Controlling the Spin Polarization of the Electron Current in a Semimagnetic Resonant-Tunneling Diode

The spin filtering effect of the electron current in a double-barrier resonant-tunneling diode (RTD) consisting of ZnMnSe semimagnetic layers has been studied theoretically. The influence of the distribution of the magnesium ions on the coefficient of the spin polarization of the electron current has been investigated. The dependence of the spin filtering degree of the electron current on the external magnetic field and the bias voltage has been obtained. The effect of the total spin polarization of the electron current has been predicted. This effect is characterized by total suppression of the spin-up component of electron current, that takes place when the Fermi level coincides with the lowest Landau level for spin-up electrons in the RTD semimagnetic emitter

Electron spin relaxation via flexural phonon modes in semiconducting carbon nanotubes

This work considers the g-tensor anisotropy induced by the flexural thermal vibrations in one-dimensional structures and its role in electron spin relaxation. In particular, the mechanism of spin-lattice relaxation via flexural modes is studied theoretically for localized and delocalized electronic states in semiconducting carbon nanotubes in the presence of magnetic field. The calculation of one-phonon spin-flip process predicts distinctive dependencies of the relaxation rate on temperature, magnetic field and nanotube diameter. Comparison with the spin relaxation caused by the hyperfine interaction clearly suggests the relative efficiency of the proposed mechanism at sufficiently high temperatures. Specifically, the longitudinal spin relaxation time in the semiconducting carbon nanotubes is estimated to be as short as 30 microseconds at room temperature.Comment: 18 pages, 7 figure

First Principles Analysis of Electron-Phonon Interaction in Graphene

The electron-phonon interaction in monolayer graphene is investigated by using density functional perturbation theory. The results indicate that the electron-phonon interaction strength is of comparable magnitude for all four in-plane phonon branches and must be considered simultaneously. Moreover, the calculated scattering rates suggest an acoustic phonon contribution that is much weaker than previously thought, revealing the role of optical phonons even at low energies. Accordingly it is predicted, in good agreement with a recent measurement, that the intrinsic mobility of graphene may be more than an order of magnitude larger than the high values reported in suspended samples.Comment: 12 pages, 4 figure

Investigations of the properties of solutions of impulsive differential systems in the linear approximation

Проведено якiсний аналiз властивостей розв’язкiв нелiнiйних iмпульсних систем диференцiальних рiвнянь iз збуреннями на деяких гiперповерхнях {ti(x)}. Отримано новi умови обмеженостi, практичної стiйкостi за Четаєвим (рiвномiрної, стискуючої), стiйкостi за Ляпуновим (рiвномiрної, асимптотичної), притягування розв’язкiв збурених систем за лiнiйним наближенням

Synthesis and examination of nanocomposites based on poly(2-hydroxyethyl methacrylate) for medicinal use

Preparation of poly(2-hydroxyethyl methacrylate) (PHEMA) based nanocomposites using different approaches such as synthesis with water as the porogen, filling of polymer matrix by silica and formation of interpenetrating polymer networks with polyurethane was demonstrated. Incorporation of various biologically active compounds (BAC) such as metronidazole, decamethoxin, zinc sulphate, silver nitrate or amino acids glycine and tryptophan into nanocomposites was achieved. BAC were introduced into the polymer matrix either (1) directly, or (2) with a solution of colloidal silica, or (3) through immobilization on silica (sol-densil). Morphology of prepared materials was investigated by laser scanning microscopy and low-vacuum scanning electron microscopy. In vacuum freeze-drying, prior imaging was proposed for improving visualization of the porous structure of composites. The interaction between PHEMA matrix and silica filler was investigated by IR spectroscopy. Adsorption of 2-hydroxyethyl methacrylate and BAC from aqueous solution on the silica surface was also examined. Phase composition and thermal stability of composites were studied by the differential thermogravimetry/differential thermal analysis. Release of BAC into water medium from prepared composites were shown to depend on the synthetic method and differed significantly. Obtained PHEMA-base materials which are characterized by controlled release of BAC have a strong potential for application in manufacturing of different surgical devices like implants, catheters and drainages. © 2017, The Author(s)

Assessment of the dynamics of individual indicators of the psychoemotional state of students of "UMSA"

Процес набуття професійних навичоку вищому навчальному закладі має суттєві відмінності від середньої освіти в школі. Період адаптації студента в умовахнавчання в ВУЗінесезначні навантаження на психоемоційний стан у зв’язку суттєвою зміною стереотипу поведінки за рахунок видозміни взаємозв’язків у спілкуванні, методології навчання та інших факторів, що безпосередньо супроводжується психологічним навантаженням на особистість крізь дію різноманітних соціально-економічних та психогенних чинників.Найбільш схильними до фрустрацій стають студенти медичних вищих навчальних закладів, оскільки інформаційне та емоційне навантаження на ще недостатньо сформовану психіку підлітківзростає, що, у свою чергу, безпосередньо стає одним із чинників, що впливають на рівень поведінкових розладів. Переїзд до нового міста, нові житлові умови погіршують процес пристосування студента

Професор Г.Л. Кулініч (09.12.1938 – 10.02.2022) – видатний вчений і педагог

Pages of the article in the issue: 11 - 21 Language of the article: UkrainianСторінки у випуску: 11 - 21 Мова статті: українськ