Sergey A. Ponomarenko, Nikolay M. Surin, Oleg V. Borshchev, Yuriy N. Luponosov, D. Akimov, I. S. Alexandrov, A. Burenkov, Alexey G. Kovalenko, Viktor N. Stekhanov, Elena A. Kleymyuk, O.T. Gritsenko, Georgiy V. Cherkaev, A. S. Kechek’yan, О. А. Серенко, Aziz M. Muzafarov,
Organic luminophores are widely used in various optoelectronic devices, which serve for photonics, nuclear and particle physics, quantum electronics, medical diagnostics and many other fields of science and technology. Improving their spectral-luminescent characteristics for particular technical requirements of the devices is a challenging task. Here we show a new concept to universal solution of this problem by creation of nanostructured organosilicon luminophores (NOLs), which are a particular ...
Tópico(s): Molecular Junctions and Nanostructures
2014 - Nature Portfolio | Scientific Reports
Alexandre V. Ivachtchenko, Olexiy V. Silin, Т. И. Савченко, Sergiy M. Kovalenko, Viktor M. Nikitchenko,
A convenient synthesis of 3-aryl-5H-pyrazolo[4,3-c]quinolines is described.The key reactions include alkylation of 3-aroyl-1H-quinolin-4-ones with alkyl halides in DMF in the presence of sodium hydride, followed by hydrazine-mediated cyclization of the alkylated products in acetic acid.
Tópico(s): Synthesis and Reactivity of Heterocycles
2004 - Elsevier BV | Heterocycles
Volodymyr Chenchevoi, Valeriy Kuznetsov, Vitaliy Kuznetsov, Olga Chencheva, Iurii Zachepa, Oleksii Chornyi, М. A. Kovzel, Viktor Kovalenko, Mykola Babyak, Serhii Levchenko,
The paper presents studies of the system "induction generator-induction motor" with parametric asymmetry on a mathematical model to determine the quality of generated electricity in load operating modes. A mathematical model of the "induction generator-induction motor" system has been developed taking into account losses in steel and parametric asymmetry. The analysis of the transient characteristics of an induction generator when a motor load is connected in symmetrical and asymmetrical modes of ...
Tópico(s): Industrial Engineering and Technologies
2021 - Kharkiv State Academy of Physical Culture | Eastern-European Journal of Enterprise Technologies
Mariya Kovalenko, Oleg Bovgyra, Viktor Dzikovskyi, Rostyslav Bovhyra,
Using density functional theory calculations, we studied structural, electronic and adsorption properties of CO and H2 adsorption on the Pt-doped (ZnO)12 nanoclusters. The more suitable position for the Pt atom is its lateral doping on the nanocluster surface. The lower energy gap for the Pt-doped (ZnO)12 nanoclusters denotes that their conductivity is higher in comparison with the bare nanocluster. The results showed quite a reasonable increase in CO and H2 gas molecules adsorption energies on the ...
Tópico(s): Catalytic Processes in Materials Science
2020 - Springer Nature | SN Applied Sciences
А. І. Кашуба, Г. А. Ільчук, R. Petrus, I. V. Semkiv, O. Bovgyra, Mariya Kovalenko, Viktor Dzikovskyi,
The optical constants and thickness of Al-doped ZnO (ZnO:Al(2.5 wt.%)) thin films prepared by high-frequency magnetron sputtering method are determined. ZnO:Al thin films are crystallized in the hexagonal structure from XRD studies. The optical constants and the bandgap of the films under study have been determined. Optical properties (refractive index [Formula: see text], absorption coefficient [Formula: see text], extinction coefficient [Formula: see text], dielectric functions [Formula: see text] and ...
