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Sprinklers have been in use in the United States since 1874, and were installed into factory applications where fires at the turn of the century had often catastrophic in terms of both human and property losses. In the US, sprinklers are today required in all new high rise and underground buildings generally above or below fire department access, where the ability of firefighters to provide adequate hose streams to fires is limited.
Sprinklers may be required to be installed by building codes, or may be recommended by insurance companies to reduce potential property losses or business interruption. US building codes for places of assembly (generally over 100 persons) and places with overnight sleeping accommodation such as hotels, nursing homes, dormitories, and hospitals, usually require sprinklers either under local building codes, as a condition of receiving State and Federal funding, or as a requirement to obtain certification (essential for institutions who wish to train medical staff). | 1 | Applied and Interdisciplinary Chemistry |
Special caution should be taken with people who have fish and shellfish allergies. In addition, as with other omega-3 fatty acids, taking ethyl eicosapentaenoic acid (E-EPA) puts people who are on anticoagulants at risk for prolonged bleeding time.
The most commonly reported side effect in clinical trials has been joint pain; some people also reported pain in their mouth or throat. E-EPA has not been tested in pregnant women; it is excreted in breast milk and the effects on infants are not known. | 1 | Applied and Interdisciplinary Chemistry |
Sedimentation potential is measured by attaching electrodes to a glass column filled with the dispersion of interest. A voltmeter is attached to measure the potential generated from the suspension. To account for different geometries of the electrode, the column is typically rotated 180 degrees while measuring the potential. This difference in potential through rotation by 180 degrees is twice the sedimentation potential. The zeta potential can be determined through measurement by sedimentation potential, as the concentration, conductivity of the suspension, density of the particle, and potential difference are known. By rotating the column 180 degrees, drift and geometry differences of the column can be ignored.
When dealing with the case of concentrated systems, the zeta potential can be determined through measurement of the sedimentation potential , from the potential difference relative to the distance between the electrodes. The other parameters represent the following: the viscosity of the medium; the bulk conductivity; the relative permittivity of the medium; the permittivity of free space; the density of the particle; the density of the medium; is the acceleration due to gravity; and σ is the electrical conductivity of the bulk electrolyte solution.
An improved design cell was developed to determine sedimentation potential, specific conductivity, volume fraction of the solids as well as pH. Two pairs of electrodes are used in this set up, one to measure potential difference and the other for resistance. A flip switch is utilized to avoid polarization of the resistance electrodes and buildup of charge by alternating the current. The pH of the system could be monitored and the electrolyte was drawn into the tube using a vacuum pump. | 0 | Theoretical and Fundamental Chemistry |
The molecular orbital explanation of the stability of homoaromaticity has been widely discussed with numerous diverse theories, mostly focused on the homotropenylium cation as a reference. R.C. Haddon initially proposed a Mobius model where the outer electrons of the sp hybridized methylene bridge carbon(2) back-donate to the adjacent carbons to stabilize the C1-C3 distance. | 0 | Theoretical and Fundamental Chemistry |
The use of displacement chromatography is rather limited, and is mostly used for preparative chromatography. The basic principle is based on a molecule with a high affinity for the chromatography matrix (the displacer) which is used to compete effectively for binding sites, and thus displace all molecules with lesser affinities.
There are distinct differences between displacement and elution chromatography. In elution mode, substances typically emerge from a column in narrow, Gaussian peaks. Wide separation of peaks, preferably to baseline, is desired in order to achieve maximum purification. The speed at which any component of a mixture travels down the column in elution mode depends on many factors. But for two substances to travel at different speeds, and thereby be resolved, there must be substantial differences in some interaction between the biomolecules and the chromatography matrix. Operating parameters are adjusted to maximize the effect of this difference. In many cases, baseline separation of the peaks can be achieved only with gradient elution and low column loadings. Thus, two drawbacks to elution mode chromatography, especially at the preparative scale, are operational complexity, due to gradient solvent pumping, and low throughput, due to low column loadings. Displacement chromatography has advantages over elution chromatography in that components are resolved into consecutive zones of pure substances rather than "peaks". Because the process takes advantage of the nonlinearity of the isotherms, a larger column feed can be separated on a given column with the purified components recovered at significantly higher concentration. | 0 | Theoretical and Fundamental Chemistry |
The equivalence point, or stoichiometric point, of a chemical reaction is the point at which chemically equivalent quantities of reactants have been mixed. For an acid-base reaction the equivalence point is where the moles of acid and the moles of base would neutralize each other according to the chemical reaction. This does not necessarily imply a 1:1 molar ratio of acid:base, merely that the ratio is the same as in the chemical reaction. It can be found by means of an indicator, for example phenolphthalein or methyl orange.
The endpoint (related to, but not the same as the equivalence point) refers to the point at which the indicator changes color in a colorimetric titration. | 0 | Theoretical and Fundamental Chemistry |
Hemoglycin (previously termed hemolithin) is a space polymer that is the first polymer of amino acids found in meteorites. | 0 | Theoretical and Fundamental Chemistry |
Researchers at Sandia Labs, Ames National Laboratory and Iowa State University reported a 3D-printed superalloy composed of 42% aluminum, 25% titanium, 13% niobium, 8% zirconium, 8% molybdenum and 4% tantalum. Most alloys are made chiefly of one primary element, combined with low amounts of other elements. In contrast MPES have substantial amounts of three or more elements.
Such alloys promise improvements on high-temperature applications, strength-to-weight, fracture toughness, corrosion and radiation resistance, wear resistance, and others. They reported hardness and density of 1.8–2.6 GPa-cm/g, which surpasses all known alloys, including intermetallic compounds, titanium aluminides, refractory MPEAs, and conventional Ni-based superalloys. This represents a 300% improvement over Inconel 718 based on measured peak hardness of 4.5 GPa and density of 8.2 g/cm, (0.55 GPa-cm/g).
The material is stable at 800 °C, hotter than the 570+ °C found in typical coal-based power plants.
The researchers acknowledged that the 3D printing process produces microscopic cracks when forming large parts, and that the feedstock includes metals that limit applicability in cost-sensitive applications. | 1 | Applied and Interdisciplinary Chemistry |
In pharmacology, an indirect agonist or indirect-acting agonist is a substance that enhances the release or action of an endogenous neurotransmitter but has no specific agonist activity at the neurotransmitter receptor itself. Indirect agonists work through varying mechanisms to achieve their effects, including transporter blockade, induction of transmitter release, and inhibition of transmitter breakdown. | 1 | Applied and Interdisciplinary Chemistry |
Tc is normally supplied to hospitals through a radionuclide generator containing the parent radionuclide molybdenum-99. Mo is typically obtained as a fission product of U in nuclear reactors, however global supply shortages have led to the exploration of other methods of production. About a third of the worlds supply, and most of Europes supply, of medical isotopes is produced at the Petten nuclear reactor in the Netherlands. Another third of the worlds supply, and most of North Americas supply, was produced at the Chalk River Laboratories in Chalk River, Ontario, Canada until its permanent shutdown in 2018.
The most commonly used radioisotope in PET, F, is not produced in a nuclear reactor, but rather in a circular accelerator called a cyclotron. The cyclotron is used to accelerate protons to bombard the stable heavy isotope of oxygen O. The O constitutes about 0.20% of ordinary oxygen (mostly oxygen-16), from which it is extracted. The F is then typically used to make FDG.
A typical nuclear medicine study involves administration of a radionuclide into the body by intravenous injection in liquid or aggregate form, ingestion while combined with food, inhalation as a gas or aerosol, or rarely, injection of a radionuclide that has undergone micro-encapsulation. Some studies require the labeling of a patient's own blood cells with a radionuclide (leukocyte scintigraphy and red blood cell scintigraphy). Most diagnostic radionuclides emit gamma rays either directly from their decay or indirectly through electron–positron annihilation, while the cell-damaging properties of beta particles are used in therapeutic applications. Refined radionuclides for use in nuclear medicine are derived from fission or fusion processes in nuclear reactors, which produce radionuclides with longer half-lives, or cyclotrons, which produce radionuclides with shorter half-lives, or take advantage of natural decay processes in dedicated generators, i.e. molybdenum/technetium or strontium/rubidium.
The most commonly used intravenous radionuclides are technetium-99m, iodine-123, iodine-131, thallium-201, gallium-67, fluorine-18 fluorodeoxyglucose, and indium-111 labeled leukocytes. The most commonly used gaseous/aerosol radionuclides are xenon-133, krypton-81m, (aerosolised) technetium-99m. | 1 | Applied and Interdisciplinary Chemistry |
When a fluid flow at the speed of sound over a thin sharp flat plate over the leading edge at low incident angle at low Reynolds Number. Then a laminar boundary layer will be developed at the leading edge of the plate. And as there are viscous boundary layer, the plate will have a fictitious boundary layer so that a curved induced shock wave will be generated at the leading edge of the plate.
The shock layer is the region between the plate surface and the boundary layer. This shock layer be further subdivided into layer of viscid and inviscid flow, according to the values of Mach number, Reynolds Number and Surface Temperature. However, if the entire layer is viscous, it is called as merged shock layer. | 1 | Applied and Interdisciplinary Chemistry |
Oxaziridines with unsubstituted or acylated nitrogens are capable of nitrogen atom transfer, although this reactivity has received considerably less attention. | 0 | Theoretical and Fundamental Chemistry |
Nucleotide analogues require only two phosphorylation steps whereas nucleoside analogues require three steps. Reduction in the phosphorylation requirement may allow more rapid and complete conversion of drugs to their active metabolites. Such considerations have led to the development of phosphonate nucleotide analogues such as tenofovir. Tenofovir disoproxil fumarate (Tenofovir DF) is the prodrug of tenofovir. Tenofovir is an acyclic adenosine derivative. The acyclic nature of the compound and its phosphonate moiety are unique structural features among the approved NRTIs. Tenofovir DF is hydrolyzed enzymatically to tenofovir which exhibits anti-HIV activity. It was developed by the synthesis and broad spectrum antiviral activity of 2,3-dihydroxypropyladenine. Tenofovir DF was the first nucleotide reverse-transcriptase inhibitor approved by the FDA for the treatment of HIV-1 infection in October 2001.
