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A non-profit research and testing organization, the Instrumentation Testing Association (ITA) can provide results of field testing online TOC analysers in an industrial wastewater application. Gulf Coast Waste Disposal Authority (GCWDA), Bayport Industrial Wastewater Treatment Plant in Pasadena, Texas sponsored and conducted this test in 2011. The GCWDA Bayport facility treats approximately 30 mgd of industrial waste received from approximately 65 customers (primarily petrochemical). Field tests consisted of operating online TOC analysers at the influent of the Bayport facility in which TOC concentrations can range from 490 to 1020 mg/L with an average of 870 mg/L. GCWDA conducts approximately 102 TOC analyses in their laboratory per day at their Bayport treatment facility and use TOC measurements for process control and billing purposes. GCWDA plans to use online TOC analysers for process control, detecting influent slug loads from industries and to potentially use online TOC analysers to detect and monitor volatiles of the incoming stream. Field tests were conducted for a period of 90-days and used laboratory conformance measurements once per day to compare with analyser output to demonstrate the instrument's overall accuracy when subjected to many simultaneously changing parameters as experienced in real-time monitoring conditions. Field test results can provide information regarding instrument design, operation and maintenance requirements which influence the performance of the instruments in field applications. The field test report includes evaluations of online TOC analysers utilizing the following technologies: High temperature combustion (HTC), high temperature catalytic/combustion oxidation (HTCO), supercritical water oxidation (SCWO), and two-stage advanced oxidation (TSAO). | 0 | Theoretical and Fundamental Chemistry |
The oxides of d metals such as , , dissolve at high pH to give orthometalates, , , . For and , the nature of the dissolved species at high pH is less clear, but these oxides also form polyoxometalates.
As the pH is lowered, orthometalates protonate to give oxide–hydroxide compounds such as and . These species condense via the process called olation. The replacement of terminal M=O bonds, which in fact have triple bond character, is compensated by the increase in coordination number. The nonobservation of polyoxochromate cages is rationalized by the small radius of Cr(VI), which may not accommodate octahedral coordination geometry.
Condensation of the species entails loss of water and the formation of linkages. The stoichiometry for hexamolybdate is shown:
An abbreviated condensation sequence illustrated with vanadates is:
When such acidifications are conducted in the presence of phosphate or silicate, heteropolymetalate result. For example, the phosphotungstate anion consists of a framework of twelve octahedral tungsten oxyanions surrounding a central phosphate group. | 0 | Theoretical and Fundamental Chemistry |
Stable carbenes are very reactive, and so the minimum amount of handling is desirable using air-free techniques. However, provided rigorously dry, relatively non-acidic and air-free materials are used, stable carbenes are reasonably robust to handling per se. By way of example, a stable carbene prepared from potassium hydride can be filtered through a dry celite pad to remove excess KH (and resulting salts) from the reaction. On a relatively small scale, a suspension containing a stable carbene in solution can be allowed to settle and the supernatant solution pushed through a dried membrane syringe filter. Stable carbenes are readily soluble in non-polar solvents such as hexane, and so typically recrystallisation of stable carbenes can be difficult, due to the unavailability of suitable non-acidic polar solvents. Air-free sublimation as shown right can be an effective method of purification, although temperatures below 60 °C under high vacuum are preferable as these carbenes are relatively volatile and also could begin to decompose at these higher temperatures. Indeed, sublimation in some cases can give single crystals suitable for X-ray analysis. However, strong complexation to metal ions like lithium will in most cases prevent sublimation. | 0 | Theoretical and Fundamental Chemistry |
Although less common, transition metal complexes can act as cationic photoinitiators as well. In general, the mechanism is more simplistic than the onium ions previously described. Most photoinitiators of this class consist of a metal salt with a non-nucleophilic counter anion. For example, ferrocinium salts have received much attention for commercial applications. The absorption band for ferrocinium salt derivatives are in a much longer, and sometimes visible, region. Upon radiation the metal center loses one or more ligands and these are replaced by functional groups that begin the polymerization. One of the drawbacks of this method is a greater sensitivity to oxygen. There are also several organometallic anionic photoinitiators which react through a similar mechanism. For the anionic case, excitation of a metal center is followed by either heterolytic bond cleavage or electron transfer generating the active anionic initiator. | 0 | Theoretical and Fundamental Chemistry |
The dissolved copper (Cu) ions are removed from the solution by ligand exchange solvent extraction, which leaves other ions in the solution. The copper is removed by bonding to a ligand, which is a large molecule consisting of a number of smaller groups, each possessing a lone electron pair. The ligand-copper complex is extracted from the solution using an organic solvent such as kerosene:
:Cu + 2LH(organic) → CuL(organic) + 2H
The ligand donates electrons to the copper, producing a complex - a central metal atom (copper) bonded to the ligand. Because this complex has no charge, it is no longer attracted to polar water molecules and dissolves in the kerosene, which is then easily separated from the solution. Because the initial reaction is reversible, it is determined by pH. Adding concentrated acid reverses the equation, and the copper ions go back into an aqueous solution.
Then the copper is passed through an electro-winning process to increase its purity: An electric current is passed through the resulting solution of copper ions. Because copper ions have a 2+ charge, they are attracted to the negative cathodes and collect there.
The copper can also be concentrated and separated by displacing the copper with Fe from scrap iron:
:Cu + Fe → Cu + Fe
The electrons lost by the iron are taken up by the copper. Copper is the oxidising agent (it accepts electrons), and iron is the reducing agent (it loses electrons).
Traces of precious metals such as gold may be left in the original solution. Treating the mixture with sodium cyanide in the presence of free oxygen dissolves the gold. The gold is removed from the solution by adsorbing (taking it up on the surface) to charcoal. | 1 | Applied and Interdisciplinary Chemistry |
Several GC–MS systems have left earth. Two were brought to Mars by the Viking program. Venera 11 and 12 and Pioneer Venus analysed the atmosphere of Venus with GC–MS. The Huygens probe of the Cassini–Huygens mission landed one GC–MS on Saturns largest moon, Titan. The MSL Curiosity rovers Sample analysis at Mars (SAM) instrument contains both a gas chromatograph and quadrupole mass spectrometer that can be used in tandem as a GC–MS. The material in the comet 67P/Churyumov–Gerasimenko was analysed by the Rosetta mission with a chiral GC–MS in 2014. | 0 | Theoretical and Fundamental Chemistry |
The potentially hazardous effects of methylglyoxal require regulation of the reactions with this substrate. Synthesis of methylglyoxal is regulated by levels of DHAP and phosphate concentrations. High concentrations of DHAP encourage methylglyoxal synthase to produce methylglyoxal, while high phosphate concentrations inhibit the enzyme, and therefore the production of more methylglyoxal. The enzyme triose phosphate isomerase affects the levels of DHAP by converting glyceraldehyde 3-phosphate (GAP) into DHAP. The usual pathway converting GAP to pyruvate starts with the enzyme glyceraldehyde 3-phosphate dehydrogenase ([http://mic.sgmjournals.org/cgi/reprint/151/3/707 Weber] 711–13). Low phosphate levels inhibit GAP dehydrogenase; GAP is instead converted into DHAP by triosephosphate isomerase. Again, increased levels of DHAP activate methylglyoxal synthase and methylglyoxal production ([http://mic.sgmjournals.org/cgi/reprint/151/3/707 Weber] 711–13). | 1 | Applied and Interdisciplinary Chemistry |
Much of the early understanding of transcription came from bacteria, although the extent and complexity of transcriptional regulation is greater in eukaryotes. Bacterial transcription is governed by three main sequence elements:
* Promoters are elements of DNA that may bind RNA polymerase and other proteins for the successful initiation of transcription directly upstream of the gene.
* Operators recognize repressor proteins that bind to a stretch of DNA and inhibit the transcription of the gene.
* Positive control elements that bind to DNA and incite higher levels of transcription.
While these means of transcriptional regulation also exist in eukaryotes, the transcriptional landscape is significantly more complicated both by the number of proteins involved as well as by the presence of introns and the packaging of DNA into histones.
The transcription of a basic bacterial gene is dependent on the strength of its promoter and the presence of activators or repressors. In the absence of other regulatory elements, a promoter's sequence-based affinity for RNA polymerases varies, which results in the production of different amounts of transcript. The variable affinity of RNA polymerase for different promoter sequences is related to regions of consensus sequence upstream of the transcription start site. The more nucleotides of a promoter that agree with the consensus sequence, the stronger the affinity of the promoter for RNA Polymerase likely is.
In the absence of other regulatory elements, the default state of a bacterial transcript is to be in the “on” configuration, resulting in the production of some amount of transcript. This means that transcriptional regulation in the form of protein repressors and positive control elements can either increase or decrease transcription. Repressors often physically occupy the promoter location, occluding RNA polymerase from binding. Alternatively a repressor and polymerase may bind to the DNA at the same time with a physical interaction between the repressor preventing the opening of the DNA for access to the minus strand for transcription. This strategy of control is distinct from eukaryotic transcription, whose basal state is to be off and where co-factors required for transcription initiation are highly gene dependent.
Sigma factors are specialized bacterial proteins that bind to RNA polymerases and orchestrate transcription initiation. Sigma factors act as mediators of sequence-specific transcription, such that a single sigma factor can be used for transcription of all housekeeping genes or a suite of genes the cell wishes to express in response to some external stimuli such as stress.
In addition to processes that regulate transcription at the stage of initiation, mRNA synthesis is also controlled by the rate of transcription elongation. RNA polymerase pauses occur frequently and are regulated by transcription factors, such as NusG and NusA, transcription-translation coupling, and mRNA secondary structure. | 1 | Applied and Interdisciplinary Chemistry |
Organic halides, extractable organic halides (EOX), and total organic halides (TOX) are related content for this topic. EOX provides information on how halides can be extracted using a solvent while TOX provides information about the total organic halide content in the sample. This value can be used to estimate biochemical oxygen demand (BOD) or chemical oxygen demand (COD), a key factor in estimating the required oxygen to burn the organic compounds to estimate the percentage of AOX’s and Extractable organic halides. | 1 | Applied and Interdisciplinary Chemistry |
Genome size varies among different organisms and the cloning vector must be selected accordingly. For a large genome, a vector with a large capacity should be chosen so that a relatively small number of clones are sufficient for coverage of the entire genome. However, it is often more difficult to characterize an insert contained in a higher capacity vector.
Below is a table of several kinds of vectors commonly used for genomic libraries and the insert size that each generally holds. | 1 | Applied and Interdisciplinary Chemistry |
* Dr. Vahan Simonyan and Dr. Raja Mazumder presented at the NIH Frontiers in Data Science about HIVE acting as a bridge between research and regulatory analytics. Simonyan also presented on the topic at the 2014 Bio-IT World Expo.
* HIVE was additionally discussed in FedScoop.
* Inside the HIVE, the FDA's Multi-Omics Compute Architecture, BioIT World. | 1 | Applied and Interdisciplinary Chemistry |
Magnox (magnesium non-oxidising) reactors are pressurised, carbon dioxide–cooled, graphite-moderated reactors using natural uranium (i.e. unenriched) as fuel and Magnox alloy as fuel cladding. Working pressure varies from for the steel pressure vessels, and the two reinforced concrete designs operated at . Magnox alloy consists mainly of magnesium with small amounts of aluminium and other metals—used in cladding unenriched uranium metal fuel with a non-oxidising covering to contain fission products. This material has the advantage of a low neutron capture cross-section, but has two major disadvantages:
* It limits the maximum temperature, and hence the thermal efficiency, of the plant.
