Effect of temperature and cyclic heating on the structure and strength of glass textolite

The article established the regularities of change of the physicomechanical characteristics and strength of glass textolites in single and repeated thermal loading. It shows that under multiple loading the intense loss of strength of the investigated materials is due to increased porosity on account of the large number of microcracks appearing in the structure. A correlation is obtained between the elastic and strength characteristics and porosity in dependence on the temperature of multiple heating which in the first approximation is described by a polynomial of second degree with respect to temperature, multiplied by the reciprocal of porosity.Translated from Problemy Prochnosti, No. 6, pp. 53–58, June, 1991.     

Catalytic oxidation of sulfide ions over nickel hydroxides

The catalytic sulfide ion oxidation by oxygen to elemental sulfur over β-Ni(OH)₂ and LiNiO₂ has been studied. As a result of experimental investigation performed, a reaction mechanism is suggested which involves heterogeneous and homogeneous processes. Dioxygen activation in the heterogeneous process proceeds via a redox Ni²⁺ ↔ Ni³⁺ transition and participation of OH⁻ groups. The active HO⁻₂ species thus formed carries on the reaction in homogeneous phase. Nickel hydroxides are promising catalysts for practical application.     

Adsorption layer and foam film properties of mixed solutions containing β-casein and C12DMPO

The interrelations between adsorption layer properties and surface forces in thin foam films of protein/surfactant mixtures were investigated. The adsorption from β-casein/dodecyl dimethyl phosphine oxide (C₁₂DMPO) mixed solutions was studied by Profile Analysis Tensiometry (PAT). The adsorption of protein/surfactant mixtures at the air/water interface is of competitive nature. The obtained adsorption isotherms suggest a gradual displacement of the protein molecules from the interface with increasing surfactant concentration. Foam films were studied by microinterferometry, originally introduced by Scheludko and Exerowa. The obtained experimental results show that the composition of the mixed adsorption layers changes with increasing amount of added surfactant. At a certain mixing ratio the corresponding foam film thickness decreases dramatically. This change happens above the surfactant concentration where the surface tension of the protein–surfactant mixtures approaches the values obtained for the respective pure surfactant solutions. The thickness, refractive index and adsorbed amount of the respective adsorption layers were determined by ellipsometry. These results correlate with the above-mentioned PAT and foam film data. The refractive index and adsorbed amount decrease monotonically and reach values close to those for pure surfactant solutions. On the contrary, a continuous increase can be observed in the layer thickness up to the above-mentioned concentration, indicating the formation of a more diffuse layer at the air–water interface formed by β-casein and C₁₂DMPO molecules upon increase of surfactant concentration. For foam films the electrolyte concentration can change the equilibrium thickness of the films and the Π(h)-isotherms significantly.     

The sol-gel method of fabrication of zinc silicate luminophores

Fabrication of zinc-silicate luminophores by a new nontraditional method was examined. A wide range of gel compositions (40–95% ZnO) was investigated. Zinc-containing raw material was selected and it was shown that zinc nitrate is optimum. The thermal properties and crystallizability of the gels and the photo- and cathode-luminescent properties of final materials fabricated by two different methods were investigated. The experiments demonstrated a number of advantages of the sol-gel method: reduced power consumption, simplification of the technological scheme, improvement in the properties of the products, the possibility of obtaining different properties by altering the parameters in the different stages of fabrication.