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DTIs that fit in the active binding site have to fit in the hydrophobic pocket (S1) that contains aspartic acid residue at the bottom which recognizes the basic side chain. The S2 site has a loop around tryptophan which occludes a hydrophobic pocket that can recognize larger aliphatic residues. The S3 site is flat and the S4 site is hydrophobic, it has tryptophan lined by leucine and isoleucine.
Nα-(2-naphthyl-sulphonyl-glycyl)-DL-p-amidinophenylalanyl-piperidine (NAPAP) binds thrombin in the S1, S2 and S4 pockets. The amidine group on NAPAP forms a bidentate salt bridge with Asp deep in the S1 pocket, the piperidine group takes the role of proline residue and binds in the S2 pocket, and the naphthyl rings of the molecule forms a hydrophobic interaction with Trp in the S4 pocket. Pharmaceutical companies have used the structural knowledge of NAPAP to develop DTIs. Dabigatran, like NAPAP binds to S1, S2 and S4 pockets. Benzamidine group on the dabigatran structure binds deep in the S1 pocket, the methylbenzimidazole fits nicely in the hydrophobic S2 pocket and the Ile and Leu at the bottom of the S4 pocket binds to the aromatic group of dabigatran. | 1 | Applied and Interdisciplinary Chemistry |
Androsterone glucuronide (ADT-G) is a major circulating and urinary metabolite of testosterone and dihydrotestosterone (DHT). It accounts for 93% of total androgen glucuronides in women. ADT-G is formed from androsterone by UDP-glucuronosyltransferases, with the major enzymes being UGT2B15 and UGT2B17. It is a marker of acne in women while androstanediol glucuronide is a marker of hirsutism (excess hair growth) in women. | 1 | Applied and Interdisciplinary Chemistry |
Iodine-125 is commonly used for labeling proteins, usually at tyrosine residues. Unbound iodine is volatile and must be handled in a fume hood. Its maximum specific activity is .
A good example of the difference in energy of the various radionuclei is the detection window ranges used to detect them, which are generally proportional to the energy of the emission, but vary from machine to machine: in a Perkin elmer TriLux Beta scintillation counter , the hydrogen-3 energy range window is between channel 5–360; carbon-14, sulfur-35 and phosphorus-33 are in the window of 361–660; and phosphorus-32 is in the window of 661–1024. | 0 | Theoretical and Fundamental Chemistry |
The kinetic process of destabilization can be rather long – up to several months, or even years for some products. Often the formulator must accelerate this process in order to test products in a reasonable time during product design. Thermal methods are the most commonly used – these consist of increasing the emulsion temperature to accelerate destabilization (if below critical temperatures for phase inversion or chemical degradation). Temperature affects not only the viscosity but also the interfacial tension in the case of non-ionic surfactants or, on a broader scope, interactions between droplets within the system. Storing an emulsion at high temperatures enables the simulation of realistic conditions for a product (e.g., a tube of sunscreen emulsion in a car in the summer heat), but also accelerates destabilization processes up to 200 times.
Mechanical methods of acceleration, including vibration, centrifugation, and agitation, can also be used.
These methods are almost always empirical, without a sound scientific basis. | 0 | Theoretical and Fundamental Chemistry |
Another form of plant communication occurs through their root networks. Through roots, plants can share many different resources including carbon, nitrogen, and other nutrients. This transfer of below ground carbon is examined in Philip et al. 2011. The goals of this paper were to test if carbon transfer was bi-directional, if one species had a net gain in carbon, and if more carbon was transferred through the soil pathway or common mycorrhizal network (CMN). CMNs occur when fungal mycelia link roots of plants together. The researchers followed seedlings of paper birch and Douglas-fir in a greenhouse for 8 months, where hyphal linkages that crossed their roots were either severed or left intact. The experiment measured amounts of labeled carbon exchanged between seedlings. It was discovered that there was indeed a bi-directional sharing of carbon between the two tree species, with the Douglas-fir receiving a slight net gain in carbon. Also, the carbon was transferred through both soil and the CMN pathways, as transfer occurred when the CMN linkages were interrupted, but much more transfer occurred when the CMN's were left unbroken.
This experiment showed that through fungal mycelia linkage of the roots of two plants, plants are able to communicate with one another and transfer nutrients as well as other resources through below ground root networks. Further studies go on to argue that this underground “tree talk” is crucial in the adaptation of forest ecosystems. Plant genotypes have shown that mycorrhizal fungal traits are heritable and play a role in plant behavior. These relationships with fungal networks can be mutualistic, commensal, or even parasitic. It has been shown that plants can rapidly change behavior such as root growth, shoot growth, photosynthetic rate, and defense mechanisms in response to mycorrhizal colonization. Through root systems and common mycorrhizal networks, plants are able to communicate with one another below ground and alter behaviors or even share nutrients depending on different environmental cues. | 1 | Applied and Interdisciplinary Chemistry |
Fumagillin has been used in the treatment of microsporidiosis. It is also an amebicide.
Fumagillin can block blood vessel formation by binding to an enzyme methionine aminopeptidase 2 and for this reason, the compound, together with semisynthetic derivatives, are investigated as an angiogenesis inhibitor in the treatment of cancer.
The company Zafgen conducted clinical trials using the fumagillin analog beloranib for weight loss, but they were unsuccessful.
Fumagillin is toxic to erythrocytes in vitro at concentrations greater than 10 μM. | 0 | Theoretical and Fundamental Chemistry |
Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron. This reaction has a quite small absorption cross section, making heavy water a good neutron moderator, and relatively little tritium is produced. Even so, cleaning tritium from the moderator may be desirable after several years to reduce the risk of its escaping to the environment. Ontario Power Generation's "Tritium Removal Facility" processes up to of heavy water a year, and it separates out about of tritium, making it available for other uses.
CANDU reactors typically produce of tritium per year, which is recovered at the Darlington Tritium Recovery Facility (DTRF) attached to the 3,512 MW Darlington Nuclear Generating Station in Ontario. The total production at DTRF between 1989 and 2011 was – with an activity of – which averages to about per year.
Deuterium's absorption cross section for thermal neutrons is about 0.52 millibarns, whereas that of oxygen-16 () is about 0.19 millibarns and that of oxygen-17 () is about 240 millibarns. While is by far the most common isotope of oxygen in both natural oxygen and heavy water, depending on the method used for isotope separation, heavy water may be slightly to notably higher in and content. Due to both neutron capture and (n,α) reactions (the latter of which produce , an undesirable long-lived beta emitter, from ) they are net "neutron consumers" and are thus undesirable in a moderator of a natural uranium reactor which needs to keep neutron absorption outside the fuel as low as feasible. Some facilities that remove tritium also remove (or at least reduce the content of) and , which can – at least in principle – be put to use for isotope labeling.
India, which also has a large fleet of pressurized heavy water reactors (initially CANDU technology but since indigenized and further developed IPHWR technology), also removes at least some of the tritium produced in the moderator/coolant of its reactors but due to the dual use nature of tritium and the Indian nuclear bomb program, less information about this is publicly available than for Canada. | 0 | Theoretical and Fundamental Chemistry |
Best management practices (BMPs) is a term used in the United States and Canada to describe a type of water pollution control. Historically the term has referred to auxiliary pollution controls in the fields of industrial wastewater control and municipal sewage control, while in stormwater management (both urban and rural) and wetland management, BMPs may refer to a principal control or treatment technique as well. | 1 | Applied and Interdisciplinary Chemistry |
DEHPA is prepared through the reaction of phosphorus pentoxide and 2-ethylhexanol:
:4 CHOH + PO → 2 [(CHO)PO(OH)]O
:[(CHO)PO(OH)]O + CHOH → (CHO)PO(OH) + (CHO)PO(OH)
These reaction produce a mixture of mono-, di-, and trisubstituted phosphates, from which DEHPA can be isolated based on solubility. | 0 | Theoretical and Fundamental Chemistry |
The Venerable Bede discusses the tides in The Reckoning of Time and shows that the twice-daily timing of tides is related to the Moon and that the lunar monthly cycle of spring and neap tides is also related to the Moon's position. He goes on to note that the times of tides vary along the same coast and that the water movements cause low tide at one place when there is high tide elsewhere. However, he made no progress regarding the question of how exactly the Moon created the tides.
Medieval rule-of-thumb methods for predicting tides were said to allow one "to know what Moon makes high water" from the Moons movements. Dante references the Moons influence on the tides in his Divine Comedy.
Medieval European understanding of the tides was often based on works of Muslim astronomers, which became available through Latin translation starting from the 12th century. Abu Mashar al-Balkhi, in his Introductorium in astronomiam, taught that ebb and flood tides were caused by the Moon. Abu Mashar discussed the effects of wind and Moons phases relative to the Sun on the tides. In the 12th century, al-Bitruji contributed the notion that the tides were caused by the general circulation of the heavens. Medieval Arabic astrologers frequently referenced the Moons influence on the tides as evidence for the reality of astrology; some of their treatises on the topic influenced western Europe. Some theorized that the influence was caused by lunar rays heating the ocean's floor. | 1 | Applied and Interdisciplinary Chemistry |
One aspect of RNA silencing to consider is its possible off-target affects, toxicity, and delivery methods. If RNA silencing is to become a conventional drug, it must first pass the typical ethical issues of biomedicine. Using risk-benefit analysis, researchers can determine whether RNA silencing conforms to ethical ideologies such as nonmaleficence, beneficence, and autonomy.
There is a risk of creating infection-competent viruses that could infect non-consenting people. There is also a risk of affecting future generations based on these treatments. These two scenarios, in respect to autonomy, is possible unethical. At this moment, unsafe delivery methods and unintended aspects of vector viruses add to the argument against RNA silencing.
In terms of off-target effects, siRNA can induce innate interferon responses, inhibit endogenous miRNAs through saturation, and may have complementary sequences to other non-target mRNAs. These off-targets could also have target up-regulations such as oncogenes and antiapoptotic genes. The toxicity of RNA silencing is still under review as there are conflicting reports.
RNA silencing is quickly developing, because of that, the ethical issues need to be discussed further. With the knowledge of general ethical principles, we must continuously perform risk-benefit analysis. | 1 | Applied and Interdisciplinary Chemistry |
Phosphines accept electron density from metal p or d orbitals into combinations of P–C σ* antibonding orbitals that have π symmetry. When phosphines bond to electron-rich metal atoms, backbonding would be expected to lengthen P–C bonds as P–C σ* orbitals become populated by electrons. The expected lengthening of the P–C distance is often hidden by an opposing effect: as the phosphorus lone pair is donated to the metal, P(lone pair)–R(bonding pair) repulsions decrease, which acts to shorten the P–C bond. The two effects have been deconvoluted by comparing the structures of pairs of metal-phosphine complexes that differ only by one electron. Oxidation of RP–M complexes results in longer M–P bonds and shorter P–C bonds, consistent with π-backbonding. In early work, phosphine ligands were thought to utilize 3d orbitals to form M–P pi-bonding, but it is now accepted that d-orbitals on phosphorus are not involved in bonding as they are too high in energy. | 0 | Theoretical and Fundamental Chemistry |
The use of photoredox catalysis to generate reactive heteroatom-centered radicals was first explored in the 1990s. [Ru(bipy)] was found to catalyze the fragmentation of tosylphenylselenide to phenylselenolate anion and tosyl radical and that a radical chain propagation mechanism allowed the addition of tosyl radical and phenylseleno- radical across the double bond of electron rich alkyl vinyl ethers. Since phenylselenolate anion is readily oxidized to diphenyldiselenide, the low quantities of diphenyldiselenide observed was taken as an indication that photoredox-catalyzed fragmentation of tosylphenylselenide was only important as an initiation step, and that most of the reactivity was due to a radical chain process.
