Vapor pressure measurements of para-hydrogen adsorbed on exfoliated graphite

Monolayer isotherms were measured for 15, 18, and 20 K for para-hydrogen adsorbed on exfoliated graphite foam, and for the second, third, and fourth layers in the temperature interval of 8 to 20 K, using the standard volumetric method. From the data, the isosteric heat of adsorption, molar entropies and internal energies were obtained as a function of coverage. The values for coverages above the third layer were compared to those at the p-H₂ bulk triple point, showing that, within our experimental uncertainty, the results are closer to the values of bulk solid para-hydrogen. Critical temperatures for the second and third layers and the triple point temperature for the second layer, were determined, yielding values of T_c2 = (10.0±0.1) K, T_c3 = (11.0±0.5) K and T_t2 = (6.5±0.1) K respectively. Features occurring along the monolayer coverages are compared to transitions which occur in the para-hydrogen phase diagrams adsorbed on graphite, obtained from heat capacity measurements by other authors. From the isotherms, compressibilities were calculated as a function of coverage for several temperatures. Whenever possible the obtained results were compared to existing data in the literature.     

Influence of structural factors on the macro- and micromechanisms of fracture of austenitic dispersion-hardening alloys with an interrupted type of decomposition. Report 1

The commercial alloy 36NKhTYu in various structural conditions differing in the type of decomposition, grain size, and degree of dispersion of Y'- and -phase hardening particles was investigated by high-voltage electron microscopy and determination of the mechanical properties in tension in fatigue tests. It was established that in the alloy with the original coarse grain size regardless of the type of structure being formed and the form of loading, fracture is primarily ductile, occurring by a dislocation-shear mechanism. The comparison of structures of different type that was made showed that the structure with interrupted precipitation of -phase has the highest fracture energy requirement as the result of the presence of plastic interlamellar layers, providing effective dissipation of the energy supplied in loading. Deformation and fracture of the fragmented and ultradispersed structures is controlled by collective rotational processes.Translated from Problemy Prochnosti, No. 10, pp. 23–28, October, 1992.     

Application of the monte carlo method in the processing of experimental data on dynamic deformation of materials

The article presents a method of processing the recorded diagram of deformations vs time t for the purpose of determining the time-dependent change of strain rate and acceleration. The method is based on the utilization of data of statistical tests (the Monte Carlo method) and the least squares method applied to the deviations of the functions (t) from the experimental curve at the specified number of points.Translated from Problemy Prochnosti, No. 8, pp. 20–22, August, 1992.     

Threshold phenomena in the excitation spectrum of liquid 4He

The elementary theory of threshold phenomena in the excitation spectrum of superfluid ⁴He is presented. The multiphonon threshold in the initial part of the spectrum and the two-roton threshold at energy 2 are discussed.     

Low-temperature nonequilibrium-ionization inert-gas plasma and MHD-generators

The main results of theoretical and experimental studies of low-temperature magnetized (>1) nonequilibrium-ionization plasma properties are reported. Such plasma is found to be more stable as compared to the equilibrium-ionization one. Development of ionization instability in such plasma results in the formation of striae oriented perpendicularly to the plasma velocity and not decreasing its effective electric conductivity. Thus, the possibility exists of designing an effective MHD-generator operating with the inert-gas plasma without admixtures in closed-cycle installations.Reported at the VIIIth All-Union Conference on Physics of Low-Temperature Plasma (Minsk, September 1991).St. Petersburg Branch of the All-Union Research Institute for Electromechanical Engineering. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 2, pp. 161–164, August, 1992.     

Healthcare industry to benefit from 'Baby Bell' court ruling

Courts have cleared the way for regional Bell operating companies to sell electronic information. Although critics are fearful of the Baby Bells' power, others say the decision will open a myriad of possibilities that could have far-reaching effects on the healthcare industry.     

Effects of silicon powder structure of nitriding

A study has been made on how the structural state of the silicon affects the nitriding at 1200–1400C. As the initial powder becomes more defective, the nitriding accelerates, and there is an increase in the importance of reactions in the gas phase, with an increase in the proportion of the a modification of silicon nitride, and a tendency for elongated crystals to form.Translated from Poroshkovaya Metallurgiya, No. 10, pp. 1–7, October, 1992.