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Abstract—X-ray and neutron diffraction are indispensable in the analysis of the integral characteristics of the dispersed precipitates in high-strength medium-carbon steels. Advantages and limitations of methods application have been compared by studying changes in qualitative and quantitative compositions of dispersed phases of the wear-resistant B1700 steel after quenching and tempering in the temperature range of 150–600°C. The quantity of retained austenite decreases to zero when the tempering temperature rises above 300°C. Cementite becomes noticeable in the diffraction patterns in the same temperature range. The results of the study show that neutron instruments can more reliably detect small amounts of retained austenite, while X-ray instruments provide better resolution, especially at large scattering angles.

Abstract: Modified carboxymethyl cellulose (CMC) biopolymer materials are widely used in various fields of medicine. For different medical purpose and therapeutic goals, it is required to regulate the degree of biodegradation of implanted biopolymers by synthesizing modified gels using substituted oxyrane crosslinkers—1,4-butanediol diglycidyl ether (BDDE) and polyethylene glycol diglycidyl ether (PEGDE). However, their high cost dictates the urgency of investigation of new crosslinking agents that will be cheaper and at the same time will not require a change in the technological process. So, the crosslinking agent polypropylene glycol diglycidyl ether (PPGDE) was chosen. In this work the rheological and structural properties of modified CMC gels with a new crosslinking agent—polypropylene glycol diglycidyl ether (PPGDE)—were investigated and compared with the properties of both unmodified CMC and modified CMC using BDDE and PEGDE. It is shown the modified samples have a 2–3 times higher viscosity in comparison with unmodified CMC. The sample modified with PPGDE showed high viscosity and shear force; however, the difference in comparison with the other samples is small. The degree of modification of all gels is similar, but the degree of crosslinking of PPGDE is practically absent. However, owing to the low degree of crosslinking in the rest of the samples, this parameter has no effect on the viscosity of the solution. The cytotoxicity of all gels was also tested, which confirmed their low toxicity. Thus, gels using a new crosslinking agent—PPGDE—exhibit properties similar to both BDDE and PEGDE, which makes it possible to predict other properties and effects in practical use.

Properties of light characteristics of external-cavity high-power semiconductor lasers with an active region based on a single InGaAs quantum well operating at ultrahigh pulsed currents are studied. A maximum peak power of 45 W at 110 A (from the aperture of 100 µm), a linewidth of 0.15 nm, and a wavelength in the range of 1040–1070 nm are demonstrated for an external-cavity laser. The tuning range narrows with an increase in the pump current from 27 nm at a current of 20 A to 23 nm at a current of 100 A. The maximum side-mode suppression ratio is up to 45 dB in the central region of the tuning range, while at the edges of this range it was no worse than 20 dB. It is determined that the tuning range of the laser spectrum is limited by the onset of an additional Fabry–Perot cavity line in the spectrum.

Recent experiments performed on heating of matter using intense uranium beams generated by the heavy ion synchrotron, SIS18, at the Gesellschaft für Schwerionenforschung (GSI) Darmstadt, have shown that using the present beam parameters, one can achieve near critical states of lead. The beam intensity was $4\cdot10^9$ions per bunch that was 130 ns long while the particle energy was 350 AMeV. A fast 6-channel pyrometer has been developed at the GSI in collaboration with scientists from the Institute of Problems of Chemical Physics (IPCP), Chernogolovka, to measure the temperature of the heated material. Temperatures from 1500 K to 5000 K were recorded for metallic targets.

We report an experimental study of power characteristics of semiconductor lasers based on MOVPE-grown asymmetric separate-confinement heterostructures with a broadened waveguide as functions of cavity length, stripe contact width and mirror reflectivities. It is shown that at high current pump levels, the variation of the cavity parameters of a semiconductor laser (width, length and mirror reflectivities) influences the light - current (L - I) characteristic saturation and maximum optical power by affecting such laser characteristics, as the current density and the optical output loss. A model is elaborated and an optical power of semiconductor lasers is calculated by taking into account the dependence of the internal optical loss on pump current density and concentration distribution of charge carriers and photons along the cavity axis of the cavity. It is found that only introduction of the dependence of the internal optical loss on pump current density to the calculation model provides a good agreement between experimental and calculated L - I characteristics for all scenarios of variations in the laser cavity parameters.

