WorldWideScience

Sample records for inner-sphere two-electron reduction

  1. Heating-induced inner-sphere substitution and reduction-oxidation reactions of the solid phenanthroline containing cobalt (2) and cobalt (3) complexes

    International Nuclear Information System (INIS)

    Palade, D.M.

    1996-01-01

    The results of the differential thermal and thermogravimetric analyses of solid phenanthroline-containing complexes of cobalt (2) and cobalt (3) in the atmosphere of the air have been analyzed. Mechanism of redox reactions occurring when cobalt (3) complexes are heated has been discussed. It is shown that some of gaseous products of the redox processes appear as a result of secondary reactions and not the processes of the ligands oxidation by Co 3+ . The influence of certain inner-sphere and coordinated anions (of I, inclusively) on cobalt (3) complexes behaviour during heating has been considered

  2. Evidence for Single Metal Two Electron Oxidative Addition and Reductive Elimination at Uranium

    OpenAIRE

    Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; Mcinnes, Eric; Tuna, Floriana; Wooles, Ashley; Maron, Laurent; Liddle, Stephen

    2017-01-01

    Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here, we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido compl...

  3. Performance Limits of Photoelectrochemical CO2 Reduction Based on Known Electrocatalysts and the Case for Two-Electron Reduction Products

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard; Seger, Brian

    2016-01-01

    Solar-drivenreduction of CO2 to solar fuels as an alternative to H2 via water splitting is an intriguing proposition. We modelthe solar-to-fuel (STF) efficiencies using realistic parameters basedon recently reported CO2 reduction catalysts with a highperformance tandem photoabsorber structure. CO...... due to excessiveoverpotentials and poor selectivity. This work considers breakingup the multielectron reduction pathway into individually optimized,separate two-electron steps as a way forward....

  4. Evidence for single metal two electron oxidative addition and reductive elimination at uranium.

    Science.gov (United States)

    Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; McInnes, Eric J L; Tuna, Floriana; Wooles, Ashley J; Maron, Laurent; Liddle, Stephen T

    2017-12-01

    Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition. Thermolysis of this complex promotes extrusion of azobenzene, where H-/D-isotopic labelling finds no isotopomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive elimination has occurred. Though not optimally balanced in this case, this work presents evidence that classical d-block redox chemistry can be performed reversibly by f-block metals, and that uranium can thus mimic elementary transition metal reactivity, which may lead to the discovery of new f-block catalysis.

  5. Inertial waves in a spherical shell induced by librations of the inner sphere: experimental and numerical results

    Energy Technology Data Exchange (ETDEWEB)

    Koch, S; Harlander, U; Egbers, C [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology Cottbus, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Hollerbach, R, E-mail: uwe.harlander@tu-cottbus.de [Institute of Geophysics, ETH Zuerich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland)

    2013-06-15

    We begin with an experimental investigation of the flow induced in a rotating spherical shell. The shell globally rotates with angular velocity {Omega}. A further periodic oscillation with angular velocity 0 Less-Than-Or-Slanted-Equal-To {omega} Less-Than-Or-Slanted-Equal-To 2{Omega}, a so-called longitudinal libration, is added on the inner sphere's rotation. The primary response is inertial waves spawned at the critical latitudes on the inner sphere, and propagating throughout the shell along inclined characteristics. For sufficiently large libration amplitudes, the higher harmonics also become important. Those harmonics whose frequencies are still less than 2{Omega} behave as inertial waves themselves, propagating along their own characteristics. The steady component of the flow consists of a prograde zonal jet on the cylinder tangent to the inner sphere and parallel to the axis of rotation, and increases with decreasing Ekman number. The jet becomes unstable for larger forcing amplitudes as can be deduced from the preliminary particle image velocimetry observations. Finally, a wave attractor is experimentally detected in the spherical shell as the pattern of largest variance. These findings are reproduced in a two-dimensional numerical investigation of the flow, and certain aspects can be studied numerically in greater detail. One aspect is the scaling of the width of the inertial shear layers and the width of the steady jet. Another is the partitioning of the kinetic energy between the forced wave, its harmonics and the mean flow. Finally, the numerical simulations allow for an investigation of instabilities, too local to be found experimentally. For strong libration amplitudes, the boundary layer on the inner sphere becomes unstable, triggering localized Goertler vortices during the prograde phase of the forcing. This instability is important for the transition to turbulence of the spherical shell flow. (paper)

  6. Inner-Sphere versus Outer-Sphere Coordination of BF4– in a NHC-Gold(I) Complex

    KAUST Repository

    Veenboer, Richard M. P.

    2017-07-20

    The role of counterions in chemistry mediated by gold complexes stretches much further than merely providing charge balance to cationic gold species. Interplay between their basicities and coordination strengths influences interactions with both the gold center and substrates in catalysis. Actual monogold(I) active species are generally believed to be monocoordinated species, formed from the abstraction or the decoordination of a second ligand from precursor complexes, but only a small amount of experimental evidence exists to underpin the existence of these transient species. The formation of a bench-stable neutral IPrCl-gold(I) tetrafluoroborate complex is reported herein. Experimental studies by X-ray diffraction analysis and NMR spectroscopy and theoretical studies by DFT calculations were conducted to determine the composition, structure, and behavior of this complex. The absence of an auxiliary ligand resulted in inner-sphere coordination of the counterion in the solid state. In solution, an equilibrium between two conformations was found with the counterion occupying inner-sphere and outer-sphere positions, respectively. Stoichiometric and catalytic reactivity studies with the tetrafluoroborate complex have been conducted. These confirmed the lability of the inner-sphere coordinating counterion that gives the IPrCl-gold(I) fragment behavior similar to that of related systems.

  7. Controllable Electrochemical Activities by Oxidative Treatment toward Inner-Sphere Redox Systems at N-Doped Hydrogenated Amorphous Carbon Films

    Directory of Open Access Journals (Sweden)

    Yoriko Tanaka

    2012-01-01

    Full Text Available The electrochemical activity of the surface of Nitrogen-doped hydrogenated amorphous carbon thin films (a-CNH, N-doped DLC toward the inner sphere redox species is controllable by modifying the surface termination. At the oxygen plasma treated N-doped DLC surface (O-DLC, the surface functional groups containing carbon doubly bonded to oxygen (C=O, which improves adsorption of polar molecules, were generated. By oxidative treatment, the electron-transfer rate for dopamine (DA positively charged inner-sphere redox analyte could be improved at the N-doped DLC surface. For redox reaction of 2,4-dichlorophenol, which induces an inevitable fouling of the anode surface by forming passivating films, the DLC surfaces exhibited remarkably higher stability and reproducibility of the electrode performance. This is due to the electrochemical decomposition of the passive films without the interference of oxygen evolution by applying higher potential. The N-doped DLC film can offer benefits as the polarizable electrode surface with the higher reactivity and higher stability toward inner-sphere redox species. By making use of these controllable electrochemical reactivity at the O-DLC surface, the selective detection of DA in the mixed solution of DA and uric acid could be achieved.

  8. Inner-Sphere versus Outer-Sphere Coordination of BF4– in a NHC-Gold(I) Complex

    KAUST Repository

    Veenboer, Richard M. P.; Collado, Alba; Dupuy, Sté phanie; Lebl, Tomas; Falivene, Laura; Cavallo, Luigi; Cordes, David B.; Slawin, Alexandra M. Z.; Cazin, Catherine S. J.; Nolan, Steven P.

    2017-01-01

    The role of counterions in chemistry mediated by gold complexes stretches much further than merely providing charge balance to cationic gold species. Interplay between their basicities and coordination strengths influences interactions with both the gold center and substrates in catalysis. Actual monogold(I) active species are generally believed to be monocoordinated species, formed from the abstraction or the decoordination of a second ligand from precursor complexes, but only a small amount of experimental evidence exists to underpin the existence of these transient species. The formation of a bench-stable neutral IPrCl-gold(I) tetrafluoroborate complex is reported herein. Experimental studies by X-ray diffraction analysis and NMR spectroscopy and theoretical studies by DFT calculations were conducted to determine the composition, structure, and behavior of this complex. The absence of an auxiliary ligand resulted in inner-sphere coordination of the counterion in the solid state. In solution, an equilibrium between two conformations was found with the counterion occupying inner-sphere and outer-sphere positions, respectively. Stoichiometric and catalytic reactivity studies with the tetrafluoroborate complex have been conducted. These confirmed the lability of the inner-sphere coordinating counterion that gives the IPrCl-gold(I) fragment behavior similar to that of related systems.

  9. Competition Between Co(NH3)63+ and Inner Sphere Mg2+ Ions in the HDV Ribozyme

    Science.gov (United States)

    Gong, Bo; Chen, Jui-Hui; Bevilacqua, Philip C.; Golden, Barbara L.; Carey, Paul R.

    2009-01-01

    Divalent cations play critical structural and functional roles in many RNAs. While the hepatitis delta virus (HDV) ribozyme can undergo self-cleavage in the presence of molar concentrations of monovalent cations, divalent cations such as Mg2+ are required for efficient catalysis under physiological conditions. Moreover, the cleavage reaction can be inhibited with Co(NH3)63+, an analog of Mg(H2O)62+. Here, the binding of Mg2+ and Co(NH3)63+ to the HDV ribozyme are studied by Raman microscopic analysis of crystals. Raman difference spectra acquired at different metal ion conditions reveal changes in the ribozyme. When Mg2+ alone is introduced to the ribozyme, inner sphere coordination of Mg(H2O)x2+ (x≤5) to non-bridging PO2− oxygen, and changes in base stretches and phosphodiester group conformation are observed. In addition, binding of Mg2+ induces deprotonation of a cytosine assigned to the general acid C75, consistent with solution studies. When Co(NH3)63+ alone is introduced, deprotonation of C75 is again observed, as are distinctive changes in base vibrational ring modes and phosphodiester backbone conformation. In contrast to Mg2+ binding, Co(NH3)63+ binding does not perturb PO2− group vibrations, consistent with its ability to make only outer sphere contacts. Surprisingly, competitive binding studies reveal that Co(NH3)63+ ions displace some inner sphere-coordinated magnesium species, including ions coordinated to PO2− groups or the N7 of a guanine, likely G1 at the active site. These observations contrast with the tenet that Co(NH3)63+ ions displace only outer sphere magnesium ions. Overall, our data support two classes of inner sphere Mg2+-PO2− binding sites: sites that Co(NH3)63+ can displace, and others it cannot. PMID:19888753

  10. In situ spectroscopic identification of neptunium(V) inner-sphere complexes on the hematite-water interface.

    Science.gov (United States)

    Müller, Katharina; Gröschel, Annett; Rossberg, André; Bok, Frank; Franzen, Carola; Brendler, Vinzenz; Foerstendorf, Harald

    2015-02-17

    Hematite plays a decisive role in regulating the mobility of contaminants in rocks and soils. The Np(V) reactions at the hematite-water interface were comprehensively investigated by a combined approach of in situ vibrational spectroscopy, X-ray absorption spectroscopy and surface complexation modeling. A variety of sorption parameters such as Np(V) concentration, pH, ionic strength, and the presence of bicarbonate was considered. Time-resolved IR spectroscopic sorption experiments at the iron oxide-water interface evidenced the formation of a single monomer Np(V) inner-sphere sorption complex. EXAFS provided complementary information on bidentate edge-sharing coordination. In the presence of atmospherically derived bicarbonate the formation of the bis-carbonato inner-sphere complex was confirmed supporting previous EXAFS findings.1 The obtained molecular structure allows more reliable surface complexation modeling of recent and future macroscopic data. Such confident modeling is mandatory for evaluating water contamination and for predicting the fate and migration of radioactive contaminants in the subsurface environment as it might occur in the vicinity of a radioactive waste repository or a reprocessing plant.

  11. Single-Step versus Stepwise Two-Electron Reduction of Polyarylpyridiniums: Insights from the Steric Switching of Redox Potential Compression

    Czech Academy of Sciences Publication Activity Database

    Fortage, J.; Peltier, C.; Perruchot, Ch.; Takemoto, Y.; Teki, Y.; Bedioui, F.; Marvand, V.; Dupeyre, G.; Pospíšil, Lubomír; Adamo, C.; Hromadová, Magdaléna; Ciofini, I.; Lainé, P. P.

    2012-01-01

    Roč. 134, č. 5 (2012), s. 2691-2705 ISSN 0002-7863 Institutional research plan: CEZ:AV0Z40400503 Keywords : FUNCTIONALIZED TERPYRIDYL LIGANDS * GATED PHOTOINDUCED PROCESSES * ONE-ELECTRON REDUCTION Subject RIV: CG - Electrochemistry Impact factor: 10.677, year: 2012

  12. Inner-sphere, outer-sphere and ternary surface complexes: a TRLFS study of the sorption process of europium(III) onto smectite

    International Nuclear Information System (INIS)

    Stumpf, Th.; Fanghaenel, Th.; Bauer, A.; Kim, J.I.

    2002-01-01

    The surface sorption process of Eu(III) onto smectite was investigated by TRLFS in the trace concentration range. With increasing pH the formation of an inner-sphere Eu(III) surface complex was observed. The differences in the spectra and the fluorescence emission lifetimes of the surface sorbed Eu(III) in presence and absence of carbonate indicate the formation of ternary clay/Eu(III)/carbonate complexes /1/. (orig.)

  13. Two electron Rydberg states

    International Nuclear Information System (INIS)

    Cooke, W.E.

    1981-01-01

    This paper addresses the study of two-electron Rydberg atoms. With Multichannel Quantum Defect Theory (MQDT), there is a technique for characterizing a spectra in terms of a small number of parameters. A survey of some important effects specific to two-electon Rydberg states, using primarily the alkaline earth atoms for examples, is made. The remainder of the paper deals with a discussion of the electron-electron interaction, including some of the basic points of MQDT. Energy exchange between two electrons is also addressed

  14. In situ spectroscopic evidence for neptunium(V)-carbonate inner-sphere and outer-sphere ternary surface complexes on hematite surfaces.

    Science.gov (United States)

    Arai, Yuji; Moran, P B; Honeyman, B D; Davis, J A

    2007-06-01

    Np(V) surface speciation on hematite surfaces at pH 7-9 under pC2 = 10(-3.45) atm was investigated using X-ray absorption spectroscopy (XAS). In situ XAS analyses suggest that bis-carbonato inner-sphere and tris-carbonato outer-sphere ternary surface species coexist at the hematite-water interface at pH 7-8.8, and the fraction of outer-sphere species gradually increases from 27 to 54% with increasing pH from 7 to 8.8. The results suggest that the heretofore unknown Np(V)-carbonato ternary surface species may be important in predicting the fate and transport of Np(V) in the subsurface environment down gradient of high-level nuclear waste respositories.

  15. inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    Energy Technology Data Exchange (ETDEWEB)

    Ridley, Mora K. [Texas Tech University, Lubbock; Hiemstra, T [Oak Ridge National Laboratory (ORNL); Van Riemsdijk, Willem H. [Wageningen University and Research Centre, The Netherlands; Machesky, Michael L. [Illinois State Water Survey, Champaign, IL

    2009-01-01

    Acid base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in principle does not require a molecular picture. The models are typically calibrated to relatively simple solid-electrolyte solution pairs and may provide poor descriptions of complex multicomponent mineral aqueous solutions, including those found in natural environments. Surface complexation models may be improved by incorporating molecular-scale surface structural information to constrain the modeling efforts. Here, we apply a concise, molecularly-constrained surface complexation model to a diverse suite of surface titration data for rutile and thereby begin to address the complexity of multi-component systems. Primary surface charging curves in NaCl, KCl, and RbCl electrolyte media were fit simultaneously using a charge distribution (CD) and multisite complexation (MUSIC) model [Hiemstra T. and Van Riemsdijk W. H. (1996) A surface structural approach to ion adsorption: the charge distribution (CD) model. J. Colloid Interf. Sci. 179, 488 508], coupled with a Basic Stern layer description of the electric double layer. In addition, data for the specific interaction of Ca2+ and Sr2+ with rutile, in NaCl and RbCl media, were modeled. In recent developments, spectroscopy, quantum calculations, and molecular simulations have shown that electrolyte and divalent cations are principally adsorbed in various inner-sphere configurations on the rutile 110 surface [Zhang Z., Fenter P., Cheng L., Sturchio N. C., Bedzyk M. J., Pr edota M., Bandura A., Kubicki J., Lvov S. N., Cummings P. T., Chialvo A. A., Ridley M. K., Be ne zeth P., Anovitz L., Palmer D. A., Machesky M. L. and Wesolowski D. J. (2004) Ion adsorption at the rutile water interface: linking molecular and macroscopic

  16. Inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    Science.gov (United States)

    Ridley, Moira K.; Hiemstra, Tjisse; van Riemsdijk, Willem H.; Machesky, Michael L.

    2009-04-01

    Acid-base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in principle does not require a molecular picture. The models are typically calibrated to relatively simple solid-electrolyte solution pairs and may provide poor descriptions of complex multi-component mineral-aqueous solutions, including those found in natural environments. Surface complexation models may be improved by incorporating molecular-scale surface structural information to constrain the modeling efforts. Here, we apply a concise, molecularly-constrained surface complexation model to a diverse suite of surface titration data for rutile and thereby begin to address the complexity of multi-component systems. Primary surface charging curves in NaCl, KCl, and RbCl electrolyte media were fit simultaneously using a charge distribution (CD) and multisite complexation (MUSIC) model [Hiemstra T. and Van Riemsdijk W. H. (1996) A surface structural approach to ion adsorption: the charge distribution (CD) model. J. Colloid Interf. Sci. 179, 488-508], coupled with a Basic Stern layer description of the electric double layer. In addition, data for the specific interaction of Ca 2+ and Sr 2+ with rutile, in NaCl and RbCl media, were modeled. In recent developments, spectroscopy, quantum calculations, and molecular simulations have shown that electrolyte and divalent cations are principally adsorbed in various inner-sphere configurations on the rutile 1 1 0 surface [Zhang Z., Fenter P., Cheng L., Sturchio N. C., Bedzyk M. J., Předota M., Bandura A., Kubicki J., Lvov S. N., Cummings P. T., Chialvo A. A., Ridley M. K., Bénézeth P., Anovitz L., Palmer D. A., Machesky M. L. and Wesolowski D. J. (2004) Ion adsorption at the rutile-water interface: linking molecular and macroscopic

  17. Two-Electron Transfer Pathways.

    Science.gov (United States)

    Lin, Jiaxing; Balamurugan, D; Zhang, Peng; Skourtis, Spiros S; Beratan, David N

    2015-06-18

    The frontiers of electron-transfer chemistry demand that we develop theoretical frameworks to describe the delivery of multiple electrons, atoms, and ions in molecular systems. When electrons move over long distances through high barriers, where the probability for thermal population of oxidized or reduced bridge-localized states is very small, the electrons will tunnel from the donor (D) to acceptor (A), facilitated by bridge-mediated superexchange interactions. If the stable donor and acceptor redox states on D and A differ by two electrons, it is possible that the electrons will propagate coherently from D to A. While structure-function relations for single-electron superexchange in molecules are well established, strategies to manipulate the coherent flow of multiple electrons are largely unknown. In contrast to one-electron superexchange, two-electron superexchange involves both one- and two-electron virtual intermediate states, the number of virtual intermediates increases very rapidly with system size, and multiple classes of pathways interfere with one another. In the study described here, we developed simple superexchange models for two-electron transfer. We explored how the bridge structure and energetics influence multielectron superexchange, and we compared two-electron superexchange interactions to single-electron superexchange. Multielectron superexchange introduces interference between singly and doubly oxidized (or reduced) bridge virtual states, so that even simple linear donor-bridge-acceptor systems have pathway topologies that resemble those seen for one-electron superexchange through bridges with multiple parallel pathways. The simple model systems studied here exhibit a richness that is amenable to experimental exploration by manipulating the multiple pathways, pathway crosstalk, and changes in the number of donor and acceptor species. The features that emerge from these studies may assist in developing new strategies to deliver multiple

  18. Enhanced catalytic four-electron dioxygen (O2) and two-electron hydrogen peroxide (H2O2) reduction with a copper(II) complex possessing a pendant ligand pivalamido group.

    Science.gov (United States)

    Kakuda, Saya; Peterson, Ryan L; Ohkubo, Kei; Karlin, Kenneth D; Fukuzumi, Shunichi

    2013-05-01

    A copper complex, [(PV-tmpa)Cu(II)](ClO4)2 (1) [PV-tmpa = bis(pyrid-2-ylmethyl){[6-(pivalamido)pyrid-2-yl]methyl}amine], acts as a more efficient catalyst for the four-electron reduction of O2 by decamethylferrocene (Fc*) in the presence of trifluoroacetic acid (CF3COOH) in acetone as compared with the corresponding copper complex without a pivalamido group, [(tmpa)Cu(II)](ClO4)2 (2) (tmpa = tris(2-pyridylmethyl)amine). The rate constant (k(obs)) of formation of decamethylferrocenium ion (Fc*(+)) in the catalytic four-electron reduction of O2 by Fc* in the presence of a large excess CF3COOH and O2 obeyed first-order kinetics. The k(obs) value was proportional to the concentration of catalyst 1 or 2, whereas the k(obs) value remained constant irrespective of the concentration of CF3COOH or O2. This indicates that electron transfer from Fc* to 1 or 2 is the rate-determining step in the catalytic cycle of the four-electron reduction of O2 by Fc* in the presence of CF3COOH. The second-order catalytic rate constant (k(cat)) for 1 is 4 times larger than the corresponding value determined for 2. With the pivalamido group in 1 compared to 2, the Cu(II)/Cu(I) potentials are -0.23 and -0.05 V vs SCE, respectively. However, during catalytic turnover, the CF3COO(-) anion present readily binds to 2 shifting the resulting complex's redox potential to -0.35 V. The pivalamido group in 1 is found to inhibit anion binding. The overall effect is to make 1 easier to reduce (relative to 2) during catalysis, accounting for the relative k(cat) values observed. 1 is also an excellent catalyst for the two-electron two-proton reduction of H2O2 to water and is also more efficient than is 2. For both complexes, reaction rates are greater than for the overall four-electron O2-reduction to water, an important asset in the design of catalysts for the latter.

  19. Spectroscopy of two-electron atoms

    International Nuclear Information System (INIS)

    Desesquelles, J.

    1988-01-01

    Spectroscopy of heliumlike ions is discussed putting emphasis on mid and high Z atoms. Experimental aspects of ion charge, excitation production, clean spectra, and precise wavelength measurement are detailed. Recent results obtained at several laboratories including Lyon, Argonne, Notre-Dame, Oxford, Berkeley, Darmstadt, Paris, are used to test the QED contributions and higher order relativistic corrections to two-electron atom energies. (orig.)

  20. Timing analysis of two-electron photoemission

    International Nuclear Information System (INIS)

    Kheifets, A S; Ivanov, I A; Bray, Igor

    2011-01-01

    We predict a significant delay of two-electron photoemission from the helium atom after absorption of an attosecond XUV pulse. We establish this delay by solving the time-dependent Schroedinger equation and by subsequently tracing the field-free evolution of the two-electron wave packet. This delay can also be related to the energy derivative of the phase of the complex double-photoionization (DPI) amplitude which we evaluate by using the convergent close-coupling method. Our observations indicate that future attosecond time delay measurements on DPI of He can provide information on the absolute quantum phase and elucidate various mechanisms of this strongly correlated ionization process. (fast track communication)

  1. Stark shifting two-electron quantum dot

    International Nuclear Information System (INIS)

    Dineykhan, M.; Zhaugasheva, S.A.; Duysebaeva, K.S.

    2003-01-01

    Advances in modern technology make it possible to create semiconducting nano-structures (quantum dot) in which a finite number of electrons are 'captured' in a bounded volume. A quantum dot is associated with a quantum well formed at the interface, between two finite-size semiconductors owing to different positions of the forbidden gaps on the energy scale in these semiconductors. The possibility of monitoring and controlling the properties of quantum dots attracts considerable attention to these objects, as a new elemental basis for future generations of computers. The quantum-mechanical effects and image potential play a significant role in the description of the formation mechanism quantum dot, and determined the confinement potential in a two-electron quantum dot only for the spherical symmetric case. In the present talk, we considered the formation dynamics of two-electron quantum dot with violation of spherical symmetry. So, we have standard Stark potential. The energy spectrum two-electron quantum dot were calculated. Usually Stark interactions determined the tunneling phenomena between quantum dots

  2. Nonadiabatic two-electron transfer mediated by an irregular bridge

    International Nuclear Information System (INIS)

    Petrov, E.G.; Shevchenko, Ye.V.; May, V.

    2004-01-01

    Nonadiabatic two-electron transfer (TET) mediated by a linear molecular bridge is studied theoretically. Special attention is put on the case of a irregular distribution of bridge site energies as well as on the inter-site Coulomb interaction. Based on the unified description of electron transfer reactions [J. Chem. Phys. 115 (2001) 7107] a closed set of kinetic equations describing the TET process is derived. A reduction of this set to a single exponential donor-acceptor (D-A) TET is performed together with a derivation of an overall D-A TET rate. The latter contains a contribution of the stepwise as well as of the concerted route of D-A TET. The stepwise contribution is determined by two single-electron steps each of them associated with a sequential and a superexchange pathway. A two-electron unistep superexchange transition between the D and A forms the concerted contribution to the overall rate. Both contributions are analyzed in their dependency on the bridge length. The irregular distribution of the bridge site energies as well as the influence of the Coulomb interaction facilitates the D-A TET via a modification of the stepwise and the concerted part of the overall rate. At low temperatures and for short bridges with a single or two units the concerted contribution exceeds the stepwise contribution. If the bridge contains more than two units, the stepwise contribution dominates the overall rate

  3. Natural occupation numbers in two-electron quantum rings.

    Science.gov (United States)

    Tognetti, Vincent; Loos, Pierre-François

    2016-02-07

    Natural orbitals (NOs) are central constituents for evaluating correlation energies through efficient approximations. Here, we report the closed-form expression of the NOs of two-electron quantum rings, which are prototypical finite-extension systems and new starting points for the development of exchange-correlation functionals in density functional theory. We also show that the natural occupation numbers for these two-electron paradigms are in general non-vanishing and follow the same power law decay as atomic and molecular two-electron systems.

  4. Natural occupation numbers in two-electron quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Tognetti, Vincent, E-mail: vincent.tognetti@univ-rouen.fr [Normandy Univ., COBRA UMR 6014 & FR 3038, Université de Rouen, INSA Rouen, CNRS, 1 rue Tesniére, 76821 Mont Saint Aignan, Cedex (France); Loos, Pierre-François [Research School of Chemistry, Australian National University, Canberra ACT 2601 (Australia)

    2016-02-07

    Natural orbitals (NOs) are central constituents for evaluating correlation energies through efficient approximations. Here, we report the closed-form expression of the NOs of two-electron quantum rings, which are prototypical finite-extension systems and new starting points for the development of exchange-correlation functionals in density functional theory. We also show that the natural occupation numbers for these two-electron paradigms are in general non-vanishing and follow the same power law decay as atomic and molecular two-electron systems.

  5. Fundamental Mechanistic Understanding of Electrocatalysis of Oxygen Reduction on Pt and Non-Pt Surfaces: Acid versus Alkaline Media

    Directory of Open Access Journals (Sweden)

    Nagappan Ramaswamy

    2012-01-01

    Full Text Available Complex electrochemical reactions such as Oxygen Reduction Reaction (ORR involving multi-electron transfer is an electrocatalytic inner-sphere electron transfer process that exhibit strong dependence on the nature of the electrode surface. This criterion (along with required stability in acidic electrolytes has largely limited ORR catalysts to the platinum-based surfaces. New evidence in alkaline media, discussed here, throws light on the involvement of surface-independent outer-sphere electron transfer component in the overall electrocatalytic process. This surface non-specificity gives rise to the possibility of using a wide-range of non-noble metal surfaces as electrode materials for ORR in alkaline media. However, this outer-sphere process predominantly leads only to peroxide intermediate as the final product. The importance of promoting the electrocatalytic inner-sphere electron transfer by facilitation of direct adsorption of molecular oxygen on the active site is emphasized by using pyrolyzed metal porphyrins as electrocatalysts. A comparison of ORR reaction mechanisms between acidic and alkaline conditions is elucidated here. The primary advantage of performing ORR in alkaline media is found to be the enhanced activation of the peroxide intermediate on the active site that enables the complete four-electron transfer. ORR reaction schemes involving both outer- and inner-sphere electron transfer mechanisms are proposed.

  6. Exact wave functions of two-electron quantum rings.

    Science.gov (United States)

    Loos, Pierre-François; Gill, Peter M W

    2012-02-24

    We demonstrate that the Schrödinger equation for two electrons on a ring, which is the usual paradigm to model quantum rings, is solvable in closed form for particular values of the radius. We show that both polynomial and irrational solutions can be found for any value of the angular momentum and that the singlet and triplet manifolds, which are degenerate, have distinct geometric phases. We also study the nodal structure associated with these two-electron states.

  7. Regular perturbation theory for two-electron atoms

    International Nuclear Information System (INIS)

    Feranchuk, I.D.; Triguk, V.V.

    2011-01-01

    Regular perturbation theory (RPT) for the ground and excited states of two-electron atoms or ions is developed. It is shown for the first time that summation of the matrix elements from the electron-electron interaction operator over all intermediate states can be calculated in a closed form by means of the two-particle Coulomb Green's function constructed in the Letter. It is shown that the second order approximation of RPT includes the main part of the correlation energy both for the ground and excited states. This approach can be also useful for description of two-electron atoms in external fields. -- Highlights: → We develop regular perturbation theory for the two-electron atoms or ions. → We calculate the sum of the matrix elements over all intermediate states. → We construct the two-particle Coulomb Green's function.

  8. Angular correlation in the two-electron continuum

    International Nuclear Information System (INIS)

    Kheifets, A. S.; Bray, I.

    2006-01-01

    Following absorption of a single photon, angles of simultaneous emission of two electrons from a He(n 1 S) atom become more correlated with increasing n. We find that the strength of this correlation is due to the two-electron continuum of the electron-impact ionization of the He + (ns) ion. The strength is determined by the width of the momentum profile of the ionic ns state but not the strength of the electron correlation in the He initial state. This can explain the increasing (over He) angular correlation strength found in double photoionization of targets such as Be, Ne, and H 2

  9. Bridge mediated two-electron transfer reactions: Analysis of stepwise and concerted pathways

    International Nuclear Information System (INIS)

    Petrov, E.G.; May, V.

    2004-01-01

    A theory of nonadiabatic donor (D)-acceptor (A) two-electron transfer (TET) mediated by a single regular bridge (B) is developed. The presence of different intermediate two-electron states connecting the reactant state D -- BA with the product state DBA -- results in complex multiexponential kinetics. The conditions are discussed at which a reduction to two-exponential as well as single-exponential kinetics becomes possible. For the latter case the rate K TET is calculated, which describes the bridge-mediated reaction as an effective two-electron D-A transfer. In the limit of small populations of the intermediate TET states D - B - A, DB -- A, D - BA - , and DB - A - , K TET is obtained as a sum of the rates K TET (step) and K TET (sup) . The first rate describes stepwise TET originated by transitions of a single electron. It starts at D -- BA and reaches DBA -- via the intermediate state D - BA - . These transitions cover contributions from sequential as well as superexchange reactions all including reduced bridge states. In contrast, a specific two-electron superexchange mechanism from D -- BA to DBA -- defines K TET (sup) . An analytic dependence of K TET (step) and K TET (sup) on the number of bridging units is presented and different regimes of D-A TET are studied

  10. CMS: Simulated Higgs to two jets and two electrons

    CERN Multimedia

    1997-01-01

    This track is an example of simulated data modelled for the CMS detector on the Large Hadron Collider (LHC) at CERN, which will begin taking data in 2008. Here a Higgs boson is produced which decays into two jets of hadrons and two electrons. The lines represent the possible paths of particles produced by the proton-proton collision in the detector while the energy these particles deposit is shown in blue.

  11. Electron correlation energy in confined two-electron systems

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, C.L. [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Montgomery, H.E., E-mail: ed.montgomery@centre.ed [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Sen, K.D. [School of Chemistry, University of Hyderabad, Hyderabad 500 046 (India); Thompson, D.C. [Chemistry Systems and High Performance Computing, Boehringer Ingelheim Pharamaceuticals Inc., 900 Ridgebury Road, Ridgefield, CT 06877 (United States)

    2010-09-27

    Radial, angular and total correlation energies are calculated for four two-electron systems with atomic numbers Z=0-3 confined within an impenetrable sphere of radius R. We report accurate results for the non-relativistic, restricted Hartree-Fock and radial limit energies over a range of confinement radii from 0.05-10a{sub 0}. At small R, the correlation energies approach limiting values that are independent of Z while at intermediate R, systems with Z{>=}1 exhibit a characteristic maximum in the correlation energy resulting from an increase in the angular correlation energy which is offset by a decrease in the radial correlation energy.

  12. Two Electron States in a Quantum Ring on a Sphere

    International Nuclear Information System (INIS)

    Kazaryan, Eduard M.; Shahnazaryan, Vanik A.; Sarkisyan, Hayk A.

    2014-01-01

    Two electron states in a quantum ring on a spherical surface are discussed. The problem is discussed within the frameworks of Russell–Saunders coupling scheme, that is, the spin–orbit coupling is neglected. Treating Coulomb interaction as a perturbation, the energy correction for different states is calculated. The dependence of the Coulomb interaction energy on external polar boundary angle of quantum ring is obtained. In analogue with the helium atom the concept of states exchange time is introduced, and its dependence on geometrical parameters of the ring is shown. (author)

  13. Dynamics of two-electron excitations in helium

    Energy Technology Data Exchange (ETDEWEB)

    Caldwell, C.D.; Menzel, A.; Frigo, S.P. [Univ. of Central Florida, Orlando, FL (United States)] [and others

    1997-04-01

    Excitation of both electrons in helium offers a unique window for studying electron correlation at the most basic level in an atom in which these two electrons and the nucleus form a three-body system. The authors utilized the first light available at the U-8 undulator-SGM monochromator beamline to investigate the dynamic parameters, partial cross sections, differential cross sections, and photoelectron angular distribution parameters ({beta}), with a high resolving power for the photon beam and at the highly differential level afforded by the use of their electron spectrometer. In parallel, they carried out detailed calculations of the relevant properties by a theoretical approach that is based on the hyperspherical close-coupling method. Partial photoionization cross sections {sigma}{sub n}, and photoelectron angular distributions {beta}{sub n} were measured for all possible final ionic states He{sup +}(n) in the region of the double excitations N(K,T){sup A} up to the N=5 threshold. At a photon energy bandpass of 12 meV below the thresholds N=3, 4, and 5, this level of differentiation offers the most critical assessment of the dynamics of the two-electron excitations to date. The experimental data were seen to be very well described by the most advanced theoretical calculations.

  14. Complex dynamics in planar two-electron quantum dots

    International Nuclear Information System (INIS)

    Schroeter, Sebastian Josef Arthur

    2013-01-01

    Quantum dots play an important role in a wide range of recent experimental and technological developments. In particular they are promising candidates for realisations of quantum bits and further applications in quantum information theory. The harmonically confined Hooke's atom model is experimentally verified and separates in centre-of-mass and relative coordinates. Findings that are contradictory to this separability call for an extension of the model, in particular changing the confinement potential. In order to study effects of an anharmonic confinement potential on spectral properties of planar two-electron quantum dots a sophisticated numerical approach is developed. Comparison between the Helium atom, Hooke's atom and an anharmonic potential model are undertaken in order to improve the description of quantum dots. Classical and quantum features of complexity and chaos are investigated and used to characterise the dynamics of the system to be mixed regular-chaotic. Influence of decoherence can be described by quantum fidelity, which measures the effect of a perturbation on the time evolution. The quantum fidelity of eigenstates of the system depends strongly on the properties of the perturbation. Several methods for solving the time-dependent Schrödinger equation are implemented and a high level of accuracy for long time evolutions is achieved. The concept of offset entanglement, the entanglement of harmonic models in the noninteracting limit, is introduced. This concept explains different questions raised in the literature for harmonic quantum dot models, recently. It shows that only in the groundstate the electrons are not entangled in the fermionic sense. The applicability, validity, and origin of Hund's first rule in general quantum dot models is further addressed. In fact Hund's first rule is only applicable, and in this case also valid, for one pair of singlet and triplet states in Hooke's atom. For more realistic models of two-electron quantum dots an

  15. Complex dynamics in planar two-electron quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Schroeter, Sebastian Josef Arthur

    2013-06-25

    Quantum dots play an important role in a wide range of recent experimental and technological developments. In particular they are promising candidates for realisations of quantum bits and further applications in quantum information theory. The harmonically confined Hooke's atom model is experimentally verified and separates in centre-of-mass and relative coordinates. Findings that are contradictory to this separability call for an extension of the model, in particular changing the confinement potential. In order to study effects of an anharmonic confinement potential on spectral properties of planar two-electron quantum dots a sophisticated numerical approach is developed. Comparison between the Helium atom, Hooke's atom and an anharmonic potential model are undertaken in order to improve the description of quantum dots. Classical and quantum features of complexity and chaos are investigated and used to characterise the dynamics of the system to be mixed regular-chaotic. Influence of decoherence can be described by quantum fidelity, which measures the effect of a perturbation on the time evolution. The quantum fidelity of eigenstates of the system depends strongly on the properties of the perturbation. Several methods for solving the time-dependent Schrödinger equation are implemented and a high level of accuracy for long time evolutions is achieved. The concept of offset entanglement, the entanglement of harmonic models in the noninteracting limit, is introduced. This concept explains different questions raised in the literature for harmonic quantum dot models, recently. It shows that only in the groundstate the electrons are not entangled in the fermionic sense. The applicability, validity, and origin of Hund's first rule in general quantum dot models is further addressed. In fact Hund's first rule is only applicable, and in this case also valid, for one pair of singlet and triplet states in Hooke's atom. For more realistic models of two-electron

  16. Solitary Langmuir waves in two-electron temperature plasma

    Science.gov (United States)

    Prudkikh, V. V.; Prudkikh

    2014-06-01

    Nonlinear interaction of Langmuir and ion-acoustic waves in two-electron temperature plasma is investigated. New integrable wave interaction regime was discovered, this regime corresponds to the Langmuir soliton with three-hump amplitude, propagating with a speed close to the ion-sound speed in the conditions of strong non-isothermality of electronic components. It was discovered that besides the known analytical solution in the form of one- and two-hump waves, there exists a range of solutions in the form of solitary waves, which in the form of envelope has multi-peak structure and differs from the standard profiles described by hyperbolic functions. In case of fixed plasma parameters, different group velocities correspond to the waves with different number of peaks. It is found that the Langmuir wave package contains both even and uneven numbers of oscillations. Low-frequency potential here has uneven number of peaks. Interrelation of obtained and known earlier results are also discussed.

  17. Dimensional perturbation theory for the two-electron atom

    International Nuclear Information System (INIS)

    Goodson, D.Z.

    1987-01-01

    Perturbation theory in δ = 1/D, where D is the dimensionality of space, is applied to the two-electron atom. In Chapter 1 an efficient procedure for calculating the coefficients of the perturbation series for the ground-state energy is developed using recursion relations between the moments of the coordinate operators. Results through tenth order are presented. The series is divergent, but Pade summation gives results comparable in accuracy to the best configuration-interaction calculations. The singularity structure of the Pade approximants confirms the hypothesis that the energy as a function of δ has an infinite sequence of poles on the negative real axis that approaches an essential singularity at δ = O. The essential singularity causes the divergence of the perturbation series. There are also two poles at δ = 1 that slow the asymptotic convergence of the low-order terms. In Chapter 2, various techniques are demonstrated for removing the effect of these poles, and accurate results are thereby obtained, even at very low order. In Chapter 3, the large D limit of the correlation energy (CE) is investigated. In the limit D → infinity it is only 35% smaller than at D = 3. It can be made to vanish in the limit by modifying the Hartree-Fock (HF) wavefunction. In Chapter 4, perturbation theory is applied to the Hooke's-law model of the atom. Prospects for treating more-complicated systems are briefly discussed

  18. Theoretical description of high-lying two-electrons states

    International Nuclear Information System (INIS)

    Greene, C.H.; Cavagnero, M.; Sadeghpour, H.R.

    1993-01-01

    Within the past two years, experiments on high-lying doubly-excited states in He and H- have shown spectra at energies near excited hydrogenic thresholds having principal quantum numbers in the range N=5--9. While they display some nontrivial complexities, the spectra are tremendously simpler than might be anticipated on the basis of independent electron models, in that only a small fraction of the total number of anticipated resonances are observed experimentally. Moreover, for principal quantum number N that are not too high, specifically N - , the resonance positions are described accurately by adiabatic calculations using hyperspherical coordinates and can be parametrized by a remarkably simple two-electron Rydberg formula. The observed propensity for excitation of only a small subset of the possible resonance states has been codified by several groups into approximate selection rules based on alternative (but apparently equivalent) classification schemes. Comparatively few attempts have been made at quantitative tests of the validity of these rules. The present review describes recent efforts to quantify their accuracy and limitations using R-matrix and quantum defect techniques, and Smith's delay-time matrix. Prospensity rules for exciting different degrees of freedom are found to differ greatly in their degree of validity

  19. Two-electron oxidation of cobalt phthalocyanines by thionyl chloride: Implications for lithium/thionyl chloride batteries. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, P.A.; Lever, A.B.

    1989-10-20

    Cyclic voltammetry, DPV and electronic spectroscopy are used to study the reaction between thionyl chloride and cobalt phthalocyanine. SOCl2 reacts with (Co(I)Tn Pc(2-)) and Co(II)Tn Pc(2-) to give two-electron oxidized species. Implications for Li/SOCl2 batteries are discussed. Thionyl chloride also forms a mono SOCl2 adduct with Co(II)TnPc(2-). Driving forces (Delta E values) were calculated for CoTnPc comproportionation and CoTnPc + SOCl2 reactions. Rest potential measurements of a Li/SOCl2 cells show that addition of AlCl3 stabilizes the LiCl product as LiAlCl4. A catalytic two-electron mechanism is indicated for the reduction of thionyl chloride in a Li/SOCl2/(CoTnPc,C) battery.

  20. Atomic-batched tensor decomposed two-electron repulsion integrals

    Science.gov (United States)

    Schmitz, Gunnar; Madsen, Niels Kristian; Christiansen, Ove

    2017-04-01

    We present a new integral format for 4-index electron repulsion integrals, in which several strategies like the Resolution-of-the-Identity (RI) approximation and other more general tensor-decomposition techniques are combined with an atomic batching scheme. The 3-index RI integral tensor is divided into sub-tensors defined by atom pairs on which we perform an accelerated decomposition to the canonical product (CP) format. In a first step, the RI integrals are decomposed to a high-rank CP-like format by repeated singular value decompositions followed by a rank reduction, which uses a Tucker decomposition as an intermediate step to lower the prefactor of the algorithm. After decomposing the RI sub-tensors (within the Coulomb metric), they can be reassembled to the full decomposed tensor (RC approach) or the atomic batched format can be maintained (ABC approach). In the first case, the integrals are very similar to the well-known tensor hypercontraction integral format, which gained some attraction in recent years since it allows for quartic scaling implementations of MP2 and some coupled cluster methods. On the MP2 level, the RC and ABC approaches are compared concerning efficiency and storage requirements. Furthermore, the overall accuracy of this approach is assessed. Initial test calculations show a good accuracy and that it is not limited to small systems.

  1. Electron Bifurcation: Thermodynamics and Kinetics of Two-Electron Brokering in Biological Redox Chemistry.

    Science.gov (United States)

    Zhang, Peng; Yuly, Jonathon L; Lubner, Carolyn E; Mulder, David W; King, Paul W; Peters, John W; Beratan, David N

    2017-09-19

    processes of their own. We dissect the thermodynamics and kinetics of electron bifurcation in Nfn and find that the key features of electron bifurcation are (1) spatially separated transfer pathways that diverge from a two-electron donor, (2) one thermodynamically uphill and one downhill redox pathway, with a large negative shift in the donor's reduction potential after departure of the first electron, and (3) electron tunneling and activation factors that enable bifurcation, producing a 1:1 partitioning of electrons onto the two pathways. Electron bifurcation is found in the CO 2 reducing pathways of methanogenic archaea, in the hydrogen pathways of hydrogenases, in the nitrogen fixing pathway of Fix, and in the mitochondrial charge transfer chain of complex III, cytochrome bc 1 . While crossed potentials may offer the biological advantage of producing tightly regulated high energy reactive species, neither kinetic nor thermodynamic considerations mandate crossed potentials to generate successful electron bifurcation. Taken together, the theoretical framework established here, focusing on the underpinning electron tunneling barriers and activation free energies, explains the logic of electron bifurcation that enables energy conversion and conservation in Nfn, points toward bioinspired schemes to execute multielectron redox chemistry, and establishes a roadmap for examining novel electron bifurcation networks in nature.

  2. Calculation of the two-electron Darwin term using explicitly correlated wave functions

    International Nuclear Information System (INIS)

    Middendorf, Nils; Höfener, Sebastian; Klopper, Wim; Helgaker, Trygve

    2012-01-01

    Graphical abstract: The two-electron Darwin term is computed analytically at the MP2-F12 level of theory using density fitted integrals. Highlights: ► Two-electron Darwin term computed analytically at the MP2-F12 level. ► Darwin two-electron integrals computed using density fitting techniques. ► Two-electron Darwin term dominated by singlet pair contributions. ► Much improved basis set convergence is achieved with F12 methods. ► Interference correction works well for the two-electron Darwin term. - Abstract: This article is concerned with the calculation of the two-electron Darwin term (D2). At the level of explicitly correlated second-order perturbation theory (MP2-F12), the D2 term is obtained as an analytic energy derivative; at the level of explicitly correlated coupled-cluster theory, it is obtained from finite differences. To avoid the calculation of four-center integrals, a density-fitting approximation is applied to the D2 two-electron integrals without loss of accuracy, even though the absolute value of the D2 term is typically about 0.1 mE h . Explicitly correlated methods provide a qualitatively correct description of the short-range region around the Coulomb hole, even for small orbital basis sets. Therefore, explicitly correlated wave functions remedy the otherwise extremely slow convergence of the D2 contribution with respect to the basis-set size, yielding more accurate results than those obtained by two-point basis-set extrapolation. Moreover, we show that the interference correction of Petersson’s complete-basis-set model chemistry can be used to compute a D2 basis-set correction at the MP2-F12 level to improve standard coupled-cluster singles-and-doubles results.

  3. Binding of two-electron metastable states in semiconductor quantum dots under a magnetic field

    Science.gov (United States)

    Garagiola, Mariano; Pont, Federico M.; Osenda, Omar

    2018-04-01

    Applying a strong enough magnetic field results in the binding of few-electron resonant states. The mechanism was proposed many years ago but its verification in laboratory conditions is far more recent. In this work we study the binding of two-electron resonant states. The electrons are confined in a cylindrical quantum dot which is embedded in a semiconductor wire. The geometry considered is similar to the one used in actual experimental setups. The low-energy two-electron spectrum is calculated numerically from an effective-mass approximation Hamiltonian modelling the system. Methods for binding threshold calculations in systems with one and two electrons are thoroughly studied; in particular, we use quantum information quantities to assess when the strong lateral confinement approximation can be used to obtain reliable low-energy spectra. For simplicity, only cases without bound states in the absence of an external field are considered. Under these conditions, the binding threshold for the one-electron case is given by the lowest Landau energy level. Moreover, the energy of the one-electron bounded resonance can be used to obtain the two-electron binding threshold. It is shown that for realistic values of the two-electron model parameters it is feasible to bind resonances with field strengths of a few tens of tesla.

  4. ATLAS proton-proton event containing two electrons and two muons

    CERN Multimedia

    ATLAS Collaboration

    2011-01-01

    An event with two identified muons and two identified electrons from a proton- proton collision in ATLAS. This event is consistent with coming from two Z particles decaying: one Z decays to two muons, the other to two electrons. Such events are produced by Standard Model processes without Higgs particles. They are also a possible signature for Higgs particle production, but many events must be analysed together in order to tell if there is a Higgs signal. The two muons are picked out as red tracks penetrating right through the detector. The two electrons are picked out as green tracks in the central, inner detector, matching narrow green clusters of energy in the barrel part of the calorimeters. The inset at the bottom right shows a map of the energy seen in the detector: the two big yellow spikes correspond to the two electrons.

  5. Hyperpolarizabilities of one and two electron ions under strongly coupled plasma

    International Nuclear Information System (INIS)

    Sen, Subhrangsu; Mandal, Puspajit; Kumar Mukherjee, Prasanta; Fricke, Burkhard

    2013-01-01

    Systematic investigations on the hyperpolarizabilities of hydrogen and helium like ions up to nuclear charge Z = 7 under strongly coupled plasma environment have been performed. Variation perturbation theory has been adopted to evaluate such properties for the one and two electron systems. For the two electron systems coupled Hartree-Fock theory, which takes care of partial electron correlation effects, has been utilised. Ion sphere model of the strongly coupled plasma, valid for ionic systems only, has been adopted for estimating the effect of plasma environment on the hyperpolarizability. The calculated free ion hyperpolarizability for all the systems is in good agreement with the existing data. Under confinement hyperpolarizabilities of one and two electron ions show interesting trend with respect to plasma coupling strength.

  6. Sheath and heat flow of a two-electron-temperature plasma in the presence of electron emission

    International Nuclear Information System (INIS)

    Sato, Kunihiro; Miyawaki, Fujio

    1992-01-01

    The electrostatic sheath and the heat flow of a two-electron-temperature plasma in the presence of electron emission are investigated analytically. It is shown that the energy flux is markedly enhanced to a value near the electron free-flow energy flux as a result of considerable reduction of the sheath potential due to electron emission if the fraction of hot electrons at the sheath edge is much smaller than one. If the hot- to cold-electron temperature ratio is of the order of ten and the hot electron density is comparable to the cold electron density, the action of the sheath as a thermal insulator is improved as a result of suppression of electron emission due to the space-charge effect of hot electrons. (author)

  7. Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Pepper, Michael; Kumar, Sanjeev [Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom)

    2015-11-15

    For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

  8. New method of ionization energy calculation for two-electron ions

    International Nuclear Information System (INIS)

    Ershov, D.K.

    1997-01-01

    A new method for calculation of the ionization energy of two-electron ions is proposed. The method is based on the calculation of the energy of second electron interaction with the field of an one-electron ion the potential of which is well known

  9. An exciton approach to the excited states of two electron atoms. I Formalism and interpretation

    International Nuclear Information System (INIS)

    Schipper, P.E.

    1985-01-01

    The exciton model is formally applied to a description of the excited states of two electron atoms with the explicit inclusion of exchange. The model leads to a conceptually simple framework for the discussion of the electronic properties of the archetypical atomic electron pair

  10. Are we ready to test QED in two-electron ions

    International Nuclear Information System (INIS)

    Ermolaev, A.M.

    1981-01-01

    The great improvement on the accuracy of the measured transition intervals in two-electron ions achieved recently is discussed with reference to reports of Berry (ANL) and Silver (Oxford) on the precision determination of the 2s 3 S 1 - 2p 3 P/sub J/, J = 0, and 2, intervals in the ions with intermediate Z

  11. Observation and spectroscopy of a two-electron Wigner molecule in an ultraclean carbon nanotube

    DEFF Research Database (Denmark)

    Pecker, S.; Kuemmeth, Ferdinand; Secchi, A.

    2013-01-01

    Two electrons on a string form a simple model system where Coulomb interactions are expected to play an interesting role. In the presence of strong interactions, these electrons are predicted to form a Wigner molecule, separating to the ends of the string. This spatial structure is believed to be...

  12. Two-electron Rabi oscillations in real-time time-dependent density-functional theory

    International Nuclear Information System (INIS)

    Habenicht, Bradley F.; Tani, Noriyuki P.; Provorse, Makenzie R.; Isborn, Christine M.

    2014-01-01

    We investigate the Rabi oscillations of electrons excited by an applied electric field in several simple molecular systems using time-dependent configuration interaction (TDCI) and real-time time-dependent density-functional theory (RT-TDDFT) dynamics. While the TDCI simulations exhibit the expected single-electron Rabi oscillations at a single resonant electric field frequency, Rabi oscillations in the RT-TDDFT simulations are a two-electron process. The existence of two-electron Rabi oscillations is determined both by full population inversion between field-free molecular orbitals and the behavior of the instantaneous dipole moment during the simulations. Furthermore, the Rabi oscillations in RT-TDDFT are subject to an intensity threshold of the electric field, below which Rabi oscillations do not occur and above which the two-electron Rabi oscillations occur at a broad range of frequencies. It is also shown that at field intensities near the threshold intensity, the field frequency predicted to induce Rabi oscillations by linear response TDDFT only produces detuned Rabi oscillations. Instead, the field frequency that yields the full two-electron population inversion and Rabi oscillation behavior is shown to be the average of single-electron transition frequencies from the ground S 0 state and the doubly-excited S 2 state. The behavior of the two-electron Rabi oscillations is rationalized via two possible models. The first model is a multi-photon process that results from the electric field interacting with the three level system such that three level Rabi oscillations may occur. The second model suggests that the mean-field nature of RT-TDDFT induces paired electron propagation

  13. Local energy equation for two-electron atoms and relation between kinetic energy and electron densities

    International Nuclear Information System (INIS)

    March, N.H.

    2002-08-01

    In early work, Dawson and March [J. Chem. Phys. 81, 5850 (1984)] proposed a local energy method for treating both Hartree-Fock and correlated electron theory. Here, an exactly solvable model two-electron atom with pure harmonic interactions is treated in its ground state in the above context. A functional relation between the kinetic energy density t(r) at the origin r=0 and the electron density p(r) at the same point then emerges. The same approach is applied to the Hookean atom; in which the two electrons repel with Coulombic energy e 2 /r 12 , with r 12 the interelectronic separation, but are still harmonically confined. Again the kinetic energy density t(r) is the focal point, but now generalization away from r=0 is also effected. Finally, brief comments are added about He-like atomic ions in the limit of large atomic number. (author)

  14. Photoelectron spectra as a probe of double-core resonsance in two-electron atoms

    International Nuclear Information System (INIS)

    Grobe, R.; Haan, S.L.; Eberly, J.H.

    1996-01-01

    The authors calculate photoelectron spectra for a two-electron atom under the influence of two external driving fields, using an essential states formalism. They focus on the regime of so-called coherence transfer, in which electron-electron correlation transfers field-induced photo-coherence from one electron to the other. In the case studied here, two laser fields are resonant with coupled atomic transitions, in the manner familiar from three-level dark-state spectroscopy. Dynamical two electron effects are monitored via the photoelectron energy spectrum. The authors show that the distribution of the photoelectron energies can be singly, doubly or triply peaked depending on the relative laser intensities. The electron spectra are independent of the turn-on sequence of the fields

  15. Wave functions and two-electron probability distributions of the Hooke's-law atom and helium

    International Nuclear Information System (INIS)

    O'Neill, Darragh P.; Gill, Peter M. W.

    2003-01-01

    The Hooke's-law atom (hookium) provides an exactly soluble model for a two-electron atom in which the nuclear-electron Coulombic attraction has been replaced by a harmonic one. Starting from the known exact position-space wave function for the ground state of hookium, we present the momentum-space wave function. We also look at the intracules, two-electron probability distributions, for hookium in position, momentum, and phase space. These are compared with the Hartree-Fock results and the Coulomb holes (the difference between the exact and Hartree-Fock intracules) in position, momentum, and phase space are examined. We then compare these results with analogous results for the ground state of helium using a simple, explicitly correlated wave function

  16. Electron acoustic solitary waves in unmagnetized two electron population dense plasmas

    International Nuclear Information System (INIS)

    Mahmood, S.; Masood, W.

