equation is:
Hydroxamic acids can also be synthesized from aldehydes and N-sulfonylhydroxylamine via the Angeli-Rimini reaction. Alternatively, molybdenum oxide diperoxide oxidizes trimethylsilated amides to hydroxamic acids, although yields are only about 50%. In a variation on the Nef reaction, primary nitro compounds kept in an acidic solution (to minimize the nitronate tautomer) hydrolyze to a hydroxamic acid.
A well-known reaction of hydroxamic acid esters is the Lossen rearrangement. | 0 | Organic Chemistry |
Yttrium is found in most rare-earth minerals, it is found in some uranium ores, but is never found in the Earths crust as a free element. About 31 ppm of the Earths crust is yttrium, making it the 43rd most abundant element. Yttrium is found in soil in concentrations between 10 and 150 ppm (dry weight average of 23 ppm) and in sea water at 9 ppt. Lunar rock samples collected during the American Apollo Project have a relatively high content of yttrium.
Yttrium has no known biological role, though it is found in most, if not all, organisms and tends to concentrate in the liver, kidney, spleen, lungs, and bones of humans. Normally, as little as is found in the entire human body; human breast milk contains 4 ppm. Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with cabbage having the largest amount. With as much as 700 ppm, the seeds of woody plants have the highest known concentrations.
there are reports of the discovery of very large reserves of rare-earth elements in the deep seabed several hundred kilometers from the tiny Japanese island of Minami-Torishima Island, also known as Marcus Island. This location is described as having "tremendous potential" for rare-earth elements and yttrium (REY), according to a study published in Scientific Reports. "This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features," the study reads. The study shows that more than of rare-earth elements could be "exploited in the near future." As well as yttrium (Y), which is used in products like camera lenses and mobile phone screens, the rare-earth elements found are europium (Eu), terbium (Tb), and dysprosium (Dy). | 8 | Metallurgy |
Anti-DFS70 antibodies generate a dense fine speckled pattern in indirect immunofluorescence and are found in normals and in various conditions, but are not associated with a systemic autoimmune pathology. Therefore, they can be used to help to rule out such conditions in ANA positive individuals. A significant number of patients are diagnosed as systemic lupus erythematosus or undifferentiated connective tissue disease largely based on a positive ANA. In case no defined autoantibody can be detected (e.g. anti-ENA antibodies), the testing of anti-DFS70 antibodies is recommended to verify the diagnosis. Anti-DFS70 antibody tests are available as CE-marked tests. Until now, no FDA cleared assay is available. | 1 | Biochemistry |
Self-assembly can also be observed in the presence of organic ligands and various metals centers through coordinative bonds or supramolecular interactions. Molecular self- assembly involves the association by many weak, reversible interactions to obtain a final structure that represents a thermodynamic minimum. A class of coordination polymers, known also as metal-organic frameworks (MOFs), are metal-ligand compounds that extend "infinitely" into one, two or three dimensions. | 7 | Physical Chemistry |
The separation of compounds is due to the differences in their attraction to the stationary phase and because of differences in solubility in the solvent. As a result, the compounds and the mobile phase compete for binding sites on the stationary phase. Different compounds in the sample mixture travel at different rates due to the differences in their partition coefficients. Different solvents, or different solvent mixtures, gives different separation. The retardation factor (R), or retention factor, quantifies the results. It is the distance traveled by a given substance divided by the distance traveled by the mobile phase.
In normal-phase TLC, the stationary phase is polar. Silica gel is very common in normal-phase TLC. More polar compounds in a sample mixture interact more strongly with the polar stationary phase. As a result, more-polar compounds move less (resulting in smaller R) while less-polar compounds move higher up the plate (higher R). A more-polar mobile phase also binds more strongly to the plate, competing more with the compound for binding sites; a more-polar mobile phase also dissolves polar compounds more. As such, all compounds on the TLC plate move higher up the plate in polar solvent mixtures. "Strong" solvents move compounds higher up the plate, whereas "weak" solvents move them less.
If the stationary phase is non-polar, like C18-functionalized silica plates, it is called reverse-phase TLC. In this case, non-polar compounds move less and polar compounds move more. The solvent mixture will also be much more polar than in normal-phase TLC. | 3 | Analytical Chemistry |
A typical example of a conserved moiety in biochemistry is the Adenosine diphosphate (ADP) subgroup that remains unchanged when it is phosphorylated to create adenosine triphosphate (ATP) and then dephosphorylated back to ADP forming a conserved cycle. Moiety-conserved cycles in nature exhibit unique network control features which can be elucidated using techniques such as metabolic control analysis. Other examples in metabolism include NAD/NADH, NADP/NADPH, CoA/Acetyl-CoA. Conserved cycles also exist in large numbers in protein signaling networks when proteins get phosphorylated and phosphorylated.
Most, if not all, of these cycles, are time-scale-dependent. For example, although a protein in a phosphorylation cycle is conserved during the interconversion, over a longer time scale, there will be low levels of protein synthesis and degradation, which change the level of protein moiety. The same applies to cycles involving ATP, NAD, etc. Thus, although the concept of a moiety-conserved cycle in biochemistry is a useful approximation, over time scales that include significant net synthesis and degradation of the moiety, the approximation is no longer valid. When invoking the conserved-moiety assumption on a particular moiety, we are, in effect, assuming the system is closed to that moiety. | 1 | Biochemistry |
De novo repeat identification is an initial scan of sequence data that seeks to find the repetitive regions of the genome, and to classify these repeats. Many computer programs exist to perform de novo repeat identification, all operating under the same general principles. As short tandem repeats are generally 1–6 base pairs in length and are often consecutive, their identification is relatively simple. Dispersed repetitive elements, on the other hand, are more challenging to identify, due to the fact that they are longer and have often acquired mutations. However, it is important to identify these repeats as they are often found to be transposable elements (TEs).
De novo identification of transposons involves three steps: 1) find all repeats within the genome, 2) build a consensus of each family of sequences, and 3) classify these repeats. There are three groups of algorithms for the first step. One group is referred to as the k-mer approach, where a k-mer is a sequence of length k. In this approach, the genome is scanned for overrepresented k-mers; that is, k-mers that occur more often than is likely based on probability alone. The length k is determined by the type of transposon being searched for. The k-mer approach also allows mismatches, the number of which is determined by the analyst. Some k-mer approach programs use the k-mer as a base, and extend both ends of each repeated k-mer until there is no more similarity between them, indicating the ends of the repeats. Another group of algorithms employs a method called sequence self-comparison. Sequence self-comparison programs use databases such as AB-BLAST to conduct an initial sequence alignment. As these programs find groups of elements that partially overlap, they are useful for finding highly diverged transposons, or transposons with only a small region copied into other parts of the genome. Another group of algorithms follows the periodicity approach. These algorithms perform a Fourier transformation on the sequence data, identifying periodicities, regions that are repeated periodically, and are able to use peaks in the resultant spectrum to find candidate repetitive elements. This method works best for tandem repeats, but can be used for dispersed repeats as well. However, it is a slow process, making it an unlikely choice for genome-scale analysis.
