Formation of soluble chitosan–carrageenan polyelectrolyte complexes

The formation process of soluble chitosan (C)/κ-carrageenan (K) complexes was studied. It was shown that soluble complexes were obtained preferentially by mixing the starting components at given ratios whereas soluble complexes were formed only over a narrow range of starting-component ratios by titration of K with C. The formation of C/K polyelectrolyte complexes was confirmed by gel-permeation chromatography and centrifugation in a Percoll gradient. The formation process of C/K complexes depended on the C molecular weight and the concentrations and ratios of starting polysaccharides. It was shown that unbound components in addition to the complex remained in the mixture upon mixing carrageenan with high-molecular-weight C (C-HM) in 1:1.5 and 1:30 ratios (mol/mol) whereas low-molecular-weight C (C-LM) was bonded completely to the polyanion.     

The structure of electron beam-modified cellulose triacetate

The structure, relaxation, and surface properties of cellulose triacetate (CTA) fibers and films modified by electron-beam irradiation in the absorbed dose range of D = 0−1000 kGy have been studied. The relation of the glass transition and melting temperatures of the irradiated CTA samples with the local density and the fractal dimensionality of the macrochain has been revealed. It has been shown that the radiation-chemical processes associated with the rupture of acetal bonds and the hydrolysis of CTA acetate groups predetermine the change in the structural and relaxation characteristics of the irradiated samples, as well as a nonmonotonic form of the dependence of the density and the surface energy of the films upon the absorbed dose near the threshold value of D = 75 kGy.     

Tandem transformations of tetrahydropyrrolo[3,2-<Emphasis Type="Italic">c</Emphasis>]pyridines under the action of dimethyl acetylenedicarboxylate. A novel route to pyrrolo[2,3-<Emphasis Type="Italic">d</Emphasis>]azocines

Reactions of substituted tetrahydropyrrolo[3,2-c]pyridines with dimethyl acetylenedicarboxylate in protic and aprotic solvents were studied. A novel single-step method for the synthesis of pyrrolo[2,3-d]azocine derivatives was developed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2513–2519, November, 2005.     

Features of Laser-Induced Modification of Sclera and Cornea

Results are presented from studying collagen degradation in scleral and corneal tissues upon CW IR laser irradiation at a wavelength of 1.56 μm and powers of 1.4 and 7 W. The exposure time is such that the radiometrically determined maximum tissue temperature ranges from 55 to 70°C. It is shown that at a power of 1.4 W, laser-induced collagen denaturation in sclera and cornea starts at 55 and 60°C, respectively. When the power is increased to 7 W, the temperature of denaturation onset rises by 2°C. These findings are discussed from the viewpoint of the joint photothermal and photomechanical effects of laser irradiation.     

Synthesis and optical properties of new coumarin derivatives based on 2-(2-chlorobenzylidene)malononitrile

A procedure has been developed for the conversion of the CS gas [2-(2-chlorobenzylidene)-malononitrile] to new 3-cyanocoumarin derivatives, 4-(2-chlorophenyl)-2-oxo-2H-chromene-3-carbonitriles. Study of the optical properties of the synthesized compounds has revealed strong fluorescence in the violet and blue regions.     

Study of thermohumid aging of aircraft fiberglass plastic

The thermohumid aging of aircraft fiberglass plastic over 5.5 years is studied. It is shown that, under conditions that simulate a tropical climate, the controlled parameters (maximal water saturation, moisture diffusion coefficient, shear modulus along the sheet plane) vary to the greatest extent after 1 year of aging, after which they stabilize. The molding conditions under which fiberglass plastic preserves high parameters under long-term exposure to a moist environment are determined.     

The role of mercury in the processes of vital activity of the human and mammalian organisms

Mercury belongs to one of the most common heavy metals that have high biological activity in relation to human and animal cells. However, the physiological role of mercury in the metabolism of eukaryotic cells is still unclear. The given review provides current information on certain properties of mercury, the mechanisms of penetration of Hg (II) inside cells, its genotoxic and cytotoxic effects, as well as the role of mercury in the induction of autoimmune processes involving production of autoantibodies to the nucleolar protein fibrillarin.     

Effect of the thickness and porosity of carbon-black gas-diffusion air electrodes on the efficiency of hydrogen peroxide synthesis from atmospheric oxygen

Effect of the porosity and thickness of hydrophobized gas-diffusion air electrodes composed of A 437-E acetylene black or its mixture with P 702 and P 701 furnace blacks on the efficiency of electroreduction of atmospheric oxygen to H₂O₂ in 0.5 M NaOH was studied.