Photolyse d'oxazirannes: VI—Détermination par RMN du proton des configurations et conformations privilégiées d'oxazirannes à jonction spirannique

The structures of imines and oxaziridines derived from 2-methyl and 2,6-dimethyl cyclohexanone have been determined by ¹H n.m.r. spectroscopy. The preferred conformation of all the oxaziridines we examined was found to have the nitrogen atom in equatorial position.     

Etude en spectrometrie de masse de la fragmentation de di-O-isopropylidene-1,2-5,6-α-D-hexofurannoses

The mass spectra of three stereoisomeric 1,2-5,6-di-O-isopropylidene-α-D -hexofuranoses have been investigated. Fragmentation mechanisms based upon the results which were obtained with deuterium labelled molecules are proposed.     

N,N′‐Di­methyl‐1,4‐dithiine‐1,2:4,5‐tetracarbox­imide and N,N′‐di­methyl‐1,4‐diselenine‐1,2:4,5‐tetracarbox­imide

The title compounds of sulfur, C₁₀H₆N₂O₄S₂, (I), and selenium, C₁₀H₆N₂O₄Se₂, (II), are isomorphous. The crystallographically centrosymmetric mol­ecules are planar. The bond distances and angles, except for those involving the S and Se atoms, are comparable. The mol­ecules are disposed in layers parallel to the bc plane. The molecular axes differ by 75° for (I) and by 80° for (II) from one layer to the next.     

Local Convergence Analysis of a Primal–Dual Method for Bound-Constrained Optimization Without SOSC

Journal of Optimization Theory and Applications - We propose a local convergence analysis of a primal–dual interior point algorithm for the solution of a bound-constrained optimization...     

Eine Methode zur Darstellung und Bestimmung des Glykogens

Ohne Zusammenfassung     

Ueber die L?slichkeit des frisch gef?llten kohlensauren Kalkes in Ammonsalzen

Ohne Zusammenfassung     

Finiteness theorems for discrete subgroups of bounded covolume in semi-simple groups

Supported by the National Science Foundation during 1986–1988 at the Mathematical Sciences Research Institute, Berkeley, and at the Institute for Advanced Study, Princeton.     

Acetylenic and diacetylenic liquid-crystalline monomers: towards ordered conjugated polymers

Acetylenic and diacetylenic mesomorphic monomers have been prepared in order to obtain long conjugated polymers able to give high non-linear optical hyperpolarizabilities. Here we report the synthesis of such monomers incorporating cholesteryl and methoxybiphenyl groups; their structural and thermal behaviour are described. The occurrence of mesophases in the acetylenic and diacetylenic derivatives is discussed as a function of the spacer length and of the size of the mesogen moiety. The diacetylenic derivatives containing the methoxybiphenyl groups do not exhibit any liquid-crystalline behaviour but are able to polymerize under U.V. radiation.     

Determination of the efficient set in multiobjective linear programming

This paper develops a method for finding the whole set of efficient points of a multiobjective linear problem. Two algorithms are presented; the first one describes the set of all efficient vertices and all efficient rays of the constraint polyhedron, while the second one generates the set of all efficient faces. The method has been tested on several examples for which numerical results are reported.The authors are grateful to Professor W. Stadler and an anonymous referee for their helpful comments and corrections.