Heteroaromatic additions to olefins include multicomponent oxy- and aminotrifluoromethylation reactions. These reactions use Umemotos reagent, a sulfonium salt that serves as an electrophilic source of the trifluoromethyl group and that is precedented to react via a single-electron transfer pathway. Thus, single-electron reduction of Umemotos reagent releases trifluoromethyl radical, which adds to the reactive olefin. Subsequently, single-electron oxidation of the alkyl radical generated by this addition produces a cation which can be trapped by water, an alcohol, or a nitrile. In order to achieve high levels of regioselectivity, this reactivity has been explored mainly for styrenes, which are biased towards formation of the benzylic radical intermediate.
Hydrotrifluoromethylation of styrenes and aliphatic alkenes can be effected with a mesityl acridinium organic photoredox catalyst and Langlois' reagent as the source of CF radical. In this reaction, it was found that trifluoroethanol and substoichiometric amounts of an aromatic thiol, such as methyl thiosalicylate, employed in tandem served as the best source of hydrogen radical to complete the catalytic cycle.
Intramolecular hydroetherifications and hydroaminations proceed with anti-Markovnikov selectivity. One mechanism invokes the single-electron oxidation of the olefin, trapping the radical cation by a pendant hydroxyl or amine functional group, and quenching the resulting alkyl radical by H-atom transfer from a highly labile donor species. Extensions of this reactivity to intermolecular systems have resulted in i) a new synthetic route to complex tetrahydrofurans by a "polar-radical-crossover cycloaddition" (PRCC reaction) of an allylic alcohol with an olefin, and ii) the anti-Markovnikov addition of carboxylic acids to olefins. | 0 | Theoretical and Fundamental Chemistry |
* 2011 "Distinguished Service to Humanism Award" from the International Humanist and Ethical Union
* 2015 "Lawrence Pinto Human Rights Award" from the Friends of Lawry
* 2017 "Academy Honorary Award" Karnataka Balavikas Academy, Directorate of Women and Child Development Department, Government of Karnataka | 1 | Applied and Interdisciplinary Chemistry |
Dozens of congenital metabolic diseases also known as inborn errors of metabolism (IEM) are now detectable by newborn screening tests, especially the testing using gas chromatography–mass spectrometry. GC–MS can determine compounds in urine even in minor concentration. These compounds are normally not present but appear in individuals suffering with metabolic disorders. This is increasingly becoming a common way to diagnose IEM for earlier diagnosis and institution of treatment eventually leading to a better outcome. It is now possible to test a newborn for over 100 genetic metabolic disorders by a urine test at birth based on GC–MS.
In combination with isotopic labeling of metabolic compounds, the GC–MS is used for determining metabolic activity. Most applications are based on the use of C as the labeling and the measurement of C-C ratios with an isotope ratio mass spectrometer (IRMS); an MS with a detector designed to measure a few select ions and return values as ratios. | 0 | Theoretical and Fundamental Chemistry |
Plasmonic nanoparticles are particles whose electron density can couple with electromagnetic radiation of wavelengths that are far larger than the particle due to the nature of the dielectric-metal interface between the medium and the particles: unlike in a pure metal where there is a maximum limit on what size wavelength can be effectively coupled based on the material size.
What differentiates these particles from normal surface plasmons is that plasmonic nanoparticles also exhibit interesting scattering, absorbance, and coupling properties based on their geometries and relative positions. These unique properties have made them a focus of research in many applications including solar cells, spectroscopy, signal enhancement for imaging, and cancer treatment. Their high sensitivity also identifies them as good candidates for designing mechano-optical instrumentation.
Plasmons are the oscillations of free electrons that are the consequence of the formation of a dipole in the material due to electromagnetic waves. The electrons migrate in the material to restore its initial state; however, the light waves oscillate, leading to a constant shift in the dipole that forces the electrons to oscillate at the same frequency as the light. This coupling only occurs when the frequency of the light is equal to or less than the plasma frequency and is greatest at the plasma frequency that is therefore called the resonant frequency. The scattering and absorbance cross-sections describe the intensity of a given frequency to be scattered or absorbed. Many fabrication processes or chemical synthesis methods exist for preparation of such nanoparticles, depending on the desired size and geometry.
The nanoparticles can form clusters (the so-called "plasmonic molecules") and interact with each other to form cluster states. The symmetry of the nanoparticles and the distribution of the electrons within them can affect a type of bonding or antibonding character between the nanoparticles similarly to molecular orbitals. Since light couples with the electrons, polarized light can be used to control the distribution of the electrons and alter the mulliken term symbol for the irreducible representation. Changing the geometry of the nanoparticles can be used to manipulate the optical activity and properties of the system, but so can the polarized light by lowering the symmetry of the conductive electrons inside the particles and changing the dipole moment of the cluster. These clusters can be used to manipulate light on the nano scale. | 0 | Theoretical and Fundamental Chemistry |
The aluminothermic reaction is used for the production of several ferroalloys, for example ferroniobium from niobium pentoxide and ferrovanadium from iron, vanadium(V) oxide, and aluminium. The process begins with the reduction of the oxide by the aluminium:
:3 VO + 10 Al → 5 AlO + 6 V
Other metals can be produced from their oxides in the same way.
Aluminothermic reactions have been used for welding rail tracks on-site, useful for complex installations or local repairs that cannot be done using continuously welded rail. Another common use is the welding of copper cables (wire) for use in direct burial (grounding/earthing) applications. It is still the only type of electrical connection recognized by the IEEE (IEEE, Std 80–2001) as continuous un-spliced cable. | 1 | Applied and Interdisciplinary Chemistry |
A core suite of environmental variables was selected at the start of the program that is expected to display detectable change on time scales of several days to one decade. Since 1988, the interdisciplinary station work has included physical, chemical, biological and sedimentological observations and rate measurements. The initial phase of the HOT program (October 1988 – February 1991) was entirely supported by research vessels, with the exception of the availability of existing satellite and ocean buoy sea surface data. In February 1991, an array of inverted echosounders (IES) was deployed around Station ALOHA and in June 1992, a sequencing sediment trap mooring was deployed a few km north of it. In 1993, the IES network was replaced with two strategically positioned instruments: one at Station ALOHA and the other at the coastal station Kaena. A physical-biogeochemical mooring (known as HALE-ALOHA) was deployed from January 1997 to June 2000 for high frequency atmospheric and oceanic observations.
HOT relies on the University-National Oceanographic Laboratory System research vessel Kilo Moana operated by the University of Hawaii for most of the near-monthly sampling expeditions. When at Station ALOHA, a variety of sampling strategies is used to capture the range of physical and biogeochemical dynamics natural to the NPSG ecosystem. These strategies include high resolution conductivity-temperature-depth (CTD) profiles, biogeochemical analyses of discrete water samples, in situ vertically profiling bio-optical instrumentation, free-drifting arrays for determinations of primary production and particle fluxes, deep ocean sediment traps, and oblique plankton net tows.
The suite of core measurements conducted by HOT has remained largely unchanged over the program’s lifetime. On each HOT cruise, samples are collected from the surface ocean to near the sea bed (~4,800 m), with the most intensive sampling occurring in the upper 1,000 m. HOT utilizes a “burst” vertical profiling strategy where physical and biogeochemical properties are measured at 3 hour intervals over a 36-hour period, covering 3 semi-diurnal tidal cycles and 1 inertial period (~31 hours). This approach captures variability in ocean dynamics due to internal tides around Station ALOHA. It is designed to assess variability on time scales of a few hours to a few years. High frequency variability (less than 6 hours) and variability on time scales of between 3–60 days are not adequately sampled at the present time. | 0 | Theoretical and Fundamental Chemistry |
A lipopeptide is a molecule consisting of a lipid connected to a peptide. They are able to self-assemble into different structures. Many bacteria produce these molecules as a part of their metabolism, especially those of the genus Bacillus, Pseudomonas and Streptomyces. Certain lipopeptides are used as antibiotics. Due to the structural and molecular properties such as the fatty acid chain, it poses the effect of weakening the cell function or destroying the cell. Other lipopeptides are toll-like receptor agonists. Certain lipopeptides can have strong antifungal and hemolytic activities. It has been demonstrated that their activity is generally linked to interactions with the plasma membrane, and sterol components of the plasma membrane could play a major role in this interaction. It is a general trend that adding a lipid group of a certain length (typically C10–C12) to a lipopeptide will increase its bactericidal activity. Lipopeptides with a higher amount of carbon atoms, for example 14 or 16, in its lipid tail will typically have antibacterial activity as well as anti-fungal activity. Therefore, an increase in the alkyl chain can make lipopeptides soluble in water. As well, it opens the cell membrane of the bacteria, so antimicrobial activity can take place.
Lipopeptide detergents (LPDs) are composed of amphiphiles and two alkyl chains which are located on the last part of the peptide backbone. They were designed to mimic the architecture of the native membranes in which two alkyl chains in a lipid molecule facially interact with the hydrophobic segment of MPs. | 1 | Applied and Interdisciplinary Chemistry |
Ethane-1,2-dithiol, also known as EDT, is a colorless liquid with the formula CH(SH). It has a very characteristic odor which is compared by many people to rotten cabbage. It is a common building block in organic synthesis and an excellent ligand for metal ions. | 0 | Theoretical and Fundamental Chemistry |
Membrane bioreactors (MBR) are activated sludge systems using a membrane liquid-solid phase separation process. The membrane component uses low pressure microfiltration or ultrafiltration membranes and eliminates the need for a secondary clarifier or filtration. The membranes are typically immersed in the aeration tank; however, some applications utilize a separate membrane tank. One of the key benefits of an MBR system is that it effectively overcomes the limitations associated with poor settling of sludge in conventional activated sludge (CAS) processes. The technology permits bioreactor operation with considerably higher mixed liquor suspended solids (MLSS) concentration than CAS systems, which are limited by sludge settling. The process is typically operated at MLSS in the range of 8,000–12,000 mg/L, while CAS are operated in the range of 2,000–3,000 mg/L. The elevated biomass concentration in the MBR process allows for very effective removal of both soluble and particulate biodegradable materials at higher loading rates. Thus increased sludge retention times, usually exceeding 15 days, ensure complete nitrification even in extremely cold weather.
The cost of building and operating an MBR is often higher than conventional methods of sewage treatment. Membrane filters can be blinded with grease or abraded by suspended grit and lack a clarifier's flexibility to pass peak flows. The technology has become increasingly popular for reliably pretreated waste streams and has gained wider acceptance where infiltration and inflow have been controlled, however, and the life-cycle costs have been steadily decreasing. The small footprint of MBR systems, and the high quality effluent produced, make them particularly useful for water reuse applications. | 1 | Applied and Interdisciplinary Chemistry |
Worldwide production of R-22 in 2008 was about 800Gg per year, up from about 450Gg per year in 1998, with most production in developing countries. R-22 use is being phased out in developing countries, where it is largely used for air conditioning applications. Air conditioning sales are growing 20% annually in India and China.
