Photoemission of polarized electrons from InAlGaAs/GaAs superlattices with minimum conduction band offsets

Photoemission of polarized electrons from heterostructures based on InAlGaAs/GaAs superlattices with minimum conduction-band offsets is investigated. The comparison of the excitation energy dependence of the photoemission polarization degree with the calculated spectra make it possible to determine the polarization losses at different stages of the photoemission. A maximum polarization of P = 91% and a quantum yield of 0.14% are close to the best results obtained for photocathodes on the basis of strained semiconductor superlattices.     

Measurement of the angle of the direction of linear polarization of laser radiation by nonlinear thin-wire bolometers

The systematic error in measuring the angle of the direction of linear polarization of laser radiation from the difference in the signals of three identical bolometric arrays is analyzed. The error is due to the temperature dependence of the physical parameters of the bolometers and is increased by the nonuniformity of the distribution of the incident radiation intensity over the area of the input aperture of the measuring instrument. The calculations are carried out for platinum bolometers under model conditions and for radiation of wavelength 10.6 μm. A method of processing the recorded signals is proposed which gives an uneliminated residue of the systematic error of not greater than ±1°. Translated from Izmeritel’naya Tekhnika, No. 8, pp. 24–26, August, 1996.     

Mechanics of sintering materials with bimodal pore distribution. III. Kinetics of sintering combined with various forms of loading and adhesion conditions

A study has been made on the effects of loading scheme and conditions restricting macroscopic strain on the work-hardening kinetics and strain accumulation in the solid state in sintering materials with bimodal pore size distributions. Active loading intensifies the reduction in the small pores. The greatest effect comes from combining sintering with hydrostatic compression. At the same time, kinematic constraints (partial or complete adhesion in surfaces) substantially retards the shrinkage of large pores, which means that the porous structure can be controlled. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 10–15, May–June, 2006.     

Effect of the particle size ratio on the conductivity of conductor-insulator powder composites: Numerical simulation

A theoretical method for determining the percolation limit and effective conductivity of composites based on polydisperse mixtures of insulator and conductor powders is proposed. The effect of the particle size ratio between the insulator and conductor on the percolation limit and effective conductivity is studied. Numerical simulation of the microstructure, effective properties, and percolation limit in composites is discussed. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 1–2(453), pp. 31–40, 2007.     

A relation between interfacial and bulk properties along the saturation curve

A liquid-vapor interface in thermal equilibrium was considered, where the pressure tensor depends upon the density (z) and the position z. The surface tension coefficient results are parametrized with the bulk compressibility, liquid-vapor density difference, and interfacial width along the saturation curve. Previous results at the triple and critical points reported by other investigators are verified. Also included is a plot of the computed results using the parametric equation and experimental data for different substances.     

Formation of carbon nanofibers via carbon monoxide disproportionation

Experimental results suggesting that carbon nanofibers are formed from amorphous carbon released at several compact active sites are reported. It was shown that the sites in question are catalyst crystal lattice defects formed at the crystallite contact boundaries.     

Ionization of glycine molecules by α-particles with keV energies

The method of “multistop” time-of-flight mass spectrometry has been used to study the mechanism of radiation damage to glycine molecules in the gas phase upon their interaction with He²⁺ ions with energy E _p = 4 keV/amu. The relative cross sections of various elementary processes occurring in single collisions of glycine molecules with the ions were measured for the first time. A difference was found between the fragmentations of intermediate doubly charged ions formed in capture of a single electron with ionization and in two-electron capture, which is accounted for by the difference between the excitation energies of molecular ions.     

Non-alloy Cr/Au Ohmic contacts in the technology of planar beam-lead GaAs <Emphasis Type="Italic">p-i-n</Emphasis> diodes

The characteristics of non-alloy Cr/Au ohmic contacts in planar beam-lead GaAs p-i-n diodes have been studied. The room-temperature reduced contact resistance in the structures studied was 2 × 10⁻⁶ Ω cm². The obtained parameters of p-i-n diodes allow these devices to be used as limiters in radar protection systems.     

On the resonance and antiresonance frequencies of a plate piezoceramic transducer

Problems related to applying the concepts of resonance and antiresonance frequencies of a plate piezotransducer have been studied. The case of a plate unilaterally loaded on an aqueous medium has been researched. It has been shown that the concept of the antiresonance frequency determined with the use of an elastic modulus c₃₃ ^D can be applied only conditionally, still allowing one to calculate frequency characteristics for different values of a squared electromechanical-coupling coefficient. Notwithstanding the conditional nature of the term “antiresonance”, its practical use does not cause any difficulties.     

Prospects for Consteel technology in Russia

The development of the Consteel process is briefly analyzed. Foreign experience with the Consteel system and its derivatives (Faststeel and Consteel Evolution) is discussed. Its introduction in Russia is expedient for the production of high-quality steel.