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Ion semiconductor sequencing is a method of DNA sequencing based on the detection of hydrogen ions that are released during the polymerization of DNA. This is a method of "sequencing by synthesis", during which a complementary strand is built based on the sequence of a template strand.
A microwell containing a template DNA strand to be sequenced is flooded with a single species of deoxyribonucleotide triphosphate (dNTP). If the introduced dNTP is complementary to the leading template nucleotide, it is incorporated into the growing complementary strand. This causes the release of a hydrogen ion that triggers an ISFET ion sensor, which indicates that a reaction has occurred. If homopolymer repeats are present in the template sequence, multiple dNTP molecules will be incorporated in a single cycle. This leads to a corresponding number of released hydrogens and a proportionally higher electronic signal.
This technology differs from other sequencing-by-synthesis technologies in that no modified nucleotides or optics are used. Ion semiconductor sequencing may also be referred to as Ion Torrent sequencing, pH-mediated sequencing, silicon sequencing, or semiconductor sequencing. | 1 | Applied and Interdisciplinary Chemistry |
Insulin is a peptide hormone that is critical for managing the body's metabolism. Insulin is released by the pancreas when blood sugar levels rise, and it has many effects that broadly promote the absorption and storage of sugars, including lipogenesis.
Insulin stimulates lipogenesis primarily by activating two enzymatic pathways. Pyruvate dehydrogenase (PDH), converts pyruvate into acetyl-CoA. Acetyl-CoA carboxylase (ACC), converts acetyl-CoA produced by PDH into malonyl-CoA. Malonyl-CoA provides the two-carbon building blocks that are used to create larger fatty acids.
Insulin stimulation of lipogenesis also occurs through the promotion of glucose uptake by adipose tissue. The increase in the uptake of glucose can occur through the use of glucose transporters directed to the plasma membrane or through the activation of lipogenic and glycolytic enzymes via covalent modification. The hormone has also been found to have long term effects on lipogenic gene expression. It is hypothesized that this effect occurs through the transcription factor SREBP-1, where the association of insulin and SREBP-1 lead to the gene expression of glucokinase. The interaction of glucose and lipogenic gene expression is assumed to be managed by the increasing concentration of an unknown glucose metabolite through the activity of glucokinase.
Another hormone that may affect lipogenesis through the SREBP-1 pathway is leptin. It is involved in the process by limiting fat storage through inhibition of glucose intake and interfering with other adipose metabolic pathways. The inhibition of lipogenesis occurs through the down regulation of fatty acid and triglyceride gene expression. Through the promotion of fatty acid oxidation and lipogenesis inhibition, leptin was found to control the release of stored glucose from adipose tissues.
Other hormones that prevent the stimulation of lipogenesis in adipose cells are growth hormones (GH). Growth hormones result in loss of fat but stimulates muscle gain. One proposed mechanism for how the hormone works is that growth hormones affects insulin signaling thereby decreasing insulin sensitivity and in turn down regulating fatty acid synthase expression. Another proposed mechanism suggests that growth hormones may phosphorylate with STAT5A and STAT5B, transcription factors that are a part of the Signal Transducer And Activator Of Transcription (STAT) family.
There is also evidence suggesting that acylation stimulating protein (ASP) promotes the aggregation of triglycerides in adipose cells. This aggregation of triglycerides occurs through the increase in the synthesis of triglyceride production. | 1 | Applied and Interdisciplinary Chemistry |
In physical and chemical kinetics, T-symmetry of the mechanical microscopic equations implies two important laws: the principle of detailed balance and the Onsager reciprocal relations. T-symmetry of the microscopic description together with its kinetic consequences are called microscopic reversibility. | 0 | Theoretical and Fundamental Chemistry |
If soil sulfur is derived consistently from one source, the water-soluble and insoluble organic S fractions acquire similar isotopic compositions. In the case that there are two or more sources and/or if the isotopic composition of atmospheric or groundwater sulfate fluctuates, there may not be sufficient time for isotopic homogenization among the various forms of sulfur. The primary form of sulfur in soil is sulfate, which is transported upwards through the root system with minimal δS fractionation by 1–2‰. In contrast to higher canopy plants reflecting atmospheric δS, protected understory plants tend to reflect soil sulfur. | 0 | Theoretical and Fundamental Chemistry |
Stable isotopic analysis has also been used for tracing the geographical origin of food, timber, and in tracing the sources and fates of nitrates in the environment. | 0 | Theoretical and Fundamental Chemistry |
Bisphosphonates mimic the endogenous inorganic pyrophosphate where the oxygen backbone is replaced with carbon (P-C-P for P-O-P). The two additional groups or side chains on the carbon backbone are usually referred to as R and R. R is usually a hydroxyl group which enhances the affinity for the calcium by forming a tridentate ligand along with the phosphate groups. The compound can be made more potent by optimizing the structure of the R group to best inhibit bone resorption. | 1 | Applied and Interdisciplinary Chemistry |
Dodecahedrane is a chemical compound, a hydrocarbon with formula , whose carbon atoms are arranged as the vertices (corners) of a regular dodecahedron. Each carbon is bound to three neighbouring carbon atoms and to a hydrogen atom. This compound is one of the three possible Platonic hydrocarbons, the other two being cubane and tetrahedrane.
Dodecahedrane does not occur in nature and has no significant uses. It was synthesized by Leo Paquette in 1982, primarily for the "aesthetically pleasing symmetry of the dodecahedral framework".
For many years, dodecahedrane was the simplest real carbon-based molecule with full icosahedral symmetry. Buckminsterfullerene (), discovered in 1985, also has the same symmetry, but has three times as many carbons and 50% more atoms overall. The synthesis of the C fullerene in 2000, from brominated dodecahedrane, may have demoted to second place. | 0 | Theoretical and Fundamental Chemistry |
Gustav Kirchhoff was born on 12 March 1824 in Königsberg, Prussia, the son of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke. His family were Lutherans in the Evangelical Church of Prussia. He graduated from the Albertus University of Königsberg in 1847 where he attended the mathematico-physical seminar directed by Carl Gustav Jacob Jacobi, Franz Ernst Neumann and Friedrich Julius Richelot. In the same year, he moved to Berlin, where he stayed until he received a professorship at Breslau. Later, in 1857, he married Clara Richelot, the daughter of his mathematics professor Richelot. The couple had five children. Clara died in 1869. He married Luise Brömmel in 1872.
Kirchhoff formulated his circuit laws, which are now ubiquitous in electrical engineering, in 1845, while he was still a student. He completed this study as a seminar exercise; it later became his doctoral dissertation. He was called to the University of Heidelberg in 1854, where he collaborated in spectroscopic work with Robert Bunsen. In 1857, he calculated that an electric signal in a resistanceless wire travels along the wire at the speed of light. He proposed his law of thermal radiation in 1859, and gave a proof in 1861. Together Kirchhoff and Bunsen invented the spectroscope, which Kirchhoff used to pioneer the identification of the elements in the Sun, showing in 1859 that the Sun contains sodium. He and Bunsen discovered caesium and rubidium in 1861.
At Heidelberg he ran a mathematico-physical seminar, modelled on Franz Ernst Neumann's, with the mathematician Leo Koenigsberger. Among those who attended this seminar were Arthur Schuster and Sofia Kovalevskaya.
He contributed greatly to the field of spectroscopy by formalizing three laws that describe the spectral composition of light emitted by incandescent objects, building substantially on the discoveries of David Alter and Anders Jonas Ångström. In 1862, he was awarded the Rumford Medal for his researches on the fixed lines of the solar spectrum, and on the inversion of the bright lines in the spectra of artificial light. In 1875 Kirchhoff accepted the first chair dedicated specifically to theoretical physics at Berlin.
He also contributed to optics, carefully solving the wave equation to provide a solid foundation for Huygens' principle (and correct it in the process).
In 1864, he was elected as a member of the American Philosophical Society.
In 1884, he became foreign member of the Royal Netherlands Academy of Arts and Sciences.
Kirchhoff died in 1887, and was buried in the St Matthäus Kirchhof Cemetery in Schöneberg, Berlin (just a few meters from the graves of the Brothers Grimm). Leopold Kronecker is buried in the same cemetery. | 1 | Applied and Interdisciplinary Chemistry |
* Railway - gearboxes, wheels, transmissions
* Machine tools - lathe gearboxes, mills
* Steel works - roll bearings, roll neck rings
* Power generation - various generator components
Due to the need to insert a core and also that to be effective, the core has to be in relatively close proximity to the bore of the part to be heated, there are many application in which the above bearing heater type approach is not feasible. | 1 | Applied and Interdisciplinary Chemistry |
Regardless of the presence or absence of an oxidant, the first step of the reaction is photochemical excitation of a stilbene or similar structure, leading to formation of a dihydrophenanthrene or similar intermediate. For stilbene and other chemicals containing a double-bond linker between the two aromatic rings, the excited structure can undergo reversible cis-trans isomerization. Although only cis structures can undergo the cyclization step themselves, trans structures can isomerize in situ and then cyclize. In keeping with the Woodward–Hoffmann rules, molecular orbital symmetry analysis of the photochemical reaction of the six-electron system explains the trans relative configuration at the newly bound centers by a conrotatory process.
This cyclization is reversible, but several other subsequent reactions can occur instead, depending on structural details and whether certain other reagents are present. | 0 | Theoretical and Fundamental Chemistry |
Levosalbutamol's bronchodilator properties give it indications in treatment of COPD (chronic obstructive pulmonary disease, also known as chronic obstructive lung disease) and asthma. Like other bronchodilators, it acts by relaxing smooth muscle in the bronchial tubes, and thus shortening or reversing an acute "attack" of shortness of breath or difficulty breathing. Unlike some slower-acting bronchodilators, it is not indicated as a preventative of chronic bronchial constriction. | 0 | Theoretical and Fundamental Chemistry |
The eye is most sensitive to damage by UV in the lower UV‑C band at 265–275 nm. Radiation of this wavelength is almost absent from sunlight at the surface of the Earth but is emitted by artificial sources such as the electrical arcs employed in arc welding. Unprotected exposure to these sources can cause "welder's flash" or "arc eye" (photokeratitis) and can lead to cataracts, pterygium and pinguecula formation. To a lesser extent, UV‑B in sunlight from 310 to 280 nm also causes photokeratitis ("snow blindness"), and the cornea, the lens, and the retina can be damaged.