R-22 is prepared from chloroform:
:HCCl + 2 HF → HCFCl + 2 HCl
An important application of R-22 is as a precursor to tetrafluoroethylene. This conversion involves pyrolysis to give difluorocarbene, which dimerizes:
:2 CHClF → CF + 2 HCl
The compound also yields difluorocarbene upon treatment with strong base and is used in the laboratory as a source of this reactive intermediate.
The pyrolysis of R-22 in the presence of chlorofluoromethane gives hexafluorobenzene. | 1 | Applied and Interdisciplinary Chemistry |
On March 27, 1965, Beatles members John Lennon and George Harrison (and their wives) were dosed with LSD without their permission by their dentist, John Riley. Lennon mentioned the incident in his famous 1970 Rolling Stone interview, but the name of the dentist was revealed only in 2006. On August 24, 1965, Lennon, Harrison and Ringo Starr took their second trip on LSD. Actor Peter Fonda repeatedly said "I know what its like to be dead" to John Lennon during an LSD trip. John Lennon wrote "Lucy in the Sky with Diamonds", a fanciful song which many assumed referred to LSD, although he always denied the connection as coincidence. The songs "She Said She Said" and "Tomorrow Never Knows" from the Beatles Revolver album explicitly reference LSD trips, and many lines of "Tomorrow Never Knows" were borrowed from Timothy Learys book The Psychedelic Experience. Around the same time, bands such as Pink Floyd, Jefferson Airplane, and The Grateful Dead helped give birth to a genre known as "psychedelic rock" or acid rock. In 1965, The Pretty Things released an album called Get the Picture?' which included a track titled "L.S.D."
LSD became a headline item in early 1967, and the Beatles admitted to having been under the influence of LSD. Earlier in the year, British tabloid News of the World ran a sensational three-week series on "drug parties" hosted by rock group the Moody Blues and attended by leading stars including Donovan, the Whos Pete Townshend and Cream drummer Ginger Baker. Largely as a result of collusion between News of the World' journalists and the London Drug Squad, many pop stars including Donovan and Rolling Stones members Mick Jagger and Keith Richards were arrested for drug possession, although none of the arrests involved LSD.
The FBI suggested in now declassified documents that the Grateful Dead were responsible for introducing LSD to the U.S. The Grateful Dead were the "house band" at Ken Kesey and the Merry Pranksters Acid Tests. These free-form parties introduced many people on the West Coast to LSD for the first time, as documented in Tom Wolfes The Electric Kool-Aid Acid Test and Phil Leshs Searching for the Sound. Acid historian Jesse Jarnow describes how Grateful Dead concerts served as the United States primary distribution network for LSD in the second half of the twentieth century.
In 1992, Mike Dirnt of Green Day wrote the famous "Longview" bass line while under the influence of LSD. In an interview, Green Day lead singer and guitarist Billie Joe Armstrong recalled that he arrived at their house and saw Mike sitting on the floor with highly dilated pupils, holding his bass guitar. Mike looked up at Billie and exclaimed, "Listen to this!" | 1 | Applied and Interdisciplinary Chemistry |
Spinthariscopes were quickly replaced with more accurate and quantitative devices for measuring radiation in scientific experiments, but enjoyed a modest revival in the mid 20th century as children's educational toys. In 1947, Kix cereal offered a Lone Ranger atomic bomb ring that contained a small one, in exchange for a box top and US$0.15 (). Spinthariscopes can still be bought today as instructional novelties, but they now use americium or thorium. Looking into a properly focused toy spinthariscope, one can see many flashes of light spread randomly across the screen. Almost all are circular, with a very bright pinpoint centre surrounded by a dimmer circle of emission. | 0 | Theoretical and Fundamental Chemistry |
Gadolin was fluent in Latin, Finnish, Russian, German, English and French in addition to his native Swedish. He was a candidate for the chair of chemistry at Uppsala in 1784, but Johann Afzelius was selected instead. Gadolin became an extraordinary professor at Åbo in 1785 (an unpaid position). Beginning in 1786, he made a chemical "grand tour" of Europe, visiting universities and mines in various countries. He worked with Lorenz Crell, editor of the journal Chemische Annalen in Germany, and with Adair Crawford and Richard Kirwan in Ireland.
Gadolin was elected a member of the Royal Swedish Academy of Sciences in 1790.
Gadolin became the ordinary professor of chemistry at the Royal Academy of Turku in 1797, after the death of Pehr Adrian Gadd. He retained the position until his retirement in 1822. He was one of the first chemists who gave laboratory exercises to students. He even allowed the students to use his private laboratory. | 1 | Applied and Interdisciplinary Chemistry |
In general, the chemical structure of a given polycyclic aromatic hydrocarbon admits more than one resonance structure: these are sometimes referred to as Kekulé resonance structures. Some of such structures may contain aromatic π-sextets, namely groups of six π-electrons localized in a benzene-like moiety and separated by adjacent rings by formal C–C bonds. An aromatic π-sextet can be represented by a circle, as in the case of the anthracene molecule. Clars rule states that for a benzenoid polycyclic aromatic hydrocarbon (i.e. with only hexagonal rings), the resonance structure with the largest number of disjoint aromatic π-sextets is the most important to characterize its chemical and physical properties. Such resonance structure is called the Clar structure. In other words, a polycyclic aromatic hydrocarbon with a given number of π-sextets is more stable than its isomers with less π-sextets. In 1984, Glidewell and Lloyd provided an extension of Clars rule to polycyclic aromatic hydrocarbons containing rings of any size. More recently, Clar's rule was further extended to biradicaloids in their singlet state. | 0 | Theoretical and Fundamental Chemistry |
Other functions of coatings include:
* Anti-fouling coatings
* Anti-microbial coatings.
* Anti-reflective coatings for example on spectacles.
* Coatings that alter or have magnetic, electrical or electronic properties.
* Flame retardant coatings. Flame-retardant materials and coatings are being developed that are phosphorus and bio-based. These include coatings with intumescent functionality.
* Non-stick PTFE coated cooking pots/pans.
* Optical coatings are available that alter optical properties of a material or object.
* UV coatings | 1 | Applied and Interdisciplinary Chemistry |
Two syringes are filled with solutions that do not undergo a chemical reaction until mixed together. These have pistons that are driven by a single drive piston or by independent stepping motors, so that they are coupled together and their contents are forced out simultaneously into a mixing device. | 0 | Theoretical and Fundamental Chemistry |
There are several biological surfaces that have superhydrophobic properties far superior to any synthetic materials: lotus leaves, rice leaves, cicadia wings, and butterfly wings. | 0 | Theoretical and Fundamental Chemistry |
Pipe drift is a measure of the roundness or eccentricity of the inside wall of a pipe. "API drift" refers to primary specifications set forth in API Specification 5CT (ISO 11960), "Specification for Casing and Tubing". "Alternate drift" refers to alternate drift specifications listed in API 5CT. "Special drift" refers to industry drift specifications other than those found in API 5CT.
Drifting means measuring a pipe's inner roundness. Drifting is typically performed by passing a cylindrical mandrel through the length of the pipe to detect occlusions. It occurs both at the pipe mill and in the field. Drifting is performed to ensure that tools, pumps, smaller pipe, and other items can be passed through the pipe. | 1 | Applied and Interdisciplinary Chemistry |
Mass spectrometry (MS) is helpful for the determination of the molecular weight of the polymer, structure of the polymer, etc. Although chemists utilize many kinds of MS, the two that are used most typically are matrix-assisted laser desorption ionization/time of flight (MALDI-TOF) and electrospray ionization-mass spectroscopy (ESI-MS). One of the biggest disadvantages of this technique is that much like NMR spectroscopy the polymers have to be soluble in some organic solvent. An advantage of using MALDI is that it provides the simpler data to interpret for end group identification compared with ESI, but a disadvantage is that the ionization can be rather hard and as a result some end groups do not remain intact for analysis. Because of the harsh ionization in MALDI, one of the biggest advantages of using ESI is for its "softer" ionization methods. The disadvantage of using ESI is that the data obtained can be very complex due to the mechanism of the ionization and thus can be difficult to interpret. | 0 | Theoretical and Fundamental Chemistry |
The first examples of nontrigonal pnictogen compound were synthesized by Arduengo and co-workers in 1984, through condensation of a diketoamine with a phosphorus trihalide in the presence of base. This group reported also on the first systematic investigations into its chemical behavior. Later, on similar routes, the corresponding and isostructural arsenic and antimony species were also synthesized. Other synthetic methods involve deprotonation of OH or NH groups in the presence of ECl (E=P, As, Sb and Bi), salt metathesis or reduction of pentavalent pnictogen compounds. | 0 | Theoretical and Fundamental Chemistry |
The silicon cycle has gained increasingly in scientific attention the past decade for several reasons:
Firstly, the modern marine silica cycle is widely believed to be dominated by diatoms for the fixation and export of particulate matter (including organic carbon), from the euphotic zone to the deep ocean, via a process known as the biological pump. As a result, diatoms, and other silica-secreting organisms, play a crucial role in the global carbon cycle, and have the ability to affect atmospheric CO concentrations on a variety of time scales, by sequestering CO in the ocean. This connection between biogenic silica and organic carbon, together with the significantly higher preservation potential of biogenic siliceous compounds, compared to organic carbon, makes opal accumulation records very interesting for paleoceanography and paleoclimatology.
Secondly, biogenic silica accumulation on the sea floor contains lot of information about where in the ocean export production has occurred on time scales ranging from hundreds to millions of years. For this reason, opal deposition records provide valuable information regarding large-scale oceanographic reorganizations in the geological past, as well as paleoproductivity.
Thirdly, the mean oceanic residence time for silicate is approximately 10,000–15,000 yr. This relative short residence time, makes oceanic silicate concentrations and fluxes sensitive to glacial/interglacial perturbations, and thus an excellent proxy for evaluating climate changes.
Increasingly, isotope ratios of oxygen (O:O) and silicon (Si:Si) are analysed from biogenic silica preserved in lake and marine sediments to derive records of past climate change and nutrient cycling (De La Rocha, 2006; Leng and Barker, 2006). This is a particularly valuable approach considering the role of diatoms in global carbon cycling. In addition, isotope analyses from BSi are useful for tracing past climate changes in regions such as in the Southern Ocean, where few biogenic carbonates are preserved. | 1 | Applied and Interdisciplinary Chemistry |
FMRFamide, a neuropeptide involved in cardiac activity regulation, is found in Biomphalaria glabrata, a species of a freshwater snail best known for its role as the intermediate host for the human-infecting trematode parasite Schistosoma mansoni.
This freshwater snail species is used as a model organism, in other words, a non-human species which is extensively studied to understand a biological phenomenon, with the expectation that discoveries made in the model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to research human disease when human experimentation would be unfeasible or unethical. | 1 | Applied and Interdisciplinary Chemistry |
Dioxane is used in a variety of applications as a versatile aprotic solvent, e. g. for inks, adhesives, and cellulose esters. It is substituted for tetrahydrofuran (THF) in some processes, because of its lower toxicity and higher boiling point (101 °C, versus 66 °C for THF).
