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An assessment of the health indicators of young people in Uzbekistan was carried out based on the results of immunological screening - determining the quantitative content of antigen-binding lymphocytes (ASL), sensitized to tissue antigens (TA) of various organs. For a comparative study, male and female volunteers aged 18-25 years old living in Tashkent city of the Tashkent region (northern region) and in the city of Termez of the Surkhandarya region (southern region) of Uzbekistan was examined. Consequently, in the southern region of Uzbekistan (Termez), the frequency of manifestation of pathological processes in various organs is relatively higher than in the northern region (Tashkent). [ABSTRACT FROM AUTHOR]

An analysis is made of the low-temperature behavior of the chemical potential μ of a quasi-two-dimensional electron gas near the resonance point (at the bottom of the miniband) and far from it. Low-temperature analytical formulas for μ (T) are obtained under the conditions of the existence of an arbitrary number of minibands. It is shown that with the increasing temperature near the resonance point, the chemical potential decreases linearly and exponentially slowly in the middle of the resonance points. Analytical formulas are compared to the numerical solutions. [ABSTRACT FROM AUTHOR]

Technology has been developed for generating a vapor phase in a separate evaporator at a temperature of 80–120°C by dropping a mixture in a quasi-closed reactor with the help of chemical vapor deposition (CVD). Tin oxide (SnO2) layers were grown on the surface of single-crystal p-Si by chemical vaporization epitaxy and formed a microcrystalline structure on the substrate surface at a temperature of 170–500°C. The study of the spectral dependence of the photosensitivity of the n-SnO2/p-Si heterostructure with an aluminum back contact showed that the inversion of photocurrent photosensitivity occurred associated with the formation of an inbuilt electric field that was generated at the boundary of the frontal electric contact between Al and p-Si and counter connected to the main potential barrier of the n-SnO2/p-Si heterojunction. [ABSTRACT FROM AUTHOR]

The energy of electrons and holes in cylindrical quantum wires with a finite potential well was calculated by two methods. An analytical expression is approximately determined that allows one to calculate the energy of electrons and holes at the first discrete level in a cylindrical quantum wire. The electron energy was calculated by two methods for cylindrical layers of different radius. In the calculations, the nonparabolicity of the electron energy spectrum is taken into account. The dependence of the effective masses of electrons and holes on the radius of a quantum wires is determined. An analysis is made of the dependence of the energy of electrons and holes on the internal and external radii, and it is determined that the energy of electrons and holes in cylindrical layers with a constant thickness weakly depends on the internal radius. The results were obtained for the InP/InAs heterostructures. [ABSTRACT FROM AUTHOR]

The influence of the cross-sectional shape of a quantum filament on the energy spectrum of electrons is studied. The calculation of energy levels of electrons in a quantum wire is performed. For the AlxGa1 - xAs quantum wire with infinite and finite depths, energy level spectra were obtained. The dispersion dependence with a parabolic law in a quantum wire with finite and infinite height of the potential barrier based on Al0.25Ga0.75As and Al0.75Ga0.25As was calculated, and graphs of dispersion dependences were obtained. The results are obtained for the linear sizes of a quantum wire from 5 nm to 15 nm. The transverse dimensions of cylindrical and rectangular quantum wires with close energy levels are found. The analysis of energy levels in cylindrical and rectangular quantum wires is carried out, and their similarities are revealed. It is shown that the energy levels are close to each other when the cross-sectional areas of rectangular and cylindrical quantum wires become equal. The solutions of the Schrödinger equation are presented, when the solution for a cylindrical wire can be replaced by the solution for a rectangular wire. [ABSTRACT FROM AUTHOR]

Numerical and analytical results of the investigation of the thermodynamic properties of a quasi-2D electron gas are presented. The density of states, the temperature derivative of the chemical potential, and the heat capacity of the gas at the resonance points and away from it are analyzed. It is shown that, in the dependence of the heat capacity on the chemical potential, there are additional steps at the resonance points. The width of the additional steps increases with temperature. With the increase in temperature, when the main steps are practically blurred, there are still visible marks from the additional steps. [ABSTRACT FROM AUTHOR]

Mathematical models for the Shubnikov-de Haas oscillations in semiconductors are obtained at the microwave-radiation absorption and its temperature dependence. Three-dimensional image of microwave magnetoabsorption oscillations in narrow-gap semiconductors is established. Using a mathematical model, the oscillations of the microwave magnetoabsorption are considered for different values of the electromagnetic field. The results of calculations are compared with experimental data. The proposed model explains the experimental results in HgSe at different temperatures. [ABSTRACT FROM AUTHOR]

Simulation of the temperature dependence on the microwave magnetoabsorption oscillations in electronic semiconductors is conducted using the Gaussian function and derivative of the Fermi-Dirac function by energy. Gaussian distribution function and derivative of the Fermi-Dirac function by energy are compared at different temperatures. It is shown that the distribution of the Gauss function is much more efficient and more rapidly tends to an ideal Dirac δ-function than the derivative of the Fermi-Dirac function by energy. The temperature dependence of the spectral density of states in semiconductors is calculated at quantizing magnetic fields. An analytical expression is obtained for the density of states in a quantizing magnetic field for narrow-gap semiconductors. Graphs of the temperature dependence of the density of states for InAs are constructed in a quantizing magnetic field. Oscillations of the absorption of microwave radiation in semiconductors are considered at different temperatures. A new mathematical model has been created for microwave absorption oscillations in narrow-band semiconductors. Using this model, the dependence of quantum oscillation phenomena on microwave absorption and temperature is calculated in electron gases. Graphs of oscillations of the derivative of the absorbed power by the magnetic field strength are obtained for InAs. A three-dimensional image of the absorption of microwave radiation for semiconductors has been constructed with the Kane dispersion law. The microwave magnetoabsorption oscillation was calculated in narrow-gap electronic semiconductors at different temperatures using the Gauss function. Formula for the dependence of the microwave magnetoabsorption oscillations on the electric field strength of an electromagnetic wave and temperature is obtained with the parabolic and Kane dispersion law. The calculation results are compared with experimental data. The proposed model explains the experimental results in HgSe at different temperatures. [ABSTRACT FROM AUTHOR]

The influence of pressure on the oscillations of Shubnikov-de Haas (ShdH) and de Haas-van Alphen (dHvA) in semiconductors is studied. Working formula for the calculation of the influence of hydrostatic pressure on the Landau levels of electrons is obtained. The temperature dependence of quantum oscillations for different pressures is determined. The calculation results are compared with experimental data. It is shown that the effect of pressure on the band gap is manifested to oscillations and ShdH and dHvA effects in semiconductors. [ABSTRACT FROM AUTHOR]