    2008-01-01

    The electron acoustic solitary waves are studied in unmagnetized two population electron quantum plasmas. The quantum hydrodynamic model is employed with the Sagdeev potential approach to describe the arbitrary amplitude electron acoustic waves in a two electron population dense Fermi plasma. It is found that hot electron density hump structures are formed in the subsonic region in such type of quantum plasmas. The wave amplitude as well as the width of the soliton are increased with the increase of percentage presence of cold (thinly populated) electrons in a multicomponent quantum plasma. It is found that an increase in quantum diffraction parameter broadens the nonlinear structure. Furthermore, the amplitude of the nonlinear electron acoustic wave is found to increase with the decrease in Mach number. The numerical results are also presented to understand the formation of solitons in two electron population Fermi plasmas.

  17. Dynamical localization of two electrons in triple-quantum-dot shuttles

    International Nuclear Information System (INIS)

    Qu, Jinxian; Duan, Suqing; Yang, Ning

    2012-01-01

    The dynamical localization phenomena in two-electron quantum-dot shuttles driven by an ac field have been investigated and analyzed by the Floquet theory. The dynamical localization occurs near the anti-crossings in Floquet eigenenergy spectrum. The oscillation of the quantum-dot shuttles may increase the possibility of the dynamical localization. Especially, even if the two electrons are initialized in two neighbor dots, they can be localized there for appropriate intensity of the driven field. The studies may help the understanding of dynamical localization in electron shuttles and expand the application potential of nanoelectromechanical devices. -- Highlights: ► The dynamical localization in electron shuttle is studied by Floquet theory. ► There is a relation between quasi-energy anti-crossings and dynamical localization. ► The oscillation of quantum dot increases the dynamical localization. ► Even the electrons are initialized in different dots, the localization can occur.

  18. Exact exchange-correlation potentials of singlet two-electron systems

    Science.gov (United States)

    Ryabinkin, Ilya G.; Ospadov, Egor; Staroverov, Viktor N.

    2017-10-01

    We suggest a non-iterative analytic method for constructing the exchange-correlation potential, v XC ( r ) , of any singlet ground-state two-electron system. The method is based on a convenient formula for v XC ( r ) in terms of quantities determined only by the system's electronic wave function, exact or approximate, and is essentially different from the Kohn-Sham inversion technique. When applied to Gaussian-basis-set wave functions, the method yields finite-basis-set approximations to the corresponding basis-set-limit v XC ( r ) , whereas the Kohn-Sham inversion produces physically inappropriate (oscillatory and divergent) potentials. The effectiveness of the procedure is demonstrated by computing accurate exchange-correlation potentials of several two-electron systems (helium isoelectronic series, H2, H3 + ) using common ab initio methods and Gaussian basis sets.

  19. Space-group approach to two-electron states in unconventional superconductors

    International Nuclear Information System (INIS)

    Yarzhemsky, V. G.

    2008-01-01

    The direct application of the space-group representation theory, makes possible to obtain limitations for the symmetry of SOP on lines and planes of symmetry in one-electron Brillouin zone. In the case of highly symmetric UPt 3 only theoretical nodal structure of IR E 2u is in agreement with all the experimental results. On the other hand, in the case of high-T c superconductors the two electron description of Cooper pairs in D 2h symmetry is not sufficient to describe experimental nodal structure. It was shown that in this case, the nodal structure is the result of underlying interactions between two-electron states and hidden symmetry D-4 h . (author)

  20. Two electron response to an intense x-ray free electron laser pulse

    International Nuclear Information System (INIS)

    Moore, L R; Parker, J S; Meharg, K J; Armstrong, G S J; Taylor, K T

    2009-01-01

    New x-ray free electron lasers (FELs) promise an ultra-fast ultra-intense regime in which new physical phenomena, such as double core hole formation in at atom, should become directly observable. Ahead of x-ray FEL experiments, an initial key task is to theoretically explore such fundamental laser-atom interactions and processes. To study the response of a two-electron positive ion to an intense x-ray FEL pulse, our theoretical approach is a direct numerical integration, incorporating non-dipole Hamiltonian terms, of the full six-dimensional time-dependent Schroedinger equation. We present probabilities of double K-shell ionization in the two-electron positive ions Ne 8+ and Ar 16+ exposed to x-ray FEL pulses with frequencies in the range 50 au to 300 au and intensities in the range 10 17 to 10 22 W/cm 2 .

  1. Two electron response to an intense x-ray free electron laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Moore, L R; Parker, J S; Meharg, K J; Armstrong, G S J; Taylor, K T, E-mail: l.moore@qub.ac.u [DAMTP, David Bates Building, Queen' s University Belfast, Belfast, BT7 1NN (United Kingdom)

    2009-11-01

    New x-ray free electron lasers (FELs) promise an ultra-fast ultra-intense regime in which new physical phenomena, such as double core hole formation in at atom, should become directly observable. Ahead of x-ray FEL experiments, an initial key task is to theoretically explore such fundamental laser-atom interactions and processes. To study the response of a two-electron positive ion to an intense x-ray FEL pulse, our theoretical approach is a direct numerical integration, incorporating non-dipole Hamiltonian terms, of the full six-dimensional time-dependent Schroedinger equation. We present probabilities of double K-shell ionization in the two-electron positive ions Ne{sup 8+} and Ar{sup 16+} exposed to x-ray FEL pulses with frequencies in the range 50 au to 300 au and intensities in the range 10{sup 17} to 10{sup 22} W/cm{sup 2}.

  2. Electron Bifurcation: Thermodynamics and Kinetics of Two-Electron Brokering in Biological Redox Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Peng; Yuly, Jonathon L.; Lubner, Carolyn E. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Mulder, David W. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; King, Paul W. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Peters, John W. [Institute; Beratan, David N. [Department

    2017-08-23

    How can proteins drive two electrons from a redox active donor onto two acceptors at very different potentials and distances? And how can this transaction be conducted without dissipating very much energy or violating the laws of thermodynamics? Nature appears to have addressed these challenges by coupling thermodynamically uphill and downhill electron transfer reactions, using two-electron donor cofactors that have very different potentials for the removal of the first and second electron. Although electron bifurcation is carried out with near perfection from the standpoint of energy conservation and electron delivery yields, it is a biological energy transduction paradigm that has only come into focus recently. This Account provides an exegesis of the biophysical principles that underpin electron bifurcation.

  3. Quantification of entanglement entropies for doubly excited resonance states in two-electron atomic systems

    International Nuclear Information System (INIS)

    Ho, Yew Kam; Lin, Chien-Hao

    2015-01-01

    In this work, we study the quantum entanglement for doubly excited resonance states in two-electron atomic systems such as the H - and Ps - ions and the He atom by using highly correlated Hylleraas type functions The resonance states are determined by calculation of density of resonance states with the stabilization method. The spatial (electron-electron orbital) entanglement entropies (linear and von Neumann) for the low-lying doubly excited states are quantified using the Schmidt-Slater decomposition method. (paper)

  4. A simple parameter-free wavefunction for the ground state of two-electron atoms

    International Nuclear Information System (INIS)

    Ancarani, L U; Rodriguez, K V; Gasaneo, G

    2007-01-01

    We propose a simple and pedagogical wavefunction for the ground state of two-electron atoms which (i) is parameter free (ii) satisfies all two-particle cusp conditions (iii) yields reasonable ground-state energies, including the prediction of a bound state for H - . The mean energy, and other mean physical quantities, is evaluated analytically. The simplicity of the result can be useful as an easy-to-use wavefunction when testing collision models

  5. Ion emission from laser-produced plasmas with two electron temperatures

    International Nuclear Information System (INIS)

    Wickens, L.M.; Allen, J.E.; Rumsby, P.T.

    1978-01-01

    An analytic theory for the expansion of a laser-produced plasma with two electron temperatures is presented. It is shown that from the ion-emission velocity spectrum such relevant parameters as the hot- to -cold-electron density ratio, the absolute hot- and cold-electron temperatures, and a sensitive measure of hot- and cold-electron temperature ratio can be deduced. A comparison with experimental results is presented

  6. Simultaneous adsorption and reduction of U(VI) on reduced graphene oxide-supported nanoscale zerovalent iron

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yubing [School of Environment and Chemical Engineering, North China Electric Power University, Beijing 102206 (China); Institute of Plasma Physics, Chinese Academy of Science, P.O. Box 1126, Hefei, 230031 (China); Ding, Congcong; Cheng, Wencai [Institute of Plasma Physics, Chinese Academy of Science, P.O. Box 1126, Hefei, 230031 (China); Wang, Xiangke, E-mail: xkwang@ipp.ac.cn [School of Environment and Chemical Engineering, North China Electric Power University, Beijing 102206 (China); Faculty of Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2014-09-15

    Graphical abstract: - Highlights: • Sorption and in-situ reduction of U(VI) is observed. • The composites are more effective for U(VI) removal and solidification. • The inner-sphere surface complexes are observed. - Abstract: The reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites were synthesized by chemical deposition method and were characterized by SEM, high resolution TEM, Raman and potentiometric acid-base titrations. The characteristic results showed that the nZVI nanoparticles can be uniformly dispersed on the surface of rGO. The removal of U(VI) on nZVI/rGO composites as a function of contact time, pH and U(VI) initial concentration was investigated by batch technique. The removal kinetics of U(VI) on nZVI and nZVI/rGO were well simulated by a pseudo-first-order kinetic model and pseudo-second-order kinetic model, respectively. The presence of rGO on nZVI nanoparticles increased the reaction rate and removal capacity of U(VI) significantly, which was attributed to the chemisorbed OH{sup −} groups of rGO and the massive enrichment of Fe{sup 2+} on rGO surface by XPS analysis. The XRD analysis revealed that the presence of rGO retarded the transformation of iron corrosion products from magnetite/maghemite to lepidocrocite. According to the fitting of EXAFS spectra, the U-C (at ∼2.9 Å) and U-Fe (at ∼3.2 Å) shells were observed, indicating the formation of inner-sphere surface complexes on nZVI/rGO composites. Therefore, the nZVI/rGO composites can be suitable as efficient materials for the in-situ remediation of uranium-contaminated groundwater in the environmental pollution management.

  7. Doubly excited 3Pe resonance states of two-electron positive ions in Debye plasmas

    International Nuclear Information System (INIS)

    Hu, Xiao-Qing; Wang, Yang; Kar, Sabyasachi; Jiang, Zishi; Jiang, Pinghui

    2015-01-01

    We investigate the doubly excited 3 P e resonance states of two-electron positive ions Li + , Be 2+ , B 3+ , and C 4+ by employing correlated exponential wave functions. In the framework of the stabilization method, we calculate two series (3pnp and 3dnd) of 3 P e resonances below the N = 3 threshold. The 3 P e resonance parameters (resonance energies and widths) are reported for the first time as a function of the screening parameter. For free-atomic cases, comparisons are made with the reported results and few resonance states are reported for the first time

  8. Potential Formation in Front of an Electron Emitting Electrode in a Two-Electron Temperature Plasma

    International Nuclear Information System (INIS)

    Gyergyek, T.; Cercek, M.; Erzen, D.

    2003-01-01

    Plasma potential formation in the pre-sheath region of a floating electron emitting electrode (collector) is studied theoretically in a two-electron-temperature plasma using a static kinetic plasma-sheath model. Dependence of the collector floating potential, the plasma potential in the pre-sheath region, and the critical emission coefficient on the hot electron density and temperature is calculated. It is found that for high hot to cool electron temperature ratio a double layer like solutions exist in a certain range of hot to cool electron densities

  9. Two-electron states in double quantum dot in direct electric field

    International Nuclear Information System (INIS)

    Burdov, V.A.

    2001-01-01

    One determined analytically the wave functions of stationary states and the spectrum of two-electron system in symmetric binary quantum point. It is shown that in the normal state at the absence of external electric field the electrons due to the Coulomb blockade can not be collectively in one quantum point. In the external electric field the situation changes. When a certain critical value of field intensity is reached the probability of detection of both electrons in one quantum point by a jump increases from zero up to 1 [ru

  10. Impurity with two electrons in the spherical quantum dot with Unite confinement potential

    International Nuclear Information System (INIS)

    Baghdasaryan, D A; Ghaltaghchyan, H Ts; Kazaryan, E M; Sarkisyan, H A

    2016-01-01

    Two-electron states in a spherical QD with the hydrogenic impurity located in the center and with a finite height confinement potential barrier are investigated. The effective mass mismatch have been taken into account. The dependence of ground state energy and Coulomb electron-electron interaction energy correction on the QD size is studied. The problem of the state exchange time control in QD is discussed, taking into account the spins of the electrons in the Russell-Saunders approximation. The effect of quantum emission has been shown. (paper)

  11. Two-electron excitation to Rydberg levels in fast I6+ on hydrogen collisions

    International Nuclear Information System (INIS)

    Liao, C.; Hagmann, S.; Zouros, T.J.M.; Montenegro, E.C.; Toth, G.; Richard, P.; Grabbe, S.; Bhalla, C.P.

    1995-01-01

    The emission of electrons in the forward direction in collisions of 0.3 MeV/u I 6+ with H 2 has been studied, and strong autoionization peaks are observed on the shoulder of the cusp peak. The energies of these autoionization lines in the projectile rest frame are determined by high-resolution electron spectroscopy. Using the electron projectile final charge state coincidence technique, we probe different collision mechanisms, which create continuum electrons that are slow in the projectile rest frame. We conclude that the observed autoionization lines are due to two electron excitation to projectile Rydberg levels. (orig.)

  12. Critical density for Landau damping in a two-electron-component plasma

    Energy Technology Data Exchange (ETDEWEB)

    Rupp, Constantin F.; López, Rodrigo A.; Araneda, Jaime A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción (Chile)

    2015-10-15

    The asymptotic evolution of an initial perturbation in a collisionless two-electron-component plasma with different temperatures is studied numerically. The transition between linear and nonlinear damping regimes is determined by slowly varying the density of the secondary electron-component using high-resolution Vlasov-Poisson simulations. It is shown that, for fixed amplitude perturbations, this transition behaves as a critical phenomenon with time scales and field amplitudes exhibiting power-law dependencies on the threshold density, similar to the critical amplitude behavior in a single-component plasma.

  13. First and second derivatives of two electron integrals over Cartesian Gaussians using Rys polynomials

    International Nuclear Information System (INIS)

    Schlegel, H.B.; Binkley, J.S.; Pople, J.A.

    1984-01-01

    Formulas are developed for the first and second derivatives of two electron integrals over Cartesian Gaussians. Integrals and integral derivatives are evaluated by the Rys polynomial method. Higher angular momentum functions are not used to calculate the integral derivatives; instead the integral formulas are differentiated directly to produce compact and efficient expressions for the integral derivatives. The use of this algorithm in the ab initio molecular orbital programs gaussIan 80 and gaussIan 82 is discussed. Representative timings for some small molecules with several basis sets are presented. This method is compared with previously published algorithms and its computational merits are discussed

  14. On the exact spectra of two electrons confined by two-dimensional quantum dots

    International Nuclear Information System (INIS)

    Soldatov, A.V.; Bogolubov Jr, N.N.

    2005-12-01

    Applicability of the method of intermediate problems to investigation of the energy spectrum and eigenstates of a two- electron two-dimensional quantum dot (QD) formed by a parabolic confining potential is discussed. It is argued that the method of intermediate problems, which provides convergent improvable lower bound estimates for eigenvalues of linear half-bound Hermitian operators in Hilbert space, can be fused with the classical Rayleigh-Ritz variational method and stochastic variational method thus providing an efficient tool of verification of the results obtained so far by various analytical and numerical methods being of current usage for studies of quantum dot models. (author)

  15. Double-continuum wave functions and double-photoionization cross sections of two-electron systems

    International Nuclear Information System (INIS)

    Tiwary, S.N.

    1996-09-01

    The present review briefly presents the growing experimental as well as theoretical interests in recent years in the double-continuum wave functions and double-photoionization cross sections of two-electron systems. The validity of existing double-continuum wave functions is analyzed and the importance of electronic correlations in both the initial as well as final states wave functions involved in the transition amplitude for double-photoionization process is demonstrated. At present, we do not have comprehensive and practical double-continuum wave functions which account the full correlation of two-electron in the continuum. Basic difficulties in making accurate theoretical calculations of double ionization by a single high energy photon especially in the vicinity of the threshold, where the correlation plays an important role, are discussed. Illuminating, illustrative and representative examples are presented in order to show the present status and the progress in this field. Future challenges and directions, in high-precision double-photoionization cross sections calculations, have been discussed and suggested. (author). 133 refs, 9 figs

  16. Two-electron electrochemical oxidation of quercetin and kaempferol changes only the flavonoid C-ring

    DEFF Research Database (Denmark)

    Jørgensen, Lars; Cornett, Claus; Justesen, Ulla

    1998-01-01

    Bulk electrolysis of the antioxidant flavonoids quercetin and kaempferol in acetonitrile both yield a single oxidation product in two-electron processes. The oxidation products are more polar than their parent compounds, with an increased molecular weight of 16g/mol, and were identified as 2......-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3 (2H)-benzofuranone and 2-(4-hydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone for quercetin and kaempferol, respectively. Two-electron oxidation of the parent flavonoid is suggested to yield a 3,4-flavandione with unchanged substitution pattern in the A- and B-ring, which...... may rearrange to form the substituted 3(2H)-benzofuranone through the chalcan-trione ring-chain tautomer. The acidity of the 3-OH group is suggested to determine the fate of the flavonoid phenoxyl radical originally formed by one-electron oxidation, as no well-defined oxidation product of luteolin...

  17. Two-electron one-photon decay rates in doubly ionized atoms

    International Nuclear Information System (INIS)

    Baptista, G.B.

    1984-01-01

    The transion rate for the two-electron one-photon and one-electron one-photon decaying processes in atoms bearing initially two K-shell vacancies were evaluated for Ne up to Zr. The two-electron one-photon decay process is considered to be the result of the interaction between the jumping electrons and their interaction with the radiation field. The calculation is performed in second order perturbation theory and the many particle states are constructed from single particle solutions. The present approach allows one to discuss several aspects of the decaying process. The results obtained for the branching ratio between the two processes reproduces reasonably well available experimental data and show an almost linear dependence on the second power of the atomic number. A comparison with other theoretical predictions is also presented for the two decaying processes and the strong dependence of the branching ratio on the initial configuration of the decaying atom is pointed out. (Author) [pt

  18. Measurements of threshold behavior for one- and two-electron photodetachment from the H- ion

    International Nuclear Information System (INIS)

    Frost, C.A.

    1981-09-01

    One and two-electron photodetachment from the H - ion by a single photon has been studied using a crossed beam apparatus. A Q-switched laser beam was directed across the 800 MeV H - beam at LAMPF (β=0.842) resulting in Doppler-shifted photon energies in the H - barycentric frame, which were tunable from 0.4 eV to 15.5 eV by changing the intersection angle. The particles (e - , H 0 , H + ) resulting from photodetachment reactions were magnetically deflected into scintillation detectors allowing the total and partial cross sections for 1e - and 2e - processes to be separately measured. The 2e - signal (H + ) was produced by two different mechanisms, the true signal γ + H - → H + + 2e - and the background process γ + H - → H 0 (n), followed by motional electric field ionization of excited H 0 . Two-electron photodetachment which had been predicted theoretically was observed for the first time, and the relative cross section was measured from threshold to 15.5 eV. Tfrared absorption spectra of intrinsic a-Si:H films by the argon working gas partial pressure, hydrogen partial pressure, and substrate temperature variperiods of time at lower temperatures because aromatic hydrocarbons economic conditions. The symptomology of the various trace metals and oxides isen as potentially more efficient for both employer and employee than is the use of regulatory standards

  19. Quadrupole moments as measures of electron correlation in two-electron atoms

    International Nuclear Information System (INIS)

    Ceraulo, S.C.; Berry, R.S.

    1991-01-01

    We have calculated quadrupole moments, Q zz , of helium in several of its doubly excited states and in two of its singly excited Rydberg states, and of the alkaline-earth atoms Be, Mg, Ca, Sr, and Ba in their ground and low-lying excited states. The calculations use well-converged, frozen-core configuration-interaction (CI) wave functions and, for interpretive purposes, Hartree-Fock (HF) atomic wave functions and single-term, optimized, molecular rotor-vibrator (RV) wave functions. The quadrupole moments calculated using RV wave functions serve as a test of the validity of the correlated, moleculelike model, which has been used to describe the effects of electron correlation in these two-electron and pseudo-two-electron atoms. Likewise, the quadrupole moments calculated with HF wave functions test the validity of the independent-particle model. In addition to their predictive use and their application to testing simple models, the quadrupole moments calculated with CI wave functions reveal previously unavailable information about the electronic structure of these atoms. Experimental methods by which these quadrupole moments might be measured are also discussed. The quadrupole moments computed from CI wave functions are presented as predictions; measurements of Q zz have been made for only two singly excited Rydberg states of He, and a value of Q zz has been computed previously for only one of the states reported here. We present these results in the hope of stimulating others to measure some of these quadrupole moments

  20. A comparative study of electrochemical reduction of isatin and its ...

    Indian Academy of Sciences (India)

    Administrator

    hibit a single irreversible two-electron reduction wave in contrast with the two discrete one-electron transfer reduction ... experiments. The working electrode was a Static Mercury Drop Elec- ..... Women Scientist Scheme (WOS-A), is gratefully.

  1. Impurity effects in two-electron coupled quantum dots: entanglement modulation

    International Nuclear Information System (INIS)

    Acosta Coden, Diego S; Romero, Rodolfo H; Ferrón, Alejandro; Gomez, Sergio S

    2013-01-01

    We present a detailed analysis of the electronic and optical properties of two-electron quantum dots with a two-dimensional Gaussian confinement potential. We study the effects of Coulomb impurities and the possibility of manipulating the entanglement of the electrons by controlling the confinement potential parameters. The degree of entanglement becomes highly modulated by both the location and charge screening of the impurity atom, resulting in two regimes: one of low entanglement and the other of high entanglement, with both of them mainly determined by the magnitude of the charge. It is shown that the magnitude of the oscillator strength of the system could provide an indication of the presence and characteristics of impurities and, therefore, the degree of entanglement. (paper)

  2. Full two-electron calculations of antiproton collisions with molecular hydrogen

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2010-01-01

    Total cross sections for single ionization and excitation of molecular hydrogen by antiproton impact are presented over a wide range of impact energies from 1 keV to 6.5 MeV. A nonperturbative time-dependent close-coupling method is applied to fully treat the correlated dynamics of the electrons....... Good agreement is obtained between the present calculations and experimental measurements of single-ionization cross sections at high energies, whereas some discrepancies with the experiment are found around the maximum. The importance of the molecular geometry and a full two-electron description...... is demonstrated. The present findings provide benchmark results which might be useful for the development of molecular models....

  3. Confined quantum systems: spectral properties of two-electron quantum dots

    International Nuclear Information System (INIS)

    Sako, T; Diercksen, G H F

    2003-01-01

    The spectrum, electron-density distribution and ground-state correlation energy of two electrons confined by an anisotropic harmonic oscillator potential have been studied for different confinement strengths ω by using the quantum chemical configuration interaction (CI) method employing a large Cartesian anisotropic Gaussian basis set and a full CI wavefunction. Energy level diagrams and electron-density distributions are displayed for selected electronic states and confinement parameters. The total energy and spacing between energy levels increase in all cases with increasing ω. The energy level structure cannot be matched by scaling with respect to ω. The correlation energy of the ground state is comparable in magnitude to that of the helium atom. It increases for increasing ω. The percentage of the correlation energy with respect to the total energy of the ground state is considerably larger than that of the helium atom

  4. Dynamical generalization of a solvable family of two-electron model atoms with general interparticle repulsion

    International Nuclear Information System (INIS)

    Niehaus, T A; Suhai, S; March, N H

    2008-01-01

    Holas, Howard and March (2003 Phys. Lett. A 310 451) have obtained analytic solutions for ground-state properties of a whole family of two-electron spin-compensated harmonically confined model atoms whose different members are characterized by a specific interparticle potential energy u(r 12 ). Here, we make a start on the dynamic generalization of the harmonic external potential, the motivation being the serious criticism levelled recently against the foundations of time-dependent density-functional theory (e.g., Schirmer and Dreuw 2007 Phys. Rev. A 75 022513). In this context, we derive a simplified expression for the time-dependent electron density for arbitrary interparticle interaction, which is fully determined by a one-dimensional non-interacting Hamiltonian. Moreover, a closed solution for the momentum space density in the Moshinsky model is obtained

  5. Weak-field asymptotic theory of tunneling ionization: benchmark analytical results for two-electron atoms

    International Nuclear Information System (INIS)

    Trinh, Vinh H; Morishita, Toru; Tolstikhin, Oleg I

    2015-01-01

    The recently developed many-electron weak-field asymptotic theory of tunneling ionization of atoms and molecules in an external static electric field (Tolstikhin et al 2014, Phys. Rev. A 89, 013421) is extended to the first-order terms in the asymptotic expansion in field. To highlight the results, here we present a simple analytical formula giving the rate of tunneling ionization of two-electron atoms H − and He. Comparison with fully-correlated ab initio calculations available for these systems shows that the first-order theory works quantitatively in a wide range of fields up to the onset of over-the-barrier ionization and hence is expected to find numerous applications in strong-field physics. (fast track communication)

  6. Variational and robust density fitting of four-center two-electron integrals in local metrics

    Science.gov (United States)

    Reine, Simen; Tellgren, Erik; Krapp, Andreas; Kjærgaard, Thomas; Helgaker, Trygve; Jansik, Branislav; Høst, Stinne; Salek, Paweł

    2008-09-01

    Density fitting is an important method for speeding up quantum-chemical calculations. Linear-scaling developments in Hartree-Fock and density-functional theories have highlighted the need for linear-scaling density-fitting schemes. In this paper, we present a robust variational density-fitting scheme that allows for solving the fitting equations in local metrics instead of the traditional Coulomb metric, as required for linear scaling. Results of fitting four-center two-electron integrals in the overlap and the attenuated Gaussian damped Coulomb metric are presented, and we conclude that density fitting can be performed in local metrics at little loss of chemical accuracy. We further propose to use this theory in linear-scaling density-fitting developments.

  7. Formation of presheath and current-free double layer in a two-electron-temperature plasma

    International Nuclear Information System (INIS)

    Sato, Kunihiro; Miyawaki, Fujio

    1992-02-01

    Development of the steady-state potential in a two-temperature-electron plasma in contact with the wall is investigated analytically. It is shown that if the hot- to cold electron temperature ratio is greater than ten, the potential drop in the presheath, which is allowed to have either a small value characterized by the cold electrons or a large value by the hot electrons, discontinuously changes at a critical value for the hot- to total electron density ratio. It is also found that the monotonically decreasing potential structure which consists of the first presheath, a current-free double layer, the second presheath, and the sheath can be steadily formed in a lower range of the hot- to total electron density ratio around the critical value. The current-free double layer is set up due to existence of the two electron species and cold ions generated by ionization so as to connect two presheath potentials at different levels. (author)

  8. Electron capture in pseudo-two-electron systems: Ar8++He

    International Nuclear Information System (INIS)

    Kimura, M.; Olson, R.E.

    1985-01-01

    Molecular-structure calculations using the pseudopotential method have been performed on the (ArHe) 8+ system. The cross section for single-electron capture in Ar 8+ +He collisions was calculated for energies from 20 eV to 10 keV/amu. The perturbed-stationary-state method [M. Kimura, H. Sato, and R. E. Olson, Phys. Rev. A 28, 2085 (1983)], modified to include electron translation factors appropriate to two-electron systems, was used. The total cross section is relatively energy independent with a value of approximately 2.5 x 10 -15 cm 2 . The n = 4 level of Ar 7+ is found to be preferentially populated, with the 4f level being dominant

  9. Imaging the square of the correlated two-electron wave function of a hydrogen molecule.

    Science.gov (United States)

    Waitz, M; Bello, R Y; Metz, D; Lower, J; Trinter, F; Schober, C; Keiling, M; Lenz, U; Pitzer, M; Mertens, K; Martins, M; Viefhaus, J; Klumpp, S; Weber, T; Schmidt, L Ph H; Williams, J B; Schöffler, M S; Serov, V V; Kheifets, A S; Argenti, L; Palacios, A; Martín, F; Jahnke, T; Dörner, R

    2017-12-22

    The toolbox for imaging molecules is well-equipped today. Some techniques visualize the geometrical structure, others the electron density or electron orbitals. Molecules are many-body systems for which the correlation between the constituents is decisive and the spatial and the momentum distribution of one electron depends on those of the other electrons and the nuclei. Such correlations have escaped direct observation by imaging techniques so far. Here, we implement an imaging scheme which visualizes correlations between electrons by coincident detection of the reaction fragments after high energy photofragmentation. With this technique, we examine the H 2 two-electron wave function in which electron-electron correlation beyond the mean-field level is prominent. We visualize the dependence of the wave function on the internuclear distance. High energy photoelectrons are shown to be a powerful tool for molecular imaging. Our study paves the way for future time resolved correlation imaging at FELs and laser based X-ray sources.

  10. A Moessbauer study of the germanium two-electron donor centers in PbSe

    International Nuclear Information System (INIS)

    Terukov, E.I.; Khuzhakulov, Eh.S.

    2005-01-01

    The 73 As( 73 Ge) Moessbauer emission spectroscopy is used for identification of neutral and ionized two-electron germanium centers in PbSe. It is shown that the charge state of antistructural defect 73 Ge, generating in the anion sublattice after 73 As radioactive decay, does not depend on the Fermi level position. In contrast to this, the 73 Ge center in the cation PbSe sublattice represents the electrically active substitution impurity. The emission spectra correspond to the neutral state of the ( 73 Ge 2+ ) donor center in n-type conductors and to the double ionized state of this ( 73 Ge 4+ ) center in p-type conductors [ru

  11. Origin of Hund's multiplicity rule in quasi-two-dimensional two-electron quantum dots

    International Nuclear Information System (INIS)

    Sako, Tokuei; Paldus, Josef; Diercksen, Geerd H. F.

    2010-01-01

    The origin of Hund's multiplicity rules has been studied for a system of two electrons confined by a quasi-two-dimensional harmonic-oscillator potential by relying on a full configuration interaction wave function and Cartesian anisotropic Gaussian basis sets. In terms of appropriate normal-mode coordinates the wave function factors into a product of the center-of-mass and the internal components. The 1 Π u singlet state and the 3 Π u triplet state represent the energetically lowest pair of states to which Hund's multiplicity rule applies. They are shown to involve excitations into different degrees of freedom, namely, into the center-of-mass angular mode and the internal angular mode for the singlet and triplet states, respectively. The presence of an angular nodal line in the internal space allows then the triplet state to avoid the singularity in the electron-electron interaction potential, leading to the energy lowering of the triplet state relative to its counterpart singlet state.

  12. Confinement control mechanism for two-electron Hulthen quantum dots in plasmas

    Science.gov (United States)

    Bahar, M. K.; Soylu, A.

    2018-05-01

    In this study, for the first time, the energies of two-electron Hulthen quantum dots (TEHQdots) embedded in Debye and quantum plasmas modeled by the more general exponential cosine screened Coulomb (MGECSC) potential under the combined influence of electric and magnetic fields are investigated by numerically solving the Schrödinger equation using the asymptotic iteration method. To do this, the four different forms of the MGECSC potential, which set through the different cases of the potential parameters, are taken into consideration. We propose that plasma environments form considerable quantum mechanical effects for quantum dots and other atomic systems and that plasmas are important experimental arguments. In this study, by considering the quantum dot parameters, the external field parameters, and the plasma screening parameters, a control mechanism of the confinement on energies of TEHQdots and the frequency of the radiation emitted by TEHQdots as a result of any excitation is discussed. In this mechanism, the behaviors, similarities, the functionalities of the control parameters, and the influences of plasmas on these quantities are explored.

  13. Investigations of the Lamb shift in heavy one and two electron systems

    International Nuclear Information System (INIS)

    Reuschl, Regina

    2008-01-01

    Experiments on the 1s Lamb-shift in heavy H-like ions and on the intra-shell transitions in heavy He-like systems have been performed. These investigations are of particular interest to verify the validity of quantum electrodynamics (QED) in extremely strong Coulomb fields. In addition, in heavy systems not only QED but also relativistic effects start to play a key role. The experiments have been performed at the gas-jet target of the experimental storage ring (ESR) at GSI. In an experiment with He-like uranium we were able to directly measure the intra-shell transition 2 3 P 2 →2 3 S 1 , in a high-Z system for the very first time. This has been achieved by combining the results from a high-resolution Bragg crystal-spectrometer and a standard planar Germanium detector. A fit of the experimental spectrum with data obtained from a simulation shows, the theoretical predictions describe the transition dynamics very well in this two-electron system. Another experiment has been performed on H-like lead to investigate the 1s Lamb-shift in heavy H-like systems. Here, a high-resolution Laue crystal-spectrometer has been commissioned together with novel high-resolution two dimensional micro-strip Ge-detectors. The combination of both instruments is a very promising tool for future high-precision X-ray experiments. (orig.)

  14. Two-electrons quantum dot in plasmas under the external fields

    Science.gov (United States)

    Bahar, M. K.; Soylu, A.

    2018-02-01

    In this study, for the first time, the combined effects of the external electric field, magnetic field, and confinement frequency on energies of two-electron parabolic quantum dots in Debye and quantum plasmas modeled by more general exponential cosine screened Coulomb (MGECSC) potential are investigated by numerically solving the Schrödinger equation using the asymptotic iteration method. The MGECSC potential includes four different potential forms when considering different sets of the parameters in potential. Since the plasma is an important experimental argument for quantum dots, the influence of plasmas modeled by the MGECSC potential on quantum dots is probed. The confinement frequency of quantum dots and the external fields created significant quantum restrictions on quantum dot. In this study, as well as discussion of the functionalities of the quantum restrictions for experimental applications, the parameters are also compared with each other in terms of influence and behaviour. In this manner, the motivation points of this study are summarized as follows: Which parameter can be alternative to which parameter, in terms of experimental applications? Which parameters exhibit similar behaviour? What is the role of plasmas on the corresponding behaviours? In the light of these research studies, it can be said that obtained results and performed discussions would be important in experimental and theoretical research related to plasma physics and/or quantum dots.

  15. Two-electron spin correlations in precision placed donors in silicon.

    Science.gov (United States)

    Broome, M A; Gorman, S K; House, M G; Hile, S J; Keizer, J G; Keith, D; Hill, C D; Watson, T F; Baker, W J; Hollenberg, L C L; Simmons, M Y

    2018-03-07

    Substitutional donor atoms in silicon are promising qubits for quantum computation with extremely long relaxation and dephasing times demonstrated. One of the critical challenges of scaling these systems is determining inter-donor distances to achieve controllable wavefunction overlap while at the same time performing high fidelity spin readout on each qubit. Here we achieve such a device by means of scanning tunnelling microscopy lithography. We measure anti-correlated spin states between two donor-based spin qubits in silicon separated by 16 ± 1 nm. By utilising an asymmetric system with two phosphorus donors at one qubit site and one on the other (2P-1P), we demonstrate that the exchange interaction can be turned on and off via electrical control of two in-plane phosphorus doped detuning gates. We determine the tunnel coupling between the 2P-1P system to be 200 MHz and provide a roadmap for the observation of two-electron coherent exchange oscillations.

  16. One- and two-electron processes in collisions of heavy ions with H2 and He

    International Nuclear Information System (INIS)

    Richard, P.; Hall, J.; Shinpaugh, J.L.; Sanders, J.M.; Tipping, T.N.; Zouros, T.J.M.; Lee, D.H.; Schmidt-Boecking, H.

    1987-01-01

    In this paper we present a description of the apparatus and results for experiments involving one- and two-electron processes in collisions of heavy ions with H 2 and He. The experiments were performed using one-electron and bare projectiles. In the first section we describe the measurement of pure ionization of one-electron projectiles by H 2 targets and compare with previous results for He targets. We also present the results for one-electron capture by the projectile from H 2 targets. The energy dependence of the cross sections is compared to theoretical predictions for atomic and molecular hydrogen targets. Both experiments were performed by measuring only the final charge state of the projectile. In the second section we describe the measurement of partial cross sections for the same collisions by measuring the target recoil charge state in coincidence with the projectile charge state. By this method we can measure pure single- and double-ionization of the target, pure single-electron transfer and transfer ionization, and pure double-electron transfer. This experiment is presently being performed for bare flourine on He; however, absolute cross sections are not available at the time of this conference. (orig.)

  17. Two-electron germanium centers with a negative correlation energy in lead chalcogenides

    International Nuclear Information System (INIS)

    Terukov, E. I.; Marchenko, A. V.; Zaitseva, A. V.; Seregin, P. P.

    2007-01-01

    It is shown that the charge state of the 73 Ge antisite defect that arises in anionic sublattices of PbS, PbSe, and PbTe after radioactive transformation of 73 As does not depend on the position of the Fermi level, whereas the 73 Ge center in cationic sublattices of PbS and PbSe represents a two-electron donor with the negative correlation energy: the Moessbauer spectrum for the n-type samples corresponds to the neutral state of the donor center (Ge 2+ ), while this spectrum corresponds to the doubly ionized state (Ge 4+ ) of the center in the p-type samples. In partially compensated PbSe samples, a fast electron exchange between the neutral and ionized donor centers is realized. It is shown by the method of Moessbauer spectroscopy for the 119 Sn isotope that the germanium-related energy levels are located higher than the levels formed in the band gap of these semiconductors by the impurity tin atoms

  18. Spin-orbit coupling induced two-electron relaxation in silicon donor pairs

    Science.gov (United States)

    Song, Yang; Das Sarma, S.

    2017-09-01

    We unravel theoretically a key intrinsic relaxation mechanism among the low-lying singlet and triplet donor-pair states in silicon, an important element in the fast-developing field of spintronics and quantum computation. Despite the perceived weak spin-orbit coupling (SOC) in Si, we find that our discovered relaxation mechanism, combined with the electron-phonon and interdonor interactions, drives the transitions in the two-electron states over a large range of donor coupling regimes. The scaling of the relaxation rate with interdonor exchange interaction J goes from J5 to J4 at the low to high temperature limits. Our analytical study draws on the symmetry analysis over combined band, donor envelope, and valley configurations. It uncovers naturally the dependence on the donor-alignment direction and triplet spin orientation, and especially on the dominant SOC source from donor impurities. While a magnetic field is not necessary for this relaxation, unlike in the single-donor spin relaxation, we discuss the crossover behavior with increasing Zeeman energy in order to facilitate comparison with experiments.

  19. Observation of the two-electron cusp in atomic collisions. Evidence for strong electron-electron correlation

    International Nuclear Information System (INIS)

    Sarkadi, L.; Orban, A.

    2007-01-01

    Complete text of publication follows. In this report we present experimental data for a process when two electrons with velocity vectors equal to that of the projectile are emitted from collisions. By observing the two electron cusp the study of the threshold phenomenon for two-electron break-up is possible. It is a particularly interesting question whether the outgoing charged projectile can attract the two repulsing electrons so strongly that the two-electron cusp is formed. If it is so, a further question arises: Are the two electrons correlated in the final state as it is predicted by the Wannier theory? The experiments have been done at the 1 MeV VdG accelerator of ATOMKI using our TOF spectrometer. The first measurements clearly showed the formation of the two-electron cusp and signature of the electron correlation in 200 keV He 0 +He collisions. These promising results motivated us to carry out the experiment at 100 keV beam energy where the coincidence count rate is still reasonable but the energy resolution is better. For an acceptable data acquisition time we improved our data acquisition and data processing system for triple coincidence measurements. In Fig. 1a we present our measured relative fourfold differential cross section (FDCS) that shows strong electron correlation. For a comparison, in Fig. 1b we displayed the contour plot for uncorrelated electron pair emission. These latter data were synthesized artificially, generating the energies of the electron pairs from two independent double coincidence experiments. In both figures the distributions are characterized by two ridges. In Fig. 1b the ridges are perpendicular straight lines (E 1 = E 2 .13.6 eV). As a result of the correlation, the ridges in Fig. 1a are distorted in such a way that they have a joint straight-line section following the line E 1 + E 2 = 27.2 eV. This means that the electron pairs in the vicinity of the cusp maximum are emitted with a center of- mass velocity equal to that of

  20. Absolute total and one and two electron transfer cross sections for Ar8+ on Ar as a function of energy

    International Nuclear Information System (INIS)

    Vancura, J.; Kostroun, V.O.

    1992-01-01

    The absolute total and one and two electron transfer cross sections for Ar 8+ on Ar were measured as a function of projectile laboratory energy from 0.090 to 0.550 keV/amu. The effective one electron transfer cross section dominates above 0.32 keV/amu, while below this energy, the effective two electron transfer starts to become appreciable. The total cross section varies by a factor over the energy range explored. The overall error in the cross section measurement is estimated to be ± 15%

  1. One-photon two-electron processes in helium close to the double ionization threshold

    International Nuclear Information System (INIS)

    Bouri, C.

    2007-04-01

    This work presents a study of the 1 P 0 excited states of He that can be reached by absorption of a single photon carrying an energy close to the double ionization threshold (DIT) (79 eV). Above the DIT, these states are the double continuum states; below, they are the double excited states. These two types of states are tightly coupled to the single continuum states with or without excitation of the residual ion He + , owing to their degeneracy in energy. In a one-photon process, these states can only be formed owing to the electronic correlations in the system which must be well described to obtain quantitative good results. Our study is a part of the work which aims at a united description of all these doubly excited, ionized-excited, and double continuum states. We use the Hyperspherical R-Matrix with Semiclassical Outgoing Waves (HRM-SOW) method, initially dedicated to double photoionization studies. We extend it to extract information on the single continuum. This extension allows us to compute cross sections of single photoionization with or without excitation up to n 50 for an excess of 100 meV just above the double ionization threshold. A deep insight into this process is given by a partial waves analysis. The results obtained shed light on the key role of angular and radial correlations. The numerous data we obtain on double and single ionization allow us to establish a continuity relation between these two processes. We show that single ionization with an infinite excitation of the residual ion merges into double photoionization when the excess energy is redistributed between the two electrons. It appears that this relation is valid not only for low but also for high photon energies. Since the HRM-SOW can produce the integrated cross section for double photoionization with high accuracy in the low energy domain, we check the Wannier threshold law. The parameters extracted support strongly this threshold law, and are in good agreement with experimental

  2. Mechanism of Cobalamin-Mediated Reductive Dehalogenation of Chloroethylenes

    DEFF Research Database (Denmark)

    Ji, Li; Wang, Chenchen; Ji, Shujing

    2017-01-01

    molecular-level insight into the competing pathways for chloroethylenes reacting with cob(I)alamin: the computed ratios of inner-sphere to outer-sphere pathways for perchloroethylene and trichloroethylene are 17:1 and 3.5:1, respectively, in accord with the corresponding experimental ratios of >10:1 and >2...

  3. Coulomb Repulsion Effect in Two-electron Non-adiabatic Tunneling through a One-level redox Molecule

    DEFF Research Database (Denmark)

    Medvedev, Igor M.; Kuznetsov, Alexander M.; Ulstrup, Jens

    2009-01-01

    We investigated Coulomb repulsion effects in nonadiabatic (diabatic) two-electron tunneling through a redox molecule with a single electronic level in a symmetric electrochemical contact under ambient conditions, i.e., room temperature and condensed matter environment. The electrochemical contact...

  4. Two-electron states of a group-V donor in silicon from atomistic full configuration interactions

    Science.gov (United States)

    Tankasala, Archana; Salfi, Joseph; Bocquel, Juanita; Voisin, Benoit; Usman, Muhammad; Klimeck, Gerhard; Simmons, Michelle Y.; Hollenberg, Lloyd C. L.; Rogge, Sven; Rahman, Rajib

    2018-05-01

    Two-electron states bound to donors in silicon are important for both two-qubit gates and spin readout. We present a full configuration interaction technique in the atomistic tight-binding basis to capture multielectron exchange and correlation effects taking into account the full band structure of silicon and the atomic-scale granularity of a nanoscale device. Excited s -like states of A1 symmetry are found to strongly influence the charging energy of a negative donor center. We apply the technique on subsurface dopants subjected to gate electric fields and show that bound triplet states appear in the spectrum as a result of decreased charging energy. The exchange energy, obtained for the two-electron states in various confinement regimes, may enable engineering electrical control of spins in donor-dot hybrid qubits.

  5. Direct measurement of two-electron contributions to the ground state energy of heliumlike high-Z ions

    International Nuclear Information System (INIS)

    Stoehlker, T.; Elliott, S.R.; Marrs, R.E.

    1995-09-01

    We report on a novel technique which exploits Radiative Recombination transitions for a direct experimental determination of the two-electron contributions to the ground state energy in heliumlike high-Z ions. Results are presented of a first experiment which was conducted at an electron beam ion trap for various elements ranging from Z=32 to 83. The comparison with theoretical predictions demonstrates that the achieved precision already provides a sensitive test of second order manybody contributions and approaches the size of the two-electron (screened) Lamb shift. The ptoential of the new technique will be outlined and the capability of the ESR storage ring for future investigations will be emphasized. (orig.)

  6. Effective one-body potential of DFT plus correlated kinetic energy density for two-electron spherical model atoms

    International Nuclear Information System (INIS)

    March, N.H.; Ludena, Eduardo V.

    2004-01-01

    For three model problems concerning two-electron spin-compensated ground states with spherical density, the third-order linear homogeneous differential equation constructed for the determination of ρ(r) is used here in conjunction with the von Weizsacker functional to characterize the one-body potential of density functional theory (DFT). Correlated von Weizsacker-type terms are compared to the exact DFT functional

  7. Highly Efficient and Scalable Compound Decomposition of Two-Electron Integral Tensor and Its Application in Coupled Cluster Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Bo [William R. Wiley Environmental; Kowalski, Karol [William R. Wiley Environmental

    2017-08-11

    The representation and storage of two-electron integral tensors are vital in large- scale applications of accurate electronic structure methods. Low-rank representation and efficient storage strategy of integral tensors can significantly reduce the numerical overhead and consequently time-to-solution of these methods. In this paper, by combining pivoted incomplete Cholesky decomposition (CD) with a follow-up truncated singular vector decomposition (SVD), we develop a decomposition strategy to approximately represent the two-electron integral tensor in terms of low-rank vectors. A systematic benchmark test on a series of 1-D, 2-D, and 3-D carbon-hydrogen systems demonstrates high efficiency and scalability of the compound two-step decomposition of the two-electron integral tensor in our implementation. For the size of atomic basis set N_b ranging from ~ 100 up to ~ 2, 000, the observed numerical scaling of our implementation shows O(N_b^{2.5~3}) versus O(N_b^{3~4}) of single CD in most of other implementations. More importantly, this decomposition strategy can significantly reduce the storage requirement of the atomic-orbital (AO) two-electron integral tensor from O(N_b^4) to O(N_b^2 log_{10}(N_b)) with moderate decomposition thresholds. The accuracy tests have been performed using ground- and excited-state formulations of coupled- cluster formalism employing single and double excitations (CCSD) on several bench- mark systems including the C_{60} molecule described by nearly 1,400 basis functions. The results show that the decomposition thresholds can be generally set to 10^{-4} to 10^{-3} to give acceptable compromise between efficiency and accuracy.

  8. Asymptotically exact expression for the energies of the 3Se Rydberg series in a two-electron system

    International Nuclear Information System (INIS)

    Ivanov, I.A.; Bromley, M.W.J.; Mitroy, J.

    2002-01-01

    The 1sns 3 S e Rydberg series in a two-electron system with the charge of the nucleus, Z≅1, is treated by means of the quantum-defect theory. Comparison with configuration interaction calculations suggests that the quantum-defect expression for the energy levels becomes asymptotically exact as Z→1. This provides an analytic description of the disappearance of the 1sns 3 S e bound states when Z approaches the critical value of 1

  9. Electrocatalytic oxygen reduction and hydrogen evolution reactions on phthalocyanine modified electrodes: Electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Koca, Atif, E-mail: akoca@eng.marmara.edu.tr [Department of Chemical Engineering, Faculty of Engineering, Marmara University, Goeztepe, 34722 Istanbul (Turkey); Kalkan, Ayfer; Bayir, Zehra Altuntas [Department of Chemistry, Technical University of Istanbul, Maslak, 34469 Istanbul (Turkey)

    2011-06-30

    Highlights: > Electrochemical and in situ spectroelectrochemical characterizations of the metallophthalocyanines were performed. > The presence of O{sub 2} influences both oxygen reduction reaction and the electrochemical behaviors of the complexes. > Homogeneous catalytic ORR process occurs via an 'inner sphere' chemical catalysis process. > CoPc and CuPc coated on a glassy carbon electrode decrease the overpotential of the working electrode for H{sup +} reduction. - Abstract: This study describes electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric monitoring of the electrocatalytic reduction of molecular oxygen and hydronium ion on the phthalocyanine-modified electrodes. For this purpose, electrochemical and in situ spectroelectrochemical characterizations of the metallophthalocyanines (MPc) bearing tetrakis-[4-((4'-trifluoromethyl)phenoxy)phenoxy] groups were performed. While CoPc gives both metal-based and ring-based redox processes, H{sub 2}Pc, ZnPc and CuPc show only ring-based electron transfer processes. In situ electrocolorimetric method was applied to investigate the color of the electrogenerated anionic and cationic forms of the complexes. The presence of O{sub 2} in the electrolyte system influences both oxygen reduction reaction and the electrochemical and spectral behaviors of the complexes, which indicate electrocatalytic activity of the complexes for the oxygen reduction reaction. Perchloric acid titrations monitored by voltammetry represent possible electrocatalytic activities of the complexes for hydrogen evolution reaction. CoPc and CuPc coated on a glassy carbon electrode decrease the overpotential of the working electrode for H{sup +} reduction. The nature of the metal center changes the electrocatalytic activities for hydrogen evolution reaction in aqueous solution. Although CuPc has an inactive metal center, its electrocatalytic activity is recorded more than CoPc for H{sup +} reduction in aqueous

  10. Exact correlated kinetic energy related to the electron density for two-electron model atoms with harmonic confinement

    International Nuclear Information System (INIS)

    March, Norman H.; Akbari, Ali; Rubio, Angel

    2007-01-01

    For arbitrary interparticle interaction u(r 12 ), the model two-electron atom in the title is shown to be such that the ground-state electron density ρ(r) is determined uniquely by the correlated kinetic energy density t R (r) of the relative motion. Explicit results for t R (r) are presented for the Hookean atom with force constant k=1/4, and also for u(r 12 )=(λ)/(r 12 2 ) . Possible relevance of the Hookean atom treatment to the ground state of the helium atom itself is briefly discussed

  11. Electron-atom spin asymmetry and two-electron photodetachment - Addenda to the Coulomb-dipole threshold law

    Science.gov (United States)

    Temkin, A.

    1984-01-01

    Temkin (1982) has derived the ionization threshold law based on a Coulomb-dipole theory of the ionization process. The present investigation is concerned with a reexamination of several aspects of the Coulomb-dipole threshold law. Attention is given to the energy scale of the logarithmic denominator, the spin-asymmetry parameter, and an estimate of alpha and the energy range of validity of the threshold law, taking into account the result of the two-electron photodetachment experiment conducted by Donahue et al. (1984).

  12. Excitation and charge transfer in He/sup +/ + H collisions. A molecular approach including two-electron translation factors

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Mendez, L.; Riera, A.

    1983-06-01

    In a previous paper we have pointed out that the common-translation-factor (CTF) method is the only one which, at present, and within the framework of the molecular model of atomic collisions, can be shown to be both convergent and computationally fast, even for many-electron systems. In this Communication we check that this second statement is correct, presenting, for the first time, a molecular calculation involving two-electron translation factors, for He/sup +/ + H collisions. A careful study of the sensitivity of the calculated cross sections to the choice of the CTF is performed, and conclusions on that sensitivity are drawn, for several types of processes.

  13. Excitation and charge transfer in He+ + H collisions. A molecular approach including two-electron translation factors

    International Nuclear Information System (INIS)

    Errea, L.F.; Mendez, L.; Riera, A.

    1983-01-01

    In a previous paper we have pointed out that the common-translation-factor (CTF) method is the only one which, at present, and within the framework of the molecular model of atomic collisions, can be shown to be both convergent and computationally fast, even for many-electron systems. In this Communication we check that this second statement is correct, presenting, for the first time, a molecular calculation involving two-electron translation factors, for He + + H collisions. A careful study of the sensitivity of the calculated cross sections to the choice of the CTF is performed, and conclusions on that sensitivity are drawn, for several types of processes

  14. Reduction of adsorbed As(V) on nano-TiO2 by sulfate-reducing bacteria.

    Science.gov (United States)

    Luo, Ting; Ye, Li; Ding, Cheng; Yan, Jinlong; Jing, Chuanyong

    2017-11-15

    Reduction of surface-bound arsenate [As(V)] and subsequent release into the aqueous phase contribute to elevated As in groundwater. However, this natural process is not fully understood, especially in the presence of sulfate-reducing bacteria (SRB). Gaining mechanistic insights into solid-As(V)-SRB interactions motivated our molecular level study on the fate of nano-TiO 2 bound As(V) in the presence of Desulfovibrio vulgaris DP4, a strain of SRB, using incubation and in situ ATR-FTIR experiments. The incubation results clearly revealed the reduction of As(V), either adsorbed on nano-TiO 2 or dissolved, in the presence of SRB. In contrast, this As(V) reduction was not observed in abiotic control experiments where sulfide was used as the reductant. Moreover, the reduction was faster for surface-bound As(V) than for dissolved As(V), as evidenced by the appearance of As(III) at 45h and 75h, respectively. ATR-FTIR results provided direct evidence that the surface-bound As(V) was reduced to As(III) on TiO 2 surfaces in the presence of SRB. In addition, the As(V) desorption from nano-TiO 2 was promoted by SRB relative to abiotic sulfide, due to the competition between As(V) and bacterial phosphate groups for TiO 2 surface sites. This competition was corroborated by the ATR-FTIR analysis, which showed inner-sphere surface complex formation by bacterial phosphate groups on TiO 2 surfaces. The results from this study highlight the importance of indirect bacteria-mediated As(V) reduction and release in geochemical systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Demonstration of two-electron (shake-up) photoionization and population inversions in the visible and VUV

    International Nuclear Information System (INIS)

    Silfvast, W.T.; Wood, O.R. II; Al-Salameh, D.Y.

    1986-01-01

    The two-electron (shake-up) photoionization process has been shown to be an effective mechanism for producing large population inversions in He/sup +/ with gain at 164 nm and in Ar/sup +/ with gain at 428 and 477 nm and for observing the first autoionizing states in Cd/sup +/. Such a mechanism was recently proposed as an excitation mechanism for a VUV laser in lithium. In each species the rapid excitation and detection using broadband emission from a 30-mJ 100-ps duration laser-produced plasma and a detection system with subnanosecond time resolution were essential in observing these effects. In He, gains of up to 0.8 cm/sup -1/ for durations of 2-4 ns at 164.0 nm on the He-like (n = 3-2) transition in He/sup +/ were measured by comparing the plasma emission from a well-defined volume with and without the presence of a mirror of known reflectivity. The n = 3 upper laser level is pumped not only directly via two-electron photoionization from the neutral ground state but also indirectly (in times of the order of 1-2 ns) via electron collisions from photoionization-pumped higher-lying levels. The decay rate of the photoionization-pumped radiation-trapped lower laser level is increased by a unique process involving absorption of radiation via photoionization of ground state neutral helium atoms

  16. 1,3Do and 1,3Pe states of two electron atoms under Debye plasma screening

    International Nuclear Information System (INIS)

    Saha, Jayanta K.; Bhattacharyya, S.; Mukherjee, T.K.; Mukherjee, P.K.