While diethyl ether is rather insoluble in water, dioxane is miscible and in fact is hygroscopic. At standard pressure, the mixture of water and dioxane in the ratio 17.9:82.1 by mass is a positive azeotrope that boils at 87.6 C.
The oxygen atoms are weakly Lewis-basic. It forms adducts with a variety of Lewis acids. It is classified as a hard base and its base parameters in the ECW model are E =1.86 and C = 1.29.
Dioxane produces coordination polymers by linking metal centers. In this way, it is used to drive the Schlenk equilibrium, allowing the synthesis of dialkyl magnesium compounds. Dimethylmagnesium is prepared in this manner:
:2 CHMgBr + (CHO) → MgBr(CHO) + (CH)Mg | 0 | Theoretical and Fundamental Chemistry |
Cadmium sulfide is toxic, especially dangerous when inhaled as dust, and cadmium compounds in general are classified as carcinogenic. Problems of biocompatibility have been reported when CdS is used as colors in tattoos. CdS has an LD of approximately 7,080 mg/kg in rats - which is higher than other cadmium compounds due to its low solubility. | 0 | Theoretical and Fundamental Chemistry |
Tramadol is marketed as a racemic mixture of both R- and S-stereoisomers, because the two isomers complement each other's analgesic activities. The (+)-isomer is predominantly active as an opiate with a higher affinity for the µ-opiate receptor (20 times higher affinity than the (-)-isomer). | 0 | Theoretical and Fundamental Chemistry |
The classical piston theory is a powerful aerodynamic tool. From the use of the momentum equation and the assumption of isentropic perturbations, one obtains the following basic piston theory formula for the surface pressure:
where is the downwash speed and is the sound speed.
The surface is defined as
The slip velocity boundary condition leads to
The downwash speed is approximated as | 1 | Applied and Interdisciplinary Chemistry |
Redox zonation refers to how the processes that transfer terminal electrons as a result of organic matter degradation vary depending on time and space. Certain reactions will be favored over others due to their energy yield as detailed in the energy acceptor cascade detailed above. In oxic conditions, in which oxygen is readily available, aerobic respiration will be favored due to its high energy yield. Once the use of oxygen through respiration exceeds the input of oxygen due to bioturbation and diffusion, the environment will become anoxic and organic matter will be broken down via other means, such as denitrification and manganese reduction. | 0 | Theoretical and Fundamental Chemistry |
; (2017 June) – Second (Revised) Edition;
This book is a tribute to Pereras father, who served Sri Lankas Navy in its formative years (1950–1975) and founded the Naval and Maritime Academy (NMA) at Dockyard Trincomalee on 18 July 1967, serving as its first commandant. See under External links and the first Director Naval Training Sri Lanka Navy | 0 | Theoretical and Fundamental Chemistry |
With reference to the definitions, above, a magma chamber will tend to cool down and crystallize minerals according to the liquid line of descent. When this occurs, especially in conjunction with zonation and crystal accumulation, and the melt portion is removed, this can change the composition of a magma chamber. In fact, this is basically fractional crystallization, except in this case we are observing a magma chamber which is the remnant left behind from which a daughter melt has been extracted.
If such a magma chamber continues to cool, the minerals it forms and its overall composition will not match a sample liquid line of descent or a parental magma composition. | 0 | Theoretical and Fundamental Chemistry |
This detector is mostly used with alkali atoms, having a low ionization potential, with applications in mass spectrometry and atomic clocks. | 0 | Theoretical and Fundamental Chemistry |
There has been extensive research to discover treatment for DMD. The most common drug treated against DMD is known to be Deflazacort yielding the greatest benefits with the most acceptable side effects. Physical therapy consists of varying exercises that aim to increase muscle strength and durability so to facilitate normal physical activity and is recommended to begin as early as possible after diagnosis. Contracture intervention is recommended for patients in the middle ambulatory stage. However, surgical approach to DMD is declining as less invasive treatment becomes available. While treatment for DMD has been observed to improve muscle function and quality of life, a cure to the debilitating disease remains to be found. | 1 | Applied and Interdisciplinary Chemistry |
Racemic crystallography is a technique used in structural biology where crystals of a protein molecule are developed from an equimolar mixture of an L-protein molecule of natural chirality and its D-protein mirror image. L-protein molecules consist of left-handed L-amino acids and the achiral amino acid glycine, whereas the mirror image D-protein molecules consist of right-handed D-amino acids and glycine. Typically, both the L-protein and the D-protein are prepared by total chemical synthesis. | 0 | Theoretical and Fundamental Chemistry |
In recent years, NAD has also been recognized as an extracellular signaling molecule involved in cell-to-cell communication. NAD is released from neurons in blood vessels, urinary bladder, large intestine, from neurosecretory cells, and from brain synaptosomes, and is proposed to be a novel neurotransmitter that transmits information from nerves to effector cells in smooth muscle organs. In plants, the extracellular nicotinamide adenine dinucleotide induces resistance to pathogen infection and the first extracellular NAD receptor has been identified. Further studies are needed to determine the underlying mechanisms of its extracellular actions and their importance for human health and life processes in other organisms. | 0 | Theoretical and Fundamental Chemistry |
More recently, analytical closed-form solutions were found for the Rayleigh–Plesset equation for both an empty and gas-filled bubble and were generalized to the N-dimensional case. The case when the surface tension is present due to the effects of capillarity were also studied.
Also, for the special case where surface tension and viscosity are neglected, high-order analytical approximations are also known.
In the static case, the Rayleigh–Plesset equation simplifies, yielding the Young–Laplace equation:
When only infinitesimal periodic variations in the bubble radius and pressure are considered, the RP equation also yields the expression of the natural frequency of the bubble oscillation. | 1 | Applied and Interdisciplinary Chemistry |
A miniemulsion (also known as nanoemulsion) is a particular type of emulsion. A miniemulsion is obtained by shearing a mixture comprising two immiscible liquid phases (for example, oil and water), one or more surfactants and, possibly, one or more co-surfactants (typical examples are hexadecane or cetyl alcohol). They usually have nanodroplets with uniform size distribution (20–500 nm) and are also known as sub-micron, mini-, and ultra-fine grain emulsions. | 0 | Theoretical and Fundamental Chemistry |
*2020 David Anthony Worsley
*2019 J Bolton
*2018 I Samarasekera
*2017 J Speer
*2016 A W Cramb
*2015 John Beynon
*2014 H Tomono
*2013 Prince Philip, Duke of Edinburgh
*2013 K Mills
*2012 G Honeyman
*2011 I Christmas
*2010 M Sellars
*2009 G Arvedi
*2008 T Mukherjee
*2007 L Mittal
*2006 H Bhadeshia
*2005 S I Pettifor
*2004 R J Fruehan
*2003 J P Birat
*2002 R E Dolby | 1 | Applied and Interdisciplinary Chemistry |
Carbonation of ammonia is one step in the industrial production of urea:In 2020, worldwide production capacity was approximately 180 million tonnes. As a fertilizer, it is a source of nitrogen for plants.
Urea production plants are almost always located adjacent to the site where the ammonia is manufactured.
In the subsequent urea conversion: the ammonium carbamate is decomposed into urea, releasing water: | 0 | Theoretical and Fundamental Chemistry |
While the frequency of alterations of the RB gene is substantial for many human cancer types including as lung, esophageal, and liver, alterations in up-steam regulatory components of pRb such as CDK4 and CDK6 have been the main targets for potential therapeutics to treat cancers with dysregulation in the RB pathway. This focus has resulted in the recent development and FDA clinical approval of three small molecule CDK4/6 inhibitors (Palbociclib (IBRANCE, Pfizer Inc. 2015), Ribociclib (KISQUALI, Novartis. 2017), & Abemaciclib (VERZENIO, Eli Lilly. 2017)) for the treatment of specific breast cancer subtypes. However, recent clinical studies finding limited efficacy, high toxicity, and acquired resistance of these inhibitors suggests the need to further elucidate mechanisms that influence CDK4/6 activity as well as explore other potential targets downstream in the pRb pathway to reactivate pRb's tumor suppressive functions. Treatment of cancers by CDK4/6 inhibitors depends on the presence of pRb within the cell for therapeutic effect, limiting their usage only to cancers where RB is not mutated and pRb protein levels are not significantly depleted.
Direct pRb reactivation in humans has not been achieved. However, in murine models, novel genetic methods have allowed for in vivo pRb reactivation experiments. pRb loss induced in mice with oncogenic KRAS-driven tumors of lung adenocarcinoma negates the requirement of MAPK signal amplification for progression to carcinoma and promotes loss of lineage commitment as well as accelerate the acquisition of metastatic competency. Reactivation of pRb in these mice rescues the tumors towards a less metastatic state, but does not completely stop tumor growth due to a proposed rewiring of MAPK pathway signaling, which suppresses pRb through a CDK-dependent mechanism. | 1 | Applied and Interdisciplinary Chemistry |
Polymorphism in binary metal oxides has attracted much attention because these materials are of significant economic value. One set of famous examples have the composition SiO, which form many polymorphs. Important ones include: α-quartz, β-quartz, tridymite, cristobalite, moganite, coesite, and stishovite. | 0 | Theoretical and Fundamental Chemistry |
The Schumann–Runge bands are a set of absorption bands of molecular oxygen that occur at wavelengths between 176 and 192.6 nanometres. The bands are named for Victor Schumann and Carl Runge. | 0 | Theoretical and Fundamental Chemistry |
Mitochondrial replacement therapy (MRT), where the nuclear DNA is transferred to another healthy egg cell leaving the defective mitochondrial DNA behind, is an IVF treatment procedure. Using a similar pronuclear transfer technique, researchers at Newcastle University led by Douglass Turnbull successfully transplanted healthy DNA in human eggs from women with mitochondrial disease into the eggs of women donors who were unaffected. In such cases, ethical questions have been raised regarding biological motherhood, since the child receives genes and gene regulatory molecules from two different women. Using genetic engineering in attempts to produce babies free of mitochondrial disease is controversial in some circles and raises important ethical issues. A male baby was born in Mexico in 2016 from a mother with Leigh syndrome using MRT.
In September 2012 a public consultation was launched in the UK to explore the ethical issues involved. Human genetic engineering was used on a small scale to allow infertile women with genetic defects in their mitochondria to have children.
In June 2013, the United Kingdom government agreed to develop legislation that would legalize the three-person IVF procedure as a treatment to fix or eliminate mitochondrial diseases that are passed on from mother to child. The procedure could be offered from 29 October 2015 once regulations had been established.
Embryonic mitochondrial transplant and protofection have been proposed as a possible treatment for inherited mitochondrial disease, and allotopic expression of mitochondrial proteins as a radical treatment for mtDNA mutation load.
