45 research outputs found
Neutralising Antibodies against Ricin Toxin
The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this purpose, mouse monoclonal antibodies (mAbs) were produced against the two chains of ricin toxin (RTA and RTB). Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro. Three of these, two anti-RTB (RB34 and RB37) and one anti-RTA (RA36), when used in combination improved neutralising capacity in vitro with an IC50 of 31 ng/ml. Passive administration of association of these three mixed mAbs (4.7 ”g) protected mice from intranasal challenges with ricin (5 LD50). Among those three antibodies, anti-RTB antibodies protected mice more efficiently than the anti-RTA antibody. The combination of the three antibodies protected mice up to 7.5 hours after ricin challenge. The strong in vivo neutralising capacity of this three mAbs combination makes it potentially useful for immunotherapeutic purposes in the case of ricin poisoning or possibly for prevention
Nanostructures et électrochimie (préparation et propriétés de structures silicium / platine)
PARIS-BIUSJ-ThĂšses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
SynthÚse par dépÎt de couches atomiques et caractérisations de couches minces d'oxyde de vanadium applications aux accumulateurs au lithium
PARIS-BIUSJ-ThĂšses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
Ătude de la tension de dĂ©composition de HF sur Ă©lectrode de carbone dans un bain 2 HF, KF
Nous dĂ©terminons la tension rĂ©versible de dĂ©composition EHF de l'acide fluorhydrique dans le milieu 2 HF, KF par un calcul thermodynamique utilisant la pression de vapeur de HF au-dessus du bain et lâenthalpie libre de formation de HF (gaz) dĂ©duite de donnĂ©es spectrales. Nous proposons une expression analytique de EHF en fonction de la tempĂ©rature et du pourcentage pondĂ©ral en HF.
Lâexploitation de courbes courant-tension fournit alors une valeur du courant d'Ă©change i0 = 10-7 A/cm2 et le coefficient de transfert α = 0,27 Ă 85 °C
Transformations de lâinterface dâune anode de carbone dans lâĂ©lectrolyte 2HF-KF
Le comportement des anodes de carbone dans lâĂ©lectrolyte fondu 2HF-KF sâinterprĂšte par la formation dâune couche passivante de composĂ©s carbone-fluor solides.
La voltammĂ©trie cyclique fait apparaĂźtre un pic de passivation Ă un potentiel infĂ©rieur Ă celui de la formation du fluor. La chronoampĂ©romĂ©trie montre que la cinĂ©tique de croissance de la couche est conforme Ă la thĂ©orie de Mott-Cabrera avec un coefficient dâinterdiffusion : D â 4,5 Ă 10 â14cm2.sâ1.
Lors des mesures dâimpĂ©dance, la forte diminution du terme capacitif est liĂ©e Ă la croissance de lâĂ©paisseur du film de diĂ©lectrique
Comportement électrochimique des électrodes de carbone en milieu KF,xHF; influence de l'acidité de l'électrolyte et de la température
La formation d'une couche passivante sur les anodes de carbone dans l'électrolyte KF,xHF obéit à une loi de surtension ohmique; l'insertion des espÚces fluorées dans la matrice carbonée est d'autant plus facile que leur concentration est importante (électrolytes acides) et que la température est élevée.Les expériences réalisées en chronopotentiométrie et voltammétrie cyclique ont permis de mettre en évidence l'influence de l'acidité et de la température des bains KF,xHF sur le comportement électrochimique des électrodes de graphite, dans le domaine de température compris entre 80 et 125 °C et pour un pourcentage pondéral en HF variant de 38 à 44. En particulier, on note en voltammétrie cyclique une augmentation de l'intensité du pic de passivation lorsque l'un de ces deux paramÚtres augmente. Les résultats sont conformes aux prévisions du modÚle théorique développé antérieurement et font ressortir l'influence de la conductivité de l'électrolyte qui est corrélée à son acidité et à sa température
Influence de lâinsertion de cations Li
Nous avons montrĂ© que la rĂ©duction des fluorures de graphite en solvant non-aqueux est dâautant plus facile Ă rĂ©aliser que la concentration en cations Li+ dans lâĂ©lectrolyte est importante. Cette propriĂ©tĂ© qui a dâimportantes consĂ©quences dans le processus Ă©lectrolytique de production du fluor a Ă©tĂ© dĂ©montrĂ©e par des expĂ©riences de voltammĂ©trie cyclique dans lâĂ©lectrolyte fondu KF-2HF et au moyen de la technique de lâĂ©lectrode Ă pĂąte de carbone dans le carbonate de propylĂšne, solvant frĂ©quemment utilisĂ© dans les piles Ă haute densitĂ© dâĂ©nergie Li/CFX. Les performances de ces derniĂšres sont comparĂ©es Ă celles de quelques piles Li/polymĂšre conducteur rĂ©cemment dĂ©crites dans la littĂ©rature
A realistic Greenland ice sheet and surrounding glaciers and ice caps melting in a coupled climate model
International audienceGreenland ice sheet experienced an intensive melting in the last century, especially in the 1920s and over the last decades. The supplementary input into the ocean could disrupt the freshwater budget of the North Atlantic. Simultaneously, some signs of a recent weakening of the Atlantic Meridional Overturning Circulation (AMOC) have been reported. In order to better understand the possible impact of the increasing melting on the North Atlantic circulation, salinity and temperature trends, we construct an observation-based estimate of the freshwater fluxes spanning from 1840 to 2014. The estimate is based on runoff fluxes coming from Greenland ice sheet and surrounding glaciers and ice caps. Input from iceberg melting is also included and spatially distributed over the North Atlantic following an observed climatology. We force a set of historical simulations of the IPSL-CM6A-LR coupled climate model with this reconstruction from 1920 to 2014. The ten-member ensemble mean displays freshened and cooled waters around Greenland, which spread in the subpolar gyre, and then towards the subtropical gyre and the Nordic Seas. Over the whole period, the convection is reduced in the Labrador and Nordic Seas, while it is slightly enhanced in the Irminger Sea, and the AMOC is weakened by 0.32±0.35 Sv at 26â N. The multi-decadal trend of the North Atlantic surface temperature obtained with the additional freshwater forcing is slightly closer to observations than in standard historical simulations, although the two trends are only different at the 90% confidence level. Slight improvement of the Root Mean Square Error with respect to observations in the subpolar gyre region suggests that part of the surface temperature variability over the recent decades may have been forced by the release of freshwater from Greenland and surrounding regions since the 1920s. Finally, we highlight that the AMOC decrease due to Greenland melting remains modest in these simulations and can only explain a very small amount of the 3±1 Sv weakening suggested in a recent study
Formation and physicochemical properties of composite PbO2 materials
International audienceThere is a great interest in the improvement of lead dioxide based materials for use in different applications. Some metal ions present in the Pb(II) deposition solution are well incorporated into the PbO2 matrix during electrodeposition (for example Bi3+, Fe3+, F-) to produce a doped oxide with improved reactivity and stability in comparison with pure PbO2 [1-3]. In comparison, there is much less information on effects of polyelectrolytes and surfactants additives on the process of oxide electrodeposition and the physicochemical properties of the resulting materials [4-6]. In the present work we used some polyelectrolytes (Nafion, Drimax 1235, Magnafloc, gelatin, polyamino guanidinehydrochloride) and surfactants (potassium salt of nonafluoro-1-butanesulfonic acid, sodium dodecylsulphate, sodium lauretsulphate) as electrolyte additives for electrosynthesis of composite materials oxide-polyelectrolyte and oxide-surfactant