* It reacts with water, preventing long-term storage of spent fuel under water - such as in a spent fuel pool.
Magnox fuel incorporated cooling fins to provide maximum heat transfer despite low operating temperatures, making it expensive to produce. While the use of uranium metal rather than oxide made nuclear reprocessing more straightforward and therefore cheaper, the need to reprocess fuel a short time after removal from the reactor meant that the fission product hazard was severe. Expensive remote handling facilities were required to address this issue. | 0 | Theoretical and Fundamental Chemistry |
In nature bacteria play a major role in the degradation of phosphonates. Due to the presence of natural phosphonates in the environment, bacteria have evolved the ability to metabolize phosphonates as nutrient sources. Some bacteria use phosphonates as a phosphorus source for growth. Aminophosphonates can also be used as sole nitrogen source by some bacteria. The polyphosphonates used in industry differ greatly from natural phosphonates such as 2-aminoethylphosphonic acid, because they are much larger, carry a high negative charge and are complexed with metals. Biodegradation tests with sludge from municipal sewage treatment plants with HEDP and NTMP showed no indication for any degradation. An investigation of HEDP, NTMP, EDTMP and DTPMP in standard biodegradation tests also failed to identify any biodegradation. It was noted, however, that in some tests due to the high sludge to phosphonate ratio, removal of the test substance from solution observed as loss of DOC was observed. This factor was attributed to adsorption rather than biodegradation. However, bacterial strains capable of degrading aminopolyphosphonates and HEDP under P-limited conditions have been isolated from soils, lakes, wastewater, activated sludge and compost.
"No biodegradation of phosphonates during water treatment is observed but photodegradation of the Fe(III)-complexes is rapid. Aminopolyphosphonates are also rapidly oxidized in the presence of Mn(II) and oxygen and stable breakdown products are formed that have been detected in wastewater. The lack of information about phosphonates in the environment is linked to analytical problems of their determination at trace concentrations in natural waters. Phosphonates are present mainly as Ca and Mg-complexes in natural waters and therefore do not affect metal speciation or transport." Phosphonates interact strongly with some surfaces, which results in a significant removal in technical and natural systems. | 0 | Theoretical and Fundamental Chemistry |
Molecular glue serves as a valuable tool in chemical biology, enabling scientists to manipulate and understand protein functions and interactions in a controlled manner. The emergence of targeted protein degradation as a modality in drug discovery has further expanded the applications of molecular glue in chemical biology. The ability of small-molecule molecular glue compounds to induce iterative cycles of target degradation provides researchers with a powerful method for studying protein-protein interactions and opens avenues for drug development in various human diseases. | 1 | Applied and Interdisciplinary Chemistry |
Granular sludge biomass is developed in sequencing batch reactors (SBR) and without carrier materials. These systems fulfil most of the requirements for their formation as:
: Feast – Famine regime: short feeding periods must be selected to create feast and famine periods (Beun et al. 1999), characterized by the presence or absence of organic matter in the liquid media, respectively. With this feeding strategy the selection of the appropriate micro-organisms to form granules is achieved. When the substrate concentration in the bulk liquid is high, the granule-former organisms can store the organic matter in form of poly-β-hydroxybutyrate to be consumed in the famine period, giving an advantage over filamentous organisms. When an anaerobic feeding is applied this factor is enhanced, minimising the importance of short settling time and higher hydrodynamic forces.
: Short settling time: This hydraulic selection pressure on the microbial community allows the retention granular biomass inside the reactor while flocculent biomass is washed-out. (Qin et al. 2004)
: Hydrodynamic shear force : Evidences show that the application of high shear forces favours the formation of aerobic granules and the physical granule integrity. It was found that aerobic granules could be formed only above a threshold shear force value in terms of superficial upflow air velocity above 1.2 cm/s in a column SBR, and more regular, rounder, and more compact aerobic granules were developed at high hydrodynamic shear forces (Tay et al., 2001 ).
Granular activated sludge is also developed in flow-through reactors using the Hybrid Activated Sludge (HYBACS) process, comprising an attached-growth reactor with short retention time upstream of a suspended growth reactor. The attached bacteria in the first reactor, known as a SMART unit, are exposed to a constant high COD, triggering the expression of high concentrations of hydrolytic enzymes in the EPS layer around the bacteria. The accelerated hydrolysis liberates soluble readily-degradable COD which promotes the formation of granular activated sludge. | 1 | Applied and Interdisciplinary Chemistry |
The fact that cells and tissues reflect the doubling of C in the atmosphere during and after nuclear testing, has been of great use for several biological studies, for forensics and even for the determination of the year in which certain wine was produced. | 0 | Theoretical and Fundamental Chemistry |
A chase nipple is a short pipe fitting, which creates a path for wires between two electrical boxes. A chase nipple has male threads on one end only. The other end is a hexagon. The chase nipple passes through the knockouts of two boxes, and is secured by an internally threaded ring called a lock nut.
Chase-Shawmut Company, of Boston, is the company which first produced chase nipples. | 1 | Applied and Interdisciplinary Chemistry |
Blood has been understood to absorb and deliver oxygen since the mid-1790s.
*vital air
*highly respirable air
*pure air
*phosoxygen
*dephlogisticated air
*empyreal air
*base of vital air
*oxy-gene means acid-former or acid-expression, once thought all acids contained oxygen. | 1 | Applied and Interdisciplinary Chemistry |
Under the framework of valence bond theory, resonance is an extension of the idea that the bonding in a chemical species can be described by a Lewis structure. For many chemical species, a single Lewis structure, consisting of atoms obeying the octet rule, possibly bearing formal charges, and connected by bonds of positive integer order, is sufficient for describing the chemical bonding and rationalizing experimentally determined molecular properties like bond lengths, angles, and dipole moment. However, in some cases, more than one Lewis structure could be drawn, and experimental properties are inconsistent with any one structure. In order to address this type of situation, several contributing structures are considered together as an average, and the molecule is said to be represented by a resonance hybrid in which several Lewis structures are used collectively to describe its true structure. For instance, in NO, nitrite anion, the two N–O bond lengths are equal, even though no single Lewis structure has two N–O bonds with the same formal bond order. However, its measured structure is consistent with a description as a resonance hybrid of the two major contributing structures shown above: it has two equal N–O bonds of 125 pm, intermediate in length between a typical N–O single bond (145 pm in hydroxylamine, HN–OH) and N–O double bond (115 pm in nitronium ion, [O=N=O]). According to the contributing structures, each N–O bond is an average of a formal single and formal double bond, leading to a true bond order of 1.5. By virtue of this averaging, the Lewis description of the bonding in NO is reconciled with the experimental fact that the anion has equivalent N–O bonds.
The resonance hybrid represents the actual molecule as the "average" of the contributing structures, with bond lengths and partial charges taking on intermediate values compared to those expected for the individual Lewis structures of the contributors, were they to exist as "real" chemical entities. The contributing structures differ only in the formal apportionment of electrons to the atoms, and not in the actual physically and chemically significant electron or spin density. While contributing structures may differ in formal bond orders and in formal charge assignments, all contributing structures must have the same number of valence electrons and the same spin multiplicity.
Because electron delocalization lowers the potential energy of a system, any species represented by a resonance hybrid is more stable than any of the (hypothetical) contributing structures. Electron delocalization stabilizes a molecule because the electrons are more evenly spread out over the molecule, decreasing electron-electron repulsion. The difference in potential energy between the actual species and the (computed) energy of the contributing structure with the lowest potential energy is called the resonance energy or delocalization energy. The magnitude of the resonance energy depends on assumptions made about the hypothetical "non-stabilized" species and the computational methods used and does not represent a measurable physical quantity, although comparisons of resonance energies computed under similar assumptions and conditions may be chemically meaningful.
Molecules with an extended π system such as linear polyenes and polyaromatic compounds are well described by resonance hybrids as well as by delocalised orbitals in molecular orbital theory. | 0 | Theoretical and Fundamental Chemistry |
An enal (or alkenal) is an organic compound containing both alkene and aldehyde functional groups. In an α,β-unsaturated enal, the alkene is conjugated to the carbonyl group of the aldehyde (formyl group). The simplest enal is acrolein (CH=CHCHO). Other examples include cis-3-hexenal (essence of mowed lawns) and cinnamaldehyde (essence of cinnamon). | 0 | Theoretical and Fundamental Chemistry |
Multiple labs identified the PRR genes as parts of the circadian clock in the 1990s. In 2000, Akinori Matsushika, Seiya Makino, Masaya Kojima, and Takeshi Mizuno were the first to understand PRR genes as pseudo-response repressor genes rather than as response regulator (ARR) genes. The factor that distinguishes PRR from ARR genes is the lack of a phospho-accepting aspartate site that characterizes ARR proteins. Though their research that discovered PRR genes was primarily hailed during the early 2000s as informing the scientific community about the function of TOC1 (named APRR1 by the Mizuno lab), an additional pseudo-response regulator in the Arabidopsis thaliana biological clock, the information about PRR genes that Matsushika and his team found deepened scientific understanding of circadian clocks in plants and led other researchers to hypothesize about the purpose of the PRR genes. Though current research has identified TOC1, PRR3, PRR5, PRR7, and PRR9 as of importance to the A. thaliana circadian clock mechanism, Matsushika et al. first categorized PRR genes into two subgroups (APRR1 and APRR2, the A stands for Arabidopsis) due to two differing amino acid structures. The negative feedback loops including PRR genes, proposed by Mizuno, were incorporated into a complex repressilator circuit by Andrew Millar’s lab in 2012. The conception of the plant biological clock as made up of interacting negative feedback loops is unique in comparison to mammal and fungal circadian clocks which contain autoregulatory negative feedback loops with positive and negative elements (see "Transcriptional and non-transcriptional control on the Circadian clock page). | 1 | Applied and Interdisciplinary Chemistry |
Indigo carmine, or 5,5′-indigodisulfonic acid sodium salt, is an organic salt derived from indigo by aromatic sulfonation, which renders the compound soluble in water. It is approved for use as a food colorant in the United States and European Union to produce a blue color. It has the E number E132, and is named Blue No. 2 by the Federal Food, Drug, and Cosmetic Act. It is also a pH indicator. | 0 | Theoretical and Fundamental Chemistry |
Within a homogeneous media such as a solution, there is no scatter. For this case, the function is linear with both the concentration of the absorbing species and the path-length. Additionally, the contributions of individual absorbing species are additive. For samples which scatter light, absorbance is defined as "the negative logarithm of one minus absorptance (absorption fraction: ) as measured on a uniform sample". For decadic absorbance, this may be symbolized as: . Even though this absorbance function is useful with scattering samples, the function does not have the same desirable characteristics as it does for non-scattering samples. There is, however, a property called absorbing power which may be estimated for these samples. The absorbing power of a single unit thickness of material making up a scattering sample is the same as the absorbance of the same thickness of the materiel in the absence of scatter. | 0 | Theoretical and Fundamental Chemistry |
Hydrolysis of a silyl enol ether results in the formation of a carbonyl compound and a disiloxane. In this reaction, water acts as an oxygen nucleophile and attacks the silicon of the silyl enol ether. This leads to the formation of the carbonyl compound and a trimethylsilanol intermediate that undergoes nucleophilic substitution at silicon (by another trimethylsilanol) to give the disiloxane. | 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 |
An example is shown where GEBIK and GEBIF equations are used to describe the isotopic reactions of consumption into according to the simultaneous set of reactions
These can be rewritten using the notation introduced before as.
