https://periodicals.karazin.ua/eejp/issue/feed East European Journal of Physics 2019-01-29T14:00:45+02:00 Serhii Hirnyk serhii.hirnyk@karazin.ua Open Journal Systems <p>International peer-reviewed journal devoted to experimental and theoretical research on the nuclear physics, cosmic rays and particles, high-energy physics, solid state physics, plasma physics and controlled thermonuclear fusion, physics of charged particle beams, plasma electronics, radiation materials science, physics of thin films, condensed matter physics, functional materials and coatings, technical thermophysics and industrial power,&nbsp;medical physics and physical technologies in an interdisciplinary context.</p> <p><strong>East European Journal of Physics</strong> <strong>has been selected for coverage in Clarivate Analytics products and services.&nbsp;Beginning with 2017 it will be indexed and abstracted in: "Emerging Sources Citation Index"(ESCI).</strong></p> https://periodicals.karazin.ua/eejp/article/view/12160 Cosmography of the Dynamical Cosmological «Constant» 2019-01-29T14:00:45+02:00 Oryna Ivashtenko arinaivashtenko@gmail.com <p>The paper considers a cosmographical approach to analyze cosmological models. Cosmography is a method to describe the kinematics of the cosmological expansion based only on the cosmological principle. We consider a method of treating free parameters of a cosmological model in terms of the directly observable cosmographic values related to the time-derivatives of the Hubble parameter (deceleration, jerk, snap). The method is applied to analyze two cosmological models involving the time-dependence of the cosmological constant in the form&nbsp;Λ(<em>t</em>)→Λ(<em>H</em>)&nbsp;when this approach is especially efficient. Both models interpret the dark energy in the form of the cosmological constant &nbsp;as energy of physical vacuum, which is currently the most supported treatment. The first one means &nbsp;being proportional to the Hubble parameter, and the second one involves a constant and a quadratic term. As a result, the free parameters of both models are expressed in terms of the currently observed values of the Hubble parameter, deceleration, and jerk. The obtained expressions for model parameters are exact, as the method does not involve any additional assumptions. Furthermore, it leads to deal with algebraic equations instead of differential ones. After this procedure, solutions of the evolution equations are obtained in the form of the time-dependence of the Hubble parameter. The obtained model parameters are substituted to the solutions, which are analyzed for a typical range of cosmographic scalars taken from recent observations. Finally, the proposed approach is used to eliminate free parameters from both models and to obtain constraints for the directly observable cosmographic values that can be tested to correspond to present observations data. For the considered cases, such constraints are received respectively for the jerk and the snap parameters with respect to the deceleration. The constraint for the linear model is compared with current observational value ranges for the deceleration and the jerk parameters.</p> 2019-01-05T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12200 Growth of Europium-Doped Magnesium Selenide Films by Electric Field-Assisted Spray Pyrolysis: Optical and Structural Analysis 2019-01-29T14:00:45+02:00 Diemiruaye M. Jeroh jeruaye@gmail.com Azubike J. Ekpunobi eejp@karazin.ua Donald N. Okoli eejp@karazin.ua <p>Europium-doped MgSe films were deposited via electric field-assisted spray pyrolysis. The dopant concentration of the bulk solution of europium trioxide was 5wt.&nbsp;%. However, for doping the films at different substrate temperatures, volume percentage (vol.&nbsp;%) was employed at each instance of variation. Variation of spray temperature was around 573K and 673K (±0.3). Deposition occurred at optimized conditions. Spectra of absorption indicate poor absorption characteristics demonstrated by Europium-doped MgSe films in the ultra-violet region and very low absorption characteristics in the visible section. Absorption peaks were evident around 230nm, 240nm, 350nm and 365nm which confirmed defect states are inherent inside the crystal structure of the films. The films displayed high transparency and low reflection in the visible section at varying substrate temperatures. The high transparency revealed by the MgSe:Eu films in the visible section of the