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Serine/arginine-rich splicing factor 1 ASF/SF2 is also implicated in cellular mechanisms to hinder exon skipping and to ensure splicing is occurring accurately and correctly. ASF/SF2 has been shown to have a critical function in heart development, embryogenesis, tissue formation, cell motility, and cell viability in general. SFRS1 is a proto-oncogene, and thus ASF/SF2 can act as an oncoprotein; it can alter the splicing patterns of crucial cell cycle regulatory genes and suppressor genes. ASF/SF2 controls the splicing of various tumor suppressor genes, kinases, and kinase receptors, all of which have the potential to be alternatively spliced into oncogenic isoforms. As such, ASF/SF2 is an important target for cancer therapy, as it is over-expressed in many tumors. Modifications and defects in the alternative splicing pathway are associated with a variety of human diseases. ASF/SF2 is involved in the replication of HIV-1, as HIV-1 needs a delicate balance of spliced and unspliced forms of its viral DNA. ASF/SF2 action in the replication of HIV-1 is a potential target for HIV therapy. ASF/SF2 is also implicated in the production of T cell receptors in Systemic Lupus Erythematosus, altering specific chain expression in T cell receptors through alternative splicing. ASF/SF2 has been shown to interact with: | https://en.wikipedia.org/wiki?curid=22264033 |
Substance of very high concern A substance of very high concern (SVHC) is a chemical substance (or part of a group of chemical substances) concerning which it has been proposed that use within the European Union be subject to authorisation under the REACH Regulation. Indeed, listing of a substance as an SVHC by the European Chemicals Agency (ECHA) is the first step in the procedure for authorisation or restriction of use of a chemical. The first list of SVHCs was published on 28 October 2008 and the list has been updated many times to include new candidates. The most recent update occurred on 16 January 2020 to include a total 205 SVHC. The criteria are given in article 57 of the REACH Regulation. A substance "may" be proposed as an SVHC if it meets one or more of the following criteria: The "equivalent concern" criterion is significant because it is this classification which allows substances which are, for example, neurotoxic, endocrine-disrupting or otherwise present an unanticipated environmental health risk to be regulated under REACH. Simply because a substance meets one or more of the criteria does not necessarily mean that it will be proposed as an SVHC. Many such substances are already subject to restrictions on their use within the European Union, such as those in Annex XVII of the REACH Regulation. SVHCs are substances for which the current restrictions on use (where these exist) might be insufficient | https://en.wikipedia.org/wiki?curid=22266408 |
Substance of very high concern There are three priority groups for assessment: Proposals for inclusion of a substance on the list of SVHCs can come either from the European Commission or one of the Member States of the European Union. The proposals are made public by the European Chemicals Agency (ECHA) and are open for public comment for 60–90 days. If the substance is deemed to meet one or more of the criteria, it is then listed as an SVHC. Once a substance has been listed as an SVHC, the Agency commissions a technical report from one or more national or private laboratories, which analyses the available information on manufacture, imports, uses and releases of the substance, as well as possible alternatives. On the basis of this technical report, the Agency decides whether to prioritise the substance, in effect, whether to make a recommendation to the European Commission to add the substance to Annex XIV of the REACH Regulation, making its use subject to authorisation. The draft recommendations must be made public and opened for comment for three months before the final recommendations are sent to the Commission. The first draft recommendations were published on 14 January 2009, and new draft recommendations must be issued at least once every two years. The list of SVHCs is primarily a public list of substances for which the European Chemicals Agency is considering imposing a requirement for authorisation for some or all uses. However, there are some direct consequences of including a substance on the list of SVHCs | https://en.wikipedia.org/wiki?curid=22266408 |
Substance of very high concern Suppliers of pure SVHCs must provide their customers with a safety data sheet (SDS). Suppliers of mixtures of substances which contain more than 0.1% by weight of any SVHC must provide their customers with a safety data sheet "on request". Manufacturers or importers of articles containing more than 0.1% by weight of any SVHC must provide their customers, and consumers on request, with adequate information on the safe use and disposal of the article, including the name of the SVHC(s) concerned. From 1 June 2011, manufacturers and importers of articles also have to notify the European Chemicals Agency of the quantities of SVHCs used in their articles. In addition to the obviously involved chemical industry, there are many more industries affected by this regulation: drapery and leather industry, plastic processing, cosmetic industry, food industry, petroleum processing, printing industry, sports equipment industry, toys industry, recycling industry, electrical engineering industry, fine mechanics industry, optics industry, engine and plant production industry. The following substances are included on the candidate list of substance of very high concern. This list is updated at regular intervals by the European Chemicals Agency (ECHA), with the first substances listed on 28 October 2008. In June 2012, ECHA updated the Candidate List of Substances of Very High Concern (SVHC) for Authorization by including 13 new substances. Among the 13 newly added SVHCs on June 18, 2012, four of them (C.I. Basic Violet 3, C.I | https://en.wikipedia.org/wiki?curid=22266408 |
Substance of very high concern Basic Blue 26, C.I. Solvent Blue 4 and 4,4'-bis(dimethylamino)-4'-(methylamino)trityl alcohol) are identified as SVHC only if the presence of the carcinogenic constituents Michler's ketone or Michler's base is ≥ 0.1% w/w. Therefore, all the proposed substances are carcinogenic, mutagenic and toxic for reproduction (CMR substances; H-phrases H340, H341, H350, H351, H360, H361), which may pose serious effects on human beings. To sell or use these substances, manufacturers, importers and users in the European Union (EU) need to apply for authorization from the ECHA. This list is referred to as the "candidate" list because all substances placed on it are candidates for inclusion in Annex XIV of REACH. If a substance is added to Annex XIV, it is given a "latest application date" and a "sunset date". The sunset date is the date after which the substance cannot be used or imported into the EU without authorisation from the ECHA, and the latest application date is the date by which any applications for use must be submitted to the ECHA. The most recent update is from 16 January, 2020; find the complete list in references. | https://en.wikipedia.org/wiki?curid=22266408 |
Prp24 (precursor RNA processing, gene 24) is a protein part of the pre-messenger RNA splicing process and aids the binding of U6 snRNA to U4 snRNA during the formation of spliceosomes. Found in eukaryotes from yeast to "E. coli", fungi, and humans, was initially discovered to be an important element of RNA splicing in 1989. Mutations in were later discovered in 1991 to suppress mutations in U4 that resulted in cold-sensitive strains of yeast, indicating its involvement in the reformation of the U4/U6 duplex after the catalytic steps of splicing. The process of spliceosome formation involves the U4 and U6 snRNPs associating and forming a di-snRNP in the cell nucleus. This di-snRNP then recruits another member (U5) to become a tri-snRNP. U6 must then dissociate from U4 to bond with U2 and become catalytically active. Once splicing has been done, U6 must dissociate from the spliceosome and bond back with U4 to restart the cycle. has been shown to promote the binding of U4 and U6 snRNPs. Removing results in the accumulation of free U4 and U6, and the subsequent addition of regenerates U4/U6 and reduces the amount of free U4 and U6. Naked U6 snRNA is very compact and has little room to form base pairs with other RNA. However, when U6 snRNP associates with proteins such as Prp24, the structure is much more open, thus facilitating the binding to U4. is not present in the U6/U4 duplex itself, and it has been suggested that must leave the complex in order for proper base pairs to be formed | https://en.wikipedia.org/wiki?curid=22269613 |
Prp24 It has also been suggested that may play a role in destabilizing U4/U6 in order for U6 to pair bases with U2. has a molecular weight of 50 kDa and has been shown to contain four RNA recognition motifs (RRMs) and a conserved 12-amino acid sequence at the C-terminus. RRMs 1 and 2 have been shown to be important for high-affinity binding of U6, while RRMs 3 and 4 bind at lower affinity sites on U6. The first three RRMs interact extensively with each other and contain canonical folds that contain a four-stranded beta-sheet and two alpha-helices. The electropositive surface of RRMs 1 and 2 is a RNA annealing domain while the cleft between RRMs 1 and 2 including the beta-sheet face of RRM2 is a sequence-specific RNA binding site. The C-terminal motif is required for association with LSm proteins and contributes to substrate (U6) binding and not the catalytic rate of splicing. interacts with the U6 snRNA via its RRMs. It has been shown through chemical modification testing that nucleotides 39–57 of U6 (40–43 in particular) are involved in binding Prp24. The LSm proteins are in a consistent configuration on the U6 RNA. It has been proposed that the LSm proteins and interact both physically and functionally and the C-terminal motif of is important for this interaction. The binding of to U6 is enhanced by the binding of Lsm proteins to U6, as is binding of U4 and U6. It was revealed by electron microscopy that may interact with the LSm protein ring at LSm2. has a human homolog, SART3 | https://en.wikipedia.org/wiki?curid=22269613 |
Prp24 SART3 is a tumor rejection antigen (SART3 stands for "squamous cell carcinoma antigen recognized by T cells, gene 3). The RRMs 1 and 2 in yeast are similar to RRMs in human SART3. The C-terminal domain is also highly conserved from yeast to humans. This protein, like Prp24, interacts with the LSm proteins for the recycling of U6 into the U4/U6 snRNP. It has been proposed that SART3 target U6 to a Cajal body or a nuclear inclusion as the site of assembly of the U4/U6 snRNP. SART3 is located on chromosome 12, and a mutation is likely the cause of disseminated superficial actinic porokeratosis. | https://en.wikipedia.org/wiki?curid=22269613 |
SUPER HI-CAT C-MORE: (Center for Microbial Oceanography- Research and Education: Survey of Underwater Plastic Ecosystem Response Hawaii to California Transit) The research cruise was the first effort to study the microbial communities and the biogeochemistry associated with the Great Pacific Garbage Patch.[1] The study was conducted aboard the RV Kilo Moana (T-AGOR-26) between August 25, 2008 and September 5, 2008 by researchers from UH Manoa, Oregon State University, and the Algalita Marine Research Foundation. Previous research on the Plastic Patch had mostly focused on the effects of the plastic pieces on jellyfish, fish, sea turtles, and seabirds. Relatively little was known about how this type of marine debris would affect the microbial communities that make up 98% of the biomass in the ocean and control oceanic biogeochemistry. During this cruise, 30 sites were sampled. At 15 of these sites, a modified surface net called a manta trawl was used to collect plastic pieces, while water samples were collected from the upper 200 meters of the ocean. At the other 15 stations, only the surface waters were sampled. This study will allow researchers to begin to determine whether biofilms are forming on the plastic particles, whether the microbes living on the particles are different from the free-living planktonic organisms, and what effect these communities might have on the oceanic carbon cycle and nitrogen cycle. cruise page and data links | https://en.wikipedia.org/wiki?curid=22270456 |
Covalent organic framework Covalent organic frameworks (COFs) are two-dimensional and three-dimensional organic solids with extended structures in which building blocks are linked by strong covalent bonds. COFs are porous and crystalline and are made entirely from light elements (H, B, C, N, and O) that are known to form strong covalent bonds in well-established and useful materials such as diamond, graphite, and boron nitride. Preparation of COF materials from molecular building blocks would provide covalent frameworks that could be functionalized into lightweight materials for diverse applications. Porous crystalline solids consists of secondary building units (SBUs) which assemble to form a periodic and porous framework. An almost infinite numbers of frameworks can be formed through various SBU combinations leading to unique material properties for applications in separations, storage, and heterogeneous catalysis. Porous crystalline solids can be used to describe materials such as Zeolite, Metal-organic frameworks (MOFs), and Covalent Organic Frameworks (COFs). Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. MOFs are a class of porous polymeric material, consisting of metal ions linked together by organic bridging ligands and are a new development on the interface between molecular coordination chemistry and materials science | https://en.wikipedia.org/wiki?curid=22272874 |