The second step of de novo repeat identification involves building a consensus of each family of sequences. A consensus sequence is a sequence that is created based on the repeats that comprise a TE family. A base pair in a consensus is the one that occurred most often in the sequences being compared to make the consensus. For example, in a family of 50 repeats where 42 have a T base pair in the same position, the consensus sequence would have a T at this position as well, as the base pair is representative of the family as a whole at that particular position, and is most likely the base pair found in the family's ancestor at that position. Once a consensus sequence has been made for each family, it is then possible to move on to further analysis, such as TE classification and genome masking in order to quantify the overall TE content of the genome. | 1 | Biochemistry |
Terminal alkynes add across α,β-unsaturated ketones in the presence of palladium catalysts. The reaction affords γ,δ-ynones. Terminal alkynes add across epoxides to given yneols, which can be oxidized to give β,γ-ynones. | 0 | Organic Chemistry |
Ethanol fermentation produces unharvested byproducts such as heat, carbon dioxide, food for livestock, water, methanol, fuels, fertilizer and alcohols. The cereal unfermented solid residues from the fermentation process, which can be used as livestock feed or in the production of biogas, are referred to as Distillers grains and sold as WDG, Wet Distillers grains, and DDGS, Dried Distillers Grains with Solubles, respectively. | 1 | Biochemistry |
Serial Analysis of Gene Expression (SAGE) is a transcriptomic technique used by molecular biologists to produce a snapshot of the messenger RNA population in a sample of interest in the form of small tags that correspond to fragments of those transcripts. Several variants have been developed since, most notably a more robust version, LongSAGE, RL-SAGE and the most recent SuperSAGE. Many of these have improved the technique with the capture of longer tags, enabling more confident identification of a source gene. | 1 | Biochemistry |
In the gram-negative bacterium Escherichia coli (E. coli), cell division may be partially regulated by AI-2-mediated quorum sensing. This species uses AI-2, which is produced and processed by the lsr operon. Part of it encodes an ABC transporter, which imports AI-2 into the cells during the early stationary (latent) phase of growth. AI-2 is then phosphorylated by the LsrK kinase, and the newly produced phospho-AI-2 can be either internalized or used to suppress LsrR, a repressor of the lsr operon (thereby activating the operon). Transcription of the lsr operon is also thought to be inhibited by dihydroxyacetone phosphate (DHAP) through its competitive binding to LsrR. Glyceraldehyde 3-phosphate has also been shown to inhibit the lsr operon through cAMP-CAPK-mediated inhibition. This explains why, when grown with glucose, E. coli will lose the ability to internalize AI-2 (because of catabolite repression). When grown normally, AI-2 presence is transient.
E. coli and Salmonella enterica do not produce AHL signals commonly found in other gram-negative bacteria. However, they have a receptor that detects AHLs from other bacteria and change their gene expression in accordance with the presence of other "quorate" populations of gram-negative bacteria. AHL quorum sensing regulates a wide range of genes through cell density. Other species of bacteria produce AHLs that Eschericia and Salmonella can detect. E.coli and Salmonella produce a receptor like protein (SdiA) allowing the amino acid sequence that is similar to AHL show AHLs can be found in the bovine rumen and E. Coli responds to AHLs taken out of the bovine rumen. Most animals do not have AHL in their gastrointestinal tracts. | 1 | Biochemistry |
Jones was honoured with a stone grotesque in the Great Court of the University of Queensland placed on the Forgan Smith building. An annual lecture is presented in his name at the University of Queensland in the School of Chemistry of Molecular Biosciences. | 0 | Organic Chemistry |
Dexmethylphenidate, sold under the brand name Focalin among others, is a potent central nervous system (CNS) stimulant used to treat attention deficit hyperactivity disorder (ADHD) in those over the age of five years. It is taken by mouth. The immediate release formulation lasts up to five hours while the extended release formulation lasts up to twelve hours. It is the more active enantiomer of methylphenidate.
Common side effects include abdominal pain, loss of appetite, and fever. Serious side effects may include abuse, psychosis, sudden cardiac death, mania, anaphylaxis, seizures, and dangerously prolonged erection. Safety during pregnancy and breastfeeding is unclear. Dexmethylphenidate is a central nervous system (CNS) stimulant. How it works in ADHD is unclear.
Dexmethylphenidate was approved for medical use in the United States in 2001. It is available as a generic medication. In 2021, it was the 121st most commonly prescribed medication in the United States, with more than 4million prescriptions. | 4 | Stereochemistry |
In plants, potassium plays a key role in maintaining plant health. High concentrations of potassium in plants play a key role in synthesis of essential proteins in plants as well as development of plant organelles like cell walls to prevent damage from viruses and insects. It also lowers the concentration of low molecular weight molecules like sugars and amino acids and increases the concentration of high weight molecular weight molecules like protein which also prevent the development and propagation of viruses. Potassium absorption has a positive correlation with aquaporins and the uptake of water in plant cells via cell membrane proteins. Because of this correlation, it has been noted that potassium also plays a key part in stomatal movement and regulation as high concentrations of potassium are moved into the plant stomata to keep them open and promote photosynthesis. In animals, potassium also plays a key part along with sodium in maintaining resting cell membrane potential and in cell-cell communication via repolarization of axon pathways after an action potential between neurons. Potassium may also play a key part in maintaining blood pressure in animals as shown in a study where increased severity of periodontal disease and hypertension were inversely correlated to urinary potassium excretion (a telltale sign of low potassium intake). | 1 | Biochemistry |
The cytochrome complex, or cyt c, is a small hemeprotein found loosely associated with the inner membrane of the mitochondrion where it plays a critical role in cellular respiration.
It transfers electrons between Complexes III (Coenzyme Q – Cyt c reductase) and IV (Cyt c oxidase). Cytochrome c is highly water-soluble, unlike other cytochromes. It is capable of undergoing oxidation and reduction as its iron atom converts between the ferrous and ferric forms, but does not bind oxygen. It also plays a major role in cell apoptosis. In humans, cytochrome c is encoded by the CYCS gene. | 1 | Biochemistry |
The Newton and the Schrödinger equations in the absence of the macroscopic magnetic fields and in the inertial frame of reference are T-invariant: if X(t) is a solution then X(-t) is also a solution (here X is the vector of all dynamic variables, including all the coordinates of particles for the Newton equations and the wave function in the configuration space for the Schrödinger equation).
There are two sources of the violation of this rule:
* First, if dynamics depend on a pseudovector like the magnetic field or the rotation angular speed in the rotating frame then the T-symmetry does not hold.