electromagnetic spectrum makes the material applicable as a coating layer in the manufacturing of transparent products. Band gap energies within the range of 2.49eV to 2.95eV corresponding to varying substrate temperatures (573K, 598K, 623K, 648K and 673K) and film thicknesses (2900nm, 2750nm, 2500nm, 2100nm and 200nm) were determined for the MgSe:Eu films. However, a clear observation shows that the band gaps of MgSe:Eu films are mainly dependent on thickness such that the obtained band gaps decreased with increasing thickness (band gap increases with thickness reduction). Structural analysis (XRD) studied at 10% and 40% Eu concentrations reveals a hexagonal (or wurzite) structure for the films with a distortion in crystallinity at higher dopant concentration (40 vol. %) and a resultant blue shift in the lattice constant from the bulk value. Multiple planes of reflection from XRD pattern of the deposited MgSe:Eu films indicate clearly that the films are polycrystalline. Surface morphology (SEM) confirms the highly strained nature and the presence of defect states within the crystal lattice of the Europium-doped MgSe films. Composition of MgSe:Eu films obtained by energy dispersive analysis x-ray (EDAX) confirms the growth of MgSe:Eu films.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12201 Novel Trimethine Cyanine Dye as Potential Amyloid Marker 2019-01-29T14:00:44+02:00 Uliana Tarabara uliana.tarabara@gmail.com Olga Ryzhova olya_zhitniakivska@yahoo.com Kateryna Vus kateryna.vus@karazin.ua Atanas Kurutos eejp@karazin.ua Valeriya Trusova valeriya.m.trusova@gmail.com Galyna Gorbenko galyagor@yahoo.com N. Gadjev eejp@karazin.ua Todor Deligeorgiev eejp@karazin.ua <p>The applicability of the novel cyanine dye AK 3-1 to the detection and characterization of pathogenic protein aggregates, amyloid fibrils, was tested using the absorption spectroscopy technique. In an organic solvent dimethyl sulfoxide (DMSO), absorption spectra of AK3-1 exhibits vibrational structure with the relative intensity of 0-0 sub-band being higher than that for the 0-1 sub-band. In an aqueous phase the dye absorption band undergoes hypsochromic shift relative to DMSO due to H-aggregation of the dye. The interaction of AK3-1 with the native and fibrillar insulin was followed by the decrease of monomer band and the enhancement of H-dimer band. To evaluate the relative contributions of the monomeric and aggregated forms, the absorption spectra of the protein-bound dye were deconvoluted using the asymmetric log-normal (LN) function. The analysis of the set of fitting parameters provides evidence for the protein-induced AK3-1 self-association into the head-to-head dimers, with the magnitude of this effect being much more pronounced for fibrillar protein form. The molecular docking studies showed that the AK3-1 monomer tends to associate with the specific arrangement of side chains in the β-sheet formed by L17 leucine residues (of the insulin B-chain), located on the dry steric zipper interface of the fibril, while the dye dimers form stable complexes with the amyloid groove formed by the residues Q15 and E17 of the A-chain, and located on the wet interface of the fibril. The latter binding site is more easily accessible and is additionally stabilized by the electrostatic interactions between the positively charged dye and the E17 residue. This binding mode seems to be prevailing over that for the AK3-1 monomers. Based on the results obtained, AK3-1 may be recommended as a prospective amyloid marker complementary to the classical amyloid reporters Thioflavin T and Congo Red.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12203 Molecular Dynamics Study of Amyloidogenic Mutants of Human Lysozyme 2019-01-29T14:00:43+02:00 Uliana Tarabara uliana.tarabara@gmail.com Valeriya Trusova valtrusova@yahoo.com Kateryna Vus kateryna.vus@karazin.ua Olga Ryzhova olya_zhitniakivska@yahoo.com Galyna Gorbenko galyagor@yahoo.com <p>The mutants of human lysozyme are capable of fibril formation implicated in the etiology of familial systemic or renal amyloidosis. A series of 100 ns thermal unfolding molecular dynamics (MD) simulations with WT human lysozyme and its seven amyloidogenic variants (I56T, D67H, F57I, W64R, Y54N, F57I/T70N and T70N/W112R) have been performed at 500 K. The molecular dynamics simulations were performed with GROMACS software (version 5.1) using the CHARMM36m force field. The MD results have been analysed in terms of the parameters characterizing