In June 2018 Australian Senates Senate Community Affairs References Committee recommended a move towards legalising Mitochondrial replacement therapy (MRT). Research and clinical applications of MRT were overseen by laws made by federal and state governments. State laws were, for the most part, consistent with federal law. In all states, legislation prohibited the use of MRT techniques in the clinic, and except for Western Australia, research on a limited range of MRT was permissible up to day 14 of embryo development, subject to a license being granted. In 2010, the Hon. Mark Butler MP, then Federal Minister for Mental Health and Ageing, had appointed an independent committee to review the two relevant acts: the Prohibition of Human Cloning for Reproduction Act 2002 and the Research Involving Human Embryos Act 2002. The committees report, released in July 2011, recommended the existing legislation remain unchanged
Currently, human clinical trials are underway at GenSight Biologics (ClinicalTrials.gov # NCT02064569) and the University of Miami (ClinicalTrials.gov # NCT02161380) to examine the safety and efficacy of mitochondrial gene therapy in Leber's hereditary optic neuropathy. | 1 | Applied and Interdisciplinary Chemistry |
It is possible to build a basic optical spectrometer using an optical disc grating and a basic webcam, using a CFL lamp for calibrating the wavelengths. A calibration using a source of known spectrum can then turn the spectrometer into a spectroradiometer by interpreting the brightness of photo pixels. A DIY build is affected by some extra error sources in the photo-to-value conversion: photographic noise (requiring dark frame subtraction) and non-linearity in the CCD-to-photograph conversion (possibly solved by a raw image format). | 0 | Theoretical and Fundamental Chemistry |
In 1951 Ivy Mike, part of Operation Ivy, became the first detonation of a thermonuclear weapon, yielding 10.4 megatons of TNT using liquid deuterium. Cousins and Ware built a toroidal pinch device in England and demonstrated that the plasma in pinch devices is inherently unstable. In 1953 The Soviet Union tested its RDS-6S test, (codenamed "Joe 4" in the US) demonstrated a fission/fusion/fission ("Layercake") design that yielded 600 kilotons. Igor Kurchatov spoke at Harwell on pinch devices, revealing that the USSR was working on fusion.
Seeking to generate electricity, Japan, France and Sweden all start fusion research programs
In 1955, John D. Lawson (scientist) creates what is now known as the Lawson criterion which is a criterion for a fusion reactor to produce more energy than is lost to the environment due to problems like Bremsstrahlung radiation.
In 1956 the Soviet Union began publishing articles on plasma physics, leading the US and UK to follow over the next several years.
The Sceptre III z-pinch plasma column remained stable for 300 to 400 microseconds, a dramatic improvement on previous efforts. The team calculated that the plasma had an electrical resistivity around 100 times that of copper, and was able to carry 200 kA of current for 500 microseconds. | 0 | Theoretical and Fundamental Chemistry |
In free-radical additions, a radical adds to a spin-paired substrate. When applied to organic compounds, the reaction usually entails addition to an alkene. This addition generates a new radical, which can add to yet another alkene, etc. This behavior underpins radical polymerization, technology that produces many plastics. | 1 | Applied and Interdisciplinary Chemistry |
Photolithographic methods are useful in patterning SAMs. SAMs are also useful in depositing nanostructures, because each adsorbate molecule can be tailored to attract two different materials. Current techniques utilize the head to attract to a surface, like a plate of gold. The terminal group is then modified to attract a specific material like a particular nanoparticle, wire, ribbon, or other nanostructure. In this way, wherever the SAM is patterned to a surface there will be nanostructures attached to the tail groups. One example is the use of two types of SAMs to align single wall carbon nanotubes, SWNTs. Dip pen nanolithography was used to pattern a 16-mercaptohexadecanoic acid (MHA)SAM and the rest of the surface was passivated with 1-octadecanethiol (ODT) SAM. The polar solvent that is carrying the SWNTs is attracted to the hydrophilic MHA; as the solvent evaporates, the SWNTs are close enough to the MHA SAM to attach to it due to Van der Waals forces. The nanotubes thus line up with the MHA-ODT boundary. Using this technique Chad Mirkin, Schatz and their co-workers were able to make complex two-dimensional shapes, a representation of a shape created is shown to the right.
Another application of patterned SAMs is the functionalization of biosensors. The tail groups can be modified so they have an affinity for cells, proteins, or molecules. The SAM can then be placed onto a biosensor so that binding of these molecules can be detected. The ability to pattern these SAMs allows them to be placed in configurations that increase sensitivity and do not damage or interfere with other components of the biosensor. | 0 | Theoretical and Fundamental Chemistry |
Stability of isotopes is affected by the ratio of protons to neutrons, and also by presence of certain magic numbers of neutrons or protons which represent closed and filled quantum shells. These quantum shells correspond to a set of energy levels within the shell model of the nucleus; filled shells, such as the filled shell of 50 protons for tin, confers unusual stability on the nuclide. As in the case of tin, a magic number for Z, the atomic number, tends to increase the number of stable isotopes for the element.
Just as in the case of electrons, which have the lowest energy state when they occur in pairs in a given orbital, nucleons (both protons and neutrons) exhibit a lower energy state when their number is even, rather than odd. This stability tends to prevent beta decay (in two steps) of many even–even nuclides into another even–even nuclide of the same mass number but lower energy (and of course with two more protons and two fewer neutrons), because decay proceeding one step at a time would have to pass through an odd–odd nuclide of higher energy. Such nuclei thus instead undergo double beta decay (or are theorized to do so) with half-lives several orders of magnitude larger than the age of the universe. This makes for a larger number of stable even–even nuclides, which account for 150 of the 251 total. Stable even–even nuclides number as many as three isobars for some mass numbers, and up to seven isotopes for some atomic numbers.
Conversely, of the 251 known stable nuclides, only five have both an odd number of protons and odd number of neutrons: hydrogen-2 (deuterium), lithium-6, boron-10, nitrogen-14, and tantalum-180m. Also, only four naturally occurring, radioactive odd–odd nuclides have a half-life over a billion years: potassium-40, vanadium-50, lanthanum-138, and lutetium-176. Odd–odd primordial nuclides are rare because most odd–odd nuclei are unstable with respect to beta decay, because the decay products are even–even, and are therefore more strongly bound, due to nuclear pairing effects.
Yet another effect of the instability of an odd number of either type of nucleons is that odd-numbered elements tend to have fewer stable isotopes. Of the 26 monoisotopic elements (those with only a single stable isotope), all but one have an odd atomic number, and all but one has an even number of neutrons—the single exception to both rules being beryllium.
The end of the stable elements in the periodic table occurs after lead, largely due to the fact that nuclei with 128 neutrons—two neutrons above the magic number 126—are extraordinarily unstable and almost immediately shed alpha particles. This also contributes to the very short half-lives of astatine, radon, and francium relative to heavier elements. A similar phenomenon occurs to a much lesser extent with 84 neutrons—two neutrons above the magic number 82—where various isotopes of elements in the lanthanide series exhibit alpha decay. | 0 | Theoretical and Fundamental Chemistry |
Soils with pH values that are higher than 7.3 are usually defined as being alkaline. These soils can occur naturally, due to the presence of alkali salts. Although many plants do prefer slightly basic soil (including vegetables like cabbage and fodder like buffalo grass), most plants prefer a mildly acidic soil (with pHs between 6.0 and 6.8), and alkaline soils can cause problems. | 0 | Theoretical and Fundamental Chemistry |
*The discovery of Camptothecin (1966) and Taxol (1971) at the Research Triangle Institute by Monroe E. Wall, Mansukh C. Wani, and colleagues
*Establishment of the Polymer Research Institute (now Polytechnic Institute of New York University) by Herman Mark in 1946, the first academic facility in the United States devoted to the study and teaching of polymer science
*Development of high-performance carbon fibers at Union Carbide Corporation (now GrafTech International) between 1958 and 1970 | 1 | Applied and Interdisciplinary Chemistry |
Solids such as stones, grit, and sand may be removed from wastewater by gravity when density differences are sufficient to overcome dispersion by turbulence. This is typically achieved using a grit channel designed to produce an optimum flow rate that allows grit to settle and other less-dense solids to be carried forward to the next treatment stage. Gravity separation of solids is the primary treatment of sewage, where the unit process is called "primary settling tanks" or "primary sedimentation tanks". It is also widely used for the treatment of other types of wastewater. Solids that are denser than water will accumulate at the bottom of quiescent settling basins. More complex clarifiers also have skimmers to simultaneously remove floating grease such as soap scum and solids such as feathers, wood chips, or condoms. Containers like the API oil-water separator are specifically designed to separate non-polar liquids. | 1 | Applied and Interdisciplinary Chemistry |
Enzymatic deficiency in alpha-oxidation (most frequently in phytanoyl-CoA dioxygenase) leads to Refsum's disease, in which the accumulation of phytanic acid and its derivatives leads to neurological damage. Other disorders of peroxisome biogenesis also prevent alpha-oxidation from occurring. | 1 | Applied and Interdisciplinary Chemistry |
In transportation infrastructure, a bidirectional traffic system divides travellers into two streams of traffic that flow in opposite directions.
In the design and construction of tunnels, bidirectional traffic can markedly affect ventilation considerations.
Microscopic traffic flow models have been proposed for bidirectional automobile, pedestrian, and railway traffic. Bidirectional traffic can be observed in ant trails which have been researched for insight into human traffic models. In a macroscopic theory proposed by Laval, the interaction between fast and slow vehicles conforms to the Newell kinematic wave model of moving bottlenecks.
In air traffic control traffic is normally separated by elevation, with east bound flights at odd thousand feet elevations and west bound flights at even thousand feet elevations (1000 ft ≈ 305m). Above 28,000 ft (~8.5 km) only odd flight levels are used, with FL 290, 330, 370, etc., for eastbound flights and FL 310, 350, 390, etc., for westbound flights. Entry to and exit from airports is always one-way traffic, as runways are chosen to allow aircraft to take off and land into the wind, to reduce ground speed. Even in no wind cases, a preferred calm wind runway and direction is normally chosen and used by all flights, to avoid collisions. In uncontrolled airports, airport information can be obtained from anyone at the airport. Traffic follows a specific traffic pattern, with designated entry and exits. Radio announcements are made, whether anyone is listening or not, to allow any other traffic to be aware of other traffic in the area.
In the earliest days of railways in the United Kingdom, most lines were built double tracked because of the difficulty of coordinating operations in pre-telegraphy times.
Most modern roads carry bidirectional traffic, although one-way traffic is common in dense urban centres. Bidirectional traffic flow is believed to influence the rate of traffic collisions. In an analysis of head-on, rear-end, and lane-changing collisions based on the Simon-Gutowitz bidirectional traffic model, it was concluded that "the risk of collisions is important when the density of cars in one lane is small and ... the other lane['s] is high enough," and that "heavy vehicles cause an important reduction of traffic flow on the home lane and provoke an increase of the risk of car accident."
Bidirectional traffic is the most common form of flow observed in trails, however, some larger pedestrian concourses exhibit multidirectional traffic. | 0 | Theoretical and Fundamental Chemistry |
In 1975, Draper's house, known as the Henry Draper Observatory, in Hastings was designated a National Historic Landmark.
In 1976, New York University founded the John W. Draper Interdisciplinary Master's Program in Humanities and Social Thought (Draper Program) in honor of his lifelong commitment to interdisciplinary study.