* Second, in microphysics of weak interaction the T-symmetry may be violated and only the combined CPT symmetry holds. | 7 | Physical Chemistry |
The objective of environmental risk assessment is to protect the environment from adverse effects. Researchers are further developing QSAR models with the ultimate goal providing a clear insight about a mode of toxic action, but also about what the actual target site is, the concentration of the chemical at this target site, and the interaction occurring at the target site, as well as to predict the modes of toxic action in mixtures. Information on the mode of toxic action is crucial not only in understanding joint toxic effects and potential interactions between chemicals in mixtures, but also for developing assays for the evaluation of complex mixtures in the field. | 1 | Biochemistry |
A harmful algal bloom (HAB), or excessive algae growth, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Blooms can last from a few days to many months. After the bloom dies, the microbes that decompose the dead algae use up more of the oxygen, generating a "dead zone" which can cause fish die-offs. When these zones cover a large area for an extended period of time, neither fish nor plants are able to survive. Harmful algal blooms in marine environments are often called "red tides".
It is sometimes unclear what causes specific HABs as their occurrence in some locations appears to be entirely natural, while in others they appear to be a result of human activities. In certain locations there are links to particular drivers like nutrients, but HABs have also been occurring since before humans started to affect the environment. HABs are induced by eutrophication, which is an overabundance of nutrients in the water. The two most common nutrients are fixed nitrogen (nitrates, ammonia, and urea) and phosphate. The excess nutrients are emitted by agriculture, industrial pollution, excessive fertilizer use in urban/suburban areas, and associated urban runoff. Higher water temperature and low circulation also contribute.
HABs can cause significant harm to animals, the environment and economies. They have been increasing in size and frequency worldwide, a fact that many experts attribute to global climate change. The U.S. National Oceanic and Atmospheric Administration (NOAA) predicts more harmful blooms in the Pacific Ocean. Potential remedies include chemical treatment, additional reservoirs, sensors and monitoring devices, reducing nutrient runoff, research and management as well as monitoring and reporting.
Terrestrial runoff, containing fertilizer, sewage and livestock wastes, transports abundant nutrients to the seawater and stimulates bloom events. Natural causes, such as river floods or upwelling of nutrients from the sea floor, often following massive storms, provide nutrients and trigger bloom events as well. Increasing coastal developments and aquaculture also contribute to the occurrence of coastal HABs. Effects of HABs can worsen locally due to wind driven Langmuir circulation and their biological effects. | 3 | Analytical Chemistry |
The ionization threshold energy of atoms and small molecules are typically larger than the photon energies that are most easily available experimentally. However, it can be possible to span this ionization threshold energy if the photon energy is resonant with an intermediate electronically excited state. While it is often possible to observe the lower Rydberg levels in conventional spectroscopy of atoms and small molecules, Rydberg states are even more important in laser ionization experiments. Laser spectroscopic experiments often involve ionization through a photon energy resonance at an intermediate level, with an unbound final electron state and an ionic core. On resonance for phototransitions permitted by selection rules, the intensity of the laser in combination with the excited state lifetime makes ionization an expected outcome. This RIS approach and variations permit sensitive detection of specific species. | 7 | Physical Chemistry |
The enzymatic mechanism of influenza virus sialidase has been studied by Taylor et al., shown in Figure 1. The enzyme catalysis process has four steps. The first step involves the distortion of the α-sialoside from a C chair conformation (the lowest-energy form in solution) to a pseudoboat conformation when the sialoside binds to the sialidase. The second step leads to an oxocarbocation intermediate, the sialosyl cation. The third step is the formation of Neu5Ac initially as the α-anomer, and then mutarotation and release as the more thermodynamically stable β-Neu5Ac. | 0 | Organic Chemistry |
Ion semiconductor sequencing is a method of DNA sequencing based on the detection of hydrogen ions that are released during the polymerization of DNA. This is a method of "sequencing by synthesis", during which a complementary strand is built based on the sequence of a template strand.
A microwell containing a template DNA strand to be sequenced is flooded with a single species of deoxyribonucleotide triphosphate (dNTP). If the introduced dNTP is complementary to the leading template nucleotide, it is incorporated into the growing complementary strand. This causes the release of a hydrogen ion that triggers an ISFET ion sensor, which indicates that a reaction has occurred. If homopolymer repeats are present in the template sequence, multiple dNTP molecules will be incorporated in a single cycle. This leads to a corresponding number of released hydrogens and a proportionally higher electronic signal.
This technology differs from other sequencing-by-synthesis technologies in that no modified nucleotides or optics are used. Ion semiconductor sequencing may also be referred to as Ion Torrent sequencing, pH-mediated sequencing, silicon sequencing, or semiconductor sequencing. | 1 | Biochemistry |
UV water treatment devices can be used for well water and surface water disinfection. UV treatment compares favourably with other water disinfection systems in terms of cost, labour and the need for technically trained personnel for operation. Water chlorination treats larger organisms and offers residual disinfection, but these systems are expensive because they need special operator training and a steady supply of a potentially hazardous material. Finally, boiling of water is the most reliable treatment method but it demands labour and imposes a high economic cost. UV treatment is rapid and, in terms of primary energy use, approximately 20,000 times more efficient than boiling. | 5 | Photochemistry |
Reinecke's salt is an inorganic compound with the formula NH[Cr(NCS)(NH)]·HO. The dark-red crystalline compound is soluble in boiling water, acetone, and ethanol. It can be classified as a metal isothiocyanate complex. | 0 | Organic Chemistry |
Bacteria and archaea reproduce through asexual reproduction, usually by binary fission. Genetic exchange and recombination still occur, but this is a form of horizontal gene transfer and is not a replicative process, simply involving the transference of DNA between two cells, as in bacterial conjugation. | 1 | Biochemistry |
Presumptive tests, in medical and forensic science, analyze a sample and establish one of the following:
#The sample is definitely not a certain substance.
#The sample probably is the substance.
For example, the Kastle–Meyer test will show either that a sample is not blood or that the sample is probably blood but may be a less common substance. Further chemical tests are needed to prove that the substance is blood.
Confirmatory tests are the tests required to confirm the analysis. Confirmatory tests cost more than simpler presumptive tests so presumptive tests are often done to see if confirmatory tests are necessary.
Similarly, in medicine, a presumptive diagnosis identifies the likely condition of a patient, and a confirmatory diagnosis is needed to confirm the condition. | 3 | Analytical Chemistry |
There has been a general trend towards converting existing resin systems to waterborne resins, for ease of use and environmental considerations. Particularly, their development was driven by increased demand for solventless systems since the manufacture of coatings and adhesives entailed the increasing release of solvents into the atmosphere from numerous sources. Using VOC exempt solvents is not a panacea as they have their own weaknesses.
