Action of a gas flux on the surface layer of the bore

The heating parameters and temperature of the surface layer in the bore are determined in the case of a single shot, for sections of the bore subject to the action of a gas flux at the corners of grooves that are unfilled by the bullet’s casing.     

Some characteristics of soil stabilization by “sealed” injection using microcement

Characteristic features of “sealed injection” for the microcement stabilization of the saturated soils between the Serebryanovorsk transportation and service tunnels in Moscow are examined. __________ Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 25–28, January–February, 2008.     

Roller bearings with rational working surfaces and their manufacture

Russian Engineering Research -     

A strain of the yeast Saccharomyces cerevisiae for testing environmental mutagens based on interaction of the mutations rad2 and him1

The interaction between mutations at the RAD2 and HIM1 genes was studied. The RAD2 gene encodes endonuclease involved in nucleotide excision repair. Mutants at this gene are highly sensitive to the lethal effect of a variety of mutagens. The product of the HIM1 gene is needed for correction of mismatched bases and repair of premutational DNA damage. Mutations in this gene lead to the formation of the mutator phenotype and high sensitivity to induced mutagenesis. The double rad2 him1 mutant manifested the synergic type of interaction. The level of UV-induced mutagenesis in the double mutant was five times higher than in single mutants, and the absolute yield of forward mutations in five genes controlling adenine biosynthesis was 1 to 2%. UV-induced mutagenesis was increased, at low doses, by several orders of magnitude in the double mutant, compared to the wild-type strain. The high level of mutagenesis in this mutant was caused by ethyl and methyl methanesulfonate. These properties of the stock with the double rad2 him1 mutation makes it promising as a tester in analysis of the gene toxicity of different substances.     

The shape of the signals of transient photoconductivity in silicon doped with gold or sulfur

Experimental results of studying the photoconductivity kinetics in silicon doped with either gold or sulfur are reported. The nonequilibrium charge-carrier concentration was generated by the effect of pulsed laser radiation. The time dependence of nonequilibrium conductivity was determined by contactless measurements from a variation in the reflected power of the microwave field. The long-term photoconductivity with the time constant of τ ≈ 1.6 ms at room temperature is observed in the silicon samples overcompensated with sulfur. Conventional short-term processes (τ ≈ 2–3 μs) characteristic of the centers with deep levels are observed in the silicon samples doped with gold. These differences are accounted for using the known data on the energy characteristics of the gold and sulfur levels in the silicon band gap and their charge states. Original Russian Text ? A.D. Kiryukhin, V.V. Grigor’ev, A.V. Zuev, V.V. Zuev, N.A. Korolev, 2007, published in Fizika i Tekhnika Poluprovodnikov, 2007, Vol. 41, No. 3, pp. 269–272.     

Texture formation on the friction surface in transformation-toughened ceramics

The surface of Y-TZP ceramics after dry friction on steel in a wide range of relative sliding velocities (0.2–11.1 m/s) was studied by X-ray diffraction. An analysis of the surface structure showed that the texture state of the friction surface is similar to that observed for analogous materials upon rough grinding. The main trends in the I ₍₀₀₂₎/I ₍₂₀₀₎ intensity ratio characterizing the tetragonal ZrO₂ phase as a function of the sliding velocity and the ceramic grain size are established. The mechanisms of lattice reorientation operative at various sliding velocities are discussed.