992 resultados para Sensibilité au contraste temporel
Resumo:
The structure and stability of palladium adlayers on Au(hkl) and Pt(hkl) were studied at different coverage degrees by means of Monte Carlo simulations using the interatomic potentials of the embedded atom model. In all cases the Pd films were found to grow epitaxially and pseudomorphically with the crystallographic orientation of the substrate. The differences and similarities of the adlayer with the substrate were analyzed.
Resumo:
Despite the compelling parallels between George Sand’s Laura; ou, le voyage dans le cristal and Jules Verne’s Voyage au centre de la Terre (both 1864), Sand’s place within the intertextual fabric of Verne’s novel has been occluded. By shifing the terms of the debate away from the vexed issues of borrowing, influence, or inspiration, and focusing on Verne’s sustained engagement with Sand’s work as a specifically geological fiction, this article sheds new light on the imbrication of the scientific and the fictional in Voyage au centre de la Terre, whereby geological and palaeontological references not only guarantee the text’s verisimilitude and underwrite its didactic objectives, but also fulfil an important metatextual function.
Resumo:
The mechanism of CO oxidation reactions over undoped and gold-doped CuMnOX (Hopcalite) catalysts has been examined using a temporal analysis of products (TAP) reactor Gold doping has been found to increase the activity of the mixed oxide catalyst significantly however using consecutive pulsing TAP experiments the presence of gold was not found to affect the contribution of the Langmuir-Hinshelwood mechanism Conversely gold doping was found to promote the Mars van Krevelen mechanism Using CO and O-2 multi-pulse TAP experiments the gold was found to modify the catalyst surface such that it stores much more oxygen that is active for the CO oxidation The CO multi-pulse experiments indicated that two distinct types of active oxygen species were found to be involved in the CO oxidation One type was observed in a similar amount on both doped and undoped catalysts and was associated with mixed oxide while the second type was only found on the gold-doped catalyst and was therefore clearly associated with the presence of gold on the catalyst surface The latter was found to be much less active than the oxygen inherent to the oxide but was at a concentration of approximately 10 times larger leading to the enhanced activity observed on gold doping (C) 2010 Elsevier Inc All rights reserved
Resumo:
This paper explores one of the defining aspects of politics and identity in Northern Ireland : the control and utilisation of public space, particularly urban public space. I will examine evidence of some changes in the way public space is being used in central Belfast that potentially reflects changing identities in the city. The paper concludes by speculating on whether a new civic identity that spans the political and ethnic divisions has started to develop in Belfast and that this might evolve even with increased residential division throughout the Belfast urban area.
Resumo:
The kinetics of the liquid-phase hydrogenation of citral (3,7-dimethyl-2,6-octadienal) on Au/TiO2 and Pt-Sn/TiO2 thin films was studied in the temperature range 313-353 K and citral concentrations of 0.25-10.0 mol m(-3). The thin films were deposited onto the inner walls of silica capillaries with internal diameter of 250 mu m. First-order dependence on hydrogen pressure and near zero order dependence on citral concentration were observed for the initial rate of citral hydrogenation over the Pt-Sn/TiO2 and Au/TiO2 thin films. The Au/TiO2 catalyst prevents citronellal formation. The highest yield of unsaturated alcohols was obtained on the Pt-Sn/TiO2 film at a reaction temperature of 343 K, liquid residence time of 30 min and a citral conversion of 99%. (C) 2011 Elsevier B.V. All rights reserved.
Resumo:
Surface-enhanced Raman (SERS) spectra of deoxyadenosine and 5'-dAMP on Ag and Au surfaces showed the protonation of both compounds in the N1 position, their orientation geometry on metal surfaces, and the formation of Ag+ complexes at alkaline pH on hydroxylamine-reduced Ag colloids. Interestingly, substitution at the N9 position caused dramatic changes in the relative band intensities within the spectra of both deoxyadenosine and 5'-dAMP compared to that of simple adenine, although they continued to be dominated by adenine vibrations. Concentration-dependent spectra of 5'-dAMP were observed, which matched that of adenine at high concentrations and that of deoxyadenosine at lower concentration (
Resumo:
The article presented to Malraux specialists the conclusions and findings of the international conference on André Malraux held at Queen's University Belfast in 2007.