Low temperature specific heat of dense kondo ferromagnets and intermediate valence CeNixPtt-x compounds

Specific heat measurements performed in the temperature range 1.5 to 30 K in the compounds CeNi_xPt_{1 - x} with x = 0.5, 0.8 and 0.95 are presented. The analysis of the magnetic entropy enhances the results obtained previously by magnetic measurements: i) the reduction of the cerium moment due to the Kondo effect; ii) the increase of the importance of the Kondo effect in competition with the RKKY interactions when Pt is replaced by Ni. The variation of γ along the series indicates a maximum around x = 0.9 which corresponds to the magnetic instability. It is worth noting that below T_c in the ferromagnetic compounds, C_mag follows a T law, characteristic of magnon dispersion.     

Instabilité d'une nappe de vorticité étirée instationnaireInstability of an unsteady stretched vortex layer

We consider how the Kelvin–Helmholtz instability is affected by an external hyperbolic strain flow. The basic flow being unsteady, the inviscid evolution of perturbations is studied within the framework of a non-normal analysis in which the maximum amplification is computed for any given time. A positive or negative stretching is shown to enhance or reduce, respectively, the instability even for weak stretching rates. To cite this article: T. Gomez, M. Rossi, C. R. Mecanique 331 (2003).     

ZrO2?SiO2 mixed oxides as supports for platinum catalysts

Mixed ZrO₂–SiO₂ oxides were prepared by the sol-gel method and used as supports for platinum catalysts. Activity tests show that Pt/ZrO₂–SiO₂ catalysts can be used in the aromatization of n-heptane.     

Oxidative dehydrogenation of propane over Mo/g-Al2O3. effect of precursor

Alumina supported molybdenum oxide was prepared using ammonium heptamolybdate and molybdenum acetate as different precursors. The catalysts were characterized by BET, AAS, SEM-EDAX, XRD, TPR and surface acidity measurements. The characterization results and the catalytic behavior in oxydehydrogenation of propane were similar irrespective of precursor. This revised version was published online in August 2006 with corrections to the Cover Date.