    2010-01-01

    Extensive non-relativistic variational calculations for estimating the energy values of 2pnd( 1,3 D o ) states [n=3-6] of two electron atoms (He, Li + ,Be 2+ ) and 2pnp( 1 P e )[n=3-8] and 2pnp( 3 P e ) states [n=2-7] of Be 2+ under weakly coupled plasma screening have been performed using explicitly correlated Hylleraas type basis. The modified energy eigenvalues of 1,3 P e states arising from two p electrons of Be 2+ ion and 1,3 D o states due to 2pnd configuration of Li + and Be 2+ ion in the Debye plasma environment are being reported for the first time. The effect of plasma has been incorporated through the Debye screening model. The system tends towards gradual instability and the number of bound states reduces with increasing plasma coupling strength. The wavelengths for 2pn ' p( 1 P e )[n ' =3-8]→2pnd( 1 D o )[n=3-6] and 2pn ' p( 3 P e )[n ' =2-8]→2pnd( 3 D o )[n=3-6] transitions in plasma embedded two electron atoms have also been reported.

  17. Measurements of threshold behavior for one- and two-electron photodetachment from the H/sup -/ ion

    Energy Technology Data Exchange (ETDEWEB)

    Frost, C.A.

    1981-09-01

    One and two-electron photodetachment from the H/sup -/ ion by a single photon has been studied using a crossed beam apparatus. A Q-switched laser beam was directed across the 800 MeV H/sup -/ beam at LAMPF (..beta..=0.842) resulting in Doppler-shifted photon energies in the H/sup -/ barycentric frame, which were tunable from 0.4 eV to 15.5 eV by changing the intersection angle. The particles (e/sup -/, H/sup 0/, H/sup +/) resulting from photodetachment reactions were magnetically deflected into scintillation detectors allowing the total and partial cross sections for 1e/sup -/ and 2e/sup -/ processes to be separately measured. The 2e/sup -/ signal (H/sup +/) was produced by two different mechanisms, the true signal ..gamma.. + H/sup -/ ..-->.. H/sup +/ + 2e/sup -/ and the background process ..gamma.. + H/sup -/ ..-->.. H/sup 0/(n), followed by motional electric field ionization of excited H/sup 0/. Two-electron photodetachment which had been predicted theoretically was observed for the first time, and the relative cross section was measured from threshold to 15.5 eV.

  18. Competition Between Co(NH3)63+ and Inner Sphere Mg2+ Ions in the HDV Ribozyme

    OpenAIRE

    Gong, Bo; Chen, Jui-Hui; Bevilacqua, Philip C.; Golden, Barbara L.; Carey, Paul R.

    2009-01-01

    Divalent cations play critical structural and functional roles in many RNAs. While the hepatitis delta virus (HDV) ribozyme can undergo self-cleavage in the presence of molar concentrations of monovalent cations, divalent cations such as Mg2+ are required for efficient catalysis under physiological conditions. Moreover, the cleavage reaction can be inhibited with Co(NH3)63+, an analog of Mg(H2O)62+. Here, the binding of Mg2+ and Co(NH3)63+ to the HDV ribozyme are studied by Raman microscopic ...

  19. Performance Tuning of Fock Matrix and Two-Electron Integral Calculations for NWChem on Leading HPC Platforms

    Energy Technology Data Exchange (ETDEWEB)

    Shan, Hongzhan; Austin, Brian M.; De Jong, Wibe A.; Oliker, Leonid; Wright, Nicholas J.; Apra, Edoardo

    2014-10-01

    Attaining performance in the evaluation of two-electron repulsion integrals and constructing the Fock matrix is of considerable importance to the computational chemistry community. Due to its numerical complexity improving the performance behavior across a variety of leading supercomputing platforms is an increasing challenge due to the significant diversity in high-performance computing architectures. In this paper, we present our successful tuning methodology for these important numerical methods on the Cray XE6, the Cray XC30, the IBM BG/Q, as well as the Intel Xeon Phi. Our optimization schemes leverage key architectural features including vectorization and simultaneous multithreading, and results in speedups of up to 2.5x compared with the original implementation.

  20. Modified electron-acoustic and lower-hybrid drift dissipative instability in a two-electron temperature plasma

    International Nuclear Information System (INIS)

    Bose, M.

    1989-01-01

    It is often found, in fusion devices as well as in the auroral ionosphere, that the electrons consist of two distinct group, viz., hot and cold. These two-temperature electron model is sometimes convenient for analytical purposes. Thus the authors have considered a two-temperature electron plasma. In this paper, they investigated analytically the drift dissipative instabilities of modified electron-acoustic and lower-hybrid wve in a two-electron temperature plasma. It is found that the modified electron-acoustic drift dissipative mode are strongly dependent on the number density of cold electrons. From the expression of the growth rate, it is clear that these cold electrons can control the growth of this mode as well

  1. Correlated kinetic energy density functional of ground states of harmonically confined two-electron atoms for arbitrary interparticle interaction

    International Nuclear Information System (INIS)

    Amovilli, C; March, N H

    2012-01-01

    Utilizing the earlier work of Holas et al (2003 Phys. Lett. A 310 451) and the more recent contribution of Akbari et al (2009 Phys. Rev. A 80 032509), we construct an integral equation for the relative motion (RM) contribution t RM (r) to the correlated kinetic energy density for modelling two-electron atoms with harmonic confinement but arbitrary interparticle interaction. It is stressed that t RM = t RM [f(G)], where f(G) is the atomic scattering factor: the Fourier transform of the density ρ(r). As a simple illustrative example of this functional relation for the correlated kinetic energy density, the harmonic Moshinsky case is investigated, the scattering factor then having a Gaussian form. (paper)

  2. Two-electron excitation in slow ion-atom collisions: Excitation mechanisms and interferences among autoionizing states

    International Nuclear Information System (INIS)

    Kimura, M.; Rice Univ., Houston, TX

    1990-01-01

    The two-electron capture or excitation process resulting from collisions of H + and O 6+ ions with He atoms in the energy range from 0.5 keV/amu to 5 keV/amu is studied within a molecular representation. The collision dynamics for formation of doubly excited O 4+ ions and He** atoms and their (n ell, n'ell ') populations are analyzed in conjunction with electron correlations. Autoionizing states thus formed decay through the Auger process. An experimental study of an ejected electron energy spectrum shows ample structures in addition to two characteristic peaks that are identified by atomic and molecular autoionizations. These structures are attributable to various interferences among electronic states and trajectories. We examine the dominant sources of the interferences. 12 refs., 5 figs

  3. Entanglement dynamics of two electron-spin qubits in a strongly detuned and dissipative quantum-dot-cavity system

    International Nuclear Information System (INIS)

    Xiang Shaohua; Deng Xiaopeng; Song Kehui; Wen Wei; Shi Zhengang

    2011-01-01

    We investigate the entanglement dynamics of two electron-spin qubits in the quantum-dot (QD)-microcavity system in the large-detuning limit and subjected to two different noise sources: electron-spin dephasing and relaxation. We show that when one of the two dots is prepared initially in the excited state, the created entanglement exhibits oscillatory behavior at the beginning of evolution and then completely disappears over time. For two QDs that are initially in either the Einstein-Podolsky-Rosen-Bell states or the Werner states, their entanglement evolution exhibits the same behavior in the presence of pure dephasing, but is completely different under the relaxation process. We also show that the interdot interaction induced by a single-mode cavity field does not contribute to the dynamics of entanglement for these Bell states and Werner states.

  4. Reflection-time-of-flight spectrometer for two-electron (e,2e) coincidence spectroscopy on surfaces

    International Nuclear Information System (INIS)

    Kirschner, J.; Kerherve, G.; Winkler, C.

    2008-01-01

    In this article, a novel time-of-flight spectrometer for two-electron-emission (e,2e/γ,2e) correlation spectroscopy from surfaces at low electron energies is presented. The spectrometer consists of electron optics that collect emitted electrons over a solid angle of approximately 1 sr and focus them onto a multichannel plate using a reflection technique. The flight time of an electron with kinetic energy of E kin ≅25 eV is around 100 ns. The corresponding time- and energy resolution are typically ≅1 ns and ≅0.65 eV, respectively. The first (e,2e) data obtained with the present setup from a LiF film are presented

  5. Effect of Temperature and Pressure on Correlation Energy in a Triplet State of a Two Electron Spherical Quantum Dot

    Directory of Open Access Journals (Sweden)

    A. Rejo Jeice

    2013-09-01

    Full Text Available The combined effect of hydrostatic pressure and temperature on correlation energy in a triplet state of two electron spherical quantum dot with square well potential is computed. The result is presented taking GaAs dot as an example. Our result shows the correlation energies are inegative in the triplet state contrast to the singlet state ii it increases with increase in pressure  iiifurther decreases due to the application  of temperature iv it approaches zero as dot size approaches infinity and v it contribute 10% decrement in total confined energy to the narrow dots. All the calculations have been carried out with finite models and the results are compared with existing literature.

  6. Particle dynamics and current-free double layers in an expanding, collisionless, two-electron-population plasma

    International Nuclear Information System (INIS)

    Hairapetian, G.; Stenzel, R.L.

    1991-01-01

    The expansion of a two-electron-population, collisionless plasma into vacuum is investigated experimentally. Detailed in situ measurements of plasma density, plasma potential, electric field, and particle distribution functions are performed. At the source, the electron population consists of a high-density, cold (kT e congruent 4 eV) Maxwellian, and a sparse, energetic ( (1)/(2) mv 2 e congruent 80 eV) tail. During the expansion of plasma, space-charge effects self-consistently produce an ambipolar electric field whose amplitude is controlled by the energy of tail electrons. The ambipolar electric field accelerates a small number (∼1%) of ions to streaming energies which exceed and scale linearly with the energy of tail electrons. As the expansion proceeds, the energetic tail electrons electrostatically trap the colder Maxwellian electrons and prevent them from reaching the expansion front. A potential double layer develops at the position of the cold electron front. Upstream of the double layer both electron populations exist; but downstream, only the tail electrons do. Hence, the expansion front is dominated by retarded tail electrons. Initially, the double layer propagates away from the source with a speed approximately equal to the ion sound speed in the cold electron population. The propagation speed is independent of the tail electron energy. At later times, the propagating double layer slows down and eventually stagnates. The final position and amplitude of the double layer are controlled by the relative densities of the two electron populations in the source. The steady-state double layer persists till the end of the discharge (Δt congruent 1 msec), much longer than the ion transit time through the device (t congruent 150 μsec)

  7. Compact two-electron wave function for bond dissociation and Van der Waals interactions: a natural amplitude assessment.

    Science.gov (United States)

    Giesbertz, Klaas J H; van Leeuwen, Robert

    2014-05-14

    Electron correlations in molecules can be divided in short range dynamical correlations, long range Van der Waals type interactions, and near degeneracy static correlations. In this work, we analyze for a one-dimensional model of a two-electron system how these three types of correlations can be incorporated in a simple wave function of restricted functional form consisting of an orbital product multiplied by a single correlation function f (r12) depending on the interelectronic distance r12. Since the three types of correlations mentioned lead to different signatures in terms of the natural orbital (NO) amplitudes in two-electron systems, we make an analysis of the wave function in terms of the NO amplitudes for a model system of a diatomic molecule. In our numerical implementation, we fully optimize the orbitals and the correlation function on a spatial grid without restrictions on their functional form. Due to this particular form of the wave function, we can prove that none of the amplitudes vanishes and moreover that it displays a distinct sign pattern and a series of avoided crossings as a function of the bond distance in agreement with the exact solution. This shows that the wave function ansatz correctly incorporates the long range Van der Waals interactions. We further show that the approximate wave function gives an excellent binding curve and is able to describe static correlations. We show that in order to do this the correlation function f (r12) needs to diverge for large r12 at large internuclear distances while for shorter bond distances it increases as a function of r12 to a maximum value after which it decays exponentially. We further give a physical interpretation of this behavior.

  8. electrocatalytic reduction of oxygen at vapor phase polymerized poly ...

    African Journals Online (AJOL)

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    In all fuel cell devices, the reduction of O2 to H2O plays a critical role. The sluggish nature of the oxygen reduction reaction requires an expensive electrocatalyst like platinum. The high .... equations. The Levich equation is expressed as equation 1: ... solution is not a two electron reaction via the formation of H2O2. Similar ...

  9. Magnetic field manipulation of spin current in a single-molecule magnet tunnel junction with two-electron Coulomb interaction

    Science.gov (United States)

    Zhang, Chao; Yao, Hui; Nie, Yi-Hang; Liang, Jiu-Qing; Niu, Peng-Bin

    2018-04-01

    In this work, we study the generation of spin-current in a single-molecule magnet (SMM) tunnel junction with Coulomb interaction of transport electrons and external magnetic field. In the absence of field the spin-up and -down currents are symmetric with respect to the initial polarizations of molecule. The existence of magnetic field breaks the time-reversal symmetry, which leads to unsymmetrical spin currents of parallel and antiparallel polarizations. Both the amplitude and polarization direction of spin current can be controlled by the applied magnetic field. Particularly when the magnetic field increases to a certain value the spin-current with antiparallel polarization is reversed along with the magnetization reversal of the SMM. The two-electron occupation indeed enhances the transport current compared with the single-electron process. However the increase of Coulomb interaction results in the suppression of spin-current amplitude at the electron-hole symmetry point. We propose a scheme to compensate the suppression with the magnetic field.

  10. On the enhancement of the back-to-back two-electron-one photon ionization in molecules

    Science.gov (United States)

    Amusia, Miron; Drukarev, Eugene

    2014-05-01

    Recently, the long ago predicted quasi-free mechanism of two-electron photoionization was detected already at relatively low energy photoionization in He. It was observed that some pairs of electrons are leaving the target atom back-to-back, i.e. in opposite direction with almost the same energy. They have opposite spin directions. The cross-section of this process depends upon the probability for a pair of electrons to be close to each other before meeting the incoming photon. Such probability is greatly enhanced in molecules with covalent bonding, like H2. In this and similar molecules the electrons spend an essential part of time being between nuclei and thus screening them from each other. We demonstrate that indeed the back-to-back contribution is much bigger in H2 than in He. We analyze qualitatively some other situations that lead to relative growth of back-to-back contribution. Atoms with electrons with bigger principal quantum numbers have bigger back-to-back contributions. An external pressure applied to molecules forces electrons to be closer to each other. As a result for them the back-to-back contribution can be controllable enhanced.

  11. Time-dependent reduced density matrix functional theory applied to laser-driven, correlated two-electron dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Brics, Martins; Kapoor, Varun; Bauer, Dieter [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany)

    2013-07-01

    Time-dependent density functional theory (TDDFT) with known and practicable exchange-correlation potentials does not capture highly correlated electron dynamics such as single-photon double ionization, autoionization, or nonsequential ionization. Time-dependent reduced density matrix functional theory (TDRDMFT) may remedy these problems. The key ingredients in TDRDMFT are the natural orbitals (NOs), i.e., the eigenfunctions of the one-body reduced density matrix (1-RDM), and the occupation numbers (OCs), i.e., the respective eigenvalues. The two-body reduced density matrix (2-RDM) is then expanded in NOs, and equations of motion for the NOs can be derived. If the expansion coefficients of the 2-RDM were known exactly, the problem at hand would be solved. In practice, approximations have to be made. We study the prospects of TDRDMFT following a top-down approach. We solve the exact two-electron time-dependent Schroedinger equation for a model Helium atom in intense laser fields in order to study highly correlated phenomena such as the population of autoionizing states or single-photon double ionization. From the exact wave function we calculate the exact NOs, OCs, the exact expansion coefficients of the 2-RDM, and the exact potentials in the equations of motion. In that way we can identify how many NOs and which level of approximations are necessary to capture such phenomena.

  12. A π-Conjugation Extended Viologen as a Two-Electron Storage Anolyte for Total Organic Aqueous Redox Flow Batteries.

    Science.gov (United States)

    Luo, Jian; Hu, Bo; Debruler, Camden; Liu, Tianbiao Leo

    2018-01-02

    Extending the conjugation of viologen by a planar thiazolo[5,4-d]thiazole (TTz) framework and functionalizing the pyridinium with hydrophilic ammonium groups yielded a highly water-soluble π-conjugation extended viologen, 4,4'-(thiazolo[5,4-d]thiazole-2,5-diyl)bis(1-(3-(trimethylammonio)propyl)pyridin-1-ium) tetrachloride, [(NPr) 2 TTz]Cl 4  , as a novel two-electron storage anolyte for aqueous organic redox flow battery (AORFB) applications. Its physical and electrochemical properties were systematically investigated. Paired with 4-trimethylammonium-TEMPO (N Me -TEMPO) as catholyte, [(NPr) 2 TTz]Cl 4 enables a 1.44 V AORFB with a theoretical energy density of 53.7 Wh L -1 . A demonstrated [(NPr) 2 TTz]Cl 4 /N Me -TEMPO AORFB delivered an energy efficiency of 70 % and 99.97 % capacity retention per cycle. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Reduction redux.

    Science.gov (United States)

    Shapiro, Lawrence

    2018-04-01

    Putnam's criticisms of the identity theory attack a straw man. Fodor's criticisms of reduction attack a straw man. Properly interpreted, Nagel offered a conception of reduction that captures everything a physicalist could want. I update Nagel, introducing the idea of overlap, and show why multiple realization poses no challenge to reduction so construed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Rank restriction for the variational calculation of two-electron reduced density matrices of many-electron atoms and molecules

    International Nuclear Information System (INIS)

    Naftchi-Ardebili, Kasra; Hau, Nathania W.; Mazziotti, David A.

    2011-01-01

    Variational minimization of the ground-state energy as a function of the two-electron reduced density matrix (2-RDM), constrained by necessary N-representability conditions, provides a polynomial-scaling approach to studying strongly correlated molecules without computing the many-electron wave function. Here we introduce a route to enhancing necessary conditions for N representability through rank restriction of the 2-RDM. Rather than adding computationally more expensive N-representability conditions, we directly enhance the accuracy of two-particle (2-positivity) conditions through rank restriction, which removes degrees of freedom in the 2-RDM that are not sufficiently constrained. We select the rank of the particle-hole 2-RDM by deriving the ranks associated with model wave functions, including both mean-field and antisymmetrized geminal power (AGP) wave functions. Because the 2-positivity conditions are exact for quantum systems with AGP ground states, the rank of the particle-hole 2-RDM from the AGP ansatz provides a minimum for its value in variational 2-RDM calculations of general quantum systems. To implement the rank-restricted conditions, we extend a first-order algorithm for large-scale semidefinite programming. The rank-restricted conditions significantly improve the accuracy of the energies; for example, the percentages of correlation energies recovered for HF, CO, and N 2 improve from 115.2%, 121.7%, and 121.5% without rank restriction to 97.8%, 101.1%, and 100.0% with rank restriction. Similar results are found at both equilibrium and nonequilibrium geometries. While more accurate, the rank-restricted N-representability conditions are less expensive computationally than the full-rank conditions.

  15. Electron-electron interaction in strong electromagnetic fields The two-electron contribution to the ground-state energy in He-like uranium

    CERN Document Server

    Gumberidze, A; Barnás, D; Beckert, Karl; Beller, Peter; Beyer, H F; Bosch, F; Cai, X; Stöhlker, T; Hagmann, S; Kozhuharov, C; Liesen, D; Nolden, F; Ma, X; Mokler, P H; Orsic-Muthig, A; Steck, Markus; Sierpowski, D; Tashenov, S; Warczak, A; Zou, Y

    2004-01-01

    Radiative recombination transitions into the ground state of cooled bare and hydrogen-like uranium ions were measured at the storage ring ESR. By comparing the corresponding x-ray centroid energies, this technique allows for a direct measurement of the electron-electron contribution to the ionization potential in the heaviest He-like ions. For the two-electron contribution to the ionization potential of He-like uranium we obtain a value of 2248 ± 9 eV. This represents the most accurate determination of two-electron effects in the domain of high-Z He-like ions and the accuracy reaches already the size of the specific two-electron radiative QED corrections.

  16. Wave functions and low-order density matrices for a class of two-electron 'artificial atoms' embracing Hookean and Moshinsky models

    International Nuclear Information System (INIS)

    Holas, A.; Howard, I.A.; March, N.H.

    2003-01-01

    A class of model two-electron 'artificial atoms' is proposed which embraces both Hookean and Moshinsky models. Particle densities and spinless first-order density matrices are obtained for this class of models. These quantities and the interacting system kinetic energy can be calculated using the ground-state solution of an explicit single-particle radial Schroedinger equation

  17. Energy spectra and oscillatory magnetization of two-electron self-assembled Inx Ga1-x As quantum rings in GaAs

    NARCIS (Netherlands)

    Fomin, V.M.; Gladilin, V.N.; Devreese, J.T.; Kleemans, N.A.J.M.; Koenraad, P.M.

    2008-01-01

    The effects of the Coulomb interaction on the energy spectrum and the magnetization of two electrons in a strained Inx Ga1-x As/GaAs ringlike nanostructure are analyzed with realistic parameters inferred from the cross-sectional scanning-tunneling microscopy data. With an increasing magnetic field,

  18. The autoprotonation in reduction mechanism of pesticide ioxynil

    Energy Technology Data Exchange (ETDEWEB)

    Sokolova, Romana, E-mail: sokolova@jh-inst.cas.c [J. Heyrovsky Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague (Czech Republic); Hromadova, Magdalena; Ludvik, Jiri; Pospisil, Lubomir [J. Heyrovsky Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague (Czech Republic); Giannarelli, Stefania [Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56100 Pisa (Italy)

    2010-11-30

    The reduction mechanism of ioxynil (3,5-diiodo-4-hydroxy-benzonitrile) was studied in dimethylsulfoxide using the electrochemical methods (tast polarography, cyclic voltammetry and controlled potential electrolysis) combined with GC/MS identification of products. The reduction is accompanied by the cleavage of iodide yielding 3-iodo-4-hydroxybenzonitrile. Surprisingly, this process requires only one electron for the exhaustive electrolysis of the starting compound. We showed that the apparent one electron reduction observed in the aprotic solvent is due to the autoprotonation by another molecule of ioxynil. The overall one electron reduction (uptake of two electrons per two molecules of ioxynil) is changed in the presence of a strong proton donor to a two electron process per one molecule.

  19. Metastable He2- ions formed by two-electron attachment to the excited He2+ Σg+ (1σg22σg1) core

    International Nuclear Information System (INIS)

    Adamowicz, L.; Pluta, T.

    1991-01-01

    Four metastable states (1 4 Π u , 2 4 Π u , 4 Φ u , and 4 I u ), resulting from two-electron attachments to the excited He 2 + core ( 2 Σ g + ), are characterized using the numerical Hartree-Fock method. It is determined that such metastable states are formed when both valence electrons are placed into equally diffused orbitals, which have bonding charter, and whose angular momentum quantum numbers do not differ by more than 1

  20. Hartree-Fock implementation using a Laguerre-based wave function for the ground state and correlation energies of two-electron atoms.

    Science.gov (United States)

    King, Andrew W; Baskerville, Adam L; Cox, Hazel

    2018-03-13

    An implementation of the Hartree-Fock (HF) method using a Laguerre-based wave function is described and used to accurately study the ground state of two-electron atoms in the fixed nucleus approximation, and by comparison with fully correlated (FC) energies, used to determine accurate electron correlation energies. A variational parameter A is included in the wave function and is shown to rapidly increase the convergence of the energy. The one-electron integrals are solved by series solution and an analytical form is found for the two-electron integrals. This methodology is used to produce accurate wave functions, energies and expectation values for the helium isoelectronic sequence, including at low nuclear charge just prior to electron detachment. Additionally, the critical nuclear charge for binding two electrons within the HF approach is calculated and determined to be Z HF C =1.031 177 528.This article is part of the theme issue 'Modern theoretical chemistry'. © 2018 The Author(s).

  1. Reduction corporoplasty.

    Science.gov (United States)

    Hakky, Tariq S; Martinez, Daniel; Yang, Christopher; Carrion, Rafael E

    2015-01-01

    Here we present the first video demonstration of reduction corporoplasty in the management of phallic disfigurement in a 17 year old man with a history sickle cell disease and priapism. Surgical management of aneurysmal dilation of the corpora has yet to be defined in the literature. We preformed bilateral elliptical incisions over the lateral corpora as management of aneurysmal dilation of the corpora to correct phallic disfigurement. The patient tolerated the procedure well and has resolution of his corporal disfigurement. Reduction corporoplasty using bilateral lateral elliptical incisions in the management of aneurysmal dilation of the corpora is a safe an feasible operation in the management of phallic disfigurement.

  2. Comparative evaluation of accuracy of two electronic apex locators in the presence of various irrigants: An in vitro study

    Directory of Open Access Journals (Sweden)

    Saru Jain

    2012-01-01

    Full Text Available Context: The establishment of appropriate working length is one of the most critical steps in endodontic therapy. Electronic apex locators have been introduced to determine the working length. The development of electronic apex locators has helped make the assessment of the working length more accurate and predictable, along with reduction in treatment time and radiation dose. Objectives: The aim of this study was to compare the efficacy of electronic apex locators after cleansing and shaping of the root canals and whether there was any alteration in accuracy when used in the presence of irrigants. Materials and Methods: Seventy extracted human permanent molars with mature apices were selected. Equal number of maxillary and mandibular permanent molars (35 each were sectioned at the cemento-enamel junction. Access opening was done and only the mesiobuccal root canal was studied for the purpose of standardization. Electronic working length measurements were taken before and after preparation of the mesiobuccal canal with Root ZX and ProPex II using various irrigants. Statistical Analysis Used: The data were statistically analyzed using a paired t-test at 0.05 level of significance. Results: P-values for actual and final canal lengths for Root ZX employing NaoCl(0.001, CHX(0.006, LA(0.020 and for ProPex II was (0.001 respectively. When the data were compared, results were statistically significant (P < 0.05. Conclusion: Within the limitations of this study Root ZX can be considered to be an accurate electronic apex locator and CHX as irrigant matched more precisely with the actual canal length measurements.

  3. Reduction Corporoplasty

    Directory of Open Access Journals (Sweden)

    Tariq S. Hakky

    2015-04-01

    Full Text Available Objective Here we present the first video demonstration of reduction corporoplasty in the management of phallic disfigurement in a 17 year old man with a history sickle cell disease and priapism. Introduction Surgical management of aneurysmal dilation of the corpora has yet to be defined in the literature. Materials and Methods: We preformed bilateral elliptical incisions over the lateral corpora as management of aneurysmal dilation of the corpora to correct phallic disfigurement. Results The patient tolerated the procedure well and has resolution of his corporal disfigurement. Conclusions Reduction corporoplasty using bilateral lateral elliptical incisions in the management of aneurysmal dilation of the corpora is a safe an feasible operation in the management of phallic disfigurement.

  4. Metal-free reduction of the greenhouse gas sulfur hexafluoride, formation of SF5 containing ion pairs and the application in fluorinations

    KAUST Repository

    Rueping, Magnus; Nikolaienko, Pavlo; Lebedev, Yury; Adams, Alina

    2017-01-01

    A protocol for the fast and selective two-electron reduction of the potent greenhouse gas sulfur hexafluoride (SF6) by organic electron donors at ambient temperature has been developed. The reaction yields solid ion pairs consisting of donor

  5. Snubber reduction

    International Nuclear Information System (INIS)

    Olson, D.E.; Singh, A.K.

    1986-01-01

    Many safety-related piping systems in nuclear power plants have been oversupported. Since snubbers make up a large percentage of the pipe supports or restraints used in a plant, a plant's snubber population is much larger than required to adequately restrain the piping. This has resulted in operating problems and unnecessary expenses for maintenance and inservice inspections (ISIs) of snubbers. This paper presents an overview of snubber reduction, including: the incentives for removing snubbers, a historical perspective on how piping became oversupported, why it is possible to remove snubbers, and the costs and benefits of doing so

  6. Electron Transfer Pathways Facilitating U(VI) Reduction by Fe(II) on Al- vs Fe-Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, S. D. [Pacific Northwest National Laboratory, Physical Sciences Division, P.O. Box; Becker, U. [The University of Michigan, Department of Earth; Rosso, K. M. [Pacific Northwest National Laboratory, Physical Sciences Division, P.O. Box

    2017-09-06

    This study continues mechanistic development of heterogeneous electron transfer (ET) pathways at mineral surfaces in aquatic environments that enable the reduction U(VI) by surface-associated Fe(II). Using computational molecular simulation within the framework of Marcus Theory, our findings highlight the importance of the configurations and interaction of the electron donor and acceptor species with the substrate, with respect to influencing its electronic structure and thereby the ability of semiconducting minerals to facilitate ET. U(VI) reduction by surface-associated Fe(II) (adsorbed or structurally incorporated into the lattice) on an insulating, corundum (001) surface (α-Al2O3) occurs when proximal inner-sphere (IS) surface complexes are formed, such that ET occurs through a combination of direct exchange (i.e., Fe d- and U f-orbitals overlap through space) and superexchange via intervening surface oxygen atoms. U(VI) reduction by coadsorbed Fe(II) on the isostructural semiconducting hematite (α-Fe2O3) basal surface requires either their direct electronic interaction (e.g., IS complexation) or mediation of this interaction indirectly through the surface via an intrasurface pathway. Conceptually possible longer-range ET by charge-hopping through surface Fe atoms was investigated to determine whether this indirect pathway is competitive with direct ET. The calculations show that energy barriers are large for this conduction-based pathway; interfacial ET into the hematite surface is endothermic (+80.1 kJ/mol) and comprises the rate-limiting step (10–6 s–1). The presence of the IS adsorbates appears to weaken the electronic coupling between underlying Fe ions within the surface, resulting in slower intra-surface ET (10–5 s–1) than expected in the bulk basal plane. Our findings lay out first insights into donor-acceptor communication via a charge-hopping pathway through the surface for heterogeneous reduction of U(VI) by Fe(II) and help provide a basis

  7. Radon reduction

    International Nuclear Information System (INIS)

    Hamilton, M.A.

    1990-01-01

    During a radon gas screening program, elevated levels of radon gas were detected in homes on Mackinac Island, Mich. Six homes on foundations with crawl spaces were selected for a research project aimed at reducing radon gas concentrations, which ranged from 12.9 to 82.3 pCi/l. Using isolation and ventilation techniques, and variations thereof, radon concentrations were reduced to less than 1 pCi/l. This paper reports that these reductions were achieved using 3.5 mil cross laminated or 10 mil high density polyethylene plastic as a barrier without sealing to the foundation or support piers, solid and/or perforated plastic pipe and mechanical fans. Wind turbines were found to be ineffective at reducing concentrations to acceptable levels. Homeowners themselves installed all materials

  8. Theoretical treatment of electron capture and excitation in two-electron system ion-atom, atom-atom collisions at low to intermediate energy

    International Nuclear Information System (INIS)

    Kimura, M.

    1986-01-01

    A review of various theoretical treatments which have been used to study electron-capture and excitation processes in two-electron-system ion-atom, atom-atom collisions at low to intermediate energy is presented. Advantages as well as limitations associated with these theoretical models in application to practical many-electron ion-atom, atom-atom collisions are specifically pointed out. Although a rigorous theoretical study of many-electron systems has just begun so that reports of theoretical calculations are scarce to date in comparison to flourishing experimental activities, some theoretical results are of great interest and provide important information for understanding collision dynamics of the system which contains many electrons. Selected examples are given for electron capture in a multiply charged ion-He collision, ion-pair formation in an atom-atom collision and alignment and orientation in a Li + + He collision. (Auth.)

  9. Inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    NARCIS (Netherlands)

    Ridley, M.K.; Hiemstra, T.; Riemsdijk, van W.H.; Machesky, M.L.

    2009-01-01

    Acid–base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in

  10. N-representability-driven reconstruction of the two-electron reduced-density matrix for a real-time time-dependent electronic structure method

    International Nuclear Information System (INIS)

    Jeffcoat, David B.; DePrince, A. Eugene

    2014-01-01

    Propagating the equations of motion (EOM) for the one-electron reduced-density matrix (1-RDM) requires knowledge of the corresponding two-electron RDM (2-RDM). We show that the indeterminacy of this expression can be removed through a constrained optimization that resembles the variational optimization of the ground-state 2-RDM subject to a set of known N-representability conditions. Electronic excitation energies can then be obtained by propagating the EOM for the 1-RDM and following the dipole moment after the system interacts with an oscillating external electric field. For simple systems with well-separated excited states whose symmetry differs from that of the ground state, excitation energies obtained from this method are comparable to those obtained from full configuration interaction computations. Although the optimized 2-RDM satisfies necessary N-representability conditions, the procedure cannot guarantee a unique mapping from the 1-RDM to the 2-RDM. This deficiency is evident in the mean-field-quality description of transitions to states of the same symmetry as the ground state, as well as in the inability of the method to describe Rabi oscillations

  11. N-representability-driven reconstruction of the two-electron reduced-density matrix for a real-time time-dependent electronic structure method

    Science.gov (United States)

    Jeffcoat, David B.; DePrince, A. Eugene

    2014-12-01

    Propagating the equations of motion (EOM) for the one-electron reduced-density matrix (1-RDM) requires knowledge of the corresponding two-electron RDM (2-RDM). We show that the indeterminacy of this expression can be removed through a constrained optimization that resembles the variational optimization of the ground-state 2-RDM subject to a set of known N-representability conditions. Electronic excitation energies can then be obtained by propagating the EOM for the 1-RDM and following the dipole moment after the system interacts with an oscillating external electric field. For simple systems with well-separated excited states whose symmetry differs from that of the ground state, excitation energies obtained from this method are comparable to those obtained from full configuration interaction computations. Although the optimized 2-RDM satisfies necessary N-representability conditions, the procedure cannot guarantee a unique mapping from the 1-RDM to the 2-RDM. This deficiency is evident in the mean-field-quality description of transitions to states of the same symmetry as the ground state, as well as in the inability of the method to describe Rabi oscillations.

  12. Local unitary transformation method for large-scale two-component relativistic calculations. II. Extension to two-electron Coulomb interaction.

    Science.gov (United States)

    Seino, Junji; Nakai, Hiromi

    2012-10-14

    The local unitary transformation (LUT) scheme at the spin-free infinite-order Douglas-Kroll-Hess (IODKH) level [J. Seino and H. Nakai, J. Chem. Phys. 136, 244102 (2012)], which is based on the locality of relativistic effects, has been extended to a four-component Dirac-Coulomb Hamiltonian. In the previous study, the LUT scheme was applied only to a one-particle IODKH Hamiltonian with non-relativistic two-electron Coulomb interaction, termed IODKH/C. The current study extends the LUT scheme to a two-particle IODKH Hamiltonian as well as one-particle one, termed IODKH/IODKH, which has been a real bottleneck in numerical calculation. The LUT scheme with the IODKH/IODKH Hamiltonian was numerically assessed in the diatomic molecules HX and X(2) and hydrogen halide molecules, (HX)(n) (X = F, Cl, Br, and I). The total Hartree-Fock energies calculated by the LUT method agree well with conventional IODKH/IODKH results. The computational cost of the LUT method is reduced drastically compared with that of the conventional method. In addition, the LUT method achieves linear-scaling with respect to the system size and a small prefactor.

  13. Top-Down Charge Transfer Dissociation (CTD) of Gas-Phase Insulin: Evidence of a One-Step, Two-Electron Oxidation Mechanism

    Science.gov (United States)

    Li, Pengfei; Kreft, Iris; Jackson, Glen P.

    2018-02-01

    Top-down analyses of protonated insulin cations of charge states of 4+, 5+, or 6+ were performed by exposing the isolated precursor ions to a beam of helium cations with kinetic energy of more than 6 keV, in a technique termed charge transfer dissociation (CTD). The 100 ms charge transfer reaction resulted in approximately 20% conversion efficiency to other intact charge exchange products (CTnoD), and a range of low abundance fragment ions. To increase backbone and sulfide cleavages, and to provide better structural information than straightforward MS2 CTD, the CTnoD oxidized products were isolated and subjected to collisional activation at the MS3 level. The MS3 CTD/CID reaction effectively broke the disulfide linkages, separated the two chains, and yielded more structurally informative fragment ions within the inter-chain cyclic region. CTD also provided doubly oxidized intact product ions at the MS2 level, and resonance ejection of the singly oxidized product ion revealed that the doubly oxidized product originates directly from the isolated precursor ion and not from consecutive CTD reactions of a singly oxidized intermediate. MS4 experiments were employed to help identify potential radical cations and diradical cations, but the results were negative or inconclusive. Nonetheless, the two-electron oxidation process is a demonstration of the very large potential energy (>20 eV) available through CTD, and is a notable capability for a 3D ion trap platform.

  14. Characterization of high-energy photoionization in terms of the singularities of the atomic potential. I. Photoionization of the ground state of a two-electron atom

    International Nuclear Information System (INIS)

    Suric, T.; Drukarev, E.G.; Pratt, R.H.

    2003-01-01

    We describe single and double photoionization of two-electron atoms by photoabsorption at high incident photon energies ω (but still ω 2 ) using a unified approach based on asymptotic Fourier transform (AFT) theory modified by Coulombic interactions. Within this approach the matrix elements for photoabsorption processes at high energies can be understood in terms of the singularities of the many-body Coulomb potential. These singularities (e-e and e-N) result in the singularities of the wave functions and the singularities of the e-γ interaction, which determine the asymptotic behavior of the matrix element. Within our unified approach we explain the dominant contributions, including both the dominant contributions to the total cross section for single ionization and for ionization with excitation, and the dominant contributions to the double ionization spectrum, as a Fourier transform asymptotic in a single large momentum (dependent on the process and the region of the spectrum). These dominant contributions are connected, through AFT, with either the e-N singularity or the e-e singularity. The AFT results are modified by Coulombic interactions. We include these modifications, for the cases of single ionization and of double ionization in the shake-off region at high energies, and extract a slowly convergent factor (Stobbe factor). In this way we obtain rapid convergence of the cross sections to their high-energy behaviors. This also allows us to discuss the convergence of ratios of cross sections

  15. Strong correlation in acene sheets from the active-space variational two-electron reduced density matrix method: effects of symmetry and size.

    Science.gov (United States)

    Pelzer, Kenley; Greenman, Loren; Gidofalvi, Gergely; Mazziotti, David A

    2011-06-09

    Polyaromatic hydrocarbons (PAHs) are a class of organic molecules with importance in several branches of science, including medicine, combustion chemistry, and materials science. The delocalized π-orbital systems in PAHs require highly accurate electronic structure methods to capture strong electron correlation. Treating correlation in PAHs has been challenging because (i) traditional wave function methods for strong correlation have not been applicable since they scale exponentially in the number of strongly correlated orbitals, and (ii) alternative methods such as the density-matrix renormalization group and variational two-electron reduced density matrix (2-RDM) methods have not been applied beyond linear acene chains. In this paper we extend the earlier results from active-space variational 2-RDM theory [Gidofalvi, G.; Mazziotti, D. A. J. Chem. Phys. 2008, 129, 134108] to the more general two-dimensional arrangement of rings--acene sheets--to study the relationship between geometry and electron correlation in PAHs. The acene-sheet calculations, if performed with conventional wave function methods, would require wave function expansions with as many as 1.5 × 10(17) configuration state functions. To measure electron correlation, we employ several RDM-based metrics: (i) natural-orbital occupation numbers, (ii) the 1-RDM von Neumann entropy, (iii) the correlation energy per carbon atom, and (iv) the squared Frobenius norm of the cumulant 2-RDM. The results confirm a trend of increasing polyradical character with increasing molecular size previously observed in linear PAHs and reveal a corresponding trend in two-dimensional (arch-shaped) PAHs. Furthermore, in PAHs of similar size they show significant variations in correlation with geometry. PAHs with the strictly linear geometry (chains) exhibit more electron correlation than PAHs with nonlinear geometries (sheets).

  16. Finding optimal exact reducts

    KAUST Repository

    AbouEisha, Hassan M.

    2014-01-01

    The problem of attribute reduction is an important problem related to feature selection and knowledge discovery. The problem of finding reducts with minimum cardinality is NP-hard. This paper suggests a new algorithm for finding exact reducts

  17. Breast Reduction Surgery

    Science.gov (United States)

    ... considering breast reduction surgery, consult a board-certified plastic surgeon. It's important to understand what breast reduction surgery entails — including possible risks and complications — as ...

  18. Infinitary Combinatory Reduction Systems: Normalising Reduction Strategies

    NARCIS (Netherlands)

    Ketema, J.; Simonsen, Jakob Grue

    2010-01-01

    We study normalising reduction strategies for infinitary Combinatory Reduction Systems (iCRSs). We prove that all fair, outermost-fair, and needed-fair strategies are normalising for orthogonal, fully-extended iCRSs. These facts properly generalise a number of results on normalising strategies in

  19. Reduction in language testing

    DEFF Research Database (Denmark)

    Dimova, Slobodanka; Jensen, Christian

    2013-01-01

    /video recorded speech samples and written reports produced by two experienced raters after testing. Our findings suggest that reduction or reduction-like pronunciation features are found in tested L2 speech, but whenever raters identify and comment on such reductions, they tend to assess reductions negatively......This study represents an initial exploration of raters' comments and actual realisations of form reductions in L2 test speech performances. Performances of three L2 speakers were selected as case studies and illustrations of how reductions are evaluated by the raters. The analysis is based on audio...

  20. MCNP variance reduction overview

    International Nuclear Information System (INIS)

    Hendricks, J.S.; Booth, T.E.

    1985-01-01

    The MCNP code is rich in variance reduction features. Standard variance reduction methods found in most Monte Carlo codes are available as well as a number of methods unique to MCNP. We discuss the variance reduction features presently in MCNP as well as new ones under study for possible inclusion in future versions of the code

  1. Modern Reduction Methods

    CERN Document Server

    Andersson, Pher G

    2008-01-01

    With its comprehensive overview of modern reduction methods, this book features high quality contributions allowing readers to find reliable solutions quickly and easily. The monograph treats the reduction of carbonyles, alkenes, imines and alkynes, as well as reductive aminations and cross and heck couplings, before finishing off with sections on kinetic resolutions and hydrogenolysis. An indispensable lab companion for every chemist.

  2. Detection of two electrons in low-lying continuum states of a single projectile ion resulting from the collision of a 10.7-MeV Ag4+ ion with an Ar gas atom

    International Nuclear Information System (INIS)

    Richards, J.D.; Breinig, M.; Gaither, C.C.; Berryman, J.W.; Hasson, B.F.

    1993-01-01

    Two electrons, excited just above the double-ionization threshold of an Ag q+ (q=5,6) core in a single collision of a 0.1-MeV/u Ag 4+ projectile ion with an Ar atom, are detected. The electron detector consists of electrically isolated anode segments located behind a microchannel-plate electron multiplier. A large electrostatic 30 degree parallel-plate analyzer is used to deflect the two free electrons, which move with approximately the projectile velocity, into the detector. The cross sections for producing final states consisting of a positively charged ionic core and two electrons just above the threshold for double ionization in ion-atom collisions have been measured. The cross sections for producing states with one electron moving with a kinetic energy less than 0.13 eV in the projectile frame and the other moving with somewhat higher kinetic energy are presented

  3. Experimental cross sections for two-electron capture into nitrogen autoionising states in Nsup(q+) (q=6,7) on He and H/sub 2/ collisions at 10. 5q keV

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.; Dousson, S.; Hitz, D.

    1985-07-01

    Singly differential cross sections for two-electron capture into autoionising states (nl,n'l') with n=2,3,4 and n'>=n in Nsup(q+) (q=6,7) on He and H/sub 2/ collisions have been measured at 10,5q ke V collision energy and an observation angle thetasub(lab)=11.6/sup 0/. Total cross sections are estimated assuming isotropic angular distributions. (orig.).

  4. Experimental cross sections for two-electron capture into nitrogen autoionising states in Nsup(q+) (q=6,7) on He and H2 collisions at 10.5q keV

    International Nuclear Information System (INIS)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.

    1985-01-01

    Singly differential cross sections for two-electron capture into autoionising states (nl,n'l') with n=2,3,4 and n'>=n in Nsup(q+) (q=6,7) on He and H 2 collisions have been measured at 10,5q ke V collision energy and an observation angle thetasub(lab)=11.6 0 . Total cross sections are estimated assuming isotropic angular distributions. (orig.)

  5. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  6. Reduction - competitive tomorrow

    International Nuclear Information System (INIS)

    Worley, L.; Bargerstock, S.

    1995-01-01

    Inventory reduction is one of the few initiatives that represent significant cost-reduction potential that does not result in personnel reduction. Centerior Energy's Perry nuclear power plant has embarked on an aggressive program to reduce inventory while maintaining plant material availability. Material availability to the plant was above 98%, but at an unacceptable 1994 inventory book value of $47 million with inventory carrying costs calculated at 30% annually

  7. Process energy reduction

    International Nuclear Information System (INIS)

    Lowthian, W.E.

    1993-01-01

    Process Energy Reduction (PER) is a demand-side energy reduction approach which complements and often supplants other traditional energy reduction methods such as conservation and heat recovery. Because the application of PER is less obvious than the traditional methods, it takes some time to learn the steps as well as practice to become proficient in its use. However, the benefit is significant, often far outweighing the traditional energy reduction approaches. Furthermore, the method usually results in a better process having less waste and pollution along with improved yields, increased capacity, and lower operating costs

  8. Finding optimal exact reducts

    KAUST Repository

    AbouEisha, Hassan M.

    2014-01-01

    The problem of attribute reduction is an important problem related to feature selection and knowledge discovery. The problem of finding reducts with minimum cardinality is NP-hard. This paper suggests a new algorithm for finding exact reducts with minimum cardinality. This algorithm transforms the initial table to a decision table of a special kind, apply a set of simplification steps to this table, and use a dynamic programming algorithm to finish the construction of an optimal reduct. I present results of computer experiments for a collection of decision tables from UCIML Repository. For many of the experimented tables, the simplification steps solved the problem.

  9. Metallothermic reduction of molybdate

    International Nuclear Information System (INIS)

    Mukherjee, T.K.; Bose, D.K.

    1987-01-01

    This paper gives a brief account of the investigations conducted so far on metallothermic reduction of high grade molybdenite with particular emphasis on the work carried out in Bhabha Atomic Research Centre. Based on thermochemical considerations, the paper first introduces a number of metallic reductants suitable for use in metallothermic reduction of molybdenite. Aluminium, sodium and tin are found to be suitable reducing agents and very rightly they have found most applications in the research and development efforts on metallothermic reduction of molybdenite. The reduction with tin was conducted on fairly large scale both in vacuum and hydrogen atmosphere. The reaction was reported to be invariant depending mainly on the reduction temperature and a temperature of the order of 1250deg to 1300degC was required for good metal recovery. In comparison to tin, aluminothermic reduction of molybdenite was studied more extensively and it was conducted in closed bomb, vacuum and also in open atmosphere. In aluminothermic reduction, the influence of amount of reducing agent, amount of heat booster, preheating temperature and charging procedure on these metal yield was studied in detail. The reduction generally yielded massive molybdenum metal contaminated with aluminium as the major impurity element. Efforts were made to purify the reduced metal by arc melting, electron beam melting and molten salt electrorefining. 9 refs. (author)

  10. Microbial reductive dehalogenation.

    Science.gov (United States)

    Mohn, W W; Tiedje, J M

    1992-01-01

    A wide variety of compounds can be biodegraded via reductive removal of halogen substituents. This process can degrade toxic pollutants, some of which are not known to be biodegraded by any other means. Reductive dehalogenation of aromatic compounds has been found primarily in undefined, syntrophic anaerobic communities. We discuss ecological and physiological principles which appear to be important in these communities and evaluate how widely applicable these principles are. Anaerobic communities that catalyze reductive dehalogenation appear to differ in many respects. A large number of pure cultures which catalyze reductive dehalogenation of aliphatic compounds are known, in contrast to only a few organisms which catalyze reductive dehalogenation of aromatic compounds. Desulfomonile tiedjei DCB-1 is an anaerobe which dehalogenates aromatic compounds and is physiologically and morphologically unusual in a number of respects, including the ability to exploit reductive dehalogenation for energy metabolism. When possible, we use D. tiedjei as a model to understand dehalogenating organisms in the above-mentioned undefined systems. Aerobes use reductive dehalogenation for substrates which are resistant to known mechanisms of oxidative attack. Reductive dehalogenation, especially of aliphatic compounds, has recently been found in cell-free systems. These systems give us an insight into how and why microorganisms catalyze this activity. In some cases transition metal complexes serve as catalysts, whereas in other cases, particularly with aromatic substrates, the catalysts appear to be enzymes. Images PMID:1406492

  11. Active3 noise reduction

    International Nuclear Information System (INIS)

    Holzfuss, J.

    1996-01-01

    Noise reduction is a problem being encountered in a variety of applications, such as environmental noise cancellation, signal recovery and separation. Passive noise reduction is done with the help of absorbers. Active noise reduction includes the transmission of phase inverted signals for the cancellation. This paper is about a threefold active approach to noise reduction. It includes the separation of a combined source, which consists of both a noise and a signal part. With the help of interaction with the source by scanning it and recording its response, modeling as a nonlinear dynamical system is achieved. The analysis includes phase space analysis and global radial basis functions as tools for the prediction used in a subsequent cancellation procedure. Examples are given which include noise reduction of speech. copyright 1996 American Institute of Physics

  12. Metal-free reduction of the greenhouse gas sulfur hexafluoride, formation of SF5 containing ion pairs and the application in fluorinations

    KAUST Repository

    Rueping, Magnus

    2017-05-04

    A protocol for the fast and selective two-electron reduction of the potent greenhouse gas sulfur hexafluoride (SF6) by organic electron donors at ambient temperature has been developed. The reaction yields solid ion pairs consisting of donor dications and SF5-anions which can be effectively used in fluorination reactions.

  13. Electrochemical reduction of imazamethabenz methyl on mercury and carbon electrodes

    International Nuclear Information System (INIS)

    Ruiz Montoya, Mercedes; Pintado, Sara; Rodriguez Mellado, Jose Miguel

    2010-01-01

    This paper presents polarographic and voltammetric studies of the reduction of the herbicide imazamethabenz methyl (2/3-methyl-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-p-toluate), on mercury and carbon electrodes. The electrochemical studies were performed in strongly acidic media (0.1-2.7 M H 2 SO 4 ) as well as in the pH range of 1-12. The overall reduction process involves the uptake of two electrons. The results obtained in polarography show that there is the reduction of two species, related via an acid-base equilibrium, and having very close reduction potentials. The voltammetric results obtained with a glassy carbon electrode were very similar to those observed on mercury electrodes. The reducible group in the molecule is the imidazolinone ring. In strongly acidic media (pH a ), the reaction mechanism proposed is the reduction of the protonated herbicide by an electrochemical-chemical-electrochemical (ECE) process, being the r.d.s. the second electron transfer. At pH > pK a the neutral form of the herbicide is reduced and the second electron transfer becomes reversible or quasi-reversible. In basic media, the species reduced is the deprotonated imazamethabenz methyl and the r.d.s. is the second electron transfer.

  14. Electrochemical reduction of imazamethabenz methyl on mercury and carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz Montoya, Mercedes, E-mail: mmontoya@uhu.e [Departamento de Ingenieria Quimica, Quimica Fisica y Quimica Organica, Universidad de Huelva, Campus El Carmen, Facultad de Ciencias Experimentales, E-21071 Huelva (Spain); Pintado, Sara; Rodriguez Mellado, Jose Miguel [Departamento de Quimica Fisica y Termodinamica Aplicada, Universidad de Cordoba, Campus Universitario de Rabanales, edificio ' Marie Curie' , E-14014 Cordoba (Spain)

    2010-03-30

    This paper presents polarographic and voltammetric studies of the reduction of the herbicide imazamethabenz methyl (2/3-methyl-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-p-toluate), on mercury and carbon electrodes. The electrochemical studies were performed in strongly acidic media (0.1-2.7 M H{sub 2}SO{sub 4}) as well as in the pH range of 1-12. The overall reduction process involves the uptake of two electrons. The results obtained in polarography show that there is the reduction of two species, related via an acid-base equilibrium, and having very close reduction potentials. The voltammetric results obtained with a glassy carbon electrode were very similar to those observed on mercury electrodes. The reducible group in the molecule is the imidazolinone ring. In strongly acidic media (pH < pK{sub a}), the reaction mechanism proposed is the reduction of the protonated herbicide by an electrochemical-chemical-electrochemical (ECE) process, being the r.d.s. the second electron transfer. At pH > pK{sub a} the neutral form of the herbicide is reduced and the second electron transfer becomes reversible or quasi-reversible. In basic media, the species reduced is the deprotonated imazamethabenz methyl and the r.d.s. is the second electron transfer.

  15. Potential for waste reduction

    International Nuclear Information System (INIS)

    Warren, J.L.

    1990-01-01

    The author focuses on wastes considered hazardous under the Resource Conservation and Recovery Act. This chapter discusses wastes that are of interest as well as the factors affecting the quantity of waste considered available for waste reduction. Estimates are provided of the quantities of wastes generated. Estimates of the potential for waste reduction are meaningful only to the extent that one can understand the amount of waste actually being generated. Estimates of waste reduction potential are summarized from a variety of government and nongovernment sources

  16. Breast reduction (mammoplasty) - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100189.htm Breast reduction (mammoplasty) - series—Indications To use the sharing features ... Lickstein, MD, FACS, specializing in cosmetic and reconstructive plastic surgery, Palm Beach Gardens, FL. Review provided by ...

  17. Medical Errors Reduction Initiative

    National Research Council Canada - National Science Library

    Mutter, Michael L

    2005-01-01

    The Valley Hospital of Ridgewood, New Jersey, is proposing to extend a limited but highly successful specimen management and medication administration medical errors reduction initiative on a hospital-wide basis...

  18. Microbial reductive dehalogenation.

    OpenAIRE

    Mohn, W W; Tiedje, J M

    1992-01-01

    A wide variety of compounds can be biodegraded via reductive removal of halogen substituents. This process can degrade toxic pollutants, some of which are not known to be biodegraded by any other means. Reductive dehalogenation of aromatic compounds has been found primarily in undefined, syntrophic anaerobic communities. We discuss ecological and physiological principles which appear to be important in these communities and evaluate how widely applicable these principles are. Anaerobic commun...

  19. Radiolytic and photochemical reduction of carbon dioxide in solution catalyzed by transition metal complexes with some selected macrocycles

    International Nuclear Information System (INIS)

    Grodkowski, J.

    2004-01-01

    The main goal of the work presented in this report is an explanation of the mechanism of carbon dioxide (CO 2 ) reduction catalyzed by transition metal complexes with some selected macrocycles. The catalytic function of two electron exchange centers in the reduction of CO 2 , an inner metal and a macrocycle ring, was defined. Catalytic effects of rhodium, iron and cobalt porphyrins, cobalt and iron phthalocyanines and corroles as well as cobalt corrins have been investigated. CO 2 reduction by iron ions without presence of macrocycles and also in presence of copper compounds in aqueous solutions have been studied as well

  20. Air Layer Drag Reduction

    Science.gov (United States)

    Ceccio, Steven; Elbing, Brian; Winkel, Eric; Dowling, David; Perlin, Marc

    2008-11-01

    A set of experiments have been conducted at the US Navy's Large Cavitation Channel to investigate skin-friction drag reduction with the injection of air into a high Reynolds number turbulent boundary layer. Testing was performed on a 12.9 m long flat-plate test model with the surface hydraulically smooth and fully rough at downstream-distance-based Reynolds numbers to 220 million and at speeds to 20 m/s. Local skin-friction, near-wall bulk void fraction, and near-wall bubble imaging were monitored along the length of the model. The instrument suite was used to access the requirements necessary to achieve air layer drag reduction (ALDR). Injection of air over a wide range of air fluxes showed that three drag reduction regimes exist when injecting air; (1) bubble drag reduction that has poor downstream persistence, (2) a transitional regime with a steep rise in drag reduction, and (3) ALDR regime where the drag reduction plateaus at 90% ± 10% over the entire model length with large void fractions in the near-wall region. These investigations revealed several requirements for ALDR including; sufficient volumetric air fluxes that increase approximately with the square of the free-stream speed, slightly higher air fluxes are needed when the surface tension is reduced, higher air fluxes are required for rough surfaces, and the formation of ALDR is sensitive to the inlet condition.

