Une recherche partenariale appuyant l'évolution de la réglementation : Un cas délicat de dimensionnement d'évent pour le stockage de peroxydes organiques

National audienceLes dangers présentés par les peroxydes organiques sont très variés, et dans tous les cas, le risque d'emballement thermique, avec explosion pneumatique du contenant est à considérer. Dans le cas étudié, le danger de déflagration ou d'explosion pneumatique éliminé au niveau du stockage mère par l'emploi d'un emballage plastique de 35 litres peu résistant, réapparaît au cœur même de l'unité de polymérisation utilisant le peroxyde, car le concepteur a prévu un stockage tampon en cuve inox d'environ 1 m3 . La préparation de ditertiobutylperoxyde (DTBP) peut donner lieu à une explosion en phase gazeuse même sous azote, induisant éventuellement une déflagration de la phase liquide. Plus classiquement, on doit tenir compte du scénario d'emballement thermique du stockage menant à l'éclatement de la cuve, suite à un incendie extérieur ou à un auto-échauffement. Nous avons réalisé des essais à l'échelle de 0,8 - 10 et 20 litres, en modifiant des méthodes normalisées ou recommandées internationalement ; une évolution de ces méthodes sera proposée dans le futur. Nous avons pu ainsi étudier le couplage entre 'explosion en phase gazeuse et l'emballement thermique de la phase liquide pour le DTBP, et proposer au vu des résultats des recommandations pour réduire dès la conception de l'installation l'apparition de ce phénomène, tout en limitant la violence de l'emballement thermique s'il apparaît. La présente étude a aussi permis de contribuer à mieux comprendre comment établir le projet d'arrêté pour les cas très différents du stockage et de l'usage des peroxydes, dans le contexte de la révision de la nomenclature et les arrêtés relatifs au stockage et à l'utilisation des peroxydes organiques, au titre des Installations Classées pour la Protection de l'Environnement (ICPE)

Merremia pterygocaulos (Choisy) Hallier f. : une espèce indigène méconnue et non revue à La Réunion depuis le 19ème siècle… (Convolvulaceae)

La présence de <i>Merremia pterygocaulos</i> à la Réunion est attestée et si on se réfère aux flores existantes et à sa répartition mondiale, nous postulons qu’il s’agit d’une espèce indigène très rare pour La Réunion

Impact of the severity of negative energy balance on gene expression in the subcutaneous adipose tissue of periparturient primiparous Holstein dairy cows: Identification of potential novel metabolic signals for the reproductive system

The severity of negative energy balance (NEB) in high-producing dairy cows has a high incidence among health diseases. The cow's energy status during early lactation critically affects metabolic and reproductive parameters. The first objective of this study was to investigate by RNA-seq analysis and RT-qPCR the gene expression profile in white adipose tissue and by gene ontology and upstream regulation tools the relationships with energy metabolism and reproduction in two groups of primiparous dairy cows with extreme NEB statuses (NEB < -9 Mcal/day vs. NEB > -9 Mcal/day) around parturition. The second objective was to determine the potential involvement of a new adipokine identified as a candidate for the regulation of ovarian function in our RNA-seq analysis by using bovine primary granulosa culture, thymidine incorporation to determine cell proliferation and ELISA assays to measure progesterone secretion. The RNA-seq analysis revealed that 514 genes were over-expressed and 695 were under-expressed in the adipose tissue of cows with severe NEB (SNEB) and cows with moderate NEB (MNEB) during the -4 and 16 wkpp period. In addition, 491 genes were over-expressed and 705 genes were under-expressed in the adipose tissue of SNEB cows compared to MNEB cows. Among these differently expressed genes (DEGs), 298 were related to metabolic functions and 264 to reproductive traits. A set of 19 DEGs were validated by RT-qPCR, including CCL21 (C-C motif chemokine ligand 21). Moreover, CCL21, a gene known to be secreted by adipose tissue, was chosen for further analysis in plasma and ovaries. The use of next-generation sequencing technologies allowed us to characterise the transcriptome of white adipose tissue from primiparous cows with different levels of NEB during lactation. This study highlighted the alteration of the expression of genes related to lipid metabolism, including CCL21, which is released in the bloodstream and associated with the in vitro regulation of ovarian functions

Clostridium perfringens Epsilon Toxin Targets Granule Cells in the Mouse Cerebellum and Stimulates Glutamate Release

