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Flare connections require that the end of a tubing section be spread outward in a bell shape using a flare tool. A flare nut then compresses this bell-shaped end onto a male fitting. Flare connections are a labor-intensive method of making connections, but are quite reliable over the course of many years. | 1 | Applied and Interdisciplinary Chemistry |
Sea salt aerosol, which originally comes from sea spray, is one of the most widely distributed natural aerosols. Sea salt aerosols are characterized as non-light-absorbing, highly hygroscopic, and having coarse particle size. Some sea salt dominated aerosols could have a single scattering albedo as large as ~0.97. Due to the hygroscopy, a sea salt particle can serve as a very efficient cloud condensation nuclei (CCN), altering cloud reflectivity, lifetime, and precipitation process. According to the IPCC report, the total sea salt flux from ocean to atmosphere is ~3300 teragrams (Tg) per year. | 0 | Theoretical and Fundamental Chemistry |
The zero-phonon line and the phonon sideband jointly constitute the line shape of individual light absorbing and emitting molecules (chromophores) embedded into a transparent solid matrix. When the host matrix contains many chromophores, each will contribute a zero-phonon line and a phonon sideband to the absorption and emission spectra. The spectra originating from a collection of identical chromophores in a matrix is said to be inhomogeneously broadened because each chromophore is surrounded by a somewhat different matrix environment which modifies the energy required for an electronic transition. In an inhomogeneous distribution of chromophores, individual zero-phonon line and phonon sideband positions are therefore shifted and overlapping.
Figure 1 shows the typical line shape for electronic transitions of individual chromophores in a solid matrix. The zero-phonon line is located at a frequency ω’ determined by the intrinsic difference in energy levels between ground and excited state as well as by the local environment. The phonon sideband is shifted to a higher frequency in absorption and to a lower frequency in fluorescence. The frequency gap Δ between the zero-phonon line and the peak of the phonon side band is determined by Franck–Condon principles.
The distribution of intensity between the zero-phonon line and the phonon side band is strongly dependent on temperature. At room temperature there is enough thermal energy to excite many phonons and the probability of zero-phonon transition is close to zero. For organic chromophores in organic matrices, the probability of a zero-phonon electronic transition only becomes likely below about 40 kelvins, but depends also on the strength of coupling between the chromophore and the host lattice. | 0 | Theoretical and Fundamental Chemistry |
Intensity-modulated radiation therapy (IMRT) is an advanced type of high-precision radiation that is the next generation of 3DCRT. IMRT also improves the ability to conform the treatment volume to concave tumor shapes, for example when the tumor is wrapped around a vulnerable structure such as the spinal cord or a major organ or blood vessel. Computer-controlled X-ray accelerators distribute precise radiation doses to malignant tumors or specific areas within the tumor. The pattern of radiation delivery is determined using highly tailored computing applications to perform optimization and treatment simulation (Treatment Planning). The radiation dose is consistent with the 3-D shape of the tumor by controlling, or modulating, the radiation beam's intensity. The radiation dose intensity is elevated near the gross tumor volume while radiation among the neighboring normal tissues is decreased or avoided completely. This results in better tumor targeting, lessened side effects, and improved treatment outcomes than even 3DCRT.
3DCRT is still used extensively for many body sites but the use of IMRT is growing in more complicated body sites such as CNS, head and neck, prostate, breast, and lung. Unfortunately, IMRT is limited by its need for additional time from experienced medical personnel. This is because physicians must manually delineate the tumors one CT image at a time through the entire disease site which can take much longer than 3DCRT preparation. Then, medical physicists and dosimetrists must be engaged to create a viable treatment plan. Also, the IMRT technology has only been used commercially since the late 1990s even at the most advanced cancer centers, so radiation oncologists who did not learn it as part of their residency programs must find additional sources of education before implementing IMRT.
Proof of improved survival benefit from either of these two techniques over conventional radiation therapy (2DXRT) is growing for many tumor sites, but the ability to reduce toxicity is generally accepted. This is particularly the case for head and neck cancers in a series of pivotal trials performed by Professor Christopher Nutting of the Royal Marsden Hospital. Both techniques enable dose escalation, potentially increasing usefulness. There has been some concern, particularly with IMRT, about increased exposure of normal tissue to radiation and the consequent potential for secondary malignancy. Overconfidence in the accuracy of imaging may increase the chance of missing lesions that are invisible on the planning scans (and therefore not included in the treatment plan) or that move between or during a treatment (for example, due to respiration or inadequate patient immobilization). New techniques are being developed to better control this uncertainty – for example, real-time imaging combined with real-time adjustment of the therapeutic beams. This new technology is called image-guided radiation therapy or four-dimensional radiation therapy.
Another technique is the real-time tracking and localization of one or more small implantable electric devices implanted inside or close to the tumor. There are various types of medical implantable devices that are used for this purpose. It can be a magnetic transponder which senses the magnetic field generated by several transmitting coils, and then transmits the measurements back to the positioning system to determine the location. The implantable device can also be a small wireless transmitter sending out an RF signal which then will be received by a sensor array and used for localization and real-time tracking of the tumor position.
A well-studied issue with IMRT is the "tongue and groove effect" which results in unwanted underdosing, due to irradiating through extended tongues and grooves of overlapping MLC (multileaf collimator) leaves. While solutions to this issue have been developed, which either reduce the TG effect to negligible amounts or remove it completely, they depend upon the method of IMRT being used and some of them carry costs of their own. Some texts distinguish "tongue and groove error" from "tongue or groove error", according as both or one side of the aperture is occluded. | 0 | Theoretical and Fundamental Chemistry |
Threonine proteases, such as the proteasome protease subunit and ornithine acyltransferases use the secondary hydroxyl of threonine in a manner analogous to the use of the serine primary hydroxyl. However, due to the steric interference of the extra methyl group of threonine, the base member of the triad is the N-terminal amide which polarises an ordered water which, in turn, deprotonates the catalytic hydroxyl to increase its reactivity. Similarly, there exist equivalent serine only and cysteine only configurations such as penicillin acylase G and penicillin acylase V which are evolutionarily related to the proteasome proteases. Again, these use their N-terminal amide as a base. | 1 | Applied and Interdisciplinary Chemistry |
The binding constant, or affinity constant/association constant, is a special case of the equilibrium constant K, and is the inverse of the dissociation constant. It is associated with the binding and unbinding reaction of receptor (R) and ligand (L) molecules, which is formalized as:
:R + L RL
The reaction is characterized by the on-rate constant k and the off-rate constant k, which have units of M s and s, respectively. In equilibrium, the forward binding transition R + L → RL should be balanced by the backward unbinding transition RL → R + L. That is,
where [R], [L] and [RL] represent the concentration of unbound free receptors, the concentration of unbound free ligand and the concentration of receptor-ligand complexes. The binding constant K is defined by
An often considered quantity is the dissociation constant K ≡ , which has the unit of concentration, despite the fact that strictly speaking, all association constants are unitless values. The inclusion of units arises from the simplification that such constants are calculated solely from concentrations, which is not the case. Once chemical activity is factored into the correct form of the equation, a dimensionless value is obtained. For the binding of receptor and ligand molecules in solution, the molar Gibbs free energy ΔG, or the binding affinity is related to the dissociation constant K via
in which R is the ideal gas constant, T temperature and the standard reference concentration c</sup> = 1 mol/L. | 0 | Theoretical and Fundamental Chemistry |
A widely use Code for the procedures, direction, and guidance for determining the thermo-hydraulic performance of a closed feedwater heater is the ASME PTC 12.1 Feedwater Heater Standard. | 1 | Applied and Interdisciplinary Chemistry |
A western blot is a technique by which specific proteins can be detected from a mixture of proteins. Western blots can be used to determine the size of isolated proteins, as well as to quantify their expression. In western blotting, proteins are first separated by size, in a thin gel sandwiched between two glass plates in a technique known as SDS-PAGE. The proteins in the gel are then transferred to a polyvinylidene fluoride (PVDF), nitrocellulose, nylon, or other support membrane. This membrane can then be probed with solutions of antibodies. Antibodies that specifically bind to the protein of interest can then be visualized by a variety of techniques, including colored products, chemiluminescence, or autoradiography. Often, the antibodies are labeled with enzymes. When a chemiluminescent substrate is exposed to the enzyme it allows detection. Using western blotting techniques allows not only detection but also quantitative analysis. Analogous methods to western blotting can be used to directly stain specific proteins in live cells or tissue sections. | 1 | Applied and Interdisciplinary Chemistry |
Barbas is known for her research on metabolomics, a field she was first introduced to while she was a Marie Curie fellow. Her early research centered on the analysis of vitamins and development of chemical methods to analyze compounds such as caffeine. Her subsequent research has developed methods to analyze organic compounds in pharmaceutical drugs and foods, and defined biomarkers for diseases such as leukemia and Parkinson's disease. She is also known for defining quality assurance protocols for metabolomics data analysis and establishing workflows to analyze metabolomics data. | 0 | Theoretical and Fundamental Chemistry |
Titanium boride (TiB) is intentionally added to the melt for grain refinement to improve mechanical properties.
Phosphorus is added to the melt hypereutectic alloys for modification of the silicon phase for better mechanical properties. This creates AlP inclusions.
Boron treatment inclusions ( (Ti, V)B ) form when boron is added to the melt to increase conductivity by precipitating vanadium and titanium. | 1 | Applied and Interdisciplinary Chemistry |
Seaborgs subsequent elaborations of the actinide concept theorized a series of superheavy elements in a transactinide series comprising elements from 104 to 121 and a superactinide series of elements from 122 to 153. He proposed an extended periodic table with an additional period of 50 elements (thus reaching element 168); this eighth period was derived from an extrapolation of the Aufbau principle and placed elements 121 to 138 in a g-block, in which a new g subshell would be filled. Seaborgs model, however, did not take into account relativistic effects resulting from high atomic number and electron orbital speed. Burkhard Fricke in 1971 and Pekka Pyykkö in 2010 used computer modeling to calculate the positions of elements up to Z = 172, and found that the positions of several elements were different from those predicted by Seaborg. Although models from Pyykkö and Fricke generally place element 172 as the next noble gas, there is no clear consensus on the electron configurations of elements beyond 120 and thus their placement in an extended periodic table. It is now thought that because of relativistic effects, such an extension will feature elements that break the periodicity in known elements, thus posing another hurdle to future periodic table constructs.
The discovery of tennessine in 2010 filled the last remaining gap in the seventh period. Any newly discovered elements will thus be placed in an eighth period.
