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Carbon Action is an investor-led initiative which shows how companies in investment portfolios are managing carbon emissions and energy efficiency.
Over 300 investors with US$25 trillion in assets under management ask the world's highest emitting companies to take three specific actions in response to climate change:
* Make emissions reductions (year-on-year)
* Publicly disclose emission reduction targets
* Make ROI-positive investments in projects
CDP launched a new research series at the beginning of 2015, taking a sector by sector approach. | 2 | Environmental Chemistry |
;AIME
*Sir Henry Ayers foundation president, 1893
*Uriah Dudley foundation general secretary 1893–1897
*David Lauder Stirling (c. 1871 – 30 August 1949); president 1894, secretary 1906–1941 or later; also secretary, Victorian Chamber of Mines 1898–1945
*H. W. Ferd Kayser (mine manager Mount Bischoff Tin Mining Company), vice-president 1894, president 1898, 1899
*Alexander Montgomery (government geologist in New Zealand, Tasmania, and Western Australia), president 1895
*Ernest Lidgey geological surveyor in Victoria; conducted Australia's first geophysical surveys; president 1901
*Samuel Henry McGowan (c. 1845 – 13 May 1921), accountant specializing in gold mining companies, mayor of Bendigo 1899–1900; president 1902
*F. Danvers Power, lecturer at Sydney University, president 1897, 1904.
*Robert C. Sticht general manager, Mount Lyell Mining & Railway Company, president 1905, 1915, vice-president 1909
*G. D. Delprat (manager of the Broken Hill mine), president 1906
*Dr. Alfred William Howitt, C.M.G., F.G.S., the eminent naturalist, was president 1907
*Frank A. Moss, (general manager of Kalgurli Gold Mines), president 1907
*C. F. Courtney (general manager of the Sulphide Corporation), president 1908
*Richard Hamilton, (general manager of the Great Boulder Proprietary mine), president 1909, vice-president 1910
*G. A. Richard (of Mount Morgan, Queensland), president 1910
*Herman Carl Bellinger from US; mine manager, Cobar 1909–1914, president 1912
*James Hebbard (manager of the Central Mine, Broken Hill), president 1913
*John Warren (mining) (manager of Block 10, Broken Hill), vice-president 1894, president 1902
*Hyman Herman (director of the Victorian geological survey), joined 1897, president 1914, remained councillor to 1959.
*Robert Silvers Black, (general manager of Kalgurli Gold Mines), president 1917
*J. W. Sutherland metallurgist at Lake View Consols and Golden Horse Shoe gold mines; president 1918
*Professor D. B. Waters of Otago, New Zealand, vice-president 1917,1918 (absent for most of this period — he was with New Zealand Tunnelling Company in France).
;AIMM
*R. W. Chapman, vice-president 1906, president 1920
*Colin Fraser (later Sir Colin), president 1923
*H. W. Gepp, later Sir Herbert William Gepp, president 1924
*Ernest W. Skeats (professor of geology, University of Melbourne), vice-president 1924, president 1925
*David Lauder Stirling, general secretary 1922–45
*R. M. Murray (general manager, Mount Lyell Mining & Railway Company), president 1927
*Alfred Stephen Kenyon, treasurer 1897, secretary 1906, president 1928
*E. C. Andrews (New South Wales Government Geologist), president 1929
*William Edward Wainwright (general manager of Broken Hill South), president 1919, 1930, vice-president 1916–18, 1933, 1934
*Wiliam Harley Wainwright son of W. E. Wainwright, (chief metallurgist, BHP) life member
*Essington Lewis (managing director of BHP) vice-president 1932, president 1935
*Andrew Fairweather, president 1932 (succeeded W. E. Mainwright at Broken Hill South mine and as General Manager)
*Professor J. Neill Greenwood (dean of Melbourne University Faculty of Applied Science), president 1936,1937
*Donald Yates, superintendent of Broken Hill Associated Smelters Pty., president 1937
*Julius Kruttschnitt (general manager, Mount Isa Mines) president 1939
*Oliver H. Woodward (general manager, North Mine, Broken Hill) active in tunnelling operations WWI, president 1940
*Arthur H. P. Moline (1877–1965) (succeeded R. M. Murray as general manager, Mount Lyell, in 1944), president 1945
*Asdruebal James Keast (general manager, Zinc Corporation; Australian Aluminium Production Commission 1951–55), president 1946, vice-president 1947
*Frank R. Hockey / Francis Richard Hockey (general superintendent, BHP), president 1947, vice-president 1949,1950
*F. F. Espie / Frank Fancett Espie (general superintendent, Western Mining Corporation), president 1948
*Godfrey Bernard O'Malley, vice-president 1943–46
*Maurice Alan Edgar Mawby (director of exploration, Zinc Corporation, Limited), vice-president 1950,1951, president 1953,1954
*Ian Munro McLennan (General Manager, BHP), president 1951
*Beryl Elaine Jacka MBE, typist 1936; assistant general secretary 1945–52, secretary 1952–1976
*Gordon Colvin Lindesay Clark CMG | 8 | Metallurgy |
Lasso peptides are short peptides containing an N-terminal macrolactam macrocycle "ring" through which a linear C-terminal "tail" is threaded. Because of this threaded-loop topology, these peptides resemble lassos, giving rise to their name. They are a member of a larger class of amino-acid-based lasso structures. Additionally, lasso peptides are formally rotaxanes.
The N-terminal "ring" can be from 7 to 9 amino acids long and is formed by an isopeptide bond between the N-terminal amine of the first amino acid of the peptide and the carboxylate side chain of an aspartate or glutamate residue. The C-terminal "tail" ranges from 7 to 15 amino acids in length.
The first amino acid of lasso peptides is almost invariably glycine or cysteine, with mutations at this site not being tolerated by known enzymes. Thus, bioinformatics-based approaches to lasso peptide discovery have thus used this as a constraint. However, some lasso peptides were recently discovered that also contain serine or alanine as their first residue.
The threading of the lasso tail is trapped either by disulfide bonds between ring and tail cysteine residues (class I lasso peptides), by steric effects due to bulky residues on the tail (class II lasso peptides), or both (class III lasso peptides). The compact structure makes lasso peptides frequently resistant to proteases or thermal unfolding. | 1 | Biochemistry |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), and Valine (Val, V). | 1 | Biochemistry |
Phenolic compounds can act as protective agents, inhibitors, natural animal toxicants and pesticides against invading organisms, i.e. herbivores, nematodes, phytophagous insects, and fungal and bacterial pathogens. The scent and pigmentation conferred by other phenolics can attract symbiotic microbes, pollinators and animals that disperse fruits. | 0 | Organic Chemistry |
Zero-point energy is fundamentally related to the Heisenberg uncertainty principle. Roughly speaking, the uncertainty principle states that complementary variables (such as a particles position and momentum, or a fields value and derivative at a point in space) cannot simultaneously be specified precisely by any given quantum state. In particular, there cannot exist a state in which the system simply sits motionless at the bottom of its potential well, for then its position and momentum would both be completely determined to arbitrarily great precision. Therefore, the lowest-energy state (the ground state) of the system must have a distribution in position and momentum that satisfies the uncertainty principle, which implies its energy must be greater than the minimum of the potential well.
Near the bottom of a potential well, the Hamiltonian of a general system (the quantum-mechanical operator giving its energy) can be approximated as a quantum harmonic oscillator,
where is the minimum of the classical potential well.
The uncertainty principle tells us that
making the expectation values of the kinetic and potential terms above satisfy
The expectation value of the energy must therefore be at least
where is the angular frequency at which the system oscillates.
A more thorough treatment, showing that the energy of the ground state actually saturates this bound and is exactly , requires solving for the ground state of the system. | 7 | Physical Chemistry |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), and Valine (Val, V). | 1 | Biochemistry |
Hexamethylenetetramine is the base component to produce RDX and, consequently, C-4 as well as octogen (a co-product with RDX), hexamine dinitrate, hexamine diperchlorate and HMTD. | 0 | Organic Chemistry |
Butyllithium reacts with some organic bromides and iodides in an exchange reaction to form the corresponding organolithium derivative. The reaction usually fails with organic chlorides and fluorides:
: CHLi + RX → CHX + RLi (X = Br, I)
This lithium–halogen exchange reaction is useful for preparation of several types of RLi compounds, particularly aryl<nowiki/>lithium and some vinyl<nowiki/>lithium reagents. The utility of this method is significantly limited, however, by the presence in the reaction mixture of n-BuBr or n-BuI, which can react with the RLi reagent formed, and by competing dehydrohalogenation reactions, in which n-BuLi serves as a base:
:2 CHBr + RLi → 2 CHR + LiBr
:2 CHLi + R′CH=CHBr → 2 CH + R′C≡CLi + LiBr
These side reaction are significantly less important for RI than for RBr, since the iodine–lithium exchange is several orders of magnitude faster than the bromine–lithium exchange. For these reasons, aryl, vinyl and primary alkyl iodides are the preferred substrates, and t-BuLi rather than n-BuLi is usually used, since the formed t-BuI is immediately destroyed by the t-BuLi in a dehydrohalogenation reaction (thus requiring two equivalents of t-BuLi). Alternatively, vinyl lithium reagents can be generated by direct reaction of the vinyl halide (e.g. cyclohexenyl chloride) with lithium or by tin–lithium exchange (see next section). | 0 | Organic Chemistry |
Photochemical conversion occurs due to interactions between the chromophoric unit and residues in its vicinity. Glu-212 functions as a base that removes a proton from His-62 aiding in the cleavage of the His-62-Nα-Cα bond. Replacing Glu-212 with glutamine prevents photoconversion. At low pH, the yield of Eos involved in photoconversion is greatly increased as the fraction of molecules in the protonated form increases. The action spectrum for photoconversion is closely related to the action spectrum for Eos's protonated form. These observations suggest that the neutral form of the green chromophore, including a protonated Tyr-63 side chain, is the gateway structure for photoconversion. Proton ejection from the Tyr-63 phenyl side chain is an important event in the conversion mechanism where a proton is transferred from the His-62 imidazole, which is hydrogen-bonded to the Phe-61 carbonyl. The extra proton causes His-62 to donate a proton to the Phe-61 carbonyl forming a leaving group out of the peptide bond between His and Phe in the elimination reaction. The His-62 side chain is protonated during photoexcitation and assists the reaction by donating a proton to the Phe-61 carbonyl in the leaving group. After the backbone is cleaved, the hydrogen bond between His-62 and Phe-61 is reformed. When His-62 is replaced with other amino acids, EosFP loses its ability to photoconvert, providing evidence that His-62 is a necessary component of the photoconversion mechanism. The internal charge distribution of the green chromophore is altered during photo excitation to assist in the elimination reaction. | 1 | Biochemistry |
In most cases mesocrystals form nanoparticles in solution. These nanoparticles aggregate and arrange in crystallographic formation, without any additives. The main causes of this ordering are tensorial polarization forces and dipole fields. | 7 | Physical Chemistry |
Lidocaine, a local anesthetic, has multiple inhibitory actions on the receptor and analysis of the structure of lidocaine has identified the presence of a hydrophobic aromatic ring and a hydrophilic terminal amine. Diethylamine (DEA), a molecule that mimics the hydrophilic moiety of lidocaine by way of a positively charged amine, has been found to block the channel when the receptor is open restricting the flow of Na and K ions. 2,6-Dimethylaniline (DMA), a molecule that mimics the hydrophobic moiety of lidocaine, has been found to bind the receptor at inter-subunit crevices of the trans-membrane spanning domain thereby causing non-competitive inhibition and restricting the channel from opening.
