text stringlengths 11 1.65k | source stringlengths 38 44 |
|---|---|
C16H16ClN3O3S The molecular formula CHClNOS may refer to: | https://en.wikipedia.org/wiki?curid=41295527 |
European Young Chemists' Network The (EYCN) is the young division of the European Chemical Society (EuChemS), and aims at promoting chemistry among young people, under the age of 35, that belong to a fellow European society. Founded in 2006, the idea for a (EYCN) within EuChemS was formed during several young scientist meetings in Europe. On the 31st August 2006, during the 1st European Chemistry Congress (ECC) in Budapest, a paper was written entitled "Aims, Tasks and Goals of EYCN", which was seen to be the foundation of the EYCN. In March 2007, Jens Breffke (Germany) and Csaba Janaky (Hungary) invited all societies to send their young representatives to Berlin in order to set the rules of EYCN. These were later confirmed by the Executive Committee of EuChemS. Meanwhile, EYCN reached out to all young chemists within the European Chemical Society (EuChemS) framework to exchange knowledge, experiences and ideas. The EYCN consists of a Board with three Executive Board members and five complementary teams (Membership Team, Networks Team, Global Connections Team, Science Team and Communication Team) that have their own responsibilities, and each is managed by a Team Leader. The Delegate Assembly (DA), a meeting of the national chemical societies' representatives, takes place annually and the Board members and the Team Leaders are elected biennially | https://en.wikipedia.org/wiki?curid=41305472 |
European Young Chemists' Network Being one of the most active divisions of EuChemS, the EYCN’s main goal is to support and mentor students, early career researchers and professionals through awards (best poster and best oral presentation prizes, the European Young Chemist Award - EYCA), exchange programs (congress fellowships, Young Chemists Crossing Borders - YCCB program) and educational activities (conferences, Career Days, soft-skills symposiums). The EYCN successfully collaborates with other early-career chemistry networks both within and outside of Europe. It has built a particularly prolific collaboration with the American Chemical Society - Younger Chemists Committee (ACS-YCC) and is actively cooperating with the International Younger Chemists Network (IYCN). In addition to the financial support from EuChemS, the EYCN is also supported by the EVONIK Industries. In order to bring science closer to a broader audience, the EYCN organizes the photography contest Photochimica since 2016, in collaboration with the Royal Society of Chemistry (RSC), and the video contest Chemistry Rediscovered. The EYCN organizes also a variety of different events, including the biennial international conference European Young Chemists’ Meeting (EYCheM), a symposium at the biennial ECC and the annual DA. There have been 15 DAs so far since the first in 2006 in Budapest, Hungary. From 2006 to 2013 the EYCN Board and the relative teams were randomly changed every one to three years. After 2013, elections took place every two years | https://en.wikipedia.org/wiki?curid=41305472 |
European Young Chemists' Network Each EYCN Board has improved the EYCN impact through several key contributions. Chair: Antonio M. Rodríguez García (Spain); Secretary: Maximilian Menche (Germany); Treasurer: Jelena Lazić (2019-20) (Serbia), Carina Crucho (2020-21) (Portugal); Communication team leader: Maxime Rossato (France); Global connection team leader: Lieke van Gijzel (The Netherlands); Membership team leader: Miguel Steiner (Austria); Networks team leader: Jovana V. Milic (Switzerland); Science team leader: Katarina Josifovska (2019-20) (North Macedonia), Robert-Andrei Țincu (2020-21) (Romania); Advisor: Alice Soldà (Italy) Chair: Alice Soldà (Italy); Secretary: Torsten John (Germany); Communication team leader: Xseniia Otvagina (Russia); Membership team leader: Jelena Lazić (Serbia); Networks team leader: Victor Mougel (France); Science team leader: Hanna Makowska (Poland); Advisor: Fernando Gomollón-Bel (Spain) Key achievements: The webpage "Chemistry across Europe" providing the basic information about chemistry in the academic and industrial field across Europe and the EYCN YouTube channel were established. The 2nd European Young Chemists' Meeting (EYCheM) was organized in collaboration with the JCF Bremen | https://en.wikipedia.org/wiki?curid=41305472 |
European Young Chemists' Network Chair: Fernando Gomollón-Bel (Spain); Secretary: Camille Oger (France); Science team leader: Oana Fronoiu (Romania); Communication team leader: Sarah Newton (UK); Networks team leader: Michael Terzidis (Greece); Membership team leader: Emanuel Ehmki (Austria) Key achievements: The rules for the election process of the EYCN board and the attendance to the DA were established and the publication of a monthly newsletter was decided. Chair: Frédérique Backaert (Belgique); Secretary: Aurora Walshe (UK); Scientific team leader: Vladimir Ene (Romania); External communication team leader: Lisa Phelan (Ireland); Membership team leader: Koert Wijnbergen (The Netherlands); Networks team leader: Anna Stefaniuk-Grams (Poland) Key achievement: First participation of the EYCN at the EuCheMS Chemistry Congress (ECC5) in Istanbul, Turkey in 2014. Chair: Cristina Todasca (Romania); Secretary: Aurora Walshe (UK) Key achievement: The EYCN was for the first time organized into teams, each with its own leader and delegates as team members. Chair: Viviana Fluxa (Switzerland); Secretary: Cristina Todasca (Romania); Relationship with industries: Lineke Pelleboer (The Netherlands); External communication: Guillaume Poisson (France); Membership and internal communication: Aurora Walshe (UK); Website designer: Magorzata Zaitz (Poland) Key achievements: Development of the EYCN's website and active participation at the 3rd EuCheMS Chemistry Congress in Nürnberg in 2010 | https://en.wikipedia.org/wiki?curid=41305472 |
European Young Chemists' Network Chair: Sergej Toews (Germany); Secretary: Helena Laavi (Finland); Relationship with industry: Viviana Fluxa (Switzerland); Communications: Dan Dumitrescu (Romania); Scientific affairs: Ilya Vorotyntsev (Russia) Key achievement: The corporate identity of the EYCN was developed. Chair: Csaba Janáky (Hungary); Secretary: Emma Dumphy (Switzerland); Treasurer: Juan Luis Delgado de la Cruz (Spain); Sponsor relations officer: Jens Breffke (Germany) Key achievement: Creation of the EYCN in Berlin from the representatives of 12 Chemical Societies representatives. The EYCN represents 30 European chemical societies and one affiliated member (the American Chemical Society). Member societies include: | https://en.wikipedia.org/wiki?curid=41305472 |
C13H8O4 The molecular formula CHO may refer to: | https://en.wikipedia.org/wiki?curid=41314653 |
Cavitation (elastomers) Cavitation is the unstable unhindered expansion of a microscopic void in a solid elastomer under the action of tensile hydrostatic stresses. This can occur whenever the hydrostatic tension exceeds 5/6 of Young's modulus. The cavitation phenomenon may manifest in any of the following situations: | https://en.wikipedia.org/wiki?curid=41318434 |
Polar point group In geometry, a polar point group is a point group in which there is more than one point that every symmetry operation leaves unmoved. The unmoved points will constitute a line, a plane, or all of space. While the simplest point group, C, leaves all points invariant, most polar point groups will move some, but not all points. To describe the points which are unmoved by the symmetry operations of the point group, we draw a straight line joining two unmoved points. This line is called a polar direction. The electric polarization must be parallel to a polar direction. In polar point groups of high symmetry, the polar direction can be a unique axis of rotation, but if the symmetry operations do not allow any rotation at all, such as mirror symmetry, there can be an infinite number of such axes: in that case the only restriction on the polar direction is that it must be parallel to any mirror planes. A point group with more than one axis of rotation or with a mirror plane perpendicular to an axis of rotation cannot be polar. Of the 32 crystallographic point groups, 10 are polar: The space groups associated with a polar point group do not have a discrete set of possible origin points that are unambiguously determined by symmetry elements. When materials having a polar point group crystal structure are heated or cooled, they may temporarily generate a voltage called pyroelectricity. Molecular crystals which have symmetry described by one of the polar space groups may exhibit triboluminescence | https://en.wikipedia.org/wiki?curid=41321254 |
Polar point group A common example of this is sucrose, demonstrated by smashing a wintergreen lifesaver in a darkened room. | https://en.wikipedia.org/wiki?curid=41321254 |
Erbium(III) bromide is a chemical compound with the chemical formula ErBr crystal which is highly soluble in water. It is used, like other metal bromide compounds, in water treatment, chemical analysis and for certain crystal growth applications. | https://en.wikipedia.org/wiki?curid=41323234 |
C24H30N2O2 The molecular formula CHNO may refer to: | https://en.wikipedia.org/wiki?curid=41323425 |
Methylsalicylic acid may refer to: | https://en.wikipedia.org/wiki?curid=41324054 |
Erbium tetraboride Erbium boride is a boride of the lanthanide metal erbium. It is hard and has a high melting point. Industrial applications of erbium boride include use in semiconductors, the blades of gas turbines, and the nozzles of rocket engines. | https://en.wikipedia.org/wiki?curid=41331583 |
Erbium(III) iodide Erbium iodide is an iodide of lanthanide metal Erbium. | https://en.wikipedia.org/wiki?curid=41332572 |
Barium boride is a hard material with a high melting point. | https://en.wikipedia.org/wiki?curid=41332950 |
Robert J. Ferrier Robert John "Robin" Ferrier FRSNZ, FNZIC, (7 August 1932 – 11 July 2013) was an organic chemist who discovered two chemical reactions, the Ferrier rearrangement and the Ferrier carbocyclization. Originally from Edinburgh, he moved to Wellington, New Zealand, in 1970. Ferrier was born in Edinburgh on 7 August 1932. Following the family's idiosyncratic naming tradition, although he was named Robert John, he was always known as Robin. Likewise his father Edward was known as William and his mother Sophia was known as Rita. William was a policeman and became head of Edinburgh CID, while Rita was a housewife. His only sibling was a fraternal twin sister Dr Barbara M. Ferrier (d. 2006), known as Ray, who likewise became an organic chemist, becoming professor emeritus of the Department of Biochemistry and Biomedical Sciences at McMaster University. A polycyclic ketone "barbaralone", related to bullvallene was named after her. Ferrier attended George Heriot's School for all of his schooling, apart from a brief time in Traquair, to where he was evacuated during the war with his mother and sister. He gained a Bachelor of Science with first class honours in 1954 and a PhD in plant polysaccharides in 1957, under Professor Gerald Aspinall. Appointed to a teaching position at Birkbeck College, University of London, Ferrier's focus turned from polysaccharides to monosaccharides | https://en.wikipedia.org/wiki?curid=41333269 |
Robert J. Ferrier New laboratory tools and methods enabled their reactions and mechanisms to be studied like normal organic compounds, rather than a separate field, and he pioneered this approach. In the early 1960s as a NATO Post Doctoral Fellow, he worked in Professor Melvin Calvin’s group at the University of California, Berkeley. They were exciting times. While Ferrier was there, Calvin was awarded the Nobel Prize for Chemistry, and he also met Carolyn Tompkins, the pair marrying in Edinburgh in 1962. Arriving in New Zealand in 1970 as Victoria University’s first Chair of Organic Chemistry, Ferrier continued to lead work on the monosaccharides, specialising in their use as starting materials for the synthesis of non-carbohydrate compounds of pharmaceutical interest. He had previously clarified the mechanism of the Fischer glycosidation and discovered an allylic rearrangement reaction of glycals, now known as the Ferrier rearrangement – the first of two reactions that bear his name. Many of Ferrier's best discoveries were made by following up unexpected chemical observations, which often led him into uncharted territory. His second ‘name’ reaction, the Ferrier carbocyclization, was the result of this approach. He served on the Toxic Substances Board in the 1980s and the leadership of the RSNZ report "Lead in the Environment" that confirmed the toxic effects of lead and began the phase-out of leaded petrol. After his retirement from Victoria University in 1998, he became an Emeritus Professor | https://en.wikipedia.org/wiki?curid=41333269 |
