MNDO/HB study of proton transfer in the condensed phase of H2O including medium effects in the combined “supermolecule and pseudocontinuum” model

N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 1, pp. 24–30, January–February, 1992.     

Unconditional exponential bases in Bergman spaces

It is proved that unconditional exponential bases cannot be constructed in the Bergman space B ₂(D) in the case when D is a bounded convex domain in the plane such that at least at one point of its boundary the curvature exists and is different from zero.     

Synthesis of Unsaturated Carboxylic and Amino Acids of Adamantane Series with the Use of Organophosphorus Reagents

Sodium derivative of diethyl(3-amino-1-ethoxycarbonylpropane)phosphonic acid was obtained by reaction of triethyl phosphonoacetate with ethylene imine in the presence of sodium hydride. The compound obtained was brought into Horner-Emmons reaction with carbonyl derivatives of adamantane series to afford the corresponding unsaturated amino acids. From adamantanecarbonyl chlorides and triphenylphosphonium ethoxycarbonylmethylide were prepared new phosphorus acylylides that on thermolysis provide ethyl acetylenecarboxylates containing an adamantyl substituent.     

Theory of superfluidity of nuclear matter based on the Fermi-liquid approach

This paper discusses how an electromagnetic field consisting of a superposition of a constant magnetic field and a field of laser type can affect nuclear beta decay. In general it is not assumed that the intensities of the two types of fields are small compared to the characteristic field H _cr*=β ₁ H _cr, where H _cr=m ² c ³/eℏ and the quantity β ₁ depends on the energy liberated in the decay and the configuration of the electromagnetic field. For nonrelativistic decays the quantity β ₁ is found to be of the same order as the maximum kinetic energy of an electron referenced to its rest energy β ₁∼I≪1. It is assumed that the frequency of the wave field satisfies ℏω/mc ²⩽I. The behavior of the probability for the process is studied over a wide range of the fundamental parameters that characterize the fields. Corresponding asymptotic expressions are derived in the “weak”-and “strong”-field regimes. Also discussed are so-called interference corrections to the unperturbed decay probability, which cannot in principle be studied by the methods of perturbation theory. It is shown that the times and distances that are important in generating these contributions exceed the parameters of the unperturbed processes, just as in the case of a plane-wave field previously investigated in detail by Nikishov and Ritus. However, in contrast to the case of a pure wave field, when a system is simultaneously subjected to a constant magnetic field and a wave field, the degree to which these characteristic regions are enlarged can depend not only on the intensities of the electromagnetic fields but also on their rates of change, even in the limit in which the wave field is slowly varying. Zh. éksp. Teor. Fiz. 111, 3–24 (January 1997)     

Triterpene glycosides ofAstragalus and their genins. XXI. Circular dichroism of cycloartane ketones

The CD spectra of a number of natural and synthetic cycloartane ketones have been studied. The influence of 6α-hydroxy group on the Cotton effect due to a 3-keto function has been found. The Cotton effect has been determined for 6-oxo-and 11-oxocycloartanes.     

Triterpenoids of the cycloartane series

In this review on triterpenoids of the cycloartane series, new achievements in this field of natural compounds are considered, the literature up to 1983 and, in part, 1984 being covered.     

Triterpene glycosides of Astragalus and their genins. XXXI. Cycloorbigenin B from Astragalus orbiculatus

Chemistry of Natural Compounds - A new methylsteroid of the cycloartane series has been isolated from the epigeal part ofAstragalus orbiculatus Ledeb. (Leguminosae); it has the structure of a...