Benzocaine and tetracaine are also local anesthetics that have an inhibitory effect on the muscle‐type nicotinic receptor. Benzocaine is a permanently uncharged species that inhibits the receptor by plugging the pore of the opened channel. Tetracaine is a permanently positively charged species. It can bind to the receptor at different sites in both the open and closed conformations. Both of these local anesthetics enhance nAChR desensitization. | 1 | Biochemistry |
Microalgae have gained attention in recent years due to several reasons including their greater sensitivity to pollutants than many other organisms. In addition, they occur abundantly in nature, they are an essential component in very many food webs, they are easy to culture and to use in assays and there are few if any ethical issues involved in their use.
Euglena gracilis is a motile, freshwater, photosynthetic flagellate. Although Euglena is rather tolerant to acidity, it responds rapidly and sensitively to environmental stresses such as heavy metals or inorganic and organic compounds. Typical responses are the inhibition of movement and a change of orientation parameters. Moreover, this organism is very easy to handle and grow, making it a very useful tool for eco-toxicological assessments. One very useful particularity of this organism is gravitactic orientation, which is very sensitive to pollutants. The gravireceptors are impaired by pollutants such as heavy metals and organic or inorganic compounds. Therefore, the presence of such substances is associated with random movement of the cells in the water column. For short-term tests, gravitactic orientation of E. gracilis is very sensitive.
Other species such as Paramecium biaurelia (see Paramecium aurelia) also use gravitactic orientation.
Automatic bioassay is possible, using the flagellate Euglena gracilis in a device which measures their motility at different dilutions of the possibly polluted water sample, to determine the EC (the concentration of sample which affects 50 percent of organisms) and the G-value (lowest dilution factor at which no-significant toxic effect can be measured). | 2 | Environmental Chemistry |
The simplest application of this technique is to assess whether a given protein binds to a region of interest within a DNA molecule. Polymerase chain reaction (PCR) amplify and label region of interest that contains a potential protein-binding site, ideally amplicon is between 50 and 200 base pairs in length. Add protein of interest to a portion of the labeled template DNA; a portion should remain separate without protein, for later comparison. Add a cleavage agent to both portions of DNA template. The cleavage agent is a chemical or enzyme that will cut at random locations in a sequence independent manner. The reaction should occur just long enough to cut each DNA molecule in only one location. A protein that specifically binds a region within the DNA template will protect the DNA it is bound to from the cleavage agent. Run both samples side by side on a polyacrylamide gel electrophoresis. The portion of DNA template without protein will be cut at random locations, and thus when it is run on a gel, will produce a ladder-like distribution. The DNA template with the protein will result in ladder distribution with a break in it, the "footprint", where the DNA has been protected from the cleavage agent.
Note: Maxam-Gilbert chemical DNA sequencing can be run alongside the samples on the polyacrylamide gel to allow the prediction of the exact location of ligand binding site. | 1 | Biochemistry |
Scintillons are not identical in different species. Scintillons isolated from dinoflagellates belonging to the genus Pyrocystis such as P. lunula (previously Dissodinium lunula) or P. noctiluca are less dense than those of L. polyedra and do not contain LBP. Little is known about the structure or composition of scintillons in species other than L. polyedra. | 1 | Biochemistry |
The composition of gases present in the soils pores, referred to commonly as the soil atmosphere or atmosphere of the soil, is similar to that of the Earths atmosphere. Unlike the atmosphere, moreover, soil gas composition is less stagnant due to the various chemical and biological processes taking place in the soil. The resulting changes in composition from these processes can be defined by their variation time (i.e. daily vs. seasonal). Despite this spatial- and temporal-dependent fluctuation, soil gases typically boast greater concentrations of carbon dioxide and water vapor in comparison to the atmosphere. Furthermore, concentration of other gases, such as methane and nitrous oxide, are relatively minor yet significant in determining greenhouse gas flux and anthropogenic impact on soils. | 9 | Geochemistry |
Methane clathrate, also known commonly as methane hydrate, is a form of water ice that contains a large amount of methane within its crystal structure. Potentially large deposits of methane clathrate have been found under sediments on the ocean floors of the Earth, although the estimates of total resource size given by various experts differ by many orders of magnitude, leaving doubt as to the size of methane clathrate deposits (particularly in the viability of extracting them as a fuel resource). Indeed, cores of greater than 10 centimeters' contiguous depth had only been found in three sites as of 2000, and some resource reserve size estimates for specific deposits/locations have been based primarily on seismology. The sudden release of large amounts of natural gas from methane clathrate deposits in runaway climate change could be a cause of past, future, and present climate changes.
In the Arctic ocean, clathrates can exist in shallower water stabilized by lower temperatures rather than higher pressures; these may potentially be marginally stable much closer to the surface of the sea-bed, stabilized by a frozen lid of permafrost preventing methane escape. The so-called self-preservation phenomenon has been studied by Russian geologists starting in the late 1980s. This metastable clathrate state can be a basis for release events of methane excursions, such as during the interval of the Last Glacial Maximum. A study from 2010 concluded with the possibility for a trigger of abrupt climate warming based on metastable methane clathrates in the East Siberian Arctic Shelf (ESAS) region. | 6 | Supramolecular Chemistry |
Electrometallurgy involves metallurgical processes that take place in some form of electrolytic cell. The most common types of electrometallurgical processes are electrowinning and electro-refining. Electrowinning is an electrolysis process used to recover metals in aqueous solution, usually as the result of an ore having undergone one or more hydrometallurgical processes. The metal of interest is plated onto the cathode, while the anode is an inert electrical conductor. Electro-refining is used to dissolve an impure metallic anode (typically from a smelting process) and produce a high purity cathode. Fused salt electrolysis is another electrometallurgical process whereby the valuable metal has been dissolved into a molten salt which acts as the electrolyte, and the valuable metal collects on the cathode of the cell. The fused salt electrolysis process is conducted at temperatures sufficient to keep both the electrolyte and the metal being produced in the molten state. The scope of electrometallurgy has significant overlap with the areas of hydrometallurgy and (in the case of fused salt electrolysis) pyrometallurgy. Additionally, electrochemical phenomena play a considerable role in many mineral processing and hydrometallurgical processes. | 8 | Metallurgy |
A library is often prepared by random fragmentation of DNA and ligation of common adaptor sequences. However, the generated short reads challenge the identification of structural variants, such as indels, translocations, and duplication. Large regions of simple repeats can further complicate the alignment. Alternatively, a jumping library can be used with NGS for the mapping of structural variation and scaffolding of de novo assemblies.
Jumping libraries can be categorized according to the length of the incorporated DNA fragments. | 1 | Biochemistry |
Deane Judd was very interested the effect of light polarization and degree of diffusion on the appearance of objects. He made important contributions to the fields of colorimetry, color discrimination, color order, and color vision. Judd defined the scattering power for a sample as , where is the particle diameter. This is consistent with the belief that the scattering from a single particle is conceptually more important than the derived coefficients.
The above Kubelka–Munk equation can be resolved for the ratio in terms of . This led to a very early (perhaps the first) use of the term "remission" in place of "reflectance" when Judd defined a "remission function" as , where and are absorption and scattering coefficients, which replace and in the Kubelka–Munk equation above. Judd tabulated the remission function as a function of percent reflectance from an infinitely thick sample. This function, when used as a measure of absorption, was sometimes referred to as "pseudo-absorbance", a term which has been used later with other definitions as well. | 7 | Physical Chemistry |
Traumatic brain injury is a major neurological disorder when the brain is injured by traumatic force such as a bluent trauma or blast over-pressure wave.
For the disorders of central nervous system, the neuronal cell body-located Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and Glial fibrillary acidic protein (GFAP) are the first-in-class FDA cleared blood-based biomarker test for mild traumatic brain injury (TBI) with potential brain lesions. These tandem biomarkers were first discovered by Dr. Kevin K. Wang and Dr. Ronald. L. Hayes’ neuroscience laboratories at the McKnight Brain Institute of University of Florida from 2003-2007). Here, traumatic brain injury (TBI) blood-based biomarker test consisted of measuring the levels of neuronal (UCH-L1) and astroglial GFAP to aid in the diagnosis of the presence of cranial lesion(s) among moderate to mild TBI patients that is(are) otherwise only diagnosable with the use of a CT scan of the head.
Banyan Biomarkers, Inc., a company co-founded by Drs. Wang, Hayes and Nancy Denslow developed an optimized sandwich chemiluminescent ELISA for UCH-L1/GFAP, termed Brain Trauma Indicator™ (BTI); it contains two kits - one for each of the two biomarkers as chemiluminescence assays on the Synergy 2 Multi-mode Reader (BioTek). These assays were the basis of a pivotal TBI clinical trial called ALERT-TBI (ClinicalTrials.gov #NCT01426919). Over 1,900 adult TBI subjects with a Glasgow Coma Scale of (GCS) 9-15 (mind TBI) were recruited with blood samples drawn within 12 hours of injury to determine if the UCH-L1/GFAP tandem test can aid in the diagnosis of ta presence a cranial lesion that is otherwise only diagnosable with the use of a CT scan of the head. The results of the study show BTI has high sensitivity (97.6%) and negative predictive value (NPV) (99.6%). In February, 2018, FDA cleared the use the BTI for this mild TBI indication. | 1 | Biochemistry |
Hemoglobin acts to transport oxygen which the body receives to all body tissue via blood vessels. Over time, when red blood cells need to be replenished, the hemoglobin is broken down in the spleen; it breaks down into two parts: heme group consisting of iron and bile and protein fraction. While protein and iron are utilized to renew red blood cells, pigments that make up the red color in blood are deposited into the bile to form bilirubin. Jaundice leads to raised bilirubin levels that in turn negatively remove elastin-rich tissues. Jaundice may be noticeable in the sclera of the eyes at levels of about 2 to 3 mg/dl (34 to 51 μmol/L), and in the skin at higher levels.
Jaundice is classified, depending upon whether the bilirubin is free or conjugated to glucuronic acid, into conjugated jaundice or unconjugated jaundice. | 1 | Biochemistry |
While a reaction may exhibit one set of kinetic behavior at early conversion, that behavior may change due to:
* changes in catalyst resting state influenced by changing substrate concentrations
* multiple or changing mechanisms influenced by substrate or product concentrations
* catalyst activation (an initiation period)
* product inhibition
* irreversible (or reversible) catalyst death
In the case of saturation kinetics described above, provided that [A] is not present in a large excess relative to [B], saturation conditions will only apply at the beginning of the reaction. As the substrate is consumed, the concentration decreases and eventually [A] is no longer sufficient to completely overwhelm [Cat]. This is manifested by a gradual change in rate from 0-order to some higher (i.e. 1st, 2nd, etc.) order in [A]. This can also be described as a change in catalyst resting state from the bound form to the unbound form over the course of the reaction.
In addition to simply slowing the reaction, a change in catalyst resting state over the course of the reaction may result in competing paths or processes. Multiple mechanisms may be present to access the product, in which case the order in catalyst or substrate may change depending on the conditions or point in the reaction. A particularly useful probe for changes in reaction mechanism involves examination of the normalized reaction rate vs. catalyst loading at multiple, fixed conversion points. Note that the normalized reaction rate:
:k =
adjusts for the consumption of substrate over the course of the reaction, so only rate changes due to catalyst loading will be observed. A linear dependence on catalyst loading for a given conversion is indicative of a first order dependence on catalyst at that conversion, and one can similarly imagine the non-linear plots resulting from higher order dependence. Changes in the linearity or non-linearity from one set of conversion points to another are indicative of changes in the dependence on catalyst over the course of the reaction. Conversely, changes in the linearity or non-linearity of regions of the plot conserved over multiple conversion points (i.e. at 30, 50, and 70%) are indicative of a change in the dependence on catalyst based on the absolute catalyst concentration.
Catalyst interactions with multiple components of a reaction mixture can lead to a complex kinetic dependence. While off-cycle catalyst-substrate or catalyst-product interactions are generally considered "poisonous" to the system (certainly the case in the event of irreversible complexation) cases do exist in which the off-cycle species actually protects the catalyst from permanent deactivation.
