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In 2008, Place et al. identified targets for miRNA miR-373 on the promoters of several human genes and found that introduction of miR-373 mimics into human cells induced the expression of its predicted target genes. This study provided the first example that RNAa could be mediated by naturally occurring non-coding RNA (ncRNA). In 2011, Huang et al. further demonstrated in mouse cells that endogenous RNAa mediated by miRNAs functions in a physiological context and is possibly exploited by cancer cells to gain a growth advantage. Since then, a number of miRNAs have been shown to upregulate gene expression by targeting gene promoters or enhancers, thereby, exerting important biological roles. A good example is miR-551b-3p which is overexpressed in ovarian cancer due to amplification. By targeting the promoter of STAT3 to increase its transcription, miR-551b-3p confers to ovarian cancer cells resistance to apoptosis and a proliferative advantage.
In C. elegans hypodermal seam cells, the transcription of lin-4 miRNA is positively regulated by lin-4 itself which binds to a conserved lin-4 complementary element in its promoter, constituting a positive autoregulatory loop.
In C. elegans, Argonaute CSR-1 interacts with 22G small RNAs derived from RNA-dependent RNA polymerase and antisense to germline-expressed transcripts to protect these mRNAs from Piwi-piRNA mediated silencing via promoting epigenetic activation.
It is currently unknown how widespread gene regulation by endogenous RNAa is in mammalian cells. Studies have shown that both miRNAs and Ago proteins (Ago1) bind to numerous sites in human genome, especially promoter regions, to exert a largely positive effect on gene transcription. | 1 | Applied and Interdisciplinary Chemistry |
Several isozymes of malate dehydrogenase exist. There are two main isoforms in eukaryotic cells. One is found in the mitochondrial matrix, participating as a key enzyme in the citric acid cycle that catalyzes the oxidation of malate. The other is found in the cytoplasm, assisting the malate-aspartate shuttle with exchanging reducing equivalents so that malate can pass through the mitochondrial membrane to be transformed into oxaloacetate for further cellular processes.
Humans and most other mammals express the following two malate dehydrogenases: | 1 | Applied and Interdisciplinary Chemistry |
Fatty acids with an odd number of carbons are found in the lipids of plants and some marine organisms. Many ruminant animals form a large amount of 3-carbon propionate during the fermentation of carbohydrates in the rumen. Long-chain fatty acids with an odd number of carbon atoms are found particularly in ruminant fat and milk.
Chains with an odd-number of carbons are oxidized in the same manner as even-numbered chains, but the final products are propionyl-CoA and acetyl-CoA.
Propionyl-CoA is first carboxylated using a bicarbonate ion into a D-stereoisomer of methylmalonyl-CoA. This reaction involves a biotin co-factor, ATP and the enzyme propionyl-CoA carboxylase. The bicarbonate ion's carbon is added to the middle carbon of propionyl-CoA, forming a D-methylmalonyl-CoA. However, the D-conformation is enzymatically converted into the L-conformation by methylmalonyl-CoA epimerase. It then undergoes intramolecular rearrangement, which is catalyzed by methylmalonyl-CoA mutase (requiring B as a coenzyme) to form succinyl-CoA. The succinyl-CoA formed then enters the citric acid cycle.
However, whereas acetyl-CoA enters the citric acid cycle by condensing with an existing molecule of oxaloacetate, succinyl-CoA enters the cycle as a principal in its own right. Thus, the succinate just adds to the population of circulating molecules in the cycle and undergoes no net metabolization while in it. When this infusion of citric acid cycle intermediates exceeds cataplerotic demand (such as for aspartate or glutamate synthesis), some of them can be extracted to the gluconeogenesis pathway, in the liver and kidneys, through phosphoenolpyruvate carboxykinase, and converted to free glucose. | 1 | Applied and Interdisciplinary Chemistry |
Droplet-based microfluidics can be used to generate microparticles with repeatable size.
* manipulation of alginate solution to allow microcapsules to be created | 1 | Applied and Interdisciplinary Chemistry |
The Boulet Asphyxiant was a rumoured Russian chemical weapon during the Crimean War. The rumour was first found in the French newspaper Atlas before spreading to English-language publications.
According to the rumour, the Asphyxiant was developed by a French chemical researcher, M. Fortier, in 1839. He approached the Minister of Marine, who refused to accept the design, noting "the great number of means for the destruction of human life already existing", and the proposal ended there. The same proposal was made again in 1842, this time by a M. Champion, and again rejected, ending the matter until Champion "repaired his broken fortunes in Russia".
Fortiers Asphyxiant was then allegedly discovered during the Crimean War after the Battle of Sinop; those Turkish sailors who escaped reported that the Russians were using Greek fire. This was treated as humour until a French engineer examined the destroyed ships and found that the weapons used against them were new and unknown, sending fragments to his commander, who served with an officer who had been on the Council of the Marine when Fortier made his initial proposal. The Asphyxiant, according to the rumour, was a liquid fire that exploded under the waters surface, producing a gas that suffocated anyone on the surface. The rumour was countered by allegations amongst British forces that they had invented a secret device of their own, MacIntosh's Portable Buoyant Wave Repressor, which suppressed waves. | 1 | Applied and Interdisciplinary Chemistry |
I is produced by proton irradiation of Xe. The caesium isotope produced is unstable and decays to I. The isotope is usually supplied as the iodide and hypoiodate in dilute sodium hydroxide solution, at high isotopic purity. I has also been produced at Oak Ridge National Laboratories by proton bombardment of Te.
I decays by electron capture with a half-life of 13.22 hours. The emitted 159 keV gamma ray is used in single-photon emission computed tomography (SPECT). A 127 keV gamma ray is also emitted.
I is frequently used in radioimmunoassays because of its relatively long half-life (59 days) and ability to be detected with high sensitivity by gamma counters.
I is present in the environment as a result of the testing of nuclear weapons in the atmosphere. It was also produced in the Chernobyl and Fukushima disasters. I decays with a half-life of 15.7 million years, with low-energy beta and gamma emissions. It is not used as a tracer, though its presence in living organisms, including human beings, can be characterized by measurement of the gamma rays. | 0 | Theoretical and Fundamental Chemistry |
* Since the technique involves the use of SDS-PAGE which utilizes the effect that sodium-dodecyl sulfate has on proteins which is to denature them, there is the possibility of dissociating protein factors that possess multiple subunits through the process. This could end up affecting how well the protein factor binds to DNA in later steps of the technique.
* Not all proteins renature during the transfer process to the nitrocellulose membranes after separation via SDS-PAGE. This area of protein renaturation is still being experimented with.
* Also being experimented with is reusability of southwestern blots to test proteins with a variety of DNA probes before disposal. However, the main challenge is putting together a scheme that outlines conditions that can remove previously used probes from the blot without the expense of denaturing the proteins or extracting them. | 1 | Applied and Interdisciplinary Chemistry |
After completing his education, Taube remained in the United States, becoming an instructor in chemistry at Berkeley until 1941. He initially wanted to return to Canada to work, but did not receive a response when he applied for jobs at the major Canadian universities. From Berkeley, he served as an instructor and assistant professor at Cornell University until 1946. During World War II, Taube served on the National Defense Research Committee. Taube spent time at the University of Chicago as an assistant professor, associate professor and as a full professor from 1946 to 1961. He served as chair of the chemistry department in Chicago from 1956 to 1959, but did not enjoy administrative work. After leaving Chicago, Taube worked as a professor at Stanford University until 1986, a position that allowed him to focus on research, while also teaching classes at the undergraduate and graduate levels. He became a Professor Emeritus at Stanford in 1986, but he continued to perform research until 2001, and visited his labs every day until his death in 2005. In addition to his academic duties, Taube also served as a consultant at Los Alamos National Laboratory from 1956 until the 1970s. | 0 | Theoretical and Fundamental Chemistry |
Alexander Nikolayevich was one of the greatest organic chemists of the 20th century. He organised a number of fundamental works on the theory of the structure and reactivity of organic compounds. He created a new discipline lying on the border of inorganic and organic chemistry, which was called "chemistry of organoelement compounds". Also he has researched the production of synthetic food, the creation of new drugs and the synthesis of a number of technical materials. | 0 | Theoretical and Fundamental Chemistry |
The spliceosome is a very complex structure containing up to one hundred proteins and five different RNAs. The substrate of the reaction is a long RNA molecule and the transesterification reactions catalyzed by the spliceosome require the bringing together of sites that may be thousands of nucleotides apart. All biochemical reactions are associated with known error rates and the more complicated the reaction the higher the error rate. Therefore, it is not surprising that the splicing reaction catalyzed by the spliceosome has a significant error rate even though there are spliceosome accessory factors that suppress the accidental cleavage of cryptic splice sites.
Under ideal circumstances, the splicing reaction is likely to be 99.999% accurate (error rate of 10) and the correct exons will be joined and the correct intron will be deleted. However, these ideal conditions require very close matches to the best splice site sequences and the absence of any competing cryptic splice site sequences within the introns and those conditions are rarely met in large eukaryotic genes that may cover more than 40 kilobase pairs. Recent studies have shown that the actual error rate can be considerably higher than 10 and may be as high as 2% or 3% errors (error rate of 2 or 3 x 10) per gene. Additional studies suggest that the error rate is no less than 0.1% per intron. This relatively high level of splicing errors explains why most splice variants are rapidly degraded by nonsense-mediated decay.
The presence of sloppy binding sites within genes causes splicing errors and it may seem strange that these sites haven't been eliminated by natural selection. The argument for their persistence is similar to the argument for junk DNA.
While the catalytic reaction may be accurate enough for effective processing most of the time, the overall error rate may be partly limited by the fidelity of transcription because transcription errors will introduce mutations that create cryptic splice sites. In addition, the transcription error rate of 10 – 10 is high enough that one in every 25,000 transcribed exons will have an incorporation error in one of the splice sites leading to a skipped intron or a skipped exon. Almost all multi-exon genes will produce incorrectly spliced transcripts but the frequency of this background noise will depend on the size of the genes, the number of introns, and the quality of the splice site sequences.
In some cases, splice variants will be produced by mutations in the gene (DNA). These can be SNP polymorphisms that create a cryptic splice site or mutate a functional site. They can also be somatic cell mutations that affect splicing in a particular tissue or a cell line. When the mutant allele is in a heterozygous state this will result in production of two abundant splice variants; one functional and one non-functional. In the homozygous state the mutant alleles may cause a genetic disease such as the hemophilia found in descendants of Queen Victoria where a mutation in one of the introns in a blood clotting factor gene creates a cryptic 3' splice site resulting in aberrant splicing. A significant fraction of human deaths by disease may be caused by mutations that interfere with normal splicing; mostly by creating cryptic splice sites.
