Andersson O.,Umeå University |
Chobal O.,Uzhhorod National University |
Rizak I.,National Aerospace University - Kharkiv Aviation Institute |
Rizak V.,Uzhhorod National University |
Sabadosh V.,Uzhhorod National University
Physical Review B - Condensed Matter and Materials Physics | Year: 2011
The thermal conductivity κ of the ferroelectric, paraelectric, and incommensurate phases of polycrystalline Sn2P2S 6 has been measured in the 0.1-0.7GPa range. The thermal conductivity κ of the ferroelectric phase decreases with increasing pressure p. This unusual behavior, which is found in only a few other phases, is attributed to a negative Grüneisen parameter. The temperature T dependence of κ for the ferroelectric phase (κ~T-1) is well described by the Debye model for κ, with three-phonon Umklapp scattering serving as the dominant scattering mechanism near and above the Debye temperature (∼100 K) up to a few tenths of degrees below the ferro- to paraelectric phase transition, where κ(T) gradually changes and becomes temperature independent upon further heating. The thermal conductivity of the paraelectric and incommensurate phases was temperature independent and indistinguishable. Possible causes for the unusually weak T dependence at high temperatures and implications of the p dependence of κ are discussed. © 2011 American Physical Society.
Zhaba V.I.,Uzhhorod National University
Journal of Physical Studies | Year: 2015
For the calculation of single-channel nucleon–nucleon scattering the phase-functions method has been proposed. Using the phase-functions method the following phase shifts of a nucleon–nucleon scattering are calculated numerically: nn (1S0-,3P0-,3P1-,1D2-state), pp (1S0-,3P0-,3P1-,1D2-state) and nð (1S0-,1P1-,3P0-,3P1-,1D2-,3D2-state). The calculations have been performed using realistic nucleon–nucleon potentials Nijmegen groups (NijmI, NijmII and Nijm93). The feasibility of the fourth-order Runge–Kutta method for numerical calculations of phase shifts was explained. When choosing the step of the optimized calculations phase shifts of up to 0.01 were received. The obtained phase shifts are in good agreement with the results obtained in the framework of other methods. They are also in good agreement with the results of the original paper for the same potential. The deviation is not more than 2%. We also compared the results of calculations of the phase shift under the phase-functions method with the phase shift for other potential models (Argonne v18 and CD-Bonn) and for the partial wave analysis. The deviation between these data is up to 5%. Using the obtained phase shifts we have calculated the full cross-section and the partial scattering amplitudes. These results are in good agreement with those obtained by using known phases published in the literature. © 2015, Ivan Franko National University of Lviv. All rights reserved.
Zhaba V.I.,Uzhhorod National University
Problems of Atomic Science and Technology | Year: 2016
Numerical coefficients of analytical forms for deuteron wave function in configuration representation for Reid93 potential are designed. The obtained wave functions do not contain superfluous knots. The designed parameters of a deuteron well agree with the experimental and theoretical data. The polarization performances T20 and Ayy designed on wave functions are proportionate with earlier published. © 2016, National Science Center, Kharkov Institute of Physics and Technology. All rights reserved.
Bokotey O.V.,Uzhhorod National University
Journal of Alloys and Compounds | Year: 2016
This paper focuses on optical activity investigations of Hg3X2Cl2 (X = Se, Te) crystals. To understand better the nature of gyrotropy occurrence, relation to the crystal structure of Hg3X2Cl2 (X = Se, Te) crystals and contribution of interband transitions to optical rotation the detailed theoretical analysis is conducted. The gyration tensor of Hg3Se2Cl2 crystals is calculated. The theoretical results are confirmed by experimental observation of optical activity. Nanomaterials based on Hg3X2Y2 (X = S, Se, Te; Y = F, Cl, Br, I) gyrotropic crystals have tremendous potential in addressing the two major issues faced by our society: the searching for new energy sources and improving healthcare. Obtained data suggest that the phenomenon of optical activity should be taken into account in the studies concerning optical diagnostic methods in medicine. © 2016 Elsevier B.V.
Chupov S.V.,Uzhhorod National University
Cybernetics and Systems Analysis | Year: 2016
New approaches are proposed to the solution of discrete programming problems on the basis of searching for lexicographic vector ordering for which the optimal solution to a problem coincides with the lexicographic extremum of the set of feasible solutions of the problem or is located rather close to it in the lexicographic sense. A generalized scheme of this lexicographic search and possibilities of its modification are described. Considerable advantages of this approach over the standard lexicographic search algorithm in efficiency are illustrated. © 2016 Springer Science+Business Media New York
Bokotey O.V.,Uzhhorod National University
Nanoscale Research Letters | Year: 2016
This paper reviews the optical properties, such as refractive index, optical dielectric constant, and reflection coefficient of the Hg3Te2Cl2 crystals. The applications of the Hg3X2Y2 crystals as electronic, optical, and optoelectronic devices are very much determined by the nature and magnitude of these fundamental material properties. The origin of chemical bonding in the crystals is very important for definition of the physical and chemical properties. The main structural feature of the Hg3X2Y2 crystals is the presence of covalent pyramids [XHg3] and linear X-Hg-X groups. Optical properties are calculated according to the model proposed by Harrison. The refractive index in the spectral region far from the absorption edge is determined within the generalized single-oscillator model. The calculated results are found to be in good agreement with experimental data. © 2016, Bokotey.
