Academic literature on the topic 'Heavy Element Containing Molecules'
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Journal articles on the topic "Heavy Element Containing Molecules"
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Thomas, Reji, and Nobuyuki Tamaoki. "Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element." Beilstein Journal of Organic Chemistry 12 (October 19, 2016): 2211–15. http://dx.doi.org/10.3762/bjoc.12.212.
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Single crystal X-ray diffraction has been used as one of the common methods for the unambiguous determination of the absolute stereostructure of chiral molecules. However, this method is limited to molecules containing heavy atoms or to molecules with the possibility of functionalization with heavy elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i.e., defunctionalization of its precursor of known stereostructure with bromine substitution (S-(−)-(E)-1). A reductive debromination of S-(−)-(E)-1 results in formation of one of the enantiomers of (E)-2. Using a combination of HPLC and CD spectroscopy we could safely assign the stereostructure of one of the enantiomers of (E)-2, the reduced product R-(−)-(E)-1.
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Scott, Gregory E., and Karl K. Irikura. "Electron-Impact Ionization Cross Sections of Molecules Containing Heavy Elements (Z> 10)." Journal of Chemical Theory and Computation 1, no. 6 (November 2005): 1153–61. http://dx.doi.org/10.1021/ct050077j.
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Bazett-Jones, D. P., and M. J. Hendzel. "High resolution mapping of nucleic acid containing complexes in vitro and in situ." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 48–49. http://dx.doi.org/10.1017/s0424820100162703.
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Structural analysis of combinations of nucleosomes and transcription factors on promoter and enhancer elements is necessary in order to understand the molecular mechanisms responsible for the regulation of transcription initiation. Such complexes are often not amenable to study by high resolution crystallographic techniques. We have been applying electron spectroscopic imaging (ESI) to specific problems in molecular biology related to transcription regulation. There are several advantages that this technique offers in studies of nucleoprotein complexes. First, an intermediate level of spatial resolution can be achieved because heavy atom contrast agents are not necessary. Second, mass and stoichiometric relationships of protein and nucleic acid can be estimated by phosphorus detection, an element in much higher proportions in nucleic acid than protein. Third, wrapping or bending of the DNA by the protein constituents can be observed by phosphorus mapping of the complexes. Even when ESI is used with high exposure of electrons to the specimen, important macromolecular information may be provided. For example, an image of the TATA binding protein (TBP) bound to DNA is shown in the Figure (top panel). It can be seen that the protein distorts the DNA away from itself and much of its mass sits off the DNA helix axis. Moreover, phosphorus and mass estimates demonstrate whether one or two TBP molecules interact with this particular promoter TATA sequence.
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Bischoff, Florian A., Sebastian Höfener, Andreas Glöß, and Wim Klopper. "Explicitly correlated second-order perturbation theory calculations on molecules containing heavy main-group elements." Theoretical Chemistry Accounts 121, no. 1-2 (April 8, 2008): 11–19. http://dx.doi.org/10.1007/s00214-008-0441-8.
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Wang, Fan, and Lemin Li. "Numerical examination of performance of some exchange-correlation functionals for molecules containing heavy elements." Journal of Computational Chemistry 25, no. 5 (2004): 669–77. http://dx.doi.org/10.1002/jcc.10421.
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Oura, M., T. Gejo, K. Nagaya, Y. Kohmura, K. Tamasaku, L. Journel, M. N. Piancastelli, and M. Simon. "Hard x-ray photoelectron spectroscopy on heavy atoms and heavy-element containing molecules using synchrotron radiation up to 35 keV at SPring-8 undulator beamlines." New Journal of Physics 21, no. 4 (April 12, 2019): 043015. http://dx.doi.org/10.1088/1367-2630/ab09a3.
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Andreocci, Marco V., Carla Cauletti, Stefano Stranges, Bernd Wrackmeyer, and Carin Stader. "UV Photoelectron Spectra and Pseudopotential “ab initio” Calculations of Some 4-Membered Cyclic Amides of Group XIV Elements." Zeitschrift für Naturforschung B 46, no. 1 (January 1, 1991): 39–46. http://dx.doi.org/10.1515/znb-1991-0109.
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Gas-phase He I and He II photoelectron spectroscopy and Pseudopotential “ab initio” calculations were used to determine the electronic structure of some 4-membered cyclic amides containing Si, Sn and Pb.The IE splitting on the non-bonding nitrogen-localized m .o .s ., nNasym(a2) and nNsym(b2), due to the “through space” interaction is critically affected by the planar ring molecular structure and the coordination of the silicon and tin atoms of the ring.The pseudopotential “ab initio” model resulted successful in describing the electronic structure of the molecules containing heavy atoms, at a Koopmans’ approximation level.
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Lloyd, Austin, Helen Moylan, and Joseph McDouall. "Modelling the Effect of Zero-Field Splitting on the 1H, 13C and 29Si Chemical Shifts of Lanthanide and Actinide Compounds." Magnetochemistry 5, no. 1 (January 11, 2019): 3. http://dx.doi.org/10.3390/magnetochemistry5010003.