Covalent organic framework COFs are another class of porous polymeric materials, consisting of porous, crystalline, covalent bonds that usually have rigid structures, exceptional thermal stabilities (to temperatures up to 600 °C), are stable in water and low densities. They exhibit permanent porosity with specific surface areas surpassing those of well-known zeolites and porous silicates. The term ‘secondary building unit’ has been used for some time to describe conceptual fragments which can be compared as bricks used to build a house of zeolites; in the context of this page it refers to the geometry of the units defined by the points of extension. Although the synthesis of new materials has long been recognized as the most essential element in advancing technology, it generally remains more of an art than a science—in that the discovery of new compounds has mostly been serendipitous, using methods referred to by critics as 'shake and bake', ‘mix and wait', 'mash and smash' and 'heat and beat'. The reason is that the starting entities do maintain their structure during the reaction, leading to poor correlation between reactants and products. However, the design of an extended network that will maintain its structural integrity throughout the construction process can be realized by starting with well-defined and rigid molecular building blocks | https://en.wikipedia.org/wiki?curid=22272874 |
Covalent organic framework In essence, reticular synthesis can be described as the process of assembling judiciously designed rigid secondary building units into predetermined ordered structures (networks), which are held together by strong bonding. It is different from retrosynthesis of organic compounds, because the structural integrity and rigidity of the building blocks in reticular synthesis remain unaltered throughout the construction process—an important aspect that could help to fully realize the benefits of design in crystalline solid-state frameworks. Similarly, reticular synthesis should be distinguished from supramolecular assembly, because in the former, building blocks are linked by strong bonds throughout the crystal. Omar M. Yaghi and William A. Goddard III reported COFs as exceptional hydrogen storage materials. They predicted the highest excess H uptakes at 77 K are 10.0 wt % at 80 bar for COF-105, and 10.0 wt % at 100 bar for COF-108, which have higher surface area and free volume, by grand canonical Monte Carlo (GCMC) simulations as a function of temperature and pressure. This is the highest value reported for associative H storage of any material. Thus 3-D COFs are most promising new candidates in the quest for practical H storage materials. In 2012, the lab of William A. Goddard III reported the uptake for COF102, COF103, and COF202 at 298 K and they also proposed new strategies to obtain higher interaction with H. Such strategy consist on metalating the COF with alkaline metals such as Li | https://en.wikipedia.org/wiki?curid=22272874 |
Covalent organic framework Uptake in Li-, Na-, K-Metalated Covalent Organic Frameworks and Metal Organic Frameworks at 298 K. "J. Phys. Chem. A". 2012, "116", pp 1621–1631. </ref> These complexes composed of Li, Na and K with benzene ligands (such as 1,3,5-benzenetribenzoate, the ligand used in MOF-177) have been synthesized by Krieck et al. and Goddard showed that the THF is important of their stability. If the metalation with alkaline is performed in the COFs, Goddard et al. calculated that some COFs can reach 2010 DOE gravimetric target in delivery units at 298 K of 4.5 wt %: COF102-Li (5.16 wt %), COF103-Li (4.75 wt %), COF102-Na (4.75 wt %) and COF103-Na (4.72 wt %). COFs also perform better in delivery units than MOFs because the best volumetric performance is for COF102-Na (24.9), COF102-Li (23.8), COF103-Na (22.8), and COF103-Li (21.7), all using delivery g H/L units for 1–100 bar. These are the highest gravimetric molecular hydrogen uptakes for a porous material under these thermodynamic conditions. Omar M. Yaghi and William A. Goddard III also reported COFs as exceptional methane storage materials. The best COF in terms of total volume of CH per unit volume COF absorbent is COF-1, which can store 195 v/v at 298 K and 30 bar, exceeding the U.S. Department of Energy target for CH storage of 180 v/v at 298 K and 35 bar. The best COFs on a delivery amount basis (volume adsorbed from 5 to 100 bar) are COF-102 and COF-103 with values of 230 and 234 v(STP: 298 K, 1 | https://en.wikipedia.org/wiki?curid=22272874 |
Covalent organic framework 01 bar)/v, respectively, making these promising materials for practical methane storage. More recently, new COFs with better delivery amount have been designed in the lab of William A. Goddard III, and they have been shown to be stable and overcome the DOE target in delivery basis. COF-103-Eth-trans and COF-102-Ant, are found to exceed the DOE target of 180 v(STP)/v at 35 bar for methane storage. They reported that using thin vinyl bridging groups aid performance by minimizing the interaction methane-COF at low pressure. A highly ordered π-conjugation TP-COF, consisting of pyrene and triphenylene functionalities alternately linked in a mesoporous hexagonal skeleton, is highly luminescent, harvests a wide wavelength range of photons, and allows energy transfer and migration. Furthermore, TP-COF is electrically conductive and capable of repetitive on–off current switching at room temperature. Most studies to date have focused on the development of synthetic methodologies with the aim of maximizing pore size and surface area for gas storage. That means the functions of COFs have not yet been well explored, but COFs can be used as catalyst, or gas separation etc. In 2015 the use of highly porous, catalyst-decorated COFs for converting carbon dioxide into carbon monoxide. COFs have been studied as non-metallic electrocatalyst for energy-related catalysis, including carbon dioxide electro-reduction and water splitting reaction. However, such researches are still in the very earlier stage | https://en.wikipedia.org/wiki?curid=22272874 |
Covalent organic framework Most of the efforts have been focusing on solving the key issues, such as conductivity, stability in electrochemical processes. While at UMich, Omar M. Yaghi (currently at UCBerkeley) and Adrien P Cote published the first paper of COF. They reported the design and successful synthesis of COFs by condensation reactions of phenyl diboronic acid (CH[B(OH)]) and hexahydroxytriphenylene (CH(OH)). Powder X-ray diffraction studies of the highly crystalline products having empirical formulas (CHBO)·(CH) (COF-1) and CHBO (COF-5) revealed 2-dimensional expanded porous graphitic layers that have either staggered conformation (COF-1) or eclipsed conformation (COF-5). Their crystal structures are entirely held by strong bonds between B, C, and O atoms to form rigid porous architectures with pore sizes ranging from 7 to 27 [Ängstrom]]s. COF-1 and COF-5 exhibit high thermal stability (to temperatures up to 500 to 600 C), permanent porosity, and high surface areas (711 and 1590 square meters per gram, respectively). The synthesis of 3D COFs has been hindered by longstanding practical and conceptual challenges. Unlike 0D and 1D systems, which are soluble, the insolubility of 2D and 3D structures precludes the use of stepwise synthesis, making their isolation in crystalline form very difficult. This first challenge, however, was overcome by judiciously choosing building blocks and using reversible condensation reactions to crystallize COFs | https://en.wikipedia.org/wiki?curid=22272874 |
Covalent organic framework The most popular COF synthesis route is a boron condensation reaction which is a molecular dehydration reaction between boronic acids. In case of COF-1, three boronic acid molecules converge to form a planar six-membered BO (boroxine) ring with the elimination of three water molecules. Another class of high performance polymer frameworks with regular porosity and high surface area is based on triazine materials which can be achieved by dynamic trimerization reaction of simple, cheap, and abundant aromatic nitriles in ionothermal conditions (molten zinc chloride at high temperature (400 °C)). CTF-1 is a good example of this chemistry. A new class of COFs can be obtained by imine condensation of aniline with benzaldehyde that results in imine bond formation with elimination of water. COF-300 is a good example of this chemistry. Even though COFs are usually harder to characterize in terms of their properties than MOFs because COFs have no single crystal structure, COFs can be characterized by some following methods. Powder X-ray diffraction (PXRD) is used to determine structure. Morphology is understood by Scanning electron microscopy (SEM). Finally, porosity, in some meaning surface area, is measured by N2 isotherm. | https://en.wikipedia.org/wiki?curid=22272874 |
Niobium(V) bromide is the inorganic compound with the formula NbBr. Its name comes from the compound's empirical formula, NbBr. It is a diamagnetic, orange solid that hydrolyses readily. The compound adopts an edge-shared bioctahedral structure, which means that two NbBr units are joined by a pair of bromide bridges. The pentachloride and pentaiodides of Nb and Ta share this structural motif. There is no bond between the Nb centres. It is prepared by the reaction of bromine with niobium metal at high temperature in a tube furnace. | https://en.wikipedia.org/wiki?curid=22273121 |
Lexitropsin Lexitropsins are members of a family of semi-synthetic DNA-binding ligands. They are structural analogs of the natural antibiotics netropsin and distamycin. Antibiotics of this group can bind in the minor groove of DNA with different sequence-selectivity. Lexitropsins form a complexes with DNA with stoichiometry 1:1 and 2:1. Based on the 2:1 complexes were obtained ligands with high sequence-selectivity. | https://en.wikipedia.org/wiki?curid=22275501 |
Apparent molar property An apparent molar property of a solution component in a mixture or solution is a quantity defined with the purpose of isolating the contribution of each component to the non-ideality of the mixture. It shows the change in the corresponding solution property (for example, volume) when all of that component is added to the solution, per mole of component added. It is described as "apparent" because it appears to represent the molar property of that component "in solution", provided that the properties of the other solution components are assumed to remain constant during the addition. However this assumption is often not justified, since the values of apparent molar properties of a component may be quite different from its molar properties in the pure state. For instance, the volume of a solution containing two components identified as solvent and solute is given by where "V" is the volume of the pure solvent before adding the solute and formula_2 its molar volume (at the same temperature and pressure as the solution), "n" is the number of moles of solvent, formula_3 is the apparent molar volume of the solute, and "n" is the number of moles of the solute in the solution. By dividing this relation to the molar amount of one component a relation between the apparent molar property of a component and the mixing ratio of components can be obtained. This equation serves as the definition of formula_3 | https://en.wikipedia.org/wiki?curid=22276716 |
Apparent molar property The first term is equal to the volume of the same quantity of solvent with no solute, and the second term is the change of volume on addition of the solute. formula_3 may then be considered as the molar volume of the solute "if it is assumed" that the molar volume of the solvent is unchanged by the addition of solute. However this assumption must often be considered unrealistic as shown in the Examples below, so that formula_3 is described only as an "apparent" value. An apparent molar quantity can be similarly defined for the component identified as solvent formula_7. Some authors have reported apparent molar volumes of both (liquid) components of the same solution. This procedure can be extended to ternary and multicomponent mixtures. Apparent quantities can also be expressed using mass instead of number of moles. This expression produces apparent specific quantities, like the apparent specific volume. where the specific quantities are denoted with small letters. Apparent (molar) properties are not constants (even at a given temperature), but are functions of the composition. At infinite dilution, an apparent molar property and the corresponding partial molar property become equal. Some apparent molar properties that are commonly used are apparent molar enthalpy, apparent molar heat capacity, and apparent molar volume. The apparent (molal) volume of a solute can be expressed as a function of the molality "b" of that solute (and of the densities of the solution and solvent) | https://en.wikipedia.org/wiki?curid=22276716 |
Apparent molar property The volume of solution per mole of solute is Subtracting the volume of pure solvent per mole of solute gives the apparent molal volume: For more solutes the above equality is modified with the mean molar mass of the solutes as if they were a single solute with molality b: The sum of products molalities – apparent molar volumes of solutes in their binary solutions equals the product between the sum of molalities of solutes and apparent molar volume in ternary of multicomponent solution mentioned above. A relation between the apparent molar of a component of a mixture and molar mixing ratio can be obtained by dividing the definition relation to the number of moles of one component. This gives the following relation: Note the contrasting definitions between partial molar quantity and apparent molar quantity: in the case of partial molar volumes formula_16, defined by we can write formula_18, and so formula_19 always holds. In contrast, in the definition of apparent molar volume, the molar volume of the pure solvent, formula_20, is used instead, which can be written as for comparison. In other words, we assume that the volume of the solvent does not change, and we use the partial molar volume where the number of moles of the solute is exactly zero ("the molar volume"). Thus, in the defining expression for apparent molar volume formula_22, the term formula_24 is attributed to the pure solvent, while the "leftover" excess volume, formula_25, is considered to originate from the solute | https://en.wikipedia.org/wiki?curid=22276716 |