both the global and local protein structure, such as the backbone root mean-square deviation, gyration radius, solvent accessible surface area, the root mean-square fluctuations and the secondary structure content. Depending on the observed effects, the examined variants of human lysozyme have been roughly divided into three groups comprising of mutants with faster (Y54N and F57I/T70N), similar (D67H and I56T) or slower (W64, F57I and T70N/W112R) unfolding rate compared to the wild-type counterpart. The analysis of the protein fluctuational behavior revealed that in most mutants the β-domain displays stronger fluctuations (except the W64R and F57I) and higher flexibility of the C- and D-helices relative to the native lysozyme with the exception of W64R and Y54N which show marked decrease (W64R) or increase (Y54N) in mobility of almost all residues. The analysis of secondary structure evolution provided evidence for higher stability of α-domain compared to β-domain. The results obtained reinforce the idea that mutation-induced global structural destabilization is not the only factor contributing to protein misfolding, the modifications in conformation and dynamics of selected protein regions may also play significant role in amyloid fibril formation.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12204 Physical-Mechanical Properties of γ-Irradiated SiC Ceramics for Radioactive Wastes Immobilization 2019-01-29T14:00:42+02:00 Kostiantyn Lobach lobach0709@gmail.com Sergey Sayenko eejp@karazin.ua Volodymyr Shkuropatenko eejp@karazin.ua Victor Voyevodin EEJP@KARAZIN.UA Anna Zykova eejp@karazin.ua Elena Bereznyak eejp@karazin.ua Y. Hodyreva eejp@karazin.ua S. Bykanov eejp@karazin.ua A. Bykov eejp@karazin.ua Leonid Tovazhnyanskyy eejp@karazin.ua <p>The interest in silicon carbide (SiC-based) ceramics and composites as matrix material for nuclear waste immobilization is grown up. Long-term chemical durability and radiation resistance of SiC are important factors for radionuclides immobilization. Advantages of SiC-based ceramics as structural materials in nuclear applications are the high-temperature properties, high density and reduced neutron activation. The use of radiation resistant materials is a strong requirement for safe and environmentally beneficial energy system. The SiC ceramics stability under irradiation for temperatures up to 1273 K is also very important for nuclear power applications. The SiC matrices doped by additives of Cr, Si were fabricated using High Speed Hot Pressing Method. Additives content was in the range from 0.5 to 3&nbsp;wt %. Microstructural characteristics of silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and infra-red spectroscopy (IR) methods. The results of microcracking under indentation conditions were revealed the lack of cracks in the SiC ceramics with Cr additives before and after irradiation process. In addition, it was demonstrated that samples of SiC with alloying additives Cr and Si possess high mechanical parameters under γ-irradiation process. The strength of ceramics increases with the uniform and fine-grained structure formation. The modification of phase composition and mechanical properties of the SiC ceramics with Cr and Si additives under γ-irradiation were analyzed for further development of radiation resistant and matrix materials for radioactive wastes immobilization.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12205 Supramolecular Design of Carbons for Energy Storage with the Reactanse-Sensor Functional Hybridity 2019-01-11T17:15:00+02:00 Ivan Grygorchak ivan_gryg@ukr.net Anatolii Borysiuk eejp@karazin.ua Roman Shvets eejp@karazin.ua Dariya Matulka eep@karazin.ua Orest Hryhorchak eejp@karazin.ua <p>The purpose of this work is to expand the class of electrical energy storage devices with non-conjugate functional hybridity. Cyclodextrins of <em>β-</em> and <em>γ-</em>modifications has used as a starting material for research. These materials containing intramolecular voids, which are able to accommodate guest components by molecular recognition on the "lock-key" principle. Methods of precision porometry and impedance spectroscopy has used to study the obtained carbon structures, electrochemical and magnetic measurements has performed to study the obtained carbon structures. Data of the precision porometry has indicated a bimodal porous structure of the synthesized chars. The total specific surface area of active surface of the <em>β-</em>cyclodextrin