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The prediction of paramagnetic NMR (pNMR) chemical shifts in molecules containing heavy atoms presents a significant challenge to computational quantum chemistry. The importance of meeting this challenge lies in the central role that NMR plays in the structural characterisation of chemical systems. Hence there is a need for reliable assignment and prediction of chemical shifts. In a previous study [Trends in Physical Chemistry, 17, 25–57, (2017)] we looked at the computation of pNMR chemical shifts in lanthanide and actinide complexes using a spin Hamiltonian approach. In that study we were principally concerned with molecules with S = 1/2 ground states. In the present work we extend that study by looking at the effect of zero field splitting (ZFS) for six complexes with S = 3/2 ground states. It is shown that the inclusion of ZFS can produce substantial shifts in the predicted chemical shifts. The computations presented are typically sufficient to enable assignment of experimental spectra. However for one case, in which the peaks are closely clustered, the inclusion of ZFS re-orders the chemical shifts making assignment quite difficult. We also observe, and echo, the previously reported importance of including the paramagnetic spin-orbit hyperfine interaction for 13 C and 29 Si atoms, when these are directly bound to a heavy element and thus subject to heavy-atom-light-atom effects. The necessary computations are very demanding, and more work is needed to find theoretical and computational approaches that simplify the evaluation of this term. We discuss the computation of each term required in the spin Hamiltonian. The systems we study in this work are restricted to a single heavy atom ion (one Nd(III) and five U(III) complexes), but typify some of the computational complexity encountered in lanthanide and actinide containing molecules.
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Gaul, Konstantin, and Robert Berger. "Quasi-relativistic study of nuclear electric quadrupole coupling constants in chiral molecules containing heavy elements." Molecular Physics 118, no. 19-20 (August 3, 2020): e1797199. http://dx.doi.org/10.1080/00268976.2020.1797199.
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Märkl, Raphael S., Nuri Hohn, Emanuel Hupf, Lorenz Bießmann, Volker Körstgens, Lucas P. Kreuzer, Gaetano Mangiapia, et al. "Comparing the backfilling of mesoporous titania thin films with hole conductors of different sizes sharing the same mass density." IUCrJ 7, no. 2 (February 12, 2020): 268–75. http://dx.doi.org/10.1107/s2052252520000913.
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Efficient infiltration of a mesoporous titania matrix with conducting organic polymers or small molecules is one key challenge to overcome for hybrid photovoltaic devices. A quantitative analysis of the backfilling efficiency with time-of-flight grazing incidence small-angle neutron scattering (ToF-GISANS) and scanning electron microscopy (SEM) measurements is presented. Differences in the morphology due to the backfilling of mesoporous titania thin films are compared for the macromolecule poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7-Th) and the heavy-element containing small molecule 2-pinacolboronate-3-phenylphenanthro[9,10-b]tellurophene (PhenTe-BPinPh). Hence, a 1.7 times higher backfilling efficiency of almost 70% is achieved for the small molecule PhenTe-BPinPh compared with the polymer PTB7-Th despite sharing the same volumetric mass density. The precise characterization of structural changes due to backfilling reveals that the volumetric density of backfilled materials plays a minor role in obtaining good backfilling efficiencies and interfaces with large surface contact.
Dissertations / Theses on the topic "Heavy Element Containing Molecules"
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Wann, Derek A. "Gas-phase structures of molecules containing heavy p-block elements." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/1209.
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Gas-phase electron diffraction (GED) is the method of choice for determining the structures of molecules containing between two and 100 atoms, free from intermolecular interaction. However, for many molecules it becomes necessary to augment the experimental GED data with information from other sources. The SARACEN method, used routinely at Edinburgh when determining structures, allows computed parameters from ab initio and density functional theory (DFT) calculations to be used as extra data in the GED refinement process. This thesis describes the determinations of the gas-phase structures of molecules that contain heavy p-block elements, including examples from Groups 13, 14, 15 and 16. Each of the compounds studied was solid at room temperature, requiring heating to produce a suitable vapour pressure and vaporisation rate and testing the existing electron diffraction apparatus to its limits. Use was made of a new heated reservoir, recently developed in Edinburgh by a previous PhD student, which has allowed compounds to be studied that were previously inaccessible. The molecules that were studied during the course of this degree are: In(P3C2But2), In(P2C3But3), Sn(P2C2But2), Sb2(C6F6)3, Bi2(C6F6)3, Se(SCH3)2 and Te(SCH3)2. While determining the structures of these molecules, accurate theoretical geometries have been obtained using both ab initio and DFT methods. As a result a better understanding has been achieved of which methods are suitable for use in calculating the structures of molecules with heavy p-block elements. The use of pseudopotentials as opposed to all-electron basis sets proved necessary when performing calculations on such large molecules with heavy atoms. The extent to which these pseudopotentials, especially ones that consider very few electrons to be in the valence shell of an atom, can affect the calculated geometries has been shown to be considerable. In addition, methods being developed to compute vibrational corrections for gas-phase structure determination have been extended to the crystalline phase. Molecular dynamics simulations have been used to derive the effects of vibrations on average nuclear positions, relative to equilibrium positions. The differences, when applied to coordinates obtained experimentally by neutron diffraction yield experimental equilibrium structures.
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Zhao, KeZhao Ke. "Electronic structure of heavy-element molecules : Pa@c28, Pa(C8H8)2, and the Jahn-Teller effect in VCl4 /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487940665435687.
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Nahrwold, Sophie [Verfasser], Robert [Akademischer Betreuer] Berger, and Dieter [Akademischer Betreuer] Schuch. "Electroweak quantum chemistry: Parity violation in spectra of chiral molecules containing heavy atoms / Sophie Nahrwold. Gutachter: Robert Berger ; Dieter Schuch." Frankfurt am Main : Univ.-Bibliothek Frankfurt am Main, 2012. http://d-nb.info/1044275545/34.
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Oberlander, Michael David. "Laser Excited Fluorescence Studies of Reactions of Group 2 Metals with Oxygen Containing Molecules and of Heavy Group 15 Clusters with Fluorine : Reactivities, Product State Distributions and Spectroscopy of the BiF A 0+ - X 0+ Transition /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487862399449884.
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"Optical Spectroscopy of Heavy Element Containing Molecules In Support of Fundamental Physics." Doctoral diss., 2019. http://hdl.handle.net/2286/R.I.53580.