Incorrectly spliced transcripts can easily be detected and their sequences entered into the online databases. They are usually described as "alternatively spliced" transcripts, which can be confusing because the term does not distinguish between real, biologically relevant, alternative splicing and processing noise due to splicing errors. One of the central issues in the field of alternative splicing is working out the differences between these two possibilities. Many scientists have argued that the null hypothesis should be splicing noise, putting the burden of proof on those who claim biologically relevant alternative splicing. According to those scientists, the claim of function must be accompanied by convincing evidence that multiple functional products are produced from the same gene. | 1 | Applied and Interdisciplinary Chemistry |
Terfenol-D, an alloy of the formula (x ≈ 0.3), is a magnetostrictive material. It was initially developed in the 1970s by the Naval Ordnance Laboratory in the United States. The technology for manufacturing the material efficiently was developed in the 1980s at Ames Laboratory under a U.S. Navy-funded program. It is named after terbium, iron (Fe), Naval Ordnance Laboratory (NOL), and the D comes from dysprosium. | 1 | Applied and Interdisciplinary Chemistry |
In the adult brain, the endocannabinoid system facilitates the neurogenesis of hippocampal granule cells. In the subgranular zone of the dentate gyrus, multipotent neural progenitors (NP) give rise to daughter cells that, over the course of several weeks, mature into granule cells whose axons project to and synapse onto dendrites on the CA3 region. NPs in the hippocampus have been shown to possess fatty acid amide hydrolase (FAAH) and express CB and utilize 2-AG. Intriguingly, CB activation by endogenous or exogenous cannabinoids promote NP proliferation and differentiation; this activation is absent in CB knockouts and abolished in the presence of antagonist. | 1 | Applied and Interdisciplinary Chemistry |
While identification of open reading frames within a DNA sequence is straightforward, identifying coding sequences is not, because the cell translates only a subset of all open reading frames to proteins. Currently CDS prediction uses sampling and sequencing of mRNA from cells, although there is still the problem of determining which parts of a given mRNA are actually translated to protein. CDS prediction is a subset of gene prediction, the latter also including prediction of DNA sequences that code not only for protein but also for other functional elements such as RNA genes and regulatory sequences.
In both prokaryotes and eukaryotes, gene overlapping occurs relatively often in both DNA and RNA viruses as an evolutionary advantage to reduce genome size while retaining the ability to produce various proteins from the available coding regions. For both DNA and RNA, pairwise alignments can detect overlapping coding regions, including short open reading frames in viruses, but would require a known coding strand to compare the potential overlapping coding strand with. An alternative method using single genome sequences would not require multiple genome sequences to execute comparisons but would require at least 50 nucleotides overlapping in order to be sensitive. | 1 | Applied and Interdisciplinary Chemistry |
In the study of heat transfer, radiative cooling is the process by which a body loses heat by thermal radiation. As Planck's law describes, every physical body spontaneously and continuously emits electromagnetic radiation.
Radiative cooling has been applied in various contexts throughout human history, including ice making in India and Iran, heat shields for spacecraft, and in architecture. In 2014, a scientific breakthrough in the use of photonic metamaterials made daytime radiative cooling possible. It has since been proposed as a strategy to mitigate local and global warming caused by greenhouse gas emissions known as passive daytime radiative cooling. | 0 | Theoretical and Fundamental Chemistry |
The 5′ UTR begins at the transcription start site and ends one nucleotide (nt) before the initiation sequence (usually AUG) of the coding region. In prokaryotes, the length of the 5′ UTR tends to be 3–10 nucleotides long, while in eukaryotes it tends to be anywhere from 100 to several thousand nucleotides long. For example, the ste11 transcript in Schizosaccharomyces pombe has a 2273 nucleotide 5′ UTR while the lac operon in Escherichia coli only has seven nucleotides in its 5′ UTR. The differing sizes are likely due to the complexity of the eukaryotic regulation which the 5′ UTR holds as well as the larger pre-initiation complex that must form to begin translation.
The 5′ UTR can also be completely missing, in the case of leaderless mRNAs. Ribosomes of all three domains of life accept and translate such mRNAs. Such sequences are naturally found in all three domains of life. Humans have many pressure-related genes under a 2–3 nucleotide leader. Mammals also have other types of ultra-short leaders like the TISU sequence. | 1 | Applied and Interdisciplinary Chemistry |
SCO is also influenced by the application of pressure, which changes the population of the HS and LS states. Upon application of pressure, a conversion from the HS state to the LS state and a shift from T, (the temperature at which half of the complex is in a LS state), to higher temperatures will occur. This effect results from an increase in the zero point energy difference, ΔE°, caused by an increase in the relative vertical displacement of the potential wells and a decrease in the activation energy, ΔW°, which favors the LS state. The complex Fe(phen)(SCN) exhibits this effect. At high pressures the LS state predominates and the transition temperature increases. At high pressures the compound is almost entirely transformed to the LS state at room temperature. As a result of the application of pressure on the Fe(phen)(SCN) compound, the bond lengths are affected. The difference in M-L bond lengths in both HS and LS states changes the entropy of the system. The change in spin transition temperature, T and pressure obeys the Clausius-Clapeyron relationship:
The increase in pressure will decrease the volume of the unit cell of the Fe(phen)(SCN) and increase the T of the system. A linear relationship between T and pressure for Fe(phen)(SCN), where the slope of the line is . | 0 | Theoretical and Fundamental Chemistry |
Polymer concrete, a material commonly used in industrial flooring, uses polymers, typically resins, to replace lime-type cements as a binder. Researchers have found that grounded recycled glass can be used as a substitute for sand when making polymer concrete.
According to research, using recycled glass instead of sand produces a high strength, water-resistant material suitable for industrial flooring and infrastructure drainage, particularly in areas subject to heavy traffic such as service stations, forklift operating areas and airports. | 0 | Theoretical and Fundamental Chemistry |
If the substrate has both an α- and β-stereocenter, the Felkin–Anh rule (1,2-induction) and the Evans model (1,3-induction) should considered at the same time. If these two stereocenters have an anti- relationship, both models predict the same diastereomer (the stereoreinforcing case).
However, in the case of the syn-substrate, the Felkin–Anh and the Evans model predict different products (non-stereoreinforcing case). It has been found that the size of the incoming nucleophile determines the type of control exerted over the stereochemistry. In the case of a large nucleophile, the interaction of the α-stereocenter with the incoming nucleophile becomes dominant; therefore, the Felkin product is the major one. Smaller nucleophiles, on the other hand, result in 1,3 control determining the asymmetry. | 0 | Theoretical and Fundamental Chemistry |
A relatively non-toxic metal to humans and the second most abundant, the body has 2-3 grams of zinc. It can enter the body through inhalation, skin absorption, and ingestion, with the latter of the bunch being the most common. The mucosal cells of the digestive tract contain metallothionein proteins that store the zinc ions.
Nearly 90% of zinc is found in the bones, muscles, and vesicles in the brain. Zinc is a cofactor in hundreds of enzyme reactions and a major component of zinc finger proteins. | 0 | Theoretical and Fundamental Chemistry |
Sometimes, the potential or real toxicity of the compound is taken into account (ADME-Tox or ADMET). Parameters used to characterize toxicity include the median lethal dose (LD) and therapeutic index.
Computational chemists try to predict the ADME-Tox qualities of compounds through methods like QSPR or QSAR.
The route of administration critically influences ADME. | 1 | Applied and Interdisciplinary Chemistry |
Self-assembly is the most common term in use in the modern scientific community to describe the spontaneous aggregation of particles (atoms, molecules, colloids, micelles, etc.) without the influence of any external forces. Large groups of such particles are known to assemble themselves into thermodynamically stable, structurally well-defined arrays, quite reminiscent of one of the seven crystal systems found in metallurgy and mineralogy (e.g., face-centered cubic, body-centered cubic, etc.). The fundamental difference in equilibrium structure is in the spatial scale of the unit cell (lattice parameter) in each particular case.
Molecular self assembly is found widely in biological systems and provides the basis of a wide variety of complex biological structures. This includes an emerging class of mechanically superior biomaterials based on microstructural features and designs found in nature. Thus, self-assembly is also emerging as a new strategy in chemical synthesis and nanotechnology. Molecular crystals, liquid crystals, colloids, micelles, emulsions, phase-separated polymers, thin films and self-assembled monolayers all represent examples of the types of highly ordered structures, which are obtained using these techniques. The distinguishing feature of these methods is self-organization. | 1 | Applied and Interdisciplinary Chemistry |
The equilibrium of two molecular conformations is determined by the difference in Gibbs free energy of the two conformations. From this energy difference, the equilibrium constant for the two conformations can be determined.
If there is a decrease in Gibbs free energy from one state to another, this transformation is spontaneous and the lower energy state is more stable. A highly strained, higher energy molecular conformation will spontaneously convert to the lower energy molecular conformation.
Enthalpy and entropy are related to Gibbs free energy through the equation (at a constant temperature):
Enthalpy is typically the more important thermodynamic function for determining a more stable molecular conformation. While there are different types of strain, the strain energy associated with all of them is due to the weakening of bonds within the molecule. Since enthalpy is usually more important, entropy can often be ignored. This isn't always the case; if the difference in enthalpy is small, entropy can have a larger effect on the equilibrium. For example, n-butane has two possible conformations, anti and gauche. The anti conformation is more stable by 0.9 kcal mol. We would expect that butane is roughly 82% anti and 18% gauche at room temperature. However, there are two possible gauche conformations and only one anti conformation. Therefore, entropy makes a contribution of 0.4 kcal in favor of the gauche conformation. We find that the actual conformational distribution of butane is 70% anti and 30% gauche at room temperature. | 0 | Theoretical and Fundamental Chemistry |
* A configurational stereoisomer is a stereoisomer of a reference molecule that has the opposite configuration at a stereocenter (e.g., R- vs S- or E- vs Z-). This means that configurational isomers can be interconverted only by breaking covalent bonds to the stereocenter, for example, by inverting the configurations of some or all of the stereocenters in a compound.