In either case, it is often essential to understand the role of the catalyst resting state. | 7 | Physical Chemistry |
A codon table can be used to translate a genetic code into a sequence of amino acids. The standard genetic code is traditionally represented as an RNA codon table, because when proteins are made in a cell by ribosomes, it is messenger RNA (mRNA) that directs protein synthesis. The mRNA sequence is determined by the sequence of genomic DNA. In this context, the standard genetic code is referred to as translation table 1. It can also be represented in a DNA codon table. The DNA codons in such tables occur on the sense DNA strand and are arranged in a 5-to-3 direction. Different tables with alternate codons are used depending on the source of the genetic code, such as from a cell nucleus, mitochondrion, plastid, or hydrogenosome.
There are 64 different codons in the genetic code and the below tables; most specify an amino acid. Three sequences, UAG, UGA, and UAA, known as stop codons, do not code for an amino acid but instead signal the release of the nascent polypeptide from the ribosome. In the standard code, the sequence AUG—read as methionine—can serve as a start codon and, along with sequences such as an initiation factor, initiates translation. In rare instances, start codons in the standard code may also include GUG or UUG; these codons normally represent valine and leucine, respectively, but as start codons they are translated as methionine or formylmethionine.
The first table—the standard table—can be used to translate nucleotide triplets into the corresponding amino acid or appropriate signal if it is a start or stop codon. The second table, appropriately called the inverse, does the opposite: it can be used to deduce a possible triplet code if the amino acid is known. As multiple codons can code for the same amino acid, the International Union of Pure and Applied Chemistry's (IUPAC) nucleic acid notation is given in some instances. | 1 | Biochemistry |
Cold black oxide, also known as room temperature black oxide, is applied at a temperature of . It is not an oxide conversion coating, but rather a deposited copper selenide (CuSe) compound. Cold black oxide is convenient for in-house blackening. This coating produces a similar color to the one the oxide conversion does, but tends to rub off easily and offers less abrasion resistance. The application of oil, wax, or lacquer brings the corrosion resistance up to par with the hot and mid-temperature. Applications for cold black oxide process include tooling and architectural finishing on steel. It is also known as cold bluing. | 7 | Physical Chemistry |
Of historical interest but not often of practical value, the first isocyanide, allyl isocyanide, was prepared by the reaction of allyl iodide and silver cyanide.
:RI + AgCN → RNC + AgI | 0 | Organic Chemistry |
Although arsenical bronze occurs in the archaeological record across the globe, the earliest artifacts so far known, dating from the 5th millennium BC, have been found on the Iranian plateau. Arsenic is present in a number of copper-containing ores (see table at right, adapted from Lechtman & Klein, 1999), and therefore some contamination of the copper with arsenic would be unavoidable. However, it is still not entirely clear to what extent arsenic was deliberately added to copper and to what extent its use arose simply from its presence in copper ores that were then treated by smelting to produce the metal.
Reconstructing a possible sequence of events in prehistory involves considering the structure of copper ore deposits, which are mostly sulphides. The surface minerals would contain some native copper and oxidized minerals, but much of the copper and other minerals would have been washed further into the ore body, forming a secondary enrichment zone. This includes many minerals such as tennantite, with their arsenic, copper and iron. Thus, the surface deposits would have been used first; with some work, deeper sulphidic ores would have been uncovered and worked, and it would have been discovered that the material from this level had better properties.
Using these various ores, there are four possible methods that may have been used to produce arsenical bronze alloys. These are:
* The direct addition of arsenic-bearing metals or ores such as realgar to molten copper. This method, although possible, lacks evidence.
* The reduction of antimony-bearing copper arsenates or fahlore to produce an alloy high in arsenic and antimony. This is entirely practicable.
* The reduction of roasted copper sulfarsenides such as tennantite and enargite. This method would result in the production of toxic fumes of arsenous oxide and the loss of much of the arsenic present in the ores.
* The co-smelting of oxidic and sulphidic ores such as malachite and arsenopyrite together. This method has been demonstrated to work well, with little in the way of dangerous fumes given off during it, because of the reactions together among the different minerals.
Furthermore, greater sophistication of metal workers is suggested by Thornton et al. They suggest that iron arsenide was deliberately produced as part of the copper-smelting process, to be traded and used to make arsenical bronze elsewhere by addition to molten copper.
Artifacts made of arsenical bronze cover the complete spectrum of metal objects, from axes to ornaments. The method of manufacture involved heating the metal in crucibles, and casting it into moulds made of stone or clay. After solidifying, it would be polished or, in the case of axes and other tools, work-hardened by beating the working edge with a hammer, thinning out the metal and increasing its strength. Finished objects could also be engraved or decorated as appropriate. | 8 | Metallurgy |
A variety of geologic and environmental settings have been proposed for an origin of life. These theories are often in competition with one another as there are many differing views of prebiotic compound availability, geophysical setting, and early life characteristics. The first organism on Earth likely looked different from LUCA. Between the first appearance of life and where all modern phylogenies began branching, an unknown amount of time passed. Within this time, unknown gene transfer, extinctions, and evolutions may have occurred, creating adaptations for a more diverse amount of environmental niches. One notable shifts is the one from an RNA-based to an RNA-DNA-protein world. There is more known about LUCA than the first organisms due to genomic reconstructions based on modern phylogenies.
The most popular hypotheses for settings in which an origin of life are possible are deep sea hydrothermal vents and surface bodies of water. Surface waters can be broken down into hot springs, moderate temperature lakes and ponds, and cold settings. | 9 | Geochemistry |
S1 end mapping - S1 nuclease - satellite DNA - screening - SDS-PAGE - secondary structure - selection - selenium responsive proteins - sense strand - sequence - sequence motif - sequence polymorphism - sequence-tagged site - sequential epitope - severe combined immunodeficiency - sex chromosome - sex-linked - Shine-Dalgarno sequence - shotgun cloning - shotgun cloning or sequencing - shotgun sequencing - shuttle vector - Siah interacting protein N-terminal domain - sickle-cell disease - side chain - sigma factor - signal peptidase - signal sequence - silent mutation - single nucleotide polymorphism - siRNA - site-directed mutagenesis - site-specific recombination - Slc22a21 - slot blot - SNP - Slc22a21 - SMCR2 - snRNA - snRNP - solution hybridization - somatic cells - Southern blot - southwestern blot - SP6 RNA polymerase - SpAB protein domain - spectral karyotype - splicing - Simple Sequence Repeats (SSR) - SPR domain - SQ2397 - SRG1 RNA - ST7-AS2 - ST7-OT3 - stable transfection - start codon - stem-loop - sticky end - stomoxyn - stop codon - streptavidin - stringency - structural motif - sub-cloning - substitution - succinate—citramalate CoA-transferase - suicide gene - sulfate-transporting ATPase - supercoil - SurE, survival protein E - Syb-prII-1 - syndrome - | 1 | Biochemistry |
The most studied is neurturin’s role in neurodegenerative disease like Parkinsons disease and Huntingtons, where several rat studies have implicated neurturin’s role in rescuing neurons. However, these results have never been observed in humans. Hirschsprung disease, a autosomal dominant genetic disorder, is characterized by complete absence of neuronal ganglion cells from the intestinal tract. Previous studies indicate a role of NRTN gene mutations in the disease. One study showed evidence that a mutation in the NRTN gene was not enough alone to cause onset of the disease, however when coupled with a mutation in the RET gene, disease was present in family members as well as the individual. A more recent study showed NRTN variants present in individuals with Hirschsprung disease. However, RET associated mutations were not found and in one variant, RET phosphorylation levels were reduced, which has the potential to have downstream effects on the proliferation and differentiation of neuronal crests. Also, high levels of expression of neurturin were found to be associated with nephroblastoma indicating the possible that the growth factor could be influencing differentiation. Lastly, a study also associated neurturin deficiency in mice with keratoconjunctivitis and dry eye. | 1 | Biochemistry |
Indirect immunofluorescence is one of the most commonly used tests for ANAs. Typically, HEp-2 cells are used as a substrate to detect the antibodies in human serum. Microscope slides are coated with HEp-2 cells and the serum is incubated with the cells. If the said and targeted antibodies are present then they will bind to the antigens on the cells; in the case of ANAs, the antibodies will bind to the nucleus. These can be visualised by adding a fluorescent tagged (usually FITC or rhodopsin B) anti-human antibody that binds to the antibodies. The molecule will fluoresce when a specific wavelength of light shines on it, which can be seen under the microscope. Depending on the antibody present in the human serum and the localisation of the antigen in the cell, distinct patterns of fluorescence will be seen on the HEp-2 cells. Levels of antibodies are analysed by performing dilutions on blood serum. An ANA test is considered positive if fluorescence is seen at a titre of 1:40/1:80. Higher titres are more clinically significant as low positives (≤1:160) are found in up to 20% of healthy individuals, especially the elderly. Only around 5% of the healthy population have ANA titres of 1:160 or higher. | 1 | Biochemistry |
On April 17, 2005, the Millstone Nuclear Power Plant in Connecticut was shut down due to a "false alarm" that indicated an unsafe pressure drop in the reactor's steam system when the steam pressure was actually nominal. The false alarm was caused by a tin whisker that short circuited the logic board responsible for monitoring the steam pressure lines in the power plant. | 8 | Metallurgy |
Halo ketones take part in several reaction types, especially since they are bifunctional, with two electrophilic sites (α-carbon and carbonyl carbon). In one manifestation of this duality, they are precursors to heterocycles. Thiazoles arise from reaction of chloroacetone with thioamides.2-Aminothiazoles are similarly produced by reaction of 2-chloroketones with thioureas. Pyrroles may be synthesized by reaction of halo ketones with dicarbonyls and ammonia in the Hantzsch pyrrole synthesis. | 0 | Organic Chemistry |
The interfacial (surface) tension, St, (dyne cm), can be calculated by applying the equation of capillary rise method (when the contact angle Ө → 0):<br />
where:
* h (cm) is the height of Hg column above the Hg meniscus in the capillary
* r (cm) is the radius of capillary
* g is the acceleration due to gravity
* d (g cm) is the Hg density
The circuit contains Hg electrode as the ideally polarizable electrode and a reference electrode as the non-polarizable electrode. Thus, when an external voltage is applied, only EM/S of Hg/solution fluid interface is changed. | 7 | Physical Chemistry |
RT-PCR can also be very useful in the insertion of eukaryotic genes into prokaryotes. Because most eukaryotic genes contain introns, which are present in the genome but not in the mature mRNA, the cDNA generated from a RT-PCR reaction is the exact (without regard to the error-prone nature of reverse transcriptases) DNA sequence that would be directly translated into protein after transcription. When these genes are expressed in prokaryotic cells for the sake of protein production or purification, the RNA produced directly from transcription need not undergo splicing as the transcript contains only exons. (Prokaryotes, such as E. coli, lack the mRNA splicing mechanism of eukaryotes). | 1 | Biochemistry |
In May 2010, an application of SNALPs to the Ebola Zaire virus made headlines, as the preparation was able to cure rhesus macaques when administered shortly after their exposure to a lethal dose of the virus, which can be up to 90% lethal to humans in sporadic outbreaks in Africa. The treatment used for rhesus macaques consisted of three siRNAs (staggered duplexes of RNA) targeting three viral genes. The SNALPs (around 81 nm in size here) were formulated by spontaneous vesiculation from a mixture of cholesterol, dipalmitoyl phosphatidylcholine, 3-N-[(ω-methoxy
poly(ethylene glycol)2000)carbamoyl]-1,2-dimyrestyloxypropylamine, and cationic 1,2-dilinoleyloxy-3-N,N-dimethylaminopropane.