Semiconductor lasers based on MOVPE-grown asymmetric separate-confinement heterostructures with a broadened waveguide and emitting in the wavelength range 1.0 - 1.1 um are studied. It is found that the intensity of spontaneous emission from the active region increases with increasing pump current above the lasing threshold and that this is caused by a growth in the concentration of charge carriers in the active region due to the modal gain enhancement needed to compensate for the growing internal optical loss at high pulsed pump currents. It is shown that the increase in the internal optical loss with increasing pulsed pump current is one of the main reasons for saturation of the light - current characteristics of high-power semiconductor lasers.

The article is devoted to the search of a way to solve one of the fundamental problems of economic analysis of industrial markets, that is, the identification of the market structure type, lying at the interface of oligopoly and monopolistic competition or oligopoly and monopoly. It is proposed to conduct such an identification procedure on the base of using the instruments of L. Zadeh’s possibility theory. The proposed approach has been evaluated on the example of the fish production market in Primorskii krai.

Development of new diagnostic techniques allowed, during the past few years, for a first series of measurements on the electrical resistivity of heavy ion beam generated high energy density (HED) matter. The experimental investigations have been carried out at the HHT laboratory of the Plasma Physics Department of the Gesellschaft für Schwerionenforschung in Darmstadt. In this report we review the results of these experiments and discuss future experimental and theoretical work planned to be carried out within the framework of the HEDgeHOB collaboration for precise determination of the electrical resistivity of HED matter.

We present the results of interference studies of a diode-pumped active disk element made of a gadolinium -- gallium -- garnet (GGG:Nd) crystal. The disk is cut perpendicular to the crystallographic axis [001], along which the pump beam propagates. With absorbing pump radiation, a thermal lens, which has been investigated by the interference methods using linearly polarised probe radiation, is formed in the disk. At the absorbed pump power up to 12 W, the interference pattern near the disk surface is a system of concentric rings. With increasing absorbed pump power up to 24 W, the outer rings transform into hexagons. It is shown that such an interference pattern in the garnet crystal is caused by thermally induced birefringence.

Recent experiments performed on heating of matter using intense uranium beams generated by the heavy ion synchrotron, SIS18, at the Gesellschaft f?r Schwerionenforschung (GSI) Darmstadt, have shown that using the present beam parameters, one can achieve near critical states of lead. The beam intensity was 4.109 ions per bunch that was 130?ns long while the particle energy was 350?AMeV. A fast 6-channel pyrometer has been developed at the GSI in collaboration with scientists from the Institute of Problems of Chemical Physics (IPCP), Chernogolovka, to measure the temperature of the heated material. Temperatures from 1500?K to 5000?K were recorded for metallic targets.

The structural-group composition of samples of organic matter of Chara sapropel and Characeaealgae was studied by 1H NMR.

Results of experiments on the expansion of shock-compressed nickel samples into helium are presented. An isentrope with an initial pressure of 170 GPa was studied. The radiance temperature of the nickel sample and the velocity of the shock wave, generated in helium, were measured by a fast multichannel optical pyrometer; other parameters, such as the particle velocity, the pressure on the He-Ni interface, and the temperature of He were calculated using He Hugoniot (chemical plasma model). To increase the shock entropy up to a near-critical value and to intensify the process of heat-mass transfer, porous samples were used. Final states with pressures below 1.5 GPa, determined by the initial He pressure, were generated. The isobaric overheat of nickel by hot shocked helium provided an information about the nickel liquid spinodal. The change in slope of an isentrope in the pressure-particle velocity plane allowed an estimate of the point of its entrance in the two-phase region. Estimates of the critical temperature and pressure were made from peculiarities of P-Tpath, using various models of the nickel liquid spinodal to represent experimental data.