* An epimer is a diastereoisomer that has the opposite configuration at only one of the stereocenters. | 0 | Theoretical and Fundamental Chemistry |
The Sleeping Beauty (SB) transposase is the recombinase that drives the Sleeping Beauty transposon system. SB transposase belongs to the DD[E/D] family of transposases, which in turn belong to a large superfamily of polynucleotidyl transferases that includes RNase H, RuvC Holliday resolvase, RAG proteins, and retroviral integrases. The SB system is used primarily in vertebrate animals for gene transfer, including gene therapy, and gene discovery. The engineered SB100X is an enzyme that directs the high levels of transposon integration. | 1 | Applied and Interdisciplinary Chemistry |
Thermal radiation can be concentrated on a tiny spot via reflecting mirrors, which concentrating solar power takes advantage of. Instead of mirrors, Fresnel lenses can also be used to concentrate radiant energy. In principle, any kind of lens can be used, but only the Fresnel lens design is practical for very large lenses. Either method can be used to quickly vaporize water into steam using sunlight. For example, the sunlight reflected from mirrors heats the PS10 Solar Power Plant, and during the day it can heat water to . | 0 | Theoretical and Fundamental Chemistry |
There are also many other descriptive terms, often with very specialized usage and confined to specific taxonomic groups. The conspicuousness of veins depends on a number of features. These include the width of the veins, their prominence in relation to the lamina surface and the degree of opacity of the surface, which may hide finer veins. In this regard, veins are called obscure and the order of veins that are obscured and whether upper, lower or both surfaces, further specified.
Terms that describe vein prominence include bullate, channelled, flat, guttered, impressed, prominent and recessed (Fig. 6.1 Hawthorne & Lawrence 2013). Veins may show different types of prominence in different areas of the leaf. For instance Pimenta racemosa has a channelled midrib on the upper surface, but this is prominent on the lower surface.
Describing vein prominence:
;Bullate: Surface of leaf raised in a series of domes between the veins on the upper surface, and therefore also with marked depressions. e.g. Rytigynia pauciflora, Vitis vinifera
;Channelled (canalicululate): Veins sunken below the surface, resulting in a rounded channel. Sometimes confused with "guttered" because the channels may function as gutters for rain to run off and allow drying, as in many Melastomataceae. e.g. (see) Pimenta racemosa (Myrtaceae), Clidemia hirta (Melastomataceae).
;Guttered: Veins partly prominent, the crest above the leaf lamina surface, but with channels running along each side, like gutters
;Impressed: Vein forming raised line or ridge which lies below the plane of the surface which bears it, as if pressed into it, and are often exposed on the lower surface. Tissue near the veins often appears to pucker, giving them a sunken or embossed appearance
;Obscure: Veins not visible, or not at all clear; if unspecified, then not visible with the naked eye. e.g. Berberis gagnepainii. In this Berberis, the veins are only obscure on the undersurface.
;Prominent: Vein raised above surrounding surface so to be easily felt when stroked with finger. e.g. (see) Pimenta racemosa, Spathiphyllum cannifolium
;Recessed: Vein is sunk below the surface, more prominent than surrounding tissues but more sunken in channel than with impressed veins. e.g. Viburnum plicatum.
Describing other features:
;Plinervy (plinerved): More than one main vein (nerve) at the base. Lateral secondary veins branching from a point above the base of the leaf. Usually expressed as a suffix, as in 3-plinerved or triplinerved leaf. In a 3-plinerved (triplinerved) leaf three main veins branch above the base of the lamina (two secondary veins and the main vein) and run essentially parallel subsequently, as in Ceanothus and in Celtis. Similarly, a quintuplinerve (five-veined) leaf has four secondary veins and a main vein. A pattern with 3–7 veins is especially conspicuous in Melastomataceae. The term has also been used in Vaccinieae. The term has been used as synonymous with acrodromous, palmate-acrodromous or suprabasal acrodromous, and is thought to be too broadly defined.
;Scalariform: Veins arranged like the rungs of a ladder, particularly higher order veins
;Submarginal: Veins running close to leaf margin
;Trinerved: 2 major basal nerves besides the midrib | 0 | Theoretical and Fundamental Chemistry |
In order to specify the different harmonic components of the tide-generating potential, Doodson devised a practical system which is still in use, involving what are called the Doodson numbers based on the six Doodson arguments or Doodson variables. The number of different tidal frequency components is large, but each corresponds to a specific linear combination of six frequencies using small-integer multiples, positive or negative. In principle, these basic angular arguments can be specified in numerous ways; Doodson's choice of his six "Doodson arguments" has been widely used in tidal work. In terms of these Doodson arguments, each tidal frequency can then be specified as a sum made up of a small integer multiple of each of the six arguments. The resulting six small integer multipliers effectively encode the frequency of the tidal argument concerned, and these are the Doodson numbers: in practice all except the first are usually biased upwards by +5 to avoid negative numbers in the notation. (In the case that the biased multiple exceeds 9, the system adopts X for 10, and E for 11.)
The Doodson arguments are specified in the following way, in order of decreasing frequency:
: is mean Lunar time, the Greenwich hour angle of the mean Moon plus 12 hours.
: is the mean longitude of the Moon.
: is the mean longitude of the Sun.
: is the longitude of the Moon's mean perigee.
: is the negative of the longitude of the Moons mean ascending node on the ecliptic.
: or is the longitude of the Suns mean perigee.
In these expressions, the symbols , , and refer to an alternative set of fundamental angular arguments (usually preferred for use in modern lunar theory), in which:-
: is the mean anomaly of the Moon (distance from its perigee).
: is the mean anomaly of the Sun (distance from its perigee).
: is the Moon's mean argument of latitude (distance from its node).
: is the Moon's mean elongation (distance from the sun).
It is possible to define several auxiliary variables on the basis of combinations of these.
In terms of this system, each tidal constituent frequency can be identified by its Doodson numbers. The strongest tidal constituent "M" has a frequency of 2 cycles per lunar day, its Doodson numbers are usually written 255.555, meaning that its frequency is composed of twice the first Doodson argument, and zero times all of the others. The second strongest tidal constituent "S" is influenced by the sun, and its Doodson numbers are 273.555, meaning that its frequency is composed of twice the first Doodson argument, +2 times the second, -2 times the third, and zero times each of the other three. This aggregates to the angular equivalent of mean solar time +12 hours. These two strongest component frequencies have simple arguments for which the Doodson system might appear needlessly complex, but each of the hundreds of other component frequencies can be briefly specified in a similar way, showing in the aggregate the usefulness of the encoding. | 1 | Applied and Interdisciplinary Chemistry |
Poly(pentafluorophenyl acrylate) (variously abbreviated PPFPA, PolyPFPA, PPfpA, or PolyPfpA) is a highly fluorinated polymer. It features the pentafluorophenyl ester functionality, from which its properties and applications result. It is most commonly used in post-polymerization modification to synthesize functional polyacrylamides or polyacrylates. As such, it is advantageous to poly(N-acryloyl succinimide) due to its broader solubility in organic solvents as well as its higher stability towards hydrolysis. | 0 | Theoretical and Fundamental Chemistry |
PET scans are increasingly read alongside CT or MRI scans, with the combination (co-registration) giving both anatomic and metabolic information (i.e., what the structure is, and what it is doing biochemically). Because PET imaging is most useful in combination with anatomical imaging, such as CT, modern PET scanners are now available with integrated high-end multi-detector-row CT scanners (PET-CT). Because the two scans can be performed in immediate sequence during the same session, with the patient not changing position between the two types of scans, the two sets of images are more precisely registered, so that areas of abnormality on the PET imaging can be more perfectly correlated with anatomy on the CT images. This is very useful in showing detailed views of moving organs or structures with higher anatomical variation, which is more common outside the brain.
At the Jülich Institute of Neurosciences and Biophysics, the world's largest PET-MRI device began operation in April 2009. A 9.4-tesla magnetic resonance tomograph (MRT) combined with a PET. Presently, only the head and brain can be imaged at these high magnetic field strengths.
For brain imaging, registration of CT, MRI and PET scans may be accomplished without the need for an integrated PET-CT or PET-MRI scanner by using a device known as the N-localizer. | 1 | Applied and Interdisciplinary Chemistry |
When encapsulating hydrophobic or potentially toxic materials it is important that the encapsulant remain intact while inside the body. Studying the rheological properties of the micelles permits identification and selection of the polymer that is most appropriate for use in long-term biological applications. R-PEG exhibits superior rheological properties when used in vivo. | 0 | Theoretical and Fundamental Chemistry |
Kinetic studies show that malate dehydrogenase enzymatic activity is ordered. The cofactor NAD/NADH is bound to the enzyme before the substrate. The Km value for malate, i.e., the concentration at which the enzyme activity is half-maximal, is 2 mM. The Kcat value is 259.2 s. | 1 | Applied and Interdisciplinary Chemistry |
Espín was married to Raúl Castro, the former First Secretary of the Communist Party of Cuba, who is the brother to former First Secretary Fidel Castro. Their wedding took place in 1959, only weeks after the 26th of July Movement had successfully overthrown dictator Fulgencio Batista. She had four children (Deborah, Mariela, Nilsa, and Alejandro Castro Espín) and eight grandchildren. Her daughter, Mariela Castro, currently heads the Cuban National Center for Sex Education, and her son, Alejandro Castro Espín, is a Colonel in the Ministry of Interior. | 1 | Applied and Interdisciplinary Chemistry |
Chiral acyclic alkenes also show diastereoselectivity upon reactions such as epoxidation and enolate alkylation. The substituents around the alkene can favour the approach of the electrophile from one or the other face of the molecule. This is the basis of the Houks model, based on theoretical work by Kendall Houk, which predicts that the selectivity is stronger for cis than for trans' double bonds.
In the example shown, the cis alkene assumes the shown conformation to minimize steric clash between R and the methyl group. The approach of the electrophile preferentially occurs from the same side of the medium group (R) rather than the large group (R), mainly producing the shown diastereoisomer. Since for a trans alkene the steric hindrance between R and the H group is not as large as for the cis case, the selectivity is much lower. | 0 | Theoretical and Fundamental Chemistry |
Benzenesulfonyl chloride is an organosulfur compound with the formula CHSOCl. It is a colourless viscous oil that dissolves in organic solvents, but reacts with compounds containing reactive N-H and O-H bonds. It is mainly used to prepare sulfonamides and sulfonate esters by reactions with amines and alcohols, respectively. The closely related compound toluenesulfonyl chloride is often preferred analogue because it is a solid at room temperature and easier to handle.
The compound is prepared by the chlorination of benzenesulfonic acid or its salts with phosphorus oxychloride or, less commonly, by a reaction between benzene and chlorosulfuric acid.
The Hinsberg test for amines involves their reaction with benzenesulfonyl chloride. | 0 | Theoretical and Fundamental Chemistry |
Production of crude steel has risen at an astounding rate, reaching 1.691 billion tonnes by 2017
During the 20th century, the consumption of steel increased at an average annual rate of 3.3%. In 1900, the United States was producing 37% of the world's steel, but with post war industrial development in Asia and centralised investment by China, by 2017 China alone accounted for 50%, with Europe (including the former Soviet Union) down to 24% and North America down to 6%.
