35 resultados para Narváez, Ramón María, 1800-1868


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The collection of the data for this volume formed part of the work of the European Science Foundation project on Writing National Histories. I was a member of the Research Team (1) which produced the volume. I also wrote two contributions for the Atlas. I collected the data and wrote the section on academic historians in Ireland. I also wrote a synthesis of the data on academic women historians in Europe, 1815-2005.

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Dense ceramics with mixed protonic-electronic conductivity are of considerable interest for the separation and purification of hydrogen and as electrochemical reactors. In this work, the hydrogen permeability of a Sr0.97Ce0.9Yb0.1O3 - δ (SCYb) membrane with a porous Pt catalytic layer on the hydrogen feed-exposed side has been studied over the temperature range 500-804 °C employing Ar as the permeate sweep gas. A SiO2-B2O3-BaO-MgO-ZnO-based glass-ceramic sealant was successfully employed to seal the membrane to the dual-chamber reactor. After 14 h of exposure to 10% H2:90% N2 at 804 °C, the H2 flux reached a maximum of 33 nmol cm- 2 s- 1, over an order of magnitude higher than that obtained on membranes of similar thickness without surface modification. The permeation rate then decreased slowly and moderately on annealing at 804 °C over a further 130 h. Thereafter, the flux was both reproducible and stable on thermal cycling in the range 600-804 °C. The results indicate an important role of superficial activation processes in the flux rate and suggest that hydrogen fluxes can be further optimised in cerate-based perovskites. © 2009 Elsevier B.V. All rights reserved.