Protective eyewear is beneficial to those exposed to ultraviolet radiation. Since light can reach the eyes from the sides, full-coverage eye protection is usually warranted if there is an increased risk of exposure, as in high-altitude mountaineering. Mountaineers are exposed to higher-than-ordinary levels of UV radiation, both because there is less atmospheric filtering and because of reflection from snow and ice.
Ordinary, untreated eyeglasses give some protection. Most plastic lenses give more protection than glass lenses, because, as noted above, glass is transparent to UV‑A and the common acrylic plastic used for lenses is less so. Some plastic lens materials, such as polycarbonate, inherently block most UV. | 0 | Theoretical and Fundamental Chemistry |
The BCS formalism is applicable without modifications to the description of quark matter with color group SU(2), where Cooper pairs are colorless. The Nambu–Jona-Lasinio model
predicts the existence of the superconducting phase of SU(2) color quark matter at high densities
This physical picture is confirmed in the Polyakov–Nambu–Jona-Lasinio model,
and also in lattice QCD models
in which the properties of cold quark matter can be described based on the first principles of quantum chromodynamics.
The possibility of modeling on the lattices of two-color QCD at finite chemical potentials for even numbers of the quark flavors is associated with the positive-definiteness
of the integral measure and the absence of a sign problem. | 0 | Theoretical and Fundamental Chemistry |
The word malic is derived from Latin , meaning apple. The related Latin word , meaning apple tree, is used as the name of the genus Malus, which includes all apples and crabapples; and the origin of other taxonomic classifications such as Maloideae, Malinae, and Maleae. | 1 | Applied and Interdisciplinary Chemistry |
Endoreversible thermodynamics was discovered multiple times, with Reitlinger (1929), Novikov (1957) and Chambadal (1957), although it is most often attributed to Curzon & Ahlborn (1975).
Reitlinger derived it by considering a heat exchanger receiving heat from a finite hot stream fed by a combustion process.
A brief review of the history of rediscoveries is in. | 0 | Theoretical and Fundamental Chemistry |
In cooperativity, the initial ligand binding affects the host's affinity for subsequent ligands. In positive cooperativity, the first binding event enhances the affinity of the host for another ligand. Examples of positive and negative cooperativity are hemoglobin and aspartate receptor, respectively.
The thermodynamic properties of cooperativity have been studied in order to define mathematical parameters that distinguish positive or negative cooperativity. The traditional Gibbs free energy equation states: . However, to quantify cooperativity in a host–guest system, the binding energy needs to be considered. The schematic on the right shows the binding of A, binding of B, positive cooperative binding of A–B, and lastly, negative cooperative binding of A–B. Therefore, an alternate form of the Gibbs free energy equation would be
where:
: = free energy of binding A
: = free energy of binding B
: = free energy of binding for A and B tethered
: = sum of the free energies of binding
It is considered that if more than the sum of and , it is positively cooperative. If is less, then it is negatively cooperative.
Host–guest chemistry is not limited to receptor-lingand interactions. It is also demonstrated in ion-pairing systems. Such interactions are studied in an aqueous media utilizing synthetic organometallic hosts and organic guest molecules. For example, a poly-cationic receptor containing copper (the host) is coordinated with molecules such as tetracarboxylates, tricarballate, aspartate, and acetate (the guests). This study illustrates that entropy rather than enthalpy determines the binding energy of the system leading to negative cooperativity. The large change in entropy originates from the displacement of solvent molecules surrounding the ligand and the receptor. When multiple acetates bind to the receptor, it releases more water molecules to the environment than a tetracarboxylate. This led to a decrease in free energy implying that the system is cooperating negatively. In a similar study, utilizing guanidinium and Cu(II) and polycarboxylate guests, it is demonstrated that positive cooperatively is largely determined by enthalpy. In addition to thermodynamic studies, host–guest chemistry also has biological applications. | 0 | Theoretical and Fundamental Chemistry |
He was involved in the creation of the Masters and Ph.D. Programs in Chemistry from his university and it was the very first doctoral program in Usach. He has supervised more 60 thesis: 36 undergraduate and professional students: 20 doctorates, 5 masters and 9 postdocs, some coming from Europe (Russian Federation, France, Germany, Spain and Italy). | 0 | Theoretical and Fundamental Chemistry |
HYSYS was first conceived and created by the Canadian company Hyprotech, founded by researchers from the University of Calgary. The HYSYS Version 1.1 Reference Volume was published in 1996.
In May 2002, AspenTech acquired Hyprotech, including HYSYS. Following a 2004 ruling by the United States Federal Trade Commission, AspenTech was forced to divest its Hyprotech assets, including HYSYS source code, ultimately selling these to Honeywell. Honeywell was also able to hire a number of HYSYS developers, ultimately mobilizing these resources to produce UniSim. The divestment agreement specified that Aspentech would retain rights to market and develop most Hyprotech products (including HYSYS) royalty-free. As of late 2016, AspenTech continues to produce HYSYS. | 1 | Applied and Interdisciplinary Chemistry |
In incompressible fluids (liquids) such as water, a bow wake is created when a watercraft moves through the medium; as the medium cannot be compressed, it must be displaced instead, resulting in a wave. As with all wave forms, it spreads outward from the source until its energy is overcome or lost, usually by friction or dispersion.
The non-dimensional parameter of interest is the Froude number. | 1 | Applied and Interdisciplinary Chemistry |
The US Department of Defense developed favipiravir in partnership with MediVector, Inc. as a broad-spectrum antiviral and sponsored it through FDA Phase II and Phase III clinical trials, where it demonstrated safety in humans and efficacy against the influenza virus. favipiravir remains unapproved in the UK and the USA. In 2014, Japan approved favipiravir for treating influenza strains unresponsive to current antivirals. Toyama Chemical initially hoped that favipiravir would become a new influenza medication that could replace oseltamivir (brand name Tamiflu). However, animal experiments show the potential for teratogenic effects, and the approval of production by The Ministry of Health, Labor and Welfare was greatly delayed and the production condition is limited only in an emergency in Japan.
Despite limited data on efficacy, as of March 2021 favipiravir is widely prescribed for outpatient treatment of mild to moderate COVID-19 in Egypt, Hungary and Serbia. Patients are required to sign a consent form before obtaining the drug. | 0 | Theoretical and Fundamental Chemistry |
The skeletal muscle accounts for more than 80 percent of the postprandial whole body glucose uptake and therefore plays an important role in glucose homeostasis. Skeletal muscle lipid levels – intramyocellular lipids (IMCL) – correlate negatively with insulin sensitivity in a sedentary population and hence were considered predictive for insulin resistance and causative in obesity-associated insulin resistance. However, endurance athletes also have high IMCL levels despite being highly insulin sensitive, which indicates that not the level of IMCL accumulation per se, but rather the characteristics of this intramyocellular fat determine whether it negatively affects insulin signaling. Intramyocellular lipids are mainly stored in lipid droplets, the organelles for fat storage. Recent research indicates that creating intramyocellular neutral lipid storage capacity for example by increasing the abundance of lipid droplet coat proteins protects against obesity-associated insulin resistance in skeletal muscle. | 1 | Applied and Interdisciplinary Chemistry |
Pneumatic bladders are used to seal drains and ducts to contain chemical spills or gases. Pneumatic bladders are often used for the containment of chemical spills, oil spills or fire water on water to prevent them from entering the environment, usually in the form of booms. | 1 | Applied and Interdisciplinary Chemistry |
In the early 2020s, molecular biology entered a golden age defined by both vertical and horizontal technical development. Vertically, novel technologies are allowing for real-time monitoring of biological processes at the atomic level. Molecular biologists today have access to increasingly affordable sequencing data at increasingly higher depths, facilitating the development of novel genetic manipulation methods in new non-model organisms. Likewise, synthetic molecular biologists will drive the industrial production of small and macro molecules through the introduction of exogenous metabolic pathways in various prokaryotic and eukaryotic cell lines.
Horizontally, sequencing data is becoming more affordable and used in many different scientific fields. This will drive the development of industries in developing nations and increase accessibility to individual researchers. Likewise, CRISPR-Cas9 gene editing experiments can now be conceived and implemented by individuals for under $10,000 in novel organisms, which will drive the development of industrial and medical applications. | 1 | Applied and Interdisciplinary Chemistry |
The first to report on the relationship between kinetic and thermodynamic control were R.B. Woodward and Harold Baer in 1944. They were re-investigating a reaction between maleic anhydride and a fulvene first reported in 1929 by Otto Diels and Kurt Alder. They observed that while the endo isomer is formed more rapidly, longer reaction times, as well as relatively elevated temperatures, result in higher exo / endo ratios which had to be considered in the light of the remarkable stability of the exo-compound on the one hand and the very facile dissociation of the endo isomer on the other.
C. K. Ingold with E. D. Hughes and G. Catchpole independently described a thermodynamic and kinetic reaction control model in 1948. They were reinvestigating a certain allylic rearrangement reported in 1930 by Jakob Meisenheimer. Solvolysis of gamma-phenylallyl chloride with AcOK in acetic acid was found to give a mixture of the gamma and the alpha acetate with the latter converting to the first by equilibration. This was interpreted as a case in the field of anionotropy of the phenomenon, familiar in prototropy, of the distinction between kinetic and thermodynamic control in ion-recombination. | 0 | Theoretical and Fundamental Chemistry |
For this track, students take classes introducing them to ways to conserve natural resources. This can include classes in water chemistry, sanitation, combustion, air pollution and radioactive waste management. | 1 | Applied and Interdisciplinary Chemistry |
Published in Nov 2019 by CRC Press, Taylor & Francis
The textbook sets out the premise, processes, methods and tools of Transition Engineering. The book includes the perspective stories that Professor Susan Krumdieck has used for sensemaking around wicked problems of change to downshift fossil fuels. Professor Krumdieck was awarded Queens New Years Honours in 2021 with New Zealand Order of Merit for her research, teaching and publication of the book. The book is also popular with non-technical readers.