Robert J. Ferrier Ferrier then entered what he referred to as his 'supposed retirement', working with the carbohydrate chemists at Industrial Research Ltd. Here he continued to foster the next generation of carbohydrate chemists in New Zealand – his 'grandchildren', instilling his rigorous approach to chemistry with mentoring and assistance with the group's publications. The Ferrier Research Institute at Victoria University of Wellington was named for Ferrier. It was created on 6 January 2014 to accommodate the group of carbohydrate chemists who left Callaghan Innovation on that date. (Callaghan Innovation was previously Industrial Research Ltd.) In August 2012, Ferrier celebrated his 80th birthday and retired a second time. Later that year, the Ferrier Trust was set up in his honour, to bring a scientist to New Zealand each year, to engage with chemistry students and lecture. Peppi Prasit, a Ferrier PhD graduate and founder of Amira Pharmaceuticals and Inception Sciences in the US, was the trust's foundation donor. He was able to attend the inaugural Ferrier Lecture in March 2013. In his 50-year career, Ferrier published 180 papers, reviews and books, and gave 10 invited plenary lectures at international symposia. His reviews were of particular benefit to the chemical community but perhaps of most value was the book "Monosaccharide Chemistry, written with Dr Peter Collins in 1972 and majorly updated as "Monosaccharides: Their chemistry and their roles in natural products in 1995 | https://en.wikipedia.org/wiki?curid=41333269 |
Robert J. Ferrier Ferrier was elected Fellow of the Royal Society of New Zealand (1977) and the New Zealand Institute of Chemistry (1972) and awarded a DSc (London, 1968). | https://en.wikipedia.org/wiki?curid=41333269 |
Monochromatic wavelength dispersive x-ray fluorescence ("MWD XRF") is an enhanced version of conventional wavelength-dispersive X-ray spectroscopy ("WDXRF") elemental analysis. The key difference is that MWD XRF uses a doubly curved crystal X-ray optic between the X-ray source and the sample resulting in monochromatic excitation. This additional optic creates a high-intensity X-ray beam on a small spot size without increasing the power of the X-ray source. An MWD XRF instrument is constructed from a low-power X-ray tube, a point-to-point focusing optic for excitation, a sample cell, a focusing optic that collects the fluorescence from the sample, and an X-ray detector. By using an optic between the X-ray source and the sample, a monochromatic beam free of bremsstrahlung, excites the sample, eliciting the secondary fluorescence X-rays needed for elemental analysis. By restricting the band of wavelengths used for excitation, a much higher signal to background ratio is achieved. This type of excitation allows much lower limits of detection and faster reading times. | https://en.wikipedia.org/wiki?curid=41336594 |
Perfluorotributylamine (PFTBA), also referred to as FC43, is a colorless liquid with the formula N(CF). The compound consists of three butyl groups connected to an amine center, in which all of the hydrogen atoms have been replaced with fluorine. The compound is produced for the electronics industry, along with other perfluoroalkylamines. Unlike ordinary amines, perfluoroamines are nonbasic. It is prepared by electrofluorination of tributylamine using hydrogen fluoride as solvent and source of fluorine: The compound has two commercial uses. It is used as an ingredient in Fluosol, artificial blood. This application exploits the high solubility of oxygen and carbon dioxide in the solvent, as well as the low viscosity and toxicity. It is also a component of Fluorinert coolant liquids. CPUs of some computers are immersed in this liquid to facilitate cooling. The compound is used as a calibrant in gas chromatography when the analytical technique uses mass spectrometry as a detector to identify and quantify chemical compounds in gases or liquids. When undergoing ionization in the mass spectrometer, the compound decomposes in a repeatable pattern to form fragments of specific masses, which can be used to tune the mass response and accuracy of the mass spectrometer. Most commonly used ions are those with approximate mass of 69, 131, 219, 414 and 502 atomic mass units. Fluorofluids are generally of very low toxicity, so much that they have been evaluated as synthetic blood | https://en.wikipedia.org/wiki?curid=41337708 |
Perfluorotributylamine It is a greenhouse gas with warming properties more than 7,000 times that of carbon dioxide over a 100 year period, and, as such, is the most potent greenhouse gas ever discovered. Its concentration in the atmosphere is approximately 0.18 parts per trillion. The compound can persist in the atmosphere for up to 500 years. Sulfur hexafluoride, however, has a GWP of 23,900, which would make it much more powerful. | https://en.wikipedia.org/wiki?curid=41337708 |
Spectator ligand In coordination chemistry, a spectator ligand is a ligand that does not participate in chemical reactions of the complex. Instead, spectator ligands (vs "actor ligands") occupy coordination sites. Spectator ligands tend to be of polydentate, such that the M-spectator ensemble is inert kinetically. Although they do not participate in reactions of the metal, spectator ligands influence the reactivity of the metal center to which they are bound. These ligands are sometimes referred to as ancillary ligands. Several different classes of ligand that can be considered spectator ligands. A few examples include trispyrazolylborates (Tp), cyclopentadienyl ligands (Cp), and many chelating diphosphines such as 1,2-bis(diphenylphosphino)ethane ligands (dppe). Varying the substituents on the spectator ligands greatly influences the solubility, stability, electronic, and steric properties of the metal complex. In the area of platinum-based antineoplastic agents, spectator (and nonspectator) ligands greatly affect efficacy. | https://en.wikipedia.org/wiki?curid=41340447 |
OpenPHACTS Open PHACTS (Open Pharmacological Concept Triple Store) is a European initiative public–private partnership between academia, publishers, enterprises, pharmaceutical companies and other organisations working to enable better, cheaper and faster drug discovery. It has been funded by the Innovative Medicines Initiative, selected as part of three projects to "design methods for common standards and sharing of data for more efficient drug development and patient treatment in the future". A total of 27 partners are currently involved including: The Open Pharmacological Space created by the consortium is intended to support open innovation and in-house non-public drug discovery research by removing bottlenecks in drug development. Resources from the project are publicly available on GitHub. To reduce the barriers to drug discovery in industry, academia and for small businesses, the Open PHACTS consortium built the Open PHACTS Discovery Platform. This platform is freely available, integrating pharmacological data from a variety of information resources and providing tools and services to question this integrated data to support pharmacological research. | https://en.wikipedia.org/wiki?curid=41341760 |
C9H6O6 The molecular formula CHO may refer to: | https://en.wikipedia.org/wiki?curid=41346435 |
Flotation of flexible objects is a phenomenon in which the bending of a flexible material allows an object to displace a greater amount of fluid than if it were completely rigid. This ability to displace more fluid translates directly into an ability to support greater loads, giving the flexible structure an advantage over a similarly rigid one. Inspiration to study the effects of elasticity are taken from nature, where plants, such as black pepper, and animals living at the water surface have evolved to take advantage of the load-bearing benefits elasticity imparts. In his work "On Floating Bodies", Archimedes famously stated: While this basic idea carried enormous weight and has come to form the basis of understanding why objects float, it is best applied for objects with a characteristic length scale greater than the capillary length. What Archimedes had failed to predict was the influence of surface tension and its impact at small length scales. More recent works, such as that of Keller, have extended these principles by considering the role of surface tension forces on partially submerged bodies. Keller, for instance, demonstrated analytically that the weight of water displaced by a meniscus is equal to the vertical component of the surface tension force. Nonetheless, the role of flexibility and its impact on an object's load-bearing potential is one that did receive attention until the mid-2000s and onward. In an initial study, Vella studied the load supported by a raft composed of thin, rigid strips | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects Specifically, he compared the case of floating individual strips to floating an aggregation of strips, wherein the aggregate structure causes portions of the meniscus (and hence, resulting surface tension force) to disappear. By extending his analysis to consider a similar system composed of thin strips of some finite bending stiffness, he found that this later case in fact was able support a greater load. A well known work in the area of surface tension aided flotation was the analysis of water strider locomotion along the surface of water. Using the idea of flexible structures, Ji et al. re-examined this problem by considering the compliance of a water strider leg. By modeling the leg as a compliant structure that deforms at the water surface (rather than pierce it), Ji was able to ascertain what added benefit this flexibility has in supporting the insect. Other studies on the water strider have examined the ways in which flexibility can affect wetting properties of the leg. Another track of research has been to investigate how exactly the interaction between liquid and a compliant object leads to the resulting deformation. In one example, such analysis has been extended to explain the difficulty in submerging hairs in a fluid. These works focus on behavior near the contact line, and consider what role non-linear effects such as slippage play. In a liquid solution, any given liquid molecule experience strong cohesive forces from neighboring molecules | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects While these forces are balanced in the bulk, molecules at the surface of the solution are surrounded on one side by water molecules and on the other side by gas molecules. The resulting imbalance of cohesive forces along the surface results in a net "pull" toward the bulk, giving rise to the phenomena of surface tension. When a hydrophobic object of weight formula_1 is placed on the surface of water, its weight begins deforming the water line. The hydrophobic nature of the object means that the water will attempt to minimize contact due to an unfavorable energy tradeoff associated with wetting. As a result, surface tension attempts to pull back on the water line in order to minimize contact with the hydrophobic object and retain a lowest energy state. This action by the surface to pull back on the depressed water interface is the source of a capillary force, which acts tangentially along the contact line and thereby gives rise to a component in the vertical direction. An attempt to further depress the object is resisted by this capillary force until the contact line reaches a vertical position located about two capillary lengths below the undisturbed water line. Once this occurs, the meniscus collapses and the object sinks. The more fluid a floating object is able to displace, the greater the load it is able to bear. As a result, the ultimate payoff of flexibility is in determining whether or not a bent configuration results in an increased volume of displaced water | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects As a flexible object bends, it penetrates further into the water and increases the total fluid displaced above it. However, this bending action necessarily forces the cross-section at the water line to decrease, narrowing the column of displaced water above the object. Thus, whether or not bending is advantageous is ultimately given by a tradeoff of these factors. The following analysis is taken largely from the work of Burton and Bush, and offers some mathematical insight into the role that flexibility plays in improving load-bearing characteristics of floating objects. Consider two plates of infinite width, thickness formula_2, and length formula_3 that are connected by a torsional spring with spring constant per unit width formula_4. Furthermore, let formula_5 be the angle between a plate and the horizontal, and formula_6 the from where the meniscus meets the plate to the horizontal. The distance from the undisturbed water line to the plate's outer edge is formula_7. The density of water is formula_8, the density of air is considered negligible, and the plate density, formula_9, shall be varied. All systems naturally assume a configuration that minimizes total energy. Thus, the goal of this analysis is to identify the configurations (i.e., values of formula_7 and formula_5) that result in a stable equilibrium for a given value of formula_9 | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects For a total system energy of formula_13, it is natural to distinguish sub-components: formula_14 In defining formula_17, there are several associated components: formula_18 Similarly, the system potential energy, formula_23, is taken to be composed of two terms: formula_24 There are two ways in which the system energy can change by an incremental amount. The first is a translation of the center of mass of the plates by some distance formula_28. The second is an incremental change, formula_29 in the hinge angle. Such a change will induce a new moment. As mentioned, the system will seek the orientation that minimizes formula_30 in order to find point of stable equilibrium. Writing out these terms more explicitly: formula_31 formula_36 Here, formula_37 is the equation air/water interface, formula_38 is the incremental displacement of the interface, and formula_39 is the surface tension of water. For a given value of formula_9, stable equilibrium configurations are identified as being those values of formula_7 and formula_5 that satisfy formula_43 formula_44 Taken in a different light, these conditions can be seen as