Despite the completion of the seventh period, experimental chemistry of some transactinides has been shown to be inconsistent with the periodic law. In the 1990s, Ken Czerwinski at University of California, Berkeley observed similarities between rutherfordium and plutonium and between dubnium and protactinium, rather than a clear continuation of periodicity in groups 4 and 5. More recent experiments on copernicium and flerovium have yielded inconsistent results, some of which suggest that these elements behave more like the noble gas radon rather than mercury and lead, their respective congeners. As such, the chemistry of many superheavy elements has yet to be well characterized, and it remains unclear whether the periodic law can still be used to extrapolate the properties of undiscovered elements. | 1 | Applied and Interdisciplinary Chemistry |
He was a medical doctor from the Faculty of Paris and received his degree in medicine in 1669, after presenting a thesis under the presidency of Guy-Crescent Fagon, first physician to the king, against the use of tobacco. Claude Berger was related to Fagon, but the latter only knew him during this thesis. He then granted her his friendship and protection. He worked with Joseph Pitton de Tournefort on the study of plants who appreciated him and made him enter as his pupil at the Royal Academy of Sciences, on February 14, 1699. After various arrangements inside the academy, he became a pupil of Guillaume Homberg on January 27, 1700. Having been received as a doctor of medicine, he was obliged to give lessons at the Schools of Paris for two years, where he obtained some success. His father took him with him to visit his sick and being ill replaced him for the last two years of his life, from 1703. He succeeded his father after his death and was appointed doctor regent, in 1705. In 1708 he obtained the position of medical adviser to the king for 22,000 pounds, which requires him to be present at Versailles the first quarter of each year. | 1 | Applied and Interdisciplinary Chemistry |
It can complement X-ray crystallography for studies of very small crystals (<0.1 micrometers), both inorganic, organic, and proteins, such as membrane proteins, that cannot easily form the large 3-dimensional crystals required for that process. Protein structures are usually determined from either 2-dimensional crystals (sheets or helices), polyhedrons such as viral capsids, or dispersed individual proteins. Electrons can be used in these situations, whereas X-rays cannot, because electrons interact more strongly with atoms than X-rays do. Thus, X-rays will travel through a thin 2-dimensional crystal without diffracting significantly, whereas electrons can be used to form an image. Conversely, the strong interaction between electrons and protons makes thick (e.g. 3-dimensional > 1 micrometer) crystals impervious to electrons, which only penetrate short distances.
One of the main difficulties in X-ray crystallography is determining phases in the diffraction pattern. Because of the complexity of X-ray lenses, it is difficult to form an image of the crystal being diffracted, and hence phase information is lost. Fortunately, electron microscopes can resolve atomic structure in real space and the crystallographic structure factor phase information can be experimentally determined from an image's Fourier transform. The Fourier transform of an atomic resolution image is similar, but different, to a diffraction pattern—with reciprocal lattice spots reflecting the symmetry and spacing of a crystal. Aaron Klug was the first to realize that the phase information could be read out directly from the Fourier transform of an electron microscopy image that had been scanned into a computer, already in 1968. For this, and his studies on virus structures and transfer-RNA, Klug received the Nobel Prize for chemistry in 1982. | 0 | Theoretical and Fundamental Chemistry |
FAIRE uses the biochemical properties of protein-bound DNA to separate nucleosome-depleted regions in the genome. Cells will be subjected to cross-linking, ensuring that the interaction between the nucleosomes and DNA are fixed. After sonication, the fragmented and fixed DNA is separated using a phenol-chloroform extraction. This method creates two phases, an organic and an aqueous phase. Due to their biochemical properties, the DNA fragments cross-linked to nucleosomes will preferentially sit in the organic phase. Nucleosome depleted or ‘open’ regions on the other hand will be found in the aqueous phase. By specifically extracting the aqueous phase, only nucleosome-depleted regions will be purified and enriched. | 1 | Applied and Interdisciplinary Chemistry |
Finally since
we find that
Since the Gibbs free energy per mole of the mixture is
then
At last we can calculate the molar entropy of mixing since
and | 0 | Theoretical and Fundamental Chemistry |
* [http://catalog.hathitrust.org/Record/001566171 Dietary Prevention and Treatment of Heart Disease], (with E. Virginia Dobbin and Alex V. Nichols), 256 pages, 1958, Putnam
* [http://catalog.hathitrust.org/Record/001588231 What we do know about heart attacks], 180 pages, 1958, Putnam
* [http://catalog.hathitrust.org/Record/001578403 Coronary heart disease], 363 pages, 1959, Charles C. Thomas
* Population control through nuclear pollution,(with Arthur R. Tamplin, Ph.D.) 242 pages, 1970, Nelson Hall Co.
* [http://www.ratical.org/radiation/CNR/PP/ Poisoned Power, The Case Against Nuclear Power Plants Before and After Three Mile Island] (with Arthur R. Tamplin, Ph.D.), 1971, 1979
* Irrevy: an irreverent, illustrated view of nuclear power, 1979, Committee for Nuclear Responsibility,
* Radiation And Human Health, 908 pages, 1981
* X-Rays: Health Effects of Common Exams (with Egan O'Connor), 439 pages, 1985
* [http://www.ratical.org/radiation/CNR/RIC/ Radiation-Induced Cancer From Low-Dose Exposure: An Independent Analysis] 480 pages, 1990
* Chernobyl Accident: Radiation Consequences for This and Future Generations, 574 pages, 1994
* [http://www.ratical.org/radiation/CNR/PBC/ Preventing Breast Cancer: The Story of a Major, Proven, Preventable Cause of this Disease] 1996
* [http://www.ratical.org/radiation/CNR/RMP/ Radiation from Medical Procedures in the Pathogenesis of Cancer and Ischemic Heart Disease: Dose-Response Studies with Physicians per 100,000 Population] 1999 | 0 | Theoretical and Fundamental Chemistry |
Numerous biomolecules exhibit the ability to dissolve certain metal cations. Thus, proteins, polysaccharides, and polynucleic acids are excellent polydentate ligands for many metal ions. Organic compounds such as the amino acids glutamic acid and histidine, organic diacids such as malate, and polypeptides such as phytochelatin are also typical chelators. In addition to these adventitious chelators, several biomolecules are specifically produced to bind certain metals (see next section).
Virtually all metalloenzymes feature metals that are chelated, usually to peptides or cofactors and prosthetic groups. Such chelating agents include the porphyrin rings in hemoglobin and chlorophyll. Many microbial species produce water-soluble pigments that serve as chelating agents, termed siderophores. For example, species of Pseudomonas are known to secrete pyochelin and pyoverdine that bind iron. Enterobactin, produced by E. coli, is the strongest chelating agent known. The marine mussels use metal chelation esp. Fe chelation with the Dopa residues in mussel foot protein-1 to improve the strength of the threads that they use to secure themselves to surfaces.
In earth science, chemical weathering is attributed to organic chelating agents (e.g., peptides and sugars) that extract metal ions from minerals and rocks. Most metal complexes in the environment and in nature are bound in some form of chelate ring (e.g., with a humic acid or a protein). Thus, metal chelates are relevant to the mobilization of metals in the soil, the uptake and the accumulation of metals into plants and microorganisms. Selective chelation of heavy metals is relevant to bioremediation (e.g., removal of Cs from radioactive waste). | 0 | Theoretical and Fundamental Chemistry |
By targeting proteins, heavy metals have been known to disrupt the function and activity carried out by proteins. It is important to note that heavy metals fall into categories consisting of transition metals as well as a select amount of metalloid. These metals, when interacting with native, folded proteins, tend to play a role in obstructing their biological activity. This interference can be carried out in a different number of ways. These heavy metals can form a complex with the functional side chain groups present in a protein or form bonds to free thiols. Heavy metals also play a role in oxidizing amino acid side chains present in protein. Along with this, when interacting with metalloproteins, heavy metals can dislocate and replace key metal ions. As a result, heavy metals can interfere with folded proteins, which can strongly deter protein stability and activity. | 1 | Applied and Interdisciplinary Chemistry |
Common species that isotope markers are used for include proteins. In this case, amino acids with stable isotopes of either carbon, nitrogen, or hydrogen are incorporated into polypeptide sequences. These polypeptides are then put through mass spectrometry. Because of the exact defined change that these isotopes incur on the peptides, it is possible to tell through the spectrometry graph which peptides contained the isotopes. By doing so, one can extract the protein of interest from several others in a group. Isotopic compounds play an important role as photochromes, described below. | 1 | Applied and Interdisciplinary Chemistry |
In 1967, the first Tc procedures were carried out in Auckland, New Zealand. Mo was initially supplied by Amersham, UK, then by the Australian Nuclear Science and Technology Organisation (ANSTO) in Lucas Heights, Australia. | 0 | Theoretical and Fundamental Chemistry |
Non-dimensional scales of time, temperature, length, and heat transfer may be defined as
where
;Note:
:In a typical combustion process, so that .
:Therefore, . That is, fuel consumption time is much longer than ignition time, so fuel consumption is essentially negligible in the study of ignition.
:This is why the fuel concentration is assumed to remain the initial fuel concentration .
Substituting the non-dimensional variables in the energy equation from the introduction
Since , the exponential term can be linearized , hence
At , we have and for , needs to satisfy and | 1 | Applied and Interdisciplinary Chemistry |
Urine excretion of pregnanetriol can be measured over a period of 24 hours. Elevated urine pregnanetriol levels suggest adrenogenital syndrome. In monitoring treatment with cortisol replacement, elevated urine pregnanetriol levels indicate insufficient dosage of cortisol. | 1 | Applied and Interdisciplinary Chemistry |
The potential role of bioaerosols in climate change offers an abundance of research opportunities. Specific areas of study include monitoring bioaerosol impacts on different ecosystems and using meteorological data to forecast ecosystem changes. Determining global interactions is possible through methods like collecting air samples, DNA extraction from bioaerosols, and PCR amplification.
Developing more efficient modelling systems will reduce the spread of human disease and benefit economic and ecologic factors. An atmospheric modeling tool called the Atmospheric Dispersion Modelling System (ADMS 3) is currently in use for this purpose. The ADMS 3 uses computational fluid dynamics (CFD) to locate potential problem areas, minimizing the spread of harmful bioaerosol pathogens include tracking occurrences.
Agroecosystems have an array of potential future research avenues within bioaerosols. Identification of deteriorated soils may identify sources of plant or animal pathogens. | 0 | Theoretical and Fundamental Chemistry |
A neutron moisture meter is a moisture meter utilizing neutron scattering. The meters are most frequently used to measure the water content in soil or rock. The technique is non-destructive, and is sensitive to moisture in the bulk of the target material, not just at the surface.