Apparent molar property At high dilution with formula_26, we have formula_27, and so the apparent molar volume and partial molar volume of the solute also converge: formula_28. Quantitatively, the relation between partial molar properties and the apparent ones can be derived from the definition of the apparent quantities and of the molality. For volume, The ratio "r" between the apparent molar volume of a dissolved electrolyte in a concentrated solution and the molar volume of the solvent (water) can be linked to the statistical component of the activity coefficient of the electrolyte and its solvation shell number "h": formula_30, where ν is the number of ions due to dissociation of the electrolyte. The apparent molar volume of a salt is usually less than the molar volume of the solid salt. For instance, solid NaCl has a volume of 27 cm per mole, but the apparent molar volume at low concentrations is only 16.6 cc/mole. In fact, some aqueous electrolytes have negative apparent molar volumes: NaOH −6.7, LiOH −6.0, and NaCO −6.7 cm/mole. This means that their solutions in a given amount of water have a smaller volume than the same amount of pure water. (The effect is small however.) The physical reason is that nearby water molecules are strongly attracted to the ions so that they occupy less space. Another example of the apparent molar volume of the second component being less than its molar volume as a pure substance is the case of ethanol in water. For example, at 20 mass percents ethanol, the solution has a volume of 1 | https://en.wikipedia.org/wiki?curid=22276716 |
Apparent molar property 0326 litres per kg at 20 °C, while pure water is 1.0018 L/kg (1.0018 cc/g). The apparent volume of the added ethanol is 1.0326 L – 0.8 kg x 1.0018 L/kg = 0.2317 L. The number of moles of ethanol is 0.2 kg / (0.04607 kg/mol) = 4.341 mol, so that the apparent molar volume is 0.2317 L / 4.341 mol = 0.0532 L / mol = 53.2 cc/mole (1.16 cc/g). However pure ethanol has a molar volume at this temperature of 58.4 cc/mole (1.27 cc/g). If the solution were ideal, its volume would be the sum of the unmixed components. The volume of 0.2 kg pure ethanol is 0.2 kg x 1.27 L/kg = 0.254 L, and the volume of 0.8 kg pure water is 0.8 kg x 1.0018 L/kg = 0.80144 L, so the ideal solution volume would be 0.254 L + 0.80144 L = 1.055 L. The nonideality of the solution is reflected by a slight decrease (roughly 2.2%, 1.0326 rather than 1.055 L/kg) in the volume of the combined system upon mixing. As the percent ethanol goes up toward 100%, the apparent molar volume rises to the molar volume of pure ethanol. Apparent quantities can underline interactions in electrolyte – non-electrolyte systems which show interactions like salting in and salting out, but also give insights in ion-ion interactions, especially by their dependence on temperature. For multicomponent solutions, apparent molar properties can be defined in several ways. For the volume of a "ternary" (3-component) solution with one solvent and two solutes as an example, there would still be only one equation formula_31, which is insufficient to determine the two apparent volumes | https://en.wikipedia.org/wiki?curid=22276716 |
Apparent molar property (This is in contrast to partial molar properties, which are well-defined intensive properties of the materials and therefore unambiguously defined in multicomponent systems. For example, partial molar volume is defined for each component "i" as formula_32.) One description of ternary aqueous solutions considers only the weighted mean apparent molar volume of the solutes, defined as where formula_34 is the solution volume and formula_24 the volume of pure water. This method can be extended for mixtures with more than 3 components. The sum of products molalities – apparent molar volumes of solutes in their binary solutions equals the product between the sum of molalities of solutes and apparent molar volume in ternary of multicomponent solution mentioned above. Another method is to treat the ternary system as "pseudobinary" and define the apparent molar volume of each solute with reference to a binary system containing both other components: water and the other solute. The apparent molar volumes of each of the two solutes are then The apparent molar volume of the solvent is: formula_40 However, this is an unsatisfactory description of volumetric properties. The apparent molar volume of two components or solutes considered as one pseudocomponent formula_41 or formula_42 is not to be confused with volumes of partial binary mixtures with one common component "V", "V" which mixed in a certain mixing ratio form a certain ternary mixture "V" or "V" | https://en.wikipedia.org/wiki?curid=22276716 |
Apparent molar property Of course the complement volume of a component in respect to other components of the mixture can be defined as a difference between the volume of the mixture and the volume of a binary submixture of a given composition like: formula_43 There are situations when there is no rigorous way to define which is solvent and which is solute like in the case of liquid mixtures (say water and ethanol) that can dissolve or not a solid like sugar or salt. In these cases apparent molar properties can and must be ascribed to all components of the mixture. | https://en.wikipedia.org/wiki?curid=22276716 |
Reproductive toxicity is a hazard associated with some chemical substances, which interfere in some way with normal reproduction; such substances are called reprotoxic. They may adversely affect sexual function and fertility in adult males and females, as well as causing developmental toxicity in the offspring. is usually defined practically, to include several different effects which are unrelated to each other except in their outcome of lowered effective fertility. The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) separates reproductive toxicity from germ cell mutagenicity and carcinogenicity, even though both these hazards may also affect fertility. Many drugs can affect the human reproductive system. Their effects can be However, most studies of reproductive toxicity have focused on occupational or environmental exposure to chemicals and their effects on reproduction. Both consumption of alcohol and tobacco smoking are known to be "toxic for reproduction" in the sense used here. One well-known group of substances which are toxic for reproduction are teratogens – substances which cause birth defects. ("S")-thalidomide is possibly the most notorious of these. Another group of substances which have received much attention (and prompted some controversy) as possibly toxic for reproduction are the so-called endocrine disruptors. Endocrine disruptors change how hormones are produced and how they interact with their receptors | https://en.wikipedia.org/wiki?curid=22277265 |
Reproductive toxicity Endocrine disruptors are classified as estrogenic, anti-estrogenic, androgenic or anti-androgenic. Each category includes pharmaceutical compounds and environmental compounds. Estrogenic or androgenic compounds will cause the same hormonal responses as the sex steroids (estrogen and testosterone). However anti-estrogenic and anti-andogenic compounds bind to a receptor and block the hormones from binding to their receptors, thus preventing their function. A few examples of the many types of endocrine disruptors are trenbolone (androgenic), flutamide (anti-androgenic), dieththylstilbestrol (estrogenic), Bisphenol A (estrogenic), tributyltin (anti-estrogenic). However, many substances which are toxic for reproduction do not fall into any of these groups: lead compounds, for example, are considered to be toxic for reproduction given their adverse effects on the normal intellectual and psychomotor development of human babies and children. Bisphenol A (BPA) is an example of an endocrine disruptor which negatively affects reproductive development. BPA is a known as an estrogen mimicker (Xenoestrogen) and a likely androgen mimicker. It is used in the production of various plastic products. BPA exposure in fetal female rats leads to mammary gland morphogenesis, increased formation of ovarian tumors, and increased risk of developing mammary gland neoplasia in adult life. BPA also affects male fertility by resulting in lower sperm quality and sex function | https://en.wikipedia.org/wiki?curid=22277265 |
Reproductive toxicity The toxicological impact of BPA is better understood and studied in females than in males. Lead is a heavy metal that has been associated not only with mental deficits, but also with male infertility and male reproductive issues. Lead is believed to predominantly affect male reproduction by the disruption of hormones, which reduces the quantity of sperm production in the seminiferous tubules. It has also been proposed that lead causes poor semen quality by increasing reactive oxygen species due to lipid peroxidation, leading to cellular damage. Other reproductive toxins such as Thalidomide were once prescribed therapeutically. In the 1950s and early 1960s, Thalidomide was widely used in Europe as an anti-nausea medication to alleviate morning sickness in pregnant women. But it was found in the 1960s that Thalidomide altered embryo development and led to limb deformities such as thumb absence, underdevelopment of entire limbs, or phocomelia. Thalidomide may have caused teratogenic effects in over 10,000 babies worldwide. Diethylstilbestrol (DES), a synthetic estrogen known to be another reproductive toxin, was used from 1938 to 1971 to prevent spontaneous abortions. DES causes cancer and mutations by producing highly reactive metabolites, also causing DNA adducts to form. Exposure to DES in the womb can cause atypical reproductive tract formation | https://en.wikipedia.org/wiki?curid=22277265 |
Reproductive toxicity Specifically, females exposed, "in utero", to DES during the first trimester have are more likely to develop clear cell vaginal carcinoma, and males have an increased risk of hypospadias. | https://en.wikipedia.org/wiki?curid=22277265 |
Phosphaalkene Phosphaalkenes (IUPAC name: alkylidenephosphanes) are organophosphorus compounds with double bonds between carbon and phosphorus(III) with the formula RC=PR. In the compound phosphorine one carbon atom in benzene is replaced by phosphorus. The reactivity of phosphaalkenes is often compared to that of alkenes and not to that of imines because the HOMO of phosphaalkenes is not the phosphorus lone pair (as in imines the amine lone pair) but the double bond. Therefore like alkenes, phosphaalkenes engage in Wittig reactions, Peterson reactions, Cope rearrangements, and Diels-Alder reactions. The first phosphaalkene discovered was a phosphabenzene, by Mërkl in 1969. The first localized phosphaalkene was reported in 1976 by Gerd Becker as a keto-enol tautomerism akin a Brook rearrangement: In the same year Harold Kroto established spectroscopically that thermolysis of MePH generates CH=PMe. A general method for the synthesis of phosphaalkenes is by 1,2-elimination of suitable precursors, initiated thermally or by base such as DBU, DABCO or triethylamine: The Becker method is used in the synthesis of the phosphorus pendant of Poly(p-phenylene vinylene): | https://en.wikipedia.org/wiki?curid=22278085 |
