Institute for Command Engineers

Minsk, Belarus

Institute for Command Engineers

Minsk, Belarus
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Bashkirov L.A.,Belarusian National Technical University | Slonskaya S.V.,Belarussian State Agrarian Technical University | Lubinskii N.N.,Institute for Command Engineers | Galyas A.I.,National Academy of Sciences of Belarus | And 2 more authors.
Inorganic Materials | Year: 2014

We have found that the 77-K magnetization per formula unit of the SrFeO3 - δ ferrite, Sr0.9La0.1Fe 0.9Cd0.1O3 - δ and Sr 0.75La0.75Fe0.75Cd0.75O 4 - δ mixed oxides, and SrLaFeO4 compound, calculated per mole of Fe ions, is 0.114μB, 0.024μB, 5 × 10-3 μB, and 4.3 × 10-2 μB, respectively. The resultant effective magnetic moment of the Fe3+ and Fe4+ ions (μeffFe3+,Fe4+) in the Sr0.9La0.1Fe0.9Cd0.1O 3 - δ solid solution in the temperature range 520-850 K is 3.61μB, and (μeffFe3+,Fe4+) in Sr 0.75La0.75Fe0.75Cd0.75O 4 - δ and SrLaFeO4 in the temperature ranges 350-600 and 100-550 K is 5.89μB and 5.70μB, respectively. © 2014 Pleiades Publishing, Ltd.

Stsiapura V.I.,Kupala State University | Kurhuzenkau S.A.,Kupala State University | Kuzmitsky V.A.,Institute for Command Engineers | Bouganov O.V.,National Academy of Sciences of Belarus | Tikhomirov S.A.,National Academy of Sciences of Belarus
Journal of Physical Chemistry A | Year: 2016

It has been established earlier that fluorescence quantum yield of thioflavin T (ThT) - a probe widely used for amyloid fibrils detection - is viscosity-dependent, and photophysical properties of ThT can be well-described by the fluorescent molecular rotor model, which associates twisted internal charge transfer (TICT) reaction with the main nonradiative decay process in the excited state of the dye. Solutions of ThT in a range of polar solvents were studied using steady-state fluorescence and sub-picosecond transient absorption spectroscopy methods, and we showed that solvent effect on nonradiative transition rate knr cannot be reduced to the dependence on viscosity only and that ∼3 times change of knr can be observed for ThT in aprotic solvents and water, which correlates with solvent polarity. Different behavior was observed in alcohol solutions, particularly in longer n-alcohols, where TICT rate was mainly determined by rotational diffusion of ThT fragments. Quantum-chemical calculations of S0 → S1 transition energy were performed to get insight of polar solvent contribution to the excited-state energy stabilization. Effect of polar solvent on electronic energy levels of ThT was simulated by applying homogeneous electric field according to the Onsager cavity model. Static solvent effect on the excited-state potential energy surface, where charge transfer reaction takes place, was not essential to account for experimentally observed TICT rate differences in water and aprotic solvents. From the other side, nonradiative decay rate of ThT in water, ethylene glycol, and aprotic solvents was found to follow dynamics of polar solvation knr ∼ τS -1, which can explain dependence of the TICT rate on both polarity and viscosity of the solvents. © 2016 American Chemical Society.

Pershukevich P.P.,National Academy of Sciences of Belarus | Volkovich D.I.,National Academy of Sciences of Belarus | Gladkov L.L.,Higher State College of Communications | Dudkin S.V.,Organic Intermediates and Dyes Institute | And 4 more authors.
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2014

The effect of the addition of phenyl groups to pyrrole rings of tetraazachlorins, a new class of tetrapyrroles, on the photophysical properties and electronic structure of the molecules has been investigated by a complex of experimental and theoretical methods. Characteristics of fluorescence at 293 and 77 K have been determined for phenyl-substituted tetraazachlorins. The objects of this study include unsubstituted tetraazaporphine. The introduction of phenyl groups affords a marked increase in the fluorescence quantum yield. For tetraazaporphine and phenyl-substituted tetraazachlorins, fluorescence buildup occurs as the temperature is decreased from 293 to 77 K, but to a lesser extent than for tetraazachlorins having no phenyl groups, which were earlier studied by the authors. The fluorescence buildup mechanism is discussed. The singlet oxygen generation quantum yield has been determined for the tetrapyrroles examined. This characteristic increases upon tetrapyrrole is phenylation. The electronic structure and absorption spectra of unsubstituted porphine and chlorin, tetraazaporphine, tetraazachlorin, octaphenyltetraazaporphine, and tetramethylhexaphenyltetraazachlorin have been calculated by the INDO/Sm method (original modification of the INDO/S method) with molecular geometry optimization using DFT. The results of the quantum-chemical calculation of the absorption spectra are in good agreement with experimental data for transitions to the lowest excited electronic states Qx(S1) and Qy(S2). © 2014, Pleiades Publishing, Ltd.