Tópico(s): Gas Sensing Nanomaterials and Sensors
2021 - World Scientific | Modern Physics Letters B
O. Bovgyra, Mariya Kovalenko, R. V. Bovhyra, Viktor Dzikovskyi,
Iнститут прикладних проблем механiки i математики iм
Tópico(s): Transition Metal Oxide Nanomaterials
2019 - Lviv University | Journal of Physical Studies
Т. И. Савченко, Olexiy V. Silin, Sergiy M. Kovalenko, Vladymir I. Musatov, Viktor M. Nikitchenko, Alexander V. Ivachtchenko,
Abstract The interaction of 3‐phenyl‐1H‐pyrazolo[4.3‐c]quinoline with alkylating agents in the presence of NaH leads mainly to N1‐substituted derivatives. The regioselectivity of the reaction has been studied using AM1 semi‐empirical calculations in the isolated molecule approximation. Keywords: alkylationAM1 method3‐phenyl‐1H‐pyrazolo[4.3‐c]quinolineregioselectivity Acknowledgments The authors thank Vladymir V. Ivanov, Konstantin V. Balakin, and Yan A. Ivanenkov (ChemDiv, Inc.) for discussion and ...
Tópico(s): Molecular spectroscopy and chirality
2007 - Taylor & Francis | Synthetic Communications
Andrey Sidorenkov, Eugene Borokhovski, Viktor A Kovalenko,
This study explores the connections between formal quantitative group characteristics (such as group size, group composition by gender, age, and duration of group membership of individual workers, their average age, and duration of membership) with three levels of conflict (ie, interpersonal, individual-group, and individual-subgroup) of two types (ie, activity-oriented and subject-oriented).Forty-one work groups - small-size enterprises and basic-level teams and units in medium-size companies and large ...
Tópico(s): Social Power and Status Dynamics
2018 - Dove Medical Press | Psychology Research and Behavior Management
А. І. Кашуба, Г. А. Ільчук, R. Petrus, B. Andriyevsky, Oleg Bovgyra, I. V. Semkiv, Mariya Kovalenko, Viktor Dzikovskyi,
Al-doped ZnO (ZnO:Al) thin films are prepared by high-frequency magnetron sputtering method. The phase analysis and crystal structure refinement are performed using X-ray diffraction data. The mean grain size of the films was determined using the Scherrer formula. The strain and the dislocation density are also calculated. The spectral dependence of the optical transmittance of the obtained sample in the visible and near-infrared regions is studied at room temperature. The integral optical transmittance ...
Tópico(s): Chalcogenide Semiconductor Thin Films
2021 - Taylor & Francis | Molecular Crystals and Liquid Crystals
O. Bovgyra, Mariya Kovalenko, Viktor Dzikovskyi, A. Vaskiv, M. Ya. Sheremeta,
ZnO/GaN heterostructures are promising systems for solar cells, light-emitting diodes and photocatalytic applications due to their appropriate band gaps that correspond to the wavelength range of visible light and thus have attracted wide attention over the past ten years.In this study, investigations of structural and electronic properties of bulk ZnO, GaN and ZnO/GaN superlattice have been performed based on first-principles calculations within the density functional theory.For a more accurate ...
Tópico(s): GaN-based semiconductor devices and materials
2020 - Sumy State University | Journal of Nano- and Electronic Physics
Olha Zamaslo, Viktor Kovalenko, Olha Lozynska,
The article studies the approach to assessing the banking digitalization influenced by economy digitalization, dynamically spread electronic payments, e-commerce, and innovative digital service technologies. Digitalized banking services, widespread online platforms and digital customer communication channels require an approach to assessing the banking digitalization identifying the bank’s competitiveness, strengths and weaknesses strategically. The aim is to develop a banking digitalization indicator ...
Tópico(s): Economic Issues in Ukraine
2021 - Izdevnieciba “Baltija Publishing” | Baltic Journal of Economic Studies
Alexander Kaklyugin, Nonna Stupen, Lubov Kastornykh, Viktor Kovalenko,
The results of the studies aimed at increasing the water resistance of the pressed building materials based on gypsum and magnesia binders due to their modification with active dispersed fillers from secondary resources are presented. The gypsum binder modification was carried out by the joint introduction of carbonate-containing sludge from it into the chemical treatment of thermal power plants and monoammonium phosphate, and of magnesia cement - silica fume and finely ground burnt mines. Physical ...