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abstract: Transient molecules are of great importance having proposed applications in quantum science and technology and tests of fundamental physics. In the present dissertation, the transient molecules studied are SrOH, ThF, ThCl, YbF and YbOH; each having been selected because of their proposed application. Specifically, SrOH is a candidate of constructing a molecular magneto-optical trap (MOT). The simple actinide molecules, ThF and ThCl, were selected as ligand bonding model systems to gain insight into chemical processing of Spent Nuclear Fuel. The lanthanides YbF and YbOH are venues for the determination of electron electric dipole moment (eEDM) and the studies in this dissertation provide the requisite properties for those experiments.
Intense supersonic molecular beams of these transient molecules were generated via laser ablation and spectroscopically characterized using a novel medium-resolution two-dimensional (2D) spectroscopic approach, as well as high-resolution laser induced fluorescence (LIF). The 2D medium resolution approach, which was used in the studies SrOH, ThF, ThCl and YbOH, uses a multiplexing method that simultaneously records dispersed fluorescence and excitation spectra. A significant advantage of 2D-LIF imaging is that all the electronics states can be targeted to determine the electronics states and associated vibrational spacing individually. Consequently, in the 2D spectra of ThF, ThCl and YbOH, several previously unobserved band systems have been detected in one single scan. For the DF spectra of SrOH and YbOH, the determined branching ratios show that the transitions of these molecules are diagonal (i.e. Δv=0), which is essential for the proposed potential for laser cooling. In the high-resolution of YbF, ThF, ThCl and SrOH optical spectra were recorded to an accuracy of ±30 MHz, which represents an unprecedented precision of 1:10+8.
In addition to field free spectra, optical Stark and Zeeman studies were performed to determine the most fundamental magneto-and electro-static properties. Effective Hamiltonian operators were employed to analyze the recorded spectra and determine the spectroscopic parameters. This data set also establishes a contribution toward developing new computational methodologies for treating relativistic effects and electron correlation.Dissertation/Thesis
Doctoral Dissertation Chemistry 2019
Books on the topic "Heavy Element Containing Molecules"
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Trieloff, Mario. Noble Gases. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190647926.013.30.
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This is an advance summary of a forthcoming article in the Oxford Encyclopedia of Planetary Science. Please check back later for the full article.Although the second most abundant element in the cosmos is helium, noble gases are also called rare gases. The reason is that they are not abundant on terrestrial planets like our Earth, which is characterized by orders of magnitude depletion of—particularly light—noble gases when compared to the cosmic element abundance pattern. Indeed, such geochemical depletion and enrichment processes make noble gases so versatile concerning planetary formation and evolution: When our solar system formed, the first small grains started to adsorb small amounts of noble gases from the protosolar nebula, resulting in depletion of light He and Ne when compared to heavy noble gases Ar, Kr, and Xe: the so-called planetary type abundance pattern. Subsequent flash heating of the first small mm to cm-sized objects (chondrules and calcium, aluminum rich inclusions) resulted in further depletion, as well as heating—and occasionally differentiation—on small planetesimals, which were precursors of larger planets and which we still find in the asteroid belt today from where we get rocky fragments in form of meteorites. In most primitive meteorites, we even can find tiny rare grains that are older than our solar system and condensed billions of years ago in circumstellar atmospheres of, for example, red giant stars. These grains are characterized by nucleosynthetic anomalies and particularly identified by noble gases, for example, so-called s-process xenon.While planetesimals acquired a depleted noble gas component strongly fractionated in favor of heavy noble gases, the sun and also gas giants like Jupiter attracted a much larger amount of gas from the protosolar nebula by gravitational capture. This resulted in a cosmic or “solar type” abundance pattern, containing the full complement of light noble gases. Contrary to Jupiter or the sun, terrestrial planets accreted from planetesimals with only minor contributions from the protosolar nebula, which explains their high degree of depletion and basically “planetary” elemental abundance pattern. Indeed this depletion enables another tool to be applied in noble gas geo- and cosmochemistry: ingrowth of radiogenic nuclides. Due to heavy depletion of primordial nuclides like 36Ar and 130Xe, radiogenic ingrowth of 40Ar by 40K decay, 129Xe by 129I decay, or fission Xe from 238U or 244Pu decay are precisely measurable, and allow insight in the chronology of fractionation of lithophile parent nuclides and atmophile noble gas daughters, mainly caused by mantle degassing and formation of the atmosphere.Already the dominance of 40Ar in the terrestrial atmosphere allowed C. F v. Weizsäcker to conclude that most of the terrestrial atmosphere originated by degassing of the solid Earth, which is an ongoing process today at mid ocean ridges, where primordial helium leaves the lithosphere for the first time. Mantle degassing was much more massive in the past; in fact, most of the terrestrial atmosphere formed during the first 100 million years of Earth´s history, and was completed at about the same time when the terrestrial core formed and accretion was terminated by a giant impact that also formed our moon. However, before that time, somehow also tiny amounts of solar noble gases managed to find their way into the mantle, presumably by solar wind irradiation of small planetesimals or dust accreting to Earth. While the moon-forming impact likely dissipated the primordial atmosphere, today´s atmosphere originated by mantle degassing and a late veneer with asteroidal and possibly cometary contributions. As other atmophile elements behave similar to noble gases, they also trace the origin of major volatiles on Earth, for example, water, nitrogen, sulfur, and carbon.
Book chapters on the topic "Heavy Element Containing Molecules"
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Tanaka, Kazuo, and Yoshiki Chujo. "Rational Designs of AIE-Active Molecules and Luminochromic Materials Based on Group 13 Element-Containing Element-Blocks." In Principles and Applications of Aggregation-Induced Emission, 27–42. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99037-8_2.
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Sawyer, Donald T., and R. J. P. Williams. "Introduction: Why oxygen chemstry?" In Oxygen Chemistry. Oxford University Press, 1992. http://dx.doi.org/10.1093/oso/9780195057980.003.0005.