  1. Quantum theory without reduction

    International Nuclear Information System (INIS)

    Cini, Marcello; Levy-Leblond, J.-M.

    1990-01-01

    Quantum theory offers a strange, and perhaps unique, case in the history of science. Although research into its roots has provided important results in recent years, the debate goes on. Some theorists argue that quantum theory is weakened by the inclusion of the so called 'reduction of the state vector' in its foundations. Quantum Theory without Reduction presents arguments in favour of quantum theory as a consistent and complete theory without this reduction, and which is capable of explaining all known features of the measurement problem. This collection of invited contributions defines and explores different aspects of this issue, bringing an old debate into a new perspective, and leading to a more satisfying consensus about quantum theory. (author)

  2. Measuring mandibular ridge reduction

    International Nuclear Information System (INIS)

    Steen, W.H.A.

    1984-01-01

    This thesis investigates the mandibular reduction in height of complete denture wearers and overdenture wearers. To follow this reduction in the anterior region as well as in the lateral sections of the mandible, an accurate and reproducible measuring method is a prerequisite. A radiologic technique offers the best chance. A survey is given of the literature concerning the resorption process after the extraction of teeth. An oblique cephalometric radiographic technique is introduced as a promising method to measure mandibular ridge reduction. The reproducibility and the accuracy of the technique are determined. The reproducibility in the positioning of the mandible is improved by the introduction of a mandibular support which permits a precise repositioning of the edentulous jaw, even after long periods of investigation. (Auth.)

  3. REDUCTIONS WITHOUT REGRET: SUMMARY

    Energy Technology Data Exchange (ETDEWEB)

    Swegle, J.; Tincher, D.

    2013-09-16

    This paper briefly summarizes the series in which we consider the possibilities for losing, or compromising, key capabilities of the U.S. nuclear force in the face of modernization and reductions. The first of the three papers takes an historical perspective, considering capabilities that were eliminated in past force reductions. The second paper is our attempt to define the needed capabilities looking forward in the context of the current framework for force modernization and the current picture of the evolving challenges of deterrence and assurance. The third paper then provides an example for each of our undesirable outcomes: the creation of roach motels, box canyons, and wrong turns.

  4. Reduction of dinitrogen ligands

    International Nuclear Information System (INIS)

    Richards, R.L.

    1983-01-01

    Processes of dinitrogen ligand reduction in complexes of transition metals are considered. The basic character of the dinitrogen ligand is underlined. Data on X-ray photoelectronic spectroscopy and intensities of bands ν (N 2 ) in IR-spectra of nitrogen complexes are given. The mechanism of protonation of an edge dinitrogen ligand is discussed. Model systems and mechanism of nitrogenogenase are compared

  5. Infinitary Combinatory Reduction Systems

    DEFF Research Database (Denmark)

    Ketema, Jeroen; Simonsen, Jakob Grue

    2011-01-01

    We define infinitary Combinatory Reduction Systems (iCRSs), thus providing the first notion of infinitary higher-order rewriting. The systems defined are sufficiently general that ordinary infinitary term rewriting and infinitary ¿-calculus are special cases. Furthermore,we generalise a number...

  6. Galactorrhea after reduction mammaplasty

    NARCIS (Netherlands)

    Schuurman, A. H.; Assies, J.; van der Horst, C. M.; Bos, K. E.

    1993-01-01

    A case of extremely painful swelling of the breasts following a reduction mammaplasty is presented. There were no signs of an abscess or hematoma. A milky white fluid due to galactorrhea was evacuated at operation, and further galactorrhea was inhibited by medication. The pathogenesis of

  7. (MTT) dye reduction assay.

    African Journals Online (AJOL)

    to inhibit proliferation of HeLa cells was determined using the 3443- dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) dye reduction assay. Extracts from roots of Agathisanthemum bojeri, Synaptolepis kirkii and Zanha africana and the leaf extract of Physalis peruviana at a concentration of 10 pg/ml inhibited cell ...

  8. Streaming Reduction Circuit

    NARCIS (Netherlands)

    Gerards, Marco Egbertus Theodorus; Kuper, Jan; Kokkeler, Andre B.J.; Molenkamp, Egbert

    2009-01-01

    Reduction circuits are used to reduce rows of floating point values to single values. Binary floating point operators often have deep pipelines, which may cause hazards when many consecutive rows have to be reduced. We present an algorithm by which any number of consecutive rows of arbitrary lengths

  9. Reduction of nitrobenzene with alkaline ascorbic acid: Kinetics and pathways

    International Nuclear Information System (INIS)

    Liang, Chenju; Lin, Ya-Ting; Shiu, Jia-Wei

    2016-01-01

    Highlights: • Alkaline ascorbic acid (a.k.a. vitamin C) is capable of reductively degrading NB. • The pH above the pK_a_2 of ascorbic acid increases reductive electron transfer to NB. • The rate equation for the reactions between NB and AA is determined. • NSB, AZOXY, and AZO are identified as intermediates and aniline as a final product. • Alkaline pH is essential for AA remediation of NB contaminated soils. - Abstract: Alkaline ascorbic acid (AA) exhibits the potential to reductively degrade nitrobenzene (NB), which is the simplest of the nitroaromatic compounds. The nitro group (NO_2"−) of NB has a +III oxidation state of the N atom and tends to gain electrons. The effect of alkaline pH ranging from 9 to 13 was initially assessed and the results demonstrated that the solution pH, when approaching or above the pK_a_2 of AA (11.79), would increase reductive electron transfer to NB. The rate equation for the reactions between NB and AA at pH 12 can be described as r = ((0.89 ± 0.11) × 10"−"4 mM"1"−"("a "+ "b") h"−"1) × [NB]"a "= "1"."3"5 "± "0"."1"0[AA]"b "= "0"."8"9 "± "0"."0"1. The GC/MS analytical method identified nitrosobenzene, azoxybenzene, and azobenzene as NB reduction intermediates, and aniline (AN) as a final product. These experimental results indicate that the alkaline AA reduction of NB to AN mainly proceeds via the direct route, consisting of a series of two-electron or four-electron transfers, and the condensation reaction plays a minor route. Preliminary evaluation of the remediation of spiked NB contaminated soils revealed that maintenance of alkaline pH and a higher water to soil ratio are essential for a successful alkaline AA application.

  10. Spontaneous wave packet reduction

    International Nuclear Information System (INIS)

    Ghirardi, G.C.

    1994-06-01

    There are taken into account the main conceptual difficulties met by standard quantum mechanics in dealing with physical processes involving macroscopic system. It is stressed how J.A.Wheeler's remarks and lucid analysis have been relevant to pinpoint and to bring to its extreme consequences the puzzling aspects of quantum phenomena. It is shown how the recently proposed models of spontaneous dynamical reduction represent a consistent way to overcome the conceptual difficulties of the standard theory. Obviously, many nontrivial problems remain open, the first and more relevant one being that of generalizing the model theories considered to the relativistic case. This is the challenge of the dynamical reduction program. 43 refs, 2 figs

  11. BP volume reduction equipment

    International Nuclear Information System (INIS)

    Kitamura, Yoshinori; Muroo, Yoji; Hamanaka, Isao

    2003-01-01

    A new type of burnable poison (BP) volume reduction system is currently being developed. Many BP rods, a subcomponent of spent fuel assemblies are discharged from nuclear power reactors. This new system reduces the overall volume of BP rods. The main system consists of BP rod cutting equipment, equipment for the recovery of BP cut pieces, and special transport equipment for the cut rods. The equipment is all operated by hydraulic press cylinders in water to reduce operator exposure to radioactivity. (author)

  12. Anaerobic azo dye reduction

    OpenAIRE

    Zee, van der, F.P.

    2002-01-01

    Azo dyes, aromatic moieties linked together by azo (-N=N-) chromophores, represent the largest class of dyes used in textile-processing and other industries. The release of these compounds into the environment is undesirable, not only because of their colour, but also because many azo dyes and their breakdown products are toxic and/or mutagenic to life. To remove azo dyes from wastewater, a biological treatment strategy based on anaerobic reduction of the azo dye...

  13. Thermochemical nitrate reduction

    International Nuclear Information System (INIS)

    Cox, J.L.; Lilga, M.A.; Hallen, R.T.

    1992-09-01

    A series of preliminary experiments was conducted directed at thermochemically converting nitrate to nitrogen and water. Nitrates are a major constituent of the waste stored in the underground tanks on the Hanford Site, and the characteristics and effects of nitrate compounds on stabilization techniques must be considered before permanent disposal operations begin. For the thermochemical reduction experiments, six reducing agents (ammonia, formate, urea, glucose, methane, and hydrogen) were mixed separately with ∼3 wt% NO 3 - solutions in a buffered aqueous solution at high pH (13); ammonia and formate were also mixed at low pH (4). Reactions were conducted in an aqueous solution in a batch reactor at temperatures of 200 degrees C to 350 degrees C and pressures of 600 to 2800 psig. Both gas and liquid samples were analyzed. The specific components analyzed were nitrate, nitrite, nitrous oxide, nitrogen, and ammonia. Results of experimental runs showed the following order of nitrate reduction of the six reducing agents in basic solution: formate > glucose > urea > hydrogen > ammonia ∼ methane. Airnmonia was more effective under acidic conditions than basic conditions. Formate was also effective under acidic conditions. A more thorough, fundamental study appears warranted to provide additional data on the mechanism of nitrate reduction. Furthermore, an expanded data base and engineering feasibility study could be used to evaluate conversion conditions for promising reducing agents in more detail and identify new reducing agents with improved performance characteristics

  14. Electrocatalytic Reduction-oxidation of Chlorinated Phenols using a Nanostructured Pd-Fe Modified Graphene Catalyst

    International Nuclear Information System (INIS)

    Shi, Qin; Wang, Hui; Liu, Shaolei; Pang, Lei; Bian, Zhaoyong

    2015-01-01

    A Pd-Fe modified graphene (Pd-Fe/G) catalyst was prepared by the Hummers oxidation method and bimetallic co-deposition method. The catalyst was then characterized by various characterization techniques and its electrochemical property toward the electrocatalytic reduction-oxidation of chlorinated phenols was investigated by using cyclic voltammetry and differential pulse voltammetry. The results of the characterization show that the Pd-Fe/G catalyst in which the weight proportion of Pd and Fe is 1:1 has an optimal surface performance. The diameter of the Pd-Fe particles is approximately 5.2 ± 0.3 nm, with a uniform distribution on the supporting graphene. This is smaller than the Pd particles of a Pd-modified graphene (Pd/G) catalyst. The Pd-Fe/G catalyst shows a higher electrocatalytic activity than the Pd/G catalyst for reductive dechlorination when feeding with hydrogen gas. The reductive peak potentials of −0.188 V, −0.836 V and −0.956 V in the DPV curves are attributed to the dechlorination of ortho-Cl, meta-Cl, and para-Cl in 2-chlorophenol, 3-chlorophenol and 4-chlorophenol, respectively. In accordance with an analysis of the frontier orbital theory, the order of ease of dechlorination with Pd-Fe/G catalyst is 2-chlorophenol > 3-chlorophenol > 4-chlorophenol. The Pd-Fe/G catalyst has a greater activity than the Pd/G catalyst in accelerating the two-electron reduction of O_2 to H_2O_2, which is attributed to the higher current of the reduction peak at approximately −0.40 V when feeding with oxygen gas. Therefore, the Pd-Fe/G catalyst exhibits a higher electrocatalytic activity than the Pd/G catalyst for the reductive dechlorination and acceleration of the two-electron reduction of O_2 to H_2O_2.

  15. Vietnam; Poverty Reduction Strategy Paper

    OpenAIRE

    International Monetary Fund

    2004-01-01

    This paper assesses the Poverty Reduction Strategy Paper of Vietnam, known as the Comprehensive Poverty Reduction and Growth Strategy (CPRGS). It is an action program to achieve economic growth and poverty reduction objectives. This paper reviews the objectives and tasks of socio-economic development and poverty reduction. The government of Vietnam takes poverty reduction as a cutting-through objective in the process of country socio-economic development and declares its commitment to impleme...

  16. Discrete Routh reduction

    International Nuclear Information System (INIS)

    Jalnapurkar, Sameer M; Leok, Melvin; Marsden, Jerrold E; West, Matthew

    2006-01-01

    This paper develops the theory of Abelian Routh reduction for discrete mechanical systems and applies it to the variational integration of mechanical systems with Abelian symmetry. The reduction of variational Runge-Kutta discretizations is considered, as well as the extent to which symmetry reduction and discretization commute. These reduced methods allow the direct simulation of dynamical features such as relative equilibria and relative periodic orbits that can be obscured or difficult to identify in the unreduced dynamics. The methods are demonstrated for the dynamics of an Earth orbiting satellite with a non-spherical J 2 correction, as well as the double spherical pendulum. The J 2 problem is interesting because in the unreduced picture, geometric phases inherent in the model and those due to numerical discretization can be hard to distinguish, but this issue does not appear in the reduced algorithm, where one can directly observe interesting dynamical structures in the reduced phase space (the cotangent bundle of shape space), in which the geometric phases have been removed. The main feature of the double spherical pendulum example is that it has a non-trivial magnetic term in its reduced symplectic form. Our method is still efficient as it can directly handle the essential non-canonical nature of the symplectic structure. In contrast, a traditional symplectic method for canonical systems could require repeated coordinate changes if one is evoking Darboux' theorem to transform the symplectic structure into canonical form, thereby incurring additional computational cost. Our method allows one to design reduced symplectic integrators in a natural way, despite the non-canonical nature of the symplectic structure

  17. One-electron reduction of 2- and 6-methyl-1,4-naphthoquinone bioreductive alkylating agents

    International Nuclear Information System (INIS)

    Wilson, I.; Wardman, P.; Lin, T.S.; Sartorelli, A.C.

    1986-01-01

    The semiquinones, Q.-, of derivatives of 2- and 6-methyl-1,4-naphthoquinones, some incorporating leaving groups with substituents such as CH 2 Br or CH 2 OCONHCH 3 , have been produced by radiolytic reduction of Q by (CH 3 )2COH radicals. The absorption spectra and decay kinetics of Q.- were all closely similar to that produced from 2-methyl-1,4-naphthoquinone, with no evidence for unimolecular elimination of a leaving group in the semiquinone form, but immediate loss of leaving group upon two-electron reduction of Q to the hydroquinone. The redox equilibria between Q/Q.- and O2/O2.- were characterized, and reduction potentials of the couples Q/Q.- in water at pH 7.6 were calculated. The implications of these observations for the use of these compounds as bioreductive alkylating agents or as radiosensitizers with potential selective activity toward hypoxic cells are discussed

  18. Absolute total and one- and two-electron transfer cross sections for Arq+ (8≤q≤16) on He and H2 at 2.3q keV

    International Nuclear Information System (INIS)

    Vancura, J.; Marchetti, V.J.; Perotti, J.J.; Kostroun, V.O.

    1993-01-01

    Absolute values for the total and one- and two-electron transfer cross sections for Ar q+ ions (8≤q≤16) colliding with helium and molecular hydrogen at 2.3q keV laboratory energy were measured by the growth-rate method. The He and H 2 total cross sections as a function of Ar-projectile L-shell occupation number increase monotonically from Ar 8+ , 2p shell full, to Ar 16+ , 2s shell empty. The H 2 one-electron capture cross section scales approximately as [E IP (He)/E IP (H 2 )] 2 times the corresponding He cross section, but the shapes of the two cross sections differ in detail. The Ar q+ ions were produced by the Cornell superconducting-solenoid, cryogenic electron-beam ion source (CEBIS) and extracted at 2.3 kV. Selected charge states traversed a gas cell, after which they were detected and charge-state analyzed by the energy-retardation method and by a π/ √2 cylindrical electrostatic analyzer. The target-gas pressure in the cell was measured directly by the orifice-flow method used for absolute-pressure gauge calibration. The overall error in the Ar q+ on H 2 cross-section measurements is ±10%, and ±15% in the He measurements

  19. Economical benzene emission reduction

    International Nuclear Information System (INIS)

    Schuetz, R.

    1999-01-01

    Benzene has been classified as a toxic compound under the Canadian Environmental Protection Act. This has prompted the Alberta Energy and Utilities Board (AEUB) to introduce specific reporting and monitoring guidelines for the oil and gas industry regarding excessive benzene emissions. Glycol dehydration units have been determined to be the major single source of benzene emissions causing air and soil pollution. DualTank Corp. has designed a condensation and storage tank unit to enhance emission reduction, odour elimination and liquid recovery from dehydration units. Their newly designed combined tank unit consists of a large, uninsulated surface area for cooling, and an excessive internal volume for increased retention time. The first prototype was installed in December 1998 at an Enerplus Resources Site. The system provides excellent benzene emission reduction and the elimination of odours and visual plumes. Effective January 1, 1999, the petroleum and natural gas industry must either clean up excessive emissions voluntarily or face government imposed regulations, facility shutdowns and/or fines. 1 fig

  20. LOFT data reduction

    International Nuclear Information System (INIS)

    Norman, N.L.

    1975-08-01

    The Loss-of-Fluid Test (LOFT) Facility is an experimental facility built around a ''scaled'' version of a large pressurized water reactor (LPWR). LOFT will be used to run loss-of-coolant experiments (LOCEs) and to acquire the necessary data required ''to evaluate the adequacy and improve the analytical methods currently used to predict the loss-of-coolant accident (LOCA) response of LPWRs'' and ''to identify and investigate any unexpected event(s) or threshold(s) in the response of either the plant or the engineered safety features and develop analytical techniques that adequately describe and account for the unexpected behavior(s)''. During the LOCE this required data will be acquired and recorded in both analog and digital modes. Subsequent to the test the analog data will also be converted to the raw digital mode. This raw digital data will be converted to the desired engineering units using the LOFT Data Reduction System. This system is implemented on the IBM 360/75 and is a part of a commercially available data processing program called MAC/RAN III. The theory of reducing LOFT data to engineering units and the application of the MAC/ RAN III system to accomplish this reduction is given. (auth)

  1. Islam and harm reduction.

    Science.gov (United States)

    Kamarulzaman, A; Saifuddeen, S M

    2010-03-01

    Although drugs are haram and therefore prohibited in Islam, illicit drug use is widespread in many Islamic countries throughout the world. In the last several years increased prevalence of this problem has been observed in many of these countries which has in turn led to increasing injecting drug use driven HIV/AIDS epidemic across the Islamic world. Whilst some countries have recently responded to the threat through the implementation of harm reduction programmes, many others have been slow to respond. In Islam, The Quran and the Prophetic traditions or the Sunnah are the central sources of references for the laws and principles that guide the Muslims' way of life and by which policies and guidelines for responses including that of contemporary social and health problems can be derived. The preservation and protection of the dignity of man, and steering mankind away from harm and destruction are central to the teachings of Islam. When viewed through the Islamic principles of the preservation and protection of the faith, life, intellect, progeny and wealth, harm reduction programmes are permissible and in fact provide a practical solution to a problem that could result in far greater damage to the society at large if left unaddressed. Copyright (c) 2009. Published by Elsevier B.V.

  2. Emergency planning zone reduction

    International Nuclear Information System (INIS)

    Edwards, C.

    2002-01-01

    This paper describes the process used by a large industrial Department of Energy (DOE) site to communicate changing hazards to its stakeholders and install the confidence necessary to implement the resulting emergency planning changes. Over the last decade as the sites missions have shifted from full-scale production to a greater emphasis on environmental restoration and waste management, the off-site threat from its operations has substantially decreased. The challenge was to clearly communicate the reduced hazards, install confidence in the technical analysis that documented the hazard reduction, and obtain stakeholder buy-in on the path forward to change the emergency management program. The most significant change to the emergency management program was the proposed reduction of the sites Emergency Planning Zone (EPZ). As the EPZ is defined as an area for which planning is needed to protect the public in the event of an accident, the process became politically challenging. An overview of how the site initially approached this problem and then learned to more substantially involve the state and local emergency preparedness agencies and the local Citizens Advisory Board will be presented. (author)

  3. Reduction operators of Burgers equation.

    Science.gov (United States)

    Pocheketa, Oleksandr A; Popovych, Roman O

    2013-02-01

    The solution of the problem on reduction operators and nonclassical reductions of the Burgers equation is systematically treated and completed. A new proof of the theorem on the special "no-go" case of regular reduction operators is presented, and the representation of the coefficients of operators in terms of solutions of the initial equation is constructed for this case. All possible nonclassical reductions of the Burgers equation to single ordinary differential equations are exhaustively described. Any Lie reduction of the Burgers equation proves to be equivalent via the Hopf-Cole transformation to a parameterized family of Lie reductions of the linear heat equation.

  4. Oxygen Reduction on Platinum

    DEFF Research Database (Denmark)

    Nesselberger, Markus

    . The influence of the ion adsorption strength, which is observed in the “particle size studies” on the oxygen reduction rate on Pt/C catalysts, is further investigated under similar reaction conditions by infrared spectroscopy. The designed in situ electrochemical ATR-FTIR setup features a high level...... of instrument automation and online data treatment, and provides welldefined mass transport conditions enabling kinetic measurements. A modified electrochemical / spectroscopic interface is presented allowing the exclusive investigation of the Pt/C catalyst layer. Three types of potential dependent adsorption...... adsorption on Pt does not block the ORR directly. Instead, the onset of oxide formation with the concomitant conversion of the anion adsorbate layer is the decisive blocking mechanism....

  5. Multiple gas reduction strategy

    Energy Technology Data Exchange (ETDEWEB)

    A. Kurosawa [Institute of Applied Energy, Tokyo (Japan)

    2003-07-01

    Future global warming has a close relationship with the abatement potential of six greenhouse gases (GHGs), including carbon dioxide (CO{sub 2}), methane (CH{sub 4}), nitrous oxide (N{sub 2}O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). Therefore, multiple gas reduction flexibility should be assessed. The emission of each non-CO{sub 2} GHG is calculated endogenously by the sum of the product of the emission factor and the endogenous activity index using an integrated assessment model, GRAPE (Global Relationship Assessment to Protect the Environment). The model consists of five modules dealing with issues on energy, climate, land use, macroeconomics and environmental impacts. The uncertainty in the non-CO{sub 2} GHG emission inventory and emission factors is discussed. 5 refs., 3 figs., 1 tab.

  6. Minimal Reducts with Grasp

    Directory of Open Access Journals (Sweden)

    Iris Iddaly Mendez Gurrola

    2011-03-01

    Full Text Available The proper detection of patient level of dementia is important to offer the suitable treatment. The diagnosis is based on certain criteria, reflected in the clinical examinations. From these examinations emerge the limitations and the degree in which each patient is in. In order to reduce the total of limitations to be evaluated, we used the rough set theory, this theory has been applied in areas of the artificial intelligence such as decision analysis, expert systems, knowledge discovery, classification with multiple attributes. In our case this theory is applied to find the minimal limitations set or reduct that generate the same classification that considering all the limitations, to fulfill this purpose we development an algorithm GRASP (Greedy Randomized Adaptive Search Procedure.

  7. Aircraft engine pollution reduction.

    Science.gov (United States)

    Rudey, R. A.

    1972-01-01

    The effect of engine operation on the types and levels of the major aircraft engine pollutants is described and the major factors governing the formation of these pollutants during the burning of hydrocarbon fuel are discussed. Methods which are being explored to reduce these pollutants are discussed and their application to several experimental research programs are pointed out. Results showing significant reductions in the levels of carbon monoxide, unburned hydrocarbons, and oxides of nitrogen obtained from experimental combustion research programs are presented and discussed to point out potential application to aircraft engines. An experimental program designed to develop and demonstrate these and other advanced, low pollution combustor design methods is described. Results that have been obtained to date indicate considerable promise for reducing advanced engine exhaust pollutants to levels significantly below current engines.

  8. Inner-sphere and outer-sphere complexes of yttrium(III), lanthanum (III), neodymium(III), terbium(III) and thulium(III) with halide ions in N,N-dimethylformamide

    International Nuclear Information System (INIS)

    Takahashi, Ryouta; Ishiguro, Shin-ichi

    1991-01-01

    The formation of chloro, bromo and iodo complexes of yttrium(III), and bromo and iodo complexes of lanthanum(III), neodymium(III), terbium(III) and thulium(III) has been studied by precise titration calorimetry in N,N-dimethylformamide (DMF) at 25 o C. The formation of [YCl] 2+ , [YCl 2 ] + , [YCl 3 ] and [YCl 4 ] - , and [MBr] 2+ and [MBr 2 ] + (M = Y, La, Nd, Tb, Tm) was revealed, and their formation constants, enthalpies and entropies were determined. It is found that the formation enthalpies change in the sequence ΔH o (Cl) > ΔH o (l), which is unusual for hard metal (III) ions. This implies that, unlike the chloride ion, the bromide ion forms outer-sphere complexes with the lanthanide(III) and yttrium(III) ions in DMF. Evidence for either an inner- or outer-sphere complex was obtained from 89 Y NMR spectra for Y(ClO 4 ) 3 , YCl 3 and YBr 3 DMF solutions at room temperature. (author)

  9. Mindfulness-Based Stress Reduction

    Science.gov (United States)

    ... R S T U V W X Y Z Mindfulness-Based Stress Reduction (MBSR) Information 6 Things You ... Disease and Dementia (12/20/13) Research Spotlights Mindfulness-Based Stress Reduction, Cognitive-Behavioral Therapy Shown To ...

  10. Consumer's Guide to Radon Reduction

    Science.gov (United States)

    ... Labs and Research Centers Radon Contact Us Share Consumer's Guide to Radon Reduction: How to Fix Your ... See EPA’s About PDF page to learn more. Consumer's Guide to Radon Reduction: How to Fix Your ...

  11. Confluence reduction for Markov automata

    NARCIS (Netherlands)

    Timmer, Mark; Katoen, Joost P.; van de Pol, Jaco; Stoelinga, Mariëlle Ida Antoinette

    2016-01-01

    Markov automata are a novel formalism for specifying systems exhibiting nondeterminism, probabilistic choices and Markovian rates. As expected, the state space explosion threatens the analysability of these models. We therefore introduce confluence reduction for Markov automata, a powerful reduction

  12. Hazardous material reduction initiative

    International Nuclear Information System (INIS)

    Nichols, D.H.

    1995-02-01

    The Hazardous Material Reduction Initiative (HMRI) explores using the review of purchase requisitions to reduce both the use of hazardous materials and the generation of regulated and nonregulated wastes. Based on an 11-month program implemented at the Hanford Site, hazardous material use and waste generation was effectively reduced by using a centralized procurement control program known as HMRI. As expected, several changes to the original proposal were needed during the development/testing phase of the program to accommodate changing and actual conditions found at the Hanford Site. The current method requires a central receiving point within the Procurement Organization to review all purchase requisitions for potentially Occupational Safety and Health Administration (OSHA) hazardous products. Those requisitions (approximately 4% to 6% of the total) are then forwarded to Pollution Prevention personnel for evaluation under HMRI. The first step is to determine if the requested item can be filled by existing or surplus material. The requisitions that cannot filled by existing or surplus material are then sorted into two groups based on applicability to the HMRI project. For example, laboratory requests for analytical reagents or standards are excluded and the purchase requisitions are returned to Procurement for normal processing because, although regulated, there is little opportunity for source reduction due to the strict protocols followed. Each item is then checked to determine if it is regulated or not. Regulated items are prioritized based on hazardous contents, quantity requested, and end use. Copies of these requisitions are made and the originals are returned to Procurement within 1-hr. Since changes to the requisition can be made at later stages during procurement, the HMRI fulfills one of its original premises in that it does not slow the procurement process

  13. Dose Reduction Techniques

    International Nuclear Information System (INIS)

    WAGGONER, L.O.

    2000-01-01

    As radiation safety specialists, one of the things we are required to do is evaluate tools, equipment, materials and work practices and decide whether the use of these products or work practices will reduce radiation dose or risk to the environment. There is a tendency for many workers that work with radioactive material to accomplish radiological work the same way they have always done it rather than look for new technology or change their work practices. New technology is being developed all the time that can make radiological work easier and result in less radiation dose to the worker or reduce the possibility that contamination will be spread to the environment. As we discuss the various tools and techniques that reduce radiation dose, keep in mind that the radiological controls should be reasonable. We can not always get the dose to zero, so we must try to accomplish the work efficiently and cost-effectively. There are times we may have to accept there is only so much you can do. The goal is to do the smart things that protect the worker but do not hinder him while the task is being accomplished. In addition, we should not demand that large amounts of money be spent for equipment that has marginal value in order to save a few millirem. We have broken the handout into sections that should simplify the presentation. Time, distance, shielding, and source reduction are methods used to reduce dose and are covered in Part I on work execution. We then look at operational considerations, radiological design parameters, and discuss the characteristics of personnel who deal with ALARA. This handout should give you an overview of what it takes to have an effective dose reduction program

  14. Dose Reduction Techniques

    Energy Technology Data Exchange (ETDEWEB)

    WAGGONER, L.O.

    2000-05-16

    As radiation safety specialists, one of the things we are required to do is evaluate tools, equipment, materials and work practices and decide whether the use of these products or work practices will reduce radiation dose or risk to the environment. There is a tendency for many workers that work with radioactive material to accomplish radiological work the same way they have always done it rather than look for new technology or change their work practices. New technology is being developed all the time that can make radiological work easier and result in less radiation dose to the worker or reduce the possibility that contamination will be spread to the environment. As we discuss the various tools and techniques that reduce radiation dose, keep in mind that the radiological controls should be reasonable. We can not always get the dose to zero, so we must try to accomplish the work efficiently and cost-effectively. There are times we may have to accept there is only so much you can do. The goal is to do the smart things that protect the worker but do not hinder him while the task is being accomplished. In addition, we should not demand that large amounts of money be spent for equipment that has marginal value in order to save a few millirem. We have broken the handout into sections that should simplify the presentation. Time, distance, shielding, and source reduction are methods used to reduce dose and are covered in Part I on work execution. We then look at operational considerations, radiological design parameters, and discuss the characteristics of personnel who deal with ALARA. This handout should give you an overview of what it takes to have an effective dose reduction program.

  15. Alcohol harm reduction in Europe

    DEFF Research Database (Denmark)

    Herring, Rachel; Betsy, Thom; Beccaria, Franca

    2010-01-01

    The EMCDDA’s 10th scientific monograph, entitled Harm reduction: evidence, impacts and challenges provides a comprehensive overview of the harm reduction field. Part I of the monograph looks back at the emergence of harm reduction approaches and their diffusion, and explores the concept from diff...

  16. Model Reduction in Biomechanics

    Science.gov (United States)

    Feng, Yan

    mechanical parameters from experimental results. However, in real biological world, these homogeneous and isotropic assumptions are usually invalidate. Thus, instead of using hypothesized model, a specific continuum model at mesoscopic scale can be introduced based upon data reduction of the results from molecular simulations at atomistic level. Once a continuum model is established, it can provide details on the distribution of stresses and strains induced within the biomolecular system which is useful in determining the distribution and transmission of these forces to the cytoskeletal and sub-cellular components, and help us gain a better understanding in cell mechanics. A data-driven model reduction approach to the problem of microtubule mechanics as an application is present, a beam element is constructed for microtubules based upon data reduction of the results from molecular simulation of the carbon backbone chain of alphabeta-tubulin dimers. The data base of mechanical responses to various types of loads from molecular simulation is reduced to dominant modes. The dominant modes are subsequently used to construct the stiffness matrix of a beam element that captures the anisotropic behavior and deformation mode coupling that arises from a microtubule's spiral structure. In contrast to standard Euler-Bernoulli or Timoshenko beam elements, the link between forces and node displacements results not from hypothesized deformation behavior, but directly from the data obtained by molecular scale simulation. Differences between the resulting microtubule data-driven beam model (MTDDBM) and standard beam elements are presented, with a focus on coupling of bending, stretch, shear deformations. The MTDDBM is just as economical to use as a standard beam element, and allows accurate reconstruction of the mechanical behavior of structures within a cell as exemplified in a simple model of a component element of the mitotic spindle.

  17. Cholesterol Hydroperoxide Generation, Translocation, and Reductive Turnover in Biological Systems.

    Science.gov (United States)

    Girotti, Albert W; Korytowski, Witold

    2017-12-01

    Cholesterol is like other unsaturated lipids in being susceptible to peroxidative degradation upon exposure to strong oxidants like hydroxyl radical or peroxynitrite generated under conditions of oxidative stress. In the eukaryotic cell plasma membrane, where most of the cellular cholesterol resides, peroxidation leads to membrane structural and functional damage from which pathological states may arise. In low density lipoprotein, cholesterol and phospholipid peroxidation have long been associated with atherogenesis. Among the many intermediates/products of cholesterol oxidation, hydroperoxide species (ChOOHs) have a number of different fates and deserve special attention. These fates include (a) damage-enhancement via iron-catalyzed one-electron reduction, (b) damage containment via two-electron reduction, and (c) inter-membrane, inter-lipoprotein, and membrane-lipoprotein translocation, which allows dissemination of one-electron damage or off-site suppression thereof depending on antioxidant location and capacity. In addition, ChOOHs can serve as reliable and conveniently detected mechanistic reporters of free radical-mediated reactions vs. non-radical (e.g., singlet oxygen)-mediated reactions. Iron-stimulated peroxidation of cholesterol and other lipids underlies a newly discovered form of regulated cell death called ferroptosis. These and other deleterious consequences of radical-mediated lipid peroxidation will be discussed in this review.

  18. Reduction of blue tungsten oxide

    International Nuclear Information System (INIS)

    Wilken, T.; Wert, C.; Woodhouse, J.; Morcom, W.

    1975-01-01

    A significant portion of commercial tungsten is produced by hydrogen reduction of oxides. Although several modes of reduction are possible, hydrogen reduction is used where high purity tungsten is required and where the addition of other elements or compounds is desired for modification of the metal, as is done for filaments in the lamp industry. Although several investigations of the reduction of oxides have been reported (1 to 5), few principles have been developed which can aid in assessment of current commercial practice. The reduction process was examined under conditions approximating commercial practice. The specific objectives were to determine the effects of dopants, of water vapor in the reducing atmosphere, and of reduction temperature upon: (1) the rate of the reaction by which blue tungsten oxide is reduced to tungsten metal, (2) the intermediate oxides associated with reduction, and (3) the morphology of the resulting tungsten powder

  19. Size reduction machine

    International Nuclear Information System (INIS)

    Fricke, V.

    1999-01-01

    The Size Reduction Machine (SRM) is a mobile platform capable of shearing various shapes and types of metal components at a variety of elevations. This shearing activity can be performed without direct physical movement and placement of the shear head by the operator. The base unit is manually moved and roughly aligned to each cut location. The base contains the electronics: hydraulic pumps, servos, and actuators needed to move the shear-positioning arm. The movable arm allows the shear head to have six axes of movement and to cut to within 4 inches of a wall surface. The unit has a slick electrostatic capture coating to assist in external decontamination. Internal contamination of the unit is controlled by a high-efficiency particulate air (HEPA) filter on the cooling inlet fan. The unit is compact enough to access areas through a 36-inch standard door opening. This paper is an Innovative Technology Summary Report designed to provide potential users with the information they need to quickly determine if a technology would apply to a particular environmental management problem. They also are designed for readers who may recommend that a technology be considered by prospective users

  20. Electrochemical reduction of NOx

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund

    NO and NO2 (collectively referred to as NOx) are air pollutants, and the largest single contributor to NOx pollution is automotive exhaust. This study investigates electrochemical deNOx, a technology which aims to remove NOx from automotive diesel exhaust by electrochemical reduction of NOx to N2...... and O2. The focus in this study is on improving the activity and selectivity of solid oxide electrodes for electrochemical deNOx by addition of NOx storage compounds to the electrodes. Two different composite electrodes, La0.85Sr0.15MnO3-δ-Ce0.9Gd0.1O1.95 (LSM15-CGO10) and La0.85Sr0.15FeO3-δ-Ce0.9Gd0.1O......1.95 (LSF15-CGO10), have been investigated in combination with three different NOx storage compounds: BaO, K2O and MnOx. The main focus in the investigation has been on conversion measurements and electrochemical characterization, the latter by means of electrochemical impedance spectroscopy...

  1. Syncrude emissions reduction project

    Energy Technology Data Exchange (ETDEWEB)

    Fiedler, M.A. [Alstom Power Inc., Knoxville, TN (United States); Ibbotson, P. [Syncrude Canada Ltd., Calgary, AB (Canada)

    2008-07-01

    This paper described an emissions reduction project conducted by Syncrude Canada and various other companies currently developing and processing oil sands in Alberta. Syncrude's upgrader expansion program included the installation of an ammonia-based wet flue gas desulfurizer (FGD) designed to remove sulphur dioxide (SO{sub 2}) from a coker train. Syncrude is also installing the FGD technology at its existing plants. It is expected that installation of the FGDs will reduced total site emissions of SO{sub 2} by 60 per cent. The fluid cokers are used to crack the long hydrocarbon chain bitumen molecules into shorter molecules. It is expected that the FGD system will also reduce particulate and SO{sub 3} levels. The FGD system was selected after an evaluation of technologies used by the coal-fired power industry. A dry FGD system was selected to operate above the water saturation temperature of the flue gas. Calcium oxide was used as a reagent. Hot gas was quenched in a spray dryer absorber with a slurry of calcium hydroxide. Rotary atomizers were used to developer uniform droplets of slurry. The system's fabric filter was a low ratio reverse gas-cleaned unit. Particulate matter from the gases was deposited on the interior of the filter bags. Clean hot gas was drawn through reverse gas fans into a reverse gas manifold. A timeline of the FGD technology installation process was included. 3 tabs., 28 figs.

  2. Deliberating emission reduction options

    Energy Technology Data Exchange (ETDEWEB)

    Dowd, A. M.; Rodriguez, M.; Jeanneret, T. [Commonwealth Scientific and Industrial Research Organisation CSIRO, 37 Graham Rd, Highett VIC 3190 (Australia); De Best-Waldhober, M.; Straver, K.; Mastop, J.; Paukovic, M. [Energy research Centre of the Netherlands ECN, Policy Studies, Amsterdam (Netherlands)

    2012-06-15

    For more than 20 years there has been a concerted international effort toward addressing climate change. International conventions, such as the United Nations Foreign Convention on Climate Change (UNFCCC; ratified in 1994), have been established by committed nations seeking to address global climate change through the reduction of greenhouse gases emitted into the Earth's atmosphere (Global CCS Institute, 2011). Long recognised as the most crucial of the greenhouse gases to impact global warming, the majority of carbon dioxide's anthropogenic global emissions are directly related to fuel combustion of which both Australia and the Netherlands' energy production is significantly reliant. Both these nations will need to consider many opinions and make hard decisions if alternative energy options are to be implemented at the scale that is required to meet international emission targets. The decisions that are required not only need to consider the many options available but also their consequences. Along with politicians, policy developers and industry, the general public also need to be active participants in deciding which energy options, and their subsequent consequences, are acceptable for implementation at the national level. Access to balanced and factual information is essential in establishing informed opinions on the many policy options available. Past research has used several methods to measure public perceptions and opinions yet for complex issues, such as emission reduction, some of these methods have shown to be problematic. For example, semi structured interviews can provide data that is flexible and context rich yet is does also come with the limitations such as it seldom provides a practical assessment that can be utilised from researcher to researcher, across disciplines and public participation techniques. Surveys on the other hand usually address these limitations but surveys that do not encourage comparison of information or ask participants to

  3. Deliberating emission reduction options

    Energy Technology Data Exchange (ETDEWEB)

    Dowd, A.M.; Rodriguez, M.; Jeanneret, T. [Commonwealth Scientific and Industrial Research Organisation CSIRO, 37 Graham Rd, Highett VIC 3190 (Australia); De Best-Waldhober, M.; Straver, K.; Mastop, J.; Paukovic, M. [Energy research Centre of the Netherlands ECN, Policy Studies, Amsterdam (Netherlands)

    2012-06-15

    For more than 20 years there has been a concerted international effort toward addressing climate change. International conventions, such as the United Nations Foreign Convention on Climate Change (UNFCCC; ratified in 1994), have been established by committed nations seeking to address global climate change through the reduction of greenhouse gases emitted into the Earth's atmosphere (Global CCS Institute, 2011). Long recognised as the most crucial of the greenhouse gases to impact global warming, the majority of carbon dioxide's anthropogenic global emissions are directly related to fuel combustion of which both Australia and the Netherlands' energy production is significantly reliant. Both these nations will need to consider many opinions and make hard decisions if alternative energy options are to be implemented at the scale that is required to meet international emission targets. The decisions that are required not only need to consider the many options available but also their consequences. Along with politicians, policy developers and industry, the general public also need to be active participants in deciding which energy options, and their subsequent consequences, are acceptable for implementation at the national level. Access to balanced and factual information is essential in establishing informed opinions on the many policy options available. Past research has used several methods to measure public perceptions and opinions yet for complex issues, such as emission reduction, some of these methods have shown to be problematic. For example, semi structured interviews can provide data that is flexible and context rich yet is does also come with the limitations such as it seldom provides a practical assessment that can be utilised from researcher to researcher, across disciplines and public participation techniques. Surveys on the other hand usually address these limitations but surveys that do not encourage comparison of information or ask

  4. Principal Components as a Data Reduction and Noise Reduction Technique

    Science.gov (United States)

    Imhoff, M. L.; Campbell, W. J.

    1982-01-01

    The potential of principal components as a pipeline data reduction technique for thematic mapper data was assessed and principal components analysis and its transformation as a noise reduction technique was examined. Two primary factors were considered: (1) how might data reduction and noise reduction using the principal components transformation affect the extraction of accurate spectral classifications; and (2) what are the real savings in terms of computer processing and storage costs of using reduced data over the full 7-band TM complement. An area in central Pennsylvania was chosen for a study area. The image data for the project were collected using the Earth Resources Laboratory's thematic mapper simulator (TMS) instrument.

  5. One-photon two-electron processes in helium close to the double ionization threshold; Diexcitation electronique de l'helium par un photon au voisinage du seuil de double ionisation

    Energy Technology Data Exchange (ETDEWEB)

    Bouri, C

    2007-04-15

    This work presents a study of the {sup 1}P{sup 0} excited states of He that can be reached by absorption of a single photon carrying an energy close to the double ionization threshold (DIT) (79 eV). Above the DIT, these states are the double continuum states; below, they are the double excited states. These two types of states are tightly coupled to the single continuum states with or without excitation of the residual ion He{sup +}, owing to their degeneracy in energy. In a one-photon process, these states can only be formed owing to the electronic correlations in the system which must be well described to obtain quantitative good results. Our study is a part of the work which aims at a united description of all these doubly excited, ionized-excited, and double continuum states. We use the Hyperspherical R-Matrix with Semiclassical Outgoing Waves (HRM-SOW) method, initially dedicated to double photoionization studies. We extend it to extract information on the single continuum. This extension allows us to compute cross sections of single photoionization with or without excitation up to n 50 for an excess of 100 meV just above the double ionization threshold. A deep insight into this process is given by a partial waves analysis. The results obtained shed light on the key role of angular and radial correlations. The numerous data we obtain on double and single ionization allow us to establish a continuity relation between these two processes. We show that single ionization with an infinite excitation of the residual ion merges into double photoionization when the excess energy is redistributed between the two electrons. It appears that this relation is valid not only for low but also for high photon energies. Since the HRM-SOW can produce the integrated cross section for double photoionization with high accuracy in the low energy domain, we check the Wannier threshold law. The parameters extracted support strongly this threshold law, and are in good agreement with

  6. Robust methods for data reduction

    CERN Document Server

    Farcomeni, Alessio

    2015-01-01

    Robust Methods for Data Reduction gives a non-technical overview of robust data reduction techniques, encouraging the use of these important and useful methods in practical applications. The main areas covered include principal components analysis, sparse principal component analysis, canonical correlation analysis, factor analysis, clustering, double clustering, and discriminant analysis.The first part of the book illustrates how dimension reduction techniques synthesize available information by reducing the dimensionality of the data. The second part focuses on cluster and discriminant analy

  7. Fraction Reduction in Membrane Systems

    Directory of Open Access Journals (Sweden)

    Ping Guo

    2014-01-01

    Full Text Available Fraction reduction is a basic computation for rational numbers. P system is a new computing model, while the current methods for fraction reductions are not available in these systems. In this paper, we propose a method of fraction reduction and discuss how to carry it out in cell-like P systems with the membrane structure and the rules with priority designed. During the application of fraction reduction rules, synchronization is guaranteed by arranging some special objects in these rules. Our work contributes to performing the rational computation in P systems since the rational operands can be given in the form of fraction.

  8. Logistics Reduction: Heat Melt Compactor

    Data.gov (United States)

    National Aeronautics and Space Administration — The Advanced Exploration Systems (AES) Logistics Reduction (LR) project Heat Melt Compactor (HMC) technology is a waste management technology. Currently, there are...

  9. Nonlinear Model Reduction for RTCVD

    National Research Council Canada - National Science Library

    Newman, Andrew J; Krishnaprasad, P. S

    1998-01-01

    ...) for semiconductor manufacturing. They focus on model reduction for the ordinary differential equation model describing heat transfer to, from, and within a semiconductor wafer in the RTCVD chamber...

  10. Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study

    International Nuclear Information System (INIS)

    Pinakidou, Fani; Kaprara, Efthimia; Katsikini, Maria; Paloura, Eleni C.; Simeonidis, Konstantinos; Mitrakas, Manassis

    2016-01-01

    The feasibility of implementing a Sn(II) oxy-hydroxide (Sn_6O_4(OH)_4) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn_6O_4(OH)_4 for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn_6O_4(OH)_4 can decrease Cr(VI) concentration below the upcoming regulation limit of 10 μg/L for drinking water. Moreover, an uptake capacity of 7.2 μg/mg at breakthrough concentration of 10 μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH)_3 precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO_2, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ("2C) and monodentate ("1V) geometries, at the expense of the present bidentate mononuclear ("2E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn_6O_4(OH)_4 in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the "2C and "1V configurations, which enhances the safe disposal of spent adsorbents. - Highlights: • Effective Cr(VI) removal from drinking water by Sn_6O_4(OH)_4 • Sn_6O_4(OH)_4 transformation to SnO_2 after Cr(VI) reduction to Cr(III) • Strong Cr(III) sorption onto SnO_2 by formation of inner sphere complexes • Cr(III) sorption

  11. Reduction of nitrobenzene with alkaline ascorbic acid: Kinetics and pathways

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chenju, E-mail: cliang@nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan (China); Lin, Ya-Ting [Department of Environmental Engineering, Chung Yuan Christian University, 200 Chung Pei Road, Chung Li District, Taoyuan City 320, Taiwan (China); Shiu, Jia-Wei [Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan (China)

    2016-01-25

    Highlights: • Alkaline ascorbic acid (a.k.a. vitamin C) is capable of reductively degrading NB. • The pH above the pK{sub a2} of ascorbic acid increases reductive electron transfer to NB. • The rate equation for the reactions between NB and AA is determined. • NSB, AZOXY, and AZO are identified as intermediates and aniline as a final product. • Alkaline pH is essential for AA remediation of NB contaminated soils. - Abstract: Alkaline ascorbic acid (AA) exhibits the potential to reductively degrade nitrobenzene (NB), which is the simplest of the nitroaromatic compounds. The nitro group (NO{sub 2}{sup −}) of NB has a +III oxidation state of the N atom and tends to gain electrons. The effect of alkaline pH ranging from 9 to 13 was initially assessed and the results demonstrated that the solution pH, when approaching or above the pK{sub a2} of AA (11.79), would increase reductive electron transfer to NB. The rate equation for the reactions between NB and AA at pH 12 can be described as r = ((0.89 ± 0.11) × 10{sup −4} mM{sup 1−(a} {sup +} {sup b)} h{sup −1}) × [NB]{sup a} {sup =} {sup 1.35} {sup ±} {sup 0.10}[AA]{sup b} {sup =} {sup 0.89} {sup ±} {sup 0.01}. The GC/MS analytical method identified nitrosobenzene, azoxybenzene, and azobenzene as NB reduction intermediates, and aniline (AN) as a final product. These experimental results indicate that the alkaline AA reduction of NB to AN mainly proceeds via the direct route, consisting of a series of two-electron or four-electron transfers, and the condensation reaction plays a minor route. Preliminary evaluation of the remediation of spiked NB contaminated soils revealed that maintenance of alkaline pH and a higher water to soil ratio are essential for a successful alkaline AA application.

  12. Confluence reduction for probabilistic systems

    NARCIS (Netherlands)

    Timmer, Mark; van de Pol, Jan Cornelis; Stoelinga, Mariëlle Ida Antoinette

    In this presentation we introduce a novel technique for state space reduction of probabilistic specifications, based on a newly developed notion of confluence for probabilistic automata. We proved that this reduction preserves branching probabilistic bisimulation and can be applied on-the-fly. To

  13. Aircraft Noise Reduction Subproject Overview

    Science.gov (United States)

    Fernandez, Hamilton; Nark, Douglas M.; Van Zante, Dale E.

    2016-01-01

    The material presents highlights of propulsion and airframe noise research being completed for the Advanced Air Transport Technology Project. The basis of noise reduction plans along with representative work for the airframe, propulsion, and propulsion-airframe integration is discussed for the Aircraft Noise reduction Subproject.

  14. Casting light on harm reduction

    DEFF Research Database (Denmark)

    Jourdan, Michael

    2009-01-01

    Background: Harm reduction is commonly regarded as complementary to other drug problem responses - as the fourth tier. Yet even core examples of harm reduction such as the provision of injection equipment and methadone treatment has over and over encountered considerable opposition, and harm redu...

  15. Reduction of chemical reaction models

    Science.gov (United States)

    Frenklach, Michael

    1991-01-01

    An attempt is made to reconcile the different terminologies pertaining to reduction of chemical reaction models. The approaches considered include global modeling, response modeling, detailed reduction, chemical lumping, and statistical lumping. The advantages and drawbacks of each of these methods are pointed out.

  16. Comments on Beckmann's Uniform Reducts

    OpenAIRE

    Cook, Stephen

    2006-01-01

    Arnold Beckmann defined the uniform reduct of a propositional proof system f to be the set of those bounded arithmetical formulas whose propositional translations have polynomial size f-proofs. We prove that the uniform reduct of f + Extended Frege consists of all true bounded arithmetical formulas iff f + Extended Frege simulates every proof system.

  17. Chronic sleep reduction in adolescents

    NARCIS (Netherlands)

    Dewald-Kaufmann, J.F.

    2012-01-01

    Based on the results of this thesis, it can be concluded that sleep problems and chronic sleep reduction have a high impact on adolescents’ daytime functioning. Additionally, this research shows that gradual sleep extension can improve adolescents’ sleep and especially their chronic sleep reduction.

  18. Biochemistry of Catabolic Reductive Dehalogenation.

    Science.gov (United States)

    Fincker, Maeva; Spormann, Alfred M

    2017-06-20

    A wide range of phylogenetically diverse microorganisms couple the reductive dehalogenation of organohalides to energy conservation. Key enzymes of such anaerobic catabolic pathways are corrinoid and Fe-S cluster-containing, membrane-associated reductive dehalogenases. These enzymes catalyze the reductive elimination of a halide and constitute the terminal reductases of a short electron transfer chain. Enzymatic and physiological studies revealed the existence of quinone-dependent and quinone-independent reductive dehalogenases that are distinguishable at the amino acid sequence level, implying different modes of energy conservation in the respective microorganisms. In this review, we summarize current knowledge about catabolic reductive dehalogenases and the electron transfer chain they are part of. We review reaction mechanisms and the role of the corrinoid and Fe-S cluster cofactors and discuss physiological implications.

  19. Reduction mechanisms of ethylene carbonate on si anodes of lithium-ion batteries: effects of degree of lithiation and nature of exposed surface.

    Science.gov (United States)

    Martinez de la Hoz, Julibeth M; Leung, Kevin; Balbuena, Perla B

    2013-12-26

    Ab initio molecular dynamics simulations are used to identify mechanisms of reduction of ethylene carbonate on Si surfaces at various degrees of lithiation, where the low-coordinated surface Si atoms are saturated with O, OH, or H functional groups. The lowest Si content surfaces are represented by quasi-amorphous LiSi4 and LiSi2; intermediate lithiation is given by LiSi crystalline facets, and the highest Li content is studied through Li13Si4 surfaces. It is found that ethylene carbonate (EC) reduction mechanisms depend significantly on the degree of lithiation of the surface. On LiSi surfaces EC is reduced according to two different two-electron mechanisms (one simultaneous and one sequential), which are independent of specific surface functionalization or nature of exposed facets. On the less lithiated surfaces, the simultaneous two-electron reduction is found more frequently. In that mechanism, the EC reduction is initiated by the formation of a C-Si bond that allows adsorption of the intact molecule to the surface and is followed by electron transfer and ring-opening. Strongly lithiated Li13Si4 surfaces are found to be highly reactive. Reduction of adsorbed EC molecules occurs via a four-electron mechanism yielding as reduction products CO(2-) and O(C2H4)O(2-). Direct transfer of two electrons to EC molecules in liquid phase is also possible, resulting in the presence of O(C2H4)OCO(2-) anions in the liquid phase.

  20. Determination of reduction yield of lithium metal reduction process

    International Nuclear Information System (INIS)

    Choi, In Kyu; Cho, Young Hwan; Kim, Taek Jin; Jee, Kwang Young

    2004-01-01

    Metal reduction of spent oxide fuel is the first step for the effective storage of spent fuel in Korea as well as transmutation purpose of long-lived radio-nuclides. During the reduction of uranium oxide by lithium metal to uranium metal, lithium oxide is stoichiometrically produced. By determining the concentration of lithium oxide in lithium chloride, we can estimate that how much uranium oxide is converted to uranium metal. Previous method to determine the lithium oxide concentration in lithium chloride is tedious and timing consuming. This paper describe the on-line monitoring method of lithium oxide during the reduction process

  1. The impact of electrochemical reduction potentials on the electrocatalytic activity of graphene oxide toward the oxygen reduction reaction in an alkaline medium

    International Nuclear Information System (INIS)

    Toh, Shaw Yong; Loh, Kee Shyuan; Kamarudin, Siti Kartom; Daud, Wan Ramli Wan

    2016-01-01

    We report the synthesis of graphene via the electrochemical reduction of graphene oxide (GO). In this study, GO nanosheets from aqueous dispersion were pre-assembled on a glassy carbon (GC) electrode and then electrochemically reduced in 1 M KOH under various constant reduction potentials in the range of −0.6 V to −1.5 V (vs. Ag/AgCl). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses revealed that the graphitic structure was substantially restored in the resulting electrochemically reduced graphene oxide (ERGO). The ERGO electrodes exhibited significantly enhanced catalytic activity toward the oxygen reduction reaction (ORR) in an alkaline medium compared with the initial GO electrode. Of the ERGO electrodes produced at various cathodic potentials, the ERGO-1.2 V electrode, which was produced at a reduction potential of −1.2 V, demonstrated the best catalytic activity toward the ORR in an alkaline medium. The ORR on GO and ERGO electrodes was shown to proceed via a two-electron mechanism at low overpotentials. The agreement between the spectroscopy results and electrochemical measurements provide strong evidence that the enhanced ORR catalytic activity is mainly attributed to the restoration of GO’s graphitic structure. Furthermore, the ERGO-1.2 V electrode showed excellent tolerance to the methanol poisoning effect compared with a Pt/C catalyst electrode.