In 2001, Draper and the founding of the American Chemical Society were designated a National Historic Chemical Landmark at New York University. | 0 | Theoretical and Fundamental Chemistry |
Plant and fungal cells are also electrically excitable. The fundamental difference from animal action potentials is that the depolarization in plant cells is not accomplished by an uptake of positive sodium ions, but by release of negative chloride ions. In 1906, J. C. Bose published the first measurements of action potentials in plants, which had previously been discovered by Burdon-Sanderson and Darwin. An increase in cytoplasmic calcium ions may be the cause of anion release into the cell. This makes calcium a precursor to ion movements, such as the influx of negative chloride ions and efflux of positive potassium ions, as seen in barley leaves.
The initial influx of calcium ions also poses a small cellular depolarization, causing the voltage-gated ion channels to open and allowing full depolarization to be propagated by chloride ions.
Some plants (e.g. Dionaea muscipula) use sodium-gated channels to operate movements and essentially "count". Dionaea muscipula, also known as the Venus flytrap, is found in subtropical wetlands in North and South Carolina. When there are poor soil nutrients, the flytrap relies on a diet of insects and animals. Despite research on the plant, there lacks an understanding behind the molecular basis to the Venus flytraps, and carnivore plants in general.
However, plenty of research has been done on action potentials and how they affect movement and clockwork within the Venus flytrap. To start, the resting membrane potential of the Venus flytrap (-120mV) is lower than animal cells (usually -90mV to -40mV). The lower resting potential makes it easier to activate an action potential. Thus, when an insect lands on the trap of the plant, it triggers a hair-like mechanoreceptor. This receptor then activates an action potential which lasts around 1.5 ms. Ultimately, this causes an increase of positive Calcium ions into the cell, slightly depolarizing it.
However, the flytrap does not close after one trigger. Instead, it requires the activation of 2 or more hairs. If only one hair is triggered, it throws the activation as a false positive. Further, the second hair must be activated within a certain time interval (0.75 s - 40 s) for it to register with the first activation. Thus, a buildup of calcium starts and slowly falls from the first trigger. When the second action potential is fired within the time interval, it reaches the Calcium threshold to depolarize the cell, closing the trap on the prey within a fraction of a second.
Together with the subsequent release of positive potassium ions the action potential in plants involves an osmotic loss of salt (KCl). Whereas, the animal action potential is osmotically neutral because equal amounts of entering sodium and leaving potassium cancel each other osmotically. The interaction of electrical and osmotic relations in plant cells appears to have arisen from an osmotic function of electrical excitability in a common unicellular ancestors of plants and animals under changing salinity conditions. Further, the present function of rapid signal transmission is seen as a newer accomplishment of metazoan cells in a more stable osmotic environment. It is likely that the familiar signaling function of action potentials in some vascular plants (e.g. Mimosa pudica) arose independently from that in metazoan excitable cells.
Unlike the rising phase and peak, the falling phase and after-hyperpolarization seem to depend primarily on cations that are not calcium. To initiate repolarization, the cell requires movement of potassium out of the cell through passive transportation on the membrane. This differs from neurons because the movement of potassium does not dominate the decrease in membrane potential; In fact, to fully repolarize, a plant cell requires energy in the form of ATP to assist in the release of hydrogen from the cell – utilizing a transporter commonly known as H+-ATPase. | 0 | Theoretical and Fundamental Chemistry |
Dispersants are used to prevent formation of biofouling or biofilms in industrial processes. It is also possible to disperse bacterial slime and increase the efficiency of biocides. | 0 | Theoretical and Fundamental Chemistry |
Bismuth vanadate is a visible-light-driven photocatalyst with a bandgap of 2.4 eV. BV have demonstrated efficiencies of 5.2% for flat thin films and 8.2% for core-shell WO@BiVO nanorods with thin absorbers. | 0 | Theoretical and Fundamental Chemistry |
Successive stepwise formation constants K in a series such as ML (n = 1, 2, ...) usually decrease as n increases. Exceptions to this rule occur when the geometry of the ML complexes is not the same for all members of the series. The classic example is the formation of the diamminesilver(I) complex [Ag(NH)] in aqueous solution.
In this case, K > K. The reason for this is that, in aqueous solution, the ion written as Ag actually exists as the four-coordinate tetrahedral aqua species [Ag(HO)]. The first step is then a substitution reaction involving the displacement of a bound water molecule by ammonia forming the tetrahedral complex [Ag(NH)(HO)]. In the second step, all the aqua ligands are lost and a linear, two-coordinate product [HN–Ag–NH] is formed. Examination of the thermodynamic data shows that the difference in entropy change is the main contributor to the difference in stability constants for the two complexation reactions.
Other examples exist where the change is from octahedral to tetrahedral, as in the formation of [CoCl] from [Co(HO)]. | 0 | Theoretical and Fundamental Chemistry |
In cyclohexane, the two chair conformations have the same energy. The situation becomes more complex with substituted derivatives. | 0 | Theoretical and Fundamental Chemistry |
If the model is not acceptable, a variety of other models should be examined to find one that best fits the experimental data, within experimental error. The main difficulty is with the so-called minor species. These are species whose concentration is so low that the effect on the measured quantity is at or below the level of error in the experimental measurement. The constant for a minor species may prove impossible to determine if there is no means to increase the concentration of the species. | 0 | Theoretical and Fundamental Chemistry |
Throughout this sub-section, as in the previous one, the two ends of the polymer are attached to a micro-manipulation device. This time, however, the device does not maintain the two ends of the ideal chain in a fixed position, but rather it maintains a constant pulling force on the ideal chain. In this case the two ends of the polymer fluctuate around a mean position . The ideal chain reacts with a constant opposite force .
For an ideal chain exchanging length with a reservoir, a macro-state of the system is characterized by the vector .
The change between an ideal chain of fixed length and an ideal chain in contact with a length reservoir is very much akin to the change between the micro-canonical ensemble and the canonical ensemble (see the Statistical mechanics article about this). The change is from a state where a fixed value is imposed on a certain parameter, to a state where the system is left free to exchange this parameter with the outside. The parameter in question is energy for the microcanonical and canonical descriptions, whereas in the case of the ideal chain the parameter is the length of the ideal chain.
As in the micro-canonical and canonical ensembles, the two descriptions of the ideal chain differ only in the way they treat the system's fluctuations. They are thus equivalent at the thermodynamic limit. The equation of state of the ideal chain remains the same, except that is now subject to fluctuations: | 0 | Theoretical and Fundamental Chemistry |
N1-methyladenosine is a modified nucleoside in which a methyl group is added to N1 of the adenosine base. This modification introduces a positive charge on the nitrogen atom to which the methyl group is added, because the modified nitrogen donates its lone pair to the carbon atom of the methyl group in order to form a bond. N1-methyladenosine modification is thought to regulate tRNA and rRNA stability, as well as potentially alter protein-RNA interactions or RNA secondary structures. This modification results in the melting of double-stranded RNA, due to alterations in the RNA structure. The N1-methyladenosine modification is less common than the mA modification, with modified transcripts usually only containing a single mA modification, whereas they may contain several mA residues.
Studies of these modifications have been slow to advance due to a lack of sound methodology to locate and identify them. A few methods, such as MeRIP-seq and mA-ID-seq, have been developed, but the particular adenosine that is modified still cannot be identified. A computational tool based on the data generated from these methods called RAMPed has been developed to try to identify these particular modifications.
Disease
Modification of m1a is of interest regarding its considerable correlation with cancer biology and tumorigenesis. Involvement of m1a may be organized under the categories of proliferation, invasion, cell death, tumor microenvironment, or cancer metabolism. Cancer cell proliferation has been found to be promoted by specific m1a “writers”. For example, the regulator TRMT6 has been found to be overexpressed in individuals with glioma, a cancer marked by the inappropriate proliferation of glial cells of the brain or spinal cord. Additionally, regulation of ALKBH3 has been found to support and bolster cancer cell invasiveness in certain breast and ovarian cancers. | 1 | Applied and Interdisciplinary Chemistry |
The Hedgehog Signaling pathway is critical in proper tissue patterning and orientation during normal development of most animals. Hedgehog proteins induce cell proliferation in certain cells and differentiations in others. Aberrant activation of the Hedgehog pathway has been implicated in several types of cancers, Basal Cell Carcinoma in particular. This uncontrolled activation of the Hedgehog proteins can be caused by mutations to the signal pathway, which would be ligand independent, or a mutation that causes overexpression of the Hedgehog protein, which would be ligand dependent. In addition, therapy-induced Hedgehog pathway activation has been shown to be necessary for progression of Prostate Cancer tumors after androgen deprivation therapy. This connection between the Hedgehog signaling pathway and human cancers may provide for the possible of therapeutic intervention as treatment for such cancers. The Hedgehog signaling pathway is also involved in normal regulation of stem-cell populations, and required for normal growth and regeneration of damaged organs. This may provide another possible route for tumorigenesis via the Hedgehog pathway. | 1 | Applied and Interdisciplinary Chemistry |
Pewter was first used around the beginning of the Bronze Age in the Near East. The earliest known piece of pewter was found in an Egyptian tomb, , but it is unlikely that this was the first use of the material. Pewter was used for decorative metal items and tableware in ancient times by the Egyptians and later the Romans, and came into extensive use in Europe from the Middle Ages until the various developments in pottery and glass-making during the 18th and 19th centuries. Pewter was the chief material for producing plates, cups, and bowls until the making of porcelain. Mass production of pottery, porcelain and glass products have almost universally replaced pewter in daily life, although pewter artifacts continue to be produced, mainly as decorative or specialty items. Pewter was also used around East Asia. Although some items still exist, Ancient Roman pewter is rare.
Lidless mugs and lidded tankards may be the most familiar pewter artifacts from the late 17th and 18th centuries, although the metal was also used for many other items including porringers (shallow bowls), plates, dishes, basins, spoons, measures, flagons, communion cups, teapots, sugar bowls, beer steins (tankards), and cream jugs. In the early 19th century, changes in fashion caused a decline in the use of pewter flatware. At the same time, production increased of both cast and spun pewter tea sets, whale-oil lamps, candlesticks, and so on. Later in the century, pewter alloys were often used as a base metal for silver-plated objects.
In the late 19th century, pewter came back into fashion with the revival of medieval objects for decoration. New replicas of medieval pewter objects were created, and collected for decoration. Today, pewter is used in decorative objects, mainly collectible statuettes and figurines, game figures, aircraft and other models, (replica) coins, pendants, plated jewellery and so on. Certain athletic contests, such as the United States Figure Skating Championships, award pewter medals to fourth-place finishers. | 1 | Applied and Interdisciplinary Chemistry |
McTaggarts plasma research led to patents as assignor to the CSIRO, including US 3,533,777 Production of metals from their halides' filed 2 Nov. 1966 for an apparatus and process for producing metals from the halides of metals of Groups I, II, III of the Periodic table and rare earth metals. It consisted of means to generate a plasma through high frequency electromagnetic energy within a gas or a vapor of that halide to cause the halide to dissociate, and then separating the metal thus produced from the other dissociation products, a process in which an auxiliary gas, hydrogen, helium or nitrogen, may also be used in conjunction with the halide.
