Rearrangements photochimiques d'α-epoxycetones spiranniques et de composes dicarbonyles; nouvelle etude de la photolyse du benzoyloxy-3-5-cholestene-2; photoepimerisation en 5 de la benzoyl-2-5α-cholestanone-3

The photolysis of epoxides derived from 2 - benzylidène - 5α - cholestan - 3 - one depends considerably on stereochemistry. No photoepimerisation can be detected; expected β diketones are formed. Several tautomeric forms of 2 - benzoyl - 5α - cholestan - 3 - one have been isolated in crystalline form, and some exist in neutral solution. A δ hydrogen abstraction by the benzoyl group is involved in the photolysis of this δ-diketone.     

PHOTOCROISSANCE DE SEGMENTS DE COLEOPTILES D'AVOINE MAINTENUS EN SURVIE-SPECTRES D'ACTION

Résumé— La photocroissance des coléoptiles d'avoine in vitro est contrôlée par le phytochrome. Une thérie est proposée suivant laquelle ce pigment est sensibilisé par les pigments photosynthétiques des coléoptiles.     

A facilities in series capacity constrained dynamic lot-size model

A facilities in series dynamic lot-size model is studied. The model differs from earlier studies involving concave cost functions in the introduction of capacity constraints for production at the last facility. The structure of the optimal solution is characterized. Two algorithms, one involving decomposition the other a one-stage algorithm are presented and compared with respect to their computational efficiency. Only the non backlogging case is considered.     

New Indigo Syntheses. Preliminary Communication

Three novel routes for the preparation of the dyestuff indigo are described. Two of the methods use isatoic anhydride, the third one styrene as starting materials. Key reactions are acylation of both dimsyl and nitromethane anions, Pummerer rearrangement and Nef reaction. A novel nitration of styrene is the basis of the third method.     

Étude théorique d'une électrode tournante à double annfau: Partie III. Simulation d'un courant constant sur l'anneau interne

Digital simulation treatments supposing constant current flowing suddenly imposed across the internal electrode for two rotating systems, the ring-disk and the double ring, are compared. Results are given for a double ring system.     

Reduction electrochimique des sulfures de fer application a la mesure de la non stoechiometrie

Iron sulfides Fe_1?xS are electrochemically reduced in chloride medium, at pH=0.2 according to a dissolution process. The coulometric measurement of the Fe(III) amount in the solid and the evaluation of the Fe²⁺ concentration in the solution after electroreduction lead to the determination of the stoechiometry on an amount of solid lower than one milligramme.     

Absolute Line Intensities and Self-Broadening Coefficients in the nu(1) Band of (35)Cl(12)C(14)N

The self-broadening coefficients and the intensities of 29 lines in the nu(1) band of cyanogen chloride ((35)Cl(12)C(14)N) have been measured at high resolution in the range 699-736 cm(-1), using a tunable diode-laser spectrometer. The collisional widths and most of the intensities are obtained by fitting Voigt and Rautian profiles to the measured shapes of the lines. From the analysis of the line intensities we determine the absolute strength as well as the Herman-Wallis factors for the nu(1) band. A semiclassical calculation of the self-broadening coefficients, performed by considering the main electrostatic interactions only, has provided larger results than the experimental data. Copyright 2001 Academic Press.