The substrate has not been included due to its scarcity. In addition, we have not specified the isotopic substitution in the product of the second and third reactions because is symmetric. Assuming that the second and third reactions have identical reaction rates , , and , the full GEBIK and GEBIF equations are | 0 | Theoretical and Fundamental Chemistry |
The Coblentz Society is a non-profit scientific organization named after William Weber Coblentz which is involved in fostering the understanding and application of vibrational spectroscopy. The Society provides education, awards and recognitions enhancing the understanding of molecular (vibrational) spectroscopy. The organization was founded in 1954 and is incorporated in the state of Connecticut. Originally considered to be the Infrared Society at its founding, the Coblentz Society has expanded its technical reach into Raman spectroscopy as the technique has become more accessible to both researchers and more casual users. The Society is the oldest organization in the United States specifically dedicated to the profession and activities associated with vibrational spectroscopy. The Coblentz Society is also the infrared and Raman technical affiliate of the Society for Applied Spectroscopy.
The Awards sponsored by The Coblentz Society include:
*The Coblentz Award is to recognize the contributions by a young professional spectroscopist to the fundamental understanding of vibrational spectroscopy
*The Craver Award is to recognize the efforts of young professional spectroscopists in the field of applied analytical spectroscopy
*The Williams–Wright Award is unique in that it recognizes the lifetime accomplishments of an industrial spectroscopist
*The Bomem-Michelson Award is currently inactive but was designed to recognize advancements in the field of vibrational spectroscopy
*The Lippincott Award for the advancement of spectroscopy from an optical perspective (co-sponsored by Optica and the Society for Applied Spectroscopy). | 0 | Theoretical and Fundamental Chemistry |
In situ chemical reduction (ISCR) is a type of environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels. It is the mirror process of In Situ Chemical Oxidation (ISCO). ISCR is usually applied in the environment by injecting chemically reductive additives in liquid form into the contaminated area or placing a solid medium of chemical reductants in the path of a contaminant plume. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation.
The in situ in ISCR is just Latin for "in place", signifying that ISCR is a chemical reduction reaction that occurs at the site of the contamination. Like ISCO, it is able to decontaminate many compounds, and, in theory, ISCR could be more effective in ground water remediation than ISCO.
Chemical reduction is one half of a redox reaction, which results in the gain of electrons. One of the reactants in the reaction becomes oxidized, or loses electrons, while the other reactant becomes reduced, or gains electrons. In ISCR, reducing compounds, compounds that accept electrons given by other compounds in a reaction, are used to change the contaminants into harmless compounds.
__TOC__ | 1 | Applied and Interdisciplinary Chemistry |
Liquid slosh in microgravity is relevant to spacecraft, most commonly Earth-orbiting satellites, and must take account of liquid surface tension which can alter the shape (and thus the eigenvalues) of the liquid slug. Typically, a large fraction of the mass of a satellite is liquid propellant at/near Beginning of Life (BOL), and slosh can adversely affect satellite performance in a number of ways. For example, propellant slosh can introduce uncertainty in spacecraft attitude (pointing) which is often called jitter. Similar phenomena can cause pogo oscillation and can result in structural failure of a space vehicle.
Another example is problematic interaction with the spacecrafts Attitude Control System (ACS), especially for spinning satellites which can suffer resonance between slosh and nutation, or adverse changes to the rotational inertia. Because of these types of risk, in the 1960s the National Aeronautics and Space Administration (NASA) extensively studied liquid slosh in spacecraft tanks, and in the 1990s NASA undertook the Middeck 0-Gravity Dynamics Experiment' on the Space Shuttle. The European Space Agency has advanced these investigations with the launch of SLOSHSAT. Most spinning spacecraft since 1980 have been tested at the Applied Dynamics Laboratories drop tower using sub-scale models. Extensive contributions have also been made by the Southwest Research Institute, but research is widespread in academia and industry.
Research is continuing into slosh effects on in-space propellant depots. In October 2009, the Air Force and United Launch Alliance (ULA) performed an experimental on-orbit demonstration on a modified Centaur upper stage on the DMSP-18 satellite launch in order to improve "understanding of propellant settling and slosh", "The light weight of DMSP-18 allowed of remaining LO and LH propellant, 28% of Centaur’s capacity", for the on-orbit tests. The post-spacecraft mission extension ran 2.4 hours before the planned deorbit burn was executed.
NASA's Launch Services Program is working on two on-going slosh fluid dynamics experiments with partners: CRYOTE and SPHERES-Slosh. ULA has additional small-scale demonstrations of cryogenic fluid management are planned with project CRYOTE in 2012–2014 leading to a ULA large-scale cryo-sat propellant depot test under the NASA flagship technology demonstrations program in 2015. SPHERES-Slosh with Florida Institute of Technology and Massachusetts Institute of Technology will examine how liquids move around inside containers in microgravity with the SPHERES Testbed on the International Space Station. | 1 | Applied and Interdisciplinary Chemistry |
A tetrahedron can also be distorted by increasing the angle between two of the bonds. In the extreme case, flattening results. For carbon this phenomenon can be observed in a class of compounds called the fenestranes. | 0 | Theoretical and Fundamental Chemistry |
The Mark–Houwink equation, also known as the Mark–Houwink–Sakurada equation or the Kuhn–Mark–Houwink–Sakurada equation or the Landau–Kuhn–Mark–Houwink–Sakurada equation or the Mark-Chrystian equation gives a relation between intrinsic viscosity and molecular weight :
From this equation the molecular weight of a polymer can be determined from data on the intrinsic viscosity and vice versa.
The values of the Mark–Houwink parameters, and , depend on the particular polymer-solvent system. For solvents, a value of is indicative of a theta solvent. A value of is typical for good solvents. For most flexible polymers, . For semi-flexible polymers, . For polymers with an absolute rigid rod, such as Tobacco mosaic virus, .
It is named after Herman F. Mark and Roelof Houwink. | 0 | Theoretical and Fundamental Chemistry |
The Chézy formula describes mean flow velocity in turbulent open channel flow and is used broadly in fields related to fluid mechanics and fluid dynamics.Open channels refer to any open conduit, such as rivers, ditches, canals, or partially full pipes. The Chézy formula is defined for uniform equilibrium and non-uniform gradually varied flows.
The formula is written as:
where,
* is average velocity [length/time];
* is the hydraulic radius [length], which is the cross-sectional area of flow divided by the wetted perimeter (for a wide channel this is approximately equal to the water depth); and
* is the hydraulic gradient, which for uniform normal depth of flow is the slope of the channel bottom [unitless; length/length]; and
* is Chézy's coefficient [length/time]. The value of this coefficient must be determined by experiments. The Chézy coefficient ranges typically from 30 m/s (small rough channel) up to 90 m/s (large smooth channel).
The formula is named after Antoine de Chézy, the French hydraulics engineer who devised it in 1775.
For many years following Antoine de Chézys development of this formula, researchers assumed that was a constant independent of flow conditions. However, additional research proved the coefficients dependence upon the Reynolds number as well as channel roughness. Accordingly, although the Chézy formula does not appear to incorporate either of these terms, the Chézy coefficient empirically and indirectly represents them.
Hydraulic radius, R, is 1/4 the hydraulic diameter and is defined as the area of the flow section divided by the wetted perimeter, P. | 1 | Applied and Interdisciplinary Chemistry |
For an ideal gas, K (the bulk modulus in equations above, equivalent to C, the coefficient of stiffness in solids) is given by
Thus, from the Newton–Laplace equation above, the speed of sound in an ideal gas is given by
where
* γ is the adiabatic index also known as the isentropic expansion factor. It is the ratio of the specific heat of a gas at constant pressure to that of a gas at constant volume () and arises because a classical sound wave induces an adiabatic compression, in which the heat of the compression does not have enough time to escape the pressure pulse, and thus contributes to the pressure induced by the compression;
* p is the pressure;
* ρ is the density.
Using the ideal gas law to replace p with nRT/V, and replacing ρ with nM/V, the equation for an ideal gas becomes
where
* c is the speed of sound in an ideal gas;
* R is the molar gas constant;
* k is the Boltzmann constant;
* γ (gamma) is the adiabatic index. At room temperature, where thermal energy is fully partitioned into rotation (rotations are fully excited) but quantum effects prevent excitation of vibrational modes, the value is for diatomic gases (such as oxygen and nitrogen), according to kinetic theory. Gamma is actually experimentally measured over a range from 1.3991 to 1.403 at , for air. Gamma is exactly for monatomic gases (such as argon) and it is for triatomic molecule gases that, like , are not co-linear (a co-linear triatomic gas such as is equivalent to a diatomic gas for our purposes here);
* T is the absolute temperature;
* M is the molar mass of the gas. The mean molar mass for dry air is about ;
* n is the number of moles;
* m is the mass of a single molecule.
This equation applies only when the sound wave is a small perturbation on the ambient condition, and the certain other noted conditions are fulfilled, as noted below. Calculated values for c have been found to vary slightly from experimentally determined values.
Newton famously considered the speed of sound before most of the development of thermodynamics and so incorrectly used isothermal calculations instead of adiabatic. His result was missing the factor of γ but was otherwise correct.
Numerical substitution of the above values gives the ideal gas approximation of sound velocity for gases, which is accurate at relatively low gas pressures and densities (for air, this includes standard Earth sea-level conditions). Also, for diatomic gases the use of requires that the gas exists in a temperature range high enough that rotational heat capacity is fully excited (i.e., molecular rotation is fully used as a heat energy "partition" or reservoir); but at the same time the temperature must be low enough that molecular vibrational modes contribute no heat capacity (i.e., insignificant heat goes into vibration, as all vibrational quantum modes above the minimum-energy-mode have energies that are too high to be populated by a significant number of molecules at this temperature). For air, these conditions are fulfilled at room temperature, and also temperatures considerably below room temperature (see tables below). See the section on gases in specific heat capacity for a more complete discussion of this phenomenon.
For air, we introduce the shorthand
In addition, we switch to the Celsius temperature , which is useful to calculate air speed in the region near 0 °C (273 K). Then, for dry air,
Substituting numerical values
and using the ideal diatomic gas value of , we have
Finally, Taylor expansion of the remaining square root in yields
A graph comparing results of the two equations is to the right, using the slightly more accurate value of for the speed of sound at . | 1 | Applied and Interdisciplinary Chemistry |
Laser-induced incandescence (LII) is an in situ method of measuring aerosol particle volume fraction, primary particle sizes, and other thermophysical properties in flames, during gas-phase nanoparticle synthesis, and in aerosol streams more broadly. The technique is prominently used to characterize soot.