carbonizate was about 72&nbsp;m<sup>2</sup>/g. After KOH-modification, the specific capacity for <em>β-</em>cyclodextrin char was 158&nbsp;F/g, and in the negative potential range – 203&nbsp;F/g. The last value for <em>γ-</em>cyclodextrin carbon was 162&nbsp;F/g. The ability of <em>β-</em>cyclodextrin to molecular recognition of ferrocene (FC) has used and this cavitat has subjected to activation carbonation according to the same modes as <em>β-</em>cyclodextrin. The specific capacity of the obtained char of the <em>β-</em>CD complex after the KOH-modification was 110&nbsp;F/g, the specific capacity of the cavitate carbon synthesized on <em>γ-</em>CD has dropped twice. The study of complexes host-guest inclusions <em>β-</em>cyclodextrin with molecular iodine has indicated a slight increase of capacity. However, their interface with 30&nbsp;% aqueous electrolyte solution has shown high photosensitivity. The specific capacitance of the cavitate carbon without KOH-modification has increased four times when it was illuminated with integral and monochromatic light from LEDs of the same intensity. Magnetic studies of the synthesized carbonates have shown that they all demonstrate ferromagnetic properties. Measurement under normal conditions and in a constant magnetic field of cells of symmetric configuration on carbon-based electrodes synthesized with <em>γ-</em>CD and <em>γ-</em>CD has showed that their capacitance practically does not change, but their reactance parameters change significantly. Supercapacitors based on these carbonates can serve as sensors of a weak magnetic field at room temperature. Magnetovarionistors is a new class of devices, which are forming on such kind of supercapacitors.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12206 Diffusion Temperature Dependence in Tilted Periodic Potentials Ranging from Underdamped Systems to Overdamped Systems 2019-01-11T17:39:46+02:00 Ivan G. Marchenko march@kipt.kharkov.ua Igor I. Marchenko eejp@karazin.ua Viktor Tkachenko tkachenko@kipt.kharkov.ua <p>Recently, both the experimental data and the data of theoretical research appeared stating that the diffusion coefficient shows nonmonotonic behavior with temperature. The motion of Brownian particles in the space periodic structures is an example of the systems with abnormal temperature dependence of the diffusion.&nbsp; The aim of the work was to study the change in the temperature dependence of the diffusion coefficient with a change in friction, both in underdamp and overdamped systems. This scientific paper studies the diffusion of particles in tilted spatial-periodic potentials in a wide temperature range. It is shown that in both underdempted and overdamped systems, the diffusion coefficient reaches a maximum value for a certain value of an external force, the value of which depends on the value of the friction coefficient. However, in systems with low and high friction, the temperature dependence of the diffusion coefficient differs. It was established that the systems with a low friction level γ’ show temperature abnormal diffusion (TAD) at which the diffusion coefficient D is increased with a decrease in temperature. At the same time, the diffusion is enhanced at high γ values with the rise in temperature. This scientific paper studies the transition procedure from the exponential dependence of TAD to the ordinary power temperature dependence with an increase in γ’.&nbsp; It was shown that the energy hump that separates “running” solutions and “localized” solutions is decreased with an increase in the friction coefficient and it vanishes at γ&nbsp;-&gt;&nbsp;0 . Simultaneously with a decrease in ε, the temperature interval of the TAD also narrows. It was established that the temperature-limited TAD domain appears in the region of intermediate values of the friction coefficient. In a specified force range the diffusion coefficient is first increased with a decrease in temperature and then it begins to decrease again. The diagrams of existence of such domains have been constructed. The results obtained opens up prospects for the creation of new technologies for managing diffusion processes. This is of great importance for the production of nanomaterials with a given structure, the creation of surface nanostructures, etc.