For details of country-wise steel production see steel production by country. | 1 | Applied and Interdisciplinary Chemistry |
Besides de novo synthesis, PA can be formed in three ways:
* By phospholipase D (PLD), via the hydrolysis of the P-O bond of phosphatidylcholine (PC) to produce PA and choline.
* By the phosphorylation of diacylglycerol (DAG) by DAG kinase (DAGK).
* By the acylation of lysophosphatidic acid by lysoPA-acyltransferase (LPAAT); this is the most common pathway.
The glycerol 3-phosphate pathway for de novo synthesis of PA is shown here:
In addition, PA can be converted into DAG by lipid phosphate phosphohydrolases (LPPs) or into lyso-PA by phospholipase A (PLA). | 1 | Applied and Interdisciplinary Chemistry |
Several lines of evidence suggest that intelectins recognize microbes and may function as an innate immune defense protein. Tunicate intelectin is an opsonin for phagocytosis by hemocyte. Amphioxus intelectin has been shown to agglutinate bacteria. In zebrafish and rainbow trout, intelectin expression is stimulated upon microbial exposure. Mammals such as sheep and mice also upregulate intelectin expression upon parasitic infection. Increase in intelectin expression upon microbial exposure support the hypothesis that intelectins play a role in the immune system. | 1 | Applied and Interdisciplinary Chemistry |
The limiting equivalent conductivity of solutions based on mixed solvents like water alcohol has minima depending on the nature of alcohol. For methanol the minimum is at 15 molar % water, and for the ethanol at 6 molar % water. | 0 | Theoretical and Fundamental Chemistry |
The most common method for cantilever-deflection measurements is the beam-deflection method. In this method, laser light from a solid-state diode is reflected off the back of the cantilever and collected by a position-sensitive detector (PSD) consisting of two closely spaced photodiodes, whose output signal is collected by a differential amplifier.
Angular displacement of the cantilever results in one photodiode collecting more light than the other photodiode, producing an output signal (the difference between the photodiode signals normalized by their sum), which is proportional to the deflection of the cantilever. The sensitivity of the beam-deflection method is very high, and a noise floor on the order of 10 fm Hz can be obtained routinely in a well-designed system. Although this method is sometimes called the "optical lever" method, the signal is not amplified if the beam path is made longer. A longer beam path increases the motion of the reflected spot on the photodiodes, but also widens the spot by the same amount due to diffraction, so that the same amount of optical power is moved from one photodiode to the other. The "optical leverage" (output signal of the detector divided by deflection of the cantilever) is inversely proportional to the numerical aperture of the beam focusing optics, as long as the focused laser spot is small enough to fall completely on the cantilever. It is also inversely proportional to the length of the cantilever.
The relative popularity of the beam-deflection method can be explained by its high sensitivity and simple operation, and by the fact that cantilevers do not require electrical contacts or other special treatments, and can therefore be fabricated relatively cheaply with sharp integrated tips. | 0 | Theoretical and Fundamental Chemistry |
Several important measures are used to characterize solar cells. The most obvious is the total amount of electrical power produced for a given amount of solar power shining on the cell. Expressed as a percentage, this is known as the solar conversion efficiency. Electrical power is the product of current and voltage, so the maximum values for these measurements are important as well, J and V respectively. Finally, in order to understand the underlying physics, the "quantum efficiency" is used to compare the chance that one photon (of a particular energy) will create one electron.
In quantum efficiency terms, DSSCs are extremely efficient. Due to their "depth" in the nanostructure there is a very high chance that a photon will be absorbed, and the dyes are very effective at converting them to electrons. Most of the small losses that do exist in DSSC's are due to conduction losses in the TiO and the clear electrode, or optical losses in the front electrode. The overall quantum efficiency for green light is about 90%, with the "lost" 10% being largely accounted for by the optical losses in the top electrode. The quantum efficiency of traditional designs vary, depending on their thickness, but are about the same as the DSSC.
In theory, the maximum voltage generated by such a cell is simply the difference between the (quasi-)Fermi level of the TiO and the redox potential of the electrolyte, about 0.7 V under solar illumination conditions (V). That is, if an illuminated DSSC is connected to a voltmeter in an "open circuit", it would read about 0.7 V. In terms of voltage, DSSCs offer slightly higher V than silicon, about 0.7 V compared to 0.6 V. This is a fairly small difference, so real-world differences are dominated by current production, J.
Although the dye is highly efficient at converting absorbed photons into free electrons in the TiO, only photons absorbed by the dye ultimately produce current. The rate of photon absorption depends upon the absorption spectrum of the sensitized TiO layer and upon the solar flux spectrum. The overlap between these two spectra determines the maximum possible photocurrent. Typically used dye molecules generally have poorer absorption in the red part of the spectrum compared to silicon, which means that fewer of the photons in sunlight are usable for current generation. These factors limit the current generated by a DSSC, for comparison, a traditional silicon-based solar cell offers about 35 mA/cm, whereas current DSSCs offer about 20 mA/cm.
Overall peak power conversion efficiency for current DSSCs is about 11%. Current record for prototypes lies at 15%. | 0 | Theoretical and Fundamental Chemistry |
Base calling can be assessed by two metrics, read accuracy and consensus accuracy. Read accuracy refers to the called base's accuracy to a known reference. Consensus accuracy refers to how accurate a consensus sequence is compared to overlapping reads from the same genetic locus. | 1 | Applied and Interdisciplinary Chemistry |
Lillie's trichrome is a combination of dyes used in histology.
It is similar to Massons trichrome stain, but it uses Biebrich scarlet for the plasma stain. It was initially published by Ralph D. Lillie in 1940. It is applied by submerging the fixated sample into the following three solutions: Weigerts iron hematoxylin working solution, Biebrich scarlet solution, and Fast Green FCF solution.
The resulting stains are black cell nuclei, brown cytoplasm, red muscle and myelinated fibers, blue collagen, and scarlet erythrocytes. | 1 | Applied and Interdisciplinary Chemistry |
Overdose symptoms can be confusion, hypotension, and tachycardia, and several fatalities have been reported with concentrations in postmortem blood ranging from 0.1 to 7.0 mg/L compared to non-toxic levels in postmortem blood which can extend to 0.4 mg/kg. | 0 | Theoretical and Fundamental Chemistry |
Amorphous solids in general have a unique magnetic property because of their atomic disorder as explained above. They are rather soft metals and each has its own specific magnetic property depending on the means of production. In the splat quenching process, the metals are very soft and have superparamagnetic properties or shifting polarity behavior caused by the rapid and intense heat transfer. | 1 | Applied and Interdisciplinary Chemistry |
The antibiotic is produced under many brand names across the world.
* Bangladesh: Ancef, Ancef forte, Aphrin, Avlosef, Cefadin, Cephadin, Cephran, Cephran-DS, Cusef, Cusef DS, Dicef , Dicef forte, Dolocef, Efrad, Elocef, Extracef, Extracef-DS, Intracef, Kefdrin, Lebac, Lebac Forte, Medicef, Mega-Cef, Megacin, Polycef, Procef, Procef, Procef forte, Rocef, Rocef Forte DS, Sefin, Sefin DS, Sefnin, Sefrad, Sefrad DS, Sefril, Sefril-DS, Sefro, Sefro-HS, Sephar, Sephar-DS, Septa, Sinaceph, SK-Cef, Sk-Cef DS, Supracef and Supracef-F, Torped, Ultrasef, Vecef, Vecef-DS, Velogen, Sinaceph, Velox
* China: Cefradine, Cephradine, Kebili, Saifuding, Shen You, Taididing, Velosef, Xianyi, and Xindadelei
* Colombia: Cefagram, Cefrakov, Cefranil , Cefrex, and Kliacef
* Egypt: Cefadrin, Cefadrine, Cephradine, Cephraforte, Farcosef, Fortecef, Mepadrin, Ultracef, and Velosef
* France: Dexef
* Hong Kong: Cefradine and ChinaQualisef-250
* Indonesia: Dynacef, Velodine, and Velodrom
* Lebanon: Eskacef, Julphacef, and Velosef
* Lithuania: Tafril
* Myanmar: Sinaceph
* Oman: Ceframed, Eskasef, Omadine, and Velocef
* Pakistan: Abidine, Ada-Cef, Ag-cef, Aksosef, Amspor, Anasef, Antimic, Atcosef, Bactocef, Biocef, Biodine, Velora, Velosef
* Peru: Abiocef, Cefradinal, Cefradur, Cefrid, Terbodina II, Velocef, Velomicin
* Philippines: Altozef, Racep, Senadex, Solphride, Yudinef, Zefadin, Zefradil, and Zolicef
* Poland: Tafril
* Portugal: Cefalmin, Cefradur
* South Africa: Cefril A
* South Korea: Cefradine and Tricef
* Taiwan: Cefadin, Cefamid, Cefin, Cekodin, Cephradine, Ceponin, Lacef, Licef-A, Lisacef, Lofadine, Recef, S-60, Sefree, Sephros, Topcef, Tydine, Unifradine, and U-Save
* UK: Cefradune (Kent)
* Vietnam: Eurosefro and Incef | 0 | Theoretical and Fundamental Chemistry |
When photon energies are as high as the electron rest energy of , yet another process, Compton scattering, may occur. Above twice this energy, at , pair production is also more likely. Compton scattering and pair production are examples of two other competing mechanisms.
Even if the photoelectric effect is the favoured reaction for a particular interaction of a single photon with a bound electron, the result is also subject to quantum statistics and is not guaranteed. The probability of the photoelectric effect occurring is measured by the cross section of the interaction, σ. This has been found to be a function of the atomic number of the target atom and photon energy. In a crude approximation, for photon energies above the highest atomic binding energy, the cross section is given by:
Here Z is the atomic number and n is a number which varies between 4 and 5. The photoelectric effect rapidly decreases in significance in the gamma-ray region of the spectrum, with increasing photon energy. It is also more likely from elements with high atomic number. Consequently, high-Z materials make good gamma-ray shields, which is the principal reason why lead (Z = 82) is preferred and most widely used. | 0 | Theoretical and Fundamental Chemistry |
Commercially made Geiger counters are expensive and require frequent calibration. It is possible to construct an electrometer-type radiation meter called the Kearny fallout meter, which does not require batteries or professional calibration, from properly-scaled plans with just a coffee can or pail, gypsum board, monofilament fishing line, and aluminum foil. Plans are freely available in the public domain in the reference Nuclear War Survival Skills by Cresson Kearny. | 0 | Theoretical and Fundamental Chemistry |
The case of a vertical line absorbing at a fixed rate a constant quantity of fluid Q per unit length is a line sink. Everything is the same as the case of a line source a part from the negative sign.