  2. Nanocomposite films containing Au nanoparticles formed by electrochemical reduction of metal ions in the multilayer films as electrocatalyst for dioxygen reduction

    International Nuclear Information System (INIS)

    Huang Minghua; Shen Yan; Cheng Wenlong; Shao Yong; Sun Xuping; Liu Baifeng; Dong Shaojun

    2005-01-01

    Through electrostatic layer-by-layer assembly, AuCl 4 - anions and [tetrakis(N-methylpyridyl)porphyrinato] cobalt (CoTMPyP) cations were alternately deposited on indium tin oxide (ITO) substrates, and 4-aminobenzoic acid modified glassy carbon electrode. Electrochemical reduction of AuCl 4 - anions sandwiched between CoTMPyP layers leads to the in situ formation of Au nanoparticles in the multilayer films. Regular growth of the multilayer films is monitored by UV-vis spectroscopy. UV-vis spectroscopy, X-ray photoelectron spectroscopy and cyclic voltammetry confirm the formation of Au nanoparticles in the multilayer films after electrochemical reduction of AuCl 4 - anions. Atomic force spectroscopy verifies that the as-prepared Au nanoparticles are uniformly distributed with average particles diameters of 20-25 nm. The resulting composite films containing Au nanoparticles with high stability exhibit high electrocatalytic activity for the reduction of dioxygen. Rotating disk electrode voltammetry and rotating ring-disk electrode voltammetry demonstrate the Au nanoparticles-containing films can catalyze two-electron reduction of O 2 to H 2 O 2 in O 2 -saturated 0.1 M H 2 SO 4 solution

  3. New Mechanism for the Reduction of Vanadyl Acetylacetonate to Vanadium Acetylacetonate for Room Temperature Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shamie, Jack S. [Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago Illinois 60616 USA; Liu, Caihong [Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago Illinois 60616 USA; Shaw, Leon L. [Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago Illinois 60616 USA; Sprenkle, Vincent L. [Energy Storage and Conversion Energy Materials, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2016-12-29

    In this study, a new mechanism for the reduction of vanadyl acetylacetonate, VO(acac)2, to vanadium acetylacetonate, V(acac)3, is introduced. V(acac)3 has been studied for use in redox flow batteries (RFBs) for some time; however, contamination by moisture leads to the formation of VO(acac)2. In previous work, once this transformation occurs, it is no longer reversible because there is a requirement for extreme low potentials for the reduction to occur. Here, we propose that, in the presence of excess acetylacetone (Hacac) and free protons (H+), the reduction can take place between 2.25 and 1.5 V versus Na/Na+ via a one-electron-transfer reduction. This reduction can take place in situ during discharge in a novel hybrid Na-based flow battery (HNFB) with a molten Na–Cs alloy as the anode. The in situ recovery of V(acac)3 during discharge is shown to allow the Coulombic efficiency of the HNFB to be ≈100 % with little or no capacity decay over cycles. In addition, utilizing two-electron-transfer redox reactions (i.e., V3+/V4+ and V2+/V3+ redox couples) per V ion to increase the energy density of RFBs becomes possible owing to the in situ recovery of V(acac)3 during discharge. The concept of in situ recovery of material can lead to more advances in maintaining the cycle life of RFBs in the future.

  4. Cost reduction through system integration

    International Nuclear Information System (INIS)

    Helsing, P.

    1994-01-01

    In resent years cost reduction has been a key issue in the petroleum industry. Several findings are not economically attractive at the current cost level, and for this and other reasons some of the major oil companies require the suppliers to have implemented a cost reduction programme to prequalify for projects. The present paper addresses cost reduction through system design and integration in both product development and working methods. This is to be obtained by the combination of contracts by reducing unnecessary coordination and allow re-use of proven interface designs, improve subsystem integration by ''top down'' system design, and improve communication and exchange of experience. 3 figs

  5. Chemical model reduction under uncertainty

    KAUST Repository

    Malpica Galassi, Riccardo; Valorani, Mauro; Najm, Habib N.; Safta, Cosmin; Khalil, Mohammad; Ciottoli, Pietro P.

    2017-01-01

    A general strategy for analysis and reduction of uncertain chemical kinetic models is presented, and its utility is illustrated in the context of ignition of hydrocarbon fuel–air mixtures. The strategy is based on a deterministic analysis

  6. Acute IPPS - Readmissions Reduction Program

    Data.gov (United States)

    U.S. Department of Health & Human Services — Section 3025 of the Affordable Care Act added section 1886(q) to the Social Security Act establishing the Hospital Readmissions Reduction Program, which requires CMS...

  7. Fermion masses from dimensional reduction

    International Nuclear Information System (INIS)

    Kapetanakis, D.; Zoupanos, G.

    1990-01-01

    We consider the fermion masses in gauge theories obtained from ten dimensions through dimensional reduction on coset spaces. We calculate the general fermion mass matrix and we apply the mass formula in illustrative examples. (orig.)

  8. Fermion masses from dimensional reduction

    Energy Technology Data Exchange (ETDEWEB)

    Kapetanakis, D. (National Research Centre for the Physical Sciences Democritos, Athens (Greece)); Zoupanos, G. (European Organization for Nuclear Research, Geneva (Switzerland))

    1990-10-11

    We consider the fermion masses in gauge theories obtained from ten dimensions through dimensional reduction on coset spaces. We calculate the general fermion mass matrix and we apply the mass formula in illustrative examples. (orig.).

  9. Reduction and determination of dixanthogens.

    Science.gov (United States)

    Prasad, M S

    1971-06-01

    A convenient method for the reduction and determination of dixaathogen has been developed. It is based on the quantitative reaction of dixanthogen with zinc amalgam to form xanthate; the latter can be determined by iodine titration, potentiometric titration with silver nitrate or by spectrophotometry at 310 mmu. Dixanthogen can be determined in mixtures containing xanthate, by titration of aliquots with and without reduction. Higher dixanthogens can also be determined, and flotation liquors analysed.

  10. Chemical model reduction under uncertainty

    KAUST Repository

    Najm, Habib; Galassi, R. Malpica; Valorani, M.

    2016-01-01

    We outline a strategy for chemical kinetic model reduction under uncertainty. We present highlights of our existing deterministic model reduction strategy, and describe the extension of the formulation to include parametric uncertainty in the detailed mechanism. We discuss the utility of this construction, as applied to hydrocarbon fuel-air kinetics, and the associated use of uncertainty-aware measures of error between predictions from detailed and simplified models.

  11. Chemical model reduction under uncertainty

    KAUST Repository

    Najm, Habib

    2016-01-05

    We outline a strategy for chemical kinetic model reduction under uncertainty. We present highlights of our existing deterministic model reduction strategy, and describe the extension of the formulation to include parametric uncertainty in the detailed mechanism. We discuss the utility of this construction, as applied to hydrocarbon fuel-air kinetics, and the associated use of uncertainty-aware measures of error between predictions from detailed and simplified models.

  12. Electrochemical Reduction Process for Pyroprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Eun-Young; Hong, Sun-Seok; Park, Wooshin; Im, Hun Suk; Oh, Seung-Chul; Won, Chan Yeon; Cha, Ju-Sun; Hur, Jin-Mok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-06-15

    Nuclear energy is expected to meet the growing energy demand while avoiding CO{sub 2} emission. However, the problem of accumulating spent fuel from current nuclear power plants which is mainly composed of uranium oxides should be addressed. One of the most practical solutions is to reduce the spent oxide fuel and recycle it. Next-generation fuel cycles demand innovative features such as a reduction of the environmental load, improved safety, efficient recycling of resources, and feasible economics. Pyroprocessing based on molten salt electrolysis is one of the key technologies for reducing the amount of spent nuclear fuel and destroying toxic waste products, such as the long-life fission products. The oxide reduction process based on the electrochemical reduction in a LiCl-Li{sub 2}O electrolyte has been developed for the volume reduction of PWR (Pressurized Water Reactor) spent fuels and for providing metal feeds for the electrorefining process. To speed up the electrochemical reduction process, the influences of the feed form for the cathode and the type of anode shroud on the reduction rate were investigated.

  13. INEL waste reduction: summary paper

    International Nuclear Information System (INIS)

    Rhoades, W.A.

    1987-01-01

    The Idaho National Engineering Laboratory (INEL) is a Department of Energy (DOE) facility located in southeastern Idaho. Located at the INEL are a Waste Experimental Reduction Facility (WERF) which processes low level radioactive waste (LLW) materials and a Radioactive Waste Management Complex (RWMC) which provides for disposal of radioactive waste materials. There are currently 9 active facilities (waste generators) at the INEL which produce an average total volume of about 5000 cubic meters of solid LLW annually. This boxed or bulk waste is ultimately disposed of at the RWMC Subsurface Disposal Area (SDA). The SDA is currently the only active LLW disposal site at the INEL, and the prospects for opening another shallow land burial disposal facility are uncertain. Therefore, it has become imperative that EG and G Idaho Waste Management Department make every reasonable effort to extend the disposal life of the SDA. Among Waste Management Department's principal efforts to extend the SDA disposal life are operation of the Waste Experimental Reduction Facility (WERF) and administration of the INEL Waste Reduction Program. The INEL Waste Reduction Program is charged with providing assistance to all INEL facilities in reducing LLW generation rates to the lowest practical levels while at the same time encouraging optimum utilization of the volume reduction capabilities of WERF. Both waste volume and waste generation reductions are discussed

  14. State of the direct reduction and reduction smelting processes

    Directory of Open Access Journals (Sweden)

    Markotić A.

    2002-01-01

    Full Text Available For quite a long time efforts have been made to develop processes for producing iron i.e. steel without employing conventional procedures - from ore, coke, blast furnace, iron, electric arc furnace, converter to steel. The insufficient availability and the high price of the coking coals have forced many countries to research and adopt the non-coke-consuming reduction and metal manufacturing processes (non-coke metallurgy, direct reduction, direct processes. This paper represents a survey of the most relevant processes from this domain by the end of 2000, which display a constant increase in the modern process metallurgy.

  15. Unfavourable results following reduction mammoplasty

    Directory of Open Access Journals (Sweden)

    Lakshmi Saleem

    2013-01-01

    Full Text Available Breast reduction is a common cosmetic surgical procedure. It aims not only at bringing down the size of the breast proportionate to the build of the individual, but also to overcome the discomfort caused by massive, ill-shaped and hanging breasts. The operative procedure has evolved from mere reduction of breast mass to enhanced aesthetic appeal with a minimum of scar load. The selection of technique needs to be individualised. Bilateral breast reduction is done most often. Haematoma, seroma, fat necrosis, skin loss, nipple loss and unsightly, painful scars can be the complications of any procedure on the breast. These may result from errors in judgement, wrong surgical plan and imprecise execution of the plan. Though a surfeit of studies are available on breast reduction, very few dwell upon its complications. The following article is a distillation of three decades of experience of the senior author (L.S. in reduction mammoplasty. An effort is made to understand the reasons for unfavourable results. To conclude, most complications can be overcome with proper selection of procedure for the given patient and with gentle tissue handling.

  16. A Virtual Aluminum Reduction Cell

    Science.gov (United States)

    Zhang, Hongliang; Zhou, Chenn Q.; Wu, Bing; Li, Jie

    2013-11-01

    The most important component in the aluminum industry is the aluminum reduction cell; it has received considerable interests and resources to conduct research to improve its productivity and energy efficiency. The current study focused on the integration of numerical simulation data and virtual reality technology to create a scientifically and practically realistic virtual aluminum reduction cell by presenting complex cell structures and physical-chemical phenomena. The multiphysical field simulation models were first built and solved in ANSYS software (ANSYS Inc., Canonsburg, PA, USA). Then, the methodology of combining the simulation results with virtual reality was introduced, and a virtual aluminum reduction cell was created. The demonstration showed that a computer-based world could be created in which people who are not analysis experts can see the detailed cell structure in a context that they can understand easily. With the application of the virtual aluminum reduction cell, even people who are familiar with aluminum reduction cell operations can gain insights that make it possible to understand the root causes of observed problems and plan design changes in much less time.

  17. Model reduction of parametrized systems

    CERN Document Server

    Ohlberger, Mario; Patera, Anthony; Rozza, Gianluigi; Urban, Karsten

    2017-01-01

    The special volume offers a global guide to new concepts and approaches concerning the following topics: reduced basis methods, proper orthogonal decomposition, proper generalized decomposition, approximation theory related to model reduction, learning theory and compressed sensing, stochastic and high-dimensional problems, system-theoretic methods, nonlinear model reduction, reduction of coupled problems/multiphysics, optimization and optimal control, state estimation and control, reduced order models and domain decomposition methods, Krylov-subspace and interpolatory methods, and applications to real industrial and complex problems. The book represents the state of the art in the development of reduced order methods. It contains contributions from internationally respected experts, guaranteeing a wide range of expertise and topics. Further, it reflects an important effor t, carried out over the last 12 years, to build a growing research community in this field. Though not a textbook, some of the chapters ca...

  18. Thermodynamics of lunar ilmenite reduction

    Science.gov (United States)

    Altenberg, B. H.; Franklin, H. A.; Jones, C. H.

    1993-01-01

    With the prospect of returning to the moon, the development of a lunar occupation would fulfill one of the goals of the Space Exploration Initiative (SEI) of the late 1980's. Processing lunar resources into useful products, such as liquid oxygen for fuel and life support, would be one of many aspects of an active lunar base. ilmenite (FeTiO3) is found on the lunar surface and can be used as a feed stock to produce oxygen. Understanding the various ilmenite-reduction reactions elucidates many processing options. Defining the thermodynamic chemical behavior at equilibrium under various conditions of temperature and pressures can be helpful in specifying optimal operating conditions. Differences between a previous theoretical analysis and experimentally determined results has sparked interest in trying to understand the effect of operating pressure on the hydrogen-reduction-of-ilmenite reaction. Various aspects of this reduction reaction are discussed.

  19. Microbial reduction of iron ore

    Science.gov (United States)

    Hoffmann, M.R.; Arnold, R.G.; Stephanopoulos, G.

    1989-11-14

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry. 11 figs.

  20. Outage reduction of Hamaoka NPS

    International Nuclear Information System (INIS)

    Hida, Shigeru; Anma, Minoru

    1999-01-01

    In the Hamaoka nuclear power plant, we have worked on the outage reduction since 1993. In those days, the outage length in Hamaoka was 80 days or more, and was largely far apart from excellent results of European and American plants about the 30days. A concrete strategy to achieve the reduction process is the extension of working hours, the changing work schedule control unit for every hour, the equipment improvements, and the improvements of work environments, etc. We executed them one by one reflecting results. As a result, we achieved the outage for 57 days in 1995. Starting from this, we acquired the further outage reduction one by one and achieved the outage for 38 days in 1997 while maintaining safety and reliability of the plant. We advance these strategies further and we will aim at the achievement of the 30·35 days outage in the future. (author)

  1. Representative mass reduction in sampling

    DEFF Research Database (Denmark)

    Petersen, Lars; Esbensen, Harry Kim; Dahl, Casper Kierulf

    2004-01-01

    We here present a comprehensive survey of current mass reduction principles and hardware available in the current market. We conduct a rigorous comparison study of the performance of 17 field and/or laboratory instruments or methods which are quantitatively characterized (and ranked) for accuracy...... dividers, the Boerner Divider, the ??spoon method??, alternate/fractional shoveling and grab sampling. Only devices based on riffle splitting principles (static or rotational) passes the ultimate representativity test (with minor, but significant relative differences). Grab sampling, the overwhelmingly...... most often used mass reduction method, performs appallingly?its use must be discontinued (with the singular exception for completely homogenized fine powders). Only proper mass reduction (i.e. carried out in complete compliance with all appropriate design principles, maintenance and cleaning rules) can...

  2. Solid-phase reduction of silico-12-molybdic acid H4SiMo12O40 by some organic oxygen containing compounds

    International Nuclear Information System (INIS)

    Chuvaev, V.F.; Pinchuk, I.N.; Spitsyn, V.I.

    1982-01-01

    A study is made on reduction reactions of anhydrous silico-12-molybdic acid by vapors of organic oxygen-containing compounds at 170 deg C: alcohols, simple carbonyl compounds. Methods of thermal analysis, electron paramagnetic resonance, paramagnetic resonance were used to established that depending on the nature of organic reagent and temperature, H 6 SiMo 2 5 Mo 10 6 O 40 two-electron or H 8 SiMo 4 5 Mo 8 6 O 40 four-electron flues form. It is shown that the increase of heterogeneous reduction temperature can lead to formation of anhydrous phases of SiMo 12 O 38 -(n/2), able to attach water reversibly with formation of corresponding blue. Characteristics of blues, prepared during solid-phase reduction of silico-12-molybdic acid and mixed valent forms with corresponding reduction degree, separated from water solutions, were compared

  3. Catalytic reduction of ruthenium tetroxide

    International Nuclear Information System (INIS)

    Nakhutin, I.E.; Polyakov, A.S.; Ananyan, O.S.; Blinnikov, S.A.; Kulakov, A.I.; Takmazyan, A.S.

    1978-01-01

    RuO 4 removal from the gaseous phase by reduction to solid RuO 2 with carbon oxide has been investigated. The reaction has been shown to be autocatalytic. A catalyst (RuO 2 on Al 2 O 3 ) for the reduction has been developed. There have been determined the region of reaction RuO 4 +CO on the catalyst containing RuO 2 , the temperature dependence of the decontamination factor and the reaction order in RuO 4 . The feasibility of RuO 4 thermal decomposition on the catalyst has been shown. A number of other metal oxides that can catalyze the process is listed

  4. Bohm's theory versus dynamical reduction

    International Nuclear Information System (INIS)

    Ghirardi, G.C.; Grassi, R.

    1995-10-01

    This essay begins with a comparison between Bohm's theory and the dynamical reduction program. While there are similarities (e.g., the preferred basis), there are also important differences (e.g., the type of nonlocality or of Lorentz invariance). In particular, it is made plausible that theories which exhibit parameter dependence effects cannot be ''genuinely Lorentz invariant''. For the two approaches under consideration, this analysis provides a comparison that can produce a richer understanding both of the pilot wave and of the dynamical reduction mechanism. (author). 33 refs, 1 fig

  5. NEC-2020 emission reduction scenarios

    DEFF Research Database (Denmark)

    Slentø, Erik; Nielsen, Ole-Kenneth; Hoffmann, Leif

    The upcoming NEC-2020 EU directive sets up emission ceilings for NOX, SO2, NH3, NMVOC and PM in order to meet the environmental exposure targets of the Thematic Strategy. This report contains an assessment of intermediary emission reduction scenarios for Denmark, computed by the GAINS model 2007,......, which serves as the basis for the pending negotiations in EU. The assessment is brought up to date by including a brief evaluation of the new reduction scenarios published in 2008, founding the European Commission NEC-2020 directive proposal....

  6. Morphologisation or Reduction by Context?

    DEFF Research Database (Denmark)

    Heegård Petersen, Jan

    2013-01-01

    of regression analysis which shows that also a following sound or pause, word form frequency and social class are factors that contribute significantly to the reduction pattern of the variable (te). The study cannot find any effects of clitizisation or n-gram based contextual predictability, factors...

  7. GumTree: Data reduction

    Energy Technology Data Exchange (ETDEWEB)

    Rayner, Hugh [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)]. E-mail: hrz@ansto.gov.au; Hathaway, Paul [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Hauser, Nick [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Fei, Yang [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Franceschini, Ferdi [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Lam, Tony [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    2006-11-15

    Access to software tools for interactive data reduction, visualisation and analysis during a neutron scattering experiment enables instrument users to make informed decisions regarding the direction and success of their experiment. ANSTO aims to enhance the experiment experience of its facility's users by integrating these data reduction tools with the instrument control interface for immediate feedback. GumTree is a software framework and application designed to support an Integrated Scientific Experimental Environment, for concurrent access to instrument control, data acquisition, visualisation and analysis software. The Data Reduction and Analysis (DRA) module is a component of the GumTree framework that allows users to perform data reduction, correction and basic analysis within GumTree while an experiment is running. It is highly integrated with GumTree, able to pull experiment data and metadata directly from the instrument control and data acquisition components. The DRA itself uses components common to all instruments at the facility, providing a consistent interface. It features familiar ISAW-based 1D and 2D plotting, an OpenGL-based 3D plotter and peak fitting performed by fityk. This paper covers the benefits of integration, the flexibility of the DRA module, ease of use for the interface and audit trail generation.

  8. Intraoperative hydrostatic reduction of intussusception

    Directory of Open Access Journals (Sweden)

    Chatterjee Uday

    2008-01-01

    Full Text Available Aims: To find out an easier way of reduction of intussusception during open surgery to avoid unnecessary bowel injury. Materials and Methods: Under general anesthesia, before laparotomy, warm normal saline was infused into the rectum with a Foley catheter and an intravenous drip set maintaining the level of the bottle at 80 cm above the operating table. After opening the abdomen, pressure was applied on the colon filled with normal saline distal to the intussusceptum. The pressure was transmitted to the intussusceptum and the walls of the intussuscipient and caused reduction of intussusception without any injury to the intussuscipient and intussusceptum. This procedure was performed on those patients on whom laparotomy was performed as a primary procedure due to nonavailability of fluoroscopy or ultrasonography. Results: Between August 1998 and July 2005, we had six patients of mean (range age 11 months (7-17 months. In two cases, at laparotomy, the intussusceptions were found to have already reduced. Conclusions: Gentle finger pressure is necessary for reduction of intussusception. This subjective "gentleness" is dependant on experience of the surgeon and varies from person to person. Focal pressure on the intussuscipient and apex of the intussusceptum by the finger during reduction may be more damaging than the diffusely transmitted hydrostatic pressure even by a less-experienced surgeon. This will avoid the needless resection and anastomosis of the intestine on many occasions.

  9. Sex-work harm reduction.

    Science.gov (United States)

    Rekart, Michael L

    2005-12-17

    Sex work is an extremely dangerous profession. The use of harm-reduction principles can help to safeguard sex workers' lives in the same way that drug users have benefited from drug-use harm reduction. Sex workers are exposed to serious harms: drug use, disease, violence, discrimination, debt, criminalisation, and exploitation (child prostitution, trafficking for sex work, and exploitation of migrants). Successful and promising harm-reduction strategies are available: education, empowerment, prevention, care, occupational health and safety, decriminalisation of sex workers, and human-rights-based approaches. Successful interventions include peer education, training in condom-negotiating skills, safety tips for street-based sex workers, male and female condoms, the prevention-care synergy, occupational health and safety guidelines for brothels, self-help organisations, and community-based child protection networks. Straightforward and achievable steps are available to improve the day-to-day lives of sex workers while they continue to work. Conceptualising and debating sex-work harm reduction as a new paradigm can hasten this process.

  10. Reduction des effectifs ou licenciements

    CERN Multimedia

    Maiani, Luciano

    2002-01-01

    "Vous faites un amalgame entre la reduction en cours des effectifs du CERN (organisation europeenne pour la recherche nucleaire) et les economies que le laboratoire doit realiser dans les cinq ans a venir pour financer le projet de grand collisionneur de hadrons (Le Monde du 4 septembre)" (1/2 page).

  11. Noise reduction by wavelet thresholding

    National Research Council Canada - National Science Library

    Jansen, Maarten

    2001-01-01

    .... I rather present new material and own insights in the que stions involved with wavelet based noise reduction . On the other hand , the presented material does cover a whole range of methodologies, and in that sense, the book may serve as an introduction into the domain of wavelet smoothing. Throughout the text, three main properties show up ever again: spar...

  12. Dimensional Reduction and Hadronic Processes

    International Nuclear Information System (INIS)

    Signer, Adrian; Stoeckinger, Dominik

    2008-01-01

    We consider the application of regularization by dimensional reduction to NLO corrections of hadronic processes. The general collinear singularity structure is discussed, the origin of the regularization-scheme dependence is identified and transition rules to other regularization schemes are derived.

  13. Graded geometry and Poisson reduction

    OpenAIRE

    Cattaneo, A S; Zambon, M

    2009-01-01

    The main result of [2] extends the Marsden-Ratiu reduction theorem [4] in Poisson geometry, and is proven by means of graded geometry. In this note we provide the background material about graded geometry necessary for the proof in [2]. Further, we provide an alternative algebraic proof for the main result. ©2009 American Institute of Physics

  14. Dose reduction - the radiologist's view

    International Nuclear Information System (INIS)

    Russell, J.G.B.

    1984-01-01

    The magnitude of the exposure to ionising radiation dominates radiological practice in only three fields, i.e. foetal radiography, mammography and computed tomography. The balance between risk and benefit are briefly examined. The types of hazard considered are carcinogenesis, genetic injury and organogenesis. Ways of achieving a reduction of the dose to the patient are also briefly discussed. (U.K.)

  15. Basis reduction for layered lattices

    NARCIS (Netherlands)

    E.L. Torreão Dassen (Erwin)

    2011-01-01

    htmlabstractWe develop the theory of layered Euclidean spaces and layered lattices. With this new theory certain problems that usually are solved by using classical lattices with a "weighting" gain a new, more natural form. Using the layered lattice basis reduction algorithms introduced here these

  16. GumTree: Data reduction

    International Nuclear Information System (INIS)

    Rayner, Hugh; Hathaway, Paul; Hauser, Nick; Fei, Yang; Franceschini, Ferdi; Lam, Tony

    2006-01-01

    Access to software tools for interactive data reduction, visualisation and analysis during a neutron scattering experiment enables instrument users to make informed decisions regarding the direction and success of their experiment. ANSTO aims to enhance the experiment experience of its facility's users by integrating these data reduction tools with the instrument control interface for immediate feedback. GumTree is a software framework and application designed to support an Integrated Scientific Experimental Environment, for concurrent access to instrument control, data acquisition, visualisation and analysis software. The Data Reduction and Analysis (DRA) module is a component of the GumTree framework that allows users to perform data reduction, correction and basic analysis within GumTree while an experiment is running. It is highly integrated with GumTree, able to pull experiment data and metadata directly from the instrument control and data acquisition components. The DRA itself uses components common to all instruments at the facility, providing a consistent interface. It features familiar ISAW-based 1D and 2D plotting, an OpenGL-based 3D plotter and peak fitting performed by fityk. This paper covers the benefits of integration, the flexibility of the DRA module, ease of use for the interface and audit trail generation

  17. Sulfate reduction in freshwater peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Oequist, M.

    1996-12-31

    This text consist of two parts: Part A is a literature review on microbial sulfate reduction with emphasis on freshwater peatlands, and part B presents the results from a study of the relative importance of sulfate reduction and methane formation for the anaerobic decomposition in a boreal peatland. The relative importance of sulfate reduction and methane production for the anaerobic decomposition was studied in a small raised bog situated in the boreal zone of southern Sweden. Depth distribution of sulfate reduction- and methane production rates were measured in peat sampled from three sites (A, B, and C) forming an minerotrophic-ombrotrophic gradient. SO{sub 4}{sup 2-} concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 {mu}M. In contrast, rates of sulfate reduction were vastly different: Maximum rates in the three profiles were obtained at a depth of ca. 20 cm below the water table. In A it was 8 {mu}M h{sup -1} while in B and C they were 1 and 0.05 {mu}M h{sup -1}, respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 {mu}g d{sup -1} g{sup -1}) were found 10 cm below the water table, in B (ca. 1.0 {mu}g d{sup -1} g{sup -1}) in the vicinity of the water table, and in C (0.75 {mu}g d{sup -1} g{sup -1}) 20 cm below the water table. In all profiles both sulfate reduction and methane production rates were negligible above the water table. The areal estimates of methane production for the profiles were 22.4, 9.0 and 6.4 mmol m{sup -2} d{sup -1}, while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m{sup -2} d{sup -1}, respectively. The calculated turnover times at the sites were 1.2, 14.2, and 198.7 days, respectively. The study shows that sulfate reducing bacteria are important for the anaerobic degradation in the studied peatland, especially in the minerotrophic sites, while methanogenic bacteria dominate in ombrotrophic sites Examination

  18. Sulfate reduction in freshwater peatlands

    International Nuclear Information System (INIS)

    Oequist, M.

    1996-01-01

    This text consist of two parts: Part A is a literature review on microbial sulfate reduction with emphasis on freshwater peatlands, and part B presents the results from a study of the relative importance of sulfate reduction and methane formation for the anaerobic decomposition in a boreal peatland. The relative importance of sulfate reduction and methane production for the anaerobic decomposition was studied in a small raised bog situated in the boreal zone of southern Sweden. Depth distribution of sulfate reduction- and methane production rates were measured in peat sampled from three sites (A, B, and C) forming an minerotrophic-ombrotrophic gradient. SO 4 2- concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 μM. In contrast, rates of sulfate reduction were vastly different: Maximum rates in the three profiles were obtained at a depth of ca. 20 cm below the water table. In A it was 8 μM h -1 while in B and C they were 1 and 0.05 μM h -1 , respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 μg d -1 g -1 ) were found 10 cm below the water table, in B (ca. 1.0 μg d -1 g -1 ) in the vicinity of the water table, and in C (0.75 μg d -1 g -1 ) 20 cm below the water table. In all profiles both sulfate reduction and methane production rates were negligible above the water table. The areal estimates of methane production for the profiles were 22.4, 9.0 and 6.4 mmol m -2 d -1 , while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m -2 d -1 , respectively. The calculated turnover times at the sites were 1.2, 14.2, and 198.7 days, respectively. The study shows that sulfate reducing bacteria are important for the anaerobic degradation in the studied peatland, especially in the minerotrophic sites, while methanogenic bacteria dominate in ombrotrophic sites Examination paper. 67 refs, 6 figs, 3 tabs

  19. Titanium Nitride Nanoparticle Electrocatalysts for Oxygen Reduction Reaction in Alkaline Solution

    KAUST Repository

    Ohnishi, R.; Katayama, M.; Cha, Dong Kyu; Takanabe, Kazuhiro; Kubota, J.; Domen, K.

    2013-01-01

    Monodispersed TiN nanoparticles with a narrow size distribution (7–23 nm) were synthesized using mesoporous graphitic (mpg)-C3N4 templates with different pore sizes. The nano-materials were examined as electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. The TiN nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 sorption, transmission electron microscopy (TEM), and C-H-N elemental analysis. The ORR current increased as the TiN particle size decreased, and hence the surface area of TiN nanoparticles reactive to ORR increased. Rotating ring disk electrode (RRDE) measurements revealed that the ORR on TiN surfaces proceeded mainly via a two-electron pathway, producing H2O2 as the main product. Mechanistic aspects of ORR on TiN surfaces are discussed.

  20. Titanium Nitride Nanoparticle Electrocatalysts for Oxygen Reduction Reaction in Alkaline Solution

    KAUST Repository

    Ohnishi, R.

    2013-03-12

    Monodispersed TiN nanoparticles with a narrow size distribution (7–23 nm) were synthesized using mesoporous graphitic (mpg)-C3N4 templates with different pore sizes. The nano-materials were examined as electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. The TiN nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 sorption, transmission electron microscopy (TEM), and C-H-N elemental analysis. The ORR current increased as the TiN particle size decreased, and hence the surface area of TiN nanoparticles reactive to ORR increased. Rotating ring disk electrode (RRDE) measurements revealed that the ORR on TiN surfaces proceeded mainly via a two-electron pathway, producing H2O2 as the main product. Mechanistic aspects of ORR on TiN surfaces are discussed.

  1. Recursions of Symmetry Orbits and Reduction without Reduction

    Directory of Open Access Journals (Sweden)

    Andrei A. Malykh

    2011-04-01

    Full Text Available We consider a four-dimensional PDE possessing partner symmetries mainly on the example of complex Monge-Ampère equation (CMA. We use simultaneously two pairs of symmetries related by a recursion relation, which are mutually complex conjugate for CMA. For both pairs of partner symmetries, using Lie equations, we introduce explicitly group parameters as additional variables, replacing symmetry characteristics and their complex conjugates by derivatives of the unknown with respect to group parameters. We study the resulting system of six equations in the eight-dimensional space, that includes CMA, four equations of the recursion between partner symmetries and one integrability condition of this system. We use point symmetries of this extended system for performing its symmetry reduction with respect to group parameters that facilitates solving the extended system. This procedure does not imply a reduction in the number of physical variables and hence we end up with orbits of non-invariant solutions of CMA, generated by one partner symmetry, not used in the reduction. These solutions are determined by six linear equations with constant coefficients in the five-dimensional space which are obtained by a three-dimensional Legendre transformation of the reduced extended system. We present algebraic and exponential examples of such solutions that govern Legendre-transformed Ricci-flat Kähler metrics with no Killing vectors. A similar procedure is briefly outlined for Husain equation.

  2. Electrochemical reduction of nitroaromatic compounds by single sheet iron oxide coated electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Li-Zhi, E-mail: lizhi@plen.ku.dk [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Hansen, Hans Christian B. [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Bjerrum, Morten Jannik [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK–2100 København Ø (Denmark)

    2016-04-05

    Highlights: • Composite layers of single sheet iron oxides were coated on indium tin oxide electrodes. • Single sheet iron oxide is an electro-catalyst for reduction of nitroaromatic compounds in aqueous solution. • The reduction is well explained by a diffusion layer model. • The charge properties of the nitrophenols have an important influence on reduction. • Low-cost iron oxide based materials are promising electro-catalyst for water treatment. - Abstract: Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30 μA cm{sup −2} was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400 μM of the nitroaromatic compound at a potential of −0.7 V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant = 0.28 h{sup −1}) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant = 6.9 μM h{sup −1}). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and

  3. Electrochemical Reduction of Oxygen on Anthraquinone/Carbon Nanotubes Nanohybrid Modified Glassy Carbon Electrode in Neutral Medium

    Directory of Open Access Journals (Sweden)

    Zheng Gong

    2013-01-01

    Full Text Available The electrochemical behaviors of monohydroxy-anthraquinone/multiwall carbon nanotubes (MHAQ/MWCNTs nanohybrid modified glassy carbon (MHAQ/MWCNTs/GC electrodes in neutral medium were investigated; also reported was their application in the electrocatalysis of oxygen reduction reaction (ORR. The resulting MHAQ/MWCNTs nanohybrid was characterized by scanning electron microscope (SEM and transmission electron microscope (TEM. It was found that the ORR at the MHAQ/MWCNTs/GC electrode occurs irreversibly at a potential about 214 mV less negative than at a bare GC electrode in pH 7.0 buffer solution. Cyclic voltammetric and rotating disk electrode (RDE techniques indicated that the MHAQ/MWCNTs nanohybrid has high electrocatalytic activity for the two-electron reduction of oxygen in the studied potential range. The kinetic parameters of ORR at the MHAQ/MWCNTs nanohybrid modified GC electrode were also determined by RDE and EIS techniques.

  4. Pathogen reduction of blood components.

    Science.gov (United States)

    Solheim, Bjarte G

    2008-08-01

    Thanks to many blood safety interventions introduced in developed countries the risk of transfusion transmitted infections has become exceedingly small in these countries. However, emerging pathogens still represent a serious challenge, as demonstrated by West Nile virus in the US and more recently by Chikungunya virus in the Indian Ocean. In addition bacterial contamination, particularly in platelets, and protozoa transmitted by blood components still represent sizeable risks in developed countries. In developing countries the risk of all transfusion transmitted infections is still high due to insufficient funding and organisation of the health service. Pathogen reduction of pooled plasma products has virtually eliminated the risk of transfusion transmitted infections, without compromising the quality of the products significantly. Pathogen reduction of blood components has been much more challenging. Solvent detergent treatment which has been so successfully applied for plasma products dissolves cell membranes, and can, therefore, only be applied for plasma and not for cellular blood components. Targeting of nucleic acids has been another method for pathogen inactivation of plasma and the only approach possible for cellular blood products. As documented in more than 15 year's track record, solvent detergent treatment of pooled plasma can yield high quality plasma. The increased risk for contamination by unknown viruses due to pooling is out weighed by elimination of TRALI, significant reduction in allergic reactions and standardisation of the product. Recently, a promising method for solvent detergent treatment of single donor plasma units has been published. Methylene blue light treatment of single donor plasma units has a similar long track record as pooled solvent detergent treated plasma; but the method is less well documented and affects coagulation factor activity more. Psoralen light treated plasma has only recently been introduced (CE marked in Europe

  5. Mechanochemical reduction of copper sulfide

    DEFF Research Database (Denmark)

    Balaz, P.; Takacs, L.; Jiang, Jianzhong

    2002-01-01

    The mechanochemical reduction of copper sulfide with iron was induced in a Fritsch P-6 planetary mill, using WC vial filled with argon and WC balls. Samples milled for specific intervals were analyzed by XRD and Mossbauer spectroscopy. Most of the reaction takes place during the first 10 min...... of milling and only FeS and Cu are found after 60 min. The main chemical process is accompanied by phase transformations of the sulfide phases as a result of milling. Djurleite partially transformed to chalcocite and a tetragonal copper sulfide phase before reduction. The cubic modification of FeS was formed...... first, transforming to hexagonal during the later stages of the process. The formation of off-stoichiometric phases and the release of some elemental sulfur by copper sulfide are also probable....

  6. Random walks on reductive groups

    CERN Document Server

    Benoist, Yves

    2016-01-01

    The classical theory of Random Walks describes the asymptotic behavior of sums of independent identically distributed random real variables. This book explains the generalization of this theory to products of independent identically distributed random matrices with real coefficients. Under the assumption that the action of the matrices is semisimple – or, equivalently, that the Zariski closure of the group generated by these matrices is reductive - and under suitable moment assumptions, it is shown that the norm of the products of such random matrices satisfies a number of classical probabilistic laws. This book includes necessary background on the theory of reductive algebraic groups, probability theory and operator theory, thereby providing a modern introduction to the topic.

  7. Reduction of LNG FOB cost

    International Nuclear Information System (INIS)

    Aoki, Ichizo; Kikkawa, Yoshitsugi

    1997-01-01

    To achieve a competitive LNG price for the consumers against other energy sources, reduction of LNG FOB (Free on Board) cost i.e. LNG cost at LNG ship flange, will be the key item. It is necessary to perform a many optimization studies (or value engineering) for each stage of the LNG project. These stages are: Feasibility study; Conceptual design - FEED (Front End Engineering and Design); EPC (Engineering, Procurement and Construction); Operation and maintenance. Since the LNG plant forms one part of the LNG chain, starting from gas production to LNG receiving, and requires several billion US dollar of investment, the consequences of a plant shut down on the LNG chain are clear, it is, therefore, important to get high availability which will also contribute the reduction of LNG FOB cost. (au) 25 refs

  8. Exploring Paradigms of Crime Reduction

    DEFF Research Database (Denmark)

    Soothill, Keith; Christoffersen, Mogens N.; Hussain, Azhar

    2010-01-01

    Using Danish registers for a 1980 birth cohort of 29,944 males with parental information and following up these cases for 25 years, the study considers four paradigms of crime reduction (parental child rearing, structural factors around adolescence, locality and individual resources). Focusing on...... have more widespread benefits, but the assumed causal links need to be further explored. The use of population registers, under controlled conditions, provides an important window on criminal careers....

  9. An alternative dimensional reduction prescription

    International Nuclear Information System (INIS)

    Edelstein, J.D.; Giambiagi, J.J.; Nunez, C.; Schaposnik, F.A.

    1995-08-01

    We propose an alternative dimensional reduction prescription which in respect with Green functions corresponds to drop the extra spatial coordinate. From this, we construct the dimensionally reduced Lagrangians both for scalars and fermions, discussing bosonization and supersymmetry in the particular 2-dimensional case. We argue that our proposal is in some situations more physical in the sense that it maintains the form of the interactions between particles thus preserving the dynamics corresponding to the higher dimensional space. (author). 12 refs

  10. Precipitation-Static-Reduction Research

    Science.gov (United States)

    1943-03-31

    if» 85 z \\ PRECIPITATION-STATIC-REDUCTION RESEARCH study of the effects of flame length , flame spacing, and burner spacing on B shows that there...unod: Flame length *. The visual length of the flame from the burner tip to the flame tip when examined in a darkened room against a black background...Postlve and Negative Flames The use of the second flame-conduction coefficient, B, facilitates considerably the study of the effect of flame length , spacing

  11. CO2 reduction by dematerialization

    Energy Technology Data Exchange (ETDEWEB)

    Hekkert, M.P. [Department of Innovation Studies, Copernicus Institute, Utrecht University, Utrecht (Netherlands)

    2002-04-01

    Current policy for the reduction of greenhouse gases is mainly concerned with a number of types of solutions: energy saving, shifting to the use of low-carbon fuels and the implementation of sustainable energy technologies. Recent research has shown that a strategy directed at a more efficient use of materials could make a considerable contribution to reducing CO2 emissions. Moreover, the costs to society as a whole of such a measure appear to be very low.

  12. Asymmetry Reduction Theory of FDI

    DEFF Research Database (Denmark)

    Li, Xin

    In this paper, I first briefly introduce Moon & Roehl’s (1993, 2001) imbalance theory of FDI, then I identify its three deficiencies that may be responsible for the relative lack of impact of the potentially powerful imbalance logic, and then I propose an asymmetry reduction theory (ARC) of FDI...... and explain its aspiration-resource-control (ARC) framework. I conclude the paper with a brief discussion of the OLI framework being a special case of the ARC framework....

  13. Dimensional reduction in anomaly mediation

    International Nuclear Information System (INIS)

    Boyda, Ed; Murayama, Hitoshi; Pierce, Aaron

    2002-01-01

    We offer a guide to dimensional reduction in theories with anomaly-mediated supersymmetry breaking. Evanescent operators proportional to ε arise in the bare Lagrangian when it is reduced from d=4 to d=4-2ε dimensions. In the course of a detailed diagrammatic calculation, we show that inclusion of these operators is crucial. The evanescent operators conspire to drive the supersymmetry-breaking parameters along anomaly-mediation trajectories across heavy particle thresholds, guaranteeing the ultraviolet insensitivity

  14. Reduction of mesqa improvement costs

    Directory of Open Access Journals (Sweden)

    Mohamed Ahmed Saad ElFetyany

    2017-10-01

    Results show that using the revised approach brings down the cost of mesqa improvement from nearly 10,000LE/fed at present to about 6000LE/fed. These reductions based on the analyses of different mesqa modelling through the adoption of certain parameters such as feasibility of the revised design, effective application of continuous flow for water distribution, and downsizing of the capacity of improved mesqas.

  15. Exposure reduction in panoramic radiography

    International Nuclear Information System (INIS)

    Kapa, S.F.; Platin, E.

    1990-01-01

    Increased receptor speed in panoramic radiography is useful in reducing patient exposure if it doesn't substantially decrease the diagnostic quality of the resultant image. In a laboratory investigation four rare earth screen/film combinations were evaluated ranging in relative speed from 400 to 1200. The results indicated that an exposure reduction of approximately 15 percent can be achieved by substituting a 1200 speed system for a 400 speed system without significantly affecting the diagnostic quality of the image

  16. Americium recovery from reduction residues

    Science.gov (United States)

    Conner, W.V.; Proctor, S.G.

    1973-12-25

    A process for separation and recovery of americium values from container or bomb'' reduction residues comprising dissolving the residues in a suitable acid, adjusting the hydrogen ion concentration to a desired level by adding a base, precipitating the americium as americium oxalate by adding oxalic acid, digesting the solution, separating the precipitate, and thereafter calcining the americium oxalate precipitate to form americium oxide. (Official Gazette)

  17. Lung volume reduction for emphysema.

    Science.gov (United States)

    Shah, Pallav L; Herth, Felix J; van Geffen, Wouter H; Deslee, Gaetan; Slebos, Dirk-Jan

    2017-02-01

    Advanced emphysema is a lung disease in which alveolar capillary units are destroyed and supporting tissue is lost. The combined effect of reduced gas exchange and changes in airway dynamics impairs expiratory airflow and leads to progressive air trapping. Pharmacological therapies have limited effects. Surgical resection of the most destroyed sections of the lung can improve pulmonary function and exercise capacity but its benefit is tempered by significant morbidity. This issue stimulated a search for novel approaches to lung volume reduction. Alternative minimally invasive approaches using bronchoscopic techniques including valves, coils, vapour thermal ablation, and sclerosant agents have been at the forefront of these developments. Insertion of endobronchial valves in selected patients could have benefits that are comparable with lung volume reduction surgery. Endobronchial coils might have a role in the treatment of patients with emphysema with severe hyperinflation and less parenchymal destruction. Use of vapour thermal energy or a sclerosant might allow focal treatment but the unpredictability of the inflammatory response limits their current use. In this Review, we aim to summarise clinical trial evidence on lung volume reduction and provide guidance on patient selection for available therapies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Applications of the reduction method

    International Nuclear Information System (INIS)

    Zimmermann, W.

    1987-01-01

    A renoramalizable model of quantum field theory involving several independent coupling parameters, λ 0 , ..., λ n and a normalization mass K is considered. If the model involves massive particles a formulation of the renormalization group should be used in which the β-functions are independent of the masses. The aim of the reduction method is to reduce the model to a description in terms of a single coupling parameter. Although the reduction method does not work for the gauge couplings it leads to reasonable mass constraints if applied to the Yukawa and the Higgs couplings. The underlying idea is that - whatever the fundamental interaction if going to be - eventually there is only one coupling which determines all parameters of the standard model. However, one should be skeptical about numerical results in the standard model. For the standard model is only an effective theory, its β-functions are only approximate and change on their lowest order coefficients may have large effects on the reduction solutions

  19. Results Evaluation in Reduction Rhinoplasty

    Directory of Open Access Journals (Sweden)

    Arima, Lisandra Megumi

    2011-01-01

    Full Text Available Introduction: Final results evaluation after rhinoplasty is a not a topic widely studied from the patient's viewpoint. Objective:Evaluate the satisfaction of the patients submitted to reduction rhinoplasty, from the questionnaire Rhinoplasty Outcomes Evaluation (ROE. Method: Longitudinal study, retrospective cut type, of the preoperative and postoperative satisfaction. The sample was composed by 28 patients who were submitted to rhinoplasty and answered the ROE questionnaire. Three variables were obtained: satisfaction note that the patient had with his/her image before the surgery; note of satisfaction with the current appearance; the difference of the average satisfaction notes between postoperative and preoperative approaches. Results: The postoperative note was higher than the preoperative in all patients. We noticed a difference between the average of the postoperative and preoperative of 48.3 (p75 considered to be an excellent outcome (67.9%. Conclusions: The ROE questionnaire is a helpful tool to show the satisfaction of the patient submitted to reduction rhinoplasty. About 92% of the patients submitted to reduction rhinoplasty consider the postoperative result to be good or excellent.

  20. Photochemical reduction of uranyl nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Duerksen, W.K.

    1993-10-20

    The photochemical reduction of uranyl nitrate solutions to tetravalent uranium was investigated as a means of producing uranium dioxide feed for the saltless direct oxide reduction (SDOR) process. At high uranium concentrations, reoxidation of U{sup +4} occurs rapidly. The kinetics of the nitric oxidation of tetravalent uranium depend on the concentrations of hydrogen ion, nitrate ion, nitrous acid, and tetravalent uranium in the same manner as was reported elsewhere for the nitrate oxidation of PU{sup +3}. Reaction rate data were successfully correlated with a mechanism in which nitrogen dioxide is the reactive intermediate. Addition of a nitrous acid scavenger suppresses the reoxidation reaction. An immersion reactor employing a mercury vapor lamp gave reduction times fast enough for routine production usage. Precipitation techniques for conversion of aqueous U(NO{sub 3}){sub 4} to hydrous UO{sub 2} were evaluated. Prolonged dewatering times tended to make the process time consuming. Use of 3- to 4-M aqueous NaOH gave the best dewatering times observed. Reoxidation of the UO{sub 2} by water of hydration was encountered, which required the drying process to be carried out under a reducing atmosphere.

  1. A systematic way for the cost reduction of density fitting methods

    International Nuclear Information System (INIS)

    Kállay, Mihály

    2014-01-01

    We present a simple approach for the reduction of the size of auxiliary basis sets used in methods exploiting the density fitting (resolution of identity) approximation for electron repulsion integrals. Starting out of the singular value decomposition of three-center two-electron integrals, new auxiliary functions are constructed as linear combinations of the original fitting functions. The new functions, which we term natural auxiliary functions (NAFs), are analogous to the natural orbitals widely used for the cost reduction of correlation methods. The use of the NAF basis enables the systematic truncation of the fitting basis, and thereby potentially the reduction of the computational expenses of the methods, though the scaling with the system size is not altered. The performance of the new approach has been tested for several quantum chemical methods. It is demonstrated that the most pronounced gain in computational efficiency can be expected for iterative models which scale quadratically with the size of the fitting basis set, such as the direct random phase approximation. The approach also has the promise of accelerating local correlation methods, for which the processing of three-center Coulomb integrals is a bottleneck

  2. Role of Reversible Histidine Coordination in Hydroxylamine Reduction by Plant Hemoglobins (Phytoglobins).

    Science.gov (United States)

    Athwal, Navjot Singh; Alagurajan, Jagannathan; Andreotti, Amy H; Hargrove, Mark S

    2016-10-18

    Reduction of hydroxylamine to ammonium by phytoglobin, a plant hexacoordinate hemoglobin, is much faster than that of other hexacoordinate hemoglobins or pentacoordinate hemoglobins such as myoglobin, leghemoglobin, and red blood cell hemoglobin. The reason for differences in reactivity is not known but could be intermolecular electron transfer between protein molecules in support of the required two-electron reduction, hydroxylamine binding, or active site architecture favoring the reaction. Experiments were conducted with phytoglobins from rice, tomato, and soybean along with human neuroglobin and soybean leghemoglobin that reveal hydroxylamine binding as the rate-limiting step. For hexacoordinate hemoglobins, binding is limited by the dissociation rate constant for the distal histidine, while leghemoglobin is limited by an intrinsically low affinity for hydroxylamine. When the distal histidine is removed from rice phytoglobin, a hydroxylamine-bound intermediate is formed and the reaction rate is diminished, indicating that the distal histidine imidazole side chain is critical for the reaction, albeit not for electron transfer but rather for direct interaction with the substrate. Together, these results demonstrate that phytoglobins are superior at hydroxylamine reduction because they have distal histidine coordination affinity constants near 1, and facile rate constants for binding and dissociation of the histidine side chain. Hexacoordinate hemoglobins such as neuroglobin are limited by tighter histidine coordination that blocks hydroxylamine binding, and pentacoordinate hemoglobins have intrinsically lower hydroxylamine affinities.

  3. Silver modified platinum surface/H{sup +} conducting Nafion membrane for cathodic reduction of nitrate ions

    Energy Technology Data Exchange (ETDEWEB)

    Hasnat, M.A., E-mail: mahtazim@yahoo.com [Department of Chemistry, Graduate School of Physical Sciences, Shahajalal University of Science and Technology, Sylhet 3114 (Bangladesh); School of Chemical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang (Malaysia); Ahamad, N.; Nizam Uddin, S.M. [Department of Chemistry, Graduate School of Physical Sciences, Shahajalal University of Science and Technology, Sylhet 3114 (Bangladesh); Mohamed, Norita [School of Chemical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang (Malaysia)

    2012-01-15

    Electrocatalytic reduction of NO{sub 3}{sup -} was performed at an Ag modified Pt electrodes supported on a H{sup +} conducting Nafion-117 polymer electrolyte. The cyclic voltammetric and electrolysis experiments showed that the reduction process was a two-electron transfer reaction. The conversion of nitrate to nitrite follows first order kinetics. Controlled potential electrolysis experiments revealed that the highest reduction rate (k{sub 1}; 95.1 Multiplication-Sign 10{sup -3} min{sup -1}) could be obtained at -1.3 V versus Ag/AgCl (std. KCl) reference electrode. Meanwhile, substantial nitrate removal (ca. 89%) could be attained by a flow system when the flow rate is as low as 0.1 ml min{sup -1}. The Ag particles on the Pt film were a in polycrystalline state having roughness value of 0.45 {mu}m, which was reduced to 0.30 {mu}m after 270 min of undergoing electrolysis.

  4. Dihydropyridine-fused and pyridine-fused coumarins: Reduction on a glassy carbon electrode in dimethylformamide

    International Nuclear Information System (INIS)

    Nuñez-Vergara, Luis J.; Pardo-Jiménez, V.; Barrientos, C.; Olea-Azar, C.A.; Navarrete-Encina, P.A.; Squella, J.A.

    2012-01-01

    In this study, two series of dihydropyridine-fused and pyridine-fused coumarins were synthesised and electrochemically characterised in aprotic medium. In both series, the most easily reducible groups were the endocyclic carbonyl groups. The electrochemical mechanism for both types of compounds is strongly dependent on the experimental time-scale. Cyclic voltammetric (CV) reduction on a glassy carbon electrode (GCE) of the endocyclic carbonyl group of dihydropyridine-fused coumarins involves an ECEC mechanism with two electron transfer steps that are coupled with chemical reactions to produce the corresponding hemiacetal derivative. In the case of pyridine-fused coumarins, CV reduction of the endocyclic carbonyl group involves an EEC mechanism. ESR studies revealed the presence of a stabilised intermediate only for the pyridine-fused derivatives. Our theoretical study showed a spin density map of radical species delocalised mainly within the coumarin ring, indicating the reduction of the endocyclic carbonyl group. In the case of the dihydropyridine-fused derivatives, the mildly acid hydrogen of the dihydropyridine ring destabilises the radical via a father–son type reaction.

  5. Reduction reactions of water soluble cyano-cobalt(III)-porphyrins: Metal versus ligand centered processes

    International Nuclear Information System (INIS)

    Mosseri, S.; Neta, P.; Harriman, A.; Hambright, P.

    1990-01-01

    Reduction reactions of dicyano-cobalt(III)-porphyrins [potential in vivo cyanide scavenger drugs] were studied by radiolytic and electrochemical methods using the water soluble tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP). For [(CN)2CoIIITPPS]-, reduction occurs stepwise to the CoII, CoI, and finally to the phlorin anion. This behavior is similar to that of the cobalt porphyrins in the absence of cyanide, except that the cyanide ligand shifts the reduction potentials to much more negative values. On the other hand, under radiolytic conditions, [(CN)2CoIIITMPyP]- is reduced on the porphyrin macrocycle by one electron to give the CoIII pi-radical anion, which disproportionates into the initial complex and the two-electron ring reduced CoIII phlorin. The radical anion is also formed by intramolecular electron transfer subsequent to the reaction of CoIITMPyP and cyanide. The results are compared with the chemistry of Vitamin B-12

  6. Electrocatalytic reduction of oxygen at glassy carbon electrode modified by polypyrrole/anthraquinones composite film in various pH media

    International Nuclear Information System (INIS)

    Valarselvan, S.; Manisankar, P.

    2011-01-01

    Graphical abstract: The electrocatalytic reduction of dioxygen by one mono and four dihydroxy derivatives of 9,10-anthraquinone (AQ) incorporated in polypyrrole (PPy) matrix on glassy carbon electrode has been investigated. AQ and PPy composite film showed excellent electrocatalytic performance for the reduction of O 2 to H 2 O 2 . Highlights: → Hydroxyl derivatives of anthraquinones as electrocatalysts for dioxygen reduction. → AQ/PPy composite film on GC electrode exhibits potent electrocatalytic activity. → Substituent groups influence electrocatalytic dioxygen reduction. → Surface coverage varies the rate of electrocatalytic dioxygen reduction. - Abstract: The electrocatalytic reduction of dioxygen by one mono and four dihydroxy derivatives of 9,10-anthraquinone (AQ) incorporated in polypyrrole (PPy) matrix on glassy carbon electrode has been investigated. The electrochemical behaviour of the modified electrodes was examined in various pH media and both the formal potential of anthraquinones and reduction potential of dioxygen exhibited pH dependence. AQ and PPy composite film showed excellent electrocatalytic performance for the reduction of O 2 to H 2 O 2 . pH 6.0 was chosen as the most suitable medium to study the electrocatalysis by comparing the peak potential of oxygen reduction and enhancement in peak current for oxygen reduction. The diffusion coefficient values of AQ at the modified electrodes and the number of electrons involved in AQ reduction were evaluated by chronoamperometric and chronocoulometric techniques, respectively. In addition, hydrodynamic voltammetric studies showed the involvement of two electrons in O 2 reduction. The mass specific activity of AQ used, the diffusion coefficient of oxygen and the heterogeneous rate constants for the oxygen reduction at the surface of modified electrodes were also determined by rotating disk voltammetry.