The problem has always been that polyurethanes in water are not stable, reacting to produce a urea and carbon dioxide. Many papers and patents have been published on the subject. For environmental reasons there is even a push to have PUD available both water-based and bio-based or made from renewable raw materials. PUDs are used because of the general desire to formulate coatings, adhesives, sealants and elastomers based on water rather than solvent, and because of the perceived or assumed benefits to the environment. | 7 | Physical Chemistry |
The term intermetallic is used to describe compounds involving two or more metals such as the cyclopentadienyl complex CpNiZn. | 8 | Metallurgy |
Buccianti was born on 7 August 1960 in Florence. She earned a master's degree in stratigraphy from the University of Florence in 1988, including work done as a student with Agip, and completed a PhD at the University of Florence in 1994. She obtained a permanent research position at the university in 2001. | 9 | Geochemistry |
Toxicological databases are large compilations of data derived from aquatic and environmental toxicity studies. Data is aggregated from a large number of individual studies in which toxic effects upon aquatic and terrestrial organisms have been determined for different chemicals. These databases are then used by toxicologists, chemists, regulatory agencies and scientists to investigate and predict the likelihood that an organic or inorganic chemical will cause an adverse effect (i.e. toxicity) on exposed organisms.
Several such databases have been compiled relating specifically to aquatic toxicology. | 1 | Biochemistry |
Naphthalene, an organic compound commonly found in pesticides such as mothballs, sublimes easily because it is made of non-polar molecules that are held together only by van der Waals intermolecular forces. Naphthalene is a solid that sublimes gradually at standard temperature and pressure, at a high rate, with the critical sublimation point at around 80°C or 176°F. At low temperature, its vapour pressure is high enough, 1mmHg at 53°C, to make the solid form of naphthalene evaporate into gas. On cool surfaces, the naphthalene vapours will solidify to form needle-like crystals. | 3 | Analytical Chemistry |
Brinelling is a material surface failure caused by Hertz contact stress that exceeds the material limit. It usually occurs in situations where a significant load force is distributed over a relatively small surface area. Brinelling typically results from a heavy or repeated impact load, either while stopped or during rotation, though it can also be caused by just one application of a force greater than the material limit.
Brinelling can be caused by a heavy load resting on a stationary bearing for an extended length of time. The result is a permanent dent or "brinell mark". The brinell marks will often appear in evenly spaced patterns along the bearing races, resembling the primary elements of the bearing, such as rows of indented lines for needle or roller bearings or rounded indentations in ball bearings. It is a common cause of roller bearing failures, and loss of preload in bolted joints when a hardened washer is not used. For example, brinelling occurs in casters when the ball bearings within the swivel head produce grooves in the hard cap, thus degrading performance by increasing the required swivel force. | 8 | Metallurgy |
Photoelectrochemistry has been intensively studied in the 1970-80s because of the first peak oil crisis. Because fossil fuels are non-renewable, it is necessary to develop processes to obtain renewable resources and use clean energy. Artificial photosynthesis, photoelectrochemical water splitting and regenerative solar cells are of special interest in this context. The photovoltaic effect was discovered by Alexandre Edmond Becquerel.
Heinz Gerischer, H. Tributsch, AJ. Nozik, AJ. Bard, A. Fujishima, K. Honda, PE. Laibinis, K. Rajeshwar, TJ Meyer, PV. Kamat, N.S. Lewis, R. Memming, John Bockris are researchers which have contributed a lot to the field of photoelectrochemistry. | 5 | Photochemistry |
The organic compound 1,1,1-trichloroethane, also known as methyl chloroform and chlorothene, is a chloroalkane with the chemical formula CHCCl. It is an isomer of 1,1,2-trichloroethane. This colorless, sweet-smelling liquid was once produced industrially in large quantities for use as a solvent. It is regulated by the Montreal Protocol as an ozone-depleting substance and its use is being rapidly phased out. | 2 | Environmental Chemistry |
Some methods are based on solutions to the Poisson–Boltzmann equation (PBE), often referred to as FDPB-based methods (FDPB stands for "finite difference Poisson–Boltzmann"). The PBE is a modification of Poisson's equation that incorporates a description of the effect of solvent ions on the electrostatic field around a molecule.
The [http://newbiophysics.cs.vt.edu/H++/ H++ web server], the [https://web.archive.org/web/20070728080556/http://enzyme.ucd.ie/pKD pKD webserver], [https://gunnerlab.github.io/Stable-MCCE/ MCCE2], [http://agknapp.chemie.fu-berlin.de/karlsberg Karlsberg+], [https://www.itqb.unl.pt/labs/molecular-simulation/in-house-software/ PETIT] and [https://rtullmann.de/parts/gmct-gcem.html GMCT] use the FDPB method to compute pK values of amino acid side chains.
FDPB-based methods calculate the change in the pK value of an amino acid side chain when that side chain is moved from a hypothetical fully solvated state to its position in the protein. To perform such a calculation, one needs theoretical methods that can calculate the effect of the protein interior on a pK value, and knowledge of the pKa values of amino acid side chains in their fully solvated states. | 7 | Physical Chemistry |
Co-administration of quinidine, a potent CYP2D6 enzyme inhibitor, with tramadol, a combination which results in markedly reduced levels of desmetramadol, was found not to significantly affect the analgesic effects of tramadol in human volunteers. However, other studies have found that the analgesic effects of tramadol are significantly decreased or even absent in CYP2D6 poor metabolizers. The analgesic effects of tramadol are only partially reversed by naloxone in human volunteers, hence indicating that its opioid action is unlikely the sole factor; tramadol's analgesic effects are also partially reversed by α-adrenergic receptor antagonists such as yohimbine, the 5-HT receptor antagonist ondansetron, and the 5-HT receptor antagonists SB-269970 and SB-258719. Pharmacologically, tramadol is similar to tapentadol and methadone in that it not only binds to the MOR, but also inhibits the reuptake of serotonin and norepinephrine due to its action on the noradrenergic and serotonergic systems, such as its "atypical" opioid activity.
Tramadol has inhibitory actions on the 5-HT receptor. Antagonism of 5-HT could be partially responsible for tramadols reducing effect on depressive and obsessive–compulsive symptoms in patients with pain and co-morbid neurological illnesses. 5-HT blockade may also account for its lowering of the seizure threshold, as 5-HT knockout mice display significantly increased vulnerability to epileptic seizures, sometimes resulting in spontaneous death. However, the reduction of seizure threshold could be attributed to tramadols putative inhibition of GABA receptors at high doses (significant inhibition at 100 μM). In addition, desmetramadol is a high-affinity ligand of the DOR, and activation of this receptor could be involved in tramadol's ability to provoke seizures in some individuals, as DOR agonists are well known for inducing seizures.
Nausea and vomiting caused by tramadol are thought to be due to activation of the 5-HT receptor via increased serotonin levels. In accordance, the 5-HT receptor antagonist ondansetron can be used to treat tramadol-associated nausea and vomiting. Tramadol and desmetramadol themselves do not bind to the 5-HT receptor. | 4 | Stereochemistry |
Bis(chloromethyl) ether is carcinogenic. It is one of 13 chemicals considered an OSHA-regulated occupational carcinogen. Chronic exposure has been linked to in increased risk of lung cancer.
It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities. | 0 | Organic Chemistry |
*Aerosol compound
**Cone pattern dispersion - wide pattern, don't have to aim precisely. It can be blown back by wind and if used inside a building, will eventually make room temporarily uninhabitable.
