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The red component of color television cathode ray tubes is typically emitted from an yttria () or yttrium oxide sulfide () host lattice doped with europium (III) cation (Eu) phosphors. The red color itself is emitted from the europium while the yttrium collects energy from the electron gun and passes it to the phosphor. Yttrium compounds can serve as host lattices for doping with different lanthanide cations. Tb can be used as a doping agent to produce green luminescence. As such yttrium compounds such as yttrium aluminium garnet (YAG) are useful for phosphors and are an important component of white LEDs.
Yttria is used as a sintering additive in the production of porous silicon nitride.
Yttrium compounds are used as a catalyst for ethylene polymerization. As a metal, yttrium is used on the electrodes of some high-performance spark plugs. Yttrium is used in gas mantles for propane lanterns as a replacement for thorium, which is radioactive. | 1 | Applied and Interdisciplinary Chemistry |
Although there are several commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1933. | 0 | Theoretical and Fundamental Chemistry |
The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars. | 0 | Theoretical and Fundamental Chemistry |
Runoff generated on cropland during storms or long winter rains concentrates in the thalweg where it can lead to rill or gully erosion.
Rills and gullies further concentrate runoff and speed up its transfer, which can worsen damage occurring downstream. This can result in a muddy flood.
In this context, a grassed waterway allows increasing soil cohesion and roughness. It also prevents the formation of rills and gullies. Furthermore, it can slow down runoff and allow its re-infiltration during long winter rains. In contrast, its infiltration capacity is generally not sufficient to reinfiltrate runoff produced by heavy spring and summer storms. It can therefore be useful to combine it with extra measures, like the installation of earthen dams across the grassed waterway, in order to buffer runoff temporarily. | 1 | Applied and Interdisciplinary Chemistry |
The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP clade. The PACMAD lineage is the only group within the grasses in which the C photosynthesis pathway has evolved; studies have shown that this happened independently multiple times.
The name of the clade comes from the first initials of the included subfamilies Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, and Danthonioideae. It has no defined taxonomic rank but is used frequently because it refers to a well-defined monophyletic group with a distinct ecology.
Phylogeny of the PACMAD clade, with photosynthetic pathways for each subfamily: | 0 | Theoretical and Fundamental Chemistry |
Inverse agonists differ from regular agonists in that they effect receptors to which a regular agonist binds such that the bound receptors demonstrate reduced activity compared to when they are normally inactive. In other words, inverse antagonists limit the efficacy of the bound receptor in some way. This is noted to be beneficial in instances wherein expression of receptors or up-regulated receptor sensitivity could be detrimental, thus making suppression of response the best recourse. A handful of examples of inverse agonist use in therapy include β-blockers, antihistamines, ACP-103 to treat Parkinson's disease, hemopressin, drugs to treat obesity, and more besides. | 1 | Applied and Interdisciplinary Chemistry |
In general, electric (charge) radiation or magnetic (current, magnetic moment) radiation can be classified into multipoles E (electric) or M (magnetic) of order 2, e.g., E1 for electric dipole, E2 for quadrupole, or E3 for octupole. In transitions where the change in angular momentum between the initial and final states makes several multipole radiations possible, usually the lowest-order multipoles are overwhelmingly more likely, and dominate the transition.
The emitted particle carries away angular momentum, with quantum number , which for the photon must be at least 1, since it is a vector particle (i.e., it has total angular momentum quantum number| = 1). Thus, there is no radiation from E0 (electric monopoles) or M0 (magnetic monopoles, which do not seem to exist).
Since the total angular momentum has to be conserved during the transition, we have that
where and its z-projection is given by and where and are, respectively, the initial and final angular momenta of the atom.
The corresponding quantum numbers and (-axis angular momentum) must satisfy
and
Parity is also preserved. For electric multipole transitions
while for magnetic multipoles
Thus, parity does not change for E-even or M-odd multipoles, while it changes for E-odd or M-even multipoles.
These considerations generate different sets of transitions rules depending on the multipole order and type. The expression forbidden transitions is often used, but this does not mean that these transitions cannot occur, only that they are electric-dipole-forbidden. These transitions are perfectly possible; they merely occur at a lower rate. If the rate for an E1 transition is non-zero, the transition is said to be permitted; if it is zero, then M1, E2, etc. transitions can still produce radiation, albeit with much lower transitions rates. The transition rate decreases by a factor of about 1000 from one multipole to the next one, so the lowest multipole transitions are most likely to occur.
Semi-forbidden transitions (resulting in so-called intercombination lines) are electric dipole (E1) transitions for which the selection rule that the spin does not change is violated. This is a result of the failure of LS coupling. | 0 | Theoretical and Fundamental Chemistry |
When a ligand activates the G protein-coupled receptor, it induces a conformational change in the receptor that allows the receptor to function as a guanine nucleotide exchange factor (GEF) that exchanges GDP for GTP. The GTP (or GDP) is bound to the G subunit in the traditional view of heterotrimeric GPCR activation. This exchange triggers the dissociation of the G subunit (which is bound to GTP) from the G dimer and the receptor as a whole. However, models which suggest molecular rearrangement, reorganization, and pre-complexing of effector molecules are beginning to be accepted. Both G-GTP and G can then activate different signaling cascades (or second messenger pathways) and effector proteins, while the receptor is able to activate the next G protein. | 1 | Applied and Interdisciplinary Chemistry |
High precision isotope-ratio mass spectrometry (IRMS) is another method for measuring kinetic fractionation of isotopes for natural abundance KIE measurements. Widlanski and coworkers demonstrated KIE at natural abundance measurements for the hydrolysis of sulfate monoesters. Their observation of a large KIE suggests S-O bond cleavage is rate controlling and likely rules out an associate reaction mechanism.
The major limitation for determining KIE's at natural abundance using IRMS is the required site selective degradation without isotopic fractionation into an analyzable small molecule, a non-trivial task. | 0 | Theoretical and Fundamental Chemistry |
The bioluminescent bacterium A. fischeri is the first organism in which QS was observed. It lives as a mutualistic symbiont in the photophore (or light-producing organ) of the Hawaiian bobtail squid. When A. fischeri cells are free-living (or planktonic), the autoinducer is at low concentration, and, thus, cells do not show luminescence. However, when the population reaches the threshold in the photophore (about cells/ml), transcription of luciferase is induced, leading to bioluminescence.
In A. fischeri bioluminescence is regulated by AHLs (N-acyl-homoserine lactones) which is a product of the LuxI gene whose transcription is regulated by the LuxR activator. LuxR works only when AHLs binds to the LuxR. | 1 | Applied and Interdisciplinary Chemistry |
Nanoelectrochemistry is a branch of electrochemistry that investigates the electrical and electrochemical properties of materials at the nanometer size regime. Nanoelectrochemistry plays significant role in the fabrication of various sensors, and devices for detecting molecules at very low concentrations. | 0 | Theoretical and Fundamental Chemistry |
Cancer-based research into co-receptors includes the investigation of growth factor activated co-receptors, such as Transforming Growth Factor (TGF-β) co-receptors. Expression of the co-receptor endoglin, which is expressed on the surface of tumor cells, is correlated with cell plasticity and the development of tumors.
Another co-receptor of TGF-β is CD8. Although the exact mechanism is still unknown, CD8 co-receptors have been shown to enhance T-cell activation and TGF-β-mediated immune suppression.
TGF-β has been shown to influence the plasticity of cells through integrin and focal adhesion kinase. The co-receptors of tumor cells and their interaction with T-cells provide important considerations for tumor immunotherapy.
Recent research into co-receptors for p75, such as the sortilin co-receptor, has implicated sortilin in connection to neurotrophins, a type of nerve growth factor.
The p75 receptor and co-receptors have been found to influence the aggressiveness of tumors, specifically via the ability of neurotrophins to rescue cells from certain forms of cell death.
Sortilin, the p75 co-receptor, has been found in natural killer cells, but with only low levels of neurotrophin receptor. The sortilin co-receptor is believed to work with a neurotrophin homologue that can also cause neurotrophin to alter the immune response. | 1 | Applied and Interdisciplinary Chemistry |
The parent compound of the phosphines is PH, called phosphine in the US and British Commonwealth, but phosphane elsewhere. Replacement of one or more hydrogen centers by an organic substituents (alkyl, aryl), gives PHR, an organophosphine, generally referred to as phosphines.
From the commercial perspective, the most important phosphine is triphenylphosphine, several million kilograms being produced annually. It is prepared from the reaction of chlorobenzene, PCl, and sodium. Phosphines of a more specialized nature are usually prepared by other routes. Phosphorus halides undergo nucleophilic displacement by organometallic reagents such as Grignard reagents. Organophosphines are nucleophiles and ligands. Two major applications are as reagents in the Wittig reaction and as supporting phosphine ligands in homogeneous catalysis.
Their nucleophilicity is evidenced by their reactions with alkyl halides to give phosphonium salts. Phosphines are nucleophilic catalysts in organic synthesis, e.g. the Rauhut–Currier reaction and Baylis-Hillman reaction. Phosphines are reducing agents, as illustrated in the Staudinger reduction for the conversion of organic azides to amines and in the Mitsunobu reaction for converting alcohols into esters. In these processes, the phosphine is oxidized to phosphorus(V). Phosphines have also been found to reduce activated carbonyl groups, for instance the reduction of an α-keto ester to an α-hydroxy ester. | 0 | Theoretical and Fundamental Chemistry |
When a dry porous medium is brought into contact with a liquid, it will absorb the liquid at a rate which decreases over time. When considering evaporation, liquid penetration will reach a limit dependent on parameters of temperature, humidity and permeability. This process is known as evaporation limited capillary penetration and is widely observed in common situations including fluid absorption into paper and rising damp in concrete or masonry walls. For a bar shaped section of material with cross-sectional area A that is wetted on one end, the cumulative volume V of absorbed liquid after a time t is
where S is the sorptivity of the medium, in units of m·s or mm·min. This time dependence relation is similar to Washburn's equation for the wicking in capillaries and porous media. The quantity
is called the cumulative liquid intake, with the dimension of length. The wetted length of the bar, that is the distance between the wetted end of the bar and the so-called wet front, is dependent on the fraction f of the volume occupied by voids. This number f is the porosity of the medium; the wetted length is then
Some authors use the quantity S/f as the sorptivity.
The above description is for the case where gravity and evaporation do not play a role.