identifying formula_7 and formula_5 that result in zero net force and zero net torque for a given formula_9 | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects Defining non-dimensional plate length formula_48, non-dimensional plate edge depth formula_49, and non-dimensional load formula_50, Burton and Bush derived the following analytical results: formula_51 formula_52 formula_53 The equations for formula_54 and formula_5 give the configuration parameters that give the maximum value of formula_56. For further insight, it is helpful to examine various regimes of the non-dimensional plate length, formula_57. When the characteristic plate length is much smaller than the characteristic plate edge depth, the effects of gravity, surface tension, and spring energy become dominant. In this limiting case, it turns out that flexibility does not improve load-bearing capabilities of the plates; indeed, the optimal configuration is a flat plate. Since the plate length is so much smaller than the displacement from the undisturbed water line, the extra fluid displaced by bending a rigid plate is outweighed by the loss of fluid in the column above the plate. In this regime, flexibility may or may not improve load-bearing capabilities of the plates. The two characteristics lengths are of comparable dimension, so particular values for each determine whether or not additional fluid displaced through bending exceeds fluid lost through the narrowing of the column. In this regime, the benefit of flexibility is most pronounced. The characteristic plate length is significantly longer than the characteristic depth to which the plate is submerged beneath the water line | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects As a result, the narrowing column above the plate is negligible, which the additional displacement of water due to bending is significant. To relate this mathematical to physical systems, the above analysis can be extended to continuously deformable bodies. Generalizing the equations of the two plate system allows one to write a corresponding set of equations for the case of a continuously deformable plate. This continuously deformable plate is composed of formula_61 sub-plates, where similar force and torque equilibrium conditions described before must be satisfied for each sub-plate. Such analysis reveals that for a highly compliant 2D structure with a characteristic length much greater than the capillary length, the shape bearing the highest load is a perfect semi-circle. As stiffness increases, the semi-circle is deformed to shapes with lower curvature. This initial look at continuously deformable bodies represents an initial stab into a very complicated problem. With the groundwork laid here in this analysis, it is likely that future works will implement this general ideology in a finite element approach. Doing so will allow much closer simulation of real world phenomena and will aid in determining how effects of elasticity can aid in the design of robots, instruments, and other devices that operate along the water line. In the Brazilian rain forest, sudden rainfall can trigger flooding at a moment's notice | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects Given that flooding can potentially destroy a colony and drown the insects, fire ants have developed a unique adaptation to this situation. While individual fire ants are hydrophobic and flounder at the waters surface, large groups of ants can link together to form a living raft. As the queen and larvae are evacuated from the flooding colony, they sit upon this living raft, floating along the waterline until reaching some solid land. The importance of flexibility in this self-assembled ant raft is several fold. The extra weight-bearing that flexibility imparts is vital as hungry fish will swim along the underside of the raft and eat at many of the members. Furthermore, as waves travel along the water surface, the ant raft's flexibility allows it to effectively "roll" with the wave and minimize disturbances it would otherwise cause for a similar but rigid structure. Among aquatic vegetation, the lily pad is perhaps the most recognizable, commonly associated with ponds and lakes. Their flexibility allows for increased loads, enabling them to support animals, such as frogs, many times their own weight. Some aquatic flowers, such as the daisy Bellis perennis, use compliance as a survival mechanism. Such flowers have roots that extend down to the underlying soil, anchoring the flower to the surface of the water. When flooding occurs, the petals pull inward and deform the water line, shielding the genetic material in the core | https://en.wikipedia.org/wiki?curid=41351364 |
Flotation of flexible objects Some flowers are even known to completely close up into a shell in this fashion, trapping air inside. | https://en.wikipedia.org/wiki?curid=41351364 |
Imidoyl chloride Imidoyl halides are synthesized by combining amides and halogenating agents. The structure of the carboxylic acid amides plays a role in the outcome of the synthesis. can be prepared by treating a monosubstituted carboxylic acid amide with phosgene. Thionyl chloride is also used. Imidoyl chlorides are generally colorless liquids or low-melting solids that are sensitive to both heat and especially moisture. In their IR spectra these compounds exhibit a characteristic ν band near 1650–1689 cm. Although both the syn and anti configurations are possible, most imidoyl chlorides adopt the anti configuration. Imidoyl chlorides react readily with water, hydrogen sulfide, amines, and hydrogen halides. Treating imidoyl chlorides with water forms the corresponding amide: Aliphatic imidoyl chlorides are more sensitive toward hydrolysis than aryl derivatives. Electron-withdrawing substituents decrease the reaction rate. Imidoyl chlorides react with hydrogen sulfide to produce thioamides: When amines are treated with imidoyl chlorides, amidines are obtained. When R' ≠ R", two isomers are possible. Upon heating, imidoyl chlorides also undergo dehydrohalogenation to form nitriles: Treatment of imidoyl chloride with hydrogen halides, such as HCl, forms the corresponding iminium chloride cations: Imidoyl chlorides are useful intermediates in the syntheses of several compounds, including imidates, thioimidates, amidines, and imidoyl cyanides | https://en.wikipedia.org/wiki?curid=41351768 |
Imidoyl chloride Most of these syntheses involve replacing the chloride with alcohols, thiols, amines, and cyanates, respectively. Imidoyl chlorides can also undergo Friedel-Crafts reactions to install an imine groups on aromatic substrates. If the nitrogen of the imidoyl chloride has two substituents, the resulting chloroiminium ion is vulnerable to attack by aromatic rings without the need for a Lewis acid to remove the chloride first. This reaction is called the Vilsmeier–Haack reaction, and the chloroiminium ion is referred to as the Vilsmeier reagent. After attaching the iminium ion to the ring, the functional group can later be hydrolyzed to a carbonyl for further modification. The Vilsmeier-Haack reaction can be a useful technique to add functional groups to an aromatic ring if the ring contains electron-withdrawing groups, which make using the alternative Friedel-Crafts reaction difficult. Imidoyl chlorides can be easily halogenated at the α carbon position. By treating imidoyl chlorides with hydrogen halide, will cause all α hydrogens to be replaced with the halide. This method can be an effective way to halogenate many substances. Imidoyl chlorides can also be used to form peptide bonds by first creating amidines and then allowing them to be hydrolyzed to the amide. This approach may prove to be a useful route to synthesizing synthetic proteins. Imidoyl chlorides can be difficult to handle. Imidoyl chlorides react readily with water, which makes any attempt to isolate and store them for long periods of time difficult | https://en.wikipedia.org/wiki?curid=41351768 |
Imidoyl chloride Further, imidoyl chlorides tend to undergo self-condensation at higher temperatures if the imidoyl chloride has an α CH group. At even higher temperatures, the chlorine of the imidoyl chloride tends to be eliminated, leaving the nitrile. Because of these complications, imidoyl chlorides are typically prepared and used immediately. More stable intermediates are being sought, with substances such as imidoylbenzotriazoles being suggested. | https://en.wikipedia.org/wiki?curid=41351768 |
Neurochemical Research is a monthly peer-reviewed scientific journal covering neurochemistry. It was established in 1976 and is published by Springer Science+Business Media. The editor-in-chief is Arne Schousboe (University of Copenhagen). The journal is abstracted and indexed in: According to the "Journal Citation Reports", the journal has a 2012 impact factor of 2.125. | https://en.wikipedia.org/wiki?curid=41351843 |
Ionic hydrogenation Ionic Hydrogenation refers to hydrogenation achieved by the addition of a proton and a hydride to substrate; in contrast to traditional hydrogenation which is achieved using H. The proton and hydride transfers can be either sequential or concerted. Usually ionic hydrogenation is shown to occur in two steps, starting with protonation. is employed when the substrate can produce a stable carbonium ion. Polar double bonds are favored substrates. In the case of metal-catalyzed ionic hydrogenation, the substrates and their products must not bind to metal sites, as this would interfere with H activation. Ketones are the most common substrates. Less common are imines and N-heterocycles. The reaction can also be performed in reverse to effect hydrogenolysis. Liquid substrates can sometimes be hydrogenated without solvent, a goal of green chemistry. The most common hydrogenating pair is an organosilane as the hydride source (e.g. triethylsilane), and a strong oxyacid as the proton source (e.g. trifluoroacetic acid or triflic acid). The hydride and proton source cannot combine to give H, which limits the hydricity and acidity of the H and H sources, respectively. Transition metal hydride complexes can be used in place of organosilanes as the hydride source. In these cases, triflic acid is a typical proton donor. Ketones such as benzophenones, and 1,1-disubstituted olefins are typical substrates. Hydrides of tungsten, chromium, osmium, and molybdenum complexes have also been reported | https://en.wikipedia.org/wiki?curid=41356580 |
Ionic hydrogenation Tungsten dihydride complexes can hydrogenate ketones stoichiometrically with no external acids. One hydride serves as the hydride source, and the other serves as a proton source. In the case of ionic hydrogenation, a dihydride complex is regenerated by hydrogen gas following hydrogenation. Typical catalysts are tungsten or molybdenum complexes. An example of such a catalyst is CpMo(CO)(PR)(OCR')]+ where M = W or Mo. Transfer hydrogenation (TH) catalysts, e.g. Shvo catalyst, are related to catalysts used for ionic hydrogenation. TH catalysts however do not employ strong acids and both the H and H components are covalently bonded to the complex prior to transfer to the unsaturated substrates. Typically, TH catalysts are more widely employed in organic synthesis. | https://en.wikipedia.org/wiki?curid=41356580 |
Iron powder has several uses; for example production of magnetic alloys and certain types of steels. is formed as a whole from several other iron particles. The particle sizes vary anywhere from 20-200 μm. The iron properties differ depending on the production method and history of a specific iron powder. There are three types of iron powder classifications: reduced iron powder, atomized powder, and electrolyte iron powder. Each type is used in various applications depending on their properties. There is very little difference in the visual appearances of reduced iron powder and atomized iron powder. Most iron powders are used for automobile parts. is also used for the following: | https://en.wikipedia.org/wiki?curid=41359304 |
Recoil (fluid behavior) Recoil is a rheological phenomenon observed only in non-Newtonian fluids that is characterized by a moving fluid's ability to snap back to a previous position when external forces are removed. Recoil is a result of the fluid's elasticity and memory where the speed and acceleration by which the fluid moves depends on the molecular structure and the location to which it returns depends on the conformational entropy. This effect is observed in numerous non-Newtonian liquids to a small degree, but is prominent in some materials such as molten polymers. The degree to which a fluid will “remember” where it came from depends on the entropy. Viscoelastic properties in fluids cause them to snap back to entropically favorable conformations. Recoil is observed when a favorable conformation is in the fluid's recent past. However, the fluid cannot fully return to its original position due to energy losses stemming from less than perfect elasticity. Recoiling fluids display fading memory meaning the longer a fluid is elongated, the less it will recover. Recoil is related to characteristic time, an estimate of the order of magnitude of reaction for the system. Fluids that are described as recoiling generally have characteristic times on the order of a few seconds. Although recoiling fluids usually recover relatively small distances, some molten polymers can recover back to 1/10 of the total elongation. This property of polymers must be accounted for in polymer processing | https://en.wikipedia.org/wiki?curid=41359517 |
