Time filter

Source Type

Odessa, Ukraine

The National Academy of science of Ukraine is the highest research body in Ukraine, as a self-governing state-funded organization. It is the main research institution along with the five other academies specialized in various scientific disciplines. NAS Ukraine consists of numerous departments, sections, research institutes, scientific centers and various other supporting scientific organizations. The Academy reports on the annual basis to the Cabinet of Ministers of Ukraine.The presidium of the academy is located at the following address vulytsia Volodymyrska, 57, across the street from the Building of Pedagogical Museum where used to preside the Central Council during the independence period of 1917-18. Wikipedia.

Nedukha O.M.,Ukrainian Academy of Sciences
Cytology and Genetics | Year: 2015

Callose plays an important role in fragmoplast formation at cytokinesis and differentiation of pores in the phloem, as well as within the courses of microsporogenesis, functioning of stomata closure cells, and protection of plant cells from biotic and abiotic stresses. Special attention is given to consideration of callose functions and its synthesis. Callose synthase is activated by the glucosides, polyamines, calcium ions, magnesium ions, manganese ions, and abscisic acid. The callose synthase gene polymorphism (AtCalS1-AtCalS12) is related to cell growth, tissue differentiation, and cell response to stress as well. © 2015, Allerton Press, Inc. Source

Potoyan D.A.,University of Maryland University College | Savelyev A.,Ukrainian Academy of Sciences | Papoian G.A.,University of Maryland University College
Wiley Interdisciplinary Reviews: Computational Molecular Science | Year: 2013

The growing interest in the DNA-based mesoscale systems of biological and nonbiological nature has encouraged the computational molecular science community to develop coarse-grained (CG) representationsof the DNA that will be simple enough to permit exhaustive simulations in a reasonable amount of time, yet complex enough to capture the essential physics at play. In the recent years, there have been some major developments in the DNA coarse-graining area and several fairly sophisticated models are now available that faithfully reproduce key mechanical and chemical properties of the double- and single-stranded DNA. However, there are still many challenges, which limit the applicability of the present models, and much has to be done yet to develop more reliable schemes which would have a predictive power beyond the target domain of the intrinsic parametrization. A development of robust, controllable, and transferrable CG DNA force fields will provide an invaluable tool for gaining physical insights into the molecular nature of complex DNA-based nanoscale entities such as the chromatin, virus capsids, and DNA nanocomposites. In the present contribution, we provide an overview of the recent developments in the DNA coarse-graining field. Our aim is to review the existing CG models of the double-stranded DNA, where a small selection of models, which we believe provide avenues for promising future development, are discussed in some detail. © 2012 John Wiley & Sons, Ltd. Source

Braun O.M.,Ukrainian Academy of Sciences | Peyrard M.,Laboratoire Of Physique Of Lecole Normale Superieure Of Lyon
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

At the mesoscale friction occurs through the breaking and formation of local contacts. This is often described by the earthquakelike model which requires numerical studies. We show that this phenomenon can also be described by a master equation, which can be solved analytically in some cases and provides an efficient numerical solution for more general cases. We examine the effect of temperature and aging of the contacts and discuss the statistical properties of the contacts for different situations of friction and their implications, particularly regarding the existence of stick-slip. © 2010 The American Physical Society. Source

In central and eastern Europe, the development of the architecture of mammoth bone dwellings is associated with the abundance of mammoth bone beds which were exploited by human groups in the Upper Paleolithic. The present paper focuses on the mammoth bone circular dwellings of Gravettian and Epigravettian cultures: Pavlovian (Early Gravettian of Moravia), Gagarino and Pouchkari (Gravettian of Eastern Europe), Kostienki 11/1a (Zamiatnine culture), and Mezinian. The difference between architectures is discussed, focusing on the procurement of the mammoth bones, the ground plan, and the 3D reconstruction of the dwellings. A spectacular "parietal art" is visible in the dwellings of the Mezinian, in the grouping in the outer wall of jaws and long bones showing a geometric pattern of lines, chevrons and zigzags, which are also figured in the painted bones of the dwellings and in the mobile art of the statuettes, tools and various artefacts, confirming they are the manifestation of a socio-symbolic system of the Mezinian culture. © 2014 Elsevier Ltd and INQUA. Source

Cheremnykh O.K.,Ukrainian Academy of Sciences
Plasma Physics and Controlled Fusion | Year: 2010

It is shown that in arbitrary plasma systems with magnetic surfaces there are transversally small-scale (ballooning) perturbations with the vector of displacement lying in a magnetic surface. The equations of small oscillations for these perturbations are derived. It is shown that the spectrum of eigenmodes of these equations coincides with a continuous spectrum of resonant MHD modes (Cheng and Chance 1986 Phys. Fluids 29 3695-01). The case of a dipole magnetic field is analysed. © 2010 IOP Publishing Ltd. Source

Redko R.,Ukrainian Academy of Sciences
Journal of Applied Physics | Year: 2012

Long-term transformations of the optical reflectance and the surface microrelief of GaAs epitaxial structure under weak magnetic field treatment (B=60 mT, f=10 Hz, τ=1.2 ms, t=5 min) were obtained. Optical measurements were performed in the waverange of 8001100 nm at 300 K. The epitaxial layer thickness was determined by scanning electron microscopy (SEM). Non-monotonous changes of reflectance accompanied by changes of SEM images were observed. Experimental results have been interpreted in terms of the diffusion of point defects, resulted from the destruction of metastable complexes (probably [V As+impurity]), from the internal boundaries to the surfaces of investigated structures. A method for the detection of non-equilibrium complexes in multilayer objects was proposed. © 2012 American Institute of Physics. Source

Stasyshyn O.,Ukrainian Academy of Sciences | Antunes S.,UNIFESP Sao Paulo Brazil | Mamonov V.,Russian Academy of Medical Sciences
Haemophilia | Year: 2014

The Pro-FEIBA study reported health-related quality of life (HRQoL) improved following 6-month of Factor Eight Inhibitor Bypassing Activity (FEIBA) prophylaxis. This study investigates whether 12-month of FEIBA prophylaxis improved HRQoL in haemophilia patients with inhibitors. Thirty-six subjects in a 1-year prospective, randomized, open-label, parallel-design study were randomized to prophylaxis (85 ± 15 U kg-1 every other day) or on-demand treatment. HRQoL was assessed at screening, 6 and 12-month termination using the EQ-5D, Haem-A-QoL, Haemo-QoL and a general pain visual analog scale (VAS). To evaluate changes, paired t-tests and criteria for minimally important differences were applied. Repeated measures regression tested the association between annualized bleeding rate (ABR) and physical HRQoL. At 6 and 12 months, prophylaxis subjects reported clinically meaningful improvement in EQ-5D index (mean improvement, 0.10 and 0.08, respectively) and both clinically meaningful and statistically significant improvements in EQ-VAS scores (16.9 and 15.7, respectively; P < 0.05) vs. baseline. General pain was significantly reduced during prophylaxis at each follow-up (mean improvement, 20.3 and 23.2, respectively; both P <0.05). At 12 months, prophylaxis subjects achieved significant improvements in Haem-A-QoL Total Score and in four domains: Physical Health, Feeling, View, and Work and School (all P < 0.05). No statistically significant changes, except for Haem-A-QoL Physical Health at 6 months, were observed with on-demand treatment. ABR was decreased by 72.5% with prophylaxis vs. on-demand treatment (P = 0.0003) and reduced ABR was associated with better physical HRQoL (P < 0.05). FEIBA prophylaxis significantly reduced ABR and improved HRQoL in inhibitor patients. Subjects with lower ABR reported better physical HRQoL. © 2014 John Wiley & Sons Ltd. Source

Lyubashenko V.,Ukrainian Academy of Sciences
Applied Categorical Structures | Year: 2016

We describe the category of homotopy coalgebras, concentrating on properties of relatively cofree homotopy coalgebras, morphisms and coderivations from an ordinary coalgebra to a relatively cofree homotopy coalgebra, morphisms and coderivations between coalgebras of latter type. Cobar- and bar-constructions between counit-complemented curved coalgebras, unit-complemented curved algebras and curved homotopy coalgebras are described. Using twisting cochains an adjunction between cobar- and bar-constructions is derived under additional assumptions. © 2016 Springer Science+Business Media Dordrecht Source

The construction of a set of two-level integration ω-schemes for the equations of the flow theory of plasticity, describing anisothermic loading processes along the deformation paths of small curvature, is described. In this case, a stress-strain state is dependent on thermomechanical loading history, and inelastic deformation should be followed over the whole examined time interval in step solving the boundary problem. Basic concepts of the phenomenological model are built upon the Prandtl- Reuss equations of plasticity and the Huber-Mises yield condition. The loading process is divided into several time steps. The equations of plasticity are integrated in a loading step. The general procedure of transformations to construct a set of two-level integration ω-schemes for the equations of plasticity is proposed. The conditions for the agreement between the considered equations of plasticity and the principle of work irreversibility with plastic strain increments and Drucker's hardening postulate are formulated. As an example, illustrating the properties of these equations, the deformation problem is solved for a thin-walled round pipe subject to axial tension and torsional moment. Results of solving the model problem, obtained with different two-level integration schemes, are presented. Practical recommendations as to the choice of the parameter ω are given. © 2012 Springer Science+Business Media New York. Source

Results of design of metal oxide (Co, Cr, Ce, In, Fe) catalysts including those doped with Rh (Pd) supported on ZrO 2, Al 2O 3, H-ZSM-5 and their binary compositions for reduction of NO, N 2O by C 1, C 3-C 4-hydrocarbons and CO in gas flows containing oxygen, H 2O and SO 2, are presented. SCR-activity of Co-In-oxide catalysts towards NO depends on the nature of support and the sequence of active components' application, and the catalysts (In 2O 3-CoO)/ZrO 2 exhibit high resistance against moisture and sulfur dioxide. In combined reduction of nitrogen(I), (II) oxides with C 3-C 4 alkanes (SCR-conditions) at 400-450°C, higher conversions for NO (60-78%) were observed on the Co-containing catalysts, whereas for N 2O (90-95%) - on the Fe-containing ones supported on the H-ZSM-5. Composites over structured support Pd/Co 3O 4-CeO 2/cordierite showed high activity in NO + N 2O + CO reactions (95-99% conversion of N 2O and NO at 200-300°C) in the presence of H 2O. © 2012 Elsevier B.V. Source

Malovichko P.,Ukrainian Academy of Sciences | Voitenko Y.,Belgian Institute for Space Aeronomy | De Keyser J.,Belgian Institute for Space Aeronomy
Astrophysical Journal | Year: 2014

Compensated-current systems created by energetic ion beams are widespread in space and astrophysical plasmas. The well-known examples are foreshock regions in the solar wind and around supernova remnants. We found a new oblique Alfvénic instability driven by compensated currents flowing along the background magnetic field. Because of the vastly different electron and ion gyroradii, oblique Alfvénic perturbations react differently on the currents carried by the hot ion beams and the return electron currents. Ultimately, this difference leads to a non-resonant aperiodic instability at perpendicular wavelengths close to the beam ion gyroradius. The instability growth rate increases with increasing beam current and temperature. In the solar wind upstream of Earth's bow shock, the instability growth time can drop below 10 proton cyclotron periods. Our results suggest that this instability can contribute to the turbulence and ion acceleration in space and astrophysical foreshocks. © 2014. The American Astronomical Society. All rights reserved.. Source

Bastun V.N.,Ukrainian Academy of Sciences
Strength of Materials | Year: 2012

The dependence of the Bauschinger effect measure on the plastic strain value in tension in the direction of the axis of symmetry and in the orthogonal direction is investigated within the framework of the model of a transversely isotropic material with translational strain-hardening. A numerical example of determining the Bauschinger effect measure in martensitic 28Kh3SNMVFA steel is presented. The anisotropy of the yield strength in the region of small plastic strains is shown to be accompanied by a significant anisotropy of the Bauschinger effect measure. © 2012 Springer Science+Business Media, Inc. Source

Dovzhik M.V.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2012

Non-classical problems of fracture mechanics for a half-space with a crack located at a short distance from the free surface are solved. An axisymmetric problem for a penny-shaped crack is considered. A numerical analysis is performed for materials with harmonic and Bartenev-Khazanovich potentials in the case of unequal roots of the characteristic equation. This case is similar in mathematical structure of the equations to the case of equal roots in the classical theory of isotropic elasticity. The numerical results are tabulated and analyzed © 2012 Springer Science+Business Media, Inc. Source

Avramenko O.A.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2012

The stress-strain state of nonthin conical shells with thickness varying in two coordinate directions is examined using the approach developed to solve boundary-value problems. Displacement and stress fields in such shells are determined and analyzed © 2012 Springer Science+Business Media, Inc. Source

Guz A.N.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2012

The main results on the three-dimensional theory of stability of compressible and incompressible hyperelastic simply connected bodies under uniform compression are analyzed. The problems are classified according to the type of loading (dead or follower loads, acting on the whole or a part of the surface) and the type of boundary conditions (the same conditions on the whole surface or different conditions on different parts of the surface). Approaches based on the three-dimensional linearized theory of stability (theory of finite subcritical deformations, first and second theories of small subcritical deformations, incremental-deformation theory, theory of small average rotations) and an approximate approach (linear equations; the loading parameter is approximately included in the boundary conditions) to solving these problems are discussed. Related problems (rock pressure manifestations, folding in the Earth's crust, wave-like formations on the surface of structural members, stability of laminated composite materials) are briefly commented. Regarding isotropic compressible and incompressible hyperelastic materials, the three-dimensional theory of elastic stability, theory of finite subcritical deformations, and first and second theories of small subcritical deformations are considered. The sufficient conditions for the applicability of the static (Euler's) method, the sufficient conditions for the stability of equilibrium state, and the general solutions to anti-plane, plane, and spatial problems for homogeneous subcritical states are formulated. The exact solutions, obtained with the above-mentioned general approaches, for compressible and incompressible isotropic bodies (strip, rectangular and circular plates, circular cylinder, sphere, and body of arbitrary geometry) under dead or follower loading are presented. These solutions were obtained for isotropic hyperelastic materials with an arbitrary elastic potential under uniform (hydrostatic, biaxial, or triaxial) pressure. The reviewed results were originally reported in the author's monograph (A. N. Guz, Stability of Elastic Bodies under Uniform Compression [in Russian], Naukova Dumka, Kyiv (1979)) and articles listed in the References © 2012 Springer Science+Business Media, Inc. Source

Kirichok I.F.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2012

The problem of the forced axisymmetric vibrations and self-heating of a clamped flexible circular plate with piezoelectric actuators is solved. The aspects of mechanical and electric excitation of vibrations and damping of mechanical vibrations with actuators are discussed. The effect of geometrical nonlinearity on the frequency dependence of deflections and self-heating temperature under electromechanical harmonic loading at the principal resonance of bending vibrations of the plate is studied © 2012 Springer Science+Business Media New York. Source

The author formulates the rules one should follow when choosing strength criteria for a composite. A comparative analysis of Ashkenazi and Tsai-Wu strength criteria is performed for a specific orthotropic material, and the criteria are shown to agree with each other. An update of the Tsai-Wu criterion is put forward for composites that have uniform tension and compression strength. © 2012 Springer Science+Business Media New York. Source

Snopok B.A.,Ukrainian Academy of Sciences
Theoretical and Experimental Chemistry | Year: 2012

On the basis of an analysis of current views about plasmonics a conceptual examination of propagating surface plasmon resonance (SPR) in relation to the basic mechanisms and operating forces was undertaken with the aim of defining the characteristics of SPR transducers for analytical applications. A simple model of a sensor system that makes it possible to relate the analytical requirements to the intrinsic physical or mechanical characteristics of SPR is examined. A brief review of modern developments is presented. © 2012 Springer Science+Business Media New York. Source

Panchenko B.E.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2012

A new approach to the synthesis of the domain-key normal form (DK/NF) for an arbitrary domain is proposed. The Cartesian dependency, which is a special case of multivalued dependencies, is investigated. A lemma on the non-abnormality of a special relational and a theorem on the non-abnormality of the actual part of a relational framework are proved. A new criterion for determining the belonging of a database schema to DK/NF is given. The proposed approach can be used in designing information warehouse schemas. © 2012 Springer Science+Business Media, Inc. Source

Pilyugin L.S.,Ukrainian Academy of Sciences | Thuan T.X.,University of Virginia
Astrophysical Journal Letters | Year: 2011

The oxygen and nitrogen abundance evolutions with redshift of emission-line galaxies in the Sloan Digital Sky Survey are considered for four intervals of galaxy stellar masses, ranging from 1011.3 M⊙ to 1010.2 M⊙. We have measured their line fluxes and derived the O and N abundances using recent calibrations. The evolution of O and N abundances with redshift clearly shows the galaxy downsizing effect, where enrichment (and hence star formation) ceases in high-mass galaxies at earlier times and shifts to lower-mass galaxies at later epochs. The origin of the scatter in the N/H-O/H diagram has been examined. The most massive galaxies, where O and N enrichment and star formation have already stopped, occupy a narrow band in the N/H-O/H diagram, defining an upper envelope. The less massive galaxies which are still undergoing star formation at the current epoch are shifted downward, toward lower N/H values in the N/H-O/H diagram. This downward shift is caused by the time delay between N and O enrichment. This time delay together with the different star formation histories in galaxies is responsible for the large scatter in the N/H-O/H diagram. © 2011. The American Astronomical Society. All rights reserved. Printed in the U.S.A. Source