Sorptivity is a relevant property of building materials, because it affects the amount of rising dampness. Some values for the sorptivity of building materials are in the table below. | 0 | Theoretical and Fundamental Chemistry |
The community multiscale air quality model, or CMAQ, is a sophisticated three-dimensional Eulerian grid chemical transport model developed by the US EPA for studying air pollution from local to hemispheric scales. EPA and state environmental agencies use CMAQ to develop and assess implementation actions needed to attain National Ambient Air Quality Standards (NAAQS) defined under the Clean Air Act. The CMAQ simulates air pollutants of concern—including ozone, particulate matter (PM), and a variety of air toxics — to optimize air quality management. Deposition values from the CMAQ are used to assess ecosystem impacts such as eutrophication and acidification from air pollutants. In addition, the National Weather Service uses the CMAQ to produce twice-daily forecast guidance for ozone air quality across the U.S. The CMAQ unites the modeling of meteorology, emissions, and chemistry to simulate the fate of air pollutants under varying atmospheric conditions. Other kinds of models—including crop management and hydrology models— can be linked with the CMAQ simulations, as needed, to simulate pollution more holistically across environmental media.
The CMAQ is developed and maintained by scientists in the EPA's Office of Research and Development, and new versions of the software are made publicly available through regular public releases.
CMAQ may also refer to the Congestion Mitigation and Air Quality Improvement Program, a program of the United States Department of Transportation. | 1 | Applied and Interdisciplinary Chemistry |
When placed in benzylic or allylic positions, the strength of the bond is decreased, and the reactivity of the methyl group increases. One manifestation of this enhanced reactivity is the photochemical chlorination of the methyl group in toluene to give benzyl chloride. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, the standard state of a material (pure substance, mixture or solution) is a reference point used to calculate its properties under different conditions. A degree sign (°) or a superscript Plimsoll symbol () is used to designate a thermodynamic quantity in the standard state, such as change in enthalpy (ΔH°), change in entropy (ΔS°), or change in Gibbs free energy (ΔG°). The degree symbol has become widespread, although the Plimsoll is recommended in standards, see discussion about typesetting below.
In principle, the choice of standard state is arbitrary, although the International Union of Pure and Applied Chemistry (IUPAC) recommends a conventional set of standard states for general use. The standard state should not be confused with standard temperature and pressure (STP) for gases, nor with the standard solutions used in analytical chemistry. STP is commonly used for calculations involving gases that approximate an ideal gas, whereas standard state conditions are used for thermodynamic calculations.
For a given material or substance, the standard state is the reference state for the material's thermodynamic state properties such as enthalpy, entropy, Gibbs free energy, and for many other material standards. The standard enthalpy change of formation for an element in its standard state is zero, and this convention allows a wide range of other thermodynamic quantities to be calculated and tabulated. The standard state of a substance does not have to exist in nature: for example, it is possible to calculate values for steam at 298.15 K and , although steam does not exist (as a gas) under these conditions. The advantage of this practice is that tables of thermodynamic properties prepared in this way are self-consistent. | 0 | Theoretical and Fundamental Chemistry |
Surface energy is conventionally defined as the work that is required to build an area of a particular surface. Another way to view the surface energy is to relate it to the work required to cleave a bulk sample, creating two surfaces. If the new surfaces are identical, the surface energy γ of each surface is equal to half the work of cleavage, W: γ = (1/2)W.
If the surfaces are unequal, the Young-Dupré equation applies:
W = γ + γ – γ, where γ and γ are the surface energies of the two new surfaces, and γ is the interfacial energy.
This methodology can also be used to discuss cleavage that happens in another medium: γ = (1/2)W = (1/2)W. These two energy quantities refer to the energy that is needed to cleave one species into two pieces while it is contained in a medium of the other species. Likewise for a three species system: γ + γ – γ = W + W – W – W = W, where W is the energy of cleaving species 1 from species 2 in a medium of species 3.
A basic understanding of the terminology of cleavage energy, surface energy, and surface tension is very helpful for understanding the physical state and the events that happen at a given surface, but as discussed below, the theory of these variables also yields some interesting effects that concern the practicality of adhesive surfaces in relation to their surroundings. | 0 | Theoretical and Fundamental Chemistry |
Compounds and their metabolites need to be removed from the body via excretion, usually through the kidneys (urine) or in the feces. Unless excretion is complete, accumulation of foreign substances can adversely affect normal metabolism.
There are three main sites where drug excretion occurs. The kidney is the most important site and it is where products are excreted through urine. Biliary excretion or fecal excretion is the process that initiates in the liver and passes through to the gut until the products are finally excreted along with waste products or feces. The last main method of excretion is through the lungs (e.g. anesthetic gases).
Excretion of drugs by the kidney involves 3 main mechanisms:
* Glomerular filtration of unbound drug.
* Active secretion of (free & protein-bound) drug by transporters (e.g. anions such as urate, penicillin, glucuronide, sulfate conjugates) or cations such as choline, histamine.
* Filtrate 100-fold concentrated in tubules for a favorable concentration gradient so that it may be secreted by passive diffusion and passed out through the urine. | 1 | Applied and Interdisciplinary Chemistry |
Acarbose is a pseudotetrasaccharide mimicking maltotetraose (a substructure of starch). One of the glucose units has been replaced by valienamine - a carbasugar, linked to the next carbohydrate by an amine bridge. Another of the glucose units appears as a 6-deoxy variant. Acarbose is an enzyme inhibitor that is used as a drug against type 2 diabetes. | 1 | Applied and Interdisciplinary Chemistry |
ASL is in general a safe technique, although injuries may occur as a result of failed safety procedures or human error like other MRI techniques.
ASL, like other MRI modalities generate a fair amount of acoustic noise during the scan, so earplugs are advised. | 0 | Theoretical and Fundamental Chemistry |
Government agencies in China passed bans on the use of IVF in 2003 by unmarried people or by couples with certain infectious diseases.
In India, the use of IVF as a means of sex selection (preimplantation genetic diagnosis) is banned under the Pre-Conception and Pre-Natal Diagnostic Techniques Act, 1994.
Sunni Muslim nations generally allow IVF between married couples when conducted with their own respective sperm and eggs, but not with donor eggs from other couples. But Iran, which is Shia Muslim, has a more complex scheme. Iran bans sperm donation but allows donation of both fertilised and unfertilised eggs. Fertilised eggs are donated from married couples to other married couples, while unfertilised eggs are donated in the context of mutah or temporary marriage to the father.
By 2012 Costa Rica was the only country in the world with a complete ban on IVF technology, it having been ruled unconstitutional by the nations Supreme Court because it "violated life." Costa Rica had been the only country in the western hemisphere that forbade IVF. A law project sent reluctantly by the government of President Laura Chinchilla was rejected by parliament. President Chinchilla has not publicly stated her position on the question of IVF. However, given the massive influence of the Catholic Church in her government any change in the status quo seems very unlikely. In spite of Costa Rican government and strong religious opposition, the IVF ban has been struck down by the Inter-American Court of Human Rights in a decision of 20 December 2012. The court said that a long-standing Costa Rican guarantee of protection for every human embryo violated the reproductive freedom of infertile couples because it prohibited them from using IVF, which often involves the disposal of embryos not implanted in a womans uterus. On 10 September 2015, President Luis Guillermo Solís signed a decree legalising in-vitro fertilisation. The decree was added to the countrys official gazette on 11 September. Opponents of the practice have since filed a lawsuit before the countrys Constitutional Court.
All major restrictions on single but infertile people using IVF were lifted in Australia in 2002 after a final appeal to the Australian High Court was rejected on procedural grounds in the Leesa Meldrum case. A Victorian federal court had ruled in 2000 that the existing ban on all single women and lesbians using IVF constituted sex discrimination. Victoria's government announced changes to its IVF law in 2007 eliminating remaining restrictions on fertile single women and lesbians, leaving South Australia as the only state maintaining them.
Federal regulations in the United States include screening requirements and restrictions on donations, but generally do not affect sexually intimate partners. However, doctors may be required to provide treatments due to nondiscrimination laws, as for example in California. The US state of Tennessee proposed a bill in 2009 that would have defined donor IVF as adoption. During the same session another bill proposed barring adoption from any unmarried and cohabitating couple, and activist groups stated that passing the first bill would effectively stop unmarried women from using IVF. Neither of these bills passed.
In 2024, the Supreme Court of Alabama ruled that embryos created during in-vitro fertilisation are "extrauterine children", and that an 1872 state law allowing parents to sue over the death of a minor "applies to all unborn children, regardless of their location." This ruling raised concerns from The National Infertility Association and the American Society for Reproductive Medicine that the decision would mean Alabama's bans on abortion prohibit IVF as well, while the University of Alabama at Birmingham health system paused IVF treatments. Eight days later the Alabama legislature voted to protect IVF providers and patients from criminal or civil liability.
Few American courts have addressed the issue of the "property" status of a frozen embryo. This issue might arise in the context of a divorce case, in which a court would need to determine which spouse would be able to decide the disposition of the embryos. It could also arise in the context of a dispute between a sperm donor and egg donor, even if they were unmarried. In 2015, an Illinois court held that such disputes could be decided by reference to any contract between the parents-to-be. In the absence of a contract, the court would weigh the relative interests of the parties. | 1 | Applied and Interdisciplinary Chemistry |
All statins have the same pharmacophore so the difference in their pharmacodynamic effect is mostly based on the substituents. The activity of each statin is dependent on the binding affinity of the compound for the substrate site and the length of time it binds to the site. Type 2 statins have unique fluorophenyl group that causes additional polar interaction between the enzyme and the statins, which results in a tighter binding to the enzyme. The newest statin, rosuvastatin has a unique polar methane sulfonamide group, which is quite hydrophilic and confers low lipophilicity. The sulfonamide group forms a unique polar interaction with the enzyme. As a result, rosuvastatin has superior binding affinity to the HMGR enzyme compared to the other statins, which is directly related to its efficiency to lower LDL cholesterol. | 1 | Applied and Interdisciplinary Chemistry |
Lake Chichoj is located in the municipality of San Cristóbal Verapaz, department of Alta Verapaz, in Guatemala. The catchment of lake has been designated as a Protected Area, in an attempt to protect the lake from environmental degradation. Water routing through the catchment is made complex by karstic groundwater flow. It is estimated that the catchment of the lake drains . The lake in turn drains superficially to the Cahabón River, which flows to the Atlantic Ocean via Lake Izabal. | 1 | Applied and Interdisciplinary Chemistry |
A cosmid is a type of hybrid plasmid that contains a Lambda phage cos sequence. Often used as cloning vectors in genetic engineering, cosmids can be used to build genomic libraries. They were first described by Collins and Hohn in 1978.
Cosmids can contain 37 to 52 (normally 45) kb of DNA, limits based on the normal bacteriophage packaging size. They can replicate as plasmids if they have a suitable origin of replication (ori): for example SV40 ori in mammalian cells, ColE1 ori for double-stranded DNA replication, or f1 ori for single-stranded DNA replication in prokaryotes. They frequently also contain a gene for selection such as antibiotic resistance, so that the transformed cells can be identified by plating on a medium containing the antibiotic. Those cells which did not take up the cosmid would be unable to grow.