The technique can broadly be separated into applications involving continuous or pulsed laser sources, with the former implemented in the Single Particle Soot Photometer (SP2) and the latter used in time-resolved laser-induced incandescence (TiRe-LII) analyses. | 0 | Theoretical and Fundamental Chemistry |
There are various important electrochemical processes in both nature and industry, like the coating of objects with metals or metal oxides through electrodeposition, the addition (electroplating) or removal (electropolishing) of thin layers of metal from an object's surface, and the detection of alcohol in drunk drivers through the redox reaction of ethanol. The generation of chemical energy through photosynthesis is inherently an electrochemical process, as is production of metals like aluminum and titanium from their ores. Certain diabetes blood sugar meters measure the amount of glucose in the blood through its redox potential. In addition to established electrochemical technologies (like deep cycle lead acid batteries) there is also a wide range of new emerging technologies such as fuel cells, large format lithium-ion batteries, electrochemical reactors and super-capacitors that are becoming increasingly commercial. Electrochemical or coulometric titrations were introduced for quantitative analysis of minute quantities in 1938 by the Hungarian chemists László Szebellédy and Zoltan Somogyi. Electrochemistry also has important applications in the food industry, like the assessment of food/package interactions, the analysis of milk composition, the characterization and the determination of the freezing end-point of ice-cream mixes, or the determination of free acidity in olive oil. | 0 | Theoretical and Fundamental Chemistry |
Several compounds are known to promote the opening or activation of specific ion channels. These are classified by the channel on which they act:
*Calcium channel openers, such as Bay K8644
*Chloride channel openers, such as phenanthroline
*Potassium channel openers, such as minoxidil
*Sodium channel openers, such as DDT | 1 | Applied and Interdisciplinary Chemistry |
The deformation field at the slip-band is due to three-dimensional elastic and plastic strains where the concentrated shear of the slip band tip deforms the grain in its vicinity. The elastic strains describe the stress concentration ahead of the slip band, which is important as it can affect the transfer of plastic deformation across grain boundaries. An understanding of this is needed to support the study of yield and inter/intra-granular fracture. The concentrated shear of slip bands can also nucleate cracks in the plane of the slip band, and persistent slip bands that lead to intragranular fatigue crack initiation and growth may also form under cyclic loading conditions. To properly characterise slip bands and validate mechanistic models for their interactions with microstructure, it is crucial to quantify the local deformation fields associated with their propagation. However, little attention has been given to slip bands within grains (i.e., in the absence of grain boundary interaction).
The long-range stress field (i.e., the elastic strain field) around the tip of a stress concentrator, such as a slip band, can be considered a singularity equivalent to that of a crack. This singularity can be quantified using a path independent integral since it satisfies the conservation laws of elasticity. The conservation laws of elasticity related to translational, rotational, and scaling symmetries were derived initially by Knowles and Sternberg from the Noether's theorem. Budiansky and Rice introduced the J-, M-, L-integral and were the first to give them a physical interpretation as the strain energy-release rates for mechanisms such as cavity propagation, simultaneous uniform expansion, and defect rotation, respectively. When evaluated over a surface that encloses a defect, these conservation integrals represent a configurational force on the defect. That work paved the way for the field of Configurational mechanics of materials, with the path-independent J-integral now widely used to analyse the configurational forces in problems as diverse as dislocation dynamics, misfitting inclusions, propagation of cracks, shear deformation of clays, and co-planar dislocation nucleation from shear loaded cracks. The integrals have been applied to linear elastic and elastic-plastic materials and have been coupled with processes such as thermal and electrochemical loading, and internal tractions. Recently, experimental fracture mechanics studies have used full-field in situ measurements of displacements and elastic strains to evaluate the local deformation field surrounding the crack tip as a J-integral.
Slip bands form due to plastic deformation, and the analysis of the force on a dislocation considers the two-dimensional nature of the dislocation line defect. General definitions of the Peach–Koehler configurational force (𝑃) (or the elastic energy-momentum tensor ) on a dislocation in the arbitrary 𝑥, 𝑥, 𝑥 coordinate system, decompose the Burgers vector (𝑏) to orthogonal components. This leads to the generalised definition of the J-integral in equations below. For a dislocation pile-up, the J-integral is the summation of the Peach–Koehler configurational force of the dislocations in the pile-up (including out-of-plane, 𝑏 ).
𝐽 = ∫ 𝑃 𝑛 𝑑𝑆 = ∫(𝑊 𝑛− 𝑇 𝑢) 𝑑𝑆
𝐽 = 𝑅 𝐽, 𝑖,𝑗,𝑘=1,2,3
where 𝑆 is an arbitrary contour around the dislocation pile-up with unit outward normal 𝑛, 𝑊 is the strain energy density, 𝑇 = 𝜎 𝑛 is the traction on 𝑑𝑆, 𝑢 are the displacement vector components, 𝐽 is 𝐽-integral evaluated along the 𝑥 direction, and 𝑅 is a second-order mapping tensor that maps 𝐽 into 𝑥 direction. This vectorial 𝐽-integral leads to numerical difficulties in the analysis since 𝐽 and, for a three-dimensional slip band or inclined crack, the 𝐽 terms cannot be neglected. | 1 | Applied and Interdisciplinary Chemistry |
The lac repressor is a four-part protein, a tetramer, with identical subunits. Each subunit contains a helix-turn-helix (HTH) motif capable of binding to DNA. The operator site where repressor binds is a DNA sequence with inverted repeat symmetry. The two DNA half-sites of the operator together bind to two of the subunits of the repressor. Although the other two subunits of repressor are not doing anything in this model, this property was not understood for many years.
Eventually it was discovered that two additional operators are involved in lac regulation. One (O) lies about −90 bp upstream of O in the end of the lacI gene, and the other (O) is about +410 bp downstream of O in the early part of lacZ. These two sites were not found in the early work because they have redundant functions and individual mutations do not affect repression very much. Single mutations to either O or O have only 2 to 3-fold effects. However, their importance is demonstrated by the fact that a double mutant defective in both O and O is dramatically de-repressed (by about 70-fold).
In the current model, lac repressor is bound simultaneously to both the main operator O and to either O or O. The intervening DNA loops out from the complex. The redundant nature of the two minor operators suggests that it is not a specific looped complex that is important. One idea is that the system works through tethering; if bound repressor releases from O momentarily, binding to a minor operator keeps it in the vicinity, so that it may rebind quickly. This would increase the affinity of repressor for O. | 1 | Applied and Interdisciplinary Chemistry |
The International Radon Project (IRP) is a World Health Organization initiative to reduce the lung cancer risk around the world.
The IRP released their guidance to member countries in September 2009.
Exposure to radon in the home and workplace is one of the main risks of ionizing radiation causing tens of thousands of deaths from lung cancer each year globally. In order to reduce this burden it is important that national authorities have methods and tools based on solid scientific evidence and sound public health policy. The public needs to be aware of radon risks and the means to reduce and prevent these.
In 1996, WHO published a report containing several conclusions and recommendations covering the scientific understanding of radon risk and the need for countries to take action in the areas of risk management and risk communication.
Recent findings from case-control studies on lung cancer and exposure to radon in homes completed in many countries allow for substantial improvement in risk estimates and for further consolidation of knowledge by pooling data from these studies. The consistency of the findings from the latest pooled analyses of case-control studies from Europe and North America as well as China provides a strong argument for an international initiative to reduce indoor radon risks.
To fulfill these goals, WHO has developed a program on public health aspects of radon exposure. This project enjoys high priority with WHO's Department of Public Health and Environment. The key elements of the International Radon Project include:
*Estimation of the global burden of disease (GBD) associated with exposure to radon, based on the establishment of a global radon database
*Provision of guidance on methods for radon measurements and mitigation
*Developing evidence-based public health guidance for Member States to formulate policy and advocacy strategy including the establishment of radon action levels
*Development of approaches for radon risk communication.
To achieve these aims, WHO has formed a network of key partner agencies from some 40 Member States. This network is the basis for the WHO International Radon Project which was launched in 2005. Working groups will collect and analyse information on radon risk, radon policies, radon mitigation and prevention as well as risk communication. The project members meet regularly and work towards achieving the outlined objectives. | 0 | Theoretical and Fundamental Chemistry |
General function of TFH:
# Initiation transcription of protein- coding gene.
# DNA nucleotide repairing.
(NER)TFH is a general transcription factor that acts to recruit RNA Pol II to the promoters of genes. It functions as a helicase that unwinds DNA. It also unwinds DNA after a DNA lesion has been recognized by either the global genome repair (GGR) pathway or the transcription-coupled repair (TCR) pathway of NER. Purified TFH has role in stopping further RNA synthesis by activating the cyclic peptide α-amanitin. | 1 | Applied and Interdisciplinary Chemistry |
Hydrolysis is one of the primary reactions to occur in diboryl porphyrin complexes. In this reaction, RBOBR(por) reacts with water to exchange a B-OH bond for a B-R bond, liberating the R group.
Hydrolysis products are important intermediates in the synthesis of the B-O-B(por) compounds from BX(por) compounds. In fact, simply performing column chromatography on (BF)(por) on silica gives the partial hydrolysis product BOF(por).
DFT computations show that hydrolysis, as in the scheme shown here, is energetically favorable (breaking of a relatively weak B-C bond, formation of a strong B-O bond, formation of benzene). However, only one of the two phenyl groups is observed to undergo hydrolysis. This suggests thermodynamic favorability is not the only factor at play. Rather, as Belcher et al. suggest, there is a significant steric component to this reaction. The boron in the porphyrin ring plane undergoes substitution, while the out-of-plane boron retains its phenyl bond. | 0 | Theoretical and Fundamental Chemistry |
The attraction between cationic and anionic sites is a noncovalent, or intermolecular interaction which is usually referred to as ion pairing or salt bridge.
It is essentially due to electrostatic forces, although in aqueous medium the association is driven by entropy and often even endothermic. Most salts form crystals with characteristic distances between the ions; in contrast to many other noncovalent interactions, salt bridges are not directional and show in the solid state usually contact determined only by the van der Waals radii of the ions.
Inorganic as well as organic ions display in water at moderate ionic strength I similar salt bridge as association ΔG values around 5 to 6 kJ/mol for a 1:1 combination of anion and cation, almost independent of the nature (size, polarizability, etc.) of the ions. The ΔG values are additive and approximately a linear function of the charges, the interaction of e.g. a doubly charged phosphate anion with a single charged ammonium cation accounts for about 2x5 = 10 kJ/mol. The ΔG values depend on the ionic strength I of the solution, as described by the Debye-Hückel equation, at zero ionic strength one observes ΔG = 8 kJ/mol. | 0 | Theoretical and Fundamental Chemistry |
In the US, the EPA issued a health advisory in 2015. A ten day Health Advisory was calculated for different ages which is considered protective of non-carcinogenic adverse health effects over a ten-day exposure to microcystins in drinking water: 0.3 μg/L for bottle-fed infants and young children of pre-school age and 1.6 μg/L for children of school age through adults. | 1 | Applied and Interdisciplinary Chemistry |
Square pyramidal geometry describes the shape of certain chemical compounds with the formula where L is a ligand. If the ligand atoms were connected, the resulting shape would be that of a pyramid with a square base. The point group symmetry involved is of type C. The geometry is common for certain main group compounds that have a stereochemically-active lone pair, as described by VSEPR theory. Certain compounds crystallize in both the trigonal bipyramidal and the square pyramidal structures, notably . | 0 | Theoretical and Fundamental Chemistry |
The analogous problem in cylindrical geometry corresponding to an axisymmetric blast wave can be solved analytically. This problem was solved independently by Leonid Sedov, A. Sakurai and S. C. Lin. | 1 | Applied and Interdisciplinary Chemistry |
A balloon is an inflatable flexible filled with air and also gas, such as helium, hydrogen, nitrous oxide or oxygen. Modern balloons can be made from materials such as latex rubber, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders . Latex rubber balloons may be used as inexpensive childrens toys or decorations, while others are used for practical purposes such as meteorology, medical treatment, military defense, or transportation. A balloons properties, including its low density and low cost, have led to a wide range of applications. The inventor of the natural latex rubber balloon, (the most common balloon) was Michael Faraday in 1824, via experiments with air and various gases. | 1 | Applied and Interdisciplinary Chemistry |
Umaswati, in chapter 8 of Tattvartha Sutra presents his sutras on how karma affects rebirths. He asserts that accumulated karma in life determines the length of life and realm of rebirth for each soul in each of four states – infernal beings, plants and animals, human beings and as gods. Further, states Umaswati, karma also affects the body, the shape, the characteristics as well as the status of the soul within the same species, such as Ucchi (upper) or Nicchi (lower) status. The accumulated and new karma are material particles, states Umaswati, which stick to the soul and these travel with the soul from one life to the next as bondage, where each ripens. Once ripened, the karmic particles fall off, states Umaswati. | 1 | Applied and Interdisciplinary Chemistry |
dPCR’s ability to detect rare mutations may be of particular benefit in the clinic through the use of the liquid biopsy, a generally noninvasive strategy for detecting and monitoring disease via bodily fluids. Researchers have used liquid biopsy to monitor tumor load, treatment response and disease progression in cancer patients by measuring rare mutations in circulating tumor DNA (ctDNA) in a variety of biological fluids from patients including blood, urine and cerebrospinal fluid. Early detection of ctDNA (as in molecular relapse) may lead to earlier administration of an immunotherapy or a targeted therapy specific for the patient’s mutation signature, potentially improving chances of the treatment’s effectiveness rather than waiting for clinical relapse before altering treatment. Liquid biopsies can have turnaround times of a few days, compared to two to four weeks or longer for tissue-based tests. This reduced time to results has been used by physicians to expedite treatments tailored to biopsy data.
