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Bridge scour is the removal of sediment such as sand and gravel from around bridge abutments or piers. Hydrodynamic scour, caused by fast flowing water, can carve out scour holes, compromising the integrity of a structure.
In the United States, bridge scour is one of the three main causes of bridge failure (the others being collision and overloading). It has been estimated that 60% of all bridge failures result from scour and other hydraulic-related causes. It is the most common cause of highway bridge failure in the US, where 46 of 86 major bridge failures resulted from scour near piers from 1961 to 1976. | 1 | Applied and Interdisciplinary Chemistry |
Out of the available endocrine-disrupting compounds looked at, flutamide has a notable effect on anogenital distance in rats.) | 0 | Theoretical and Fundamental Chemistry |
Copper-clad steel wire find applications in grounding, connection of ground rods to metallic structures, ground grid meshes, substations, power installations, and lightning arresters.
This wire is also sometimes used for power transmission.
Copper coated welding wire has become common since wire welding equipment has become popular.
Copper-clad steel is occasionally used for making durable radio antennas, where its HF conductivity is nearly identical to a same-diameter solid copper conductor. It is most often used in antennas with long spans of unsupported wire, which need extra strength to withstand high tension which would cause solid copper or aluminum wire to break or stretch excessively. | 1 | Applied and Interdisciplinary Chemistry |
In materials science, the sol–gel process is a method for producing solid materials from small molecules. The method is used for the fabrication of metal oxides, especially the oxides of silicon (Si) and titanium (Ti). The process involves conversion of monomers into a colloidal solution (sol) that acts as the precursor for an integrated network (or gel) of either discrete particles or network polymers. Typical precursors are metal alkoxides. Sol–gel process is used to produce ceramic nanoparticles. | 0 | Theoretical and Fundamental Chemistry |
The data generated in metabolomics usually consist of measurements performed on subjects under various conditions. These measurements may be digitized spectra, or a list of metabolite features. In its simplest form, this generates a matrix with rows corresponding to subjects and columns corresponding with metabolite features (or vice versa). Several statistical programs are currently available for analysis of both NMR and mass spectrometry data. A great number of free software are already available for the analysis of metabolomics data shown in the table. Some statistical tools listed in the table were designed for NMR data analyses were also useful for MS data. For mass spectrometry data, software is available that identifies molecules that vary in subject groups on the basis of mass-over-charge value and sometimes retention time depending on the experimental design.
Once metabolite data matrix is determined, unsupervised data reduction techniques (e.g. PCA) can be used to elucidate patterns and connections. In many studies, including those evaluating drug-toxicity and some disease models, the metabolites of interest are not known a priori. This makes unsupervised methods, those with no prior assumptions of class membership, a popular first choice. The most common of these methods includes principal component analysis (PCA) which can efficiently reduce the dimensions of a dataset to a few which explain the greatest variation. When analyzed in the lower-dimensional PCA space, clustering of samples with similar metabolic fingerprints can be detected. PCA algorithms aim to replace all correlated variables with a much smaller number of uncorrelated variables (referred to as principal components (PCs)) and retain most of the information in the original dataset. This clustering can elucidate patterns and assist in the determination of disease biomarkers – metabolites that correlate most with class membership.
Linear models are commonly used for metabolomics data, but are affected by multicollinearity. On the other hand, multivariate statistics are thriving methods for high-dimensional correlated metabolomics data, of which the most popular one is Projection to Latent Structures (PLS) regression and its classification version PLS-DA. Other data mining methods, such as random forest, support-vector machines, etc. are received increasing attention for untargeted metabolomics data analysis. In the case of univariate methods, variables are analyzed one by one using classical statistics tools (such as Student's t-test, ANOVA or mixed models) and only these with sufficient small p-values are considered relevant. However, correction strategies should be used to reduce false discoveries when multiple comparisons are conducted since there is no standard method for measuring the total amount of metabolites directly in untargeted metabolomics. For multivariate analysis, models should always be validated to ensure that the results can be generalized. | 1 | Applied and Interdisciplinary Chemistry |
In order to fully understand complex ocean systems, a wide variety of sensor arrays, capable of surviving for long periods of time in harsh conditions, are necessary. A suite of sensors (over 100) were selected and strategically placed throughout RSN. They are located at Axial Seamount, Hydrate Ridge, and also on the water-column moorings.
Instruments connected to the RSN include:
* Conductivity Temperature Depth (located on profilers)
* Dissolved Oxygen,
* 3-D Single Point Current Meter
* Temperature
* Fluorometers
* CDOM,
* Chlorophyll-a,
* Optical Backscatter
The instruments are the final spot of each regional network branch. | 0 | Theoretical and Fundamental Chemistry |
The New Zealand Association of Scientists awarded Halton its Research Medal in 1974, and the Shorland Medal in 2001. In 1980, he received the ICI Medal for excellence in chemical research from the NZIC. Halton was elected a Fellow of the New Zealand Institute of Chemistry in 1977, and a Fellow of the Royal Society of New Zealand in 1992. In 2005, he was awarded an honorary fellowship of the NZIC. | 0 | Theoretical and Fundamental Chemistry |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), Valine (Val, V) | 1 | Applied and Interdisciplinary Chemistry |
Lipid peroxidation, or lipid oxidation, is a complex chemical process that leads to oxidative degradation of lipids, resulting in the formation of peroxide and hydroperoxide derivatives. It occurs when free radicals, specifically reactive oxygen species (ROS), interact with lipids within cell membranes, typically polyunsaturated fatty acids (PUFAs) as they have carbon–carbon double bonds. This reaction leads to the formation of lipid radicals, collectively referred to as lipid peroxides or lipid oxidation products (LOPs), which in turn react with other oxidizing agents, leading to a chain reaction that results in oxidative stress and cell damage.
In pathology and medicine, lipid peroxidation plays a role in cell damage which has broadly been implicated in the pathogenesis of various diseases and disease states, including ageing, whereas in food science lipid peroxidation is one of many pathways to rancidity. | 1 | Applied and Interdisciplinary Chemistry |
Unlike DNA editing, which is permanent, the effects of RNA editing − including potential off-target mutations in RNA − are transient and are not inherited. RNA editing is therefore considered to be less risky. Furthermore, it may only require a guide RNA by using the ADAR protein already found in humans and many other eukaryotes' cells instead of needing to introduce a foreign protein into the body. | 1 | Applied and Interdisciplinary Chemistry |
A variation of the Washoe process was developed in the Reese River mining district around Austin, Nevada. The Washoe process was found not to work well for ores with arsenic or antimony sulfides, or with galena or sphalerite. In 1869, Carl A. Stetefeldt of Reno found that roasting the ore with salt converted the silver sulfides to silver chlorides, which could then be recovered in amalgamation pans. The process was introduced in the Reese River District in 1879, with great success.
Other silver-mining districts using the Reese River process included Georgetown, Colorado, Caribou, Colorado, and Silver Cliff, Colorado. | 1 | Applied and Interdisciplinary Chemistry |
Many cyanobacteria are able to reduce nitrogen and carbon dioxide under aerobic conditions, a fact that may be responsible for their evolutionary and ecological success. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z-scheme). In contrast to green sulfur bacteria which only use one photosystem, the use of water as an electron donor is energetically demanding, requiring two photosystems.
Attached to the thylakoid membrane, phycobilisomes act as light-harvesting antennae for the photosystems. The phycobilisome components (phycobiliproteins) are responsible for the blue-green pigmentation of most cyanobacteria. The variations on this theme are due mainly to carotenoids and phycoerythrins that give the cells their red-brownish coloration. In some cyanobacteria, the color of light influences the composition of the phycobilisomes. In green light, the cells accumulate more phycoerythrin, which absorbs green light, whereas in red light they produce more phycocyanin which absorbs red. Thus, these bacteria can change from brick-red to bright blue-green depending on whether they are exposed to green light or to red light. This process of "complementary chromatic adaptation" is a way for the cells to maximize the use of available light for photosynthesis.
A few genera lack phycobilisomes and have chlorophyll b instead (Prochloron, Prochlorococcus, Prochlorothrix). These were originally grouped together as the prochlorophytes or chloroxybacteria, but appear to have developed in several different lines of cyanobacteria. For this reason, they are now considered as part of the cyanobacterial group. | 0 | Theoretical and Fundamental Chemistry |
Typically, column chromatography is set up with peristaltic pumps, flowing buffers and the solution sample through the top of the column. The solutions and buffers pass through the column where a fraction collector at the end of the column setup collects the eluted samples. Prior to the fraction collection, the samples that are eluted from the column pass through a detector such as a spectrophotometer or mass spectrometer so that the concentration of the separated samples in the sample solution mixture can be determined.
For example, if you were to separate two different proteins with different binding capacities to the column from a solution sample, a good type of detector would be a spectrophotometer using a wavelength of 280 nm. The higher the concentration of protein that passes through the eluted solution through the column, the higher the absorbance of that wavelength.
Because the column chromatography has a constant flow of eluted solution passing through the detector at varying concentrations, the detector must plot the concentration of the eluted sample over a course of time. This plot of sample concentration versus time is called a chromatogram.
The ultimate goal of chromatography is to separate different components from a solution mixture. The resolution expresses the extent of separation between the components from the mixture. The higher the resolution of the chromatogram, the better the extent of separation of the samples the column gives. This data is a good way of determining the column's separation properties of that particular sample. The resolution can be calculated from the chromatogram.
The separate curves in the diagram represent different sample elution concentration profiles over time based on their affinity to the column resin. To calculate resolution, the retention time and curve width are required.
Retention time is the time from the start of signal detection by the detector to the peak height of the elution concentration profile of each different sample.
Curve width is the width of the concentration profile curve of the different samples in the chromatogram in units of time.
A simplified method of calculating chromatogram resolution is to use the plate model. The plate model assumes that the column can be divided into a certain number of sections, or plates and the mass balance can be calculated for each individual plate. This approach approximates a typical chromatogram curve as a Gaussian distribution curve. By doing this, the curve width is estimated as 4 times the standard deviation of the curve, 4σ. The retention time is the time from the start of signal detection to the time of the peak height of the Gaussian curve.