Omel'Chenko O.E.,Weierstrass Institute for Applied Analysis And Stochastics | Omel'Chenko O.E.,Ukrainian Academy of Sciences | Wolfrum M.,Weierstrass Institute for Applied Analysis And Stochastics
Physica D: Nonlinear Phenomena | Year: 2013

We analyze the Sakaguchi-Kuramoto model of coupled phase oscillators in a continuum limit given by a frequency dependent version of the Ott-Antonsen system. Based on a self-consistency equation, we provide a detailed analysis of partially synchronized states, their bifurcation from the completely incoherent state and their stability properties. We use this method to analyze the bifurcations for various types of frequency distributions and explain the appearance of non-universal synchronization transitions. © 2013 Elsevier B.V. All rights reserved. Source

Bovsunovskii P.,Ukrainian Academy of Sciences
Strength of Materials | Year: 2011

High-cycle fatigue curves in symmetrical torsion were plotted, the endurance limit-mean cycle stress relation was derived, and damping of torsional vibrations was evaluated by the results of R2MA rotor steel specimen testing. © 2011 Springer Science+Business Media, Inc. Source

Nikitina N.V.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2011

The principle of antisymmetry that gives rise to closed orbits of limit cycles and quasiperiodic trajectories of stable oscillations is formulated. The conditions of attraction of synchronized limit cycle as a whole are established. A bifurcational phase portrait of a synchronized limit cycle is considered. It is shown that the subharmonic capture of the limit cycle with period multiplication involves loss of symmetry and preservation of attraction. © 2011 Springer Science+Business Media, Inc. Source

Lakiza V.D.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2011

We discuss test data on the nonlinear dynamic deformation of the elastic wall of a cylindrical glassfiber-reinforced shell (empty or filled) subject to radial two-frequency excitation. It is revealed that such processes can be accompanied (especially at the lowest resonant frequencies) by the cyclic variation in the amplitude and deformation mode between traveling and standing circumferential wave © 2011 Springer Science+Business Media, Inc. Source

Arkhypova K.A.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2011

Waveguide single-frequency method has been used to measure the complex permittivity of human red blood cells in the high-frequency domain (γ-dispersion). The relationship between the dielectric and physiological characteristics of human blood is described. It was experimentally detected that changes in complex permittivity of blood caused by the action of endogenous epinephrine in vitro can serve as criterion for assessing the functional state of the human body in health and disease. It opens an opportunity of using this method in the biomedical field for diagnostic purposes. © 2011 by Begell House, Inc. Source

In order to simulate the operating fretting-fatigue conditions in cylindrical structural components, we have performed experimental studies on fretting fatigue of cylindrical specimens with clamped concave cylindrical pads of bridge type. Using the known solutions for stress intensity factors in the semi-elliptical cracks growing in cylindrical specimens, we predict the kinetics of propagation of fretting-fatigue cracks according to the two-parameter model described in Part 1. A close correlation of calculated and experimental fretting-fatigue life values is observed for AMg6N alloy for varied experimental fretting conditions (contact load, slip amplitude and friction coefficient). For alloy VT9 we have provided approbation of the technique, which takes into account distribution of the residual stresses in the material subsurface during calculation of stress-strain state and life under fretting-fatigue conditions. © 2011 Springer Science+Business Media, Inc. Source

Chekhov V.N.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2011

The equilibrium state of layered bodies under biaxial loading is analyzed for stability. It is assumed that the in-plane strains in the layers are zero. The three-dimensional linearized theory of stability and the piecewise-homogeneous material model are used. Two models of layered bodies are considered. Specific problems for layered bodies of different structure are solved. The critical load and wave number that cause instability of layered bodies are found © 2011 Springer Science+Business Media, Inc. Source

Bovsunovskii P.,Ukrainian Academy of Sciences
Strength of Materials | Year: 2011

We present a technique and results of fatigue damage evaluation of steam turbine shafting material under conditions of torque vibrations occurring at turbogenerator abnormal modes of operation (short circuit, random paralleling start, etc.). Combinations of loading parameters, which provide the shafting limiting conditions, are identified. © 2011 Springer Science+Business Media, Inc. Source

Temnykh A.,Ukrainian Academy of Sciences | Nishida S.,University of Tokyo
Aquatic Invasions | Year: 2012

Specimens of small (< 1 mm) cyclopoid copepods of the genus Oithona were collected from Sevastopol Bay and an offshore area of the Black Sea. On the basis of a combination of characteristics such as those in the maxillule and the genital double-somite, the specimens were identified as O. davisae Ferrari and Orsi, 1984. The identity of "O. brevicornis" that was reported in the Black Sea and the possible origin of O. davisae in the Black Sea are discussed. © 2012 The Author(s). Source

Dolinskaya I.V.,Ukrainian Academy of Sciences
Vestnik Zoologii | Year: 2014

The eggs of 10 species Noctuidae from 6 subfamilies (Acronictinae, Metoponiinae, Cuculliinae, Heliothinae, Condicinae and Bryophilinae) occurring in Ukraine are examined, described, and illustrated with SEM. Th e diagnostic characters of examined species are carried out © by I. V. Dolinskaya. Source

Gol'din P.,Ukrainian Academy of Sciences
Biological Journal of the Linnean Society | Year: 2014

Skulls of many living and extinct beaked whales (Ziphiidae) contain various bizarre bone and tooth structures. Many of them show sexual dimorphism in their skull anatomy: males have bizarre skull structures, whereas females do not. Opinions differ as to what the function of these structures might be. Some believe that these are weapons; others, that they are sound transmitters. This article argues that these structures are the means of visual display. Many of the bizarre bone structures of beaked whales are not exposed like 'visuals' of terrestrial tetrapods, but are located deep in soft tissues. Nevertheless, toothed whales recognize objects (including three-dimensional bodies), using echolocation. So, along with visual means, they can 'see' and 'show' their internal bone structures with echoic imaging and use them as informational sources in social interactions and in individual or species recognition. © 2014 The Linnean Society of London. Source

Degtyarev V.A.,Ukrainian Academy of Sciences
Strength of Materials | Year: 2013

Results of experimental investigations displayed the effect of vibrotreatment, high-frequency hammering, dressing of weld reinforcement, argon-are processing, and explosive treatment on the fatigue resistance of welds of low-carbon and low-alloy steels under different thermomechanical loading conditions. Vibrotreatment and high-frequency hammering of the welded elements of metallic structures were improved. © 2013 Springer Science+Business Media New York. Source

Bondarenko V.,Ukrainian Academy of Sciences
Physica Status Solidi (B) Basic Research | Year: 2015

Abstractauthoren A generalized cubic equation is presented to describe the intrinsic optical bistability (IOB) process in a two-level system within the rotating wave approximation when repopulation of the two levels is governed not only by the incident radiation with changing intensity but also by an additional external factor (X-factor). Numerical simulations are performed for two- and three-quantum-well (QW) systems without and within a microcavity. The obtained results demonstrate that a relatively small change of the X-factor-caused repopulation of the subbands (as in all QWs simultaneously as in only one selected QW) can produce a dramatic effect on the reflectance dependence upon the incident radiation intensity, in particular on the IOB pictures. It is shown that the IOB process (dubbed as the IOBX) can be driven by the cyclic change of the X-factor-caused repopulation of the subbands at a carefully chosen fixed value of the incident radiation intensity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Kucherenko Y.V.,University of Tubingen | Kucherenko Y.V.,Ukrainian Academy of Sciences | Lang F.,University of Tubingen
Cellular Physiology and Biochemistry | Year: 2012

Background: Furosemide, a loop diuretic inhibiting the renal tubular Na+,K+,2Cl- cotransporter, has been shown to decrease cytosolic Ca2+ concentration ([Ca2+]i) in platelets and erythrocytes. [Ca2+]i in erythrocytes is a function of Ca2+ permeable cation channels. Activation of those channels e.g. by energy depletion or oxidative stress leads to increase of [Ca2+]i, which in turn triggers eryptosis, a suicidal erythrocyte death characterized by cell membrane scrambling. The present study was performed to explore whether furosemide influences the cation channels and thus influences eryptosis. Methods: Cation channel activity was determined by whole-cell patch clamp, [Ca2+]i utilizing Fluo3 fluorescence and annexin V binding to estimate cell membrane scrambling with phosphatidylserine exposure. Results: A 45 min exposure to furosemide (10 and 100 μM) slightly, but significantly decreased cation channel activity and [Ca2+]i in human erythrocytes drawn from healthy individuals. ATP-depletion (> 3 hours, +37°C, 6 mM ionosine and 6 mM iodoacetic acid) enhanced the non-selective cation channel activity, increased [Ca2+]i and triggered cell membrane scrambling, effects significantly blunted by furosemide (10-100 μM). Oxidative stress by exposure to tert-butylhydroperoxide (0.1-1. mM) similarly enhanced the non-selective cation channels activity, increased [Ca2+]i and triggered cell membrane scrambling, effects again significantly blunted by furosemide (10-100 μM). Conclusions:: The present study shows for the first time that the loop diuretic furosemide applied at micromolar concentrations (10-100 μM) inhibits non-selective cation channel activity in and eryptosis of human erythrocytes. Copyright © 2012 S. Karger AG, Basel. Source

Khotenko E.A.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2012

The equations of two-dimensional quadratic nonlinear elastic deformation described by the Murnaghan model are derived and used as the basis for the analysis of a nonlinear Rayleigh wave. In the case of geometrical nonlinearity alone, a preliminary theoretical analysis of the nonlinear equations is carried out, and the first and second approximations are found and commented on. Some numerical results on the approximate representation of Rayleigh wave are presented. The dependence of displacements on the distance traveled by the wave is plotted for different material properties and different initial amplitude and frequency of the wave © 2012 Springer Science+Business Media New York. Source

Bliokh K.Y.,RIKEN | Bliokh K.Y.,Ukrainian Academy of Sciences | Schattschneider P.,Vienna University of Technology | Verbeeck J.,University of Antwerp | And 2 more authors.
Physical Review X | Year: 2012

We examine the propagation of the recently discovered electron vortex beams in a longitudinal magnetic field. We consider both the Aharonov-Bohm configuration with a single flux line and the Landau case of a uniform magnetic field. While stationary Aharonov-Bohm modes represent Bessel beams with flux- and vortex-dependent probability distributions, stationary Landau states manifest themselves as nondiffracting Laguerre-Gaussian beams. Furthermore, the Landau-state beams possess field- and vortex-dependent phases: (i) the Zeeman phase from coupling the quantized angular momentum to the magnetic field and (ii) the Gouy phase, known from optical Laguerre-Gaussian beams. Remarkably, together these phases determine the structure of Landau energy levels. This unified Zeeman-Landau-Gouy phase manifests itself in a nontrivial evolution of images formed by various superpositions of modes. We demonstrate that, depending on the chosen superposition, the image can rotate in a magnetic field with either (i) Larmor, (ii) cyclotron (double-Larmor), or (iii) zero frequency. At the same time, its centroid always follows the classical cyclotron trajectory, in agreement with the Ehrenfest theorem. Interestingly, the nonrotating superpositions reproduce stable multivortex configurations that appear in rotating superfluids. Our results open an avenue for the direct electron-microscopy observation of fundamental properties of free quantum-electron states in magnetic fields. Source

Vel'Magina N.A.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2013

The effect of characteristic parameters of a system describing a wheeled assembly on the oscillatory-instability domain is analyzed. The influence of the accuracy of approximation of the lateral force and the heeling moment on the behavior of self-exciting oscillations is examined. A bifurcation set that divides the plane of parameters into domains with different number of limit cycles is constructed © 2013 Springer Science+Business Media New York. Source

Kirichok I.F.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2013

The coupled problem of the forced axially symmetric vibrations and self-heating of clamped and hinged flexible circular plates with viscoelastic piezoelectric layers as sensors and actuators is solved. The mechanical and electric excitation of vibrations and the damping of mechanical vibrations by applying the appropriate potential difference to the electrodes of the actuators are studied. The effect of geometrical nonlinearity on the frequency-dependence of the deflection, self-heating temperature, and sensor voltage of a plate under harmonic electromechanical loading at principal bending resonance is analyzed © 2013 Springer Science+Business Media New York. Source

Zalizovski A.V.,Ukrainian Academy of Sciences
International Journal of Remote Sensing | Year: 2011

Records of the weather conditions, total ozone content (TOC) and ionospheric parameters measured at the Antarctic Base 'Akademik Vernadsky' (Argentine Islands Archipelago) during 1995-2004 are analysed in this paper. The ionospheric region above the ozone hole is found to be characterized by an increased level of disturbance during atmospheric fronts, and the ozone hole geometry is shown to be dependent on cyclonic activity. The results are discussed with reference to a model of internal atmospheric wave propagation through a non-isothermal atmosphere. © 2011 Taylor & Francis. Source

Tuz V.R.,Ukrainian Academy of Sciences
Journal of Magnetism and Magnetic Materials | Year: 2016

In the context of polaritons in a ferrite-semiconductor structure which is influenced by an external static magnetic field, the gyrotropic-nihility can be identified from the dispersion equation related to bulk polaritons as a particular extreme state, at which the longitudinal component of the corresponding constitutive tensor and bulk constant simultaneously acquire zero. Near the frequency of the gyrotropic-nihility state, the conditions of branches merging of bulk polaritons, as well as an anomalous dispersion of bulk and surface polaritons are found and discussed. © 2016 Elsevier B.V. Source

Mishchuk N.A.,Ukrainian Academy of Sciences
Advances in Colloid and Interface Science | Year: 2010

The review addresses the peculiarities of concentration polarization caused by an electric current passing through conducting and around nonconducting charged materials. The conditions of emergence of an induced space charge of large density and thickness behind an electrical double layer, leading to strong non-linearity of electroosmosis and electrophoresis, are analyzed. Basic findings about concentration polarization, its theoretical modeling and experimental investigations, as well as its influence on electrokinetic phenomena and mass transfer through ion-exchange materials are discussed from the point of view of the fundamental knowledge about polarization processes and from the perspective of their practical application. The analysis focuses on the main properties of concentration polarization, electroosmotic flow of liquid around single fixed particles and through the system of particles, and electrophoresis of particles suspended in aqueous medium and current through flat, spherical and cylindrical interfaces and membranes with heterogeneous conductivity. The paper also presents the general ideas of concentration polarization and non-linear electrokinetic phenomena in case of nonconducting particles and their dependence on particle surface electroconductivity. Existing theoretical models describing polarization of nonconducting particles at high and low Peclet numbers are analyzed, with appropriate experimental data being provided to validate the theory. A joint analysis of polarization of conducting and nonconducting particles completes the review. © 2010 Elsevier B.V. Source

Sugakov V.I.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2016

The paper studies the spatial variation of the magnetization in a nonconducting magnetic sample with an excess number of magnons in comparison to the equilibrium. The phenomenon is considered using the Landau-Lifshits equation with additional terms describing the longitudinal relaxation of the magnetization, the magnon diffusion, and the magnon creation by external pumping. The free energy of the system is presented in the mean-field approximation. It is shown that, if the pumping exceeds some critical value, regions of a new phase arise where the magnetic moments are oriented opposite to the magnetization of the magnetic sample. The phenomenon is similar to the appearance of droplets of condensed phase in a supersaturated vapor. The appearance of a new phase either in the form of a single domain or a periodical lattice is demonstrated. The studied process is a competitor to the process of the Bose-Einstein condensation of magnons. © 2016 American Physical Society. Source

Herasymchuk O.M.,Ukrainian Academy of Sciences
Strength of Materials | Year: 2011

A generalized model is developed for calculating the fatigue limit of the material based on the data on its microstructure. The experimental results of fatigue and cyclic fracture toughness tests and the data on the analysis of the microstructure of two-phase (α+β) titanium VT3-1 alloy with a different microstructure (globular, bimodal and fine lamellar microstructure) have shown that the dependence of the fatigue limit on the structural parameter, which is responsible for the material fatigue strength, has a nonlinear S-like nature. The formula for calculating the fatigue limit is justified by the data on the microstructural parameters and by the results of static tensile tests of the material, with a fair agreement obtained between the calculated and experimental results. The model has been validated for materials with another type of the crystal lattice [steel containing 0.16% C with a body-centered cubic lattice (bcc) and brass 70/30 with a face-centered cubic lattice (fcc)] and has shown a satisfactory agreement between the experimental and calculation results. © 2011 Springer Science+Business Media, Inc. Source

Plakhtienko N.P.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2011

The efficiency of an acceleration-feedback controlled frictional electromagnetic damper is proved. An oscillator with a controlled damper is modeled by three ordinary differential equations of the first order with discontinuous right-hand side. An oscillator with acceleration-dependent energy dissipation is described by a simpler model: one equation of the second order with discontinuous coefficients. The exact solution of this equation is found. An approximate law of damping is established. It is shown that the damping parameter is in the base of the exponential function. Double nonstationaryphase-frequency resonance is examined © 2011 Springer Science+Business Media, Inc. Source

Babenko L.P.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

The author discusses modern methods of requirements engineering oriented on human communication and proposes the way for their transformation into semantic annotation of these requirements, suitable for manipulation in the Semantic Web environment. © 2016 Springer Science+Business Media New York Source

A new subtribe Febraina subtr.n. is established with Febra Clark designated as the type genus. Cladistic analysis based on morphological characters is carried out to reveal the composition of a new subtribe and to test its monophyly. Subtribe includes the following genera: Chilocoristes Weise; Halticorcus Lea; Setsaltica Samuelson; Maaltica Samuelson; Axillofebra Samuelson; Profebra Samuelson. Bionomical features of the genera of the subtribe are summarised. The syndrome of hemisphery is recorded for the genera of the subtribe, and morphological transformation resulting in hemisphery is described and discussed. Correspondence between direction of morphological transformation, phylogenetic arrangement of genera, and distributional pattern is recorded and discussed. © 2013 The Royal Entomological Society. Source