**Fog pattern dispersion (fogger)
**Stream pattern dispersion
**Grenade
*Gel compound: has greater accuracy and a reduced risk of blowback and area cross-contamination as the carrying gel does not disperse over a large area. The gel compound also adheres to the target making it more difficult to remove.
*Foam compound | 1 | Biochemistry |
Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings. Thermal spraying, also known as a spray welding process, is an industrial coating process that consists of a heat source (flame or other) and a coating material that can be in a powder or wire form, which is melted then sprayed on the surface of the material being treated at a high velocity. The spray treating process is known by many different names such as HVOF (High Velocity Oxygen Fuel), plasma spray, flame spray, arc spray and metalizing. | 8 | Metallurgy |
The evolution of hominoid communication is evident through chimpanzee hoo vocalizations and alarm calls. Researchers propose that communication evolved as natural selection diversified hoo vocalizations into context-dependent hoos for travel, rest, and threats. Context-dependent communication is beneficial and likely maintained by selection as it facilities cooperative activities and social cohesion between signallers and receivers that can increase the likelihood of survival. Alarm calls in chimpanzees also point to the evolution of hominoid language. Callers assess conspecifics' knowledge of threats, fill their need for information, and, in doing so, use social cues and intentionality to inform communication. Filling a gap in information and incorporating social cues and intentionality into communication are all components of human language. These shared elements between chimpanzee and human communication suggest an evolutionary basis, most likely that the last common human ancestor with chimpanzees also possessed these linguistic abilities. | 1 | Biochemistry |
In genetics, shotgun sequencing is a method used for sequencing random DNA strands. It is named by analogy with the rapidly expanding, quasi-random shot grouping of a shotgun.
The chain-termination method of DNA sequencing ("Sanger sequencing") can only be used for short DNA strands of 100 to 1000 base pairs. Due to this size limit, longer sequences are subdivided into smaller fragments that can be sequenced separately, and these sequences are assembled to give the overall sequence.
In shotgun sequencing, DNA is broken up randomly into numerous small segments, which are sequenced using the chain termination method to obtain reads. Multiple overlapping reads for the target DNA are obtained by performing several rounds of this fragmentation and sequencing. Computer programs then use the overlapping ends of different reads to assemble them into a continuous sequence.
Shotgun sequencing was one of the precursor technologies that was responsible for enabling whole genome sequencing. | 1 | Biochemistry |
In instances in which the environment is suboxic or anoxic, organisms will prefer to utilize denitrification to remineralise organic matter as it provides the second largest amount of energy. In depths below where denitrification is favored, reactions such as Manganese Reduction, Iron Reduction, Sulfate Reduction, Methane Reduction (also known as Methanogenesis), become favored respectively. This favorability is governed by Gibbs Free Energy (ΔG). In a water body, sediment seabed, or soil, the sorting of these chemical reactions with depth in order of energy provided is called a redox gradient. | 9 | Geochemistry |
In the synthesis of the cytotoxic germacranolide sesquiterpene eucannabinolide, Still demonstrates the application of the peripheral attack model to the reduction of a ketone to set a new stereocenter using NaBH. Significantly, the synthesis of eucannabinolide relied on the usage of molecular mechanics (MM2) computational modeling to predict the lowest energy conformation of the macrocycle to design substrate-controlled stereochemical reactions. | 0 | Organic Chemistry |
On 30 July 2015, scientists reported that upon the first touchdown of the Philae lander on comet 67/P surface, measurements by the COSAC and Ptolemy instruments revealed sixteen organic compounds, four of which were seen for the first time on a comet, including acetamide, acetone, methyl isocyanate and propionaldehyde.
In 2017, two teams of astronomers using the Atacama Large Millimeter Array (ALMA) interferometer made of 66 radio telescopes in the Atacama Desert (northern Chile) have discovered the presence of MIC around young Sun-like stars.
MIC is considered a prebiotic molecule as explained by the discoverers of the ALMA findings in IRAS 16293-2422, a multiple system of very young stars: "This family of organic molecules is involved in the synthesis of peptides and amino acids, which, in the form of proteins, are the biological basis for life as we know it". | 9 | Geochemistry |
UIT is highly controllable. Incorporating a programmable logic controller (PLC) or a Digital Ultrasonic Generator, the frequency and amplitude of UIT are easily set and maintained, thus removing a significant portion of operator dependency. UIT can also be mechanically controlled, thus providing repeatability of results from one application to the next. Examples of mechanical control employed with UIT include:
*CNC milling machines
*Lathes
*Robotic control
*Weld tractors
With these types of controlled applications, the surface finish of the work piece is highly controllable.
For many applications, UIT is most effectively employed by hand. The high portability of the UIT system enables travel to austere locations and hard to reach places. The flexibility that is facilitated by variations in the tool configuration (such as angle-peening-head) ensures that access to very tight locations is possible.
UIT's effectiveness has been illustrated on the following metals, among others:
*Aluminium (including sensitized Aluminium)
*Bronze
*Cobalt alloys
*Nickel alloys
*Steels
**Carbon steel
**Stainless steel
**High-strength low-alloy steel
**Manganese steel
*Titanium | 8 | Metallurgy |
Peroxisomal disorders are a class of medical conditions that typically affect the human nervous system as well as many other organ systems. Two common examples are X-linked adrenoleukodystrophy and the peroxisome biogenesis disorders. | 1 | Biochemistry |
Historically a cesium chloride (CsCl) solution was often used, but more commonly used density gradients are sucrose or Percoll. The sample is put on top of the solution, and then the tube is spun at a very high speed for an extended time, at times lasting days. The CsCl molecules become densely packed toward the bottom, so a continuous gradient of layers of different densities (and CsCl concentrations) form. Since the original solution was approximately the same density, they go to a level where their density and the CsCl density are the same, to which they form a sharp, distinctive band. | 3 | Analytical Chemistry |
The temperature of the system can be estimated by use of the Equipartition Theorem, with three degrees of freedom for each ion. Since ionic velocities are generally recorded at each step in the numerical simulation, the average kinetic energy of each ion is easy to calculate. There exist schemes which attempt to control the temperature of the simulation by, e.g. enforcing each ion to have exactly the kinetic energy predicted by the Equipartition Theorem (Berendsen thermostat) or by allowing the system to exchange energy and momentum with a (more massive) fictitious enclosing system (Nose-Hoover thermostat).