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The fundamental premise of chemistry is that all matter consists of molecules. The physical and chemical properties of matter are those of the constituent molecules, and the transformation of matter into different materials (compounds) is the result of their reactions to form new molecules. A molecule consists of two or more atoms held in a relatively fixed array via valence-electron orbital overlap (covalent bonds; chemical bonds). In the nineteenth century chemists focused on the remarkable diversity of molecules produced by living organisms, which have in common the presence of tetravalent carbon atoms. As a result the unique versatility of carbon for the design and synthesis of new molecules was discovered, and the subdiscipline of organic chemistry (the science of carbon-containing molecules) has become the dominant part of the discipline. Clearly, the results from a focus on carbon-based chemistry have been immensely useful to science and to society. Although most molecules in biological systems [and produced by living organisms (particularly aerobic systems)] contain oxygen atoms as well as carbon and hydrogen (e.g., proteins, nucleic acids, carbohydrates, lipids, hormones, and vitamins), there has been a long tradition in all of chemistry to treat oxygen atoms as “neutral counterweights” for the “important,” character-determining elements (C, H, Al, Si, Fe, I) of the molecule. Thus, chemists have tended to take the most important element (oxygen) for granted. The chemistry curriculum devotes one or two year-courses to the chemistry of carbon (“Organic Chemistry”), but only a brief chapter on oxygen is included in the first-year and the inorganic courses. However, if the multitude of hydrocarbon molecules is from the incorporation of oxygen atoms in single-carbon molecules argues against the assignment of a “neutral character” for oxygen atoms [e.g., Cn(graphite), CH4(g), CH3OH(1), CH2(O)(1), HC(O)OH(1), (HO)2C(O)(aq), CO(g), CO2(g)]. Just as the focus of nineteenth century chemists on carbon-containing molecules has produced revolutionary advances in chemical understanding, and yielded the technology to synthesize and produce useful chemicals, polymers, and medicinals; I believe that a similar focus on oxygen chemistry is appropriate and will have analogous rewards for chemistry, biochemistry, and the chemical process technologies.
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Chantrapromma, Suchada, Hoong-Kun Fun, Surat Laphookhieo, Saroj Cheenpracha, and Chatchanok Karalai. "Determination of Absolute Configuration of Natural Products by X-ray Diffraction: A Novel Approach of Incorporating Heavy-Atom-Containing Solvent Molecules into the Single Crystals and Refinement of Flack Parameter." In Frontiers in Natural Product Chemistry, 99–106. BENTHAM SCIENCE PUBLISHERS, 2009. http://dx.doi.org/10.2174/907752704410501010099.
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Rigoutsos, Isidore, and Daniel Platt. "Representation and Matching of Small Flexible Molecules in Large Databases of 3D Molecular Information." In Pattern Discovery in Biomolecular Data. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195119404.003.0013.
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In recent years, the need to process and mine available information repositories has been increasing. The variety of the data contained in the targeted databases has given rise to a variety of tools for mining them, and computers have assumed an increasingly important role in this process. One of the many domains in which this scenario has been repeated is that of the drug discovery and design process. Computers have helped researchers to quickly eliminate unlikely drug candidates, to home in on promising ones, and to shorten the lead-compound-search cycle. Researchers are helped in this multidisciplinary effort by accessing proprietary and public resources containing crystallography, nuclear magnetic resonance, toxicology, pharmacology, and other types of data. Using the computer to filter out unlikely candidates can greatly shorten the length of a cycle in this iterative process. Some scenarios encountered in the context of the drug design process include . . . (a) a pharmacophore model that has been proposed from several active molecules—one wishes to determine other molecules that either corroborate or refute the model; (b) a set of untested molecules that exhibit biological activity—one wishes to identify relationships between their 3D structure and the activity; (c) a ligand that has been proposed to be active in a certain conformation- -other molecules that mimic the ligand’s behavior are sought. . . . The common element in all of these cases is that they are in essence searches for member elements in one or more repositories, each of the elements having some desired properties or behavior. Let us take a step back and reexamine the problem we are trying to solve. Two basic elements of the problem are “representation” and “storage.” If answers to both of these questions are available, then one can implement a retrieval system the properties and behavior of which are directly related to those of the two basic elements. We begin with a body of knowledge D that consists of D data items {di / i = 1,..., D}. Each data item is represented by a set of k properties and their respective values.
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Keats, Jonathon. "Copernicium." In Virtual Words. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195398540.003.0005.
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The only accolade that American chemist Glen T. Seaborg cared for more than winning the Nobel Prize was having an element named in his honor. In 1994 his colleagues gave him that distinction, elevating the Nobel laureate to the status of helium and hydrogen. Over the next fifteen years, six more elements followed seaborgium onto the periodic table, bringing the total to 112. The last, enshrined in 2009, pays homage to Nicolas Copernicus. Unlike Seaborg, Copernicus never sought such a tribute. Having already scored ample name recognition with the Copernican Revolution, he didn’t really need it. If anything, by the time copernicium was recognized as an element, the periodic table needed him. Copernicium is one of twenty elements containing more protons than the ninety-two naturally found in uranium. All twenty are made artificially in laboratories by colliding preexisting elements such as zinc and lead in a particle accelerator or cyclotron. In some ten billion billion bombardments, two protons will fuse to make one atom of a new super-heavy element. Typically the atom is unstable, lasting perhaps a millisecond before decaying into lighter elements again. All of which makes element fabrication a tricky enterprise, nearly as miraculous as alchemy and considerably more contentious. Who synthesized the first atom of an element, and therefore gets to name it? Seaborg’s UC Berkeley laboratory was the only one in the business through the 1940s and 1950s, netting him ten elements, including plutonium, for which he won the 1951 Nobel Prize in Chemistry. By the 1960s, however, there was competition from the Soviets, resulting in the so-called Transfermium Wars. For several decades the periodic table became a political battlefield rather than an intellectual commons. Nothing could have been further from the table’s Enlightenment origins. The product of empirical research and intended to disseminate universal knowledge, a table of presumed elements was first published by the French chemist Antoine Lavoisier in 1789, arranging thirty-three substances, including silver and sulfur and phosphorus, based on observed attributes (such as “Oxydable and Acidifiable simple Metallic Bodies”) rather than according to philosophical precepts.
