Publications

Abstract Here, we report on a Si–air/ionic liquid electrolyte battery whose performance improves with small amounts of water in the electrolyte. The shift of the generation zone of the SiO 2 discharge product from the air cathode surface into the bulk region of the liquid electrolyte, caused by water addition, is demonstrated through various means. Addition of 15 vol % water leads to an increase of 40 % in the discharge capacity as compared to the capacity obtained using a pure ionic liquid electrolyte. If the water content increases above 20 vol %, the Si–air cell capacity dramatically decreases. The water–ionic liquid electrolyte mixture shows a maximum in the ionic conductivity with a water content of 10 vol %. In‐depth studies indicate a reduced amount of discharge product at the air electrode using 15 vol % H 2 O electrolyte. The morphology of the anode surface, as well as the developed surface film in the presence of water‐containing ionic liquid, is reported. This study shows that exposing a Si–air battery to a humid environment does not result in capacity losses, but rather improves cell performance.

A low-copy expression vector has been constructed from a 9 Kbp region of the Escherichia coli F plasmid containing the oriV and oriS origins of replication. This plasmid carries the β-lactamase gene (Apr) and the araBAD promoter/araC regulator for arabinose-inducible gene expression. A derivative which carries a lacZ reporter gene was found to be stably maintained for at least 150 generations. A related multi-copy plasmid was stably maintained in arabinose-free medium, but no plasmid-bearing segregants remained after 60 generations when lacZ expression was induced. Induced expression resulted in 27% (multi-copy) and 12% (low-copy) decreases in growth rate. The uninduced levels of β-galactosidase were 200 units (multi-copy) and 15 units (low-copy). © 1998 John-Wiley & Sons, Inc. Biotechnol Bioeng 59:659–665, 1998.

A reformulação da questão de classe empreendida por Pierre Bourdieu exemplifica os traços principais da sua sociologia e a maneira pela qual ele amplia, mescla e corrige visões clássicas num quadro próprio. O artigo revela a motivação existente por detrás dos deslocamentos conceituais-chave que Bourdieu efetua, de estrutura de classe a espaço social, de consciência de classe a habitus, de ideologia a violência simbólica, e de classe dirigente a campo de poder. Destaca também estudos recentes que investigaram, testaram e refinaram os princípios centrais do modelo de Bourdieu e oferece uma bibliografia das suas publicações sobre classe, documentando um duplo deslocamento, empírico e analítico, para uma sociologia da realização de categorias, o que evidencia o poder constitutivo das estruturas simbólicas.

Corrosion potentials and cyclic voltammograms are reported for AISI 1010 carbon steel, E-Brite 26-1 stainless steel, AISI 316L stainless steel, Haynes Alloy 20 Mod, Carpenter 20 Cb-3, Inconel Alloy 625, Hastelloy Alloy G, Hastelloy Alloy C-276, Titanium 50A, and TiCode 12 in high salinity geothermal brine at 250 C. Potential-pH diagrams for the component metals (Fe, Ni, Cr, Ti) in the brine at 25 and 250 C are also derived, and are used to interpret the corrosion behavior and cyclic voltammetric responses of the alloys in the elevated temperature brine environment.

geologic repository. Studtite was exposed to different fluences of radiation, and amorphization was analyzed as a function of these doses. In a different set of experiments, two other uranium-containing minerals, soddyite and uranophane, were studied under electron irradiation and over the temperature range of 25-300 °C. Under certain conditions the formation of nanocrystalline U02 was observed. Related to this we synthesized different uranium -containing compounds, for example, coffinite, USiO4, has been produced by hydrothermal synthesis and was analyzed using different electron microscopy and diffraction methods. Related to this, phosphorous-rich coffinite, U(Si,P)O4 $$\cdot$$ H2O, from the natural nuclear reactor at Bangombe, Gabon, has been examined as an important primary mineral and alteration product of uraninite under reducing conditions. In addition, a mineral assemblage of coffinite, USiO4$$\cdot$$ nH2O, carbonate-fluorapatite and (Ca, Sr)-(meta)autunite from the Woodrow Mine, Grants uranium region, New Mexico, has been investigated in order to understand the influence of a P-rich micro-geochemical environment on precipitation of coffinite and its subsequent alteration under oxidizing conditions. Finally, the response of synthetic coffinite to energetic ion beam irradiation was investigated. The second complex topic was the mechanism of redox reactions of actinides, with special emphasis on the kinetics. This topic led to the development of computational and experimental techniques to approach the redox mechanism in a more fundamental way, specifically to conceptualize a standard set of kinetic roadblocks that could be built into a more fundamental kinetic theory that is less based on a black-box model. Here, we have combined experimental techniques such as electrochemistry, electrochemical atomic force microscopy, x-ray photoelectron and Auger spectroscopy, electron microscopy, and a new set of quantum mechanical calculations that allow for the derivation of reaction paths. In addition, the role of mineral surfaces was evaluated in catalyzing reactions as they might be doing it in natural environments, and geologic barriers, but also in the near field of nuclear waste repositories. In addition, we have developed an experimental setup to quantify the synergistic interaction of different organic ligands as e- donors and TiO2 as a photocatalyst, with light at different wavelengths, for uranyl reduction, showing that all components are necessary for efficient photoreduction. In addition, electronic and atomic structure, thermodynamics, and reaction pathways were investigated for light -induced redox reactions. The third complex topic developed in the grant period was the incorporation of actinide ions into minerals as well as actinide metal organic frameworks. Step by step, we have developed a more comprehensive picture of the incorporation energies, structures, and electronic properties of actinyls incorporated into sedimentary minerals, such as carbonates and sulfates, iron oxides that, in addition to being present in natural environments, maybe a corrosion product of nuclear waste containers, and jarosites that are common waste products in acid mine setting s and also occur in uranium mines. There is also a progression of theoretical concepts within this series of papers: while our earlier papers lay the ground rules for combining aqueous ions and periodic minerals within the same chemical equation (typically a roadblock for traditional quantum-mechanical models), and we have extended the usage of endmember minerals by complex solid solutions series on the cation and anion sites. Furthermore, while typically only equilibria between dissolved species and incorporation into bulk minerals are considered, our latest contribution analyzes the thermodynamics along the entire reaction path from solution, to surface adsorption, to incorporation into the uppermost surface layer, and finally to incorporation into the bulk solid.