Mutagenic effects of heavy ions in bacteria.

The peculiarities and mechanisms of the mutagenic action of gamma-rays and heavy ions on bacterial cells have been investigated. Direct mutations in the lac-operon of E. coli in wild type cells and repair deficient strains have been detected. Furthermore, the induction of revertants in Salmonella tester strains was measured. It was found that the mutation rate was a linear-quadratic function of dose in the case of both gamma-rays and heavy ions with LET up to 200 keV/micrometer. The relative biological effectiveness (RBE) increased with LET up to 20 keV/micrometer. Low mutation rates were observed in repair deficient mutants with a block of SOS-induction. The induction of SOS-repair by ionizing radiation has been investigated by means of the "SOS-chromotest" and lambda-prophage induction. It was shown that the intensity of the SOS-induction in E. coli increased with increasing LET up to 40-60 keV/micrometer.     

Polarization Studies of Contribution of Aerosol Scattering to the Glow of Twilight Sky

The paper is devoted to studies and a quantitative estimation of the influence of scattering of direct solar radiation by particles of tropospheric aerosols in the period of light twilight, close to sunrise and sunset. Polarization measurements of the twilight sky in two broad spectral bands lying near the standard bands V and R form the basis of these studies. The measurements were carried out in 2002 and 2003 at the Southern Laboratory (Crimea) of the Sternberg Astronomical Institute. The twilight period during which the single aerosol scattering becomes significant is isolated. The character of its influence on the intensity and polarization of the twilight sky is demonstrated. A method is suggested to evaluate polarization of the single aerosol scattering and its contribution to the general brightness of the twilight sky background. The method is based on differential characteristics of the background near the zenith and on their correlations with each other.     

Spatial vibration protection in a turbopump of hydrogen rocket engines

We discuss the use of multilayered annular-plate dampers as rotor supports in turbopumps of the RD-0120 and RD-0146 rocket engines. We present a technique of calculating the elastic and damping characteristics of multilayer corrugated annular supports in the case of the conical precession of the rotor.     

Algorithms of Constructing the Regions of Initial States for Unmanned Winged Gliders

The algorithms of controlled descent for unmanned winged gliders are designed taking into account the requirements to the flight trajectory. The calculation results are represented to show the efficiency of the algorithms.     

Fuel atomization and mixing in unsteady swirling flows behind the gas-dynamic stabilizer

Features of fuel atomization and propagation in the flow behind a gas-dynamic stabilizer are considered. Estimations of the influence of transverse jets impulse magnitude on characteristics of mixing behind the stabilizer are obtained by numerical and experimental methods.     

On the analysis of electric arc process stability in plasma systems of ignition with allowance for GTE combustion chamber parameters

An approach to the analysis of electric arc process stability in plasma systems of ignition is considered depending on the ignition system power circuit parameters, speed of plasma-generating air, and combustion chamber inlet pressure. Also solved is the problem on determination of the calculated value of the maximum admissible speed of plasma-generating air that corresponds to the critical regime of stable arcing in plasma spark plug at the GTE start.     

Microindentation of plasma zirconia-based thermal barrier coatings

A technique of evaluating the micromechanical characteristics (namely, microhardness, microdurability, microbrittleness and static crack resistance coefficient) using microindentation as applied to plasma zirconia-based thermal barrier coatings is presented.     

Generalization of experimental data on two-phase critical efflux through axisymmetric channels

The results of studying the characteristics of a two-phase flow being formed during adiabatic water efflux through axisymmetric cylindrical and Laval nozzle channels are presented. Experiments were carried out with saturated water in the range of initial pressures 0.6–4.0 MPa. The fluid efflux was performed into the air with atmospheric pressure. The generalizing relations for calculating thrust pulse and critical flowrate were obtained.