Transition Engineering, Building a Sustainable Future, Susan Krumdieck (2019) CRC Press, Taylor & Francis, Boca Raton | 1 | Applied and Interdisciplinary Chemistry |
In the unswollen state, hydrogels can be modelled as highly crosslinked chemical gels, in which the system can be described as one continuous polymer network. In this case:
where G is the shear modulus, k is the Boltzmann constant, T is temperature, N is the number of polymer chains per unit volume, ρ is the density, R is the ideal gas constant, and is the (number) average molecular weight between two adjacent cross-linking points. can be calculated from the swell ratio, Q, which is relatively easy to test and measure.
For the swollen state, a perfect gel network can be modeled as:
In a simple uniaxial extension or compression test, the true stress, , and engineering stress, , can be calculated as:
where is the stretch. | 0 | Theoretical and Fundamental Chemistry |
Drug combinations with additive effects have the potential to cause adverse effects. Adverse effects induced by drug combinations are not uncommon. The risk of having adverse effects is increased when the drug combination with additive effect has the same adverse effect. Thus, some drug combinations with additive effect are avoided. Below are commonly seen drug combinations with additive effect causing adverse effects. | 1 | Applied and Interdisciplinary Chemistry |
The nuclear power industry is also a source of uranium in the environment in the form of radioactive waste or through nuclear accidents such as Three Mile Island or the Chernobyl disaster. Perceived risks of contamination associated with this industry contribute to the anti-nuclear movement.
In 2020, there were over 250,000 metric tons of high-level radioactive waste being stored globally in temporary containers. This waste is produced by nuclear power plants and weapons facilities, and is a serious human health and environmental issue. There are plans to permanently dispose of high-level waste in deep geological repositories, but none of these are operational. Corrosion of aging temporary containers has caused some waste to leak into the environment.
Spent uranium dioxide fuel is very insoluble in water, it is likely to release uranium (and fission products) even more slowly than borosilicate glass when in contact with water. | 0 | Theoretical and Fundamental Chemistry |
ASDs are complex; autism is a medical condition with several etiologies caused due to the interactions between environmental conditions and genetic vulnerability. The challenge in finding out the biomarkers related to ASDs is that they may reflect genetic or neurobiological changes that may be active only to a certain point. ASDs show heterogeneous clinical symptoms and genetic architecture, which have hindered the identification of common genetic susceptibility factors. Still, many researches are being done to find out the main reason behind the genetic incomparability. | 1 | Applied and Interdisciplinary Chemistry |
In 1901, Langley challenged the dominant hypothesis that drugs act at nerve endings by demonstrating that nicotine acted at sympathetic ganglia even after the degeneration of the severed preganglionic nerve endings. In 1905 he introduced the concept of a receptive substance on the surface of skeletal muscle that mediated the action of a drug. Langley postulated that these receptive substances were different in different species (citing the fact that nicotine-induced muscle paralysis in mammals was absent in crayfish). Around the same time, Ehrlich was trying to understand the basis of selectivity of agents. He theorized that selectivity was the basis of a preferential distribution of lead and dyes in different body tissues. However, he later modified the theory in order to explain immune reactions and the selectivity of the immune response. Thinking that selectivity was derived from interaction with the tissues themselves, Ehrlich envisaged molecules extending from cells that the body could use to distinguish and mount an immune response to foreign objects. However, it was only after Ahlquist demonstrated the differential effects of adrenaline on two distinct receptor populations, that the theory of receptor-mediated drug interactions gained acceptance. | 1 | Applied and Interdisciplinary Chemistry |
Primary alkyl halides react with aqueous NaOH or KOH to alcohols in nucleophilic aliphatic substitution. (Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead). Grignard reagents react with carbonyl groups to secondary and tertiary alcohols. Related reactions are the Barbier reaction and the Nozaki-Hiyama reaction. | 0 | Theoretical and Fundamental Chemistry |
A meta-analysis of four RCTs concluded that there is no support for selenium supplementation for prevention of type 2 diabetes mellitus in Caucasians. | 1 | Applied and Interdisciplinary Chemistry |
Anoxygenic photosynthesis is a special form of photosynthesis used by some bacteria and archaea, which differs from the better known oxygenic photosynthesis in plants in the reductant used (e.g. hydrogen sulfide instead of water) and the byproduct generated (e.g. elemental sulfur instead of molecular oxygen). | 0 | Theoretical and Fundamental Chemistry |
V̇O max has been measured in other animal species. During loaded swimming, mice had a V̇O max of around 140 mL/(kg·min). Thoroughbred horses had a V̇O max of around 193 mL/(kg·min) after 18 weeks of high-intensity training. Alaskan huskies running in the Iditarod Trail Sled Dog Race had V̇O max values as high as 240 mL/(kg·min). Estimated V̇O max for pronghorn antelopes was as high as 300 mL/(kg·min). | 1 | Applied and Interdisciplinary Chemistry |
Using the A-values of the hydroxyl and isopropyl subunit, the energetic value of a favorable intramolecular hydrogen bond can be calculated. | 0 | Theoretical and Fundamental Chemistry |
The underlying principle is to merge pores of different sizes into a material with a large surface area (thanks to smaller pores), which in turn allows efficient molecular transport (which requires larger pores). The process used to produce these materials is a combination of the replication method, typically used to produce large-pore foams, and the selective dissolution method, generally used to manufacture small-pore foams.
Ag foams with hierarchical porous structures are prepared by the following three-step method:
(i) Packing large spherical NaCl particles to create a hard template, with a distinct perform network of negative space. Then this network is filled with liquid Al-25Ag.
(ii) Removing the NaCl template by water dissolution to form Al−25Ag macro-porous foam.
(iii) Dissolving the Al-rich phase by a chemical attack with aqueous solutions of HCl or NaOH to form the final Ag foam. This creates the nanoscale pores of the foam. | 0 | Theoretical and Fundamental Chemistry |
In thin layer chromatography (TLC) color reactions are frequently used to detect compound spots by dipping the plate into the reagent or by spraying the reagent onto the plates. | 0 | Theoretical and Fundamental Chemistry |
The adsorption and absorption rate of a diluted solute in gas or liquid solution to a surface or interface can be calculated using Fick's laws of diffusion. | 0 | Theoretical and Fundamental Chemistry |
Laser spectroscopy can be used to measure isotope enrichments of gases in the environment. Laser spectroscopy takes advantage of the different vibrational frequencies of isotopologues which cause them to absorb different wavelengths of light. Transmission of light through the gaseous sample at a controlled temperature can be quantitatively converted into a statement about isotopic composition. For N2O, these measurements can determine the position specific isotope enrichments of (N. These measurements are fast and can reach relatively good precision (1-10 per mille). It is used to characterize environmental gas fluxes, and effects on these fluxes. This method is limited to measurement and characterization of gases. | 0 | Theoretical and Fundamental Chemistry |
The applications of photophoresis expand into the various divisions of science, thus physics, chemistry as well as in biology. Photophoresis is applied in particle trapping and levitation, in the field flow fractionation of particles, in the determination of thermal conductivity and temperature of microscopic grains and also in the transport of soot particles in the atmosphere. The use of light in the separation of particles aerosols based on their optical properties, makes possible the separation of organic and inorganic particles of the same aerodynamic size.
Recently, photophoresis has been suggested as a chiral sorting mechanism for single walled carbon nanotubes. The proposed method would utilise differences in the absorption spectra of semiconducting carbon nanotubes arising from optically excited transitions in electronic structure. If developed the technique would be orders of magnitudes faster than currently established ultracentrifugation techniques.
In 2021 Azadi, Popov et al. report "light-driven levitation of macroscopic polymer films with nanostructured surface as candidates for long-duration near-space flight" Using a light intensity comparable to sunlight, they levitated centimeter-scale disks made of commercial 0.5-micron-thick mylar film coated with carbon nanotubes on one side. Experiments by Schafer, Kim, Vlassak and Keith suggest that photophoretic forces could levitate thin 10 centimetre-scale structures in Earth′s stratosphere indefinitely for the purpose of atmospheric science, especially monitoring high-altitude weather. They describe in 2022 a preliminary design fabricated with available methods of a 10 cm diameter device combining a levitating structure of two membranes 2 μm apart in a stiff support structure tested to have sufficient strength to withstand transport, deployment, and flight at 25 km altitude. Payload capacity is 300 mg and could support bidirectional radio communication at over 10 Mb/s and some navigational control. By upscaling the structure it might carry payloads of a few grams. They suggest uses for telecommunications, and deployment on Mars. | 0 | Theoretical and Fundamental Chemistry |
The Bouguer-Lambert law may be applied to describe the attenuation of solar or stellar radiation as it travels through the atmosphere. In this case, there is scattering of radiation as well as absorption. The optical depth for a slant path is , where refers to a vertical path, is called the relative airmass, and for a plane-parallel atmosphere it is determined as where is the zenith angle corresponding to the given path. The Bouguer-Lambert law for the atmosphere is usually written
where each is the optical depth whose subscript identifies the source of the absorption or scattering it describes:
* refers to aerosols (that absorb and scatter);
* are uniformly mixed gases (mainly carbon dioxide (CO) and molecular oxygen (O) which only absorb);
* is nitrogen dioxide, mainly due to urban pollution (absorption only);
* are effects due to Raman scattering in the atmosphere;
* is water vapour absorption;
* is ozone (absorption only);
* is Rayleigh scattering from molecular oxygen () and nitrogen () (responsible for the blue color of the sky);
* the selection of the attenuators which have to be considered depends on the wavelength range and can include various other compounds. This can include tetraoxygen, HONO, formaldehyde, glyoxal, a series of halogen radicals and others.
is the optical mass or airmass factor, a term approximately equal (for small and moderate values of ) to where is the observed objects zenith angle (the angle measured from the direction perpendicular to the Earths surface at the observation site). This equation can be used to retrieve , the aerosol optical thickness, which is necessary for the correction of satellite images and also important in accounting for the role of aerosols in climate. | 0 | Theoretical and Fundamental Chemistry |
Asymmetrical flow field-flow fractionation (AF4) is most versatile and most widely used sub-technique within the family of field flow fractionation (FFF) methods. AF4 can be used in aqueous and organic solvents and is able to characterize nanoparticles, polymers and proteins. The theory for AF4 was conceived in 1986 and was established in 1987 and first published by Wahlund and Giddings. AF4 is distinct from symmetrical Flow FFF because it contains only one permeable wall so the cross-flow is caused only by the carrier liquid. The cross-flow is induced by the carrier liquid constantly exiting by way of the semi-permeable wall on the bottom of the channel. | 0 | Theoretical and Fundamental Chemistry |
During the development of the vertebrate nervous system, many neurons become redundant (because they have died, failed to connect to target cells, etc.) and are eliminated. At the same time, developing neurons send out axon outgrowths that contact their target cells. Such cells control their degree of innervation (the number of axon connections) by the secretion of various specific neurotrophic factors that are essential for neuron survival. One of these is nerve growth factor (NGF or beta-NGF), a vertebrate protein that stimulates division and differentiation of sympathetic and embryonic sensory neurons. NGF is mostly found outside the central nervous system (CNS), but slight traces have been detected in adult CNS tissues, although a physiological role for this is unknown. It has also been found in several snake venoms.