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Oriakhi, Christopher O. "Chemical Equations." In Chemistry in Quantitative Language. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780195367997.003.0012.
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A chemical equation is a shorthand way of describing a chemical reaction. It uses symbols of elements and formulas of compounds in place of words to describe a chemical change or reaction. 1. The formulas and symbols of reactants are written on the left side of the equation. 2. The formulas and symbols of products are written on the right side of the equation. 3. A plus sign (+) is placed between different reactants and different products. 4. The reactants are separated from the products by an arrow (→) pointing in the direction of the reaction. For a reversible reaction, double arrow (⇄) is used. 5. The physical states of substances may be indicated by the symbols (s) for solid, (l) for liquid, (aq) for aqueous solution, and (g) for gases. 6. The equation is then balanced by inserting appropriate coefficients for the products and reactants. For the word equation Sulfur trioxide+Water → Sulfuric acid we can substitute the formulas for reactants and products, following the above rules, and obtain a chemical equation for the reaction as: SO3(g)+H2O(l) −→ H2SO4(aq) A chemical equation is balanced when it has the same number of atoms of each element on either side of the equation. Thus, a balanced equation obeys the law of conservation of mass. That is, atoms are not ‘created’ or ‘destroyed’ in writing a chemical equation. 1. Formulate and write a word equation if necessary from experiment or problem. 2. Write the unbalanced equation using the rules for writing chemical formulas. 3. Balance the equation to make sure the law of conservation of mass is observed. (a) Inspect both sides of the equation to identify atoms that need to be balanced. (b) Balance one element at a time by placing a suitable coefficient to the left of the formula containing the element. Note that a coefficient placed in front of the formula affects all the atoms in the formula. For example, 2 H2O implies 2 molecules of water containing 4 atoms of hydrogen and 2 atoms of oxygen. (c) Never attempt to balance an equation by changing subscripts because this will change the formulas of the compounds.
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Atkins, Peter. "Give and Take: Neutralization." In Reactions. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199695126.003.0006.
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The almost infinite can spring from the almost infinitesimal. Two almost infinitesimally small fundamental particles are of considerable interest to chemists: the proton and the electron. As to the almost infinite that springs from them, almost the whole of the processes that constitute what we call ‘life’ can be traced to the transfer of one or other of these particles from one molecule to another in a giant network of reactions going on inside our cells. I think it quite remarkable, and rather wonderful, that a hugely complex network of extremely simple processes in which protons and electrons hop from one molecule to another, sometimes dragging groups of atoms with them, sometimes not, results in our formation, our growth, and all our activities. Even thinking about proton and electron transfer, as you are now, involves them. Here I consider the transfer of a proton in some straightforward reactions in preparation for seeing later, in the second part of the book, how the same processes result in eating, growing, reproducing, and thinking. For reactions that involve the transfer of electrons, see Reaction 5. What is a proton? For physicists, a proton is a minute, positively charged, very stable cluster of three quarks; they denote it p. For chemists, who are less concerned with ultimate things, a proton is the nucleus of a hydrogen atom; they commonly denote it H+ to signify that it is a hydrogen atom stripped of its one electron, a hydrogen ion. I shall flit between referring to this fundamental particle as a proton or a hydrogen ion as the fancy takes me: they are synonyms and the choice of name depends on convention and context. An atom is extraordinarily small, but a proton is about 100 000 times smaller than an atom. If you were to think of an atom as being the size of a football stadium, then a proton would be the size of a fly at its centre. It is nearly 2000 times as heavy as an electron. Nevertheless, a proton is still light and nimble enough to be able to slip reasonably easily out from its home at the centre of a hydrogen atom in some types of hydrogen-containing molecules.
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Anderson, Sharon J. "Proton and 19F NMR Spectroscopy of Pesticide Intermolecular Interactions." In Nuclear Magnetic Resonance Spectroscopy in Environment Chemistry. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195097511.003.0008.
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Sorption of organic pollutants by soils and sediments is one of the main chemical processes that controls pollutant migration in the environment. Information about the molecular mechanisms by which an organic pollutant interacts with other solution-phase constituents and with solid-phase sorbents would be invaluable for more accurate prediction of pollutant fate and transport and for optimal design and application of remediation procedures. Many current models and remediation strategies are based upon the “partition theory” of organic compound sorption, which predicts sorption coefficients from properties such as water solubility or octanol-water partition coefficients. Partition theory is well suited for nonpolar hydrocarbons but may not be appropriate for pesticides with electrophilic or weakly acidic or basic substituents, which may interact with soils or organic matter through specific interactions such as hydrogen bonding or charge-transfer complexes. If a pesticide can form hydrogen bonds or a charge-transfer complex with a sorbent, sorption may be greater than in the absence of specific interactions. Nuclear magnetic resonance (NMR) spectroscopy is well suited for the study of pesticide-solution or pesticide-sorbent interactions because NMR is an element-specific method that is extremely sensitive to the electron density (shielding) near the nucleus of interest. Consequently, solution-state NMR can distinguish between closely related functional groups and can provide information about intermolecular interactions. All nuclei with nonzero nuclear spin quantum number can be studied by NMR spectroscopy. Of the more than 100 NMR-active nuclei, 1H and 19F are the easiest to study because both have natural abundances near 100% and greater NMR sensitivity than any other nuclei. In addition, both 1H and 19F have zero quadrupolar moments, which means that sharp, well resolved NMR peaks can be obtained, at least in homogeneous solutions. Proton NMR is well suited for elucidating molecular interactions in solution but cannot be used to study interactions between pesticides and heterogeneous sorbents such as soils, humic acid, or even cell extracts, since protons in the sorbent generally produce broad peaks that mask the NMR peaks from the solute or sorbate of interest. In contrast, 19F NMR can be used to study interactions between fluorine-containing molecules and heterogeneous sorbents because the fluorine concentration in most natural sorbents is negligible.