This is derived from a stream function
or from a potential function
Given that the two results are the same a part from a minus sign we can treat transparently both line sources and line sinks with the same stream and potential functions permitting Q to assume both positive and negative values and absorbing the minus sign into the definition of Q. | 1 | Applied and Interdisciplinary Chemistry |
As mentioned in the introduction, -photo-leucine is a synthetic derivative of the -Leucine amino acid. -photo-leucine is characterized by the presence of a diazirine ring linked to the R radical of the original amino acid. This cyclopropene ring-shaped molecule is constituted of a carbon atom attached to two nitrogen atoms through a covalent single bond. These two nitrogen atoms are simultaneously connected to each other by a double covalent bond. The diazirine carbon is located in the position where theoretically the 2nd carbon atom of the R radical of -leucine would be, linked up with the 1st and 3rd carbon of this theoretical R radical.
The diazirine ring confers to the photo-leucine its photoreactive property. When irradiated with UV light, it splits releasing nitrogen in gas form and leaving an unbound carbon atom (see Diazirine). In protein-protein interactions (PPI), this atom is attached to the complex formed by the two proteins susceptible of being under study.
The rest of the amino acid has indeed the same structure as the original -leucine molecule, which includes, as every amino acid, an amino group and a carboxyl group bonded to an α-carbon, and a radical that is attached to this carbon atom. The R chain, contains, in this case, a diazirine ring and two extra carbon atoms connected each to the diazirine carbon as it has been previously mentioned.
For use in biology experiments, only the -enantiomer of the photo-leucine amino acid is synthesized, so that it can substitute for natural -leucine. (Natural proteins consist only of -amino acids; see homochirality.) | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry. | 0 | Theoretical and Fundamental Chemistry |
It is used as a pH indicator and as a tracking dye for DNA agarose gel electrophoresis. It can be used in its free acid form (light brown solid), or as a sodium salt (dark green solid). It is also an inhibitor of the prostaglandin E transport protein. Additional applications include use in sol-gel matrices, the detection of ammonia, and the measurement of albumin in human plasma and serum. | 0 | Theoretical and Fundamental Chemistry |
Trans-acting factors can be categorized by their interactions with the regulated genes, cis-acting elements of the genes, or the gene products. | 1 | Applied and Interdisciplinary Chemistry |
The more comprehensive approach to assessment of ion suppression is to constantly infuse an appropriate concentration into the mobile phase flow, downstream from the analytical column, using a syringe pump and a tee union. A typical sample should then be injected through the HPLC inlet as per the usual analytical parameters.
Monitoring of detector response during this experiment should yield a constant signal appropriate to the concentration of infused species. Once the sample has been injected, a drop in signal intensity (or a negative response) should be observed any time a species is ionised in the ion source. This should allow the retention time of any such species under the analytical parameters of the assay to be determined. Any species causing a negative response may be considered to be contributing to ion suppression, but only if such species co-elute with the analyte of interest.
It is also important to consider that species contributing to ion suppression may be retained by the column to a much greater extent than the analyte of interest. To this end, the detector response should be monitored for several times the usual chromatographic run time to ensure that ion suppression will not affect subsequent injections. | 0 | Theoretical and Fundamental Chemistry |
Several authors have reported the existence of supramultiplicative behavior in signaling cascades (i.e. the ultrasensitivity of the combination of layers is higher than the product of individual ultrasensitivities), but in many cases the ultimate origin of supramultiplicativity remained elusive. Altszyler et al. (2017) framework naturally suggested a general scenario where supramultiplicative behavior could take place. This could occur when, for a given module, the corresponding Hill's input working range was located in an input region with local ultrasensitivities higher than the global ultrasensitivity of the respective dose-response curve. | 1 | Applied and Interdisciplinary Chemistry |
Perey received a grant to study at Paris Sorbonne, but because she didnt have a bachelor's degree, the Sorbonne required her to take courses and obtain the equivalent of a B.S. to fulfill their PhD program requirements before she could earn her doctorate. She graduated from the Sorbonne in 1946 with a Doctorate of Physics. After obtaining her PhD, Perey returned to the Radium Institute as a senior scientist and worked there until 1949.
Perey was made the head of the department of nuclear chemistry at the University of Strasbourg in 1949, where she developed the university's radiochemistry and nuclear chemistry program and continued her work on francium. She founded a laboratory that in 1958 became the Laboratory of Nuclear Chemistry in the Center for Nuclear Research, for which she served as director. She also served as a member of the Atomic Weights Commission from 1950 to 1963.
Because of her work with francium, Perey was nominated five times for a Nobel Prize, but she never received it.
Ironically, Perey hoped that francium would help diagnose cancer, but in fact it itself was carcinogenic, and Perey developed bone cancer which eventually killed her. Perey died on 13 May 1975 (age 65). She is credited with championing better safety measures for scientists working with radiation. | 1 | Applied and Interdisciplinary Chemistry |
Figure 3 shows the line of contact where three phases meet. In equilibrium, the net force per unit length acting along the boundary line between the three phases must be zero. The components of net force in the direction along each of the interfaces are given by:
where α, β, and θ are the angles shown and γ is the surface energy between the two indicated phases. These relations can also be expressed by an analog to a triangle known as Neumann’s triangle, shown in Figure 4. Neumann’s triangle is consistent with the geometrical restriction that , and applying the law of sines and law of cosines to it produce relations that describe how the interfacial angles depend on the ratios of surface energies.
Because these three surface energies form the sides of a triangle, they are constrained by the triangle inequalities, γ + γ meaning that no one of the surface tensions can exceed the sum of the other two. If three fluids with surface energies that do not follow these inequalities are brought into contact, no equilibrium configuration consistent with Figure 3 will exist. | 0 | Theoretical and Fundamental Chemistry |
As with all non-lethal or less-lethal weapons, there is a risk of serious permanent injury or death when tear gas is used. This includes risks from being hit by tear gas cartridges that may cause severe bruising, loss of eyesight, or skull fracture, resulting in immediate death. A case of serious vascular injury from tear gas shells has also been reported from Iran, with high rates of associated nerve injury (44%) and amputation (17%), as well as instances of head injuries in young people. Novel findings suggest that menstrual changes are one of the most commonly reported health issues in women.
While the medical consequences of the gases themselves are typically limited to minor skin inflammation, delayed complications are also possible. People with pre-existing respiratory conditions such as asthma are particularly at risk. They are likely to need medical attention and may sometimes require hospitalization or even ventilation support. Skin exposure to CS may cause chemical burns or induce allergic contact dermatitis. When people are hit at close range or are severely exposed, eye injuries involving scarring of the cornea can lead to a permanent loss in visual acuity. Frequent or high levels of exposure carry increased risks of respiratory illness.
Venezuelan chemist Mónica Kräuter studied thousands of tear gas canisters fired by Venezuelan authorities since 2014. She concluded that the majority of canisters used the main component CS gas, but that 72% of the tear gas used was expired. She noted that expired tear gas "breaks down into cyanide oxide, phosgenes and nitrogens that are extremely dangerous".
In the 2019–20 Chilean protests various people have had complete and permanent loss of vision in one or both eyes as result of the impact of tear gas grenades.
The majority (2116; 93.8%) of protestors who reported exposure to tear gas during the 2020 protests in Portland, Oregon (USA) reported physical (2114; 93.7%) or psychological (1635; 72.4%) health issues experienced immediately after (2105; 93.3%) or days following (1944; 86.1%) the exposure. The majority (1233; 54.6%) of respondents who reported exposure to tear gas during the 2020 protests in Portland, Oregon (USA) have also reported receiving or planning to seek medical or mental healthcare for their tear gas-related health issues. It has been shown that health issues associated with the exposure to tear gas are often require medical attention. | 1 | Applied and Interdisciplinary Chemistry |
Corrosion in Ballast Tanks is the deterioration process where the surface of a ballast tank progresses from microblistering, to hydroscaletric electration, and finally to cracking of the tank steel itself.
::“Effective corrosion control in segregated water ballast spaces is probably the single most important feature, next to the integrity of the initial design, in determining the ship’s effective life span and structural reliability,” said Alan Gavin, Germanischer Lloyd's Principal surveyor.
Throughout the years the merchant fleet has become increasingly aware of the importance of avoiding corrosion in ballast tanks. | 1 | Applied and Interdisciplinary Chemistry |
Environmental engineering law professionals offer a sound knowledge base in the fields of both environmental engineering and law to address complex environmental problems which demand both professional technical practice and legal expertise. Areas of practice are continually expanding, but frequently include complex land transactions, such as:
*Brownfields redevelopment
*Asbestos baseline survey and building revaluation due to forthcoming asbestos abatements
*Soil contamination assessment & remediation, the development of a remedial action workplan (RAWP) and engineering controls, including an environmental land use restriction (ELUR)
*Total maximum daily load (TMDL) nutrient loading studies (ex. for NPDES wastewater discharges) and regulatory negotiation of nutrients discharge limits from waste treatment plants, such as phosphorus and nitrogen. | 1 | Applied and Interdisciplinary Chemistry |
Americium-241, an alpha emitter, is used in smoke detectors. The alpha particles ionize air in an open ion chamber and a small current flows through the ionized air. Smoke particles from the fire that enter the chamber reduce the current, triggering the smoke detector's alarm.
Radium-223 is also an alpha emitter. It is used in the treatment of skeletal metastases (cancers in the bones).
Alpha decay can provide a safe power source for radioisotope thermoelectric generators used for space probes and were used for artificial heart pacemakers. Alpha decay is much more easily shielded against than other forms of radioactive decay.
Static eliminators typically use polonium-210, an alpha emitter, to ionize the air, allowing the "static cling" to dissipate more rapidly. | 0 | Theoretical and Fundamental Chemistry |
Pre-computed results for biological assemblies
For a lot of proteins deposited in Protein Data Bank, the asymmetric unit might be different from biological unit, which would make the computational result biologically irrelevant. So the new CASTp 3.0 computed the topological features for biological assemblies, overcome the barriers between asymmetric unit and biological assemblies.
Imprints of negative volumes of topological features
In the 1st release of CASTp server in 2006, only geometric and topological features of those surface atoms participated in the formation of protein pockets, cavities, and channels. The new CASTp added the "negative volume" of the space, referred to the space encompassed by the atoms formed these geometric and topological features.
Comprehensive annotation on single amino-acid polymorphism
The latest CASTp integrated protein annotations aligned with the sequence, including the brief feature, positions, description, and reference of the domains, motifs, and single amino-acid polymorphisms.