Water, due to its hydrogen content, is an effective neutron moderator, slowing high-energy neutrons. With a source of high-energy neutrons and a detector sensitive to low-energy neutrons (thermal neutrons), the detection rate will be governed by the water content of the soil between the source and the detector. The neutron source typically contains a small amount of a radionuclide. Sources may emit neutrons during spontaneous fission, as with californium; alternatively, an alpha emitter may be mixed with a light element for a nuclear reaction yielding excess neutrons, as with americium in a beryllium matrix. | 0 | Theoretical and Fundamental Chemistry |
Sporopollenin is a biological polymer found as a major component of the tough outer (exine) walls of plant spores and pollen grains. It is chemically very stable (one of the most inert among biopolymers) and is usually well preserved in soils and sediments. The exine layer is often intricately sculptured in species-specific patterns, allowing material recovered from (for example) lake sediments to provide useful information to palynologists about plant and fungal populations in the past. Sporopollenin has found uses in the field of paleoclimatology as well. Sporopollenin is also found in the cell walls of several taxa of green alga, including Phycopeltis (an ulvophycean) and Chlorella.
Spores are dispersed by many different environmental factors, such as wind, water or animals. In suitable conditions, the sporopollenin-rich walls of pollen grains and spores can persist in the fossil record for hundreds of millions of years, since sporopollenin is resistant to chemical degradation by organic and inorganic chemicals. | 1 | Applied and Interdisciplinary Chemistry |
*[http://www.google.com/patents?id=l5wdAAAAEBAJ&dq=ininventor:%22heinz+falk%22&as_drrb_ap=q&as_minm_ap=1&as_miny_ap=2008&as_maxm_ap=1&as_maxy_ap=2008&as_drrb_is=q&as_minm_is=1&as_miny_is=2008&as_maxm_is=1&as_maxy_is=2008 Process for the N-alkylation or ureas] US Pat. 5124451 - Filed Jul 10, 1991 - Chemie Linz GmbH
*[http://www.google.com/patents?id=va8fAAAAEBAJ&dq=ininventor:%22heinz+falk%22&as_drrb_ap=q&as_minm_ap=1&as_miny_ap=2008&as_maxm_ap=1&as_maxy_ap=2008&as_drrb_is=q&as_minm_is=1&as_miny_is=2008&as_maxm_is=1&as_maxy_is=2008 Process for the N-alkylation of ureas] US Pat. 5169954 - Filed Dec 16, 1991 - Chemie Linz GmbH
*[http://www.google.com/patents?id=K7ccAAAAEBAJ&dq=ininventor:%22heinz+falk%22&as_drrb_ap=q&as_minm_ap=1&as_miny_ap=2008&as_maxm_ap=1&as_maxy_ap=2008&as_drrb_is=q&as_minm_is=1&as_miny_is=2008&as_maxm_is=1&as_maxy_is=2008 Process for the preparation of pure N,N'-asymmetrically substituted phenylureas] US Pat. 5283362 - Filed Jul 31, 1992 - Chemie Linz GmbH
*[http://www.google.com/patents?id=XU4aAAAAEBAJ&dq=5360601 Process for the preparation of Isocyanic Acid by Decomposition of N,N-trisubstituted Ureas] Eur. Pat. EP 0582863A2 - Filed Feb 16, 1994 - US Pat. Nr. 5360601 Filed Nov 1, 1994 - Chemie Linz GmbH
*Isocyanates by Decomposition of N,N,N-trisubstituted Ureas Eur. Pat. EP 0583637A1 - Filed Feb 23, 1994 - Chemie Linz GmbH
*[http://www.google.com/patents?id=XBUbAAAAEBAJ&dq=ininventor:%22heinz+falk%22&as_drrb_ap=q&as_minm_ap=1&as_miny_ap=2008&as_maxm_ap=1&as_maxy_ap=2008&as_drrb_is=q&as_minm_is=1&as_miny_is=2008&as_maxm_is=1&as_maxy_is=2008 Amine-oxides] US Pat. 5409532 - Filed Jan 21, 1993 - Lenzing AG | 0 | Theoretical and Fundamental Chemistry |
Aerobic respiration requires oxygen (O) in order to create ATP. Although carbohydrates, fats and proteins are consumed as reactants, aerobic respiration is the preferred method of pyruvate production in glycolysis, and requires pyruvate to the mitochondria in order to be fully oxidized by the citric acid cycle. The products of this process are carbon dioxide and water, and the energy transferred is used to make bonds between ADP and a third phosphate group to form ATP (adenosine triphosphate), by substrate-level phosphorylation, NADH and FADH.
The negative ΔG indicates that the reaction is exothermic (exergonic) and can occur spontaneously.
The potential of NADH and FADH is converted to more ATP through an electron transport chain with oxygen and protons (hydrogen) as the "terminal electron acceptors". Most of the ATP produced by aerobic cellular respiration is made by oxidative phosphorylation. The energy released is used to create a chemiosmotic potential by pumping protons across a membrane. This potential is then used to drive ATP synthase and produce ATP from ADP and a phosphate group. Biology textbooks often state that 38 ATP molecules can be made per oxidized glucose molecule during cellular respiration (2 from glycolysis, 2 from the Krebs cycle, and about 34 from the electron transport system). However, this maximum yield is never quite reached because of losses due to leaky membranes as well as the cost of moving pyruvate and ADP into the mitochondrial matrix, and current estimates range around 29 to 30 ATP per glucose.
Aerobic metabolism is up to 15 times more efficient than anaerobic metabolism (which yields 2 molecules of ATP per 1 molecule of glucose). However, some anaerobic organisms, such as methanogens are able to continue with anaerobic respiration, yielding more ATP by using inorganic molecules other than oxygen as final electron acceptors in the electron transport chain. They share the initial pathway of glycolysis but aerobic metabolism continues with the Krebs cycle and oxidative phosphorylation. The post-glycolytic reactions take place in the mitochondria in eukaryotic cells, and in the cytoplasm in prokaryotic cells.
Although plants are net consumers of carbon dioxide and producers of oxygen via photosynthesis, plant respiration accounts for about half of the CO generated annually by terrestrial ecosystems. | 1 | Applied and Interdisciplinary Chemistry |
In the 1970s, Dr. K.L. Rao, a dams designer and former irrigation minister proposed "National Water Grid". He was concerned about the severe shortages of water in the South and repetitive flooding in the North every year. He suggested that the Brahmaputra and Ganga basins are water surplus areas, and central and south India as water deficit areas. He proposed that surplus water be diverted to areas of deficit. When Rao made the proposal, several inter-basin transfer projects had already been successfully implemented in India, and Rao suggested that the success be scaled up.
In 1980, India's then Ministry of Water Resources came out with a report entitled "National Perspectives for Water Resources Development". This report split the water development project in two parts – the Himalayan and Peninsular components. The Congress Party came to power and it abandoned the plan. In 1982, India financed and set up a committee of nominated experts, through National Water Development Agency (NWDA) to complete detailed studies, surveys and investigations in respect of reservoirs, canals and all aspects of feasibility of interlinking peninsular rivers and related water resource management. NWDA has produced many reports over 30 years, from 1982 through 2013. However, the projects were not pursued.
The river inter-linking idea was revived in 1999, after the National Democratic Alliance formed the Government of India, but this time with a major strategic shift. The proposal was modified to intra-basin development as opposed to inter-basin water transfer. | 1 | Applied and Interdisciplinary Chemistry |
The Krupp–Renn process is a direct reduction process that uses a long tubular furnace similar to those found in cement production. The most recent units constructed have a diameter of approximately 4.5 meters and a length of 110 meters. The residence time of the product is influenced by the slope and speed of rotation of the rotary kiln, which is inclined at an angle of roughly 2.5 percent.
Prior to usage, the iron ore is crushed to less than 6 mm in particle size. The iron ore is introduced into the furnace upstream and mixed with a small amount of fuel, typically hard coal. After 6 to 8 hours, it exits the furnace as pre-reduced iron ore at 1,000 °C. The amount of iron recovered ranges from 94% to 97.5% of the initial iron in the ore.
A burner located at the lower end of the furnace provides heat, transforming it into a counter-current reactor. The fuel comprises finely pulverized coal, which, upon high-temperature combustion, generates reducing gas primarily consisting of CO. Once the furnace reaches an optimal temperature, the ore-coal mixture can serve as the primary fuel source.
The fumes exiting the furnace's upper end attain temperatures ranging from 850 to 900 °C and are subsequently cooled and purged of dust by water injection before discharge through the chimney.
The process is efficient in producing ferronickel due to the proximity of its constituent elements. At 800 °C, carbon easily reduces iron and nickel oxides, while the gangue's other oxides are not significantly reduced. Specifically, iron(II) oxide (or wustite), which is the stable iron oxide at 800 °C, has a reducibility similar to that of nickel(II) oxide, making it impossible to reduce one without reducing the other. | 1 | Applied and Interdisciplinary Chemistry |
Infragravity waves are thought to be a generating mechanism behind sneaker waves, unusually large and long-duration waves that cause water to surge far onshore and that have killed a number of people in the US Pacific Northwest.
Infragravity waves generated along the Pacific coast of North America have been observed to propagate transoceanically to Antarctica and there to impinge on the Ross Ice Shelf. Their frequencies more closely couple with the ice shelf natural frequencies and they produce a larger amplitude ice shelf movement than the normal ocean swell of gravity waves. Further, they are not damped by sea ice as normal ocean swell is. As a result, they flex floating ice shelves such as the Ross Ice Shelf; this flexure contributes significantly to the breakup on the ice shelf. | 1 | Applied and Interdisciplinary Chemistry |
Borate buffered saline (abbreviated BBS) is a buffer used in some biochemical techniques to maintain the pH within a relatively narrow range. Borate buffers have an alkaline buffering capacity in the 8–10 range.
Boric acid has a pK of 9.14 at 25 °C. | 1 | Applied and Interdisciplinary Chemistry |
During the American Civil War, British India was the main source for saltpeter for the manufacture of gunpowder for the Union armies. This supply was threatened by the British government during the Trent Affair, when Union naval forces stopped a British ship, the RMS Trent, and removed two Confederate diplomats. The British government responded in part by halting all exports of saltpeter to the United States, threatening their gunpowder manufacturing resources. Shortly thereafter, the situation was resolved and the Confederate diplomats were released.
The Union Navy blockaded the southern Confederate States, which reduced the amount of gunpowder that could be imported from overseas. The Confederate Nitre and Mining Bureau was formed to produce gunpowder for the army and the navy from domestic resources. Nitre is the English spelling of "Niter". While carbon and sulfur were readily available throughout the south, potassium nitrate was often produced from the Calcium nitrate found in cave dirt, tobacco barn floors and barn stalls other places. A number of caves were mined, and the men and boys who worked in the caves were called "peter monkey", somewhat in imitation of the naval term "powder monkey" that was used for the boys who brought up charges of gunpowder on gunboats.