Unlike plasmids, they can also be packaged in vitro into phage capsids, a step which requires cohesive ends, also known as cos sites also used in cloning with a lambda phage as a vector, however nearly all the lambda genes have been deleted with the exception of the cos sequence. The hybrid cosmid DNA in the capsids can then be transferred into bacterial cells by transduction. Since there is a requirement for in vitro packaging whereby at least 38 kb of DNA is required between the cos sites, the vector without insert DNA will not be packaged (plasmids instability is increased if the novel inserted DNA contains many direct repeats or palindromic (inverted repeats) DNA. This instability can largely be counteracted by using a host bacterium with specific mutations affecting DNA recombination (N.B. Absence of inverted repeats was noted in the first Hohn & Collins publication cited above; see also). | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, transannular strain (also called Prelog strain after chemist Vladimir Prelog) is the unfavorable interactions of ring substituents on non-adjacent carbons. These interactions, called transannular interactions, arise from a lack of space in the interior of the ring, which forces substituents into conflict with one another. In medium-sized cycloalkanes, which have between 8 and 11 carbons constituting the ring, transannular strain can be a major source of the overall strain, especially in some conformations, to which there is also contribution from large-angle strain and Pitzer strain. In larger rings, transannular strain drops off until the ring is sufficiently large that it can adopt conformations devoid of any negative interactions.
Transannular strain can also be demonstrated in other cyclo-organic molecules, such as lactones, lactams, ethers, cycloalkenes, and cycloalkynes. These compounds are not without significance, since they are particularly useful in the study of transannular strain. Furthermore, transannular interactions are not relegated to only conflicts between hydrogen atoms, but can also arise from larger, more complicated substituents interacting across a ring. | 0 | Theoretical and Fundamental Chemistry |
Because the hull speed is related to the length of the boat and the wavelength of the wave it produces as it moves through water, there is another formula that arrives at the same values for hull speed based on the waterline length.
where
: is the length of the waterline in meters,
: is the hull speed of the vessel in meters per second, and
: is the acceleration due to gravity in meters per second squared.
This equation is the same as the equation used to calculate the speed of surface water waves in deep water. It dramatically simplifies the units on the constant before the radical in the empirical equation, while giving a deeper understanding of the principles at play. | 1 | Applied and Interdisciplinary Chemistry |
Inductively, the negatively charged carboxylate ion moderately repels the electrons in the bond attaching it to the ring. Thus, there is a weak electron-donating +I effect. There is an almost zero -M effect since the electron-withdrawing resonance capacity of the carbonyl group is effectively removed by the delocalisation of the negative charge of the anion on the oxygen. Thus overall the carboxylate group (unlike the carboxyl group) has an activating influence. | 0 | Theoretical and Fundamental Chemistry |
The human interactome is the set of protein–protein interactions (the interactome) that occur in human cells. The sequencing of reference genomes, in particular the Human Genome Project, has revolutionized human genetics, molecular biology, and clinical medicine. Genome-wide association study results have led to the association of genes with most Mendelian disorders, and over 140 000 germline mutations have been associated with at least one genetic disease. However, it became apparent that inherent to these studies is an emphasis on clinical outcome rather than a comprehensive understanding of human disease; indeed to date the most significant contributions of GWAS have been restricted to the “low-hanging fruit” of direct single mutation disorders, prompting a systems biology approach to genomic analysis. The connection between genotype and phenotype (how variation in genotype affects the disease or normal functioning of the cell and the human body) remain elusive, especially in the context of multigenic complex traits and cancer. To assign functional context to genotypic changes, much of recent research efforts have been devoted to the mapping of the networks formed by interactions of cellular and genetic components in humans, as well as how these networks are altered by genetic and somatic disease. | 1 | Applied and Interdisciplinary Chemistry |
Photons hitting a thin film of alkali metal or semiconductor material such as gallium arsenide in an image intensifier tube cause the ejection of photoelectrons due to the photoelectric effect. These are accelerated by an electrostatic field where they strike a phosphor coated screen, converting the electrons back into photons. Intensification of the signal is achieved either through acceleration of the electrons or by increasing the number of electrons through secondary emissions, such as with a micro-channel plate. Sometimes a combination of both methods is used. Additional kinetic energy is required to move an electron out of the conduction band and into the vacuum level. This is known as the electron affinity of the photocathode and is another barrier to photoemission other than the forbidden band, explained by the band gap model. Some materials such as gallium arsenide have an effective electron affinity that is below the level of the conduction band. In these materials, electrons that move to the conduction band all have sufficient energy to be emitted from the material, so the film that absorbs photons can be quite thick. These materials are known as negative electron affinity materials. | 0 | Theoretical and Fundamental Chemistry |
The technique of vibrational analysis with scanning probe microscopy allows probing vibrational properties of materials at the submicrometer scale, and even of individual molecules. This is accomplished by integrating scanning probe microscopy (SPM) and vibrational spectroscopy (Raman scattering or/and Fourier transform infrared spectroscopy, FTIR). This combination allows for much higher spatial resolution than can be achieved with conventional Raman/FTIR instrumentation. The technique is also nondestructive, requires non-extensive sample preparation, and provides more contrast such as intensity contrast, polarization contrast and wavelength contrast, as well as providing specific chemical information and topography images simultaneously. | 0 | Theoretical and Fundamental Chemistry |
There are a variety of probes with different membrane and shaft length combinations available. The molecular weight cutoff of commercially available microdialysis probes covers a wide range of approximately 6-100kD, but also 1MD is available. While water-soluble compounds generally diffuse freely across the microdialysis membrane, the situation is not as clear for highly lipophilic analytes, where both successful (e.g. corticosteroids) and unsuccessful microdialysis experiments (e.g. estradiol, fusidic acid) have been reported. However, the recovery of water-soluble compounds usually decreases rapidly if the molecular weight of the analyte exceeds 25% of the membrane’s molecular weight cutoff. | 1 | Applied and Interdisciplinary Chemistry |
The Woodward–Hoffmann rules (or the pericyclic selection rules) are a set of rules devised by Robert Burns Woodward and Roald Hoffmann to rationalize or predict certain aspects of the stereochemistry and activation energy of pericyclic reactions, an important class of reactions in organic chemistry. The rules originate in certain symmetries of the molecule's orbital structure that any molecular Hamiltonian conserves. Consequently, any symmetry-violating reaction must couple extensively to the environment; this imposes an energy barrier on its occurrence, and such reactions are called symmetry-forbidden. Their opposites are symmetry-allowed.
Although the symmetry-imposed barrier is often formidable (up to ca. 5 eV or 480 kJ/mol in the case of a forbidden [2+2] cycloaddition), the prohibition is not absolute, and symmetry-forbidden reactions can still take place if other factors (e.g. strain release) favor the reaction. Likewise, a symmetry-allowed reaction may be preempted by an insurmountable energetic barrier resulting from factors unrelated to orbital symmetry. All known cases only violate the rules superficially; instead, different parts of the mechanism become asynchronous, and each step conforms to the rules. | 0 | Theoretical and Fundamental Chemistry |
An estimated 30% of agrichemical compounds contain fluorine. Most of them are used as poisons, but a few stimulate growth instead.
Sodium fluoroacetate has been used as an insecticide, but it is especially effective against mammalian pests. The name "1080" refers to the catalogue number of the poison, which became its brand name. Fluoroacetate is similar to acetate, which has a pivotal role in the Krebs cycle (a key part of cell metabolism). Fluoroacetate halts the cycle and causes cells to be deprived of energy. Several other insecticides contain sodium fluoride, which is much less toxic than fluoroacetate. Insects fed 29-fluorostigmasterol use it to produce fluoroacetates. If a fluorine is transferred to a body cell, it blocks metabolism at the position occupied.
Trifluralin was widely used in the 20th century, for example, in over half of U.S. cotton field acreage in 1998. Because of its suspected carcinogenic properties some Northern European countries banned it in 1993. As of 2015, the European Union has banned it, although Dow made a case to cancel the decision in 2011. | 1 | Applied and Interdisciplinary Chemistry |
6-Phosphogluconic acid (6-phosphogluconate) is an intermediate in the pentose phosphate pathway and the Entner–Doudoroff pathway.
It is formed by 6-phosphogluconolactonase from 6 phosphogluconolactone, and acted upon by phosphogluconate dehydrogenase to produce ribulose 5-phosphate.These two steps are the part of Pentose Phosphate Pathway. It may also be acted upon by 6-phosphogluconate dehydratase to produce 2-keto-3-deoxy-6-phosphogluconate. | 1 | Applied and Interdisciplinary Chemistry |
Any 4-substituted pyridine, pyridine itself, 1-substituted pyrazinium ion, diazine, 1-substituted or unsubstituted pyrrole and related aromatic heterocyclics (phospholes, furan, thiophene, etc.) as well as unsubstituted or 1-substituted cyclopentadienes and 1-substituted cyclopentadienides all have the same symmetry framework as para-disubstituted or ortho-homodisubstituted benzenes, and will present chemically equivalent but magnetically inequivalent pairs of protons. In heterocycles and in five-membered rings in general, however, J values can be significantly smaller than in benzenes and the manifestation of magnetic inequivalence may be subtle.
The rarer seven-membered and higher ring systems may also show the same symmetry property, as can linked and fused aromatic ring systems such as biphenyls, naphthalenes and isoindoles. Similarly, 1-H benzimidazoles have the appropriate symmetry if N-deprotonated or N-protonated, or as a result of rapid tautomerization of the neutral form (for instance, in DMSO-d) where the signals greatly resemble those of 1,2-dichlorobenzene. | 0 | Theoretical and Fundamental Chemistry |
Soil chemistry is the study of the chemical characteristics of soil. Soil chemistry is affected by mineral composition, organic matter and environmental factors. In the early 1870s a consulting chemist to the Royal Agricultural Society in England, named J. Thomas Way, performed many experiments on how soils exchange ions, and is considered the father of soil chemistry. Other scientists who contributed to this branch of ecology include Edmund Ruffin, and Linus Pauling. | 0 | Theoretical and Fundamental Chemistry |
Although there was already a main project (magnetic mirror) at the University of California, scientist W. R. Baker began research into the pinch effect at UCRL, Berkeley in 1952. Two years later, Stirling Colgate began research on shock-heating at UCRL, Livermore. | 0 | Theoretical and Fundamental Chemistry |
The Weisz–Prater criterion is a method used to estimate the influence of pore diffusion on reaction rates in heterogeneous catalytic reactions. If the criterion is satisfied, pore diffusion limitations are negligible. The criterion is <br />
<br />
Where is the reaction rate per volume of catalyst, is the catalyst particle radius, is the reactant concentration at the particle surface, and is the effective diffusivity. Diffusion is usually in the Knudsen regime when average pore radius is less than 100 nm.<br />
For a given effectiveness factor,, and reaction order, n, the quantity is defined by the equation:<br />
<br />
for small values of beta this can be approximated using the binomial theorem:<br />
<br />
Assuming with a reaction order gives value of equal to 0.1. Therefore, for many conditions, if then pore diffusion limitations can be excluded. | 1 | Applied and Interdisciplinary Chemistry |
Lithium plasma concentrations are known to be increased with concurrent use of diuretics—especially loop diuretics (such as furosemide) and thiazides—and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. Lithium concentrations can also be increased with concurrent use of ACE inhibitors such as captopril, enalapril, and lisinopril.