Thermoset polymer matrix A thermoset polymer matrix is a synthetic polymer reinforcement first developed for structural applications, such as glass-reinforced plastic radar domes on aircraft and graphite-epoxy payload bay doors on the space shuttle. In polymer matrix composites, polymers act as binder or matrix to secure in place incorporated particulates, fibres or other reinforcements. They were first used after World War II, and continuing research has led to an increased range of thermoset resins, polymers or plastics, as well as engineering grade thermoplastics, all developed for use in the manufacture of polymer composites with enhanced and longer-term service capabilities. technologies also find use in a wide diversity of non-structural industrial applications. The foremost types of thermosetting polymers used in structural composites are benzoxazine resins, bis-Maleimide resins (BMI), cyanate ester resins, epoxy (epoxide) resins, phenolic (PF) resins, unsaturated polyester (UP) resins, polyimides, polyurethane (PUR) resins, silicones, and vinyl esters. These are made by the reaction of phenols, formaldehyde and primary amines which at elevated temperatures (400 °F (200 °C)) undergo ring–opening polymerisation forming polybenzoxazine thermoset networks; when hybridised with epoxy and phenolic resins the resulting ternary systems have glass transition temperatures in excess of 490 °F (250 °C) | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Cure is characterised by expansion rather than shrinkage and uses include structural prepregs, liquid molding and film adhesives for composite construction, bonding and repair. The high aromatic content of the high molecular weight polymers provides enhanced mechanical and flammability performance compared to epoxy and phenolic resins. Formed by the condensation reaction of a diamine with maleic anhydride, and processed basically like epoxy resins ( cure). After an elevated post-cure (), they will exhibit superior properties. These properties are influenced by a 400-450 °F (204-232 °C) continuous use temperature and a glass transition of . This thermoset polymer type is merged into composites as a prepreg matrix used in electrical printed circuit boards, and for large scale structural aircraft – aerospace composite structures, etc. It is also used as a coating material and as the matrix of glass reinforced pipes, particularly in high temperature and chemical environments. The reaction of bisphenols or multifunctional phenol novolac resins with cyanogen bromide or chloride leads to cyanate functional monomers which can be converted in a controlled manner into cyanate ester functional prepolymer resins by chain extension or copolymerization | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix When postcured, all residual cyanate ester functionality polymerises by cyclotrimerisation leading to tightly crosslinked polycyanurate networks with high thermal stability and glass transition temperatures up to 752 °F (400 °C) and wet heat stability up to around 400 °F (200 °C). Cyanate ester resin prepregs combine the high temperature stability of polyimides with the flame and fire resistance of phenolics and are used in the manufacture of aerospace structural composite components which meet fire protection regulations concerning flammability, smoke density and toxicity. Other uses include film adhesives, surfacing films and 3D printing. Epoxy resins are thermosetting prepolymers made either by the reaction of epichlorohydrin with hydroxyl functional aromatics, cycloaliphatics and aliphatics or amine functional aromatics, or by the oxidation of unsaturated cycloaliphatics. The diglycidyl ethers of bisphenol-A (DGEBA) and bisphenol-F (DGEBF) are the most widely used due to their characteristic high adhesion, mechanical strength, heat and corrosion resistance. Epoxide functional resins and prepolymers cure by polyaddition/copolymerisation or homopolymerisation depending on the selection of crosslinker, hardener, curing agent or catalyst as well as by the temperature. Epoxy resin is used widely in numerous formulations and forms in the aircraft-aerospace industry. It is regarded as "the work-horse of modern day composites" | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix In recent years, the epoxy formulations used in composite prepregs have been fine-tuned to improve their toughness, impact strength and moisture absorption resistance. Maximum properties have been realized for this polymer. This is not only used in aircraft-aerospace demand. It is used in military and commercial applications and is also used in construction. Epoxy-reinforced concrete and glass-reinforced and carbon-reinforced epoxy structures are used in building and bridge structures. Epoxy composites have the following properties: Epoxy Phenol Novolac (EPN) and Epoxy Cresol Novolac (ECN) resins made by reacting epichlorohydrin with multifunctional phenol novolac or cresol novolac resins have more reactive sites compared to DGEBF epoxy resins and on cure result in higher crosslink density thermosets. They are used in printed wire/circuit board laminating and also for electrical encapsulation, adhesive and coatings for metal where there is a need to provide protection from corrosion, erosion or chemical attack at high continuous operating temperatures. There are two types of phenolic resins - novolacs and resoles. Novolacs are made with acid catalysts and a molar ratio of formaldehyde to phenol of less than one to give methylene linked phenolic oligomers; resoles are made with alkali catalysts and a molar ratio of formaldehyde to phenol of greater than one to give phenolic oligomers with methylene and benzylic ether-linked phenol units | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Phenolic resins, originally developed in the late 19th century and, regarded as the first truly synthetic polymer types, are often referred to as the “work-horse of thermosetting resins”. They are characterised by high bonding strength, dimensional stability and creep resistance at elevated temperatures, and frequently combined with co-curing resins such as epoxies. General purpose molding compounds, engineering molding compounds and sheet molding compounds are the primary forms of phenolic composites. Phenolics are also used as the matrix binder with Honeycomb core. Phenolics find use in many electrical applications such as breaker boxes, brake lining materials and most recently in combination with various reinforcements in the molding of an engine block-head assembly, called the polimotor. Phenolics may be processed by the various common techniques, including compression, transfer and injection molding. Properties of phenolic composites have the following properties: Unsaturated polyester resins are an extremely versatile, and fairly inexpensive class of thermosetting polymer formed by the polycondensation of glycol mixtures containing propylene glycol, with a dibasic acid and anhydrides usually maleic anhydride to provide backbone unsaturation needed for crosslinking, and orthophthalic anhydride, isophthalic acid or terephthalic acid where superior structural and corrosion resistance properties are required | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Polyester resins are routinely diluted/dissolved in a vinyl functional monomer such as styrene and include an inhibitor to stabilize the resin for storage purposes. Polymerisation in service is initiated by free radicals generated from ionizing radiation or by the photolytic or thermal decomposition of a radical initiator. Organic peroxides, such as methyl ethyl ketone peroxide and auxiliary accelerators which promote decomposition to form radicals are combined with the resin to initiate a room temperature cure. In the liquid state, unsaturated polyester resins may be processed by numerous methods, including Hand Layup, vacuum bag molding, and spray-up and compression molded Sheet Molding Compound (SMC). They can also be B-staged after application to chopped reinforcement and continuous reinforcement, to form pre-pregs. Solid molding compounds in the form of pellets or granules are also used in processes such as compression and transfer molding. There are two types of commercial polyimides: thermosetting cross-linkable polyimides made by the condensation of aromatic diamines with aromatic dianhydride derivatives and anhydrides with unsaturated sites that facilitate addition polymerisation between preformed imide monomers and oligomers, and thermoplastic polyimides formed by the condensation reaction between aromatic diamines and aromatic dianhydrides | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Thermoset polyimides are the most advanced of all thermoset polymer matrices with characteristics of high temperature physical and mechanical properties and are available commercially as resin, prepreg, stock shapes, thin sheets/films, laminates, and machined parts. Along with the high temperature properties, this thermoset polymer type must be processed at very high temperatures and relative pressure to produce optimum characteristics. With prepreg materials, to temperatures and pressures are required. The entire cure profiles are inherently long as there are a number of intermediate temperatures dwells, duration of which are dependent on part size and thickness. The cut of polyimides is , highest of all thermosets, with short term exposure capabilities of . Normal operating temperatures range from cryogenic to . Polyimide composites have the following properties: Polyimide film possesses a unique combination of properties that make it ideal for a variety of applications in many different industries especially as excellent physical, electrical, and mechanical properties are maintained over a wide temperature range. High-performance polyimide resin is used in electrical, wear resistant and as structural materials when combined with reinforcement for aircraft-aerospace applications, which are replacing heavier more expensive metals. High temperature processing causes some technical problems as well as higher costs compared to other polymers. Hysols PMR series is an example of this polymer | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Thermoset polyurethane prepolymers with carbamate (-NH-CO-O-) links are linear and elastomeric if formed by combining diisocyanates (OCN-R1-NCO) with long chain diols (HO-R2-OH), or crosslinked and rigid if formed from combinations of polyisocyanates and, polyols. They can be solid or have an open cellular structure if foamed, and are widely used for their characteristic high adhesion and resistance to fatigue. Polyurethane foam structural cores combined with glass-reinforced or graphite-reinforced composite laminates are used to make lightweight, strong, sandwich structures. All forms of the material, inclusive of flexible and rigid foams, foam moldings, solid elastomeric moldings and extrudates, when combined with various reinforcement–fillers have found commercial applications in thermoset polymer matrix composites. They differ from polyureas which are thermoset elastomeric polymers with carbamide (-NH-CO-NH-) links made by combining diisocyanate monomers or prepolymers (OCN-R-NCO) with blends of long-chain amine-terminated polyether or polyester resins (H2N-RL-NH2) and short-chain diamine extenders (H2N-RS-NH2). Polyureas are characterised by near instantaneous cure, high mechanical strength and resistance to corrosion so are widely used for 1:1 volume mix ratio spray applied, abrasion resistant waterproofing protective coating and lining | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Silicone resins are partly organic in nature with a backbone polymer structure made of alternating silicon and oxygen atoms rather than the familiar carbon-to-carbon backbone characteristics of organic polymers. In addition to having at least one oxygen atom bonded to each silicon atom, silicone resins have direct bonds to carbon and therefore also known as polyorganosiloxanes. They have the general formula (R2SiO)n and the physical form (liquid, gel, elastomer or solid) and use varies with molecular weight, structure (linear, branched, caged) and nature of substituent groups (R = alkyl, aryl, H, OH, alkoxy). Aryl substituted silicone resins have greater thermal stability than alkyl substituted silicone resins when polymerised (condensation cure mechanism) at temperatures between ~300 °F (~150 °C) and ~400 °F (~200 °C). Heating above ~600 °F (~ 300 °C) converts all silicone polymers into ceramics since all organic constituents pyrolytically decompose leaving crystalline silicate polymers with the general formula (-SiO2-)n. In addition to applications as ceramic matrix composite precursors, silicone resins in the form of polysiloxane polymers made from silicone resins with pendant acrylate, vinyl ether or epoxy functionality find application as UV, electron beam and thermoset polymer matrix composites where they are characterised by their resistance to oxidation, heat and ultraviolet degradation | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Assorted other uses in the general area of composites for silicones include sealants, coating materials, and as a reusable bag material for vacuum-bag curing of composite parts. Vinyl ester resins made by addition reactions between an epoxy resin with acrylic acid derivatives, when diluted/dissolved in a vinyl functional monomer such as styrene, polymerise. The resulting thermosets are notable for their high adhesion, heat resistance and corrosion resistance. They are stronger than polyesters and more resistant to impact than epoxies. Vinyl ester resins are used for wet lay-up laminating, SMC and BMC in the manufacture and repair of corrosion and heat resistant components ranging from pipelines, vessels and buildings to transportation, marine, military and aerospace applications. Amino resins are another class of thermoset prepolymers formed by copolymerisation of amines or amides with an aldehyde. Urea-formaldehyde and melamine-formaldehyde resins, although not widely used in high performance structural composite applications, are characteristically used as the polymer matrix in molding and extrusion compounds where some use of fillers and reinforcements occurs. Urea-formaldehyde resins are widely used as the matrix binder in construction utility products such as particle board, wafer board, and plywood, which are true particulate and laminar composite structures. Melamine-formaldehyde resins are used for plastic laminating | https://en.wikipedia.org/wiki?curid=22282547 |
Thermoset polymer matrix Furan resin prepolymers made from furfuryl alcohol, or by modification of furfural with phenol, formaldehyde (methanal), urea or other extenders, are similar to amino and phenolic thermosetting resins in that cure involves polycondensation and release of water as well as heat. While they are generally cured under the influence of heat, catalysts and pressure, furan resins can also be formulated as dual-component no-bake acid-hardened systems which are characterised by high resistance to heat, acids and alkalies. Furan resins are of increasing interest for the manufacture of sustainable composites - biocomposites made from a bio-derived matrix (in this case furan resin), or biofibre reinforcement, or both. | https://en.wikipedia.org/wiki?curid=22282547 |
Silver selenite is an inorganic compound of formula AgSeO. It is formed during recovery from copper anode slimes when they are subjected to oxidative roasting where a part of silver selenide is converted to selenite. | https://en.wikipedia.org/wiki?curid=22283945 |
C2H3NO CHNO may refer to: Compounds sharing the molecular formula: | https://en.wikipedia.org/wiki?curid=22287990 |