On 13 November 1862, the Confederate government advertised in the Charleston Daily Courier for 20 or 30 "able bodied Negro men" to work in the new nitre beds at Ashley Ferry, S.C. The nitre beds were large rectangles of rotted manure and straw, moistened weekly with urine, "dung water", and liquid from privies, cesspools and drains, and turned over regularly. The process was designed to yield saltpeter, an ingredient of gunpowder, which the Confederate army needed during the Civil War. The South was so desperate for saltpeter for gunpowder that one Alabama official reportedly placed a newspaper ad asking that the contents of chamber pots be saved for collection. In the winter of 1863, scores of enslaved people were set to work extracting it from a huge cave in Barstow County, Ga., where they labored by torchlight in grim conditions, hauling out and processing the so-called "peter dirt",. In South Carolina, in April 1864, the Confederate government hired 31 enslaved people to work at the Ashley Ferry Nitre Works. | 1 | Applied and Interdisciplinary Chemistry |
Mono-BOC-cystamine (mono BOC protected cystamine) is a tert-butyloxycarbonyl (BOC) derivative of cystamine used as crosslinker in biotechnology and molecular biology applications. This compound was originally reported by Hansen et al. | 1 | Applied and Interdisciplinary Chemistry |
The introduction of whole genome sequencing may have ethical implications. On one hand, genetic testing can potentially diagnose preventable diseases, both in the individual undergoing genetic testing and in their relatives. On the other hand, genetic testing has potential downsides such as genetic discrimination, loss of anonymity, and psychological impacts such as discovery of non-paternity.
Some ethicists insist that the privacy of individuals undergoing genetic testing must be protected, and is of particular concern when minors undergo genetic testing. Illuminas CEO, Jay Flatley, claimed in February 2009 that "by 2019 it will have become routine to map infants genes when they are born". This potential use of genome sequencing is highly controversial, as it runs counter to established ethical norms for predictive genetic testing of asymptomatic minors that have been well established in the fields of medical genetics and genetic counseling. The traditional guidelines for genetic testing have been developed over the course of several decades since it first became possible to test for genetic markers associated with disease, prior to the advent of cost-effective, comprehensive genetic screening.
When an individual undergoes whole genome sequencing, they reveal information about not only their own DNA sequences, but also about probable DNA sequences of their close genetic relatives. This information can further reveal useful predictive information about relatives' present and future health risks. Hence, there are important questions about what obligations, if any, are owed to the family members of the individuals who are undergoing genetic testing. In Western/European society, tested individuals are usually encouraged to share important information on any genetic diagnoses with their close relatives, since the importance of the genetic diagnosis for offspring and other close relatives is usually one of the reasons for seeking a genetic testing in the first place. Nevertheless, a major ethical dilemma can develop when the patients refuse to share information on a diagnosis that is made for serious genetic disorder that is highly preventable and where there is a high risk to relatives carrying the same disease mutation. Under such circumstances, the clinician may suspect that the relatives would rather know of the diagnosis and hence the clinician can face a conflict of interest with respect to patient-doctor confidentiality.
Privacy concerns can also arise when whole genome sequencing is used in scientific research studies. Researchers often need to put information on patient's genotypes and phenotypes into public scientific databases, such as locus specific databases. Although only anonymous patient data are submitted to locus specific databases, patients might still be identifiable by their relatives in the case of finding a rare disease or a rare missense mutation. Public discussion around the introduction of advanced forensic techniques (such as advanced familial searching using public DNA ancestry websites and DNA phenotyping approaches) has been limited, disjointed, and unfocused. As forensic genetics and medical genetics converge toward genome sequencing, issues surrounding genetic data become increasingly connected, and additional legal protections may need to be established. | 1 | Applied and Interdisciplinary Chemistry |
Twenty-three out of 25 patients showed high expression of SFRP1 mRNA in leiomyoma than the matched normal myometrium. During the menstrual cycle, the level of SFRP1 mRNA in leiomyoma was highest in the follicular phase. Gonadotropin releasing hormone analogue (GnRHa) decreases estrogen secretion from the ovary. Patients treated with (GnRHa) presurgically showed the lowest expression of SFRP1 in both myometrial and leiomyoma tissues. These findings suggest that SFRP1 could be under the control of estrogen. Gene expression of estrogen receptors in leiomyomas is stronger than that in the myometrium. This suggests that leiomyoma possess increased sensitivity to E2 (estradiol, a form of estrogen) and the estrogen-dependent expression of SFRP1 in leiomyoma could be associated with the growth and pathogenesis of leiomyoma. | 1 | Applied and Interdisciplinary Chemistry |
Ceramography evolved along with other branches of materialography and ceramic engineering. Alois de Widmanstätten of Austria etched a meteorite in 1808 to reveal proeutectoid ferrite bands that grew on prior austenite grain boundaries. Geologist Henry Clifton Sorby, the "father of metallography," applied petrographic techniques to the steel industry in the 1860s in Sheffield, England. French geologist Auguste Michel-Lévy devised a chart that correlated the optical properties of minerals to their transmitted color and thickness in the 1880s. Swedish metallurgist J.A. Brinell invented the first quantitative hardness scale in 1900. Smith and Sandland developed the first microindentation hardness test at Vickers Ltd. in London in 1922. Swiss-born microscopist A.I. Buehler started the first metallographic equipment manufacturer near Chicago in 1936. Frederick Knoop and colleagues at the National Bureau of Standards developed a less-penetrating (than Vickers) microindentation test in 1939. Struers A/S of Copenhagen introduced the electrolytic polisher to metallography in 1943. George Kehl of Columbia University wrote a book that was considered the bible of materialography until the 1980s. Kehl co-founded a group within the Atomic Energy Commission that became the International Metallographic Society in 1967. | 1 | Applied and Interdisciplinary Chemistry |
The cellular response in signal transduction cascades involves alteration of the expression of effector genes or activation/inhibition of targeted proteins. Regulation of protein activity mainly involves phosphorylation/dephosphorylation events, leading to its activation or inhibition. It is the case for the vast majority of responses as a consequence of the binding of the primary messengers to membrane receptors. This response is quick, as it involves regulation of molecules that are already present in the cell. On the other hand, the induction or repression of the expression of genes requires the binding of transcriptional factors to the regulatory sequences of these genes. The transcriptional factors are activated by the primary messengers, in most cases, due to their function as nuclear receptors for these messengers. The secondary messengers like DAG or Ca could also induce or repress gene expression, via transcriptional factors. This response is slower than the first because it involves more steps, like transcription of genes and then the effect of newly formed proteins in a specific target. The target could be a protein or another gene. | 0 | Theoretical and Fundamental Chemistry |
A random selection of Prof Seppelt's publications:
*Seppelt, K. “Selenoyl difluoride” Inorganic Syntheses, 1980, volume XX, pp. 36–38. .
*Seppelt, K., Pfennig, V. Science 1996, 271, 626-8.
*Kleinhenz, S., Pfennig, V., Seppelt, K. Chem. Eur. J. 1998, 4, 1687-91.
*Seppelt, K. Accounts of Chemical Research 2003, 36(2), 147-153. | 0 | Theoretical and Fundamental Chemistry |
Isozymes (and allozymes) are variants of the same enzyme. Unless they are identical in their biochemical properties, for example their substrates and enzyme kinetics, they may be distinguished by a biochemical assay. However, such differences are usually subtle, particularly between allozymes which are often neutral variants. This subtlety is to be expected, because two enzymes that differ significantly in their function are unlikely to have been identified as isozymes.
While isozymes may be almost identical in function, they may differ in other ways. In particular, amino acid substitutions that change the electric charge of the enzyme are simple to identify by gel electrophoresis, and this forms the basis for the use of isozymes as molecular markers. To identify isozymes, a crude protein extract is made by grinding animal or plant tissue with an extraction buffer, and the components of extract are separated according to their charge by gel electrophoresis. Historically, this has usually been done using gels made from potato starch, but acrylamide gels provide better resolution.
All the proteins from the tissue are present in the gel, so that individual enzymes must be identified using an assay that links their function to a staining reaction. For example, detection can be based on the localised precipitation of soluble indicator dyes such as tetrazolium salts which become insoluble when they are reduced by cofactors such as NAD or NADP, which generated in zones of enzyme activity. This assay method requires that the enzymes are still functional after separation (native gel electrophoresis), and provides the greatest challenge to using isozymes as a laboratory technique.
Isoenzymes differ in kinetics (they have different K and V values). | 1 | Applied and Interdisciplinary Chemistry |
In the case that the flow is incompressible, or equivalently that , the enstrophy can be described as the integral of the square of the vorticity :
or, in terms of the flow velocity:
In the context of the incompressible Navier-Stokes equations, enstrophy appears in the following useful result:
The quantity in parentheses on the left is the kinetic energy in the flow, so the result says that energy declines proportional to the kinematic viscosity times the enstrophy. | 1 | Applied and Interdisciplinary Chemistry |
The human body needs iron for oxygen transport. Oxygen (O) is required for the functioning and survival of nearly all cell types. Oxygen is transported from the lungs to the rest of the body bound to the heme group of hemoglobin in red blood cells. In muscles cells, iron binds oxygen to myoglobin, which regulates its release. | 1 | Applied and Interdisciplinary Chemistry |
Studies have shown that diversity among nonsynonymous substitutions is significantly lower than among synonymous substitutions. This is due to the fact that nonsynonymous substitutions are subject to much higher selective pressures than synonymous mutations. Motoo Kimura (1968) determined that calculated mutation rates were impossibly high, unless most of the mutations that occurred were either neutral or "nearly neutral". He determined that if this were true, genetic drift would be a more powerful factor in molecular evolution than natural selection. The "nearly neutral" theory proposes that molecular evolution acting on nonsynonymous substitutions is driven by mutation, genetic drift, and very weak natural selection, and that it is extremely sensitive to population size. In order to determine whether natural selection is taking place at a certain loci, the McDonald–Kreitman test can be performed. The test consists of comparing ratios of synonymous and nonsynonymous genes between closely related species to the ratio of synonymous to nonsynonymous polymorphisms within species. If the ratios are the same, then Neutral theory of molecular evolution is true for that loci, and evolution is proceeding primarily through genetic drift. If there are more nonsynonymous substitutions between species than within a species, positive natural selection is occurring on beneficial alleles and natural selection is taking place. Nonsynonymous substitutions have been found to be more common in loci involving pathogen resistance, reproductive loci involving sperm competition or egg-sperm interactions, and genes that have replicated and gained new functions, indicating that positive selection is taking place. | 1 | Applied and Interdisciplinary Chemistry |
The IChemE Global Awards take place in November in the UK. The awards are highly regarded throughout the process industries for recognising and rewarding chemical engineering excellence and innovation. The first awards took place at the National Motorcycle Museum in Birmingham on 23 March 1994.
There are 16 categories in total that applicants are invited to enter, including Business Start-Up, Industry Project, Process Safety, and Sustainability, offering a broad scope for entries.