In the peripheral and central neurons, neurotrophins are important regulators for survival, differentiation, and maintenance of nerve cells. They are small proteins that secrete into the nervous system to help keep nerve cells alive. There are two distinct classes of glycosylated receptors that can bind to neurotrophins. These two proteins are p75 (NTR), which binds to all neurotrophins, and subtypes of Trk, which are each specific for different neurotrophins. The reported structure above is a 2.6 Å-resolution crystal structure of neurotrophin-3 (NT-3) complexed to the ectodomain of glycosylated p75 (NRT), forming a symmetrical crystal structure. | 1 | Applied and Interdisciplinary Chemistry |
Synthesis is the step where the structure of the flowsheet is chosen. It is also in this step that one initializes values for variables which one is free to set. | 1 | Applied and Interdisciplinary Chemistry |
Dynamic kinetic resolution under Curtin–Hammett conditions has also been applied to enantioselective lithiation reactions. In the reaction below, it was observed that product enantioselectivities were independent of the chirality of the starting material. The use of (−)-sparteine is essential to enantioselectivity, with racemic product being formed in its absence.
Equilibration between the two alkyllithium complexes was demonstrated by the observation that enantioselectivity remained constant over the course of the reaction. Were the two reactant complexes not rapidly interconverting, enantioselectivity would erode over time as the faster-reacting conformer was depleted. | 0 | Theoretical and Fundamental Chemistry |
A patient undergoing a nuclear medicine procedure will receive a radiation dose. Under present international guidelines it is assumed that any radiation dose, however small, presents a risk. The radiation dose delivered to a patient in a nuclear medicine investigation, though unproven, is generally accepted to present a very small risk of inducing cancer. In this respect it is similar to the risk from X-ray investigations except that the dose is delivered internally rather than from an external source such as an X-ray machine, and dosage amounts are typically significantly higher than those of X-rays.
The radiation dose from a nuclear medicine investigation is expressed as an effective dose with units of sieverts (usually given in millisieverts, mSv). The effective dose resulting from an investigation is influenced by the amount of radioactivity administered in megabecquerels (MBq), the physical properties of the radiopharmaceutical used, its distribution in the body and its rate of clearance from the body.
Effective doses can range from 6 μSv (0.006 mSv) for a 3 MBq chromium-51 EDTA measurement of glomerular filtration rate to 11.2 mSv (11,200 μSv) for an 80 MBq thallium-201 myocardial imaging procedure. The common bone scan with 600 MBq of technetium-99m MDP has an effective dose of approximately 2.9 mSv (2,900 μSv).
Formerly, units of measurement were the curie (Ci), being 3.7E10 Bq, and also 1.0 grams of Radium (Ra-226); the rad (radiation absorbed dose), now replaced by the gray; and the rem (Röntgen equivalent man), now replaced with the sievert. The rad and rem are essentially equivalent for almost all nuclear medicine procedures, and only alpha radiation will produce a higher Rem or Sv value, due to its much higher Relative Biological Effectiveness (RBE). Alpha emitters are nowadays rarely used in nuclear medicine, but were used extensively before the advent of nuclear reactor and accelerator produced radionuclides. The concepts involved in radiation exposure to humans are covered by the field of Health Physics; the development and practice of safe and effective nuclear medicinal techniques is a key focus of Medical Physics. | 1 | Applied and Interdisciplinary Chemistry |
Quartz dolerite or quartz diabase is an intrusive rock similar to dolerite (also called diabase), but with an excess of quartz. Dolerite is similar in composition to basalt, which is volcanic, and gabbro, which is plutonic. The differing crystal sizes are due to the different rate of cooling, basalt cools quickly and has a very fine structure, while gabbro cools very slowly, at great depth, and large crystals develop. Dolerite is intermediate.
Quartz dolerite is very common in central Scotland, in intrusive formations, sills and dykes, and is widely quarried for roadstone. It was used with some success for making millstones at one time, the Millstone Grit part of the carboniferous strata not being present in Scotland, but it is no longer used for this purpose, and would probably be illegal now due to the formation of small quartz and other silicate particles, which could cause the serious respiratory disease silicosis.
In Scotland, quartz dolerite is commonly known as whin or whinstone.
Quartz dolerite contains many cooling fractures and weathers readily, becoming unstable. It is not uncommon for large boulders to break loose, and significant rockfalls are not uncommon. It is regarded as dangerous as far as climbing is concerned. | 0 | Theoretical and Fundamental Chemistry |
The asymmetric atom is called a chirality center, a type of stereocenter. A chirality center is also called a chiral center or an asymmetric center. Some sources use the terms stereocenter, stereogenic center, stereogenic atom or stereogen to refer exclusively to a chirality center, while others use the terms more broadly to refer also to centers that result in diastereomers (stereoisomers that are not enantiomers).
Compounds that contain exactly one (or any odd number) of asymmetric atoms are always chiral. However, compounds that contain an even number of asymmetric atoms sometimes lack chirality because they are arranged in mirror-symmetric pairs, and are known as meso compounds. For instance, meso tartaric acid (shown on the right) has two asymmetric carbon atoms, but it does not exhibit enantiomerism because there is a mirror symmetry plane. Conversely, there exist forms of chirality that do not require asymmetric atoms, such as axial, planar, and helical chirality.
Even though a chiral molecule lacks reflection (C) and rotoreflection symmetries (S), it can have other molecular symmetries, and its symmetry is described by one of the chiral point groups: C, D, T, O, or I. For example, hydrogen peroxide is chiral and has C (two-fold rotational) symmetry. A common chiral case is the point group C, meaning no symmetries, which is the case for lactic acid. | 0 | Theoretical and Fundamental Chemistry |
The BindingDB project was conceived in the mid-1990s, based upon recognition of the broad value of quantitative affinity data and the inadequacy of journal articles as a means of making these data accessible. A NIST-sponsored workshop in September 1997 validated the concept, and funding from the NSF and NIST enabled initial development of the database with a collection of data for systems of many types, including protein-ligand, protein-protein, and host–guest binding. However, hopes that the database would be populated primarily through depositions by experimentalists were not borne out, and it became clear that the project would have to take responsibility for extracting data from the literature. Given the vastness of the molecular recognition literature and limitations in available resources, this meant that creating a useful database would require limiting attention to a well-defined set of high-value binding data.
The decision was taken to focus on binding data for small molecules with proteins that are drug-targets, or potential drug-targets, and for which the three-dimensional structure is available in the PDB or can potentially be modeled to high accuracy based upon the structure of a similar protein. This choice would aid drug-discovery for the selected targets, as well as the development of both ligand-based and structure-based methods of computational ligand-design. This is the current focus of BindingDB, which is led by [http://gilson.ucsd.edu/ Michael Gilson], based at UC San Diego's Skaggs School of Pharmacy and Pharmaceutical Sciences, and supported by a grant from the NIH. | 1 | Applied and Interdisciplinary Chemistry |
In 1962, Atalla joined Hewlett-Packard, where he co-founded Hewlett-Packard and Associates (HP Associates), which provided Hewlett-Packard with fundamental solid-state capabilities. He was the Director of Semiconductor Research at HP Associates, and the first manager of HP's Semiconductor Lab.
He continued research on Schottky diodes, while working with Robert J. Archer, at HP Associates. They developed high vacuum metal film deposition technology, and fabricated stable evaporated/sputtered contacts, publishing their results in January 1963. Their work was a breakthrough in metal–semiconductor junction and Schottky barrier research, as it overcame most of the fabrication problems inherent in point-contact diodes and made it possible to build practical Schottky diodes.
At the Semiconductor Lab during the 1960s, he launched a material science investigation program that provided a base technology for gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP) and indium arsenide (InAs) devices. These devices became the core technology used by HP's Microwave Division to develop sweepers and network analyzers that pushed 2040 GHz frequency, giving HP more than 90% of the military communications market.
