Magnito-, electro- and echocardiography in detecting symptoms of the "hypertensive heart"

The study compared diagnostic potential of magnetocardiography (MCG), electrocardiography (ECG) and echocardiography (echo-CG) in 18 patients with arterial hypertension (AH). 32 healthy males served as control. Elements of MCG from normal subjects have been analyzed morphologically in 36 points of precordial leads. Left ventricular hypertrophy was registered at echo-CG, MCG, ECG in 11 (61%), 16 (84%) and 7 (34%) of the AH patients, respectively. Left atrial hypertrophy was discovered primarily by echo-CG and MCG. Defects in ventricular repolarization were recorded by MCg in 7 (39%) patients basing on MCG, echo-CG and rarely ECG signs of left ventricular hypertrophy. MCG is recommended as an effective tool in diagnosis of "hypertensive heart".     

Equation of state of polytetrafluoroethylene for calculating shock compression parameters at megabar pressures

Semi-empirical equations of state (thermal and caloric) are obtained to calculate not only the kinematic parameters (shock wave velocity, particle velocity, and reverberation of waves) but also the thermodynamic parameters (temperature, pressure, and compression) of monolithic and porous polytetrafluoroethylene at high shock pressures. The equations of state are used to model wave interaction in shock-wave experiments using the developed hydrocode. The equations are verified by comparison simulation results with published results of experiments and the data of our shock compression tests of solid and porous samples of PTFE in the range of 10–170 GPa.     

Spectral Absorptivity and Thermal Conductivity of BGO and BSO Melts and Single Crystals

The present work describes the results of spectral absorptivity, α, and thermal conductivity, λ, studies for compound oxides Bi₄Ge₃O_12, Bi₁₂GeO_20, Bi₄Si₃O_12, and Bi₁₂SiO₂₀ in molten and monocrystalline states. The data for the spectral absorptivity were obtained by placing the sample onto a mirror and using the transmission method. To obtain the data on the thermal conductivity of crystals, the stationary method of two identical samples was used. The data for the thermal conductivity of melts were obtained by a new stationary relative method in which the thermal conductivity of the crystal is used as a reference. Special attention is focused on numerical and experimental error analysis at high temperature. The studies have shown that α in the range of a transmission band strongly depends on crystal purity. It varies from 0.0005 cm⁻¹ to 0.03 cm⁻¹ for Bi₄Ge₃O₁₂ and reaches 0.15 cm⁻¹ for Bi₄Si₃O₁₂. It was found that α is significantly greater for melts than for crystals, reaching (150 to 200) cm⁻¹ for the Bi₄Ge₃O₁₂ melt. The thermal conductivity of the melts under investigation was found to be much smaller than that of the corresponding crystals.     

Numerical and Experimental Investigation of Crystal Growth Rate Dependence on Facet Undercooling for Dielectric Crystal Growth from the Melt

Combined experimental and numerical tools are developed and used to define more exactly the growth kinetic relations for (211) crystallographic orientation of Bi₄Ge₃O₁₂ (BGO) crystal growth—namely, the dependence of crystal growth rate V on supercooling, ΔT of the melt/crystal interface. A new apparatus for in situ measurements of the time dependence of the supercooling, ΔT(t), was used, and a new, two-dimensional numerical model was applied to analyze the effect of temperature boundary conditions and faceting phenomena on the character of the observed V(ΔT) dependence. The measurements of the ΔT(t) dependence show that there is a large enough undercooling and a novel effect of the appearance of the local maximum on ΔT(t) dependence at the finish of crystallization. Results on V(ΔT) dependence show that, for the variant of the crystal growth technique used (melt cooling during axial heating process method [AHP]), the type of the V(ΔT) dependence does not depend on boundary conditions. The new investigations illustrate the superlinear behavior for V(ΔT) dependence for (211) BGO crystallographic orientation and show that previous data on sublinear behavior of V(ΔT) dependence for this crystallographic orientation of BGO have not been justified.     

The Spall Strength and Dynamic Yield Stress of Hafnium

Technical Physics Letters - The spall strength and dynamic yield stress of polycrystalline hafnium have been measured in a series of plane-wave shock loading experiments using flat...     

Shock-wave-induced grain refinement and phase state modification in coarse-grained and nanocrystalline titanium

Technical Physics Letters - We have experimentally studied the structure and phase variations in polycrystalline titanium stimulated by stepwise shock compression at pressures up to 40 GPa with...