In addition to the rhesus macaque application, SNALPs have also been proven to protect cavia porcellua from viremia and death when administered shortly after postexposure to ZEBOV. A polymerase (L) gene-specific siRNAs delivery system was imposed upon four genes associated with the viral genomic RNA in the ribonucleoprotein complex found within EBOV particles (three of which match the application above): NP, VP30, VP35, and the L protein. The SNALPs ranged from 71 – 84 nm in size and were composed of synthetic cholesterol, phospholipid DSPC, PEG lipid PEGC-DMA, and cationic lipid DLinDMA at the molar ratio of 48:20:2:30. The results confirm complete protection against viremia and death in guinea pigs when administered a SNALP-siRNA delivery system after diagnosis of the Ebola virus, thus proving this technology to be an effective treatment. Future studies will focus mainly upon evaluating the effects of siRNA ‘cocktails’ on EBOV genes to increase antiviral effects. | 1 | Biochemistry |
In 1962, Harvard professor Edward O. Wilson published one of the first concrete studies constructing the groundwork for the notion of trail pheromones. Claiming an odor trail is deposited by the sting apparatus of the hymenopteran Solenopsis saevissima which results in a pathway from the colony to a food source, this study encouraged further investigation of how this chemical is laid, how it affects communication between species within and outside of its own, the evolution of the semiochemical, etc. | 1 | Biochemistry |
In alphabetic order
* Alanine transaminase (ALT)
* Body fat percentage
* Body mass index
* Body temperature
* Blood pressure
* Blood sugar level
* Complete blood count
* Creatinine
* C-reactive protein (inflammation)
* Glial fibrillary acidic protein (GFAP)
* Heart rate
* Hematocrit (HCT)
* Hemoglobin (Hgb)
* Mean corpuscular volume (MCV)
* Red Blood Cell Count (RBC)
* Thyroid-stimulating hormone (TSH)
* Triglyceride
* Troponin (cardiac TN-T, Tn-I)
* Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1)
* Waist circumference
* Waist-to-hip ratio (WHR) | 1 | Biochemistry |
Termination is the process of breaking up the polymerase complex and ending the RNA strand. In eukaryotes using RNA Pol II, this termination is very variable (up to 2000 bases), relying on post transcriptional modification.
Little regulation occurs at termination, although it has been proposed newly transcribed RNA is held in place if proper termination is inhibited, allowing very fast expression of genes given a stimulus. This has not yet been demonstrated in eukaryotes. | 1 | Biochemistry |
Antibody elution is the process of removing antibodies that are attached to their targets, such as the surface of red blood cells. Techniques include using heat, a freeze-thaw cycle, ultrasound, acids or organic solvents. No single method is best in all situations. | 3 | Analytical Chemistry |
In genetics, an expressed sequence tag (EST) is a short sub-sequence of a cDNA sequence. ESTs may be used to identify gene transcripts, and were instrumental in gene discovery and in gene-sequence determination. The identification of ESTs has proceeded rapidly, with approximately 74.2 million ESTs now available in public databases (e.g. GenBank 1 January 2013, all species). EST approaches have largely been superseded by whole genome and transcriptome sequencing and metagenome sequencing.
An EST results from one-shot sequencing of a cloned cDNA. The cDNAs used for EST generation are typically individual clones from a cDNA library. The resulting sequence is a relatively low-quality fragment whose length is limited by current technology to approximately 500 to 800 nucleotides. Because these clones consist of DNA that is complementary to mRNA, the ESTs represent portions of expressed genes. They may be represented in databases as either cDNA/mRNA sequence or as the reverse complement of the mRNA, the template strand.
One can map ESTs to specific chromosome locations using physical mapping techniques, such as radiation hybrid mapping, HAPPY mapping, or FISH. Alternatively, if the genome of the organism that originated the EST has been sequenced, one can align the EST sequence to that genome using a computer.
The current understanding of the human set of genes () includes the existence of thousands of genes based solely on EST evidence. In this respect, ESTs have become a tool to refine the predicted transcripts for those genes, which leads to the prediction of their protein products and ultimately of their function. Moreover, the situation in which those ESTs are obtained (tissue, organ, disease state - e.g. cancer) gives information on the conditions in which the corresponding gene is acting. ESTs contain enough information to permit the design of precise probes for DNA microarrays that then can be used to determine gene expression profiles.
Some authors use the term "EST" to describe genes for which little or no further information exists besides the tag. | 1 | Biochemistry |
Mitigation of adverse impacts of runoff can take several forms:
* Land use development controls aimed at minimizing impervious surfaces in urban areas
* Erosion controls for farms and construction sites
* Flood control and retrofit programs, such as green infrastructure
* Chemical use and handling controls in agriculture, landscape maintenance, industrial use, etc.
Land use controls. Many world regulatory agencies have encouraged research on methods of minimizing total surface runoff by avoiding unnecessary hardscape. Many municipalities have produced guidelines and codes (zoning and related ordinances) for land developers that encourage minimum width sidewalks, use of pavers set in earth for driveways and walkways and other design techniques to allow maximum water infiltration in urban settings. An example of a local program specifying design requirements, construction practices and maintenance requirements for buildings and properties is in Santa Monica, California.
Erosion controls have appeared since medieval times when farmers realized the importance of contour farming to protect soil resources. Beginning in the 1950s these agricultural methods became increasingly more sophisticated. In the 1960s some state and local governments began to focus their efforts on mitigation of construction runoff by requiring builders to implement erosion and sediment controls (ESCs). This included such techniques as: use of straw bales and barriers to slow runoff on slopes, installation of silt fences, programming construction for months that have less rainfall and minimizing extent and duration of exposed graded areas. Montgomery County, Maryland implemented the first local government sediment control program in 1965, and this was followed by a statewide program in Maryland in 1970.
Flood control programs as early as the first half of the twentieth century became quantitative in predicting peak flows of riverine systems. Progressively strategies have been developed to minimize peak flows and also to reduce channel velocities. Some of the techniques commonly applied are: provision of holding ponds (also called detention basins or balancing lakes) to buffer riverine peak flows, use of energy dissipators in channels to reduce stream velocity and land use controls to minimize runoff.
Chemical use and handling. Following enactment of the U.S. Resource Conservation and Recovery Act (RCRA) in 1976, and later the Water Quality Act of 1987, states and cities have become more vigilant in controlling the containment and storage of toxic chemicals, thus preventing releases and leakage. Methods commonly applied are: requirements for double containment of underground storage tanks, registration of hazardous materials usage, reduction in numbers of allowed pesticides and more stringent regulation of fertilizers and herbicides in landscape maintenance. In many industrial cases, pretreatment of wastes is required, to minimize escape of pollutants into sanitary or stormwater sewers.
The U.S. Clean Water Act (CWA) requires that local governments in urbanized areas (as defined by the Census Bureau) obtain stormwater discharge permits for their drainage systems. Essentially this means that the locality must operate a stormwater management program for all surface runoff that enters the municipal separate storm sewer system ("MS4"). EPA and state regulations and related publications outline six basic components that each local program must contain:
* Public education (informing individuals, households, businesses about ways to avoid stormwater pollution)
* Public involvement (support public participation in implementation of local programs)
* Illicit discharge detection & elimination (removing sanitary sewer or other non-stormwater connections to the MS4)
* Construction site runoff controls (i.e. erosion and sediment controls)
* Post-construction (i.e. permanent) stormwater management controls
* Pollution prevention (e.g. improved chemical handling, including management of motor fuels and oil, fertilizers, pesticides and roadway deicers) and "good housekeeping" measures (e.g. system maintenance).
Other property owners which operate storm drain systems similar to municipalities, such as state highway systems, universities, military bases and prisons, are also subject to the MS4 permit requirements. | 2 | Environmental Chemistry |
* 2,2,2-Trichloroethyl chloroformate, pyridine or aqueous sodium hydroxide at ambient temperature
* Electrolysis
* Deprotection using zinc metal | 0 | Organic Chemistry |
The rate of hypothyroidism is around six times higher in people who take lithium. Low thyroid hormone levels in turn increase the likelihood of developing depression. People taking lithium thus should routinely be assessed for hypothyroidism and treated with synthetic thyroxine if necessary.
Because lithium competes with the antidiuretic hormone in the kidney, it increases water output into the urine, a condition called nephrogenic diabetes insipidus. Clearance of lithium by the kidneys is usually successful with certain diuretic medications, including amiloride and triamterene. It increases the appetite and thirst ("polydypsia") and reduces the activity of thyroid hormone (hypothyroidism). The latter can be corrected by treatment with thyroxine and does not require the lithium dose to be adjusted. Lithium is also believed to permanently affect renal function, although this does not appear to be common. | 1 | Biochemistry |
The tendency of a given chemical species to partition itself
preferentially between liquid and vapor phases is the Henry's law constant. There can be VLE data for mixtures of four or more components, but such a boiling-point diagram is hard to show in either tabular or graphical form. For such multi-component mixtures, as well as binary
mixtures, the vapor–liquid equilibrium data are represented in terms of values (vapor–liquid distribution ratios) defined by
where and are the mole fractions of component in the phases and respectively.
For Raoult's law
For modified Raoult's law
where is the activity coefficient, is the partial pressure and is the pressure.
The values of the ratio are correlated empirically or theoretically in terms of temperature, pressure and phase compositions in the form of equations, tables or graph such as the DePriester charts.
For binary mixtures, the ratio of the values for the two components is called the relative volatility denoted by
which is a measure of the relative ease or difficulty of separating the two components. Large-scale industrial distillation is rarely undertaken if the relative volatility is less than 1.05 with the volatile component being and the less volatile component being .
values are widely used in the design calculations of continuous distillation columns for distilling multicomponent mixtures. | 7 | Physical Chemistry |
A silencer is a sequence-specific element that induces a negative effect on the transcription of its particular gene. There are many positions in which a silencer element can be located in DNA. The most common position is found upstream of the target gene where it can help repress the transcription of the gene. This distance can vary greatly between approximately -20 bp to -2000 bp upstream of a gene. Certain silencers can be found downstream of a promoter located within the intron or exon of the gene itself. Silencers have also been found within the 3 prime untranslated region (3' UTR) of mRNA. | 1 | Biochemistry |
eIF-2 - eIF-2 kinase - electrochemical potential - electron - electron capture - electron configuration - electron microscopy - electron shell - electron transport chain - electron volt - electronegativity - electrophile - electrophoresis - electrophysiology - element - element symbol - ELISA - ELISPOT - embryo - embryonal development - emulsion - endergonic reaction - endodermis - endomembrane system - endoplasmic reticulum - endothelin receptor - endothelin-1 - energy decomposition cycles - energy level - enhancer - enkephalin - enthalpy - entomology - entropy - env gene product - environmental chemistry - enzyme - epidermal growth factor - epidermal growth factor receptor - epidiorite - epigenetics - epinephrine - equine gonadotropin - erbA gene - erbB gene - erbB-2 gene - erbB-2 receptor - erythropoietin - erythropoietin receptor - essential amino acid - ester - estradiol receptor - estrogen receptor - ethanol - ether - eukaryote - evolution - evolutionary biology - evolutionary developmental biology - evolutionary tree - excretion - exergonic reaction - exon - extracellular matrix protein - eye proteins | 1 | Biochemistry |
The order of ligands which possess cis-labilizing effects are as follows:
CO, AuPPh, H, SnPh, GePh, SO, NCH CO , NCO
Anionic ligands such as F, Cl, OH, and SH have particularly strong CO labilizing effects in complexes. This is because these ligands will stabilize the 16 e intermediate by electron donation from the p-pi lone pair donor orbital. Other sulfur-containing ligands, particularly thiobenzoate, are other examples of particularly useful CO cis-labilizing ligands, which can be explained by stabilization of the intermediate that results upon CO dissociation. This can be attributed to the partial interaction of the oxygen from the thiobenzoate and the metal, which can eliminate solvent effects that can occur during ligand dissociation in transition metal complexes.