Recoil (fluid behavior) When a spinning rod is placed in a polymer solution, elastic forces generated by the rotation motion cause fluid to climb up the rod (a phenomenon known as the Weissenberg effect). If the torque being applied is immediately brought to a stop, the fluid recoils down the rod. When a viscoelastic fluid being poured from a beaker is quickly cut with a pair of scissors, the fluid recoils back into the beaker. When fluid at rest in a circular tube is subjected to a pressure drop, a parabolic flow distribution is observed that pulls the liquid down the tube. Immediately after the pressure is alleviated, the fluid recoils backward in the tube and forms a more blunt flow profile. When Silly Putty is rapidly stretched and held at an elongated position for a short period of time, it springs back. However, if it is held at an elongated position for a longer period of time, there is very little recovery and no visible recoil. | https://en.wikipedia.org/wiki?curid=41359517 |
Khalil Qureshi Khalil Ahmad Qureshi (Urdu: خليل احمد قريشى; HI, SI), is a Pakistani physical chemist and the professor of physical chemistry at the Punjab University. He has published notable papers in nuclear physical chemistry in international scientific journals as well contributing in the advancement of the scientific applications of the civilian usage of the fuel cycle. A native of Lahore, Qureshi subsequently attended the Punjab University to study chemistry where he graduated with BSc in chemistry. For his higher studies, he went to United Kingdom to attend Imperial College London. He earned MSc in Chemical Technology and worked towards gaining the DIC in physical metallurgy. At the Imperial College, he joined the doctoral group led by Thomas West and David Craig. He earned his PhD in physical chemistry under the supervision of David Craig, writing his thesis on Physico-chemical studies of the vapour deposition of AlO, in 1972. He briefly taught physical chemistry at the London University before moving to Pakistan. Upon his return, he joined the Pakistan Atomic Energy Commission (PAEC) and took the professorship of nuclear chemistry at the Pakistan Institute of Nuclear Science and Technology (PINSTECH). Subsequently, he joined the clandestine atomic bomb project's chemistry section led by fellow chemist IH Qureshi. Munir Ahmad Khan, chairman PAEC, had him to partially take over the "R-Labs" at PAEC to engage research in chemical explosives | https://en.wikipedia.org/wiki?curid=41362687 |
Khalil Qureshi Initially, the research was concentrated towards development of the HMX, a non-toxic explosive that was produced as a by-product of the RDX process. In the 1970s, he founded the Metallurgical Laboratory (Met Lab) where he also moved majority of the staff to undertake research in physical metallurgy. At the Met Lab, Qureshi led the team of physical chemists who supervised the physical conversion of UF into solid metal before coating and machining the metal. During this time, he supervised and led the research on using chemical and metallurgical industrial techniques and reduction furnaces to produce metal from the HEC which moved from KRL. Due to the sensitivity of the project and concerns of fellow theorist AQ Khan, the program was definitely moved to KRL in the 1980s. While at PAEC, Qureshi joined the chemistry department of Quaid-e-Azam University as an associate professor. In the 1990s, he joined the Punjab University to teach post-graduate course on physical chemistry. In the 2000s, he joined the Lahore University of Management Sciences's School of Science and Engineering as director of engineering and safety. Over the years, he became known for his strong scientific advocacy of peaceful usage of nuclear energy, safety, and security, following the Fukushima disaster. A member of Khwarizmi Science Society, he has lectured on safety issues regarded the nuclear power and topics in nuclear chemistry | https://en.wikipedia.org/wiki?curid=41362687 |
Khalil Qureshi He has also authored numerous articles on chemical safety and securities around the world in world's leading research journal. In 2011, he lectured on physical chemistry and spoke about how nuclear technology was being used currently and different ways of disposing nuclear waste at the Forman Christian College University in Lahore. He is the recipient of Pakistan's highest honours– the Hilal-i-Imtiaz bestowed in 2003 and the Sitara-e-Imtiaz bestowed in 1999 by the Government of Pakistan. | https://en.wikipedia.org/wiki?curid=41362687 |
EuroFlow consortium was founded in 2005 as 2U-FP6 funded project and launched in spring 2006. At first, was composed of 18 diagnostic research groups and two SMEs (small/medium enterprises) from eight different European countries with complementary knowledge and skills in the field of flow cytometry and immunophenotyping. During 2012 both SMEs left the project so it obtained full scientific independence. The goal of consortium is to innovate and standardize flow cytometry leading to global improvement and progress in diagnostics of haematological malignancies and individualisation of treatment. Since the '90s immunophenotyping (staining cells with antibodies conjugated with fluorochromes and detection with flow cytometer) became the preferred method in diagnostics of haematological malignancies. The advantages of this method are speed and simplicity, possibility to measure more than 6 parameters at a time, precise focusing on malignant population and also broad applicability in diagnostics. Because there is a great progress in development of antibodies, fluorochromes and multicolor digital flow cytometers, it became a question of how to interpret cytometric data and how to achieve comparable results between facilities. Even though a consensus of recommendations and guidelines was established, standardization was only partial because there was no regard of different antibody clones, fluorochromes and their optimal combinations or of sample preparation | https://en.wikipedia.org/wiki?curid=41363717 |
EuroFlow On that account cytometry is perceived as method highly dependent on level of expertise and with limited reproducibility in multicentric studies. These goals were set out in the journal "Leukemia" in 2012. During passed few years achieved most of its goals. Eight-color panels for diagnoses, and classification and follow-up of haematological malignancies were established. Panels, consisting of screening tube and supplementary characterisation tubes, are based on experiences and knowledge from literature but further optimised and tested in multiple research centers on large collection of samples impeaching on selection of fluorochromes and standardization of instrument settings and SOPs. Antibody clones, fluorochromes and other reagencies from different companies underwent detailed testing and comparison. Simultaneously a new software for analysing of more complex and extensive data files was developed, capable of multidimensional statistical comparison of normal data samples and patient samples. Also new antibody clones against rigorously selected epitopes of proteins involved in chromosomal translocations were developed for detection of most frequent fusion proteins in acute leukemia and chronic myeloid leukemia. Also detection of fusion proteins using immunobead assays was introduced. | https://en.wikipedia.org/wiki?curid=41363717 |
Gugiaite is a melilite mineral, named for the Chinese village of Gugia where it was first discovered. Its chemical formula is CaBeSiO It occurs mostly in skarns with melanite adjacent to an alkali syenite and has no economic value. Its crystals are small tetragonal tablets with vitreous luster and perfect cleavage. It is colorless and transparent with a density of three. The mineral belongs to space group P-421m and is strongly piezoelectric. Shortly after the discovery of gugiaite, it was noted that a new name was unnecessary as it could have been considered an end member of meliphanite, (Ca,Na)2Be(Si,Al)2(O,F)2 differing mainly in containing much less Na and F (Fleischer 1963). Recent data have confirmed that gugiaite does differ from meliphanite optically and structurally (Grice and Hawthorne 2002). is a melilite and is distinctly different from other beryllium minerals such as meliphanite and leucophanite (Grice and Hawthorne 2002). is named for its locality near the village of Gugia, China (Peng et al. 1962). Incongruent information exists regarding Gugia; consequently the actual location of this village within China is unclear (de Fourestier 2005). Gujia is most often referenced as being in either Jiangsu Province or Liaoning Province (Yang et al. 2001; Mandarino 2005). has an ideal chemical formula of Ca2BeSi2O7 and is a member of the melilite and sorosilicate (Si2O7 ) groups (Peng et al. 1962) | https://en.wikipedia.org/wiki?curid=41364692 |
Gugiaite It is chemically similar to jeffreyite (Ca,Na)2[(Be,Al)Si2(O,OH)7], meliphanite (Ca,Na)2[Be(Si,Al)2O6(O,OH,F)], and leucophanite (Ca,Na)2[Be(Si,Al)2O6(O,F)] in that they all contain essential calcium, beryllium, and silicon (Hawthorne and Huminicki 2002). Two chemical analyses gave similar results and one is as follows: SiO2 44.90, Al2O3 2.17, Fe2O3 0.11, MnO 0.07, MgO 0.38, CaO 40.09, BeO 9.49, Na2O 0.72, K2O 0.20, H2O- 0.36, H2O+ 0.90, F 0.25, Cl 0.18, P2O5 0.08, TiO2 trace, -O=(F,Cl)2 0.15, sum 99.94, 99.79% (Fleischer 1963). Common impurities are Ti, Zr, Hf, Al, Fe, Mn, Mg, Na, K, F, Cl, and P (Fleischer 1963). is usually found in skarn in contact with alkaline syenite with melanite, orthoclase, aegirine, titanite, apatite, vesuvianite, and prehnite (Peng et al. 1962). It occurs as thin square tablets, to 3 mm, in small cavities in skarn and enclosed in melanite (Peng et al. 1962). Skarns are often formed at the contact zone between granite intrusions and carbonate sedimentary rocks through metasomatism. has also been found in a miarolitic cavity in granite (Grew 2002). This type of cavity is crystal lined, irregular, and known for being a source of rare minerals, such as beryllium, that are not normally found in abundance in igneous rocks (https://web.archive.org/web/20091028021704/http://geocities.com/oklahomamgs/London/Pegmatite2.html) | https://en.wikipedia.org/wiki?curid=41364692 |
Gugiaite While initially found in Gugia, China, its localities have expanded to include Piedmont, Italy, Ehime Prefecture, Japan, Eastern Siberian Region, Russia, and most recently Telemark, Norway (http://www.mindat.org/min-1769.html). is composed of infinite sheets of tetrahedra with Be-Si-Si linkages and interstitial Ca (Hawthorne and Huminicki 2002). As shown in Figure 1, the oxygen atom bonds to a [4]-coordinated high-valence cation, Si, to produce a discontinuous polymerization of tetrahedra linked by interstitial Ca (Hawthorne and Huminicki 2002). It is isostructural with akermanite (Ca2MgSi2O7) with Be occupying the Mg site of akerminite (Hawthorne and Huminicki 2002). X-ray studies by the Weissenberg method show to be tetragonal, space group P-421m, space group number 113, and H-M Symbol -42m (Peng et al. 1962). Cell dimensions are: a=b=7.48(2) Ȧ, c=5.044(3) Ȧ, V=277.35 Ȧ, α=β=γ=90◦, and Z=2 (Peng et al. 1962). The axial ratio is a:c=1:0.67617 (Peng et al. 1962). Structurally A is Ca2, T1 is Be(54), T2 is Si2(53), and X is O7 (Yang et al. 2001). The three strongest lines of the X-ray powder data for gugiaite are: 2.765(10), 1.485(7), and 1.709(7) (Peng et al. 1962). The crystal form of occurs as thin tetragonal tablets mostly 2-3 mm across and 0.3-0.5 mm thick, shown in Figure 2 below (Fleischer 1963). The cleavages are {010} perfect, {001} distinct, and {110} poor (Peng et al. 1962). It is transparent, optically uniaxial (+), and strongly piezoelectric (Peng et al. 1962) | https://en.wikipedia.org/wiki?curid=41364692 |
Gugiaite See Table for additional physical properties. does not appear to have any political significance or economic value. From a historical perspective, gugiaite is noted as being the first beryllium mineral found in skarn systems at contacts between alkaline rocks and limestones (Peng et al. 1962). Also, thermodynamic equilibrium studies involving gugiaite have been conducted to determine the distribution of beryllium between gaseous and solid phases as a function of temperature in attempts to deduce the processes that formed the solar system (Lodders and Lauretta 1997). | https://en.wikipedia.org/wiki?curid=41364692 |
Iqbal Hussain Qureshi (Urdu:اقبال حسين قریشی; 27 September 1937 – 8 December 2012; SI, FPAS), best known as I.H. Qureshi, was a Pakistani nuclear chemist and professor of chemistry at the Institute of and Applied Sciences in Islamabad. Qureshi was the principle contributor of scientific understanding of various elements: rubidium, potassium, bromide, chlorine, and the Debye model. Early his career, he made notable contribution in advancing of the field of nuclear medicine in Pakistan. In addition, he also advised the government on nuclear policy issues and pushed his influential role in Nuclear Regulatory Authority (PNRA) and the peaceful applications of nuclear science. He spent many years as an educator and research scientist at the Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad. was born in Ajmer, Rajasthan, British Indian Empire on 27 September 1937. After the independence of Pakistan in 1947, his family moved to Hyderabad, Sindh, where he matriculated from a public high school. He was a child prodigy, having accepted at the Sindh University in his teenage years to study chemistry. He received BSc in Chemistry from Sindh University in 1956. He graduated at the top of his class, winning the Silver Medal with his degree. In 1958, he gained MSc in chemistry from the same institution, and won the scholarship to pursue higher education in chemistry abroad. He went to United States to attend the University of Michigan where he earned MSc in nuclear chemistry in 1962 | https://en.wikipedia.org/wiki?curid=41369887 |