From the variables in the figure above, the resolution, plate number, and plate height of the column plate model can be calculated using the equations:
Resolution (R):
:R = 2(t – t)/(w + w),
where:
:t = retention time of solute B
:t = retention time of solute A
:w = Gaussian curve width of solute B
:w = Gaussian curve width of solute A
Plate Number (N):
:N = (t)/(w/4)
Plate Height (H):
:H = L/N
where L is the length of the column. | 0 | Theoretical and Fundamental Chemistry |
A tablet is usually a compressed preparation that contains:
*5-10% of the drug (active substance);
*80% of fillers, disintegrants, lubricants, glidants, and binders; and
*10% of compounds which ensure easy disintegration, disaggregation, and dissolution of the tablet in the stomach or the intestine.
The dissolution time can be modified for a rapid effect or for sustained release.
Special coatings can make the tablet resistant to the stomach acids such that it only disintegrates in the duodenum, jejunum and colon as a result of enzyme action or alkaline pH.
Pills can be coated with sugar, varnish, or wax to disguise the taste. | 1 | Applied and Interdisciplinary Chemistry |
The reaction happens with two metal cofactors (Mg or Mn) coordinated to the two aspartate residues on C1. They perform a nucleophilic attack of the 3'-OH group of the ribose on the α-phosphoryl group of ATP. The two lysine and aspartate residues on C2 selects ATP over GTP for the substrate, so that the enzyme is not a guanylyl cyclase. A pair of arginine and asparagine residues on C2 stabilizes the transition state. In many proteins, these residues are nevertheless mutated while retaining the adenylyl cyclase activity. | 1 | Applied and Interdisciplinary Chemistry |
Cram was named an assistant professor at the University of California, Los Angeles in 1947, and a professor in 1955. He served there until his retirement in 1987. He was a popular teacher, having instructed some 8,000 undergraduates in his career and guided the academic output of 200 graduate students. He entertained his classes by strumming his guitar and singing folk songs. He showed a self-deprecating style, saying at one time: | 0 | Theoretical and Fundamental Chemistry |
The drawbacks of the SMB are higher investment cost compared to single column operations, a higher complexity, as well as higher maintenance costs. But these drawbacks are effectively compensated by the better yield and a much lower solvent consumption as well as a much higher productivity compared to simple batch separations.
For purifications, in particular the isolation of an intermediate single component or a fraction out of a multicomponent mixture, the SMB is not as ideally suited. Normally, a single SMB will separate only two fractions from each other, but a series or "train" of SMBs can perform multiple cuts and purify one or more products from a multi-component mixture. SMB is not readily suited for solvent gradients. Solvent gradient purification may be preferred for the purification of some biomolecules. A continuous chromatography technique to overcome the two fraction limit and to apply gradients is multicolumn countercurrent solvent gradient purification (MCSGP). | 0 | Theoretical and Fundamental Chemistry |
Phage display was first described by George P. Smith in 1985, when he demonstrated the display of peptides on filamentous phage (long, thin viruses that infect bacteria) by fusing the virus's capsid protein to one peptide out of a collection of peptide sequences. This displayed the different peptides on the outer surfaces of the collection of viral clones, where the screening step of the process isolated the peptides with the highest binding affinity. In 1988, Stephen Parmley and George Smith described biopanning for affinity selection and demonstrated that recursive rounds of selection could enrich for clones present at 1 in a billion or less. In 1990, Jamie Scott and George Smith described creation of large random peptide libraries displayed on filamentous phage. Phage display technology was further developed and improved by groups at the Laboratory of Molecular Biology with Greg Winter and John McCafferty, The Scripps Research Institute with Richard Lerner and Carlos Barbas and the German Cancer Research Center with Frank Breitling and Stefan Dübel for display of proteins such as antibodies for therapeutic protein engineering. Smith and Winter were awarded a half share of the 2018 Nobel Prize in chemistry for their contribution to developing phage display. A patent by George Pieczenik claiming priority from 1985 also describes the generation of peptide libraries. | 1 | Applied and Interdisciplinary Chemistry |
Nitrogen gas (N) makes up 78% of the atmosphere and is extremely well mixed over short time-scales, resulting in a homogenous isotopic distribution ideal for use as a reference material. Atmospheric N is commonly called AIR when being used as an isotopic reference. In addition to atmospheric N there are multiple N isotopic reference materials. | 0 | Theoretical and Fundamental Chemistry |
A jet is a stream of fluid that is projected into a surrounding medium, usually from some kind of a nozzle, aperture or orifice. Jets can travel long distances without dissipating.
Jet fluid has higher momentum compared to the surrounding fluid medium. In the case that the surrounding medium is assumed to be made up of the same fluid as the jet, and this fluid has a viscosity, the surrounding fluid is carried along with the jet in a process called entrainment.
Some animals, notably cephalopods, move by jet propulsion, as do rocket engines and jet engines. | 1 | Applied and Interdisciplinary Chemistry |
Under Mahdi's directorship, the Secretariat has been keen "on implementing the Sustainable Development Goals (SDGs), or the 2030 Agenda, adopted by the UN in September 2015," and have already "achieved a considerable part of the Sustainable Development Goals" for Post-2015.
A key mission of the KNDP is to create stronger integration between Kuwaits public and private sectors, and in an interview with the Oxford Business Group as part of their Kuwait 2017 report, Mahdi shared that "the government stated very clearly its intentions to transition its role in the economy from an operator to regulator, from wealth distribution to wealth creation, and to entrust the economy to the private sector." Additionally, Mahdi oversees the GSSCPDs engagement in development programming and support of the national development agenda, working with various sectors and segments of the population.
In Mahdi's own words about the implementation of the national plan, the Secretariat looks to build "a solid commercial and financial infrastructure, and this cements us as a financial and commercial hub", through projects like the Knowledge Transfer and Small and Medium Enterprises (SME) expo, The knowledge Economy Forum and the Kuwait Public Policy Center (KPPC). | 1 | Applied and Interdisciplinary Chemistry |
The very high precision of (strange) particle spectra and large transverse momentum coverage reported by the ALICE Collaboration at the Large Hadron Collider (LHC) allows in-depth exploration of lingering challenges, which always accompany new physics, and here in particular the questions surrounding strangeness signature. Among the most discussed challenges has been the question if the abundance of particles produced is enhanced or if the comparison base line is suppressed. Suppression is expected when an otherwise absent quantum number, such as strangeness, is rarely produced. This situation was recognized by Hagedorn in his early analysis of particle production and solved by Rafelski and Danos. In that work it was shown that even if just a few new pairs of strange particles were produced the effect disappears. However, the matter was revived by Hamieh et al. who argued that is possible that small sub-volumes in QGP are of relevance. This argument can be resolved by exploring specific sensitive experimental signatures for example the ratio of double strange particles of different type, such yield of () compared to (). The ALICE experiment obtained this ratio for several collision systems in a wide range of hadronization volumes as described by the total produced particle multiplicy. The results show that this ratio assumes the expected value for a large range volumes (two orders of magnitude). At small particle volume or multiplicity, the curve shows the expected reduction: The () must be smaller compared to () as the number of produced strange pairs decreases and thus it easier to make () compared to () that requires two pairs minimum to be made. However, we also see an increase at very high volume—this is an effect at the level of one to two standard deviations. Similar results were already recognized before by Petran et al.
Another highly praised ALICE result is the observation of same strangeness enhancement, not only on AA (nucleus–nucleus) but also in pA (proton–nucleus) and pp (proton–proton) collisions when the particle production yields are presented as a function of the multiplicity, which, as noted, corresponds to the available hadronization volume. ALICE results display a smooth volume dependence of total yield of all studied particles as function of volume, there is no additional "canonical" suppression. This is so since the yield of strange pairs in QGP is sufficiently high and tracks well the expected abundance increase as the volume and lifespan of QGP increases. This increase is incompatible with the hypothesis that for all reaction volumes QGP is always in chemical (yield) equilibrium of strangeness. Instead, this confirms the theoretical kinetic model proposed by Rafelski and Müller. The production of QGP in pp collisions was not expected by all, but should not be a surprise. The onset of deconfinement is naturally a function of both energy and collision system size. The fact that at extreme LHC energies we cross this boundary also in experiments with the smallest elementary collision systems, such as pp, confirms the unexpected strength of the processes leading to QGP formation. Onset of deconfinement in pp and other "small" system collisions remains an active research topic.
Beyond strangeness the great advantage offered by LHC energy range is the abundant production of charm and bottom flavor. When QGP is formed, these quarks are embedded in a high density of strangeness present. This should lead to copious production of exotic heavy particles, for example . Other heavy flavor particles, some which have not even been discovered at this time, are also likely to appear. | 0 | Theoretical and Fundamental Chemistry |
In electrophilic trifluoromethylation the active trifluoromethyl donor group carries a positive charge. Production of an CF cation has been described as "extremely hard" The first relevant reagent, a diaryl(trifluoromethyl) sulfonium salt (ArSCFSbF) was developed in 1984 by reaction of an aryltrifluoromethyl sulfoxide 1 with SFSbF followed by reaction with an electron-rich arene. The reagent was used in trifluoromethylation of a thiophenolate.
S-(trifluoromethyl)dibenzothiophenium tetrafluoroborate is a commercially available and known trifluoromethylation reagent based on the same principle first documented in 1990. In this type of compound sulfur has been replaced by oxygen, selenium and tellurium. Examples of substrates that have been investigated are pyridine, aniline, triphenylphosphine and the lithium salt of phenylacetylene.
Another group of trifluoromethyl donors are hypervalent iodine(III)–CF reagents for example 3,3-dimethyl-1-(trifluoromethyl)-1,2-benziodoxole. Some of these are known as Togni reagents, such as Togni reagent II. Substrates are thiols, alcohols, phosphines, (hetero) arenes, unactivated olefins and unsaturated carboxylic acids.
