Water dimer diffusion on Pd{111} assisted by an H-bond donor-acceptor tunneling exchange

Based on the results of density functional theory calculations, a novel mechanism for the diffusion of water dimers on metal surfaces is proposed, which relies on the ability of H bonds to rearrange through quantum tunneling. The mechanism involves quasifree rotation of the dimer and exchange of H-bond donor and acceptor molecules. At appropriate temperatures, water dimers diffuse more rapidly than water monomers, thus providing a physical explanation for the experimentally measured high diffusivity of water dimers on Pd{111} [Mitsui et al., Science 297, 1850 (2002)]

An assessment of environmental impacts of cassava starch extraction technologies

The environmental impacts of the transformation of cassava roots into starch were assessed for three contrasting technologies at small and large scale (1-2 and 100-200t starch per day), using the Life Cycle Assessment (LCA) methodology. The objective was to assess impacts for each unit operation, so as to identify impacts hotspots as well as sustainable practices, with a view to uncover opportunities for improving the environmental performance of cassava starch production. The system boundaries were defined as the unit operations used to transform fresh cassava roots delivered at factory gate into loose, dry cassava starch. Inventory data indicated wide variations in energy and water consumption. The large scale technology required 702kWh/t starch, mainly (75%) from fuel oil used for the drying operation, but was most efficient in terms of water use (10m3/t starch) due to water recycling between unit operations. The two small scale technologies were similar in terms of electricity use (59kWh/t starch), and relied on solar energy for drying. In contrast, their water consumption varied from 20 to 60m3/t starch due to differences in the design of the rasping and starch recovery (extraction) operations. The LCA characterizations, using the ReCiPe method, indicated that the main impact contributions were at the drying operation for the large scale technology, and at the extraction operation for the small scale technologies, mainly because of energy use, as well as water use in the case of the most water-intensive technology. Hence strategies to reduce the impacts of cassava starch production could focus on: Increasing the energy efficiency of the drying operation or replacing fossil energy with a renewable source (biogas), which can be produced from the factory wastewater; Improving the design of some unit operations with regards to water and energy efficiency; and Promoting the transfer and adoption of water recycling practices. (Texte intégral

Gemini/GMOS photometry of intermediate-age star clusters in the Large Magellanic Cloud

We present Gemini South GMOS g,i photometry of 14 intermediate-age Large Magellanic Cloud (LMC) star clusters, namely: NGC 2155, 2161, 2162, 2173, 2203, 2209, 2213, 2231, 2249, Hodge 6, SL 244, 505, 674, and 769, as part of a continuing project to investigate the extended Main Sequence Turnoff (EMSTO) phenomenon. Extensive artificial star tests were made over the observed field of view. These tests reveal the observed behaviour of photometric errors with magnitude and crowding. The cluster stellar density radial profiles were traced from star counts over the extent of the observed field. We adopt clus- ter radii and build colour-magnitude diagrams (CMDs) with cluster features clearly identified. We used the cluster (g,g-i) CMDs to estimate ages from the matching of theoretical isochrones. The studied LMC clusters are confirmed to be intermediate-age clusters, which range in age 9.10 < log(t) < 9.60. NGC 2162 and NGC 2249 look like new EMSTO candidates, in addition to NGC 2209, on the basis of having dual red clumps.Comment: MNRAS, accepte

Ação de regulador do metabolismo de etileno sobre a produtividade de soja cultivada em terras baixas.

bitstream/item/30414/1/boletim-68.pd

Preparo do solo pós-colheita do arroz irrigado.

bitstream/CPACT-2010/13008/1/preparo-do-solo.pd

Condensation in ducts

Phase changing flows are being considered for thermal management in space platforms. The resulting flow patterns are very complicated and extremely sensitive to gravity action. Concerning fluid flow in ducts, the available evidence indicates that although the pressure loss does not depend too much on the fluid flow pattern,the heat transfer (and resulting phase change) does. A simple exercise to illustrate this point is presented in this paper. It deals with condensing flow in straight circular cross-sectional ducts. Two extreme configurations are considered here, one corresponds to a stratified flow and the other to an annular flow. Both types of flow patterns have been extensively considered in the past and from this point of view almost nothing is new in the paper, but past results look conflictive and this could be due to the limitations and computational intricacies of the models used. Thus the problem has been reformulated from the onset and the results are presented as the evolution of the vapor quality (vapor to total mass flow rate) along the duct, in typical cases. The results presented here indicate that within the validity of the present models and the assumed ranges of mass flow rate, duct diameter, thermal conditions and fluid characteristics,the length of the ducts required to achieve complete condensation under zero gravity are an order of magnitude larger than in horizontal tubes under normal terrestrial conditions

Archaeological excavations in the foundation area of the city of Córdoba, Argentina: Dean Funes 67

Se presentan los primeros resultados de la intervención arqueológica, dentro del marco de un estudio de impacto, en un local comercial situado en el Barrio Centro de la ciudad de Córdoba. La parcela en estudio se encuentra localizada a escasos metros del Cabildo de la ciudad por lo que su estudio cobra importancia para el análisis de las formas de uso del espacio en la zona central de la ciudad a lo largo de más de 400 años de ocupación. Durante las excavaciones se hallaron diversos objetos (metal, vidrio, cerámica utilitaria, loza y restos de huesos) y una estructura arquitectónica. Esta última se trata de un muro de calicanto que permite asignar los restos al menos a tres momentos. Uno temprano que correspondería al siglo XVIII, y dos posteriores correspondientes a los siglos XIX y XX Con esto se evidencia la importancia de mitigar el impacto negativo que las nuevas construcciones producen sobre el registro arqueológico -oculto a quienes transitan asiduamente por su superficie- que enriquece y complementa la historia documental de la ciudad.This paper aims at showing the first results of the archaeological intervention in a commercial store located in downtown Cordoba city. The study area is located just a few meters from the city council. During the excavations we found various kinds of objects (metal, glass, ceramic pieces, pottery and bone remains), in addition to architectural features, including a masonry wall, which allow us to interpret at least three different occupations. One would be related to activities from the eighteenth century, and at least two more related to the nineteenth and twentieth centuries. This work is an attempt to underline the importance of subsurface-controlled interventions in order to record the recent history of the city, currently hidden even to those who walk past its surface.Fil: Izeta, Andres Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Antropología de Córdoba. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Instituto de Antropología de Córdoba; ArgentinaFil: Pautassi, Eduardo Adrian. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Museo de Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Silva Ferreira Da Costa, Thiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Antropología de Córdoba. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Instituto de Antropología de Córdoba; ArgentinaFil: Robledo, Andrés Ignacio. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Museo de Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bilinski, Cristian. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Museo de Antropología; Argentin