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AbstractAbstract
[en] A highly simple and effective new methodology has been proposed to analyze the reaction kinetics of non-equilibrium mass transport. Interphase mass transfer in an evidently non-ideal liquid system has been described as trajectories on a reaction plane by introducing a logarithmic driving force LG which equals to A+/RT, where A+ is newly defined chemical affinity of a solute. The affinity A+ is referenced not only to the reaction state but to the equilibrium state, and is different from the De Donder's affinity defined solely by a reaction state. The affinity A+ is always smaller than the conventional one. It has also been concluded that extractive transfer might occur in a region A+>0. This description of transfer phenomena enables us to treat the reactions directly without the knowledge of rigorous activities of solutes, and is independent to the selection of concentration scale as well as the reference systems for chemical potentials. The affinity A+, i.e. the upper limit of the reaction trajectories, and the rate of the decrease in the logarithmic driving force have been represented by A+ ≅ -RTlnξ and -dLG/dξ=1/ξ using the degree of advancement ξ. Consequently, the thermodynamic analysis of reaction trajectories gave insights about the reaction kinetics and its characteristics for two phase systems containing multi-solutes. (author)
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Journal Article
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Journal of Nuclear Science and Technology (Tokyo); ISSN 0022-3131;
; CODEN JNSTAX; v. 31(10); p. 1084-1091

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AbstractAbstract
No abstract available
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Source
National Council for Research and Development, Jerusalem (Israel); Israel Atomic Energy Commission, Beersheba. Nuclear Research Center-Negev; Ben-Gurion Univ. of the Negev, Beersheba (Israel); 45 p; nd; p. 44; International workshop on plasma chemistry in technology; Ashqelon, Israel; 30 Mar - 1 Apr 1981; Published in summary form only.
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Miscellaneous
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AbstractAbstract
[en] Positronium (Ps) reaction rates (κ) with weak Acceptors (Ac) leading to the formation of Ps-Ac complexes show several intriguing features: non-monotonic temperature dependence of κ (departing from the usual Arrhenius paradigm), considerable variability of κ with respect to different solvents, and anomalies in response to external pressure at ambient temperature (large changes of κ in some media and hardly any in others). We explain all these phenomena, introducing the novel concept of a critical surface tension, which unifies observations in diverse non-polar solvents at different temperatures and pressures
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S0969806X01005801; Copyright (c) 2002 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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Johnson, Ron; Nunes, Filomena, E-mail: r.johnson@surrey.ac.uk
AbstractAbstract
No abstract available
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Available from http://dx.doi.org/10.1088/0954-3899/41/9/090301; Abstract only; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
Journal
Journal of Physics. G, Nuclear and Particle Physics; ISSN 0954-3899;
; CODEN JPGPED; v. 41(9); [2 p.]