In 2016, a prospective trial using dPCR at the Dana-Farber Cancer Institute authenticated the clinical benefit of liquid biopsy as a predictive diagnostic tool for patients with non-small-cell lung cancer. The application of liquid biopsy tests have also been studied in patients with breast, colorectal, gynecologic, and bladder cancers to monitor both the disease load and the tumor’s response to treatment. | 1 | Applied and Interdisciplinary Chemistry |
Compressor performance changes, day to day, with changes in the ambient pressure and temperature. Woolenweber shows the change in performance of a turbocharger compressor when the inlet temperature varies between 70 and 100 deg F. In the case of aircraft compressors, inlet pressure and temperature also change with altitude and airspeed. The presentation of different performance for every combination of inlet temperature and pressure would be unmanageable but it is possible to collapse it all onto a single map, which is applicable to a wide range of inlet conditions, using dimensional analysis. In dimensional analysis individual quantities such as rotor speed, mass flow and delivery pressure are each grouped with other relevant quantities in such a way that the groups have no dimensions but still have a physical meaning. For example rotor speed , inlet temperature , compressor diameter and gas properties and are grouped together as dimensionless which is equivalent to the blade mach number.
Parameter groups which are used as the basis for gas turbine engine compressor maps are total-pressure ratio (P/P), <math>w
\sqrt{\gamma \ R \ T}/{AP} and efficiency. , for example, is simplified below while still being representative of mach number. Maps for other applications use head or discharge pressure and volume flow.
For a particular compressor and gas the flow and speed groups are simplified, by deleting the terms which are constant for a particular compressor and application, namely compressor dimensions and gas properties , , and . They are named pseudo-non-dimensional parameters and .
A final step is to give the pseudo-non-dimensional parameters standard units for mass flow and speed and more recognizable numerical values by applying pressure and temperature ratio correction factors, also derived as part of the dimensional analysis.
The corrected parameters are and . They have the same units as the original observed values and are corrected to agreed standard conditions, the International Standard Atmosphere at sea level (ISA SL). Alternatively they may be shown relative to the design value where the design value is specified as either 100% or 1.0.
The fuel burned in a gas turbine engine sets the compressor running line and also has to be used in non-dimensional form to show its effect on engine operation. It is used as a ratio with combustor pressure when shown on a compressor map. Corrected fuel flow is shown as . Although both air and fuel are flows of fluid their non-dimensional parameters are different, and , because non-dimensional airflow is a form of fluid Mach number while fuel is flow of an incompressible energy source. The dimensions of airflow are M/t and those of fuel-flow are ML/t, where M, L and t are mass, length and time.
Fuel flow is also shown on a compressor map, but in the form of its effect, ie turbine inlet temperature. This effect is shown, again non-dimensionally, as the ratio of turbine inlet temperature to compressor inlet temperature, and known as engine temperature ratio. Grandcoing shows the constant temperature lines crossed as a helicopter compressor goes from no-load to full-load with increasing fuel flow. | 0 | Theoretical and Fundamental Chemistry |
The name is a dual reference to eastern blot and the geographical concept of the Far East (which includes Japan). | 1 | Applied and Interdisciplinary Chemistry |
Splicing of all intron-containing RNA molecules is superficially similar, as described above. However, different types of introns were identified through the examination of intron structure by DNA sequence analysis, together with genetic and biochemical analysis of RNA splicing reactions. At least four distinct classes of introns have been identified:
*Introns in nuclear protein-coding genes that are removed by spliceosomes (spliceosomal introns)
* Introns in nuclear and archaeal transfer RNA genes that are removed by proteins (tRNA introns)
* Self-splicing group I introns that are removed by RNA catalysis
* Self-splicing group II introns that are removed by RNA catalysis
Group III introns are proposed to be a fifth family, but little is known about the biochemical apparatus that mediates their splicing. They appear to be related to group II introns, and possibly to spliceosomal introns. | 1 | Applied and Interdisciplinary Chemistry |
When exposed to air, warmth and light (especially without antioxidants), the oil loses its taste and psychoactivity due to aging. Cannabinoid carboxylic acids (THCA, CBDA, and maybe others) have an antibiotic effect on gram-positive bacteria such as (penicillin-resistant) Staphylococcus aureus, but gram-negative bacteria such as Escherichia coli are unaffected. | 0 | Theoretical and Fundamental Chemistry |
Like ammonia, amines are bases. Compared to alkali metal hydroxides, amines are weaker.
The basicity of amines depends on:
# The electronic properties of the substituents (alkyl groups enhance the basicity, aryl groups diminish it).
# The degree of solvation of the protonated amine, which includes steric hindrance by the groups on nitrogen. | 0 | Theoretical and Fundamental Chemistry |
* Roberto Todeschini, Viviana Consonni, Raimund Mannhold, Hugo Kubinyi & Hendrik Timmerman, 2008, "Entry: Electronic substituent constants (Hammet substituent constants, σ electronic constants)," in Handbook of Molecular Descriptors, Vol. 11 of Methods and Principles in Medicinal Chemistry (book series), pp. 144–157, New York, NY, US: John Wiley & Sons, , see [https://books.google.com/books?isbn=3527613110], accessed 22 June 2015.
* N. Chapman, 2012, Correlation Analysis in Chemistry: Recent Advances, New York, NY, US: Springer Science & Business, , see [https://books.google.com/books?isbn=1461588316], accessed 22 June 2015. | 0 | Theoretical and Fundamental Chemistry |
Deuterium-depleted water can be produced in laboratories and factories. Various technologies are used for its production, such as electrolysis, distillation (low-temperature vacuum rectification), desalination from seawater, Girdler sulfide process, and catalytic exchange. | 0 | Theoretical and Fundamental Chemistry |
The planetary equilibrium temperature is a theoretical temperature that a planet would be if it was in radiative equilibrium, typically under the assumption that it radiates as a black body being heated only by its parent star. In this model, the presence or absence of an atmosphere (and therefore any greenhouse effect) is irrelevant, as the equilibrium temperature is calculated purely from a balance with incident stellar energy.
Other authors use different names for this concept, such as equivalent blackbody temperature of a planet. The effective radiation emission temperature is a related concept, but focuses on the actual power radiated rather than on the power being received, and so may have a different value if the planet has an internal energy source or when the planet is not in radiative equilibrium.
Planetary equilibrium temperature differs from the global mean temperature and surface air temperature, which are measured observationally by satellites or surface-based instruments, and may be warmer than the equilibrium temperature due to the greenhouse effect. | 0 | Theoretical and Fundamental Chemistry |
Mutations in this gene are associated with glycogen storage disease type IV (also known as Andersen's disease) in newborns and with adult polyglucosan body disease.
Approximately 40 mutations in the GBE1 gene, most resulting in a point mutation in the glycogen branching enzyme, have led to the early childhood disorder, glycogen storage disease type IV (GSD IV). This disease is characterized by a severe depletion or complete absence of GBE, resulting in the accumulation of abnormally structured glycogen, known as polyglucosan bodies. Glycogen buildup leads to increased osmotic pressure resulting in cellular swelling and death. The tissues most affected by this disease are the liver, heart, and neuromuscular system, areas with the greatest levels of glycogen accumulation. Abnormal glycogen buildup in the liver interferes with liver functioning and can result in an enlarged liver and liver disease. In muscles, the inability of cells to efficiently breakdown glycogen due to the severe reduction or absence of branching can lead to muscle weakness and atrophy.
At least three mutations in the GBE1 gene have been found to cause another disease called adult polyglucosan body disease (APBD). While in GSD IV GBE activity is undetectable or minimally detectable, APBD is characterized by reduced or even normal GBE activity. In this disease, abnormal glycogen can build up in neurons leading to a spectrum of problems. Specifically, some disease characteristics are gait difficulties from mixed upper and lower motor neuron involvement sensory loss in lower extremities, and neurogenic bladder, a problem in which a person lacks bladder control due to a brain, spinal cord, or nerve condition. | 1 | Applied and Interdisciplinary Chemistry |
The fundamental series is a set of spectral lines in a set caused by transition between d and f orbitals in atoms.
Originally the series was discovered in the infrared by Fowler and independently by Arno Bergmann. This resulted in the name Bergmann series used for such a set of lines in a spectrum. However the name was changed as Bergmann also discovered other series of lines. And other discoverers also established other such series. They became known as the fundamental series. Bergmann observed lithium at 5347 cm, sodium at 5416 cm potassium at 6592 cm. Bergmann observed that the lines in the series in the caesium spectrum were double. His discovery was announced in Contributions to the Knowledge of the Infra-Red Emission Spectra of the Alkalies, Jena 1907. Carl Runge called this series the "new series". He predicted that the lines of potassium and rubidium would be in pairs. He expressed the frequencies of the series lines by a formula and predicted a connection of the series limit to the other known series. In 1909 W. M. Hicks produced approximate formulas for the various series and noticed that this series had a simpler formula than the others and thus called it the "fundamental series" and used the letter F.
The formula that more resembled the hydrogen spectrum calculations was because of a smaller quantum defect. There is no physical basis to call this fundamental. The fundamental series was described as badly-named. It is the last spectroscopic series to have a special designation. The next series involving transitions between F and G subshells is known as the FG series.
Frequencies of the lines in the series are given by this formula:
R is the Rydberg constant, is the series limit, represented by 3D, and is represented by mF. A shortened formula is then given by with values of m being integers from 4 upwards. The two numbers separated by the "−" are called terms, that represent the energy level of an atom.
The limit of the fundamental series is the same as the 3D level.
The terms can have different designations, mF for single line systems, mΦ for doublets and mf for triplets.
Lines in the fundamental series are split into compound doublets, due to the D and F subshells having different spin possibilities. The splitting of the D subshell is very small and that of the F subshell even less so, so the fine structure in the fundamental series is harder to resolve than that in the sharp or diffuse series. | 0 | Theoretical and Fundamental Chemistry |
Plants under horticultural care in a constructed landscape, typically a botanic garden or arboreta. This technique is similar to a field gene bank in that plants are maintained in the ambient environment, but the collections are typically not as genetically diverse or extensive. These collections are susceptible to hybridization, artificial selection, genetic drift, and disease transmission. Species that cannot be conserved by other ex situ techniques are often included in cultivated collections. | 1 | Applied and Interdisciplinary Chemistry |
The Brinkman number (Br) is a dimensionless number related to heat conduction from a wall to a flowing viscous fluid, commonly used in polymer processing. It is named after the Dutch mathematician and physicist Henri Brinkman. There are several definitions; one is
where
* μ is the dynamic viscosity;
* u is the flow velocity;
* κ is the thermal conductivity;
* T is the bulk fluid temperature;
* T is the wall temperature;
* Pr is the Prandtl number
* Ec is the Eckert number
It is the ratio between heat produced by viscous dissipation and heat transported by molecular conduction. i.e., the ratio of viscous heat generation to external heating. The higher its value, the slower the conduction of heat produced by viscous dissipation and hence the larger the temperature rise.