Macle is a term used in crystallography. It is a crystalline form, twin-crystal or double crystal (such as chiastolite). It is crystallographic twin according to the spinel twin law and is seen in octahedral crystals of minerals such as diamond and spinel. The twin law name comes from the fact that is commonly observed in the mineral spinel. "Macle" is an old French word, a heraldic term for a voided lozenge (one diamond shape within another). Etymologically the word is derived from the Latin "macula" meaning spot, mesh, or hole. | https://en.wikipedia.org/wiki?curid=22292348 |
Solvothermal synthesis is a method of producing chemical compounds. It is very similar to the hydrothermal route (where the synthesis is conducted in a stainless steel autoclave), the only difference being that the precursor solution is usually non-aqueous (however, this is not always the case in all uses of the expression in the scientific literature). Using the solvothermal route gains one the benefits of both the sol-gel and hydrothermal routes. Thus, solvothermal synthesis allows for the precise control over the size, shape distribution, and crystallinity of metal oxide nanoparticles or nanostructure products. These characteristics can be altered by changing certain experimental parameters, including reaction temperature, reaction time, solvent type, surfactant type, and precursor type. has been used in laboratory to make nanostructured titanium dioxide, graphene, carbon spheres, chalcogenides and other materials. | https://en.wikipedia.org/wiki?curid=22298230 |
Eco pickled surface (EPS) is a process applied to hot rolled sheet steel to remove all surface oxides (mill scale) and clean the steel surface. Steel which has undergone the EPS process acquires a high degree of resistance to subsequent development of surface oxide (rust), so long as it does not come into direct contact with moisture. EPS was developed by The Material Works, Ltd., which has filed several patent applications covering the process. It is primarily intended to be a replacement of the familiar acid pickling process wherein steel strip is immersed in solutions of hydrochloric and sulfuric acids to chemically remove oxides. The EPS process (see Figure 2) begins with hot rolled strip steel in coil form. This steel pays off of an uncoiler, then passes through a machine which serves the purpose of "scale breaker", "leveler" or both. This machine (see Figure 2) works the material between sets of hardened rollers. This has the effect of removing the curvature of the strip ("coil set") and breaking loose the outer layers of mill scale which encase the steel strip. After passing through the "scale breaker/leveler" machine, the steel strip enters the first "EPS slurry blasting cell". Slurry blasting is a wet abrasive blasting process that combines a fine-particle metallic abrasive with a "carrier liquid" (the most common one being water). This abrasive + water slurry mixture is fed into a rotating impeller which propels it at high velocity across the object to be cleaned (see Figure 3) | https://en.wikipedia.org/wiki?curid=22298596 |
Eco pickled surface Slurry blasting is a method for removing rust/scale, for blast cleaning and shot peening. Cleaning agents can be introduced into the carrier liquid to reduce smut and aid in rust prevention. An EPS slurry blasting cell is composed of eight of the slurry discharge heads shown in Figure 3 – four for the top surface and four for the bottom surface of the strip. Inside the slurry blasting cell, jets of water cleanse the steel strip of both the abrasive particles and the dislodged mill scale. An EPS production system may use multiple EPS slurry blasting cells arranged in tandem, so the steel strip passes from one cell into the next, then into the next, and so on. Multiple cells increase the exposure of the steel strip to the slurry blast streams, thereby allowing the strip to move faster, yet still achieve the necessary level of scale removal. The strip speed and, therefore, system output increases in rough proportion to the number of EPS slurry blasting cells used. The strip emerges from the final blasting cell and is dried using high-velocity air blowers. At this point the strip passes beneath a real-time oxide detector camera, which provides feedback to the line control to assure full oxide removal is accomplished. To conclude the process, the strip may, optionally, have an oil film or lubricant applied, then it is recoiled. Of note is that tension created by the force of the recoiler pulling the strip through the scale breaker/leveler serves to flatten the strip, removing bow, edge wave and minor coil breaks | https://en.wikipedia.org/wiki?curid=22298596 |
Eco pickled surface Also, not shown in Figure 2 is the slurry delivery/recirculation/filtering system. This closed-loop system collects the carrier liquid, abrasive and removed scale, filters out the removed scale, other contaminants and "undersized" abrasive particles, and returns a cleansed slurry mixture back to the blasting cells. Steel which utilizes the EPS process to remove surface scale shows few differences from steel which utilizes acid pickling to remove surface scale. "Downstream" industrial processes such as galvanizing, cold reducing and painting of EPS-processed steel strip show it to be interchangeable with acid-pickled steel strip. This also holds true for common sheet metal fabrication processes, such as laser cutting, plasma cutting, stamping, welding, bending, and roll forming – no meaningful difference between steel strip using the EPS process and steel strip using acid pickling. An area where the difference between EPS-processed steel strip and acid-pickled steel strip is apparent is visual appearance. Steel which has undergone EPS processing exhibits a more uniform, lustrous appearance, as shown in Figure 4. In the EPS process, the impact of the abrasive particles on the steel surface serves to "smooth out" minor surface imperfections such as scratches, pits, roll marks and silicone streaks. Another area of difference between EPS-treated steel strip and acid-pickled steel strip is rust resistance | https://en.wikipedia.org/wiki?curid=22298596 |
Eco pickled surface Conventional acid-pickled steel strip is frequently coated with a thin film of oil to serve as a barrier to contact with oxygen so as to prevent rusting. EPS-processed steel is inherently rust-inhibitive and, therefore, needs no oil or other coating to prevent rusting. Many "downstream" processes and steel fabrication processes must have the steel's oil coating (or other surface contaminants) removed as a precursor step of the process. Use of EPS-treated steel in these processes precludes the need for any such "oil-stripping" precursor step, thereby simplifying the process. The rust resistance of EPS-processed steel strip is superior to that of acid pickled steel strip primarily because acid pickling imposes a corrosion "penalty" on the steel which EPS processing does not. This penalty is a result of chemical reactions that occur after acid pickling and serve as a catalyst for oxidation. The primary pickling agent is hydrochloric acid (HCl). Although the steel strip is thoroughly rinsed with clean water after immersion in the HCl bath, some residual amount of chlorine (Cl) remains on the surface of the strip. Chlorine reacts very readily with oxygen to form chlorides, so the free Cl acts as something of a "magnet" for oxygen. This mechanism makes acid-pickled steel more prone to picking up oxygen, whereas there is no comparable mechanism at work with EPS mechanical pickling | https://en.wikipedia.org/wiki?curid=22298596 |
Eco pickled surface In addition to the free Cl, compounds known as "chloride salts" remain on the surface of acid pickled steel in trace amounts, even after rinsing. Chloride salts react rapidly with moisture and accelerate oxidation of iron on the steel's surface. To prevent oxidation of the iron in the acid pickled strip, a thin film of oil is applied to the surface to serve as a barrier between the free Cl, chloride salts and oxygen. No such protective barrier is needed for EPS-processed steel, as no free Cl or chloride salts are present. However, an additive is used in the EPS slurry blast carrier liquid to reduce the "smut" that would otherwise remain on the surface and dull the appearance of EPS-processed strip. This additive contains a rust inhibitor, a residual amount of which remains on the surface even after rinsing. It is believed that the presence of the rust inhibitor adds to the overall EPS-processed strip's ability to resist rusting. The additive has been demonstrated to have no impact on paint performance. The EPS process produces scale-free steel strip which is interchangeable with acid-pickled steel strip, yet the EPS process entails lower capital and operating (variable) cost than an acid-pickling line of equivalent output. For this reason the EPS process is considered to be a direct replacement of acid pickling | https://en.wikipedia.org/wiki?curid=22298596 |
Eco pickled surface In addition, the EPS process is considered less damaging to the environment than acid pickling for these reasons: technology has been tested and approved for use as a replacement for acid pickled steel by automotive manufacturers General Motors and Chrysler. The Eco Pickled Surface process was a finalist in the 2013 American Metal Market (AMM) Awards for Steel Excellence. | https://en.wikipedia.org/wiki?curid=22298596 |
Isotopic shift The isotopic shift (also called isotope shift) is the shift in various forms of spectroscopy that occurs when one nuclear isotope is replaced by another. Isotope shifts in atomic spectra are minute differences between the electronic energy levels of different isotopes of the same element. Today they are the focus of a multitude of theoretical and experimental efforts due to their importance for atomic and nuclear physics. If atomic spectra also have hyperfine structure the shift refers to the center of gravity of the spectra. From a nuclear physics perspective, isotope shifts combine different precise atomic physics probes for studying nuclear structure, and their main use is nuclear-model-independent determination of charge-radii differences. There are two effects which contribute to this shift: In NMR spectroscopy, Isotopic effects on chemical shifts are typically small, far less than1 ppm the typical unit for measuring shifts. The NMR signals for and ("HD") are readily distinguished in terms of their chemical shifts. The asymmetry of the signal for the "protio" impurity in arises from the differing chemical shifts of and . Isotopic shifts are best known and most widely used in vibration spectroscopy where the shifts are large, being proportional to the ratio of the square root of the isotopic masses. In the case of hydrogen, the "H-D shift" is (1/2) or 1/1.41. Thus, the (totally symmetric) C-H vibration for and occur at 2917 cm and 2109 cm, respectively | https://en.wikipedia.org/wiki?curid=22303694 |
Isotopic shift This shift reflects the differing Reduced mass for the affected bonds. | https://en.wikipedia.org/wiki?curid=22303694 |
FreeON is an experimental, open source (GPL) suite of programs for linear scaling quantum chemistry, formerly known as MondoSCF. It is highly modular, and has been written from scratch for N-scaling SCF theory in Fortran95 and C. Platform independent IO is supported with HDF5. should compile with most modern Linux distributions. performs Hartree–Fock, pure density functional, and hybrid HF/DFT calculations (e.g. B3LYP) in a Cartesian-Gaussian LCAO basis. All algorithms are O(N) or O(N lg N) for non-metallic systems. Periodic boundary conditions in 1, 2 and 3 dimensions have been implemented through the Lorentz field (formula_1-point), and an internal coordinate geometry optimizer allows full (atom+cell) relaxation using analytic derivatives. Effective core potentials for energies and forces have been implemented, but Effective Core Potential (ECP) lattice forces do not work yet. Advanced features include O(N) static and dynamic response, as well as time reversible Born Oppenheimer Molecular Dynamics (MD). | https://en.wikipedia.org/wiki?curid=22304651 |
Ishikawa reagent Ishikawa's reagent is a fluorinating reagent used in organic chemistry. It is used to convert alcohols into alkyl fluorides and carboxylic acids into acyl fluorides. Aldehydes and ketones do not react with it. The reagent consists of a mixture of "N","N"-diethyl-(1,1,2,3,3,3-hexafluoropropyl)amine and "N","N"-diethyl-("E")-pentafluoropropenylamine in varying proportions. The active species is the hexafluoropropylamine; any enamine is converted into this by the hydrogen fluoride byproduct as the reaction proceeds. Ishikawa's reagent is a popular alternative to the DAST reagent, since it is shelf-stable and easily prepared from inexpensive and innocuous reagents. It is an improvement on Yarovenko's reagent, the adduct of chlorotrifluoroethylene and diethylamine, which must be prepared in a sealed vessel and once prepared keeps only for a few days, even in the refrigerator. The reagent is mostly used to convert primary alcohols to alkyl fluorides under mild conditions with high yield. However, secondary and tertiary alcohols give a substantial amount of alkenes and ethers as side products. The compound is prepared by adding hexafluoropropene to a solution of diethylamine in ether at 0 °C and distilling the product "in vacuo". The amount of enamine in the product depends on temperature control during the reaction – the higher the temperature the more enamine. | https://en.wikipedia.org/wiki?curid=22307758 |