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Weiss, M.S.
Lawrence Livermore National Lab., CA (USA)
Lawrence Livermore National Lab., CA (USA)
AbstractAbstract
[en] Some TDHF applications are addressed that are somewhat subtler than just crashing nuclei together and looking at large chunks of nuclear material. I will also attempt to address some of the technical problems of doing TDHF and also point out some areas where work remains to be done. Topics include promptly emitted particles, large amplitude RPA, and exciting giant resonances in heavy ion collisions. 19 references
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17 May 1984; 23 p; Winter school on fundamental nuclear physics; Trieste (Italy); 11 Mar - 13 Apr 1984; CONF-8403126--1; Available from NTIS, PC A02/MF A01; 1 as DE84012319
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Report
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Ravoire, Jean
CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Genie Isotopique
CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Genie Isotopique
AbstractAbstract
[en] In the first part, some definitions and the thermodynamic and kinetic isotopic effect concepts are recalled. In the second part the kinetic laws are established, in homogeneous and heterogeneous medium (one component being on occasions present in both phases), without and with isotopic effects. Emphasis is put on application to separation of isotopes, the separation factor α being close to 1, one isotope being in large excess with respect to the other one. Isotopic transfer is then given by: J = Ka (x - y/α) where x and y are the (isotopic) mole fractions in both phases, Ka may be either the rate of exchange or a transfer coefficient which can be considered as the 'same in both ways' if α-1 is small compared to the relative error on the measure of Ka. The third part is devoted to isotopic exchange reactors. Relationships between their efficiency and kinetics are established in some simple cases: plug cocurrent flow reactors, perfectly mixed reactors, countercurrent reactors without axial mixing. We treat only cases where α and the up flow to down flow ratio is close to 1 so that Murphee efficiency approximately overall efficiency (discrete stage contactors). HTU (phase 1) approximately HTU (phase 2) approximately HETP (columns). In a fourth part, an expression of the isotopic separative power of reactors is proposed and discussed
[fr]
Dans une premiere partie, on rappelle quelques definitions et les notions d'effets isotopiques thermodynamique et cinetique. La deuxieme partie est consacree a l'etablissement des lois cinetiques, en milieu homogene et en milieu heterogene (avec eventuellement un compose present dans deux phases), en l'absence et en presence d'effets isotopiques. L'accent est mis sur l'application a la separation isotopique, avec le facteur de separation α voisin de 1, un isotope etant en grand exces par rapport a l'autre. Le transfert isotopique est alors donne par: J = Ka (x - y/α) ou x et y sont les fractions molaires (isotopiques) dans les deux phases, Ka est indifferemment une vitesse d'echange ou un coefficient de transfert qui peut etre considere comme le 'meme dans les deux sens' si α - 1 est petit devant l'erreur relative commise dans la mesure de Ka. La troisieme partie est consacree aux reacteurs d'echange isotopique. Les relations entre leur efficacite et les grandeurs cinetiques sont etablies dans des cas simples: reacteurs co-courant avec ecoulement piston, reacteurs parfaitement agites, reacteurs tubulaires avec ecoulement a contre-courant sans melange axial. Nous nous limitons aux cas ou α et le rapport des debits montant et descendant sont voisins de 1 de sorte que: Efficacite de Murphee environ egale a efficacite globale (reacteurs unitaires). HUT (phase 1) environ egale a HUT (phase 2) environ egale a HEPT (colonnes). Dans une quatrieme partie, une expression de la puissance de separation isotopique des reacteurs est proposee et discuteeOriginal Title
Reactions d'echange isotopique. Cinetique et efficacite des reacteurs les mettant en oeuvre en separation isotopique
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Nov 1979; 47 p
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Rutland, Christopher J.; Leach, Joshua
Engine Research Center, University of Wisconsin - Madison, Wisconsin, (United States). Funding organisation: USDOE Office of Energy Research (ER) (United States)
Engine Research Center, University of Wisconsin - Madison, Wisconsin, (United States). Funding organisation: USDOE Office of Energy Research (ER) (United States)
AbstractAbstract
[en] The Combustion Corridor is a concept in which researchers in combustion and thermal sciences have unimpeded access to large volumes of remote computational results. This will enable remote, collaborative analysis and visualization of state-of-the-art combustion science results. The Engine Research Center (ERC) at the University of Wisconsin - Madison partnered with Lawrence Berkeley National Laboratory, Argonne National Laboratory, Sandia National Laboratory, and several other universities to build and test the first stages of a combustion corridor. The ERC served two important functions in this partnership. First, we work extensively with combustion simulations so we were able to provide real world research data sets for testing the Corridor concepts. Second, the ERC was part of an extension of the high bandwidth based DOE National Laboratory connections to universities
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15 Dec 2001; 4 p; FG02-99ER25389; Available from Paper copy available at OSTI: phone, 865-576-8401, or email, reports@adonis.osti.gov
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Report
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Markillie, G.A.
Oxford Univ. (United Kingdom)
Oxford Univ. (United Kingdom)
AbstractAbstract
No abstract available
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Source
1997; 130 p; Available from British Library Document Supply Centre- DSC:D197156; Thesis (Ph.D.)
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Miscellaneous
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Thesis/Dissertation
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AbstractAbstract
[en] An algorithm due to Loud is used to find asymptotically convergent series solutions for limit cycles subjected to weak periodic perturbations. If an exact or approximate solution to the unperturbed limit cycle is available near or far from marginal stability, then accurate predictions can be made for entrainment bands and the phase relationships between the various oscillatory chemical species and the perturbation. The utility of this method is shown for several model systems. In an appendix, the appearance and character of critical slowing down at the edges of entrainment bands is demonstrated
Original Title
p
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Journal Article
Journal
Journal of Chemical Physics; ISSN 0021-9606;
; v. 78(6); p. 3747-3755

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AbstractAbstract
[en] A mathematical model has been proposed for an isotopic exchange reaction between the solid particles and ions in a solution of finite volume. A theoretical equation has been derived to predict the exchange fraction as a function of the dimensionless time T with the kinetic parameters xi, xi1 and final fractional uptake U as parameters for the exchange rate controlled by combined film diffusion, surface chemical reaction and intraparticle diffusion. The exchange fraction increases as the values of T, U, xi and xi1 increase. Experimental results of the isotopic exchange systems CaCO3(s)Ca2+ (aq), CaC2O4(s)/Ca2+ (aq) and Ca-form Dowex 50W-X8/Ca2+ (aq) agree well with the theoretical equation proposed in this study. (author)
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25 refs.
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Journal Article
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Canadian Journal of Chemical Engineering; v. 55(3); p. 301-306
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