Gorban I.I.,Ukrainian Academy of Sciences
Radioelectronics and Communications Systems | Year: 2012

Analytical expressions that link statistical instability parameters with process's spectrum are obtained. It is shown that statistical stability is determined solely by the character of spectral power density dependence on frequency. It is revealed that statistically stable noises are those with rising intensity when frequency is increased, white noise, and equilibrium flicker noise described by the dependence 1/ f β where the spectrum shape parameter is 0< β≤1 as well as fractal Gaussian noise. Statistically instable noises are nonequilibrium flicker noises with spectral power density 1/ f β when 1. It is determined that not only random nonstationary and β≥deterministic processes are statistically instable as it was considered earlier, but stationary processes as well. © Allerton Press, Inc., 2012. Source

Nikitin A.Yu.,University of Zaragoza | Nikitin A.Yu.,Ukrainian Academy of Sciences | Guinea F.,CSIC - Institute of Materials Science | Garcia-Vidal F.J.,Autonomous University of Madrid | Martin-Moreno L.,University of Zaragoza
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The extraordinary properties of graphene make it a very promising material for optoelectronics. However, basic attributes of the electromagnetic field in graphene are still unexplored. Here we report on the in-plane fields radiated by a nanoemitter lying on a graphene sheet in terahertz regime, which present a rich dependence on frequency, distance to the source, and orientation of the dipole moment. The field pattern is mainly composed of a core region, dominated by surface plasmons, where the electric field can be several orders of magnitude larger than in vacuum, and an outer region where the field is virtually the same as what it would be in vacuum. © 2011 American Physical Society. Source

Abdulkadyrov V.A.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2012

Excitation of waves and their active interactions in a distributed semiconductor structure has been treated in the context of the small-signal theory. A semiconductor plasma is analyzed to a quasi-dynamic approximation. A study has been made of the interaction between a plane electromagnetic (e.m.) wave and a multilayered semiconductor-dielectric structure with a diffraction grating. A numerical experiment has been performed. © 2012 by Begell House, Inc. Source

Linkova A.M.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2012

Results of study of double frequency method for measurement of rain intensity using three-parameter gamma distribution of drop sizes are presented. For elimination of measurement ambiguity of distribution parameters using data of double frequency sounding the use of data of contact measurement of connection between rain intensity and gamma distribution parameters was proposed. The results of calculations performed by the Mie theory were presented. They allow to estimate applicability of proposed method for polydisperse medium and to give recommendations for choice of frequency range for double frequency radar. ©2012 by Begell House, Inc. Source

Kuzmin Y.,Ukrainian Academy of Sciences
Zootaxa | Year: 2013

The review deals with the species of Rhabdiasidae Railliet, 1915 occurring in the Holarctic. Descriptions of 26 species from the genera Rhabdias Stiles et Hassal, 1905 (21 species), Entomelas Travassos, 1930 (4 species), and Kurolonema Szczerbak et Sharpilo, 1969 (1 species) are presented. Additionally, 5 species of Rhabdias are listed as species inquirenda, and 4 species are included into the review, since they have been reported close to south-eastern border of Palaearctic (the exact distribution is unknown). Keys to the Holarctic species and diagnoses of the genera are provided. An overview of the information on the biology, morphology and taxonomy of Rhabdiasidae is also presented, as well as the host-parasite list of Holarctic Rhabdiasidae. Copyright © 2013 Magnolia Press. Source

Nikitin A.Y.,University of Zaragoza | Nikitin A.Y.,Ukrainian Academy of Sciences | Guinea F.,CSIC - Institute of Materials Science | Garcia-Vidal F.J.,Autonomous University of Madrid | Martin-Moreno L.,University of Zaragoza
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Surface plasmon modes supported by graphene ribbon waveguides are studied and classified. The properties of both modes with the field concentration within the ribbon area (waveguiding modes) and on the edges (edge modes) are discussed. The waveguide and edge modes are shown to be separated from each other by a gap in wave numbers. The even-parity hybridized edge mode results to be the fundamental electromagnetic mode of the ribbon, possessing also the lowest losses. All of the plasmonic modes in the ribbons have an optimum frequency, at which the absorption losses are minimum, due to compromise between the plasmon confinement and the decrease of the group velocity close to the modal cutoff. The presented results show that the diffraction limit in graphene ribbons can be surpassed. © 2011 American Physical Society. Source

Nikitin A.Yu.,University of Zaragoza | Nikitin A.Yu.,Ukrainian Academy of Sciences | Garcia-Vidal F.J.,Autonomous University of Madrid | Martin-Moreno L.,University of Zaragoza
Physical Review Letters | Year: 2010

We present an analytical expression for the electromagnetic field at the surface radiated by a hole in a metal film. This expression is valid for any metal, from the optical range to longer wavelengths, and for distances to the hole larger than a few tens of nanometers. The field pattern presents a rich behavior, showing three regions (a complex short distance, an intermediate range dominated by surface plasmon polaritons, and a long-distance one dominated by Norton waves). The crossover distances between these regimes depend strongly on both the wavelength and the angle with respect to the incident field. © 2010 The American Physical Society. Source

Victor V.,Ukrainian Academy of Sciences
Palaeontologia Polonica | Year: 2011

In the marine Přidolian to early Lochkovian environments of Podolia, vertebrates were represented almost exclusively by thelodonts and acanthodians. Starting from the mid Lochkovian (Chortkiv Formation), the heterostracans increased their abundance and diversity. Diverse macroscopic remains of the cyathaspidid heterostracans, the first small-size pteraspidids and osteostracans appeared in the late Lochkovian (Ivanie Formation). The Old Red-type ecosystem of Podolia gradually emerged with retreat of the sea. Simultaneously, various agnathans, with ecological preferences to brackish or fresh waters, appeared. At the transition to the Pragian (red-bed Dniester Formation), when coarse terrigenous quartz sand gradually replaced fine carbonate silt and clay, the armoured vertebrate community reached its peak diversity, especially regarding the osteostracans and pteraspidid heterostracans. Many local lineages developed but some ties of the heterostracan faunas with those of west- ern European and the osteostracan faunas with Spitsbergen ones are traceable. Most evolu- tionary series recognised show increase in body size, both regarding the heterostracans and osteostracans. Taxonomic diversity decreased with coarsening of the sandy sediment and in- crease of sedimentation rate, culminating in complete disappearance of fish fossils before the Emsian. The sensory line system of the pteraspidids, with supraorbital commissures devel- oped on the rostral plate and arrangement of dorsomedial canals on the dorsal shield, is pro- posed to have high diagnostic value. Some 33 species, belonging to 20 genera of the hetero- stracans and 16 species of 9 genera of the osteostracans, are described. Althaspis tarloi sp. n., Djurinaspis secunda sp. n., Palanasaspis chekhivensis gen. et sp. n., Podolaspis danieli sp. n., Semipodolaspis slobodensis gen. et sp. n., and Zenaspis kasymyri sp. n. are proposed. © by the Institute of Paleobiology of the Polish Academy of Sciences Warszawa 2011. Source

Kuznetsov N.Y.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

A permutation (s0, s1, ⋯,sN−1) of symbols 0,1,,⋯, N− 1 is called “good” if the set (t0, t1,⋯,tN−1) formed by the rule ti=i + si (mod N),i = 0,1,⋯, N−1, is also a permutation. The author proposes the fast simulation method. Its implementation on the SCIT-4 multiprocessor computer complex makes it possible to evaluate the number of “good” permutations for N ≤ 305 with relative accuracy no greater than 1%. The number of “good” permutations is estimated for N 25, 35, ⋯, 305. © 2016, Springer Science+Business Media New York. Source

Laptin Y.P.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

Using exact penalty functions in schemes of decomposition in variables for nonlinear optimization make it possible to overcome problems related to implicit description of the feasible region of master problem. The paper deals with determining the values of penalty coefficients in such an approach. In the case where the functions of the original problem are not defined on the whole space of variables, the author proposes to use convex extension of functions. © 2016, Springer Science+Business Media New York. Source

Ostrovskiy A.V.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

We analyze the problem of choosing the optimal order of hidden Markov model for recognizing functional gene fragments. We propose four statistical criteria to determine the optimal order, which are based on likelihood ratio test, ergodicity, Markov property, and Akaike’s information criterion. Additionally, we confirm the efficiency of Bayesian mixtures of Markov models for solving the problem in question and determine the optimal mixture size using statistical criteria. © 2016, Springer Science+Business Media New York. Source

Bila G.D.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

A stochastic “signal plus noise”model of transmission of information is investigated in the case of an unknown signal function from some compact set of almost periodic functions K. The function is observed against the background of the random noise specified by the functional of a Gaussian random process with strong dependence. The problem of identification of a signal from observations of x(t) on an interval [0, T] is studied, and the consistency and asymptotic normality of the estimate obtained for the signal are proved. © 2016, Springer Science+Business Media New York. Source

The structural features of gallium nitride polycrystalline coating formed on a silicon oxide substrate have been considered. It has been shown experimentally that as crystals grow, not only the surface morphology, but crystalline structure and electrophysical parameters of crystals change also. The topography of crystals surfaces at the initial stage of the coating deposition has been found to form due to a diffusion mass transfer. © 2016, Allerton Press, Inc. Source

The effect of the conditions of cooling after the liquid-phase sintering of tungsten heavy metals have been studied. It has been found that to attain a high ductility of the tungsten heavy metal, the rate of cooling from the sintering temperature should afford removal of the major part of hydrogen, which was dissolved in the alloy volume in the temperature range of the liquid phase existence. © 2016, Allerton Press, Inc. Source

The paper addresses the simplest 3D model—a barrel made of parabolic and circular staves—for a diamond grain in the electroplated coating of dressing tools. It is shown that the proposed concepts of a diamond grain shape provide, on the one hand, an adequate description (including the quantitative one) the experimentally found relations between the parameters of an electroplated diamond coating and, on the other hand, a more detailed information in order to produce coatings with preset characteristics. © 2016, Allerton Press, Inc. Source

Abbas C.A.,Archer Daniels Midland Company | Sibirny A.A.,Ukrainian Academy of Sciences | Sibirny A.A.,University of Rzeszow
Microbiology and Molecular Biology Reviews | Year: 2011

Riboflavin [7,8-dimethyl-10-(1′-D-ribityl)isoalloxazine, vitamin B2] is an obligatory component of human and animal diets, as it serves as the precursor of flavin coenzymes, flavin mononucleotide, and flavin adenine dinucleotide, which are involved in oxidative metabolism and other processes. Commercially produced riboflavin is used in agriculture, medicine, and the food industry. Riboflavin synthesis starts from GTP and ribulose-5-phosphate and proceeds through pyrimidine and pteridine intermediates. Flavin nucleotides are synthesized in two consecutive reactions from riboflavin. Some microorganisms and all animal cells are capable of riboflavin uptake, whereas many microorganisms have distinct systems for riboflavin excretion to the medium. Regulation of riboflavin synthesis in bacteria occurs by repression at the transcriptional level by flavin mononucleotide, which binds to nascent noncoding mRNA and blocks further transcription (named the riboswitch). In flavinogenic molds, riboflavin overproduction starts at the stationary phase and is accompanied by derepression of enzymes involved in riboflavin synthesis, sporulation, and mycelial lysis. In flavinogenic yeasts, transcriptional repression of riboflavin synthesis is exerted by iron ions and not by flavins. The putative transcription factor encoded by SEF1 is somehow involved in this regulation. Most commercial riboflavin is currently produced or was produced earlier by microbial synthesis using special selected strains of Bacillus subtilis, Ashbya gossypii, and Candida famata. Whereas earlier RF overproducers were isolated by classical selection, current producers of riboflavin and flavin nucleotides have been developed using modern approaches of metabolic engineering that involve overexpression of structural and regulatory genes of the RF biosynthetic pathway as well as genes involved in the overproduction of the purine precursor of riboflavin, GTP. Copyright © 2011, American Society for Microbiology. All Rights Reserved. Source

Izotov Y.I.,Ukrainian Academy of Sciences | Thuan T.X.,University of Virginia
Astrophysical Journal Letters | Year: 2010

We present a new determination of the primordial helium mass fraction Yp , based on 93 spectra of 86 low-metallicity extragalactic H II regions, and taking into account the latest developments concerning systematic effects. These include collisional and fluorescent enhancements of He I recombination lines, underlying He I stellar absorption lines, collisional and fluorescent excitation of hydrogen lines, and temperature and ionization structure of the H II region. Using Monte Carlo methods to solve simultaneously for the above systematic effects, we find the best value to be Yp = 0.2565 ± 0.0010 (stat.) ± 0.0050 (syst.). This value is higher at the 2σ level than the value given by standard big bang nucleosynthesis, implying deviations from it. The effective number of light neutrino species N ν is equal to 3.68+0.80 -0.70 (2σ) and 3.80+0.80 -0.70 (2σ) for a neutron lifetime τn equal to 885.4 ± 0.9 s and 878.5 ± 0.8 s, respectively, i.e., it is larger than the experimental value of 2.993 ± 0.011. © 2010. The American Astronomical Society. All rights reserved. Source

Semenishyn N.,Technion - Israel Institute of Technology | Semenishyn N.,Ukrainian Academy of Sciences | Gross Z.,Technion - Israel Institute of Technology
Dalton Transactions | Year: 2013

Ditopic corroles with lanthanide-binding motifs were prepared and shown to be dual-range emitters, in the visible and near-IR, in ambient conditions. This journal is © 2013 The Royal Society of Chemistry. Source

Breslavsky I.D.,Ukrainian Academy of Sciences
Journal of Sound and Vibration | Year: 2012

The method of analysis of stress intensity distribution over vibrating plates is presented. Both the geometrical and physical nonlinearities are taken into account. It is showed that with the help of the small parameter method it is possible to obtain the expression for the transverse normal strain in a form, which is convenient for analytical transformations. The dynamic deflection is expanded into truncated series of eigenmodes and discrete model of the system is derived. The backbone curves of thin rectangular immovably simply supported plate vibrations are obtained. The stress intensity distribution patterns over the plate are analyzed. It is noted that in case of nonlinear vibrations not only the magnitudes of stress intensity depend on the vibration amplitude, but also on the pattern of its distribution. © 2012 Elsevier Ltd. All rights reserved. Source

Kameneva E.P.,Ukrainian Academy of Sciences
Vestnik Zoologii | Year: 2013

Herina caribbeana Kameneva, sp. n. from Dominica is described and figured. It is related to the narytia group of species, to date represented by 4 North American species, but differs from these by the wing pattern (dark spots at apex of R1 and on the crossbands r-m and dm-cu separated, not forming crossband), as well as male genitalia (prensisetae long and close together). This is the first record of the genus Herina Robineau-Desvoidy, 1830 from the Neotropical Region. A key to the New World species is provided. Source

Dublenych Yu.I.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2016

Exact and rigorous solutions of the ground-state problem for the classical Heisenberg model with nearest-neighbor interactions on two- and three-dimensional lattices composed of zigzag (triangular) ladders are obtained in a very simple way, with the use of a cluster method. It is shown how the geometrical frustration due to the presence of triangles as structural units leads to the emergence of incommensurate spiral orderings and their frustrated collinear limits which become nonfrustrated if the interaction along ladder legs changes the sign (becoming ferromagnetic). Interestingly, these orderings are determined by a single angle (along with the signs of the interactions between neighboring spins); therefore, the term "single-angle spiral ordering" is proposed. A hypothesis about the origin of a puzzling spin ordering in a zigzag ladder compound β-CaCr2O4 is made. © 2016 American Physical Society. Source

Yeryomenko Y.A.,Ukrainian Academy of Sciences
Russian Journal of Biological Invasions | Year: 2014

This paper presents results of study of allelopathic activity of invasive species Ailanthus altissima (Mill.) Swingle and Acer negundo L. in the southeast of Ukraine. The data show that physiologically active substances, which are contained in the soil under the canopy of arboreal plants under study, act mainly as inhibitors of growth. The low number of species under their crowns can be explained by not only the lack of light but also allelopathic influence. © Yu.A. Yeryomenko, 2014. Source

Pedenko Y.A.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2011

Computer simulation of a low-altitude target elevation anglemeasurement over a rough sea surface under conditions of a strong diffuse reflection is performe using MUSIC method. It is found that a part of diffuse reflection arriving from the "glittering" surface, the zone nearest tothe radar, exerts the greatest action on the errors. The axes, being a part of the receivingantenna array, are offered to align at the positive angle to the interface with the aim to reduce the errors value. In this case the antenna radiation patterns should suppress as much aspossible the diffuse reflection signals arriving from th near zone ensuring a sufficient level forreception of the signal arriving from the target. Characteristics of elevation angle measurement errors in various phases of interference of primary and mirror signals in the rceiving antenna array center and at different angles of elevation of receiving antennas axes are analyzed. © 2010 by Begell House, Inc. Source

Nikitina N.V.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2011

Loss of the orbital stability of a double pendulum is considered in terms of Lyapunov exponents. The boundaries of the domain of stochastic motion caused by bifurcational and chaotic processes are estimated. © 2011 Springer Science+Business Media, Inc. Source

Bespalova E.I.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2011

An approach to calculate the natural frequencies of an elastic parallelepiped with different boundary conditions is proposed. The approach rationally combines the inverse-iteration method of successive approximations and the advanced Kantorovich-Vlasov method. The efficiency of the approach (the accuracy of the results and the number of approximating functions) is demonstrated against the Ritz method with different basis systems, including B-splines. The dependence of the lower frequencies of a three-dimensional cantilever beam on its cross-sectional dimensions is examined © 2011 Springer Science+Business Media, Inc. Source