Conference papers on the topic "Heavy Element Containing Molecules"
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Cheng, Lan. "COUPLED-CLUSTER CALCULATIONS FOR LOW-LYING ELECTRONIC STATES OF HEAVY-METAL CONTAINING MOLECULES." In 73rd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2018. http://dx.doi.org/10.15278/isms.2018.wf07.
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Abuali Galehdari, Nasim, and Ajit D. Kelkar. "Characterization of Nanoparticle Enhanced Multifunctional Sandwich Composites Subjected to Space Radiation." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66774.
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One of the major concerns in long duration space exploration is to minimize the exposure of crew and equipment to space radiation. High energy radiation not only can be hazardous to the health but also can damage the materials and electronics. Current designs are contained heavy metals to avoid occupational hazards from radiation exposures. As a result the shielding structures are heavy and not effective to attenuate all types of radiation. Therefore, the proposed lightweight sandwich composites are designed to effectively shield high energy radiations while providing structural integrity. In the manufactured hybrid sandwich composite, High Molecular Weight Poly Ethylene (HMWPE) woven fabrics are selected as face sheets due to their advanced mechanical properties and excellent physical properties along with effective shielding properties. Basically polymers due to high hydrogen content are considered as effective materials to attenuate high energy radiations. In addition, the core material is epoxy composites incorporating three weight percentages of three different nanoparticles viz. Boron Carbide, Boron Nanopowder and Gadolinium. In fact if polymers as low Z materials are used alone, they usually are not successful to attenuate highly penetrative rays. Therefore, one solution is known to infuse polymer matrix with high radiation absorption properties nanoparticles. Among several different nanomaterials, the three aforementioned nanofillers were chosen because of their good radiation absorption properties. Gadolinium has the highest thermal neutron cross section compare to any other known element and 10B-containing materials are known as excellent radiation absorbers and the composite filled with them have the advantage of convenient and safety in construction, operation and reintegration. The sandwich composites were manufactured using Heat-Vacuum Assisted Resin Transfer Molding method (H-VARTM), which is a cost effective method for high volume production of sandwich structures. To evaluate the shielding performance of manufactured sandwich panels the neutron attenuation testing was performed. The results from neutron radiation tests show more than 99% shielding performance in all of the sandwich panels. In comparison with other nanofillers, Boron Nanopowder showed highest radiation shielding efficiency (99.64%), which can be attributed to its lowest particle size and better dispersion ability into epoxy resin. The flatwise compression testing was performed on all four sandwich panels to determine the mechanical strength of materials before and after being exposure to radiation. The results demonstrate that proposed hybrid sandwich panels can preserve their mechanical integrity while being exposed to the radiation.
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Drexel, M. V., and J. H. Ginsberg. "Modal Overlap and Dissipation Effects in a Fuzzy Structure Containing a Continuous Master Element." In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/vib-8156.
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Abstract This work was prompted by a study performed by Strasberg (1997) in which numerous small spring-mass-damper systems are attached to a large suspended mass representing the master structure. The isolated natural frequency of each attached system was selected to match in average the natural frequency of the isolated master structure. Strasberg found that the critical issue when an impulse excitation is applied to the master structure is the bandwidth of the isolated attached systems in comparison to the spacing between the natural frequencies of the system. Modal overlap, which corresponds to the bandwidths that exceed the spacing of those frequencies, was shown to greatly influence the response of the master structure. Light damping, for which there is little modal overlap, corresponds to an impulse response that consists of a sequence of nearly periodic exponentially decaying pulses, and the transfer function for harmonic excitation of the master structure indicates that the sub-structure acts as a vibration absorber for the master structure. Increased damping leads to modal overlap, with the result that the impulse response consists of a single decaying pulse. The frequency domain transfer function indicates that the vibration absorber effect is enhanced. The present work explores these issues for continuous systems by replacing the one degree of freedom master structure with a cantilever beam. The system parameters are selected to match Strasberg’s model, with the suspended sub-structure placed randomly along the beam. The beam displacement is represented as a Ritz series whose basis functions are the cantilever beam modes. The coupled equations are solved by a state-space eigenmode analysis that yields a closed form representation of the response in terms of the complex eigenmode properties. The continuous fuzzy structure is shown not to display the transfer of energy between the master structure and the substructure that was exhibited by the discrete fuzzy structure, apparently because of the asynchronous motion of the attachment points resulting from the spatial variability of the beam’s motion. The vibration absorber effect for harmonic excitation is only obtained for the heavy damping in the case of a beam.
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Doddihal, Preeti, Dennis Kawa, Douglas Scarth, and Yu Chen. "Finite Element Verification of Engineering Equations for Prediction of Structural Strength of Annulus Spacers in CANDU Nuclear Reactors." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93671.
