38 research outputs found

    Electron correlation energy in confined two-electron systems

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    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 - 10 a0. 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

    Predicting Adverse Drug Reactions Using Publicly Available PubChem BioAssay Data

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    Further Progress Toward the Determination of Ttp-x(22Ne)

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    Following the start of exploration of the problem of the effect of neon isotopes on the triple-point temperature in 2005, further progress was achieved in 2006-2008, and published in 2008. This paper summarizes the advances to date in our understanding as obtained from further work done in 2008-2009 on five basic aspects of the problem: new isotopic assays; new thermal measurements on neon of ¿natural¿ composition; the feasibility of obtaining a value of the slope dTtp/dx(22Ne) with an accuracy sufficient for the purpose; the possible occurrence of isotopic fractionation during the process of sealing the samples in the cells; and new thermal measurements on the pure isotopes 20Ne and 22Ne. The recently collected information is sufficient to state that it will eventually be possible to fulfill within 2010 the goal of recommending to the CCT solutions for the correction, with an accuracy fitting the purpose, of the neon isotopic effect on Ttp, to be included in a future revision of the Technical Annexe to the ¿mise en pratique¿ of the kelvin.JRC.D.3-Knowledge Transfer and Standards for Securit

    Dependence of the Triple Point Temperature of Neon on Isotopic Composition and its Implications for the ITS-90

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    The paper summarizes the results of an International Project started in 2003 aimed at formulating a correction for the variability of isotopic composition found in ‘natural’ neon, and presently not taken into account by the ITS-90 definition, whose consequent ambiguity leads to a combined uncertainty uc = 160 microK, whereas uc = 30–50 microK for the rest of the budget. After a very short summary of the Project results (a detailed Final Report will be published later) recommendations for the correction function are presented, in agreement with both the experimental data and the theoretical calculations

    Progress Towards the Determination of the Relationship of Triple-Point Temperature versus Isotopic Composition of Neon

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    Following the finalization of the work performed to establish the triplepoint temperature versus isotopic composition relationship for protium (Metrologia 42, 171 (2005)) adopted into the ITS-90 definition by the International Committee for Weights and Measures (CIPM) in 2005, and a preliminary exploration of the variability in the triple-point temperature of neon gas samples arising from differences in isotopic composition (Anal.Chem. 77, 5076 (2005)), this article reports further progress toward the determination of a similar comprehensive relationship for neon, to be included in a future revision of the Technical Annexe to the "mise en pratique" of the kelvin. This progress article mainly concerns a set of gas samples used for the neon triplepoint measurements during CCT-K2, and subsequently, others for which the isotopic compositions were recently measured. Recent high accuracy measurements of the corresponding thermal data are now available for many of these samples, but not yet for all of them.JRC.D.4-Isotope measurement
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