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556 results on '"Hazemann, Jean-Louis"'

207. High-resolution spectroscopy on an X-ray absorption beamline

Author

Hazemann, Jean-Louis, primary, Proux, Olivier, additional, Nassif, Vivian, additional, Palancher, Hervé, additional, Lahera, Eric, additional, Da Silva, Cécile, additional, Braillard, Aurélien, additional, Testemale, Denis, additional, Diot, Marie-Ange, additional, Alliot, Isabelle, additional, Del Net, William, additional, Manceau, Alain, additional, Gélébart, Frédéric, additional, Morand, Marc, additional, Dermigny, Quentin, additional, and Shukla, Abhay, additional

Published
2009
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209. Enhanced Adsorption of Arsenic onto Maghemites Nanoparticles: As(III) as a Probe of the Surface Structure and Heterogeneity

Author

Auffan, Mélanie, primary, Rose, Jérôme, additional, Proux, Olivier, additional, Borschneck, Daniel, additional, Masion, Armand, additional, Chaurand, Perrine, additional, Hazemann, Jean-Louis, additional, Chaneac, Corinne, additional, Jolivet, Jean-Pierre, additional, Wiesner, Mark R., additional, Van Geen, Alexander, additional, and Bottero, Jean-Yves, additional

Published
2008
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210. Evidence for the presence of U–Mo–Al ternary compounds in the U–Mo/Al interaction layer grown by thermal annealing: a coupled micro X-ray diffraction and micro X-ray absorption spectroscopy study

Author

Palancher, Hervé, primary, Martin, Philippe, additional, Nassif, Vivian, additional, Tucoulou, Remi, additional, Proux, Olivier, additional, Hazemann, Jean-Louis, additional, Tougait, Olivier, additional, Lahéra, Eric, additional, Mazaudier, Fabrice, additional, Valot, Carole, additional, and Dubois, Sylvie, additional

Published
2007
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216. VO x/SiO2 Catalyst Prepared by Grafting VOCl3 on Silica for Oxidative Dehydrogenation of Propane.

Author

Zhu, Haibo, Ould ‐ Chikh, Samy, Dong, Hailin, LlorENs, Isabelle, Saih, Youssef, Anjum, Dalaver H., Hazemann, Jean ‐ Louis, and Basset, Jean ‐ Marie

Subjects
CATALYSTS, CATALYSIS, PROPENE, SILICA, OXIDATIVE dehydrogenation, RAMAN spectroscopy
Abstract

The VO x/SiO2 catalysts for oxidative dehydrogenation of propane were synthesized by a simple grafting method. The VOCl3 was first grafted at the surface of SiO2, which was dehydrated at different temperature (from 200 to 1000 °C). The formed grafted complexes were then calcined in air, leading to the formation of VO x/SiO2 catalysts. The synthesized catalysts were characterized by nitrogen adsorption, SEM, Raman spectroscopy, temperature-programmed reduction, and extended X-ray absorption fine structure analysis. The SiO2 pretreatment temperature has an evident effect on the loading and dispersion of VO x on SiO2, which finally affects their catalytic performance. High SiO2 treatment temperature is beneficial to dispersing the vanadium oxide species at the SiO2 surface. These materials are efficient catalysts for the catalytic oxidative dehydrogenation of propane to propylene. The best selectivity to propylene is achieved on the VO x/SiO2-(1000) catalyst. The high selectivity and activity are well maintained for three days catalytic reaction. [ABSTRACT FROM AUTHOR]

Published
2015
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233. Monitoring Morphology and Hydrogen Coverage of Nanometric Pt/γ-Al2O3 Particles by In Situ HERFD-XANES and Quantum Simulations.

Author

Gorczyca, Agnes, Moizan, Virginie, Chizallet, Celine, Proux, Olivier, Del Net, William, Lahera, Eric, Hazemann, Jean-Louis, Raybaud, Pascal, and Joly, Yves

Subjects
PLATINUM nanoparticles, HETEROGENEOUS catalysis, NANOPARTICLE synthesis, DENSITY functional theory, X-ray absorption near edge structure, HYDROGEN spectra, METAL nanoparticles, HIGH resolution imaging
Abstract

Platinum nanoclusters highly dispersed on γ-alumina are widely used as heterogeneous catalysts. To understand the chemical interplay between the Pt nanoparticles, the support, and the reductive atmosphere, we performed X-ray absorption near edge structure (XANES) in situ experiments recorded in high energy resolution fluorescence detection (HERFD) mode. Spectra are assigned by comparison with simulated XANES spectra on models obtained by molecular dynamics (DFT-MD). We propose platinum cluster morphologies and quantify the hydrogen coverages compatible with XANES spectra recorded at variable hydrogen pressures and temperatures. Using cutting-edge methodologies to assign XANES spectra, this work gives unequalled atomic insights into the characterization of supported nanoclusters. [ABSTRACT FROM AUTHOR]

Published
2014
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235. Structure and Thermal Stability of Bi(III) Oxy-Clusters in Aqueous Solutions.