  7. Two-electron capture into autoionising configurations N/sup 4 +/(1snln'l') with n = 2,3,4 and n' >= n, observed by electron spectrometry in collisions of N/sup 6 +/(1s) with He and H/sub 2/, at 4. 2 keV amu/sup -1/

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.; Dousson, S.; Hitz, D.

    1984-04-14

    Double electron transfer into autoionising states N/sup 4 +/(1snln'l'), with n = 2,3,4 and n' >= n has been observed in a collision between a one-electron highly charged N/sup 6 +/(1s) ion and a two-electron target (He or H/sub 2/), by electron spectrometry. The same configurations are excited in the two collisional systems but with very different probabilities. Electron capture mainly occurs into 1s2ln'l' in He-systems whereas transfer into 1s3ln'l' is stronger in H/sub 2/ systems.

  8. Strain expansion-reduction approach

    Science.gov (United States)

    Baqersad, Javad; Bharadwaj, Kedar

    2018-02-01

    Validating numerical models are one of the main aspects of engineering design. However, correlating million degrees of freedom of numerical models to the few degrees of freedom of test models is challenging. Reduction/expansion approaches have been traditionally used to match these degrees of freedom. However, the conventional reduction/expansion approaches are only limited to displacement, velocity or acceleration data. While in many cases only strain data are accessible (e.g. when a structure is monitored using strain-gages), the conventional approaches are not capable of expanding strain data. To bridge this gap, the current paper outlines a reduction/expansion technique to reduce/expand strain data. In the proposed approach, strain mode shapes of a structure are extracted using the finite element method or the digital image correlation technique. The strain mode shapes are used to generate a transformation matrix that can expand the limited set of measurement data. The proposed approach can be used to correlate experimental and analytical strain data. Furthermore, the proposed technique can be used to expand real-time operating data for structural health monitoring (SHM). In order to verify the accuracy of the approach, the proposed technique was used to expand the limited set of real-time operating data in a numerical model of a cantilever beam subjected to various types of excitations. The proposed technique was also applied to expand real-time operating data measured using a few strain gages mounted to an aluminum beam. It was shown that the proposed approach can effectively expand the strain data at limited locations to accurately predict the strain at locations where no sensors were placed.

  9. Manganese catalysts with bulky bipyridine ligands for the electrocatalytic reduction of carbon dioxide: eliminating dimerization and altering catalysis.

    Science.gov (United States)

    Sampson, Matthew D; Nguyen, An D; Grice, Kyle A; Moore, Curtis E; Rheingold, Arnold L; Kubiak, Clifford P

    2014-04-09

    With the goal of improving previously reported Mn bipyridine electrocatalysts in terms of increased activity and reduced overpotential, a bulky bipyridine ligand, 6,6'-dimesityl-2,2'-bipyridine (mesbpy), was utilized to eliminate dimerization in the catalytic cycle. Synthesis, electrocatalytic properties, X-ray diffraction (XRD) studies, and infrared spectroelectrochemistry (IR-SEC) of Mn(mesbpy)(CO)3Br and [Mn(mesbpy)(CO)3(MeCN)](OTf) are reported. Unlike previously reported Mn bipyridine catalysts, these Mn complexes exhibit a single, two-electron reduction wave under nitrogen, with no evidence of dimerization. The anionic complex, [Mn(mesbpy)(CO)3](-), is formed at 300 mV more positive potential than the corresponding state is formed in typical Mn bipyridine catalysts. IR-SEC experiments and chemical reductions with KC8 provide insights into the species leading up to the anionic state, specifically that both the singly reduced and doubly reduced Mn complexes form at the same potential. When formed, the anionic complex binds CO2 with H(+), but catalytic activity does not occur until a ~400 mV more negative potential is present. The Mn complexes show high activity and Faradaic efficiency for CO2 reduction to CO with the addition of weak Brønsted acids. IR-SEC experiments under CO2/H(+) indicate that reduction of a Mn(I)-CO2H catalytic intermediate may be the cause of this unusual "over-reduction" required to initiate catalysis.

  10. Electrocatalysis of oxygen reduction on nitrogen-containing multi-walled carbon nanotube modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    Vikkisk, Merilin; Kruusenberg, Ivar; Joost, Urmas; Shulga, Eugene; Tammeveski, Kaido

    2013-01-01

    Highlights: ► Pyrolysis in the presence of urea was used for nitrogen doping of carbon nanotubes. ► N-doped carbon nanotubes were used as catalysts for the oxygen reduction reaction. ► N-doped carbon material showed a high catalytic activity for ORR in alkaline media. ► N-containing CNT material is an attractive cathode catalyst for alkaline membrane fuel cells. - Abstract: The electrochemical reduction of oxygen was studied on nitrogen-doped multi-walled carbon nanotube (NCNT) modified glassy carbon (GC) electrodes employing the rotating disk electrode (RDE) method. Nitrogen doping was achieved by simple pyrolysis of the carbon nanotube material in the presence of urea. The surface morphology and composition of the NCNT samples were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed a rather uniform distribution of NCNTs on the GC electrode substrate. The XPS analysis showed a successful doping of carbon nanotubes with nitrogen species. The RDE results revealed that in alkaline solution the N-doped nanotube materials showed a remarkable electrocatalytic activity towards oxygen reduction. At low overpotentials the reduction of oxygen followed a two-electron pathway on undoped carbon nanotube modified GC electrodes, whereas on NCNT/GC electrodes a four-electron pathway of O 2 reduction predominated. The results obtained are significant for the development of nitrogen-doped carbon-based cathodes for alkaline membrane fuel cells.

  11. Memory Reduction via Delayed Simulation

    Directory of Open Access Journals (Sweden)

    Michael Holtmann

    2011-02-01

    Full Text Available We address a central (and classical issue in the theory of infinite games: the reduction of the memory size that is needed to implement winning strategies in regular infinite games (i.e., controllers that ensure correct behavior against actions of the environment, when the specification is a regular omega-language. We propose an approach which attacks this problem before the construction of a strategy, by first reducing the game graph that is obtained from the specification. For the cases of specifications represented by "request-response"-requirements and general "fairness" conditions, we show that an exponential gain in the size of memory is possible.

  12. Model reduction for circuit simulation

    CERN Document Server

    Hinze, Michael; Maten, E Jan W Ter

    2011-01-01

    Simulation based on mathematical models plays a major role in computer aided design of integrated circuits (ICs). Decreasing structure sizes, increasing packing densities and driving frequencies require the use of refined mathematical models, and to take into account secondary, parasitic effects. This leads to very high dimensional problems which nowadays require simulation times too large for the short time-to-market demands in industry. Modern Model Order Reduction (MOR) techniques present a way out of this dilemma in providing surrogate models which keep the main characteristics of the devi

  13. Mechanisms and Reduction in Psychiatry

    DEFF Research Database (Denmark)

    Andersen, Lise Marie

    2017-01-01

    example of this kind of reorientation can be seen in the recent introduction of the Research Domain Criteria project (RDoC) by the U.S National Institute of Mental Health. The RDoC project is an attempt to introduce a new classification system based on brain circuits. The central idea behind the project...... factors to be found at the biological level. However, it is precisely such multilevel models that are necessary for progress in this fundamentally interdisciplinary science. This paper analyses the reductive nature of the RDoC project and investigates the potential for an interventionist account...

  14. Climate Change and Poverty Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Simon

    2011-08-15

    Climate change will make it increasingly difficult to achieve and sustain development goals. This is largely because climate effects on poverty remain poorly understood, and poverty reduction strategies do not adequately support climate resilience. Ensuring effective development in the face of climate change requires action on six fronts: investing in a stronger climate and poverty evidence base; applying the learning about development effectiveness to how we address adaptation needs; supporting nationally derived, integrated policies and programmes; including the climate-vulnerable poor in developing strategies; and identifying how mitigation strategies can also reduce poverty and enable adaptation.

  15. Cohomological reduction of sigma models

    Energy Technology Data Exchange (ETDEWEB)

    Candu, Constantin; Mitev, Vladimir; Schomerus, Volker [DESY, Hamburg (Germany). Theory Group; Creutzig, Thomas [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy

    2010-01-15

    This article studies some features of quantum field theories with internal supersymmetry, focusing mainly on 2-dimensional non-linear sigma models which take values in a coset superspace. It is discussed how BRST operators from the target space super- symmetry algebra can be used to identify subsectors which are often simpler than the original model and may allow for an explicit computation of correlation functions. After an extensive discussion of the general reduction scheme, we present a number of interesting examples, including symmetric superspaces G/G{sup Z{sub 2}} and coset superspaces of the form G/G{sup Z{sub 4}}. (orig.)

  16. Preparation of graphene/nile blue nanocomposite: Application for oxygen reduction reaction and biosensing

    International Nuclear Information System (INIS)

    Shervedani, Reza Karimi; Amini, Akbar

    2015-01-01

    Highlights: •New nanocomposite is synthesized by electrochemical polymerization of Nile blue and reduction of GO on GCE. •The nanocomposite is characterized by SEM, UV–vis and electrochemical methods. •High electrocatalytic activity was observed for O 2 reduction on GNs-NB nanocomposite. •GCE-GNs-NB poly was tested successfully for immobilization of GOx and detection of glucose. -- Abstract: Nile blue/graphene (NB-GNs) nanocomposite was synthesized for the first time via a green and effective one-step electrochemical method, allowing to reduce graphene oxide (GO) and NB on the glassy carbon electrode (GCE) simultaneously and construct GCE-GNs-NB poly composite. The composite was characterized by scanning electron microscopy (SEM), UV–Vis spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical results obtained in the absence of any redox probe, where NB was active, allowed to trace step-by-step addition of the NB-GNs nanocomposite onto the GCE electrode surface, supporting formation of the GCE-GNs-NB poly composite. The electrocatalytic activity of the as-prepared GCE-GNs-NB poly towards O 2 reduction was studied in neutral medium. The results revealed excellent electrocatalytic performance for two-electron reduction of oxygen, suggesting its potential application as metal-free electrocatalysts for O 2 reduction reaction. Application of the GCE-GNs-NB poly in electrochemical biosensing was demonstrated by immobilization of glucose oxidase (GOx) on the surface of GCE-GNs-NB poly , and then, using it for sensing of glucose. The biosensor exhibited a linear response, from 0.2 to 2.0 mM glucose, with a low detection limit, 2.1 μM, and high sensitivity, 67.0 μA mM −1 cm −2 , obtained by cyclic voltammetry method. The proposed biosensor was successfully tested for determination of glucose in blood serum samples

  17. Decision making regarding multifetal reduction.

    Science.gov (United States)

    Maifeld, Michelle; Hahn, Sandra; Titler, Marita G; Mullen, Meredithe

    2003-01-01

    To identify salient variables that influence decision making regarding multifetal reduction (MFR) and describe their effect on individuals over time. Prospective, exploratory, descriptive design, using qualitative and quantitative methods. Midwestern tertiary care center. A convenience sample of 11 consecutive consenting couples with triplet or higher-order pregnancies who elected to undergo MFR. Semistructured audiotaped telephone interviews at three points: (a) 2 weeks postreduction, (b) 6 weeks postpartum, and (c) 6 months postpartum; a demographic and marital adjustment questionnaire. Themes identified by content analysis and compared via matrix analysis between males and females and at three points in time; trends in marital adjustment. Dominant variables influencing MFR decision making were risks associated with higher-order pregnancies and preservation of infants' and mothers' health. Most participants identified emotional issues, including moral and ethical dilemmas, as the most difficult aspect of reduction. Over time, participants reported feeling more positive about their decision; nonetheless, negative feelings emerged progressively. Risk aversion favored MFR decision making. Yet, both making and living with the decision were emotionally difficult for this sample. Interventions are needed to assist couples with this decision and its consequences.

  18. Chemical model reduction under uncertainty

    KAUST Repository

    Malpica Galassi, Riccardo

    2017-03-06

    A general strategy for analysis and reduction of uncertain chemical kinetic models is presented, and its utility is illustrated in the context of ignition of hydrocarbon fuel–air mixtures. The strategy is based on a deterministic analysis and reduction method which employs computational singular perturbation analysis to generate simplified kinetic mechanisms, starting from a detailed reference mechanism. We model uncertain quantities in the reference mechanism, namely the Arrhenius rate parameters, as random variables with prescribed uncertainty factors. We propagate this uncertainty to obtain the probability of inclusion of each reaction in the simplified mechanism. We propose probabilistic error measures to compare predictions from the uncertain reference and simplified models, based on the comparison of the uncertain dynamics of the state variables, where the mixture entropy is chosen as progress variable. We employ the construction for the simplification of an uncertain mechanism in an n-butane–air mixture homogeneous ignition case, where a 176-species, 1111-reactions detailed kinetic model for the oxidation of n-butane is used with uncertainty factors assigned to each Arrhenius rate pre-exponential coefficient. This illustration is employed to highlight the utility of the construction, and the performance of a family of simplified models produced depending on chosen thresholds on importance and marginal probabilities of the reactions.

  19. Mesotherapy for local fat reduction.

    Science.gov (United States)

    Jayasinghe, S; Guillot, T; Bissoon, L; Greenway, F

    2013-10-01

    Mesotherapy, which is the injection of substances locally into mesodermally derived subcutaneous tissue, developed from empirical observations of a French physician in the 1950s. Although popular in Europe for many medical purposes, it is used for local cosmetic fat reduction in the United States. This paper reviews manuscripts indexed in PubMed/MEDLINE under 'mesotherapy', which pertains to local fat reduction. The history of lipolytic mesotherapy, the physiology of body fat distribution, the mechanism of action of different lipolytic stimulators and their increased efficacy in combination are reviewed. Mesotherapy falls into two categories. Lipolytic mesotherapy using lipolytic stimulators requires more frequent treatments as the fat cells are not destroyed and can refill over time. Ablative mesotherapy destroys fat cells with a detergent, causes inflammation and scarring from the fat necrosis, but requires fewer treatments. The historic and empiric mixing of sodium channel blocking local anaesthetics in mesotherapy solutions inhibits the intended lipolysis. Major mesotherapy safety concerns include injection site infections from poor sterile technique. Cosmetic mesotherapy directs the area from which fat is lost to improve self-image. Studies were of relatively small number, many with limited sample sizes. Future research should be directed towards achieving a Food and Drug Administration indication rather than continuing expansion of off-label use. © 2013 The Authors. obesity reviews © 2013 International Association for the Study of Obesity.

  20. Quantum noise and stochastic reduction

    International Nuclear Information System (INIS)

    Brody, Dorje C; Hughston, Lane P

    2006-01-01

    In standard nonrelativistic quantum mechanics the expectation of the energy is a conserved quantity. It is possible to extend the dynamical law associated with the evolution of a quantum state consistently to include a nonlinear stochastic component, while respecting the conservation law. According to the dynamics thus obtained, referred to as the energy-based stochastic Schroedinger equation, an arbitrary initial state collapses spontaneously to one of the energy eigenstates, thus describing the phenomenon of quantum state reduction. In this paper, two such models are investigated: one that achieves state reduction in infinite time and the other in finite time. The properties of the associated energy expectation process and the energy variance process are worked out in detail. By use of a novel application of a nonlinear filtering method, closed-form solutions-algebraic in character and involving no integration-are obtained of both these models. In each case, the solution is expressed in terms of a random variable representing the terminal energy of the system and an independent noise process. With these solutions at hand it is possible to simulate explicitly the dynamics of the quantum states of complicated physical systems

  1. Reduction of robot base parameters

    Energy Technology Data Exchange (ETDEWEB)

    Vandanjon, P O [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes et Systemes Avances; Gautier, M [Nantes Univ., 44 (France)

    1996-12-31

    This paper is a new step in the search of minimum dynamic parameters of robots. In spite of planing exciting trajectories and using base parameters, some parameters remain not identifiable due to the perturbation effects. In this paper, we propose methods to reduce the set of base parameters in order to get an essential set of parameters. This new set defines a simplified identification model witch improves the noise immunity of the estimation process. It contributes also in reducing the computation burden of a simplified dynamic model. Different methods are proposed and are classified in two parts: methods, witch perform reduction and identification together, come from statistical field and methods, witch reduces the model before the identification thanks to a priori information, come from numerical field like the QR factorization. Statistical tools and QR reduction are shown to be efficient and adapted to determine the essential parameters. They can be applied to open-loop, or graph structured rigid robot, as well as flexible-link robot. Application for the PUMA 560 robot is given. (authors). 9 refs., 4 tabs.

  2. Concrete waste reduction of 50%

    International Nuclear Information System (INIS)

    Vos, R.M. de; Van der Wagt, K.M.; Van der Kruk, E.; Meeussen, H.W.

    2016-01-01

    During decommissioning quite a volume of concrete waste is produced. The degree of activation of the waste can range from clearly activated material to slightly activated or contaminated concrete. The degree of activation influences the applicable waste management processes that can be applied. The subsequent waste management processes can be identified for concrete waste are; disposal, segregation, re-use, conditional release and release. With each of these steps, the footprint of radioactive decommissioning waste is reduced. Future developments for concrete waste reduction can be achieved by applying smart materials in new build facilities (i.e. fast decaying materials). NRG (Nuclear Research and consultancy Group) has investigated distinctive waste management processes to reduce the foot-print of concrete waste streams resulting from decommissioning. We have investigated which processes can be applied in the Netherlands, both under current legislation and with small changes in legislation. We have also investigated the separation process in more detail. Pilot tests with a newly patented process have been started in 2015. We expect that our separation methods will reduce the footprint reduction of concrete waste by approximately 50% due to release or re-use in the nuclear sector or in the conventional industry. (authors)

  3. Reduction of robot base parameters

    International Nuclear Information System (INIS)

    Vandanjon, P.O.

    1995-01-01

    This paper is a new step in the search of minimum dynamic parameters of robots. In spite of planing exciting trajectories and using base parameters, some parameters remain not identifiable due to the perturbation effects. In this paper, we propose methods to reduce the set of base parameters in order to get an essential set of parameters. This new set defines a simplified identification model witch improves the noise immunity of the estimation process. It contributes also in reducing the computation burden of a simplified dynamic model. Different methods are proposed and are classified in two parts: methods, witch perform reduction and identification together, come from statistical field and methods, witch reduces the model before the identification thanks to a priori information, come from numerical field like the QR factorization. Statistical tools and QR reduction are shown to be efficient and adapted to determine the essential parameters. They can be applied to open-loop, or graph structured rigid robot, as well as flexible-link robot. Application for the PUMA 560 robot is given. (authors). 9 refs., 4 tabs

  4. LDRD report nonlinear model reduction

    Energy Technology Data Exchange (ETDEWEB)

    Segalman, D.; Heinstein, M.

    1997-09-01

    The very general problem of model reduction of nonlinear systems was made tractable by focusing on the very large subclass consisting of linear subsystems connected by nonlinear interfaces. Such problems constitute a large part of the nonlinear structural problems encountered in addressing the Sandia missions. A synthesis approach to this class of problems was developed consisting of: detailed modeling of the interface mechanics; collapsing the interface simulation results into simple nonlinear interface models; constructing system models by assembling model approximations of the linear subsystems and the nonlinear interface models. These system models, though nonlinear, would have very few degrees of freedom. A paradigm problem, that of machine tool vibration, was selected for application of the reduction approach outlined above. Research results achieved along the way as well as the overall modeling of a specific machine tool have been very encouraging. In order to confirm the interface models resulting from simulation, it was necessary to develop techniques to deduce interface mechanics from experimental data collected from the overall nonlinear structure. A program to develop such techniques was also pursued with good success.

  5. From Outermost Reduction Semantics to Abstract Machine

    DEFF Research Database (Denmark)

    Danvy, Olivier; Johannsen, Jacob

    to transform a reduction-based normalization function into a reduction-free one where the reduction sequence is not enumerated. This reduction-free normalization function takes the form of an abstract machine that navigates from one redex site to the next without systematically detouring via the root...... of a redex. In this article, we consider such an outermost reduction semantics with backward-overlapping rules, and we investigate how to apply refocusing to still obtain a reduction-free normalization function in the form of an abstract machine....

  6. Carbothermic reduction of refractory metals

    International Nuclear Information System (INIS)

    Anderson, R.N.; Parlee, N.A.D.

    1976-01-01

    The reduction of stable refractory metal oxides by carbon is generally unacceptable since the product is usually contaminated with carbides. The carbide formation may be avoided by selecting a solvent metal to dissolve the reactive metal as it is produced and reduce its chemical activity below that required for carbide formation. This approach has been successfully applied to the oxides of Si, Zr, Ti, Al, Mg, and U. In the case where a volatile suboxide, a carbonyl reaction, or a volatile metal occur, the use of the solvent metal appears satisfactory to limit the loss of material at low pressures. In several solute--solvent systems, vacuum evaporation is used to strip the solvent metal from the alloy to give the pure metal

  7. Global threat reduction initiative (GTRI)

    International Nuclear Information System (INIS)

    Chamberlain, Travis

    2009-01-01

    The Global Threat Reduction Initiative (GTRI) is a vital part of the global efforts to combat nuclear terrorism. GTRI's unique mission to reduce and protect vulnerable nuclear and radiological material located at civilian sites both in the United States and abroad directly addresses recommendations of the bipartisan 9/11 Commission. GTRI efforts are focused on the first line of defense, namely securing or removing vulnerable nuclear and radiological material at the source. The international community has promulgated guidance on the best practice on the technical and administrative aspects of radiological source security, and the GTRI seeks to provide technical assistance to national bodies and individual facilities to adopt this best practice. This presentation will discuss security concepts that are implemented by the GTRI in cooperation with the Australian Nuclear Science and Technology Organization's Regional Security of Radioactive Sources Project. (author)

  8. Microplastics pollution and reduction strategies

    Institute of Scientific and Technical Information of China (English)

    Wei-Min Wu; Jun Yang; Craig S.Criddle

    2017-01-01

    Microplastic particles smaller than 5 mm in size are of increasing concern,especially in aquatic environments,such as the ocean.Primary source is microbeads (< 1 mm) used in cosmetics and cleaning agents and fiber fragments from washing of clothes,and secondary source such as broken down plastic litter and debris.These particles are mostly made from polyethylene (PE),polypropylene (PP),polystyrene (PS),polyethylene terephthalate (PET) and polyesters.They are ingested by diverse marine fauna,including zooplanktons,mussel,oyster,shrimp,fish etc.and can enter human food chains via several pathways.Strategy for control of microplastics pollution should primarily focus on source reduction and subsequently on the development of cost-effective clean up and remediation technologies.Recent research results on biodegradation of plastics have revealed a potential for microbial biodegradation and bioremediation of plastic pollutants,such as PE,PS and PET under appropriate conditions.

  9. Dimensional reduction in quantum gravity

    Energy Technology Data Exchange (ETDEWEB)

    Hooft, G [Rijksuniversiteit Utrecht (Netherlands). Inst. voor Theoretische Fysica

    1994-12-31

    The requirement that physical phenomena associated with gravitational collapse should be duly reconciled with the postulates of quantum mechanics implies that at a Planckian scale our world is not 3+1 dimensional. Rather, the observable degrees of freedom can best be described as if they were Boolean variables defined on a two- dimensional lattice, evolving with time. This observation, deduced from not much more than unitarity, entropy and counting arguments, implies severe restrictions on possible models of quantum gravity. Using cellular automata as an example it is argued that this dimensional reduction implies more constraints than the freedom we have in constructing models. This is the main reason why so-far no completely consistent mathematical models of quantum black holes have been found. (author). 13 refs, 2 figs.

  10. Omitted variable bias in crash reduction factors.

    Science.gov (United States)

    2015-09-01

    Transportation planners and traffic engineers are increasingly turning to crash reduction factors to evaluate changes in road : geometric and design features in order to reduce crashes. Crash reduction factors are typically estimated based on segment...

  11. Relativistic model for statevector reduction

    International Nuclear Information System (INIS)

    Pearle, P.

    1991-04-01

    A relativistic quantum field model describing statevector reduction for fermion states is presented. The time evolution of the states is governed by a Schroedinger equation with a Hamiltonian that has a Hermitian and a non-Hermitian part. In addition to the fermions, the Hermitian part describes positive and negative energy mesons of equal mass, analogous to the longitudinal and timelike photons of electromagnetism. The meson-field-sum is coupled to the fermion field. This ''dresses'' each fermion so that, in the extreme nonrelativistic limit (non-moving fermions), a fermion in a position eigenstate is also in an eigenstate of the meson-field-difference with the Yukawa-potential as eigenvalue. However, the fermions do not interact: this is a theory of free dressed fermions. It is possible to obtain a stationary normalized ''vacuum'' state which satisfies two conditions analogous to the gauge conditions of electromagnetism (i.e., that the meson-field-difference, as well as its time derivative, give zero when applied to the vacuum state), to any desired degree of accuracy. The non-Hermitian part of the Hamiltonian contains the coupling of the meson-field-difference to an externally imposed c-number fluctuating white noise field, of the CSL (Continuous Spontaneous Localization) form. This causes statevector reduction, as is shown in the extreme nonrelativistic limit. For example, a superposition of spatially separated wavepackets of a fermion will eventually be reduced to a single wavepacket: the meson-field-difference discriminates among the Yukawa-potential ''handles'' attached to each wavepacket, thereby selecting one wavepacket to survive by the CSL mechanism. Analysis beyond that given in this paper is required to see what happens when the fermions are allowed to move. (It is possible that the ''vacuum'' state becomes involved in the dynamics so that the ''gauge'' conditions can no longer be maintained.) It is shown how to incorporate these ideas into quantum

  12. Sulphate reduction experiment: SURE-1

    International Nuclear Information System (INIS)

    Pedersen, K.; Arlinger, J.; Bengtsson, A.; Edlund, J.; Eriksson, L.; Hallbeck, L.; Johansson, J.; Paeaejaervi, A.; Rabe, L.

    2013-11-01

    It was previously concluded that opposing gradients of sulphate and methane, observations of 16S rDNA sequences displaying great similarity to those of anaerobic methane-oxidizing Archaea, and a peak in sulphide concentration in groundwater from a depth of 250-350 m in Olkiluoto, Finland, indicated proper conditions for methane oxidation with sulphate. In the present research (SURE-1), pressure-resistant, gas-tight circulating systems were constructed to enable the investigation of attached and unattached anaerobic microbial populations from a depth of 327 m in Olkiluoto under in situ pressure (2.4 MPa), diversity, dissolved gas, and hydrochemical conditions of groundwater station ONKPVA6. Three parallel flow cell cabinets were configured to allow observation of the influence on microbial metabolic activity of 11 mM methane, 11 mM methane plus 10 mM H 2 , or 2.1 mM O 2 plus 7.9 mM N 2 (i.e., air). The concentrations of these gases and of organic acids and carbon, sulphur chemistry, pH and E h , ATP, numbers of cultivable microorganisms, and total numbers of cells and bacteriophages were subsequently recorded under batch conditions for 105 d. The system containing H 2 and methane displayed microbial reduction of 0.7 mM sulphate to sulphide, while the system containing only methane produced 0.2 mM reduced sulphate. The system containing added air became inhibited and displayed no signs of microbial activity. Added H 2 and methane induced increasing numbers of lysogenic bacteriophages per cell. It appears possible that a microbial anaerobic methane-oxidizing process coupled to acetate formation and sulphate reduction may be ongoing in aquifers at a depth of 250-350 m in Olkiluoto, but clear evidence of such an AOM process was not obtained. (orig.)

  13. Sulphate reduction experiment: SURE-1

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, K.; Arlinger, J.; Bengtsson, A.; Edlund, J.; Eriksson, L.; Hallbeck, L.; Johansson, J.; Paeaejaervi, A.; Rabe, L. [Microbial Analytics Sweden AB, Moelnlycke (Sweden)

    2013-11-15

    It was previously concluded that opposing gradients of sulphate and methane, observations of 16S rDNA sequences displaying great similarity to those of anaerobic methane-oxidizing Archaea, and a peak in sulphide concentration in groundwater from a depth of 250-350 m in Olkiluoto, Finland, indicated proper conditions for methane oxidation with sulphate. In the present research (SURE-1), pressure-resistant, gas-tight circulating systems were constructed to enable the investigation of attached and unattached anaerobic microbial populations from a depth of 327 m in Olkiluoto under in situ pressure (2.4 MPa), diversity, dissolved gas, and hydrochemical conditions of groundwater station ONKPVA6. Three parallel flow cell cabinets were configured to allow observation of the influence on microbial metabolic activity of 11 mM methane, 11 mM methane plus 10 mM H{sub 2}, or 2.1 mM O{sub 2} plus 7.9 mM N{sub 2} (i.e., air). The concentrations of these gases and of organic acids and carbon, sulphur chemistry, pH and E{sub h}, ATP, numbers of cultivable microorganisms, and total numbers of cells and bacteriophages were subsequently recorded under batch conditions for 105 d. The system containing H{sub 2} and methane displayed microbial reduction of 0.7 mM sulphate to sulphide, while the system containing only methane produced 0.2 mM reduced sulphate. The system containing added air became inhibited and displayed no signs of microbial activity. Added H{sub 2} and methane induced increasing numbers of lysogenic bacteriophages per cell. It appears possible that a microbial anaerobic methane-oxidizing process coupled to acetate formation and sulphate reduction may be ongoing in aquifers at a depth of 250-350 m in Olkiluoto, but clear evidence of such an AOM process was not obtained. (orig.)

  14. Measurements of Neutral Kaon Decays to Two Electron Positron Pairs

    Energy Technology Data Exchange (ETDEWEB)

    Halkiadakis, Eva [Rutgers U., Piscataway

    2001-01-01

    We observed 441 $K_L \\to e^+ e^- e^+ e^-$ events with a background of 4.2 events in the KTeV/E799II experiment at Fermilab. We present here a measurement of the $K_L \\to e^+ e^- e^+ e^-$ branching ratio (B), a study of CP symmetry and the first detailed study of the $e^+ e^-$ invariant mass spectrum in this decay mode....

  15. The First Two Electron Linear Accelerators in South Mrica

    African Journals Online (AJOL)

    gap oscillator and transmission lines to accelerate particles in a straight line. In 1928, Wideroe in Germany success- fully applied the resonance principle to accelerate potas- sium ions to 50 kV with an applied voltage of 25 kV. Technical advances resulting from the development of radar during World War II made possible ...

  16. A comparison and benchmark of two electron cloud packages

    Energy Technology Data Exchange (ETDEWEB)

    Lebrun, Paul L.G.; Amundson, James F; Spentzouris, Panagiotis G; Veitzer, Seth A

    2012-01-01

    We present results from precision simulations of the electron cloud (EC) problem in the Fermilab Main Injector using two distinct codes. These two codes are (i)POSINST, a F90 2D+ code, and (ii)VORPAL, a 2D/3D electrostatic and electromagnetic code used for self-consistent simulations of plasma and particle beam problems. A specific benchmark has been designed to demonstrate the strengths of both codes that are relevant to the EC problem in the Main Injector. As differences between results obtained from these two codes were bigger than the anticipated model uncertainties, a set of changes to the POSINST code were implemented. These changes are documented in this note. This new version of POSINST now gives EC densities that agree with those predicted by VORPAL, within {approx}20%, in the beam region. The root cause of remaining differences are most likely due to differences in the electrostatic Poisson solvers. From a software engineering perspective, these two codes are very different. We comment on the pros and cons of both approaches. The design(s) for a new EC package are briefly discussed.

  17. Two-electron photoionization cross sections at high energies

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Krivec, R.; Mandelzweig, V.B.

    2003-01-01

    Double and single electron photoionization cross sections and their ratios at high and ultra-relativistic energies are calculated for H - , He and helium-like ions in ground and excited states including triplet states. The ratios contain shake-off and quasi-free terms. A high precision non-variational wave function is used. The quasi-free mechanism increases the ratios impressively: for He we get 0.0762 instead of 0.0164 in the non-relativistic case. Ratios are inversely proportional to Z 2 , with a factor increasing from 0.094 in the nonrelativistic to 0.595 in the ultra-relativistic limit. (author)

  18. Attosecond-correlated dynamics of two electrons in argon

    Indian Academy of Sciences (India)

    2014-01-11

    Jan 11, 2014 ... 2Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany ... involving a highly correlated electronic transition state. ... laser is low, the recolliding electron can have a maximum energy of about 15 eV which.

  19. The First Two Electron Linear Accelerators in South Africa | Minnaar ...

    African Journals Online (AJOL)

    The electron linear accelerator is considered by many leading radiotherapy centres throughout the world as the most suitable equipment for the treatment of cancer. There are good reasons for this opinion, and some physical aspects are summarised here. S. Afr. Med. J., 48, 1004 (1974) ...

  20. Safe reduction rules for weighted treewidth

    NARCIS (Netherlands)

    Eijkhof, F. van den; Bodlaender, H.L.; Koster, A.M.C.A.

    2002-01-01

    Several sets of reductions rules are known for preprocessing a graph when computing its treewidth. In this paper, we give reduction rules for a weighted variant of treewidth, motivated by the analysis of algorithms for probabilistic networks. We present two general reduction rules that are safe for

  1. [Advances in microbial genome reduction and modification].

    Science.gov (United States)

    Wang, Jianli; Wang, Xiaoyuan

    2013-08-01

    Microbial genome reduction and modification are important strategies for constructing cellular chassis used for synthetic biology. This article summarized the essential genes and the methods to identify them in microorganisms, compared various strategies for microbial genome reduction, and analyzed the characteristics of some microorganisms with the minimized genome. This review shows the important role of genome reduction in constructing cellular chassis.

  2. CO2 Reduction Catalyzed by Nitrogenase: Pathways to Formate, Carbon Monoxide, and Methane.

    Science.gov (United States)

    Khadka, Nimesh; Dean, Dennis R; Smith, Dayle; Hoffman, Brian M; Raugei, Simone; Seefeldt, Lance C

    2016-09-06

    The reduction of N2 to NH3 by Mo-dependent nitrogenase at its active-site metal cluster FeMo-cofactor utilizes reductive elimination of Fe-bound hydrides with obligatory loss of H2 to activate the enzyme for binding/reduction of N2. Earlier work showed that wild-type nitrogenase and a nitrogenase with amino acid substitutions in the MoFe protein near FeMo-cofactor can catalytically reduce CO2 by two or eight electrons/protons to carbon monoxide (CO) and methane (CH4) at low rates. Here, it is demonstrated that nitrogenase preferentially reduces CO2 by two electrons/protons to formate (HCOO(-)) at rates >10 times higher than rates of CO2 reduction to CO and CH4. Quantum mechanical calculations on the doubly reduced FeMo-cofactor with a Fe-bound hydride and S-bound proton (E2(2H) state) favor a direct reaction of CO2 with the hydride ("direct hydride transfer" reaction pathway), with facile hydride transfer to CO2 yielding formate. In contrast, a significant barrier is observed for reaction of Fe-bound CO2 with the hydride ("associative" reaction pathway), which leads to CO and CH4. Remarkably, in the direct hydride transfer pathway, the Fe-H behaves as a hydridic hydrogen, whereas in the associative pathway it acts as a protic hydrogen. MoFe proteins with amino acid substitutions near FeMo-cofactor (α-70(Val→Ala), α-195(His→Gln)) are found to significantly alter the distribution of products between formate and CO/CH4.

  3. Reduction of lumichrome by the radical anions of CO2 and lipoamide

    International Nuclear Information System (INIS)

    Ahmad, R.; Armstrong, D.A.

    1984-01-01

    The uptake of reducing equivalents of .CO 2 - by lumichrome in spectrophotometric titrations has been re-examined in the light of a recently reported extinction coefficient of 10 500 M -1 cm -1 at pH 6, which is in agreement with 10 270 +- 100 M -1 cm -1 determined here. The average uptake was 1.8 +- 0.1, independent of pH in the range 6.3-9.0. The major product appears to be a dihydro-alloxazine, which can be reoxidized quantitatively to lumichrome by .Br 2 - radicals or by O 2 . As in the case of dihydroflavins, oxidation by O 2 is biphasic. As in the case of flavins, a two electron reduction of lumichrome was also observed with the disulphide monoanion of lipoamide (LS. 2 - ), but that reduction does not go to 100 per cent yield. Contrary to our earlier conclusions, which were based on an erroneous extinction coefficient, the combination of lumichrome radicals (2.LcH→HLc-LcH) was of relatively little (< approx. 20 per cent) importance, and the behaviour of lumichrome on treatment with reducing species was rather similar to that of flavins. (author)

  4. Oxygen reduction of several gold alloys in 1-molar potassium hydroxide

    Science.gov (United States)

    Miller, R. O.

    1975-01-01

    With rotated disk-and-ring equipment, polarograms and other electrochemical measurements were made of oxygen reduction in 1-molar potassium hydroxide on an equiatomic gold-copper (Au-Cu) alloy and a Au-Cu alloy doped with either indium (In) or cobalt (Co) and on Au doped with either nickel (Ni) or platinum (Pt). The results were compared with those for pure Au and pure Pt. The two-electron reaction dominated on all Au alloys as it did on Au. The polarographic results at lower polarization potentials were compared, assuming exclusively a two-step reduction. A qualified ranking of cathodic electrocatalytic activity on the freshly polished reduced disks was indicated: anodized Au Au-Cu-In Au-Cu Au-Cu-Co is equivalent or equal to Au-Pt Au-Ni. Aging in distilled water improved the electrocatalytic efficiency of Au-Cu-Co, Au-Cu, and (to a lesser extent) Au-Cu-In.

  5. Admissible invariant distributions on reductive

    CERN Document Server

    Harish-Chandra; Paul J Sally, Jr

    1999-01-01

    Harish-Chandra presented these lectures on admissible invariant distributions for p-adic groups at the Institute for Advanced Study in the early 1970s. He published a short sketch of this material as his famous "Queen's Notes". This book, which was prepared and edited by DeBacker and Sally, presents a faithful rendering of Harish-Chandra's original lecture notes. The main purpose of Harish-Chandra's lectures was to show that the character of an irreducible admissible representation of a connected reductive p-adic group G is represented by a locally summable function on G. A key ingredient in this proof is the study of the Fourier transforms of distributions on \\mathfrak g, the Lie algebra of G. In particular, Harish-Chandra shows that if the support of a G-invariant distribution on \\mathfrak g is compactly generated, then its Fourier transform has an asymptotic expansion about any semisimple point of \\mathfrak g. Harish-Chandra's remarkable theorem on the local summability of characters for p-adic groups was ...

  6. Software for Probabilistic Risk Reduction

    Science.gov (United States)

    Hensley, Scott; Michel, Thierry; Madsen, Soren; Chapin, Elaine; Rodriguez, Ernesto

    2004-01-01

    A computer program implements a methodology, denoted probabilistic risk reduction, that is intended to aid in planning the development of complex software and/or hardware systems. This methodology integrates two complementary prior methodologies: (1) that of probabilistic risk assessment and (2) a risk-based planning methodology, implemented in a prior computer program known as Defect Detection and Prevention (DDP), in which multiple requirements and the beneficial effects of risk-mitigation actions are taken into account. The present methodology and the software are able to accommodate both process knowledge (notably of the efficacy of development practices) and product knowledge (notably of the logical structure of a system, the development of which one seeks to plan). Estimates of the costs and benefits of a planned development can be derived. Functional and non-functional aspects of software can be taken into account, and trades made among them. It becomes possible to optimize the planning process in the sense that it becomes possible to select the best suite of process steps and design choices to maximize the expectation of success while remaining within budget.

  7. Electrochemical Reduction of Zinc Phosphate

    International Nuclear Information System (INIS)

    Kim, Chang Hwan; Lee, Jung Hyun; Shin, Woon Sup

    2010-01-01

    We demonstrated first that the electrochemical reduction of zinc phosphate in neutral phosphate buffer is possible and potentially applicable to bio-compatible rechargeable battery. The actual redox component is Zn(s)/Zn phosphate(s) and the future research about the control of crystal formation for the better cyclability is required. In lead-acid battery, the electrochemical redox reaction of Pb (s) /PbSO 4(s) is used by reducing Pb(II) and oxidizing Pb(0) in sulfate rich solution. Since both reduced form and oxidized form are insoluble, they cannot diffuse to the opposite electrodes and react. It is a very common strategy to make a stable battery electrode that a metal element is reduced and oxidized in solution containing an abundance of anion readily precipitating with the metal ion. For the application of this strategy to construction of rechargeable battery using bio-compatible electrode materials and electrolytes, the use of phosphate ion can be considered as anion readily precipitating with metal ions. If phosphate buffer with neutral pH is used as electrolyte, the better bio-compatibility will be achieved than most of rechargeable battery using strong acid, strong base or organic solvent as electrolyte solution. There are many metal ions readily precipitating with phos-phate ion, and zinc is one of them

  8. The Study of NADPH-Dependent Flavoenzyme-Catalyzed Reduction of Benzo[1,2-c]1,2,5-oxadiazole N-Oxides (Benzofuroxans

    Directory of Open Access Journals (Sweden)

    Jonas Šarlauskas

    2014-12-01

    Full Text Available The enzymatic reactivity of a series of benzo[1,2-c]1,2,5-oxadiazole N-oxides (benzofuroxans; BFXs towards mammalian single-electron transferring NADPH:cytochrome P-450 reductase (P-450R and two-electron (hydride transferring NAD(PH:quinone oxidoreductase (NQO1 was examined in this work. Since the =N+ (→OO− moiety of furoxan fragments of BFXs bears some similarity to the aromatic nitro-group, the reactivity of BFXs was compared to that of nitro-aromatic compounds (NACs whose reduction mechanisms by these and other related flavoenzymes have been extensively investigated. The reduction of BFXs by both P-450R and NQO1 was accompanied by O2 uptake, which was much lower than the NADPH oxidation rate; except for annelated BFXs, whose reduction was followed by the production of peroxide. In order to analyze the possible quantitative structure-activity relationships (QSARs of the enzymatic reactivity of the compounds, their electron-accepting potency and other reactivity indices were assessed by quantum mechanical methods. In P-450R-catalyzed reactions, both BFXs and NACs showed the same reactivity dependence on their electron-accepting potency which might be consistent with an “outer sphere” electron transfer mechanism. In NQO1-catalyzed two-electron (hydride transferring reactions, BFXs acted as more efficient substrates than NACs, and the reduction efficacy of BFXs by NQO1 was in general higher than by single-electron transferring P-450R. In NQO1-catalyzed reactions, QSARs obtained showed that the reduction efficacy of BFXs, as well as that of NACs, was determined by their electron-accepting potency and could be influenced by their binding mode in the active center of NQO1 and by their global softness as their electronic characteristic. The reductive conversion of benzofuroxan by both flavoenzymes yielded the same reduction product of benzofuroxan, 2,3-diaminophenazine, with the formation of o-benzoquinone dioxime as a putative primary

  9. Telerobotics for dry size reduction

    International Nuclear Information System (INIS)

    Sturm, A.J. Jr; La Valle, D.R.

    1996-01-01

    Remote handling in nuclear Environmental Management (EM) programs is likely to emphasize small batch sizes in unstructured environments. Most existing robotic solutions are impractical due to cost, complexity, or reliability issues. New processes that are environmentally safe are too demanding for human operators, and require precise motion control making traditional electromechanical, hydraulic, and master/slave manipulators unacceptable. The critical missing element is a method to bridge the gap between manual operation and full automation. Rapid advances in computer technology, coupled with national laboratory research activities, has challenged PaR Systems to develop a new line of telerobotics, exploiting this technology, to enhance EM processes. Telerobotics systems permit the human operator to direct and supervise the operation of a remote robotic mechanism. The typical robotic device responds to human inputs and transfers human motion into robot motion. However, unlike teleoperation, the robotic system not only incorporates local decision making authority but can enhance input devices by; producing motion in multiple coordinate frames (e.g., base, tool, joint), automating repetitive motions, responding to real-time sensory input, and facilitating a virtual collaborative environment. The basic premise is to augment, not replace, the human operator and blend the individual abilities of each system. Humans have superior cognitive and pattern recognitive skills, while the robot is a tireless precise positioning device. To provide insight into why telerobotics is crucial to EM, this paper highlights a proposed telerobotic system for the Dry Size Reduction of contaminated components. Different design concepts, robotic control features, and networking for remote operation needed are discussed. (author)

  10. Lake Nasser evaporation reduction study

    Directory of Open Access Journals (Sweden)

    Hala M.I. Ebaid

    2010-10-01

    Full Text Available This study aims to evaluate the reduction of evaporation of Lake Nasser’s water caused by disconnecting (fully or partially some of its secondary channels (khors. This evaluation integrates remote sensing, Geographic Information System (GIS techniques, aerodynamic principles, and Landsat7 ETM+ images. Three main procedures were carried out in this study; the first derived the surface temperature from Landsat thermal band; the second derived evaporation depth and approximate evaporation volume for the entire lake, and quantified evaporation loss to the secondary channels’ level over one month (March by applied aerodynamic principles on surface temperature of the raster data; the third procedure applied GIS suitability analysis to determine which of these secondary channels (khors should be disconnected. The results showed evaporation depth ranging from 2.73 mm/day at the middle of the lake to 9.58 mm/day at the edge. The evaporated water-loss value throughout the entire lake was about 0.86 billion m3/month (March. The analysis suggests that it is possible to save an approximate total evaporation volume loss of 19.7 million m3/month (March, and thus 2.4 billion m3/year, by disconnecting two khors with approximate construction heights of 8 m and 15 m. In conclusion, remote sensing and GIS are useful for applications in remote locations where field-based information is not readily available and thus recommended for decision makers remotely planning in water conservation and management.

  11. Training smarter: Refocus through reduction

    International Nuclear Information System (INIS)

    Durham, L.B.

    1991-01-01

    In this era of ever increasing operations and maintenance (O and M) costs, the Tennessee Valley Authority (TVA) like most other nuclear utilities, has been faced with the problem of reducing its overhead costs while at the same time maintaining its commitment to providing effective training. Due in part to the extended shutdown of its operating nuclear plants (Sequoyah and Browns Ferry Nuclear Plants) and faced with continued delays in its construction programs at the Watts Bar and Bellefonte Nuclear Plants, TVA had relied on an expanded complement of personnel in all facets of its nuclear program to get back on track and operating once again. Nuclear Training was no exception. At one point in the recovery process (1988), Nuclear Training had an authorized manpower level of 573. Faced with spiraling O and M costs, potential loss of long-term customers to neighboring utilities, and enormous outstanding debt, TVA management responded by setting goals that included becoming the best electric utility in North America and the most productive and effective agency in the Federal government. Operating TVA like a business became second only to safety as a managerial objective. Accountability for planning ahead, achieving goals, and operating within authorized budgets became a way of life. Work forces were reduced significantly including reduction of Nuclear Training's complement to 203. In spite of the importance of training to a nuclear utility, Nuclear Training was not immune to such sweeping changes. Program scope was refocused on accredited and regulatory training. The purpose of this paper is to explain the major elements of this revitalization program

  12. REDUCTION CAPACITY OF SALTSTONE AND SALTSTONE COMPONENTS

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, K.; Kaplan, D.

    2009-11-30

    The duration that saltstone retains its ability to immobilize some key radionuclides, such as technetium (Tc), plutonium (Pu), and neptunium (Np), depends on its capacity to maintain a low redox status (or low oxidation state). The reduction capacity is a measure of the mass of reductants present in the saltstone; the reductants are the active ingredients that immobilize Tc, Pu, and Np. Once reductants are exhausted, the saltstone loses its ability to immobilize these radionuclides. The reduction capacity values reported here are based on the Ce(IV)/Fe(II) system. The Portland cement (198 {micro}eq/g) and especially the fly ash (299 {micro}eq/g) had a measurable amount of reduction capacity, but the blast furnace slag (820 {micro}eq/g) not surprisingly accounted for most of the reduction capacity. The blast furnace slag contains ferrous iron and sulfides which are strong reducing and precipitating species for a large number of solids. Three saltstone samples containing 45% slag or one sample containing 90% slag had essentially the same reduction capacity as pure slag. There appears to be some critical concentration between 10% and 45% slag in the Saltstone formulation that is needed to create the maximum reduction capacity. Values from this work supported those previously reported, namely that the reduction capacity of SRS saltstone is about 820 {micro}eq/g; this value is recommended for estimating the longevity that the Saltstone Disposal Facility will retain its ability to immobilize radionuclides.

  13. Two-equivalent electrochemical reduction of a cyano-complex [TlIII(CN)2]+ and the novel di-nuclear compound [(CN)5PtII-TlIII]0

    International Nuclear Information System (INIS)

    Dolidze, Tina D.; Khoshtariya, Dimitri E.; Behm, Martin; Lindbergh, Goeran; Glaser, Julius

    2005-01-01

    Extending our recent insights in two-electron transfer microscopic mechanisms for a Tl III /Tl I redox system [D.E. Khoshtariya, et al., Inorg. Chem. 41 (2002) 1728], the electrochemical response of glassy carbon electrode in acidified solutions of Tl III (ClO 4 ) 3 containing different concentrations of sodium cyanide has been extensively studied for the first time by use of cyclic voltammetry and the CVSIM curve simulation PC program. The complex [Tl III (CN) 2 ] + has been thoroughly identified electrochemically and shown to display a single well-defined reduction wave (which has no anodic counterpart), ascribed to the two-equivalent process yielding [Tl I (aq)] + . This behavior is similar to that of [Tl III (aq)] 3+ ion in the absence of sodium cyanide, disclosed in the previous work, and is compatible with the quasi-simultaneous yet sequential two-electron transfer pattern (with two reduction waves merged in one), implying the rate-determining first electron transfer step (resulting in the formation of a covalently interacting di-thallium complex as a metastable intermediate), and the fast second electron transfer step. Some preliminary studies of the two-equivalent reduction of directly metal-metal bonded stable compound [(CN) 5 Pt II -Tl III ] 0 has been also performed displaying two reduction waves compatible with a true sequential pattern

  14. Three Syntactic Theories for Combinatory Graph Reduction

    DEFF Research Database (Denmark)

    Danvy, Olivier; Zerny, Ian

    2013-01-01

    , as a store-based reduction semantics of combinatory term graphs. We then refocus this store-based reduction semantics into a store-based abstract machine. The architecture of this store-based abstract machine coincides with that of Turner's original reduction machine. The three syntactic theories presented......We present a purely syntactic theory of graph reduction for the canonical combinators S, K, and I, where graph vertices are represented with evaluation contexts and let expressions. We express this rst syntactic theory as a storeless reduction semantics of combinatory terms. We then factor out...... the introduction of let expressions to denote as many graph vertices as possible upfront instead of on demand . The factored terms can be interpreted as term graphs in the sense of Barendregt et al. We express this second syntactic theory, which we prove equivalent to the rst, as a storeless reduction semantics...

  15. Reductive photocatalysis and smart inks.

    Science.gov (United States)

    Mills, Andrew; Wells, Nathan

    2015-05-21

    Semiconductor-sensitised photocatalysis is a well-established and growing area of research, innovation and commercialisation; the latter being mostly limited to the use of TiO2 as the semiconductor. Most of the work on semiconductor photocatalytic systems uses oxygen as the electron acceptor and explores a wide range of electron donors; such systems can be considered to be examples of oxidative photocatalysis, OP. OP underpins most current examples of commercial self-cleaning materials, such as: glass, tiles, concrete, paint and fabrics. OP, and its myriad of applications, have been reviewed extensively over the years both in this journal and elsewhere. However, the ability of TiO2, and other semiconductor sensitisers, to promote reductive photocatalysis, RP, especially of dyes, is significant and, although less well-known, is of growing importance. In such systems, the source of the electrons is some easily oxidised species, such as glycerol. One recent, significant example of a RP process is with respect to photocatalyst activity indicator inks. paiis, which provide a measure of the activity of a photocatalytic film under test via the rate of change of colour of the dye in the ink coating due to irreversible RP. In contrast, by incorporating the semiconductor sensitiser in the ink, rather than outside it, it is possible to create an effective UV dosimeter, based on RP, which can be used as a sun-burn warning indicator. In the above examples the dye is reduced irreversibly, but when the photocatalyst in an ink is used to reversibly photoreduce a dye, a novel, colourimetric oxygen-sensitive indicator ink can be created, which has commercial potential in the food packaging industry. Finally, if no dye is present in the ink, and the semiconductor photocatalyst-loaded ink film coats an easily reduced substrate, such as a metal oxide film, then it can be used to reduce the latter and so, for example, clean up tarnished steel. The above are examples of smart inks, i

  16. REDUCTIONS WITHOUT REGRET: HISTORICAL PERSPECTIVES

    Energy Technology Data Exchange (ETDEWEB)

    Swegle, J.; Tincher, D.

    2013-09-09

    This is the first of three papers (in addition to an introductory summary) aimed at providing a framework for evaluating future reductions or modifications of the U.S. nuclear force, first by considering previous instances in which nuclear-force capabilities were eliminated; second by looking forward into at least the foreseeable future at the features of global and regional deterrence (recognizing that new weapon systems currently projected will have expected lifetimes stretching beyond our ability to predict the future); and third by providing examples of past or possible undesirable outcomes in the shaping of the future nuclear force, as well as some closing thoughts for the future. This paper examines the circumstances and consequences of the elimination of The INF-range Pershing II ballistic missile and Gryphon Ground-Launched Cruise Missile (GLCM), deployed by NATO under a dual-track strategy to counter Soviet intermediate-range missiles while pursuing negotiations to limit or eliminate all of these missiles. The Short-Range Attack Missile (SRAM), which was actually a family of missiles including SRAM A, SRAM B (never deployed), and SRAM II and SRAM T, these last two cancelled during an over-budget/behind-schedule development phase as part of the Presidential Nuclear Initiatives of 1991 and 1992. The nuclear-armed version of the Tomahawk Land-Attack Cruise Missile (TLAM/N), first limited to shore-based storage by the PNIs, and finally eliminated in deliberations surrounding the 2010 Nuclear Posture Review Report. The Missile-X (MX), or Peacekeeper, a heavy MIRVed ICBM, deployed in fixed silos, rather than in an originally proposed mobile mode. Peacekeeper was likely intended as a bargaining chip to facilitate elimination of Russian heavy missiles. The plan failed when START II did not enter into force, and the missiles were eliminated at the end of their intended service life. The Small ICBM (SICBM), or Midgetman, a road-mobile, single-warhead missile for

  17. Harm reduction principles for healthcare settings

    Directory of Open Access Journals (Sweden)

    Mary Hawk

    2017-10-01

    Full Text Available Abstract Background Harm reduction refers to interventions aimed at reducing the negative effects of health behaviors without necessarily extinguishing the problematic health behaviors completely. The vast majority of the harm reduction literature focuses on the harms of drug use and on specific harm reduction strategies, such as syringe exchange, rather than on the harm reduction philosophy as a whole. Given that a harm reduction approach can address other risk behaviors that often occur alongside drug use and that harm reduction principles have been applied to harms such as sex work, eating disorders, and tobacco use, a natural evolution of the harm reduction philosophy is to extend it to other health risk behaviors and to a broader healthcare audience. Methods Building on the extant literature, we used data from in-depth qualitative interviews with 23 patients and 17 staff members from an HIV clinic in the USA to describe harm reduction principles for use in healthcare settings. Results We defined six principles of harm reduction and generalized them for use in healthcare settings with patients beyond those who use illicit substances. The principles include humanism, pragmatism, individualism, autonomy, incrementalism, and accountability without termination. For each of these principles, we present a definition, a description of how healthcare providers can deliver interventions informed by the principle, and examples of how each principle may be applied in the healthcare setting. Conclusion This paper is one of the firsts to provide a comprehensive set of principles for universal harm reduction as a conceptual approach for healthcare provision. Applying harm reduction principles in healthcare settings may improve clinical care outcomes given that the quality of the provider-patient relationship is known to impact health outcomes and treatment adherence. Harm reduction can be a universal precaution applied to all individuals regardless of

  18. Reduction of symplectic principal R-bundles

    International Nuclear Information System (INIS)

    Lacirasella, Ignazio; Marrero, Juan Carlos; Padrón, Edith

    2012-01-01

    We describe a reduction process for symplectic principal R-bundles in the presence of a momentum map. These types of structures play an important role in the geometric formulation of non-autonomous Hamiltonian systems. We apply this procedure to the standard symplectic principal R-bundle associated with a fibration π:M→R. Moreover, we show a reduction process for non-autonomous Hamiltonian systems on symplectic principal R-bundles. We apply these reduction processes to several examples. (paper)

  19. Reduction Expansion Synthesis for Magnetic Alloy Powders

    Science.gov (United States)

    2015-12-01

    in Figure 1, the Army was able to address its need for printable plastic components, thus enabling a reduction in the total quantity of spare...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited REDUCTION EXPANSION SYNTHESIS FOR...Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202–4302, and to the Office of Management and Budget, Paperwork Reduction Project

  20. Direct 'delay' reductions of the Toda equation

    International Nuclear Information System (INIS)

    Joshi, Nalini

    2009-01-01

    A new direct method of obtaining reductions of the Toda equation is described. We find a canonical and complete class of all possible reductions under certain assumptions. The resulting equations are ordinary differential-difference equations, sometimes referred to as delay-differential equations. The representative equation of this class is hypothesized to be a new version of one of the classical Painleve equations. The Lax pair associated with this equation is obtained, also by reduction. (fast track communication)

  1. Hexavalent Chromium reduction by Trichoderma inhamatum

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Battera, L.; Cristiani-Urbina, E.