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12207 Helium Porosity Development During Annealing of Helium-Implanted 18Cr10NiTi Steel 2019-01-11T18:24:44+02:00 V. V. Ruzhytskyi eejp@karazin.ua Sergiy A. Karpov karpofff@kipt.kharkov.ua А. S. Kalchenko eejp@karazin.ua I. Е. Кopanets eejp@karazin.ua B. S. Sungurov eejp@karazin.ua G. D. Tolstolutskaya eejp@karazin.ua <p>The kinetics of helium porosity development during annealing of 18Cr10NiTi stainless steel irradiated with 20 keV helium ions at room temperature for simultaneous creation of displacement damage at a level of 0.5–5 dpa and a helium concentration of 1–12 at.%, have been investigated by electron microscopy and thermal desorption spectrometry. The temperature ranges of helium release from steel and their dependence on the irradiation dose are determined. The evolution of 18Cr10NiTi steel microstructure was investigated during post-implantation annealing in the temperature range from T<sub>room</sub> to 1420 K. At a dose of 1·10<sup>20</sup> m<sup>-2</sup>, helium bubbles were detected only after annealing to a temperature of 890 K, while at a dose of 1·10<sup>21</sup> m<sup>-2</sup>, bubbles were observed immediately after radiation at T<sub>room</sub>. During annealing, the average diameters of the bubbles vary from ~1 nm at T<sub>room</sub> to 10–20 nm at T<sub>ann</sub> 1420 K. The mechanisms of bubbles growth either by migration and coalescence, or by Ostwald ripening – dissolution and re-trapping are considered. Since each of these mechanisms corresponds to a certain trend of bubbles size and density dependence on the annealing temperature, the temperature dependences of average diameters and densities of helium bubbles for a dose of 1·10<sup>21</sup> m<sup>-2</sup> have been constructed and analyzed. Experimental data are characterized by three temperature ranges: 1 – from 300 to 760 K, 2 – from 760 to 1030&nbsp;K, and 3 – from 1030 to 1350 K with clearly differing trends. In the low-temperature region the diameter and density of the bubbles virtually does not change. Their size increases and the density decreases at annealing in the temperature range 760-1030&nbsp;K. This tendency intensifies in the temperature range of 1030-1420 K. An estimation of activation energy of the processes controlling the mechanism of bubble growth in the temperature range of 1000-1420 K has been done. An obtained value of ~3.7 eV correlates well with the theoretically calculated value of the activation energy of the dissociation process (E<sub>He</sub><sup>diss</sup>) of the Ostwald ripening mechanism.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12208 Production of 11C and 18F Isotopes. Getting the “Glucose, 11C “ Radiopharmaceutical 2019-01-11T18:48:07+02:00 Anatoliy N. Dovbnya eejp@karazin.ua Roman N. Dronov eejp@karazin.ua Volodymyr A. Kushnir eejp@karazin.ua Viktor V. Mytrochenko eejp@karazin.ua Sergey A. Perezhogin eejp@karazin.ua Leonid I. Selivanov eejp@karazin.ua V. A. Shevchenko eejp@karazin.ua Boris I. Shramenko bshram@kipt.kharkov.ua <p>The results of the photonuclear production of <sup>11</sup>C and <sup>18</sup>F isotopes in various target-matrices are summarized. The studies were performed using linear electron accelerators of the R&amp;DE "Accelerator" NSC KIPT NAS of Ukraine in the energy range 10&nbsp;-40&nbsp;MeV to determine the possibilities of obtaining the maximum achievable activity levels of <sup>11</sup>C isotopes, and <sup>18</sup>F with a view to planning further developments on the creation of radiopharmaceutical for these nuclear isotopes. In the framework of the above approach, we measured the activity levels of the <sup>18</sup>F which is transferred to the surrounding aquatic environment during irradiation of targets-matrices of fluoroplastic (C<sub>2</sub>F<sub>4</sub>) with bremsstrahlung flux. The release of the <sup>18</sup>F isotope into the aquatic environment under the most favorable conditions (in terms of energy and average beam current) was 3.6% of the target-matrices activity - 40&nbsp;MBq/g, which is a very low figure. Despite the encouraging value of the specific activity of <sup>18</sup>F isotope in lithium fluoride (LiF) -77&nbsp;MBq/g target–matrices and hydrofluoric acid (HF) - close to 100&nbsp;MBq/g, the process of extracting <sup>18</sup>F from C<sub>2</sub>F<sub>4</sub>, LiF and HF as basis of the radiopharmaceutical is not sufficiently effective and brings into question the feasibility of such a methodology for producing <sup>18</sup>F isotope for further use. More efficient was the production of the <sup>11</sup>C isotope in the irradiated target-matrix of the standard therapeutic form "glucose