Search results for "mécanisme"
showing 10 items of 31 documents
High chromium-carbon’s steel microstructural and properties evolutions after Hot Isostatic Pressing (HIP) process : From powder to final product.
2021
Fe-Cr-C alloys are frequently used as hard coating coatings for nuclear valves in pressurized water reactors (PWRs), due to their good mechanical resistance and corrosion. The Norem02 alloy (Fe - 25% Cr - 4% Ni - 4% Mn - 4% Si - 2% Mo) is one of the most promising candidates. Hardfacing coatings are typically deposited by a plasma transferred arc welding (PTAW) process, which results in a coarse and heterogeneous microstructure, exhibiting unsatisfactory wear resistance properties, mainly at high temperature. In the present study, Norem02 is developed by Hot Isostatic Compression (CIC), a pressure assisted sintering technique where a powder is placed in a plastically deformable container un…
The mechanisms for maintenance of verbal information in working memory
2011
Working memory is a system that allows to maintain information, while performing a concurrent processing. The subvocal rehearsal (Baddeley, 1986) and the attentional refreshing (Barrouillet et al., 2007) are two mechanisms identified as playing a role in maintenance of verbal information within working memory. However, the exact nature of the interplay of these two mechanisms was little studied and remains unclear. Therefore, the purpose of our work was first to investigate the interplay of rehearsal and refreshing. In several experiments performed with young adults, the use of rehearsal and refreshing were respectively manipulated through articulatory suppression and attentional demand of …
How Do French Junior Secondary Schools Operate ? Academic Achievement, Grading and Streaming of Students
1989
International audience; This paper is concerned with the operation of Junior Secondary Schools in France. Students' school careers have been analysed in three sequential and cumulative components: student progress in learning in the junior secondary school, student grading by teachers, and student streaming, i.e., admission, or not, into a general form 3. For each of the three mechanisms described above, the authors examine whether they are influenced by the schooling context, which schooling context (school and/or classroom), and which characteristics of those contexts it is relevant to consider. Finally, they focus on the process by which the large social inequalities visible after the pu…
Supercritical hydrothermal synthesis of ZnO nanopowders beyond the critical point : understanding of nucleation and growth steps
2014
The supercritical hydrothermal synthesis of nanopowders (especially metal oxide) has been widely studied. To the best of our knowledge, no nanoparticle formation mechanism has been published yet. In this prospect, this study is dedicated to the understanding of metal oxide nanoparticle nucleation and growth mechanisms. For this purpose, zinc oxide is used as a model material. First, the influence of synthesis operating conditions such as pressure, temperature, pH, precursor concentrations and solution flow rates on particle morphological properties (size, particle size distribution or morphologies) has been investigated. Hence, two approaches have simultaneously been carried out. The first …
New solutions of preparation and activation of surfaces
2017
Organic coatings applied on the surface of cast iron pipes ensure very good chemical and anti-corrosion protection against aggressive effluents. To improve adherence between coating (epoxy) and substrate, a surface preparation is required. Among conventional processes shot blasting has emerged as the most efficient and cheapest solution for ensuring stripping while generating adapted roughness. However, as it may enhance both mechanical anchorage and chemical bonding a better understanding of these phenomena should be developed. Besides new eco-friendly alternatives were investigated.Indeed, new techniques were evaluated, i.e. laser structuring and an ultra-high pressure water jet whose maj…
Philosophie de la machine, néo-mécanisme et post-humanisme
2013
International audience
Généralités sur la résistance aux Produits de Protection des Plantes (PPP)
2015
SPEPôle GEAPSICT2Communication orale invitée; Au niveau d’un individu, la résistance « biologique » correspond à une moindre sensibilité à un PPP en comparaison d’individus sensibles de référence, mesurée au laboratoire. Un individu résistant peut être caractérisé par son facteur de résistance (l’« intensité » ou la « force » de la résistance, correspondant au rapport entre la quantité de PPP requise pour avoir le même effet sur un individu résistant que sur un individu sensible), et son profil (ou spectre) de résistance (la gamme de substances auquel l’individu sera résistant). Le caractère de résistance est transmis aux générations suivantes de bio-agresseurs, car déterminé par une ou des…
La teneur hépatique en F4-Neuroprostanes : une variable prédictive majeure de la réduction de la plaque d’athérome
2012
Le fichier annexe contient le livre des résumés; Les propriétés athéroprotectrices des acides gras polyinsaturés de type n-3 à longue chaîne (AGPI n-3 LC), et en particulier de l’acide docosahexaénoique (DHA) ont été largement décrites. Néanmoins, les mécanismes d’action restent encore mal connus. Les recherches se sont récemment orientées vers l’identification des métabolites oxygénés issus des AGPI n-3 LC qui sont de plus en plus considérés comme des effecteurs majeurs de leurs effets athéroprotecteurs. Dans ce contexte, une étude dose-réponse de supplémentation en DHA a été réalisée chez un modèle animal d’athérosclérose (souris LDLR-/-) afin d’étudier les relations entre la progression …
La sensibilité à l'astringence en fonction de l'âge est-elle liée aux Protéines Riches en Proline (PRP) de la salive ?
2022
Rôle de la Dynamique Membranaire dans la Mise en Place des Mécanismes de Défense chez le Tabac
2011
Cryptogein, a protein secreted by the oomycete Phytophthora cryptogea, induces defense mechanisms in tobacco. Several proteins involved in the associated signaling pathway were identified and localized on the plasma membrane (PM). A fraction resistant to solubilization by detergent named DIMs for Detergent Insoluble Membranes, enriched in sterols an sphigolipids had been isolated from tobacco PM. It was proved to contain proteins previously identified as actors of the signaling cascade triggered by cryptogein. In animal cells, the dynamic association of proteins to sterol and sphingolipid rich microdomains under the influence of a biological stimulus plays an essential role in the regulatio…