Etudes conformationnelles par Résonance Magnetique Nucléaire et variations de températures d'éthanes di- et trisubstitués

In this paper we report the conformational analysis of several di- or trisubstituted ethanes substituted by the following groups: N-dialkly, thioalkyl, alkoxy, N-pyrrolidino, N-benzyl, nitrile or carbomethoxy. Spectra were calculated by a method based on chemical shifts. Relative stabilities of rotamers were discussed in relation to structural parameters (geometrical and electronic).     

Etude variationnelle d'une double perturbation. Application au calcul des constantes de couplage entre spins nucleaires

The calculation of molecular electronic polarizability tensor components is presented in the CNDO approximation using several methods, on one hand a perturbation calculation, on the other hand a variational method. Results obtained on thirty molecules are used to compare these methods and to discuss their usefulness.

     

Iterations of transformations on the unit interval: Approach to a periodic attractor

We consider a transformation of the unit interval which exhibits a stable periodic attractor and whose topological entropy is positive. We show that the dynamics leading to this attractor has a statistical character.     

Homogeneous and facially homogeneous self-dual cones

We show that any self-dual come in a real finite dimensional Hilbert space is homogeneous iff it is facially homogeneous in the sense of A. Connes. We develop a spectral decomposition theory for these cones which is the analogue of the usual one for self-adjoint operators on a finite-dimensional Hilbert space.     

Biaryles dissymétriques par diformylation et aromatisation de cyclohexén-2 ones.

The classical procedure of formylation of ketones is reinvestigated in order to provide a synthetic route to unsymmetrical biaryls from cyclohexenones.     

Acoustic characteristics of vocal oscillations: Vibrato, exaggerated vibrato, trill, and trillo

Acoustic analysis was performed on recordings of 10 early music singers producing examples of vibrato, exaggerated vibrato, whole-tone trill, and trillo to obtain measures of oscillation rate, frequency extent, and jitter. Oscillation rates for vibrato, exaggerated vibrato, and trill were similar, but trillo rate was much faster. Average frequency extent of oscillation was 1 semitone (st) for vibrato, 2.21 st for exaggerated vibrato, 2.71 st for whole-tone trill, and 1.64 st for trillo. Jitter measures indicated that exaggerated vibrato had the most stable oscillations and trillo the least.     

Amino-nucléosides. V. Amino-3′-didésoxy-3′, 5′-adénosine

A synthesis of 3′-amino-3′, 5′-dideoxyadenosine is described. This compound is not a substrate of adenosine deaminase.