Gorban I.I.,Ukrainian Academy of Sciences
Radioelectronics and Communications Systems | Year: 2011

New parameters describing disturbance of statistical stability on a finite observation interval are proposed. Measuring units that allow to quantitatively characterize disturbance of statistical stability for the known and new statistical instability parameters. It is shown that fluctuations of expected value, which lead to changes of mean expected value, and dispersion fluctuations under certain parameters play an essential role in disturbance of statistical stability. Change ranges of sampling statistical instability parameter values weakly depend on the distribution law. © 2011 Allerton Press, Inc. Source

Polishchuk P.G.,Ukrainian Academy of Sciences | Madzhidov T.I.,Kazan Federal University | Varnek A.,University of Strasbourg
Journal of Computer-Aided Molecular Design | Year: 2013

The goal of this paper is to estimate the number of realistic drug-like molecules which could ever be synthesized. Unlike previous studies based on exhaustive enumeration of molecular graphs or on combinatorial enumeration preselected fragments, we used results of constrained graphs enumeration by Reymond to establish a correlation between the number of generated structures (M) and the number of heavy atoms (N): logM = 0.584 × N × logN + 0.356. The number of atoms limiting drug-like chemical space of molecules which follow Lipinsky's rules (N = 36) has been obtained from the analysis of the PubChem database. This results in M ≈ 1033 which is in between the numbers estimated by Ertl (1023) and by Bohacek (1060). © 2013 Springer Science+Business Media Dordrecht. Source

Balashov I.,Ukrainian Academy of Sciences
Journal of Conchology | Year: 2012

One immature specimen of Selenochlamys cf. ysbryda Rowson & Symondson 2008 subterranean carnivorous slug, was found in the coliections of 1989 from the Crimean Mountains in Ukraine. By the reduced eyes, structure of tentacle retractors and large size of the body this slug corresponds well to S. ysbryda, but not to the second species of this genus S. pallida. However because of immaturity it is not certain that this slug belongs exactly to S. ysbryda. The specimen is compared with a specimen of S. pallida from the Caucasus. Habitat and biology of S. cf. ysbryda in the Crimea is discussed. It appears to be a native species. Source

Shul'Ga N.A.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2013

A general analysis of the mixed systems of four equations in Kirchhoff's theory of the vibrations of plates in rectangular and polar coordinates is carried out. It is shown that these systems can be represented in Hamiltonian (canonical) operator form in space coordinate after the selection of the appropriate "canonical" variables and operator Hamiltonian. Functionals for canonical systems are formulated © 2013 Springer Science+Business Media New York. Source

Semenyuk N.P.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2013

A method of analyzing the stability and post-buckling behavior of corrugated arches is proposed. It involves solving a nonlinear system of first-order differential equations with the method of incremental loading. The boundary-value problem for increments is solved with the discrete- orthogonalization method. The results obtained show that the behavior of corrugated arches is essentially different from that of circular arches © 2013 Springer Science+Business Media New York. Source

Gogotsi G.A.,Ukrainian Academy of Sciences
Strength of Materials | Year: 2013

We illustrate the relationship between the deformation characteristics, fracture resistance, including the effects of R-curve and the R-line, and heat resistance of ceramic materials. The expediency of the classification of materials via the deformation characteristics is shown. The brittleness measure is shown to be a lucrative classification parameter. It has been found that reliable assessment of various ceramic materials within framework of thermal stability criteria should be based on the true limiting elastic deformations, rather than on the elasic limiting deformation values. The analysis of test results made it possible to determine the behavior of materials under different conditions of mechanical and thermal loading. The techniques that have been used in obtaining the experimental data are discussed. The experiments have been conducted using elastic and inelastic, oxide and non-oxide, as well as composite ceramic materials. © 2013 Springer Science+Business Media New York. Source

Timchenko V.,Ukrainian Academy of Sciences
Ecohydrology and Hydrobiology | Year: 2016

The understanding of ecohydrology in Ukraine, which was formed due to a large number of detailed hydrological investigations in natural and artificial water bodies, is presented. The approach presented here focuses on one of the hydrology side of this scientific discipline that is to study hydrological processes, which are responsible for the functioning of aquatic ecosystems, vital activity of hydrobionts, bioproductivity of the aquatic environment and its quality. The main goal of ecohydrology is to develop management methods of structural and functional parameters of aquatic ecosystems. In this approach, ecohydrology is a part of aquatic ecology (hydroecology). © 2016 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved. Source

Karlash V.L.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2013

Piezoelectric bars with sectional electrodes are studied experimentally. It is shown that the distribution of internal mechanical stresses remains harmonic after the sectionalization of the electrodes. The constant output voltage between the resonances is due to capacitive division © 2013 Springer Science+Business Media New York. Source

Campione S.,University of California at Irvine | Steshenko S.,University of Siena | Steshenko S.,Ukrainian Academy of Sciences | Capolino F.,University of California at Irvine
Optics Express | Year: 2011

Bound and leaky modes with complex wavenumber in chains (linear arrays) of plasmonic nanospheres are characterized for both longitudinal and transverse polarization states (with respect to the array axis). The proposed method allows for the description of each mode evolution when varying frequency. As a consequence, full characterization of the guided modes with complex wavenumber is provided in terms of propagation direction, guidance or radiance, proper or improper, and physical or nonphysical conditions. Each nanosphere is modeled according to the single dipole approximation, and the metal permittivity is described by the Drude model. Modal wavenumbers are obtained by computing the complex zeroes of the homogeneous equation characterizing the field in the one dimensional periodic array. The required periodic Green's function is analytically continued into the complex wavenumber space by using the Ewald method. Furthermore, a parametric analysis of the mode wavenumbers is performed with respect to the geometrical parameters of the array. © 2011 Optical Society of America. Source

A method has been developed for producing a sharp crack and evaluating the fracture toughness characteristics of ceramic materials from the acoustic emission parameters. The method involves the use of a computer-aided measuring and control system and the appropriate FAE 1.0 software. With this method, it is possible to determine the important characteristics of the fracture toughness of ceramics, such as the R-curve for a fixed crack growth rate and V - K 1-diagram in a wide range of subcritical crack growth rates. © 2013 Springer Science+Business Media New York. Source

Maksymov P.P.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2010

An algorithm has been developed for solving the equations of the drift-diffusion model of reverse-based pn-i - pn structures with abrupt p - n junctions. The algorithm is based on the finite-difference equations of the modified counter-sweep method, combined with a technique for calculating semiconducting pn - i - pn structures with abrupt p-n junctions and methods for analyzing abrupt p-n junctions in the self-oscillation regime. The computation error is estimated for the electric field in Ge-, Si-and GaAs-based pn - i - pn structures with a feedback. The relative error of computation has been shown to decrease as the number of modes of the finite difference scheme is increased being limited by the error at approximating to differential operators by the finite-difference ones. The electric field selfoscillations and current densities in such structures are analyzed along with their spectra. The limiting case of low avalanche currents has been investigated. © 2010 by Begell House, Inc. Source

Manini N.,University of Milan | Braun O.M.,Ukrainian Academy of Sciences
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2011

For the contact of two finite portions of interacting rigid crystalline surfaces, we compute the pinning energy barrier dependency on the misfit angle and contact area. This simple model allows us to investigate a broad contact-size and angular range, thus obtaining the statistical properties of the energy barriers opposing sliding for a single asperity. These data are used to generate the distribution of static frictional thresholds for the contact of polycrystals, as in dry or even lubricated friction. This distribution is used as the input of a master equation to predict the sliding properties of macroscopic contacts. © 2011 Elsevier B.V. All rights reserved. Source

Campione S.,University of California at Irvine | Steshenko S.,University of Siena | Steshenko S.,Ukrainian Academy of Sciences | Albani M.,University of Siena | Capolino F.,University of California at Irvine
Optics Express | Year: 2011

We characterize the modes with complex wavenumber for both longitudinal and transverse polarization states (with respect to the mode traveling direction) in three dimensional (3D) periodic arrays of plasmonic nanospheres, including metal losses. The Ewald representation of the required dyadic periodic Green's function to represent the field in 3D periodic arrays is derived from the scalar case, which can be analytically continued into the complex wavenumber space. We observe the presence of one longitudinal mode and two transverse modes, one forward and one backward. Despite the presence of two modes for transverse polarization, we notice that the forward one is "dominant" (i.e., it contributes most to the field in the array). Therefore, in case of transverse polarization, we describe the composite material in terms of a homogenized effective refractive index, comparing results from (i) modal analysis, (ii) Maxwell Garnett theory, (iii) Nicolson-Ross-Weir retrieval method from scattering parameters for finite thickness structures (considering different thicknesses, showing consistency of results), and (iv) the fitting of the fields obtained through HFSS simulations. The agreement among the different methods justifies the performed homogenization procedure in case of transverse polarization. © 2011 Optical Society of America. Source

Rozenbaum V.M.,Ukrainian Academy of Sciences | Shapochkina I.V.,Belarusian State University
JETP Letters | Year: 2015

A generalized approach has been proposed to describe the diffusive transport of inertial particles at which the known inertialess relations (in particular, between the concentration of particles and the corresponding flux) are supplemented by a factor allowing the calculation of inertial effects in terms of the matrix continued fraction method. The advantage of this approach, which is in the analytical representation of the results, is illustrated by solving the problem of the determination of the effective diffusion coefficient of an inertial particle in a sawtooth potential and the average velocity of the adiabatic inertial ratchet. The character of the nonanalytic behavior of these quantities in the presence of large gradients of the potential has been established. © 2015, Pleiades Publishing, Inc. Source

Krainyukova N.V.,Ukrainian Academy of Sciences
Journal of Low Temperature Physics | Year: 2010

We apply a modified Debye approach to calculate the Gibbs free energy for different structural phases and crystallite sizes in 4He. Atoms are assumed to interact via the Aziz potential. We have found that some intermediate (between hcp and bcc) phase predicted previously is more favorable than hcp at low temperatures and for small sizes. We show that it can exist in a wide pressure range up to 60 bar in 4He for crystallite sizes about 3,000 atoms. For larger sizes (10,000 atoms or more) this phase becomes unfavorable. In multidomain structures the intermediate phase competes with hcp and metastable fcc that can be a reason for disorder in solid 4He. © 2009 Springer Science+Business Media, LLC. Source

Krainyukova N.V.,Ukrainian Academy of Sciences
Journal of Low Temperature Physics | Year: 2010

The modified Debye approach was used to calculate the Gibbs free energy for solid 4He and energetic profiles for different atomic displacements with respect to an equilibrium lattice. Atoms interact via the applied Aziz potential. We have found that individual atomic displacements may hardly give rise to any delocalization because of huge barriers but cooperative plane sliding is highly plausible especially in the intermediate phase, which was found to be more favorable than hcp for small cluster sizes. In the latter case the roughness of the potential profile is less than one kelvin. In some particular sliding cases the energy levels in the nearest wells nearly coincide that is a well-known precursor for the delocalization effect. © 2009 Springer Science+Business Media, LLC. Source

Malyshev V.V.,Ukrainian Academy of Sciences
Materials Science | Year: 2011

A review of experimental investigations of electrochemical deposition of tungsten from ionic melts is presented. The electrolytes used are systematized depending on the structure of deposits. © 2011 Springer Science+Business Media, Inc. Source

Fil D.V.,Ukrainian Academy of Sciences | Fil D.V.,Max Planck Institute for Solid State Research
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The counterflow transport in quantum Hall bilayers provided by superfluid excitons is locked at small input currents due to a complete leakage caused by the interlayer tunneling. We show that the counterflow critical current Ic CF above which the system unlocks for the counterflow transport can be controlled by a tilt of magnetic field in the plane perpendicular to the current direction. The effect is asymmetric with respect to the tilting angle. The unlocking is accompanied by switching of the systems from the dc to the ac Josephson state. Similar switching takes place for the tunneling setup when the current flowing through the system exceeds the critical value IcT. At zero tilt the relation between the tunnel and counterflow critical currents is IcT =2 Ic CF. We compare the influence of the in-plane magnetic field component B on the critical currents Ic CF and IcT. The in-plane magnetic field reduces the tunnel critical current and this reduction is symmetric with respect to the tilting angle. It is shown that the difference between Ic CF and IcT is essential at field | B | 0 /d λJ, where 0 is the flux quantum, d is the interlayer distance, and λJ is the Josephson length. At larger B the critical currents Ic CF and IcT almost coincide each other. © 2010 The American Physical Society. Source

Braun O.M.,Ukrainian Academy of Sciences
EPL | Year: 2015

The stick-slip and smooth sliding regimes of motion for the multicontact frictional interface are studied within the earthquake-like model. It is shown that the stick-slip appears when two necessary conditions are fulfilled: first, the system must be soft enough for the elastic instability to emerge, and second, it must be ageing of the interface. The stick-slip exists only for an interval of sliding velocities v 1< v d < v 2, where both boundary velocities v 1,2 are determined by the ageing rate. © EPLA, 2015. Source

A complete and exact solution of the ground-state problem for the Ising model on the Shastry-Sutherland lattice in an applied magnetic field is found. The magnetization plateau at one third of the saturation value is shown to be the only possible fractional plateau in this model. However, stripe magnetic structures with 1/2 and 1/n (n>3) magnetization, observed in the rare-earth-metal tetraborides RB 4, occur at the boundaries of the three-dimensional regions of the ground-state phase diagram. These structures give rise to new magnetization plateaus if interactions of longer range are taken into account. For instance, an additional third-neighbor interaction is shown to produce a 1/2 plateau. The results obtained significantly refine the understanding of the magnetization process in RB 4 compounds, especially in TmB 4 and ErB 4, which are strong Ising magnets. © 2012 American Physical Society. Source

We propose a transformation of real input vectors to output binary vectors by projection using a binary random matrix with elements {0,1} and thresholding. We investigate the rate of convergence of the distribution of vector components before binarization to the Gaussian distribution as well as its relationship to the estimation error of the angle between the input vectors by the binarized output vectors. It is shown that for the choice of projection parameters that provide nearly-Gaussian distribution, the experimental and analytical errors are close. ©2015 Springer Science+Business Media New York. Source

Gafiychuk V.,SGT Inc. | Gafiychuk V.,NASA | Datsko B.,Ukrainian Academy of Sciences
Computers and Mathematics with Applications | Year: 2010

In this article we investigate possible scenarios of pattern formations in reaction-diffusion systems with time fractional derivatives. Linear stability analysis is performed for different values of derivative orders. Results of qualitative analysis are confirmed by numerical simulations of specific partial differential equations. Most attention is paid to two models: a fractional order reaction diffusion system with Bonhoeffer-van der Pol kinetics and to the Brusselator model. © 2009 Elsevier Ltd. All rights reserved. Source

Perkovsky E.E.,Ukrainian Academy of Sciences
Paleontological Journal | Year: 2010

Arboreal specialists (including Ctenobethylus goepperti) comprise 54% of all ant inclusions in Rovno amber pieces weighing up to 1.5 g and 43% of those in larger pieces. In the small-size amber fraction, syninclusions containing more than a single worker ant are represented exclusively by the arboreal Dolichoderus spp. and C. goepperti, while syninclusions in larger amber pieces often contain workers of Lasius spp., which are not associated with trees. Species of Lasius comprise 15% of ants in the smaller and 28% in the larger amber pieces. It seems that the smaller pieces of amber have formed on the thinner branches of the amberproducing trees and, consequently, contain a larger proportion of arboreal ant species. Comparison of composition of inclusions between different weight fractions of amber is a promising tool to study fossil faunas and environments. © Pleiades Publishing, Ltd., 2009. Source

Raichev O.E.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

The response of two-dimensional electron gas to a temperature gradient in perpendicular magnetic field under steady-state microwave irradiation is studied theoretically. The electric currents induced by the temperature gradient and the thermopower coefficients are calculated taking into account both diffusive and phonon-drag mechanisms. The modification of thermopower by microwaves takes place because of Landau quantization of the electron energy spectrum and is governed by the microscopic mechanisms which are similar to those responsible for microwave-induced oscillations of electrical resistivity. The magnetic-field dependence of microwave-induced corrections to phonon-drag thermopower is determined by mixing of phonon resonance frequencies with radiation frequency, which leads to interference oscillations. The transverse thermopower is modified by microwave irradiation much stronger than the longitudinal one. Apart from showing prominent microwave-induced oscillations as a function of magnetic field, the transverse thermopower appears to be highly sensitive to the direction of linear polarization of microwave radiation. © 2015 American Physical Society. Source

Yesylevskyy S.O.,Ukrainian Academy of Sciences
Protein and Peptide Letters | Year: 2010

The Hierarchical Domain-Wise Alignment (HDWA) technique of domain identification in proteins is presented. HDWA is designed to identify hierarchically organized dynamic domains in proteins using the MD trajectories by eliminating systematic motions from MD trajectories recursively in a model-free manner. The method is tested on the proteins from different structural classes. © 2010 Bentham Science Publishers Ltd. Source

Chlubna P.,J. Heyrovsky Institute of Physical Chemistry | Roth W.J.,J. Heyrovsky Institute of Physical Chemistry | Greer H.F.,University of St. Andrews | Zhou W.,University of St. Andrews | And 4 more authors.
Chemistry of Materials | Year: 2013