Iqbal Hussain Qureshi Qureshi continued his research on nuclear chemistry and took the PhD in nuclear chemistry from the University of Tokyo, with a doctoral thesis on the "Radiochemical separations by Amalgam exchange" which contained fundamental work on chemical amalgam, in 1963. In 1967, he availed a post doctoral position at US's National Bureau of Standards and during 1969 he obtained a specialised training in the area of uranium and plutonium separation from Denmark. He married twice in his life; his first wife died in mid 1980s and afterwards he got remarried. He was not only a scientist in its true meaning but also a man of exemplary character and showed immense kindness towards his colleagues and fellow workers. In 1960, Qureshi joined the Pakistan Atomic Energy Commission (PAEC) and posted at the chemistry division working under nuclear physicist, dr. Naeem Ahmad Khan. However, he was separated from the division when he independently established the radiochemistry division there. In 1967, he took up the professorship at the Pakistan Institute of Engineering and Applied Sciences where he pioneered the research in nuclear chemistry. In 1972, he was reached by Naeem Ahmad Khan and joined the chemistry division at the Pakistan Institute of Nuclear Science and Technology (PINSTECH). He began working of equation of state on plutonium device as early as 1972 | https://en.wikipedia.org/wiki?curid=41369887 |
Iqbal Hussain Qureshi He developed and established the computerised radiation detection chemical analysis laboratories at PINSTECH in 1973, which became an instrumental in detecting the tested radioactive emissions of India's first nuclear bomb test at Rajasthan, in 1974. Notably, he balanced the crucial chemical equation required for the chemical reactions in the fission devices. By 1977, he famously discovered the technique in order for balancing the Q-value and energy balance in a fission device. At PINSTECH, he was Head of the nuclear chemistry division (NCD) which was responsible for the multi-stage chemical process that separated, concentrated and isolated plutonium from uranium. At NCD he also played a supervisory role in developing Analytical Chemistry Group comprising modern and state of the art analytical chemistry labs such as Atomic Absorption Spectroscopy lab, Emission Spectrography lab, Chromatography lab, Electrochemical Analysis lab and radio-isotope production labs etc. In 1983, he successfully oversaw the PARR-III reactor went into criticality. He engage his research in copper-nickel alloys after introducing the lattice dynamical method to evaluate the Cu/Ni alloys. Key and fundamental research on understanding the neutron flux were carried out by Qureshi, in which, he managed to secure the patents from the IAEA. After the conclusion of the clandestine atomic bomb projects, he was appointed chief technical officer at the PAEC in 1991; though he was more eager to return to academia | https://en.wikipedia.org/wiki?curid=41369887 |
Iqbal Hussain Qureshi Throughout his time at the PAEC, he had earned several scientific honours, including the Gold Medal and fellowship of the Pakistan Academy of Sciences in 1994. He was the recipient of the prestigious Sitara-i-Imtiaz by the Government of Pakistan in 1992. In 1997, he was awarded the notable Khwarizmi Award on advancing and understanding the "Nuclear analytical techniques development and application in Pakistan". In 1996, he retired from PAEC as Chief Scientific Officer and was made scientist emeritus, which allowed him to continue research at PINSTECH before moving to Karachi. He took up the professorship of chemistry at the Karachi University and headed the nuclear chemistry section at the H.E.J. Research Institute of Chemistry. During this time, he authored several articles and published books on nuclear chemistry. He retained his position till 2001 when he joined the Pakistan Nuclear Regulatory Authority. At PNRA, he served as the chief scientific officer and adviser to the government on nuclear policy issues. His contribution and policy efforts led to the physical security of the commercial nuclear power infrastructure in the country and helped launched the nuclear awareness campaign following the Fukushima nuclear disaster in 2011. He served until 2009 when he decided to accept the professorship of chemistry at the Institute of and Applied Sciences. In 2012, he died with a sudden problem of breathing, and buried in Karachi, Sindh | https://en.wikipedia.org/wiki?curid=41369887 |
Iqbal Hussain Qureshi As a scientist, he was remembered and noted as "a very highly skilled and duty conscientious scientist throughout." He was a versatile scholar who played classical Sitar on multiple public occasions. | https://en.wikipedia.org/wiki?curid=41369887 |
Daily light integral (DLI) describes the number of photosynthetically active photons (individual particles of light in the 400-700 nm range) that are delivered to a specific area over a 24-hour period. This variable is particularly useful to describe the light environment of plants. The daily light integral (DLI) is the number of photosynthetically active photons (photons in the PAR range) accumulated in a square meter over the course of a day. It is a function of photosynthetic light intensity and duration (day length) and is usually expressed as moles of light (mol photons) per square meter (m) per day (d), or: mol·m·d. DLI is usually calculated by measuring the photosynthetic photon flux density (PPFD) in μmol·m·s (number of photons in the PAR range received in a square meter per second) as it changes throughout the day, and then using that to calculate total estimated number of photons in the PAR range received over a 24-hour period for a specific area. In other words, DLI describes the sum of the per second PPFD measurements during a 24-hour period. If the photosynthetic light intensity stays the same for the entire 24-hour period, DLI in mol m d can be estimated from the instantaneous PPFD from the following equation: μmol m s multiplied by 86,400 (number of seconds in a day) and divided by 10 (number of μmol in a mol). Thus, 1 μmol m s = 0.0864 mol m d if light intensity stays the same for the entire 24 hour period. In the past, biologists have used lux or energy meters to quantify light intensity | https://en.wikipedia.org/wiki?curid=41379697 |
Daily light integral They switched to using PPFD when it was realized that the flux of photons in the 400-700 m range is the important factor in driving the photosynthetic process. However, PPFD is usually expressed as the photon flux per second. This is a convenient time scale when measuring short-term changes in photosynthesis in gas exchange systems, but falls short when the light climate for plant growth has to be characterized. First because it does not take into account the length of the day light period, but foremost because light intensity in the field or in glasshouses changes so much diurnally and from day to day. Scientists have tried to solve this by reporting light intensity measured for one or more sunny days at noon, but this is grasping the light level for only a very short period of the day. includes both the diurnal variation and day length, and can also be reported as a mean value per month or over an entire experiment. It has been shown to be better related to plant growth and morphology than PPFD at any moment or day length alone. Some energy meters are able to capture PPFD during an interval period suc as 24-hours. Outdoors, DLI values vary depending on latitude, time of year, and cloud cover. Occasionally, values over 70 mol·m·d can be reached at bright summer days at some locations. Monthly-averaged DLI values range between 20-40 in the tropics, 15-60 at 30° latitude and 1-40 at 60° latitude | https://en.wikipedia.org/wiki?curid=41379697 |
Daily light integral For plants growing in the shade of taller plants, such as on the forest floor, DLI may be less than 1 mol·m·d, even in summer. In greenhouses, 30-70% of the outside light will be absorbed or reflected by the glass and other greenhouse structures. DLI levels in greenhouses therefore rarely exceed 30 mol·m·d. In growth chambers, values between 10 and 30 mol·m·d are most common. DLI affects many plant traits. Although not all plants respond in the same way, some general trends are found: High light increases leaf thickness, either because of an increase in the number of cell layers within the leaf, and/or because of an increase in the cells within a cell layer. The density of a leaf increases a well, and so does the leaf dry mass per area (LMA). There are also more stomata per mm2. Taken over all species and experiments, high light does not affect the organic nitrogen concentration, but decreases the concentration of chlorophyll and minerals. It increases the concentration of starch and sugars, soluble phenolics, and also the xanthophyll/chlorophyll ratio and the chlorophyll a/b ratio. While the chlorophyll concentration decreases, leaves have more leaf mass per unit leaf area, and as a result the chlorophyll content per unit leaf area is relatively unaffected. This is also true for the light absorptance of a leaf. Leaf light reflectance goes up and leaf light transmittance goes down. Per unit leaf area there is more RuBisCO and a higher photosynthetic rate under light-saturated conditions | https://en.wikipedia.org/wiki?curid=41379697 |
Daily light integral Expressed per unit leaf dry mass, however, photosynthetic capacity decreases. Plants at high light invest less of their biomass in leaves and stems, and more in roots. They grow faster, per unit leaf area (ULR) and per unit total plant mass (RGR), and therefore high-light grown plants generally have more biomass. They have shorter internodes, with more stem biomass per unit stem length, but plant height is often not strongly affected. High-light plants do show more branches or tillers. High-light grown plants generally have somewhat larger seeds, but produce many more flowers, and therefore there is a large increase in seed production per plant. Sturdy plants with short internodes and many flowers are important for horticulture, and hence a minimum amount of DLI is required for marketable horticultural plants. Measuring DLI over a growing season and comparing it to results can help determine which varieties of plants will thrive in a specific location. | https://en.wikipedia.org/wiki?curid=41379697 |
Rui L. Reis Rui Luís Reis is a Portuguese scientist known for his research in tissue engineering, regenerative medicine, biomaterials, biomimetics, stem cells, and biodegradable polymers. Reis is Professor of tissue engineering, regenerative medicine and stem cells at the Department of Polymer Engineering, School of Engineering of the University of Minho, in Braga and Guimarães. He is the Director of the 3B's Research Group, part of the Research Institute on Biomaterials, Biodegradables and Biomimetics (I3Bs) of UMinho (www.i3bs.uminho.pt), which specializes in the areas of regenerative Medicine, tissue engineering, stem cells and biomaterials. He is also the Director of the ICVS/3B's Associate Laboratory of UMinho. He is also the CEO of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine. is also, since 2013, the Vice-Rector (Vice-President) for research and innovation of UMinho. Since 2007 he is also editor-in-chief of the "Journal of Tissue Engineering and Regenerative Medicine". He is since 2016 and until 2018 the Global (World) President of the Tissue Engineering and Regenerative Medicine International Society (TERMIS) | https://en.wikipedia.org/wiki?curid=41392177 |
Rui L. Reis He is the responsible and PI of the EU funded project for the creation of the new center of Excellence, with headquarters in AvePark in Caldas das Taipas - Guimarães, the Discoveries Center for Regenerative and Precision Medicine in a Teaming process between University of Minho, University College London, University of Porto, University of Aveiro, University of Lisbon, University NOVA Lisbon. Reis was born and has always lived in Porto, being one of three children of a chemical engineering professor and a domestic. Reis spent a small part of his childhood in Metangula, Mozambique, a small town near Lake Niassa, while his father was engaged in military service during the Portuguese Colonial War. He is married with Olga Paiva and has one son, Bernardo Reis (born in 2001). He is a strong supporter of FC Porto. Reis began his research into biomaterials in 1990. He studies the development of biomaterials from natural origin polymers and their possible biomedical applications, including bone replacement and fixation, drug delivery carriers, partially degradable bone cements and tissue engineering scaffolding. His team works under his leadership in the tissue engineering of many different tissues, namely: bone, cartilage, osteochondral, skin, tendon and ligaments, meniscus, intervertebral disks, as well as on peripheral and central nervous systems regeneration, diabetes treatment and cancer 3D disease models. In 2015 Reis' research team developed a new type of catheter which is made of hydrogel | https://en.wikipedia.org/wiki?curid=41392177 |
Rui L. Reis In 2014 he was made a Commander of Portugal's Order of Saint James of the Sword and in 2016, Reis was elected a foreign member of the United States National Academy of Engineering. He has won many other awards, including the Jean Leray (in 2002) and the George Winter award (in 2011) the two major awards of the European Society for Biomaterials. was also awarded the Clemson Award for Contributions to the Literature by the Society for Biomaterials (USA, in 2014) and the Contributions to the Literature Award by the European Chapter of TERMIS (TERMIS-EU in 2017). He has an Honouris Causa by the University of Granada, Spain, in 2010. | https://en.wikipedia.org/wiki?curid=41392177 |