Grondin J.,University of Bordeaux 1 |
Lassegues J.-C.,University of Bordeaux 1 |
Cavagnat D.,University of Bordeaux 1 |
Buffeteau T.,University of Bordeaux 1 |
And 2 more authors.
Journal of Raman Spectroscopy | Year: 2011
Imidazolium-based ionic liquids (ILs) involving anions of variable coordinating strength have been investigated using infrared (IR) and Raman spectroscopies, density functional theory (DFT) calculations and selective deuteration of the imidazolium CH groups. Particular emphasis has been placed on the vibrational assignments of the anion and cation internal vibrations, a prerequisite before any interpretation of spectral changes due to ion-ion interactions in these unconventional liquids. The vibrations of highly symmetric and weakly coordinating anions, such as PF6 -, have unperturbed wavenumbers, but unexpected IR or Raman activity for some modes, showing that the anion is subjected to an anisotropic electric field. The stretching as well as the in-plane and out-of-plane bending modes of the imidazolium CH groups are anharmonic. They give broad bands that reflect a large distribution of interactions with the surrounding anions. All the bending modes are mixed with ring vibrations and the stretching modes are complicated by Fermi resonance interactions with overtones and combination of in-plane ring modes. However, the stretching vibration of the quasi-diatomic C(2)i- D bond appears to be a good spectroscopic probe of the increasing cation-anion interactions when the coordinating strength of the anion increases. The broad absorption observed in the far IR with weakly coordinating anions remains practically unchanged when the acidic C(2)i- H imidazolium bond is methylated and even when the imidazolium cation is substituted by tetra-alkyl ammonium or pyrrolidinium cations. It is concluded that this absorption is a general feature of any IL, coming from the relative translational and librational motions of the ions without needing to invoke C(2)i- H anion hydrogen bonds. Vibrational assignments are given between 3200 and 40 cm-1 of ionic liquids involving imidazolium cations and anions of variable coordinating strength, with particular emphasis on the nature of the Ci- H⋯anion interactions. Copyright © 2010 John Wiley & Sons, Ltd.
Bidzilya Y.,Uzhhorod National University
European Journal of Science and Theology | Year: 2015
The author analyses the positive influence of the contemporary vernacular media of Zakarpattia on the rebirth of national identity of the Slovak minority in the region. He also touches upon the reasons of the decline of the Slovak information and communication fields in Zakarpattia in the middle of the XXth century which have led to a significant assimilation of this nation. The informative strategy and the thematic content of the ‘Podkarpatskiy Slovak’ and ‘Slovenske slovo’ newspapers and the ‘Dovera’ journal are analyzed. These carry out the regenerative process of the Slovak information and communication segment in Zakarpattia which has formed only during the contemporary history after declaring the independence of Ukraine. Since then the Slovak ethno-national rebirth has been characterized by intensive development. It has been under the direct influence of the Slovak national cultural and educational institutions of Zakarpattia. The department of Slovak studies has become independent, the Uzhhorod National University and the Slovak media in the region as well. © 2015, Ecozone, OAIMDD. All rights reserved.
Gasuda M.,Uzhhorod National University
Economic Annals-XXI | Year: 2014
The evolution of the environmental management theories has been considered in the paper. Approaches towards environmental management in different economic and environmental theories have been studied as follows. The theories of pre-classical and classical periods: The labor theory of property; elite; exploitation; social division of labor; the state and the economic role of the state; property rights, the government regulation; mercantilism; as well as the theories of neoclassical period: The marginal utility theory, the theory of value; and theories of the modern period: geographical determinism, technological determinism, economic growth, consumption theory, and the theory of sustainable development. The conceptual characteristics being the basis for each of the theories have been pointed out. The position of the theories of environmental management in the system of renewable natural resources usage has been grounded. The author view of the sustainable environmental management concept has been presented in the paper. The main idea of the concept has been determined as ensuring the balance between the growing needs for natural resources and the available amount of such resources. The postulates of the sustainable environmental management concept have been distinguished, namely: cost-effectiveness and efficiency ensuring in the allocation and usage of natural resources; a simple and expanded reproduction of the natural resources forming; safe usage of natural resources and food safety; the environment protection. The principles of sustainable environmental management have been determined, which are: equality in the natural resources usage and consumption; free access to the natural resources; ensuring the effectiveness and productivity of the natural resources utilization; protection of natural resources and the environment from the threats and dangers.
Zhaba V.I.,Uzhhorod National University
Nuclear Physics and Atomic Energy | Year: 2016
To approximate the deuteron wave function in coordinate representation two new analytical forms were proposed. They are represented as the product of the power function rn for the sum of exponential terms Ai • exp(-ai • r3). For rea-listic phenomenological potentials of the Nijmegen groups these forms are constructed as deuteron wave function in the coordinate representation, which do not contain superfluous knots. The calculated parameters of the deuteron compared with experimental and theoretical data are compared. © V. I. Zhaba, 2016.