This contribution reports new methodology we have developed for the disassembly of 3-D UTL framework into 2-D lamellae followed by structure modification including pillaring. This may be widely applicable, particularly to other zeolites that have D4R units present, and so should have great impact also on other porous solids. Specifically, controlled hydrolysis of D4R units in the interlayer space provides individual ultrathin layers with UTL structure by a chemically selective method. Further manipulation of the layers gives a completely novel approach (3D to 2D to pillared) offering hitherto unprecedented opportunities for the preparation of modified zeolites with diverse chemical and structural properties. © 2013 American Chemical Society. Source

Demchenko A.P.,Ukrainian Academy of Sciences
Journal of Molecular Structure | Year: 2014

Wavelength ratiometry (often abbreviated as λ-ratiometry) is one of the most popular methods to study intermolecular interactions that allows obtaining both thermodynamic and kinetic parameters and can be applied in a variety of sensing and imaging technologies. In comparison with simple recording of intensity it allows avoiding many technical problems and realizing many new possibilities. Here we briefly analyze different approaches in λ-ratiometric sensing that use single, double and multiple fluorescence emitters that are based on different mechanisms producing spectroscopic change and concentrate on their practical aspects. Finally we present several examples of successful application of this method and discuss the prospects for its further development. © 2013 Elsevier B.V. All rights reserved. Source

The influence of variations in the parameters, determining the physical properties of a medium, on the characteristics of the vertical structure of clouds in the Jovian atmosphere has been studied. The data from spectrophotometric measurements of Jupiter carried out in the spectral range from 500 to 900 nm during 1993 were processed. The analysis was performed with the method suggested by A.V. Morozhenko. We used a special software that was developed to define the behavior of the aerosol scattering component of the effective optical thickness versus the depth in a semi-infinite atmosphere. Spectral absorption bands of the atmospheric gas were considered. The characteristics of the vertical structure of the aerosol component of the Jovian atmosphere averaged over the planetary disk were determined: in the atmospheric layer with a pressure ranging from 0.12 to 1.3 bar, the volume density of the aerosol cloud first rapidly increases and then gently reaches its maximum; from 1.3 to 4.0 bar, the aerosol cloud becomes extremely rarefied; from 4.0 to 15.0 bar, there are no indications of significant aerosol inclusions. © 2015, Pleiades Publishing, Inc. Source

Kravets V.G.,University of Manchester | Neubeck S.,University of Manchester | Grigorenko A.N.,University of Manchester | Kravets A.F.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We have experimentally and theoretically demonstrated strong absorption of visible light in a thin nanostructured layer consisting of silver nanoparticles embedded in a dielectric matrix. Light absorption at the level of above 90% is recorded over a wide optical wavelength range (240-850 nm) and for a broad range of angles of light incidence (0°-70°) in extremely thin films (160 nm). We suggest a generic principle for enhancement of light absorption in thin layers of artificial metamaterials and show that effective refractive indices of our samples measured with the help of ellipsometry can be adequately described by an effective-medium theory. We demonstrate that a substantial fraction of light can be trapped in the nanostructured film due to scattering by noble metal nanoparticles and total internal reflection. © 2010 The American Physical Society. Source

Usatenko Z.,Ukrainian Academy of Sciences
Journal of Molecular Liquids | Year: 2011

The universal density-force relation is analyzed and the correspondent universal amplitude ratio Breal is obtained using the massive field theory approach in fixed space dimensions d = 3 up to one-loop order. The layer monomer density profiles of ideal chains and real polymer chains with excluded volume interaction in a good solvent between two parallel repulsive walls, one inert and one repulsive wall and for the case of wall and a mesoscopic spherical particle of a big radius are obtained using the massive field theory approach up to one-loop order. The last mentioned situation is analyzed for both cases when wall and particle are repulsive and for the mixed case of repulsive wall and inert particle. Besides, the layer monomer density profiles of polymer chains with one end fixed at the surface and other free are analyzed near the repulsive and inert wall up to two-loop order. The obtained results are in qualitative agreement with previous theoretical investigations and with the results of Monte Carlo simulations. © 2011 Elsevier B.V. All rights reserved. Source

Baumketner A.,Ukrainian Academy of Sciences
Journal of Physical Chemistry B | Year: 2014

Folding and aggregation lie on competing reaction pathways in proteins. Altering the occupancy of one pathway is automatically relayed to the other pathway, leading to a shift in the balance between the two processes. In particular, it is known that the stabilization of the native state through mutations or solvent alterations is able to halt aggregation. In this work, we explore the feasibility of using external electric field as an agent preventing aggregation through the promotion of folding. We use an atomically accurate protein model and computer simulations to investigate folding and aggregation of alanine polypeptides in electric field of varying strength. The studied peptides are mostly unstructured in the absence of the field but experience a transition into α-helical states when the field is applied. The transition is accompanied by the disassembly of preseeded stacked β-sheets, which are used as a model of amyloid fibrils, suggesting that electric field can be employed to control aggregation propensity of intrinsically disordered peptides. According to our calculations, the strength of the field required for the disaggregation could be suitable for both controlled in vitro experiments as well as for experiments on live cells. Additionally, our estimates suggest that endogenous electric fields may have a significant effect on in vivo amyloid formation. © 2014 American Chemical Society. Source

Khomyak O.N.,Ukrainian Academy of Sciences
Journal of Automation and Information Sciences | Year: 2013

We consider two Markovian chains. One chain defines efficiency of system operation, another defines demanded system efficiency. Probability of functional fault is investigated, when current efficiency of the system becomes lower than the demanded one. We suggested fast method of modeling and found conditions, which guarantee boundedness of relative root-mean-square error on increase of reliability of system elements. Numerical example is stated. © 2013 by Begell House Inc. Source

Maslova O.O.,Ukrainian Academy of Sciences
Biopolymers and Cell | Year: 2012

Although mesenchymal stem cells (MSC) are in a focus of attention, some aspects of their biology are still unclear. This paper is a review of current research on MSC biology. The use ofMSC in regenerative medicine is also briefly discussed. © Institute of Molecular Biology and Genetics, NAS of Ukraine, 2012. Source

Tykhomyrov A.A.,Ukrainian Academy of Sciences
Biopolymers and Cell | Year: 2012

In the present review, we have summarized and analyzed the literature data concerning cooperation between multifunctional proteins, the components of plasminogen/plasmin system and actin. The mechanisms underlying intermolecular interactions and the role of plasminogen kringle domains in protein-protein recognition are reviewed. A particular attention is paid to extracellular actin that serves as a surface protein of plasma membrane in various cells. A putative role of surface actin as the universal «non-hemostatic» center of plasminogen activation is discussed. The exposition of cytoskeletal actin on the outer surface of cellular membrane is thought to be a phenomenon, which is involved in both normal cell functioning and development of pathologies. In particular, the mechanism of plasminogen fragmentation on the surface of cancer cells mediated by actin, which re- sults in generation of endogenous suppressors of tumor growth and metastazing (angiostatins), is described. It has been acknowledged that the plasminogen/plasmin system in concert with surface actin regulates releasing biologically active substances, e. g. catecholamines. The comprehensive assessment of plasminogen/plasmin system and surface actin exposition is proposed to be a criterion of functional status of cells and can be used as a diagnostic parameter at various pathologies. © Institute of Molecular Biology and Genetics, NAS of Ukraine, 2012. Source

Rassamakin Y.,Ukrainian Academy of Sciences | Menotti F.,University of Basel
Radiocarbon | Year: 2011

The long tradition of relative chronology based on pottery typology has often hindered the development of radiocarbon dating amongst the Tripolye giant-settlement in Ukraine. Although it is fairly reliable, relative chronology encounters insurmountable obstacles in identifying internal phases of development within a single settlement. This paper presents the first attempt to use 14C dates to monitor the chronological development of the Talianki giant-settlement, from its formation to the various phases of development and the final decline. It then goes one step further by proving genetic links between 2 "neighboring" settlements, confirming that one is the result of migration processes of the other. This study does not intend to prove that one of the dating techniques is better than the other, but to demonstrate that a synergetic combination of the 2 methods will certainly lead to more reliable results. © 2011 by the Arizona Board of Regents on behalf of the University of Arizona. Source

Rodik R.V.,Ukrainian Academy of Sciences
Ukrain'skyi Biokhimichnyi Zhurnal | Year: 2012

First results of non-ionic and poly-cationic calixarenes utilization for gene transfection are presented and analyzed in this survey. State of the art in the field of scientific searching for new non-viral vectors are shown in the general form. The prospects of supramolecular concept in design agents for transfection are demonstrated. Some relationships between calixarene architecture and calixarene ability to promote gene transfection are revealed, namely: formation of supramolecular self-assembled aggregates at water media facilitates hierarchical formation of complexes with DNA molecules. Latter particles will effectively transfect genes if they are nano-sized and positivelycharged. Source

A convenient synthesis of methyl α-iminotrifluoropropionate (methyl 3,3,3-trifluoro-2-iminopropanoate, 3), based on the aza-Wittig reaction of methyl trifluoropyruvate with triphenylphosphine imide, was developed. The synthetic potential of N-H imine 3, existing as equilibrium mixture (10:1) of E/Z isomers, in the preparation of functionalized acyclic and heterocyclic derivatives possessing a pharmacophoric trifluoroalanine fragment, is disclosed. © Georg Thieme Verlag Stuttgart. Source

Kolesnikova E.E.,Ukrainian Academy of Sciences
Neurophysiology | Year: 2013

This paper reviews the published data of modern studies, which allow one to summarize the accumulated knowledge on the molecular mechanisms underlying the development of some neurodegenerative diseases and the role of disorders of these mechanisms in the pathogenesis of diseases directly related to the impairments of mitochondrial functions. © 2013 Springer Science+Business Media New York. Source

Purnyn H.,Ukrainian Academy of Sciences
Neurophysiology | Year: 2013

Examination of the functioning of the visual analyzer is an urgent task in modern neurophysiology. The peripheral receptor part of this analyzer, the retina, provides perception of light signals, their transformation into nerve impulses, and transfer of impulsation to the brain. Retinal rods responsible for perception of black-and-white images and cones responsible for color light perception are connected, via bipolar neurons, to ganglion retinal cells. Horizontal and amacrine cells are inhibitory neurons responsible for horizontal interaction within the retina. Processing of visual information in the retina is, to a significant extent, based on interaction of the receptive fields of its sensitive elements, the stimulation of which causes a response of the output neuron, the ganglion cell. This review considers modern concepts of functioning of the visual system of mammals at the retinal level and summarizes the data on cell elements of the retina, their connections, blood supply, and innervation, as well as on pathways for visual signal propagation in the retina. © 2013 Springer Science+Business Media New York. Source

Vishnyakova K.,South Scientific Research Institute of Marine Fisheries and Oceanography | Gol'Din P.,Ukrainian Academy of Sciences
ICES Journal of Marine Science | Year: 2015

In this study, we analyse seasonal aspects of harbour porpoise strandings in the Sea of Azov and discuss factors affecting the stranding rate. Data on 633 strandings were obtained frommonitoring of a 35-km long area of the south coast of the Sea of Azov in 1999-2013.Adistinct peak of strandings fell in July and August: it depended on the bycatch peak and calving season. Stranding rates depended neither on weather conditions nor on the seasonal fishing activities (including IUU fisheries). Moreover, stranding peaks in the neighbouring Black Sea were also tied to the calving season rather than to the fishing activities. We suggest that the seasonal mortality patterns are indirectly determined by nutritional stress: in Atlantic, winter-stranding oceanic populations and summer-stranding inner-sea populations occur that also possibly differ in the seasonal dynamics of body mass, weaning time or duration of mother-calf association, and dentine structure. In a typical summer-stranding population, summer is the season of nutritional stress, parturition, independent foraging of yearlings and lactation of nursing females, which leads to the risky foraging behaviour near gillnets. Another possible factor of increased bycatch is the seasonal habitat preference, corresponding to the gillnet preferences. Therefore, stranding and bycatch seasonality of porpoises can largely be explained by the aspects of their life history and foraging behaviour rather than by weather conditions and fisheries. This supports the time-area closure strategy as an adequate conservation measure, which would consider minimizing the conflict of interest with fisheries. © International Council for the Exploration of the Sea 2014. All rights reserved. Source

Pokutnii S.I.,Ukrainian Academy of Sciences
Semiconductors | Year: 2010

In the adiabatic approximation in the context of the modified effective mass approach, in which the reduced exciton effective mass μ = μ(a) is a function of the radius a of the semiconductor quantum dot, an expression for the exciton binding energy Eex(a) in the quantum dot is derived. It is found that, in the CdSe and CdS quantum dots with the radii a comparable to the Bohr exciton radii aex, the exciton binding energy Eex(a) is substantially (respectively, 7.4 and 4.5 times) higher than the exciton binding energy in the CdSe and CdS single crystals. © 2010 Pleiades Publishing, Ltd. Source

Akopova O.V.,Ukrainian Academy of Sciences
Fiziolohichnyǐ zhurnal (Kiev, Ukraine : 1994) | Year: 2012

The influence of exogenous cytochrome c on reactive oxygen species (ROS) formation and its dependence on mitochondrial permeability transition pore (MPTP) opening is studied in rat liver mitochondria. Fluorescent probe dichlorofluorescein (DCF) was used. It was shown that MPTP activation by increasing concentrations of Ca2+ in the medium results in the increase in mitochondrial ROS production and oxygen consumption, but the decrease in matrix calcium retention, dependent on the amount of added Ca2+. Cytochrome c in the incubation medium does not much influence ROS formation when MPTP opening is blocked by cyclosporine A. However, in the presence of cytochrome c MPTP opening is accompanied by dramatic increase in ROS production. Steep rise in DCF fluorescence because of matrix ROS formation is sensitive to MPTP opening and is not resulted from the direct interaction between the probe and cytochrome c outside the mitochondria. To explain obtained data the hypothesis is put forward that MPTP could serve for ROS exchange between the matrix and the medium where heme iron of cytochrome c would act as a catalytic center to enhance ROS production. We suppose that apart of its conventional function, cytochrome c which is not involved in electron transport, could serve in such way as the amplifier of ROS production which in turn would provide a background for the development of apoptosis due to MPTP opening. Source

Starovoitova S.A.,Ukrainian Academy of Sciences
Mikrobiolohichnyǐ zhurnal (Kiev, Ukraine : 1993) | Year: 2012

Cholesterol-lowering activity of probiotic strains of lactic acid bacteria genera Lactobacillus and Bifidobacterium in the in vivo experiments on the model of experimental hypercholesterolemia in mice was studied. It is established that the prophylactic scheme of introduction of probiotic cultures is more effective than therapeutic one for the manifestation of cholesteraze activity of probiotic cultures. The most effective were the cultures: L. acidophilus and B. bifidum, as well as the composition B. bifidum + B. longum. Cholesterol-lowering activity of the studied strains and their compositions in this experiment ranged between 40-78%. It is noted that cholesteraze activity of other studied strains was not lower and in some cases, higher than that of most of the drugs currently used in cholesterinozis. Source

The paper presents some findings of the investigation of finish turning of KhVG hardened steel using a cutting tool tipped with a round insert made of a composite based on cubic boron nitride (cBN-Si3N4 system). Based on the analysis of machined surface roughness, the cutting conditions have been found which ensure a stable interaction between the cutting tool and the workpiece. © 2013 Allerton Press, Inc. Source

Karabanova L.V.,Ukrainian Academy of Sciences | Mikhalovsky S.V.,University of Brighton | Lloyd A.W.,University of Brighton
Journal of Materials Chemistry | Year: 2012

Gradient semi-interpenetrating polymer networks (gradient semi-IPNs) as well as the traditional semi-interpenetrating polymer networks (semi-IPNs) were synthesized using polyurethane (PU) and poly(2-hydroxyethyl methacrylate) (PHEMA). The materials were characterized with respect to thermodynamic miscibility, NIR imaging, mechanical properties and morphological structure by tapping mode atomic force microscopy (TM AFM). The positive values of Gibbs free energy indicated that polymeric systems were thermodynamically immiscible. The dynamic mechanical analysis as well as TM AFM demonstrated that the systems under investigation were two-phase systems with incomplete phase separation. The gradient semi-IPNs were shown to have unique mechanical properties dependent on the composition and on the degree of microphase separation. The ability to create a layer of biocompatible polymer, such as PHEMA, at the surface, or create nanostructured surface consisting of nanodomains of different polymeric compositions, and engineer the improvements in the mechanical properties of the materials through the use of gradient systems should allow the creation of novel materials for biomedical application through the optimisation of mechanical properties, surface chemistry and biological properties. © 2012 The Royal Society of Chemistry. Source

Stepanenko D.I.,Ukrainian Academy of Sciences
Solid State Communications | Year: 2010

We show a mechanism for angle-dependent resonant oscillations of high-frequency conductivity and surface impedance in organic Q2D conductors in the presence of strong magnetic field H0. In highly anisotropic conducting systems, the drift velocity vD of electrons is an oscillatory function of the angle of the magnetic field direction. As a result the location of Landau absorption regions depends on the orientation of H0. Under the condition of anomalous skin effect, when the displacement of an electron over the period of electron motion in a magnetic field exceeds skin depth, the Landau damping becomes essential. In this case the angle-dependent oscillations of high-frequency conductivity and surface impedance result from the angular dependence of drift velocity should appear. For the directions of H0, such that vD is close to zero, the intensity of cyclotron resonance is of the same order as the intensity of the resonance in a magnetic field parallel to the sample surface. © 2010 Elsevier Ltd. All rights reserved. Source