Tópico(s): Innovations in Concrete and Construction Materials
2020 - Trans Tech Publications | Materials science forum
Nataliia Kovalenko, Taras Hutsol, Vitalii Kovalenko, Szymon Głowacki, С.В. Коковіхін, Viktor Dubik, Oleksander Mudragel, Maciej Kuboń, Wioletta Tomaszewska-Górecka,
Abstract Over the last few years, hydrogen energy has shifted from a little-studied field to the main one with which leading western countries associate the prospects of their national economies. The reasons are the unprecedented pace of development of hydrogen technologies. It turned out that they are able to provide significant reductions in greenhouse gas emissions, and thus bring closer the solution to the problem of global climate change. The first and foremost purpose of our investigation ...
Tópico(s): Economic and Business Development Strategies
2021 - | Agricultural Engineering/Inżynieria Rolnicza
B. Turko, U. Mostovoy, Mariya Kovalenko, Yu. Eliyashevskyi, Yuriy Kulyk, O. Bovgyra, Viktor Dzikovskyi, А. Kostruba, R Vlokh, V Savaryn, V. V. Stybel, B. Tsizh, S Majevska,
We study the crystalline structure and absorption spectra for the zinc oxide films with different levels of yttrium doping.The films are deposited on glass substrates, using radio-frequency magnetron sputtering.We estimate the concentration of free charge carriers and show that the 'blue' shift of the fundamental absorption edge in ZnO:Y films with increasing doping level (up to 4.7 wt.%) is explained by Burstein-Moss effect.At higher concentrations of yttrium, behaviour of the fundamental absorption ...
Tópico(s): Copper-based nanomaterials and applications
2021 - | Ukrainian Journal of Physical Optics
Vitalii Serdiuk, Oleh Shevchuk, Natalya Bukartyk, Tetiana Kovalenko, Anatoliy Borysiuk, Viktor Tokarev,
Abstract Magnetite nanoparticles (Fe 3 O 4 NPs) with peroxide‐containing polymer shell have been synthesized using the method of coprecipitation from the mixture solutions of Fe (II) and Fe (III) salts in the presence of peroxide‐containing copolymer (PCC). Polymer shell presence has been proved by elemental and complex thermal analysis. Synthesized Fe 3 O 4 NPs possess superparamagnetic properties. Their specific saturation magnetization decreases gradually from 65 to 54 A·m 2 ·kg −1 with increasing ...
Tópico(s): Magnetic Properties and Synthesis of Ferrites
2021 - Wiley | Journal of Applied Polymer Science
Mariya Kovalenko, Oleg Bovgyra, Andriy Franiv, Viktor Dzikovskyi,
First-principles calculations based on density functional theory are performed to understand the electronic properties of III group elements doped ZnO as functions of the dopant atoms content. The results reveal that the lattice constants of Ga, In, Tl, Y, Sc and La doped ZnO increase linearly with the doping increasing, while for B and Al doped ZnO observed decreases lattice parameters with increases dopant content in ZnO. According to the results, the optical band gap of all ZnO doped systems ...
Tópico(s): Copper-based nanomaterials and applications
2019 - Elsevier BV | Materials Today Proceedings
Viktor Leontyev, Matthew M. Hawkeye, Andriy Kovalenko, Michael J. Brett,
Anisotropic properties of columnar nanoporous thin films were utilized to design and fabricate interference mirrors with lossless omnidirectional reflection in the visible spectral range. Index graded columnar films with distributed Bragg reflector (DBR), sinusoidal, and Gaussian refractive index profiles were studied using finite-difference frequency-domain and finite-difference time-domain methods, with an emphasis on maximizing the omnidirectional reflection bandwidth. Titanium dioxide columnar ...
Tópico(s): Photonic and Optical Devices
2012 - American Institute of Physics | Journal of Applied Physics
Nonna Stupen, Alexander Kaklyugin, Lyubov Kastornykh, Viktor Kovalenko,
The results of studies evaluating the possibility of increasing the water resistance of pressed magnesia composites for the purpose of their use in the construction of agro-industrial objects are presented. As a modifying filler, a secondary resource was used: the burnt rock from the mines of the Rostov region, which has pozzolanic properties. In the studied compositions, a modifying filler was replaced with 10–25% of the magnesian binder. The water resistance of the pressed modified magnesia composites ...
