Features of the Interaction and Phase Formation in the WC–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>–C System When Heated in Vacuum and in Argon

Special features of the interactions and phase formations in carbide-oxide mixture WC 33.5 wt % Fe₂O₃ and in the WC–Fe₂O₃–C system when heated in vacuum and in argon have been studied. To add free carbon into carbide-oxide mixture, the K354 soot and saccharose, which dissociated when heated to high-clean carbon. It is established that at the absence of free carbon in the carbide-oxide system the active interaction between carbon of tungsten carbide and oxygen of iron oxide takes place that shows up in the weight loss of the samples. As a results there form the phase of the intermetallide Fe₇, W₆, the phase with a structure of the FeWO₄ and W. The addition of free carbon allows keeping tungsten carbide partly or completely and reducing iron from oxide. At the lack of free carbon some part of the tungsten carbide carbon starts to interact with oxygen and the Fe₃W₃C complex carbide forms in the system, at the excess of carbon the tungsten carbide retained and the bcc-iron forms. The heating in vacuum differs from the heating in argon by two indications: to remove the same amount of oxygen is spent more carbon than in heating in argon; the temperature of the active interaction of carbon with oxygen decreases. The largest (by 300°C) decrease of the temperature is observed when the saccharose is used as the source of free carbon.     

Current-Oscillation Power Growth in a Semiconductor Superlattice with Regard to Interminiband Tunneling

The total power of oscillations of current flowing through a semiconductor superlattice with different gaps between the first and second minibands is discussed. It is demonstrated that, with a decrease in the band gap, i.e., with an increase in the probability of interminiband tunneling, the total current-oscillation power increases when certain voltages are applied to the superlattice.     

Instability of the Flow in a Spherical Layer under Torsional Oscillations of the Inner Boundary

The instability of viscous incompressible fluid flows caused in a thin spherical layer by torsional oscillations of the inner sphere in a thin spherical layer with respect to the sate of rest is studied numerically. It has been established that an increase in the frequency of torsional oscillations leads to a change in the mode of the instability, with a transition from secondary flows in the form of Taylor vortices to structures not observed earlier. The revealed instability is observed in the frequency range from 0.61 to 2.45 Hz or, if the wavelengths are taken relative to the layer thickness, from 0.67 to 1.33.     

Zinc Diffusion into InP via a Narrow Gap from a Planar Zn<Subscript>3</Subscript>P<Subscript>2</Subscript>-Based Source

An original technology of zinc diffusion into InP via a narrow gap is described, which allows reproducible formation of p–n junctions with preset depth of doping and retained surface morphology of the doped layers. Using the proposed method, desired charge carrier distribution profiles in Zn-doped InP layers were obtained. It has been experimentally confirmed that the method of cross-sectional scanning electron microscopy allows to precision measure of the zinc diffusion depth.     

Spatial Effects of Interaction of a Shock with a Lateral Low-Density Gas Channel

Three-dimensional interaction of a shock with lateral low-density gas channel of round, elliptic or rectangular cross-section is numerically studied using Euler’s equations. The structure of formed shock wave precursor is described in detail. Internal shear layer instabilities in three-dimensional flow are shown to develop faster than in axisymmetric case. Moderate amplification of high-pressure jet cumulation effect is noted for elliptic and rectangular channel cases. Dependence of precursor growth rate on cross-section shape is studied. It is found that stretching of cross-section shape significantly increases the duration of linear precursor growth phase.     

Features of Switching Memristor Structures to a High-Resistance State by Sawtooth Pulses

Technical Physics Letters - It has been experimentally established that the time of switching by triangular pulses in Ti—TiN–ZrO2(Y)–Zr–Au memristor structures from the...     

Test Results of an Active System for Reducing Vibration Forces and Pressure Pulsations

Technical Physics Letters - The absence of literature data on active reduction of the transmission of vibrations and pulsations of pressure through pipeline compensators with liquid is noted. A...     

Stream Processing of Multichannel EEG Data Using Parallel Computing Technology with NVIDIA CUDA Graphics Processors

Technical Physics Letters - Prospects of using parallel computing technology (PaCT) methods for the stream processing and online analysis of multichannel EEG data are considered. It is shown that...     

Prevalence and incidence of hand dermatitis in hairdressing apprentices: results of the POSH study. Prevention of occupational skin disease in hairdressers

OBJECTIVE: Occupational skin changes in hairdressers are very common. Morbidity, however, has not yet been quantified precisely. METHODS: A cohort of 2,352 hairdressing apprentices (of the 2,570 invited to participate, i.e., 91.5% response) was prospectively followed for the duration of their vocational training (3 years) by three examinations. Three waves (years) were recruited in 1992, 1993, and 1994 from 15 vocational training schools in northwestern Germany. RESULTS: The point prevalence of (mostly slight) irritant skin changes of the hands increased from 35.4% in the initial examination to 47.5% in the intermediate examination and to 55.1% in the final examination. Given a more conservative definition of a case of "hand dermatitis," these estimates were 12.9%, 23.5%, and 23.9%, respectively. Altogether, 34.3 and 15.2 cases of "skin changes (any degree)" and "hand dermatitis," respectively, in 100 person-years were observed during the study period. The incidence rate, i.e., the number of newly diseased study participants in relation to the person-time at risk contributed, decreased in the course of the study. The proportion of dropouts until final follow-up was 51.8%. CONCLUSION: The present results appear to lie in a range with those found in other, much smaller cohort studies. However, comparison of the results is hampered either by the lack of a clear definition or by a different definition of "person-time at risk" or "a case of hand dermatitis." As compared with an external control group of office apprentices, the incidence was several times higher in hairdressing apprentices, which points to the high risk for skin damage in this occupation.