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Douayar A.,Mohammed V University | Abd-Lefdil M.,Mohammed V University | Nouneh K.,Mohammed V University | Prieto P.,Autonomous University of Madrid | And 3 more authors.
Applied Physics B: Lasers and Optics | Year: 2013

Photoinduced linear electrooptical (EO) effect was studied for Zinc oxide nanofilms doped by Nd. We have chosen Nd rare earth impurity with different contents to explore its influence on photoinduced EO. The kinetics of the photoinduced EO changes was studied. We have chosen the bicolor coherent 10 ns Nd:YAG laser pulses with power densities varying up to about 1 GW/cm2 as the photoinducing beam. The enhancement of the photoinduced liner EO and its relaxation was explored. Additionally, the study of the photoinduced trapping levels within the energy gap was performed and the explanation of the obtained results is given. © 2013 Springer-Verlag Berlin Heidelberg.


Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Gorgut G.P.,Lesya Ukrainka Eastern European National University | Parasyuk O.V.,Lesya Ukrainka Eastern European National University | Lakshminarayana G.,Los Alamos National Laboratory | And 2 more authors.
Journal of Physics and Chemistry of Solids | Year: 2011

In this work, we report on the structural and optical properties of novel Ag0.98Cu0.02GaGe3Se8 single crystals that were synthesized by the BridgmanStockbarger technique. We have performed illumination by 10.6 μm CO2 pulsed laser working in the microsecond time duration regime. Such illumination allows causing substantial changes for both pure electronic nonlinear optical effects like optical second harmonic generation as well as piezooptical effects described by the fourth rank tensors. The measurements of the piezo-optical effects were carried out at different temperatures. The effects are observed only during the IR CO 2 laser illumination and are disappeared after switching off the illumination. Simultaneously the IR induced optical second harmonic generation at Er:glass laser fundamental wavelength 1540 nm was performed during illumination by nanosecond Nd:YAG and Er3:glass laser. The observed effects allow to use the studied materials as promising for IR-optoelectronic devices. © 2011 Elsevier Ltd. All rights reserved.


Kozer V.R.,Lesya Ukrainka Eastern European National University | Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Olekseyuk I.D.,Lesya Ukrainka Eastern European National University | Parasyuk O.V.,Lesya Ukrainka Eastern European National University
Journal of Alloys and Compounds | Year: 2010

Crystal structure of the chalcogenide compounds Hg5Ga 2Se8, Hg5In2Se8, Hg 5Ga2Te8 and Hg5In2Te 8 was investigated by X-ray structural analysis (powder method) of alloys annealed at 500 K. These phases crystallize in space group F4-3m with unit cell parameters a ≈ 2a (HgIIX) - 11.6876(2) Å (Hg 5Ga2Se8), 11.8876(2) Å (Hg 5In2Se8), 12.4738(2) Å (Hg 5Ga2Te8) and 12.6723(2) Å (Hg 5In2Te8). © 2010 Elsevier B.V. All rights reserved.


Parasyuk O.V.,Lesya Ukrainka Eastern European National University | Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Gorgut G.P.,Lesya Ukrainka Eastern European National University | Khyzhun O.Y.,Ukrainian Academy of Sciences | And 3 more authors.
Optical Materials | Year: 2012

Quaternary single crystals Ag xGa xGe 1- xSe 2 (x = 0.333, 0.250, 0.200, and 0.167) have been grown by the two-zone Bridgman method. X-ray diffraction analysis has revealed that all the four compounds are crystallized in the noncentrosymmetric orthorhombic space group Fdd2. Position of constituent atoms in the unit cells of the Ag xGa xGe 1-xSe 2 single crystals have been determined. X-ray photoelectron core-level and valence-band spectra for pristine and Ar + ion-irradiated surfaces of the single crystals under consideration have been measured. It has been established that the Ag xGa xGe 1-xSe 2 single crystals are very sensitive to Ar + ion-irradiation. In particular, bombardment of the single-crystal surfaces with energy of 3.0 keV during 5 min at an ion current density of 14 μA/cm 2 has induced significant modification in top surface layers leading to complete elimination of Ag atoms in the layers. Furthermore, for all four Ag xGa xGe 1-xSe 2 single crystals, the charge states of Ag, Ga, and Ge atoms do not alter when varying the x value, whilst the negative charge of selenium atoms slightly decreases with decreasing x value. All the crystals show substantial photo induced changes of absorption under influence of 808 nm 0.8 W cw laser.


Gorgut G.P.,Lesya Ukrainka Eastern European National University | Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Kityk I.V.,Czestochowa University of Technology | Sachanyuk V.P.,Lesya Ukrainka Eastern European National University | And 2 more authors.
Journal of Crystal Growth | Year: 2011

The synthesis of the CuInGeS4 compound was performed in a shaft-type furnace by the single-temperature method realized by the gradual heating of the samples (heating rate of 10 K/h) to 1370 K with an intermediate exposure to 820 K for 36 h. The annealing was performed at 670 K for 250 h. The synthesis process was finished after quenching the samples into cold water. The phase diagram of the CuInS2GeS2 system was investigated using XRD, differential thermal and microstructure analyses. Two different processes take place in the system, a peritectic one, with the peritectic point coordinates 75 mol% GeS2, 1108 K, and a eutectic one at 86 mol% GeS2, 1033 K. The crystal structure of CuInGeS4 was studied by the powder method. The compound crystallizes in the tetragonal symmetry, space group I-4 (structural type CdGa2S4), with the lattice parameters a=0.55492(2) nm, c=1.00282(6) nm. Atomic parameters were calculated in the anisotropic approximation, with RI=0.0680 and RP=0.1315. © 2011 Elsevier B.V.