In, for example, a screw extruder, the energy supplied to the polymer melt comes primarily from two sources:
* viscous heat generated by shear between elements of the flowing liquid moving at different velocities;
* direct heat conduction from the wall of the extruder.
The former is supplied by the motor turning the screw, the latter by heaters. The Brinkman number is a measure of the ratio of the two. | 0 | Theoretical and Fundamental Chemistry |
SLS is used in an improved technique for preparing brain tissues for study by optical microscopy. The technique, which has been branded as CLARITY, was the work of Karl Deisseroth and coworkers at Stanford University, and involves infusion of the organ with an acrylamide solution to bind the macromolecules of the organ (proteins, nucleic acids, etc.), followed by thermal polymerization to form a "brain–hydrogel" (a mesh interspersed throughout the tissue to fix the macromolecules and other structures in space), and then by lipid removal using SDS to eliminate light scattering with minimal protein loss, rendering the tissue quasi-transparent.
Along with sodium dodecylbenzene sulfonate and Triton X-100, aqueous solutions of SDS are popular for dispersing or suspending nanotubes, such as carbon nanotubes. | 1 | Applied and Interdisciplinary Chemistry |
The microscopic "reversing of time" turns at the kinetic level into the "reversing of arrows": the elementary processes transform into their reverse processes. For example, the reaction
: transforms into
and conversely. (Here, are symbols of components or states, are coefficients). The equilibrium ensemble should be invariant with respect to this transformation because of microreversibility and the uniqueness of thermodynamic equilibrium. This leads us immediately to the concept of detailed balance: each process is equilibrated by its reverse process.
This reasoning is based on three assumptions:
# does not change under time reversal;
# Equilibrium is invariant under time reversal;
# The macroscopic elementary processes are microscopically distinguishable. That is, they represent disjoint sets of microscopic events.
Any of these assumptions may be violated. For example, Boltzmanns collision can be represented as where is a particle with velocity v. Under time reversal transforms into . Therefore, the collision is transformed into the reverse collision by the PT transformation, where P is the space inversion and T is the time reversal. Detailed balance for Boltzmanns equation requires PT-invariance of collisions dynamics, not just T'-invariance. Indeed, after the time reversal the collision transforms into For the detailed balance we need transformation into
For this purpose, we need to apply additionally the space reversal P. Therefore, for the detailed balance in Boltzmanns equation not T-invariance but PT'-invariance is needed.
Equilibrium may be not T- or PT-invariant even if the laws of motion are invariant. This non-invariance may be caused by the spontaneous symmetry breaking. There exist nonreciprocal media (for example, some bi-isotropic materials) without T and PT invariance.
If different macroscopic processes are sampled from the same elementary microscopic events then macroscopic detailed balance may be violated even when microscopic detailed balance holds.
Now, after almost 150 years of development, the scope of validity and the violations of detailed balance in kinetics seem to be clear. | 0 | Theoretical and Fundamental Chemistry |
* U.S. National Academy of Sciences, 1961
* American Academy of Arts and Sciences, 1962
* Foreign Member of the French Academy of Sciences, 1989
* American Philosophical Society, 1995
* The Royal Society, UK 1999 | 0 | Theoretical and Fundamental Chemistry |
Paints, inks, and dyes that are organic are more susceptible to photodegradation than those that are not. Ceramics are almost universally colored with non-organic origin materials so as to allow the material to resist photodegradation even under the most relentless conditions, maintaining its color. | 0 | Theoretical and Fundamental Chemistry |
The active component, eslicarbazepine, has the same mechanism of action as oxcarbazepine (which is a prodrug for licarbazepine, the racemate of eslicarbazepine) and most likely the closely related carbamazepine. It stabilises the inactive state of voltage-gated sodium channels, allowing for less sodium to enter neural cells, which leaves them less excitable. According to some sources, it has not been shown conclusively that this is the actual mechanism. | 0 | Theoretical and Fundamental Chemistry |
Typically, single chain cyclized/knotted polymers are synthesized by deactivation enhanced ATRP of multivinyl monomers via kinetically controlled strategy. There are several main reactions during this polymerization process: initiation, activation, deactivation, chain propagation, intramolecular cyclization and intermolecular crosslinking. The polymerization process is explained in Figure 2.
In a similar way to normal ATRP, the polymerization is started by initiation to produce a free radical, followed by chain propagation and reversible activation/deactivation equilibrium. Unlike the polymerization of single vinyl monomers, for the polymerization of multivinyl monomers, the chain propagation occurs between the active centres and one of the vinyl groups from the free monomers. Therefore, multiple unreacted pendent vinyl groups are introduced into the linear primary polymer chains, resulting in a high local/spatial vinyl concentration. As the chain grows, the propagating centre reacts with their own pendent vinyl groups to form intramolecular cyclized rings (i.e. intramolecular cyclization). The unique alternating chain propagation/intramolecular cyclization process eventually leads to the single chain cyclized/knotted polymer architecture. | 0 | Theoretical and Fundamental Chemistry |
Several human and yeast snRNP structures were determined by the cryo-electron microscopy and successive single particle analysis.
Recently, the human U1 snRNP core structure was determined by X-ray crystallography (3CW1, 3PGW), followed by a structure of the U4 core snRNP (2Y9A), which yielded first insights into atomic contacts, especially the binding mode of the Sm proteins to the Sm site. The structure of U6 UsnRNA was solved in complex with a specific protein Prp24 (4N0T), as well as a structure of its 3'-nucleotides bound to the special Lsm2-8 protein ring (4M7A). The PDB codes for the respective structures are mentioned in parentheses.
The structures determined by single particle electron microscopy analysis are: human U1 snRNP, human U11/U12 di-snRNP,
human U5 snRNP, U4/U6 di-snRNP, U4/U6∙U5 tri-snRNP.
The further progress determining the structures and functions of snRNPs and spliceosomes continues. | 1 | Applied and Interdisciplinary Chemistry |
The isochore theory became one of the most useful theories in molecular evolution for many years. It was the first and most comprehensive attempt to explain the long-range compositional heterogeneity of vertebrate genomes within an evolutionary framework. Despite the interest in the early years in the isochore model, in recent years, the theory’s methodology, terminology, and predictions have been challenged.
Because this theory was proposed in the 20th century before complete genomes were sequenced, it could not be fully tested for nearly 30 years. In the beginning of the 21st century, when the first genomes were made available it was clear that isochores do not exist in the human genome
nor in other mammalian genomes. When failed to find isochores, many attacked the very existence of isochores.
The most important predictor of isochores, GC3 was shown to have no predictable power
to the GC content of nearby genomic regions, refuting findings from over 30 years of research, which were the basis for many isochore studies. Isochore-originators replied that the term was misinterpreted
as isochores are not "homogeneous" but rather fairly homogeneous regions with a heterogeneous nature (especially) of GC-rich regions at the 5 kb scale, which only added to the already growing confusion. The reason for this ongoing frustration was the ambiguous definition of isochores as long and homogeneous, allowed some researchers to discover "isochores" and others to dismiss them, although both camps used the same data.
The unfortunate side effect of this controversy was an "arms race" in which isochores are frequently redefined and relabeled following conflicting findings that failed to reveal "mosaic of isochores." The unfortunate outcomes of this controversy and the following terminological-methodological mud were the loss of interest in isochores by the scientific community. When the most important core-concept in isochoric literature, the thermodynamic stability hypothesis, was rejected, the theory lost its appeal. Even today, there is no clear definition to isochores nor is there an algorithm that detects isochores. Isochores are detected manually by visual inspection of GC content curves , however because this approach lacks scientific merit and is difficult to replicate by independent groups, the findings remain disputed. | 1 | Applied and Interdisciplinary Chemistry |
Irisin (fibronectin type III domain-containing protein 5 or FNDC5), a recently described myokine hormone produced and secreted by acutely exercising skeletal muscles, is thought to bind white adipose tissue cells via undetermined receptors. Irisin has been reported to promote a brown adipose tissue-like phenotype upon white adipose tissue by increasing cellular mitochondrial density and expression of uncoupling protein-1, thereby increasing adipose tissue energy expenditure via thermogenesis. This is considered important, because excess visceral adipose tissue in particular distorts the whole body energy homeostasis, increases the risk of cardiovascular disease and raises exposure to a milieu of adipose tissue-secreted hormones (adipokines) that promote inflammation and cellular aging. The authors enquired whether the favorable impact of irisin on white adipose tissue might be associated with maintenance of telomere length, a well-established genetic marker in the aging process. They conclude that these data support the view that irisin may have a role in the modulation not only of energy balance but also the aging process.
However, exogenous irisin may aid in heightening energy expenditure, and thus in reducing obesity. Boström et al. reported on December 14, 2012: "Since the conservation of calories would likely provide an overall survival advantage for mammals, it appears paradoxical that exercise would stimulate the secretion of a polypeptide hormone that increases thermogenesis and energy expenditure. One explanation for the increased irisin expression with exercise in mouse and man may have evolved as a consequence of muscle contraction during shivering. Muscle secretion of a hormone that activates adipose thermogenesis during this process might provide a broader, more robust defense against hypothermia. The therapeutic potential of irisin is obvious. Exogenously administered irisin induces the browning of subcutaneous fat and thermogenesis, and it presumably could be prepared and delivered as an injectable polypeptide. Increased formation of brown or beige/brite fat has been shown to have anti-obesity, anti-diabetic effects in multiple murine models, and adult humans have significant deposits of UCP1-positive brown fat. (Our data show) that even relatively short treatments of obese mice with irisin improves glucose homeostasis and causes a small weight loss. Whether longer treatments with irisin and/or higher doses would cause more weight loss remains to be determined. The worldwide, explosive increase in obesity and diabetes strongly suggests exploring the clinical utility of irisin in these and related disorders. Another potentially important aspect of this work relates to other beneficial effects of exercise, especially in some diseases for which no effective treatments exist. The clinical data linking exercise with health benefits in many other diseases suggests that irisin could also have significant effects in these disorders."
While the murine findings reported by Boström et al. appear encouraging, other researchers have questioned whether irisin operates in a similar manner in humans. For example, Timmons et al. noted that over 1,000 genes are upregulated by exercise and examined how expression of FNDC5 was affected by exercise in ~200 humans. They found that it was upregulated only in highly active elderly humans, casting doubt on the conclusions of Boström et al. Further discussion of this issue can be found in . | 1 | Applied and Interdisciplinary Chemistry |
Subcritical crack propagation in glasses falls into three regions. In region I, the velocity of crack propagation increases with ambient humidity due to stress-enhanced chemical reaction between the glass and water. In region II, crack propagation velocity is diffusion controlled and dependent on the rate at which chemical reactants can be transported to the tip of the crack. In region III, crack propagation is independent of its environment, having reached a critical stress intensity. Chemicals other than water, like ammonia, can induce subcritical crack propagation in silica glass, but they must have an electron donor site and a proton donor site. | 1 | Applied and Interdisciplinary Chemistry |
The trifluoromethyl group occurs in certain pharmaceuticals, drugs, and abiotically synthesized natural fluorocarbon based compounds. The medicinal use of the trifloromethyl group dates from 1928, although research became more intense in the mid-1940s. The trifluoromethyl group is often used as a bioisostere to create derivatives by replacing a chloride or a methyl group. This can be used to adjust the steric and electronic properties of a lead compound, or to protect a reactive methyl group from metabolic oxidation. Some notable drugs containing trifluoromethyl groups include efavirenz (Sustiva), an HIV reverse transcriptase inhibitor; fluoxetine (Prozac), an antidepressant; and celecoxib (Celebrex), a nonsteroidal anti-inflammatory drug. Sulfoxaflor is used as a systemic insecticide.