monohydrate" (glucose). It was shown that, as a result of irradiation of glucose with a gamma-quanta beam, it is possible to “label” glucose with the <sup>11</sup>C isotope, which is formed as a result of the photonuclear reaction <sup>12</sup>C(γ, n)<sup>11</sup>C at the <sup>12</sup>C nucleus, which is part of the glucose molecule C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>&nbsp;×H<sub>2</sub>O. Irradiated sample of glucose dissolved in a given volume of solvent (distilled water) will be ready for use radiopharmaceutical "Glucose,&nbsp;<sup>11</sup>C". It has been shown that the “photonuclear method” provides for obtaining the “Glucose,&nbsp;<sup>11</sup>C” radiopharmaceutical complex with total activity necessary for performing PET diagnostics. The radiopharmaceutical "Glucose,&nbsp;<sup>11</sup>C" by the time of its use has 100% radionuclide purity. “Glucose,&nbsp;<sup>11</sup>C” obtained in this way was produced for the first time. The choice of the optimal design of a water-cooled target station, providing a moderate (in terms of heat loads) mode of irradiation of a capsule filled with glucose tablets, is discussed. Using the program “SolidWorks FlowSimulation 2011”, the quantitative characteristics of the flow rates of water flowing around the glucose capsule and the converter are calculated.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12209 Investigation of the Liquidus Line on the Fe-B State Diagram 2019-01-11T19:01:44+02:00 Natalia Yu. Filonenko natph2016@gmail.com <p>In this paper we determine the crystallization temperature of a melt of the Fe-B system depending on the boron content and. The thermodynamic properties of the boron-bearing phases are studied. The investigation was performed for alloys with the boron content of 2.0-4.2.0% (wt.), the rest is iron. The smelting of Fe-B system alloy was carried out in a furnace in alundum saggers in the argon atmosphere. The cooling rate of as-cast alloys was 10&nbsp;K/s. To ascertain the structural condition of alloys we used the microstructure analysis, the differential thermal and the X-ray structural analyses. In the paper, based on experimental data for the Fe-B alloys, we determined the crystallization temperatures of alloys under consideration, depending on the content of boron in the alloy. In addition, we revealed that the γ-Fe+Fe<sub>2</sub>B eutectic transformation occurs at the temperature of 1441 K and at the boron content of 3.8% (wt.). To determine the thermodynamic functions of the phases we used the quasi-chemical method. With accounting for the contribution of the first degree approximation of the high-temperature expansion for the thermodynamic potential we derived expressions for the free energy of the melt of the binary Fe-B alloy, the boron-doped austenite and the Fe<sub>2</sub>B boride. The expressions obtained for the free energy potential and the chemical potential of the melt of the binary Fe-B alloy, the austenite and the Fe<sub>2</sub>B boride enable to obtain the Fe-В phase diagram liquidus boundaries. The calculations performed in this paper made it possible to obtain the numerical values of the crystallization temperature of the alloy, depending on the boron content, and to determine the temperature of the γ-Fe+Fe<sub>2</sub>B eutectic transformation and the boron content, at which this transformation takes place in the alloy. Such an approach allows describing most completely from the thermodynamic point of view the crystallization process and the eutectic transformation. The results of the calculations obtained in this paper are in good agreement with the experimental data.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12210 Two band structure of poleskiy amber photoluminescence 2019-01-11T19:29:20+02:00 Ruslan Skiba eejp@karazin.ua Illia Mysiura eejp@karazin.ua Oganes Kalantaryan eejp@karazin.ua Vitaliy Zhurenko v.zhurenko@gmail.com Sergiy Kononenko eejp@karazin.ua <p>The paper presents the results of an experimental study of Poleskiy amber luminescence excited by narrow band UV radiation (7 nm) at the wavelength range of 310–410&nbsp;nm with step of 10 nm. The purpose of the study was to determine the relation between an excitation of two luminescence centers, which we found earlier as a result of the mathematical treatment of the spectra obtained during a cycle of experiments on the photo- and X-ray luminescence of amber from the Poleskiy deposit. It was shown that for various samples the spectra of