Note that the strongest labilizing effects come from ligands that are weak sigma donors with virtually no pi-accepting behavior. The cis effect can be attributed to the role of ligand X in stabilizing the transition state. It has also been determined that labilizing X ligands do in fact strengthen the M-CO bond trans to X, which is hypothesized to be due to the weak pi-accepting and/or sigma donating behavior of ligand X. This lack of strong sigma donation/pi-accepting will allow the CO (a strong pi-acceptor) trans to ligand X to pull electron density toward it, strengthening the M-CO bond. This phenomenon is further supported by the evidence from extensive studies on the trans effect, which in turn shows how ligands that are actually strong sigma donors and pi-acceptors weaken the M-L bond trans to them. Since the cis and trans effects seem to have generally opposite trends, the electronic argument supports both phenomena. Further evidence for cis labilization of CO can be attributed to the CO ligands being in competition for the d, d, and d orbitals. This argument especially holds true when the X is a halogen. | 0 | Organic Chemistry |
The concentration of carbamate (HbCO2) was estimated in oxygenated and deoxygenated red blood cells of adult and fetal humans. The estimation was carried out at a constant pressure of carbon dioxide (PCO2 = 40 mm Hg) and varied pH levels of the serum. The bicarbonate concentration in the red cells was calculated using the Donnan ratio for chloride and bicarbonate ions. Based on this figure, the carbamate concentration was determined by subtracting the bicarbonate concentration and dissolved CO2 from the total CO2 concentration.
Deoxygenated fetal red cells contain more HbCO2 than deoxygenated adult red cells at a given pH value in the red cell. Upon oxygenation, HbCO2 decreased in both types of erythrocytes to values lower than in deoxygenated cells, at a constant pH. The fraction of oxylabile carbamate (-ΔHbCO2/ΔHbO2) at a red cell pH of 7·2 and a PCO2 of 40 mm Hg is 0·117 in fetal and 0·081 in adult erythrocytes.
The apparent carbamate equilibrium constants (Kc and Kz) were calculated from the fraction of moles carbamate formed per Hb monomer (moles CO2/mole Hbi). These constants can be used to estimate the carbamate concentration in normal adult and fetal blood.
In adult red cells, the first apparent dissociation constant of carbonic acid is significantly higher in oxygenated (-log10K1 = pK1 = 6·10) than in deoxygenated (pK'1 = 6·12) red cells, whereas in fetal red cells, the difference is smaller and statistically not significant.
Using the present results, the fractional contribution of carbamino compounds of hemoglobin to the amount of carbon dioxide exchanged during the respiratory cycle was computed for a given set of physiological conditions in arterial and mixed venous blood. The computed value was found to be 10·5% in adult and 19% in fetal blood. | 0 | Organic Chemistry |
*Bark, L. S. and Bark, S. M.; (1969). Thermometric titrimetry. International Series of Monographs in Analytical Chemistry Vol 33 Pergamon Press (Oxford) Library of Congress Catalog Card No. 68-57883
*Barthel, J.; (1975) Thermometric titrations. John Wiley & Sons, New York. Library of Congress Catalog Card No. 75-17503
*Eatough, D. J.; Christensen, J. J. & Izatt R. M. ; (1974) Experiments in thermometric titrimetry and titration calorimetry. Brigham Young University Press, Provo, Utah. Library of Congress Catalog Card 74-13074
*Grime, J. K.; (1985) Analytical solution calorimetry. John Wiley & Sons, New York. Library of Congress Catalog Card No. 84-28424
*Vaughan, G.A.; (1973) Thermometric and enthalpimetric titrimetry. Van Nostrand Reinhold Company (London) Library of Congress Catalog Card No. 79-186764 | 3 | Analytical Chemistry |
With improvements in measuring techniques such as atomic force microscopy, confocal microscopy, and scanning electron microscope, researchers were able to produce and image droplets at ever smaller scales. With the reduction in droplet size came new experimental observations of wetting. These observations confirmed that the modified Young's equation does not hold at the micro-nano scales. Jasper proposed that including a term in the variation of the free energy may be the key to solving the contact angle problem at such small scales. Given that the variation in free energy is zero at equilibrium:
The variation in the pressure at the free liquid-vapor boundary is due to Laplace pressure, which is proportional to the mean curvature. Solving the above equation for both convex and concave surfaces yields:
where
This equation relates the contact angle, a geometric property of a sessile droplet to the bulk thermodynamics, the energy at the three phase contact boundary, and the mean curvature of the droplet. For the special case of a sessile droplet on a flat surface ():
In the above equation, the first two terms are the modified Young's equation, while the third term is due to the Laplace pressure. This nonlinear equation correctly predicts the sign and magnitude of , the flattening of the contact angle at very small scales, and contact angle hysteresis. | 7 | Physical Chemistry |
Flash smelting () is a smelting process for sulfur-containing ores including chalcopyrite. The process was developed by Outokumpu in Finland and first applied at the Harjavalta plant in 1949 for smelting copper ore. It has also been adapted for nickel and lead production.
A second flash smelting system was developed by the International Nickel Company (INCO) and has a different concentrate feed design compared to the Outokumpu flash furnace. The Inco flash furnace has end-wall concentrate injection burners and a central waste gas off-take, while the Outokumpu flash furnace has a water-cooled reaction shaft at one end of the vessel and a waste gas off-take at the other end. While the INCO flash furnace at Sudbury was the first commercial use of oxygen flash smelting, fewer smelters use the INCO flash furnace than the Outokumpu flash furnace.
Flash smelting with oxygen-enriched air (the reaction gas) makes use of the energy contained in the concentrate to supply most of the energy required by the furnaces. The concentrate must be dried before it is injected into the furnaces and, in the case of the Outokumpu process, some of the furnaces use an optional heater to warm the reaction gas typically to 100–450 °C.
The reactions in the flash smelting furnaces produce copper matte, iron oxides and sulfur dioxide. The reacted particles fall into a bath at the bottom of the furnace, where the iron oxides react with fluxes, such as silica and limestone, to form a slag.
In most cases, the slag can be discarded, perhaps after some cleaning, and the matte is further treated in converters to produce blister copper. In some cases where the flash furnaces are fed with concentrate containing a sufficiently high copper content, the concentrate is converted directly to blister in a single Outokumpu furnace and further converting is unnecessary.
The sulfur dioxide produced by flash smelting is typically captured in a sulfuric acid plant, removing the major environmental effect of smelting.
Outotec, formerly the technology division of Outokumpu, now holds Outokumpu's patents to the technology and licenses it worldwide.
INCO was acquired by Brazil's Vale in 2006. | 8 | Metallurgy |
In 1802, Joseph Louis Gay-Lussac published results of similar, though more extensive experiments. Gay-Lussac credited Charles earlier work by naming the law in his honor. Gay-Lussac himself is credited with the law describing pressure, which he found in 1809. It states that the pressure exerted on a containers sides by an ideal gas is proportional to its temperature. | 7 | Physical Chemistry |
In the genus Lyophyllum the lamellae usually turn blue with the application of para-Dimethylaminobenzaldehyde (PDAB or pDAB). | 3 | Analytical Chemistry |
On some other instances in biology (not necessarily about cell signaling), the term "Scaffold protein" is used in a broader sense, where a protein holds several things together for any purpose.
;In chromosome folding: Chromosome scaffold has important role to hold the chromatin into compact chromosome. Chromosome scaffold is made of proteins including condensin, topoisomerase IIα and kinesin family member 4 (KIF4) Chromosome scaffold constituent proteins are also called scaffold protein.
;In enzymatic reaction: Large multifunctional enzymes that performs a series or chain of reaction in a common pathway, sometimes called scaffold proteins. such as Pyruvate dehydrogenase.
;In molecule shape formation: An enzyme or structural protein that holds several molecules together to hold them in proper spatial arrangement, such as Iron sulphur cluster scaffold proteins.
;Structural scaffold: In cytoskeleton and ECM, the molecules provide mechanical scaffold. Such as type 4 collagen | 1 | Biochemistry |
Auxiliary metabolic genes (AMGs) are found in many bacteriophages but originated in bacterial cells. AMGs modulate host cell metabolism during infection so that the phage can replicate more efficiently. For instance, bacteriophages that infect the abundant marine cyanobacteria Synechococcus and Prochlorococcus (cyanophages) carry AMGs that have been acquired from their immediate host as well as more distantly-related bacteria. Cyanophage AMGs support a variety of functions including photosynthesis, carbon metabolism, nucleic acid synthesis and metabolism. AMGs also have broader ecological impacts beyond their host including their influence on biogeochemical cycling. | 1 | Biochemistry |
The metal-dependent Fdh's feature Mo or W at their active sites. These active sites resemble the motif seen in DMSO reductase, with two molybdopterin cofactors bound to Mo/W in a bidentate fashion. The fifth and sixth ligands are sulfide and either cysteinate or selenocysteinate.
The mechanism of action appears to involve 2e redox of the metal centers, induced by hydride transfer from formate and release of carbon dioxide:
In this scheme, represents the four thiolate-like ligands provided by the two dithiolene cofactors, the molybdopterins. The dithiolene and cysteinyl/selenocysteinyl ligands are redox-innocent. In terms of the molecular details, the mechanism remains uncertain, despite numerous investigations. Most mechanisms assume that formate does not coordinate to Mo/W, in contrast to typical Mo/W oxo-transferases (e.g., DMSO reductase). A popular mechanistic proposal entails transfer of H from formate to the Mo/W=S group. | 1 | Biochemistry |
Mond gas is a cheap coal gas that was used for industrial heating purposes. Coal gases are made by decomposing coal through heating it to a high temperature. Coal gases were the primary source of gas fuel during the 1940s and 1950s until the adoption of natural gas. They were used for lighting, heating, and cooking, typically being supplied to households through pipe distribution systems. The gas was named after its discoverer, Ludwig Mond. | 7 | Physical Chemistry |
Marine snow is made up of a variety of mostly organic matter, including dead or dying animals and phytoplankton, protists, fecal matter, sand, and other inorganic dust. Most trapped particles are more vulnerable to grazers than they would be as free-floating individuals. Aggregates can form through abiotic processes (i.e. extrapolymeric substances). These are natural polymers exuded as waste products mostly by phytoplankton and bacteria. Mucus secreted by zooplankton (mostly salps, appendicularians, and pteropods) also contribute to the constituents of marine snow aggregates. These aggregates grow over time and may reach several centimeters in diameter, traveling for weeks before reaching the ocean floor.
Marine snow often forms during algal blooms. As phytoplankton accumulate, they aggregate or get captured in other aggregates, both of which accelerate the sinking rate. Aggregation and sinking is actually thought to be a large component of sources for algae loss from surface water. Most organic components of marine snow are consumed by microbes, zooplankton and other filter-feeding animals within the first 1,000 metres of their journey. In this way marine snow may be considered the foundation of deep-sea mesopelagic and benthic ecosystems: As sunlight cannot reach them, deep-sea organisms rely heavily on marine snow as an energy source. The small percentage of material not consumed in shallower waters becomes incorporated into the muddy "ooze" blanketing the ocean floor, where it is further decomposed through biological activity.