Lithium is primarily cleared from the body through glomerular filtration, but some is then reabsorbed together with sodium through the proximal tubule. Its levels are therefore sensitive to water and electrolyte balance. Diuretics act by lowering water and sodium levels; this causes more reabsorption of lithium in the proximal tubules so that the removal of lithium from the body is less, leading to increased blood levels of lithium. ACE inhibitors have also been shown in a retrospective case-control study to increase lithium concentrations. This is likely due to constriction of the afferent arteriole of the glomerulus, resulting in decreased glomerular filtration rate and clearance. Another possible mechanism is that ACE inhibitors can lead to a decrease in sodium and water. This will increase lithium reabsorption and its concentrations in the body.
There are also drugs that can increase the clearance of lithium from the body, which can result in decreased lithium levels in the blood. These drugs include theophylline, caffeine, and acetazolamide. Additionally, increasing dietary sodium intake may also reduce lithium levels by prompting the kidneys to excrete more lithium.
Lithium is known to be a potential precipitant of serotonin syndrome in people concurrently on serotonergic medications such as antidepressants, buspirone and certain opioids such as pethidine (meperidine), tramadol, oxycodone, fentanyl and others. Lithium co-treatment is also a risk factor for neuroleptic malignant syndrome in people on antipsychotics and other antidopaminergic medications.
High doses of haloperidol, fluphenazine, or flupenthixol may be hazardous when used with lithium; irreversible toxic encephalopathy has been reported.
Indeed, these and other antipsychotics have been associated with increased risk of lithium neurotoxicity, even with low therapeutic lithium doses.
Classical psychedelics such as psilocybin and LSD may cause seizures if taken while using lithium, although further research is needed. | 1 | Applied and Interdisciplinary Chemistry |
The CSI is a graph-based technique that essentially employs an amino acid-specific digital filter to convert every assigned backbone chemical shift value into a simple three-state (-1, 0, +1) index. This approach generates a more easily understood and much more visually pleasing graph of protein chemical shift values. In particular, if the upfield Hα chemical shift (relative to an amino acid-specific random coil value) of a certain residue is > 0.1 ppm, then that amino acid residue is assigned a value of -1. Similarly, if the downfield Hα chemical shift of a certain amino acid residue is > 0.1 ppm then that residue is assigned a value of +1. If an amino acid residue's chemical shift is not shifted downfield or upfield by a sufficient amount (i.e. <0.1 ppm), it is given a value of 0. When this 3-state index is plotted as a bar graph over the full length of the protein sequence, simple inspection can allow one to identify beta strands (clusters of +1 values), alpha helices (clusters of -1 values), and random coil segments (clusters of 0 values). A list of the amino acid-specific random coil chemical shifts for CSI calculations is given in Table 1. An example of a CSI graph for a small protein is shown in Figure 1 with the arrows located above the black bars indicating locations of the beta strands and the rectangular box indicating the location of a helix. | 0 | Theoretical and Fundamental Chemistry |
The Pederson process is a process of refining aluminum that first separates iron by reducing it to metal, and reacting alumina with lime to produce calcium aluminate, which is then leached with sodium hydroxide. It is more environmentally friendly than the more well-known Bayer process. This is because instead of producing alumina slag, also known as red mud, it produces pig iron as a byproduct. Red mud is considered both an economic and environmental challenge in the aluminum industry because it is considered a waste, with little benefit. It destroys the environment with its high pH, and is costly to maintain, even when in a landfill. Iron, however, is used in the manufacture of steel, and has structural uses in civil engineering and chemical uses as a catalyst. | 1 | Applied and Interdisciplinary Chemistry |
1,4-Dioxane () is a heterocyclic organic compound, classified as an ether. It is a colorless liquid with a faint sweet odor similar to that of diethyl ether. The compound is often called simply dioxane because the other dioxane isomers (1,2- and 1,3-) are rarely encountered.
Dioxane is used as a solvent for a variety of practical applications as well as in the laboratory, and also as a stabilizer for the transport of chlorinated hydrocarbons in aluminium containers. | 0 | Theoretical and Fundamental Chemistry |
Corrosion in space has the highest impact on spacecraft with moving parts. Early satellites tended to develop problems with seizing bearings. Now the bearings are coated with a thin layer of gold.
Different materials resist corrosion in space differently. For example, aluminium is slowly eroded by atomic oxygen, while gold and platinum are highly corrosion-resistant. Gold-coated foils and thin layers of gold on exposed surfaces are therefore used to protect the spacecraft from the harsh environment. Thin layers of silicon dioxide deposited on the surfaces can also protect metals from the effects of atomic oxygen; e.g., the Starshine 3 satellite aluminium front mirrors were protected that way. However, the protective layers are subject to erosion by micrometeorites.
Silver builds up a layer of silver oxide, which tends to flake off and has no protective function; such gradual erosion of silver interconnects of solar cells was found to be the cause of some observed in-orbit failures.
Many plastics are considerably sensitive to atomic oxygen and ionizing radiation. Coatings resistant to atomic oxygen are a common protection method, especially for plastics. Silicone-based paints and coatings are frequently employed, due to their excellent resistance to radiation and atomic oxygen. However, the silicone durability is somewhat limited, as the surface exposed to atomic oxygen is converted to silica which is brittle and tends to crack. | 1 | Applied and Interdisciplinary Chemistry |
The mechanism of PEP carboxylase has been well studied. The enzymatic mechanism of forming oxaloacetate is very exothermic and thereby irreversible; the biological Gibbs free energy change (△G°’) is -30kJmol. The substrates and cofactor bind in the following order: metal cofactor (either Co, Mg, or Mn), PEP, bicarbonate (HCO). The mechanism proceeds in two major steps, as described below and shown in figure 2:
# The bicarbonate acts as a nucleophile to attack the phosphate group in PEP. This results in the splitting of PEP into a carboxyphosphate and the (very reactive) enolate form of pyruvate.
# Proton transfer takes place at the carboxyphosphate. This is most likely modulated by a histidine (H138) residue that first deprotonates the carboxy side, and then, as an acid, protonates the phosphate part. The carboxyphosphate then exothermically decomposes into carbon dioxide and inorganic phosphate, at this point making this an irreversible reaction. Finally, after the decomposition, the carbon dioxide is attacked by the enolate to form oxaloacetate.
The metal cofactor is necessary to coordinate the enolate and carbon dioxide intermediates; the CO molecule is only lost 3% of the time. The active site is hydrophobic to exclude water, since the carboxyphosphate intermediate is susceptible to hydrolysis. | 0 | Theoretical and Fundamental Chemistry |
Hydrazones are the basis for various analyses of ketones and aldehydes. For example, dinitrophenylhydrazine coated onto a silica sorbent is the basis of an adsorption cartridge. The hydrazones are then eluted and analyzed by high-performance liquid chromatography (HPLC) using a UV detector.
The compound carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (abbreviated as FCCP) is used to uncouple ATP synthesis and reduction of oxygen in oxidative phosphorylation in molecular biology.
Hydrazones are the basis of bioconjugation strategies. Hydrazone-based coupling methods are used in medical biotechnology to couple drugs to targeted antibodies (see ADC), e.g. antibodies against a certain type of cancer cell. The hydrazone-based bond is stable at neutral pH (in the blood), but is rapidly destroyed in the acidic environment of lysosomes of the cell. The drug is thereby released in the cell, where it exerts its function. | 0 | Theoretical and Fundamental Chemistry |
Photoexcitation is the production of an excited state of a quantum system by photon absorption. The excited state originates from the interaction between a photon and the quantum system. Photons carry energy that is determined by the wavelengths of the light that carries the photons. Objects that emit light with longer wavelengths, emit photons carrying less energy. In contrast to that, light with shorter wavelengths emit photons with more energy. When the photon interacts with a quantum system, it is therefore important to know what wavelength one is dealing with. A shorter wavelength will transfer more energy to the quantum system than longer wavelengths.
On the atomic and molecular scale photoexcitation is the photoelectrochemical process of electron excitation by photon absorption, when the energy of the photon is too low to cause photoionization. The absorption of the photon takes place in accordance with Planck's quantum theory.
Photoexcitation plays a role in photoisomerization and is exploited in different techniques:
*Dye-sensitized solar cells makes use of photoexcitation by exploiting it in cheaper inexpensive mass production solar cells. The solar cells rely on a large surface area in order to catch and absorb as many high energy photons as possible. Shorter wavelengths are more efficient for the energy conversion compared to longer wavelengths, since shorter wavelengths carry photons that are more energy rich. Light containing shorter wavelengths therefore cause a longer and less efficient conversion of energy in dye-sensitized solar cells.
*Photochemistry
*Luminescence
*Optically pumped lasers use photoexcitation in a way that the excited atoms in the lasers get an enormous direct-gap gain needed for the lasers. The density that is needed for the population inversion in the compound Ge, a material often used in lasers, must become 10 cm, and this is acquired via photoexcitation. The photoexcitation causes the electrons in atoms to go to an excited state. The moment the amount of atoms in the excited state is higher than the amount in the normal ground state, the population inversion occurs. The inversion, like the one caused with germanium, makes it possible for materials to act as lasers.
*Photochromic applications. Photochromism causes a transformation of two forms of a molecule by absorbing a photon. For example, the BIPS molecule(2H-l-benzopyran-2,2-indolines) can convert from trans to cis and back by absorbing a photon. The different forms are associated with different absorption bands. In a cis-form of BIPS, the transient absorption band has a value of 21050 cm, in contrast to the band from the trans-form, that has a value of 16950 cm. The results were optically visible, where the BIPS in gels turned from a colorless appearance to a brown or pink color after repeatedly being exposed to a high energy UV pump beam. High energy photons cause a transformation in the BIPS molecule making the molecule change its structure.
On the nuclear scale photoexcitation includes the production of nucleon and delta baryon resonances in nuclei. | 0 | Theoretical and Fundamental Chemistry |
Angles are, by convention, considered to be dimensionless quantities (although the wisdom of this is contested ) . As an example, consider again the projectile problem in which a point mass is launched from the origin at a speed and angle above the x-axis, with the force of gravity directed along the negative y-axis. It is desired to find the range , at which point the mass returns to the x-axis. Conventional analysis will yield the dimensionless variable , but offers no insight into the relationship between and .