Goncharenko I.A.,Belarusian State University | Goncharenko I.A.,Institute for Command Engineers | Kabanova O.S.,Belarusian State University | Melnikova E.A.,Belarusian State University | And 3 more authors.
International Conference on Transparent Optical Networks | Year: 2016

In this paper the techniques to create the liquid-crystal (LC) photonic structures with the controllable configuration of anisotropy are proposed. The regularities in propagation and transformation of the light beams in such structures are analyzed. Experimental implementation of the waveguide propagation and signal multiplexing regimes based on the total internal reflection of radiation from the electrically controlled interface of two LC regions with planar orthogonal orientation of the director, and also the formation of waveguide channels due to the graded index distribution on application of the voltage to the LC cell electrodes is described. © 2016 IEEE.

Knyukshto V.N.,B. I. Stepanov Institute of Physics | Volkovich D.I.,B. I. Stepanov Institute of Physics | Gladkov L.L.,Higher State College of Communications | Kuzmitsky V.A.,Institute for Command Engineers | And 4 more authors.
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2012

We have performed complex experimental and theoretical investigations of the spectral-luminescent properties and electronic structure of new phthalocyanine analogs, Mg octaphenylporphyrazine and its derivatives with an annulated thiadiazole or selenadiazole ring instead of two phenyl groups. Fluorescence characteristics have been determined at 293 and 77 K: emission, excitation, and fluorescence polarization spectra; fluorescence quantum yield φF, and lifetime τF. Annulation of a five-membered chalcogen-containing heterocycle leads to splitting of the long-wavelength absorption band Q(0-0) and to the bathochromic shift of its longest wavelength component Qx(0-0), which increase upon passage from S to Se. At the same time, the fluorescence quantum yield φF and lifetime τF decrease, which is related to the intramolecular heavy-atom effect. The geometric structure of the ground state of the Mg porphyrazine molecules has been determined based on the density functional theory (DFT), and excited electronic states have been calculated with modified parametrization of the INDO/S method, INDO/Sm. Semiquantitatively, the calculated level positions of the lowest Q states and spectral shifts of Mg octaphenylporphyrazine and S-derivative agree with experimental data. For the range of the Soret band, calculated transition energies and their intensity distributions substantially depend on the dihedral angle γ between a phenyl ring and porphyrazine macrocycle. We show that, based on calculations at the angle γ = 60°, bands in the observed absorption spectra can be assigned with an accuracy of ~2000 cm-1. © Pleiades Publishing, Ltd., 2012.

Goncharenko I.A.,Institute for Command Engineers | Kireenko V.,Belarusian National Technical University | Marciniak M.,National Institute of Telecommunications | Marciniak M.,Kielce University of Technology
Optical Engineering | Year: 2014

We consider the design methods and operation principles of a fast-response optical sensor for precise measurement of small temperature variations, which is based on ring resonators of micron size made from waveguides with one or two slots filled by a liquid crystal. The sensor sensitivity and measurement region can be changed by modifying the parameters of the waveguide or resonator, such as width of the waveguide strips or slots, slot separation, resonator bend radius, coefficient of coupling between the ring and input/output waveguides, etc. We analyzed the dependence of the transverse field distribution and effective indices of the orthogonally polarized modes in the slot and double-slot waveguides on the waveguide and resonator parameters, and we have considered the optimization of the temperature sensor structure based on such waveguides. © 2014 Society of Photo-Optical Instrumentation Engineers.

Goncharenko I.,Institute for Command Engineers | Marciniak M.,National Institute of Telecommunications
International Conference on Transparent Optical Networks | Year: 2011

In paper the optical sensor allowing measuring both a direction and bend and stress values in building structures is described. The sensitive element of the sensor is the microstructured fiber with three cores. Distribution of mode fields in fiber cores depending on fiber structure and bend value is analyzed. The optimization of the sensitive element parameters depending on the purpose of use is proposed. © 2011 IEEE.

Leshenyuk N.S.,Institute for Command Engineers | Apanasevich E.E.,Institute for Command Engineers | Tereshenkov V.I.,Institute for Command Engineers
Biophysics (Russian Federation) | Year: 2014

Induced oscillations and periodic displacements of equilibrium positions were shown to occur in biomacromolecules in the absence of electromagnetic radiation absorption because the external electromagnetic field modulates the interaction potential between atoms and groups of atoms forming nonvalence bonds in macromolecules. This “hyperoscillation” state inevitably changes the biochemical properties and conformational transformation times of macromolecules. © 2014, Pleiades Publishing, Inc.

Goncharenko I.,Institute for Command Engineers | Marciniak M.,National Institute of Telecommunications
International Conference on Transparent Optical Networks | Year: 2013

We analyze the dependence of transverse field distribution and effective indices of the two orthogonally polarized modes in slot and double-slot waveguides on waveguide parameters (slot width, slot separation) and bend. Optimization of the parameters of microring resonator on the base of such waveguides used as a temperature sensor is considered. © 2013 IEEE.

Kurochkin Y.,B. I. Stepanov Institute of Physics | Otchik V.,Institute for Command Engineers
Nonlinear Phenomena in Complex Systems | Year: 2012

A possibility to define an analog of a uniform electric field in the Lobachevsky space is considered. Schrödinger equation for the hydrogen atom in this electric field is separated and Stark shifts of energy levels are evaluated.

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