He filed another patent on 5 Sept. 1967 for Plasma sintering with Neil Mckinnon, C.E.G. Bennet and Lloyd S. Williams, which was issued 11 March 1969. | 0 | Theoretical and Fundamental Chemistry |
GCN2 (encoded in humans by the gene EIF2AK4) is activated as a result of amino acid deprivation. The mechanisms regarding this activation are still being researched; however, one mechanism has been studied in yeast. It was observed that GCN2 binds to uncharged/deacylated tRNA which causes a conformational change, resulting in dimerization. Dimerization then causes autophosphorylation and activation. Other stressors have also been reported to activate GCN2. GCN2 activation was observed in glucose deprived tumor cells, although it was suggested that it was an indirect effect due to cells using amino acids as an alternate energy source. In mouse embryonic fibroblast cells and human keratinocytes, GCN2 was activated due to UV light exposure. The pathways for this activation require further research, although multiple models have been proposed, including crosslinking between GCN2 and tRNA. | 1 | Applied and Interdisciplinary Chemistry |
In vivo gene electrotransfer was first described in 1991 and today there are many preclinical studies of gene electrotransfer. The method is used to deliver large variety of therapeutic genes for potential treatment of several diseases, such as: disorders in immune system, tumors, metabolic disorders, monogenetic diseases, cardiovascular diseases, analgesia....
With regards to irreversible electroporation, the first successful treatment of malignant cutaneous tumors implanted in mice was completed in 2007 by a group of scientists who achieved complete tumor ablation in 12 out of 13 mice. They accomplished this by sending 80 pulses of 100 microseconds at 0.3 Hz with an electrical field magnitude of 2500 V/cm to treat the cutaneous tumors. Currently, a number of companies, including AngioDynamics, Inc. and VoltMed, Inc., are continuing to develop and deploy irreversible electroporation-based technologies within clinical environments.
The first group to look at electroporation for medical applications was led by Lluis M Mir at the Institute Gustave Roussy. In this case, they looked at the use of reversible electroporation in conjunction with impermeable macromolecules. The first research looking at how nanosecond pulses might be used on human cells was conducted by researchers at Eastern Virginia Medical School and Old Dominion University, and published in 2003. | 1 | Applied and Interdisciplinary Chemistry |
Mechanisms for C-H activations by metal centers can be classified into three general categories:
*(i) Oxidative addition, in which a low-valent metal center inserts into a carbon-hydrogen bond, which cleaves the bond and oxidizes the metal:
:LM + RH → LMR(H)
*(ii) Electrophilic activation in which an electrophilic metal attacks the hydrocarbon, displacing a proton:
:LM + RH → LMR + H
*(iii) Sigma-bond metathesis, which proceeds through a "four-centered" transition state in which bonds break and form in a single step:
:LMX + RH → LMR + XH | 0 | Theoretical and Fundamental Chemistry |
Paytan is both an interdisciplinary scientist and an advocate for STEM education and public outreach. As a scientist, Paytan uses isotopic and chemical signatures to examine global biogeochemical cycling. This includes studies of groundwater discharge into coastal systems, nutrient cycling, ocean acidification, and paleoceanography. This research includes high resolution measurements of carbon and sulfur isotopes to characterize changes in the marine and atmospheric carbon cycle, using strontium isotopes within barite to infer changes in the global carbon cycle over geologic time, and modern investigations of groundwater discharge as a source of nutrients to the coastal ocean and coral reefs.
Paytan also deliberately works on STEM education and public outreach, and obtained an M.S. in Science Education from the Weizmann Institute in 1987. Paytan served as a mentor for the Centers for Ocean Sciences Education Excellence (COSEE) where she advocated for the role of universities in conducting public outreach. Paytan started the GeoKids program at Stanford in order to educate elementary school children about science. Paytan also mentors masters and Ph.D. students in her lab. | 0 | Theoretical and Fundamental Chemistry |
M2-PK, as measured in feces, is a potential tumor marker for colorectal cancer. When measured in feces with a cutoff value of 4 U/ml, its sensitivity has been estimated to be 85% (with a 95% confidence interval of 65 to 96%) for colon cancer and 56% (confidence interval 41–74%) for rectal cancer. Its specificity is 95%.
The M2-PK test is not dependent on occult blood (ELISA method), so it can detect bleeding or non-bleeding bowel cancer and also polyps with high sensitivity and high specificity with no false negative, but false positives may occur.
Most people are more willing to accept non-invasive preventive medical check-ups. Therefore, the measurement of tumor M2-PK in stool samples, with follow-up by colonoscopy to clarify the tumor M2-PK positive results, may prove to be an advance in the early detection of colorectal carcinomas. The CE marked M2-PK Test is available in form of an ELISA test for quantitative results or as point of care test to receive results within minutes.
Tumor M2-PK is also useful to diagnose lung cancer and better than SCC and NSE tumor markers. With renal cell carcinoma (RCC), the M2PK test has sensitivity of 66.7 percent for metastatic RCC and 27.5 percent for nonmetastatic RCC, but M2PK test cannot detect transitional cell carcinoma of the bladder, prostate cancer and benign prostatic hyperplasia. | 1 | Applied and Interdisciplinary Chemistry |
Aryl alkynes are typically made utilizing the Sonogashira reaction which is the palladium catalyzed cross-coupling reaction of terminal alkynes and aryl halides. Instead of the terminal alkynes, alkyne carboxylic acids has advantages, easy handling and storage. The first decarboxylative coupling of alkyne carboxylic acids was reported in 2008 by S. Lee. They employed propiolic acid as an alkyne source. One year later, S. Lee applied the decarboxylative coupling reactions toward 2-octynoic acid and phenylpropiolic acid. In 2010, Xue et al. reported the coupling of an aryl halide and alkynyl carboxylic acid under mild reactions conditions and a copper-only catalyst to obtain aryl alkynes. | 0 | Theoretical and Fundamental Chemistry |
Thermally enclosed spaces, including automobiles and greenhouses, are particularly susceptible to harmful temperature increases, especially during extreme weather. This is because of the heavy presence of windows, which are act as "transparent" to incoming solar radiation yet "opaque" to outgoing long-wave thermal radiation, which causes them to heat rapidly. The temperature of an automobile in direct sunlight can rise to 60–82ᵒC when ambient temperatures is only 21ᵒC. This accumulation of heat "can cause heat stroke and hyperthermia in the occupants, especially children", which can be alleviated with passive radiative cooling. | 0 | Theoretical and Fundamental Chemistry |
The synthesized laminin–111 formed in an embryo contributes to the formation of Reichert’s membrane, a thick extra-embryonic basement membrane. When the laminin α1 chain is deficient in an organism, an embryo dies, likely as a result of a defective Reichert’s membrane due to a lack of laminin–111 being produced. Laminin-111 has been identified as a crucial molecule for development of the embryo as shown by the consequences that occur when laminin-111 is lacking.
Laminin-111 is expressed very early on in development and is present in the blastocyst. When various parts of the trimer chains are knocked out by mutations, devastating consequences occur in the embryo. If the β1 or γ1 chains of laminin-111 are absent the basement membrane fails to form. Without a basement membrane cells have nowhere to attach and all dependent activities such as cell migration and epithelial formation can no longer occur. The self-assembly and tight network formation by laminin-111 are essential for holding the basement membrane together.
Although it is expressed abundantly during the early embryonic stage, laminin-111 is mostly absent in adults. The injection of laminin-111, however, helps with Duchenne muscular dystrophy, a neuromuscular disease in which the connection between the extracellular matrix and cell cytoskeleton is lost. Increased levels of laminin-111 triggered an increase in the expression of α7-integrin receptor and this prevented onset of the disease. Additionally, the presence of laminin-111 increased muscle strength and protected it from injury. When injected with myoblast transplants, laminin–111 decreased degeneration and inflammatory reactions and increased the success of the transplantation. The experiments utilizing laminin–111 as a source of therapy for Duchenne muscular dystrophy suggest that it has protective qualities in addition to its association with muscle tissue. | 0 | Theoretical and Fundamental Chemistry |
Minimotif Miner is a program and database designed to identify minimotifs in any protein. Minimotifs are short, contiguous peptide sequences that are known to have a function in at least one protein. Minimotifs are also called sequence motifs or short linear motifs or SLiMs. These are generally restricted to one secondary structure element and are less than 15 amino acids in length. | 1 | Applied and Interdisciplinary Chemistry |
Excitatory amino acid receptor ligands are ligands of excitatory amino acid receptors (EAARs), also known as glutamate receptors. They include excitatory amino acid receptor agonists and excitatory amino acid receptor antagonists. | 1 | Applied and Interdisciplinary Chemistry |
Because it is biologically inert and chemically stable, perfluorohexane has attracted attention in medicine. Like other fluorocarbons, perfluorohexane dissolves gases, including oxygen from the air, to a higher concentration than ordinary organic solvents. This effect is attributed to the weak intermolecular forces between perfluorohexane molecules, which allows "space" for gas molecules to partition into the liquid. Animals can be submerged in a bath of oxygenated perfluorohexane without drowning, as there is sufficient oxygen available in the solvent to allow respiration to continue. This effect has led to the experimental use of perfluorohexane in treating burn victims, as their lungs can be filled with either perfluorohexane vapor or in extreme cases liquid perfluorohexane, allowing breathing to continue without the problems normally seen with pulmonary edema that sometimes occur when the inside of the lungs have been burnt e.g. by inhalation of hot smoke. Research was particularly active on the topic of partial liquid ventilation (PLV) in the 1990s and early 2000s, however, perfluorohexane and other perfluorocarbons showed no significant improvement of patient outcomes in clinical trials. | 1 | Applied and Interdisciplinary Chemistry |
There has been some inaccuracies of the SFT caused by the differences in the basicity of the nitrogen in different amino acids which were explained by S. L. Jodidi. For instances, proline(an amino acid), histidine, and lysine yields too low values compared to the theory. Unlike alpha, monobasic (containing one amino group per molecule) amino acids, these amino (or imino) acids' nitrogens have inconstant basicity, which results in partial reaction with formaldehyde.
In case of tyrosine, the actual results are too high due to the negative hydroxyl group (-OH), which acts as a base. This explanation is supported by the fact that phenylalanine can be accurately titrated. | 1 | Applied and Interdisciplinary Chemistry |
When handled improperly, or if manufactured defectively, some rechargeable batteries can experience thermal runaway resulting in overheating. Sealed cells will sometimes explode violently if safety vents are overwhelmed or nonfunctional. Especially prone to thermal runaway are lithium-ion batteries, most markedly in the form of the lithium polymer battery. Reports of exploding cellphones occasionally appear in newspapers. In 2006, batteries from Apple, HP, Toshiba, Lenovo, Dell and other notebook manufacturers were recalled because of fire and explosions. The Pipeline and Hazardous Materials Safety Administration (PHMSA) of the U.S. Department of Transportation has established regulations regarding the carrying of certain types of batteries on airplanes because of their instability in certain situations. This action was partially inspired by a cargo bay fire on a FedEx airplane.
