Measurement of the Dynamic Characteristics of Soft Soils Using the Kolsky Method

A modified Kolsky method for dynamic tests of soft soils in an elastic holder is analyzed. It is shown the axial and radial stresses in the sample are uniform. The rational geometry of the holder is determined. Friction is found to have an effect on the dynamic strain diagram obtained. It is suggested that this effect can be reduced by lubricating the inner surface of the holder.     

Some kinetic aspects regarding the preparation of telomeric ω-hydroperfluoroalkanols

Telomerization of tetrafluoroethylene (TFE) with methanol in the presence of a free-radical initiator such as α, α′-azoisobutyronitrile (AIBN) has been carried out. The product composition was related to kinetic equations involving the chaintransfer coefficients and the concentration of telomeric fluoroalkanols obtained.     

Polarization modulation of light in an optical waveguide under lateral compression

It is shown that a lateral pressure applied to a circular single-mode optical waveguide changes the phase difference between two orthogonally polarized modes and thereby modulates the polarization state of light (elastooptic effect). The efficiency of polarization modulation is characterized by a strain-to-phase difference conversion factor as applied to polarization modes of the fiber. An expression relating the phase difference between the modes and the displacement of squeezing plates is obtained and checked in real experiments and numerically. The efficiency of conversion of lateral pressure to phase difference between the polarization modes is shown to be fairly high, on the order of 10⁴ rad/(μm m).     

Nuclear spin echo in magnetics with inhomogeneous hyperfine and quadrupole interaction

Additional spin-ocho signale from quadrupole nuclei with I=7/2 (Co⁵⁹ nuclei in Co and Fe−Co thin films) were investigated. It has been shown, that the time dependence of the additional ocho signals, arising at the time moments 2nς reflect quadrupole interaction inhomogenety.     

First results of investigation of radiation from positrons in a crystalline undulator

Radiation emitted by positrons moving in a periodically deformed crystal has been experimentally observed for the first time. Radiation spectra have been measured in a wide energy range. Experimental evidence has been obtained for an undulator peak in a radiation spectrum, which is qualitatively consistent with calculations. Crystalline undulators ensure an equivalent magnetic field of 1000 T and a period in the submillimeter range and can therefore be used to generate x-ray and gamma radiation that is a hundred times harder than radiation in usual undulators.     

X-ray semiconductor (CdTe) spectrometer for solar flare and preflare studies

This paper describes the main parameters of an instrument for X-ray flux measurement and solar flare and preflare spectrum registration. The nontraditional CdTe semiconductor detector was space qualified and has sensitivity 0.5 cm², energy region 3–30 keV, and energy resolutions ～ 1.3 keV for 5.9 keV and ～ 10% for 22.1 keV.     

Determination of Gases Using Polymer-Coated Semiconductor Sensors

Comparative characteristics of Pt-doped SnO₂ sensors with coatings of different depths were studied. It was found that the application of a thin membrane layer enhanced the selectivity and improved the stability of the sensor, as well as its sensitivity in detecting hydrogen in the air.     

Paramagnetism in copper monoxide systems

This paper describes the problem of high-temperature superconductivity related to investigations of the magnetic susceptibility, electron paramagnetic resonance, and O Kα x-ray emission spectra of samples from the following systems based on copper monoxide: CuO-Cu, CuO-Cu₂O and CuO-MgO. In all these systems, thermal processing results in a paramagnetism which is not observed in the individual components of these systems before they are processed. O Kα spectra of the interface of a Cu-single-crystal CuO film structure indicate the presence of not only Cu²⁺ but also Cu¹⁺ ions in the layer of CuO in close contact with Cu. Possible reasons for the appearance of paramagnetism in these systems are discussed. It is proposed that a paramagnetic layer at the contact between the antiferromagnetic copper monoxide and the other copper-oxide phases or with copper could be the cause of the impurity metastability observed previously in the high-T _c superconducting phase. Fiz. Tverd. Tela (St. Petersburg) 40, 295–298 (February 1998)