Khyzhun O.Y.,Ukrainian Academy of Sciences | Ocheretova V.A.,Kharkiv Polytechnic Institute | Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Parasyuk O.V.,European University at Kiev
Optical Materials | Year: 2014

We report on studies of the electronic structure of Ag 2CdSnS4 single crystal grown by the horizontal gradient freeze technique. For the crystal under consideration, X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated surfaces have been measured. The present X-ray photoelectron spectroscopy (XPS) results indicate that Ag2CdSnS4 single crystal surface is very rigid with respect to Ar+ ion-irradiation. In particular, Ar+ bombardment of the single crystal surface does not induce any significant changes of values of the binding energies of core-level electrons as well as the energy distribution of electronic states within the valence-band region. The Ar+ bombardment does not change the elemental stoichiometry of the Ag2CdSnS4 surface. For the Ag2CdSnS4 compound, the X-ray emission bands representing the energy distribution of the valence Ag d, Cd d and S p states were recorded and compared on a common energy scale with the XPS valence-band spectrum. Results of such a comparison indicate that the S 3p states contribute predominantly in the upper and central portions of the valence band of the Ag2CdSnS4 single crystal. In addition, our data reveal that the Ag 4d and Cd 4d states contribute mainly in the central portion and at the bottom of the valence band, respectively. © 2014 Elsevier B.V. All rights reserved.


Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies | Parasyuk O.V.,European University at Kiev | Kityk I.V.,European University at Kiev | Kityk I.V.,Czestochowa University of Technology
Materials Chemistry and Physics | Year: 2013

A new approach to describe anion sub-lattice for chalcogenide compounds is proposed. The approach is developed on the base of wurtzite and sphalerite structures and includes consideration of the second coordination sphere of anion atoms. A variety of discussed examples show that the second coordination surrounding may be formed both by single anion atoms and by atom pairs or more complex configurations. Considering some chalcogenide compounds, the efficiency of such approach is demonstrated for the search of some similarities between the compounds and for optimization of corresponding quantum chemical calculations. © 2013 Elsevier B.V. All rights reserved.


Khyzhun O.Y.,Ukrainian Academy of Sciences | Bekenev V.L.,Ukrainian Academy of Sciences | Denysyuk N.M.,Ukrainian Academy of Sciences | Parasyuk O.V.,European University at Kiev | Fedorchuk A.O.,Lviv National University of Veterinary Medicine and Biotechnologies
Journal of Alloys and Compounds | Year: 2014

We report on first-principles calculations of total and partial densities of states of atoms constituting TlPb2Cl5 using the full potential linearized augmented plane wave (FP-LAPW) method. The calculations reveal that the valence band of TlPb2Cl5 is dominated by contributions of the Cl 3p-like states, which contribute mainly at the top of the valence band with also significant contributions throughout the whole valence-band region. In addition, the bottom of the conduction band of TlPb 2Cl5 is composed mainly of contributions of the unoccupied Pb 6p-like states. Our FP-LAPW data indicate that the TlPb2Cl 5 compound is an indirect-gap material with band gap of 3.42 eV. The X-ray photoelectron core-level and valence-band spectra for pristine and Ar + ion-irradiated surfaces of a TlPb2Cl5 polycrystalline sample were measured. The measurements reveal high chemical stability and confirm experimentally the low hygroscopicity of TlPb 2Cl5 surface. © 2013 Elsevier B.V. All rights reserved.


Fedets O.,Lviv National University of Veterinary Medicine and Biotechnologies
Bulgarian Journal of Agricultural Science | Year: 2015

The level of glutathione and activities of glutathione S-transferase, glutathione peroxidase and glutathione reductase in caecum and liver of food-producing animals have been investigated and compared. The activity of glutathione S-transferase is the highest in the liver, but that of glutathione reductase is the highest in mucosa of caecum. Pig and rabbit have significant differences of glutathione peroxidase activity in caecum and liver. The highest content of glutathione and activity of glutathione S-transferase were in sheep liver and rabbit caecum, the lowest were in cattle. The highest glutathione peroxidase activity was in pig liver and cattle caecum. In horse the activities of glutathione peroxidase and glutathione reductase were the lowest. The highest glutathione reductase activity was in liver of cattle and caecum of cattle and pig. © 2015, National Centre for Agrarian Sciences. All Rights Reserved.


Fedets O.M.,Lviv National University of Veterinary Medicine and Biotechnologies
Ukrain'skyi Biokhimichnyi Zhurnal | Year: 2014

Data about classification, nomenclature, structure, substrate specificity and role of many glutathione transferase's isoenzymes in cell functions have been summarised. The enzyme has been discovered more than 50 years ago. This family of proteins is updated continuously. It has very different composition and will have demand for system analysis for many years.

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