Differentiation-inducing factor (DIF) is one of a class of effector molecules that induce changes in cell chemistry, inhibiting growth and promoting differentiation of cell type. This name has been given to several factors before it was clear if they were the same or different effectors. More recently DIFs have garnered interest with their potential tumor inhibiting properties. DIFs have also been used to help regulate plant growth. "Dictyostelium discoideum" has been used since the 1940s to study cellular and developmental biology. It is well-suited for this research because it only develops two types of cells (stalk and spore) during morphogenesis. Each cell type has a distinct physical origin within the organism; pre-stalk cells coming from the anterior side and pre-spore cells from the posterior. Early evidence showed the differentiation of dense patches of pre-stalk cells were induced by cyclic AMP (cAMP) along with "a factor" that was likely low in molecular weight and able to diffuse across membranes. The structures for DIF-1, DIF-2, and DIF-3 were identified as these factors for stalk differentiation and subsequently synthesized to further research into implications for developmental biology. DIFs 1-3 are chlorinated hexaphenones (phenylalkan-1-ones, with chloro, hydroxy and methoxy substitution on the benzene ring), and have been isolated from "Dictyostelium discoideum" slime mold. Some research has shown that they have a role in controlling chemotaxis of "Dictyostelium discoideum", too | https://en.wikipedia.org/wiki?curid=22307956 |
Differentiation-inducing factor DIF-1 and DIF-3 are related in structure and function. DIF-3 is formed from the first step in the breakdown of DIF-1. In this state DIF-3 only performs about 3.5% as much of the activity of its predecessor. DIF-2 is unrelated to DIFs -1 and -3, but it works 40% as well as DIF-1 does to induce differentiation in stalk cells. Despite this similarity in function during differentiation, DIFs -1 and -2 act very differently in chemotactic movement of the cells toward cAMP. DIF-1 has a slight inhibitory effect on movement of starved cells toward cAMP, while DIF-2 has a strong positive effect of movement of these cells toward cAMP. These effects are thought to be carried out through phosphodiesterase activations that impact cGMP production to impact chemotaxis. An increase in chemotaxis can be related to malignant migration of cancer cells. Investigation into the anti-tumor properties of DIFs have followed one main line; the disruption of a pathway necessary for the cancer's uncontrolled growth reducing its proliferative ability. As mentioned above, the ability of DIF-1 to decrease movement of proliferating cells toward sources of energy could serve as an anti-tumor property. In another example, DIF-1 has been shown to reduce the proliferation of gastric cancer cells via upregulation of the MEK-ERK-dependent pathway. Other studies have shown how complicated the anti-tumor interactions of DIFs may be, especially when considering the indirect impacts DIFs have on target molecules | https://en.wikipedia.org/wiki?curid=22307956 |
Differentiation-inducing factor For instance, DIF-like molecules have been shown to inhibit cell growth and bring about cell death through uncoupling in mitochondria. More recent focus has been on the potential therapeutic effects DIF-like molecules. Derivatives of DIF-1 and DIF-3 have already been investigated with promising initial results. One group of derivatives yielded two DIF-1-like compounds that were effective in suppression of IL-2 production which could be helpful in controlling septic responses and other infections. | https://en.wikipedia.org/wiki?curid=22307956 |
Niobium bromide may refer to | https://en.wikipedia.org/wiki?curid=22308837 |
Deoxycorticosterone (DOC), or desoxycorticosterone, may refer to: | https://en.wikipedia.org/wiki?curid=22311468 |
Androstanediol may refer to: | https://en.wikipedia.org/wiki?curid=22311834 |
C19H28O3 The molecular formula CHO may refer to: | https://en.wikipedia.org/wiki?curid=22312854 |
Pregnanediol Pregnanediol, or 5β-pregnane-3α,20α-diol, is an inactive metabolic product of progesterone. A test can be done to measure the amount of pregnanediol in urine, which offers an indirect way to measure progesterone levels in the body. | https://en.wikipedia.org/wiki?curid=22312911 |
Pregnanetriol Pregnanetriol, or 5β-pregnane-3α,17α,20α-triol, is a steroid and inactive metabolite of progesterone. Urine excretion of pregnanetriol can be measured over a period of 24 hours. Elevated urine pregnanetriol levels suggest adrenogenital syndrome. In monitoring treatment with cortisol replacement, elevated urine pregnanetriol levels indicate insufficient dosage of cortisol. For females: For males: | https://en.wikipedia.org/wiki?curid=22312918 |
Isomeric shift The isomeric shift (also called isomer shift) is the shift on atomic spectral lines and gamma spectral lines, which occurs as a consequence of replacement of one nuclear isomer by another. It is usually called isomeric shift on atomic spectral lines and Mössbauer isomeric shift respectively. If the spectra also have hyperfine structure the shift refers to the center of gravity of the spectra. The isomeric shift provides important information about the nuclear structure and the physical, chemical or biological environment of atoms. More recently the effect has also been proposed as a tool in the search for the time variation of fundamental constants of nature. The isomeric shift on atomic spectral lines is the energy or frequency shift in atomic spectra, which occurs when one replaces one nuclear isomer by another. The effect was predicted by Richard M. Weiner in 1956, whose calculations showed that it should be measurable by atomic (optical) spectroscopy (see also). It was observed experimentally for the first time in 1958. The theory of the atomic isomeric shift is also used in the interpretation of the Mössbauer isomeric shift. The notion of isomer also appears in other fields such as chemistry and meteorology. Therefore, in the first publications devoted to this effect the name "nuclear isomeric shift on spectral lines" was used | https://en.wikipedia.org/wiki?curid=22314785 |
Isomeric shift Before the discovery of the Mössbauer effect, the isomeric shift referred exclusively to atomic spectra; this explains the absence of the word "atomic" in the initial definition of the effect. Subsequently, the isomeric shift was also observed in gamma spectroscopy through the Mössbauer effect and was called Mössbauer isomeric shift. For further details on the history of the isomeric shift and the terminology used, see . Atomic spectral lines are due to transitions of electrons between different atomic energy levels "E", followed by emission of photons. Atomic levels are a manifestation of the electromagnetic interaction between electrons and nuclei. The energy levels of two atoms, the nuclei of which are different isotopes of the same element, are shifted one with respect to the other, despite the fact that the electric charges "Z" of the two isotopes are identical. This is so because isotopes differ by the number of neutrons, and therefore the masses and volumes of two isotopes are different; these differences give rise to the isotopic shift on atomic spectral lines. In the case of two nuclear isomers, the number of protons and the number of neutrons are identical, but the quantum states and in particular the energy levels of the two nuclear isomers differ. This difference induces a difference in the electric charge distributions of two isomers and thus a difference δφ in the corresponding electrostatic nuclear potentials φ, which ultimately leads to a difference Δ"E" in the atomic energy levels | https://en.wikipedia.org/wiki?curid=22314785 |
Isomeric shift The isomeric shift on atomic spectral lines is then given by where ψ is the wave function of the electron involved in the transition, "e" its electric charge, and the integration is performed over the electron coordinates. The isotopic and the isomeric shift are similar in the sense that both are effects in which the finite size of the nucleus manifests itself and both are due to a difference in the electromagnetic interaction energy between the electrons and the nucleus of the atom. The isotopic shift had been known decades before the isomeric shift and provided useful but limited information about atomic nuclei. Unlike the isomeric shift, the isotopic shift was at first discovered in experiment and then interpreted theoretically (see also ). While in the case of the isotopic shift the determination of the interaction energy between electrons and nuclei is a relatively simple electromagnetic problem, for isomers the problem is more involved, since it is the strong interaction, which accounts for the isomeric excitation of the nucleus and thus for the difference of charge distributions of the two isomeric states. This circumstance explains in part why the nuclear isomeric shift was not discovered earlier: the appropriate nuclear theory and in particular the nuclear shell model were developed only in the late 1940s and early 1950s. As to the experimental observation of this shift, it also had to await the development of a new technique, that permitted spectroscopy with isomers, which are metastable nuclei | https://en.wikipedia.org/wiki?curid=22314785 |
Isomeric shift This too happened only in the 1950s. While the isomeric shift is sensitive to the internal structure of the nucleus, the isotopic shift is (in a good approximation) not. Therefore, the nuclear physics information that can be obtained from the investigation of the isomeric shift, is superior to what can be obtained from isotopic-shift studies. The measurements through the isomeric shift of e.g. the difference of nuclear radii of the excited and ground state constitute one of the most sensitive tests of nuclear models. Moreover, combined with the Mössbauer effect, the isomeric shift constitutes at present a unique tool in many other fields besides physics. According to the nuclear shell model, there exists a class of isomers, for which, in a first approximation, it is sufficient to consider one single nucleon, called the "optical" nucleon, to get an estimate of the difference between the charge distributions of the two isomer states, the rest of the nucleons being "filtered out". This applies in particular for isomers in odd-proton–even-neutron nuclei, with nearly closed shells. Indium-115, for which the effect was calculated, is such an example. The result of the calculation was that the isomeric shift on atomic spectral lines, although rather small, turned out to be two orders of magnitude bigger than a typical natural line width, which constitutes the limit of optical measurability | https://en.wikipedia.org/wiki?curid=22314785 |
Isomeric shift The shift measured three years later in Hg-197 was quite close to that calculated for In-115, although in Hg-197, unlike in In-115, the optical nucleon is a neutron instead of a proton, and the electron–free-neutron interaction is much smaller than the electron—free-proton interaction. This is a consequence of the fact that the optical nucleons are not free, but bound particles. Thus the results could be explained within the theory by associating with the odd optical neutron an effective electric charge of "Z"/"A". The Mössbauer isomeric shift is the shift seen in gamma-ray spectroscopy when one compares two different nuclear isomeric states in two different physical, chemical or biological environments, and is due to the combined effect of the recoil-free Mössbauer transition between the two nuclear isomeric states and the transition between two atomic states in those two environments. The isomeric shift on atomic spectral lines depends on the electron wave function ψ and on the difference δφ of electrostatic potentials φ of the two isomeric states. For a given nuclear isomer in two different physical or chemical environments (different physical phases or different chemical combinations), the electron wave functions are also different. Therefore, on top of the isomeric shift on atomic spectral lines, which is due to the difference of the two nuclear isomer states, there will be a shift between the two environments (because of the experimental arrangement, these are called source (s) and absorber (a)) | https://en.wikipedia.org/wiki?curid=22314785 |
Isomeric shift This combined shift is the Mössbauer isomeric shift, and it is described mathematically by the same formalism as the nuclear isomeric shift on atomic spectral lines, except that instead of one electron wave function, that in the source ψ, one deals with the difference between the electron wave function in the source ψ and the electron wave function in the absorber ψ: The first measurement of the isomeric shift in gamma spectroscopy with the help of the Mössbauer effect was reported in 1960, two years after its first experimental observation in atomic spectroscopy. By measuring this shift, one obtains important and extremely precise information, both about the nuclear isomer states and about the physical, chemical or biological environment of the atoms, represented by the electronic wave functions. Under its Mössbauer variant, the isomeric shift has found important applications in domains as different as atomic physics, solid-state physics, nuclear physics, chemistry, biology, metallurgy, mineralogy, geology, and lunar research. For further literature, see also . The nuclear isomeric shift has also been observed in muonic atoms, that is, atoms in which a muon is captured by the excited nucleus and makes a transition from an atomic excited state to the atomic ground state in a time shorter than the lifetime of the excited isomeric nuclear state. | https://en.wikipedia.org/wiki?curid=22314785 |
Electromethanogenesis is a form of electrofuel production where methane is produced by direct biological conversion from electrical current and carbon dioxide. The reduction process is carried out in a microbial electrolysis cell. A 2009 article by Cheng and Logan reports that a current capture efficiency of 96% can be achieved using a 1.0 V current. | https://en.wikipedia.org/wiki?curid=22315224 |
