Study of the sintering and oxidation behavior to the HfB2/SiC system. Synthesis, reactivity and chemical-physical characterization.

International audienceThe first aim of our work consists in synthesizing Ultra High Temperature HfB2/SiC ceramics, used as structural materials in aeronautic and aerospace areas, by Spark Plasma Sintering (SPS). This process is used to obtain fully dense materials (>99% relative density) with fine grains, at lower sintering temperature and shorter dwell time than conventional techniques. Sintered materials are then oxidized in a solar furnace and characterized in order to better understand the oxidation mechanisms

Oxidation Behavior of HfB2-SiC and ZrB2-SiC Ultra-High Temperature Ceramics in different air atmospheres

International audienceUltra-High Temperature Ceramics, in particular diborides of the IVb group, are promising materials for extreme environments, more specifically for thermal protection systems of hypersonic vehicles during their atmospheric reentry at temperatures higher than 1800 °C. The main objective of this work is to study the oxidation behavior in air of (Hf or Zr)B2-SiC composites under severe conditions. The first stage consists in elaborating fully-dense (Hf or Zr)B2-SiC ceramics, from 0 to 30 vol.% SiC, with similar and controlled microstructures using Spark Plasma Sintering to obtain materials with fine grains, high relative density (> 99 %) at lower temperatures and shorter dwell times. An optimization of sintering parameters has been carried out for every composition. The second step consists in understanding the oxidation mechanisms of both composites. To this end, these materials have been oxidized at several temperatures using concentrated solar energy, including the oxidation in atomic oxygen. The mechanisms have been highlighted through the study of the oxidized layers by combining XRD, SEM and Raman spectroscopy with imaging and by the monitoring of oxidation kinetics. This work was helped by a first thermodynamic approach of both systems through the modeling of ternary diagrams

Comprehensive genetic dissection of wood properties in a widely-grown tropical tree: Eucalyptus

Background: Eucalyptus is an important genus in industrial plantations throughout the world and is grown for use as timber, pulp, paper and charcoal. Several breeding programmes have been launched worldwide to concomitantly improve growth performance and wood properties (WPs). In this study, an interspecific cross between Eucalyptus urophylla and E. grandis was used to identify major genomic regions (Quantitative Trait Loci, QTL) controlling the variability of WPs. Results: Linkage maps were generated for both parent species. A total of 117 QTLs were detected for a series of wood and end-use related traits, including chemical, technological, physical, mechanical and anatomical properties. The QTLs were mainly clustered into five linkage groups. In terms of distribution of QTL effects, our result agrees with the typical L-shape reported in most QTL studies, i.e. most WP QTLs had limited effects and only a few (13) had major effects (phenotypic variance explained > 15%). The co-locations of QTLs for different WPs as well as QTLs and candidate genes are discussed in terms of phenotypic correlations between traits, and of the function of the candidate genes. The major wood property QTL harbours a gene encoding a Cinnamoyl CoA reductase (CCR), a structural enzyme of the monolignol-specific biosynthesis pathway. Conclusions: Given the number of traits analysed, this study provides a comprehensive understanding of the genetic architecture of wood properties in this Eucalyptus full-sib pedigree. At the dawn of Eucalyptus genome sequence, it will provide a framework to identify the nature of genes underlying these important quantitative traits. (Résumé d'auteur

Prescriptions médicales et iatrogénie médicamenteuse chez le sujet âgé (analyse de cinquante ordonnances de médecine de ville)

La qualité de la prescription médicamenteuse chez les personnes âgées est un enjeu important pour lutter contre la iatrogénie médicamenteuse. La prévalence des maladies chroniques augmente avec l'âge et le nombre de médicaments présents sur les ordonnances des personnes âgées ne cesse lui aussi d'accroître. Après avoir détaillé les causes et les conséquences d'iatrogénie médicamenteuse, nous montrerons grâce à notre travail la présence du risque iatrogène chez les personnes âgées. Pour cela, nous avons analysé cinquante ordonnances de médecine de ville de patients âgés de plus de soixante cinq ans et non institutionnalisés. Le rôle du pharmacien d'officine est primordial dans la prévention du risque thérapeutique médicamenteux. Nous évoquerons avec quels moyens le pharmacien peut lutter contre la iatrogénie médicamenteuse au sein de l'officine.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

Le suivi de reproduction des bovins en France, pratiques des vétérinaires et des éleveurs en 2008

La profession vétérinaire en milieu rural est confrontée à de nombreux changements du monde agricole. Le rôle de vétérinaire a évolué de celui d'urgentiste à celui de conseiller. Mais l'évolution du praticien se heurte à certaines difficultés, notamment à une concurrence importantedans le conseil en élevage. L'enquête de la Société Nationale des Groupements Techniques Vétérinaires a montré que le vétérinaire reste un interlocuteur de choix dans la résolution de problèmes de reproduction, mais que la concurrence des centres d'insémination artificielle reste un obstacle de taille à la mise en place de services de suivi. Une meilleure approche marketing du service proposé et une utilisation généralisée de l'informatique sont les pistes à suivre en priorité pour gagner du terrain dans le domaine du suivi de reproduction.TOULOUSE-EN Vétérinaire (315552301) / SudocMAISONS-ALFORT-Ecole Vétérin (940462302) / SudocSudocFranceF

Les étangs-réservoirs de la Ligne Maginot Aquatique, un socio-écosystème durable ?

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In vitro stimulation of vitellogenin incorporation into trout oocytes by salmon pituitary extracts

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