    2009-07-01

    Reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] is a useful and attractive process for remediation of ecosystems and industrial effluents contaminated with Cr(VI). Cr(VI) reduction to Cr(II) can be achieved by both chemical and biological methods; however, the biological reduction is more convenient than the chemical one since costs are lower, and sludge is generated in smaller amounts. (Author)

  2. Harm reduction principles for healthcare settings.

    Science.gov (United States)

    Hawk, Mary; Coulter, Robert W S; Egan, James E; Fisk, Stuart; Reuel Friedman, M; Tula, Monique; Kinsky, Suzanne

    2017-10-24

    Harm reduction refers to interventions aimed at reducing the negative effects of health behaviors without necessarily extinguishing the problematic health behaviors completely. The vast majority of the harm reduction literature focuses on the harms of drug use and on specific harm reduction strategies, such as syringe exchange, rather than on the harm reduction philosophy as a whole. Given that a harm reduction approach can address other risk behaviors that often occur alongside drug use and that harm reduction principles have been applied to harms such as sex work, eating disorders, and tobacco use, a natural evolution of the harm reduction philosophy is to extend it to other health risk behaviors and to a broader healthcare audience. Building on the extant literature, we used data from in-depth qualitative interviews with 23 patients and 17 staff members from an HIV clinic in the USA to describe harm reduction principles for use in healthcare settings. We defined six principles of harm reduction and generalized them for use in healthcare settings with patients beyond those who use illicit substances. The principles include humanism, pragmatism, individualism, autonomy, incrementalism, and accountability without termination. For each of these principles, we present a definition, a description of how healthcare providers can deliver interventions informed by the principle, and examples of how each principle may be applied in the healthcare setting. This paper is one of the firsts to provide a comprehensive set of principles for universal harm reduction as a conceptual approach for healthcare provision. Applying harm reduction principles in healthcare settings may improve clinical care outcomes given that the quality of the provider-patient relationship is known to impact health outcomes and treatment adherence. Harm reduction can be a universal precaution applied to all individuals regardless of their disclosure of negative health behaviors, given that health

  3. Reduction of nuclear waste with ALMRS

    International Nuclear Information System (INIS)

    Bultman, J.H.

    1993-10-01

    The Advanced Liquid Metal Reactor (ALMR) can operate on LWR discharged material. In the calculation of the reduction of this material in the ALMR the inventory of the core should be taken into account. A high reduction can only be obtained if this inventory is reduced during operation of ALMRs. Then, it is possible to achieve a high reduction upto a factor 100 within a few hundred years. (orig.)

  4. Developing emission reduction credit trading in Texas

    International Nuclear Information System (INIS)

    Dodds, J.E.

    1993-01-01

    The Texas Air Control Board has begun to develop a system of emission reduction credit training. The system will be developed incrementally over time. The first step, banking of VOC and NO x Emission Reduction Credits, began March 15, 1993. Additional programs under study and development include NO x RACT trading, emission credits for motor vehicle scrappage and alternative fuel conversion, and establishment of community organizations to generate and acquire emission reduction credits for economic development purposes

  5. Redox cycles of vitamin E: Hydrolysis and ascorbic acid dependent reduction of 8a-(alkyldioxy)tocopherones

    International Nuclear Information System (INIS)

    Liebler, D.C.; Kaysen, K.L.; Kennedy, T.A.

    1989-01-01

    Oxidation of the biological antioxidant α-tocopherol (vitamin E; TH) by peroxyl radicals yields 8a-(alkyldioxy)tocopherones, which either may hydrolyze to α-tocopheryl quinone (TQ) or may be reduced by ascorbic acid to regenerate TH. To define the chemistry of this putative two-electron TH redox cycle, we studied the hydrolysis and reduction of 8a-[(2,4-dimethyl-1-nitrilopent-2-yl)dioxyl]tocopherone (1) in acetonitrile/buffer mixtures and in phospholipid liposomes. TQ formation in acetonitrile/buffer mixtures, which was monitored spectrophotometrically, declined with increasing pH and could not be detected above pH 4. The rate of TQ formation from 1 first increased with time and then decreased in a first-order terminal phase. Rearrangement of 8a-hydroxy-α-tocopherone (2) to TQ displayed first-order kinetics identical with the terminal phase for TQ formation from 1. Both rate constants increased with decreasing pH. Hydrolysis of 1 in acetonitrile/H 2 18 O yielded [ 18 O]TQ. These observations suggest that 1 loses the 8a-(alkyldioxy) moiety to produce the tocopherone cation (T + ), which hydrolyzes to 2, the TQ-forming intermediate. Incubation of either 1 or 2 with ascorbic acid in acetonitrile/buffer yielded TH. Reduction of both 1 and 2 decreased with increasing pH. In phosphatidylcholine liposomes at pH 7, approximately 10% of the T + generated from 1 was reduced to TH by 5 mM ascorbic acid. The results collectively demonstrate that T + is the ascorbic acid reducible intermediate in a two-electron TH redox cycle, a process that probably would require biocatalysis to proceed in biological membranes

  6. On Graph Rewriting, Reduction and Evaluation

    DEFF Research Database (Denmark)

    Zerny, Ian

    2010-01-01

    We inter-derive two prototypical styles of graph reduction: reduction machines à la Turner and graph rewriting systems à la Barendregt et al. To this end, we adapt Danvy et al.'s mechanical program derivations from the world of terms to the world of graphs. We also outline how to inter-derive a t......We inter-derive two prototypical styles of graph reduction: reduction machines à la Turner and graph rewriting systems à la Barendregt et al. To this end, we adapt Danvy et al.'s mechanical program derivations from the world of terms to the world of graphs. We also outline how to inter...

  7. Optimal reduction of flexible dynamic system

    International Nuclear Information System (INIS)

    Jankovic, J.

    1994-01-01

    Dynamic system reduction is basic procedure in various problems of active control synthesis of flexible structures. In this paper is presented direct method for system reduction by explicit extraction of modes included in reduced model form. Criterion for optimal system discrete approximation in synthesis reduced dynamic model is also presented. Subjected method of system decomposition is discussed in relation to the Schur method of solving matrix algebraic Riccati equation as condition for system reduction. By using exposed method procedure of flexible system reduction in addition with corresponding example is presented. Shown procedure is powerful in problems of active control synthesis of flexible system vibrations

  8. NOx reduction using biomass as reburning fuel

    Energy Technology Data Exchange (ETDEWEB)

    Niu Sheng-li; Lu Chun-mei; Gao Pan; Han Kui-hua; Geng Ping; Cheng Zhong-jie [Shandong University, Jinan (China). School of Energy and Power Engineering

    2008-10-15

    A series of experiments were conducted in a multiple-functional combustion test bed with several kinds of biomass as reburning fuel to reduce NOx. The character and experimental parameters are, emphasized to examine the influences on NOx reduction. The results show that biomass could get about 55% to 70% NOx reduction. Within a certain range of the parameters tested, NOx reduction increases with the increasing temperature of reburning zone and initial concentration of NOx and with decreasing excess air ratio and diameter of fuel particle. Under the same test conditions, cornstalk gets the highest NOx reduction and wheat straw, peanut shell, wood chip follow in turn. 14 refs., 7 figs., 1 tab.

  9. First Class Call Stacks: Exploring Head Reduction

    Directory of Open Access Journals (Sweden)

    Philip Johnson-Freyd

    2016-06-01

    Full Text Available Weak-head normalization is inconsistent with functional extensionality in the call-by-name λ-calculus. We explore this problem from a new angle via the conflict between extensionality and effects. Leveraging ideas from work on the λ-calculus with control, we derive and justify alternative operational semantics and a sequence of abstract machines for performing head reduction. Head reduction avoids the problems with weak-head reduction and extensionality, while our operational semantics and associated abstract machines show us how to retain weak-head reduction's ease of implementation.

  10. Axially symmetric U-O-Ln- and U-O-U-containing molecules from the control of uranyl reduction with simple f-block halides

    International Nuclear Information System (INIS)

    Arnold, Polly L.; Cowie, Bradley E.; Suvova, Marketa; Zegke, Markus; Love, Jason B.; Magnani, Nicola; Colineau, Eric; Griveau, Jean-Christophe; Caciuffo, Roberto

    2017-01-01

    The reduction of U"V"I uranyl halides or amides with simple Ln"I"I or U"I"I"I salts forms highly symmetric, linear, oxo-bridged trinuclear U"V/Ln"I"I"I/U"V, Ln"I"I"I/U"I"V/Ln"I"I"I, and U"I"V/U"I"V/U"I"V complexes or linear Ln"I"I"I/U"V polymers depending on the stoichiometry and solvent. The reactions can be tuned to give the products of one- or two-electron uranyl reduction. The reactivity and magnetism of these compounds are discussed in the context of using a series of strongly oxo-coupled homo- and heterometallic poly(f-block) chains to better understand fundamental electronic structure in the f-block. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Axially symmetric U-O-Ln- and U-O-U-containing molecules from the control of uranyl reduction with simple f-block halides

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, Polly L.; Cowie, Bradley E.; Suvova, Marketa; Zegke, Markus; Love, Jason B. [EaStCHEM School of Chemistry, University of Edinburgh (United Kingdom); Magnani, Nicola; Colineau, Eric; Griveau, Jean-Christophe; Caciuffo, Roberto [European Commission, Directorate for Nuclear Safety and Security, Joint Research Centre, Karlsruhe (Germany)

    2017-08-28

    The reduction of U{sup VI} uranyl halides or amides with simple Ln{sup II} or U{sup III} salts forms highly symmetric, linear, oxo-bridged trinuclear U{sup V}/Ln{sup III}/U{sup V}, Ln{sup III}/U{sup IV}/Ln{sup III}, and U{sup IV}/U{sup IV}/U{sup IV} complexes or linear Ln{sup III}/U{sup V} polymers depending on the stoichiometry and solvent. The reactions can be tuned to give the products of one- or two-electron uranyl reduction. The reactivity and magnetism of these compounds are discussed in the context of using a series of strongly oxo-coupled homo- and heterometallic poly(f-block) chains to better understand fundamental electronic structure in the f-block. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Reduction by metals dissolved in liquid ammonia of keto steroids. Equilibration of the alcohols

    International Nuclear Information System (INIS)

    Giroud, A.M.

    1970-01-01

    Reducing a ketone by dissolved metals involves two electrons; we may consider as intermediate a radical-anion, then a di-anion or a carbo-anion. The radical-anion may also split and give pinacols away. In order to discuss the reduction proceeds, we had to know the respective stabilities of the alcohols, which lead us to effectuate equilibration. The first chapter is devoted to the method of preparing the androstanone-II and the androstanols-IIα and II-β. We further establish the impossibility of using our methods for reaching a conclusion about the alcohols relative stability by experimental equilibration. Last we describe the methods for reducing the ketone by alkaline and earth-alkaline metals, dissolved in liquid ammonia, either in contact with a protons donor or with a later added protons donor. The resulting mixture of the two alcohols shows a prevailing quantity of the stable equatorial isomer α. In a second chapter, we study the action of selenic acid and hydroperoxide on cholestanone-3, which leads us to study the preparation and stereochemistry of the A-nor cholestane derivates. We further describe the preparation of the A-nor cholestanols-2α and 2β, and the corresponding acetates. Equilibration of the alcohols by chemical methods shows the 2 α-alcohol more stable than the 2β, which is mathematically confirmed. Last, the reduction of the A-nor cholestanone-2 by dissolved metals consistently leads to the less stable 2 β epimer, with associated pinacols. The third chapter is devoted to the study of the androstanone-17 reductions, and the relative stabilities of the 17α and 17β alcohols. Whichever operating methods is used, we predominantly obtain the more stable 17β alcohol. In all cases, a pinacol production is observed. Summing up, we note that, in all cases, we predominantly obtain the equatorial epimer, whether it should be the more stable or the less stable. (author) [fr

  13. Confluence Reduction for Probabilistic Systems (extended version)

    NARCIS (Netherlands)

    Timmer, Mark; Stoelinga, Mariëlle Ida Antoinette; van de Pol, Jan Cornelis

    2010-01-01

    This paper presents a novel technique for state space reduction of probabilistic specifications, based on a newly developed notion of confluence for probabilistic automata. We prove that this reduction preserves branching probabilistic bisimulation and can be applied on-the-fly. To support the

  14. Industrial Diversification, Employment and Rural Poverty Reduction ...

    African Journals Online (AJOL)

    This study compares the impact of industrial diversification on employment and rural poverty reduction in China and Nigeria. The fact that both countries ... better success. Key Words: Agro-Allied Industry, Industrial Diversification, Rural Development, Poverty Reduction, Employment, Non-Farm Enterprise, Nigerian Economy.

  15. Growth and poverty reduction in Tanzania

    DEFF Research Database (Denmark)

    Arndt, Channing; Demery, Lionel; McKay, Andy

    . The household survey data documents a limited reduction in consumption poverty over the period, and what poverty reduction there has been has mostly occurred in Dar es Salaam. Indicators of non-monetary poverty have gradually improved over the past 20 years but significant differences across the country remain....

  16. Convenient Reduction of Carbonyl Compounds to their ...

    African Journals Online (AJOL)

    NICO

    Alcohols and their derivatives occupy an important position in organic synthesis. ... review also reveals that the reduction of carbonyl compounds ..... 1 H.B. Ji and Y.B. She, Green Oxidation and Reduction, China Petrochemi- cal Press, Beijing ...

  17. Reduction of soil erosion on forest roads

    Science.gov (United States)

    Edward R. Burroughs; John G. King

    1989-01-01

    Presents the expected reduction in surface erosion from selected treatments applied to forest road traveledways, cutslopes, fillslopes, and ditches. Estimated erosion reduction is expressed as functions of ground cover, slope gradient, and soil properties whenever possible. A procedure is provided to select rock riprap size for protection of the road ditch.

  18. Three extensions to subtractive crosstalk reduction

    NARCIS (Netherlands)

    Smit, F.A.; Liere, van R.; Fröhlich, B.; Fröhlich, B.; Blach, R.; Liere, van R.

    2007-01-01

    Stereo displays suffer from crosstalk, an effect that reduces or even inhibits the viewer¿s ability to correctly fuse stereoscopic images. In this paper, three extensions for improved software crosstalk reduction are introduced. First, we propose a reduction method operating in CIELAB color space to

  19. Peace and Development : Democratization, Poverty Reduction and ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Peace and Development : Democratization, Poverty Reduction and Risk Mitigation in Fragile and Post Conflict States. Both the social science literature and policymakers tend to take for granted that poverty reduction, risk mitigation and democratization are mutually reinforcing. This basic assumption was first challenged ...

  20. Gaugings at angles from orientifold reductions

    International Nuclear Information System (INIS)

    Roest, Diederik

    2009-01-01

    We consider orientifold reductions to N= 4 gauged supergravity in four dimensions. A special feature of this theory is that different factors of the gauge group can have relative angles with respect to the electro-magnetic SL(2) symmetry. These are crucial for moduli stabilization and de Sitter vacua. We show how such gaugings at angles generically arise in orientifold reductions.

  1. An algorithm for reduct cardinality minimization

    KAUST Repository

    AbouEisha, Hassan M.

    2013-12-01

    This is devoted to the consideration of a new algorithm for reduct cardinality minimization. This algorithm transforms the initial table to a decision table of a special kind, simplify this table, and use a dynamic programming algorithm to finish the construction of an optimal reduct. Results of computer experiments with decision tables from UCI ML Repository are discussed. © 2013 IEEE.

  2. Basic principles of forest fuel reduction treatments

    Science.gov (United States)

    James K. Agee; Carl N. Skinner

    2005-01-01

    Successful fire exclusion in the 20th century has created severe fire problems across the West. Not every forest is at risk of uncharacteristically severe wildfire, but drier forests are in need of active management to mitigate fire hazard. We summarize a set of simple principles important to address in fuel reduction treatments: reduction of surface fuels, increasing...

  3. Parallel Algorithms for Groebner-Basis Reduction

    Science.gov (United States)

    1987-09-25

    22209 ELEMENT NO. NO. NO. ACCESSION NO. 11. TITLE (Include Security Classification) * PARALLEL ALGORITHMS FOR GROEBNER -BASIS REDUCTION 12. PERSONAL...All other editions are obsolete. Productivity Engineering in the UNIXt Environment p Parallel Algorithms for Groebner -Basis Reduction Technical Report

  4. Methane emission reduction: an application of FUND

    NARCIS (Netherlands)

    Tol, R.S.J.; Heintz, R.J.; Lammers, P.E.M.

    2003-01-01

    Methane is, after carbon dioxide, the most important anthropogenic greenhouse gas. Governments plan to abate methane emissions. A crude set of estimates of reduction costs is included in FUND, an integrated assessment model of climate change. In a cost-benefit analysis, methane emission reduction is

  5. Time-Weighted Balanced Stochastic Model Reduction

    DEFF Research Database (Denmark)

    Tahavori, Maryamsadat; Shaker, Hamid Reza

    2011-01-01

    A new relative error model reduction technique for linear time invariant (LTI) systems is proposed in this paper. Both continuous and discrete time systems can be reduced within this framework. The proposed model reduction method is mainly based upon time-weighted balanced truncation and a recently...

  6. An algorithm for reduct cardinality minimization

    KAUST Repository

    AbouEisha, Hassan M.; Al Farhan, Mohammed; Chikalov, Igor; Moshkov, Mikhail

    2013-01-01

    This is devoted to the consideration of a new algorithm for reduct cardinality minimization. This algorithm transforms the initial table to a decision table of a special kind, simplify this table, and use a dynamic programming algorithm to finish the construction of an optimal reduct. Results of computer experiments with decision tables from UCI ML Repository are discussed. © 2013 IEEE.

  7. Electrochemical and photoelectrochemical reduction of furfurals

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung-Shin; Roylance, John James; Kubota, Stephen R.

    2018-02-06

    Electrochemical cells and photoelectrochemical cells for the reduction of furfurals are provided. Also provided are methods of using the cells to carry out the reduction reactions. Using the cells and methods, furfurals can be converted into furan alcohols or linear ketones.

  8. Catalysis of the reduction of Tl+ and of CH2Cl2 by colloidal silver in aqueous solution

    International Nuclear Information System (INIS)

    Henglein, A.

    1979-01-01

    (CH 3 ) 2 COH radicals (1-hydroxy-1-methylethyl) do not reduce Tl + or CH 2 Cl 2 in homogeneous aqueous solution. In the presence of 2.5 x 10 -4 g atom/L of colloidal silver, Tl + is reduced to yield colloidal thallium, and CH 2 Cl 2 to yield Cl - plus CH 3 Cl. These reactions occur in competition with the silver-catalyzed reduction of water. Tl + is reduced in a one-electron transfer reaction and CH 2 Cl 2 in a two-electron transfer process. The effects are understood in terms of the colloidal particles acting as a pool for electrons that is continuously charged by the organic radicals and discharged by water or dissolved substrates. The specific rate for the CH 2 Cl 2 reduction at the silver pool is 4.3 x 10 3 times greater than that of the water reduction. Electrochemical considerations are carried out to estimate a stationary potential of -0.62 V (vs the standard hydrogen electrode) for the electron pool and to discuss the energetics of the observed reactions and the possible role of adsorbed hydrogen atoms. Colloidal silver and organic radicals were radiolytically produced. 7 figures

  9. Catalysis of the reduction of Tl+ and of CH2Cl2 by colloidal silver in aqueous solution

    International Nuclear Information System (INIS)

    Henglein, A.

    1979-01-01

    (CH 3 ) 2 COH radicals (1-hydroxy-1-methylethyl) do not reduce Tl + or CH 2 CL 2 in homogeneous aqueous solution. In the presence of 2.5 x 10 -4 g atom/L of colloidal silver, Tl + is reduced to yield colloidal thallium, and CH 2 Cl 2 to yield Cl - plus CH 3 Cl. These reactions occur in competition with the silver-catalyzed reduction of water. Tl + is reduced in a one-electron transfer reaction and CH 2 Cl 2 in a two-electron transfer process. The effects are understood in terms of the colloidal particles acting as a pool for electrons that is continuously charged by the organic radicals and discharged by water or dissolved substrates. The specific rate for the CH 2 Cl 2 reduction at the silver pool is 4.3 x 10 3 times greater than that of the water reduction. Electrochemical considerations are carried out to estimate a stationary potential of -0.62 V (vs the standard hydrogen electrode) for the electron pool and to discuss the energetics of the observed reactions and tha materials handling point of view, are being determined

  10. Three Syntactic Theories for Combinatory Graph Reduction

    DEFF Research Database (Denmark)

    Danvy, Olivier; Zerny, Ian

    2011-01-01

    in a third syntactic theory. The structure of the store-based abstract machine corresponding to this third syntactic theory oincides with that of Turner's original reduction machine. The three syntactic theories presented here The three syntactic heories presented here therefore have the following......We present a purely syntactic theory of graph reduction for the canonical combinators S, K, and I, where graph vertices are represented with evaluation contexts and let expressions. We express this syntactic theory as a reduction semantics, which we refocus into the first storeless abstract machine...... for combinatory graph reduction, which we refunctionalize into the first storeless natural semantics for combinatory graph reduction.We then factor out the introduction of let expressions to denote as many graph vertices as possible upfront instead of on demand, resulting in a second syntactic theory, this one...

  11. Comparison of pressure between barium reduction and air reduction of the intussusception in children

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Hwan; Park, Sang Gyu; Park, Choong Ki; Yoon, Jong Sup [Hallym University College of Medicine, Seoul (Korea, Republic of)

    1989-08-15

    There are many method of treatment of the intussusception in children, including surgery, barium reduction, air reduction, and saline enema under ultrasonographic monitoring. Among them, barium reduction and air reduction have been used widely as nonsurgical method of treatment in radiologic department. During barium reduction, the bottle filled with barium solution must not be elevated over a 3 feet from the operating table. In air reduction, diagnostic pressure is about 60 mmHg and pressure during reduction usually is maintained between 90 mmHg and 130 mmHg. The authors have studied about pressure difference of barium solution by changing height of the bottle filled with barium solution, and have compared with pressure in air reduction. The results are as follows; 1. Pressure of 20 w/v % barium solution at the 60 cm height is 44.4 mmHg, and 69.6 mmHg at the 90 cm height. 2. Pressure of 40 w/v % barium solution at the 60 cm height is 51.4 mmHg, and 80.1 mmHg at the 90 cm height. 3. Pressure of 40 w/v % barium solution at the 90cm height is much lower than the pressure maintained during air reduction, and this difference in pressure may be one of the causes of low reduction rate in barium reduction then air reduction. 4. The pressure gradient per 10 cm height is about 8.45 mmHg in 20 w/v % barium solution, about 9.21 mmHg in 30 w/v % barium solution, and about 9.72 mmHg 40 w/v % barium solution. 5. Intraluminal pressure difference between the barium reduction and the air reduction is probably of the major causes of rapid diagnosis and high reduction rate in the air reduction.

  12. Comparison of pressure between barium reduction and air reduction of the intussusception in children

    International Nuclear Information System (INIS)

    Lee, Kyung Hwan; Park, Sang Gyu; Park, Choong Ki; Yoon, Jong Sup

    1989-01-01

    There are many method of treatment of the intussusception in children, including surgery, barium reduction, air reduction, and saline enema under ultrasonographic monitoring. Among them, barium reduction and air reduction have been used widely as nonsurgical method of treatment in radiologic department. During barium reduction, the bottle filled with barium solution must not be elevated over a 3 feet from the operating table. In air reduction, diagnostic pressure is about 60 mmHg and pressure during reduction usually is maintained between 90 mmHg and 130 mmHg. The authors have studied about pressure difference of barium solution by changing height of the bottle filled with barium solution, and have compared with pressure in air reduction. The results are as follows; 1. Pressure of 20 w/v % barium solution at the 60 cm height is 44.4 mmHg, and 69.6 mmHg at the 90 cm height. 2. Pressure of 40 w/v % barium solution at the 60 cm height is 51.4 mmHg, and 80.1 mmHg at the 90 cm height. 3. Pressure of 40 w/v % barium solution at the 90cm height is much lower than the pressure maintained during air reduction, and this difference in pressure may be one of the causes of low reduction rate in barium reduction then air reduction. 4. The pressure gradient per 10 cm height is about 8.45 mmHg in 20 w/v % barium solution, about 9.21 mmHg in 30 w/v % barium solution, and about 9.72 mmHg 40 w/v % barium solution. 5. Intraluminal pressure difference between the barium reduction and the air reduction is probably of the major causes of rapid diagnosis and high reduction rate in the air reduction

  13. INDUSTRIAL BOILER RETROFIT FOR NOX CONTROL: COMBINED SELECTIVE NONCATALYTIC REDUCTION AND SELECTIVE CATALYTIC REDUCTION

    Science.gov (United States)

    The paper describes retrofitting and testing a 590 kW (2 MBtu/hr), oil-fired, three-pass, fire-tube package boiler with a combined selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR) system. The system demonstrated 85% nitrogen oxides (NOx) reduction w...

  14. Deep sedation during pneumatic reduction of intussusception.

    Science.gov (United States)

    Ilivitzki, Anat; Shtark, Luda Glozman; Arish, Karin; Engel, Ahuva

    2012-05-01

    Pneumatic reduction of intussusception under fluoroscopic guidance is a routine procedure. The unsedated child may resist the procedure, which may lengthen its duration and increase the radiation dose. We use deep sedation during the procedure to overcome these difficulties. The purpose of this study was to summarize our experience with deep sedation during fluoroscopic reduction of intussusception and assess the added value and complication rate of deep sedation. All children with intussusception who underwent pneumatic reduction in our hospital between January 2004 and June 2011 were included in this retrospective study. Anesthetists sedated the children using propofol. The fluoroscopic studies, ultrasound (US) studies and the childrens' charts were reviewed. One hundred thirty-one attempted reductions were performed in 119 children, of which 121 (92%) were successful and 10 (8%) failed. Two perforations (1.5%) occurred during attempted reduction. Average fluoroscopic time was 1.5 minutes. No complication to sedation was recorded. Deep sedation with propofol did not add any complication to the pneumatic reduction. The fluoroscopic time was short. The success rate of reduction was high,raising the possibility that sedation is beneficial, possibly by smooth muscle relaxation.

  15. Transient burnout under rapid flow reduction condition

    International Nuclear Information System (INIS)

    Iwamura, Takamichi

    1987-01-01

    Burnout characteristics were experimentally studied using uniformly heated tube and annular test sections under rapid flow reduction conditions. Observations indicated that the onset of burnout under a flow reduction transient is caused by the dryout of a liquid film on the heated surface. The decrease in burnout mass velocity at the channel inlet with increasing flow reduction rate is attributed to the fact that the vapor flow rate continues to increase and sustain the liquid film flow after the inlet flow rate reaches the steady-state burnout flow rate. This is because the movement of the boiling boundary cannot keep up with the rapid reduction of inlet flow rate. A burnout model for the local condition could be applied to the burnout phenomena with the flow reduction under pressures of 0.5 ∼ 3.9 MPa and flow reduction rates of 0.6 ∼ 35 %/s. Based on this model, a method to predict the burnout time under a flow reduction condition was presented. The calculated burnout times agreed well with experimental results obtained by some investigators. (author)

  16. Radiology residents' experience with intussusception reduction

    International Nuclear Information System (INIS)

    Bateni, Cyrus; Stein-Wexler, Rebecca; Wootton-Gorges, Sandra L.; Li, Chin-Shang

    2011-01-01

    Residents should be exposed to adequate procedural volume to act independently upon completion of training. Informal inquiry led us to question whether residents encounter enough intussusception reductions to become comfortable with the procedure. We sought to determine radiology residents' exposure to intussusception reductions, and whether their experiences vary by region or institution. U.S. radiology residency program directors were asked to encourage their residents to complete a 12-question online survey describing characteristics of their pediatric radiology department, experiences with intussusception reduction, and confidence in their own ability to perform the procedure. Six hundred sixty-four residents responded during the study period. Of those, 308 (46.4%) had not experienced an intussusception reduction, and 228 (34%) had experienced only one or two. Twenty-two percent of fourth-year residents had never experienced an intussusception reduction, and 21% had experienced only one. Among second- through fourth-year residents, only 99 (18.3%) felt confident that they could competently reduce an intussusception (P < 0.0001), and 336 (62.2%) thought they would benefit from a computer-assisted training model simulating intussusception reduction (P < 0.0001). Radiology residents have limited opportunity to learn intussusception reduction and therefore lack confidence. Most think they would benefit from additional training with a computer-simulation model. (orig.)

  17. BARIUM REDUCTION OF INTUSSUSCEPTION IN INFANCY

    Science.gov (United States)

    Denenholz, Edward J.; Feher, George. S.

    1955-01-01

    Barium enema reduction was used as the initial routine treatment in 29 infants with intussusception. In 22 of them the intussusception was reduced by this means. In three of eight patients operated upon the intussusception was found to be reduced. Four of the remaining five patients had clinical or x-ray evidence of complications before reduction by barium enema was attempted. Twenty-one of the patients, all of whom were observed in private practice, were treated without admission to the hospital. After reduction, these patients were observed closely by the clinician. None of these patients showed clinical or x-ray signs of complications before reduction. Certain clinical and roentgen criteria must be satisfied before it can be concluded that reduction by barium enema is complete. If there are clinical signs of complications with x-ray evidence of small bowel obstruction, only a very cautious attempt at hydrostatic reduction should be made. As the time factor is generally a reliable clinical guide to reducibility, the late cases should be viewed with greater caution. Long duration of symptoms, however, is not per se a contraindication to an attempt at hydrostatic reduction. PMID:13230908

  18. The anaerobic degradation of organic matter in Danish coastal sediments: iron reduction, manganese reduction, and sulfate reduction

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene; Thamdrup, B; Hansen, Jens Würgler

    1993-01-01

    ). In the deep portion of the basin, surface Mn enrichments reached 3.5 wt%, and Mn reduction was the only important anaerobic carbon oxidation process in the upper 10 cm of the sediment. In the less Mn-rich sediments from intermediate depths in the basin, Fe reduction ranged from somewhat less, to far more...... speculate that in shallow sediments of the Skagerrak, surface Mn oxides are present in a somewhat reduced oxidation level (deep basin....

  19. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  20. Generalized Time-Limited Balanced Reduction Method

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Shaker, Fatemeh

    2013-01-01

    In this paper, a new method for model reduction of bilinear systems is presented. The proposed technique is from the family of gramian-based model reduction methods. The method uses time-interval generalized gramians in the reduction procedure rather than the ordinary generalized gramians...... and in such a way it improves the accuracy of the approximation within the time-interval which the method is applied. The time-interval generalized gramians are the solutions to the generalized time-interval Lyapunov equations. The conditions for these equations to be solvable are derived and an algorithm...

  1. Project identification for methane reduction options

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, T.

    1996-12-31

    This paper discusses efforts directed at reduction in emission of methane to the atmosphere. Methane is a potent greenhouse gas, which on a 20 year timeframe may present a similar problem to carbon dioxide. In addition, methane causes additional problems in the form of smog and its longer atmospheric lifetime. The author discusses strategies for reducing methane emission from several major sources. This includes landfill methane recovery, coalbed methane recovery, livestock methane reduction - in the form of ruminant methane reduction and manure methane recovery. The author presents examples of projects which have implemented these ideas, the economics of the projects, and additional gains which come from the projects.

  2. A reductive aminase from Aspergillus oryzae

    OpenAIRE

    Grogan, Gideon James; Aleku, Godwin; France, Scott; Man, Henry Wing-Hong; Mangas-Sanchez, Juan; Sharma, Mahima; Montgomery, Sarah L; Leipold, Friedemann; Hussain, Shahed; Turner, Nicholas

    2017-01-01

    Reductive amination is one of the most important methods for the synthesis of chiral amines. Here we report the discovery of an NADP(H)-dependent reductive aminase from Aspergillus oryzae (AspRedAm, Uniprot code Q2TW47) which can catalyse the reductive coupling of a broad set of carbonyl compounds with a variety of primary and secondary amines with up to >98% conversion and with up to >98% enantiomeric excess. In cases where both carbonyl and amine show high reactivity, it is possible to empl...

  3. A conceptual framework for noise reduction

    CERN Document Server

    Benesty, Jacob

    2015-01-01

    Though noise reduction and speech enhancement problems have been studied for at least five decades, advances in our understanding and the development of reliable algorithms are more important than ever, as they support the design of tailored solutions for clearly defined applications. In this work, the authors propose a conceptual framework that can be applied to the many different aspects of noise reduction, offering a uniform approach to monaural and binaural noise reduction problems, in the time domain and in the frequency domain, and involving a single or multiple microphones. Moreover, the derivation of optimal filters is simplified, as are the performance measures used for their evaluation.

  4. Structured building model reduction toward parallel simulation

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, Justin R. [Cornell University; Hencey, Brondon M. [Cornell University

    2013-08-26

    Building energy model reduction exchanges accuracy for improved simulation speed by reducing the number of dynamical equations. Parallel computing aims to improve simulation times without loss of accuracy but is poorly utilized by contemporary simulators and is inherently limited by inter-processor communication. This paper bridges these disparate techniques to implement efficient parallel building thermal simulation. We begin with a survey of three structured reduction approaches that compares their performance to a leading unstructured method. We then use structured model reduction to find thermal clusters in the building energy model and allocate processing resources. Experimental results demonstrate faster simulation and low error without any interprocessor communication.

  5. Reduction of U3O8 to U by a metallic reductant, Li

    International Nuclear Information System (INIS)

    Jin-Mok Hur; Sun-Seok Hong; Hansoo Lee

    2010-01-01

    Reduction of U 3 O 8 was investigated for the recycling of spent oxide fuel from a commercial nuclear power plant. The possible reduction methods were proposed and compared. Based on the thermodynamic analysis, Li metal was selected as a reductant. The optimum reaction temperature for the reduction of U 3 O 8 was investigated at the wider reaction temperature range. The adverse oxidation of U metal by Li 2 O at 1,000 deg C was experimentally verified. Ellingham diagram was constructed to investigate the extent of the uranium oxides reduction when the reaction was carried out above melting point of U metal. (author)

  6. Ion-exchange voltammetry of tris(2,2'-bipyridine) nickel(II), cobalt(II), and Co(salen) at polyestersulfonated ionomer coated electrodes in acetonitrile: Reactivity of the electrogenerated low-valent complexes

    International Nuclear Information System (INIS)

    Buriez, Olivier; Moretto, Ligia M.; Ugo, Paolo

    2006-01-01

    The electrochemical behaviour of [Ni(bpy) 3 (BF 4 ) 2 ], [Co(bpy) 3 (BF 4 ) 2 ], and Co(salen) (where bpy = 2,2'-bipyridine, and salen N,N'-bis(salicylidene)ethylenediamine) is studied at a glassy carbon electrode modified with the poly(estersulfonate) ionomer Eastman AQ 55 in acetonitrile (MeCN). It is shown that the nickel complex is strongly incorporated into the polymer. The reduction of the divalent nickel compound features a two-electron process leading to a nickel(0) species which is released from the coating because of the lack of electrostatic attraction with the ionomer. Yet, the neutral zerovalent nickel-bipyridine complex is reactive towards ethyl 4-iodobenzoate and di-bromocyclohexane despite the presence of the polymer. The activation of the aryl halide occurs through an oxidative addition, whereas, an electron transfer is involved in the presence of the alkyl halide making the catalyst regeneration much faster in the latter case. The electrochemical study of [Co(bpy) 3 (BF 4 ) 2 ] shows that incorporation of the cobalt complex into the polymer is efficient, provided excess bpy is used. This excess bpy does not interfere with the electrocatalytic activity of the cobalt complex incorporated in the AQ coating and efficient electrocatalysis is observed towards di-bromocyclohexane and benzyl-bromide as substrates. Finally, replacement of the bpy ligand with the macrocycle N,N'-bis(salicylidene)ethylenediamine, salen, leads to the incorporation of the non-charged Co II (salen) complex into the AQ 55 polymer showing the relevancy of hydrophobic interactions. The reaction between the electrogenerated [Co I (salen)] - with 1,2-dibromocyclohexane exhibits a fast inner sphere electron transfer

  7. The Effect of Carbonaceous Reductant Selection on Chromite Pre-reduction

    Science.gov (United States)

    Kleynhans, E. L. J.; Beukes, J. P.; Van Zyl, P. G.; Bunt, J. R.; Nkosi, N. S. B.; Venter, M.

    2017-04-01

    Ferrochrome (FeCr) production is an energy-intensive process. Currently, the pelletized chromite pre-reduction process, also referred to as solid-state reduction of chromite, is most likely the FeCr production process with the lowest specific electricity consumption, i.e., MWh/t FeCr produced. In this study, the effects of carbonaceous reductant selection on chromite pre-reduction and cured pellet strength were investigated. Multiple linear regression analysis was employed to evaluate the effect of reductant characteristics on the aforementioned two parameters. This yielded mathematical solutions that can be used by FeCr producers to select reductants more optimally in future. Additionally, the results indicated that hydrogen (H)- (24 pct) and volatile content (45.8 pct) were the most significant contributors for predicting variance in pre-reduction and compressive strength, respectively. The role of H within this context is postulated to be linked to the ability of a reductant to release H that can induce reduction. Therefore, contrary to the current operational selection criteria, the authors believe that thermally untreated reductants ( e.g., anthracite, as opposed to coke or char), with volatile contents close to the currently applied specification (to ensure pellet strength), would be optimal, since it would maximize H content that would enhance pre-reduction.

  8. Marine Debris Research, Prevention, and Reduction Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Debris Research, Prevention, and Reduction Act legally establishes the National Oceanic and Atmospheric Administration's (NOAA) Marine Debris Program. The...

  9. Open Reduction in Pediatric Condylar Fracture.

    Science.gov (United States)

    Barbosa, Alexandre Agostini; Mariano, Ronaldo Célio

    2017-05-01

    Facial fractures in children are rare. Lack of pneumatization, fat pockets, mixed dentition, contribute to the elasticity and bone stability. When mandibular fractures occur in children, most often involve the condyle by indirect trauma. Such fractures are the center of discussion on the form of treatment if this should be performed conservatively, or held the reduction and fixation of the fracture with surgical exposure of the fragments. In condylar fractures in children, in most patients, the proposed treatment is closed reduction. Treatment with open reduction and fixation has its specific indications. In this case, the authors report a patient cycling accident victim, with cut-contusion injury in ment with limited mouth opening and left condylar fracture with medial rotation. The treatment was the reduction and fixation of fragments by open process.

  10. Nitrogen reduction: Molybdenum does it again

    Science.gov (United States)

    Schrock, Richard R.

    2011-02-01

    Nature reduces dinitrogen under mild conditions using nitrogenases, the most active of which contains molybdenum and iron. The only abiological dinitrogen reduction catalyst that avoids the harsh conditions of the Haber-Bosch process contains just molybdenum.

  11. [Small scale direct oxide reduction (DOR) experiments

    International Nuclear Information System (INIS)

    1987-01-01

    Objectives were to provide process design information to the Plutonium Recovery Project and to produce DOR (direct oxide reduction) product which meets Foundry purity specifications and Oh-0 Foundry specifications

  12. Cyclic voltammetry and reduction mechanistic studies of ...

    African Journals Online (AJOL)

    styrylpyrylium perchlorates have been evaluated using cyclic voltammetry, in comparison to their non-methylated derivatives values. The reduction peak of all studied compounds remained chemically irreversible. The presence of the ...

  13. Sound transit climate risk reduction project.

    Science.gov (United States)

    2013-09-01

    The Climate Risk Reduction Project assessed how climate change may affect Sound Transit commuter rail, light rail, and express bus : services. The project identified potential climate change impacts on agency operations, assets, and long-term plannin...

  14. Microblowing Technique for Drag Reduction, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA seeks to develop technologies for aircraft drag reduction which contribute to improved aerodynamic efficiency in support of national goals for reducing fuel...

  15. Time requirement for barium reduction in intussusception

    International Nuclear Information System (INIS)

    Hwang, Hye Eun; Kim, Seung Ho; Kang, In Young; Park, Byoung Lan; Kim, Byoung Geun

    1988-01-01

    During the period between January 1985 and December 1987, barium reduction was performed in 146 cases of intussusception who were admitted to Kwangju Christian Hospital. The results were as follows: 1. Success rate to the symptom duration is relatively constant. 2. The success rate in infants with severe dehydration was 50% but it was gradually increased in infants with moderate dehydration and in infants with mild dehydration, 83.3% and 100% respectively. 3. The success rate of 12 cases in severely dehydrated infants with positive dissection sign was 16.7%. 4. The success rate of 15 cases in moderately dehydrated infants with positive dissection sign was 66.7%. 5. The average time requirement for barium reduction was 58.3 minutes. No serious complications were noted during barium reduction, except mild vomiting. 6. With above results, it is desirable that barium reduction should be performed according to the patient's physical status and radiologic findings.

  16. Angular reduction in multiparticle matrix elements

    International Nuclear Information System (INIS)

    Lehman, D.R.; Parke, W.C.

    1989-01-01

    A general method for reduction of coupled spherical harmonic products is presented. When the total angular coupling is zero, the reduction leads to an explicitly real expression in the scalar products of the unit vector arguments of the spherical harmonics. For nonscalar couplings, the reduction gives Cartesian tensor forms for the spherical harmonic products; tensors built from the physical vectors in the original expression. The reduction for arbitrary couplings is given in closed form, making it amenable to symbolic manipulation on a computer. The final expressions do not depend on a special choice of coordinate axes, nor do they contain azimuthal quantum number summations, or do they have complex tensor terms for couplings to a scalar; consequently, they are easily interpretable from the properties of the physical vectors they contain

  17. Quantum Hamiltonian reduction in superspace formalism

    International Nuclear Information System (INIS)

    Madsen, J.O.; Ragoucy, E.

    1994-02-01

    Recently the quantum Hamiltonian reduction was done in the case of general sl(2) embeddings into Lie algebras and superalgebras. The results are extended to the quantum Hamiltonian reduction of N=1 affine Lie superalgebras in the superspace formalism. It is shown that if we choose a gauge for the supersymmetry, and consider only certain equivalence classes of fields, then our quantum Hamiltonian reduction reduces to quantum Hamiltonian reduction of non-supersymmetric Lie superalgebras. The super energy-momentum tensor is constructed explicitly as well as all generators of spin 1 (and 1/2); thus all generators in the superconformal, quasi-superconformal and Z 2 *Z 2 superconformal algebras are constructed. (authors). 21 refs

  18. Gender equality mainstreaming: Implications for poverty reduction ...

    African Journals Online (AJOL)

    Gender equality mainstreaming: Implications for poverty reduction and sustainable development in Abia State of Nigeria. ... Empowerment of women when pursued beyond mere rhetoric and instrumentation, it will improve their wellbeing, self esteem, resource allocation, political voice and increased productivity generally.

  19. Large Scale Reduction of Graphite Oxide

    Data.gov (United States)

    National Aeronautics and Space Administration — This project seeks to develop an optical method to reduce graphite oxide into graphene efficiently and in larger formats than currently available. Current reduction...

  20. Therapeutic platelet reduction: Use in postsplenectomy thrombocytosis

    Directory of Open Access Journals (Sweden)

    Gita Negi

    2015-01-01

    Full Text Available Therapeutic platelet reduction is an effective modality for the reduction of platelet count in patients with treatment of extreme thrombocytosis resulting from a variety of primary and secondary causes of thrombocytosis, which may be associated with thrombotic or hemorrhagic complications of varying degrees. These cases when symptomatic fall into the ASFA Category II indication for therapeutic platelet apheresis procedure. Here, we report a case of postsplenectomy secondary thrombocytosis presenting with extremely high platelet counts and subsequent thrombosis in the shunt and successful treatment after therapeutic platelet reduction. The case is being presented to bring forth the fact that therapeutic platelet reduction is an easy procedure that gives quick and good results and also to bring to the attention of transfusion specialists an associated but as yet unreported procedural finding.

  1. Logistics Reduction: Advanced Clothing System (ACS)

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the Advanced Exploration System (AES) Logistics Reduction (LR) project's Advanced Clothing System (ACS) is to use advanced commercial off-the-shelf...

  2. Harm reduction-the cannabis paradox

    Directory of Open Access Journals (Sweden)

    Melamede Robert

    2005-09-01

    Full Text Available Abstract This article examines harm reduction from a novel perspective. Its central thesis is that harm reduction is not only a social concept, but also a biological one. More specifically, evolution does not make moral distinctions in the selection process, but utilizes a cannabis-based approach to harm reduction in order to promote survival of the fittest. Evidence will be provided from peer-reviewed scientific literature that supports the hypothesis that humans, and all animals, make and use internally produced cannabis-like products (endocannabinoids as part of the evolutionary harm reduction program. More specifically, endocannabinoids homeostatically regulate all body systems (cardiovascular, digestive, endocrine, excretory, immune, nervous, musculo-skeletal, reproductive. Therefore, the health of each individual is dependant on this system working appropriately.

  3. Versions of the Waste Reduction Model (WARM)

    Science.gov (United States)

    This page provides a brief chronology of changes made to EPA’s Waste Reduction Model (WARM), organized by WARM version number. The page includes brief summaries of changes and updates since the previous version.

  4. Documentation for the Waste Reduction Model (WARM)

    Science.gov (United States)

    This page describes the WARM documentation files and provides links to all documentation files associated with EPA’s Waste Reduction Model (WARM). The page includes a brief summary of the chapters documenting the greenhouse gas emission and energy factors.

  5. Drag Reduction by Leidenfrost Vapor Layers

    KAUST Repository

    Vakarelski, Ivan Uriev; Marston, Jeremy O.; Chan, Derek Y. C.; Thoroddsen, Sigurdur T

    2011-01-01

    , we show that such vapor layers can reduce the hydrodynamic drag by over 85%. These results appear to approach the ultimate limit of drag reduction possible by different methods based on gas-layer lubrication and can stimulate the development

  6. Applicabilities of ship emission reduction methods

    Energy Technology Data Exchange (ETDEWEB)

    Guleryuz, Adem [ARGEMAN Research Group, Marine Division (Turkey)], email: ademg@argeman.org; Kilic, Alper [Istanbul Technical University, Maritime Faculty, Marine Engineering Department (Turkey)], email: enviromarineacademic@yahoo.com

    2011-07-01

    Ships, with their high consumption of fossil fuels to power their engines, are significant air polluters. Emission reduction methods therefore need to be implemented and the aim of this paper is to assess the advantages and disadvantages of each emissions reduction method. Benefits of the different methods are compared, with their disadvantages and requirements, to determine the applicability of such solutions. The methods studied herein are direct water injection, humid air motor, sea water scrubbing, diesel particulate filter, selected catalytic reduction, design of engine components, exhaust gas recirculation and engine replacement. Results of the study showed that the usefulness of each emissions reduction method depends on the particular case and that an evaluation should be carried out for each ship. This study pointed out that methods to reduce ship emissions are available but that their applicability depends on each case.

  7. System reduction for nanoscale IC design

    CERN Document Server

    2017-01-01

    This book describes the computational challenges posed by the progression toward nanoscale electronic devices and increasingly short design cycles in the microelectronics industry, and proposes methods of model reduction which facilitate circuit and device simulation for specific tasks in the design cycle. The goal is to develop and compare methods for system reduction in the design of high dimensional nanoelectronic ICs, and to test these methods in the practice of semiconductor development. Six chapters describe the challenges for numerical simulation of nanoelectronic circuits and suggest model reduction methods for constituting equations. These include linear and nonlinear differential equations tailored to circuit equations and drift diffusion equations for semiconductor devices. The performance of these methods is illustrated with numerical experiments using real-world data. Readers will benefit from an up-to-date overview of the latest model reduction methods in computational nanoelectronics.

  8. Electrochemical reduction of cerium oxide into metal

    Energy Technology Data Exchange (ETDEWEB)

    Claux, Benoit [CEA, Valduc, F-21120 Is-sur-Tille (France); Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France); Serp, Jerome, E-mail: jerome.serp@cea.f [CEA, Valduc, F-21120 Is-sur-Tille (France); Fouletier, Jacques [Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France)

    2011-02-28

    The Fray Farthing and Chen (FFC) and Ono and Suzuki (OS) processes were developed for the reduction of titanium oxide to titanium metal by electrolysis in high temperature molten alkali chloride salts. The possible transposition to CeO{sub 2} reduction is considered in this study. Present work clarifies, by electro-analytical techniques, the reduction pathway leading to the metal. The reduction of CeO{sub 2} into metal was feasible via an indirect mechanism. Electrolyses on 10 g of CeO{sub 2} were carried out to evaluate the electrochemical process efficiency. Ca metal is electrodeposited at the cathode from CaCl{sub 2}-KCl solvent and reacts chemically with ceria to form not only metallic cerium, but also cerium oxychloride.

  9. Burnout characteristics under flow reduction condition

    International Nuclear Information System (INIS)

    Iwamura, Takamichi; Kuroyanagai, Toshiyuki

    1982-01-01

    Burnout characteristics in a uniformly heated, vertically oriented tube, under flow reduction condition, were experimentally studied. Test pressures ranged 0.5 -- 3.9 MPa and flow reduction rates 0.6 -- 35%/s. An analytical method was developed to obtain the local mass velocity during a transient condition. The local mass velocity at the burnout location with an increasing flow reduction rate was slightly different from that measured in steady state tests. The system pressure had a significant effect on the difference. An empirical correlation was presented to give the ratio between the transient and steady state burnout mass velocities at the burnout location as a function of the steam-water density ratio and the flow reduction rate. Experimental results of previous work were compared with this correlation. (author)

  10. Reactor power reduction system and method

    International Nuclear Information System (INIS)

    Bruno, S.J.; Dunn, S.A.; Raber, M.

    1978-01-01

    A method of operating a nuclear power reactor is disclosed which enables an accelerated power reduction of the reactor without completely shutting the reactor down. The method includes monitoring the incidents which, upon their occurrence, would require an accelerated power reduction in order to maintain the reactor in a safe operation mode; calculating the power reduction required on the occurrence of such an incident; determining a control rod insertion sequence for the normal operation of the reactor, said sequence being chosen to optimize reactor power capability; selecting the number of control rods necessary to respond to the accelerated power reduction demand, said selection being made according to a priority determined by said control rod insertion sequence; and inserting said selected control rods into the reactor core. 11 claims, 13 figures

  11. Los Alamos transuranic waste size reduction facility

    International Nuclear Information System (INIS)

    Briesmeister, A.; Harper, J.; Reich, B.; Warren, J.L.

    1982-01-01

    To facilitate disposal of transuranic (TRU) waste, Los Alamos National Laboratory designed and constructed the Size Reduction Facility (SRF) during the period 1977 to 1981. This report summarizes the engineering development, installation, and early test operations of the SRF. The facility incorporates a large stainless steel enclosure fitted with remote handling and cutting equipment to obtain an estimated 4:1 volume reduction of gloveboxes and other bulky metallic wastes

  12. Welfare Effects of Tariff Reduction Formulas

    DEFF Research Database (Denmark)

    Guldager, Jan G.; Schröder, Philipp J.H.

    WTO negotiations rely on tariff reduction formulas. It has been argued that formula approaches are of increasing importance in trade talks, because of the large number of countries involved, the wider dispersion in initial tariffs (e.g. tariff peaks) and gaps between bound and applied tariff rate....... No single formula dominates for all conditions. The ranking of the three tools depends on the degree of product differentiation in the industry, and the achieved reduction in the average tariff....

  13. Income distribution policies for faster poverty reduction

    OpenAIRE

    Addison, Tony; Cornia, Giovanni Andrea

    2001-01-01

    Inequality has risen in many countries over the last two decades, especially in the transition economies, but also in many developing and developed economies. This is disturbing since little progress can be made in poverty reduction when inequality is high and rising. Moreover, contrary to earlier theories of development, high inequality tends to reduce economic growth, and therefore poverty reduction through growth. This paper finds evidence of a concave relationship between inequality and g...

  14. Screening for breast cancer post reduction mammoplasty

    International Nuclear Information System (INIS)

    Muir, T.M.; Tresham, J.; Fritschi, L.; Wylie, E.

    2010-01-01

    Aim: To investigate whether remodelling of the breast after breast reduction surgery has an effect on mammographic cancer detection. Methods and materials: For women who attended population-based screening between January 1998 to December 2007, data were extracted on their age, history of previous breast reduction, and the result of screening (recall for further assessment, cancer, or no cancer). The number of cancers detected, recalls per 1000 screens and the characteristics of the cancers detected in the two groups was compared. Results: In total 244,147 women with 736,219 screening episodes were reviewed. In the 4743 women who had a breast reduction, 51 breast cancers were detected [age standardized rate (ASR) of 4.28 per 1000 screening episodes; 95% CI 3.11-5.46], compared with 4342 breast cancers in 239 404 women screened in the non-reduction group (ASR of 5.99 per 1000 screening episodes; 95% CI 5.81-6.16). There were fewer cancers in the breast reduction group with a relative risk of 0.71. There was no significant difference in the rate of recall between the two groups, with a crude recall rate of 46.1 per 1000 screening episodes post-breast reduction compared with 50.7 per 1000 screening episodes for women without breast reduction. There was no significant difference in the pathological type or location of the cancer between the two groups of women. Conclusion: Postoperative breast changes following reduction mammoplasty do not significantly hinder analysis of the screening mammogram.

  15. Singular reduction of Nambu-Poisson manifolds

    Science.gov (United States)

    Das, Apurba

    The version of Marsden-Ratiu Poisson reduction theorem for Nambu-Poisson manifolds by a regular foliation have been studied by Ibáñez et al. In this paper, we show that this reduction procedure can be extended to the singular case. Under a suitable notion of Hamiltonian flow on the reduced space, we show that a set of Hamiltonians on a Nambu-Poisson manifold can also be reduced.

  16. Los Alamos transuranic waste size reduction facility

    International Nuclear Information System (INIS)

    Briesmeister, A.; Harper, J.; Reich, B.; Warren, J.L.