A method of direct determining the discontinuous rotational reorientation angles from NQR exchange spectra based on recording of two-dimensional nutations of magnetization after the mixing period is suggested. The possible modification of the Jeener pulse sequence with independently varying duration of pulses for obtaining a 2D exchange nutation spectrum is described. Shapes of singularities in the 2D nutation spectrum of CCl2- and CCl3-group reorientations, which depend on the angle θSbetween C–Cl bonds and on the asymmetry parameter for nonequivalent positions of nuclei participating in the exchange are examined. The 2D exchange NQR nutation spectra of 35Cl in powders prepared from C2Cl4and C2Cl6molecular crystals are modeled. The advantages and capabilities of the method are discussed.

A method of studying the absorption coefficient in layers of semiconductor lasers is proposed. Using lasers based on MOVPE-grown separate-confinement heterostructures with a broadened waveguide, the absorption coefficient is investigated under pulsed current pumping. It is found that when the pump current flows through the laser in question, an additional internal optical absorption arises in the heterostructure layers. It is shown that an increase in the pump current density up to 20 kA cm-2 leads to an increase in absorption up to 2.5 cm-1. The feasibility of studying free-carrier absorption in the active region is demonstrated.

We demonstrate the employment of single-crystal optical fibres based on lithium niobate for doubling the laser radiation frequency. The measured characteristics of the fibre confirm its high quality and spatial homogeneity. Parameters of the frequency doublers for neodymium laser radiation (l = 1 mm) based on fibre and bulk single crystals are compared. Single crystals are grown by the method of laser-heated pedestal growing with heating by radiation of a CO2 laser (LHPG-method).

Without Abstract:

Experiments were performed to investigate the behavior of lead near its critical point. Emission spectra of shocked lead samples during unloading into helium at different initial pressures were measured by an optical multichannel analyzer (OMA), as well as by a fast optical pyrometer. To describe the obtained experimental data, a model of a thin mixture layer was suggested, in which helium emits due to the presence of external electrons from lead.

A method of concentrating the tritium in water samples by means of distillation under vacuum (~100 mm Hg) is suggested and experimentally verified. The degree of tritium enrichment is determined by the change in concentration of stable isotopes (oxygen or deuterium) on distillation of the sample. Two variations of the calculation are proposed: for the stationary state with the attainment of the maximtu~ possible degree of fractionation and cessation of enrichment at the nonstationary state.

Development of new diagnostic techniques allowed, during the past few years, for a first series of measurements on the electrical resistivity of heavy ion beam generated high energy density (HED) matter. The experimental investigations have been carried out at the HHT laboratory of the Plasma Physics Department of the Gesellschaft f?r Schwerionenforschung in Darmstadt. In this report we review the results of these experiments and discuss future experimental and theoretical work planned to be carried out within the framework of the HEDgeHOB collaboration for precise determination of the electrical resistivity of HED matter.

We present the results of interference studies of a diode-pumped active disk element made of a gadolinium — gallium — garnet (GGG:Nd) crystal. The disk is cut perpendicular to the crystallographic axis [001], along which the pump beam propagates. With absorbing pump radiation, a thermal lens, which has been investigated by the interference methods using linearly polarised probe radiation, is formed in the disk. At the absorbed pump power up to 12 W, the interference pattern near the disk surface is a system of concentric rings. With increasing absorbed pump power up to 24 W, the outer rings transform into hexagons. It is shown that such an interference pattern in the garnet crystal is caused by thermally induced birefringence.

The efficient technology is developed for growing high-quality doped single-crystal fibres by the mini-pedestal method with laser heating. The technology can be used to fabricate high-quality doped single-crystal fibres with a controllable radial gradient of the refractive index. The refractive-index profile in single-crystal fibres is studied experimentally. The efficient operation of a Nd3+: YAG single-crystal fibre laser in the waveguide regime was demonstrated upon longitudinal pumping by a laser diode.

The efficient technology is developed for growing Cr- and Ca-doped gadolinium—gallium garnet single-crystal films of thickness up to 100 μm on large substrates (76 mm) by the method of liquid-phase epitaxy from a solution—melt. The dependences of the absorption spectra of films and optical losses at 1 μm on the growth conditions and the solution—melt composition are studied. It is shown that Cr4+ions are formed in the films, and these films can be used as passive Qswitches in lasers.