Enzymatic kinetic resolution of α-hydroxysilanes

The enzymatic kinetic resolution of α-hydroxysilanes where the silicon bears a variety of substituents has been explored. Reactions were performed on various α-hydroxysilanes with several commercially available enzymes, solvents, acetylation reagents, and temperatures. The resulting optically active α-hydroxysilanes and their corresponding acetates were obtained in varying yields and ees.     

Surgénérateurs ; l'état des matériaux aux hautes irradiations, hautes puissances locales et températures, leurs gradients et propriétés mécaniques adaptées aux contraintes qui en résultent

The motivations to realize nuclear breeder reactors are developed in the present context of a strong growth in electronuclear power stations in many countries, using mostly moderated and water cooled reactors.The past studies can be of a substantial profit in France and, to a lesser degree, in other countries of the EU. However, to use fully the 238 uranium isotope, the materials for these breeders must withstand much harder radiation than those for water reactors. The power densities and thermal gradients will also be much more intense. The mechanical stresses, both static and dynamic, will be large and will act on materials with altered mechanical properties. Fuel elements will have to be produced with materials already irradiated several times and therefore showing such alterations.A field of studies concerning materials and their mechanical behavior in new and severe conditions is sketched here, both in construction and working conditions, together with proposed necessary instrumentation and research orientations.     

A new nonlinear-wave-equation formalism for stimulated Brillioun scattering

A revised formalism of SBS is given based on a new optical nonlinear wave equation which explicitly accounts for the macroscopic spatial inhomogeneity resulting from the induced acoustic wave in the medium. The new equation applies to other scattering phenomena, and more generally to optical wave propagation and interaction in nanostructured media for which characteristic spatial scale lengths of material structures (existing or optically induced) are smaller than the optical wavelength.