Tópico(s): Aerogels and thermal insulation
2024 - Springer International Publishing | Lecture notes in networks and systems
Валентина Зайцева, Sergiy Tsviliy, Valentyna Demko, Іван Клопов, Viktor Kovalenko,
The article presents an adaptative-institutional approach to determining the investment environment in the international tourism industry. The amount of foreign direct investment flows from international corporations to the tourism industry is analyzed. An integral index of the investment of investment capital (assets) of international corporations in the economic system of the country according to the high and low level of development of the tourism industry is proposed and calculated. The article ...
Tópico(s): Business and Economic Development
2024 - Pedagogical and Technological University of Colombia | APUNTES DEL CENES
Vitalii Serdiuk, Oleh Shevchuk, Tetiana Kovalenko, Natalya Bukartyk, Viktor Tokarev,
Abstract A series of reactive copolymers with peroxide functionality (RCPFs) were synthesized via radical copolymerization of monomer mixtures in an organic solvent comprised of a peroxide monomer 5‐( tert ‐butyl peroxy)‐5‐methylhex‐1‐en‐3‐yne, acrylamide, maleic anhydride, and butyl methacrylate. Peroxide functionality allows the RCPFs to initiate a variety of radical processes, including cross‐linking of organic polymers. Hydrophilic monomer subunits (acrylamide and maleic anhydride) within the RCPF ...
Tópico(s): Polymer Surface Interaction Studies
2022 - Wiley | Journal of Applied Polymer Science
Mariya Kovalenko, O. Bovgyra, Viktor Dzikovskyi, А. І. Кашуба, Г. А. Ільчук, R. Petrus, I. V. Semkiv,
The structural, electronic, and optical properties of zinc oxide thin films with Al-doping have been investigated experimentally and with density functional theory (DFT) calculations. Changes in properties of doped thin films, which are deposited on a glass substrate by a high-frequency magnetron sputtering method, are monitored using X-ray diffraction data and UV measurements. Our theoretical calculations show that the electronic structure of ZnO: Al can be well described by the DFT+U method. The ...
Tópico(s): ZnO doping and properties
2021 - Vasyl Stefanyk Prycarpathian National University | Physics and Chemistry of Solid State
Andriy Kovalenko, Eugene Babeshko, Viktor Tokarev, Kostiantyn Leontiiev,
This chapter describes an element base of new generation for NPP I&C, namely field programmable gate array (FPGA), and peculiarities of the FPGA application for designing safety critical systems. FPGA chips are modern complex electronic components that have been applied in nuclear power plants (NPPs) instrumentation and control systems (I&CSs) during the last 15-17 years. The advantages and some risks caused by application of the FPGA technology are analyzed. Safety assessment techniques of ...
Tópico(s): Nuclear reactor physics and engineering
2020 - IGI Global | Advances in information security, privacy, and ethics book series
Hennadii Khudov, Olesya Symkanych, Anna Kovalenko, Natalia Kabus, Viktor Lysytsya, Rostyslav Khudov,
The features of cytological images during processing by automated microscopy systems are determined.The essence of the known methods of processing of cytological images used in algorithms of automatic selection and transformation of micro-objects on cytological images is briefly stated.The results of cytological image processing by k-means, Prewitt, Sobel, Canny, Hough methods and combinations of these methods are presented.A comparative visual and quantitative assessment of the quality of cytological ...
Tópico(s): Mathematical Biology Tumor Growth
2020 - The World Academy of Research in Science and Engineering | International Journal of Advanced Trends in Computer Science and Engineering
Alexander Kaklyugin, Nonna Stupen, Lyubov Kastornykh, Viktor Kovalenko,
The purpose of this work is a comparative assessment of the resistance to alternating humidification and drying (air resistance) of modified pressed composites based on gypsum binder and magnesia cement. In order to increase the water and air resistance of small-piece gypsum and magnesite products manufactured by pressing, modifying fillers were introduced into the composition of molding mixtures as secondary resources. There are investigated changes in the physical and mechanical properties of pressed ...