light excited by UV irradiation had a wide band of luminescence with some differences both in shapes and maximum positions. Increasing the exciting UV radiation wavelength, the monotonic displacement of the spectrum maximum position (from 2.62 to 2.5&nbsp;eV) and the decrease of the full width at half maximum (from 0.92 to 0.62&nbsp;eV) were observed. To analyze the spectra, we applied the mathematical treatment procedure that we successfully used earlier, namely fitting of experimental curves with Gaussian functions. It was demonstrated that the shape of our spectra could be with high accuracy deconvoluted by two peaks well described by Gaussian functions. The observed differences in shapes of the spectra can be explained by changes in the amplitudes of the two peaks with centers at 2.5 and 2.95 eV. The photoluminescence experiments with excitation by a narrow band UV radiation showed that light generation at wavelengths corresponding to these centers varied significantly by the change of primary UV radiation wavelength. The most intense excitation of the 2.5 eV band (496 nm) corresponds to the UV radiation wavelength of 384 nm (3.23 eV), and for the 2.95 eV band (420 nm) – 287.5 nm (4.32) eV. This led to the conclusion about an independent nature of the excitation of these centers. Spectrum changes can be explained by the different excitation efficiency of both centers.</p> 2019-01-11T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12212 Influence of Ionic Bombardment on the Processes of Nitriding During Complex Modification of Steel Surface 2019-01-13T16:47:59+02:00 V. A. Belous eejp@karazin.ua Yuriy Zadneprovskiy yaz@kipt.kharkov.ua Mykola Lomino eejp@karazin.ua Ihor Domnich eejp@karazin.ua T. I. Bevs eejp@karazin.ua <p>Ionic bombardment of the surfaces modified with the use of vacuum-arc technologies is a basic physical process for such modifications. Experiments were produced on plant of type "Bulat". In-process on nitriding of surfaces massive steel details (item of <em>25Х1МФ</em> and <em>40Х</em>) was investigated features of using of bombardment particles with different energy content. As bombarding particles ions of titan and molybdenum was use. This stage of ionic bombardment is related to cleaning of surface and heating of it to the necessary temperature. On the step of nitriding bombardment was carried out by the ions of nitrogen, generated in a two-stage discharge. For diagnostics of changes on the surface of standards and in the distance from it deep into metal, used X-ray fluorescence mass-analysis and produced measuring of hardness by means of device of Nanoindentor G200. The comparative measuring of relative concentrations of elements is executed in composition a surface became after bombardments different ions (<em>Ti</em> or <em>Мо</em>), and also the profiles of bedding of the implanted nitrogen and modified hardness in a metal are got. Features are educed in the results of nitriding of steel surface by the use of different sorts of ions.&nbsp; The photos of the transversal microsections got by means of optical metallography microscope of ММО 1600 showed differences in structural characteristics of the nearsurface layers by using the bombardments ions of titan and molybdenum. These differences are related to the high temperature in layers during bombardment the ions of molybdenum. The purpose of this work is conduction comparative experiments on the treatment of steel surfaces with accelerated ions of various metals with the subsequent analysis of the influence of such effects on the nitriding processes on these surfaces.</p> 2019-01-13T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12213 Nonlinear Dynamical Analysis on the Formation of Cadmium Oxide by Laser Deposition 2019-01-13T18:12:26+02:00 M. A. Grado-Caffaro ma.grado-caffaro@sapienzastudies.com M. Grado-Caffaro eejp@karazin.ua <p>It is well-known that II-VI compounds occupy a very relevant place in the whole context of semiconductors. In particular, II-VI semiconductor and isolating or quasi-isolating oxides play an important role. Among these materials, we can mention zinc oxide and cadmium oxide. These oxides, which are transparent (at least in the visible range), are suitable for a number of optoelectronics applications. In this respect, let us consider solar cells; indeed, the above oxides serve as antireflection coatings for these cells. Cadmium oxide, doped or undoped, despite it is hazardous to manipulate, is certainly very