Siano has suggested that the directed dimensions of Huntley be replaced by using orientational symbols to denote vector directions, and an orientationless symbol 1. Thus, Huntley's L becomes L1 with L specifying the dimension of length, and specifying the orientation. Siano further shows that the orientational symbols have an algebra of their own. Along with the requirement that , the following multiplication table for the orientation symbols results:
The orientational symbols form a group (the Klein four-group or "Viergruppe"). In this system, scalars always have the same orientation as the identity element, independent of the "symmetry of the problem". Physical quantities that are vectors have the orientation expected: a force or a velocity in the z-direction has the orientation of . For angles, consider an angle that lies in the z-plane. Form a right triangle in the z-plane with being one of the acute angles. The side of the right triangle adjacent to the angle then has an orientation and the side opposite has an orientation . Since (using to indicate orientational equivalence) we conclude that an angle in the xy-plane must have an orientation , which is not unreasonable. Analogous reasoning forces the conclusion that has orientation while has orientation 1. These are different, so one concludes (correctly), for example, that there are no solutions of physical equations that are of the form , where and are real scalars. An expression such as is not dimensionally inconsistent since it is a special case of the sum of angles formula and should properly be written:
which for and yields . Siano distinguishes between geometric angles, which have an orientation in 3-dimensional space, and phase angles associated with time-based oscillations, which have no spatial orientation, i.e. the orientation of a phase angle is .
The assignment of orientational symbols to physical quantities and the requirement that physical equations be orientationally homogeneous can actually be used in a way that is similar to dimensional analysis to derive more information about acceptable solutions of physical problems. In this approach, one solves the dimensional equation as far as one can. If the lowest power of a physical variable is fractional, both sides of the solution is raised to a power such that all powers are integral, putting it into normal form. The orientational equation is then solved to give a more restrictive condition on the unknown powers of the orientational symbols. The solution is then more complete than the one that dimensional analysis alone gives. Often, the added information is that one of the powers of a certain variable is even or odd.
As an example, for the projectile problem, using orientational symbols, , being in the xy-plane will thus have dimension and the range of the projectile will be of the form:
Dimensional homogeneity will now correctly yield and , and orientational homogeneity requires that . In other words, that must be an odd integer. In fact, the required function of theta will be which is a series consisting of odd powers of .
It is seen that the Taylor series of and are orientationally homogeneous using the above multiplication table, while expressions like and are not, and are (correctly) deemed unphysical.
Siano's orientational analysis is compatible with the conventional conception of angular quantities as being dimensionless, and within orientational analysis, the radian may still be considered a dimensionless unit. The orientational analysis of a quantity equation is carried out separately from the ordinary dimensional analysis, yielding information that supplements the dimensional analysis. | 1 | Applied and Interdisciplinary Chemistry |
Atamestane (developmental code name SH-489), also known as metandroden, as well as 1-methylandrosta-1,4-diene-3,17-dione, is a steroidal aromatase inhibitor that was studied in the treatment of cancer. It blocks the production of estrogen in the body. The drug is selective, competitive, and irreversible in its inhibition of aromatase. | 0 | Theoretical and Fundamental Chemistry |
The modifications try to account for the points mentioned in above section like surface roughness, inhomogeneity, and adsorbate–adsorbate interactions. | 0 | Theoretical and Fundamental Chemistry |
Vertebrates were once thought to be unable to perform this cycle because there was no evidence of its two key enzymes, isocitrate lyase and malate synthase. However, some research suggests that this pathway may exist in some, if not all, vertebrates.
Specifically, some studies show evidence of components of the glyoxylate cycle existing in significant amounts in the liver tissue of chickens. Data such as these support the idea that the cycle could theoretically occur in even the most complex vertebrates. Other experiments have also provided evidence that the cycle is present among certain insect and marine invertebrate species, as well as strong evidence of the cycle's presence in nematode species. However, other experiments refute this claim. Some publications conflict on the presence of the cycle in mammals: for example, one paper has stated that the glyoxylate cycle is active in hibernating bears, but this report was disputed in a later paper. Evidence exists for malate synthase activity in humans due to a dual functional malate/B-methylmalate synthase of mitochondrial origin called CLYBL expressed in brown fat and kidney. Vitamin D may regulate this pathway in vertebrates. | 1 | Applied and Interdisciplinary Chemistry |
Some examples of glow-in-the-dark materials do not glow by phosphorescence. For example, glow sticks glow due to a chemiluminescent process which is commonly mistaken for phosphorescence. In chemiluminescence, an excited state is created via a chemical reaction. The light emission tracks the kinetic progress of the underlying chemical reaction. The excited state will then transfer to a dye molecule, also known as a sensitizer or fluorophor, and subsequently fluoresce back to the ground state. | 0 | Theoretical and Fundamental Chemistry |
Closantel and triclosan are known inhibitors of quorum sensing enzymes. Closantel induces aggregation of the histidine kinase sensor in two-component signalling. The latter disrupts the synthesis of a class of signalling molecules known as N-acyl homoserine lactones (AHLs) by blocking the enoyl-acyl carrier protein (ACP) reductase. | 1 | Applied and Interdisciplinary Chemistry |
The water gas shift reaction (CO + HO → CO + H) occurs in volcanic fluids with diverse catalysts or without catalysts. The combination of ferrous sulfide (FeS, troilite) and hydrogen sulfide () as reducing agents (both reagents are simultaneously oxidized in the reaction here under creating the disulfide bond, S–S) in conjunction with pyrite () formation:
: FeS + HS → FeS + 2 H + 2 e
: or with H directly produced instead of 2 H + 2 e
: FeS + HS → FeS + H
has been demonstrated under mild volcanic conditions. This key result has been disputed. Nitrogen fixation has been demonstrated for the isotope N in conjunction with pyrite formation. Ammonia forms from nitrate with FeS/HS as reductant. Methylmercaptan [CH-SH] and carbon oxysulfide [COS] form from CO and FeS/HS, or from CO and H in the presence of NiS. | 1 | Applied and Interdisciplinary Chemistry |
The mechanism of conformational proofreading is utilized in the system of homologous recombination to discern between similar DNA sequences. Homologous recombination facilitates the exchange of genetic material between homologous DNA molecules. This crucial process requires detecting a specific homologous DNA sequence within a huge variety of heterologous sequences. The detection is mediated by RecA in E. coli, or members of its superfamily in other organisms. RecA first polymerizes along a stretch of single-stranded DNA, and then this protein-DNA filament searches for homology along double-stranded DNA. In the RecA-DNA filament, the distance between bases increases significantly with respect to the bare 3.4 Å in the double-strand (by 50% on average).
This sets a significant energetic barrier on the search, since the double-stranded DNA has to stretch by the same magnitude to check for homology.
By formulating the DNA recognition process as a signal detection problem, it was shown that the experimentally observed RecA-induced DNA deformation and the binding energetics are fine-tuned to ensure optimal sequence detection. The amount of deformation is such that binding to homologous DNA sequences only slightly decreases, while binding to wrong sequences decreases significantly. This is exactly the conformational proofreading mechanism. | 1 | Applied and Interdisciplinary Chemistry |
Martin Schröder in an inorganic chemist. He is Vice President and Dean for the Faculty of Science and Engineering and Professor of Chemistry in the Department of Chemistry at the University of Manchester since June 2015. He served previously as Executive Dean of the Faculty of Science from 2011 to 2015 and Professor of Inorganic Chemistry at the University of Nottingham from 1995 to 2015. | 0 | Theoretical and Fundamental Chemistry |
The term forensic stems from the Latin word, forēnsis (3rd declension, adjective), meaning "of a forum, place of assembly". The history of the term originates in Roman times, when a criminal charge meant presenting the case before a group of public individuals in the forum. Both the person accused of the crime and the accuser would give speeches based on their sides of the story. The case would be decided in favor of the individual with the best argument and delivery. This origin is the source of the two modern usages of the word forensic—as a form of legal evidence; and as a category of public presentation.
In modern use, the term forensics is often used in place of "forensic science."
The word "science", is derived from the Latin word for knowledge and is today closely tied to the scientific method, a systematic way of acquiring knowledge. Taken together, forensic science means the use of scientific methods and processes for crime solving. | 0 | Theoretical and Fundamental Chemistry |
Polymerase III terminates transcription at small polyUs stretch (5-6). In eukaryotes, a hairpin loop is not required, but may enhance termination efficiency in humans. In Saccharomyces cerevisiae, it was found that termination of transcription occurred in the sequence T7GT6 and was progressive. The presence of transcripts with five, six, and seven U residues and the slow readthrough of the T7 stretch suggest that the incorporation of a single G into the RNA chain served to reset elongation rates either entirely or substantially. | 1 | Applied and Interdisciplinary Chemistry |
As listed by ECS:
* 2023 Fred Roozeboom
* 2021 Hiroshi Iwai
* 2019 David J. Lockwood
* 2015 Yue Kuo
* 2005 Dennis Hess
* 1999 Isamu Akasaki
* 1995 Wayne L. Worrell
* 1993 Bruce E. Deal
* 1987 Alfred Y. Cho
* 1985 Jerry M. Woodall
* 1983 Nick Holonyak, Jr.
* 1981 Gerald L. Pearson
* 1979 Morton B. Panish
* 1977 Robert N. Hall
* 1973 William G. Pfann | 0 | Theoretical and Fundamental Chemistry |
Endocannabinoids are known to influence synaptic plasticity, and are in particular thought to mediate long-term depression (LTD, which refers to neuronal firing, not psychological depression). Short-term depression (STD) has also been described (see the next paragraph). First reported in the striatum, this system is known to function in several other brain structures such as the nucleus accumbens, amygdala, hippocampus, cerebral cortex, cerebellum, ventral tegmental area (VTA), brain stem, and superior colliculus. Typically, these retrograde transmitters are released by the postsynaptic neuron and induce synaptic depression by activating the presynaptic CB1 receptors.