The net force on each ion is generally calculated explicitly at each numerical step. From this, the stress tensor of the system can be calculated and usually is calculated by the numerical package. By varying the convergence criteria, one can either seek a lowest energy structure or a structure that produces a desired stress tensor. Thus, high pressures can be simulated as easily as ambient pressures. | 3 | Analytical Chemistry |
Terephthalaldehyde (TA) is an organic compound with the formula CH(CHO). It is one of three isomers of benzene dicarboxaldehyde, in which the aldehyde moieties are positioned in the para conformation on the benzene ring. Terephthalaldehyde appears as a white to beige solid, typically in the form of a powder. It is soluble in many organic solvents, such as alcohols (e.g., methanol or ethanol) and ethers (e.g., tetrahydrofuran or diethylether). | 0 | Organic Chemistry |
A further step beyond superstructures and aperiodic materials is what is called diffuse scattering in electron diffraction patterns due to disorder, which is also known for x-ray or neutron scattering. This can occur from inelastic processes, for instance, in bulk silicon the atomic vibrations (phonons) are more prevalent along specific directions, which leads to streaks in diffraction patterns. Sometimes it is due to arrangements of point defects. Completely disordered substitutional point defects lead to a general background which is called Laue monotonic scattering. Often there is a probability distribution for the distances between point defects or what type of substitutional atom there is, which leads to distinct three-dimensional intensity features in diffraction patterns. An example of this is for a NbCoSb sample, with the diffraction pattern shown in Figure 16. Because of the vacancies at the niobium sites, there is diffuse intensity with snake-like structure due to correlations of the distances between vacancies and also the relaxation of Co and Sb atoms around these vacancies. | 7 | Physical Chemistry |
Laser schlieren deflectometry (LSD) is a method for a high-speed measurement of the gas temperature in microscopic dimensions, in particular for temperature peaks under dynamic conditions at atmospheric pressure. The principle of LSD is derived from schlieren photography: a narrow laser beam is used to scan an area in a gas where changes in properties are associated with characteristic changes of refractive index. Laser schlieren deflectometry is claimed to overcome limitations of other methods regarding temporal and spatial resolution.
The theory of the method is analogous to the scattering experiment of Ernest Rutherford from 1911. However, instead of alpha particles scattered by gold atoms, here an optical ray is deflected by hot spots with unknown temperature.
A general equation of LSD describes the dependence of the measured maximum deflection of the ray δ on the local maximum of the neutral gas temperature in the hot spot T:
where T is ambient temperature and δ is a calibration constant depending on the configuration of the experiment.
Laser schlieren deflectometry has been used for investigation of the temperature dynamics, heat transfer and energy balance in a miniaturized kind of atmospheric-pressure plasma. | 7 | Physical Chemistry |
hIntL-1 is a disulfide-linked trimer as shown by non-reducing SDS-PAGE and X-ray crystallography. Despite lacking the intermolecular disulfide bonds, XEEL-CRD is trimeric in solution. The N-terminal peptide of the full length XEEL is responsible for dimerizing the trimeric XEEL-CRD into a disulfide-linked hexameric full-length XEEL. Therefore, the N-termini of intelectins are often responsible for forming disulfide-linked oligomer. In intelectin homologs where the N-terminal cysteines are absent, the CRD itself may still capable of forming non-covalent oligomer in solution. | 1 | Biochemistry |
John Krige () is a historian of science and technology and the Kranzberg Professor at the School of History, Technology and Society, Georgia Institute of Technology, Atlanta. | 7 | Physical Chemistry |
The general form of the Eyring–Polanyi equation somewhat resembles the Arrhenius equation:
where is the rate constant, is the Gibbs energy of activation, is the transmission coefficient, is the Boltzmann constant, is the temperature, and is the Planck constant.
The transmission coefficient is often assumed to be equal to one as it reflects what fraction of the flux through the transition state proceeds to the product without recrossing the transition state. So, a transmission coefficient equal to one means that the fundamental no-recrossing assumption of transition state theory holds perfectly. However, is typically not one because (i) the reaction coordinate chosen for the process at hand is usually not perfect and (ii) many barrier-crossing processes are somewhat or even strongly diffusive in nature. For example, the transmission coefficient of methane hopping in a gas hydrate from one site to an adjacent empty site is between 0.25 and 0.5. Typically, reactive flux correlation function (RFCF) simulations are performed in order to explicitly calculate from the resulting plateau in the RFCF. This approach is also referred to as the Bennett-Chandler approach, which yields a dynamical correction to the standard transition state theory-based rate constant.
It can be rewritten as:
One can put this equation in the following form:
where:
* = reaction rate constant
* = absolute temperature
* = enthalpy of activation
* = gas constant
* = transmission coefficient
* = Boltzmann constant = R/N, N = Avogadro constant
* = Planck constant
* = entropy of activation
If one assumes constant enthalpy of activation, constant entropy of activation, and constant transmission coefficient, this equation can be used as follows: A certain chemical reaction is performed at different temperatures and the reaction rate is determined. The plot of versus gives a straight line with slope from which the enthalpy of activation can be derived and with intercept from which the entropy of activation is derived. | 7 | Physical Chemistry |
Although enol ethers can be considered the ether of the corresponding enolates, they are not prepared by alkylation of enolates. Some enol ethers are prepared from saturated ethers by elimination reactions.
Alternatively, vinyl ethers can be prepared from alcohols by iridium-catalyzed transesterification of vinyl esters, especially the widely available vinyl acetate:
:ROH + CH=CHOAc → ROCH=CH + HOAc
Vinyl ethers can be prepared by reaction of acetylene and alcohols in presence of a base. | 0 | Organic Chemistry |
As with any material implanted in the body, it is important to minimize or eliminate foreign body response and maximize effectual integration. Neural implants have the potential to increase the quality of life for patients with such disabilities as Alzheimers, Parkinsons, epilepsy, depression, and migraines. With the complexity of interfaces between a neural implant and brain tissue, adverse reactions such as fibrous tissue encapsulation that hinder the functionality, occur. Surface modifications to these implants can help improve the tissue-implant interface, increasing the lifetime and effectiveness of the implant. | 7 | Physical Chemistry |
This method is an adaptation of mRNA display technology. PCR DNA is first transcribed to mRNA, and a single-stranded DNA oligonucleotide modified with biotin and puromycin on each end is then hybridized to the 3’-end of the mRNA. The mRNAs are then arrayed on a slide and immobilized by the binding of biotin to streptavidin that is pre-coated on the slide. Cell extract is then dispensed on the slide for in situ translation to take place. When the ribosome reaches the hybridized oligonucleotide, it stalls and incorporates the puromycin molecule to the nascent polypeptide chain, thereby attaching the newly synthesized protein to the microarray via the DNA oligonucleotide. A pure protein array is obtained after the mRNA is digested with RNase. The protein spots generated by this method are very sharply defined and can be produced at a high density. | 1 | Biochemistry |
In the presence of excess of triphenylphosphine, RuCl(PPh) binds a fourth phosphine to give black RuCl(PPh). The triphenylphosphine ligands in both the tris(phosphine) and tetrakis(phosphine) complexes are readily substituted by other ligands. The tetrakis(phosphine) complex is a precursor to the Grubbs catalysts.
Dichlorotris(triphenylphosphine)ruthenium(II) reacts with hydrogen in the presence of base to give the purple-colored monohydride HRuCl(PPh).
:RuCl(PPh) + H + NEt → HRuCl(PPh) + [HNEt]Cl
Dichlorotris(triphenylphosphine)ruthenium(II) reacts with carbon monoxide to produce the all trans isomer of dichloro(dicarbonyl)bis(triphenylphosphine)ruthenium(II).