Frank–Kasper phases Topologically close pack (TCP) phases, also known as Frank-Kasper (FK) phases, are one of the largest groups of intermetallic compounds, known for their complex crystallographic structure and physical properties. Owing to their combination of periodic and aperiodic structure, some TCP phases belong to the class of quasicrystals. Applications of TCP phases as high-temperature structural and superconducting materials have been highlighted; however, they have not yet been sufficiently investigated for details of their physical properties. Also, their complex and often non-stoichiometric structure makes them good subjects for theoretical calculations. In 1958, Frank and Kasper, in their original work investigating many complex alloy structures, showed that non-icosahedral environments form an open-end network which they called the major skeleton, and is now identified as the declination locus. They came up with the methodology to pack asymmetric icosahedra into crystals using other polyhedra with larger coordination number and atoms. These coordination polyhedra were constructed to maintain topological close packing (TCP). Based on the tetrahedral units, FK crystallographic structures are classified into low and high polyhedral groups denoted by their coordination numbers (CN) referring to the number of atom centering the polyhedron. Some atoms have an icosahedral structure with low coordination, labeled CN12. Some others have higher coordination numbers of 14, 15 and 16, labeled CN14, CN15 and CN16, respectively | https://en.wikipedia.org/wiki?curid=41396440 |
Frank–Kasper phases These atoms with higher coordination numbers form uninterrupted networks connected along the directions where the five-fold icosahedral symmetry is replaced by six-fold local symmetry. The most common members of a FK-phases family are: A15, Laves phases, σ, μ, M, P, and R. A15 phases are intermetallic alloys with an average coordination number (ACN) of 13.5 and eight AB stoichiometry atoms per unit cell where two B atoms are surrounded by CN12 polyhedral (icosahedra), and six A atoms are surrounded by CN14 polyhedral. NbGe is a superconductor with A15 structure. Laves phases are intermetallic compounds composed of CN12 and CN16 polyhedra with AB stoichiometry, commonly seen in binary metal systems like MgZn. Due to the small solubility of AB structures, Laves phases are almost line compounds, though sometimes they can have a wide homogeneity region. The sigma (σ) phase is an intermetallic compound known as the one without definite stoichiometric composition and formed at the electron/atom ratio range of 6.2 to 7. It has a primitive tetragonal unit cell with 30 atoms. CrFe is a typical alloy crystallizing in the σ phase at the equiatomic composition. With physical properties adjustable based on its structural components, or its chemical composition provided a given structure. The μ phase has an ideal AB stoichiometry, with its prototype WFe, containing rhombohedral cell with 13 atoms. While many other Frank-Kasper alloy types have been identified, more continue to be found | https://en.wikipedia.org/wiki?curid=41396440 |
Frank–Kasper phases The alloy NbNiAl is the prototype for the M phase. It has orthorhombic space group with 52 atoms per unit cell. The alloy CrMoNi is the prototype for the P-phase. It has a primitive orthorhombic cell with 56 atoms. The alloy CoCrMo is the prototype for the R-phase which belongs to the rhombohedral space group with 53 atoms per cell. FK phase materials have been pointed out for their high-temperature structure and as superconducting materials. Their complex and often non-stoichiometric structure makes them good subjects for theoretical calculations. A15, Laves and σ are the most applicable FK structures with interesting fundamental properties. The A15 compounds are forming important intermetallic superconductor with major applications in materials used in wires for superconducting such as: NbSn, NbZr and NbTi. A majority of superconducting magnets are constructed out of NbTi alloy. Small extents of σ phase considerably decreases the flexibility and impairment in erosion resistance. While addition of refractory elements like W, Mo or Re to FK phases helps to enhance the thermal properties in such alloys as steels or nickel-based superalloys, it increases the risk of unwanted precipitation in intermetallic compounds. | https://en.wikipedia.org/wiki?curid=41396440 |
AMSilk is an industrial supplier of synthetic silk biopolymers. The polymers are biocompatible and breathable. The company was founded in 2008 and has its headquarters at the IZB in Planegg near Munich. is an industrial biotechnology company with a proprietary production process for their silk materials. produces a lightweight material trademarked as Biosteel, created from recombinant spider silk, which was used by Adidas to create a biodegradable running shoe. Jens Klein, CEO of AMSilk, said during an interview that the biodegradable material can help reduce the amount of waste that has to be burned or pollutes the environment. is also developing breast implants made of biodegradable spider silk in collaboration with the German company Polytech. | https://en.wikipedia.org/wiki?curid=41401861 |
Magnesium monoperoxyphthalate (MMPP) is a water-soluble peroxy acid used as an oxidant in organic synthesis. Its main areas of use are the conversion of ketones to esters (Baeyer-Villiger oxidation), epoxidation of alkenes (Prilezhaev reaction), oxidation of sulfides to sulfoxides and sulfones, oxidation of amines to produce amine oxides, and in the oxidative cleavage of hydrazones. Due to its insolubility in nonpolar solvents MMPP has seen less use than the more widely used "meta"-chloroperoxybenzoic acid ("m"CPBA). Although work up procedures are more simply handled in polar solvents, usage of MMPP to oxidize nonpolar substrates in biphasic media combined with a phase transfer catalyst have been inefficient. Despite this MMPP has certain advantages over "m"CPBA including a lower cost of production and increased stability. MMPP is also used as the active ingredient in certain surface disinfectants such as Dismozon Pur. As a surface disinfectant MMPP exhibits a broad spectrum biocidal effect including inactivation of endospores. Its wide surface compatibility enables its use on sensitive materials, such as plastic and rubber equipment used in hospitals. Additionally MMPP has been investigated as a potential antibacterial agent for mouthwashes and toothpaste. | https://en.wikipedia.org/wiki?curid=41404633 |
Antoine de Saporta (26 July 1855 – 14 April 1914) was a French aristocrat and non-fiction writer. was born on July 26, 1855 in Aix-en-Provence. He was a member of the Provençal nobility. His father, Gaston de Saporta (1823-1895), was a renowned botanist. He grew up in the Hôtel Boyer de Fonscolombe, a listed hôtel particulier at 21 Rue Gaston de Saporta in Aix-en-Provence. He wrote several books, mostly about wine. He also wrote many articles for "La Nature", "La Revue scientifique" and "Revue des deux Mondes". He died on April 14, 1914 in Montpellier. | https://en.wikipedia.org/wiki?curid=41414331 |
C6H6O2S The molecular formula CHOS may refer to: | https://en.wikipedia.org/wiki?curid=41416017 |
Beta attenuation monitoring (BAM) is a widely used air monitoring technique employing the absorption of beta radiation by solid particles extracted from air flow. This technique allows for the detection of PM and PM, which are monitored by most air pollution regulatory agencies. The main principle is based on a kind of Bouguer (Lambert–Beer) law: the amount by which the flow of beta radiation (electrons) is attenuated by a solid matter is exponentially dependent on its mass and not on any other feature (such as density, chemical composition or some optical or electrical properties) of this matter. So, the air is drawn from outside of the detector through an "infinite" (cycling) ribbon made from some filtering material so that the particles are collected on it. There are two sources of beta radiation placed one before and one after the region where air flow passes through the ribbon leaving particles on it; and there are also two detectors on the opposite side of the ribbon, facing the detectors. The sources' intensity and detectors' sensitivity being the same (or corrected with appropriate calibration lookup table), the intensity of beta rays detected by one of detectors is compared to that of the other. Thus one can deduce how much mass has the ribbon acquired upon being exposed to air flow; knowing the drain velocity, actual particle mass concentration in air could be assessed. The radiation source can be a gas chamber, filled with Kr gas, or a pieces of C-rich polymer plastic, such as PMMA. Detector is simply a Geiger–Mueller counter | https://en.wikipedia.org/wiki?curid=41420172 |
Beta attenuation monitoring The particulate matter content measured is affected by the moisture content in the air, unfortunately. To discriminate between particle of different sizes (e. g., between PM and PM), some preliminary separation could be accomplished, for example, by cyclone battery. A similar method exists, where instead of beta particle flow an X-ray Fluorescence Spectroscopic monitoring is applied on the either side of air flow contact with the ribbon. This allows to obtain not only cumulative measurement of particle mass, but also to detect their average chemical composition (technique works for potassium and elements heavier than it). | https://en.wikipedia.org/wiki?curid=41420172 |
Benzoxazinone biosynthesis The biosynthesis of benzoxazinone, a cyclic hydroxamate and a natural insecticide, has been well-characterized in maize and related grass species. In maize, genes in the pathway are named using the symbol "bx". Maize Bx-genes are tightly linked, a feature that has been considered uncommon for plant genes of a biosynthetic pathways. Especially notable are genes encoding the different enzymatic functions BX1, BX2 and BX8 and which are found within about 50 kilobases. Results from wheat and rye indicate that the cluster is an ancient feature. In wheat the cluster is split into two parts. The wheat genes Bx1 and Bx2 are located in close proximity on chromosome 4 and wheat Bx3, Bx4 and Bx5 map to the short arm of chromosome 5; an additional Bx3 copy was detected on the long arm of chromosome 5B. Recently, additional biosynthetic clusters have been detected in other plants for other biosynthetic pathways and this organization might be common in plants. The bx1 gene encodes a protein, BX1, that forms indol from indol-3-glycerol phosphate in the plastid. It is the first step in the pathway and determines much of the natural variation in levels of DIMBOA in maize. The next steps in the pathway occur in the endoplasmic reticulum, also referred to as the microsomes in cell fractionation experiments, and are carried by proteins encoded by genes bx2, bx3, bx4, and bx5. | https://en.wikipedia.org/wiki?curid=41442860 |
Bx1 benzoxazin1 Function Maize gene for first step in biosynthesis of benzoxazin, which aids in resistance to insect pests, pathogenic fungi and bacteria. First report Hamilton 1964, as a mutant sensitive to the herbicide atrazine, and lacking benzoxazinoids (less than 1% of non-mutant plants). Molecular characterization reveals that the BX1 protein is a homologue to the alpha-subunit of tryptophan synthase. The reference mutant allele has a deletion of about 900 bp, located at the 5'-terminus and comprising sequence upstream of the transcription start site and the first exon. Additional alleles are given by a "Mu" transposon insertion in the fourth exon (Frey et al. 1997 ) and a "Ds" transposon insertion in the maize inbred line W22 genetic background (Betsiashvili et al. 2014). Gene sequence diversity analysis has been performed for 281 inbred lines of maize, and the results suggest that bx1 is responsible for much of the natural variation in DIMBOA (a benzoxazinoid compound) synthesis (Butron et al. 2010). Genetic variation in benzoxazinoid content influences maize resistance to several insect pests (Meihls et al 2013; McMullen et al 2009). AB chromosome translocation analyses place on short arm of chromosome 4 (4S; Simcox and Weber 1985 ). There is close linkage to other genes in the benzoxazinoid synthesis pathway ["bx2, bx3, bx4, bx5" Frey et al. 1995, 1997 ). Gene "bx1" is 2490 bp from "bx2" (Frey et al. 1997 ); between "umc123" and "agrc94" on 4S (Melanson et al. 1997 ). Mapping probes: SSR p-umc1022 (Sharopova et al | https://en.wikipedia.org/wiki?curid=41443123 |
Bx1 benzoxazin1 2002 ); Overgo (physical map probe) PCO06449 (Gardiner et al. 2004 ). Mutants are viable, but may be distinguished from normal plants by FeCl3 staining: plants able to synthesize benzoxinoids have pale blue color when crushed and treated with FeCl3 solutions (Hamilton 1964, Simcox 1993 ). Mutations in the "bx1" gene reduce the resistance to first generation European corn borer ("Ostrinia nubilalis") that is conferred by benzoxazinoids (Klun et al 1970 ). "Bx1" mutant maize deposited less callose in response to chitosan elicitation than isogenic wildtype plants (Ahmad et al. 2011 ). Genetic mapping using recombinant inbred lines derived from maize inbred lines B73 and Mo17 showed that a 3.9 kb cis-regulatory element that is located approximately 140 kb upstream of "Bx1" causes higher 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) accumulation in Mo17 than in B73 seedlings (Zheng et al. 2015 ). This genetic variation is also associated with higher corn leaf aphid ("Rhopalosiphum maidis") reproduction on B73 compared to Mo17 maize seedlings (Betsiashvili et al. 2014 ). Relative to maize inbred line W22", Bx1::Ds" mutant maize plants are more sensitive to corn leaf aphids ("Rhopalosiphum maidis") (Betsiashvili et al. 2014) and beet armyworms ("Spodoptera exigua") (Tzin et al. 2017 ). Highly localized induction of benzoxazinoid accumulation in response to Egyptian cotton leafworm ("Spodoptera littoralis") feeding is abolished in a maize "bx1" mutant (Maag et al. 2016 ) | https://en.wikipedia.org/wiki?curid=41443123 |
