Modeling of structures of poly(oxyhexaorganocyclotetrasiloxy-2,6-diyl) mesophases

The idealized liquid-crystal structures of two cyclolinear organosilicon polymers, viz., poly(oxyhexaorganocyclotetrasiloxy-2,6-diyls), where the alkyl substituent is Et (1b) or Pr (1c), were modeled. The columns of monomer units in polymers have different conformations, viz., a distorted long boat in 1b and a distorted long chair in 1c. Both polymers have columnar structures with the most probable antiparallel arrangement of the columns.     

Solving some problems in the theory of thin shells of revolution with complex boundary conditions

An approach is proposed to solving linear boundary-value problems for shells of revolution that are closed in the circumferential direction, with complex boundary conditions in which the coefficients of the solving functions depend on the circumferential coordinate. The approach relies on reduction of the boundary-value problem to a number of boundary-value problems for systems of ordinary differential equations and systems of algebraic equations. We solve a specific problem for the stressed state of a conical shell with one of its ends supported by an elastic foundation with a variable modulus.Institute of Mechanics, Ukrainian Academy of Sciences. Translated from Vychislitel'naya i Prikladnaya Matematika, No. 68, pp. 85–93, 1989.     

Synthesis and Transformations of 2-Hydroxy-3-arylazo-1,4-naphthoquinones

A series of 2-hydroxy-3-arylazo-1,4-naphthoquinones were prepared by coupling of 2-hydroxy-1,4-naphthoquinone with aryldiazonium chlorides. The reactivity of the products toward electrophilic and nucleophilic agents was studied. In reaction with o-phenylenediamine they give condensation products, the corresponding benzo[a]phenazines.     

New synthesis of imidazo[4,5-e][1,3]diazepine

A new approach has been implemented in the synthesis of imidazo-[4,5,-e][1,3]diazepines consisting in the cyclization of 4,5-di-(cholormethyl)imidazole by urea derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1193–1195, September, 1993.     

Diffusion coefficients of lithium chloride and potassium chloride in hydrogel membranes derived from acrylamide

Diffusion of non-associated electrolytes (potassium chloride and lithium chloride) in concentrated aqueous solutions (0.1-1.0 mol dm⁻³) has been studied in hydrogels derived from acrylamide and methyl methacrylate to study the mechanism of electrolyte transport. The preparation of two gels with different monomer ratio compositions resulted in obtaining membranes of substantially different hydrophilic character with polymer fractions of 0.3 and 0.5.Cukier hydrodynamic model was applied to explain the dependence of the diffusion coefficients of KCl and LiCl on the electrolyte concentration in hydrogel obtained experimentally. It was shown that the increase of the diffusion coefficients is accompanied with a decrease of the mean distance of approach of the ions. This can be explained by the formation of ion-pairs, resulting in a further contribution to diffusion once there is a decrease in the hydrodynamic resistance of the medium to the diffusing particles. Parameters, which characterise such a behaviour quantitatively, are different for different electrolytes and depend on water content in the gel.     

QSPR modeling of critical properties of organic binary mixtures

QSPR models for the critical temperatures, critical volumes, and critical pressures of binary organic mixtures are given. The binary organic mixtures have been described in terms of the mixture modification of simplex representation of molecular structure. The accuracy of the obtained models is comparable to the recommended one, the mean error ranging from 6.8 to 14.6%. The models imply that electronic polarizability is the most important factor for the critical volume and that the critical temperature and critical pressure are determined primarily by van der Waals and electrostatic interactions.     

Calculation of the spectroscopic characteristics of the dimers of alkali elements on the basis of a model perturbation theory

Based on pseudopotential approach within the model, formally accurate perturbation theory of the Rayleigh–Schrödinger type with a zero-approximation priming potential, a problem of calculation of some alkaline diatomic molecules is considered in homo- and heteronuclear variants of Na₂ and RbM (M=Na, Li, K, Rb, Cs). The results of calculation of the energy parameters, in particular, the dissociation energies, are given; some of the data were obtained for the first time. The results of the calculation for the energies of Rydberg states $n^1 \sum\nolimits_g^ + {(n = 4 - 6)} $ and spectroscopic constants of the Na dimer are given. The calculation demonstrated the important role, in attainment of acceptable accuracy, of two basic 2nd order effects in the theory of perturbations, i.e., the effect of polarization interaction of valence particles through the core and the effect of their screening by one another. For Rydberd states, the contribution of core excitations turns out to be important.