The reaction mechanism of electrophilic trifluoromethylations has been described as controversial with polar substitution or single electron transfer as likely candidates. | 0 | Theoretical and Fundamental Chemistry |
Ketazines are also important intermediates in the industrial production of hydrazine hydrate by the peroxide process. In the presence of an oxidant, ammonia and ketones react to give hydrazine via ketazine:
:2 Me(Et)C=O + 2 NH + HO → Me(Et)C=NN=C(Et)Me + 2 HO
The ketazine can be hydrolyzed to the hydrazine and regenerate the ketone:
:Me(Et)C=NN=C(Et)Me + 2 HO → 2 Me(Et)C=O + NH
Ketazines have been also used as sources of hydrazine produced in situ, for example in the production of herbicide precursor 1,2,4-triazole. | 0 | Theoretical and Fundamental Chemistry |
Examples of slurries include:
*Cement slurry, a mixture of cement, water, and assorted dry and liquid additives used in the petroleum and other industries
*Soil/cement slurry, also called Controlled Low-Strength Material (CLSM), flowable fill, controlled density fill, flowable mortar, plastic soil-cement, K-Krete, and other names
*A mixture of thickening agent, oxidizers, and water used to form a gel explosive
*A mixture of pyroclastic material, rocky debris, and water produced in a volcanic eruption and known as a lahar
*A mixture of bentonite and water used to make slurry walls
*Coal slurry, a mixture of coal waste and water, or crushed coal and water
*Slip, a mixture of clay and water used for joining, glazing and decoration of ceramics and pottery.
*Slurry oil, the highest boiling fraction distilled from the effluent of an FCC unit in an oil refinery. It contains a large amount of catalyst, in form of sediments hence the denomination of slurry.
*A mixture of wood pulp and water used to make paper
*Manure slurry, a mixture of animal waste, organic matter, and sometimes water often known simply as "slurry" in agricultural use, used as fertilizer after aging in a slurry pit
*Meat slurry, a mixture of finely ground meat and water, centrifugally dewatered and used as a food ingredient.
*An abrasive substance used in chemical-mechanical polishing
*Slurry ice, a mixture of ice crystals, freezing point depressant, and water
*A mixture of raw materials and water involved in the rawmill manufacture of Portland cement
*A bolus of chewed food mixed with saliva
*A mixture of epoxy glue and glass microspheres used as a filler compound around core materials in sandwich-structured composite airframes. | 1 | Applied and Interdisciplinary Chemistry |
Gilbert Stork was born in the Ixelles municipality of Brussels, Belgium on December 31, 1921. The oldest of 3 children, his middle brother, Michel, died in infancy, but he remained close with his younger sister Monique his whole life. His family had Jewish origins, although Gilbert himself didnt recall them being religiously active. The family moved to Nice when Gilbert was about 14 (circa. 1935) and remained there until 1939. During this period, Gilbert completed his lycée studies, distinguishing himself in French literature and writing. Characterizing himself during those years as "not terribly self-confident," and uncertain whether he could find employment in a profession he enjoyed, Gilbert considered applying for a colonial civil service job in French Indochina. However, the outbreak of World War II that year led the family to flee to New York, where his fathers older brother, Sylvain, had already emigrated. | 0 | Theoretical and Fundamental Chemistry |
One example is the reconstruction of thioredoxin enzymes from up to 4 billion year old organisms. Whereas the chemical activity of these reconstructed enzymes were remarkably similar to modern enzymes, their physical properties showed significantly elevated thermal and acidic stability. These results were interpreted as suggesting that ancient life may have evolved in oceans that were much hotter and more acidic than today. | 1 | Applied and Interdisciplinary Chemistry |
The Hamiltonian is a function of J only, and in the simple case of the harmonic oscillator,
When H has no time dependence, J is constant. When H is slowly time-varying, the rate of change of J can be computed by re-expressing the integral for J:
The time derivative of this quantity is
Replacing time derivatives with theta derivatives, using and setting without loss of generality ( being a global multiplicative constant in the resulting time derivative of the action) yields
So as long as the coordinates J, do not change appreciably over one period, this expression can be integrated by parts to give zero. This means that for slow variations, there is no lowest-order change in the area enclosed by the orbit. This is the adiabatic invariance theorem the action variables are adiabatic invariants.
For a harmonic oscillator, the area in phase space of an orbit at energy E is the area of the ellipse of constant energy,
The x radius of this ellipse is while the p radius of the ellipse is . Multiplying, the area is . So if a pendulum is slowly drawn in, such that the frequency changes, the energy changes by a proportional amount. | 0 | Theoretical and Fundamental Chemistry |
The (n-p) reaction, or (n,p) reaction, is an example of a nuclear reaction. It is the reaction which occurs when a neutron enters a nucleus and a proton leaves the nucleus simultaneously.
For example, sulfur-32 (S) undergoes an (n,p) nuclear reaction when bombarded with neutrons, thus forming phosphorus-32 (P).
The nuclide nitrogen-14 (N) can also undergo an (n,p) nuclear reaction to produce carbon-14 (C). This nuclear reaction N (n,p) C continually happens in the Earth's atmosphere, forming equilibrium amounts of the radionuclide C.
Most (n,p) reactions have threshold neutron energies below which the reaction cannot take place as a result of the charged particle in the exit channel requiring energy (usually more than a MeV) to overcome the Coulomb barrier experienced by the emitted proton. The (n,p) nuclear reaction N (n,p) C is an exception to this rule, and is exothermic – it can take place at all incident neutron energies. The N (n,p) C nuclear reaction is responsible for most of the radiation dose delivered to the human body by thermal neutrons – these thermal neutrons are absorbed by the nitrogen N in proteins, causing a proton to be emitted; the emitted proton deposits its kinetic energy over a very short distance in the body tissue, thereby depositing radiation dose. | 0 | Theoretical and Fundamental Chemistry |
High-energy neutrons irradiating boron-10 will also occasionally produce tritium:
A more common result of boron-10 neutron capture is and a single alpha particle.
Especially in pressurized water reactors which only partially thermalize neutrons, the interaction between relatively fast neutrons and the boric acid added as a chemical shim produces small but non-negligible quantities of tritium. | 0 | Theoretical and Fundamental Chemistry |
In this example, the following sequence is a region of the human mitochondrial genome with the two overlapping genes MT-ATP8 and MT-ATP6.
When read from the beginning, these codons make sense to a ribosome and can be translated into amino acids (AA) under the vertebrate mitochondrial code:
|Start|AAC GAA AAT CTG TTC GCT TCA ...
|Start|123 123 123 123 123 123 123 ...
| AA | N E N L F A S ...
However, let's change the reading frame by starting one nucleotide downstream (effectively a "+1 frameshift" when considering the 0 position to be the initial position of A):
A|Start|ACG AAA ATC TGT TCG CTT CA...
-|Start|123 123 123 123 123 123 12...
| AA | T K I C S L ...
Because of this +1 frameshifting, the DNA sequence is read differently. The different codon reading frame therefore yields different amino acids. | 1 | Applied and Interdisciplinary Chemistry |
Hydrometallurgy refers to a specific process involving the chemical properties of water to create an aqueous solution for metal extraction through a series of chemical reactions | 1 | Applied and Interdisciplinary Chemistry |
6-(Methylsulfinyl)hexyl isothiocyanate (6-MITC or 6-MSITC) is a compound within the isothiocyanate group of organosulfur compounds. 6-MITC is obtained from cruciferous vegetables, chiefly wasabi. Like other isothiocyanates, it is produced when the enzyme myrosinase transforms the associated glucosinolate into 6-MITC upon cell injury.
It is a trend in Japan to apply freshly grated wasabi stem to the hair because Kinin Corporation, the world's largest wasabi producer, claims that 6-MITC promotes hair regrowth.
In a 2023 study of healthy older adults aged 60 years and over, the group taking one tablet (0.8 mg of 6-MSITC) every day for 12 weeks showed a significant improvement in working and episodic memory performances. These results have been reported in the popular press, using the name "hexaraphane" for 6-MSITC. | 1 | Applied and Interdisciplinary Chemistry |
By having more than one anion, many more compounds can be made, and properties tuned to desirable values.
In terms of optics, properties include phosphorescence, photocatalysis, laser damage threshold, refractive index, birefringence, absorption particularly in the ultraviolet or near infrared, non-linearity.
Mechanical properties can include ability to grow a large crystal, ability to form a thin layer, strength, or brittleness.
Thermal properties can include melting point, thermal stability, phase transition temperatures, thermal expansion coefficient.
For electrical properties, electric conductivity, band gap, superconducting transition temperature piezoelectricity, pyroelectricity, ferromagnetism, dielectric constant, charge-density wave transition can be adjusted. | 0 | Theoretical and Fundamental Chemistry |
[4+4] reactions are forbidden in the ground state and often entropically disfavored in the excited state. The mechanism of the [4+4] photocycloaddition is proposed to begin with the photoexcitation of a 1,3-diene system into the excited state. Because the orbital symmetry of the highest occupied molecular orbital (HOMO) in the excited diene is the same as that of the lowest unoccupied molecular orbital (LUMO) in another ground state diene, they are able to form an exciplex that decays to form the closed cyclooctane ring structure. Below is a Frontier Molecular Orbital diagram depicting the interaction between the two molecules of dienes. | 0 | Theoretical and Fundamental Chemistry |
Phosphinous acid (or Phosphinol) is the inorganic compound with the formula HPOH. It exists, fleetingly, as a mixture with its less stable tautomer HPO (phosphine oxide). This mixture has been generated by low temperature oxidation of phosphine with ozone. HPOH is mainly of pedagogical interest. Organophosphinous acids are more prevalent than the parent HPOH. | 0 | Theoretical and Fundamental Chemistry |
Phosphochloridites are precursors to phosphate esters:
:(RO)P(O)Cl + ROH → (RO)(RO)P(O) + HCl
Other nucleophiles have been employed, such as azide. | 0 | Theoretical and Fundamental Chemistry |
Ender's hydrazone alkylation reaction is usually run through a sequence of three steps. The first step should always be the synthesis of the hydrazones. The ketone or aldehyde is mixed with either SAMP or RAMP and allowed to react under argon for 12 hours. The crude hydrazone obtained is purified by distillation or recrystallization. At 0 degree celsius, the hydrazone is transferred into the ether solution of lithium diisopropylamide. Then this mixture is cooled down to -110 degree celsius and is slowly added the alkyl halide. This mixture is then allowed to warm up to room temperature. After 12 hours of reaction at room temperature, the crude alkylated hydrazone is allowed to react with ozone in a Schlenk tube to cleave the C=N bond. After distillation or column chromatography, pure alkylation product can be obtained. | 0 | Theoretical and Fundamental Chemistry |
In electrochemistry, electrode potential is the voltage of a galvanic cell built from a standard reference electrode and another electrode to be characterized. By convention, the reference electrode is the standard hydrogen electrode (SHE). It is defined to have a potential of zero volts. It may also be defined as the potential difference between the charged metallic rods and salt solution.