Atalla helped create HP Labs in 1966. He directed its solid-state division. | 0 | Theoretical and Fundamental Chemistry |
Roberts attended Wellesley College in 1880. Wellesley made her a graduate assistant in 1881, an instructor in 1882, and an associate professor in 1886. In 1885 she spent a year at Cambridge University working with Sir James Dewar, a chemist and physicist. In 1896 she published The Development and Present Aspects of Stereochemistry. She obtained a PhD from Yale in 1894 and a post at the University of Berlin from 1899 to 1900. She was made a professor and the head of the chemistry department from 1896 to 1917 at Wellesley College. | 0 | Theoretical and Fundamental Chemistry |
E.coli are shown to be more sensitive to accumulations of guanosine tetraphosphate than guanosine pentaphosphate. A complete absence of (p)ppGpp causes multiple amino acid requirements, poor survival of aged cultures, aberrant cell division, morphology, and immotility, as well as being locked in a growth mode during entry into starvation. | 1 | Applied and Interdisciplinary Chemistry |
Crithidia luciliae are haemoflaggelate single celled protists. They are used as a substrate in immunofluorescence for the detection of anti-dsDNA antibodies. They possess an organelle known as the kinetoplast which is a large mitochondrion with a network of interlocking circular dsDNA molecules. After incubation with serum containing anti-dsDNA antibodies and fluorescent-labelled anti-human antibodies, the kinetoplast will fluoresce. The lack of other nuclear antigens in this organelle means that using C. luciliae as a substrate allows for the specific detection of anti-dsDNA antibodies. | 1 | Applied and Interdisciplinary Chemistry |
Early models of the nucleus viewed the nucleus as a rotating liquid drop. In this model, the trade-off of long-range electromagnetic forces and relatively short-range nuclear forces, together cause behavior which resembled surface tension forces in liquid drops of different sizes. This formula is successful at explaining many important phenomena of nuclei, such as their changing amounts of binding energy as their size and composition changes (see semi-empirical mass formula), but it does not explain the special stability which occurs when nuclei have special "magic numbers" of protons or neutrons.
The terms in the semi-empirical mass formula, which can be used to approximate the binding energy of many nuclei, are considered as the sum of five types of energies (see below). Then the picture of a nucleus as a drop of incompressible liquid roughly accounts for the observed variation of binding energy of the nucleus:
Volume energy. When an assembly of nucleons of the same size is packed together into the smallest volume, each interior nucleon has a certain number of other nucleons in contact with it. So, this nuclear energy is proportional to the volume.
Surface energy. A nucleon at the surface of a nucleus interacts with fewer other nucleons than one in the interior of the nucleus and hence its binding energy is less. This surface energy term takes that into account and is therefore negative and is proportional to the surface area.
Coulomb energy. The electric repulsion between each pair of protons in a nucleus contributes toward decreasing its binding energy.
Asymmetry energy (also called Pauli Energy). An energy associated with the Pauli exclusion principle. Were it not for the Coulomb energy, the most stable form of nuclear matter would have the same number of neutrons as protons, since unequal numbers of neutrons and protons imply filling higher energy levels for one type of particle, while leaving lower energy levels vacant for the other type.
Pairing energy. An energy which is a correction term that arises from the tendency of proton pairs and neutron pairs to occur. An even number of particles is more stable than an odd number. | 0 | Theoretical and Fundamental Chemistry |
Cases of inhalation are also known. A man inhaled palytoxin when he tried to kill a Palythoa in his aquarium with boiling water. In 2018, six people from Steventon, Oxfordshire, England were hospitalized after probable exposure by inhalation to "palytoxins" which were released by coral that was being removed from a personal aquarium. Four firefighters, who responded to the incident, were also hospitalized. The patients presented "flu-like symptoms" and eye-irritation. Also in 2018, a woman in Cedar Park, Texas was poisoned when she scraped growing algae from Palythoa polyps in her home aquarium. Other members of the family, including children, also reportedly fell ill. The woman described intense flu-like respiratory symptoms and high fever within hours of inhalation and was hospitalized. Confused physicians initially misdiagnosed the palytoxin poisoning to viral infection. The toxin also killed most of the fish in the aquarium. Many aquatic hobbyists purchase the coral for their bright coloring unaware of the toxins present and the danger of the toxin if it is disturbed. A similar event occurred in the UK in August 2019. | 0 | Theoretical and Fundamental Chemistry |
Planar laser-induced fluorescence (PLIF) is an optical diagnostic technique widely used for flow visualization and quantitative measurements. PLIF has been shown to be used for velocity, concentration, temperature and pressure measurements. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, hydrodynamic stability is the field which analyses the stability and the onset of instability of fluid flows. The study of hydrodynamic stability aims to find out if a given flow is stable or unstable, and if so, how these instabilities will cause the development of turbulence. The foundations of hydrodynamic stability, both theoretical and experimental, were laid most notably by Helmholtz, Kelvin, Rayleigh and Reynolds during the nineteenth century. These foundations have given many useful tools to study hydrodynamic stability. These include Reynolds number, the Euler equations, and the Navier–Stokes equations. When studying flow stability it is useful to understand more simplistic systems, e.g. incompressible and inviscid fluids which can then be developed further onto more complex flows. Since the 1980s, more computational methods are being used to model and analyse the more complex flows. | 1 | Applied and Interdisciplinary Chemistry |
To perform microcrystallization, a small piece of lichen is extracted using acetone or other solvents, filtered, and evaporated to yield a residue. The residue is transferred to a microscope slide, and a drop of microcrystallization reagent is added before capping with a cover glass. Commonly used reagents include GAW (HO/glycerol/ethanol 1:1:1, v/v/v) and GE (acetic acid/glycerol 1:3). Slides using GE or GAW are gently heated and then allowed to cool, promoting the crystallization process. Once formed, crystals are best observed under polarized light with a 200–1,000-fold magnification.
This method requires basic laboratory equipment, including a microscope equipped for polarized light, test tubes, pipettes, a micro spirit-lamp or micro Bunsen burner, spatula or scalpel, and microscope slides and cover glasses. Lichen substances can be identified based on the distinctive shape and color of their crystals. | 0 | Theoretical and Fundamental Chemistry |
For plants to absorb nitrogen from urea it must first be broken down:
Urease is a naturally occurring enzyme that catalyzes the hydrolysis of urea to unstable carbamic acid. Rapid decomposition of carbamic acid occurs without enzyme catalysis to form ammonia and carbon dioxide. The ammonia will likely escape to the atmosphere unless it reacts with water to form ammonium (NH) according to the following reaction:
This is important because ammonium is a plant available source of nitrogen while ammonia is not. Additionally, the formation of the hydroxide ion may cause soils around the applied urea particle to have a pH around 9.0 which increases ammonia volatilization. This area is also highly toxic due to elevated ammonia concentration for several hours so it is recommended that urea based fertilizers not be applied or banded with planted seed at a rate that exceeds 10–20 kg/ha, depending on the crop species. It is important that there is adequate moisture because up to thirty percent of the available nitrogen can be lost through atmospheric volatilization within seventy-two hours of application. | 0 | Theoretical and Fundamental Chemistry |
Several general trends are recognized in determining the structure of Fe–Ni clusters. Larger clusters, containing both iron and nickel, are most stable with Fe atoms located in the inner parts of the cluster and Ni metals on outside. In other terms, when iron and nickel form body-centered cubic structures the preferred position of Ni atoms is at the surface, instead of at the center of the cluster, as it is energetically unfavorable for two nickel atoms to occupy nearest-neighbor positions.
Metal–metal bonds, being d-orbital interactions, happen at larger distances. More stable metal–metal bonds are expected to be longer than unstable bonds. This is shown by the fact that the Fe–Ni bond length is in between Ni–Ni and Fe–Fe bond lengths. For example, in Fe–Ni four-atom clusters (FeNi) which are most stable in a tetrahedral structure, the bond length of metal–metal Fe–Ni bond is 2.65Å and Fe–Fe bond is 2.85 Å. When bonding in these structures is examined, it follows that lowest energy cluster structures of iron and nickel are given by geometries with a maximum number of Fe–Fe bonds, and a small number of Ni–Ni bonds.
The simplest Fe–Ni clusters are of one iron atom and one nickel atom bonded together. More complex clusters can be added through the addition of another atom. Some pictures of sample geometries are shown in Fig. 2.
All Fe–Ni clusters exhibit some degree of distortion from usual geometry. This distortion generally becomes more pronounced as the number of Fe atoms increases.
Notice how in the above cluster diagrams, as calculated by Rollmann and colleagues, the symmetry of the cluster changes from a pure octahedron (D) to a square pyramid (C) as more iron atoms are added. | 0 | Theoretical and Fundamental Chemistry |
Prime editing was developed in the lab of David R. Liu at the Broad Institute and disclosed in Anzalone et al. (2019). Since then prime editing and the research that produced it have received widespread scientific acclaim, being called "revolutionary" and an important part of the future of editing. | 1 | Applied and Interdisciplinary Chemistry |
In the arts, silicon carbide is a popular abrasive in modern lapidary due to the durability and low cost of the material. In manufacturing, it is used for its hardness in abrasive machining processes such as grinding, honing, water-jet cutting and sandblasting. SiC provides a much sharper and harder alternative for sand blasting as compared to aluminium oxide. Particles of silicon carbide are laminated to paper to create sandpapers and the grip tape on skateboards.
In 1982 an exceptionally strong composite of aluminium oxide and silicon carbide whiskers was discovered. Development of this laboratory-produced composite to a commercial product took only three years. In 1985, the first commercial cutting tools made from this alumina and silicon carbide whisker-reinforced composite were introduced into the market. | 1 | Applied and Interdisciplinary Chemistry |
This book describes smelting, which Agricola describes as perfecting the metal by fire. The design of furnaces is first explained.