It has further been suggested that different endocannabinoids, i.e., 2-AG and anandamide, might mediate different forms of synaptic depression through different mechanisms. The study conducted with the bed nucleus of the stria terminalis found that the endurance of the depressant effects was mediated by two different signaling pathways based on the type of receptor activated. 2-AG was found to act on presynaptic CB receptors to mediate retrograde STD following activation of L-type calcium channeles, while anandamide was synthesized after mGluR5 activation and triggered autocrine signalling onto postsynapic TRPV1 receptors that induced LTD. These findings provide the brain a direct mechanism to selectively inhibit neuronal excitability over variable time scales. By selectively internalizing different receptors, the brain may limit the production of specific endocannabinoids to favor a time scale in accordance with its needs. | 1 | Applied and Interdisciplinary Chemistry |
Crystal field excitation is the electronic transition of an electron between two orbitals of an atom that is situated in a crystal field environment. They are often observed in coordination complexes of transition metals. Some examples of crystal field excitations are dd-transitions on a copper atom that is surrounded by an octahedron of oxygen atoms, or ff-transitions on the uranium atom in uranium antimonide. | 0 | Theoretical and Fundamental Chemistry |
The Wilhelmy plate tensiometer requires a plate to make contact with the liquid surface. It is widely considered the simplest and most accurate method for surface tension measurement. Due to a large wetted length of the platinum plate, the surface tension reading is typically very stable compared to alternative methods. As an additional benefit, the Wilhelmy plate can also be made from paper for disposable use. For interfacial tension measurements, buoyancy of the probe needs to be taken into account which complicates the measurement. | 0 | Theoretical and Fundamental Chemistry |
Superconducting materials are characterized by the loss of resistance and two parameters: a critical temperature T and a critical magnetic field which brings the
superconductor to its normal state. In 1911, H. Kamerlingh Onnes discovered the superconductivity of mercury at a temperature below 4 K. Later,
other substances with superconductivity at temperatures up to 30 K were found. Superconductors prevent the penetration of the external magnetic field
into the sample when the magnetic field strength is less than the critical value. This effect was called the Meissner effect.
High-temperature superconductivity was discovered in the 1980s. Of the known compounds, the highest critical temperature T = 135 K belongs to
HgBaCaCuO.
Low-temperature superconductivity has found a theoretical explanation in the model of Bardeen, Cooper, and Schrieffer (BCS theory).
The physical basis of the model is the phenomenon of Cooper pairing of electrons. Since a pair of electrons carries an integer spin, the correlated states of the electrons can form a Bose–Einstein condensate.
An equivalent formalism was developed by Bogoliubov
and Valatin
Cooper pairing of nucleons takes place in ordinary nuclei. The effect manifests itself in the Bethe–Weizsacker mass formula, the last pairing term
of which describes the correlation energy of two nucleons. Because of the pairing, the binding energy of even-even nuclei systematically exceeds the binding energy of odd-even and
odd-odd nuclei. | 0 | Theoretical and Fundamental Chemistry |
The Balliol-Trinity Laboratories in Oxford, England, was an early chemistry laboratory at the University of Oxford.
The laboratory was located between Balliol College and Trinity College, hence the name. It was especially known for physical chemistry.
Chemistry was first recognized as a separate discipline at Oxford University in the 19th century. From 1855, a chemistry laboratory existed in a basement at Balliol College. In 1879, Balliol and Trinity agreed to have a laboratory at the boundary of the two colleges. The laboratory became the strongest of the Oxford college research institutions in chemistry. It remained in operation until the Second World War when a new Physical Chemistry Laboratory (PCL) was constructed by Oxford University in the Science Area. | 0 | Theoretical and Fundamental Chemistry |
In 2019, the European Council requested the European Commission to develop an action plan to eliminate all non-essential uses of PFAS due to the growing evidence of adverse effects caused by exposure to these substances; the evidence for the widespread occurrence of PFAS in water, soil, articles, and waste; and the threat it can pose to drinking water. Germany, the Netherlands, Denmark, Norway, and Sweden submitted a so-called restriction proposal based on the REACH regulation to achieve a European ban on the production, use, sale and import of PFAS. The proposal states that a ban is necessary for all use of PFAS, with different periods for different applications when the ban takes effect (immediately after the restriction comes into force, 5 years afterwards, or 12 years afterwards), depending on the function and the availability of alternatives. The proposal has not assessed the use of PFAS in medicines, plant protection products and biocides because specific regulations apply to those substances (Biocidal Products Regulation, Plant Protection Products Regulation, Medicinal Products Regulation) that have an explicit authorization procedure that focuses on risk for health and the environment.
The proposal was submitted on 13 January 2023 and published by the European Chemicals Agency (ECHA) on 7 February. From 22 March to 21 September, citizens, companies and other organizations can comment on the proposal during a public consultation. Based on the information in the restriction proposal and the consultation, two committees from ECHA formulate an opinion on the risk and socio-economic aspects of the proposed restriction. Within a year of publication, the opinions are sent to the European Commission, which makes a final proposal that is submitted to the EU Member States for discussion and decision. Eighteen months after the publication of the restriction decision (which may differ from the original proposal), it will enter the ban. | 0 | Theoretical and Fundamental Chemistry |
Yueh-Lin (Lynn) Loo is a Malaysian-born chemical engineer and the Theodora D. 78 and William H. Walton III 74 Professor in Engineering at Princeton University, where she is also the Director of the Andlinger Center for Energy and the Environment. She is known for inventing nanotransfer printing. Loo was elected a Fellow of the Materials Research Society in 2020. | 1 | Applied and Interdisciplinary Chemistry |
The van Oss theory separates the surface energy of solids and liquids into three components. It includes the dispersive surface energy, as before, and subdivides the polar component as being the sum of two more specific components: the surface energy due to acidic interactions () and due to basic interactions (). The acid component theoretically describes a surface's propensity to have polar interactions with a second surface that has the ability to act basic by donating electrons. Conversely, the base component of the surface energy describes the propensity of a surface to have polar interactions with another surface that acts acidic by accepting electrons. The principle equation for this theory is
Again, the best way to deal with this theory, much like the two-component theories, is to use at least three liquids (more can be used to get more results for statistical purposes) one with only a dispersive component in its surface energy (), one with only a dispersive and an acidic or basic component (), and finally either a liquid with a dispersive and a basic or acidic component (whichever the second probe liquid did not have ()), or a liquid with all three components () and linearizing the results.
It is naturally more robust than other theories, particularly in cases where there is a great imbalance between the acid and base components of the polar surface energy. The van Oss theory is most suitable for testing the surface energies of inorganics, organometallics, and surface containing ions.
The most significant difficulty of applying the van Oss theory is the fact that there is not much of an agreement in regards to a set of reference solids that can be used to characterize the acid and base components of potential probe liquids. There are however some liquids that are generally agreed to have known dispersive/acid/base components to their surface energies. Two of them are listed in table 1. | 0 | Theoretical and Fundamental Chemistry |
Optical molasses is a laser cooling technique that can cool neutral atoms to as low as a few microkelvin, depending on the atomic species. An optical molasses consists of 3 pairs of counter-propagating circularly polarized laser beams intersecting in the region where the atoms are present. The main difference between optical molasses and an MOT is the absence of magnetic field in the former. Therefore, unlike a MOT, an optical molasses provides only cooling and no trapping. | 0 | Theoretical and Fundamental Chemistry |
Silt particles range in size (about 0.002–0.5 mm). Silt pores are considered a medium in size compared with the other particle groups. Silt has a texture consistency of flour. Silt particles allow water and air to pass readily, yet retain moisture for crop growth. Silty soil contains sufficient quantities of nutrients, both organic and inorganic. | 0 | Theoretical and Fundamental Chemistry |
In biological systems, nucleic acids contain information which is used by a living cell to construct specific proteins. The sequence of nucleobases on a nucleic acid strand is translated by cell machinery into a sequence of amino acids making up a protein strand. Each group of three bases, called a codon, corresponds to a single amino acid, and there is a specific genetic code by which each possible combination of three bases corresponds to a specific amino acid.
The central dogma of molecular biology outlines the mechanism by which proteins are constructed using information contained in nucleic acids. DNA is transcribed into mRNA molecules, which travel to the ribosome where the mRNA is used as a template for the construction of the protein strand. Since nucleic acids can bind to molecules with complementary sequences, there is a distinction between "sense" sequences which code for proteins, and the complementary "antisense" sequence, which is by itself nonfunctional, but can bind to the sense strand. | 1 | Applied and Interdisciplinary Chemistry |
The Kratky plot is typically used to analyze the conformation of proteins but can be used to analyze the random walk model of polymers. A Kratky plot can be made by plotting sin(θ/2)ΔR(θ) vs sin(θ/2) or qΔR(θ) vs q. | 0 | Theoretical and Fundamental Chemistry |
In United States patent law, incredible utility is a concept according to which, in order for an invention to be patentable, it must have some credible useful function. If it does not have a credible useful function despite the assertions of the inventor, then the application for patent can be rejected as having "incredible utility". The invention does not have to work the way the inventor thinks it works, but it must do something useful. Patents that have been held invalid for incredible utility include:
* an invention asserted to change the taste of food using a magnetic field (Fregeau v. Mossinghoff, 776 F.2d 1034, 227 USPQ 848 (Fed. Cir. 1985)),
* a perpetual motion machine (Newman v. Quigg, 877 F.2d 1575, 11 USPQ2d 1340 (Fed. Cir. 1989)),
* a flying machine operating on "flapping or flutter function" (In re Houghton, 433 F.2d 820, 167 USPQ 687 (CCPA 1970)),
* a cold fusion process for producing energy (In re Swartz, 232 F.3d 862, 56 USPQ2d 1703, (Fed. Cir. 2000)),
* a method for increasing the energy output of fossil fuels upon combustion through exposure to a magnetic field (In re Ruskin, 354 F.2d 395, 148 USPQ 221 (CCPA 1966)),
* uncharacterized compositions for curing a wide array of cancers (In re Citron, 325 F.2d 248, 139 USPQ 516 (CCPA 1963)), and
* a method of controlling the aging process (In re Eltgroth, 419 F.2d 918, 164 USPQ 221 (CCPA 1970)).
A rejection based on incredible utility can be overcome by providing evidence that, "if, considered as a whole, [...] leads a person of ordinary skill in the art to conclude that the asserted utility is more likely than not true". | 0 | Theoretical and Fundamental Chemistry |
OJSC Dolomite () forms part of the Russia metallurgical complex, being the only producer of metallurgical dolomite in the Central Black Earth economic region. The company mines 55% of the total amount of dolomite produced in Russia and 43% in CIS. It is part of the NLMK Group.
The company has explored the Dankov dolomite field (Lipetsk Oblast) since 1932. The product mix includes fluxed and converter dolomite, dolomite flour, crushed rock for construction and road works. The facility is located near to developed transport infrastructure, which is strategically advantageous for its customers.
In 2005 the Company production reached 1.9 mln. tonnes. Dolomite is mainly sold in the domestic market. The main customers are steelmaking companies; their share is 69% of the total sales volume. NLMKs share in the companys sales structure amounted to 51% in 2005. | 1 | Applied and Interdisciplinary Chemistry |
The skeletal structure of an organic compound is the series of atoms bonded together that form the essential structure of the compound. The skeleton can consist of chains, branches and/or rings of bonded atoms. Skeletal atoms other than carbon or hydrogen are called heteroatoms.