The organisation also holds awards ceremonies in other locations across the globe. 2024 will see the return of the IChemE Malaysia Awards alongside the first-ever IChemE Australasia Awards. | 1 | Applied and Interdisciplinary Chemistry |
The endocannabinoid system is also involved in mediating some of the physiological and cognitive effects of voluntary physical exercise in humans and other animals, such as contributing to exercise-induced euphoria as well as modulating locomotor activity and motivational salience for rewards. In humans, the plasma concentration of certain endocannabinoids (i.e., anandamide) have been found to rise during physical activity; since endocannabinoids can effectively penetrate the blood–brain barrier, it has been suggested that anandamide, along with other euphoriant neurochemicals, contributes to the development of exercise-induced euphoria in humans, a state colloquially referred to as a runner's high. | 1 | Applied and Interdisciplinary Chemistry |
A galactoside is a glycoside containing galactose. The H of the OH group on carbon-1 of galactose is replaced by an organic moiety.
Depending on whether the glycosidic bond lies "above" or "below" the plane of the galactose molecule, galactosides are classified as α-galactosides or β-galactosides.
A β-galactoside is a type of galactoside in which the glycosidic bond lies above the plane of the galactose residue. The most commonly recognized and used β-galactoside in biochemistry is lactose. However, other chemicals, such as ONPG, are known, but these are typically synthesized for biochemical assays.
Galactosides play significant roles in metabolic processes of many organisms and are hydrolyzed by a class of enzymes called galactosidases and are classified according to what type of glycosidic linkage on the galactoside they will break. For example, enzymes that hydrolyze the β-galactoside glycosidic bond are called β-galactosidases, while those that hydrolyze the α-galactoside glycosidic bond are known as α-galactosidases. | 1 | Applied and Interdisciplinary Chemistry |
A common means of expressing the length of a chain is the degree of polymerization, which quantifies the number of monomers incorporated into the chain. As with other molecules, a polymers size may also be expressed in terms of molecular weight. Since synthetic polymerization techniques typically yield a statistical distribution of chain lengths, the molecular weight is expressed in terms of weighted averages. The number-average molecular weight (M) and weight-average molecular weight (M) are most commonly reported. The ratio of these two values (M / M) is the dispersity (Đ'), which is commonly used to express the width of the molecular weight distribution.
The physical properties of polymer strongly depend on the length (or equivalently, the molecular weight) of the polymer chain. One important example of the physical consequences of the molecular weight is the scaling of the viscosity (resistance to flow) in the melt. The influence of the weight-average molecular weight () on the melt viscosity () depends on whether the polymer is above or below the onset of entanglements. Below the entanglement molecular weight, , whereas above the entanglement molecular weight, . In the latter case, increasing the polymer chain length 10-fold would increase the viscosity over 1000 times. Increasing chain length furthermore tends to decrease chain mobility, increase strength and toughness, and increase the glass-transition temperature (T). This is a result of the increase in chain interactions such as van der Waals attractions and entanglements that come with increased chain length. These interactions tend to fix the individual chains more strongly in position and resist deformations and matrix breakup, both at higher stresses and higher temperatures. | 0 | Theoretical and Fundamental Chemistry |
The sprays are assumed to be spherical with radius , even though the assumption is valid for solid particles(liquid droplets) when their shape has no consequence on the combustion. For liquid droplets to be nearly spherical, the spray has to be dilute(total volume occupied by the sprays is much less than the volume of the gas) and the Weber number , where is the gas density, is the spray droplet velocity, is the gas velocity and is the surface tension of the liquid spray, should be .
The equation is described by a number density function , which represents the probable number of spray particles (droplets) of chemical species (of total species), that one can find with radii between and , located in the spatial range between and , traveling with a velocity in between and , having the temperature in between and at time . Then the spray equation for the evolution of this density function is given by
where
: is the force per unit mass acting on the species spray (acceleration applied to the sprays),
: is the rate of change of the size of the species spray,
: is the rate of change of the temperature of the species spray due to heat transfer,
: is the rate of change of number density function of species spray due to nucleation, liquid breakup etc.,
: is the rate of change of number density function of species spray due to collision with other spray particles. | 1 | Applied and Interdisciplinary Chemistry |
Gold working in the Bronze Age British Isles refers to the use of gold to produce ornaments and other prestige items in the British Isles during the Bronze Age, between and in Britain, and up to about 550 BCE in Ireland. In this period, communities in Britain and Ireland first learned how to work metal, leading to the widespread creation of not only gold but also copper and bronze items as well. Gold artefacts in particular were prestige items used to designate the high status of those individuals who wore, or were buried with them.
Around 1,500 gold objects dating to the Bronze Age survive in collections, around 1000 of them from Ireland and the other 500 from Britain; this is a much smaller number than would have been originally crafted, leading archaeologists to believe that "many thousands of gold objects were made and used" in the Bronze Age British Isles.
Records indicate that Bronze Age gold artefacts had begun to be discovered by the 18th century at the least, although at the time many were melted down or lost. Only with the rise of the antiquarian and then archaeological movements were the antiquity of these items recognised, after which they were more usually preserved in collections.
The archaeologist George Eogan noted that investigation of Bronze Age gold artefacts revealed not only "the work of craftsmen and technicians" from that period but also aided our understanding of "broader aspects of society such as social stratification, trade, commerce and ritual." | 1 | Applied and Interdisciplinary Chemistry |
The Gaddum equation is a further generalisation of the Hill-equation, incorporating the presence of a reversible competitive antagonist. The Gaddum equation is derived similarly to the Hill-equation but with 2 equilibria: both the ligand with the receptor and the antagonist with the receptor. Hence, the Gaddum equation has 2 constants: the equilibrium constants of the ligand and that of the antagonist | 1 | Applied and Interdisciplinary Chemistry |
When iron is in contact with water and oxygen, it rusts. If salt is present, for example in seawater or salt spray, the iron tends to rust more quickly, as a result of chemical reactions. Iron metal is relatively unaffected by pure water or by dry oxygen. As with other metals, like aluminium, a tightly adhering oxide coating, a passivation layer, protects the bulk iron from further oxidation. The conversion of the passivating ferrous oxide layer to rust results from the combined action of two agents, usually oxygen and water.
Other degrading solutions are sulfur dioxide in water and carbon dioxide in water. Under these corrosive conditions, iron hydroxide species are formed. Unlike ferrous oxides, the hydroxides do not adhere to the bulk metal. As they form and flake off from the surface, fresh iron is exposed, and the corrosion process continues until either all of the iron is consumed or all of the oxygen, water, carbon dioxide or sulfur dioxide in the system are removed or consumed.
When iron rusts, the oxides take up more volume than the original metal; this expansion can generate enormous forces, damaging structures made with iron. See economic effect for more details. | 1 | Applied and Interdisciplinary Chemistry |
Like other straight-line forms of the Michaelis–Menten equation, the Eadie–Hofstee plot was used historically for rapid evaluation of the parameters and , but has been largely superseded by nonlinear regression methods that are significantly more accurate when properly weighted and no longer computationally inaccessible. | 1 | Applied and Interdisciplinary Chemistry |
This reagent is inexpensively available for laboratory use. It is a by-product from the production of ortho-toluenesulfonyl chloride (a precursor for the synthesis of the common food additive and catalyst saccharin), via the chlorosulfonation of toluene:
: CHCH + SOCl → CHCHSOCl + HCl | 0 | Theoretical and Fundamental Chemistry |
To quantify the exposure of particular individuals or populations two approaches are used, primarily based on practical considerations: | 1 | Applied and Interdisciplinary Chemistry |
Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct use as a finished product, but more often in a form that requires further working to achieve the given properties to suit the applications.
The field of ferrous and non-ferrous extractive metallurgy have specialties that are generically grouped into the categories of mineral processing, hydrometallurgy, pyrometallurgy, and electrometallurgy based on the process adopted to extract the metal. Several processes are used for extraction of the same metal depending on occurrence and chemical requirements. | 1 | Applied and Interdisciplinary Chemistry |
This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture. Boiling points are reported at a pressure of 760 mm Hg unless otherwise stated. Where the mixture separates into layers, values are shown for upper (U) and lower (L) layers.
The data were obtained from Langes 10th edition and CRC Handbook of Chemistry and Physics' 44th edition unless otherwise noted (see color code table).
A list of 15825 binary and ternary mixtures was collated and published by the American Chemical Society. An azeotrope databank is also available online through the University of Edinburgh. | 1 | Applied and Interdisciplinary Chemistry |
There are (at least) 10 different ways to classify space groups into classes. The relations between some of these are described in the following table. Each classification system is a refinement of the ones below it. To understand an explanation given here it may be necessary to understand the next one down.
gave another classification of the space groups, called a fibrifold notation, according to the fibrifold structures on the corresponding orbifold. They divided the 219 affine space groups into reducible and irreducible groups. The reducible groups fall into 17 classes corresponding to the 17 wallpaper groups, and the remaining 35 irreducible groups are the same as the cubic groups and are classified separately. | 0 | Theoretical and Fundamental Chemistry |
Despite being in low formal oxidation states, metal carbonyls are relatively unreactive toward many electrophiles. For example, they resist attack by alkylating agents, mild acids, and mild oxidizing agents. Most metal carbonyls do undergo halogenation. Iron pentacarbonyl, for example, forms ferrous carbonyl halides:
:Fe(CO) + X → Fe(CO)X + CO
Metal–metal bonds are cleaved by halogens. Depending on the electron-counting scheme used, this can be regarded as an oxidation of the metal atoms:
:Mn(CO) + Cl → 2 Mn(CO)Cl | 0 | Theoretical and Fundamental Chemistry |
Some of the advantages provided by membrane bioreactors are as follows.
* High quality effluent: given the small size of the membrane's pores, the effluent is clear and pathogen free.
* Independent control of solids retention time and hydraulic retention time: As all the biological solids are contained in the bioreactor, the solids retention time can be controlled independently from the hydrodynamic retention time.
* Small footprint: thanks to the membrane filtration, there is a high biomass concentration contained in a small volume.
* Robust to load variations: membrane bioreactors can be operated with a broad range of operation conditions.
* Compact process: compared to the conventional activated sludge process, membrane bioreactors are more compact. | 1 | Applied and Interdisciplinary Chemistry |
Levomethamphetamine can register on urine drug screens as either methamphetamine, amphetamine, or both, depending on the subject's metabolism and dosage. L-methamphetamine metabolizes completely into L-amphetamine after a period of time. | 0 | Theoretical and Fundamental Chemistry |
β-adrenoceptor agonists are a group of drugs that act selectively on β-receptors in the lungs causing bronchodilation. β-agonists are used to treat asthma and COPD, diseases that cause obstruction in the airways. Prior to their discovery, the non-selective beta-agonist isoprenaline was used. The aim of the drug development through the years has been to minimise side effects, achieve selectivity and longer duration of action. The mechanism of action is well understood and has facilitated the development. The structure of the binding site and the nature of the binding is also well known, as is the structure activity relationship. | 1 | Applied and Interdisciplinary Chemistry |
Inductively coupled plasma atomic emission spectroscopy (ICP-AES) uses an inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element.