interesting for the aforementioned optoelectronics applications. On the other hand, many aspects of this oxide may be regarded from the experimental and theoretical standpoints. In relation to the experimental side, several techniques are currently used to produce cadmium oxide. Among these experimental methods, one can mention metal evaporation, sputtering over a glass substrate, and laser deposition. Perhaps, laser deposition is more advanced and promising than the other techniques. In addition, the fact that laser is involved in this type of deposition gives rise to that the main aspects of the physics and chemistry of cadmium oxide are, say, enhanced. Really, the physics and chemistry of cadmium oxide constitute a significant issue. In order to examine accurately the principal physical mechanisms underlying the formation of cadmium oxide by laser deposition, an in-depth theoretical nonlinear study upon the above formation is presented in this article. As a matter of fact, taking into account that the molecules (,,) in the chemical reaction which gives CdO are diatomic, the Morse potential is assumed to act upon the inter-nuclear axis of the molecules which, consequently, behave as quantum anharmonic (nonlinear) oscillators. In fact, associated with the corresponding chemical reaction, inelastic collision between a cadmium molecule and an oxygen one is considered to give rise to two molecules of cadmium oxide. We analyze carefully this collision from the quantum-mechanical point of view (we recall that the molecules in question behave as quantum anharmonic oscillators). From this molecular collision, energy loss is produced due to the laser action. The energy loss is calculated and, from this result, we deduce a mathematical condition to be obeyed for the size of anharmonicity by using a suitable parameter.</p> 2019-01-13T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12214 Computational Modeling of SAR and Heat Distribution in Lossy Medium at GSM Frequencies 2019-01-13T19:45:40+02:00 Khitam Y. Elwasife kelwasife@iugaza.edu.ps <p>In recent years, institution has increased imposition of electromagnetic radiation in many applications. This radiation react with the human tissue and may lead to harmful and injurious effects on human health. However a finite difference thermal model of lossy medium as (spinal cord of human body) has been developed to calculate temperature rises generated in the spinal cord by radiation from cellular telephones with different frequencies. The natural metabolic heat production and the power density absorbed from the electromagnetic field have been evaluated. The specific absorption rate (SAR) was derived from a finite difference time domain model (FDTD) of the spinal cord. This is a&nbsp;numerical analysis is&nbsp;technique used for modeling&nbsp;computational electrodynamics. Aside from the specific absorption rate, through the exposure of radiation is an extremely important parameter while assessing the effects on spinal cord tissue. The heat distribution was calculated using the bioheat equation coupled with Maxwell's equation. A one dimensional finite difference time domain method has been used, some simulations for electromagnetic wave through the spinal cord tissue is made using software program. Also for the simulation, the dielectric properties supposed medium are directly taken by numerical program. Results show that electromagnetic fields penetrate the life tissues and attenuate fast to reach zero at large time steps. Specific absorption rate show maximum at the first boundary of tissue and becomes less value by using high frequency. The absorbent power and specific absorption rate show maximum at the interface of tissue, and the technique developed may be used to estimate temperature rises associated with specific absorption rate (SARs) for different types of radiation. Also, the results note that low-frequency waves have significantly affected the biological tissue.</p> 2019-01-13T00:00:00+02:00 ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/12215 Institute of Theoretical Physics Akhiezer. Origins. The first attempt in the USSR 2019-01-13T18:34:20+02:00 Alla Tan'shyna eejp@karazin.ua <p>On the 100th anniversary of the National Academy of Sciences of Ukraine &amp; the 90th anniversary of the founding of the NSC "KIPT"</p> <p>... In Kharkov, a powerful school of modern theoretical physics was created ...</p> 2019-01-13T00:00:00+02:00 ##submission.copyrightStatement##