Interplay of chemical pressure and hydrogen insertion effects in CeRhSn {\bf CeRhSn} from first principles

Investigations within the local spin density functional theory (LSDF) of the intermetallic hydride system ${\rm CeRhSnH_x}$ were carried out for discrete model compositions in the range $0.33 \leq x_H \leq 1.33$. The aim of this study is to assess the change of the cerium valence state in the neighborhood of the experimental hydride composition, ${\rm CeRhSnH_{0.8}}$. In agreement with experiment, the analyses of the electronic and magnetic structures and of the chemical bonding properties point to trivalent cerium for $1 \leq x_H \leq 1.33$. In contrast, for lower hydrogen amounts the hydride system stays in an intermediate-valent state for cerium, like in ${\rm CeRhSn}$. The influence of the insertion of hydrogen is addressed from both the volume expansion and chemical bonding effects. The latter are found to have the main influence on the change of Ce valence character. Spin polarized calculations point to a finite magnetic moment carried by the Ce $4f$ states; its magnitude increases with $x_H$ in the range $1 \leq x_H \leq 1.33$

Application of 2D correlation spectroscopy on olive stones acid hydrolysates: Effect of overliming

In order to valorize olive stones we are studying their dilute-acid hydrolysate (DAH) composition, and trying to highlight the effect of the overliming process on DAH composition in order to perform an effective treatment that maximize sugars concentrations (xylose) and minimizes the amount of toxic materials (FF and HMF). An 2(2)3(1) experimental design was established to describe the effects of three controlled factors with distinct levels: pH (10 and 12), temperature (25 and 60 degrees C) and detoxification time (15,30 and 60 min) on the concentration of xylose, FF and HMF. A better understanding of this overliming process was possible by exploring the chromatograms obtained with 2D Correlation Spectroscopy (2DCOS). 2D correlation spectroscopy gave information about the relations that exist between chromatographic peaks and chromatograms. The order in which the constituents vary can be deduced from the sign of peaks in the synchronous and asynchronous matrices, facilitating the interpretation of kinetic studies. (c) 2011 Published by Elsevier B.V

Etude ab initio de l'effet d'insertion de l'hydrogène sur les propriétés magnétiques et chimiques dans les phases de laves : cas de ZrFe2

The electronic and magnetic properties of the cubic Laves phases ZrFe2 and of its hydride ZrFe2H3,5 are studied within the density functional theory (DFT) in its local spin density approximation (LSDA) for the purpose of assessing the interplay between chemical pressures versus chemical bonding effects due to the insertion of hydrogen..

Analysis of six trace elements (Cd, Cr, Cu, Ni, Pb and Zn) in Diplodus sargus and Siganus rivulatus fish in three sites along the Lebanese coast

International audienceThe Lebanese coast is subjected to a strong urban, touristic and industrial pressure. The wastewater of the littoral zone eventually reaches the sea without undergoing, in general, any pretreatment.This precarious situation escalates with the absence of laws that address the "food security" and “environmental” aspects throughout the Lebanese coast or the non-applicationof the existing ones. The fisheries sector inparticular, suffered the consequences. Indeed, in Lebanon, the consumer’s interest for fish is growing. For them the sea products in particularly fish are considered as a healthy food, or even as a luxury food. The sea food restaurants lining the coast are among the most expensive and the most prestigious in the country. But consumer confidence has been eroded by media reports evoking the maritime pollution in the country. It is in this context that we chose to study the metal pollution of two species of fish (Diplodus sargus and Siganus rivulatus) in a region particularly affected by pollution which run from Tabarja to the north of Beirut and end at Ouzaï located at the south of the capital. The captured fishes was completely grounded, lyophilized and mineralized. The mineralization was conducted in a microwave digester. After that, the six trace elements were analyzed by atomic absorption spectroscopy: Cd, Cr, Cu, Ni, Pb and Zn. The obtained results are in general, consistent within international studies : the fish accumulation for the metal contaminants (with exception of Hg) is low. The recorded values are less or equal than the maximum limits in food set by international bodies. Considering the season factor, we note a seasonal fluctuation in the concentration of the studied metals. By comparing the metal level for the three sites, we note that the Ouzaï site is in general, the most polluted one

Adenosine reduces the reverse mode of the Na+/Ca(2+) exchanger in ferret cardiac fibres.

International audienc

Etude ab initio de l'effet d'insertion de l'hydrogène sur les propriétés magnétiques et chimiques dans les phases de laves : cas de ZrFe2

The electronic and magnetic properties of the cubic Laves phases ZrFe2 and of its hydride ZrFe2H3,5 are studied within the density functional theory (DFT) in its local spin density approximation (LSDA) for the purpose of assessing the interplay between chemical pressures versus chemical bonding effects due to the insertion of hydrogen..

Enhancing the phosphorus recovery under simulated conditions of phosphoric acid production by modification of calcium sulphate crystals using aluminum sulphate

Nous avons étudié l'effet d’Al2O3 sur le rendement de récupération de P2O5 dans des conditions simulées de la production industrielle d’acide phosphorique. L’attaque du phosphate naturel par l’acide sulfurique en présence d’acide phosphorique dilué est réalisée sur un pilote semi continu de type S3C à 80°C. Deux échantillons de phosphate naturel d’origines Algérienne et Syrienne ont été examinés dans le but d’améliorer la production d’acide phosphorique. La diminution de perte en P2O5 dans le gypse co formé est fortement liée à la morphologie et à la distribution volumétrique des cristaux de gypse di hydrate qui affecte la séparation solide/liquide. Nous avons mis en évidence l’influence de la teneur en acide sulfurique en excès et du pourcentage en P2O5 dans l’acide phosphorique produit sur le rendement de’ récupération de P2O5 lors de la filtration. La teneur optimale de Al2O3 pour avoir une meilleure filtrabilité est de 1 % (en masse). Dans ces conditions, le rendement de récupération de P2O5 à partir de gypse a atteint les 96,16% pour le phosphate syrien et 95,89% pour le phosphate algérien

Influence du broyage énergétique sur les propriétés structurales et magnétiques des intermétalliques GdNi2 et GdCu2

GdNi2 and GdCu2 were submitted to a high-energy ball-milling using a planetary ball-miller..

Investigation of changes in crystal and electronic structures by hydrogen within LaNi₅ from first-principles

Hydrogenation of LaNi5 P6/mmm, up to saturation brings modifications of the crystal structure with two possible space groups for LaNi5H7, i.e. P63mc and P31c, determined experimentally. The energetics from computations within DFT allows pointing to the former as the most favorable one within a doubled cell along the c-axis with respect to LaNi5. Results also show a compensation of the volume expansion effects favorable to the onset of magnetization by the chemical bonding involving Ni–H bond leading to vanishing moments