A hierarchy of high-order theories for symmetric modes in an elastic layer

A hierarchy of high-order theories for symmetric modes in an infinitely long elastic layer of the constant thickness is derived by means of the inertia-corrected polynomial approximations. For each member of the hierarchy, boundary conditions for layers of the finite length are formulated. The forcing problems at several approximation levels are solved with the use of the bi-orthogonality conditions. Accuracy of these approximations is assessed by comparison of results with the exact solution of the Rayleigh–Lamb problem. Special attention is paid to the power flow analysis in alternative modal excitation cases and to the applicability of the Saint-Venant?s principle in stationary elasto-dynamics.     

Chiral spin liquid in a two-dimensional helical XY magnet with two chiral order parameters

The critical properties of an XY helimagnet on a square lattice with two chiral order parameters are studied by Monte Carlo simulations. This model is a modification of the J ₁-J ₂-J ₃ model with J ₂ = 0. The case of different third range order interactions J ₃ are considered, J ₃ ^a ?? J ₃ ^b . A first order transition is found away from the Lifshitz points 4J ₃ ^a = J ₁ and 4 J ₃ ^b = J ₁. It is pointed out that a chiral spin liquid phase possibly exists near the Lifshitz points.     

Spectroscopic properties of pharmacologically active phenols

The IR Fourier-transform spectra of pharmacologically active phenol molecules in solutions in CCl₄ and in the crystalline state have been studied. Phenol derivatives with different directivities and different levels of pharmacological efficiency have been examined. Based on analysis of the IR spectra of screened phenols, the antimicrobial activity of phenols with free hydroxyl groups has been shown to be highest. The high antimicrobial activity of aminophenols is related to the formation of intramolecular hydrogen bonds. For aminophenols that are active against herpesviruses, O-H...N hydrogen bonds are formed in molecules. The main characteristic of the high antiviral activity against A-type influenza is predominance of intramolecular hydrogen bonds of the O-H...O=C type in molecules. Sulfur-containing aminophenols, which manifest activity against HIV infection, are characterized by the occurrence of hydrogen bonds that involve the participation of the OH, NH, and SO₂ groups.     

Electronic structure and spectroscopic properties of anti-HIV active aminophenols

We have measured the absorption and fluorescence spectra and fluorescence quantum yields of sulphone-containing anti-HIV active o-aminophenol molecules in an inert solvent, hexane, and in a polar solvent, acetonitrile. We have studied IR Fourier-transform spectra and examined structural features of o-aminophenols with different substituents in solutions and crystals. Functional groups of molecules that are involved in the formation of hydrogen bonds have been revealed. Proton acceptor properties of o-aminophenol molecules have been theoretically evaluated using the method of molecular electrostatic potential. Using quantum chemistry methods, we have calculated and interpreted absorption and fluorescence spectra of o-aminophenols. Calculation data are compared with experimental results. We have determined the main channels and mechanisms of photophysical relaxation processes in o-aminophenols.     

A Route to Organyl(trialkoxysilyl)chalcogenides and Dichalcogenides, Bis(trialkoxysilylmethyl)chalcogenides and Dichalcogenides

Reactions of organylchalcogenomagnesium halides RYMgX (in situ) (R = Me, Et, Ph; Y = S, Se, Te; X = Br, I) with (halomethyl)trialkoxysilanes X'CH₂Si(OR')3 (X' = Cl, I; R' = Me, Et) at reflux in tetrahydrofuran and the systems of tetrahydrofuran-acetonitrile 1:2, and ether-acetonitrile 1:2 are studied. These reactions are shown to lead to formation of mixtures of corresponding organyl(trialkoxysilylmethyl)chalcogenide and -dichalcogenide, bis(trialkoxysilyl methyl)chalcogenide and -dichalcogenide, as well as the contaminants 2,2,6,6-tetraalkoxy-2,6-disila-4-chalcogen-1-oxane, diorganylchalcogenide and -dichalcogenide, and other organic and organosilicon compounds. Composition of the formed mixtures debends considerably on the structure of R, nature of the chalcogen Y (S, Se, Te), and halides X and X' in the initial reagents, and reaction conditions. The most of synthesized and isolated organosilicon chalcogenides are newly obtained compounds.     

Neutron emission during a nanosecond discharge in deuterium in a nonuniform electric field

Neutron emission during a nanosecond deuterium discharge formed at the nonuniform electric field is investigated. A stable neutron yield is observed when the cathode is made of metallic plates covered by a layer of deuterated zirconium and the anode is made of stainless steel in the form of a tube. It is shown that, when the deuterium pressure equals several Torr, neutrons are emitted from both deuterated and deuterium-free cathodes. The influence of the anode design on the neutron yield is studied.     

Influence of nonlinear effects on destruction of active elements of electron-beam-pumped lasers Based on ZnSe-containing quantum-size structures

The fracture patterns of active elements of pulsed green lasers with transverse electron-beam pumping, based on ZnSe-containing quantum-size structures, have been investigated. The fracture in the form of thin (～1 μm) and long (to 100–150 μm) filaments can be explained by the self-focusing of the intrinsic laser radiation in the semiconductor structure.     

Millimeter-wave radio scattering from discharges stimulated by a laser pulse in the dusty atmosphere

Nizhegorod State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 1, pp. 3–8, January, 1992.