Synthesis of organoyttroxanealumoxanesiloxanes and preparation of glass and glass-ceramics on their base

We report the first synthesis of organoyttroxanealumoxanesiloxanes soluble in organic solvents. Their pyrolysis yields transparent glass-ceramic materials with a predetermined Al : Y : Si molar ratio [1]. We have studied the composition and properties of the organoyttroxanealumoxanesiloxanes and their pyrolysis products.     

Positional‐Species Composition of Triacylglycerols from the Arils of Mature Euonymus Fruits

Positional‐species composition (PSC) of 1,2,3‐triacyl‐sn‐glycerols (TAG) from the arils of mature fruits of 13 species of Euonymus L. genus was established. The residues of six major fatty acids (FA), palmitic, stearic, hexadecenoic (H), octadecenoic (O), linoleic (L), and linolenic, were present in the TAG. PSC of TAG was determined by their partial lipase hydrolysis. By using hierarchical cluster and principal component analyses, it was definitely demonstrated that separate taxonomic units forming this genus were significantly distinguished as regards PSC of TAG. In particular, the Euonymus subgenus greatly exceeded the Kalonymus subgenus in both total content of L in TAG and in the rate of its incorporation into their mid‐position, while TAG of Kalonymus were marked by a prevalence of O‐TAG and sn‐2‐O isomers. Thus, these subgenera were significantly distinct in the rate of incorporation of O and L residues in the sn‐2 position of TAG molecules. Meanwhile, the TAG from the Euonymus section species were marked by an enhanced concentration of H and the incorporation of H in UUU TAG was much more active than in other TAG types. As for positional‐type composition of TAG, saturated FA were always virtually absent in the sn‐2 position of Euonymus aril TAG.     

Surfacing methods for increasing the service life of rapidly wearing working tools of agricultural machines

The rapid wear of working tools of agricultural machines and equipment lowers the productivity of labour and the quality of operations. The most important and, correspondingly, most ‘problematic’ loaded components of agricultural machines are soil cultivating working tools. The principal methods of increasing the service life of these components are to use new materials and hardening surfacing technologies.     

Synthesis of Li x Na1 − x Ta y Nb1 − y O3 and LiTa y Nb1 − y O3 perovskite and pseudoilmenite solid solutions

This paper compares the solid-state reactions underlying the synthesis of LiTa _y Nb_{1 ? y} O₃ and Li _x Na_{1 ? x} Ta _y Nb_{1 ? y} O₃ solid solutions with the use of Ta_2y Nb_{2(1 ? y)}O₅ niobium tantalum pentoxides and a mechanical mixture of the Ta₂O₅ and Nb₂O₅ pentoxides. Our results demonstrate that the synthesis with the use of Ta_2y Nb_{2(1 ? y)}O₅ allows phase-pure solid solutions to be obtained at substantially lower temperatures in comparison with a mechanical mixture of Ta₂O₅ and Nb₂O₅.     

Nonlinear optical effects in glasses containing copper chloride nanocrystals

Nonlinear optical properties of various glasses containing copper chloride nanocrystals have been studied at wavelengths of 532 and 1064 nm. It is established that the nonlinear optical response is manifested by the optical limiting of transmitted radiation and consists of two, low- and high-threshold parts. The low-threshold response is related to a self-defocusing of the radiation, while the high-threshold response is related to the phenomena of two-photon absorption, color center photogeneration, and thermal lens formation.     

Structure and mechanical characteristics of ceramic Nb2O5 and Nb2(1 − y)Ta2y O5

The structure and mechanical characteristics of ceramic Nb₂O₅ and ceramic materials produced from coprecipitated Nb_{2(1 ? y)}Ta_2y O₅ pentoxides by a conventional ceramic processing technique and exposure to high-intensity light have been studied by scanning probe microscopy and Raman spectroscopy.