:RuCl(PPh) + 2 CO → trans,trans,trans-RuCl(CO)(PPh) + PPh
This kinetic product isomerizes to the cis adduct during recrystallization. trans-RuCl(dppe) forms upon treating RuCl(PPh) with dppe.
:RuCl(PPh) + 2 dppe → RuCl(dppe) + 3 PPh
RuCl(PPh) catalyzes the decomposition of formic acid into carbon dioxide and hydrogen gas in the presence of an amine. Since carbon dioxide can be trapped and hydrogenated on an industrial scale, formic acid represents a potential storage and transportation medium. | 0 | Organic Chemistry |
Before atomic orbitals were understood, spectroscopists discovered various distinctive series of spectral lines in atomic spectra, which they identified by letters. These letters were later associated with the azimuthal quantum number, ℓ. The letters, "s", "p", "d", and "f", for the first four values of ℓ were chosen to be the first letters of properties of the spectral series observed in alkali metals. Other letters for subsequent values of ℓ were assigned in alphabetical order, omitting the letter "j" because some languages do not distinguish between the letters "i" and "j":
This notation is used to specify electron configurations and to create the term symbol for the electron states in a multi-electron atom. When writing a term symbol, the above scheme for a single electron's orbital quantum number is applied to the total orbital angular momentum associated to an electron state. | 7 | Physical Chemistry |
Finely ground agricultural lime is often applied to acid soils to increase soil pH (liming). The amount of limestone or chalk needed to change pH is determined by the mesh size of the lime (how finely it is ground) and the buffering capacity of the soil. A high mesh size (60 mesh = 0.25 mm; 100 mesh = 0.149 mm) indicates a finely ground lime that will react quickly with soil acidity. The buffering capacity of a soil depends on the clay content of the soil, the type of clay, and the amount of organic matter present, and may be related to the soil cation exchange capacity. Soils with high clay content will have a higher buffering capacity than soils with little clay, and soils with high organic matter will have a higher buffering capacity than those with low organic matter. Soils with higher buffering capacity require a greater amount of lime to achieve an equivalent change in pH. The buffering of soil pH is often directly related to the quantity of aluminium in soil solution and taking up exchange sites as part of the cation exchange capacity. This aluminium can be measured in a soil test in which it is extracted from the soil with a salt solution, and then is quantified with a laboratory analysis. Then, using the initial soil pH and the aluminium content, the amount of lime needed to raise the pH to a desired level can be calculated.
Amendments other than agricultural lime that can be used to increase the pH of soil include wood ash, industrial calcium oxide (burnt lime), magnesium oxide, basic slag (calcium silicate), and oyster shells. These products increase the pH of soils through various acid–base reactions. Calcium silicate neutralizes active acidity in the soil by reacting with H ions to form monosilicic acid (HSiO), a neutral solute. | 9 | Geochemistry |
In 1997 France became the first country to ban minors from indoor tanning. Under-18s are similarly prohibited in Austria, Belgium, Germany, Ireland, Portugal, Spain, Poland and the United Kingdom. In addition, Ireland prohibits salons from offering "happy hour" discounts. Netherlands also forbid the usage of a tanning bed below the age of 18. | 5 | Photochemistry |
The polyol pathway is a two-step process that converts glucose to fructose. In this pathway glucose is reduced to sorbitol, which is subsequently oxidized to fructose. It is also called the sorbitol-aldose reductase pathway.
The pathway is implicated in diabetic complications, especially in microvascular damage to the retina, kidney, and nerves.
Sorbitol cannot cross cell membranes, and, when it accumulates, it produces osmotic stresses on cells by drawing water into the insulin-independent tissues. | 1 | Biochemistry |
Coatings can be both decorative and have other functions. A pipe carrying water for a fire suppression system can be coated with a red (for identification) anticorrosion paint. Most coatings to some extent protect the substrate, such as maintenance coatings for metals and concrete. A decorative coating can offer a particular reflective property, such as high gloss, satin, matte, or flat appearance.
A major coating application is to protect metal from corrosion. Automotive coatings are used to enhance the appearance and durability of vehicles. These include primers, basecoats, and clearcoats, primarily applied with spray guns and electrostatically.
The body and underbody of automobiles receive some form of underbody coating. Such anticorrosion coatings may use graphene in combination with water-based epoxies.
Coatings are used to seal the surface of concrete, such as seamless polymer/resin flooring, bund wall/containment lining, waterproofing and damp proofing concrete walls, and bridge decks.
Most roof coatings are designed primarily for waterproofing, though sun reflection (to reduce heating and cooling) may also be a consideration. They tend to be elastomeric to allow for movement of the roof without cracking within the coating membrane.
Wood has been a key material in construction since ancient times, so its preservation by coating has received much attention. Efforts to improve the performance of wood coatings continue.
Coatings are used to alter tribological properties and wear characteristics. These include anti-friction, wear and scuffing resistance coatings for rolling-element bearings | 8 | Metallurgy |
Materials with yield strength anomalies are used in nuclear reactors due to their high temperature mechanical properties and good corrosion resistance. | 8 | Metallurgy |
Environmental temperature: Decomposition is accelerated by high atmospheric or environmental temperature, with putrefaction speed optimized between and , further sped along by high levels of humidity. This optimal temperature assists in the chemical breakdown of the tissue and promotes microorganism growth. Decomposition nearly stops below or above .
Moisture and air exposure: Putrefaction is ordinarily slowed by the body being submerged in water, due to diminished exposure to air. Air exposure and moisture can both contribute to the introduction and growth of microorganisms, speeding degradation. In a hot and dry environment, the body can undergo a process called mummification where the body is completely dehydrated and bacterial decay is inhibited.
Clothing: Loose-fitting clothing can speed up the rate of putrefaction, as it helps to retain body heat. Tight-fitting clothing can delay the process by cutting off blood supply to tissues and eliminating nutrients for bacteria to feed on.
Manner of burial: Speedy burial can slow putrefaction. Bodies within deep graves tend to decompose more slowly due to the diminished influences of changes in temperature. The composition of graves can also be a significant contributing factor, with dense, clay-like soil tending to speed putrefaction while dry and sandy soil slows it.
Light exposure: Light can also contribute indirectly, as flies and insects prefer to lay eggs in areas of the body not exposed to light, such as the crevices formed by the eyelids and nostrils. | 1 | Biochemistry |
The reaction proceeds via a cascade of four subsequent pericyclic reactions (Scheme 3). Heating a cyclobutenone above 80 °C initiates a four-electron electrocyclic cleavage generating a vinyl ketene which reacts with an acetylene in a regiospecific [2+2] cycloaddition (Scheme 4). Reversible electrocyclic cleavage of the 2-vinylcyclobutenone yields a dienylketene. The dienylketene then undergoes a six-electron electrocyclization to give a hexadienone intermediate which rapidly tautomerizes to yield a highly substituted phenol or naphthol structures.