The electrode potential has its origin in the potential difference developed at the interface between the electrode and the electrolyte. It is common, for instance, to speak of the electrode potential of the redox couple. | 0 | Theoretical and Fundamental Chemistry |
Large portions of the guidelines include basic actions that would normally be included in experiments and publications regardless, such as an item for describing the experimental and control group differences. Other such information includes how many individual units are used in each group in the experiment. These two pieces are defined as essential for any study. This section also includes two desirable points, which are pointing out whether the author's laboratory itself or a core laboratory of the university or organization conducted the qPCR assay and an acknowledgement of any other individuals that contributed to the work. | 1 | Applied and Interdisciplinary Chemistry |
Deamination of adenine results in the formation of hypoxanthine. Hypoxanthine, in a manner analogous to the imine tautomer of adenine, selectively base pairs with cytosine instead of thymine. This results in a post-replicative transition mutation, where the original A-T base pair transforms into a G-C base pair. | 1 | Applied and Interdisciplinary Chemistry |
The formation of a hydroxo complex is a typical example of a hydrolysis reaction. A hydrolysis reaction is one in which a substrate reacts with water, splitting a water molecule into hydroxide and hydrogen ions. In this case the hydroxide ion then forms a complex with the substrate.
In water the concentration of hydroxide is related to the concentration of hydrogen ions by the self-ionization constant, K.
The expression for hydroxide concentration is substituted into the formation constant expression
In general, for the reaction
In the older literature the value of log K is usually cited for an hydrolysis constant. The log β value is usually cited for an hydrolysed complex with the generic chemical formula ML(OH). | 0 | Theoretical and Fundamental Chemistry |
Bitumen mixed with clay was usually called "asphaltum", but the term is less commonly used today.
In American English, "asphalt" is equivalent to the British "bitumen". However, "asphalt" is also commonly used as a shortened form of "asphalt concrete" (therefore equivalent to the British "asphalt" or "tarmac").
In Canadian English, the word "bitumen" is used to refer to the vast Canadian deposits of extremely heavy crude oil, while "asphalt" is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as "dilbit" in the Canadian petroleum industry, while bitumen "upgraded" to synthetic crude oil is known as "syncrude", and syncrude blended with bitumen is called "synbit".
"Bitumen" is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. "Bituminous rock" is a form of sandstone impregnated with bitumen. The oil sands of Alberta, Canada are a similar material.
Neither of the terms "asphalt" or "bitumen" should be confused with tar or coal tars. Tar is the thick liquid product of the dry distillation and pyrolysis of organic hydrocarbons primarily sourced from vegetation masses, whether fossilized as with coal, or freshly harvested. The majority of bitumen, on the other hand, was formed naturally when vast quantities of organic animal materials were deposited by water and buried hundreds of metres deep at the diagenetic point, where the disorganized fatty hydrocarbon molecules joined in long chains in the absence of oxygen. Bitumen occurs as a solid or highly viscous liquid. It may even be mixed in with coal deposits. Bitumen, and coal using the Bergius process, can be refined into petrols such as gasoline, and bitumen may be distilled into tar, not the other way around. | 0 | Theoretical and Fundamental Chemistry |
Tetrafluoromethane is sometimes used as a low temperature refrigerant (R-14). It is used in electronics microfabrication alone or in combination with oxygen as a plasma etchant for silicon, silicon dioxide, and silicon nitride. It also has uses in neutron detectors. | 1 | Applied and Interdisciplinary Chemistry |
*Fractional crystallization: separates ore and non-ore minerals according to their crystallization temperature. As early crystallizing minerals form from magma, they incorporate certain elements, some of which are metals. These crystals may settle onto the bottom of the intrusion, concentrating ore minerals there. Chromite and magnetite are ore minerals that form in this way.
*Liquid immiscibility: sulfide ores containing copper, nickel, or platinum may form from this process. As a magma changes, parts of it may separate from the main body of magma. Two liquids that will not mix are called immiscible; oil and water are an example. In magmas, sulfides may separate and sink below the silicate-rich part of the intrusion or be injected into the rock surrounding it. These deposits are found in mafic and ultramafic rocks. | 0 | Theoretical and Fundamental Chemistry |
ANCAs were originally described in Davies et al. in 1982 in segmental necrotising glomerulonephritis. The Second International ANCA Workshop, held in The Netherlands in May 1989, fixed the nomenclature on perinuclear vs. cytoplasmic patterns, and the antigens MPO and PR3 were discovered in 1988 and 1989, respectively. International ANCA Workshops have been carried out every two years. | 1 | Applied and Interdisciplinary Chemistry |
Peter J. H. Scott FRSC CChem (born July 27, 1979) is a British and American chemist and radiochemist who is a professor of radiology, professor of pharmacology and professor of medicinal chemistry, as well as a core member of the Rogel Cancer Center at the University of Michigan in the United States. He is Chief of Nuclear Medicine and director of the University of Michigan Positron Emission Tomography (PET) Center, and runs a research group developing new radiochemistry methodology and novel PET radiotracers. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, Bema Hapothle is an extended acronym for Bell–Marcus–Hammond–Polanyi–Thornton–Leffler, referring to the combined contribution of the theories of these chemists to the rationalization of changes in transition state structure to perturbations, such as change of reaction solvent. | 0 | Theoretical and Fundamental Chemistry |
There are polyols based on renewable sources such as plant-based materials including castor oil and cottonseed oil. Vegetable oils and biomass are also potential renewable polyol raw materials. Seed oil can even be used to produce polyester polyols. | 0 | Theoretical and Fundamental Chemistry |
While most heme proteins are attached to the prosthetic group through iron ion ligation and tertiary interactions, the heme group of cytochrome c makes thioether bonds with two cysteine side chains of the protein. One of the main properties of heme c, which allows cytochrome c to have variety of functions, is its ability to have different reduction potentials in nature. This property determines the kinetics and thermodynamics of an electron transfer reaction. | 1 | Applied and Interdisciplinary Chemistry |
It is debated whether there is a significant reduction in NEAT after beginning a structured exercise program. | 1 | Applied and Interdisciplinary Chemistry |
Center-surround antagonism refers to antagonistic interactions between center and surround regions of the receptive fields of photoreceptor cells in the retina. Center surround antagonism enables edge detection and contrast enhancement within the visual cortex. | 1 | Applied and Interdisciplinary Chemistry |
In his 50-year career, Ferrier published 180 papers, reviews and books, and gave 10 invited plenary lectures at international symposia. His reviews were of particular benefit to the chemical community but perhaps of most value was the book "Monosaccharide Chemistry, written with Dr Peter Collins in 1972 and majorly updated as "Monosaccharides: Their chemistry and their roles in natural products in 1995. | 0 | Theoretical and Fundamental Chemistry |
This is a two-scale approach which describes the superfluid component of liquid helium-4. It
consists of two nested models linked via parametric space. The short-wavelength part describes the interior structure of the fluid element using a non-perturbative approach based on the logarithmic Schrödinger equation; it suggests the Gaussian-like behaviour of the element's interior density and interparticle interaction potential. The long-wavelength part is the quantum many-body theory of such elements which deals with their dynamics and interactions. The approach provides a unified description of the phonon, maxon and roton excitations, and has noteworthy agreement with experiment: with one essential parameter to fit one reproduces at high accuracy the Landau roton spectrum, sound velocity and structure factor of superfluid helium-4. This model utilizes the general theory of quantum Bose liquids with logarithmic nonlinearities which is based on introducing a dissipative-type contribution to energy related to the quantum Everett–Hirschman entropy function. | 1 | Applied and Interdisciplinary Chemistry |
The only dose-effect relationship available are those of miners cohorts (for much higher exposures), exposed to radon. Studies of Hiroshima and Nagasaki survivors are less informative (the exposure to radon is chronic, localized, and the ionizing radiations are alpha rays).
Although low-exposed miners experienced exposures comparable to long-term residence in high-radon dwellings, the mean cumulative exposure among miners is approximately 30-fold higher than that associated with long-term residency in a typical home. Moreover, the smoking is a significant confounding factor in all miners' studies. It can be concluded from miner studies that when the radon exposure in dwellings compares to that in mines (above 1000 Bq/m), radon is a proven health hazard; but in the 1980s very little was known on the dose-effect relationship, both theoretically and statistical.
Studies have been made since the 1980s, both on epidemiological studies and in the radiobiology field.
In the radiobiology and carcinogenesis studies, progress has been made in understanding the first steps of cancer development, but not to the point of validating a reference dose-effect model. The only certainty gained is that the process is very complex, the resulting dose-effect response being complex, and most probably not a linear one.
Biologically based models have also been proposed that could project substantially reduced carcinogenicity at low doses.
In the epidemiological field, no definite conclusion has been reached. However, from the evidence now available, a threshold exposure, that is, a level of exposure below which there is no effect of radon, cannot be excluded.
Given the radon distribution observed in dwellings, and the dose-effect relationship proposed by a given model, a theoretical number of victims can be calculated, and serve as a basis for public health policies.
With the BEIR VI model, the main health effect (nearly 75% of the death toll) is to be found at low radon concentration exposures, because most of the population (about 90%) lives in the 0–200 Bq/m range. Under this modeling, the best policy is obviously to reduce the radon levels of all homes where the radon level is above average, because this leads to a significant decrease of radon exposure on a significant fraction of the population; but this effect is predicted in the 0–200 Bq/m range, where the linear model has its maximum uncertainty. From the statistical evidence available, a threshold exposure cannot be excluded; if such a threshold exists, the real radon health effect would in fact be limited to those homes where the radon concentrations reaches that observed in mines—at most a few percent. If a radiation hormesis effect exists after all, the situation would be even worse: under that hypothesis, suppressing the natural low exposure to radon (in the 0–200 Bq/m range) would actually lead to an increase of cancer incidence, due to the suppression of this (hypothetical) protecting effect. As the low-dose response is unclear, the choice of a model is very controversial.