These are very similar for smelting different metals, constructed of brick or soft stone with a brick front and mechanically driven bellows at the rear. At the front is a pit called the fore-hearth to receive the metal. The furnace is charged with beneficiated ore and crushed charcoal and lit. In some gold and silver smelting a lot of slag is produced because of the relative poverty of the ore and the tap hole has to be opened at various times to remove different slag materials. When the furnace is ready, the forehearth is filled with molten lead into which the furnace is tapped. In other furnaces the smelting can be continuous, and lead is placed into the furnace if there is none in the ore. The slag is skimmed off the top of the metal as it is tapped. The lead containing the gold is separated by cupellation, the metal rich slags are re-smelted. Other smelting processes are similar, but lead is not added. Agricola also describes making crucible steel and distilling mercury and bismuth in this book. | 1 | Applied and Interdisciplinary Chemistry |
SoluForce is a type of Reinforced Thermoplastic Pipe (RTP, also known as flexible composite pipe or FCP). | 1 | Applied and Interdisciplinary Chemistry |
Some major bacterial strains identified as being able to ferment lactose are in the genera Escherichia, Citrobacter, Enterobacter and Klebsiella . All four of these groups fall underneath the family of Enterobacteriaceae. These four genera are able to be separated from each other by using biochemical testing, and simple biological tests are readily available. Apart from whole-sequence genomics, common tests include H2S production, motility and citrate use, indole, methyl red and Voges-Proskauer tests. | 1 | Applied and Interdisciplinary Chemistry |
Tolaasin, a toxic secretion by Pseudomonas tolaasii, is the cause of bacterial brown blotch disease of edible mushrooms. Tolaasin is composed of 18 amino acids, including a beta-hydroxy-octanoic acid chain located at the N terminus. Tolaasin is a 1985 Da lipodepsipeptide non-host specific toxin. In addition to forming an amphipathic left handed alpha-helix in a hydrophobic environment, the toxin has been shown to form Zn-sensitive voltage-gated ion channels in planar lipid bilayers and to catalyze erythrocyte lysis by a colloid osmotic mechanism. At high concentrations, tolaasin acts as a detergent that is able to directly dissolve eukaryotic membranes. The fungal cell membranes are disrupted by the lipopeptides through the formation of trans-membrane pores. Tolaasin pores disrupt the cellular osmotic pressure, leading to membrane collapse. Compounds that inhibit the toxicity of tolaasin have been identified from varying food additives. Tolaasin cytotoxicity can be effectively inhibited by food detergents, as well as sucrose and polyglycerol esters of fatty acids. | 1 | Applied and Interdisciplinary Chemistry |
Early researchers found that an electric or magnetic field could split radioactive emissions into three types of beams. The rays were given the names alpha, beta, and gamma, in increasing order of their ability to penetrate matter. Alpha decay is observed only in heavier elements of atomic number 52 (tellurium) and greater, with the exception of beryllium-8 (which decays to two alpha particles). The other two types of decay are observed in all the elements. Lead, atomic number 82, is the heaviest element to have any isotopes stable (to the limit of measurement) to radioactive decay. Radioactive decay is seen in all isotopes of all elements of atomic number 83 (bismuth) or greater. Bismuth-209, however, is only very slightly radioactive, with a half-life greater than the age of the universe; radioisotopes with extremely long half-lives are considered effectively stable for practical purposes.
In analyzing the nature of the decay products, it was obvious from the direction of the electromagnetic forces applied to the radiations by external magnetic and electric fields that alpha particles carried a positive charge, beta particles carried a negative charge, and gamma rays were neutral. From the magnitude of deflection, it was clear that alpha particles were much more massive than beta particles. Passing alpha particles through a very thin glass window and trapping them in a discharge tube allowed researchers to study the emission spectrum of the captured particles, and ultimately proved that alpha particles are helium nuclei. Other experiments showed beta radiation, resulting from decay and cathode rays, were high-speed electrons. Likewise, gamma radiation and X-rays were found to be high-energy electromagnetic radiation.
The relationship between the types of decays also began to be examined: For example, gamma decay was almost always found to be associated with other types of decay, and occurred at about the same time, or afterwards. Gamma decay as a separate phenomenon, with its own half-life (now termed isomeric transition), was found in natural radioactivity to be a result of the gamma decay of excited metastable nuclear isomers, which were in turn created from other types of decay. Although alpha, beta, and gamma radiations were most commonly found, other types of emission were eventually discovered. Shortly after the discovery of the positron in cosmic ray products, it was realized that the same process that operates in classical beta decay can also produce positrons (positron emission), along with neutrinos (classical beta decay produces antineutrinos). | 0 | Theoretical and Fundamental Chemistry |
The similarity to histone H1 explains how fork head factors are able to bind chromatin by interacting with the major groove of only the one available side of DNA wrapped around a nucleosome. Fork head domains also have a helix that confers sequence specificity unlike linker histone. The C terminus is associated with higher mobility around the nucleosome than linker histone, displacing it and rearranging nucleosomal landscapes effectively. This active re-arrangement of the nucleosomes allows for other transcription factors to bind the available DNA. In thyroid cell differentiation FoxE binds to compacted chromatin of the thyroid peroxidase promoter and opens it for NF1 binding. | 1 | Applied and Interdisciplinary Chemistry |
Cross-polarization (CP) if a fundamental RF pulse sequence and a building-block in many solid-state NMR. It is typically used to enhance the signal of a dilute nuclei with a low gyromagnetic ratio (e.g. , ) by magnetization transfer from an abundant nuclei with a high gyromagnetic ratio (e.g. ), or as a spectral editing method to get through space information (e.g. directed → CP in protein spectroscopy).
To establish magnetization transfer, RF pulses ("contact pulses") are simultaneously applied on both frequency channels to produce fields whose strength fulfil the Hartmann–Hahn condition:
where are the gyromagnetic ratios, is the spinning rate, and is an integer. In practice, the pulse power, as well as the length of the contact pulse are experimentally optimised. The power of one contact pulse is typically ramped to achieve a more broadband and efficient magnetisation transfer. | 0 | Theoretical and Fundamental Chemistry |
Ancient societies used moulds to treat infections, and in the following centuries many people observed the inhibition of bacterial growth by moulds. While working at St Marys Hospital in London in 1928, Scottish physician Alexander Fleming was the first to experimentally determine that a Penicillium mould secretes an antibacterial substance, which he named "penicillin". The mould was found to be a variant of Penicillium notatum (now called Penicillium rubens), a contaminant of a bacterial culture in his laboratory. The work on penicillin at St Marys ended in 1929.
In 1939, a team of scientists at the Sir William Dunn School of Pathology at the University of Oxford, led by Howard Florey that included Edward Abraham, Ernst Chain, Norman Heatley and Margaret Jennings, began researching penicillin. They developed a method for cultivating the mould, and extracting, purifying and storing penicillin from it. They created an assay for measuring its purity. They carried out experiments with animals to determine penicillin's safety and effectiveness before conducting clinical trials and field tests. They derived its chemical formula and determined how it works. The private sector and the United States Department of Agriculture located and produced new strains and developed mass production techniques. Penicillin became an important part of the Allied war effort in the Second World War, saving the lives of thousands of soldiers. Fleming, Florey and Chain shared the 1945 Nobel Prize in Physiology or Medicine for its discovery and development. | 1 | Applied and Interdisciplinary Chemistry |
Kiick first became interested in a career in the chemical sciences when she was at high school. She studied chemistry at the University of Delaware, from which she graduated summa cum laude as a Eugene du Pont memorial distinguished scholar. She was a Masters student at the University of Georgia, where she was awarded a National Science Foundation (NSF) predoctoral fellowship, and joined Kimberly-Clark as a research scientist in 1992. Kiick returned to academia for a second masters degree in polymer science and engineering at the University of Massachusetts Amherst. She completed her doctoral research at the California Institute of Technology, as a National Defense Science and Engineering Graduate (NDSEG) fellow. She completed her PhD from the University of Massachusetts Amherst on templated macromolecular synthesis in 2001 under the supervision of David A. Tirrell, prior to starting her faculty position at the University of Delaware in 2001. | 0 | Theoretical and Fundamental Chemistry |
In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect or Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is forced through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment. This procedure is called a throttling process or Joule–Thomson process. At room temperature, all gases except hydrogen, helium, and neon cool upon expansion by the Joule–Thomson process when being throttled through an orifice; these three gases experience the same effect but only at lower temperatures. Most liquids such as hydraulic oils will be warmed by the Joule–Thomson throttling process.
The gas-cooling throttling process is commonly exploited in refrigeration processes such as liquefiers in air separation industrial process. In hydraulics, the warming effect from Joule–Thomson throttling can be used to find internally leaking valves as these will produce heat which can be detected by thermocouple or thermal-imaging camera. Throttling is a fundamentally irreversible process. The throttling due to the flow resistance in supply lines, heat exchangers, regenerators, and other components of (thermal) machines is a source of losses that limits their performance.
Since it is a constant-enthalpy process, it can be used to experimentally measure the lines of constant enthalpy (isenthalps) on the diagram of a gas. Combined with the specific heat capacity at constant pressure it allows the complete measurement of the thermodynamic potential for the gas. | 0 | Theoretical and Fundamental Chemistry |
Argillaceous rocks are those in which clay minerals are a significant component. For example, argillaceous limestones are limestones consisting predominantly of calcium carbonate, but including 10-40% of clay minerals: such limestones, when soft, are often called marls. Similarly, argillaceous sandstones such as greywacke, are sandstones consisting primarily of quartz grains, with the interstitial spaces filled with clay minerals. | 0 | Theoretical and Fundamental Chemistry |
17α-Epiestriol, or simply 17-epiestriol, also known as 16α-hydroxy-17α-estradiol or estra-1,3,5(10)-triene-3,16α,17α-triol, is a minor and weak endogenous estrogen, and the 17α-epimer of estriol (which is 16α-hydroxy-17β-estradiol). It is formed from 16α-hydroxyestrone. In contrast to other endogenous estrogens like estradiol, 17α-epiestriol is a selective agonist of the ERβ. It is described as a relatively weak estrogen, which is in accordance with its relatively low affinity for the ERα. 17α-Epiestriol has been found to be approximately 400-fold more potent than estradiol in inhibiting tumor necrosis factor α (TNFα)-induced vascular cell adhesion molecule 1 (VCAM-1) expression in vitro. | 1 | Applied and Interdisciplinary Chemistry |
Robinson was an undergraduate student at the University of Cambridge, where she studied natural sciences. She moved to the University of Oxford for her graduate studies, where she investigated pleistocene climate chronology. After completing her doctorate, Robinson moved to California. She was appointed a postdoctoral fellow at California Institute of Technology. At Caltech, worked alongside Jess Adkins on deep sea corals. The research took her on a cruise in the North Atlantic ocean, where she journeyed in a submarine to undersea mountains. On this trip she collected fossils from the sea floor. She studied 16,000 year old coral fossils from the Southern Ocean. This experience inspired her to explore how the Atlantic Ocean changed during climate transitions. She moved to the Woods Hole Oceanographic Institution, where she was made Associate Scientist. | 0 | Theoretical and Fundamental Chemistry |
Gamma rays are produced in many processes of particle physics. Typically, gamma rays are the products of neutral systems which decay through electromagnetic interactions (rather than a weak or strong interaction). For example, in an electron–positron annihilation, the usual products are two gamma ray photons. If the annihilating electron and positron are at rest, each of the resulting gamma rays has an energy of ~ 511 keV and frequency of ~ . Similarly, a neutral pion most often decays into two photons. Many other hadrons and massive bosons also decay electromagnetically. High energy physics experiments, such as the Large Hadron Collider, accordingly employ substantial radiation shielding. Because subatomic particles mostly have far shorter wavelengths than atomic nuclei, particle physics gamma rays are generally several orders of magnitude more energetic than nuclear decay gamma rays. Since gamma rays are at the top of the electromagnetic spectrum in terms of energy, all extremely high-energy photons are gamma rays; for example, a photon having the Planck energy would be a gamma ray. | 0 | Theoretical and Fundamental Chemistry |
Irradiation causes the properties of steels to become poorer, for instance SS316 becomes less ductile and less tough. Also creep and stress corrosion cracking become worse. Papers on this effect continue to be published. | 0 | Theoretical and Fundamental Chemistry |
Cycling probe technology utilizes a cyclic, isothermal process that begins with the hybridization of the chimeric probe with the target DNA. Once hybridized, the probe becomes a suitable substrate for RNase H. RNase H, an endonuclease, cleaves the RNA portion of the probe, resulting in two chimeric fragments. The melting temperature (T) of the newly cleaved fragments is lower than the melting temperature of original probe. Because the CPT reaction is isothermally kept just above the melting point of the original probe, the cleaved fragments dissociate from the target DNA. Once dissociated, the target DNA is free to hybridize with a new probe, beginning the cycle again.