Marine snow aggregates exhibit characteristics that fit Goldman's "aggregate spinning wheel hypothesis". This hypothesis states that phytoplankton, microorganisms and bacteria live attached to aggregate surfaces and are involved in rapid nutrient recycling. Phytoplankton have been shown to be able to take up nutrients from small local concentrations of organic material (e.g. fecal matter from an individual zooplankton cell, regenerated nutrients from organic decomposition by bacteria). As the aggregates slowly sink to the bottom of the ocean, the many microorganisms residing on them are constantly respiring and contribute greatly to the microbial loop. | 9 | Geochemistry |
In resting cells, axin molecules oligomerize with each other through their C-terminal DIX domains, which have two binding interfaces. Thus they can build linear oligomers or even polymers inside the cytoplasm of cells. DIX domains are unique: the only other proteins known to have a DIX domain are Dishevelled and DIXDC1. (The single Dsh protein of Drosophila corresponds to three paralogous genes, Dvl1, Dvl2 and Dvl3 in mammals.) Dsh associates with the cytoplasmic regions of Frizzled receptors with its PDZ and DEP domains. When a Wnt molecule binds to Frizzled, it induces a poorly known cascade of events, that result in the exposure of dishevelleds DIX domain and the creation of a perfect binding site for axin. Axin is then titrated away from its oligomeric assemblies – the β-catenin destruction complex – by Dsh. Once bound to the receptor complex, axin will be rendered incompetent for β-catenin binding and GSK3 activity. Importantly, the cytoplasmic segments of the Frizzled-associated LRP5 and LRP6 proteins contain GSK3 pseudo-substrate sequences (Pro-Pro-Pro-Ser-Pro-x-Ser), appropriately "primed" (pre-phosphorylated) by CKI, as if it were a true substrate of GSK3. These false target sites greatly inhibit GSK3 activity in a competitive manner. This way receptor-bound axin will abolish mediating the phosphorylation of β-catenin. Since β-catenin is no longer marked for destruction, but continues to be produced, its concentration will increase. Once β-catenin levels rise high enough to saturate all binding sites in the cytoplasm, it will also translocate into the nucleus. Upon engaging the transcription factors LEF1, TCF1, TCF2 or TCF3, β-catenin forces them to disengage their previous partners: Groucho proteins. Unlike Groucho', that recruit transcriptional repressors (e.g. histone-lysine methyltransferases), β-catenin will bind transcriptional activators, switching on target genes. | 1 | Biochemistry |
Hypophosphorous acid (and its salts) are used to reduce metal salts back into bulk metals. It is effective for various transition metals ions (i.e. those of: Co, Cu, Ag, Mn, Pt) but is most commonly used to reduce nickel. This forms the basis of electroless nickel plating (Ni–P), which is the single largest industrial application of hypophosphites. For this application it is principally used as a salt (sodium hypophosphite). | 0 | Organic Chemistry |
Apart from X-ray crystallography, important analytical techniques for the characterization of metal carbonyls are infrared spectroscopy and C NMR spectroscopy. These two techniques provide structural information on two very different time scales. Infrared-active vibrational modes, such as CO-stretching vibrations, are often fast compared to intramolecular processes, whereas NMR transitions occur at lower frequencies and thus sample structures on a time scale that, it turns out, is comparable to the rate of intramolecular ligand exchange processes. NMR data provide information on "time-averaged structures", whereas IR is an instant "snapshot". Illustrative of the differing time scales, investigation of dicobalt octacarbonyl (Co(CO)) by means of infrared spectroscopy provides 13 ν bands, far more than expected for a single compound. This complexity reflects the presence of isomers with and without bridging CO ligands. The C NMR spectrum of the same substance exhibits only a single signal at a chemical shift of 204 ppm. This simplicity indicates that the isomers quickly (on the NMR timescale) interconvert.
Iron pentacarbonyl exhibits only a single C NMR signal owing to rapid exchange of the axial and equatorial CO ligands by Berry pseudorotation. | 0 | Organic Chemistry |
Synthetic biopolymers are human-made copies of biopolymers obtained by abiotic chemical routes. Synthetic biopolymer of different chemical nature have been obtained, including polysaccharides, glycoproteins, peptides and proteins, polyhydroxoalkanoates, polyisoprenes. | 1 | Biochemistry |
The specific study of the ferrous compounds (those including iron, Fe) used in the past. Iron metal was first encountered in meteorites, and was later extracted from iron ores to create wrought iron which was never fully molten, and later, cast iron. Iron combined with carbon formed steel, allowing people to develop superior tools and weapons from the Iron Age to the industrial revolution. | 8 | Metallurgy |
Various combinations of the driving force and moving phase determine various electrokinetic effects. According to J.Lyklema, the complete family of electrokinetic phenomena includes:
* electrophoresis, as motion of charged particles under influence of electric field;
* electro-osmosis, as motion of liquid in porous body under influence of electric field;
* diffusiophoresis, as motion of particles under influence of a chemical potential gradient;
* capillary osmosis, as motion of liquid in porous body under influence of the chemical potential gradient;
* sedimentation potential, as electric field generated by sedimenting colloid particles;
* streaming potential/current, as either electric potential or current generated by fluid moving through porous body, or relative to flat surface;
* colloid vibration current, as electric current generated by particles moving in fluid under influence of ultrasound;
* electric sonic amplitude, as ultrasound generated by colloidal particles in oscillating electric field. | 7 | Physical Chemistry |
Biohydrometallurgy is used to perform processes involving metals, for example, microbial mining, oil recovery, bioleaching, water-treatment and others. Biohydrometallurgy is mainly used to recover certain metals from sulfide ores. It is usually utilized when conventional mining procedures are too expensive or ineffective in recovering a metal such as copper, cobalt, gold, lead, nickel, uranium and zinc. | 8 | Metallurgy |
For each particular lattice, a conventional cell has been chosen on a case-by-case basis by crystallographers based on convenience of calculation. These conventional cells may have additional lattice points located in the middle of the faces or body of the unit cell. The number of lattice points, as well as the volume of the conventional cell is an integer multiple (1, 2, 3, or 4) of that of the primitive cell. | 3 | Analytical Chemistry |
Simple monosaccharides have a linear and unbranched carbon skeleton with one carbonyl (C=O) functional group, and one hydroxyl (OH) group on each of the remaining carbon atoms. Therefore, the molecular structure of a simple monosaccharide can be written as H(CHOH)(C=O)(CHOH)H, where ; so that its elemental formula is CHO.
By convention, the carbon atoms are numbered from 1 to x along the backbone, starting from the end that is closest to the C=O group. Monosaccharides are the simplest units of carbohydrates and the simplest form of sugar.
If the carbonyl is at position 1 (that is, n or m is zero), the molecule begins with a formyl group H(C=O)− and is technically an aldehyde. In that case, the compound is termed an aldose. Otherwise, the molecule has a ketone group, a carbonyl −(C=O)− between two carbons; then it is formally a ketone, and is termed a ketose. Ketoses of biological interest usually have the carbonyl at position 2.
The various classifications above can be combined, resulting in names such as "aldohexose" and "ketotriose".
A more general nomenclature for open-chain monosaccharides combines a Greek prefix to indicate the number of carbons (tri-, tetr-, pent-, hex-, etc.) with the suffixes "-ose" for aldoses and "-ulose" for ketoses. In the latter case, if the carbonyl is not at position 2, its position is then indicated by a numeric infix. So, for example, H(C=O)(CHOH)H is pentose, H(CHOH)(C=O)(CHOH)H is pentulose, and H(CHOH)(C=O)(CHOH)H is pent-3-ulose. | 0 | Organic Chemistry |
Simple chemical weapons were used sporadically throughout antiquity and into the Industrial age. It was not until the 19th century that the modern conception of chemical warfare emerged, as various scientists and nations proposed the use of asphyxiating or poisonous gases. So alarmed were nations that multiple international treaties, discussed below, were passed banning chemical weapons. This however did not prevent the extensive use of chemical weapons in World War I. The development of chlorine gas, among others, was used by both sides to try to break the stalemate of trench warfare. Though largely ineffective over the long run, it decidedly changed the nature of the war. In many cases the gases used did not kill, but instead horribly maimed, injured, or disfigured casualties. Some 1.3 million gas casualties were recorded, which may have included up to 260,000 civilian casualties.
The interwar period saw occasional use of chemical weapons, mainly by multiple European colonial forces to put down rebellions. The Italians also used poison gas during their 1936 invasion of Ethiopia. In Nazi Germany, much research went into developing new chemical weapons, such as potent nerve agents. However, chemical weapons saw little battlefield use in World War II. Both sides were prepared to use such weapons, but the Allied powers never did, and the Axis used them only very sparingly. The reason for the lack of use by the Nazis, despite the considerable efforts that had gone into developing new varieties, might have been a lack of technical ability or fears that the Allies would retaliate with their own chemical weapons. Those fears were not unfounded: the Allies made comprehensive plans for defensive and retaliatory use of chemical weapons, and stockpiled large quantities. Japanese forces used them more widely, though only against their Asian enemies, as they also feared that using it on Western powers would result in retaliation. Chemical weapons were frequently used against Kuomintang and Chinese communist troops. However, the Nazis did extensively use poison gas against civilians in the Holocaust. Vast quantities of Zyklon B gas and carbon monoxide were used in the gas chambers of Nazi extermination camps, resulting in the overwhelming majority of some three million deaths. This remains the deadliest use of poison gas in history.
The post-war era has seen limited, though devastating, use of chemical weapons. Some 100,000 Iranian troops were casualties of Iraqi chemical weapons during the Iran–Iraq War. Iraq used mustard gas and nerve agents against its own civilians in the 1988 Halabja chemical attack. The Cuban intervention in Angola saw limited use of organophosphates. The Syrian government has used sarin, chlorine, and mustard gas in the Syrian civil war generally against civilians. Terrorist groups have also used chemical weapons, notably in the Tokyo subway sarin attack and the Matsumoto incident. See also chemical terrorism. | 1 | Biochemistry |
GCaMP consists of three key domains: an M13 domain at the N-terminus, a calmodulin (CaM) domain at the C-terminus, and a GFP domain in the center. The GFP domain is circularly permuted such that the native N- and C-termini are fused together by a six-amino-acid linking sequence, and the GFP sequence is split in the middle, creating new N- and C-termini that connect to the M13 and CaM domains.
In the absence of Ca, the GFP chromophore is exposed to water and exists in a protonated state with minimal fluorescence intensity. Upon Ca binding, the CaM domain undergoes a conformational change and tightly binds to the M13 domain alpha helix, preventing water molecules from accessing the chromophore. As a result, the chromophore rapidly deprotonates and converts into an anionic form that fluoresces brightly, similar to native GFP. | 1 | Biochemistry |
Julius Tafel discovered that hydroxylamine hydrochloride or sulfate salts can be produced by electrolytic reduction of nitric acid with HCl or Sulfuric acid| respectively:
Hydroxylamine can also be produced by the reduction of nitrous acid or potassium nitrite with bisulfite:
: (100 °C, 1 h)
Hydrochloric acid disproportionates nitromethane to hydroxylamine hydrochloride and carbon monoxide via the hydroxamic acid.