No conclusive statistics being available for the levels of exposure usually found in homes, the risks posed by domestic exposures is usually estimated on the basis of observed lung-cancer deaths caused by higher exposures in mines, under the assumption that the risk of developing lung-cancer increases linearly as the exposure increases. This was the basis for the model proposed by BEIR IV in the 1980s. The linear no-threshold model has since been kept in a conservative approach by the UNSCEAR report and the BEIR VI and BEIR VII publications, essentially for lack of a better choice: | 1 | Applied and Interdisciplinary Chemistry |
Pakistan Engineering Council represents the engineering community in the country and assists the Government of Pakistan at the federal and provincial levels. It also acts as a think tank to the government and undertakes efforts to establish scientific standards for engineering innovations and services. Its headquarters is located in Islamabad and regional/branch/liaison offices are located in main cities of Pakistan. The council became a provisional member of Washington Accord in 2010 and was admitted as a full member in 2017.
In 2011, it became a provisional member of the International Professional Engineer (IntPE) Agreement (IPEA), and became a full member in 2018.
In March 2021, PEC signed a memorandum of understanding with the Shenzhen University to develop and apply Internet of things as part of the Belt and Road Initiative in China and Pakistan. | 1 | Applied and Interdisciplinary Chemistry |
The existence of isotopes was first suggested in 1913 by the radiochemist Frederick Soddy, based on studies of radioactive decay chains that indicated about 40 different species referred to as radioelements (i.e. radioactive elements) between uranium and lead, although the periodic table only allowed for 11 elements between lead and uranium inclusive.
Several attempts to separate these new radioelements chemically had failed. For example, Soddy had shown in 1910 that mesothorium (later shown to be Ra), radium (Ra, the longest-lived isotope), and thorium X (Ra) are impossible to separate. Attempts to place the radioelements in the periodic table led Soddy and Kazimierz Fajans independently to propose their radioactive displacement law in 1913, to the effect that alpha decay produced an element two places to the left in the periodic table, whereas beta decay emission produced an element one place to the right. Soddy recognized that emission of an alpha particle followed by two beta particles led to the formation of an element chemically identical to the initial element but with a mass four units lighter and with different radioactive properties.
Soddy proposed that several types of atoms (differing in radioactive properties) could occupy the same place in the table. For example, the alpha-decay of uranium-235 forms thorium-231, whereas the beta decay of actinium-230 forms thorium-230. The term "isotope", Greek for "at the same place", was suggested to Soddy by Margaret Todd, a Scottish physician and family friend, during a conversation in which he explained his ideas to her. He received the 1921 Nobel Prize in Chemistry in part for his work on isotopes.
In 1914 T. W. Richards found variations between the atomic weight of lead from different mineral sources, attributable to variations in isotopic composition due to different radioactive origins. | 0 | Theoretical and Fundamental Chemistry |
The relative mass spectral intensity of natural isotopologues, calculable from the fractional abundances of the constituent elements, is exploited by mass spectrometry practitioners in quantitative analysis and unknown compound identification:
# To identify the more likely molecular formulas for an unknown compound based on the matching between the observed isotope abundance pattern in an experiment and the expected isotope abundance patterns for given molecular formulas.
# To expand the linear dynamic response range of the mass spectrometer by following multiple isotopologues, with an isotopologue of lower abundance still generating linear response even while the isotopologues of higher abundance giving saturated signals. | 0 | Theoretical and Fundamental Chemistry |
The chemical reaction of lipid peroxidation consists of three phases: initiation, propagation, and termination.
In the initiation phase, a pro-oxidant hydroxyl radical () abstracts the hydrogen at the allylic position (–CH–CH=CH) or methine bridge (=CH−) on the stable lipid substrate, typically a polyunsaturated fatty acid (PUFA), to form the lipid radical () and water (HO).
In the propagation phase, the lipid radical () reacts with molecular oxygen () to form a lipid hydroperoxyl radical (). The lipid hydroperoxyl radical () can further abstract hydrogen from a new PUFA substrate, forming another lipid radical () and now finally a lipid hydroperoxide (LOOH).
The lipid hydroperoxyl radical () can also undergo a variety of reactions to produce new radicals.
The additional lipid radical () continues the chain reaction, whilst the lipid hydroperoxide (LOOH) is the primary end product. The formation of lipid radicals is sensitive to the kinetic isotope effect. Reinforced lipids in the membrane can suppress the chain reaction of lipid peroxidation.
The termination step can vary, in both its actual chemical reaction and when it will occur. Lipid peroxidation is a self-propagating chain reaction and will proceed until the lipid substrate is consumed and the last two remaining radicals combine, or a reaction which terminates it occurs. Termination can occur when two lipid hydroperoxyl radicals () react to form peroxide and oxygen (O). Termination can also occur when the concentration of radical species is high.
The primary products of lipid peroxidation are lipid hydroperoxides (LOOH). | 1 | Applied and Interdisciplinary Chemistry |
Ortho esters can be prepared by the Pinner reaction, in which nitriles react with alcohols in the presence of one equivalent of hydrogen chloride. The reaction proceeds by formation of imido ester hydrochloride:
:RCN + R′OH + HCl → [RC(OR′)=NH]Cl
Upon standing in the presence of excess alcohol, this intermediate converts to the ortho ester:
:[RC(OR′)=NH]Cl + 2R′OH → RC(OR′) + NHCl
The reaction requires anhydrous conditions.
Although a less common method, ortho esters were first produced by reaction of 1,1,1-trichloroalkanes with sodium alkoxide:
:RCCl + 3NaOR′ → RC(OR′) + 3NaCl | 0 | Theoretical and Fundamental Chemistry |
Cephalosporins are a broad class of bactericidal antibiotics that include the β-lactam ring and share a structural similarity and mechanism of action with other β-lactam antibiotics (e.g. penicillins, carbapenems and monobactams). The cephalosporins (and other β-lactams) have the ability to kill bacteria by inhibiting essential steps in the bacterial cell wall synthesis which in the end results in osmotic lysis and death of the bacterial cell. Cephalosporins are widely used antibiotics because of their clinical efficiency and desirable safety profile.
The cephalosporins are diverse in their antibacterial spectrum, water solubility, acid tolerability, oral bioavailability, biological half-life and other properties. Therefore, the cephalosporins can be further classified into generations depending on antibacterial activity, time of invention and structural basis. | 1 | Applied and Interdisciplinary Chemistry |
Organoid formation generally requires culturing the stem cells or progenitor cells in a 3D medium. Stem cells have the ability to self-renew and differentiate into various cell subtypes, and they enable understanding the processes of development and disease progression. Therefore organoids derived from stem cells enable studying biology and physiology at the organ level. The 3D medium can be made using an extracellular matrix hydrogel such as Matrigel or Cultrex BME, which is a laminin-rich extracellular matrix that is secreted by the Engelbreth-Holm-Swarm tumor line. Organoid bodies can then be made through embedding stem cells in the 3D medium. When pluripotent stem cells are used for the creation of the organoid, the cells are usually, but not all the time, allowed to form embryoid bodies. Those embryoid bodies are then pharmacologically treated with patterning factors to drive the formation of the desired organoid identity. Organoids have also been created using adult stem cells extracted from the target organ, and cultured in 3D media.
Biochemical cues have been incorporated in 3D organoid cultures and with exposure of morphogenes, morphogen inhibitors, or growth factors, organoid models can be developed using embryonic stem cells (ESCs) or adult stem cells (ASCs). Vascularization techniques can be utilized to embody microenvironments that are close to their counterparts, physiologically. Vasculature systems that can facilitate oxygen or nutrients to the inner mass of organoids can be achieved through microfluidic systems, vascular endothelial growth factor delivery systems, and endothelial cell-coated modules. With patient-derived induced pluripotent stem cells (iPSCs) and CRISPR/Cas-based genome editing technologies, genome-edited or mutated pluripotent stem cells (PSCs) with altered signaling cues can be generated to control intrinsic cues within organoids. | 1 | Applied and Interdisciplinary Chemistry |
A faster method of log P determination makes use of high-performance liquid chromatography. The log P of a solute can be determined by correlating its retention time with similar compounds with known log P values.
An advantage of this method is that it is fast (5–20 minutes per sample). However, since the value of log P is determined by linear regression, several compounds with similar structures must have known log P values, and extrapolation from one chemical class to another—applying a regression equation derived from one chemical class to a second one—may not be reliable, since each chemical classes will have its characteristic regression parameters. | 0 | Theoretical and Fundamental Chemistry |
The continuity equation describes how the density changes with time. It can be found by integration of the Vlasov equation over the entire velocity space.
After some calculations, one ends up with
The number density , and the momentum density , are zeroth and first order moments: | 1 | Applied and Interdisciplinary Chemistry |
In almost all Fe–S proteins, the Fe centers are tetrahedral and the terminal ligands are thiolato sulfur centers from cysteinyl residues. The sulfide groups are either two- or three-coordinated. Three distinct kinds of Fe–S clusters with these features are most common. | 0 | Theoretical and Fundamental Chemistry |
Oxygen is probably the most important chemical constituent of surface water chemistry, as all aerobic organisms require it for survival. It enters the water mostly via diffusion at the water-air interface. Oxygens solubility in water decreases as water temperature increases. Fast, turbulent streams expose more of the waters surface area to the air and tend to have low temperatures and thus more oxygen than slow, backwaters. Oxygen is a by-product of photosynthesis, so systems with a high abundance of aquatic algae and plants may also have high concentrations of oxygen during the day. These levels can decrease significantly during the night when primary producers switch to respiration. Oxygen can be limiting if circulation between the surface and deeper layers is poor, if the activity of animals is very high, or if there is a large amount of organic decay occurring such as following Autumn leaf-fall.