Effect of annealing in high pressure oxygen atmosphere on superconducting transition temperatures for ceramic samples of magnetic superconductor RuSr2(Eu1.5 Ce0.5)Cu2O10.8 was studied. It was shown that properties of the samples are consistent with behavior of the granular superconducting system. As a result of oxygen saturation the superconducting transition temperatures become higher. Particularly, shift of the superconducting transition temperature for intergranular medium is Tcg - 9.2 K and for the matter within the granules ATcg = 6.8 K. This difference is due to the mechanism of oxygen diffusion along the grain boundaries. In the temperature range of 135 Source

Mishchenko M.I.,NASA | Dlugach Z.M.,Ukrainian Academy of Sciences | Zakharova N.T.,Trinnovim LLC
Optics Letters | Year: 2014

The modified unrestricted effective-medium refractive index is defined as one that yields accurate values of a representative set of far-field scattering characteristics (including the scattering matrix) for an object made of randomly heterogeneous materials. We validate the concept of the modified unrestricted effective-medium refractive index by comparing numerically exact superposition T-matrix results for a spherical host randomly filled with a large number of identical small inclusions and Lorenz-Mie results for a homogeneous spherical counterpart. A remarkable quantitative agreement between the superposition T-matrix and Lorenz-Mie scattering matrices over the entire range of scattering angles demonstrates unequivocally that the modified unrestricted effective-medium refractive index is a sound (albeit still phenomenological) concept provided that the size parameter of the inclusions is sufficiently small and their number is sufficiently large. Furthermore, it appears that in cases when the concept of the modified unrestricted effective-medium refractive index works, its actual value is close to that predicted by the Maxwell-Garnett mixing rule. © 2014 Optical Society of America. Source

Chenakin S.P.,Free University of Colombia | Chenakin S.P.,Ukrainian Academy of Sciences | Melaet G.,Free University of Colombia | Szukiewicz R.,Free University of Colombia | Kruse N.,Free University of Colombia
Journal of Catalysis | Year: 2014

X-ray photoelectron spectroscopy (XPS) was employed to study the changes in the surface composition and electronic structure of a TiO2-promoted Pd/SiO2 catalyst following methane oxidation under lean-burn conditions (up to 600 C) and SO2 treatment at 350 C. Overnight exposure of the activated catalyst to SO2 was found to cause the formation of a layer of palladium sulfate and sulfate/sulfite species on the support surface, leading to its deactivation. A single cycle of methane combustion over the SO2-treated catalyst gave rise to its reactivation due to the effective decomposition of Pd sulfate and desorption of SO2 at relatively low temperatures. In the stabilized and restored states, the catalyst exhibited a high and stable activity, had the largest proportion of metallic versus oxidic palladium species, a high density of Pd 4d states near the Fermi level, and the smallest extent of surface hydroxylation. The catalytic reaction over an as-prepared or SO2-treated catalyst was revealed to cause a partial and reversible 'encapsulation' of Pd particles by TiOx suboxide moieties from the mixed oxide support. The encapsulation resulting from strong metal-support interaction was enhanced by the SO2 treatment of the Pd/(SiO2 + 10 wt% TiO 2) catalyst. © 2014 Elsevier Inc. All rights reserved. Source

Larger L.,University of Franche Comte | Penkovsky B.,University of Franche Comte | Penkovsky B.,National University of Kyiv-Mohyla Academy | Maistrenko Y.,University of Franche Comte | Maistrenko Y.,Ukrainian Academy of Sciences
Physical Review Letters | Year: 2013

Time-delayed systems are found to display remarkable temporal patterns the dynamics of which split into regular and chaotic components repeating at the interval of a delay. This novel long-term behavior for delay dynamics results from strongly asymmetric nonlinear delayed feedback driving a highly damped harmonic oscillator dynamics. In the corresponding virtual space-time representation, the behavior is found to develop as a chimeralike state, a new paradigmatic object from the network theory characterized by the coexistence of synchronous and incoherent oscillations. Numerous virtual chimera states are obtained and analyzed, through experiment, theory, and simulations. © 2013 American Physical Society. Source

In recent years, nonalcoholic fatty liver disease is regarded as an independent risk factor for cardiovascular events. The refinement of traditional and non-traditional cardiovascular risk factors in patients with nonalcoholic fatty liver disease is relevant. Therefore, we studied the influence of the adiponectin receptor 2 polymorphic gene and metabolic disorders on the cardiovascular risk patients with nonalcoholic fatty liver disease. The study involved 230 patients with nonalcoholic fatty liver disease. Study results showed association between adiponectin receptor 2 gene polymorphism and development of cardiovascular risk in patients with nonalcoholic fatty liver disease. The results on distribution of genotypes of adiponectin receptor 2 (rs1044471) polymorphism showed association with the degree of cardiovascular risk. Significant differences when comparing the genotypes adiponectin receptor 2 rs767870 in the studied sample depending on the cardiovascular risk were not identified. It was shown that adiponectin receptor 2 rs1044471 CT genotype carriers compared with carriers of TT genotype had potentially greater cardiovascular risk. In nonalcoholic fatty liver disease patients, carriers of adiponectin receptor 2 CT genotype, the proatherogenic lipid profile and significant increase of the intima-media thickness were observed on the background of hypoadiponectinemia. The obtained results confirm the influence of both metabolic phenotype and genetic factors on the cardiovascular risk in patients with nonalcoholic fatty liver disease. This is probably mediated by the effects of adiponectin receptors in the liver leading to genetic variation in the adiponectin receptor 2 locus and influencing the expression levels of adiponectin receptor 2 and/or their functions. Source

Panfilov A.S.,Ukrainian Academy of Sciences
Low Temperature Physics | Year: 2015

The construction and operating principle of a pendulum magnetometer for measuring the magnetic susceptibility of solids under high gas pressures are described. This device is distinctive in having the pendulum mounted directly in the high pressure chamber. Experimental plots of the susceptibility of the compound V4S9Br4 as a function of pressure up to 2 kbar at temperatures of 60-300 K are presented as an example of the use of the magnetometer. © 2015 AIP Publishing LLC. Source

Zvyagin A.A.,Max Planck Institute For Physik Komplexer Systeme | Zvyagin A.A.,Ukrainian Academy of Sciences
Physical Review Letters | Year: 2013

Several scenarios for the realization of edge Majorana modes in quantum chain systems, spin chains, chains of Josephson junctions, and chains of coupled cavities in quantum optics, are considered. For all these systems excitations can be presented as superpositions of a spinless fermion and a hole, characteristic of a Majorana fermion. We discuss the features of our exact solution with respect to possible experiments, in which edge Majorana fermions can be directly observed when studying magnetic, superconducting, and optical characteristics of such systems. © 2013 American Physical Society. Source

Heepe L.,University of Kiel | Kovalev A.E.,University of Kiel | Filippov A.E.,University of Kiel | Filippov A.E.,Ukrainian Academy of Sciences | Gorb S.N.,University of Kiel
Physical Review Letters | Year: 2013

Nature has successfully evolved the mushroom-shaped contact geometry in many organisms in order to solve the attachment problem. We studied the detachment process of individual bioinspired artificial mushroom-shaped adhesive microstructures (MSAMSs) resolving the failure dynamics at high spatiotemporal resolution. The experimental data provide strong evidence for a homogeneous stress distribution in MSAMS, which was recently proposed. Our results allow us to explain the advantage of such contact geometry and provide a suggestion for the widely observed mushroom-shaped contact geometry. © 2013 American Physical Society. Source

Savelyev A.,Ukrainian Academy of Sciences | Savelyev A.,University of North Carolina at Chapel Hill
Physical Chemistry Chemical Physics | Year: 2012

Numerous theoretical and experimental studies disagree on the impact of surrounding mobile ions on DNA conformational flexibility at high salt content. Specifically, it is not clear how the DNA persistence length varies when concentration of monovalent mobile ions is increased beyond the physiological value of ∼0.1 M. In the present Communication we address this biologically important issue computationally by means of molecular dynamics simulations. We utilize our recently developed chemically accurate coarse-grained model for the double-stranded DNA with explicit mobile ions. We find that in a range of moderate-to-high ionic concentrations, ∼0.1-1 M, DNA persistence length drops noticeably by ∼25%. Our results contradict some experimental works and the celebrated theory of Odijk, Skolnick and Fixman (Skolnick et al., Macromolecules, 1977, 10, 944), suggesting a negligible variation of DNA persistence length at these concentrations. On the other hand, our findings are in near quantitative agreement with a number of other theoretical and experimental studies. Combined with our recent work on elucidating the role of elastic and electrostatic effects in maintaining DNA shape, the results reported here may indicate that conceptually new understanding of DNA rigidity needs to be developed. © 2012 the Owner Societies. Source

Gorobetsa Y.I.,Ukrainian Academy of Sciences | Kulish V.V.,Kharkiv Polytechnic Institute
Low Temperature Physics | Year: 2015

Dipole-exchange spin waves in nanotubes composed of uniaxial ferromagnets are studied. An equation for the magnetic potential of linear spin waves in uniaxial "easy plane" ferromagnets is obtained in the magnetostatic approximation taking into account magnetic dipole-dipole interactions, exchange interactions, and anisotropy effects. A solution is found for this equation and a dispersion relation for these types of spin waves is obtained. The dependence of the spin wave frequency on the total wave number is found for the case of a thin nanotube. An expression is derived for the transverse wave number spectrum. © 2015 AIP Publishing LLC. Source

Kuzovlev Yu.E.,Ukrainian Academy of Sciences
Physics-Uspekhi | Year: 2015

While ubiquitous at all levels of organization in nature, including in nanotechnology, low-frequency 1/f noise is not yet understood. A possible reason is the unjustified application of probability theory concepts, primarily that of independence, to random physical phenomena. We show that in the framework of statistical mechanics, no medium can impart a definite diffusivity and mobility to a particle that performs random walk through it, which gives rise to flicker fluctuations in these properties. A universal source of 1/f noise in manyparticle systems in this example is a dependence of the time behavior of any particular relaxation or transport process on the details of the initial microstate of the system as a whole. © 2015 Uspekhi Fizicheskikh Nauk, Russian Academy of Sciences. Source

Boguslavskii L.Z.,Ukrainian Academy of Sciences
Surface Engineering and Applied Electrochemistry | Year: 2010

The possibility of the synthesis of nanocarbons upon the high-frequency electrodischarge effect with various types of discharges in gas media is theoretically estimated by the volume, corona, spark, and arc. The experimental verification showed the possibility of the synthesis of nanocarbon with 10-45 nm sizes of the particles. © 2010 Allerton Press, Inc. Source

Tishkovets V.P.,Ukrainian Academy of Sciences | Mishchenko M.I.,NASA
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2010

Although the note by Hapke and Nelson has virtually no relevance to our original publication, it contains a number of statements that are misleading and/or wrong. We, therefore, use this opportunity to dispel several profound misconceptions that continue to hinder the progress in remote sensing of planetary surfaces. Source

Vorobyov E.I.,University of Vienna | Vorobyov E.I.,Southern Federal University | Zakhozhay O.V.,Ukrainian Academy of Sciences | Dunham M.M.,Yale University
Monthly Notices of the Royal Astronomical Society | Year: 2013

Using numerical hydrodynamic simulations, we study the gravitational fragmentation of an unstable protostellar disc formed during the collapse of a pre-stellar core with a mass of 1.2M⊙. The forming fragments span a mass range from about a Jupiter mass to very low mass protostars and are located at distances from a few tens to a thousand au, with a dearth of objects at ≲100 au. We explore the possibility of observational detection of the fragments in discs viewed through the outflow cavity at a distance of 250 pc. We demonstrate that one hour of integration time with the Atacama Large Millimeter/sub-millimeter Array (ALMA) is sufficient to detect the fragments with masses as low as 1.5MJup at orbital distances up to 800 au from the protostar. The ALMA resolution sets the limit on the minimum orbital distance of detectable fragments. For the adopted resolution of our simulated ALMA images of 0.1 arcsec, the fragments can be detected at distances down to 50 au. At smaller distances, the fragments usually merge with the central density peak. The likelihood for detecting the fragments reduces significantly for a lower resolution of 0.5 arcsec. Some of the most massive fragments, regardless of their orbital distance, can produce characteristic peaks at ̃5 μm and hence their presence can be indirectly inferred from the observed spectral energy distributions of protostars. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

Kondrashova N.N.,Ukrainian Academy of Sciences
Monthly Notices of the Royal Astronomical Society | Year: 2013

The results of the study of the thermodynamical parameters and the magnetic field in the solar photosphere during the solar microflare on 2009 July 4 in the active region NOAA 11024 are presented. The analysis is based on the observations with the French-Italian telescope THEMIS (Heliographic Telescope for the Study of the Magnetism and Instabilities on the Sun), operated on the island of Tenerife in the Spanish Observatorio del Teide of the Instituto de Astrofisica de Canarias in the multiline spectropolarimetric mode. The high-resolution Stokes I, Q, U and V profiles of 10 photospheric lines are used for the modelling. Semi-empirical models are derived from the inversion with Stokes Inversion based on Response functions code, developed by Ruiz Cobo and del Toro Iniesta. The models include two components: a thin magnetic flux tube and its non-magnetic surroundings. The temporal variations in all photospheric parameters are revealed during the microflare. The magnetic field strength increased from 800 to 1200 G during the onset phase of the microflare. The inferred flux tube models show the temperature enhancement in the photospheric layers relative to the quiet-Sun model atmosphere at the onset of the flare. The temperature inhomogeneities are found in the inferred atmosphere at the end of the microflare. © 2013 The Author. Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

Saprykina M.N.,Ukrainian Academy of Sciences
Journal of Water Chemistry and Technology | Year: 2012

A new design of the electrocoagulation apparatus consisting of an inert anode and cathode made of stainless steel was developed. The formation of a coagulant takes place due to the corrosion of ferrous plates located in the anode plane. The following optimum parameters for the operation of the apparatus were defined: current density-21 mA/cm2, current strength-60 mA, area of ferrous plates-3 cm2. The application of this apparatus makes possible to convert efficiently Fe2+ to Fe3+ allowing the user to reduce the consumption of coagulant and remove to the maximum extent contaminants including micromycetes from water. © 2012 Allerton Press, Inc. Source

Zvyagin A.A.,TU Dresden | Zvyagin A.A.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We propose an analytical ansatz, using which the ordering temperature of a quasi-one-dimensional (quasi-1D) antiferromagnetic (AF) system (weakly coupled quantum spin-1/2 chains) in the presence of the external magnetic field is calculated. The field dependence of the critical exponents for correlation functions of 1D subsystems plays a very important role. It determines the region of possible re-entrant phase transition, governed by the field. It is shown how the quantum-critical point between two phases of the 1D subsystem, caused by spin-frustrating next-nearest neighbor and multispin ringlike exchanges, affects the field dependence of the ordering temperature. Our results qualitatively agree with the features, observed in experiments on quasi-1D AF systems. © 2010 The American Physical Society. Source

Borovik A.A.,Ukrainian Academy of Sciences
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2010

We measure the full autoionization cross section of lithium atoms excited by electrons in the energy range from the first autoionization threshold at 56.39 to 600 eV. Data are obtained by determining the total intensity of electron spectrum of autoionization states 1sn 1 l 1 n 2 l 2 detected at the "magic" observation angle of 54.7°. The cross section behavior is characterized by a sharp increase to a maximum value of 1.7 × 10 -18 cm 2 in the energy interval of 56.4-60 eV and a subsequent monotonic drop to a value of 10 -18 cm 2 at 600 eV. We have discovered a "thin" cross section structure that reflects the presence of strong resonances of Li - ions in the near-threshold area of excitation of the lowest energy autoionization states (1s2s2)2S, (1s2s2p) 4 P, 1s(2s2p 3 P) 2 P), and 1s(2s2p 1 P) 2 P. We have established that the contribution of autoionization to the absolute cross section of single ionization of lithium atoms does not exceed 4%. We perform a comparative analysis of the data with analogous data for potassium and cesium atoms. © 2010 Pleiades Publishing, Ltd. Source

Kordyum E.L.,Ukrainian Academy of Sciences
Plant Biology | Year: 2014

A short overview on the effects of real and simulated microgravity on certain cell components and processes, including new information obtained recently, is presented. Attention is focused on the influence of real and simulated microgravity on plant cells that are not specialised to gravity perception and on seed formation. The paper considers the possibility of full adaptation of plants to microgravity, and suggests some questions for future plant research in order to make decisions on fundamental and applied problems of plant space biology. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands. Source

Raichev O.E.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The influence of electron-phonon interaction on magnetotransport in two-dimensional electron systems under microwave irradiation is studied theoretically. Apart from the phonon-induced resistance oscillations which exist in the absence of microwaves, the magnetoresistance of irradiated samples contains oscillating contributions due to electron scattering on both impurities and acoustic phonons. The contributions due to electron-phonon scattering are described as a result of the interference of phonon-induced and microwave-induced resistance oscillations. In addition, microwave heating of electrons leads to a special kind of phonon-induced oscillations. The relative strength of different contributions and their dependence on parameters are discussed. The interplay of numerous oscillating contributions suggests a peculiar magnetoresistance picture in high-mobility layers at the temperatures when electron-phonon scattering becomes important. © 2010 The American Physical Society. Source

Pustovit V.N.,Ukrainian Academy of Sciences
Physica B: Condensed Matter | Year: 2010

We study theoretically radiative and nonradiative decay of a single molecule near small gold nanoparticle. The local field enhancement leads to an increased radiative decay rate while the energy transfer from molecule to optically inactive electronic states in nanoparticle results in a decrease in the fluorescence quantum efficiency for small molecule-nanoparticle distances. We performed a DFT-TDLDA calculation of both the enhancement and the quenching for small nanometersized gold nanoparticles. We found that in close proximity to the surface, the nonradiative decay rate is dominated by generation of electron-hole pairs out of the Fermi sea resulting in a significantly lower quantum efficiency as compared to that obtained from electromagnetic calculations. For large distances, the efficiency is maximal for molecule polarized normal to the surface, whereas for small distances it is maximal for parallel orientation. © 2009 Elsevier B.V. All rights reserved. Source