One of the possible solutions is in using safer and less reactive anode (lithium titanates) and cathode (lithium iron phosphate) materials — thereby avoiding the cobalt electrodes in many lithium rechargeable cells — together with non-flammable electrolytes based on ionic liquids. | 1 | Applied and Interdisciplinary Chemistry |
Individuals with certain genetic variations of CYP2D6 enzymes, which convert tramadol into an inactive molecule, may not experience enough pain relief from tramadol. These genetic polymorphisms are not currently routinely tested for in clinical practice. | 0 | Theoretical and Fundamental Chemistry |
1,1-Dichloro-1-fluoroethane is mainly used as a solvent and foam blowing agent under the names R-141b and HCFC-141b. It is a class 2 ozone depleting substance undergoing a global phaseout from production and use under the Montreal Protocol since the late 1990s. It is being replaced by HFCs within some applications. | 1 | Applied and Interdisciplinary Chemistry |
Typical indicators for the evaluation of the ecological quality are the abundances of fish, macrozoobenthos, macrophytes and phytobenthos, and the number of type-specific taxa. Criteria to further classify the ecological status of river sections can be found in the European Directive or in country-specific guidelines. | 1 | Applied and Interdisciplinary Chemistry |
Omar M. Yaghi and William A. Goddard III also reported COFs as exceptional methane storage materials. The best COF in terms of total volume of CH per unit volume COF adsorbent is COF-1, which can store 195 v/v at 298 K and 30 bar, exceeding the U.S. Department of Energy target for CH storage of 180 v/v at 298 K and 35 bar. The best COFs on a delivery amount basis (volume adsorbed from 5 to 100 bar) are COF-102 and COF-103 with values of 230 and 234 v(STP: 298 K, 1.01 bar)/v, respectively, making these promising materials for practical methane storage. More recently, new COFs with better delivery amount have been designed in the lab of William A. Goddard III, and they have been shown to be stable and overcome the DOE target in delivery basis. COF-103-Eth-trans and COF-102-Ant, are found to exceed the DOE target of 180 v(STP)/v at 35 bar for methane storage. They reported that using thin vinyl bridging groups aids performance by minimizing the interaction methane-COF at low pressure. | 0 | Theoretical and Fundamental Chemistry |
By the end of the war in 1944, post war recovery started: Alain Bertons work on the application of absorption and emission spectroscopy in the ultraviolet and infrared, and within the frame of concerns about labor force protection, the specific dosage of atmospheric pollutants became of vital interest in factories to effectively detect and remedy industrial pollution. Thus, in the 1950s, based on the method of gas chromatography analysis by low temperature followed by pyrolysis, he managed to isolate chlorinated substances and acid vapors components in the air. He was able to individualize traces of gas and vapors by using ultra-sensitive galvanic batteries and galvanic microcell detectors. He presented his research in the preamble to the convention of the Analytical Chemistry Group in 1958. Alain Berton named his invention "the Osmopile," later nicknamed "the sniffing cells" by the scientific journal Atomes'. The first "artificial nose" was thus born. His invention was adopted and developed in the US and went around the world with a report from the Associated Press dated December 8, 1958.
Berton’s Osmopile was marketed by Jouan, a laboratory equipment manufacturer founded in the 1940s by a researcher from the Pasteur Institute and acquired in 2003 by Thermo Electron. The Osmopile device was modernized over time and used in the fight against industrial pollution.
Through his invention, Alain Berton proved to be an ecology pioneer. | 0 | Theoretical and Fundamental Chemistry |
Human domination of the biosphere has threatened global biodiversity, with uncertain consequences for ecosystems that provide food, clean air and water, and other valuable ecosystem services. Understanding the impacts of biodiversity loss on ecosystem function requires knowledge of the interactions between organisms within both the same and different positions in a food web (i.e. trophic levels). Food webs can have very complex structures. In many ecosystems, organisms at trophic levels higher than herbivores consume a variable combination of prey and producers, exhibiting different forms of omnivory. The loss of predator species can have a cascading effect on all organisms at lower trophic levels. Networks with more omnivores that consume species at multiple trophic levels may be more resilient to these top-down effects. Together, these factors demonstrate that a food web's structure affects its sensitivity to reductions in biodiversity, highlighting the importance of food web studies. Amino acid isotopes are an important tool used in this field.
The abundance of N in some amino acids reflects an organisms position in a food web. This is due to the ways organisms metabolize different amino acids when they are consumed. Trophic amino acids (TrAAs) are first deaminated, meaning that the amino group is removed to produce an alpha-keto acid carbon skeleton. This reaction breaks a C-N bond, causing the amino acid to become more enriched in N due to a kinetic isotope effect. For instance, glutamate, a representative TrAA, has a δN value that increases by 8‰ with each trophic level. In contrast, the first reaction in the metabolism of source amino acids (SrcAAs) is not deamination. An example is phenylalanine, with is first converted to tyrosine in a reaction that breaks no C-N bonds. Thus, there is little variation in the δN values of SrcAAs between trophic levels. Their isotopic composition instead resembles that of the species at the base of the food web. Though these trends are conflated by some environmental effects, they have been used to infer an organisms trophic position. | 0 | Theoretical and Fundamental Chemistry |
LAP proteins are expressed in a variety of marine organisms as a method of coping with the osmotic threat high salinity poses to the cell. During bouts of high salinity, LAP begins the catalysis of proteins in order to release amino acids into the cell in an attempt to balance the high ion concentrations in the external environment. | 1 | Applied and Interdisciplinary Chemistry |
During induced fission, a compound system is formed after an incident particle fuses with a target. The resultant excitation energy may be sufficient to emit neutrons, or gamma-rays, and nuclear scission. Fission into two fragments, binary fission, is the most common nuclear reaction. Occurring least frequently is ternary fission, in which a third particle is emitted. This third particle is commonly an α particle. Since in nuclear fission, the nucleus emits more neutrons than the one it absorbs, a chain reaction is possible.
Binary fission may produce any of the fission products, at 95±15 and 135±15 daltons. However, the binary process happens merely because it is the most probable. In anywhere from two to four fissions per 1000 in a nuclear reactor, ternary fission can produce three positively charged fragments (plus neutrons) and the smallest of these may range from so small a charge and mass as a proton (Z = 1), to as large a fragment as argon (Z = 18). The most common small fragments, however, are composed of 90% helium-4 nuclei with more energy than alpha particles from alpha decay (so-called "long range alphas" at ~16 megaelectronvolts (MeV)), plus helium-6 nuclei, and tritons (the nuclei of tritium). Though less common than binary fission, it still produces significant helium-4 and tritium gas buildup in the fuel rods of modern nuclear reactors.
Bohr and Wheeler used their liquid drop model, the packing fraction curve of Arthur Jeffrey Dempster, and Eugene Feenbergs estimates of nucleus radius and surface tension, to estimate the mass differences of parent and daughters in fission. They then equated this mass difference to energy using Einsteins mass-energy equivalence formula. The stimulation of the nucleus after neutron bombardment was analogous to the vibrations of a liquid drop, with surface tension and the Coulomb force in opposition. Plotting the sum of these two energies as a function of elongated shape, they determined the resultant energy surface had a saddle shape. The saddle provided an energy barrier called the critical energy barrier. Energy of about 6 MeV provided by the incident neutron was necessary to overcome this barrier and cause the nucleus to fission. According to John Lilley, "The energy required to overcome the barrier to fission is called the activation energy or fission barrier and is about 6 MeV for A ≈ 240. It is found that the activation energy decreases as A increases. Eventually, a point is reached where activation energy disappears altogether...it would undergo very rapid spontaneous fission."
Maria Goeppert Mayer later proposed the nuclear shell model for the nucleus. The nuclides that can sustain a fission chain reaction are suitable for use as nuclear fuels. The most common nuclear fuels are U (the isotope of uranium with mass number 235 and of use in nuclear reactors) and Pu (the isotope of plutonium with mass number 239). These fuels break apart into a bimodal range of chemical elements with atomic masses centering near 95 and 135 daltons (fission products). Most nuclear fuels undergo spontaneous fission only very slowly, decaying instead mainly via an alpha-beta decay chain over periods of millennia to eons. In a nuclear reactor or nuclear weapon, the overwhelming majority of fission events are induced by bombardment with another particle, a neutron, which is itself produced by prior fission events.
Fissionable isotopes such as uranium-238 require additional energy provided by fast neutrons (such as those produced by nuclear fusion in thermonuclear weapons). While some of the neutrons released from the fission of are fast enough to induce another fission in , most are not, meaning it can never achieve criticality. While there is a very small (albeit nonzero) chance of a thermal neutron inducing fission in , neutron absorption is orders of magnitude more likely. | 0 | Theoretical and Fundamental Chemistry |
A colloidal crystal is a highly ordered array of particles that forms over a long range (from a few millimeters to one centimeter in length); colloidal crystals have appearance and properties roughly analogous to their atomic or molecular counterparts. It has been known for many years that, due to repulsive Coulombic interactions, electrically charged macromolecules in an aqueous environment can exhibit long-range crystal-like correlations, with interparticle separation distances often being considerably greater than the individual particle diameter. Periodic arrays of spherical particles give rise to interstitial voids (the spaces between the particles), which act as a natural diffraction grating for visible light waves, when the interstitial spacing is of the same order of magnitude as the incident lightwave. In these cases brilliant iridescence (or play of colours) is attributed to the diffraction and constructive interference of visible lightwaves according to Bragg's law, in a matter analogous to the scattering of X-rays in crystalline solid. The effects occur at visible wavelengths because the interplanar spacing is much larger than for true crystals. Precious opal is one example of a colloidal crystal with optical effects. | 0 | Theoretical and Fundamental Chemistry |
Sodium hydroxide is also widely used in pulping of wood for making paper or regenerated fibers. Along with sodium sulfide, sodium hydroxide is a key component of the white liquor solution used to separate lignin from cellulose fibers in the kraft process. It also plays a key role in several later stages of the process of bleaching the brown pulp resulting from the pulping process. These stages include oxygen delignification, oxidative extraction, and simple extraction, all of which require a strong alkaline environment with a pH > 10.5 at the end of the stages. | 0 | Theoretical and Fundamental Chemistry |
Superfluid vacuum theory (SVT) is an approach in theoretical physics and quantum mechanics where the physical vacuum is viewed as superfluid.
The ultimate goal of the approach is to develop scientific models that unify quantum mechanics (describing three of the four known fundamental interactions) with gravity. This makes SVT a candidate for the theory of quantum gravity and an extension of the Standard Model.
It is hoped that development of such a theory would unify into a single consistent model of all fundamental interactions,
and to describe all known interactions and elementary particles as different manifestations of the same entity, superfluid vacuum.
On the macro-scale a larger similar phenomenon has been suggested as happening in the murmurations of starlings. The rapidity of change in flight patterns mimics the phase change leading to superfluidity in some liquid states.
Light behaves like a superfluid in various applications such as Poisson's Spot. As the liquid helium shown above, light will travel along the surface of an obstacle before continuing along its trajectory. Since light is not affected by local gravity its "level" becomes its own trajectory and velocity. Another example is how a beam of light travels through the hole of an aperture and along its backside before diffraction. | 0 | Theoretical and Fundamental Chemistry |
Actively expressed genes have open chromatin at their TSS region, they are less shielded by nucleosomes and, therefore, more susceptible to endonuclease cleavage. Consequently, the depth of cfDNA originating from the TSS of active genes tends to be shallower compared to that of inactive genes. NDR quantifies the normalized depth within each 2-kilobase window surrounding each TSS. The lower the NDR of a gene TSS site, the more likely the gene is highly expressed. | 1 | Applied and Interdisciplinary Chemistry |
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