Bx1 benzoxazin1 Catalyzes the first step in the synthesis of DIMBOA, forming indole from indole-3-glycerol phosphate. The enzyme is called indole-3-glycerol phosphate lyase, chloroplast, EC 4.1.2.8 and is located in the chloroplast. The X-ray structure of BX1 protein has been resolved and compared with bacterial TSA (tryptophan synthase alpha subunit, Kulik et al. 2005). Three homologs of the BX1 protein occur in maize. One is encoded by the gene "tsa1", "tryptophan synthase alpha1"(Frey et al. 1997, Melanson et al. 1997 ), on chromosome 7, another by "igl1", "indole-3-glycerol phosphate lyase1"(Frey et al. 1997, on chromosome 1, and another by "tsah1", 'TSA like" and located near the "bx1" gene (Frey et al. 1997. ). | https://en.wikipedia.org/wiki?curid=41443123 |
Poly(ethylene adipate) or PEA is an aliphatic polyester. It is most commonly synthesized from a polycondensation reaction between ethylene glycol and adipic acid. PEA has been studied as it is biodegradable through a variety of mechanisms and also fairly inexpensive compared to other polymers. Its lower molecular weight compared to many polymers aids in its biodegradability. can be synthesized through a variety of methods. First, it could be formed from the polycondensation of dimethyl adipate and ethylene glycol mixed in equal amounts and subjected to increasing temperatures (100 °C, then 150 °C, and finally 180 °C) under nitrogen atmosphere. Methanol is released as a byproduct of this polycondensation reaction and must be distilled off. Second, a melt condensation of ethylene glycol and adipic acid could be carried out at 190-200 °C under nitrogen atmosphere. Lastly, a two-step reaction between adipic acid and ethylene glycol can be carried out. A polyesterification reaction is carried out first followed by polycondensation in the presence of a catalyst. Both of these steps are carried out at 190 °C or above. Many different catalysts can be used such as stannous chloride and tetraisopropyl orthotitanate. Generally, the PEA is then dissolved in a small amount of chloroform followed by precipitation out in methanol. An alternate and less frequently used method of synthesizing PEA is ring-opening polymerization. Cyclic oligo(ethylene adipate) can be mixed with di-"n"-butyltin in chloroform | https://en.wikipedia.org/wiki?curid=41443677 |
Poly(ethylene adipate) This requires temperatures similar to melt condensation. PEA has a density of 1.183g/mL at 25 °C and it is soluble in benzene and tetrahydrofuran. PEA has a glass transition temperature of -50 °C. PEA can come in a high molecular weight or low molecular weight variety, i.e.10,000 or 1,000 Da. Further properties can be broken down into the following categories. In general, most aliphatic polyesters have poor mechanical properties and PEA is no exception. Little research has been done on the mechanical properties of pure PEA but one study found PEA to have a tensile modulus of 312.8 MPa, a tensile strength of 13.2 MPa, and an elongation at break of 362.1%. Alternate values that have been found are a tensile strength of ~10 MPa and a tensile modulus of ~240 MPa. IR spectra for PEA show two peaks at 1715–1750 cm, another at 1175–1250 cm, and a last notable peak at 2950 cm. These peaks can be easily determined to be from ester groups, COOC bonds, and CH bonds respectively. PEA has been shown to be able to form both ring-banded and Maltese-cross (or ring-less) type spherulites. Ring-banded spherulites most notably form when crystallization is carried out between 27 °C and 34 °C whereas Maltese-cross spherulites form outside of those temperatures. Regardless of the manner of banding, PEA polymer chains pack into a monoclinic crystal structure (some polymers may pack into multiple crystal structures but PEA does not). The length of the crystal edges are given as follows: a = 0.547 nm, b = 0.724 nm, and c = 1.55 nm | https://en.wikipedia.org/wiki?curid=41443677 |
Poly(ethylene adipate) The monoclinic angle, α, is equal to 113.5°. The bands formed by PEA have been said to resemble corrugation, much like a butterfly wing or Pollia fruit skin. Conductivity of films made of PEA mixed with salts was found to exceed that of PEOLiCFSO and of poly(ethylene succinate)/LiBF suggesting it could be a practical candidate for use in lithium ion batteries. Notably, PEA is used as a plasticizer and therefore amorphous flows occur at fairly low temperatures rendering it less plausible for use in electrical applications. Blends of PEA with polymers such as poly(vinyl acetate) showed improved mechanical properties at elevated temperatures. PEA is miscible with a number of polymers including: poly(L-lactide) (PLLA), poly(butylene adipate) (PBA), poly(ethylene oxide), tannic acid (TA), and poly(butylene succinate) (PBS). PEA is not miscible with low density polyethylene (LDPE). Miscibility is determined by the presence of only a single glass transition temperature being present in a polymer mixture. Aliphatic copolyesters are well known for their biodegradability by lipases and esterases as well as some strains of bacteria. PEA in particular is well degraded by hog liver esterase, "Rh. delemar, Rh. arrhizus", "P. cepacia," "R. oryzae," and "Aspergillus" sp".""" An important property in the speed of degradation is the crystallinity of the polymer. Neat PEA has been shown to have a slightly lower degradation rate than copolymers due to a loss in crystallinity | https://en.wikipedia.org/wiki?curid=41443677 |
Poly(ethylene adipate) PEA/poly(ethylene furanoate) (PEF) copolymers at high PEA concentrations were shown to degrade within 30 days while neat PEA had not fully degraded, however, mixtures approaching 50/50 mol% hardly degrade at all in the presence of lipases. Copolymerizing styrene glycol with adipic acid and ethylene glycol can result in phenyl side chains being added to PEA. Adding phenyl side chains increases steric hindrance causing a decrease in the crystallinity in the PEA resulting in an increase in biodegradability but also a notable loss in mechanical properties. Further work has shown that decreasing crystallinity is more important to degradation carried out in water than whether or not a polymer is hydrophobic or hydrophillic. PEA polymerized with 1,2-butanediol or 1,2-decanediol had an increased biodegradability rate over PBS copolymerized with the same side branches. Again, this was attributed to a greater loss in crystallinity as PEA was more affected by steric hindrance, even though it is more hydrophobic than PBS. urethane combined with small amounts of ligin can aid in preventing degradation by acting as an antioxidant. Additionally, the mechanical properties of the PEA urethane increased by ligin addition. This is thought to be due to the rigid nature of ligin which aids in reinforcing soft polymers such as PEA urethane. When PEA degrades, it has been shown that cyclic oligomers are the highest fraction of formed byproducts | https://en.wikipedia.org/wiki?curid=41443677 |
Poly(ethylene adipate) Using toluene as a solvent, the efficacy of degrading PEA through ultrasonic sound waves was examined. Degradation of a polymer chain occurs due to cavitation of the liquid leading to scission of chemical chains. In the case of PEA, degradation was not observed due to ultrasonic sound waves. This was determined to be likely due to PEA not having a high enough molar mass to warrant degradation via these means. A low molecular weight has been indicated as being necessary for the biodegradation of polymers. can effectively be used as a plasticizer reducing the brittleness of other polymers. Adding PEA to PLLA was shown to reduce the brittleness of PLLA significantly more than poly(butylene adipate) (PBA), poly(hexamethylene adipate) (PHA), and poly(diethylene adipate) (PDEA) but reduced the mechanical strength. The elongation at break was increased approximately 65x over neat PLLA. The thermal stability of PLLA also showed a significant increase with an increasing concentration of PEA. PEA has also been shown to increase the plasticity and flexibility of the terpolymer maleic anhydride-styrene-methyl metacrylate (MAStMMA). Observing the changes in thermal expansion coefficient allowed for the increasing in plasticity to be determined for this copolymer blend. Self-healing polymers is an effective method of healing microcracks caused by an accumulation of stress. Diels-Alder (DA) bonds can be incorporated into a polymer allowing microcracks to occur preferentially along these weaker bonds | https://en.wikipedia.org/wiki?curid=41443677 |
Poly(ethylene adipate) Furyl-telechelic poly(ethylene adipate) (PEAF) and tris-maleimide (M) can be combined through a DA reaction in order to bring about self-healing capabilities in PEAF. PEAFM was found to have some healing capabilities after 5 days at 60 °C, although significant evidence of the original cut appeared and the original mechanical properties were not fully restored. PEA microbeads intended for drug delivery can be made through water/oil/water double emulsion methods. By blending PEA with Poly-ε-caprolactone, beads can be given membrane porosity. Microbeads were placed into a variety of solutions including a synthetic stomach acid, pancreatin, Hank's buffer, and newborn calf serum. The degradation of the microcapsules and therefore the release of the drug was the greatest in newborn calf serum, followed by pancreatin, then synthetic stomach acid, and lastly Hank's buffer. The enhanced degradation in newborn calf serum and pancreatin was attributed to the presence of enzyme activity and that simple ester hydrolysis was able to be carried out. Additionally, an increase in pH is correlated with higher degradation rates. | https://en.wikipedia.org/wiki?curid=41443677 |
Poly(hexamethylene carbonate) (PHC) is an organic polymer. It can be biodegredated to form adipic acid and di(6-hydroxyhexyl) carbonate by "Roseateles depolymerans" 61A. PHC can be synthesized to terminate in primarily hydroxyl groups or methyl carbonate groups depending on the concentrations of monomers during synthesis. PHC with the hydroxyl end groups has less thermal stability than PHC with methyl carbonate end groups. The hydroxyl group allow for an unzipping reaction to take place in which the polymer chain bends back on itself and the hydroxyl group reacts with an acetyl mid chain, resulting in a shorter chain and a looped molecule. This type of degradation quickly shorten the length of the PHC. | https://en.wikipedia.org/wiki?curid=41445839 |
Nylon 4 or polybutyrolactam can be degraded by the (ND-10 and ND-11) strands of Pseudomonas sp. found in sludge. This produces γ-aminobutyric acid (GABA) as a byproduct. is thermally unstable. | https://en.wikipedia.org/wiki?curid=41445899 |
Solid acid Solid acids are acids that do not dissolve in the reaction medium. They are often used in heterogeneous catalysts. Most solid state acids are organic acids such as oxalic acid, tartaric acid, citric acid, maleic acid, etc. Examples include oxides, which function as Lewis acids including silico-aluminates (zeolites, alumina, silico-alumino-phosphate), and sulfated zirconia. Many transition metal oxides are acidic, including titania, zirconia, and niobia. Such acids are used in cracking. Many solid Brønsted acids are also employed industrially, including sulfonated polystyrene, solid phosphoric acid, niobic acid, and heteropolyoxometallates. Solid acids are used in catalysis in many industrial chemical processes, from large-scale catalytic cracking in petroleum refining to the synthesis of various fine chemicals. One large scale application is alkylation, e.g., the combination of benzene and ethylene to give ethylbenzene. Another application is the rearrangement of cyclohexanone oxime to caprolactam. Many alkylamines are prepared by amination of alcohols, catalyzed by solid acids. Solid acids can be used as electrolytes in fuel cells. | https://en.wikipedia.org/wiki?curid=41451915 |
Sulfoselenide In chemistry, a sulfoselenide is a compound containing both metal sulfides and metal selenides. Because metal sulfides and metal selenides have similar crystal structures, they exhibit some mutual solubility, forming solid solutions. Since the ionic radius sulfide of (S) is however much smaller than that for selenide (Se), the solubility ranges can be only limited. For example, pyrite (FeS) will accept only a few percent of selenium in place of sulfur. A broader range is seen for the solid solution of cadmium sulfide and cadmium selenide. CdS is yellow and CdSe is red. The sulfoselenides of cadmium are orange. They are used as an artist's pigment. | https://en.wikipedia.org/wiki?curid=41465446 |