Advantages of ICP-AES are the excellent limit of detection and linear dynamic range, multi-element capability, low chemical interference and a stable and reproducible signal. Disadvantages are spectral interferences (many emission lines), cost and operating expense and the fact that samples typically must be in a liquid solution.
Inductively coupled plasma (ICP) source of the emission consists of an induction coil and plasma. An induction coil is a coil of wire that has an alternating current flowing through it. This current induces a magnetic field inside the coil, coupling a great deal of energy to plasma contained in a quartz tube inside the coil. Plasma is a collection of charged particles (cations and electrons) capable, by virtue of their charge, of interacting with a magnetic field. The plasmas used in atomic emissions are formed by ionizing a flowing stream of argon gas. Plasma's high-temperature results from resistive heating as the charged particles move through the gas. Because plasmas operate at much higher temperatures than flames, they provide better atomization and a higher population of excited states.
The predominant form of sample matrix in ICP-AES today is a liquid sample: acidified water or solids digested into aqueous forms. Liquid samples are pumped into the nebulizer and sample chamber via a peristaltic pump. Then the samples pass through a nebulizer that creates a fine mist of liquid particles. Larger water droplets condense on the sides of the spray chamber and are removed via the drain, while finer water droplets move with the argon flow and enter the plasma. With plasma emission, it is possible to analyze solid samples directly. These procedures include incorporating electrothermal vaporization, laser and spark ablation, and glow-discharge vaporization. | 0 | Theoretical and Fundamental Chemistry |
Originally, n was held to have an integer value between 1 and 4, which reflected the nature of the transformation in question. In the derivation above, for example, the value of 4 can be said to have contributions from three dimensions of growth and one representing a constant nucleation rate. Alternative derivations exist, where n has a different value.
If the nuclei are preformed, and so all present from the beginning, the transformation is only due to the 3-dimensional growth of the nuclei, and n has a value of 3.
An interesting condition occurs when nucleation occurs on specific sites (such as grain boundaries or impurities) that rapidly saturate soon after the transformation begins. Initially, nucleation may be random, and growth unhindered, leading to high values for n (3 or 4). Once the nucleation sites are consumed, the formation of new particles will cease.
Furthermore, if the distribution of nucleation sites is non-random, then the growth may be restricted to 1 or 2 dimensions. Site saturation may lead to n values of 1, 2 or 3 for surface, edge and point sites respectively. | 0 | Theoretical and Fundamental Chemistry |
1,2,4,5-Tetrachloro-3-nitrobenzene (tecnazene) is an organic compound with the formula . It is a colorless solid. A related isomer is 1,2,3,4-tetrachloro-5-nitrobenzene.
It is used as a standard for quantitative analysis by nuclear magnetic resonance.
1,2,4,5-Tetrachloro-3-nitrobenzene is also a fungicide used to prevent dry rot and sprouting on potatoes during storage. | 0 | Theoretical and Fundamental Chemistry |
Both singlet oxygen states have no unpaired electrons and therefore no net electron spin. The Δ is however paramagnetic as shown by the observation of an electron paramagnetic resonance (EPR) spectrum. The paramagnetism of the Δ state is due to a net orbital (and not spin) electronic angular momentum. In a magnetic field the degeneracy of the levels is split into two levels with z projections of angular momenta +1ħ and −1ħ around the molecular axis. The magnetic transition between these levels gives rise to the EPR transition. | 0 | Theoretical and Fundamental Chemistry |
Sulfur isotope biogeochemistry is the study of the distribution of sulfur isotopes in biological and geological materials. In addition to its common isotope, S, sulfur has three rare stable isotopes: S, S, and S. The distribution of these isotopes in the environment is controlled by many biochemical and physical processes, including biological metabolisms, mineral formation processes, and atmospheric chemistry. Measuring the abundance of sulfur stable isotopes in natural materials, like bacterial cultures, minerals, or seawater, can reveal information about these processes both in the modern environment and over Earth history. | 0 | Theoretical and Fundamental Chemistry |
The Swamee equation is used to solve directly for the Darcy–Weisbach friction factor (f) for a full-flowing circular pipe for all flow regimes (laminar, transitional, turbulent). It is an exact solution for the Hagen–Poiseuille equation in the laminar flow regime and an approximation of the implicit Colebrook–White equation in the turbulent regime with a maximum deviation of less than 2.38% over the specified range. Additionally, it provides a smooth transition between the laminar and turbulent regimes to be valid as a full-range equation, 0 . | 1 | Applied and Interdisciplinary Chemistry |
Hysteresis is used to measure the compression properties of nanocomposite hydrogels, which shows that this material can withstand around 90% compression. This data shows that nanocomposite hydrogels exhibit superior strength relative to conventionally-made hydrogels, which would have broken down under less compression. | 0 | Theoretical and Fundamental Chemistry |
Non-substrate-like inhibitors do not take after dipeptidic nature of DPP-4 substrates. They are non-covalent inhibitors and usually have an aromatic ring that occupies the S1-pocket, instead of the proline mimetic.
In 1999, Merck started a drug development program on DPP-4 inhibitors. When they started internal screening and medicinal chemistry program, two DPP-4 inhibitors were already in clinical trials, isoleucyl thiazolidide (P32/38) and NVP-DPP728 from Novartis. Merck in-licensed L-threo-isoleucyl thiazolidide and its allo stereoisomer. In animal studies, they found that both isomers had similar affinity for DPP-4, similar in vivo efficacy, similar pharmacokinetic and metabolic profiles. Nevertheless, the allo isomer was 10-fold more toxic. The researchers found out that this difference in toxicity was due to the allo isomer's greater inhibition of DPP-8 and DPP-9 but not because of selective DPP-4 inhibition. More research also supported that DPP-4 inhibition would not cause compromised immune function. Once this link between affinity for DPP-8/DPP-9 and toxicity was discovered, Merck decided on identifying an inhibitor with more than a thousandfold affinity for DPP-4 over the other dipeptidases. For this purpose, they used positional scanning libraries. From scanning these libraries, the researchers discovered that both DPP-4 and DPP-8 showed a strong preference for breaking down peptides with a proline at the P1 position but they found a great difference at the P2 site; i.e., they found that acidic functionality at the P2 position could provide a greater affinity for DPP-4 over DPP-8. Merck kept up doing even more research and screening. They stopped working on compounds from the α-amino acid series related to isoleucyl thiazolidide due to lack of selectivity but instead they discovered a very selective β-amino acid piperazine series through SAR studies on two screening leads. When trying to stabilize the piperazine moiety, a group of bicyclic derivatives were made, which led to the identification of a potent and selective triazolopiperazine series. Most of these analogs showed excellent pharmacokinetic properties in preclinical species. Optimization of these compounds finally led to the discovery of sitagliptin. | 1 | Applied and Interdisciplinary Chemistry |
Acyl ligands are intermediates in many carbonylation reactions, which are important in some catalytic reactions. Metal acyls arise usually via insertion of carbon monoxide into metal–alkyl bonds. Metal acyls also arise from reactions involving acyl chlorides with low-valence metal complexes or by the reaction of organolithium compounds with metal carbonyls. Metal acyls are often described by two resonance structures, one of which emphasizes the basicity of the oxygen center. O-alkylation of metal acyls gives Fischer carbene complexes. | 0 | Theoretical and Fundamental Chemistry |
The dominant forms of nitrogen in wetlands that are of importance to wastewater treatment include organic nitrogen, ammonia, ammonium, nitrate and nitrite. Total nitrogen refers to all nitrogen species. Wastewater nitrogen removal is important because of ammonias toxicity to fish if discharged into watercourses. Excessive nitrates in drinking water is thought to cause methemoglobinemia in infants, which decreases the bloods oxygen transport ability. Moreover, excess input of N from point and non-point sources to surface water promotes eutrophication in rivers, lakes, estuaries, and coastal oceans which causes several problems in aquatic ecosystems e.g. toxic algal blooms, oxygen depletion in water, fish mortality, loss of aquatic biodiversity.
Ammonia removal occurs in constructed wetlands – if they are designed to achieve biological nutrient removal – in a similar ways as in sewage treatment plants, except that no external, energy-intensive addition of air (oxygen) is needed. It is a two-step process, consisting of nitrification followed by denitrification. The nitrogen cycle is completed as follows: ammonia in the wastewater is converted to ammonium ions; the aerobic bacterium Nitrosomonas sp. oxidizes ammonium to nitrite; the bacterium Nitrobacter sp. then converts nitrite to nitrate. Under anaerobic conditions, nitrate is reduced to relatively harmless nitrogen gas that enters the atmosphere. | 1 | Applied and Interdisciplinary Chemistry |
Galvanization consists of an application on the object to be protected of a layer of metallic zinc by either hot-dip galvanizing or electroplating. Zinc is traditionally used because it is cheap, adheres well to steel, and provides cathodic protection to the steel surface in case of damage of the zinc layer. In more corrosive environments (such as salt water), cadmium plating is preferred instead of the underlying protected metal. The protective zinc layer is consumed by this action, and thus galvanization provides protection only for a limited period of time.
More modern coatings add aluminium to the coating as zinc-alume; aluminium will migrate to cover scratches and thus provide protection for a longer period. These approaches rely on the aluminium and zinc oxides protecting a once-scratched surface, rather than oxidizing as a sacrificial anode as in traditional galvanized coatings. In some cases, such as very aggressive environments or long design life, both zinc and a coating are applied to provide enhanced corrosion protection.
Typical galvanization of steel products that are to be subjected to normal day-to-day weathering in an outside environment consists of a hot-dipped 85 µm zinc coating. Under normal weather conditions, this will deteriorate at a rate of 1 µm per year, giving approximately 85 years of protection. | 1 | Applied and Interdisciplinary Chemistry |
A typical thermal spray system consists of the following:
*Spray torch (or spray gun) – the core device performing the melting and acceleration of the particles to be deposited
*Feeder – for supplying the powder, wire or liquid to the torch through tubes.
*Media supply – gases or liquids for the generation of the flame or plasma jet, gases for carrying the powder, etc.
*Robot/Labour – for manipulating the torch or the substrates to be coated
*Power supply – often standalone for the torch
*Control console(s) – either integrated or individual for all of the above | 1 | Applied and Interdisciplinary Chemistry |
In budding yeast, SIR proteins are found at the silent mating type loci, telomeres, and at the rDNA locus. At the silent mating type loci and at the telomeres, SIR proteins participate in transcriptional silencing of genes within their domain of localization. At the rDNA locus, SIR proteins are thought to primarily be important for repressing recombination between rDNA repeats rather than for suppressing transcription. | 1 | Applied and Interdisciplinary Chemistry |
Soil texture influences the soil chemistry pertaining to the soil's ability to maintain its structure, the restriction of water flow and the contents of the particles in the soil. Soil texture considers all particle types and a soil texture triangle is a chart that can be used to calculate the percentages of each particle type adding up to total 100% for the soil profile. These soil separates differ not only in their sizes but also in their bearing on some of the important factors affecting plant growth such as soil aeration, work ability, movement and availability of water and nutrients. | 0 | Theoretical and Fundamental Chemistry |
The Eagle effect, Eagle phenomenon, or paradoxical zone phenomenon, named after Harry Eagle who first described it, originally referred to the paradoxically reduced antibacterial effect of penicillin at high doses, though recent usage generally refers to the relative lack of efficacy of beta lactam antibacterial drugs on infections having large numbers of bacteria. The former effect is paradoxical because the effectiveness of an antibiotic generally rises with increasing drug concentration.