Tópico(s): Building materials and conservation
2022 - Springer International Publishing | Lecture notes in networks and systems
Viktor Ievdokymov, Serhii Lehenchuk, Dmytro Zakharov, Уляна Андрусів, Olga Usatenko, Larisa Kovalenko,
The article substantiates the essence of the concept of "social capital" as a resource in terms of formed, permanent, established types of highly effective socio-economic interactions.In addition, the main directions of its manifestation and its structural elements are defined.It is stated that for quantitative measurement of social capital at the enterprise level, it is necessary to establish its precise framework, to determine its structure and key features.As an object of accounting, social capital ...
2019 - Growing Science | Management Science Letters
Joshua D. Krabbe, Viktor Leontyev, Michael T. Taschuk, Andriy Kovalenko, Michael J. Brett,
Nanoimprint lithography was combined with glancing angle deposition (GLAD) of titanium dioxide to fabricate a square spiral columnar film with a bandgap in the visible spectral range. Nanoimprint stamps were fabricated with seed spacing ranging from 80 to 400 nm, and four periods of square spiral film were deposited on top of the 320 nm array of seeds. The ratio of lattice spacing, vertical pitch and spiral arm swing was chosen as a : P : A = 1 : 1.35 : 0.7 and the deposition angle was fixed at 86° to maximize ...
Tópico(s): Nanofabrication and Lithography Techniques
2012 - American Institute of Physics | Journal of Applied Physics
Viktor Leontyev, Nicholas G. Wakefield, K. V. Tabunshchyk, Jeremy C. Sit, Michael J. Brett, Andriy Kovalenko,
Columnar thin films exhibiting linear polarization selectivity have been theoretically investigated and fabricated using the glancing angle deposition (GLAD) technique. The film structure employed an s-shaped columnar morphology that may be either smoothly bent or composed of discrete segments. Finite-difference time-domain and frequency-domain methods have been used to model these thin film structures numerically. Simulation results have yielded optimal geometries in which the films exhibit either ...
Tópico(s): Photonic and Optical Devices
2008 - American Institute of Physics | Journal of Applied Physics
Yuriy Akimov, A. A. Burov, Yu. A. Drozhbin, V. A. Kovalenko, G V Rodichenko, B. M. Stepanov, Viktor Yakovlev,
The results are given of an investigation of the time characteristics of an electron-beam-pumped GaAs sealed-enclosure laser. Spatial scanning of the electron beam across the GaAs crystal made it possible to vary the power, shape, and repetition frequency of 10−10–10−6 sec laser output pulses. The scanning was achieved by a wide-band system of deflecting plates and a grid modulation electrode.
Tópico(s): Solid State Laser Technologies
1972 - IOP Publishing | Soviet Journal of Quantum Electronics
Yuliia Kovalenko, Tetyana Bіlovus, Viktor Khelemskyi, Tetiana Shulha,
Further development and intensification of investment processes in the capital markets are important factors for the reset and intensive economic growth of Ukraine. Any reform measures implemented in Ukraine require substantial investment resources. The basic definition from which the study of the investment process begins is the concept of investment. Despite the significance of scientific achievements in this area, there is a certain level of fragmentation in approaches to the essence of investment ...
Tópico(s): Economic and Business Development Strategies
2021 - | SCIENTIFIC BULLETIN OF POLISSIA
Valerij S. Kovalenko, Viktor Vargalyuk F. Vargalyuk, Nadiia V. Stets,
There was examined the way of life and creative work of the well-known scientist chemist, Doctor of Chemical Sciences, Professor М. А. Rozenberg, the student and the follower of Academician L. V. Pisarzhevsky who was the one of the founders and the first Dean of the Chemical Faculty of the Dnepropetrovsk University.The scientific research of М. А. Rozenberg was mainly continuation of the works of Academician L. V. Pisarzhevsky. It was related to the electronic chemistry, magneto- and electrochemistry. ...
Tópico(s): Mining and Gasification Technologies
2019 - Oles Honchar Dnipro National University | Journal of Chemistry and Technologies