Effect of yttrium and chromium on the recrystallization of Al-Sc alloys

The effect of small chromium and yttrium additions (0.14–1.0 wt%) on the recrystallization of Al-Sc alloys having 0.1–0.4% Sc is studied with polarized light. The microstructure of cold-rolled samples annealed at 100–630°C for 1 h is examined. The chromium and yttrium additions are found to slightly affect the recrystallization temperature of the Al-Sc alloys: they increase or decrease it slightly depending on the scandium content.     

Materials with a polymeric bitumen adhesive layer

The materials based on polyethylene and poly(vinylchloride) inner tapes and polymeric bitumen mastic with the trade mark TRANSKOR used for the anticorrosion protection of steel underground pipelines are described. For the capital repair of oil pipelines, a special construction solution is offered. This structure is composed of a polymeric bitumen primer, polymeric bitumen mastic, and heat-shrinkable film.     

Wear resistance of plasma coatings for a constant work of friction

We analyze the wear resistance of plasma coatings for a constant work of friction. The dependences of the wear resistance of the coatings are obtained for a broad range of loading conditions. It is shown that the minimum sensitivity to loading conditions is exhibited by the molybdenum coatings. It is also established that the wear resistance of the coatings decreases as the amplitude of displacements increases and the cyclic frequency of the tests decreases due to the intensification of fatigue processes on the surfaces. The comparative characteristics of coatings are presented. __________ Translated from Problemy Prochnosti, No. 5, pp. 94–100, September–October, 2007.     

Decomposition in stability analysis problems of systems with self-braking gears

Decomposition algorithms for studying the stability of systems with self-braking gears are presented. The developed dynamic models of systems with self-braking gears yield simple and physically transparent spectral criteria for the neutral stability of such systems. In design of the systems considered, the obtained criteria allow development of effective procedures for parametric synthesis ensuring the stability of motion in brake release regimes.     

EFFECT OF FERMENTATION ON THE FATTY ACID CONTENT AND COMPOSITION OF CASSAVA TUBER MEAL

The effect of fermentation on the fatty acids (FA) content and composition of cassava tuber meal has been investigated. The major FA of the cassava tuber meal (CTM) lipid were oleic and palmitic acids. Other FA found in decreasing order were linoleic, linolenic, palmitoleic, stearic, myristic, pentadecanoic, heptadecanoic and nonadecanoic acids. Fermentation of the CTM resulted in substantial increases in the absolute quantities of the individual FA detected except linolenic acid. However fermentation did not alter the pattern of composition of the FA, but it caused increases in the composition of saturated FA and decreases in certain unsaturated ones. Stearic acid increased in composition by about 92.6% and pentadecanoic by about 50%. A reduction of about 72% of the linolenic acid and 24.2% of the palmitoleic acid composition were obtained in the fermented CTM lipid.     

Kinetics of decomposition of undercooled austenite formed in the critical range of temperatures

Using dilatometric and microstructural methods, the thermokinetic diagrams of decomposition of undercooled austenite formed upon heating in the intercritical temperature range have been constructed for a group of steels with 0.05–0.10% C, 0.15–1.63% Mn, 0.17–1.18% Si, and 0.003% B. The effect of the compositions of the steels, temperature of heating in the two-phase region, and rate of subsequent cooling on the kinetics of the formation of austenite and products of its decomposition has been considered. The carbon content in austenite at different temperatures of its formation has been estimated from the position of the temperature of the onset of the martensitic transformation.     

Water and Radiation Effect on Sweet Sorghum Productivity

Suitability of sweet sorghum in Greece, where irrigation supply during crop development is limited as rainfall is scarce and evapotranspiration loss is high, is examined in relation with radiation availability. A two-year field experiment was conducted, in central Greece, imposing four soil water regimes via different irrigation treatments: (1) Highly irrigated, (2) Highly irrigated till anthesis when irrigation stopped, (3) Medium irrigated, and (4) Low irrigated. It was found that above-ground dry biomass production from non-water-stressed sweet sorghum plants suggests a high productivity potential among C₄ crops. Under water shortage, radiation use efficiency may be significantly lower. Radiation use efficiency seems to be linearly related to water consumption. Stressed plants (probably except severely stressed) seem to use available water more efficiently than unstressed plants. The slope of the line relating dry matter produced and water evapotranspired increases the sooner the stress is sensed. Yield reduction resulting from post-anthesis irrigation stopage is very little. High water use efficiency values tend to be related with low radiation use efficiency values.     

Glass ceramics with controllable pore structure for medicine

The conditions for synthesis of porous biocomposite materials based on calcium phosphate for fabricating implants with prescribed pore-structure parameters, and the desired level of physical, chemical, and biological properties for clinical applications are determined. The role of a bimodal pore structure in the substrate materials for cell cultures is shown. __________ Translated from Steklo i Keramika, No. 4, pp. 23–26, April, 2007.