Synthesis and Properties of Organo-Inorganic Composites Based on Daunomycin,Polyvinylpyrrolidone, and Selenium Nanoparticles

Two procedures for preparing organo-inorganic composites based on daunomycin, polyvinylpyrrolidone, and selenium nanoparticles were developed with the aim of preparing water-soluble nontoxic derivatives of daunomycin antitumor antibiotic. The first procedure consists in preliminary stabilization of selenium nanoparticles with polyvinylpyrrolidone, followed by addition of daunomycin, and the second procedure, in preliminary formation of a complex of daunomycin with polyvinylpyrrolidone, followed by selenium reduction. As shown by optical spectroscopy and by dynamic and static light scattering, the synthesis procedure does not influence the weight-average molecular mass of the synthesized composites, but influences the structural organization and size of particles and, correspondingly, their mobility. The composite prepared by the second procedure shows promise for antitumor therapy.     

Synthesis and Stabilization of Bismuth Nanoparticles in Aqueous Solutions

Russian Journal of Physical Chemistry A - A technique is developed for the low-temperature synthesis of bismuth nanoparticles in aqueous solutions. UV–Vis spectroscopy, X-ray analysis and...     

Photophysical properties of the extract of endometallofullerenes La@C2n inortho-dichlorobenzene. Picosecond laser photolysis

The kinetics of relaxation of optical anisotropy induced by polarized light in endometallofullerenes La@C_2n inortho-dichlorobenzene was studied by picosecond laser photolysis. Decay of the optical absorption signal due to the excited states of La@C_2n follows the biexponential law with two values of relaxation time:t ₁=35±3 ps andt ₂=1100±200 ps. The lifetimet or decay of the optical anisotropy is 19±5 ps and determined by the orientational diffusion of La@C_2n . The experimentally determined lifetime of optical anisotropy agrees satisfactorily with the value yielded by the theoretical model of orientational diffusion under slip boundary conditions at the interface of the La@C_2n molecule with the solvent. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya No. 10, pp. 1921–1923, October, 1999.     

Immobilization of chymotrypsin on silver nanoparticles

Russian Chemical Bulletin - The method of immobilization of chymotrypsin based on the reduction reaction of silver nitrate with sodium borohydride in an aqueous medium in the presence of the enzyme...     

Proton conductivity of calix[n]arene-para-sulfonic acids (n = 4, 8)

High proton conductivity in calix[n]arene-para-sulfonic acid hydrates (n = 4, 8) reaching a value of 10^?1 Ohm^?1 cm^?1 at a relative humidity of 80% was revealed for the first time. This value is close to the record conductivity of solid proton conductors and acid water solutions. The dependence of proton transfer parameters and water quantity in the title compounds dependent on the relative humidity of air was investigated.     

Influence of Polycrystalline Structure on Dynamic Strength and Fracture Character of an Aluminum Alloy in Different Welding Joint Zones

Russian Physics Journal - Plastic strain localization and fracture in the nugget and thermo-mechanically affected zone of a friction stir welded Al6061-T6 alloy are numerically investigated....     

Spatial dispersion phenomena in magneto-optics

An experimental study of nonreciprocal spatial-dispersion effects in para-(Cd_1−x Mn_xTe), ferro-(LiFe₅O₈), and antiferromagnetic (Cr₂O₃) crystals caused by an external magnetic field or magnetic order is reported. Fiz. Tverd. Tela (St. Petersburg) 40, 946–948 (May 1998)     

Phase structure of silanol-modified ethylene-vinyl acetate copolymers

For (ethylene-vinyl acetate copolymer)-tetraethoxysilane and (ethylene-vinyl acetate copolymer)-polydimethylsiloxane systems, the solubility of components has been studied in a wide range of temperatures and compositions. Phase diagrams have been constructed, pair interaction parameters have been calculated, and diffusion coefficients and activation energies of diffusion have been estimated. The temperature and concentration ranges of a change in solubility related to chemical interactions between the components have been revealed, and the structure of the modified copolymers has been studied. On the basis of the kinetic data on the movement of isoconcentration planes in diffusion zones of component mixing, time intervals corresponding to the onset of the chemical reaction between the components have been determined and the apparent activation energies of the process have been computed. Complex-shaped binodal and boundary curves have been interpreted within the framework of the classical Flory-Huggins theory.