Author

Brugger, Joël, Tooth, Blake, Etschmann, Barbara, Liu, Weihua, Testemale, Denis, Hazemann, Jean-Louis, and Grundler, Pascal

Subjects
THERMAL stability, AQUEOUS solutions, PERCHLORATES, X-ray spectroscopy, POLYCYCLIC aromatic compounds, PERMITTIVITY
Abstract

The structure of Bi(III) clusters in aqueous concentrated acidic perchlorate solutions has been studied by means of X-ray absorption spectroscopy (XAS). The XAS data show that the polynuclear [BiO(OH)] complex with a cage structure predominates at room temperature in acidic Bi-rich solutions. This complex breaks down to form mononuclear complexes with increasing temperature to 428 K. This behavior is consistent with theoretical predictions based on considerations of the electrostatic repulsion, which increases sharply as the dielectric constant of the solvent decreases with increasing temperature. [ABSTRACT FROM AUTHOR]

Published
2014
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239. Spectroscopic and saturation magnetization properties of the manganese- and cobalt-substituted Fur (ferric uptake regulation) protein from Escherichia coli

Author

Adrait, Annie, Jacquamet, Lilian, Le Pape, Laurent, Gonzalez de Peredo, Anne, Aberdam, Daniel, Hazemann, Jean-Louis, Latour, Jean-Marc, and Michaud-Soret, Isabelle

Subjects
Escherichia coli -- Genetic aspects, Metalloproteins -- Research, Bacterial proteins -- Research, Bacterial genetics -- Research, Biological sciences, Chemistry
Abstract

The spectroscopic and magnetic properties of Fur protein from Escherichia coli reconstituted with Co(2+) and Mn(2+) ions have been studied. Fur is a metalloprotein that regulates genes involved in the iron uptake in gram-negative bacteria such as E coli. Results indicate that Fur can bind one metal dication per monomer while its saturation magnetization reveals the presence of a high-spin metal dication. It has also been observed that there is no interaction between the two metal ions found in the dimer.

Published
1999

241. Mechanisms of Lichen Resistance to Metallic Pollution

Author

Sarret, Géraldine, primary, Manceau, Alain, additional, Cuny, Damien, additional, Van Haluwyn, Chantal, additional, Déruelle, Serge, additional, Hazemann, Jean-Louis, additional, Soldo, Yvonne, additional, Eybert-Bérard, Laurent, additional, and Menthonnex, Jean-Jacques, additional

Published
1998
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249. Geochemical Resilience of a Ferralsol Subjected to Anoxia and Organic Matter Amendment.

Author

Lahlah, Jasmina, Renault, Pierre, Cazevieille, Patrick, Buzet, Aurélie, Hazemann, Jean-Louis, Womes, Manfred, and Cambier, Philippe

Subjects
FERRALSOLS, GEOCHEMISTRY, ANAEROBIOSIS, MANGANESE in soils, IRON, FERMENTATION
Abstract

The spreading of vinasse on soils may favor not only anoxia but also mineral alterations and metal mobilization. Our aims were to record the geochemical changes occurring in a ferralsol subjected to vinasse input and anaerobiosis, and to check for soil resilience after a return to aerobic conditions. Soil slurries were therefore incubated under successive 7 d of aerobic, 0 to 28 d of anaerobic, and 28 d of aerobic conditions, vinasse being supplied at one of three levels when anaerobiosis began. At several dates, the slurry solution was characterized (pH and organic and mineral compounds) and Mn and Fe oxidation states in solids were assessed. Before incubations, about 20% ofthe Fe in solids was already reduced, whereas almost all Mn was found as Mn(IV). During the first aerobic period, mobilized metals included Pb, Zn, Ni, Cu, and Cr. After vinasse input during the first 14 d of anaerobiosis, the principal biotransformations were fermentation and true acetogenesis; Fe and Mn were mobilized during this period (up to 4.05 and 6.2 mmol L-1, respectively), and most Mn and an unknown but small fraction of Fe in solids were reduced. During the subsequent 14 d of anaerobiosis, only acetoclastic methanogenesis was observed. The return to aerobic conditions led to rapid oxidative immobilization of Fe, desorption of exchangeable Fe(II), and the partial immobilization of other metals (Ca, Mg, K, Na, Mn, Pb, and Ni). Manganese was not oxidized, and there was no return to the initial conditions for Fe and Mn in solids. [ABSTRACT FROM AUTHOR]

Published
2009
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