Anisotropic 3D delay-damage model to simulate concrete structures

International audienceHigh dynamic loadings lead to material degradation and structural failure. This is even more the case for concrete structures where the parts initially in compression break in ten- sion due to waves propagation and reflection. The dissymmetry of the material behavior plays a major role in such cases, dissymmetry mainly due to damage induced anisotropy. Loading induced damage is most often anisotropic and one proposes here to take advantage of such a feature to build a damage model for concrete, dissymmetric in tension and in compression, 3D, suitable for dynamic computations. A single 2nd order tensorial damage variable D is consid- ered with a damage law ensuring a damage rate proportional to the square of the positive part of the strain tensor. One focus in the present work on viscous regularizations for the anisotropic damage model proposed, regularizations of Norton-Perzyna type. Numerical examples of dy- namic failures illustrate the ability and the efficiency of the model to deal with 3D structures

Rate enhancement of the catechol oxidase activity of a series of biomimetic monocopper(II) complexes by introduction of non-coordinating groups in N-tripodal ligands

International audienceAsymmetrical N-tripodal ligands have been synthesized in three steps. Diversity has been introduced at the first step of the synthesis by adding pyrazine, pyridine, benzyl and thiophene rings. The corresponding CuII complexes have been prepared by reaction with CuCl2 and characterized by Electron Paramagnetic Resonance (EPR), UV-Vis spectroscopies and cyclic voltammetry. The data show that the ligand coordinates to CuII in a mononuclear fashion in solution and that the complexes display a square pyramidal geometry. All complexes are characterized by a quasi-reversible one-electron redox behavior in acetonitrile. The ability of the complexes to oxidize 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone has been studied and the results show that the rate of the reaction depends on the basicity and the steric hindrance of the heterocyclic donor. Best results have been obtained with CuII complexes coordinated to bidentate ligands, since they facilitate the approach and the coordination of catechol to the metal. Particularly, the introduction of a thiophenyl group to mimic the sulfur atom at proximity to the catalytic center in the catechol oxidase protein structure improves the catalytic activity of the complex

1H NMR and fluorescence studies of the complexation of DMPG by wheat non-specific lipid transfer protein. Global fold of the complex

AbstractPlant non-specific lipid transfer proteins (LTPs) are proteins which transfer lipids between membranes in vitro and are believed to be involved in the transport of cutin monomers to the cuticle layer in vivo or in the plant defence against phytopathogens. The complexation of DMPG, a diacyl phospholipid, by wheat ns-LTP, a protein extracted from wheat seeds, was followed by 1H NMR and fluorescence spectroscopy. The global fold of the protein was calculated using the DIANA software package from a list of 968 distance constraints. The internal cavity volume, a feature common to all known ns-LTP structures, was estimated to be 750 Å3 using the `CAVITE' program. This model of the complex was obtained by inserting a lipid molecule in the cavity and was energy minimized. The study showed that the protein fold described for the free form was only weakly affected by the insertion of the bulky lipid. Observation of some intermolecular NOEs between the protein and the lipid glycerol moiety revealed that the cavity entrance was located between residues His35 and Arg44. The resulting solution structure was compared to the crystal structure of the maize ns-LTP/palmitate complex

Les représentations climatiques dans la presse française (analyses sémiologiques et sémiotiques comparées de discours médiatiques, scientifiques et profanes)

