Linear parameters of helical instability in thick silicon wafers at 300 K

An analysis is performed on the dependence of the threshold electric field intensity (E_t) of helical instability of a semiconductor plasma on the magnetic induction and threshold frequency on E_t at a temperature of 300 K allowing for the form of the volt-ampere characteristic curve of the specimen. It is shown that when the field dependence of the charge carrier concentration in the specimen is taken into account, the variation in the rate of surface recombination and volume lifetime in the process of preparing the specimen, the variation in the path of the threshold curve, and the variation in the field dependence of the threshold frequency are satisfactorily described by helical instability theory for the case of a homogeneous plasma for n p and _{n p}. The basic cause of incomplete matching of the experimental and theoretical curves is apparently due to not fulfilling the condition on homogeneity of the plasma and the electric field in the presence of the injection of charge carriers from the contacts.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 49–53, August, 1991.The author is grateful to Yu. V. Medvedev for performing the measurements of the parameters by microwave techniques and to O. N. Merkulova for her assistance in writing the computer program.     

The influence of the length and concentration of chopped carbon fiber on physical and mechanical properties of siloxane matrix

In this paper, the influence of the concentration and length of chopped carbon fiber on the physical and mechanical characteristics of siloxane matrix was investigated. It is shown that the highest values can be achieved at 2–5 wt % loading of chopped carbon fiber with a length of 3 mm. In this case, the elastic modulus increases by five to eight times in comparison with unmodified composite. Destruction of such materials takes place in accordance with an adhesive–cohesive mechanism, which testifies to the existence of relative adhesion of siloxane binder to carbon fiber.     

Kink instability of the semiconductor plasma in silicon parallelepipeds

Experimental results on the onset of the kink instability of the semiconductor plasma in silicon p⁺-p-n⁺ structures are analyzed. The structures were parallelepipeds. The experiments were carried out over the temperature range from 77 to 300 K. The shape of the current-voltage characteristics and that of the threshold curves of the test samples are discussed. The frequency and amplitude of the alternating current which arises as a result of the kink instability are described as a function of the electric field and the magnetic induction at levels substantially above the excitation threshold.V. D. Kuznetsov Siberian Physicotechnical Institute, Tomsk State University. Scientific-Research Institute of Semiconductor Devices. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 103–110, May, 1992.     

The Integrative Approach to Study of the Structure and Functions of Cardiac Voltage-Dependent Ion Channels

Crystallography Reports - Membrane proteins, including ion channels, became the focus of structural proteomics midway through the 20th century. Methods for studying ion channels are diverse and...     

Upper and Lower Lebesgue Classes of Multivalued Functions of Two Variables

Ukrainian Mathematical Journal - We introduce a functional Lebesgue classification of multivalued mappings and obtain results on the upper and lower Lebesgue classifications of multivalued mappings...     

Depth of focus of intraocular lenses with higher-order aberrations

The optimization problem of increasing the depth of the sharply imaged space of the intraocular lens is considered depending on its phase transmission. For a set of aberrations with axial symmetry, the phase profile of the model optical system is determined, which makes it possible to obtain recognizable images of a test object placed at a distance from 5 m to 40 cm.     

Experimental investigation of the nonlinear properties of the surface helical instability in germanium

The results of an experimental investigation of the parameters of the surface helical instability (SHI) in germanium are presented. The dependence of the amplitude of the current oscillations of the helical wave and frequency on the electric E and magnetic B fields with E and B significantly exceeding the threshold values E_t and B_t are presented for the case of nonequilibrium (for temperatures T < 343°K) and equilibrium (T 343°K) plasma. It is shown that for small supercriticality (_E = (E-E_t)/Et 1, = ( -_t)/_t 1) > the square of the amplitude of the current oscillations and the frequency shift are proportional to the supercriticality, i.e., the regime for excitation of SHI is soft.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 18–21, May, 1981.     

Equiconnected spaces and Baire classification of separately continuous functions and their analogs

We investigate the Baire classification of mappings f: X × Y → Z, where X belongs to a wide class of spaces which includes all metrizable spaces, Y is a topological space, Z is an equiconnected space, which are continuous in the first variable. We show that for a dense set in X these mappings are functions of a Baire class α in the second variable.