Most other atmospheric inputs come from man-made or anthropogenic sources the most significant of which are the oxides of sulphur produced by burning sulphur rich fuels such as coal and oil which give rise to acid rain. The chemistry of sulphur oxides is complex both in the atmosphere and in river systems. However the effect on the overall chemistry is simple in that it reduces the pH of the water making it more acidic. The pH change is most marked in rivers with very low concentrations of dissolved salts as these cannot buffer the effects of the acid input. Rivers downstream of major industrial conurbations are also at greatest risk. In parts of Scandinavia and West Wales and Scotland many rivers became so acidic from oxides of sulphur that most fish life was destroyed and pHs as low as pH4 were recorded during critical weather conditions. | 1 | Applied and Interdisciplinary Chemistry |
Cefroxadine can be prepared by several routes, including one in which the enol is methylated with diazomethane as a key step. A rather more involved route starts with comparatively readily available phenoxymethylpenicillin sulfoxide benzhydryl ester (1).
This undergoes fragmentation when treated with benzothiazole-2-thiol to give 2. Ozonolysis (reductive work-up) cleaves the olefinic linkage and the unsymmetrical disulfide moiety is converted to a tosyl thioester (3). The enol moiety is methylated with diazomethane, the six-membered ring is closed by reaction with 1,5-diazabicyclo[5.4.0]undec-5-ene (DBU), and the ester protection is removed with trifluoroacetic acid to give 4. The amide side chain is removed by the usual PCl/dimethylaniline sequence followed by reamidation with the appropriate acid chloride to give cefroxadine (5). | 0 | Theoretical and Fundamental Chemistry |
In fluid dynamics, the Darcy friction factor formulae are equations that allow the calculation of the Darcy friction factor, a dimensionless quantity used in the Darcy–Weisbach equation, for the description of friction losses in pipe flow as well as open-channel flow.
The Darcy friction factor is also known as the Darcy–Weisbach friction factor, resistance coefficient or simply friction factor; by definition it is four times larger than the Fanning friction factor. | 1 | Applied and Interdisciplinary Chemistry |
The benzene ligand in (η-CH)Cr(CO)Mi is prone to deprotonation. For example, Organolithium compounds form adducts featuring cyclohexadienyl ligands. Subsequent oxidation of the complex results in the release of a substituted benzene. Oxidation of the chromium atom by I and other iodine reagents has been shown to promote exchange of arene ligands, but the intermediate chromium iodide species has not been characterized.
(η-CH)Cr(CO) complexes exhibit "cine" and "tele" nucleophilic aromatic addition. Processes of this type involve reaction of (η-CH)Cr(CO) with an alkyl lithium reagent. Subsequent treatment with an acid results in the addition of a nucleophile to the benzene ring at a site ortho ("cine"), meta or para ("tele") to the ipso carbon (see Arene substitution patterns).
Reflecting its increased acidity, the benzene ligand can be lithiated with n-butyllithium. The resulting organolithium compound serves as a nucleophile in various reactions, for example, with trimethylsilyl chloride:
(η-CH)Cr(CO) is a useful catalyst for the hydrogenation of 1,3-dienes. The product alkene results from 1,4-addition of hydrogen. The complex does not hydrogenate isolated double bonds.
A variety of arenes ligands have been installed aside from benzene. Weakly coordinating ligands may be employed to improve ligand exchange and thus the turnover rates for (η-CH)M(CO) complexes.(η-CH)M(CO) complexes have been incorporated into high surface area porous materials.
(η-CH)M(CO) complexes serve as models for the interaction of metal carbonyls with graphene and carbon nanotubes. The presence of M(CO) on extended π-network materials has been shown to improve electrical conductivity across the material. | 0 | Theoretical and Fundamental Chemistry |
The Adams decarboxylation is a chemical reaction that involved the decarboxylation of coumarins which have carboxylic acid group in the third position. The decarboxylation is achieved by aqueous solution of sodium bisulfite, heat and a concentrated solution of sodium hydroxide. | 0 | Theoretical and Fundamental Chemistry |
BC200 RNA is expressed in the dendrites as ribonucleoprotein particles. Protein synthesis at the synapses of neurons contribute to neuronal plasticity and help prevent neuronal degradation. Small, non-coding RNAs such as BC200 RNA work to repress translation by inhibiting its initiation. During eukaryotic translation, the preinitiation complex binds mRNA and scans the coding strand for a start codon. This step is often subject to the control of a family of initiation factors and these factors are often a target for translational regulators. Poly(A)-binding protein (PABP) has been shown to bind to BC200 RNA further confirming their role as regulators of protein biosynthesis in synapses.
BC200 RNA targets an ATP-dependent RNA helicase called eukaryotic initiation factor 4A (eIF4A). eIF4A requires energy from ATP hydrolysis to unwind the double helix and initiate translation. However, BC200 RNA interferes with the transmission of energy after hydrolysis by changing the conformation of eIF4A, and thus the energy needed to unwind the double helix is never appropriately supplied and initiation of translation is inhibited.
This highly localized uncoupling of the ATPase activity, and subsequently the unwinding of the RNA duplex is proposed to have evolved as a result of the growing complexity of postsynaptic neurons and neuronal activities. Non-coding RNA molecules evolve at a much faster rate than gene-encoding proteins; thus, the sustained conservation of the BC200 RNA transcript indicates its importance for nervous system function. | 1 | Applied and Interdisciplinary Chemistry |
It was first observed by accident by Mike Marchywka while trying to find a selective means to etch non-diamond carbon and fabricate simple astronomical UV detection devices. These devices required a few specific features such as clean surfaces and patterned areas of non-diamond carbon but the approach has subsequently been explored as a more general means to terminate carbon surfaces and selectively clean and etch various other materials or structures. The term "Marchywka effect" is not used consistently and sometimes the term "bipolar surface treatment" is used as the substrate is induced to become a bipolar electrode. Various phrases such as "non-contacted electrochemical" process may also be used (see any references cited herein) or it may be mentioned as just an "electrochemical etch".
While this is easily confused with various common electrochemical cells, and may appear to be a trivial and obvious extension of well known methods, recent patents continue to reference prior work that cites non-contactedness as a feature. The use of a low conductivity medium as used in Marchywka et al.'s original paper is sometimes noted when it is used and may produce new effects.
The apparatus to create the effect is similar to the well-known electroporation system except that the biological specimen is replaced with an inorganic substrate, although, in some cases, organic films can be etched with this process using a surfactant solution as the electrolyte. | 0 | Theoretical and Fundamental Chemistry |
Well characterized modifications to histones include:
*Methylation
Both lysine and arginine residues are known to be methylated. Methylated lysines are the best understood marks of the histone code, as specific methylated lysine match well with gene expression states. Methylation of lysines H3K4 and H3K36 is correlated with transcriptional activation while demethylation of H3K4 is correlated with silencing of the genomic region. Methylation of lysines H3K9 and H3K27 is correlated with transcriptional repression. Particularly, H3K9me3 is highly correlated with constitutive heterochromatin.
*Acetylation - by HAT (histone acetyl transferase); deacetylation - by HDAC (histone deacetylase)
Acetylation tends to define the openness of chromatin as acetylated histones cannot pack as well together as deacetylated histones.
*Phosphorylation
*Ubiquitination
However, there are many more histone modifications, and sensitive mass spectrometry approaches have recently greatly expanded the catalog. | 1 | Applied and Interdisciplinary Chemistry |
In this situation RNA polymerase is dependent on (lagging) ribosome activity; if the ribosome pauses due to insufficient charged tRNA then the anti-terminator structure is favoured. The canonical attenuator example of the trp operon uses this mechanism in E. coli. Similar regulatory mechanisms have been found in many amino acid biosynthetic operons. | 1 | Applied and Interdisciplinary Chemistry |
In eukaryotes, genomic DNA is highly compacted in order to be able to fit it into the nucleus. This is accomplished by winding the DNA around protein octamers called histones, which has consequences for the physical accessibility of parts of the genome at any given time. Significant portions are silenced through histone modifications, and thus are inaccessible to the polymerases or their cofactors. The highest level of transcription regulation occurs through the rearrangement of histones in order to expose or sequester genes, because these processes have the ability to render entire regions of a chromosome inaccessible such as what occurs in imprinting.
Histone rearrangement is facilitated by post-translational modifications to the tails of the core histones. A wide variety of modifications can be made by enzymes such as the histone acetyltransferases (HATs), histone methyltransferases (HMTs), and histone deacetylases (HDACs), among others. These enzymes can add or remove covalent modifications such as methyl groups, acetyl groups, phosphates, and ubiquitin. Histone modifications serve to recruit other proteins which can either increase the compaction of the chromatin and sequester promoter elements, or to increase the spacing between histones and allow the association of transcription factors or polymerase on open DNA. For example, H3K27 trimethylation by the polycomb complex PRC2 causes chromosomal compaction and gene silencing. These histone modifications may be created by the cell, or inherited in an epigenetic fashion from a parent. | 1 | Applied and Interdisciplinary Chemistry |
Raymond and coworkers developed a supramolecular host ML (4 gallium ions and 6 ligands for each complex) that self-assembles via metal-ligand interaction in aqueous solution. This container molecule is polyanionic and thus its tetrahedron-shaped cavity is capable of encapsulating and stabilizing a cationic molecule. Consequently, encapsulated molecule can be easily protonated as a resulting carbocation from protonation is stabilized by the surrounding anions. Raymond utilized this property to perform acid-catalyzed Nazarov cyclization. The catalyst accelerates the reaction by over one million fold, making it the most efficient supramolecular catalyst to date. It was proposed that such a high catalytic activity does not arise just from the increased basicity of the encapsulated substrate but also from the constrictive binding that stabilize the transition state of the cyclization. Unfortunately, this catalyst has a problem with product inhibition. To by pass that problem, the product of the cyclization reaction could be reacted with a dienophile transforming it into a Diels-Alder adduct that no longer fits inside the catalyst cavity.
In this case, the supramolecular host was initially designed to simply capture cationic guests. Almost a decade later, it was exploited as a catalyst for Nazarov cyclization. | 0 | Theoretical and Fundamental Chemistry |
At very low temperatures (below 1-10 K), large family of amorphous solids have various similar low-temperature properties.
Although there are various theoretical models, neither glass transition nor low-temperature properties of glassy solids are well understood on the fundamental physics level.