The skeleton has hydrogen and/or various substituents bonded to its atoms. Hydrogen is the most common non-carbon atom that is bonded to carbon and, for simplicity, is not explicitly drawn. In addition, carbon atoms are not generally labelled as such directly (i.e. with "C"), whereas heteroatoms are always explicitly noted as such ("N" for nitrogen, "O" for oxygen, etc.)
Heteroatoms and other groups of atoms that give rise to relatively high rates of chemical reactivity, or introduce specific and interesting characteristics in the spectra of compounds are called functional groups, as they give the molecule a function. Heteroatoms and functional groups are collectively called "substituents", as they are considered to be a substitute for the hydrogen atom that would be present in the parent hydrocarbon of the organic compound. | 0 | Theoretical and Fundamental Chemistry |
Consider a scalar quantity , where is time and is position. Here may be some physical variable such as temperature or chemical concentration. The physical quantity, whose scalar quantity is , exists in a continuum, and whose macroscopic velocity is represented by the vector field .
The (total) derivative with respect to time of is expanded using the multivariate chain rule:
It is apparent that this derivative is dependent on the vector
which describes a chosen path in space. For example, if is chosen, the time derivative becomes equal to the partial time derivative, which agrees with the definition of a partial derivative: a derivative taken with respect to some variable (time in this case) holding other variables constant (space in this case). This makes sense because if , then the derivative is taken at some constant position. This static position derivative is called the Eulerian derivative.
An example of this case is a swimmer standing still and sensing temperature change in a lake early in the morning: the water gradually becomes warmer due to heating from the sun. In which case the term is sufficient to describe the rate of change of temperature.
If the sun is not warming the water (i.e. ), but the path is not a standstill, the time derivative of may change due to the path. For example, imagine the swimmer is in a motionless pool of water, indoors and unaffected by the sun. One end happens to be at a constant high temperature and the other end at a constant low temperature. By swimming from one end to the other the swimmer senses a change of temperature with respect to time, even though the temperature at any given (static) point is a constant. This is because the derivative is taken at the swimmer's changing location and the second term on the right is sufficient to describe the rate of change of temperature. A temperature sensor attached to the swimmer would show temperature varying with time, simply due to the temperature variation from one end of the pool to the other.
The material derivative finally is obtained when the path is chosen to have a velocity equal to the fluid velocity
That is, the path follows the fluid current described by the fluid's velocity field . So, the material derivative of the scalar is
An example of this case is a lightweight, neutrally buoyant particle swept along a flowing river and experiencing temperature changes as it does so. The temperature of the water locally may be increasing due to one portion of the river being sunny and the other in a shadow, or the water as a whole may be heating as the day progresses. The changes due to the particles motion (itself caused by fluid motion) is called advection' (or convection if a vector is being transported).
The definition above relied on the physical nature of a fluid current; however, no laws of physics were invoked (for example, it was assumed that a lightweight particle in a river will follow the velocity of the water), but it turns out that many physical concepts can be described concisely using the material derivative. The general case of advection, however, relies on conservation of mass of the fluid stream; the situation becomes slightly different if advection happens in a non-conservative medium.
Only a path was considered for the scalar above. For a vector, the gradient becomes a tensor derivative; for tensor fields we may want to take into account not only translation of the coordinate system due to the fluid movement but also its rotation and stretching. This is achieved by the upper convected time derivative. | 1 | Applied and Interdisciplinary Chemistry |
Not all elements which are found in the human body in trace quantities play a role in life. Some of these elements are thought to be simple common contaminants without function (examples: caesium, titanium), while many others are thought to be active toxins, depending on amount (cadmium, mercury, lead, radioactives). In humans, arsenic is toxic, and its levels in foods and dietary supplements are closely monitored to reduce or eliminate its intake.
Some elements (silicon, boron, nickel, vanadium) are probably needed by mammals also, but in far smaller doses. Bromine is used by some (though not all) bacteria, fungi, diatoms, and seaweeds, and opportunistically in eosinophils in humans. One study has indicated bromine to be necessary to collagen IV synthesis in humans. Fluorine is used by a number of plants to manufacture toxins but only functions in humans as a local topical hardening agent in tooth enamel. | 1 | Applied and Interdisciplinary Chemistry |
Suppose that a plane wave (of any type) is incident on planes of lattice points, with separation , at an angle as shown in the Figure. Points A and C are on one plane, and B is on the plane below. Points ABCC' form a quadrilateral.
There will be a path difference between the ray that gets reflected along AC' and the ray that gets transmitted along AB, then reflected along BC. This path difference is
The two separate waves will arrive at a point (infinitely far from these lattice planes) with the same phase, and hence undergo constructive interference, if and only if this path difference is equal to any integer value of the wavelength, i.e.
where and are an integer and the wavelength of the incident wave respectively.
Therefore, from the geometry
from which it follows that
Putting everything together,
which simplifies to which is Bragg's law shown above.
If only two planes of atoms were diffracting, as shown in the Figure then the transition from constructive to destructive interference would be gradual as a function of angle, with gentle maxima at the Bragg angles. However, since many atomic planes are participating in most real materials, sharp peaks are typical.
A rigorous derivation from the more general Laue equations is available (see page: Laue equations). | 0 | Theoretical and Fundamental Chemistry |
Thermal mass is effective in improving building comfort in any place that experiences these types of daily temperature fluctuations—both in winter as well as in summer.
When used well and combined with passive solar design, thermal mass can play an important role in major reductions to energy use in active heating and cooling systems.
The use of materials with thermal mass is most advantageous where there is a big difference in outdoor temperatures from day to night (or, where nighttime temperatures are at least 10 degrees cooler than the thermostat set point). The terms heavy-weight and light-weight are often used to describe buildings with different thermal mass strategies, and affects the choice of numerical factors used in subsequent calculations to describe their thermal response to heating and cooling.
In building services engineering, the use of dynamic simulation computational modelling software has allowed for the accurate calculation of the environmental performance within buildings with different constructions and for different annual climate data sets. This allows the architect or engineer to explore in detail the relationship between heavy-weight and light-weight constructions, as well as insulation levels, in reducing energy consumption for mechanical heating or cooling systems, or even removing the need for such systems altogether. | 0 | Theoretical and Fundamental Chemistry |
Pluvicto also uses Lu-177 as the radioisotope (which is a beta emitter that decays to Hf-177) but its ligand is a prostate-specific membrane antigen (PSMA) targeted ligand as this radioligand therapy addresses metastatic prostate cancer. It was FDA approved in 2022. The difference between Lutathera and Pluvicto is shown in the chemical linkages in the images above. The production, transportation, and storage is the same as Lutathera. The therapy is administered intravenously through gravity, syringe, or a Peristaltic Infusion Pump. The major warnings include renal toxicity, infertility in males, and embryo/fetal harm. General side effects of this radioligand therapy include fatigue, nausea, dry mouth, anemia, decreased appetite, and constipation. Regular blood tests and imaging post-therapy are needed to see if the radioligand therapy is working and its side effects.
The benefits of Pluvicto include delaying tumor growth, extending life by about 20 months, and destroying tumor cells by damaging the DNA inside those cells.
Xofigo, a radioligand therapy that was FDA approved in 2013, uses Radium-223 dichloride as the radioisotope, but its ligand varies from Pluvicto. Pluvicto only attacks cancer cells expressing PSMA, but Xofigo attacks all bone metastases. Qualified patients are 30% less likely to die when treated by Xofigo than if treated by a placebo. Ra-223-chloride is an alpha-emitting bone targeting agent. | 1 | Applied and Interdisciplinary Chemistry |
Fluidics, or fluidic logic, is the use of a fluid to perform analog or digital operations similar to those performed with electronics.
The physical basis of fluidics is pneumatics and hydraulics, based on the theoretical foundation of fluid dynamics. The term fluidics is normally used when devices have no moving parts, so ordinary hydraulic components such as hydraulic cylinders and spool valves are not considered or referred to as fluidic devices.
A jet of fluid can be deflected by a weaker jet striking it at the side. This provides nonlinear amplification, similar to the transistor used in electronic digital logic. It is used mostly in environments where electronic digital logic would be unreliable, as in systems exposed to high levels of electromagnetic interference or ionizing radiation.
Nanotechnology considers fluidics as one of its instruments. In this domain, effects such as fluid–solid and fluid–fluid interface forces are often highly significant. Fluidics have also been used for military applications. | 1 | Applied and Interdisciplinary Chemistry |
The goal of combining fluorescence and nucleic acids has been to provide a non-isotopic tag that is detectable to study DNA or RNA. This type of labeling allows scientists to study DNA or RNA in their structure, function, or formation with other nucleic acids. The first base modification for fluorescent labeling occurred in 1971 with a 4-thiouridine and 4-thiouracil. This research along with others, which included various types of direct and non-direct labeling via: analogs, addition via enzymes, or other methods made labeling of nucleotides much safer for scientist to study DNA.
As instrumentation and technologies become more advanced in the field of DNA microarray, better reagents and techniques will be needed to further scientific studies. Fluorescent labeling with Cy3 was shown to be more insufficient and skew results; the method of aminoallyl nucleotide incorporation was opted instead. Using aminoallyl nucleotides as indirect fluorescent labeling seemed to nullify the sensitivity issues seen in cyanine-labeling. | 1 | Applied and Interdisciplinary Chemistry |
Leaving alone remote antiquity and starting with Imperial Rome, the working of bronze, inspired probably by conquered Greece, is clearly seen. There are ancient bronze doors in the Temple of Romulus in the Roman Forum; others from the baths of Caracalla are in the Lateran Basilica, which also contains four fine gilt bronze fluted columns of the Corinthian order. The Naples Museum contains a large collection of domestic utensils of bronze, recovered from the buried towns of Pompeii and Herculaneum, which show a high degree of perfection in the working of the metal, as well as a wide application of its use. A number of moorings in the form of finely modelled animal heads, made in the 1st century AD, and recovered from Lake Nemi in the Alban hills some years ago, show a further acquaintance with the skilful working of this metal. The throne of Dagobert in the Bibliothèque Nationale, Paris, appears to be a Roman bronze curule chair, with back and part of the arms added by the Abbot Suger in the 12th century.
