Impact of palladium substitution for copper in Bi

An extensive new solid solution was synthesized by substitution of Pd+2 for Cu+2 in Bi2CuO4 compound [J.-C. Boivin et al., C.R. Hebd. Seances Acad. Sci., Ser. C 276, 1105 (1973)]. Polycrystalline ceramic powder with formula Bi2Cu$_{1-x}$PdxO4 were prepared by sol-gel method using (Bi, Cu, Pd) nitrates and pure citric acid. X-ray patterns show a single phase with tetragonal symmetry and space group P4/ncc (No. 130). In cases, the tetragonal cell c parameter and therefore the metal-metal distance (dM-M = c/2) increases linearly with increasing palladium concentration. Electrical conductivity measurements show that the resistivity decreases regularly with pd2+ substitution. It is possible to obtain materials with an ambient temperature conductivity ranging from 10-6 to 10-3 S cm-1

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Towards a smooth handoff for TCP and real time applications i

Assessment and modeling the influence of nitrogen input in the soil on groundwater nitrate pollution: plain of upper- cheliff (north algeria)

International audienceThe present study associates groundwater nitrate pollution with agricultural activity in the Upper-Cheliff wich is known for intensive farming practices. The indicatory kriging method is used in order to elaborate a map of the spatial probability distribution of nitrate concentration that exceeds a threshold value of 50ppm during high watering period for the year 2012. The obtained results show that the areas exceeding nitrate concentrations of 50 ppm, occupy more than 80% of the Upper-Cheliff aquifer area. It appears, from this map, the most affected areas are those for which the level of intensification of the N-fertilizers is the strongest (zone of garden farming, potatoes in particular) throw condensed.These results are coherent with the experimental data, which show an average nitrate concentration value of 75 ppm, significantly higher than the World Health Organization (WHO)'S standards. In this study, the total nitrogen brought to the soils of the Upper-Cheliff is estimated at 247 kg ha-1 for this year, and compared to the results of New Computer models such as PILOTEN used to analyze alternative management practices together with soil, plant, and climate characteristics to determine the amount of nitrogen leached under the potatoes crops. The result of this model show that 60% of nitrogen input is leaching under potato crops which is relevant to the map showing the spatial evolution of nitrate. Nitrate pollution in the groundwater of the Upper-Cheliff appears to be significant and driven by the application of both inorganic fertilizer and land use

SURFACE AND CATALYTIC PROPERTIES OF SUPPORTED Pt/Ni NANOPARTICLES

The surface and catalytic properties of SiO2 supported Pt/Ni nanoparticles have been investigated. The metal nanoparticles were prepared via simultaneous reduction of the metal salts in an aqueous media at 80&ord

The Effect of Oleic Acid Stabilizer on the Surface Properties of Bimetallic PtNi Catalysts

International audienceA detailed study on the surface properties of oleic acid-stabilized PtNi nanoparticles supported on silica is reported. The oleic acid-stabilized PtNi nanoparticles were synthesized using NaBH4 as the reducing agent at various temperatures and oleic acid concentrations, prior to incorporation onto the silica support. X-ray diffraction studies of the unsupported oleic acid-stabilized PtNi particles revealed that the PtNi existed as alloys. Upon incorporation onto silica support, surface properties of the catalysts were investigated using H-2-temperature reduction (H-2-TPR), H-2-temperature desorption (H-2-TPD) and H-2-chemisorption techniques. It was found that for the bimetallic catalysts, no oxides or very little oxidation occurred. Furthermore, these catalysts exhibited both Pt and Ni active sites on its surface though the availability of Ni active sites was dominant. A comparison of the surface properties of these materials with those prepared without oleic acid in our previous work [N. H. H. Abu Bakar et al., J. Catal. 265, 63 (2009)] and how they affect the hydrogenation of benzene is also discussed