Proposant une approche méthodologique fondée sur la sémiologie des indices et la sémiotique narrative, notre travail doctoral sous convention CIFRE pour EDF R&D s attache à comprendre le fonctionnement structural et narratif des représentations du changement climatique dans différentes sphères sociales en France. Partant du caractère scientifique de l Objet de recherche, l étude s intéresse aux discours forgés par les climatologues, la presse de vulgarisation scientifique, trois titres de la presse quotidienne nationale et les discours profanes au travers d entretiens collectifs, selon une temporalité commune, de novembre 2009 à mars 2010. La Une des quotidiens et des magazines de vulgarisation scientifique est alors considérée comme un marqueur social et historique fort, capable de construire les représentations relatives au changement climatique. Le corpus de presse d information fonde les représentations tant du phénomène climatique que des événements médiatiques qui lui donnent une existence. Le recours à la sémiotique narrative permet une comparaison de corpus de natures différentes, afin de prendre la mesure de la circulation entre les différentes sphères sociales visitées. L objectif étant une compréhension globale des représentations climatiques, permettant une réflexion sur les mythes dont nos sociétés se nourrissent pour se construire, et sur le possible ré-enchantement de ces mythes.This doctoral research, conducted through a CIFRE agreement with EDF R&D, aims to understand the structural and narrative organization of climate change representations through four different social spheres in France. First considered as a scientific topic, climate change representations are analysed throughout climate scientists and profane discourses, but also throughout documents such as science popularization magazines and three French newspapers, which of the front pages are considered as a social and historical tracer, particularly during the period running from November 2009 to March 2010. Informative press corpus enables to construct representations of global warming and of the media events that participate to their media life. The use of narrative semiotic methodology allows a comparative study through the different corpuses, in order to spot out the hypothetical circulation of these representations. The eventual aim is a global understanding of climate representations, opening the way for a consideration of the different myths as a basement of our societies, willing to reinvent themselves through new social and cultural myths.PARIS5-Bibliotheque electronique (751069902) / SudocSudocFranceF

Environmental Impacts of Solar Thermal Systems with Life Cycle Assessment

Available on: http://www.ep.liu.se/ecp/057/vol14/002/ecp57vol14_002.pdfInternational audienceSolar thermal systems are an ecological way of providing domestic hot water. They are experiencing a rapid growth since the beginning of the last decade. This study characterizes the environmental performances of such installations with a life-cycle approach. The methodology is based on the application of the international standards of Life Cycle Assessment. Two types of systems are presented. Firstly a temperate-climate system, with solar thermal collectors and a backup energy as heat sources. Secondly, a tropical system, with thermosiphonic solar thermal system and no backup energy. For temperate-climate systems, two alternatives are presented: the first one with gas backup energy, and the second one with electric backup energy. These two scenarios are compared to two conventional scenarios providing the same service, but without solar thermal systems. Life cycle inventories are based on manufacturer data combined with additional calculations and assumptions. The fabrication of the components for temperate-climate systems has a minor influence on overall impacts. The environmental impacts are mostly explained by the additional energy consumed and therefore depend on the type of energy backup that is used. The study shows that the energy pay-back time of solar systems is lower than 2 years considering gas or electric energy when compared to 100% gas or electric systems

A dietary supplementation with leucine and antioxidants is capable to accelerate muscle mass recovery after immobilization in adult rats

Prolonged inactivity induces muscle loss due to an activation of proteolysis and decreased protein synthesis; the latter is also involved in the recovery of muscle mass. The aim of the present work was to explore the evolution of muscle mass and protein metabolism during immobilization and recovery and assess the effect of a nutritional strategy for counteracting muscle loss and facilitating recovery. Adult rats (6-8 months) were subjected to unilateral hindlimb casting for 8 days (10-18) and then permitted to recover for 10 to 40 days (R10-R40). They were fed a Control or Experimental diet supplemented with antioxidants/polyphenols (AOX) (10 to 18), AOX and leucine (AOX + LEU) (18 to R15) and LEU alone (R15 to R40). Muscle mass, absolute protein synthesis rate and proteasome activities were measured in gastrocnemius muscle in casted and non-casted legs in post prandial (PP) and post absorptive (PA) states at each time point. Immobilized gastrocnemius protein content was similarly reduced (-37%) in both diets compared to the non-casted leg. Muscle mass recovery was accelerated by the AOX and LEU supplementation (+6% AOX+LEU vs. Control, P<0.05 at R40) due to a higher protein synthesis both in PA and PP states (+23% and 31% respectively, Experimental vs. Control diets, P<0.05, R40) without difference in trypsin-and chymotrypsin-like activities between diets. Thus, this nutritional supplementation accelerated the recovery of muscle mass via a stimulation of protein synthesis throughout the entire day (in the PP and PA states) and could be a promising strategy to be tested during recovery from bed rest in humans

Introgression reshapes recombination distribution in grapevine interspecific hybrids

In grapevine interspecific hybrids, meiotic recombination is suppressed in homeologous regions and enhanced in homologous regions of recombined chromosomes, whereas crossover rate remains unchanged when chromosome pairs are entirely homeologous