Influence of atomic mixing and preferential sputtering on depth profiles and interfaces

Atomic mixing and preferential sputtering impose a depth resolution limit on the use of sputter sectioning to measure the composition of metal–semiconductor interfaces. Experimental evidence obtained with the Pt–Si system is used to demonstrate ion‐induced atomic mixing and then its effect on sputter etching and depth profiling. Starting with discrete layer structures, a relatively low ion dose (≳3×10^(15) cm^(−2)) first produced a mixed surface layer with thickness comparable to the ion range. Higher ion doses then result in successive sputter etching and continual atomic mixing over a constant surface layer thickness. A model is developed that is based on a sputter removal (including preferential sputtering) of atoms at the surface and a uniform mixing of atoms over a constant thickness. The model predicts the influences of atomic mixing and preferential sputtering on the depth profiling of thin‐film structures and interfaces

Heterostructure by solid‐phase epitaxy in the Si〈111〉/Pd/Si (amorphous) system

When a thin film of Pd reacts with a 〈111〉 Si substrate, a layer of epitaxial Pd_2Si is formed. It is shown that Si can grow epitaxially on such a layer by solid‐phase reaction

Sedimentary Metal Bioavailability Determined By the Digestive Constraints of Marine Deposit Feeders: Gut Retention Time and Dissolved Amino Acids

Contaminant metals bound to sediments are subject to considerable solubilization during passage of the sediments through the digestive systems of deposit feeders. We examined the kinetics of this process, using digestive fluids extracted from deposit feeders Arenicola marina and Parastichopus californicus and then incubated with contaminated sediments. Kinetics are complex, with solubilization followed occasionally by readsorption onto the sediment. In general, solubilization kinetics are biphasic, with an initial rapid step followed by a slower reaction. For many sediment-organism combinations, the reaction will not reach a steady state or equilibrium within the gut retention time (GRT) of the organisms, suggesting that metal bioavailability in sediments is a time-dependent parameter. Experiments with commercial protein solutions mimic the kinetic patterns observed with digestive fluids, which corroborates our previous study that complexation by dissolved amino acids (AA) in digestive fluids leads to metal solubilization (Chen & Mayer 1998b; Environ Sci Technol 32:770-778). The relative importance of the fast and slow reactions appears to depend on the ratio of ligands in gut fluids to the amount of bound metal in sediments. High ligand to solid metal ratios result in more metals released in fast reactions and thus higher lability of sedimentary metals. Multiple extractions of a sediment with digestive fluid of A. marina confirm the potential importance of incomplete reactions within a single deposit-feeding event, and make clear that bioavailability to a single animal is Likely different from that to a community of organisms. The complex kinetic patterns lead to the counterintuitive prediction that toxification of digestive enzymes by solubilized metals will occur more readily in species that dissolve less metals

Stock Market, Economic Performance, And Presidential Elections

Using stock market and economic data from 1900 to 2008 from 27 separate presidential administrations in the United States (U.S.), including 15 Republican and 12 Democratic, this paper examines the relationships between the market return after each Election Day and economic performance during the presidential term. Using the theoretical framework of political economy, the authors examine how Wall Street’s reaction to a presidential election acts as a predictive measure of future economic performance. The analysis shows that the after-election market movement has progressively been more accurate in predicting the future Gross Domestic Product (GDP) growth but not the future unemployment rates. Given that the results show a higher correlation over time, the model appears to provide a good starting point for judging the economic potential of future presidential administrations.published_or_final_versio

The World Council of Churches: A Theological Appraisal

Throughout the history of the divided Church there have been earnest efforts to reunite the separated communions. The impetus for such a reunion usually was strongest in a period either of prosperity or of opposition. At the beginning of the nineteenth century the Church experienced an era of revivalism and expansion, and shortly the former confessional boundaries were ignored, and in spite of divergent doctrinal views denominations united in organizing the several national Bible Societies and large Missionary Associations. When shortly afterwards a wave of secularism swept over the world, the various communions again set aside their confessional differences and organized the Evangelical Alliance ( 1846) to meet jointly the common foe

50th Anniversary Saratov State University Zonal Library and University of Wyoming Coe Library, 1957-2007

Commemorative history booklet celebrating the joint 50th Anniversary of Saratov State University\u27s V.A. Artisevich Zonal Scientific Library and the University of Wyoming\u27s William R. Coe Library. Published in 2007

Experimental study on a metal hydride based hydrogen compressor

This is the post-print version of the final paper published in Journal of Alloys and Compounds. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2008 Elsevier B.V.A three-stage metal hydride based hydrogen compressor prototype was built. It has been designed for a hydrogen production facility using a low-pressure alkaline electrolyser. The compression system should transfer heat recovered from the electrolyser into the hydride beds to allow hydrogen desorption flow. The three-stage compressor achieves a compression ratio of 20:1 atm. It performs a thermal cycling of three AB5 hydrides between 20 and 80 °C. Its flow rate, for 25 g of each hydride bed, reaches about 20 l (NTP) of hydrogen per hour. The prototype is now operational. Some improvements in the heat transfer management system are also carried out before proceeding to the interconnection with the electrolyser and to the extent that the hydrogen produced satisfies the high purity requirement of the hydrides used in the compressor.Natural Resources Canada(NRCan), Ministère des Ressources Naturelles et de la Faune du Québec (MRNF), and Natural Sciences and Engineering Research Council of Canada