Byzantium, from the time when Constantine made it the seat of empire, in the early part of the 4th century, was for 1,000 years renowned for its works in metal. Its position as a trade centre between East and West attracted all the finest work provided by the artistic skills of craftsmen from Syria, Egypt, Persia, Asia Minor and the northern shores of the Black Sea, and for 400 years, until the beginning of the Iconoclastic period in the first half of the 8th century, its output was enormous. Several Italian churches still retain bronze doors cast in Constantinople in the later days of the Eastern Empire, such as those presented by the members of the Pantaleone family, in the latter half of the 11th century, to the churches at Amalfi, Monte Cassino, Atrani and Monte Gargano. Similar doors are at Salerno; and St Mark's, Venice, also has doors of Greek origin. | 1 | Applied and Interdisciplinary Chemistry |
Levonorgestrel is a progestogen; that is, an agonist of the progesterone receptor (PR), the main biological target of the progestogen sex hormone progesterone. It has effects similar to those of the hormone progesterone. As a contraceptive, it works primarily by preventing ovulation and closing off the cervix to prevent the passage of sperm. The endometrial transformation dose of levonorgestrel is 150 to 250μg/day or 2.5 to 6mg per cycle. | 0 | Theoretical and Fundamental Chemistry |
*UVR8: UV-B light reception
*Cryptochrome: blue and UV-A light reception
*Phototropin: blue and UV-A light perception (to mediate phototropism and chloroplast movement)
*Zeitlupe: blue light entrainment of the circadian clock
*Phytochrome: red and far-red light reception
All the photoreceptors listed above allow plants to sense light with wavelengths range from 280 nm (UV-B) to 750 nm (far-red light). Plants use light of different wavelengths as environmental cues to both alter their position and to trigger important developmental transitions. The most prominent wavelength responsible for plant mechanisms is blue light, which can trigger cell elongation, plant orientation, and flowering. One of the most important processes regulated by photoreceptors is known as photomorphogenesis. When a seed germinates underground in the absence of light, its stem rapidly elongates upwards. When it breaks through the surface of the soil, photoreceptors perceive light. The activated photoreceptors cause a change in developmental program; the plant starts producing chlorophyll and switches to photosynthetic growth. | 1 | Applied and Interdisciplinary Chemistry |
The Symons Pan / Tank is a standard instrument of the UK Met Office. It is a steel container 1.83 m (6 ft) on a side and 0.61 m (2 ft) deep, sunk into the ground with an above-ground rim of 0.076 - 0.1 m (3 - 4 in.) and is painted black internally. Its evaporation rate is lower than the Class A pan and conversion factors must be used. | 1 | Applied and Interdisciplinary Chemistry |
There are an enormous number of different ways in which a chain can be curled around in a relatively compact shape, like an unraveling ball of twine with much open space, and comparatively few ways it can be more or less stretched out. So, if each conformation has an equal probability or statistical weight, chains are much more likely to be ball-like than they are to be extended — a purely entropic effect. In an ensemble of chains, most of them will, therefore, be loosely balled up. This is the kind of shape any one of them will have most of the time.
Consider a linear polymer to be a freely-jointed chain with N subunits, each of length , that occupy zero volume, so that no part of the chain excludes another from any location. One can regard the segments of each such chain in an ensemble as performing a random walk (or "random flight") in three dimensions, limited only by the constraint that each segment must be joined to its neighbors. This is the ideal chain mathematical model. It is clear that the maximum, fully extended length L of the chain is . If we assume that each possible chain conformation has an equal statistical weight, it can be shown that the probability P(r) of a polymer chain in the population to have distance r between the ends will obey a characteristic distribution described by the formula
where is the mean of .
The average (root mean square) end-to-end distance for the chain, , turns out to be times the square root of N — in other words, the average distance scales with N . | 0 | Theoretical and Fundamental Chemistry |
Streak seeding is a method first described during ICCBM-3 by Enrico Stura to induce crystallization in a straight line into a sitting or hanging drop for protein crystallization by introducing microseeds. The purpose is to control nucleation and understand the parameters that make crystals grow. It is also used to test any particular set of conditions to check if crystals could grow under such conditions.
The technique is relatively simple. A cat whisker is used to dislodge seeds from a crystal. The whisker is passed through the drop starting from one side of the drop and ending on the opposite side of the drop in one smooth motion. To allow for vapour diffusion equilibration, the well in which the drop has been placed is resealed. The same procedure is repeated for all the drops whose conditions need testing. | 0 | Theoretical and Fundamental Chemistry |
The sodium fusion extract is made alkaline by adding NaOH. To this mixture, freshly prepared FeSO solution is added and boiled for sometimes and then cooled. A few drops of FeCl are added and Prussian blue (bluish green) color forms due to formation of ferric ferrocyanide along with NaCl. This shows the presence of nitrogen in the organic compound.<blockquote><chem>6CN- +Fe^2+ -> [Fe(CN)6]^4-
<blockquote><chem>{3[Fe(CN)6]}^{4-} +4Fe^3+ ->[\ce{xH2O}]Fe4[Fe(CN)6]3\cdot xH2O | 0 | Theoretical and Fundamental Chemistry |
Microcystins covalently bond to and inhibit protein phosphatases PP1 and PP2A and can thus cause pansteatitis. The ADDA residue is key to this functionality: greatly simplified synthetic analogues consisting of ADDA and one additional amino acid can show the same inhibiting function. | 1 | Applied and Interdisciplinary Chemistry |
The term plasmid was introduced in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time to comprise genetic elements that reproduce autonomously.
Later in 1968, it was decided that the term plasmid should be adopted as the term for extrachromosomal genetic element, and to distinguish it from viruses, the definition was narrowed to genetic elements that exist exclusively or predominantly outside of the chromosome and can replicate autonomously. | 1 | Applied and Interdisciplinary Chemistry |
The introduction of atom into a crystal of atom creates a pinning point for multiple reasons. An alloying atom is by nature a point defect, thus it must create a stress field when placed into a foreign crystallographic position, which could block the passage of a dislocation. However, it is possible that the alloying material is approximately the same size as the atom that is replaced, and thus its presence would not stress the lattice (as occurs in cobalt alloyed nickel). The different atom would, though, have a different elastic modulus, which would create a different terrain for the moving dislocation. A higher modulus would look like an energy barrier, and a lower like an energy trough – both of which would stop its movement. | 1 | Applied and Interdisciplinary Chemistry |
First-generation TSH assays were done by radioimmunoassay and were introduced in 1965. There were variations and improvements upon TSH radioimmunoassay, but their use declined as a new immunometric assay technique became available in the middle of the 1980s. The new techniques were more accurate, leading to the second, third, and even fourth generations of TSH assay, with each generation possessing ten times greater functional sensitivity than the last. Third generation immunometric assay methods are typically automated. Fourth generation TSH immunometric assay has been developed for use in research. | 1 | Applied and Interdisciplinary Chemistry |
He is credited with writing the following episodes:
*"Steamland Confidential" (2021)
*"Love Is Hell" (2022) | 0 | Theoretical and Fundamental Chemistry |
Many, if not all, retinalophototrophs are photoheterotrophs: although sufficient ATP is produced by light, they cannot subsist on light and inorganic substances alone because they cannot produce needed organic materials from only . This category includes retinalophototrophs that perform anaplerotic fixation, such as a flavobacterium that can use pyruvate and CO to make malate. This ability does, however, help "stretch" limited supplies of carbon. | 0 | Theoretical and Fundamental Chemistry |
Ted Ellis and his wife are both natives of New Orleans, and much of his art along with his passion for art are inspired by the vibrant city. As a young man, he would search the colorful French Quarter for subjects to paint. In the aftermath of Hurricane Katrina and the devastation of parts of the city, the city's role in his art drastically changed so as to reflect the story of hope and rebirth that he saw in the disaster.
On the night before the storm hit Louisiana, the Ellis home in Texas was a refuge for 10 New Orleans families, 50 people in all. After the storm, Ellis helped fly home friends stranded outside New Orleans, and he organized colleagues in the art community behind the relief effort.
Ellis was allowed to enter the city two weeks after the flood waters subsided in order to survey the damage to his mothers home in the Lower Ninth Ward and salvage her possessions. While travelling among the destroyed houses and deserted city, Ellis witnessed a lone man repairing his homes roof. The contrast resonated with Ellis, and he memorialized the hope he saw in the mans actions through his piece Surviving Katrina. The scene is of rising floodwater that traps a family on their houses roof while the father holds up the Flag of the United States, a flag that to Ellis symbolizes the need for the nation to come together to aid those affected by the storm.
In Life Begins Anew, a father holds a baby above floodwaters while another man reaches out to take the child. Ellis describes the scene as symbolizing the promise of a new beginning for those who survived Katrina and its aftermath.
As its title indicates, the Katrina: The Hope, Healing and Rebirth of New Orleans collection was for Ellis about showing the power of art to assist the healing process: "The largest piece I did is about how life begins anew and how a person can find hope even after such devastation. I want this work to be uplifting, to be a fresh breath of life for the community." | 0 | Theoretical and Fundamental Chemistry |
A crystal is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. Crystal growth is a major stage of a crystallization process, and consists of the addition of new atoms, ions, or polymer strings into the characteristic arrangement of the crystalline lattice. The growth typically follows an initial stage of either homogeneous or heterogeneous (surface catalyzed) nucleation, unless a "seed" crystal, purposely added to start the growth, was already present.
The action of crystal growth yields a crystalline solid whose atoms or molecules are close packed, with fixed positions in space relative to each other.
The crystalline state of matter is characterized by a distinct structural rigidity and very high resistance to deformation (i.e. changes of shape and/or volume). Most crystalline solids have high values both of Young's modulus and of the shear modulus of elasticity. This contrasts with most liquids or fluids, which have a low shear modulus, and typically exhibit the capacity for macroscopic viscous flow. | 0 | Theoretical and Fundamental Chemistry |
Being highly polar, imides exhibit good solubility in polar media. The N–H center for imides derived from ammonia is acidic and can participate in hydrogen bonding. Unlike the structurally related acid anhydrides, they resist hydrolysis and some can even be recrystallized from boiling water. | 0 | Theoretical and Fundamental Chemistry |
mTOR is the catalytic subunit of two structurally distinct complexes: mTORC1 and mTORC2. The two complexes localize to different subcellular compartments, thus affecting their activation and function. Upon activation by Rheb, mTORC1 localizes to the Ragulator-Rag complex on the lysosome surface where it then becomes active in the presence of sufficient amino acids. | 1 | Applied and Interdisciplinary Chemistry |
Pipes can come in many different cross-sectional shapes (rectangular, square, bread-loaf-shaped, oval, inverted pear-shaped, egg shaped, and most commonly, circular). Drainage systems may have many different features including waterfalls, stairways, balconies and pits for catching rubbish, sometimes called Gross Pollutant Traps (GPTs). Pipes made of different materials can also be used, such as brick, concrete, high-density polyethylene or galvanized steel. Fibre reinforced plastic is being used more commonly for drain pipes and fittings. | 1 | Applied and Interdisciplinary Chemistry |
From the formation of the Roman Empire, Rome was an almost completely closed economy, not reliant on imports although exotic goods from India and China (such as gems, silk and spices) were highly prized (Shepard 1993). Through the recovery of Roman coins and ingots throughout the ancient world (Hughes 1980), metallurgy has supplied the archaeologist with material culture through which to see the expanse of the Roman world. | 1 | Applied and Interdisciplinary Chemistry |
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