The trifluoromethyl group can also be added to change the solubility of molecules containing other groups of interest. | 0 | Theoretical and Fundamental Chemistry |
A benzoporphyrin is a porphyrin with a benzene ring fused to one of the pyrrole units. e.g. verteporfin is a benzoporphyrin derivative. | 1 | Applied and Interdisciplinary Chemistry |
Achieving balance in telomere length is challenging. While extended telomeres can reverse some aspects of cellular aging, excessively long telomeres may lead to cellular instability and dysfunction. It is important to strike the right balance to avoid unintended consequences. | 1 | Applied and Interdisciplinary Chemistry |
Oxidizing roasting, the most commonly practiced roasting process, involves heating the ore in excess of air or oxygen, to burn out or replace the impurity element, generally sulfur, partly or completely by oxygen. For sulfide roasting, the general reaction can be given by:
:2MS (s) + 3O (g) -> 2MO (s) + 2SO (g)
Roasting the sulfide ore, until almost complete removal of the sulfur from the ore, results in a dead roast. | 1 | Applied and Interdisciplinary Chemistry |
The committed dose in radiological protection is a measure of the stochastic health risk due to an intake of radioactive material into the human body. Stochastic in this context is defined as the probability of cancer induction and genetic damage, due to low levels of radiation. The SI unit of measure is the sievert.
A committed dose from an internal source represents the same effective risk as the same amount of effective dose applied uniformly to the whole body from an external source, or the same amount of equivalent dose applied to part of the body. The committed dose is not intended as a measure for deterministic effects, such as radiation sickness, which are defined as the severity of a health effect which is certain to happen.
The radiation risk proposed by the International Commission on Radiological Protection (ICRP) predicts that an effective dose of one sievert carries a 5.5% chance of developing cancer. Such a risk is the sum of both internal and external radiation dose. | 0 | Theoretical and Fundamental Chemistry |
Explicit expressions for the viscous Burgers' equation are available. Some of the physically relevant solutions are given below: | 1 | Applied and Interdisciplinary Chemistry |
The classes of enzymes that have manganese cofactors include oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. Other enzymes containing manganese are arginase and Mn-containing superoxide dismutase (Mn-SOD). Also the enzyme class of reverse transcriptases of many retroviruses (though not lentiviruses such as HIV) contains manganese. Manganese-containing polypeptides are the diphtheria toxin, lectins and integrins. | 1 | Applied and Interdisciplinary Chemistry |
NBS, in the presence of a strong base, such as DBU, reacts with primary amides to produce a carbamate via the Hofmann rearrangement. | 0 | Theoretical and Fundamental Chemistry |
One form of HWT is known as a Gun Tunnel or hot shot tunnel (up to M=27), which can be used for analysis of flows past ballistic missiles, space vehicles in atmospheric entry, and plasma physics or heat transfer at high temperatures. It runs intermittently, but has a very low running time (less than a second).
The method of operation is based on a high temperature and pressurized gas (air or nitrogen) produced in an arc-chamber, and a near-vacuum in the remaining part of the tunnel. The arc-chamber can reach several MPa, while pressures in the vacuum chamber can be as low as 0.1 Pa. This means that the pressure ratios of these tunnels are in the order of 10 million. Also, the temperatures of the hot gas are up to 5000 K. The arc chamber is mounted in the gun barrel. The high pressure gas is separated from the vacuum by a diaphragm.
Prior to a test run commencing, a membrane separates the compressed air from the gun barrel breech. A rifle (or similar) is used to rupture the membrane. Compressed air rushes into the breech of the gun barrel, forcing a small projectile to accelerate rapidly down the barrel. Although the projectile is prevented from leaving the barrel, the air in front of the projectile emerges at hypersonic velocity into the working section. Naturally the duration of the test is extremely brief, so high speed instrumentation is required to get any meaningful data. | 1 | Applied and Interdisciplinary Chemistry |
Bennett shows that for every function f satisfying the condition (which is essentially the detailed balance condition), and for every energy offset C, one has the exact relationship
where U and U are the potential energies of the same configurations, calculated using potential function A (when the system is in superstate A) and potential function B (when the system is in the superstate B) respectively. | 0 | Theoretical and Fundamental Chemistry |
There are several different pathways through which propionyl-CoA can be produced:
* Propionyl-CoA, a three-carbon structure, is considered to be a minor species of propionic acid. Therefore, odd-number chains of fatty acids are oxidized to yield both propionyl-CoA as well as acetyl-CoA. Propionyl-CoA is later converted into succinyl-CoA through biotin-dependant propionyl-CoA carboxylase (PCC) and b12-dependant methylmalonyl-CoA mutase (MCM), sequentially.
* Propionyl-CoA is not only produced from the oxidation of odd-chain fatty acids, but also by the oxidation of amino acids including methionine, valine, isoleucine, and threonine. Furthermore, catabolism of amino acids can also be a result of the conversion of propionyl-CoA to methylmalonyl-CoA by propionyl-CoA carboxylase.
* Cholesterol oxidation, which forms bile acids, also forms propionyl-CoA as a side product. In an experiment performed by Suld et al., when combining liver mitochondria and propionic acid with the addition of coenzyme A, labeled isotopes of psionic acid were degraded. However, following 5β-cholestane-3α,7α,12α,26-tetrol-26,27-C14 incubation, propionyl CoA was able to be rescued along with the formation of bile. | 1 | Applied and Interdisciplinary Chemistry |
STAT3 is a member of the STAT protein family. In response to cytokines and growth factors, STAT3 is phosphorylated by receptor-associated Janus kinases (JAK), forms homo- or heterodimers, and translocates to the cell nucleus where it acts as a transcription activator. Specifically, STAT3 becomes activated after phosphorylation of tyrosine 705 in response to such ligands as interferons, epidermal growth factor (EGF), interleukin (IL-)5 and IL-6. Additionally, activation of STAT3 may occur via phosphorylation of serine 727 by mitogen-activated protein kinases (MAPK) and through c-src non-receptor tyrosine kinase. STAT3 mediates the expression of a variety of genes in response to cell stimuli, and thus plays a key role in many cellular processes such as cell growth and apoptosis.
STAT3-deficient mouse embryos cannot develop beyond embryonic day 7, when gastrulation begins. It appears that at these early stages of development, STAT3 activation is required for self-renewal of embryonic stem cells (ESCs). Indeed, LIF, which is supplied to murine ESC cultures to maintain their undifferentiated state, can be omitted if STAT3 is activated through some other means.
STAT3 is essential for the differentiation of the TH17 helper T cells, which have been implicated in a variety of autoimmune diseases. During viral infection, mice lacking STAT3 in T-cells display impairment in the ability to generate T-follicular helper (Tfh) cells and fail to maintain antibody based immunity.
STAT3 caused upregulation in E-selectin, a factor in metastasis of cancers.
Hyperactivation of STAT3 occurs in COVID-19 infection and other viral infections. | 1 | Applied and Interdisciplinary Chemistry |
Alpha oxidation (α-oxidation) is a process by which certain branched-chain fatty acids are broken down by removal of a single carbon from the carboxyl end. In humans, alpha-oxidation is used in peroxisomes to break down dietary phytanic acid, which cannot undergo beta-oxidation due to its β-methyl branch, into pristanic acid. Pristanic acid can then acquire acetyl-CoA and subsequently become beta oxidized, yielding propionyl-CoA. | 1 | Applied and Interdisciplinary Chemistry |
Sternhell was born in Lwow, then in Poland but now in western Ukraine. His father was Samson Sternhell, a lawyer. Before the war he attended a Zionist Hebrew language primary school for five years. Having survived the Bergen-Belsen concentration camp, he emigrated to Australia with his parents to join members of the Sternhell family who had left Europe prior to World War II. Arriving in Sydney in February 1947, he enrolled as a boarder at Newington College a few days after the commencement of the first term. Having had no formal education since primary school, and only learnt English recently in Palestine, he spent the next nine months studying for the Leaving Certificate. He sat for his exams and received four A's and a B in English. Following Newington, he attended the University of Sydney and graduated with a BSc (hons) in 1951 and a MSc in 1953. In 1961, he was awarded a PhD and DIC from the University of London. After further study in London, he received a DSc from Imperial College. | 0 | Theoretical and Fundamental Chemistry |
Synthetic polymers are human made through chemical reactions of monomers. Their mechanical properties are favorable in that their molecular weights can be regulated from low to high based on differing requirements. However, their lack of functional groups and structural complexity has limited their usage in organ printing. Current synthetic polymers with excellent 3D printability and in vivo tissue compatibility, include polyethylene glycol (PEG), poly(lactic-glycolic acid) (PLGA), and polyurethane (PU). PEG is a biocompatible, nonimmunogenic synthetic polyether that has tunable mechanical properties for use in 3D bioprinting. Though PEG has been utilized in various 3D printing applications, the lack of cell-adhesive domains has limited further use in organ printing. PLGA, a synthetic copolymer, is widely familiar in living creatures, such as animals, humans, plants, and microorganisms. PLGA is used in conjunction with other polymers to create different material systems, including PLGA-gelatin, PLGA-collagen, all of which enhance mechanical properties of the material, biocompatible when placed in vivo, and have tunable biodegradability. PLGA has most often been used in printed constructs for bone, liver, and other large organ regeneration efforts. Lastly, PU is unique in that it can be classified into two groups: biodegradable or non-biodegradable. It has been used in the field of bioprinting due to its excellent mechanical and bioinert properties. An application of PU would be inanimate artificial hearts; however, using existing 3D bioprinters, this polymer cannot be printed. A new elastomeric PU was created composed of PEG and polycaprolactone (PCL) monomers. This new material exhibits excellent biocompatibility, biodegradability, bioprintability, and biostability for use in complex bioartificial organ printing and manufacturing. Due to high vascular and neural network construction, this material can be applied to organ printing in a variety of complex ways, such as the brain, heart, lung, and kidney. | 1 | Applied and Interdisciplinary Chemistry |
Stercobilin is a tetrapyrrolic bile pigment and is one end-product of heme catabolism. It is the chemical responsible for the brown color of human feces and was originally isolated from feces in 1932. Stercobilin (and related urobilin) can be used as a marker for biochemical identification of fecal pollution levels in rivers. | 1 | Applied and Interdisciplinary Chemistry |
Phosphine is a worldwide constituent of the Earth's atmosphere at very low and highly variable concentrations. It may contribute significantly to the global phosphorus biochemical cycle. The most likely source is reduction of phosphate in decaying organic matter, possibly via partial reductions and disproportionations, since environmental systems do not have known reducing agents of sufficient strength to directly convert phosphate to phosphine.