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Abstract The core of a CANDU (CANada Deuterium Uranium) pressurized heavy water reactor includes several hundred horizontal fuel channels that pass through a calandria vessel containing the heavy water moderator. In each fuel channel, annulus spacers are used to maintain the gap between the cold calandria tube and the hot pressure tube, a pressurized vessel containing the nuclear fuel in contact with heavy water coolant. In order to carry the loads between the pressure tube and calandria tube, the annulus spacers are required to possess adequate structural strength throughout the operating life of the reactor. The Inconel X-750 spacers used in some reactor units are susceptible to irradiation induced degradation. As irradiation fluence increases with operating time, material embrittlement has been observed due to helium bubble formation in the X-750 spacer material. An engineering approach for assessing the structural strength of CANDU annulus spacers has been recently developed. When the ductility of the material is relatively low, the region susceptible to fracture under applied tensile stress may be adequately idealized as a strip-yield process zone surrounded by elastic material and associated with restraining stress. The engineering approach is based on applying the strip-yield process zone methodology to fracture at a nominally smooth surface. Finite element modeling was undertaken to simulate the strip-yield based fracture process zone. The finite element analyses and results are presented in this paper. The finite element results verify the engineering equations developed to assess the structural strength of annulus spacers.
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Huang, Desheng, Yunlong Li, and Daoyong Yang. "Phase Behaviour and Physical Properties of Dimethyl Ether DME/CO2/Water/Heavy Oil Systems under Reservoir Conditions." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206171-ms.
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Abstract In this paper, techniques have been developed to quantify phase behaviour and physical properties including phase boundaries, swelling factors, and phase volumes for reservoir fluids containing polar components from both experimental and theoretical aspects. Experimentally, a total of five pressure-volume-temperature (PVT) experiments including three sets of DME/CO2/heavy oil systems and two sets of DME/CO2/water/heavy oil systems have been carried out to measure saturation pressures, phase volumes, and swelling factors by using a versatile PVT setup. Theoretically, the modified Peng-Robinson equation of state (PR EOS) incorporated with the Huron-Vidal mixing rule and the Péneloux volume-translation strategy is employed as the thermodynamic model to perform phase equilibrium calculations. It is observed that the experimentally measured saturation pressures of DME/CO2/water/heavy oil mixtures are higher than those of DME/CO2/heavy oil mixtures at the same temperature and same molar ratio of solvents and heavy oil, owing to the fact that more water molecules can be evaporated into vapour phase. The binary interaction parameters (BIPs) between DME/heavy oil and CO2/DME pair, which are obtained by matching the measured saturation pressures of DME/CO2/heavy oil mixtures, work well for DME/CO2/heavy oil mixtures in the presence and absence of water. In addition, a swelling effect of heavy oil can be enhanced by adding the DME and CO2 mixtures compared to only DME or CO2. The new model developed in this work is capable of accurately reproducing the experimentally measured multiphase boundaries, swelling factors, phase volumes with a root-mean-squared relative error (RMSRE) of 4.68%, 0.71%, and 9.35%, respectively, indicating that it can provide fundamental data for simulating, designing, and optimizing the hybrid solvent-thermal recovery processes for heavy oil reservoirs.
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Higashiyama, S., I. Ohkubo, H. Ishiguro, and M. Sasaki. "A NEW FUNCTION OF HUMAN KININOGENS: THE AMINO-TERMINAL REGION OF DOMAIN 1 INVOLVES AN EF HAND-LIKE STRACTURE FOR METAL BINDING." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642851.
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Two types of kininogens in mammalian plasma, high molecular weight (HMW) and low molecular weight (LMW) kininogens, are the precursors of kinin. Especially, HMW kininogen circulates in the plasma as a complex with prekallikrein and factor XI, and functions as a cofactor in the initial phase reactions of intrinsic blood coagulation cascade. Recently, it has been found that the kininogens have inhibitory activity toward cysteine proteinases. The heavy chain portion, which is identical for HMW and LMW kininogens, is composed of three domains, domain 1, 2 and 3. Each the domain 2 and 3 has a reactive site as a cysteine proteinase inhibitor. However, physiological function of domain 1 remains still unknown. By using the antibody recognizing the interaction between HMW kininogen and Ca2+ (anti-HMW kininogen-Ca2+ antibody) as a probe, we newly found the Ca2+ binding site in the domain 1.Anti-HMW kininogen-Ca2+ antibody was isolated from anti-HMW kininogen antiserum as an antibody which bound to a HMW kininogen-Sepharose column equilibrated with 40 mM Tris-HCl buffer, pH 7.5, containing 1.0 M NaCl and 1 mM CaCl2, and was eluted with 3 mM EDTA. Resulting from the characterization by ELISA, this antibody specifically recognized the CB-1 region (CNBr-cleavage fragment 1: 1-160 amino acid sequence) of the heavy chain of kininogen molecules in the presence of Ca2+ or Mg2+. Furthermore, circular dichroism (CD) experiments showed that the conformational changes of HMW kininogen and heavy chain were induced by the addition of metal ions such as Ca2+ or Mg2+, and that this change was due to the conformational change of the CB-1 region. The dissociation constant (Kd) for heavy chain measured by Ca2+ titration analysis by CD at 214 nm was found to be 0.33 ± 0.09 mM. The number of Ca2+ binding sites of heavy chain calculated from Hill plot was 1.15 ± 0.04. The EF handlike structure found in the amino-terminal portion of the heavy chain of kininogen molecules strongly supported the above data. This indicates a possibility that kininogens play an important role as a Ca2+ binding protein.
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Zhang, Aimin, and Yalun Kang. "Design of U3Si2-Al Plate-Type Fuel Element for China Advanced Research Reactor." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29231.