__TOC__ | 1 | Applied and Interdisciplinary Chemistry |
The next major change in shutter hardware coincided with the American Civil War era. Heavy presses and punches were in use in factories around the country and a maturing rail transportation system opened inland areas for the products of the factories. Iron was the norm up until that time – steel had been expensive to produce. Hardware makers were quick to take advantage of this new material. They produced the first of the "butt" and "H" or "Parliament" style lift-off hinges. Quick and easy to produce and strong enough to hold heavy shutters, they found favor in the new construction of the period.
Around 1880 the first examples of "New York" style hardware appeared. Plate steel elements were assembled by unskilled labor in sprawling factories. This hardware style evolved into the many imported forms seen today. It provided the ability to surface mount hinges and tie the wooden elements of the shutters together, and also allowed for smaller and less expensive window and shutter elements. About this time the first commercially produced "S" style tie-backs were seen – manufactured by Stanley Works in Connecticut. Historically an "S" is a very difficult form to forge. Stanley forged the first simple styles for commercial consumption but it wasn't until the 1930s that they started to stamp them. | 1 | Applied and Interdisciplinary Chemistry |
PI3K/ AKT/mTOR pathway is a central regulator of ovarian cancer. PIM kinases are over expressed in many types of cancers and they also contribute to the regulation of ovarian cancer. PIM are directly and indirectly found to activate mTOR and its upstream effectors like AKT. Besides, PIM kinases can cause phosphorylation of IRS, which can alter PI3K. This indicates the close interaction of PIM with PI3K/ AKT/mTOR cascade and its components. Similarly, AKT has also been reported to perform the BAD phosphorylation in OC cells. PIM and the PI3K/AKT/mTOR network both can inhibit the P21 and P27 expressions in OC cells. These data suggest a strong possibility of interaction and relevance of PIM kinases and the PI3K/AKT/mTOR network in the regulation of ovarian cancer. However, targeting this pathway in ovarian cancer has been challenging with several trials failing to achieve sufficient clinical benefit. | 1 | Applied and Interdisciplinary Chemistry |
Duplex sequencing tagged adapters can be used in combination with the majority of NGS adapters. In the figures and workflow section of this article, Illumina sequencing adapters are used as an example following the original published protocol. | 1 | Applied and Interdisciplinary Chemistry |
Xenon dioxide, or xenon(IV) oxide, is a compound of xenon and oxygen with formula XeO which was synthesized in 2011. It is synthesized at 0 °C by hydrolysis of xenon tetrafluoride in aqueous sulfuric acid: | 0 | Theoretical and Fundamental Chemistry |
It is assumed that the absorbance of each species is proportional to the concentration of that species, according to the Beer–Lambert law.
where λ is a wavelength, is the optical path length of the cuvette which contains the solution of the N compounds (chromophores),
is the molar absorbance (also known as the extinction coefficient) of the ith chemical species at the wavelength λ, c is its concentration. When the concentrations have been calculated as above and absorbance has been measured for samples with various concentrations of host and guest, the Beer–Lambert law provides a set of equations, at a given wavelength, that which can be solved by a linear least-squares process for the unknown extinction coefficient values at that wavelength. | 0 | Theoretical and Fundamental Chemistry |
An interesting feature of these phases is that both polar and nonpolar compounds can be retained over some range of mobile phase composition (organic/aqueous). The retention mechanism of polar compounds has recently been shown to be the result of the formation of a hydroxide layer on the surface of the silica hydride. Thus positively charged analytes are attracted to the negatively charged surface and other polar analytes are likely to be retained through displacement of hydroxide or other charged species on the surface. This property distinguishes it from a pure HILIC (hydrophilic interaction chromatography) columns where separation by polar differences is obtained through partitioning into a water-rich layer on the surface, or a pure RP stationary phase on which separation by nonpolar differences in solutes is obtained with very limited secondary mechanisms operating.
Another important feature of the hydride-based phases is that for many analyses it is usually not necessary to use a high pH mobile phase to analyze polar compounds such as bases. The aqueous component of the mobile phase usually contains from 0.1 to 0.5% formic or acetic acid, which is compatible with detector techniques that include mass spectral analysis. | 0 | Theoretical and Fundamental Chemistry |
Davis and Bahcall continued their work to understand where they may have gone wrong or what they were missing, along with other astrophysicists who also did their own research on the subject. Many reviewed and redid Bahcall's calculations in the 1970s and 1980s, and although there was more data making the results more precise, the difference still remained. Davis even repeated his experiment changing the sensitivity and other factors to make sure nothing was overlooked, but he found nothing and the results still showed "missing" neutrinos. By the end of the 1970s, the widely expected result was the experimental data yielded about 39% of the calculated number of neutrinos. In 1969, Bruno Pontecorvo, an Italo-Russian astrophysicist, suggested a new idea that maybe we do not quite understand neutrinos like we think we do, and that neutrinos could change in some way, meaning the neutrinos that are released by the sun changed form and were no longer neutrinos the way neutrinos were thought off by the time they reached Earth where the experiment was conducted. This theory Pontecorvo had would make sense in accounting for the discrepancy between the experimental and theoretical results that persisted. | 0 | Theoretical and Fundamental Chemistry |
Eukaryotic transcription is more complex than prokaryotic transcription. For instance, in eukaryotes the genetic material (DNA), and therefore transcription, is primarily localized to the nucleus, where it is separated from the cytoplasm (in which translation occurs) by the nuclear membrane. This allows for the temporal regulation of gene expression through the sequestration of the RNA in the nucleus, and allows for selective transport of mature RNAs to the cytoplasm. Bacteria do not have a distinct nucleus that separates DNA from ribosome and mRNA is translated into protein as soon as it is transcribed. The coupling between the two processes provides an important mechanism for prokaryotic gene regulation.
At the level of initiation, RNA polymerase in prokaryotes (bacteria in particular) binds strongly to the promoter region and initiates a high basal rate of transcription. No ATP hydrolysis is needed for the close-to-open transition, promoter melting is driven by binding reactions that favor the melted conformation. Chromatin greatly impedes transcription in eukaryotes. Assembly of large multi-protein preinitiation complex is required for promoter-specific initiation. Promoter melting in eukaryotes requires hydrolysis of ATP. As a result, eukaryotic RNA polymerases exhibit a low basal rate of transcription initiation. | 1 | Applied and Interdisciplinary Chemistry |
In phase I, a variety of enzymes act to introduce reactive and polar groups into their substrates. One of the most common modifications is hydroxylation catalysed by the cytochrome P-450-dependent mixed-function oxidase system. These enzyme complexes act to incorporate an atom of oxygen into nonactivated hydrocarbons, which can result in either the introduction of hydroxyl groups or N-, O- and S-dealkylation of substrates. The reaction mechanism of the P-450 oxidases proceeds through the reduction of cytochrome-bound oxygen and the generation of a highly-reactive oxyferryl species, according to the following scheme:
:O + NADPH + H + RH → NADP + HO + ROH
Phase I reactions (also termed nonsynthetic reactions) may occur by oxidation, reduction, hydrolysis, cyclization, decyclization, and addition of oxygen or removal of hydrogen, carried out by mixed function oxidases, often in the liver. These oxidative reactions typically involve a cytochrome P450 monooxygenase (often abbreviated CYP), NADPH and oxygen. The classes of pharmaceutical drugs that utilize this method for their metabolism include phenothiazines, paracetamol, and steroids. If the metabolites of phase I reactions are sufficiently polar, they may be readily excreted at this point. However, many phase I products are not eliminated rapidly and undergo a subsequent reaction in which an endogenous substrate combines with the newly incorporated functional group to form a highly polar conjugate.
A common Phase I oxidation involves conversion of a C-H bond to a C-OH. This reaction sometimes converts a pharmacologically inactive compound (a prodrug) to a pharmacologically active one. By the same token, Phase I can turn a nontoxic molecule into a poisonous one (toxification). Simple hydrolysis in the stomach is normally an innocuous reaction, however there are exceptions. For example, phase I metabolism converts acetonitrile to HOCHCN, which rapidly dissociates into formaldehyde and hydrogen cyanide.
Phase I metabolism of drug candidates can be simulated in the laboratory using non-enzyme catalysts. This example of a biomimetic reaction tends to give products that often contains the Phase I metabolites. As an example, the major metabolite of the pharmaceutical trimebutine, desmethyltrimebutine (nor-trimebutine), can be efficiently produced by in vitro oxidation of the commercially available drug. Hydroxylation of an N-methyl group leads to expulsion of a molecule of formaldehyde, while oxidation of the O-methyl groups takes place to a lesser extent. | 1 | Applied and Interdisciplinary Chemistry |
Each of these mechanisms can act in isolation or in combination with others. Assuming each effect is independent, the observed line profile is a convolution of the line profiles of each mechanism. For example, a combination of the thermal Doppler broadening and the impact pressure broadening yields a Voigt profile.
However, the different line broadening mechanisms are not always independent. For example, the collisional effects and the motional Doppler shifts can act in a coherent manner, resulting under some conditions even in a collisional narrowing, known as the Dicke effect. | 0 | Theoretical and Fundamental Chemistry |
The ability of the immune system to recognize molecules that are broadly shared by pathogens is, in part, due to the presence of immune receptors called toll-like receptors (TLRs) that are expressed on the membranes of leukocytes including dendritic cells, macrophages, natural killer cells, cells of the adaptive immunity T cells, and B cells, and non-immune cells (epithelial and endothelial cells, and fibroblasts).
The binding of ligands - either in the form of adjuvant used in vaccinations or in the form of invasive moieties during times of natural infection - to the TLR marks the key molecular events that ultimately lead to innate immune responses and the development of antigen-specific acquired immunity.
Upon activation, TLRs recruit adaptor proteins (proteins that mediate other protein-protein interactions) within the cytosol of the immune cell to propagate the antigen-induced signal transduction pathway. These recruited proteins are then responsible for the subsequent activation of other downstream proteins, including protein kinases (IKKi, IRAK1, IRAK4, and TBK1) that further amplify the signal and ultimately lead to the upregulation or suppression of genes that orchestrate inflammatory responses and other transcriptional events. Some of these events lead to cytokine production, proliferation, and survival, while others lead to greater adaptive immunity. If the ligand is a bacterial factor, the pathogen might be phagocytosed and digested, and its antigens presented to CD4+ T cells.