In the case of the modified benzannulation reaction (Scheme 5); irradiation of the diazoketones induces the Wolff rearrangement yielding the vinyl ketene intermediate which reacts with the acetylene in a [2+2] cycloaddition then a four-electron cleavage of the resulting 4-substituted cyclobutenone produces a dienylketene which then undergoes a six-electron electrocyclization to give the 2,4-cyclohexanedione which tautomerizes to the final aromatic product. | 0 | Organic Chemistry |
Co-styrene-maleic anhydride and co-styrene acrylate are common binders associated with a cationic starch pigment in Inkjet printing paper. Table 1 shows their surface tension under given conditions.
There have been several studies that have focused on how the paper printing quality is dependent on the concentration of these binders and ink pigment. Data from the experiments are congruent and stated in Table 2 as the corrected contact angle of water, the corrected contact angle of black ink, and the total surface energy.
The contact angle measurement has proven to be a very useful tool to evaluate the influence of the sizing formulation on the printing properties. Surface free energy has also shown to be very valuable in explaining the differences in sample behavior. | 7 | Physical Chemistry |
The essential feature of a glycolipid is the presence of a monosaccharide or oligosaccharide bound to a lipid moiety. The most common lipids in cellular membranes are glycerolipids and sphingolipids, which have glycerol or a sphingosine backbones, respectively. Fatty acids are connected to this backbone, so that the lipid as a whole has a polar head and a non-polar tail. The lipid bilayer of the cell membrane consists of two layers of lipids, with the inner and outer surfaces of the membrane made up of the polar head groups, and the inner part of the membrane made up of the non-polar fatty acid tails.
The saccharides that are attached to the polar head groups on the outside of the cell are the ligand components of glycolipids, and are likewise polar, allowing them to be soluble in the aqueous environment surrounding the cell. The lipid and the saccharide form a glycoconjugate through a glycosidic bond, which is a covalent bond. The anomeric carbon of the sugar binds to a free hydroxyl group on the lipid backbone. The structure of these saccharides varies depending on the structure of the molecules to which they bind. | 0 | Organic Chemistry |
While the Superstack lowered the ground-level pollution in the city, it has dispersed sulphur dioxide, and nitrogen dioxide gases over a much larger area. Though not the single source of lake acidification, it appears even the heavily industrialized Ohio Valley has contributed to the ecological problem of lakes as far north as northern Ontario. Research from data gleaned up to the late 1980s demonstrated acid rain to have affected the biology of some 7,000 lakes.
Prior to Vale's purchase of Inco, a major construction effort by Inco in the early 1990s dramatically scrubbed waste gases before pumping them up the Superstack. These upgrades were completed in 1994 and emissions from then on have been much reduced. By comparison to the plume prior to installation, the plume now disperses quite rapidly and is often see-through even at the stack site.
Emissions reductions and increases in thermal efficiency have reached the point where natural draught is no longer sufficient to draw flue gas up the stack, necessitating the use of induced draught fans and/or reheating of the flue gas using natural gas burners.
In contrast to the reduction of SO emissions, Inco's Superstack stands out in North America in its arsenic, nickel and lead emissions to the atmosphere. Using data compiled by the Commission for Environmental Cooperation, Inco alone accounts for 20% of all of the arsenic emitted in North America, 13% of the lead and 30% of the nickel. Although it is not strictly fair to compare a nickel-copper smelter to a lead smelter, by so doing one can get an idea of how poor the containment of lead is at Copper Cliff. In 1998, Inco emitted 146.7 tonnes of lead at Copper Cliff with a smelter production of 238,500 tonnes of nickel-copper matte. The EPA regulations in the United States require a primary lead smelter to limit emissions of lead to 3.0 gm per tonne of product. With this emission factor, Copper Cliff would be required to limit emissions of lead to approximately 1 tonne per year, demonstrating that the actual emission is about 150 times greater than allowed by US regulations for a lead smelter. Even with the 85% reduction postulated by Hatch, Inco would still emit 10 tonnes per year of lead, or four times the amount allowed by the EPA for a lead smelter.
As a result of the excessive lead emissions from the Inco Superstack, the surrounding community of Copper Cliff was found to have levels of lead in soil tests at a level sufficient to cause harm to young children. | 8 | Metallurgy |
The Polevskoy Copper Smelting Plant (), also known as Polevaya or Poleva, was one of the major metallurgical facilities located in Polevskoy, in Sverdlovsk Oblast of Russia. | 8 | Metallurgy |
CRISPR gene editing technology in humans has the potential to cause profound social impacts, such as in the long-term prevention of diseases in humans. However, Hes human experiments raised ethical concerns the effect are unknown on future generations. Ethical concerns have been raised relative to the four ethical criteria of autonomy, justice, beneficence, and non-maleficence, first postulated by Tom Beauchamp and James Childress in Principles of Biomedical Ethics'.
The ethical principle of autonomy requires that individuals have the ability and comprehensive information to make their own decisions based on their values and beliefs. He violated this by failing to inform patients of potential risks, including off-target mutations that might be a threat to the twins' lives.
Since He had forged the approval certificate from the hospitals Director of Direct Genomics, the procedure was likely "unlawful", which is against the principle of non-maleficence. Off-target mutations are likely to start at undesired sites, causing cell death or cell transformation. Sonia Ouagrham-Gormley, an associate professor in the Schar School of Policy and Government at George Mason University, and Kathleen Vogel, a professor in the School for the Future of Innovation in Society at Arizona State University, stated that the procedure was "unnecessary" and "risks the safety of the patients". The researchers criticized Hes unethical action by presenting the fact that the prevention of HIV transmission from parents to newborn babies can be safely achieved with existing standard methods, such as sperm washing and caesarian section delivery.
The principle of justice argues that individuals should have the right to receive the same amount of care from medical providers regardless of their social and economic background. Beneficence requires healthcare providers to maximize benefits and put the benefit of the patients first. Hes intervention in the twins genes cannot be justified, and the risk-benefit is unacceptable. He paid the couple $40,000 to ensure that they would keep his operation confidential. This action can be viewed as an inducement and violates China's regulations on the prohibition of genetic manipulation of human gametes, zygotes, and embryos for reproductive purposes; HIV carriers being not allowed to have assisted reproductive technologies, and the manipulation of a human embryo for research being only permitted within 14 days.
Thus, while genome editing in humans has potential as an effective and cost-efficient method for manipulating genes within living cells, it requires more research and transparent procedures to be ethically justified. | 1 | Biochemistry |
Arsenic can sublime readily at high temperatures.
Cadmium and zinc sublime much more than other common materials, so they are not suitable materials for use in vacuum. | 3 | Analytical Chemistry |
1-Pyrroline-5-carboxylic acid (systematic name 3,4-dihydro-2H-pyrrole-2-carboxylic acid) is a cyclic imino acid. Its conjugate base and anion is 1-pyrroline-5-carboxylate (P5C). In solution, P5C is in spontaneous equilibrium with glutamate-5-semialdhyde (GSA). | 1 | Biochemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.