Sur le groupe de la géométrie hypersphérique

Sans résumé     

Structure des peroxydates obtenus par action de lóxygene moleculaire sur des organometalliques derives du bromure de crotyle

Butenylmagnesium, butenylzinc and butenylaluminium bromides are oxidized at low temperature (?80 and ?100°C). The qualitative and quantitative studies of the reaction products after reduction by PPh₃, LiAlH₄ and n-BuMgBr show that the secondary structure is dominant in the peroxides formed.     

A remarkable accelerating effect of iodide ions in the photostimulated phosphonylation of bromoaromatic compounds

We find that 1 equiv. of NaI greatly accelerates the photostimulated substitution (S_RN¹ mechanism) of bromobenzene, bromotoluenes and bromopyridines by diethylphosphite ion, in acetonitrile/tetrahydrofuran mixtures. Consequently, bromoaromatic compounds are suitable for preparative use.     

Synthesis,Characterization and Photocatalytic Application of TiO<Subscript>2</Subscript>/SnO<Subscript>2</Subscript> Nanocomposite Obtained Under Non-thermal Plasma Condition at Atmospheric Pressure

A plasma-assisted synthesis of TiO₂/SnO₂ nanocomposite is described. In this approach, a precursor containing a mixture of [TiCl₃ and SnCl₂] exposed to electric discharge was oxidized by plasma-generated reactive species (HO^·/H₂O = 2.85 eV/SHE). SnO₂ microstructures with a diameter of 10–40 µm were coated by thin layers TiO₂ nanorods with mean diameter of 6–8 nm. The obtained TiO₂/SnO₂ nanocomposite was characterized by transmission and scanning electron microscopy, X-ray diffraction and Fourier transform infrared. TiO₂/SnO₂ nanocomposite was found to be a promising new material for the photocatalytic discoloration of aqueous Remazol Brilliant Blue-R dye under daylight and UVA light sources, due to the combined effects of large specific surface area and heterojunction which efficiently separates the electron–hole pairs delaying the charge recombination. The leaching test indicated that the nanocomposite is stable easily reusable.     

Effects of nitrogen and alkene substitution on the PtCl2 catalyzed cycloisomerization of N-tethered 1,6-enyne precursors to the triple reuptake inhibitor GSK1360707

The effects of nitrogen and alkene substitution on the cycloisomerization of N-tethered 1,6-enynes into 3-azabicyclo[4.1.0]heptene precursors to the triple reuptake inhibitor GSK1360707 are described. In general, electron donating substituents proved beneficial both in terms of the reaction rate and chemoselectivity.     

Evaluation of Energy Balance in a Batch and Circulating Non-thermal Plasma Reactors During Organic Pollutant Oxidation in Aqueous Solution

Plasma Chemistry and Plasma Processing - This work presents the treatment of an organic waste solution using gliding arc plasma in moist air, which is an excellent source of oxidizing species....     

On the strong liouville property for co-compact Riemannian covers

This note discusses the existence of non-negative non-constant harmonic functions on co-compact covers with linear deck group. Conferenza tenuta da P. Bougerol il 4 ottobre 1993     

Sets of degrees of computable fields

Given a Σ₂ (resp. Σ₁) degree of recursive unsolvability a, a computable field (resp. a computable field with a splitting algorithm)F is constructed in any given characteristic, such that the set of dimensions of all finite extensions ofF has degree a. This is part of an M.Sc. Thesis presented at The Hebrew University. The author wishes to express his indebtedness to his Supervisor Professor H. Gaifman for his constant guidance and encouragement. Thanks are also due to Professor G. Sabbagh (University of Paris VII) for several useful suggestions.     

First enantioselective synthesis and determination of the absolute configuration of natural (+)-dehydro-β-monocyclonerolidol

The enantioselective synthesis and determination of the absolute configuration of (+)-dehydro-β-monocyclonerolidol, a natural product isolated from the liverwort P. subobtusa, has been achieved starting from (+)-karahana lactone as an enantiopure building block. Furthermore, the methodology applied provided a new approach towards the known (+)-γ-cyclohomocitral, a key intermediate in the sequence, and natural (+)-pallescensone.