Ahn H.-Y.,University of Central Florida | Fairfull-Smith K.E.,Queensland University of Technology | Morrow B.J.,Queensland University of Technology | Lussini V.,Queensland University of Technology | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

A range of varying chromophore nitroxide free radicals and their nonradical methoxyamine analogues were synthesized and their linear photophysical properties examined. The presence of the proximate free radical masks the chromophore's usual fluorescence emission, and these species are described as profluorescent. Two nitroxides incorporating anthracene and fluorescein chromophores (compounds 7 and 19, respectively) exhibited two-photon absorption (2PA) cross sections of approximately 400 G.M. when excited at wavelengths greater than 800 nm. Both of these profluorescent nitroxides demonstrated low cytotoxicity toward Chinese hamster ovary (CHO) cells. Imaging colocalization experiments with the commercially available CellROX Deep Red oxidative stress monitor demonstrated good cellular uptake of the nitroxide probes. Sensitivity of the nitroxide probes to H 2O 2-induced damage was also demonstrated by both one- and two-photon fluorescence microscopy. These profluorescent nitroxide probes are potentially powerful tools for imaging oxidative stress in biological systems, and they essentially "light up" in the presence of certain species generated from oxidative stress. The high ratio of the fluorescence quantum yield between the profluorescent nitroxide species and their nonradical adducts provides the sensitivity required for measuring a range of cellular redox environments. Furthermore, their reasonable 2PA cross sections provide for the option of using two-photon fluorescence microscopy, which circumvents commonly encountered disadvantages associated with one-photon imaging such as photobleaching and poor tissue penetration. © 2012 American Chemical Society. Source

Brykov V.,Ukrainian Academy of Sciences
Microgravity Science and Technology | Year: 2011

Effects of clinorotation on the mitochondrial ultrastructure in cells of meristem, distal and central elongation zones of 3- and 5-day-old etiolated roots of pea seedling roots were studied. It was shown that mitochondria in cells of examined root growth zones revealed a different sensitivity to clinorotation. The ultrastructure of mitochondria in the meristem and central elongation zone cells did not substantially change in comparison with stationary control. At the same time, changes in the mitochondrial ultrastructure in cells of the distal elongation zone under clinorotation were observed, namely: decrease in the size of mitochondria, as well as increase in both matrix electron density and crista volume. Such changes in the mitochondrial ultrastructure under clinorotation are supposed to display the rearrangements of energy metabolism in cells of the distal elongation zone in these conditions. © 2010 Springer Science+Business Media B.V. Source

Romanyuk R.R.,Ukrainian Academy of Sciences
Inorganic Materials | Year: 2013

This paper examines the effect of Bi doping on the short-range order in amorphous (GeSe)1 - x Bi x (0 ≤ x ≤ 0.15) films and their electrical properties. Electron diffraction results demonstrate that the structure of the films can be described by a model typical of GeSe-Bi 2Se3 solid solutions. Bi doping changes the charge transport mechanism and leads to type inversion in the amorphous (GeSe) 1 - x Bi x films. © 2013 Pleiades Publishing, Ltd. Source

Luzanov A.V.,Ukrainian Academy of Sciences
Journal of Structural Chemistry | Year: 2014

The self-consistency schemes previously developed in J. Struct. Chem., 30, N 5, p. 3 (1986) are shown to belong to the class of semi-canonical orbital schemes. In the derivation they explicitly involve only a part of canonical Koopmans orbitals in the iteration process. In particular, within the restricted Hartree-Fock method for a non-degenerate case a semi-canonical variational scheme based on the matrix elements of the unrestricted Hartree-Fock method is studied. Errors present in the above mentioned work in the description of the scheme of a varied open shell are corrected. A possible generalization for the case of Roothaan type degeneration is proposed and specific examples of low-spin and high-spin states with a violated Aufbau filling principle are considered. © 2014 Pleiades Publishing, Ltd. Source

Shvets A.,Ukrainian Academy of Sciences | Hayakawa M.,University of Electro - Communications
Surveys in Geophysics | Year: 2011

The monitoring of global lightning activity and its spatial and temporal variations is known to be very essential for the study of global warming, the subject of greatest concern to human beings on planet Earth today. As a method of remote sensing for the global lightning distribution, we have proposed an inverse problem by using the data of natural electromagnetic noise in the ELF (extremely low frequency) Schumann resonance (SR) band observed simultaneously at a few stations around the world. The fundamentals of this inversion problem (or ELF tomography) to the SR data have been presented and the first attempt to deduce the global lightning distribution by means of the real SR data has been performed, which has indicated a possibility of snapshots of well-known thunderstorm centers on the globe. This ELF tomography consists of two stages. The first stage is the inversion of the ELF field power spectra to the distribution of lightning intensity by distance relative to an observation point. The obtained distance profiles of intensity of sources at a few stations are used as tomographic projections for reconstructing a spatial distribution of sources in the second stage. Maps of the global lightning distributions constructed by the result of inversions of ELF background field spectra obtained from three stations around the world show that the most active regions vary meridionally on the diurnal time scale being connected mainly with continental areas in the tropics. We do hope that this kind of inversion method to multi-stationed ELF data will be of great importance in the future. © 2011 Springer Science+Business Media B.V. Source

Sizonenko Y.V.,Ukrainian Academy of Sciences
Kinematics and Physics of Celestial Bodies | Year: 2012

We studied variations in the structure of plasma and dust tails of the C/2006 M4 (SWAN) comet during a long observation period (September-December 2006). We found sizes of grains ejected by the comet from the synchronic-syndynamic analysis of comet images. We calculated solar wind speed for high heliographic latitudes from calculations of the aberration angle of the comet plasma tail. Rapid changes in the calculated values of the solar wind speed are caused by its variable transversal component. © 2012 Allerton Press, Inc. Source

Milcho M.V.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2015

The easy-to-use and cost-efficient oscillators suitable for the submillimeter waveband and especially in its short-wave part are still a challenge to be solved. Though providing satisfactory results in the long-wave part of the submillimeter waveband, backward wave tubes (BWTs) are as good as inapplicable in its short-wave part. Available engineering methods are not capable of providing extremely thin high-current-density electron beams required for this waveband. Frequency multipliers are able to considerably mitigate such strict requirements to the electron beams. A klynotron-type oscillator can be used for electron beam bunching in the frequency multiplier. In the klynotron oscillator, a wide and comparatively thick sheet electron beam is directed at a small angle to the surface of the slow-wave structure and is partly dissipated on this surface. The output power provided by the klynotron exceeds that of a conventional BWT by several orders. This is a crucial condition for obtaining good (i.e., deep) bunching of an electron beam. Our goal is to investigate the process of dense electron bunching in klynotrontype oscillators and to clarify the conditions of its use for electron beam bunching in a frequency multiplier. In this paper, we analysed the electron bunching in the klynotron numerically, using our proprietary software, specially designed to take into account all specific features of the klynotron operating mode. Three-dimensional motion of electron was investigated in the finite focusing magnetic field. The numeral simulations revealed the effect of "layer-by-layer" bunching of the electron beam in a klynotron-type oscillator. The farther an electron layer is located from the surface of the slow-wave structure, the later electron bunching in that layer occurs. It was shown that by selecting the proper operation mode and the slope angle between of the focusing magnetic field and the comb surface one can obtain dense electron bunches in the part of the beam outside the klynotron slow-wave structure, where the second slow-wave structure should be located functioning as a power take-off. This can be considered as a proof that klynotrons can be used in the frequency multiplier engineering. © 2015 by Begell House, Inc. Source

Dutka V.A.,Ukrainian Academy of Sciences
Journal of Superhard Materials | Year: 2014

The paper presents a numerical model for infiltration of porous preforms of ceramic materials in the process of sintering. The mathematical model of infiltration is based on the Richards equation and Van Genuchten formulas describing permeability properties of the porous structure and the infiltrant. A finite-element method and stable implicit finite-difference time scheme are applied for discretization of the Richards equation. Based on the outcome of solving test problems, a comparison of the numerical results with the results obtained by other researchers and with the experimental data, the numerical model has been proved adequate. The paper provides some findings of computer modeling of infiltration of liquid silicon into porous silicon carbide preforms of various geometries and dimensions. © 2014 Allerton Press, Inc. Source

Luzanov A.V.,Ukrainian Academy of Sciences
Journal of Structural Chemistry | Year: 2014

It is shown that the numerical measure of effectively unpaired electrons Neff, proposed by Head-Gordon in 2003, is a particle-hole index: Neff is reduced to the average occupation of virtual particle-hole pairs. Specific π calculations of the Neff index provide a reasonable interpretation of the radicaloid character of the singlet ground state in complex conjugated systems. The results of the accurate π model (based on the total configuration interaction) and approximate approaches are compared. The coupled cluster method and various Hartree-Fock schemes (UHF and Löwdin EHF scheme) demonstrate an acceptable quantitative description of unpairing effects, UHF being favorable in simplicity of obtaining the measure of unpairing in megamolecules, such as graphene structures. The application of the known Yamaguchi index results in a rougher representation of the radical character of a system. © 2014 by Pleiades Publishing, Ltd. Source

Bekshaev A.,Odessa I I Mechnikov National University | Bliokh K.Y.,National University of Ireland | Soskin M.,Ukrainian Academy of Sciences
Journal of Optics | Year: 2011

We review optical phenomena associated with the internal energy redistribution which accompany propagation and transformations of monochromatic light fields in homogeneous media. The total energy flow (linear-momentum density, Poynting vector) can be divided into a spin part associated with the polarization and an orbital part associated with the spatial inhomogeneity. We give a general description of the internal flows in the coordinate and momentum (angular spectrum) representations for both nonparaxial and paraxial fields. This enables one to determine local densities and integral values of the spin and orbital angular momenta of the field. We analyse patterns of the internal flows in standard beam models (Gaussian, Laguerre-Gaussian, flat-top beam, etc), which provide an insightful picture of the energy transport. Emphasis is given to the singular points of the flow fields. We describe the spin-orbit and orbit-orbit interactions in the processes of beam focusing and symmetry breakdown. Finally, we consider how the energy flows manifest themselves in the mechanical action on probing particles and in the transformations of a propagating beam subjected to a transverse perturbation. © 2011 IOP Publishing Ltd. Source

Gladky A.V.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

The author considers the problem of numerical modeling and optimization of wave processes in inhomogeneous domains with imperfect contact conditions on the basis of Schrödinger parabolic wave equation. The optimality criterion is formulated. The differential properties of the optimization problem are investigated. The numerical method is proposed for modeling and optimization of acoustic fields in inhomogeneous domains. © 2016 Springer Science+Business Media New York Source

Analysis of the influence of horse-keeping conditions by contamination of the environment (pastures, paddocks, and stalls) by the strongylid infective larvae (L 3) was carried out at various types of horse farms, hippodromes, and riding clubs in Ukraine. A total of 1,237 horses from three types of horse-keeping conditions were examined. Epidemiological studies of stall and grazing area (pasture and paddocks) contamination by L 3 were performed at hippodrome (stalled horse-keeping) and horse farms with stall/paddock-keeping and stall/pasture-keeping conditions. Grass and stall litter samples were examined by the Baermann procedure. It was found that horses of stall-keeping conditions had the lowest level of strongylid infection (prevalence 46.4-77.8%, average infection 25.6-92.9 eggs per gram of feces (EPG)) and lowest proportion of large strongyle L 3 in coprocultures (1.6-11.3%). Horses of stall/pasture-keeping conditions were the most infected (prevalence 95.1-100%, average infection 198.2-453.7 EPG), and the proportion of large strongyle L 3 was 17.3-24.7%. Strongyle L 3 were found in litter of all parts of individual stalls; areas at the stall center, "toilet", and entrance were the most contaminated. The highest L 3 number in stall litter was registered in summer. Contamination of permanent pasture grass by L 3 was notably lower than grass in paddocks (86.3-161.4 L 3/kg compared with 305.9-409.1 L 3/kg). The highest level of pasture grass contamination was observed in the middle of summer (July) - up 970.7 L 3/kg. The results obtained confirmed importance of environmental contamination in epidemiology of horse strongylidosis at various types of horse-keeping conditions. © Springer-Verlag 2012. Source

Kravets E.A.,Ukrainian Academy of Sciences
Russian Journal of Developmental Biology | Year: 2013

UV and gamma irradiation of barley seedlings induces an increase in the number of various pathologies in the male reproductive system of plants. The majority of cytological abnormalities are rather nonspecific. The main type of the observed pathologies of microsporogenesis is cytomixis, whose activation correlates with a callose hypersecretion in microsporocyte walls. A negative correlation between cytomixis and the sterility of microspores (in the case of gamma irradiation) or the sterility of mature pollen grains (in the case of UV-B irradiation) is revealed. It is supposed that cytomixis represents a kind of a premeiotic cell selection in plants characterized by an intraorganismic genetic heterogeneity (mosaics). The novelty of the idea is that the cytopathology that accompanies cytomixis is considered as a mechanism of the induced death of genetically imbalanced or nonrepairable cells, which is intended to keep the fertility of a male reproductive system. The activation of this mechanism has a threshold character. © 2013 Pleiades Publishing, Ltd. Source

Kruse N.,Free University of Colombia | Chenakin S.,Free University of Colombia | Chenakin S.,Ukrainian Academy of Sciences
Applied Catalysis A: General | Year: 2011

X-ray photoelectron spectroscopy (XPS) was employed to study the surface composition and electronic structure of Au/TiO2 catalysts in comparison with TiO2 (anatase) and to reveal time-dependent X-ray irradiation damage of the samples. The occurrence of Au nano-sized particles on a TiO2 support was found to result in a slight shift of Ti 2p core-level spectrum and in changes of the valence band and X-ray induced Auger spectra, compared to TiO2-only. It was shown that for different means of energy referencing the charge-corrected Au 4f7/2 binding energy in Au/TiO2 catalysts was 0.15-0.45 eV lower than that in pure bulk Au. Exposure to X-rays of Au/TiO2 catalysts and pure TiO2 caused a reduction of Ti 4+ oxidation state and desorption of oxygen from the surface. As a result, the surface chemical composition and electronic structure of the samples changed with time. The X-ray irradiation affected charge transfer processes in Au/TiO2 so that the pattern of X-ray induced damage in the Au-based catalyst turned out to be quite different from that in TiO 2, with some characteristics displaying the very opposite features. Decreasing of the Au 4f7/2 binding energy and concurrent increasing of the fraction of Ti3+ species observed in the beginning of X-ray irradiation of Au/TiO2 may be taken as direct evidence for charge transfer from oxygen vacancies created by irradiation to Au particles. © 2010 Elsevier B.V. All rights reserved. Source

Kravets V.G.,Ukrainian Academy of Sciences
Journal of Alloys and Compounds | Year: 2011

We present results on the photoluminescence and optical properties of SnOx nanocrystals as a function of their size. Samariums ions are incorporated in SnOx nanostructures to huge improve their photoluminescence efficiency. We have performed photoluminescent, ellipsometrical, atomic force microscopy, and structural studies of these nanocrystals and found them to be a direct semiconductor with a gap of ≈3.6 eV. The origin of the observed photoluminescence has been discussed. The doping of lanthanide atoms in semiconductor nanocrystals expands the range of possibilities offered by such materials, allowing them to be modified to meet specific requirements in electronic and optoelectronic applications. © 2011 Elsevier B.V. All rights reserved. Source

Reutskiy S.Y.,Ukrainian Academy of Sciences
Engineering Analysis with Boundary Elements | Year: 2016

The paper presents a new meshless numerical method for solving 2D steady-state heat conduction problems in anisotropic and inhomogeneous media. The coefficients of the governing PDEs are spatially dependent functions including the main operator part. The boundary conditions of a most general form for the temperature and the heat flux are considered. The key idea of the method is the use of the basis functions which satisfy the homogeneous boundary conditions of the problem. Each basis function used in the algorithm is a sum of a RBF and a special correcting function which is chosen to satisfy the homogeneous BC of the problem. The conical radial basis functions, the Duchon splines and the multiquadric RBFs are used in approximation of the PDE. This allows us to seek an approximate solution in the form which satisfies the boundary conditions of the initial problem with any choice of the free parameters. As a result we separate the approximation of the boundary conditions and the approximation of the PDE inside the solution domain. The numerical experiments are carried out for accuracy and convergence investigations. The comparison of the numerical results obtained in the paper with the exact solutions and with the data obtained with the use of other numerical techniques is performed. The numerical examples demonstrate that the present method is accurate, convergent, stable, and computationally efficient in solving this kind of problems. © 2016 Elsevier Ltd. All rights reserved. Source

Bachinskaya N.,Ukrainian Academy of Sciences | Hoerr R.,Dr. Willmar Schwabe Pharmaceuticals | Ihl R.,Geriatric Psychiatry Center
Neuropsychiatric Disease and Treatment | Year: 2011