Diaminopropane may refer to either of two isomeric chemical compounds: | https://en.wikipedia.org/wiki?curid=22316853 |
Gunnar Aksnes (8 August 1926 in Kvam, Hardanger—31 January 2010 in Bergen, Hordaland) was a Norwegian chemist and poet, the brother of the astronomer Kaare Aksnes, married to Milly Aksnes (b. 1928) Aksnes started his studies in 1945 at the University of Oslo where he completed Mag.Scient exam in 1951. He was then employed by the Norwegian Forsvarets Forskningsinstitutt (FFI), and where he worked with problem related to chemical warfare agent until 1960. Then turning his Heimatt to the West Coast, to assistant professor of organic chemistry at the Department of Chemistry at the University of Bergen (UiB). In 1962 Aksnes defended his Dr.Philos. degree, and was appointed Professor of Organic Chemistry at the UiB in 1966, a position he filled with relish until he resigned in August 1993. Some years after this he was still active at the Department of Chemistrywith holding a senior scholarship from 'Norges Allmennvitenskapelige Forskningsråd' (NAVF). His academic interests ranged wide. Through his work on nerve gases at FFI he was attracted to the phosphorus chemistry. This was his major research field in which he published articles through the years, including many important scientific works that made his name well known in the scientific community world wide. In the late 1970s he started to work with chemical problems connected to environmental issues. As one of the first chemists in Norway, he recognized the importance of inter-disciplinary cooperation when scientists work on solving multi-disciplinary problems | https://en.wikipedia.org/wiki?curid=22317756 |
Gunnar Aksnes He took a strong interest in NAVF major Research program on marine pollution and built up a team of specialists in oil chemistry at the University of Bergen, together with younger employees. Later he focused on pollution of lakes, and here his knowledge of chemistry came to its right, when he extracted new knowledge from the previously published data. Aksnes was a popular lecturer, and all his students at the basic course in organic chemistry remember his loudly, involved explanations about organic molecule that moves and reacts. As a student mentor, he was always interested in the work of the students, and he asked critical questions that helped developing critical thinking and expanded the mind of the student. He also raised critical questions in popular scientific articles in professional magazines, the last concerning the mercury of the German U-boat in the fjord off Fedje. Through articles and interviews in the press, and through several popular books on environmental issues for nonscientists, he showed his engagement throughout his lifetime. He served in several administrative tasks, not only on at the Faculty of Mathematics and Natural Sciences (Dean 1969-72) and head of the Chemical institute (1991–93) at UiB, but also as a member of Council of Natural Sciences at NAVF (1970–76, as leader 1970-71). Aksnes also wrote poems, and in 2001 he published the book "Med penn og pensel i Hardanger" (With pen and brush in Hardanger) with the publisher 'Hardangerforlaget' in Øystese | https://en.wikipedia.org/wiki?curid=22317756 |
Gunnar Aksnes The book was richly illustrated by his wife Milly Aksnes. The poems in the book were written in the period from 1970 to 2001, and the illustrations are inspired by the scenery of Hardanger. | https://en.wikipedia.org/wiki?curid=22317756 |
Polymeric foam A polymeric foam is a foam, in liquid or solidified form, formed from polymers. Examples include: | https://en.wikipedia.org/wiki?curid=22319138 |
Hydrophobicity scales are values that define the relative hydrophobicity or hydrophilicity of amino acid residues. The more positive the value, the more hydrophobic are the amino acids located in that region of the protein. These scales are commonly used to predict the transmembrane alpha-helices of membrane proteins. When consecutively measuring amino acids of a protein, changes in value indicate attraction of specific protein regions towards the hydrophobic region inside lipid bilayer. The hydrophobic or hydrophilic character of a compound or amino acid is sometimes called its hydropathic character, hydropathicity, or even "hydropathy" (which originally meant the therapeutic use of water). The hydrophobic effect represents the tendency of water to exclude non-polar molecules. The effect originates from the disruption of highly dynamic hydrogen bonds between molecules of liquid water. Polar chemical groups, such as OH group in methanol do not cause the hydrophobic effect. However, a pure hydrocarbon molecule, for example hexane, cannot accept or donate hydrogen bonds to water. Introduction of hexane into water causes disruption of the hydrogen bonding network between water molecules. The hydrogen bonds are partially reconstructed by building a water "cage" around the hexane molecule, similar to that in clathrate hydrates formed at lower temperatures. The mobility of water molecules in the "cage" (or solvation shell) is strongly restricted | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales This leads to significant losses in translational and rotational entropy of water molecules and makes the process unfavorable in terms of free energy of the system. In terms of thermodynamics, the hydrophobic effect is the free energy change of water surrounding a solute. A positive free energy change of the surrounding solvent indicates hydrophobicity, whereas a negative free energy change implies hydrophilicity. In this way, the hydrophobic effect not only can be localized but also decomposed into enthalpic and entropic contributions. A number of different hydrophobicity scales have been developed. There are clear differences between the four scales shown in the table. Both the second and fourth scales place cysteine as the most hydrophobic residue, unlike the other two scales. This difference is due to the different methods used to measure hydrophobicity. The method used to obtain the Janin and Rose et al. scales was to examine proteins with known 3-D structures and define the hydrophobic character as the tendency for a residue to be found inside of a protein rather than on its surface. Since cysteine forms disulfide bonds that must occur inside a globular structure, cysteine is ranked as the most hydrophobic. The first and third scales are derived from the physiochemical properties of the amino acid side chains. These scales result mainly from inspection of the amino acid structures. Biswas et al., divided the scales based on the method used to obtain the scale into five different categories | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales The most common method of measuring amino acid hydrophobicity is partitioning between two immiscible liquid phases. Different organic solvents are most widely used to mimic the protein interior. However, organic solvents are slightly miscible with water and the characteristics of both phases change making it difficult to obtain pure hydrophobicity scale. Nozaki and Tanford proposed the first major hydrophobicity scale for nine amino acids. Ethanol and dioxane are used as the organic solvents and the free energy of transfer of each amino acid was calculated. Non liquid phases can also be used with partitioning methods such as micellar phases and vapor phases. Two scales have been developed using micellar phases. Fendler et al. measured the partitioning of 14 radiolabeled amino acids using sodium dodecyl sulfate (SDS) micelles. Also, amino acid side chain affinity for water was measured using vapor phases. Vapor phases represent the simplest non polar phases, because it has no interaction with the solute. The hydration potential and its correlation to the appearance of amino acids on the surface of proteins was studied by Wolfenden. Aqueous and polymer phases were used in the development of a novel partitioning scale. Partitioning methods have many drawbacks. First, it is difficult to mimic the protein interior. In addition, the role of self solvation makes using free amino acids very difficult | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales Moreover, hydrogen bonds that are lost in the transfer to organic solvents are not reformed but often in the interior of protein. can also be obtained by calculating the solvent accessible surface areas for amino acid residues in the expended polypeptide chain or in alpha-helix and multiplying the surface areas by the empirical solvation parameters for the corresponding types of atoms. A differential solvent accessible surface area hydrophobicity scale based on proteins as compacted networks near a critical point, due to self-organization by evolution, was constructed based on asymptotic power-law (self-similar) behavior. This scale is based on a bioinformatic survey of 5526 high-resolution structures from the Protein Data Bank. This differential scale has two comparative advantages: (1) it is especially useful for treating changes in water-protein interactions that are too small to be accessible to conventional force-field calculations, and (2) for homologous structures, it can yield correlations with changes in properties from mutations in the amino acid sequences alone, without determining corresponding structural changes, either in vitro or in vivo. Reversed phase liquid chromatography (RPLC) is the most important chromatographic method for measuring solute hydrophobicity. The non polar stationary phase mimics biological membranes. Peptide usage has many advantages because partition is not extended by the terminal charges in RPLC | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales Also, secondary structures formation is avoided by using short sequence peptides. Derivatization of amino acids is necessary to ease its partition into a C18 bonded phase. Another scale had been developed in 1971 and used peptide retention on hydrophilic gel. 1-butanol and pyridine were used as the mobile phase in this particular scale and glycine was used as the reference value. Pliska and his coworkers used thin layer chromatography to relate mobility values of free amino acids to their hydrophobicities. About a decade ago, another hydrophilicity scale was published, this scale used normal phase liquid chromatography and showed the retention of 121 peptides on an amide-80 column. The absolute values and relative rankings of hydrophobicity determined by chromatographic methods can be affected by a number of parameters. These parameters include the silica surface area and pore diameter, the choice and pH of aqueous buffer, temperature and the bonding density of stationary phase chains. ip mw hydrophobicity proteins This method use DNA recombinant technology and it gives an actual measurement of protein stability. In his detailed site-directed mutagenesis studies, Utani and his coworkers substituted 19 amino acids at Trp49 of the tryptophan synthase and he measured the free energy of unfolding. They found that the increased stability is directly proportional to increase in hydrophobicity up to a certain size limit | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales The main disadvantage of site-directed mutagenesis method is that not all the 20 naturally occurring amino acids can substitute a single residue in a protein. Moreover, these methods have cost problems and is useful only for measuring protein stability. The hydrophobicity scales developed by physical property methods are based on the measurement of different physical properties. Examples include, partial molar heat capacity, transition temperature and surface tension. Physical methods are easy to use and flexible in terms of solute. The most popular hydrophobicity scale was developed by measuring surface tension values for the naturally occurring 20 amino acids in NaCl solution. The main drawbacks of surface tension measurements is that the broken hydrogen bonds and the neutralized charged groups remain at the solution air interface. Another physical property method involve measuring the solvation free energy. The solvation free energy is estimated as a product of an accessibility of an atom to the solvent and an atomic solvation parameter. Results indicate the solvation free energy lowers by an average of 1 Kcal/residue upon folding. Palliser and Parry have examined about 100 scales and found that they can use them for locating B-strands on the surface of proteins. were also used to predict the preservation of the genetic code. Trinquier observed a new order of the bases that better reflect the conserved character of the genetic code | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales They believed new ordering of the bases was uracil-guanine-cystosine-adenine(UGCA)better reflected the conserved character of the genetic code compared to the commonly seen ordering UCAG. The Wimley–White whole residue hydrophobicity scales are significant for two reasons. First, they include the contributions of the peptide bonds as well as the sidechains, providing absolute values. Second, they are based on direct, experimentally determined values for transfer free energies of polypeptides. Two whole-residue hydrophobicity scales have been measured: The Stephen H. White website provides an example of whole residue hydrophobicity scales showing the free energy of transfer ΔG(kcal/mol) from water to POPC interface and to n-octanol. These two scales are then used together to make Whole residue hydropathy plots. The hydropathy plot constructed using ΔGwoct − ΔGwif shows favorable peaks on the absolute scale that correspond to the known TM helices. Thus, the whole residue hydropathy plots illustrate why transmembrane segments prefer a transmembrane location rather than a surface one. Most of the existing hydrophobicity scales are derived from the properties of amino acids in their free forms or as a part of a short peptide. Bandyopadhyay-Mehler hydrophobicity scale was based on partitioning of amino acids in the context of protein structure. Protein structure is a complex mosaic of various dielectric medium generated by arrangement of different amino acids | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales Hence, different parts of the protein structure most likely would behave as solvents with different dielectric values. For simplicity, each protein structure was considered as an immiscible mixture of two solvents, protein interior and protein exterior. The local environment around individual amino acid (termed as "micro-environment") was computed for both protein interior and protein exterior. The ratio gives the relative hydrophobicity scale for individual amino acids. Computation was trained on high resolution protein crystal structures. This quantitative descriptor for microenvironment was derived from log P values of small molecules, partitioned into water and octanol, (known as Rekker's Fragmental Constants) widely used for pharmacophores. This scale well correlate with the existing methods, based on partitioning and free energy computations. Advantage of this scale is it is more realistic, as it is in the context of real protein structures. In the field of engineering, the hydrophobicity (or dewetting ability) of a flat surface (e.g., a counter top in kitchen or a cooking pan) can be measured by the contact angle of water droplet. A University of Nebraska-Lincoln team recently devised a computational approach that can relate the molecular hydrophobicity scale of amino-acid chains to the contact angle of water nanodroplet. The team constructed planar networks composed of unified amino-acid side chains with native structure of the beta-sheet protein | https://en.wikipedia.org/wiki?curid=22323371 |