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China Advanced Research Reactor (CARR), which will be critical in China Institute of Atomic Energy (CIAE) in 2010, is a multipurpose, high neutron flux and tank-type (inverse neutron trap) reactor with compact core. Its nominal reactor power is 60MW and the maximum thermal neutron flux is about 8.0×1014n/cm2·s in heavy water tank. It has a cylindrical core having a diameter of about 450mm and a height of 850mm. The CARR’s core consists of seventeen plate-type standard fuel elements and four follower fuel elements, initially loaded with 10.97 kg of 235U. The fuel element has been designed with U3S2-Al dispersion containing 235U of (19.75±0.20)wt.% low enriched uranium (LEU) and having a density of 4.3gU/cm3. The aluminum alloy is used as the cladding. There are twenty-one and seventeen fuel plates in the standard and follower fuel element, respectively. There are specific requirements for design of the fuel element and strict limitation for the operation parameters due to the high heat flux and high velocity of coolant in CARR. Irradiation test of fuel element had been carried out at fuel element power of 3.1±20%MW at Russia MIR reactor. Average burnup of fuel element is up to 40%. This paper deals with the detailed design of fuel element for CARR, out-pile and in-pile test projects, including selection of fuel and structure material, description of element structure, miniplates and fuel element irradiation experiment, measurement of properties of fuel plate, fabrication of fuel element and test results.
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Booth, Martin, and Michael Martin. "Use of the Extended Finite Element Method in the Assessment of Delayed Hydride Cracking." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63156.
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Zirconium alloys, as used in water-cooled nuclear reactors, are susceptible to a time-dependent failure mechanism known as Delayed Hydride Cracking, or DHC. Corrosion of zirconium alloy in the presence of water generates hydrogen that subsequently diffuses through the metallic structure in response to concentration, temperature and hydrostatic stress gradients. As such, regions of increased hydrogen concentration develop at stress concentrating features, leading to zirconium hydride precipitation. Regions containing zirconium hydride are brittle and prone to failure if plant transient loads are sufficient. This paper demonstrates the application of the Extended Finite Element Method, or XFEM, to the assessment of the DHC susceptibility of stress concentrating features, typical of those considered in the structural integrity assessment of heavy water pressure tube reactors. The method enables the calculation of a DHC threshold load. This paper builds on the process-zone approach that is currently used to provide the industry-standard DHC assessment of zirconium alloy pressure tubes and also recent developments that have extended the application of the process-zone approach to arbitrary geometries by the use of finite element cohesive-zone analysis. In the standard cohesive-zone approach, regions of cohesive elements are situated in discrete locations where the formation of zirconium hydride is anticipated. In contrast, the use of XFEM based cohesive formulations removes the requirement to define cohesive zones a priori, thereby allowing the assessment of geometries in which the location of hydride material is not known.
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Kondo, Kunio, Yuji Arai, Hiroyuki Hirata, Masahiko Hamada, Keisuke Hitoshio, Nobuyuki Hisamune, and Tsuneo Murase. "Development of High Strength Heavy Wall Seamless Pipes of X80–X100 Grade for Ultra-Deep Water Application." In 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64079.
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This paper describes the development of high strength heavy wall seamless pipes of X80 to X100 grade for ultra-deep water application. Steel pipes with higher strength generally tend to have low fracture toughness either in pipe body or in weld joint and low weldability. Therefore, improvement of fracture toughness and weldability are particularly important with respect to development of higher strength seamless pipes. Metallurgical research in laboratory test was carried out and the effect of microstructure of quenched and tempered steel on strength and toughness was particularly investigated. As a result uniform lower bainite phase containing no or minimized coarse martensite-austenite (M-A) constituent at a quenched condition is suitable microstructure to perform high strength and high fracture toughness after tempering. The steel having such microstructure showed excellent performance even in the high strength grade of X100. Lowering a transformation temperature from austenite phase to bainite phase during quenching process is effective to obtain suitable microstructure by adding and controlling alloy elements such as Mn, Cr, Mo. In order to suppress an increase in carbon equivalent as Pcm value by addition of alloy element, lowering content of carbon is necessary. As a consequence of the low Pcm value mitigation of hardening in coarse grain heat affected zone (HAZ) and good toughness were confirmed by welding tests. A trial production of the developed steel based on a new metallurgical design mentioned above was conducted by applying inline heat treatment process in medium-size seamless mill. In conjunction with tremendously rapid cooling system of inline heat treatment facility the seamless pipes of the trial production achieve grades X80 of 40 mm wall thickness and X80 to X100 grades of 20 mm WT by changing tempering temperature. A good combination of high strength and good fracture toughness was confirmed.
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Song, Mingda, Weiqiang Wang, Huaixiang Cao, Lixin Wang, and Bo Zhang. "Multilayer Urea Reactor Safety Evaluation Based on Acoustic Emission Examination." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78135.
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Safety evaluation of urea reactors containing defects was studied based on acoustic emission examination and subsequent dissection. First, acoustic emission examination was conducted in the process of pressure testing during the hydro test and the existed defects of the urea reactor were detected and comprehensively evaluated. Second, the dissection results of the multilayer urea reactor confirmed that the acoustic emission source locations were heavy weld radial expansion cracks. Third, crack stress intensity factors were calculated in accordance with the finite element analysis results and actual crack sizes which were acquired during urea reactor dissection. Based on the crack stress intensity factors, the remaining life of the multilayer urea reactors can be estimated during the acoustic emission testing process in accordance with the acoustic emission source location appearance pressures.
Reports on the topic "Heavy Element Containing Molecules"
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Marino, Maria, M. and Walter C. Ermler. Reliable Electronic Structure Calculations for Heavy Element Chemistry: Molecules Containing Actinides, Lanthanides, and Transition Metals. Office of Scientific and Technical Information (OSTI), January 2006. http://dx.doi.org/10.2172/875418.
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Diel, B. N. Design and Construction of Main Group Element-Containing Molecules and Molecule-Derived Materials With Unusual Electronic, Optical, and Magnetic Properties. Office of Scientific and Technical Information (OSTI), August 2004. http://dx.doi.org/10.2172/830008.
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