Epsilon toxin (ET) produced by C. perfringens types B and D is a highly potent pore-forming toxin. ET-intoxicated animals express severe neurological disorders that are thought to result from the formation of vasogenic brain edemas and indirect neuronal excitotoxicity. The cerebellum is a predilection site for ET damage. ET has been proposed to bind to glial cells such as astrocytes and oligodendrocytes. However, the possibility that ET binds and attacks the neurons remains an open question. Using specific anti-ET mouse polyclonal antibodies and mouse brain slices preincubated with ET, we found that several brain structures were labeled, the cerebellum being a prominent one. In cerebellar slices, we analyzed the co-staining of ET with specific cell markers, and found that ET binds to the cell body of granule cells, oligodendrocytes, but not astrocytes or nerve endings. Identification of granule cells as neuronal ET targets was confirmed by the observation that ET induced intracellular Ca2+ rises and glutamate release in primary cultures of granule cells. In cultured cerebellar slices, whole cell patch-clamp recordings of synaptic currents in Purkinje cells revealed that ET greatly stimulates both spontaneous excitatory and inhibitory activities. However, pharmacological dissection of these effects indicated that they were only a result of an increased granule cell firing activity and did not involve a direct action of the toxin on glutamatergic nerve terminals or inhibitory interneurons. Patch-clamp recordings of granule cell somata showed that ET causes a decrease in neuronal membrane resistance associated with pore-opening and depolarization of the neuronal membrane, which subsequently lead to the firing of the neuronal network and stimulation of glutamate release. This work demonstrates that a subset of neurons can be directly targeted by ET, suggesting that part of ET-induced neuronal damage observed in neuronal tissue is due to a direct effect of ET on neurons

Spécification d'exigences physico-physiologiques d'interaction homme-machine en ingénierie système

10 pagesNational audienceLes travaux exploratoires relatés dans le présent article portent sur la spécification d'exigences physico-physiologiques mesurables afin de mieux prendre en compte ce type de facteurs humains en ingénierie d'un système technique contrôlé par un humain. Le cas d'étude qui sert de fil conducteur tout au long de cet article est celui du contrôle par divers opérateurs d'un mécanisme de sécurisation satisfaisant une exigence opérationnelle de fermeture verrouillée de la porte d'accès à un équipement lors de la clôture d'une intervention de maintenance pour remise en condition opérationnelle d'un appareil. Ce processus de spécification combine dans un premier temps un cadre de Modélisation Système avec celui Mathématique et Computationnel de la Physiologie Intégrative . Cette spécification d'une interaction de perception est vérifiée dans un deuxième temps par exécution de modèles "SysML" interopérant avec des modèles physico-physiologiques en ingénierie d'un système support de maintenance dans notre cas d'étude

Epsilon toxin from Clostridium perfringens acts on oligodendrocytes without forming pores, and causes demyelination.

Epsilon toxin (ET) is produced by Clostridium perfringens types B and D and causes severe neurological disorders in animals. ET has been observed binding to white matter, suggesting that it may target oligodendrocytes. In primary cultures containing oligodendrocytes and astrocytes, we found that ET (10(-9) M and 10(-7) M) binds to oligodendrocytes, but not to astrocytes. ET induces an increase in extracellular glutamate, and produces oscillations of intracellular Ca(2+) concentration in oligodendrocytes. These effects occurred without any change in the transmembrane resistance of oligodendrocytes, underlining that ET acts through a pore-independent mechanism. Pharmacological investigations revealed that the Ca(2+) oscillations are caused by the ET-induced rise in extracellular glutamate concentration. Indeed, the blockade of metabotropic glutamate receptors type 1 (mGluR1) prevented ET-induced Ca(2+) signals. Activation of the N-methyl-D-aspartate receptor (NMDA-R) is also involved, but to a lesser extent. Oligodendrocytes are responsible for myelinating neuronal axons. Using organotypic cultures of cerebellar slices, we found that ET induced the demyelination of Purkinje cell axons within 24 h. As this effect was suppressed by antagonizing mGluR1 and NMDA-R, demyelination is therefore caused by the initial ET-induced rise in extracellular glutamate concentration. This study reveals the novel possibility that ET can act on oligodendrocytes, thereby causing demyelination. Moreover, it suggests that for certain cell types such as oligodendrocytes, ET can act without forming pores, namely through the activation of an undefined receptor-mediated pathway.journal articleresearch support, non-u.s. gov't2015 Mar2014 10 31importe

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good