Effect of metallocenes on the photoinduced postpolymerization of vinyl monomers

The photoinduced postpolymerization of styrene and methyl methacrylate in the presence of metallocenes is studied. It is shown that, after short-term UV irradiation, the polymerization of vinyl monomers mediated by metallocenes continues in the dark regime until the formation of polymer glasses. The process proceeds as a terminationless complex-radical polymerization.     

A study of the radical polymerization of styrene in the presence of ferrocene

Reactions that occurred during the radical polymerization of styrene in the presence of ferrocene were analyzed by the B3LYP/6-31G(d, p) method of density functional theory. The formation of the Fe-C bond between the iron atom of ferrocene and polystyrene radical (R^·) was found to be energetically unfavorable, and the polystyrene chain growth reaction in the coordination sphere of the iron atom by the insertion of the monomer at the Fe-C bond was characterized by a high activation energy. Conversely, the addition of R^· to the ferrocene cyclopentadienyl ring occurred with the release of energy. Indications of termination-free styrene polymerization in the presence of ferrocene experimentally observed earlier were explained in terms of reversible inhibition concepts.     

UV spectroscopic quantitative determination of methanofullerene derivatives with a different degree of substitution

A spectroscopic method for the analysis of compounds belonging to methanofullerenes with different functionalization and a number of substituents is developed. In order to determine the composition of mixtures of these compounds the standard spectrophotometric procedure along with derivative spectroscopy are applied. Acceptable reproducubility and sensitivity of the methods used are demonstrated on model mixtures of fullerene derivatives. The reaction mass obtained in the interaction of fullerene with diallyl ester of malonic acid is analyzed.     

Relaxation oscillations and diffusion chaos in the Belousov reaction

Asymptotic and numerical analysis of relaxation self-oscillations in a three-dimensional system of Volterra ordinary differential equations that models the well-known Belousov reaction is carried out. A numerical study of the corresponding distributed model-the parabolic system obtained from the original system of ordinary differential equations with the diffusive terms taken into account subject to the zero Neumann boundary conditions at the endpoints of a finite interval is attempted. It is shown that, when the diffusion coefficients are proportionally decreased while the other parameters remain intact, the distributed model exhibits the diffusion chaos phenomenon; that is, chaotic attractors of arbitrarily high dimension emerge.     

Calculation of the stationary,periodic, and quasi-periodic viscous fluid flows between two rotating permeable cylinders

On the basis of the methods of the theory of codimension-two bifurcations of cylindrically symmetric hydrodynamic flows, using computer calculations, the motions of a fluid between rotating permeable coaxial cylinders are investigated near the intersection of the bifurcations corresponding to the origin of a stationary regime of the Taylor vortex type and self-oscillations with azimuthal waves.     

Chromatographic study of the chemical composition and potential toxicity of spirits and alcoholic beverages

The composition of vodkas, rectified food alcohols, cognacs, cognac spirits, and other strong alcoholic beverages was studied by chromatography and compared with the composition of industrial (synthetic and hydrolysis) ethyl alcohols, adulterated cognacs, and homemade spirits (samogon) from the illicit market. It was found that the majority of the test alcohol-containing liquids were close to commercial alcoholic beverages in terms of chemical composition and toxic properties. The samples containing ethylene glycol and enriched components of the head fraction of rectification should be considered most toxic.     

Stability properties of cycles and tori of a simplest nonresonant wave-type equation

For a number of meaningful examples, nonresonant wave-type equations are shown to be characterized by periodic dynamics. Translated fromMatematicheskie Zametki, Vol. 62, No. 5, pp. 744–750, November, 1997. Translated by O. V. Sipacheva     

Stability of liquid flow between heated rotating cylinders

The effect of a radial temperature gradient on stability of steady-state flow of a viscous liquid between two solid concentric cylinders both rotating in the same direction is considered. The linear stability problem is considered in the Boussinesq approximation. Sufficient stability and instability conditions for the flow relative to rotationally symmetric perturbation are obtained. Neutral curves are computed for a wide range of problem parameters.