Use of the CNDO/S method to elucidate the conformation of benzylidene aniline

The present study was aimed at clarifying the conformation of benzylidene aniline with the aid of the CNDO/S method. The non-planarity of benzylidene aniline is clearly established and the estimated deviation, 55°, is consistent with a recent experimental determination. An interpretation of the UV absorption of benzylidene aniline is presented. A linear relationship has been found between the orbital energies and the experimental ionization potentials, but the photoelectronic spectrum does not provide any definite information about the conformational problem.     

Les sous-algebres de Cartan reelles et la frontiere d'une orbite ouverte dans une variete de drapeaux

We show how the non compact imaginary roots of a non compact real semi-simple Lie algebra with respect to a Cartan subalgebra to allows us, alike the real roots of, to give a complete classification of the G-conjugacy classes of Cartan subalgebras of if G_c is a complex connected group whose algebra is the complexified of, if B is a Borel subgroup of G_c and G the analytic subgroup of G_c corresponding to the subalgebra of, we determine the G-orbits of codimension one in the boundary of an open G-orbit of the complex flag manifold G_c/B. If is a maximally compact Cartan subalgebra of contained in, we show how the imaginary non compact simple roots of allows us to determine such orbits.     

The behaviour of a non-differentiable stationary Gaussian process after a level crossing

A model process is obtained for the behaviour of a non-differentiable but continuous stationary Gaussian process after a level crossing. It is shown that the sampled process conditioned on a crossing of a fixed level in Slepian's sense, converges weakly towards the model process, when the sample distance decreases to zero. Further it is noticed that there is no difference between conditioning on a vertical window and on a horizontal window in this case.     

Novel polyhydronaphthalenic structures

Novel 1,7-dihydro- or 1,2,6,7-tetrahydronaphthalene derivatives were obtained from naphthalene through a polysilylation/oxidation process as well as 1,4,6,7-tetrakis(trimethylsily)naphthalene, a regiospecific precursor of 1,4,6,7-tetrafunctional naphthalenes.     

Additions dipolaires-1,3 en serie germaniee: Action de nitrilimines, oxydes de nitrile, et nitrones sur les germanones et germathiones

A new aspect of the reactivity of germanones and germathiones towards nitrilimines, nitriloxides and nitrones is investigated. The regioselectivity of the dipolar 1,3-cycloaddition reactions between germanones or germathiones and diphenylnitrilimine is discussed.

The structure of the adducts is determined from chemical or spectroscopic studies (¹³C NMR, IR).

Germa-oxa- or -thia-diazolines, germaoxathiazoles and germaoxathiazolidines are obtained and the thermal stability of these adducts reported.     

Gel permeation chromatography on polyelectrolytes in aqueous solution

Gel permeation chromatography of water-soluble polymers, with special attention to polyelectrolytes, has been studied. A three-detector system (refractometry, conductimetry, viscometry) is used to characterize the polymers. A single curve is obtained for the calibration of the set of columns taking into account the hydrodynamic volume of the solutes and using a 0.1 N salt solution as the eluent to screen electrostatic forces. The role of the low adsorption of dextran on silica gel is pointed out. The dependence of elution volume on polymer concentration is demonstrated and interpreted in terms of the screening length of the molecules.     

ESR study of second stage nickel chloride graphite intercalation compound

The temperature dependences of g-factor and linewidth of C_11,3NiCl_2,13 single crystals have been measured from 10 to 400 K. The data indicate that nickel ions in graphite behave at low temperatures like Ising ions, with a phase transition occurring at about 30 K.     

Duality in generalized linear fractional programming

We consider a generalization of a linear fractional program where the maximum of finitely many linear ratios is to be minimized subject to linear constraints. For this Min-Max problem, a dual in the form of a Max-Min problem is introduced and duality relations are established.