Amorphous solids is an important area of condensed matter physics aiming to understand these substances at high temperatures of glass transition and at low temperatures towards absolute zero. From 1970s, low-temperature properties of amorphous solids were studied experimentally in great detail.
For all of these substances, specific heat has a (nearly) linear dependence as a function of temperature, and thermal conductivity has nearly quadratic temperature dependence. These properties are conventionally called anomalous being very different from properties of crystalline solids.
On the phenomenological level, many of these properties were described by a collection of tunneling two-level systems.
Nevertheless, the microscopic theory of these properties is still missing after more than 50 years of the research.
Remarkably, a dimensionless quantity of internal friction is nearly universal in these materials.
This quantity is a dimensionless ratio (up to a numerical constant) of the phonon wavelength to the phonon mean free path. Since the theory of tunneling two-level states (TLSs) does not address the origin of the density of TLSs, this theory cannot explain the universality of internal friction, which in turn is proportional to the density of scattering TLSs. The theoretical significance of this important and unsolved problem was highlighted by Anthony Leggett. | 0 | Theoretical and Fundamental Chemistry |
After the first bond is synthesized, the RNA polymerase must escape the promoter. During this time there is a tendency to release the RNA transcript and produce truncated transcripts. This is called abortive initiation, and is common for both eukaryotes and prokaryotes. Abortive initiation continues to occur until an RNA product of a threshold length of approximately 10 nucleotides is synthesized, at which point promoter escape occurs and a transcription elongation complex is formed.
Mechanistically, promoter escape occurs through DNA scrunching, providing the energy needed to break interactions between RNA polymerase holoenzyme and the promoter.
In bacteria, it was historically thought that the sigma factor is definitely released after promoter clearance occurs. This theory had been known as the obligate release model. However, later data showed that upon and following promoter clearance, the sigma factor is released according to a stochastic model known as the stochastic release model.
In eukaryotes, at an RNA polymerase II-dependent promoter, upon promoter clearance, TFIIH phosphorylates serine 5 on the carboxy terminal domain of RNA polymerase II, leading to the recruitment of capping enzyme (CE). The exact mechanism of how CE induces promoter clearance in eukaryotes is not yet known. | 1 | Applied and Interdisciplinary Chemistry |
Hydroxylamine (also known as hydroxyammonia) is an inorganic compound with the chemical formula . The compound is in a form of a white hygroscopic crystals. Hydroxylamine is almost always provided and used as an aqueous solution. It is consumed almost exclusively to produce Nylon-6. The oxidation of Ammonia| to hydroxylamine is a step in biological nitrification. | 0 | Theoretical and Fundamental Chemistry |
Hyperspectral imaging collects and processes information from across the electromagnetic spectrum. The goal of hyperspectral imaging is to obtain the spectrum for each pixel in the image of a scene, with the purpose of finding objects, identifying materials, or detecting processes. There are three general types of spectral imagers. There are push broom scanners and the related whisk broom scanners (spatial scanning), which read images over time, band sequential scanners (spectral scanning), which acquire images of an area at different wavelengths, and snapshot hyperspectral imagers, which uses a staring array to generate an image in an instant.
Whereas the human eye sees color of visible light in mostly three bands (long wavelengths, perceived as red; medium wavelengths, perceived as green; and short wavelengths, perceived as blue), spectral imaging divides the spectrum into many more bands. This technique of dividing images into bands can be extended beyond the visible. In hyperspectral imaging, the recorded spectra have fine wavelength resolution and cover a wide range of wavelengths. Hyperspectral imaging measures continuous spectral bands, as opposed to multiband imaging which measures spaced spectral bands.
Engineers build hyperspectral sensors and processing systems for applications in astronomy, agriculture, molecular biology, biomedical imaging, geosciences, physics, and surveillance. Hyperspectral sensors look at objects using a vast portion of the electromagnetic spectrum. Certain objects leave unique fingerprints in the electromagnetic spectrum. Known as spectral signatures, these fingerprints enable identification of the materials that make up a scanned object. For example, a spectral signature for oil helps geologists find new oil fields. | 0 | Theoretical and Fundamental Chemistry |
Dexrazoxane hydrochloride (Zinecard, Cardioxane) is a cardioprotective agent. It was discovered by Eugene Herman in 1972. The IV administration of dexrazoxane is in acidic condition with HCl adjusting the pH. | 0 | Theoretical and Fundamental Chemistry |
An emulsion dispersion is thermoplastics or elastomers suspended in a liquid state by means of emulsifiers. | 0 | Theoretical and Fundamental Chemistry |
The chemical reaction catalyzed by firefly luciferase takes place in two steps:
* luciferin + ATP → luciferyl adenylate + PP
* luciferyl adenylate + O → oxyluciferin + AMP + light
Light is produced because the reaction forms oxyluciferin in an electronically excited state. The reaction releases a photon of light as oxyluciferin goes back to the ground state.
Luciferyl adenylate can additionally participate in a side reaction with O to form hydrogen peroxide and dehydroluciferyl-AMP. About 20% of the luciferyl adenylate intermediate is oxidized in this pathway.
Firefly luciferase generates light from luciferin in a multistep process. First, D-luciferin is adenylated by MgATP to form luciferyl adenylate and pyrophosphate. After activation by ATP, luciferyl adenylate is oxidized by molecular oxygen to form a dioxetanone ring. A decarboxylation reaction forms an excited state of oxyluciferin, which tautomerizes between the keto-enol form. The reaction finally emits light as oxyluciferin returns to the ground state. | 1 | Applied and Interdisciplinary Chemistry |
A normal mode of a dynamical system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The free motion described by the normal modes takes place at fixed frequencies. These fixed frequencies of the normal modes of a system are known as its natural frequencies or resonant frequencies. A physical object, such as a building, bridge, or molecule, has a set of normal modes and their natural frequencies that depend on its structure, materials and boundary conditions.
The most general motion of a linear system is a superposition of its normal modes. The modes are normal in the sense that they can move independently, that is to say that an excitation of one mode will never cause motion of a different mode. In mathematical terms, normal modes are orthogonal to each other. | 0 | Theoretical and Fundamental Chemistry |
The enzyme phenylalanine racemase (, phenylalanine racemase, phenylalanine racemase (adenosine triphosphate-hydrolysing), gramicidin S synthetase I) is the enzyme that acts on amino acids and derivatives. It activates both the L & D stereo isomers of phenylalanine to form L-phenylalanyl adenylate and D-phenylalanyl adenylate, which are bound to the enzyme. These bound compounds are then transferred to the thiol group of the enzyme followed by conversion of its configuration, the D-isomer being the more favorable configuration of the two, with a 7 to 3 ratio between the two isomers. The racemisation reaction of phenylalanine is coupled with the highly favorable hydrolysis of adenosine triphosphate (ATP) to adenosine monophosphate (AMP) and pyrophosphate (PP), thermodynamically allowing it to proceed. This reaction is then drawn forward by further hydrolyzing PP to inorganic phosphate (P), via Le Chatelier's principle. | 1 | Applied and Interdisciplinary Chemistry |
In terms of input and output, ICP-MS instrument consumes prepared sample material and translates it into mass-spectral data. Actual analytical procedure takes some time; after that time the instrument can be switched to work on the next sample. Series of such sample measurements requires the instrument to have plasma ignited, meanwhile a number of technical parameters has to be stable in order for the results obtained to have feasibly accurate and precise interpretation. Maintaining the plasma requires a constant supply of carrier gas (usually, pure argon) and increased power consumption of the instrument. When these additional running costs are not considered justified, plasma and most of auxiliary systems can be turned off. In such standby mode only pumps are working to keep proper vacuum in mass-spectrometer.
The constituents of ICP-MS instrument are designed to allow for reproducible and/or stable operation. | 0 | Theoretical and Fundamental Chemistry |
In a gridded ion source, DC or RF discharge are used to generate ions, which are then accelerated and decimated using grids and apertures. Here, the DC discharge current or the RF discharge power are used to control the beam current.
The ion current density that can be accelerated using a gridded ion source is limited by the space charge effect, which is described by Child's law:
where is the voltage between the grids, is the distance between the grids, and is the ion mass.
The grids are placed as closely as possible to increase the current density, typically . The ions used have a significant impact on the maximum ion beam current, since . Everything else being equal, the maximum ion beam current with krypton is only 69% the maximum ion current of an argon beam, and with xenon the ratio drops to 55%. | 0 | Theoretical and Fundamental Chemistry |
Protein interference is the process where in some signaling protein interacts, either with the promoter or with some stage of the partially constructed complex, to prevent further construction of the polymerase complex, so preventing initiation. In general, this is a very rapid response and is used for fine level, individual gene control and for cascade processes for a group of genes useful under a specific conditions (for example, DNA repair genes or heat shock genes).
Chromatin structure inhibition is the process wherein the promoter is hidden by chromatin structure. Chromatin structure is controlled by post-translational modification of the histones involved and leads to gross levels of high or low transcription levels. See: chromatin, histone, and nucleosome.
These methods of control can be combined in a modular method, allowing very high specificity in transcription initiation control. | 1 | Applied and Interdisciplinary Chemistry |
* Filed: December 2, 2010. Granted: November 17, 2011.
* Filed: June 25, 2009. Granted: November 20, 2012.
* Filed: October 28, 2010. Granted: February 25, 2014.