A direct production of hydroxylamine from molecular nitrogen is also possible in water plasma. | 0 | Organic Chemistry |
The second most studied triad is the Cysteine-Histidine-Aspartate motif. Several families of cysteine proteases use this triad set, for example TEV protease and papain. The triad acts similarly to serine protease triads, with a few notable differences. Due to cysteines low pK, the importance of the Asp to catalysis varies and several cysteine proteases are effectively Cys-His dyads (e.g. hepatitis A virus protease), whilst in others the cysteine is already deprotonated before catalysis begins (e.g. papain). This triad is also used by some amidases, such as N'-glycanase to hydrolyse non-peptide C-N bonds. | 1 | Biochemistry |
LOV domains have been found to control gene expression through DNA binding and
to be involved in redox-dependent regulation, like e.g. in the bacterium Rhodobacter sphaeroides. Notably, LOV-based optogenetic tools have been gaining wide popularity in recent years to control a myriad of cellular events, including cell motility, subcellular organelle distribution, formation of membrane contact sites, microtubule dynamics, transcription, and protein degradation. | 1 | Biochemistry |
While serving Rajasthan University as a professor, Mehrotra was known to have contributed in organizing a research school there and successfully tried to obtain Special Assistance Program as well as University Leadership Program from UGC. The research school has since published several original research papers in international journals. Similarly, he established research schools on inorganic and organometallic chemistry at the universities of Allahabad, Lucknow, and Delhi. During 1971–72, as a UGC National Professor, he delivered lectures at many Indian universities and he was a pioneer in popularizing science through Hindi medium for which he was awarded a cash prize by the Government of India in 1985. Besides over 800 articles published in peer-reviewed international journals, he authored five books viz. Metal alkoxides, Metal [beta] [beta]-diketonates and Allied Derivatives, Metal Carboxylates, Alkoxo and Aryloxo Derivatives of Metals and Organometallic Chemistry. He has also prepared texts for Indira Gandhi National Open University as a member of the Block Preparation Team. | 0 | Organic Chemistry |
In a crystal, the constitutive particles are arranged periodically, with translational symmetry forming a lattice. The crystal structure can be described as a Bravais lattice with a group of atoms, called the basis, placed at every lattice point; that is, [crystal structure] = [lattice] [basis]. If the lattice is infinite and completely regular, the system is a perfect crystal. For such a system, only a set of specific values for can give scattering, and the scattering amplitude for all other values is zero. This set of values forms a lattice, called the reciprocal lattice, which is the Fourier transform of the real-space crystal lattice.
In principle the scattering factor can be used to determine the scattering from a perfect crystal; in the simple case when the basis is a single atom at the origin (and again neglecting all thermal motion, so that there is no need for averaging) all the atoms have identical environments. Equation () can be written as
: and .
The structure factor is then simply the squared modulus of the Fourier transform of the lattice, and shows the directions in which scattering can have non-zero intensity. At these values of the wave from every lattice point is in phase. The value of the structure factor is the same for all these reciprocal lattice points, and the intensity varies only due to changes in with . | 3 | Analytical Chemistry |
Whereas most meteorites originate from asteroids, the contrasting make-up of micrometeorites suggests that most originate from comets.
Fewer than 1% of MMs are achondritic and are similar to HED meteorites, which are thought to be from the asteroid 4 Vesta. Most MMs are compositionally similar to carbonaceous chondrites, whereas approximately 3% of meteorites are of this type. The dominance of carbonaceous chondrite-like MMs and their low abundance in meteorite collections suggests that most MMs derive from sources different from those of most meteorites. Since most meteorites derive from asteroids, an alternative source for MMs might be comets. The idea that MMs might originate from comets originated in 1950.
Until recently the greater-than-25-km/s entry velocities of micrometeoroids, measured for particles from comet streams, cast doubts against their survival as MMs. However, recent dynamical simulations suggest that 85% of cosmic dust could be cometary. Furthermore, analyses of particles returned from the comet, Wild 2, by the Stardust spacecraft show that these particles have compositions that are consistent with many micrometeorites. Nonetheless, some parent bodies of micrometeorites appear to be asteroids with chondrule-bearing carbonaceous chondrites. | 9 | Geochemistry |
A number of SRCD beamlines exist, or are being constructed (), around the world as listed in the table.
As of 2022 components from former SRCD beamline CD12 (on [https://www.ibpt.kit.edu/kara.php KARA]) are now installed on the [https://www.synchrotron-soleil.fr/en/beamlines/disco DISCO] beamline
This facility also runs as part of the Beijing Electron Positron Collider (BEPC)
Two modules (A and B) exist on this beamline
This beamline is under construction and received its "first light" as of June 2023 | 7 | Physical Chemistry |
Aliphatic diisocyanates are not used in the production of polyurethane foam as the cost is too high and foam is very much a commodity. It is used in special applications for polyurethane, such as enamel coatings which are resistant to abrasion and degradation from ultraviolet light. There are also multiple patents where prepolymers based on it are used in golf ball production. It is available commercially under the tradename of Desmodur W from Covestro - formerly Bayer Material Science. It is used as a reactive building block for the preparation of other chemical products such as isocyanate terminated prepolymers and other urethane polymers. The isocyanate groups can undergo addition reactions at room temperature with compounds which contain active hydrogens especially amines and polyols. Polyurethane resins based on this diisocyanate have good flexibility and mechanical strength. The polymers formed tend to have abrasion and hydrolysis resistance as well as retaining gloss and physical properties upon weathering. The resins based on this material are useful in coatings for flooring, roofing, maintenance and adhesives, and sealants. They find use in the coatings, adhesives, sealants and elastomers (CASE) applications. A prepolymer made from HMDI and incorporating dimethylol propionic acid can also be converted to light stable polyurethane dispersions. | 0 | Organic Chemistry |
In this method the solid particles present into the two immiscible liquids can be easily separated by suspending those solid particles directly into these immiscible or somewhat miscible liquids. | 7 | Physical Chemistry |
Transamination is mediated by several types of aminotransferase enzymes. An aminotransferase may be specific for an individual amino acid, or it may be able to process any member of a group of similar ones, for example the branched-chain amino acids, which comprises valine, isoleucine, and leucine. The two common types of aminotransferases are alanine aminotransferase (ALT) and aspartate aminotransferase (AST). | 0 | Organic Chemistry |
This book deals with assaying techniques. Various designs of furnaces are detailed. Then cupellation, crucibles, scorifiers and muffle furnaces are described. The correct method of preparation of the cupels is covered in detail with beech ashes being preferred. Various other additives and formulae are described, but Agricola does not judge between them. Triangular crucibles and scorifiers are made of fatty clay with a temper of ground-up crucibles or bricks. Agricola then describes in detail which substances should be added as fluxes as well as lead for smelting or assaying. The choice is made by which colour the ore burns out which gives an indication of the metals present. The lead should be silver-free or be assayed separately. The prepared ore is wrapped in paper, placed on a scorifier and then placed under a muffle covered in burning charcoal in the furnace. The cupel should be heated at the same time. The scorifier is removed and the metal transferred to the cupel. Alternatively the ore can be smelted in a triangular crucible, and then have lead mixed with it when it is added to the cupel. The cupel is placed in the furnace and copper is separated into the lead which forms litharge in the cupel leaving the noble metal. Gold and silver are parted using an aqua which is probably nitric acid. Agricola describes precautions for ensuring the amount of lead is correct and also describes the amalgamation of gold with mercury. Assay techniques for base metals such as tin are described as well as techniques for alloys such as silver tin. The use of a touchstone to assay gold and silver is discussed. Finally detailed arithmetical examples show the calculations needed to give the yield from the assay. | 8 | Metallurgy |
An enantiopure drug is a pharmaceutical that is available in one specific enantiomeric form. Most biological molecules (proteins, sugars, etc.) are present in only one of many chiral forms, so different enantiomers of a chiral drug molecule bind differently (or not at all) to target receptors. Chirality can be observed when the geometric properties of an object is not superimposable with its mirror image. Two forms of a molecule are formed (both mirror images) from a chiral carbon, these two forms are called enantiomers. One enantiomer of a drug may have a desired beneficial effect while the other may cause serious and undesired side effects, or sometimes even beneficial but entirely different effects. The desired enantiomer is known as an eutomer while the undesired enantiomer is known as the distomer. When equal amounts of both enantiomers are found in a mixture, the mixture is known as a racemic mixture. If a mixture for a drug does not have a 1:1 ratio of its enantiomers it is a candidate for an enantiopure drug. Advances in industrial chemical processes have made it economical for pharmaceutical manufacturers to take drugs that were originally marketed as a racemic mixture and market the individual enantiomers, either by specifically manufacturing the desired enantiomer or by resolving a racemic mixture. On a case-by-case basis, the U.S. Food and Drug Administration (FDA) has allowed single enantiomers of certain drugs to be marketed under a different name than the racemic mixture. Also case-by-case, the United States Patent Office has granted patents for single enantiomers of certain drugs. The regulatory review for marketing approval (safety and efficacy) and for patenting (proprietary rights) is independent, and differs country by country. | 4 | Stereochemistry |
The test was originally developed by Ludwig Wilhelm Winkler, in later literature referred to as Lajos Winkler, while working at Budapest University on his doctoral dissertation in 1888. The amount of dissolved oxygen is a measure of the biological activity of the water masses. Phytoplankton and macroalgae present in the water mass-produce oxygen by way of photosynthesis. Bacteria and eukaryotic organisms (zooplankton, fish) consume this oxygen through cellular respiration. The result of these two mechanisms determines the concentration of dissolved oxygen, which in turn indicates the production of biomass. The difference between the physical concentration of oxygen in the water (or the theoretical concentration if there were no living organisms) and the actual concentration of oxygen is called the biochemical demand in oxygen. The Winkler test is often controversial as it is not 100% accurate and the oxygen levels may fluctuate from test to test despite using the same constant sample. | 3 | Analytical Chemistry |
Thioureas are building blocks to pyrimidine derivatives. Thus thioureas condense with β-dicarbonyl compounds. The amino group on the thiourea initially condenses with a carbonyl, followed by cyclization and tautomerization. Desulfurization delivers the pyrimidine.
Similarly, aminothiazoles can be synthesized by the reaction of α-haloketones and thiourea.
The pharmaceuticals thiobarbituric acid and sulfathiazole are prepared using thiourea. 4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole is prepared by the reaction of thiourea and hydrazine. | 0 | Organic Chemistry |
A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where all the atoms are carbon (i.e., are carbocycles), none of the atoms are carbon (inorganic cyclic compounds), or where both carbon and non-carbon atoms are present (heterocyclic compounds with rings containing both carbon and non-carbon). Depending on the ring size, the bond order of the individual links between ring atoms, and their arrangements within the rings, carbocyclic and heterocyclic compounds may be aromatic or non-aromatic; in the latter case, they may vary from being fully saturated to having varying numbers of multiple bonds between the ring atoms. Because of the tremendous diversity allowed, in combination, by the valences of common atoms and their ability to form rings, the number of possible cyclic structures, even of small size (e.g., < 17 total atoms) numbers in the many billions.
Adding to their complexity and number, closing of atoms into rings may lock particular atoms with distinct substitution (by functional groups) such that stereochemistry and chirality of the compound results, including some manifestations that are unique to rings (e.g., configurational isomers). As well, depending on ring size, the three-dimensional shapes of particular cyclic structures – typically rings of five atoms and larger – can vary and interconvert such that conformational isomerism is displayed. Indeed, the development of this important chemical concept arose historically in reference to cyclic compounds. Finally, cyclic compounds, because of the unique shapes, reactivities, properties, and bioactivities that they engender, are the majority of all molecules involved in the biochemistry, structure, and function of living organisms, and in man-made molecules such as drugs, pesticides, etc. | 4 | Stereochemistry |
Green vegetables such as spinach provide magnesium because of the abundance of chlorophyll molecules, which contain the ion. Nuts (especially Brazil nuts, cashews and almonds), seeds (e.g., pumpkin seeds), dark chocolate, roasted soybeans, bran, and some whole grains are also good sources of magnesium.
Although many foods contain magnesium, it is usually found in low levels. As with most nutrients, daily needs for magnesium are unlikely to be met by one serving of any single food. Eating a wide variety of fruits, vegetables, and grains will help ensure adequate intake of magnesium.
Because magnesium readily dissolves in water, refined foods, which are often processed or cooked in water and dried, in general, are poor sources of the nutrient. For example, whole-wheat bread has twice as much magnesium as white bread because the magnesium-rich germ and bran are removed when white flour is processed. The table of food sources of magnesium suggests many dietary sources of magnesium.
"Hard" water can also provide magnesium, but "soft" water contains less of the ion. Dietary surveys do not assess magnesium intake from water, which may lead to underestimating total magnesium intake and its variability.
