Electron correlation energy in confined two-electron systems

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

Macrophage ABCA2 deletion modulates intracellular cholesterol deposition, affects macrophage apoptosis, and decreases early atherosclerosis in LDL receptor knockout mice

Biopharmaceutic

Soils and agriculture in central-west and north Brazil

Modern soil science, spearheaded by research in Brazil has facilitated the utilization of vast areas of previously uncultivated soil long considered unsuitable for human food production into highly productive agricultural land. Naturally acid soils with high contents of aluminum and iron oxides and low CEC values and organic matter contents long considered insurmountable obstacles to crop production in tropical latitudes could be extremely productive. With continued development of the infrastructure needed by commercial agriculture Brazil has the potential to lead the world in its quest to provide food for growing human populations.A moderna ciência de solo, liderada pelas suas pesquisas no Brasil, tem possibilitado a utilização de vastas áreas de solos, durante muito tempo não cultivados por serem avaliados como inaptos para uma intensiva produção de alimentos. Hoje, ao contrário, constata-se que essas terras são altamente produtivas para a agricultura. Estas pesquisas vêm mostrando que alguns atributos naturais destes solos, como acidez, baixos teores de matéria orgânica, baixa capacidade de troca de cátions, além de altos teores de óxidos de ferro e/ou de alumínio - considerados como obstáculos à produção de boas colheitas em latitudes tropicais - podem ser superados. Com a continuação do desenvolvimento das infra-estruturas necessárias para alavancar ainda mais a agricultura comercial, o Brasil tem potencial para, em breve, liderar o mundo no que tange ao fornecimento de alimentos para as crescentes populações humanas

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

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

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

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