After the fragments have been cleaved and dissociated, they become detectable. A common strategy for detecting the fragments involves fluorescence. With this method, a fluorescent marker is attached to the 5’ end of the probe and a quencher is attached to the 3’ end of the probe. When RNase H cleaves the probe, the quencher and fluorescent marker separate, increasing the intensity of the fluorescent marker. Cleaved fragments can alternatively be detected via amplification (e.g., PCR) or further modification to allow for other chemical means of detection.
When working with small concentrations of target DNA, the CPT protocol can be modified to increase specificity and efficiency. Increasing allotted time has been shown to improve probe cleavage efficiency. Both increasing RNase H concentrations and use of a probe that isn't prone to inter-probe and intra-probe interactions has been shown to increase specificity. | 1 | Applied and Interdisciplinary Chemistry |
Melainabacteria is a phylum related to Cyanobacteria. Organisms belonging to this phylum have been found in the human gut and various aquatic habitats such as groundwater. By analyzing genomes of Melainabacteria, predictions are possible about the cell structure and metabolic abilities. The bacterial cell is similar to cyanobacteria in being surrounded by two membranes. It differs from cyanobacteria in its ability to move by flagella (like gram-negative flagella), though some members (e.g. Gastranaerophilales) lack flagella. Melainabacteria are not able to perform photosynthesis, but obtain energy by fermentation. | 1 | Applied and Interdisciplinary Chemistry |
This idea consists of introducing a modified version of the forcing term: (or equilibrium distribution) into the LBM as a stress divergence force. This force is considered space-time dependent and contains solid properties
where denotes the Cauchy stress tensor. and are respectively the gravity vector and solid matter density.
The stress tensor is usually computed across the lattice aiming finite difference schemes. | 0 | Theoretical and Fundamental Chemistry |
A properly designed and installed extensive green-roof system can cost while an intensive green roof costs However, since most of the materials used to build the green roof can be salvaged, it is estimated that the cost of replacing a green roof is generally one third of the initial installation costs.
With the initial cost of installing a green roof in mind, there are many financial benefits that accompany green roofing.
*Green roofing can extend the lifespan of a roof by over 200% by covering the waterproofing membrane with growing medium and vegetation, this shields the membrane from ultra-violet radiation and physical damage. Further, Penn State University's Green Roof Research Center expects the lifespan of a roof to increase by as much as three times after greening the roof.
*It is estimated that the installation of a green roof could increase the real estate value of an average house by about 7%.
*Reduction in energy use is an important property of green roofing. By improving the thermal performance of a roof, green roofing allows buildings to better retain their heat during the cooler winter months while reflecting and absorbing solar radiation during the hotter summer months, allowing buildings to remain cooler. A study conducted by Environment Canada found a 26% reduction in summer cooling needs and a 26% reduction in winter heat losses when a green roof is used. With respect to hotter summer weather, green roofing is able to reduce the solar heating of a building by reflecting 27% of solar radiation, absorbing 60% by the vegetation through photosynthesis and evapotranspiration, and absorbing the remaining 13% into the growing medium. Such mitigation of solar radiation has been found to reduce building temperatures by up to and reduce energy needs for air-conditioning by 25% to 80%. This reduction in energy required to cool a building in the summer is accompanied by a reduction in energy required to heat a building in the winter, thus reducing the energy requirements of the building year-round which allows the building temperature to be controlled at a lower cost.
*Depending on the region in which a green roof is installed, incentives may be available in the form of stormwater tax reduction, grants, or rebates. The regions where these incentives will most likely be found are areas where failing storm water management infrastructure is in place, urban heat island effect has significantly increased the local air temperature, or areas where environmental contaminants in the storm water runoff is of great concern. An example of such an incentive is a one-year property tax credit is available in New York City, since 2009, for property owners who green at least 50% of their roof area. | 1 | Applied and Interdisciplinary Chemistry |
There has been considerable interest in use of SAMs for new materials e.g. via formation of two- or three-dimensional metal organic superlattices by assembly of SAM capped nanoparticles or layer by layer SAM-nanoparticle arrays using dithiols. A detailed review on this subject using dithiols is given by Hamoudi and Esaulov | 0 | Theoretical and Fundamental Chemistry |
S. aureus causes a number of diseases. Methicillin-resistant S. aureus (MRSA) has generated growing concerns over its resistance to almost all antibiotics except vancomycin. However, most serious S. aureus infections in the community, and many in hospitals, are caused by methicillin-susceptible isolates (MSSA) and there have been few attempts to identify the hypervirulent MSSA clones associated with serious disease. MLST was therefore developed to provide an unambiguous method of characterizing MRSA clones and for the identification of the MSSA clones associated with serious disease. | 1 | Applied and Interdisciplinary Chemistry |
The human body has many defense mechanisms against pathogens, one of which is humoral immunity. This defence mechanism produces antibodies (large glycoproteins) in response to an immune stimulus. Many cells of the immune system are required for this process, including lymphocytes (T-cells and B-cells) and antigen presenting cells. These cells coordinate an immune response upon the detection of foreign proteins (antigens), producing antibodies that bind to these antigens. In normal physiology, lymphocytes that recognise human proteins (autoantigens) either undergo programmed cell death (apoptosis) or become non-functional. This self-tolerance means that lymphocytes should not incite an immune response against human cellular antigens. Sometimes, however, this process malfunctions and antibodies are produced against human antigens, which may lead to autoimmune disease. | 1 | Applied and Interdisciplinary Chemistry |
Biosurveys are used by government agencies responsible for management of public lands, environmental planning and/or environmental regulation to assess ecological resources, such as rivers, streams, lakes and wetlands. They involve collection and analysis of animal and/or plant samples which serve as bioindicators. The studies may be conducted by professional scientists or volunteer organizations. They are conducted according to published procedures to ensure consistency in data collection and analysis, and to compare findings to established metrics.
Biosurveys typically use metrics such as species composition and richness (e.g. number of species, extent of pollution-tolerant species), and ecological factors (number of individuals, proportion of predators, presence of disease). Biosurveys may identify pollution problems that are difficult or expensive to detect using chemical testing procedures.
A biosurvey may be used to generate an index of biological integrity (IBI), a scoring system for an ecological resource. | 1 | Applied and Interdisciplinary Chemistry |
In 2006 the U.S. National Research Council published a report, Human Biomonitoring for Environmental Chemicals. The report recognized the value of biomonitoring for better understanding exposure to environmental chemicals, and included several findings and recommendations to improve the utility of biomonitoring data for health risk assessment. In summary, the report called for more rigorous health-based criteria for selecting chemicals to include in biomonitoring studies; the development of tools and techniques to improve risk-based interpretation and communication of biomonitoring data; integration of biomonitoring into exposure assessment and epidemiological research; and exploration of bioethical issues around biomonitoring, including informed consent, confidentiality of results, and others.
The issue of exposure to environmental chemicals has received attention as a result of televised reports by Bill Moyers for PBS and Anderson Cooper for CNNs "Planet in Peril" series. The book Our Stolen Future', with a foreword by former Vice President Al Gore, also raised awareness by focusing on endocrine disruption.
Surveys of human exposure to chemicals do not usually integrate the number of chemical compounds detected per person and the concentration of each compound. This leaves untested relevant exposure situations; e.g., whether individuals with low concentrations of some compounds have high concentrations of the other compounds. Analyses of the concentrations of a given compound usually show that most citizens have much lower concentrations than a certain minority. A study based on a representative sample of the population of Catalonia (Spain), which integrated the number of compounds detected per person and the concentration of each compound, found that more than half of the population had concentrations in the top quartile of 1 or more of the 19 persistent toxic substances (PTS) (pesticides, PCBs) analyzed. Significant subgroups of the population accumulated PTS mixtures at high concentrations. For instance, 48% of women 60–74 years had concentrations of 6 or more PTS in the top quartile; half of the entire population had levels of 1 to 5 PTS above 500 ng/g, and less than 4% of citizens had all PTS in the lowest quartile. Thus, PTS concentrations appear low in most of the population only when each individual compound is looked at separately. It is not accurate to state that most of the population has low concentrations of PTS. The assessment of mixture effects must address the fact that most individuals are contaminated by PTS mixtures made of compounds at both low and high concentrations. | 1 | Applied and Interdisciplinary Chemistry |
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