Too much magnesium may make it difficult for the body to absorb calcium. Not enough magnesium can lead to hypomagnesemia as described above, with irregular heartbeats, high blood pressure (a sign in humans but not some experimental animals such as rodents), insomnia, and muscle spasms (fasciculation). However, as noted, symptoms of low magnesium from pure dietary deficiency are thought to be rarely encountered.
Following are some foods and the amount of magnesium in them:
* Pumpkin seeds, no hulls ( cup) = 303 mg
*Chia seeds, ( cup) = 162 mg
* Buckwheat flour ( cup) = 151 mg
* Brazil nuts ( cup) = 125 mg
* Oat bran, raw ( cup) = 110 mg
* Cocoa powder ( cup) = 107 mg
* Halibut (3 oz) = 103 mg
* Almonds ( cup) = 99 mg
* Cashews ( cup) = 89 mg
* Whole wheat flour ( cup) = 83 mg
* Spinach, boiled ( cup) = 79 mg
* Swiss chard, boiled ( cup) = 75 mg
* Chocolate, 70% cocoa (1 oz) = 73 mg
* Tofu, firm ( cup) = 73 mg
* Black beans, boiled ( cup) = 60 mg
* Quinoa, cooked ( cup) = 59 mg
* Peanut butter (2 tablespoons) = 50 mg
* Walnuts ( cup) = 46 mg
* Sunflower seeds, hulled ( cup) = 41 mg
* Chickpeas, boiled ( cup) = 39 mg
* Kale, boiled ( cup) = 37 mg
* Lentils, boiled ( cup) = 36 mg
* Oatmeal, cooked ( cup) = 32 mg
* Fish sauce (1 Tbsp) = 32 mg
* Milk, non fat (1 cup) = 27 mg
* Coffee, espresso (1 oz) = 24 mg
* Whole wheat bread (1 slice) = 23 mg | 1 | Biochemistry |
As the name would suggest this type of response is triggered by very low levels of light and is thought to be mediated by phytochrome A. It can be initiated by fluences as low as 0.0001μmol/m up to about 0.05μmol/m. Germination of Arabidopsis can be induced with very low levels of red light, as can oat seedlings. Such low levels of light are sufficient for inducing this response since they only convert 0.02% of the phytochrome to its active form. The backward reaction by far red light is only 98% efficient making the conversion non-photoreversible and allowing the response to proceed. VLFRs can also be induced by making up the required fluence by brief flashes of light. Since this depends on light levels and time it is known as the law of reciprocity. | 5 | Photochemistry |
The internal diameter (ID) of an HPLC column is an important parameter. It can influence the detection response when reduced due to the reduced lateral diffusion of the solute band. It can also affect the separation selectivity, when flow rate and injection volumes are not scaled down or up proportionally to the smaller or larger diameter used, both in the isocratic and in gradient modes. It determines the quantity of analyte that can be loaded onto the column. Larger diameter columns are usually seen in preparative applications, such as the purification of a drug product for later use. Low-ID columns have improved sensitivity and lower solvent consumption in the recent ultra-high performance liquid chromatography (UHPLC).
Larger ID columns (over 10 mm) are used to purify usable amounts of material because of their large loading capacity.
Analytical scale columns (4.6 mm) have been the most common type of columns, though narrower columns are rapidly gaining in popularity. They are used in traditional quantitative analysis of samples and often use a UV-Vis absorbance detector.
Narrow-bore columns (1–2 mm) are used for applications when more sensitivity is desired either with special UV-vis detectors, fluorescence detection or with other detection methods like liquid chromatography-mass spectrometry
Capillary columns (under 0.3 mm) are used almost exclusively with alternative detection means such as mass spectrometry. They are usually made from fused silica capillaries, rather than the stainless steel tubing that larger columns employ. | 3 | Analytical Chemistry |
Hydrogen probes are used to monitor the penetration of hydrogen into steels, which can cause brittleness, porosity or decarbonization. | 8 | Metallurgy |
There is no cure for berylliosis; the goals of treatment are to reduce symptoms and slow the progression of disease.
Although the evidence that stopping exposure to beryllium decreases progression of the disease is limited, it is still considered to be an accepted approach to treatment in any stage of disease.
People with early stages of disease, without lung function abnormalities or clinical symptoms, are periodically monitored with physical exams, pulmonary function testing and radiography.
Once clinical symptoms or significant abnormalities in pulmonary function testing appear, treatments include oxygen and oral corticosteroids and whatever supportive therapy is required. | 1 | Biochemistry |
Physical organic chemistry is the study of the interrelationships between structure and reactivity in organic molecules. It can be seen as the study of organic chemistry using tools of physical chemistry such as chemical equilibrium, chemical kinetics, thermochemistry, and quantum chemistry. | 7 | Physical Chemistry |
A common dynamic covalent building motif is bond formation between a carbon center and a heteroatom such as nitrogen or oxygen. Because the bond formed between carbon and a heteroatom is less stable than a carbon-carbon bond, they offer more reversibility and reach thermodynamic equilibrium faster than carbon bond forming dynamic covalent reactions. | 6 | Supramolecular Chemistry |
In high-temperature metal joining processes (welding, brazing and soldering), fluxes are nearly inert at room temperature, but become strongly reducing at elevated temperatures, preventing oxidation of the base and filler materials. The role of flux is typically dual: dissolving the oxides already present on the metal surface to facilitate wetting by molten metal, and acting as an oxygen barrier by coating the hot surface, preventing oxidation.
For example, tin-lead solder attaches very well to copper metal, but poorly to its oxides, which form quickly at soldering temperatures. By preventing the formation of metal oxides, flux enables the solder to adhere to the clean metal surface, rather than forming beads, as it would on an oxidized surface. | 8 | Metallurgy |
Bromophenol is also used as a colour marker to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. Since bromophenol blue carries a slight negative charge at moderate pH, it will migrate in the same direction as DNA or protein in a gel; the rate at which it migrates varies according to gel density and buffer composition, but in a typical 1% agarose gel in a 1X TAE buffer or TBE buffer, bromophenol blue migrates at the same rate as a DNA fragment of about 300 base pairs, in 2% agarose as 150 bp. Xylene cyanol and orange G may also be used for this purpose. | 3 | Analytical Chemistry |
Dialysis has both advantages and disadvantages. Following the structure of the previous section, the pros and cons are discussed based on the type of dialysis used. Advantages and drawbacks of both, diffusion dialysis and electrodialysis, are outlined below. | 1 | Biochemistry |
A common kind of hydrolysis occurs when a salt of a weak acid or weak base (or both) is dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations. The salt also dissociates into its constituent anions and cations. For example, sodium acetate dissociates in water into sodium and acetate ions. Sodium ions react very little with the hydroxide ions whereas the acetate ions combine with hydronium ions to produce acetic acid. In this case the net result is a relative excess of hydroxide ions, yielding a basic solution.
Strong acids also undergo hydrolysis. For example, dissolving sulfuric acid () in water is accompanied by hydrolysis to give hydronium and bisulfate, the sulfuric acid's conjugate base. For a more technical discussion of what occurs during such a hydrolysis, see Brønsted–Lowry acid–base theory. | 7 | Physical Chemistry |
Several derivatives of vancomycin are currently being developed, including oritavancin and dalbavancin (both lipoglycopeptides). Possessing longer half-lives than vancomycin, these newer candidates may demonstrate improvements over vancomycin due to less frequent dosing and activity against vancomycin-resistant bacteria. | 0 | Organic Chemistry |
* Amit Chatterjee, Sponge Iron Production By Direct Reduction Of Iron Oxide, PHI Learning Private Limited, 2010, 353 p. (, [https://books.google.fr/books?id=IcT6-tg1uz4C&printsec=frontcover read online] [https://archive.wikiwix.com/cache/?url=https%3A%2F%2Fbooks.google.fr%2Fbooks%3Fid%3DIcT6-tg1uz4C%26printsec%3Dfrontcover archive])
* "[http://www.ecacwb.org/editor_upload/files/Process%20Technology.pdf Process technology followed for sponge iron]" [https://archive.wikiwix.com/cache/?url=http%3A%2F%2Fwww.ecacwb.org%2Feditor_upload%2Ffiles%2FProcess%2520Technology.pdf archive], Environment Compliance Assistance Centre (ECAC)
* "[http://www.recyclingtoday.com/news/images/dri.pdf World direct reduction statistics]" [https://web.archive.org/web/20050829184014/http://www.recyclingtoday.com/news/images/dri.pdf archive of August 29th, 2005], Midrex, 2001.
* "[http://www.midrex.com/uploads/documents/MDX%20STATS%202012%207-3-13Final.pdf World direct reduction statistics] " [https://archive.wikiwix.com/cache/?url=http%3A%2F%2Fwww.midrex.com%2Fuploads%2Fdocuments%2FMDX%2520STATS%25202012%25207-3-13Final.pdf archive], Midrex, 2012.
* J. Feinman, "[http://jpkc.gsut.edu.cn/upload/20120523/20120523181034985.pdf Direct Reduction and Smelting Processes] " [https://archive.wikiwix.com/cache/?url=http%3A%2F%2Fjpkc.gsut.edu.cn%2Fupload%2F20120523%2F20120523181034985.pdf archive], The AISE Steel Foundation, 1999.
* "[http://ietd.iipnetwork.org/content/direct-reduced-iron Direct Reduced Iron] " [https://archive.wikiwix.com/cache/?url=http%3A%2F%2Fietd.iipnetwork.org%2Fcontent%2Fdirect-reduced-iron archive], The Institute for Industrial Productivity. | 8 | Metallurgy |
A finery forge was used to refine wrought iron at least by the 3rd century BC in ancient China, based on the earliest archaeological specimens of cast and pig iron fined into wrought iron and steel found at the early Han Dynasty (202 BC – 220 AD) site at Tieshengguo. Pigott speculates that the finery forge existed in the previous Warring States period (403–221 BC), because of the wrought iron items from China dating to that period and there was no documented evidence of the bloomery ever being used in China. Wagner writes that in addition to the Han Dynasty hearths believed to be fining hearths, there is also pictorial evidence of the fining hearth from a Shandong tomb mural dated 1st to 2nd century AD, as well as a hint of written evidence in the 4th century AD Daoist text Taiping Jing.
In Europe, the concept of the finery forge may have been evident as early as the 13th century. However, it was perhaps not capable of being used to fashion plate armor until the 15th century, as described in conjunction with the waterwheel-powered blast furnace by the Florentine Italian engineer Antonio Averlino (c. 1400 - 1469). The finery forge process began to be replaced in Europe from the late 18th century by others, of which puddling was the most successful, though some continued in use through the mid-19th century. The new methods used mineral fuel (coal or coke), and freed the iron industry from its dependence on wood to make charcoal. | 8 | Metallurgy |
The quantum yield of a photochemical reaction describes the number of molecules undergoing a photochemical event per absorbed photon:
In a chemical photodegradation process, when a molecule dissociates after absorbing a light quantum, the quantum yield is the number of destroyed molecules divided by the number of photons absorbed by the system. Since not all photons are absorbed productively, the typical quantum yield will be less than 1.
Quantum yields greater than 1 are possible for photo-induced or radiation-induced chain reactions, in which a single photon may trigger a long chain of transformations. One example is the reaction of hydrogen with chlorine, in which as many as 10 molecules of hydrogen chloride can be formed per quantum of blue light absorbed.
Quantum yields of photochemical reactions can be highly dependent on the structure, proximity and concentration of the reactive chromophores, the type of solvent environment as well as the wavelength of the incident light. Such effects can be studied with wavelength-tunable lasers and the resulting quantum yield data can help predict conversion and selectivity of photochemical reactions.
In optical spectroscopy, the quantum yield is the probability that a given quantum state is formed from the system initially prepared in some other quantum state. For example, a singlet to triplet transition quantum yield is the fraction of molecules that, after being photoexcited into a singlet state, cross over to the triplet state. | 7 | Physical Chemistry |
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