* Filed August 10, 2012. Granted March 4, 2014. | 0 | Theoretical and Fundamental Chemistry |
Some Chinese cookware is seasoned at a much higher temperature than conventional seasoning at 450 °C. More akin to bluing, this type of seasoning mainly involves a chemical change of the iron pan itself and not the oil. When beef tallow is heated at this temperature, it evaporates on the iron surface and increases the partial pressure of O (oxygen gas) on the pot surface. This transport of oxygen encourages the formation of FeO nanoballs. The surface formed is broadly speaking hydrophobic and oleophilic, but is more versatile in that it temporarily turns hydrophilic on contact with high-water ingredients. | 0 | Theoretical and Fundamental Chemistry |
Like most fruit, grapes vary in the number of phenolic compounds they have. This characteristic is used as a parameter in judging the quality of the wine. The general process of winemaking is initiated by the enzymatic oxidation of phenolic compounds by polyphenol oxidases. Contact between the phenolic compounds in the vacuole of the grape cell and the polyphenol oxidase enzyme (located in the cytoplasm) triggers the oxidation of the grape. Thus, the initial browning of grapes occurs as a result of "compartmentalization modification" in the cells of the grape. | 1 | Applied and Interdisciplinary Chemistry |
Fosinopril is an angiotensin converting enzyme (ACE) inhibitor used for the treatment of hypertension and some types of chronic heart failure. Fosinopril is the only phosphonate-containing ACE inhibitor marketed, by Bristol-Myers Squibb under the trade name Monopril. Fosinopril is a cascading pro-drug. The special niche for the medication that differentiates it from the other members of the ACE Inhibitor drug class is that was specifically developed for the use for patients with renal impairment. This was through manipulation of the metabolism and excretion, and is seen that fifty percent of the drug is hepatobiliary cleared, which can compensate for diminished renal clearance. The remaining fifty percent is excreted in urine. It does not need dose adjustment.
It was patented in 1980 and approved for medical use in 1991. | 0 | Theoretical and Fundamental Chemistry |
In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps (decay chain). For example, U decays to Th which decays to Pa which decays, and so on, to Pb (which is stable):
In this example:
* Th, Pa,...,Pb are the decay products of U.
* Th is the daughter of the parent U.
* Pa (234 metastable) is the granddaughter of U.
These might also be referred to as the daughter products of U.
Decay products are important in understanding radioactive decay and the management of radioactive waste.
For elements above lead in atomic number, the decay chain typically ends with an isotope of lead or bismuth. Bismuth itself decays to thallium, but the decay is so slow as to be practically negligible.
In many cases, individual members of the decay chain are as radioactive as the parent, but far smaller in volume/mass. Thus, although uranium is not dangerously radioactive when pure, some pieces of naturally occurring pitchblende are quite dangerous owing to their radium-226 content, which is soluble and not a ceramic like the parent. Similarly, thorium gas mantles are very slightly radioactive when new, but become more radioactive after only a few months of storage as the daughters of Th build up.
Although it cannot be predicted whether any given atom of a radioactive substance will decay at any given time, the decay products of a radioactive substance are extremely predictable. Because of this, decay products are important to scientists in many fields who need to know the quantity or type of the parent product. Such studies are done to measure pollution levels (in and around nuclear facilities) and for other matters. | 0 | Theoretical and Fundamental Chemistry |
The malate is oxidized by NAD (the oxidizing agent) to oxaloacetate again, releasing NADH. The replenishment of oxaloacetate can be achieved. The oxaloacetate can react with the acetyl-CoA in the first step, completing a cycle. | 1 | Applied and Interdisciplinary Chemistry |
Target 2035 is a global effort or movement to discover open science, pharmacological modulator(s) for every protein in the human proteome by the year 2035. The effort is led by the Structural Genomics Consortium with the intention that this movement evolves organically. Target 2035 has been borne out of the success that chemical probes have had in elevating or de-prioritizing the therapeutic potential of protein targets. The availability of open access pharmacological tools is a largely unmet aspect of drug discovery especially for the dark proteome.
The first five years will include building mechanisms (Phase 1 below) which allow researchers to find collaborators with like-minded goals towards discovering a pharmacological tool for a specific protein or protein family, and make it open access (without encumbrances due to intellectual property). One strategic goal is seeding new open science programs on components of the drug discovery pipeline with the goal to bring medicines to the bedside equitably, affordably and rapidly. Phase 1 will also build a framework that welcomes new and (re-)emerging enabling technologies in hit-finding and characterization. An update on the progress was published.
Target 2035 will draw on successes from past and current publicly-funded programs including National Institutes of Health (NIH) [https://druggablegenome.net/index Illuminating the Druggable Genome initiative] for under-explored kinases, GPCR’s and ion channels, Innovative Medicines Initiatives [https://re-solute.eu/ RESOLUTE] project on human SLCs, Innovative Medicines Initiatives [https://www.eubopen.org/ Enabling and Unlocking Biology in the Open] (EUbOPEN), and Innovative Medicines Initiative's [https://ultra-dd.org/ Unrestricted Leveraging of Targets for Research Advancement and Drug Discovery]. The NIH recently re-iterated their commitment to making their data open to mitigate the tens of billions due to irreproducible data.
Target 2035 will collaborate with the Chemical Probes Portal and open science platforms, e.g. [https://app.jogl.io/space/target2035 Just One Giant Lab], in order to spread awareness and education of best practices for chemical modulators and the benefits of open science, respectively.
The following draft plan has been outlined in a white paper. | 1 | Applied and Interdisciplinary Chemistry |
Sertraline and amitriptyline inhibit butyrylcholinesterase and cause prolonged paralysis. Mivacurium causes prolonged paralysis for patients chronically taking sertraline. | 1 | Applied and Interdisciplinary Chemistry |
Neutral ligands do not change name with the exception of the following:
* Water, "aqua"
* Ammonia, "ammine"
* Carbon monoxide bonded via carbon, "carbonyl"
* Nitrogen monoxide bonded via nitrogen, "nitrosyl" | 0 | Theoretical and Fundamental Chemistry |
An oceanographic water mass is an identifiable body of water with a common formation history which has physical properties distinct from surrounding water. Properties include temperature, salinity, chemical - isotopic ratios, and other physical quantities which are conservative flow tracers. Water mass is also identified by its non-conservative flow tracers such as silicate, nitrate, oxygen, and phosphate.
Water masses are generally distinguished not only by their respective tracers but also by their location in the Worlds' oceans. Water masses are also distinguished by their vertical position so that there are surface water masses, intermediate water masses and deep water masses. | 0 | Theoretical and Fundamental Chemistry |
The Maxwell Garnett equation only describes the optical properties of a collection of perfectely spherical nanoparticles. However, the optical properties of nanocomposites are sensitive to the nanoparticles shape distribution. To overcome this limit, Y. Battie et al. have developed the shape distributed effective medium theory (SDEMT). This effective medium theory enables to calculate the effective dielectric function of a nanocomposite which consists in a collection of ellipsoïdal nanoparticles distributed in shape.
with
The depolarization factors () only depend on the shape of nanoparticles. is the distribution of depolarization factors.f is the volume fraction of the nanoparticles.
The SDEMT theory was used to extract the shape distribution of nanoparticles from absorption or ellipsometric spectra. | 0 | Theoretical and Fundamental Chemistry |
The peptidoglycan monomers are synthesized in the cytosol and are then attached to a membrane carrier bactoprenol. Bactoprenol transports peptidoglycan monomers across the cell membrane where they are inserted into the existing peptidoglycan.
# In the first step of peptidoglycan synthesis, glutamine, which is an amino acid, donates an amino group to a sugar, fructose 6-phosphate. This reaction, catalyzed by EC 2.6.1.16 (GlmS), turns fructose 6-phosphate into glucosamine-6-phosphate.
# In step two, an acetyl group is transferred from acetyl CoA to the amino group on the glucosamine-6-phosphate creating N-acetyl-glucosamine-6-phosphate. This reaction is EC 5.4.2.10, catalyzed by GlmM.
# In step three of the synthesis process, the N-acetyl-glucosamine-6-phosphate is isomerized, which will change N-acetyl-glucosamine-6-phosphate to N-acetyl-glucosamine-1-phosphate. This is EC 2.3.1.157, catalyzed by GlmU.
# In step 4, the N-acetyl-glucosamine-1-phosphate, which is now a monophosphate, attacks UTP. Uridine triphosphate, which is a pyrimidine nucleotide, has the ability to act as an energy source. In this particular reaction, after the monophosphate has attacked the UTP, an inorganic pyrophosphate is given off and is replaced by the monophosphate, creating UDP-N-acetylglucosamine (2,4). (When UDP is used as an energy source, it gives off an inorganic phosphate.) This initial stage, is used to create the precursor for the NAG in peptidoglycan. This is EC 2.7.7.23, also catalyzed by GlmU, which is a bifunctional enzyme.
# In step 5, some of the UDP-N-acetylglucosamine (UDP-GlcNAc) is converted to UDP-MurNAc (UDP-N-acetylmuramic acid) by the addition of a lactyl group to the glucosamine. Also in this reaction, the C3 hydroxyl group will remove a phosphate from the alpha carbon of phosphoenolpyruvate. This creates what is called an enol derivative. EC 2.5.1.7, catalyzed by MurA.
# In step 6, the enol is reduced to a "lactyl moiety" by NADPH in step six. EC 1.3.1.98, catalyzed by MurB.
# In step 7, the UDP–MurNAc is converted to UDP-MurNAc pentapeptide by the addition of five amino acids, usually including the dipeptide -alanyl--alanine. This is a string of three reactions: EC 6.3.2.8 by MurC, EC 6.3.2.9 by MurD, and EC 6.3.2.13 by MurE.
Each of these reactions requires the energy source ATP. This is all referred to as Stage one.
Stage two occurs in the cytoplasmic membrane. It is in the membrane where a lipid carrier called bactoprenol carries peptidoglycan precursors through the cell membrane.
# Undecaprenyl phosphate will attack the UDP-MurNAc penta, creating a PP-MurNac penta, which is now a lipid (lipid I). EC 2.7.8.13 by MraY.
# UDP-GlcNAc is then transported to MurNAc, creating Lipid-PP-MurNAc penta-GlcNAc (lipid II), a disaccharide, also a precursor to peptidoglycan. EC 2.4.1.227 by MurG.
# Lipid II is transported across the membrane by flippase (MurJ), a discovery made in 2014 after decades of searching. Once it is there, it is added to the growing glycan chain by the enzyme peptidoglycan glycosyltransferase (GTase, EC 2.4.1.129). This reaction is known as transglycosylation. In the reaction, the hydroxyl group of the GlcNAc will attach to the MurNAc in the glycan, which will displace the lipid-PP from the glycan chain.
# In a final step, the DD-transpeptidase (TPase, EC 3.4.16.4) crosslinks individual glycan chains. This protein is also known as the penicillin-binding protein. Some versions of the enzyme also performs the glycosyltransferase function, while others leave the job to a separate enzyme. | 1 | Applied and Interdisciplinary Chemistry |
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