Evolution of photosynthesis The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy synthesizes sugars from carbon dioxide and water, releasing oxygen as a waste product. The process of photosynthesis was discovered by Jan Ingenhousz, a Dutch-born British physician and scientist, first publishing about it in 1779. The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or electrons, rather than water. There are three major metabolic pathways by which photosynthesis is carried out: C photosynthesis, C photosynthesis, and CAM photosynthesis. C photosynthesis is the oldest and most common form. C3 is a plant that uses the calvin cycle for the initial steps that incorporate CO2 into organic material. C4 is a plant that prefaces the calvin cycle with reactions that incorporate CO2 into four-carbon compounds. CAM is a plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions. C4 and CAM Plants have special adaptations that save water. The biochemical capacity to use water as the source for electrons in photosynthesis evolved in a common ancestor of extant cyanobacteria. The geological record indicates that this transforming event took place early in Earth's history, at least 2450–2320 million years ago (Ma), and, it is speculated, much earlier | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis Available evidence from geobiological studies of Archean (>2500 Ma) sedimentary rocks indicates that life existed 3500 Ma, but the question of when oxygenic photosynthesis evolved is still unanswered. A clear paleontological window on cyanobacterial evolution opened about 2000 Ma, revealing an already-diverse biota of blue-greens. Cyanobacteria remained principal primary producers throughout the Proterozoic Eon (2500–543 Ma), in part because the redox structure of the oceans favored photoautotrophs capable of nitrogen fixation. Green algae joined blue-greens as major primary producers on continental shelves near the end of the Proterozoic, but only with the Mesozoic (251–65 Ma) radiations of dinoflagellates, coccolithophorids, and diatoms did primary production in marine shelf waters take modern form. Cyanobacteria remain critical to marine ecosystems as primary producers in oceanic gyres, as agents of biological nitrogen fixation, and, in modified form, as the plastids of marine algae. Early photosynthetic systems, such as those from green and purple sulfur and green and purple nonsulfur bacteria, are thought to have been anoxygenic, using various molecules as electron donors. Green and purple sulfur bacteria are thought to have used hydrogen and sulfur as an electron donor. Green nonsulfur bacteria used various amino and other organic acids. Purple nonsulfur bacteria used a variety of nonspecific organic molecules. Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3 | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis 4 billion years old. More recent studies, reported in March 2018, also suggest that photosynthesis may have begun about 3.4 billion years ago. The main source of oxygen in the atmosphere is oxygenic photosynthesis, and its first appearance is sometimes referred to as the oxygen catastrophe. Geological evidence suggests that oxygenic photosynthesis, such as that in cyanobacteria, became important during the Paleoproterozoic era around 2 billion years ago. Modern photosynthesis in plants and most photosynthetic prokaryotes is oxygenic. Oxygenic photosynthesis uses water as an electron donor, which is oxidized to molecular oxygen () in the photosynthetic reaction center. Timeline of Photosynthesis on Earth Several groups of animals have formed symbiotic relationships with photosynthetic algae. These are most common in corals, sponges and sea anemones. It is presumed that this is due to the particularly simple body plans and large surface areas of these animals compared to their volumes. In addition, a few marine mollusks "Elysia viridis" and "Elysia chlorotica" also maintain a symbiotic relationship with chloroplasts they capture from the algae in their diet and then store in their bodies. This allows the mollusks to survive solely by photosynthesis for several months at a time. Some of the genes from the plant cell nucleus have even been transferred to the slugs, so that the chloroplasts can be supplied with proteins that they need to survive | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis An even closer form of symbiosis may explain the origin of chloroplasts. Chloroplasts have many similarities with photosynthetic bacteria, including a circular chromosome, prokaryotic-type ribosomes, and similar proteins in the photosynthetic reaction center. The endosymbiotic theory suggests that photosynthetic bacteria were acquired (by endocytosis) by early eukaryotic cells to form the first plant cells. Therefore, chloroplasts may be photosynthetic bacteria that adapted to life inside plant cells. Like mitochondria, chloroplasts still possess their own DNA, separate from the nuclear DNA of their plant host cells and the genes in this chloroplast DNA resemble those in cyanobacteria. DNA in chloroplasts codes for redox proteins such as photosynthetic reaction centers. The CoRR Hypothesis proposes that this Co-location is required for Redox Regulation. Photosynthesis is not quite as simple as adding water to to produce sugars and oxygen. A complex chemical pathway is involved, facilitated along the way by a range of enzymes and co-enzymes. The enzyme RuBisCO is responsible for "fixing" – that is, it attaches it to a carbon-based molecule to form a sugar, which can be used by the plant, releasing an oxygen molecule along the way. However, the enzyme is notoriously inefficient, and just as effectively will also fix oxygen instead of in a process called photorespiration. This is energetically costly as the plant has to use energy to turn the products of photorespiration back into a form that can react with | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis The C metabolic pathway is a valuable recent evolutionary innovation in plants, involving a complex set of adaptive changes to physiology and gene expression patterns. About 7600 species of plants use carbon fixation, which represents about 3% of all terrestrial species of plants. All these 7600 species are angiosperms. C plants evolved carbon concentrating mechanisms. These work by increasing the concentration of around RuBisCO, thereby facilitating photosynthesis and decreasing photorespiration. The process of concentrating around RuBisCO requires more energy than allowing gases to diffuse, but under certain conditions – i.e. warm temperatures (>25 °C), low concentrations, or high oxygen concentrations – pays off in terms of the decreased loss of sugars through photorespiration. One type of C metabolism employs a so-called Kranz anatomy. This transports through an outer mesophyll layer, via a range of organic molecules, to the central bundle sheath cells, where the is released. In this way, is concentrated near the site of RuBisCO operation. Because RuBisCO is operating in an environment with much more than it otherwise would be, it performs more efficiently. In C photosynthesis, carbon is fixed by an enzyme called PEP carboxylase, which, like all enzymes involved in C photosynthesis, originated from non-photosynthetic ancestral enzymes. A second mechanism, CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis The most important benefit of CAM to the plant is the ability to leave most leaf stomata closed during the day. This reduces water loss due to evapotranspiration. The stomata open at night to collect , which is stored as the four-carbon acid malate, and then used during photosynthesis during the day. The pre-collected is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency. More is then harvested from the atmosphere when stomata open, during the cool, moist nights, reducing water loss. CAM has evolved convergently many times. It occurs in 16,000 species (about 7% of plants), belonging to over 300 genera and around 40 families, but this is thought to be a considerable underestimate. It is found in quillworts (relatives of club mosses), in ferns, and in gymnosperms, but the great majority of plants using CAM are angiosperms (flowering plants). These two pathways, with the same effect on RuBisCO, evolved a number of times independently – indeed, C alone arose 62 times in 18 different plant families. A number of 'pre-adaptations' seem to have paved the way for C4, leading to its clustering in certain clades: it has most frequently been innovated in plants that already had features such as extensive vascular bundle sheath tissue. Whole-genome and individual gene duplication are also association with C evolution | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis Many potential evolutionary pathways resulting in the phenotype are possible and have been characterised using Bayesian inference, confirming that non-photosynthetic adaptations often provide evolutionary stepping stones for the further evolution of . The C construction is most famously used by a subset of grasses, while CAM is employed by many succulents and cacti. The trait appears to have emerged during the Oligocene, around ; however, they did not become ecologically significant until the Miocene, . Remarkably, some charcoalified fossils preserve tissue organised into the Kranz anatomy, with intact bundle sheath cells, allowing the presence C metabolism to be identified without doubt at this time. Isotopic markers are used to deduce their distribution and significance. C plants preferentially use the lighter of two isotopes of carbon in the atmosphere, C, which is more readily involved in the chemical pathways involved in its fixation. Because C metabolism involves a further chemical step, this effect is accentuated. Plant material can be analysed to deduce the ratio of the heavier C to C. This ratio is denoted . C plants are on average around 14‰ (parts per thousand) lighter than the atmospheric ratio, while C plants are about 28‰ lighter. The of CAM plants depends on the percentage of carbon fixed at night relative to what is fixed in the day, being closer to C plants if they fix most carbon in the day and closer to C plants if they fix all their carbon at night | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis It is troublesome procuring original fossil material in sufficient quantity to analyse the grass itself, but fortunately there is a good proxy: horses. Horses were globally widespread in the period of interest, and browsed almost exclusively on grasses. There's an old phrase in isotope palæontology, "you are what you eat (plus a little bit)" – this refers to the fact that organisms reflect the isotopic composition of whatever they eat, plus a small adjustment factor. There is a good record of horse teeth throughout the globe, and their has been measured. The record shows a sharp negative inflection around , during the Messinian, and this is interpreted as the rise of C plants on a global scale. While C enhances the efficiency of RuBisCO, the concentration of carbon is highly energy intensive. This means that C plants only have an advantage over C organisms in certain conditions: namely, high temperatures and low rainfall. C plants also need high levels of sunlight to thrive. Models suggest that, without wildfires removing shade-casting trees and shrubs, there would be no space for C plants. But, wildfires have occurred for 400 million years – why did C take so long to arise, and then appear independently so many times? The Carboniferous period (~) had notoriously high oxygen levels – almost enough to allow spontaneous combustion – and very low , but there is no C isotopic signature to be found. And there doesn't seem to be a sudden trigger for the Miocene rise | https://en.wikipedia.org/wiki?curid=41468418 |
Evolution of photosynthesis During the Miocene, the atmosphere and climate were relatively stable. If anything, increased gradually from before settling down to concentrations similar to the Holocene. This suggests that it did not have a key role in invoking C evolution. Grasses themselves (the group which would give rise to the most occurrences of C) had probably been around for 60 million years or more, so had had plenty of time to evolve C, which, in any case, is present in a diverse range of groups and thus evolved independently. There is a strong signal of climate change in South Asia; increasing aridity – hence increasing fire frequency and intensity – may have led to an increase in the importance of grasslands. However, this is difficult to reconcile with the North American record. It is possible that the signal is entirely biological, forced by the fire- and grazer- driven acceleration of grass evolution – which, both by increasing weathering and incorporating more carbon into sediments, reduced atmospheric levels. Finally, there is evidence that the onset of C from is a biased signal, which only holds true for North America, from where most samples originate; emerging evidence suggests that grasslands evolved to a dominant state at least 15Ma earlier in South America. | https://en.wikipedia.org/wiki?curid=41468418 |
C12H23N The molecular formula CHN may refer to: | https://en.wikipedia.org/wiki?curid=41472254 |
C19H23NO The molecular formula CHNO may refer to: | https://en.wikipedia.org/wiki?curid=41472882 |
Photoaffinity labeling is a technique used to attach "labels" to the active site of a large molecule, especially a protein. The "label" attaches to the molecule loosely and reversibly, and has an inactive site which can be converted using photolysis into a highly reactive form, which causes the label to bind more permanently to the large molecule via a covalent bond. The technique was first described in the 1970s. Molecules that have been used as labels in this process are often analogs of complex molecules, in which certain functional groups are replaced with a photoreactive group, such as an azide, a diazirine or a benzophenone. | https://en.wikipedia.org/wiki?curid=41478545 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.