Improved user interface & convenient visualization
The new CASTp now incorporated 3Dmol.js for structural visualization, made users able to browse, to interact the protein 3D model, and to examine the computational results in latest web-browsers including Chrome, Firefox, Safari, et al. Users can pick their own representation style of the atoms which form each topographic feature, and to edit the colors by their own preferences. | 1 | Applied and Interdisciplinary Chemistry |
There are two major classes of Neuraminidase that cleave exo or endo poly-sialic acids:
* Exo hydrolysis of α-(2→3)-, α-(2→6)-, α-(2→8)-glycosidic linkages of terminal sialic acid residues
* Endo hydrolysis of (2→8)-α-sialosyl linkages in oligo- or poly(sialic) acids (see endo-α-sialidase.) | 0 | Theoretical and Fundamental Chemistry |
There are many software tools for pharmaceutical bioinformatics. An example of an open source tool is the Bioclipse workbench. | 1 | Applied and Interdisciplinary Chemistry |
Dioxiranes oxidize a wide variety of functional groups. This section describes the substrate scope of dioxirane epoxidation and the products that most commonly result.
Oxidations of alkynes, allenes, arenes, and other unique unsaturated functionality may yield epoxides or other oxidized products. Oxidation of allenes affords allene dioxides or products of intramolecular participation. Minor amounts of side products derived from additional oxidation or rearrangement were also observed.
In oxidations of heteroaromatic compounds, the products obtained depend on reaction conditions. Thus, at low temperatures, acetylated indoles are simply epoxidized in high yield (unprotected indoles undergo N-oxidation). However, when the temperature is raised to 0 °C, rearranged products are obtained.
DMD may oxidize heteroatoms to the corresponding oxides (or products of oxide decomposition). Often, the results of these oxidations depend on reaction conditions. Tertiary amines cleanly give the corresponding N-oxides. Primary amines give nitroalkanes upon treatment with 4 equivalents of DMD, but azoxy compounds upon treatment with only 2 equivalents. Secondary amines afford either hydroxylamines or nitrones.
Oxidation of nitronate anions, generated in situ from nitroalkanes, leads to carbonyl compounds in an example of an oxidative Nef reaction.
Sulfide oxidation in the presence of a single equivalent of DMD leads to sulfoxides. Increasing the amount of DMD used (2 or more equivalents) leads to sulfones. Both nitrogen and sulfur are more susceptible to oxidation than carbon-carbon multiple bonds.
Although alkanes are typically difficult to functionalize directly, C-H insertion with TFD is an efficient process in many cases. The order of reactivity of C-H bonds is: allylic > benzylic > tertiary > secondary > primary. Often, the intermediate alcohols produced are oxidized further to carbonyl compounds, although this can be prevented by trapping in situ with an anhydride. Chiral alkanes are functionalized with retention of configuration.
Dioxiranes oxidize primary alcohols to either the aldehyde or carboxylic acid; however, DMD selectively oxidizes secondary over primary alcohols. Thus, vicinal diols may be transformed into α-hydroxy ketones with dioxirane oxidation.
Epoxidation is usually more facile than C-H oxidation, although sterically hindered allyl groups may undergo selective C-H oxidation instead of epoxidation of the allylic double bond. | 0 | Theoretical and Fundamental Chemistry |
The alarm photosynthesis process was first evidenced in pigweed Amaranthus hybridus plant in 2016 when A. hybridus leaves were exposed to drought conditions or exogenous application of abscisic acid. The same study showed similar results in Dianthus chinensis, Pelargonium peltatum, and Portulacaria afra plants under drought stress. In 2018, the alarm photosynthesis process was exhibited in A. hybridus plants under controlled CO starvation conditions. In 2020, evidence of this process was shown in the Antarctic extremophile plant Colobanthus quitensis under CO limiting conditions. | 0 | Theoretical and Fundamental Chemistry |
PAMPs, conserved molecules that inhabit multiple pathogen genera, are referred to as MAMPs by many researchers. The defenses induced by MAMP perception are sufficient to repel most pathogens. However, pathogen effector proteins (see below) are adapted to suppress basal defenses such as PTI. Many receptors for MAMPs (and DAMPs) have been discovered. MAMPs and DAMPs are often detected by transmembrane receptor-kinases that carry LRR or LysM extracellular domains. | 1 | Applied and Interdisciplinary Chemistry |
Epic-seq hypothesizes that cfDNA fragments originating from active promoters, which are less shielded by nucleosomes and thus more susceptible to endonuclease cleavage, will display more erratic cleavage patterns compared to fragments from inactive promoters, which are better protected by nucleosomes. PFE is a variation of the Shannon Index, which is a quantitative measure for estimating diversity. In the context of Epic-seq, PFE calculates the diversity of cfDNA fragment lengths where both ends of the fragment are situated within the 2 kb flanking region of each genes TSS. The higher the PFE of a genes TSS, the more likely the gene is highly expressed. | 1 | Applied and Interdisciplinary Chemistry |
Gene symbols are italicised, with all letters in lowercase (shh). Protein designations are the same as the gene symbol, but are not italicised; the first letter is in uppercase and the remaining letters are in lowercase (Shh). | 1 | Applied and Interdisciplinary Chemistry |
In the absence of liver disease, high levels of total bilirubin confers various health benefits. Studies have also revealed that levels of serum bilirubin (SBR) are inversely related to risk of certain heart diseases. While the poor solubility and potential toxicity of bilirubin limit its potential medicinal applications, current research is being done on whether bilirubin encapsulated silk fibrin nanoparticles can alleviate symptoms of disorders such as acute pancreatitis. In addition to this, there has been recent discoveries linking bilirubin and its ε-polylysine-bilirubin conjugate (PLL-BR), to more efficient insulin medication. It seems that bilirubin exhibits protective properties during the islet transplantation process when drugs are delivered throughout the bloodstream. | 1 | Applied and Interdisciplinary Chemistry |
The unfavourable reduction of Fd from a less reducing electron donor can be coupled simultaneously with the favourable reduction of an oxidising agent through an electron bifurcation reaction. An example of the electron bifurcation reaction is the generation of for nitrogen fixation in certain aerobic diazotrophs. Typically in oxidative phosphorylation the transfer of electrons from NADH to Ubiquinone(Q) is coupled to charging the proton motive force. In Azotobacter the energy released by transferring one electron from NADH to Q is used to simultaneously boost the transfer of one electron from NADH to Fd. | 0 | Theoretical and Fundamental Chemistry |
Mid-FTIR spectroscopy can be used to rapidly and quantitatively determine the BN of hydrocarbon lubricating oils by spectroscopically measuring the carboxylate (COO-) functional group of the salt produced when trifluoroacetic acid (TFA) reacts with basic constituents present in an oil sample. | 0 | Theoretical and Fundamental Chemistry |
The Royal Society of Chemistry, its sections, societies that merged to form it and journals published by the Society.
de:Kategorie:Royal Society of Chemistry | 1 | Applied and Interdisciplinary Chemistry |
The topological properties of circular DNA are complex. In standard texts, these properties are invariably explained in terms of a helical model for DNA, but in 2008 it was noted that each topoisomer, negative or positive, adopts a unique and surprisingly wide distribution of three-dimensional conformations.
When the sedimentation coefficient, s, of circular DNA is ascertained over a large range of pH, the following curves are seen. Three curves are shown here, representing three species of DNA. From top-to-bottom they are: "Form IV" (green), "Form I" (blue) and "Form II" (red).
"Form I" (blue curve) is the traditional nomenclature used for the native form of duplex circular DNA, as recovered from viruses and intracellular plasmids. Form I is covalently closed, and any plectonemic winding which may be present is therefore locked in. If one or more nicks are introduced to Form I, free rotation of one strand with respect to the other becomes possible, and Form II (red curve) is seen.
Form IV (green curve) is the product of alkali denaturation of Form I. Its structure is unknown, except that it is persistently duplex, and extremely dense.
Between pH 7 and pH 11.5, the sedimentation coefficient s, for Form I, is constant. Then it dips, and at a pH just below 12, reaches a minimum. With further increases in pH, s then returns to its former value. It doesnt stop there, however, but continues to increase relentlessly. By pH 13, the value of s' has risen to nearly 50, two to three times its value at pH 7, indicating an extremely compact structure.
If the pH is then lowered, the s value is not restored. Instead, one sees the upper, green curve. The DNA, now in the state known as Form IV, remains extremely dense, even if the pH is restored to the original physiologic range. As stated previously, the structure of Form IV is almost entirely unknown, and there is no currently accepted explanation for its extraordinary density. About all that is known about the tertiary structure is that it is duplex, but has no hydrogen bonding between bases.
These behaviors of Forms I and IV are considered to be due to the peculiar properties of duplex DNA which has been covalently closed into a double-stranded circle. If the covalent integrity is disrupted by even a single nick in one of the strands, all such topological behavior ceases, and one sees the lower Form II curve (Δ). For Form II, alterations in pH have very little effect on s. Its physical properties are, in general, identical to those of linear DNA. At pH 13, the strands of Form II simply separate, just as the strands of linear DNA do. The separated single strands have slightly different s values, but display no significant changes in s with further increases in pH.
A complete explanation for these data is beyond the scope of this article. In brief, the alterations in s come about because of changes in the superhelicity of circular DNA. These changes in superhelicity are schematically illustrated by four little drawings which have been strategically superimposed upon the figure above.
Briefly, the alterations of s seen in the pH titration curve above are widely thought to be due to changes in the superhelical winding of DNA under conditions of increasing pH. Up to pH 11.5, the purported "underwinding" produces a right-handed ("negative") supertwist. But as the pH increases, and the secondary helical structure begins to denature and unwind, the chromosome (if we may speak anthropomorphically) no longer "wants" to have the full Watson–Crick winding, but rather "wants", increasingly, to be "underwound". Since there is less and less strain to be relieved by superhelical winding, the superhelices therefore progressively disappear as the pH increases. At a pH just below 12, all incentive for superhelicity has expired, and the chromosome will appear as a relaxed, open circle.
At higher pH still, the chromosome, which is now denaturing in earnest, tends to unwind entirely, which it cannot do so (because L is covalently locked in). Under these conditions, what was once treated as "underwinding" has actually now become "overwinding". Once again there is strain, and once again it is (in part at least) relieved by superhelicity, but this time in the opposite direction (i.e., left-handed or "positive"). Each left-handed tertiary supertwist removes a single, now undesirable right-handed Watson–Crick secondary twist.