    1982-01-01

    A transuranic (TRU) Waste Size Reduction Facility (SRF) was designed and constructed at the Los Alamos National Laboratory during the period of 1977 to 1981. This paper summarizes the engineering development, installation, and early test operations of the SRF. The facility incorporates a large stainless steel enclosure fitted with remote handling and cutting equipment to obtain an estimated 4:1 volume reduction of gloveboxes and other bulky metallic wastes

  17. Pediatric radiology fellows' experience with intussusception reduction

    International Nuclear Information System (INIS)

    Stein-Wexler, Rebecca; Bateni, Cyrus; Wootton-Gorges, Sandra L.; Li, Chin-Shang

    2011-01-01

    Intussusception reduction allows young children to avoid surgery. However, graduating residents have had relatively little training in intussusception reduction and, for the most part, consider themselves ill-prepared to perform this procedure. The goal of this study was to assess the extent of training in intussusception reduction during one year of a pediatric radiology fellowship and to determine whether graduating fellows consider themselves adequately trained in this technique. Pediatric radiology fellows were surveyed during June 2010 and asked to characterize their fellowship, to indicate the number of intussusception reductions performed (both the total number and those performed with faculty oversight but without active faculty involvement), and to assess the adequacy of their training. There were 31 responses, representing almost 1/3 of current fellows. Pediatric radiology fellows perform on average 6.9 reductions, 3.8 of which are with faculty oversight but without active faculty involvement. Ninety percent consider themselves well-trained in the technique, whereas 10% are uncertain (none consider their training inadequate). Almost all pediatric radiology fellows consider their training in intussusception reduction to be adequate. (orig.)

  18. Development of Flow Accelerated Corrosion Reduction Technology

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Min Bum; Choi, Won Yeol; Lee, Jong Chan; Lim, Dong Seok; Kwon, Byung Il; Ku, Hee Kwon; Kim, Jong Uk [FNC Tech, Yongin (Korea, Republic of)

    2015-10-15

    Development of flow accelerated corrosion reduction technology is necessary for prevent this kind of accidents. This study deals with development of flow accelerated corrosion reduction technology through platinum injection and developed of flow accelerated corrosion reduction technology by imitating water chemical condition in PWR secondary system in practice. In addition, in order to get reliability of water chemical simulator in PWR secondary system, analyzed and compared with test result through CFD analysis. This study composed test device that can simulate water chemical environment in PWR secondary system, in order to develop flow accelerated corrosion reduction , and evaluated the ratio of corrosion in water chemical environment in PWR secondary system. In conclusion, corrosion ratio of low alloy steel material that includes more Cr and Mo was lower. And the results were confirmed to be the maximum corrosion rate in the case that replicate the 90 elbow. Additionally, inserted Pt nano particle for developing flow accelerated corrosion rate reduction technology, the test results, it was confirmed for about 80% of the flow accelerated corrosion rate reduction than before input.

  19. Establishing credible emission reduction estimates: GERT's experience

    International Nuclear Information System (INIS)

    Loseth, H.

    2001-01-01

    To address the challenge of reducing the greenhouse gas emissions in Canada, the federal and provincial governments are developing strategies and policies to reach that goal. One of the proposed solutions is the establishment of an emission trading system, which it is believed would encourage investment in lower-cost reductions. The Greenhouse Gas Emission Reduction Trading (GERT) pilot was established in 1998 to examine emission trading. It represents the collaborative efforts of government, industry, and non-governmental organizations. It is possible to establish emission reduction trading outside of a regulated environment. Emission reduction is defined as being an action which reduces emissions when compared to what they would have been otherwise. The functioning of GERT was described from the initial application by a buyer/seller to the review process. The assessment of projects is based on mandatory criteria: reductions of emissions must be real, measurable, verifiable and surplus. A section of the presentation was devoted to landfill gas recovery project issues, while another dealt with fuel substitution project issues. Section 5 discussed emission reductions from an off-site source electricity project issues. figs

  20. Isoflurane minimum alveolar concentration reduction by fentanyl.

    Science.gov (United States)

    McEwan, A I; Smith, C; Dyar, O; Goodman, D; Smith, L R; Glass, P S

    1993-05-01

    Isoflurane is commonly combined with fentanyl during anesthesia. Because of hysteresis between plasma and effect site, bolus administration of fentanyl does not accurately describe the interaction between these drugs. The purpose of this study was to determine the MAC reduction of isoflurane by fentanyl when both drugs had reached steady biophase concentrations. Seventy-seven patients were randomly allocated to receive either no fentanyl or fentanyl at several predetermined plasma concentrations. Fentanyl was administered using a computer-assisted continuous infusion device. Patients were also randomly allocated to receive a predetermined steady state end-tidal concentration of isoflurane. Blood samples for fentanyl concentration were taken at 10 min after initiation of the infusion and before and immediately after skin incision. A minimum of 20 min was allowed between the start of the fentanyl infusion and skin incision. The reduction in the MAC of isoflurane by the measured fentanyl concentration was calculated using a maximum likelihood solution to a logistic regression model. There was an initial steep reduction in the MAC of isoflurane by fentanyl, with 3 ng/ml resulting in a 63% MAC reduction. A ceiling effect was observed with 10 ng/ml providing only a further 19% reduction in MAC. A 50% decrease in MAC was produced by a fentanyl concentration of 1.67 ng/ml. Defining the MAC reduction of isoflurane by all the opioids allows their more rational administration with inhalational anesthetics and provides a comparison of their relative anesthetic potencies.

  1. A randomized trial of pneumatic reduction versus hydrostatic reduction for intussusception in pediatric patients.

    Science.gov (United States)

    Xie, Xiaolong; Wu, Yang; Wang, Qi; Zhao, Yiyang; Chen, Guobin; Xiang, Bo

    2017-08-08

    Data of randomly controlled trials comparing the hydrostatic and pneumatic reduction for intussusception in pediatric patients as initial therapy are lacking. The aim of this study was to conduct a randomly controlled trial to compare the effectiveness and safety of the hydrostatic and pneumatic reduction techniques. All intussusception patients who visited West China Hospital of Sichuan University from January 2014 to December 2015 were enrolled in this study in which they underwent pneumatic reduction or hydrostatic reduction. Patients were randomized into ultrasound-guided hydrostatic or X-ray-guided pneumatic reduction group. The data collected includes demographic data, symptoms, signs, and investigations. The primary outcome of the study was the success rate of reduction. And the secondary outcomes of the study were the rates of intestinal perforations and recurrence. A total of 124 children with intussusception who had met the inclusion criteria were enrolled. The overall success rate of this study was 90.32%. Univariable analysis showed that the success rate of hydrostatic reduction with normal saline (96.77%) was significantly higher than that of pneumatic reduction with air (83.87%) (p=0.015). Perforation after reduction was found in only one of the pneumatic reduction group. The recurrence rate of intussusception in the hydrostatic reduction group was 4.84% compared with 3.23% of pneumatic reduction group. Our study found that ultrasound-guided hydrostatic reduction is a simple, safe and effective nonoperative treatment for pediatric patients suffering from intussusceptions, and should be firstly adopted in the treatment of qualified patients. Therapeutic study TYPE OF STUDY: Prospective study. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Bomb reduction of uranium tetrafluoride. Part II: Influence of the addition elements in the reduction process

    International Nuclear Information System (INIS)

    Anca Abati, R.; Lopez Rodriguez, M.

    1962-01-01

    This work shows the influence of uranium oxide and uranyl fluoride in the reduction of uranium with Ca and Mg. These additions are more harmful when using smaller bombs. The uranyl fluoride has influence in the reduction process; the curves yield-concentration shows two regions depending upon the salt concentration. The behaviour of this addition in these regions can be explained following the different decompositions that can take place during the reduction process. (Author) 9 refs

  3. Enema reduction of intussusception: the success rate of hydrostatic and pneumatic reduction.

    Science.gov (United States)

    Khorana, Jiraporn; Singhavejsakul, Jesda; Ukarapol, Nuthapong; Laohapensang, Mongkol; Wakhanrittee, Junsujee; Patumanond, Jayanton

    2015-01-01

    Intussusception is a common surgical emergency in infants and children. The incidence of intussusception is from one to four per 2,000 infants and children. If there is no peritonitis, perforation sign on abdominal radiographic studies, and nonresponsive shock, nonoperative reduction by pneumatic or hydrostatic enema can be performed. The purpose of this study was to compare the success rates of both the methods. Two institutional retrospective cohort studies were performed. All intussusception patients (ICD-10 code K56.1) who had visited Chiang Mai University Hospital and Siriraj Hospital from January 2006 to December 2012 were included in the study. The data were obtained by chart reviews and electronic databases, which included demographic data, symptoms, signs, and investigations. The patients were grouped according to the method of reduction followed into pneumatic reduction and hydrostatic reduction groups with the outcome being the success of the reduction technique. One hundred and seventy episodes of intussusception occurring in the patients of Chiang Mai University Hospital and Siriraj Hospital were included in this study. The success rate of pneumatic reduction was 61% and that of hydrostatic reduction was 44% (P=0.036). Multivariable analysis and adjusting of the factors by propensity scores were performed; the success rate of pneumatic reduction was 1.48 times more than that of hydrostatic reduction (P=0.036, 95% confidence interval [CI] =1.03-2.13). Both pneumatic and hydrostatic reduction can be performed safely according to the experience of the radiologist or pediatric surgeon and hospital setting. This study showed that pneumatic reduction had a higher success rate than hydrostatic reduction.

  4. Energy Savings from Industrial Water Reductions

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Prakash; McKane, Aimee; de Fontaine, Andre

    2015-08-03

    Although it is widely recognized that reducing freshwater consumption is of critical importance, generating interest in industrial water reduction programs can be hindered for a variety of reasons. These include the low cost of water, greater focus on water use in other sectors such as the agriculture and residential sectors, high levels of unbilled and/or unregulated self-supplied water use in industry, and lack of water metering and tracking capabilities at industrial facilities. However, there are many additional components to the resource savings associated with reducing site water use beyond the water savings alone, such as reductions in energy consumption, greenhouse gas emissions, treatment chemicals, and impact on the local watershed. Understanding and quantifying these additional resource savings can expand the community of businesses, NGOs, government agencies, and researchers with a vested interest in water reduction. This paper will develop a methodology for evaluating the embedded energy consumption associated with water use at an industrial facility. The methodology developed will use available data and references to evaluate the energy consumption associated with water supply and wastewater treatment outside of a facility’s fence line for various water sources. It will also include a framework for evaluating the energy consumption associated with water use within a facility’s fence line. The methodology will develop a more complete picture of the total resource savings associated with water reduction efforts and allow industrial water reduction programs to assess the energy and CO2 savings associated with their efforts.

  5. Sulphate reduction in the Aespoe HRL tunnel

    International Nuclear Information System (INIS)

    Gustafson, G.; Pedersen, K.; Tullborg, E.L.; Wallin, B.; Wikberg, P.

    1995-12-01

    Evidence and indications of sulphate reduction based on geological, hydrogeological, groundwater, isotope and microbial data gathered in and around the Aespoe Hard Rock Laboratory tunnel have been evaluated. This integrated investigation showed that sulphate reduction had taken place in the past but is most likely also an ongoing process. Anaerobic sulphate-reducing bacteria can live in marine sediments, in the tunnel sections under the sea and in deep groundwaters, since there is no access to oxygen. The sulphate-reducing bacteria seem to thrive when the Cl - concentration of the groundwater is 4000-6000 mg/l. Sulphate reduction is an in situ process but the resulting hydrogen-sulphide rich water can be transported to other locations. A more vigorous sulphate reduction takes place when the organic content in the groundwater is high (>10 mg/l DOC) which is the case in the sediments and in the groundwaters under the sea. Some bacteria use hydrogen as an electron donor instead of organic carbon and can therefore live in deep environments where access to organic material is limited. The sulphate-reducing bacteria seem to adapt to changing flow situations caused by the tunnel construction relatively fast. Sulphate reduction seems to have occurred and will probably occur where conditions are favourable for the sulphate-reducing bacteria such as anaerobic brackish groundwater with dissolved sulphate and organic carbon or hydrogen. 59 refs, 37 figs, 6 tabs

  6. Bacterial chromate reduction and product characterization

    International Nuclear Information System (INIS)

    Mehlhorn, R.J.; Buchanan, B.B.; Leighton, T.

    1992-11-01

    Bacillus subtilis reduced hexavalent chromate to trivalent chromium under either aerobic or anaerobic conditions. Reduction of CR(VI) and appearance of extracellular Cr(III) were demonstrated by electron spin resonance and spectrophotometry. Chromate reduction was stimulated more than five-fold by freeze-thawing, indicating that intracellular reductases or chemical reductants reduce chromate more rapidly than do intact cells. Moderately concentrated cells (10% pellet volume after centrifugation) reduced approximately 40 μM chromate/min (2 mg Cr/1-min) when exposed to 100 μM chromate (5 mg Cr/1). Highly concentrated cells (70% pellet volume) reduced more than 99.8% of 2 mM chromate (100 mg Cr/1) within 15 min. This rate of chromate reduction was of the same order of magnitude as the rate of respiration in aerobic cells. A substantial fraction of the reduction product (ca. 75%) was extracellular Cr(M), which could readily be separated from the cells by centrifugation. At high chromate concentrations, some fraction of reduced CR(VI) appeared to be taken up by cells, consistent with a detection of intracellular paramagnetic products. At low chromate concentrations, undefined growth medium alone reduced Cr(VI), but at a slow rate, relative to cells. Under appropriate conditions, B. subtilis appears to be an organism of choice for detoxifying chromate-contaminated soil and water

  7. Ultrasound guided reduction of childhood intussusception

    International Nuclear Information System (INIS)

    Yoon, Chong Hyun; Kim, Han Suk

    1986-01-01

    Following on from diagnosis using ultrasound, hydrostatic reduction using saline enema under ultrasound guidance was tried in 20 cases of childhood intussusception. The conclusions were as follows: 1. Success rates of saline enema under ultrasound guidance during a first-8 month period (P1) and a second-10 month period (P2) were 55.6% (5/9) and 54.5% (6/11) respectively. Average success rate was 55% (11/20). 2. During the periods of P1 and P2, no case was reduced by barium enema in 6 cases of failed reduction with saline enema. 3. During the period of P2, 5 cases of successful reduction with saline enema were confirmed by clinical follow-up without barium enema. 4. During the periods of P1 and P2, 9 cases of failed reduction with saline enema were operated, resulting in 6 cases of segmental resection and 3 cases of manual reduction. 5. The obvious advantages of this method are: 1. No radiation hazard. 2. No fear of barium peritonitis. 3. Detection of leading point. 6. With above results, this method could completely replace barium enema. And ultrasonography should be the initial study in the evaluation of intussusception in children and then if necessary, saline enema under ultrasound guidance should be done.

  8. A reductive aminase from Aspergillus oryzae

    Science.gov (United States)

    Aleku, Godwin A.; France, Scott P.; Man, Henry; Mangas-Sanchez, Juan; Montgomery, Sarah L.; Sharma, Mahima; Leipold, Friedemann; Hussain, Shahed; Grogan, Gideon; Turner, Nicholas J.

    2017-10-01

    Reductive amination is one of the most important methods for the synthesis of chiral amines. Here we report the discovery of an NADP(H)-dependent reductive aminase from Aspergillus oryzae (AspRedAm, Uniprot code Q2TW47) that can catalyse the reductive coupling of a broad set of carbonyl compounds with a variety of primary and secondary amines with up to >98% conversion and with up to >98% enantiomeric excess. In cases where both carbonyl and amine show high reactivity, it is possible to employ a 1:1 ratio of the substrates, forming amine products with up to 94% conversion. Steady-state kinetic studies establish that the enzyme is capable of catalysing imine formation as well as reduction. Crystal structures of AspRedAm in complex with NADP(H) and also with both NADP(H) and the pharmaceutical ingredient (R)-rasagiline are reported. We also demonstrate preparative scale reductive aminations with wild-type and Q240A variant biocatalysts displaying total turnover numbers of up to 32,000 and space time yields up to 3.73 g l-1 d-1.

  9. Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri▿ †

    Science.gov (United States)

    Li, Fuli; Hinderberger, Julia; Seedorf, Henning; Zhang, Jin; Buckel, Wolfgang; Thauer, Rudolf K.

    2008-01-01

    Cell extracts of butyrate-forming clostridia have been shown to catalyze acetyl-coenzyme A (acetyl-CoA)- and ferredoxin-dependent formation of H2 from NADH. It has been proposed that these bacteria contain an NADH:ferredoxin oxidoreductase which is allosterically regulated by acetyl-CoA. We report here that ferredoxin reduction with NADH in cell extracts from Clostridium kluyveri is catalyzed by the butyryl-CoA dehydrogenase/Etf complex and that the acetyl-CoA dependence previously observed is due to the fact that the cell extracts catalyze the reduction of acetyl-CoA with NADH via crotonyl-CoA to butyryl-CoA. The cytoplasmic butyryl-CoA dehydrogenase complex was purified and is shown to couple the endergonic reduction of ferredoxin (E0′ = −410 mV) with NADH (E0′ = −320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (E0′ = −10 mV) with NADH. The stoichiometry of the fully coupled reaction is extrapolated to be as follows: 2 NADH + 1 oxidized ferredoxin + 1 crotonyl-CoA = 2 NAD+ + 1 ferredoxin reduced by two electrons + 1 butyryl-CoA. The implications of this finding for the energy metabolism of butyrate-forming anaerobes are discussed in the accompanying paper. PMID:17993531

  10. Coupled ferredoxin and crotonyl coenzyme A (CoA) reduction with NADH catalyzed by the butyryl-CoA dehydrogenase/Etf complex from Clostridium kluyveri.

    Science.gov (United States)

    Li, Fuli; Hinderberger, Julia; Seedorf, Henning; Zhang, Jin; Buckel, Wolfgang; Thauer, Rudolf K

    2008-02-01

    Cell extracts of butyrate-forming clostridia have been shown to catalyze acetyl-coenzyme A (acetyl-CoA)- and ferredoxin-dependent formation of H2 from NADH. It has been proposed that these bacteria contain an NADH:ferredoxin oxidoreductase which is allosterically regulated by acetyl-CoA. We report here that ferredoxin reduction with NADH in cell extracts from Clostridium kluyveri is catalyzed by the butyryl-CoA dehydrogenase/Etf complex and that the acetyl-CoA dependence previously observed is due to the fact that the cell extracts catalyze the reduction of acetyl-CoA with NADH via crotonyl-CoA to butyryl-CoA. The cytoplasmic butyryl-CoA dehydrogenase complex was purified and is shown to couple the endergonic reduction of ferredoxin (E0' = -410 mV) with NADH (E0' = -320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (E0' = -10 mV) with NADH. The stoichiometry of the fully coupled reaction is extrapolated to be as follows: 2 NADH + 1 oxidized ferredoxin + 1 crotonyl-CoA = 2 NAD+ + 1 ferredoxin reduced by two electrons + 1 butyryl-CoA. The implications of this finding for the energy metabolism of butyrate-forming anaerobes are discussed in the accompanying paper.

  11. Sulfate reduction and methanogenesis at a freshwater

    DEFF Research Database (Denmark)

    Iversen, Vibeke Margrethe Nyvang; Andersen, Martin Søgaard; Jakobsen, Rasmus

    The freshwater-seawater interface was studied in a ~9-m thick anaerobic aquifer located in marine sand and gravel with thin peat lenses. Very limited amounts of iron-oxides are present. Consequently, the dominating redox processes are sulfate reduction and methanogenesis, and the groundwater...... is enriched in dissolved sulfide, methane and bicarbonate. Under normal conditions the seawater-freshwater interface is found at a depth of 4 m at the coastline and reaches the bottom of the aquifer 40 m inland. However, occasional flooding of the area occurs, introducing sulfate to the aquifer. Groundwater...... chemistry was studied in a 120 m transect perpendicular to the coast. Cores were taken for radiotracer rate measurements of sulfate reduction and methanogenesis. In the saline part of the aquifer 35 m inland, sulfate reduction was the dominant process with rates of 0.1-10 mM/year. In the freshwater part 100...

  12. Dose reduction at nuclear power plants

    International Nuclear Information System (INIS)

    Baum, J.W.; Dionne, B.J.

    1983-01-01

    The collective dose equivalent at nuclear power plants increased from 1250 rem in 1969 to nearly 54,000 rem in 1980. This rise is attributable primarily to an increase in nuclear generated power from 1289 MW-y to 29,155 MW-y; and secondly, to increased average plant age. However, considerable variation in exposure occurs from plant to plant depending on plant type, refueling, maintenance, etc. In order to understand the factors influencing these differences, an investigation was initiated to study dose-reduction techniques and effectiveness of as low as reasonably achievable (ALARA) planning at light water plants. Objectives are to: identify high-dose maintenance tasks and related dose-reduction techniques; investigate utilization of high-reliability, low-maintenance equipment; recommend improved radioactive waste handling equipment and procedures; examine incentives for dose reduction; and compile an ALARA handbook

  13. UniPOPS: Unified data reduction suite

    Science.gov (United States)

    Maddalena, Ronald J.; Garwood, Robert W.; Salter, Christopher J.; Stobie, Elizabeth B.; Cram, Thomas R.; Morgan, Lorrie; Vance, Bob; Hudson, Jerome

    2015-03-01

    UniPOPS, a suite of programs and utilities developed at the National Radio Astronomy Observatory (NRAO), reduced data from the observatory's single-dish telescopes: the Tucson 12-m, the Green Bank 140-ft, and archived data from the Green Bank 300-ft. The primary reduction programs, 'line' (for spectral-line reduction) and 'condar' (for continuum reduction), used the People-Oriented Parsing Service (POPS) as the command line interpreter. UniPOPS unified previous analysis packages and provided new capabilities; development of UniPOPS continued within the NRAO until 2004 when the 12-m was turned over to the Arizona Radio Observatory (ARO). The submitted code is version 3.5 from 2004, the last supported by the NRAO.

  14. Waste reduction at the Savannah River Site

    International Nuclear Information System (INIS)

    Stevens, W.E.; Lee, R.A.; Reynolds, R.W.

    1990-01-01

    The Savannah River Site (SRS) is a key installation for the production and research of nuclear materials for national defense and peace time applications and has been operating a full nuclear fuel cycle since the early 1950s. Wastes generated include high level radioactive, transuranic, low level radioactive, hazardous, mixed, sanitary, and aqueous wastes. Much progress has been made during the last several years to reduce these wastes including management systems, characterization, and technology programs. The reduction of wastes generated and the proper handling of the wastes have always been a part of the Site's operation. This paper summarizes the current status and future plans with respect to waste reduction to waste reduction and reviews some specific examples of successful activities

  15. Relativistic dynamical reduction models and nonlocality

    International Nuclear Information System (INIS)

    Ghirardi, G.C.; Grassi, R.

    1990-09-01

    We discuss some features of continuous dynamical models yielding state vector reduction and we briefly sketch some recent attempts to get a relativistic generalization of them. Within the relativistic context we analyze in detail the local an nonlocal features of the reduction mechanism and we investigate critically the possibility of attributing objective properties to individual systems in the micro and macroscopic cases. At the nonrelativistic level, two physically equivalent versions of continuous reduction mechanisms have been presented. However, only one of them can be taken as a starting point for the above considered relativistic generalization. By resorting to counterfactual arguments we show that the reason for this lies in the fact that the stochasticity involved in the two approaches has different conceptual implications. (author). 7 refs, 4 figs

  16. Tritium release reduction and radiolysis gas formation

    Energy Technology Data Exchange (ETDEWEB)

    Batifol, G.; Douche, Ch.; Sejournant, Ch. [CEA Valduc, 21 - Is-sur-Tille (France)

    2008-07-15

    At CEA Valduc, the usual tritiated waste container is the steel drum. It allows good release reduction performance for middle activity waste but in some cases tritium outgassing from the waste drums is too high. It was decided to over-package each drum in a tighter container called the over-drum. According to good safety practices it was also decided to measure gas composition evolution into the over-drum in order to defect hydrogen formation over time. After a few months, a significant release reduction was observed. Additionally there followed contamination reduction in the roof storage building rainwater. However hydrogen was also observed in some over-drums, in addition to other radiolysis products. Catalyst will be added to manage the hydrogen risk in the over-drums. (authors)

  17. Photochemical reduction of uranyl ion with triphenylphosphine

    International Nuclear Information System (INIS)

    Brar, A.S.; Sidhu, M.S.; Sandhu, S.S.

    1981-01-01

    Photochemical reduction of uranyl ion with triphenylphosphine has been studied in acetone-water medium in the presence of sulphuric acid at 346nm, 400nm and 434nm wavelengths. The photochemical reduction is of second order and increases with increase in hydrogen ion concentration. Absorption spectra of uranyl ion in acidic medium and uranyl ion with triphenylphosphine do not show any ground state complex formation. The value of quantum yield increases with the wavelength of the radiation increase from 346 to 434nm. Plots of reciprocal of quantum yield for the formation of U(IV) versus reciprocal [triphenylphosphine] are linear. Products characterized by UV and visible, IR and TLC show the formation of U(IV) and triphenylphosphine oxide. On the basis of above observations mechanism of the photochemical reduction has been proposed. (author)

  18. Proceedings: Instrumentation and control test reduction workshop

    International Nuclear Information System (INIS)

    1991-09-01

    Instrumentation and control (I ampersand C) surveillance and testing is a significant contributor to operations and management costs. Several techniques to eliminate or reduce manual testing requirements could reduce costs while improving plant safety and performance. I ampersand C test reduction was the subject of this 1991 workshop. The workshop covered test elimination, test reduction, test automation, and relevant standards and benefits. The conclusions of the workshop were the following: More utility information sharing is important. There is a significant amount of information available throughout the industry, but it is not available in a concise, useable form. An I ampersand C utility users group is needed to address items such as instrument calibration reduction, set-point methodologies, and other current I ampersand C issues. The workshop was well received. The timing is right to initiate actions to reduce testing

  19. MAC reduction of isoflurane by sufentanil.

    Science.gov (United States)

    Brunner, M D; Braithwaite, P; Jhaveri, R; McEwan, A I; Goodman, D K; Smith, L R; Glass, P S

    1994-01-01

    We have shown previously that a plasma fentanyl concentration of 1.67 ng ml-1 reduced the MAC of isoflurane by 50%. By comparing equal degrees of MAC reduction by sufentanil, we may determine the potency ratio of these opioids. Seventy-six patients were allocated randomly to receive predetermined infusions of sufentanil, and end-tidal concentrations of isoflurane in oxygen. Blood samples were obtained 10 min after the start of the infusion, and just before and after skin incision. Any purposeful movement by the patient was recorded. The MAC reduction of isoflurane produced by sufentanil was obtained using a logistic regression model. A sufentanil plasma concentration of 0.145 ng ml-1 (95% confidence limits 0.04, 0.26 ng ml-1) resulted in a 50% reduction in the MAC of isoflurane. At a plasma concentration greater than 0.5 ng ml-1, sufentanil exhibited a ceiling effect.

  20. Hanford Site annual waste reduction report

    International Nuclear Information System (INIS)

    Nichols, D.H.

    1992-03-01

    The US Department of Energy (DOE), Richland Field Office (RL) has developed and implemented a Hanford Site Waste Minimization and Pollution Prevention Awareness Plan that provides overall guidance and direction on waste minimization and pollution prevention awareness to the four contractors who manage and operate the Hanford Site for the RL. Waste reduction at the RL will be accomplished by following a hierarchy of environmental protection practices. First, waste generation will be eliminated or minimized through source reduction. Second, potential waste materials that cannot be eliminated or minimized will be recycled (i.e., used, reused, or reclaimed). Third, all waste that is nevertheless generated will be treated to reduce volume, toxicity, or mobility before storage or disposal. The scope of this waste reduction program will include nonhazardous, hazardous, radioactive mixed, and radioactive wastes

  1. Optimal reduction of humus in demineralization

    International Nuclear Information System (INIS)

    Persson, F.

    1989-04-01

    To have an optimal reduction of organic substance and colloids in a demineralization plant the following ought to be observed. * At least two anion exchangers should be in series. The firs one being either a weak macroporous polystyrene anion exchanger or a weak polyacrylic anion exchanger. A third anion exchanger in series improves the reduction only marginally. * The leakage of organic substance and colloids increases rapidly at the same time or before the leakage of anions. The anion exchangers in a plant should therefore have a higher capacity than the cation exchangers. If the anion exchangers do not have a higher capacity than the cation exchangers only 90-95 % of the capacity shall be used. * The filtration rates have normally no influence of the reduction organic of substance. Sometime a low filtration rate gives a better reduction of colloids. * The content of organic substance in the water to the plants has a great effect on the capacity for ions. At high content of organic substance (20 mg KMnO 4 ) the capacity for ions can be reduced with 30-40 %. * Different technics for regenerations does not seem to have any influence on the reduction of organic substances and colloids. Neither age of the anion exchangers nor washing with solutions of sodium chloride seems to have any influence on the reduction. Age and organic contamination have mainly an influence on the capacity per regeneration. At all demineralization plants some organic substances and colloids leak through the plant, the quantities depending on the colloids. To remove this organic substances and colloids the ion exchangers must be completed with for instance flocculation or reverse osmosis. (L.E.)

  2. Reduction of Social Inequality in High School

    DEFF Research Database (Denmark)

    Jensen, Ulla Højmark

    2014-01-01

    This article explores structures in the learning environment at the classroom level that can contribute to reduction of social inequality in education. It draws on qualitative observation studies of Latino’s in high schools in New York City, USA, by a Danish researcher. The purpose of this article...... is to explore ‘good examples’ from an outsider’s perspective and there by create an empirical and theoretical focus on how school characteristics and structures cross boarders are connected to the reduction of social inequality in education....

  3. Reduction of radiation area project plan

    International Nuclear Information System (INIS)

    1979-08-01

    This plan deals with the overall reduction of outdoor surface radiation areas under Rockwell's jurisdiction. Four basic alternatives are identified which will reduce and/or stabilize radiation areas until long-term disposal decisions are made: (1) continued routine surveillance and maintenance; (2) reduction or elimination of effluent discharges; (3) improved site stabilization; and (4) site removal. The four major transport mechanisms at Hanford that are the primary forces for contamination spread are identified as wind, animal transport, concentration and dispersal by plants, and transport resulting from human activities

  4. Low-Cost Radon Reduction Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    Rose, William B. [Partnership for Advanced Residential Retrofit, Champaign, IL (United States); Francisco, Paul W. [Partnership for Advanced Residential Retrofit, Champaign, IL (United States); Merrin, Zachary [Partnership for Advanced Residential Retrofit, Champaign, IL (United States)

    2015-09-01

    The aim of the research was to conduct a primary scoping study on the impact of air sealing between the foundation and the living space on radon transport reduction across the foundation-living space floor assembly. Fifteen homes in the Champaign, Illinois area participated in the study. These homes were instrumented for hourly continuous radon measurements and simultaneous temperature and humidity the foundation was improved. However, this improved isolation did not lead to significant reductions in radon concentration in the living space. Other factors such as outdoor temperature were shown to have an impact on radon concentration.

  5. Large Scale Reduction of Graphite Oxide Project

    Science.gov (United States)

    Calle, Carlos; Mackey, Paul; Falker, John; Zeitlin, Nancy

    2015-01-01

    This project seeks to develop an optical method to reduce graphite oxide into graphene efficiently and in larger formats than currently available. Current reduction methods are expensive, time-consuming or restricted to small, limited formats. Graphene has potential uses in ultracapacitors, energy storage, solar cells, flexible and light-weight circuits, touch screens, and chemical sensors. In addition, graphite oxide is a sustainable material that can be produced from any form of carbon, making this method environmentally friendly and adaptable for in-situ reduction.

  6. Advanced digital signal processing and noise reduction

    CERN Document Server

    Vaseghi, Saeed V

    2008-01-01

    Digital signal processing plays a central role in the development of modern communication and information processing systems. The theory and application of signal processing is concerned with the identification, modelling and utilisation of patterns and structures in a signal process. The observation signals are often distorted, incomplete and noisy and therefore noise reduction, the removal of channel distortion, and replacement of lost samples are important parts of a signal processing system. The fourth edition of Advanced Digital Signal Processing and Noise Reduction updates an

  7. Reduction of UF4 to U metal

    International Nuclear Information System (INIS)

    Suh, I.S.; Kim, J.H.; Min, B.T.; Whang, S.C.; Im, K.S.

    1983-01-01

    The operating conditions for the production of uranium metal by reduction of UFsub(4) with magnesium powder have been thoroughly investigated using the reactor 1 Kg nominal capacity. UFsub(4) powders which were produced from the conversion plant in KAERI are used and MgFsub(2), by-product of the reduction, are used as liner after pulverizing. 95% of average yield of uranium metal are obtained with 6% excess of magnesium powder in size of -πo + 50 mesh and its density is 18.5 g/cc, and furthermore the yield is increased when mafnesium powders are used after washed with trichloro-ethylene and dried. (Author)

  8. Reductive methods for isotopic labeling of antibiotics

    International Nuclear Information System (INIS)

    Champney, W.S.

    1989-01-01

    Methods for the reductive methylation of the amino groups of eight different antibiotics using 3 HCOH or H 14 COH are presented. The reductive labeling of an additional seven antibiotics by NaB 3 H 4 is also described. The specific activity of the methyl-labeled drugs was determined by a phosphocellulose paper binding assay. Two quantitative assays for these compounds based on the reactivity of the antibiotic amino groups with fluorescamine and of the aldehyde and ketone groups with 2,4-dinitrophenylhydrazine are also presented. Data on the cellular uptake and ribosome binding of these labeled compounds are also presented

  9. Roasting of sulphide using carbothermal reduction

    OpenAIRE

    Orozco, Ivana Marcela; Bazan, Vanesa Lucia; Diaz, Andrea Alejandra; Lara, Rodolfo Francisco

    2016-01-01

    The carbothermic reduction process is a direct reduction of sulfides. It allows a roasting in which higher concentrations of metals such as molybdenum are obtained by using both a reducing agent (in this case, carbon C) and a sulfur scavenger, such as CaO so as to prevent air toxic gases pollution such as SO2. In this paper, we analyze sulfur concentrates rich in copper, iron, and molybdenum that are obtained through rougher flotation and differential floats, which give rise to different laws...

  10. Noise reduction in the beam current monitor

    International Nuclear Information System (INIS)

    Arai, Shigeaki.

    1982-02-01

    A simple noise reduction system using a pulse transformer and a pair of L C low pass filters has been introduced to the beam current monitor of a current transformer type at the INS electron linac. With this system, the pick-up noise has been reduced to be 1% of the noise without noise reduction. Signal deformation caused by this system is relatively small and the beam current pulse down to 20 mA is successfully monitored in the actual accelerator operation. (author)

  11. Spontaneous reduction of prolactinoma post cabergoline withdrawal

    Directory of Open Access Journals (Sweden)

    Sampath Kumar Venkatesh

    2012-01-01

    Full Text Available Prolactinomas are common pituitary tumors usually highly responsive to dopamine agonists. Around 70-90% of the prolactinomas exhibit decrease in tumor size, though variably with these agents. Uncommonly, there may be little or no shrinkage in pituitary tumor. In the absence of medical therapy, pituitary apoplexy may also result in tumor shrinkage, albeit rarely. We report here a case showing only modest reduction in prolactinoma with cabergoline given for a period of one and a half years. Surprisingly, this tumor showed a 40% reduction in the tumor size 3 months after cabergoline withdrawal in the absence of clinical or radiological evidence of apoplexy.

  12. Drag Reduction by Leidenfrost Vapor Layers

    KAUST Repository

    Vakarelski, Ivan Uriev

    2011-05-23

    We demonstrate and quantify a highly effective drag reduction technique that exploits the Leidenfrost effect to create a continuous and robust lubricating vapor layer on the surface of a heated solid sphere moving in a liquid. Using high-speed video, we show that such vapor layers can reduce the hydrodynamic drag by over 85%. These results appear to approach the ultimate limit of drag reduction possible by different methods based on gas-layer lubrication and can stimulate the development of related energy saving technologies.

  13. Dimensional reduction of a generalized flux problem

    International Nuclear Information System (INIS)

    Moroz, A.

    1992-01-01

    In this paper, a generalized flux problem with Abelian and non-Abelian fluxes is considered. In the Abelian case we shall show that the generalized flux problem for tight-binding models of noninteracting electrons on either 2n- or (2n + 1)-dimensional lattice can always be reduced to an n-dimensional hopping problem. A residual freedom in this reduction enables one to identify equivalence classes of hopping Hamiltonians which have the same spectrum. In the non-Abelian case, the reduction is not possible in general unless the flux tensor factorizes into an Abelian one times are element of the corresponding algebra

  14. Steven's orbital reduction factor in ionic clusters

    Science.gov (United States)

    Gajek, Z.; Mulak, J.

    1985-11-01

    General expressions for reduction coefficients of matrix elements of angular momentum operator in ionic clusters or molecular systems have been derived. The reduction in this approach results from overlap and covalency effects and plays an important role in the reconciling of magnetic and spectroscopic experimental data. The formulated expressions make possible a phenomenological description of the effect with two independent parameters for typical equidistant clusters. Some detailed calculations also suggest the possibility of a one-parameter description. The results of these calculations for some ionic uranium compounds are presented as an example.

  15. Transient burnout in flow reduction condition

    International Nuclear Information System (INIS)

    Iwamura, Takamichi; Kuroyanagi, Toshiyuki

    1981-01-01

    A transient flow reduction burnout experiment was conducted with water in a uniformly heated, vertically oriented tube. Test pressures ranged from 0.5 to 3.9 MPa. An analytical method was developed to obtain transient burnout conditions at the exit. A simple correlation to predict the deviation of the transient burnout mass velocity at the tube exit from the steady state mass velocity obtained as a function of steam-water density ratio and flow reduction rate. The correlation was also compared with the other data. (author)

  16. Strategies for regular segmented reductions on GPU

    DEFF Research Database (Denmark)

    Larsen, Rasmus Wriedt; Henriksen, Troels

    2017-01-01

    We present and evaluate an implementation technique for regular segmented reductions on GPUs. Existing techniques tend to be either consistent in performance but relatively inefficient in absolute terms, or optimised for specific workloads and thereby exhibiting bad performance for certain input...... is in the context of the Futhark compiler, the implementation technique is applicable to any library or language that has a need for segmented reductions. We evaluate the technique on four microbenchmarks, two of which we also compare to implementations in the CUB library for GPU programming, as well as on two...

  17. Bohm`s theory versus dynamical reduction

    Energy Technology Data Exchange (ETDEWEB)

    Ghirardi, G C [International Centre for Theoretical Physics, Trieste (Italy); Grassi, R [Udine Univ., Udine (Italy). Dept. of Civil Engineering

    1995-10-01

    This essay begins with a comparison between Bohm`s theory and the dynamical reduction program. While there are similarities (e.g., the preferred basis), there are also important differences (e.g., the type of nonlocality or of Lorentz invariance). In particular, it is made plausible that theories which exhibit parameter dependence effects cannot be ``genuinely Lorentz invariant``. For the two approaches under consideration, this analysis provides a comparison that can produce a richer understanding both of the pilot wave and of the dynamical reduction mechanism. (author). 33 refs, 1 fig.

  18. Exploring the reductive capacity of Pyrococcus furiosus : the reduction of carboxylic acids and pyridine nucleotides

    NARCIS (Netherlands)

    Ban, van den E.C.D.

    2001-01-01

    This Ph.D. project started in 1997 and its main goal was to obtain insight in the reductive capacity of the hyperthermophilic archaeon Pyrococcus furiosus . The research was focused on the biocatalytic reduction of carboxylic

  19. Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study

    Energy Technology Data Exchange (ETDEWEB)

    Pinakidou, Fani; Kaprara, Efthimia [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Katsikini, Maria; Paloura, Eleni C.; Simeonidis, Konstantinos [Aristotle University of Thessaloniki, School of Physics, Department of Solid State Physics, 54124 Thessaloniki (Greece); Mitrakas, Manassis, E-mail: manasis@eng.auth.gr [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece)

    2016-05-01

    The feasibility of implementing a Sn(II) oxy-hydroxide (Sn{sub 6}O{sub 4}(OH){sub 4}) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn{sub 6}O{sub 4}(OH){sub 4} for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn{sub 6}O{sub 4}(OH){sub 4} can decrease Cr(VI) concentration below the upcoming regulation limit of 10 μg/L for drinking water. Moreover, an uptake capacity of 7.2 μg/mg at breakthrough concentration of 10 μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH){sub 3} precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO{sub 2}, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ({sup 2}C) and monodentate ({sup 1}V) geometries, at the expense of the present bidentate mononuclear ({sup 2}E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn{sub 6}O{sub 4}(OH){sub 4} in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the {sup 2}C and {sup 1}V configurations, which enhances the safe disposal of spent adsorbents. - Highlights: • Effective Cr(VI) removal from drinking water by Sn{sub 6}O{sub 4}(OH){sub 4} • Sn{sub 6}O{sub 4}(OH){sub 4} transformation to SnO{sub 2} after Cr

  20. Improved availability through reduction in rework

    International Nuclear Information System (INIS)

    Grosswald, M.; Lowman, J.

    1985-01-01

    The Florida Power and Light Company Quality Improvement Rework Identification Program is discussed. Establishment of the Quality Improvement Rework Identification Task Team, goals, and methods of the program are noted. Resulting from the program are reductions in failure frequency and positive incentives from a teamwork approach

  1. Waste reduction through consumer education. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, E.Z.

    1996-05-01

    The Waste Reduction through Consumer Education research project was conducted to determine how environmental educational strategies influence purchasing behavior in the supermarket. The objectives were to develop, demonstrate, and evaluate consumer education strategies for waste reduction. The amount of waste generated by packaging size and form, with an adjustment for local recyclability of waste, was determined for 14 product categories identified as having more waste generating and less waste generating product choices (a total of 484 products). Using supermarket scan data and shopper identification numbers, the research tracked the purchases of shoppers in groups receiving different education treatments for 9 months. Statistical tests applied to the purchase data assessed patterns of change between the groups by treatment period. Analysis of the data revealed few meaningful statistical differences between study groups or changes in behavior over time. Findings suggest that broad brush consumer education about waste reduction is not effective in changing purchasing behaviors in the short term. However, it may help create a general awareness of the issues surrounding excess packaging and consumer responsibility. The study concludes that the answer to waste reduction in the future may be a combination of voluntary initiatives by manufacturers and retailers, governmental intervention, and better-informed consumers.

  2. Stray light reduction for Thomson scattering

    NARCIS (Netherlands)

    Bakker, L.P.; Kroesen, G.M.W.; Doebele, H.F.; Muraoka, K.

    1999-01-01

    In order to perform Thomson scattering in a gas discharge tube, the reduction of stray light is very important because of the very small Thomson cross-section. By introducing a sodium absorption cell as a notch filter, we can reduce the measured stray light considerably. Then we have to use a dye

  3. Robotic system for glovebox size reduction

    International Nuclear Information System (INIS)

    KWOK, KWAN S.; MCDONALD, MICHAEL J.

    2000-01-01

    The Intelligent Systems and Robotics Center (ISRC) at Sandia National Laboratories (SNL) is developing technologies for glovebox size reduction in the DOE nuclear complex. A study was performed for Kaiser-Hill (KH) at the Rocky Flats Environmental Technology Site (RFETS) on the available technologies for size reducing the glovebox lines that require size reduction in place. Currently, the baseline approach to these glovebox lines is manual operations using conventional mechanical cutting methods. The study has been completed and resulted in a concept of the robotic system for in-situ size reduction. The concept makes use of commercially available robots that are used in the automotive industry. The commercially available industrial robots provide high reliability and availability that are required for environmental remediation in the DOE complex. Additionally, the costs of commercial robots are about one-fourth that of the custom made robots for environmental remediation. The reason for the lower costs and the higher reliability is that there are thousands of commercial robots made annually, whereas there are only a few custom robots made for environmental remediation every year. This paper will describe the engineering analysis approach used in the design of the robotic system for glovebox size reduction

  4. Central subspace dimensionality reduction using covariance operators.

    Science.gov (United States)

    Kim, Minyoung; Pavlovic, Vladimir

    2011-04-01

    We consider the task of dimensionality reduction informed by real-valued multivariate labels. The problem is often treated as Dimensionality Reduction for Regression (DRR), whose goal is to find a low-dimensional representation, the central subspace, of the input data that preserves the statistical correlation with the targets. A class of DRR methods exploits the notion of inverse regression (IR) to discover central subspaces. Whereas most existing IR techniques rely on explicit output space slicing, we propose a novel method called the Covariance Operator Inverse Regression (COIR) that generalizes IR to nonlinear input/output spaces without explicit target slicing. COIR's unique properties make DRR applicable to problem domains with high-dimensional output data corrupted by potentially significant amounts of noise. Unlike recent kernel dimensionality reduction methods that employ iterative nonconvex optimization, COIR yields a closed-form solution. We also establish the link between COIR, other DRR techniques, and popular supervised dimensionality reduction methods, including canonical correlation analysis and linear discriminant analysis. We then extend COIR to semi-supervised settings where many of the input points lack their labels. We demonstrate the benefits of COIR on several important regression problems in both fully supervised and semi-supervised settings.

  5. Logistics Reduction Technologies for Exploration Missions

    Science.gov (United States)

    Broyan, James L., Jr.; Ewert, Michael K.; Fink, Patrick W.

    2014-01-01

    Human exploration missions under study are limited by the launch mass capacity of existing and planned launch vehicles. The logistical mass of crew items is typically considered separate from the vehicle structure, habitat outfitting, and life support systems. Although mass is typically the focus of exploration missions, due to its strong impact on launch vehicle and habitable volume for the crew, logistics volume also needs to be considered. NASA's Advanced Exploration Systems (AES) Logistics Reduction and Repurposing (LRR) Project is developing six logistics technologies guided by a systems engineering cradle-to-grave approach to enable after-use crew items to augment vehicle systems. Specifically, AES LRR is investigating the direct reduction of clothing mass, the repurposing of logistical packaging, the use of autonomous logistics management technologies, the processing of spent crew items to benefit radiation shielding and water recovery, and the conversion of trash to propulsion gases. Reduction of mass has a corresponding and significant impact to logistical volume. The reduction of logistical volume can reduce the overall pressurized vehicle mass directly, or indirectly benefit the mission by allowing for an increase in habitable volume during the mission. The systematic implementation of these types of technologies will increase launch mass efficiency by enabling items to be used for secondary purposes and improve the habitability of the vehicle as mission durations increase. Early studies have shown that the use of advanced logistics technologies can save approximately 20 m(sup 3) of volume during transit alone for a six-person Mars conjunction class mission.

  6. Evaluating a Health Risk Reduction Program.

    Science.gov (United States)

    Nagelberg, Daniel B.

    1981-01-01

    A health risk reduction program at Bowling Green State University (Ohio) tested the efficacy of peer education against the efficacy of returning (by mail) health questionnaire results. A peer health education program did not appear to be effective in changing student attitudes or lifestyles; however, the research methodology may not have been…

  7. Active sound reduction system and method

    NARCIS (Netherlands)

    2016-01-01

    The present invention refers to an active sound reduction system and method for attenuation of sound emitted by a primary sound source, especially for attenuation of snoring sounds emitted by a human being. This system comprises a primary sound source, at least one speaker as a secondary sound

  8. Multiple cost criteria for occupational dose reduction

    International Nuclear Information System (INIS)

    James, J.Z.

    1983-01-01

    This paper describes a simple, feasible procedure for deciding if a proposed dose reduction measure is justified under ALARA, based on engineering economic principles of project feasibility analysis. Particular attention is given to the fixing of cost criteria: the importance of melding disparate objectives into a single parameter, and the distinction between a cost criterion and a cost consideration. (author)

  9. Personal Approaches to Stress Reduction: A Workshop.

    Science.gov (United States)

    Remer, Rory

    1984-01-01

    Seven topic areas which may be variously combined to comprise a workshop in personal stress reduction are outlined. They include definitions and types of stress, life style planning, nutrition, exercise, networking/social support system, relaxation and other trophotropic interventions, and communication skills. Suggestions are included for…

  10. Breast Hypertrophy, Reduction Mammaplasty, and Body Image.

    Science.gov (United States)

    Fonseca, Cristiane Costa; Veiga, Daniela Francescato; Garcia, Edgard da Silva; Cabral, Isaías Vieira; de Carvalho, Monique Maçais; de Brito, Maria José Azevedo; Ferreira, Lydia Masako

    2018-02-07

    Body image dissatisfaction is one of the major factors that motivate patients to undergo plastic surgery. However, few studies have associated body satisfaction with reduction mammaplasty. The aim of this study was to evaluate the impact of breast hypertrophy and reduction mammaplasty on body image. Breast hypertrophy patients, with reduction mammaplasty already scheduled between June 2013 and December 2015 (mammaplasty group, MG), were prospectively evaluated through the body dysmorphic disorder examination (BDDE), body investment scale (BIS), and breast evaluation questionnaire (BEQ55) tools. Women with normal-sized breasts were also evaluated as study controls (normal-sized breast group, NSBG). All the participants were interviewed at the initial assessment and after six months. Data were analyzed before and after six months. Each group consisted of 103 women. The MG group had a significant improvement in BDDE, BIS, and BEQ55 scores six months postoperatively (P ≤ 0.001 for the three instruments), whereas the NSBG group showed no alteration in results over time (P = 0.876; P = 0.442; and P = 0.184, respectively). In the intergroup comparison it was observed that the MG group began to invest more in the body, similarly to the NSBG group, and surpassed the level of satisfaction and body image that the women of the NSBG group had after the surgery. Reduction mammaplasty promoted improvement in body image of women with breast hypertrophy. © 2018 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com

  11. Green reduction of graphene oxide using alanine

    International Nuclear Information System (INIS)

    Wang, Jiabin; Salihi, Elif Caliskan; Šiller, Lidija

    2017-01-01

    There remains a real need for the easy, eco-friendly and scalable preparation method of graphene due to various potential applications. Chemical reduction is the most versatile method for the large scale production of graphene. Here we report the operating conditions for a one-step, economical and green synthesis method for the reduction of graphene oxide using a biomolecule (alanine). Graphene oxide was produced by the oxidation and exfoliation of natural graphite flake with strong oxidants using Hummers method (Hummers and Offeman, 1958), but the method was revised in our laboratory to set up a safe and environmentally friendly route. The reduction of graphene oxide was investigated using alanine at various operating conditions in order to set up optimum conditions (treatment time, temperature and concentration of the reagent). Samples have been characterized by using UV–Visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectroscopy and X-ray diffraction analysis. - Highlights: • An environmentally friendly route was reported for the chemical reduction of graphene oxide (GO). • Alanine could reduce GO to rGO (reduced graphene oxide) without using any stabilizer or alcaline medium. • Characterization studies confirmed the successful deoxygenation of GO.

  12. Are Reductions in Population Sodium Intake Achievable?

    Directory of Open Access Journals (Sweden)

    Jessica L. Levings

    2014-10-01

    Full Text Available The vast majority of Americans consume too much sodium, primarily from packaged and restaurant foods. The evidence linking sodium intake with direct health outcomes indicates a positive relationship between higher levels of sodium intake and cardiovascular disease risk, consistent with the relationship between sodium intake and blood pressure. Despite communication and educational efforts focused on lowering sodium intake over the last three decades data suggest average US sodium intake has remained remarkably elevated, leading some to argue that current sodium guidelines are unattainable. The IOM in 2010 recommended gradual reductions in the sodium content of packaged and restaurant foods as a primary strategy to reduce US sodium intake, and research since that time suggests gradual, downward shifts in mean population sodium intake are achievable and can move the population toward current sodium intake guidelines. The current paper reviews recent evidence indicating: (1 significant reductions in mean population sodium intake can be achieved with gradual sodium reduction in the food supply, (2 gradual sodium reduction in certain cases can be achieved without a noticeable change in taste or consumption of specific products, and (3 lowering mean population sodium intake can move us toward meeting the current individual guidelines for sodium intake.

  13. Reduction of Double Clausenian Hypergeometric Functions

    DEFF Research Database (Denmark)

    Karlsson, Per W.

    1996-01-01

    The reduction formulas under consideration are those for which the conditions upon the variables are other than 'fixed values'. Known results are discussed, and some new formulas are derived by series manipulations from various known summation and transformation theorems. The ten functions in thi...

  14. Chromium tolerance and reduction potential of Staphylococci ...

    African Journals Online (AJOL)

    In order to study the microbiology of chromium tolerance and reduction at a fly ash dumping site in South Africa, 15 core samples were investigated. It was shown that the 30 year old dumping site exhibited high concentrations of Cr (VI) ranging from 1.6 to 9.6 mg/g. From this contaminated fly ash dumping site, 67 chromium ...

  15. Interferometric crosstalk reduction by phase scrambling

    NARCIS (Netherlands)

    Tafur Monroy, I.; Tangdiongga, E.; Jonker, R.J.W.; Waardt, de H.

    2000-01-01

    Interferometric crosstalk, arising from the detection of undesired signals at the same nominal wavelength, may introduce large power penalties and bit-error rate (BER) floor significantly restricting the scalability of optical networks. In this paper, interferometric crosstalk reduction in optical

  16. Three Extensions to Subtractive Crosstalk Reduction

    NARCIS (Netherlands)

    F.A. Smit (Ferdi); R. van Liere (Robert); B. Fröhlich (Bernd)

    2007-01-01

    textabstractStereo displays suffer from crosstalk, an effect that reduces or even inhibits the viewer's ability to correctly perceive depth. Previous work on software crosstalk reduction focussed on the preprocessing of static scenes which are viewed from a fixed viewpoint. However, in virtual

  17. 50 CFR 600.1012 - Reduction loan.

    Science.gov (United States)

    2010-10-01

    ... annual rate, that shall be determined by subsequent events, of simple interest on the reduction loan's... deposit and disburse the fee revenue in accordance with § 600.1014. (b) Principal amount, interest rate... § 600.1014. (c) Effect of prospective interest rate. Any difference between a prospective interest rate...

  18. Anaerobic reductive dehalogenation of polychlorinated dioxins

    Energy Technology Data Exchange (ETDEWEB)

    Bunge, Michael [Aarhus Univ. (DK). Dept. of Biological Sciences, Microbiology, and Interdisciplinary Nanoscience Centre (iNANO); Lechner, Ute [Halle-Wittenberg Univ., Halle (Germany). Inst. of Biology/Microbiology

    2009-09-15

    Polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) are among the most harmful environmental contaminants. Their widespread distribution due to unintentional or unknown release coincides with environmental persistence, acute and chronic toxicity to living organisms, and long-term effects due to the compounds' tendency for bioaccumulation and biomagnification. While microbial aerobic degradation of PCDD/Fs is mainly reported for the turnover of low chlorinated congeners, this review focuses on anaerobic reductive dehalogenation, which may constitute a potential remediation strategy for polychlorinated compounds in soils and sediments. Microorganisms in sediments and in microcosms or enrichment cultures have been shown to be involved in the reductive dechlorination of dioxins. Bacteria related to the genus Dehalococcoides are capable of the reductive transformation of dioxins leading to lower chlorinated dioxins including di- and monochlorinated congeners. Thus, reductive dehalogenation might be one of the very few mechanisms able to mediate the turnover of polychlorinated dioxins by reducing their toxicity and paving the way for a subsequent breakdown of the carbon skeleton. (orig.)

  19. Electrocatalytic carbon dioxide reduction - a mechanistic study

    NARCIS (Netherlands)

    Schouten, Klaas Jan Schouten

    2013-01-01

    This thesis presents new insights into the reduction of carbon dioxide to methane and ethylene on copper electrodes. This electrochemical process has great potential for the storage of surplus renewable electrical energy in the form of hydrocarbons. The research described in this thesis focuses on

  20. Accounting for Natural Reduction of Nitrogen

    DEFF Research Database (Denmark)

    Højberg, A L; Refsgaard, J. C.; Hansen, A.L.

    the same restriction for all areas independent on drainage schemes, hydrogeochemical conditions in the subsurface and retention in surface waters. Although significant reductions have been achieved this way, general measures are not cost-effective, as nitrogen retention (primarily as denitrification...