In the case of a viral factor, the infected cell may shut off its protein synthesis and may undergo programmed cell death (apoptosis). Immune cells that have detected a virus may also release anti-viral factors such as interferons.
Toll-like receptors have also been shown to be an important link between innate and adaptive immunity through their presence in dendritic cells. Flagellin, a TLR5 ligand, induces cytokine secretion on interacting with TLR5 on human T cells. | 1 | Applied and Interdisciplinary Chemistry |
MgCu can be prepared by hydrogenation of MgCu or the reaction of magnesium hydride and metallic copper at elevated temperature and pressure:
: 2 MgCu + 3 H → 3 MgH + MgCu
: MgH + 2 Cu → MgCu + H
MgCu can also be prepared by reacting of stoichiometric amounts of metals at about 380 °C in the presence of excess copper. | 1 | Applied and Interdisciplinary Chemistry |
Charles Darwin was the first to observe the transport of dust particles but Louis Pasteur was the first to research microbes and their activity within the air. Prior to Pasteur’s work, laboratory cultures were used to grow and isolate different bioaerosols.
Since not all microbes can be cultured, many were undetected before the development of DNA-based tools. Pasteur also developed experimental procedures for sampling bioaerosols and showed that more microbial activity occurred at lower altitudes and decreased at higher altitudes. | 0 | Theoretical and Fundamental Chemistry |
For each element, the following table shows the spectral lines which appear in the visible spectrum at about 400-700 nm. | 0 | Theoretical and Fundamental Chemistry |
Many of the crystallographic point groups share the same internal structure. For example, the point groups , 2, and m contain different geometric symmetry operations, (inversion, rotation, and reflection, respectively) but all share the structure of the cyclic group C. All isomorphic groups are of the same order, but not all groups of the same order are isomorphic. The point groups which are isomorphic are shown in the following table:
This table makes use of cyclic groups (C, C, C, C, C), dihedral groups (D, D, D, D), one of the alternating groups (A), and one of the symmetric groups (S). Here the symbol " × " indicates a direct product. | 0 | Theoretical and Fundamental Chemistry |
A halogen bond is almost collinear with the halogen atom's other, conventional bond, but the geometry of the electron-charge donor may be much more complex.
* Multi-electron donors such as ethers and amines prefer halogen bonds collinear with the lone pair and donor nucleus.
* Pyridine derivatives tend to donate halogen bonds approximately coplanar with the ring, and the two angles are about 120°.
* Carbonyl, thiocarbonyl-, and selenocarbonyl groups, with a trigonal planar geometry around the Lewis donor atom, can accept one or two halogen bonds.
Anions are usually better halogen-bond acceptors than neutral species: the more dissociated an ion pair is, the stronger the halogen bond formed with the anion. | 0 | Theoretical and Fundamental Chemistry |
Levels of β-TG is used to index platelet activation. It is measured by ELISA in blood plasma or urine, and often in conjunction with PF4. | 1 | Applied and Interdisciplinary Chemistry |
The continuum in the spectrum is the light with wavelengths between the lines. Polarization in the continuum is due to Rayleigh scattering by neutral hydrogen atoms (H I) and Thomson scattering by free electrons. Most of the opacity in the sun is due to the hydride ion, H which however does not alter polarization. In 1950 Subrahmanyan Chandrasekhar came up with a solution for the degree of polarization due to scattering, and predicted 11.7% polarization at the limb of the Sun. But nowhere near this level is observed. What happens at the limb is that there is a forest of spicules poking out from the edge, so it is not possible to get parallel to such a rough surface.
For most of the solar disk the degree of linear polarization of the continuum is under 0.1%, but it rises to 1% at the limb. The polarization also depends strongly on the wavelength, and for near ultraviolet 3000 Å the light near the limb is 100 times more polarized than red light at 7000 Å. At the limit of the Balmer series a change happens where at shorter wavelengths more bound-bound Balmer series transitions cause more opacity. This extra opacity drops the polarization degree by a factor of two near 3746 Å. | 0 | Theoretical and Fundamental Chemistry |
During assembly of the bacteriophage (phage) T4 virion, the morphogenetic proteins encoded by the phage genes interact with each other in a characteristic sequence. Maintaining an appropriate balance in the amounts of each of these proteins produced during viral infection appears to be critical for normal phage T4 morphogenesis. Phage T4 encoded proteins that determine virion structure include major structural components, minor structural components and non-structural proteins that catalyze specific steps in the morphogenesis sequence | 1 | Applied and Interdisciplinary Chemistry |
Jet pumps are commonly used to extract water from water wells. The main pump, often a centrifugal pump, is powered and installed at ground level. Its discharge is split, with the greater part of the flow leaving the system, while a portion of the flow is returned to the jet pump installed below ground in the well. This recirculated part of the pumped fluid is used to power the jet. At the jet pump, the high-energy, low-mass returned flow drives more fluid from the well, becoming a low-energy, high-mass flow which is then piped to the inlet of the main pump.
Shallow well pumps are those in which the jet assembly is attached directly to the main pump and are limited to a depth of approximately 5-8m to prevent cavitation.
Deep well pumps are those in which the jet is located at the bottom of the well. The maximum depth for deep well pumps is determined by the inside diameter of and the velocity through the jet. The major advantage of jet pumps for deep well installations is the ability to situate all mechanical parts (e.g., electric/petrol motor, rotating impellers) at the ground surface for easy maintenance. The advent of the electrical submersible pump has partly replaced the need for jet type well pumps, except for driven point wells or surface water intakes. | 1 | Applied and Interdisciplinary Chemistry |
A prime mover is a machine that converts energy of various forms into energy of motion.
* Steam turbine plants use the dynamic pressure generated by expanding steam to turn the blades of a turbine. Almost all large non-hydro plants use this system. About 90 percent of all electric power produced in the world is through use of steam turbines.
* Gas turbine plants use the dynamic pressure from flowing gases (air and combustion products) to directly operate the turbine. Natural-gas fuelled (and oil fueled) combustion turbine plants can start rapidly and so are used to supply "peak" energy during periods of high demand, though at higher cost than base-loaded plants. These may be comparatively small units, and sometimes completely unmanned, being remotely operated. This type was pioneered by the UK, Princetown being the world's first, commissioned in 1959.
* Combined cycle plants have both a gas turbine fired by natural gas, and a steam boiler and steam turbine which use the hot exhaust gas from the gas turbine to produce electricity. This greatly increases the overall efficiency of the plant, and many new baseload power plants are combined cycle plants fired by natural gas.
* Internal combustion reciprocating engines are used to provide power for isolated communities and are frequently used for small cogeneration plants. Hospitals, office buildings, industrial plants, and other critical facilities also use them to provide backup power in case of a power outage. These are usually fuelled by diesel oil, heavy oil, natural gas, and landfill gas.
* Microturbines, Stirling engine and internal combustion reciprocating engines are low-cost solutions for using opportunity fuels, such as landfill gas, digester gas from water treatment plants and waste gas from oil production. | 1 | Applied and Interdisciplinary Chemistry |
The scalar approach defines flux density as a scalar-valued function of a direction and sense in space prescribed by the investigator at a point prescribed by the investigator. Sometimes this approach is indicated by the use of the term hemispheric flux. For example, an investigator of thermal radiation, emitted from the material substance of the atmosphere, received at the surface of the earth, is interested in the vertical direction, and the downward sense in that direction. This investigator thinks of a unit area in a horizontal plane, surrounding the prescribed point. The investigator wants to know the total power of all the radiation from the atmosphere above in every direction, propagating with a downward sense, received by that unit area. For the flux density scalar for the prescribed direction and sense, we may write
where with the notation above, indicates that the integration extends only over the solid angles of the relevant hemisphere, and denotes the angle between and the prescribed direction. The term is needed on account of Lambert's law. Mathematically, the quantity is not a vector because it is a positive scalar-valued function of the prescribed direction and sense, in this example, of the downward vertical. In this example, when the collected radiation is propagating in the downward sense, the detector is said to be "looking upwards". The measurement can be made directly with an instrument (such as a pyrgeometer) that collects the measured radiation all at once from all the directions of the imaginary hemisphere; in this case, Lambert-cosine-weighted integration of the spectral radiance (or specific intensity) is not performed mathematically after the measurement; the Lambert-cosine-weighted integration has been performed by the physical process of measurement itself. | 0 | Theoretical and Fundamental Chemistry |
In the 1980s, the company began piping wastewater up to 14 miles to evaporation ponds on or near Ivanpah Dry Lake, east of Interstate 15 near Nevada. This pipeline repeatedly ruptured during cleaning operations to remove mineral deposits called scale. The scale is radioactive because of the presence of thorium and radium, which occur naturally in the rare-earth ore. A federal investigation later found that some 60 spills—some unreported—occurred between 1984 and 1998, when the pipeline and chemical processing at the mine were shut down. In all, about 600,000 gallons of radioactive and other hazardous waste flowed onto the desert floor, according to federal authorities. By the end of the 1990s, Unocal was served with a cleanup order and a San Bernardino County district attorney's lawsuit. The company paid more than $1.4 million in fines and settlements. After preparing a cleanup plan and completing an extensive environmental study, Unocal in 2004 won approval of a county permit that allowed the mine to operate for another 30 years. The mine passed a key county inspection in 2007. | 1 | Applied and Interdisciplinary Chemistry |
Metathesis using Grubbs-type alkylidene complexes can be used to synthesize terminal carbido-containing complexes. One example is RuC(PCy)Cl with a Ru-C distance of 163 pm, typical for a triple bond. The complex can be obtained by metathesis of vinyl acetate to give [Ru(CH-p-CHMe)(PCy)Cl] results in a metastable Ru(Cl)(PCy)CHOAc complex, which eliminates acetic acid.
The "naked" carbido ligand is weakly basic, forming complexes with other metal centers. The C-M bond is typically found to be around 1.65 Å. The C NMR resonance values for the carbido carbons vary widely, but range from δ211-406. Another example of a terminal carbido complex is Li[MoC(NR2)3] (Mo-C distance of 172 pm), which forms upon deprotonation of the respective methylidyne precursor. | 0 | Theoretical and Fundamental Chemistry |
There are examples of a new class of compounds that, on the basis of their chemical formulae, would appear to be Zintl phases, e.g., KIn, which is metallic and paramagnetic. Molecular orbital calculations have shown that the anion is (In) and that the extra electron is distributed over the cations and, possibly, the anion antibonding orbitals. Another exception is the metallic InBi. InBi fulfills the Zintl phase requisite of element-element bonds but not the requisite of the polyanionic structure fitting a normal valence compound, i.e., the Bi–Bi polyanionic structure does not correspond to a normal valence structure such as the diamond Tl in NaTl. | 0 | Theoretical and Fundamental Chemistry |
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