The titration ends at pH 13, where Form IV appears. | 1 | Applied and Interdisciplinary Chemistry |
In domestic applications, traps are typically U, S, Q, or J-shaped pipe located below or within a plumbing fixture. An S-shaped trap is also known as an S-bend. It was invented by Alexander Cumming in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The U-bend could not jam, so, unlike the S-bend, it did not need an overflow. In the United States, traps are commonly referred to as P-traps. It is the addition of a 90 degree fitting on the outlet side of a U-bend, thereby creating a P-like shape (oriented horizontally). It is also referred to as a sink trap because it is installed under most sinks.
Because of its shape, the trap retains some water after the fixture's use. This water creates an air seal that prevents sewer gas from passing from the drain pipes back into the building. Essentially all plumbing fixtures including sinks, bathtubs, and showers must be equipped with either an internal or external trap. Toilets almost always have an internal trap.
Because it is a localized low-point in the plumbing, sink traps also tend to capture small and heavy objects (such as jewellery or coins) accidentally dropped down the sink. Traps also tend to collect hair, sand, food waste and other debris and limit the size of objects that enter the plumbing system, thereby catching oversized objects. For all of these reasons, most traps may be disassembled for cleaning or provide a cleanout feature.
Where a volume of water may be rapidly discharged through the trap, a vertical vented pipe called a standpipe may be attached to the trap to prevent the disruption of the seal in other nearby traps. The most common use of standpipes in houses is for clothes washing machines, which rapidly dispense a large volume of wastewater while draining the wash and rinse cycles.
In chemical engineering applications, a trap may be known as a lute. | 1 | Applied and Interdisciplinary Chemistry |
Intramolecular Diels–Alder (IMDA) reactions pair tethered dienes and dienophiles in a [4+2] fashion, the most common being terminal substitution. These transformations are popular in total synthesis and have seen a wide spread use in advance to numerous difficult synthetic targets. One such use is the application of an enantioselective IMDA transformation in the asymmetric synthesis of the marine toxin (10).
The synthesis of demonstrated the utility of cationic Cu(II)bis(oxazoline) complex catalyzed IMDA reactions to give bicyclic products with as many as four neighboring stereogenic centers (figure 3). A rather recent application of IMDA reactions in complex molecule synthesis is the IMDA approach to the tricyclic core of palhinine lycopodium alkaloids, a class of natural products isolated from nodding club moss.
N–heterocyclic carbenes (NHCs) are an emerging class of organocatalysts that are able to induce Umpolung reactivity as well as normal polarity transformations, however until recently these have not been broadly used in total synthesis due to limited substrate scope. An interesting expansion in the use of these organocatalysts is the NHC catalyzed olefin isomerization/IMDA cascade reaction to give unique bicyclic scaffolds. Dienyl esters such as 11 were transformed into substituted bicyclo[2.2.2]octanes via an isomerization step stabilized by a hemiacetal azolium intermediate (13). The activation barrier of isomerization of 1,3–hexadiene through a [1,5]–shift is 41 Kcal mol–1 and is expected to increase with conjugation to the ester, thus uncatalyzed isomerization is unlikely. This provides the advantage of bypassing a high barrier of activation, providing access to previously unobtainable IMDA derivatives. | 0 | Theoretical and Fundamental Chemistry |
Pipes may also be threaded with cylindrical threaded sections, in which case the threads do not themselves provide any sealing function other than some labyrinth seal effect, which may not be enough to satisfy either functional or code requirements. Instead, an O-ring seated between the shoulder of the male pipe section and an interior surface on the female, provides the seal. | 1 | Applied and Interdisciplinary Chemistry |
Acid deposition also occurs via dry deposition in the absence of precipitation. This can be responsible for as much as 20 to 60% of total acid deposition. This occurs when particles and gases stick to the ground, plants or other surfaces. | 1 | Applied and Interdisciplinary Chemistry |
Disabled Iranian veterans, called janbaz (, literally "those who were willing to lose their lives") in Iran, mostly constitute the disabled veterans of the Iran–Iraq war. According to Mohammad Esfandiari, director of communications and public relations of Irans Martyrs and Disabled Veterans Organization, there are 548,499 disabled veterans of the Iran–Iraq War living in Iran as of June 2014, a number which includes the victims of Iraqs chemical weapon attacks on Iran, called "chemical janbaz'" (). Among the disabled veterans are more than 10,000 veterans with foot and ankle injuries related to war. | 1 | Applied and Interdisciplinary Chemistry |
The Rayleigh–Taylor instability, or RT instability (after Lord Rayleigh and G. I. Taylor), is an instability of an interface between two fluids of different densities which occurs when the lighter fluid is pushing the heavier fluid. Examples include the behavior of water suspended above oil in the gravity of Earth, mushroom clouds like those from volcanic eruptions and atmospheric nuclear explosions, supernova explosions in which expanding core gas is accelerated into denser shell gas, instabilities in plasma fusion reactors and inertial confinement fusion.
Water suspended atop oil is an everyday example of Rayleigh–Taylor instability, and it may be modeled by two completely plane-parallel layers of immiscible fluid, the denser fluid on top of the less dense one and both subject to the Earth's gravity. The equilibrium here is unstable to any perturbations or disturbances of the interface: if a parcel of heavier fluid is displaced downward with an equal volume of lighter fluid displaced upwards, the potential energy of the configuration is lower than the initial state. Thus the disturbance will grow and lead to a further release of potential energy, as the denser material moves down under the (effective) gravitational field, and the less dense material is further displaced upwards. This was the set-up as studied by Lord Rayleigh. The important insight by G. I. Taylor was his realisation that this situation is equivalent to the situation when the fluids are accelerated, with the less dense fluid accelerating into the denser fluid. This occurs deep underwater on the surface of an expanding bubble and in a nuclear explosion.
As the RT instability develops, the initial perturbations progress from a linear growth phase into a non-linear growth phase, eventually developing "plumes" flowing upwards (in the gravitational buoyancy sense) and "spikes" falling downwards. In the linear phase, the fluid movement can be closely approximated by linear equations, and the amplitude of perturbations is growing exponentially with time. In the non-linear phase, perturbation amplitude is too large for a linear approximation, and non-linear equations are required to describe fluid motions. In general, the density disparity between the fluids determines the structure of the subsequent non-linear RT instability flows (assuming other variables such as surface tension and viscosity are negligible here). The difference in the fluid densities divided by their sum is defined as the Atwood number, A. For A close to 0, RT instability flows take the form of symmetric "fingers" of fluid; for A close to 1, the much lighter fluid "below" the heavier fluid takes the form of larger bubble-like plumes.
This process is evident not only in many terrestrial examples, from salt domes to weather inversions, but also in astrophysics and electrohydrodynamics. For example, RT instability structure is evident in the Crab Nebula, in which the expanding pulsar wind nebula powered by the Crab pulsar is sweeping up ejected material from the supernova explosion 1000 years ago. The RT instability has also recently been discovered in the Sun's outer atmosphere, or solar corona, when a relatively dense solar prominence overlies a less dense plasma bubble. This latter case resembles magnetically modulated RT instabilities.
Note that the RT instability is not to be confused with the Plateau–Rayleigh instability (also known as Rayleigh instability) of a liquid jet. This instability, sometimes called the hosepipe (or firehose) instability, occurs due to surface tension, which acts to break a cylindrical jet into a stream of droplets having the same total volume but higher surface area.
Many people have witnessed the RT instability by looking at a lava lamp, although some might claim this is more accurately described as an example of Rayleigh–Bénard convection due to the active heating of the fluid layer at the bottom of the lamp. | 1 | Applied and Interdisciplinary Chemistry |
DMDO is most commonly used for the oxidation of alkenes to epoxides. One advantage of using DMDO is that the only byproduct of oxidation is acetone, a fairly innocuous and volatile compound. DMDO oxidations are particularly mild, sometimes allowing oxidations which might not otherwise be possible.
Despite its high reactivity, DMDO displays good selectivity for electron-rich olefins. DMDO will also oxidize several other functional groups. For example, DMDO will oxidize primary amines to nitro compounds and sulfides to sulfoxides. In some cases, DMDO will even oxidize unactivated C-H bonds:
DMDO can also be used to convert nitro compounds to carbonyl compounds (Nef reaction). | 0 | Theoretical and Fundamental Chemistry |
Cells respond to stress in the form of DNA damage, activated oncogenes, or sub-par growing conditions, and can enter a senescence-like state called "premature senescence". This allows the cell to prevent further replication during periods of damaged DNA or general unfavorable conditions. DNA damage in a cell can induce pRb activation. pRb's role in repressing the transcription of cell cycle progression genes leads to the S phase arrest that prevents replication of damaged DNA. | 1 | Applied and Interdisciplinary Chemistry |
Zyklon B (; translated Cyclone B) was the trade name of a cyanide-based pesticide invented in Germany in the early 1920s. It consists of hydrogen cyanide (prussic acid), as well as a cautionary eye irritant and one of several adsorbents such as diatomaceous earth. The product is notorious for its use by Nazi Germany during the Holocaust to murder approximately 1.1 million people in gas chambers installed at Auschwitz-Birkenau, Majdanek, and other extermination camps.
Hydrogen cyanide, a poisonous gas that interferes with cellular respiration, was first used as a pesticide in California in the 1880s. Research at Degesch of Germany led to the development of Zyklon (later known as Zyklon A), a pesticide that released hydrogen cyanide upon exposure to water and heat. It was banned after World War I, when Germany used a similar product as a chemical weapon. Degussa purchased Degesch in 1922. Their team of chemists, which included and Bruno Tesch, devised a method of packaging hydrogen cyanide in sealed canisters along with a cautionary eye irritant and one of several adsorbents such as diatomaceous earth. The new product was also named Zyklon, but it became known as Zyklon B to distinguish it from the earlier version. Uses included delousing clothing and fumigating ships, warehouses, and trains.
The Nazis started using Zyklon B in extermination camps in early 1942 to murder prisoners during the Holocaust. Tesch and his deputy executive, Karl Weinbacher, were executed in 1946 for knowingly selling the product to the SS for use on humans. Hydrogen cyanide is now rarely used as a pesticide but still has industrial applications. Firms in several countries continue to produce Zyklon B under alternative brand names, including Detia-Degesch, the successor to Degesch, who renamed the product Cyanosil in 1974. | 1 | Applied and Interdisciplinary Chemistry |
Current nanoparticle drug delivery systems can be cataloged based on their platform composition into several groups: polymeric nanoparticles, inorganic nanoparticles, viral nanoparticles, lipid-based nanoparticles, and nanoparticle albumin-bound (nab) technology. Each family has its unique characteristics. | 0 | Theoretical and Fundamental Chemistry |
The residual dipolar coupling between two spins in a molecule occurs if the molecules in solution exhibit a partial alignment leading to an incomplete averaging of spatially anisotropic dipolar couplings.