It is also found in Jupiter's atmosphere. | 0 | Theoretical and Fundamental Chemistry |
VMAT1 (SLC18A1) maps to a shared bipolar disorder(BPD)/schizophrenia locus, which is located on chromosome 8p21. It is thought that disruption in transport of monoamine neurotransmitters due to variation in the VMAT1 gene may be relevant to the etiology of these mental disorders. One study looked at a population of European descent, examining the genotypes of a bipolar group and a control group. The study confirmed expression of VMAT1 in the brain at a protein and mRNA level, and found a significant difference between the two groups, suggesting that, at least for people of European descent, variation in the VMAT1 gene may confer susceptibility. A second study examined a population of Japanese individuals, one group healthy and the other schizophrenic. This study resulted in mostly inconclusive findings, but some indications that variation in the VMAT1 gene would confer susceptibility to schizophrenia in Japanese women. While these studies provide some promising insight into the cause of some of the most prevalent mental disorders, it is clear that additional research will be necessary in order to gain a full understanding. | 1 | Applied and Interdisciplinary Chemistry |
Heterogeneous gold catalysis refers to the use of elemental gold as a heterogeneous catalyst. As in most heterogeneous catalysis, the metal is typically supported on metal oxide. Furthermore, as seen in other heterogeneous catalysts, activity increases with a decreasing diameter of supported gold clusters. Several industrially relevant processes are also observed such as H activation, Water-gas shift reaction, and hydrogenation. One or two gold-catalyzed reactions may have been commercialized.
The high activity of supported gold clusters has been proposed to arise from a combination of structural changes, quantum-size effects and support effects that preferentially tune the electronic structure of gold such that optimal binding of adsorbates during the catalytic cycle is enabled. The selectivity and activity of gold nanoparticles can be finely tuned by varying the choice of support material, with e.g. titania (TiO), hematite (α-FeO), cobalt(II/III) oxide (CoO) and nickel(II) oxide (NiO) serving as the most effective support materials for facilitating the catalysis of CO combustion. Besides enabling an optimal dispersion of the nanoclusters, the support materials have been suggested to promote catalysis by altering the size, shape, strain and charge state of the cluster. A precise shape control of the deposited gold clusters has been shown to be important for optimizing the catalytic activity, with hemispherical, few atomic layers thick nanoparticles generally exhibiting the most desirable catalytic properties due to maximized number of high-energy edge and corner sites. | 0 | Theoretical and Fundamental Chemistry |
* The process may not remove sufficient organic matter from the wastewater.
* The sludge age may be too low to enable nitrification.
The typical control band for the concentration of MLSS is 2 to 4 g/L for conventional activated sludge, or up to 15 g/L for membrane bioreactors.
One of the easiest control procedures for activated sludge systems is the Constant Mixed Liquor Suspended Solids method. In this method, the operator selects a certain MLSS concentration or range of mix liquor concentrations that produces the best effluent and the highest removal efficiencies. This specific value or range must be calculated depending on COD or BOD load [kg/d]. When the operator finds the optimum MLSS concentration for each plant, they attempt to maintain this value by adjusting the sludge wasting or sludge excess rate. One rule of thumb for activated sludge systems is that for every pound of BOD removed in the secondary system a half a pound of new solids is generated through reproduction of the organisms and addition of new organisms from the influent wastes. So, the operator tries to waste the proper amount of solids to keep their selected optimum mix liquor concentration constant. If the MLSS concentration is above the desired concentration, the wasting of the excess solids will have to be started or increased. If the MLSS concentration is below the desired concentration level, wasting should be decreased or stopped. | 0 | Theoretical and Fundamental Chemistry |
Thermal transport in non-metal solids was usually considered to be governed by the three-phonon scattering process, and the role of four-phonon and higher-order scattering processes was believed to be negligible. Recent studies have shown that the four-phonon scattering can be important for nearly all materials at high temperature and for certain materials at room temperature. The predicted significance of four-phonon scattering in boron arsenide was confirmed by experiments. | 0 | Theoretical and Fundamental Chemistry |
The Kutta–Joukowski theorem is a fundamental theorem in aerodynamics used for the calculation of lift of an airfoil (and any two-dimensional body including circular cylinders) translating in a uniform fluid at a constant speed so large that the flow seen in the body-fixed frame is steady and unseparated. The theorem relates the lift generated by an airfoil to the speed of the airfoil through the fluid, the density of the fluid and the circulation around the airfoil. The circulation is defined as the line integral around a closed loop enclosing the airfoil of the component of the velocity of the fluid tangent to the loop. It is named after Martin Kutta and Nikolai Zhukovsky (or Joukowski) who first developed its key ideas in the early 20th century. Kutta–Joukowski theorem is an inviscid theory, but it is a good approximation for real viscous flow in typical aerodynamic applications.
Kutta–Joukowski theorem relates lift to circulation much like the Magnus effect relates side force (called Magnus force) to rotation. However, the circulation here is not induced by rotation of the airfoil. The fluid flow in the presence of the airfoil can be considered to be the superposition of a translational flow and a rotating flow. This rotating flow is induced by the effects of camber, angle of attack and the sharp trailing edge of the airfoil. It should not be confused with a vortex like a tornado encircling the airfoil. At a large distance from the airfoil, the rotating flow may be regarded as induced by a line vortex (with the rotating line perpendicular to the two-dimensional plane). In the derivation of the Kutta–Joukowski theorem the airfoil is usually mapped onto a circular cylinder. In many textbooks, the theorem is proved for a circular cylinder and the Joukowski airfoil, but it holds true for general airfoils. | 1 | Applied and Interdisciplinary Chemistry |
The first implementation of the Olszewski tube was attempted at Lake Kortowo in Poland and this led to oligotrophication, reduction of nutrient cycling. This tube has shown the most promise in a 3.9 meter deep eutrophic lake in Switzerland because the phosphorus and nitrogen levels in the summer drastically decreased, oxygen levels increased, and the amount of cyanobacteria decreased from 152 grams per square meter to 41 grams per square meter. It has also been reported by a scientist named Bjork that there have been successes with the Olszewski tube in European lakes. Other limnologists like Pechlaner and Gachter have reported successes in small lakes where the total phosphorus decreased, transparency of water increased, and less algae was present. | 1 | Applied and Interdisciplinary Chemistry |
Dirubidium is produced when rubidium vapour is chilled. The enthalpy of formation (ΔH) in the gas phase is 113.29 kJ/mol. In practice, an oven heated to 600 to 800K with a nozzle can squirt out vapour that condenses into dimers. The proportion of Rb in rubidium vapour varies with its density, which depends on the temperature. At 200° the partial pressure of Rb is only 0.4%, at 400 °C it constitutes 1.6% of the pressure, and at 677 °C the dimer has 7.4% of the vapour pressure (13.8% by mass).
The rubidium dimer has been formed on the surface of helium nanodroplets when two rubidium atoms combine to yield the dimer:
:Rb + Rb → Rb
Rb has also been produced in solid helium matrix under pressure.
Ultracold rubidium atoms can be stored in a magneto-optic trap and then photoassociated to form molecules in an excited state, vibrating at a rate so high they barely hang together. In solid matrix traps, Rb can combine with the host atoms when excited to form exciplexes, for example Rb(Π)He in a solid helium matrix.
Ultracold rubidium dimers are being produced in order to observe quantum effects on well-defined molecules. It is possible to produce a set of molecules all rotating on the same axis with the lowest vibrational level. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, an aminal or aminoacetal is a functional group or type of organic compound that has two amine groups attached to the same carbon atom: . (As is customary in organic chemistry, R can represent hydrogen or an alkyl group). A common aminal is bis(dimethylamino)methane, a colorless liquid that is prepared by the reaction of dimethylamine and formaldehyde:
Aminals are encountered in, for instance, the Fischer indole synthesis. Several examples exist in nature.
Hexahydro-1,3,5-triazine (), an intermediate in the condensation of formaldehyde and ammonia, tends to degrade to hexamethylene tetraamine.
Cyclic aminals can be obtained by the condensation of a diamine and an aldehyde. Imidazolidines are one class of these cyclic aminals. | 0 | Theoretical and Fundamental Chemistry |
Depolarization is essential to the functions of many cells in the human body, which is exemplified by the transmission of stimuli both within a neuron and between two neurons. The reception of stimuli, neural integration of those stimuli, and the neuron's response to stimuli all rely upon the ability of neurons to utilize depolarization to transmit stimuli either within a neuron or between neurons. | 0 | Theoretical and Fundamental Chemistry |
Polyclonal B cell response is a natural mode of immune response exhibited by the adaptive immune system of mammals. It ensures that a single antigen is recognized and attacked through its overlapping parts, called epitopes, by multiple clones of B cell.
In the course of normal immune response, parts of pathogens (e.g. bacteria) are recognized by the immune system as foreign (non-self), and eliminated or effectively neutralized to reduce their potential damage. Such a recognizable substance is called an antigen. The immune system may respond in multiple ways to an antigen; a key feature of this response is the production of antibodies by B cells (or B lymphocytes) involving an arm of the immune system known as humoral immunity. The antibodies are soluble and do not require direct cell-to-cell contact between the pathogen and the B-cell to function.
Antigens can be large and complex substances, and any single antibody can only bind to a small, specific area on the antigen. Consequently, an effective immune response often involves the production of many different antibodies by many different B cells against the same antigen. Hence the term "polyclonal", which derives from the words poly, meaning many, and clones from Greek klōn, meaning sprout or twig; a clone is a group of cells arising from a common "mother" cell. The antibodies thus produced in a polyclonal response are known as polyclonal antibodies. The heterogeneous polyclonal antibodies are distinct from monoclonal antibody molecules, which are identical and react against a single epitope only, i.e., are more specific.
Although the polyclonal response confers advantages on the immune system, in particular, greater probability of reacting against pathogens, it also increases chances of developing certain autoimmune diseases resulting from the reaction of the immune system against native molecules produced within the host. | 1 | Applied and Interdisciplinary Chemistry |
In Canada, the Patented Medicine Prices Review Board examines drug pricing and determines if a price is excessive or not. In these circumstances, drug manufacturers must submit a proposed price to the appropriate regulatory agency. Furthermore, "the International Therapeutic Class Comparison Test is responsible for comparing the National Average Transaction Price of the patented drug product under review" different countries that the prices are being compared to are the following: France, Germany, Italy, Sweden, Switzerland, the United Kingdom, and the United States | 1 | Applied and Interdisciplinary Chemistry |
In 1662, Robert Boyle systematically studied the relationship between the volume and pressure of a fixed amount of gas at a constant temperature. He observed that the volume of a given mass of a gas is inversely proportional to its pressure at a constant temperature.
Boyle's law, published in 1662, states that, at a constant temperature, the product of the pressure and volume of a given mass of an ideal gas in a closed system is always constant. It can be verified experimentally using a pressure gauge and a variable volume container. It can also be derived from the kinetic theory of gases: if a container, with a fixed number of molecules inside, is reduced in volume, more molecules will strike a given area of the sides of the container per unit time, causing a greater pressure. | 0 | Theoretical and Fundamental Chemistry |
The above explanation is a simplification as not all tidal wave energy is transmitted, but it is partly reflected at the continental slope. The transmission coefficient of the tidal wave is given by:
This equation indicates that when the transmitted tidal wave has the same amplitude as the original wave. Furthermore, the transmitted wave will be larger than the original wave when as is the case for the transition to the continental shelf.
The reflected wave amplitude () is determined by the reflection coefficient of the tidal wave:
This equation indicates that when there is no reflected wave and if the reflected tidal wave will be smaller than the original tidal wave. | 1 | Applied and Interdisciplinary Chemistry |
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