A multi-model climate response over tropical Africa at +2 °C

The impact of a +2 °C global warming on temperature and precipitation over tropical Africa is examined, based on an ensemble of 12 regional climate model scenario simulations. These 12 scenarios are re-phased so that they all correspond to the same global warming of 2 °C with respect to pre-industrial conditions. The continental temperature increase is above the global average. If heat waves are defined with the same temperature threshold in the reference climate and in the scenario, their frequency increases by a factor of 10. When the temperature threshold is adapted to future conditions, there is still a slight increase in frequency. The average precipitation does not show a significant response, due to model-to-model spread. However two compensating phenomena occur, which are robust among the models: (a) the number of rain days decreases whereas the precipitation intensity increases, and (b) the rain season occurs later during the year with less precipitation in early summer and more precipitation in late summer. Simulated daily temperature and precipitation data are combined in two impact models, one for the hydrology of the Nile and Niger basins, one for the food security of the different countries. They show that the main feature of the climate change is not a continuous trend signal, but an alternation of dry and wet decadal to multidecadal episodes

Alliin is a suicide substrate of Citrobacter freundii methionine gamma lyase structural bases of inactivation of the enzyme

The interaction of Citrobacter freundii methionine [gamma] lyase MGL and the mutant form in which Cys115 is replaced by Ala MGL C115A with the nonprotein amino acid 2R 2 amino 3 [ S prop 2 enylsulfinyl]propanoic acid alliin was investigated. It was found that MGL catalyzes the [beta] elimination reaction of alliin to form 2 propenethiosulfinate allicin , pyruvate and ammonia. The [beta] elimination reaction of alliin is followed by the inactivation and modification of SH groups of the wild type and mutant enzymes. Three dimensional structures of inactivated wild type MGL iMGL wild type and a C115A mutant form iMGL C115A were determined at 1.85 and 1.45 resolution and allowed the identification of the SH groups that were oxidized by allicin. On this basis, the mechanism of the inactivation of MGL by alliin, a new suicide substrate of MGL, is propose

COMPOSITION, STRUCTURE AND CURRENT CARRYING CAPACITY OF Nb3Sn PHASE IN MULTIFILAMENT SUPERCONDUCTORS

Nous avons étudié les procédés de formation et les propriétés caractéristiques de la composition et de la structure du Nb3Sn formé dans des supraconducteurs multifilamentaires lors d'un recuit entre 700-820°C pendant 200 h. La capacité de transport de courant du matériau cité ci-dessus a été étudiée dans un champ < 18 T. Il a été établi que la meilleure densité de courant critique du Nb3Sn inter-métallique dans des champs magnétiques faibles et élevés est obtenue avec des temps de recuit différents.The study was made into processes of formation and characteristic properties of the composition and structure of Nb3Sn formed in multifilament superconductors during annealing within 700-820°C for up to 200 h. The current carrying capacity of the above materials was studied in the field of < 18 T. It is established that the best critical current density of intermetallic Nb3Sn in low and high magnetic fields is achieved through dissimilar annealing schedules

Development of Cu-Nb alloy microcomposite conductors for high field pulsed magnets. Final report

Primary goal is to develop high strength-high conductivity composite wires with enhanced cross section. The following research areas were started: melting, deformation, TEM, SEM, and mechanical/electrical characterization of in-situ Cu-Nb microcomposites. Consumable arc melting using initial composite electrodes produced by cold deformation was chosen for preparing initial ingots of Cu-(16- 18)wt%Nb alloy. The deformation process including extrusion, drawing with intermediate heat treatments, and rolling was analyzed. Structure of Cu-Nb composite was investigated at all stages of its fabrication. Rebundling was successfully used to manufacture conductors with enhanced cross sections. Wire with 3x7mm{sup 2} cross section and 50m length was produced with UTS (20 C) = 1000 MPa and electroconductivity 70% IACS