Flow around a flexible cylindrical shell by a plane stream of an ideal liquid

The flow by a plane stream of an ideal liquid around a cylindrical shell of zero flexural stiffness (a soft cylindrical shell), or a gas bubble on the boundary of which forces of tension act, was studied in [1–6]. The flow around an elastic plate in a linear formulation was considered in [7, 8]. We consider the flow, around a flexible cylindrical shell which possesses a flexural stiffness and at the same time admits large displacements, by a plane system of an ideal incompressible liquid. An application of methods of the theory of functions of a complex variable leads to an effective solution of the problem. The shape of the shell, the forces in it, the forces acting on the shell, and the field of velocities of the flow of the liquid are determined.     

Phase transitions,conformational lability,and intermolecular interactions in alkoxycyanobiphenyls

Vibrational spectroscopy methods (IR absorption, Raman scattering, calculations) were used to study changes in molecular structures of alkoxycyanobiphenyls during phase transitions. The spectra were measured in the 33–3500 cm⁻¹ region at temperatures of 100–450 K. The temperature dependences of the IR bands that correspond to the noncharacteristic vibrations of molecular fragments between the phenyl rings and the alkyl radicals point to the conformational polymorphism of these molecules. An analysis of the Raman bands corresponding to the characteristic vibrations of the C−H bonds of alkyl radicals [q(CH)], the C−H and C−C bonds of phenyl rings [q(CH) and Q(CC)], and the CN bonds of the cyano groups [Q(CN)] suggests significant intermolecular interactions. The conformational lability and intermolecular interactions are associated with differences in molecular packing in the substances of this homologous series. Saratov State University. Institute of Solid State Physics, Rostov State University. Institute of Physics, Uzbekistan Academy of Sciences. Samarkand State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 5, pp. 814–822, September–October, 1995. Translated by I. Izvekova     

Formylation of deoxyvasicinone by alkylformates: synthesis and reaction of <Emphasis Type="Italic">α</Emphasis>-hydroxymethylidenedeoxyvasicinone with isomeric aminophenols and aminobenzoic acids

A new method for formylation of deoxyvasicinone (DOV) was developed. Nucleophilic substitution of α-hydroxy- and -dimethylaminomethylidene-DOV by isomeric aminophenols and benzoic acids to give α-arylaminomethylidene-DOV was studied.     

Generation and metathesis of azomethine imines in reaction of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes with het(aryl)methylidenemalononitriles

A new metathesis reaction of azomethine imines is found. Catalytic or thermal diaziridine ring opening of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes leads to azomethine imines reacting further with het(aryl)methylidenemalononitriles to give in situ new azomethine imines inaccessible by common synthetic methods. New azomethine imines are detected as pyrazolines formed via a 1,4-H shift and trapped by the [3+2] cycloaddition with various dipolarophiles to yield 1,5-diazabicyclo[3.3.0]octane derivatives bearing pharmacophoric heterocycles, e.g. furan, nitrofuran, thiophene, and indole. The best results are achieved in the Et₂O·BF₃-catalyzed reactions in ionic liquids.     

On projective motions of five-dimensional spaces of special form

The paper is devoted to the problem of determining of 5-dimensional pseudo-Riemannian manifolds (M, g) admitting projective motions (h-spaces). A similar problem for n-dimensional proper Riemannian and Lorentz spaces was solved by Levi-Civita, Solodovnikov, Petrov and Aminova. For pseudo-Riemannian manifolds of arbitrary signature and dimension the problem of their classification in Lie algebras and Lie groups of projective transformations, set more than a hundred years ago, is still open. In this paper five-dimensional h-spaces of the type {221} are determined using the method of skew-normal frame (Aminova) and necessary and sufficient conditions for the existence of projective motions of the same type are established.     

Base-induced transformations of ortho-nitrobenzylketones: intramolecular displacement of nitro group versus nitro-nitrite rearrangement

Reactions of 4-bromo-5-nitrophthalonitrile (BNPN) with enolates of alkyl 4-R-2,4-dioxobutanoates gave alkyl 3-acyl-5,6-dicyanobenzofuran-2-carboxylates, 4-(2-R-2-oxoethyl)-5-nitrophthalonitriles, or 3-acyl-1,2-benzoxazole-5,6-dicarbonitriles. With a base, 4-(2-R-2-oxoethyl)-5-nitrophthalonitriles either undergo nitro-nitrite rearrangement resulting in 3-acyl-1,2-benzoxazole-5,6-dicarbonitriles or yield 2-R-benzofuran-5,6-dicarbonitriles with a nitro group displacement.     

Quantum chemical modeling of the enthalpy of formation for guanidinium bitetrazole salts

The enthalpies of formation for bitetrazole guanidinium salts in the gas and solid phases were calculated using the standard approach and isodesmic reaction method. A comparative analysis of the quality of the methods and the basis sets (HF, 3-21G, 6-31G, 6-311⁺⁺G(d, p); DFT/B3LYP, 3-21G, 6-31G(d)) was performed for the calculation of the molecular volumes necessary for modeling the enthalpies of formation in solid phase, and the optimum set was recommended. The calculated values of enthalpies of formation of the compounds obtained by the isodesmic reaction method are three times lower than the results obtained using standard procedures.     

Regeneration of an average temperature isomerization catalyst in supercritical carbon dioxide medium modified with C<Subscript>5</Subscript>–C<Subscript>6</Subscript> isoalkanes

The regeneration of an average temperature isomerization catalyst with supercritical carbon dioxide together with a cosolvent was studied. An effect of regeneration conditions on catalytic activity of the studied catalyst has been defined.