Partial molecular alignment leads to an incomplete averaging of anisotropic magnetic interactions such as the magnetic dipole-dipole interaction (also called dipolar coupling), the chemical shift anisotropy, or the electric quadrupole interaction. The resulting so-called residual anisotropic magnetic interactions are useful in biomolecular NMR spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
Colloid solutions used in intravenous therapy belong to a major group of volume expanders, and can be used for intravenous fluid replacement. Colloids preserve a high colloid osmotic pressure in the blood, and therefore, they should theoretically preferentially increase the intravascular volume, whereas other types of volume expanders called crystalloids also increase the interstitial volume and intracellular volume. However, there is still controversy to the actual difference in efficacy by this difference, and much of the research related to this use of colloids is based on fraudulent research by Joachim Boldt. Another difference is that crystalloids generally are much cheaper than colloids. | 0 | Theoretical and Fundamental Chemistry |
On January 18, 1955, then-AEC commissioner Dr. Willard Libby said that there was insufficient data regarding the effects of fallout due to a lack of human samples – especially samples taken from children – to analyze. Libby was quoted saying, "I dont know how to get them, but I do say that it is a matter of prime importance to get them, and particularly in the young age group. So, human samples are often of prime importance, and if anybody knows how to do a good job of body snatching, they will really be serving their country." This led to over 1,500 samples being gathered, of which only 500 were analyzed. Many of the 1,500 sample cadavers were babies and young children, and were taken from countries from Australia to Europe, often without their parents consent or knowledge. According to the investigation launched after a British newspaper reported that British scientists had obtained children’s bodies from various hospitals and shipped their body parts to the United States, a British mother had said that her stillborn baby's legs were removed by British doctors, and to prevent her from finding out what had happened, she was not allowed to dress the baby for the funeral. | 0 | Theoretical and Fundamental Chemistry |
Sequence reads are not perfect, so the accuracy of each base in the sequence needs to be estimated for downstream analyses. Raw data is examined to ensure: quality scores for base calls are high, the GC content matches the expected distribution, short sequence motifs (k-mers) are not over-represented, and the read duplication rate is acceptably low. Several software options exist for sequence quality analysis, including FastQC and FaQCs. Abnormalities may be removed (trimming) or tagged for special treatment during later processes. | 1 | Applied and Interdisciplinary Chemistry |
Reagents can be pulled through an endergonic reaction, if the reaction products are cleared rapidly by a subsequent exergonic reaction. The concentration of the products of the endergonic reaction thus always remains low, so the reaction can proceed.
A classic example of this might be the first stage of a reaction which proceeds via a transition state. The process of getting to the top of the activation energy barrier to the transition state is endergonic. However, the reaction can proceed because having reached the transition state, it rapidly evolves via an exergonic process to the more stable final products. | 0 | Theoretical and Fundamental Chemistry |
In the pharmaceutical industry, some amorphous drugs have been shown to offer higher bioavailability than their crystalline counterparts as a result of the higher solubility of the amorphous phase. However, certain compounds can undergo precipitation in their amorphous form in vivo, and can then decrease mutual bioavailability if administered together. | 0 | Theoretical and Fundamental Chemistry |
While it is well established that the skin provides an ideal site for the administration of local and systemic drugs, it presents a formidable barrier to the permeation of most substances. Isotropic formulations have been used to deliver drugs locally and systemically via the skin appendages, intercellular and transcellular routes. | 0 | Theoretical and Fundamental Chemistry |
Utilitarian and ceremonial objects; objects of personal adornment
#Chichén Itzá, Yucatán
#Dzantún C’hen, Yucatán
#Mayapán, Yucatán | 1 | Applied and Interdisciplinary Chemistry |
Research into the phenomenon of ocean acidification, as well as awareness raising about the problem, has been going on for several decades. The fundamental research really began with the creation of the pH scale by Danish chemist Søren Peder Lauritz Sørensen in 1909. By around the 1950s the massive role of the ocean in absorbing fossil fuel CO was known to specialists, but not appreciated by the greater scientific community. Throughout much of the 20th century, the dominant focus has been the beneficial process of oceanic CO uptake, which has enormously ameliorated climate change. The concept of "too much of a good thing" has been late in developing and was triggered only by some key events, and the oceanic sink for heat and CO is still critical as the primary buffer against climate change.
In the early 1970s questions over the long-term impact of the accumulation of fossil fuel CO in the sea were already arising around the world and causing strong debate. Researchers commented on the accumulation of fossil CO in the atmosphere and sea and drew attention to the possible impacts on marine life. By the mid-1990s, the likely impact of CO levels rising so high with the inevitable changes in pH and carbonate ion became a concern of scientists studying the fate of coral reefs.
By the end of the 20th century the trade-offs between the beneficial role of the ocean in absorbing some 90 % of all heat created, and the accumulation of some 50 % of all fossil fuel CO emitted, and the impacts on marine life were becoming more clear. By 2003, the time of planning for the "First Symposium on the Ocean in a High-CO World" meeting to be held in Paris in 2004, many new research results on ocean acidification were published.
In 2009, members of the InterAcademy Panel called on world leaders to "Recognize that reducing the build up of in the atmosphere is the only practicable solution to mitigating ocean acidification". The statement also stressed the importance to "Reinvigorate action to reduce stressors, such as overfishing and pollution, on marine ecosystems to increase resilience to ocean acidification".
For example, research in 2010 found that in the 15-year period 1995–2010 alone, acidity had increased 6 percent in the upper 100 meters of the Pacific Ocean from Hawaii to Alaska.
According to a statement in July 2012 by Jane Lubchenco, head of the U.S. National Oceanic and Atmospheric Administration "surface waters are changing much more rapidly than initial calculations have suggested. It's yet another reason to be very seriously concerned about the amount of carbon dioxide that is in the atmosphere now and the additional amount we continue to put out."
A 2013 study found acidity was increasing at a rate 10 times faster than in any of the evolutionary crises in Earth's history.
The "Third Symposium on the Ocean in a High- World" took place in Monterey, California, in 2012. The summary for policy makers from the conference stated that "Ocean acidification research is growing rapidly".
In a synthesis report published in Science in 2015, 22 leading marine scientists stated that from burning fossil fuels is changing the oceans chemistry more rapidly than at any time since the Great Dying (Earths most severe known extinction event). Their report emphasized that the 2 °C maximum temperature increase agreed upon by governments reflects too small a cut in emissions to prevent "dramatic impacts" on the world's oceans. | 0 | Theoretical and Fundamental Chemistry |
Filters are often used to collect bioaerosols because of their simplicity and low cost. Filter collection is especially useful for personal bioaerosol sampling since they are light and unobtrusive. Filters can be preceded by a size-selective inlet, such as a cyclone or impactor, to remove larger particles and provide size-classification of the bioaerosol particles. Aerosol filters are often described using the term "pore size" or "equivalent pore diameter". Note that the filter pore size does NOT indicate the minimum particle size that will be collected by the filter; in fact, aerosol filters generally will collect particles much smaller than the nominal pore size. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, a reporter gene (often simply reporter) is a gene that researchers attach to a regulatory sequence of another gene of interest in bacteria, cell culture, animals or plants. Such genes are called reporters because the characteristics they confer on organisms expressing them are easily identified and measured, or because they are selectable markers. Reporter genes are often used as an indication of whether a certain gene has been taken up by or expressed in the cell or organism population. | 1 | Applied and Interdisciplinary Chemistry |
Superhydrophobic surfaces, such as the leaves of the lotus plant, are those that are extremely difficult to wet. The contact angles of a water droplet exceeds 150°. This is referred to as the lotus effect, and is primarily a physical property related to interfacial tension, rather than a chemical property. | 0 | Theoretical and Fundamental Chemistry |
Sodium tert-butoxide (or sodium t-butoxide) is a chemical compound with the formula (CH)CONa (abbr. NaOtBu). It is a strong, non-nucleophilic base. It is flammable and moisture sensitive. It is sometimes written in the chemical literature as sodium t-butoxide. It is similar in reactivity to the more common potassium tert-butoxide.
The compound can be produced by treating tert-butyl alcohol with sodium hydride. | 0 | Theoretical and Fundamental Chemistry |
As with other pharmaceutical drugs, there is standardization of the drug nomenclature for radiopharmaceuticals, although various standards coexist. The International Nonproprietary Name (INN) gives the base drug name, followed by the radioisotope (as mass number, no space, element symbol) in parentheses with no superscript, followed by the ligand (if any). It is common to see square brackets and superscript superimposed onto the INN name, because chemical nomenclature (such as IUPAC nomenclature) uses those. The United States Pharmacopeia (USP) name gives the base drug name, followed by the radioisotope (as element symbol, space, mass number) with no parentheses, no hyphen, and no superscript, followed by the ligand (if any). The USP style is not the INN style, despite their being described as one and the same in some publications (e.g., AMA, whose style for radiopharmaceuticals matches the USP style). The United States Pharmacopeial Convention is a sponsor organization of the USAN Council, and the USAN for a given drug is often the same as the USP name. | 1 | Applied and Interdisciplinary Chemistry |
The Si-V center is formed by replacing two neighboring carbon atoms in the diamond lattice with one silicon atom, which places itself between the two vacant lattice sites. This configuration has a D point group symmetry. | 0 | Theoretical and Fundamental Chemistry |
The von Foerster equation is a continuity equation; it can be solved using the method of characteristics. Another way is by similarity solution; and a third is a numerical approach such as finite differences.
To get the solution, the following boundary conditions should be added:
which states that the initial births should be conserved (see Sharpe–Lotka–McKendrick’s equation for otherwise), and that:
which states that the initial population must be given; then it will evolve according to the partial differential equation. | 1 | Applied and Interdisciplinary Chemistry |
Some plasmids or microbial hosts include an addiction system or postsegregational killing system (PSK), such as the hok/sok (host killing/suppressor of killing) system of plasmid R1 in Escherichia coli. This variant produces both a long-lived poison and a short-lived antidote. Several types of plasmid addiction systems (toxin/ antitoxin, metabolism-based, ORT systems) were described in the literature and used in biotechnical (fermentation) or biomedical (vaccine therapy) applications. Daughter cells that retain a copy of the plasmid survive, while a daughter cell that fails to inherit the plasmid dies or suffers a reduced growth-rate because of the lingering poison from the parent cell. Finally, the overall productivity could be enhanced.
In contrast, plasmids used in biotechnology, such as pUC18, pBR322 and derived vectors, hardly ever contain toxin-antitoxin addiction systems, and therefore need to be kept under antibiotic pressure to avoid plasmid loss. | 1 | Applied and Interdisciplinary Chemistry |
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