Hydrophobicity scales Using molecular dynamics simulation, the team is able to measure the contact angle of water nanodroplet on the planar networks (caHydrophobicity). In the other hand, previous studies show that the minimum of excess chemical potential of a hard-sphere solute with respect to that in the bulk exhibits a linear dependence on cosine value of contact angle. Based on the computed excess chemical potentials of the purely repulsive methane-sized Weeks–Chandler–Andersen solute with respect to that in the bulk, the extrapolated values of cosine value of contact angle are calculated(ccHydrophobicity), which can be used to quantify the hydrophobicity of amino acid side chains with complete wetting behaviors. | https://en.wikipedia.org/wiki?curid=22323371 |
Sulfilimine A sulfilimine (or sulfimide) is a type of chemical compound containing a sulfur-to-nitrogen double bond. The parent compound is sulfilimine HS=NH, which is mainly of theoretical interest. Examples include "S","S"-diphenylsulfilimine and such as methylphenylsulfoximine: Most sulfilimines are N-substituted with electron-withdrawing groups. These compounds are typically prepared by oxidation of thioethers with electrophilic amine reagents, such as chloramine-T in the presence of a base: An alternative route involves reactions of electrophilic sulfur compounds with amines. The limidosulfonium reagents provide a source of "MeS", which are attacked by amines. bonds stabilize collagen IV strands found in the extracellular matrix and arose at least 500 mya. These bonds covalently connect hydroxylysine and methionine residues of adjacent polypeptide strands to form a larger collagen trimer. | https://en.wikipedia.org/wiki?curid=22334859 |
PHydrion pHydrion is the trademarked name for a popular line of chemical test products, marketed by Micro Essential Laboratory, Inc., the original manufacturer of Hydrion and pHydrion products. The trademarked pHydrion product line comprises chemical test papers, chemical indicators, chemical test kits, chemical indicator kits, pH indicator pencils, chemical buffers, buffer salts, buffer preservatives, dispensers, color charts, and testing products, for use in testing, detecting, identifying, measuring, and indicating levels of pH, of sanitizers, and of other substances. | https://en.wikipedia.org/wiki?curid=22336018 |
Dichlorine trioxide Dichlorine trioxide, ClO, is a chlorine oxide. It is a dark brown solid discovered in 1967 which is explosive even below 0 °C. It is formed by the low-temperature photolysis of ClO and is formed along with ClO, Cl and O. Its structure is believed to be OCl−ClO with possible isomers such as Cl−O−ClO. It is the theoretical anhydride of chlorous acid. | https://en.wikipedia.org/wiki?curid=22342923 |
Silverquant is a labeling and detection method for DNA microarrays or protein microarrays. A synonym is <colorimetric> detection. In contrast to the classical signal detection on microarrays by using fluorescence, the colorimetric detection is more sensitive and ozone-stable. The probe to be detected is labeled with some biotin-molecules. After incubation with a gold-coupled anti-biotin conjugate, silver nitrate and a reducing agent are added. The reaction starts whereas the gold particle serves as a starting point for the silver precipitation. The reaction needs to be stopped after a specific time. The constant reaction time is essential to obtain comparable results. The silver-stained spots on the microarray are clearly visible. By using a transmission microarray scanner, the signals are transformed into digital values which are finally available as an image file. Alexandre I et al. Anal Biochem. 2001 Aug 1;295(1):1-8. | https://en.wikipedia.org/wiki?curid=22343496 |
PyQuante is an open-source (BSD) suite of programs for developing quantum chemistry methods using Gaussian type orbital (GTO) basis sets. The program is written in the Python programming language, but has "rate-determining" modules written in C for speed, and also uses and requires the NumPy linear algebra extensions to Python. The resulting code, though not as fast as other quantum chemistry programs, is much easier to understand and modify. The goal of this software is not necessarily to provide a working quantum chemistry program but rather to provide a set of tools so that scientists can construct their own quantum chemistry programs without going through the tedium of having to write every low-level routine. | https://en.wikipedia.org/wiki?curid=22344920 |
Annales d'histochimie was a peer-reviewed scientific journal established in 1956. The journal covered the field of histochemistry. | https://en.wikipedia.org/wiki?curid=22346348 |
Level spreader A level spreader is an erosion control device designed to reduce water pollution by mitigating the impact of high-velocity stormwater surface runoff. It is used both on construction sites and for permanent applications such as drainage for roads and highways. The device reduces the energy level in high-velocity flow by converting it into sheet flow, and disperses the discharged water so that it may be infiltrated into soil. Level spreaders may be used in conjunction with runoff infiltration devices such as bioretention systems, infiltration basins and percolation trenches. | https://en.wikipedia.org/wiki?curid=22348485 |
Phred base calling Phred base-calling is a computer program for identifying a base (nucleobase) sequence from a fluorescence "trace" data generated by an automated DNA sequencer that uses electrophoresis and 4-fluorescent dye method. When originally developed, Phred produced significantly fewer errors in the data sets examined than other methods, averaging 40–50% fewer errors. Phred quality scores have become widely accepted to characterize the quality of DNA sequences, and can be used to compare the efficacy of different sequencing methods. The fluorescent-dye DNA sequencing is a molecular biology technique that involves labeling single-strand DNA sequences of varied length with 4 fluorescent dyes (corresponding to 4 different bases used in DNA) and subsequently separating the DNA sequences by "slab gel"- or capillary-electrophoresis method (see DNA Sequencing). The electrophoresis run is monitored by a CCD on the DNA sequencer and this produces a time "trace" data (or "chromatogram") of the fluorescent "peaks" that passed the CCD point. Examining the fluorescence peaks in the trace data, we can determine the order of individual bases (nucleobase) in the DNA. Since the intensity, shape and the location of a fluorescence peak are not always consistent or unambiguous, however, sometimes it is difficult or time-consuming to determine (or "call") the correct bases for the peaks accurately if it is done manually | https://en.wikipedia.org/wiki?curid=22359140 |
Phred base calling Automated DNA sequencing techniques have revolutionized the field of molecular biology – generating vast amounts of DNA sequence data. However, the sequence data is produced at a significantly higher rate than can be manually processed (i.e. interpreting the trace data to produce the sequence data), thereby creating a bottleneck. To remove the bottleneck, both automated software that can speed up the processing with improved accuracy and a reliable measure of the accuracy are needed. To meet this need, many software programs have been developed. One such program is Phred. Phred was originally conceived in the early 1990s by Phil Green, then a professor at Washington University in St. Louis. LaDeana Hillier, Michael Wendl, David Ficenec, Tim Gleeson, Alan Blanchard, and Richard Mott also contributed to the codebase and algorithm. Green moved to University of Washington in the mid 1990s, after which development was primarily managed by himself and Brent Ewing. Phred played a notable role in the Human Genome Project, where large amounts of sequence data were processed by automated scripts. It was at the time the most widely used base-calling software program by both academic and commercial DNA sequencing laboratories because of its high base calling accuracy. Phred is distributed commercially by CodonCode Corporation, and used to perform the "Call bases" function in the program CodonCode Aligner. It is also used by the MacVector plugin Assembler. Phred uses a four-phase procedure as outlined by Ewing "et al | https://en.wikipedia.org/wiki?curid=22359140 |
Phred base calling " to determine a sequence of base calls from the processed DNA sequence tracing: The entire procedure is rapid, usually taking less than half a second per trace. Phred is often used together with another software program called Phrap, which is a program for DNA sequence assembly. Phrap was routinely used in some of the largest sequencing projects in the Human Genome Sequencing Project and is currently one of the most widely used DNA sequence assembly programs in the biotech industry. Phrap uses Phred quality scores to determine highly accurate consensus sequences and to estimate the quality of the consensus sequences. Phrap also uses Phred quality scores to estimate whether discrepancies between two overlapping sequences are more likely to arise from random errors, or from different copies of a repeated sequence. | https://en.wikipedia.org/wiki?curid=22359140 |
C2H3N3 The molecular formula CHN may refer to: | https://en.wikipedia.org/wiki?curid=22359392 |
C2H4N4 CHN may refer to: Compounds sharing the molecular formula: | https://en.wikipedia.org/wiki?curid=22359420 |
UN Recommendations on the Transport of Dangerous Goods The are contained in the UN Model Regulations prepared by the Subcommittee of Experts on the Transport of Dangerous Goods of the United Nations Economic and Social Council (ECOSOC). They cover the transport of dangerous goods by all modes of transport except by bulk tanker. They are not obligatory or legally binding on individual countries, but have gained a wide degree of international acceptance: they form the basis of several international agreements and many national laws. "Dangerous goods" (also known as "hazardous materials" or "HAZMAT" in the United States) may be pure chemical substance (for example, trinitrotoluene (TNT), nitroglycerin), mixtures (for example, dynamite, gunpowder) or manufactured articles (for example, ammunition, fireworks). The transport hazards that they pose are grouped into nine classes, which may be subdivided into divisions and/or packing groups. The most common dangerous goods are assigned a UN number, a four digit code which identifies it internationally: less common substances are transported under generic codes such as "UN1993: flammable liquid, not otherwise specified". The "UN Recommendations" do not cover the manufacture, use or disposal of dangerous goods. The first version of the "Recommendations on the Transport of Dangerous Goods" was produced by the ECOSOC in 1956 | https://en.wikipedia.org/wiki?curid=22359662 |
UN Recommendations on the Transport of Dangerous Goods From 1996, the "Recommendations" were effectively split into two parts: the "Model Regulations", which form a suggested drafting for laws and regulations on the transport of dangerous goods; and the "Manual of Tests and Criteria", which contains technical information about methods of testing products to ascertain their hazards. The 21st edition of the "Recommendations" was published in 2019. The container requirements include some material and construction requirements but also performance testing is required. The package testing is based on the packing group (hazard level) of the contents, the quantity of material, and the type of container. The UN recommendations are implemented by regulatory bodies in each country: Transport Canada, United States Department of Transportation, etc. Some carriers have additional requirements. | https://en.wikipedia.org/wiki?curid=22359662 |
C3F6O The molecular formula CFO (molar mass: 166.022 g/mol) may refer to: | https://en.wikipedia.org/wiki?curid=22359872 |
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