Purpose: To examine the effects of Ginkgo biloba extract EGb 761® on neuropsychiatric symptoms of dementia. Patients and methods: Randomized, controlled, double-blind, multicenter clinical trial involving 410 outpatients with mild to moderate dementia (Alzheimer's disease with or without cerebrovascular disease, vascular dementia), scoring at least 5 on the Neuropsychiatric Inventory (NPI), with at least one item score of 3 or more. Total scores on the SKT cognitive test battery (Erzigkeit's short syndrome test) were between 9 and 23. After random allocation, the patients took 240 mg of EGb 761® or placebo once daily for a period of 24 weeks. Changes from baseline to week 24 in the NPI composite and in the SKT total score were the primary outcomes. The NPI distress score was chosen as a secondary outcome measure to evaluate caregivers' distress. Results: The NPI composite score improved by -3.2 (95% confidence interval -4.0 to -2.3) in patients taking EGb 761® (n = 202), but did not change (-0.9; 0.9) in those receiving placebo (n = 202), which resulted in a statistically significant difference in favor of EGb 761® (P, 0.001). Treatment with EGb 761® was significantly superior to placebo for the symptoms apathy/indifference, sleep/night-time behavior, irritability/lability, depression/dysphoria, and aberrant motor behavior. Caregivers' distress evaluation revealed similar baseline pattern and improvements. Conclusion: Treatment with EGb 761®, at a once-daily dose of 240 mg, was safe, effectively alleviated behavioral and neuropsychiatric symptoms in patients with mild to moderate dementia, and improved the wellbeing of their caregivers. © 2011 Bachinskaya et al. Source

Liu D.,CNRS Integrated Transformations of Renewable Matter | Lebovka N.I.,CNRS Integrated Transformations of Renewable Matter | Lebovka N.I.,Ukrainian Academy of Sciences | Vorobiev E.,CNRS Integrated Transformations of Renewable Matter
Food and Bioprocess Technology | Year: 2013

Treatments by high-voltage electrical discharges (HVED, needle-plate electrode geometry, U = 40 kV, tp ≈ 0.5 μs) and pulsed electric field (PEF, plate-plate electrode geometry, E = 5-40 kV/cm, tp ≈ 8.3 μs) were evaluated as tools for selective extraction of different intracellular components from the wine Saccharomyces cerevisiae (bayanus) yeasts in a 0.5% (w/w) aqueous suspension. The pulses in the form of damped oscillations and exponential decay were applied in HVED and PEF modes of treatment, respectively. The extraction efficiency results obtained using HVED and PEF techniques were compared with those for high-pressure homogenization technique. The HVED and PEF treatments always resulted in incomplete damage of yeast cells, though efficiency of HVED was higher than that of PEF. The high selectivity of extraction of ionic substances, proteins, and nucleic acids was demonstrated; e. g., electric pulse treatments at E = 40 kV/cm and N = 500 allowed extraction of ≈80% and ≈70% of ionic substances, ≈4% and ≈1% of proteins and ≈30% and ≈16% of nucleic acids in cases of HVED and PEF modes, respectively. © 2011 Springer Science+Business Media, LLC. Source

Kutsokon N.K.,Ukrainian Academy of Sciences
Cytology and Genetics | Year: 2011

The main advantages that could be obtained by poplar plantation production were described in this review. We also described the significance of poplars for industry and for solutions to ecological problems. Taking into consideration the results obtained by genetic engineering methods, we analyzed the trends in the improvement of the Populus phenotypes related to the resistance to biotic and abiotic stresses and herbicides, as well as to the modification of the wood quality (decreasing or modifing the lignin content), phytoremediation, plant growth acceleration, and changes in the plant morphology. © 2011 Allerton Press, Inc. Source

Davydov V.I.,Boise State University | Crowley J.L.,Boise State University | Schmitz M.D.,Boise State University | Poletaev V.I.,Ukrainian Academy of Sciences
Geochemistry, Geophysics, Geosystems | Year: 2010

High-precision ID-TIMS U-Pb zircon ages for 12 interstratified tuffs and tonsteins are used to radiometrically calibrate the detailed lithostratigraphic, cyclostratigraphic, and biostratigraphic framework of the Carboniferous Donets Basin of eastern Europe. Chemical abrasion of zircons, use of the internationally calibrated EARTHTIME mixed U-Pb isotope dilution tracer, and improved mass spectrometry guided by detailed error analysis have resulted in an age resolution of <0.05%, or ∼100 ka, for these Carboniferous volcanics. This precision allows the resolution of time in the Milankovitch band and confirms the long-standing hypothesis that individual high-frequency Pennsylvanian cyclothems and bundles of cyclothems into fourth-order sequences are the eustatic response to orbital eccentricity (∼100 and 400 ka) forcing. Tuning of the fourth-order sequences in the Donets Basin to the long-period eccentricity cycle results in a continuous age model for the Middle to Late Pennsylvanian (Moscovian-Kasimovian-Ghzelian) strata of the basin and their record of biological and climatic changes through the latter portion of the late Paleozoic Ice Age. Detailed fusulinid and conodont zonations allow the export of this age model to sections throughout Euramerica. Additional ages for Mississippian strata provide among the first robust radiometric calibration points within this subperiod and result in variable lowering of the base ages of its constituent stages compared to recent global time scale compilations. Copyright 2010 by the American Geophysical Union. Source

Kurgaev A.F.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

The author considers the disciplinary structure and the structure of the organizational management of science, hierarchy of the structure of reality, and questions of the evolution of nature and its components. The essence of the logic of the nature evolution process is shown to be the continuous creation and selection of ne w structures in the hierarchy of reality in the context of direct and reverse interlevel transmission of results of creation and also the inflow of matter, energy and/or information from the outside. It is obvious that it is this logic that must form the basis of the evolution of progressive intelligent systems and that the information support of scientific investigations must be adequate to the structure of the hierarchy of reality. © 2016 Springer Science+Business Media New York Source

Mishchuk N.A.,Ukrainian Academy of Sciences
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

The two-layer spherical cell model to describe the equilibrium electrical potential distribution between strongly charged particles in a monodisperse system is proposed. It is shown that the general solution of the Poisson-Boltzmann equation can be obtained by a combination of its solutions in the approximation of the excluded co-ions for the inner layer and in the Debye approximation for the outer one. The equation for the coordinate of the matching of solutions is proposed and analytically solved. It is shown that the correct choice of conditions for the matching provides a high precision of the solution in each layer. The article also analyzes the dependence of the characteristics of dispersed systems on the type of particle arrangement. © 2014 Elsevier B.V. Source

Proeschold T.,Scottish Association for Marine Science | Proeschold T.,University of Vienna | Darienko T.,Ukrainian Academy of Sciences | Silva P.C.,University of California at Berkeley | And 2 more authors.
Environmental Microbiology | Year: 2011

Symbiosis of green algae with protozoa and invertebrates has been studied for more than 100 years. Endosymbiotic green algae are widely distributed in ciliates (e.g. Paramecium, Stentor, Climacostomum, Coleps, Euplotes), heliozoa (e.g. Acanthocystis) and invertebrates (e.g. Hydra, Spongilla), and have traditionally been identified as named or unnamed species of Chlorella Beij. or Zoochlorella K. Brandt or referred to as Chlorella-like algae or zoochlorellae. We studied 17 strains of endosymbionts isolated from various hosts and geographical localities using an integrative approach (nuclear encoded small subunit and internal transcribed spacer regions of rRNA gene sequences including their secondary structures, morphology, physiology and virus sensitivity). Phylogenetic analyses have revealed them to be polyphyletic. The strains examined belong to five independent clades within the Trebouxiophyceae (Choricystis-, Elliptochloris-, Auxenochlorella- and Chlorella-clades) and Chlorophyceae (Scenedesmus-clade). The most studied host organism, Paramecium bursaria, harbours endosymbionts representing at least five different species. On the basis of our results, we propose a taxonomic revision of endosymbiotic 'Chlorella'-like green algae. Zoochlorella conductrix K. Brandt is transferred to Micractinium Fresen. and Zoochlorella parasitica K. Brandt to Choricystis (Skuja) Fott. It was shown that Choricystis minor (Skuja) Fott, the generitype, is a later heterotypic synonym of Choricystis parasitica (K. Brandt) comb. nov. A new species, Chlorella heliozoae, is proposed to accommodate the endosymbiont of Acanthocystis turfacea. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd. Source

Konstantinov D.,Okinawa Institute of Science and Technology | Monarkha Y.,Ukrainian Academy of Sciences | Kono K.,RIKEN
Physical Review Letters | Year: 2013

The experimental observation of the strong Coulombic effect on magneto-oscillations of the photoconductivity of surface electrons in liquid helium is reported. The observed broadening of the oscillations and shifts in positions of conductivity extrema with increasing electron density are in good agreement with the linear transport theory, which takes into account an internal electric field of fluctuational origin. These results provide important evidence for identification of the mechanism of the oscillations and zero-resistance states developed in their minima. © 2013 American Physical Society. Source

Chernyshuk S.B.,Ukrainian Academy of Sciences | Chernyshuk S.B.,NASU Bogolyubov Institute for Theoretical Physics | Lev B.I.,NASU Bogolyubov Institute for Theoretical Physics
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

The theory of elastic interaction of micrometer-sized axially symmetric colloidal particles immersed into confined nematic liquid crystal has been proposed. General formulas are obtained for the self-energy of one colloidal particle and interaction energy between two particles in arbitrary confined nematic liquid crystals with strong anchoring condition on the bounding surfaces. Particular cases of dipole-dipole interaction in the homeotropic and planar nematic cell with thickness L are considered and found to be exponentially screened on far distances with decay length λdd = L π. It is predicted that bounding surfaces in the planar cell crucially change the attraction and repulsion zones of usual dipole-dipole interaction. As well it is predicted that the decay length in quadrupolar interaction is two times smaller than for the dipolar case in the homeotropic cell. © 2010 The American Physical Society. Source

Lisovsky A.F.,Ukrainian Academy of Sciences
Journal of Superhard Materials | Year: 2013

Papers on theoretical and experimental investigations into the formation of a refractory skeleton in composite materials have been analyzed. It has been shown that the critical parameters that describe the refractory skeleton are the contiguity of particles and dihedral angle. In the theory of the formation of a refractory skeleton certain results have been achieved in the establishing of interrelationship between the values of dihedral angle, contiguity, concentration of phases, and the conditions for the skeleton formation. The composition and structure of interphase boundaries of the refractory skeleton have been described and the thickness of the particles contact zone has been substantiated. Various technologies that allow one to actively influence the formation of the refractory skeleton have been considered and ways of the further investigations in the field have been suggested. Original Russian Text © G.S. Oleinik, 2013. Source

Kovalchenko A.M.,Ukrainian Academy of Sciences
Journal of Superhard Materials | Year: 2013

Theoretical and experimental studies of the ductile mode of cutting brittle materials (semiconductors, ceramics, and glass) have been considered. The ductile mode of cutting has been based on the implementation of high-pressure-induced phase transformations in a material machined that followed by a cutting of a transformed amorphous layer, which makes it possible to avoid cracking. Publications on studies of phase transitions in brittle materials in the course of the indentation, scratching, friction, and cutting have been reviewed. It has been shown that the cutting depth, cutting edge radius of a tool, chip thickness, tool cutting edge inclination, and crystallographic orientation of a material machined and diamond tool as well as a type of lubricoolant are the decisive factors in implementing the ductile mode of cutting © 2013 Allerton Press, Inc. Source

Avramov K.V.,Ukrainian Academy of Sciences | Avramov K.V.,Kharkiv Polytechnic Institute | Mikhlin Y.V.,Kharkiv Polytechnic Institute
Applied Mechanics Reviews | Year: 2013

This paper is an extension of the previous review, done by the same authors (Mikhlin, Y., and Avramov, K. V., 2010, "Nonlinear Normal Modes for Vibrating Mechanical Systems. Review of Theoretical Developments," ASME Appl. Mech. Rev.,63(6), p. 060802), and it is devoted to applications of nonlinear normal modes (NNMs) theory. NNMs are typical regimes of motions in wide classes of nonlinear mechanical systems. The significance of NNMs for mechanical engineering is determined by several important properties of these motions. Forced resonances motions of nonlinear systems occur close to NNMs. Nonlinear phenomena, such as nonlinear localization and transfer of energy, can be analyzed using NNMs. The NNMs analysis is an important step to study more complicated behavior of nonlinear mechanical systems.This review focuses on applications of Kauderer-Rosenberg and Shaw-Pierre concepts of nonlinear normal modes. The Kauderer-Rosenberg NNMs are applied for analysis of large amplitude dynamics of finite-degree-of-freedom nonlinear mechanical systems. Systems with cyclic symmetry, impact systems, mechanical systems with essentially nonlinear absorbers, and systems with nonlinear vibration isolation are studied using this concept. Applications of the Kauderer-Rosenberg NNMs for discretized structures are also discussed. The Shaw-Pierre NNMs are applied to analyze dynamics of finite-degree-of-freedom mechanical systems, such as floating offshore platforms, rotors, piece-wise linear systems. Studies of the Shaw-Pierre NNMs of beams, plates, and shallow shells are reviewed, too. Applications of Shaw-Pierre and King-Vakakis continuous nonlinear modes for beam structures are considered. Target energy transfer and localization of structures motions in light of NNMs theory are treated. Application of different asymptotic methods for NNMs analysis and NNMs based model reduction are reviewed. Copyright © 2013 by ASME. Source

Satoh T.,University of Tokyo | Satoh T.,Japan Science and Technology Agency | Terui Y.,University of Tokyo | Moriya R.,University of Tokyo | And 8 more authors.
Nature Photonics | Year: 2012

In future spintronics it is anticipated that spin waves will function as unique information carriers that are free from Joule heating. Directional control of spin-wave emission has been desired for the realization of switching devices. Here, we propose a promising technique that makes use of a spatially shaped light pulse with circular polarization. Focusing this light pulse on a magnet generates spin waves via the inverse Faraday effect. Moreover, the wavenumber distribution of the spin waves is determined by the spatial intensity distribution of the light spot. We demonstrate the principle of this technique both theoretically and experimentally. We successfully control the direction of the energy flow by shaping the light spot into an ellipse, with its major axis parallel or perpendicular to the magnetic field. Our findings will open up the possibility of fast and arbitrary synthesis of spin-wave patterns by using a more sophisticated light-shaping technique, for example using a computer-generated hologram. © 2012 Macmillan Publishers Limited. All rights reserved. Source

Yakovkin I.N.,Ukrainian Academy of Sciences
European Physical Journal B | Year: 2012

The electronic structures of Au monolayers on the Ru(0001) and graphene-coated Ru(0001) surfaces have been calculated by DFT method using the supercell (repeated-slab) approach. The local densities of states (LDOS) and band structures of the monolayer and bilayer Au films adsorbed on the graphene/Ru(0001) and those of free hexagonal Au layers are found to be very similar. This result indicates that the monolayer graphene almost completely screens the Au layers from the Ru(0001) substrate surface, so that electronic properties of Au films adsorbed on graphene are determined predominantly by the electronic structure of the Au adlayers, essentially independent on the electronic structure of the substrate surface. © 2012 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg. Source

Bazaliy Y.B.,University of South Carolina | Bazaliy Y.B.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Planar spin transfer devices with dominating easy-plane anisotropy can be described by an effective one-dimensional equation for the in-plane angle. Such a description provides an intuitive qualitative understanding of the magnetic dynamics. We give a detailed derivation of the effective planar equation and use it to describe magnetic switching in devices with tilted polarizer. © 2012 American Physical Society. Source

The following four species of moths are recorded for the first time: Kessleria saxifragae (Stainton, 1868) and Paradoxus osyridellus Stainton, 1869 (Yponomeutidae) - from Ukraine; Argyresthia communana Moriuti, 1969 (Argyresthiidae) - from Russia; Ypsolopha albiramella (Mann, 1861) (Ypsolophidae) - from Mongolia. For two rare species which are Argyresthia kurenzovi Gershenson, 1988 (Argyresthiidae) and Pseudoplutella porrectella (Linnaeus, 1758) (Plutellidae) new finds in Russia are noted. © 2016 Z. S. Gershenson, published by De Gruyter Open 2016. Source

Korneyev S.V.,Ukrainian Academy of Sciences
Vestnik Zoologii | Year: 2016

While revising the Western Palaearctic species of Tephritis, the synonymy is revealed as follows: T. conyzifoliae Merz, 1992 = T. academica Bassov & Tolstoguzova, 1994, syn. n. = T. nartshukovi Bassov & Tolstoguzova, 1994, syn. n. = T. epicrepis Shcherbakov, 2001, syn. n. Tephritis angustipennis (Loew, 1844) is shown to be the senior synonym of T. ptarmicae Hering, 1935, syn. n. Examination of the holotype Tephritis kukunoria Hendel, 1927 shows it to belong in Trupanea Schrank, 1795, and the following synonymy is established: Trupanea kukunoria (Hendel, 1927), comb. n. = Trupanea pterostigma Wang, 1996, syn. n. With new records from Kazakhstan and Kyrgyzstan, T. conyzifoliae is shown to be a widespread species with distribution from West Europe to Siberia. T. angustipennis is recorded from Ukraine for the first time. Lectotypes of T. angustipennis (Loew, 1844) and T. ptarmicae Hering, 1935 are designated. © 2016 S. V. Korneyev, published by De Gruyter Open 2016. Source

Korneyev V.A.,Ukrainian Academy of Sciences
Vestnik Zoologii | Year: 2016

In addition to Toxurini and Pyrgotini, two monotypic tribes are described in the subfamily Pyrgotinae: Prodalmanniini, originally named and established by Aczél (1956) without detailed description or justification, and Toxopyrgotini trib. n. The type species of the type genera are redescribed and illustrated. © 2016 V. A. Korneyev, published by De Gruyter Open 2016. Source

Metlov L.S.,Ukrainian Academy of Sciences
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

An alternative form of kinetic equations, involving the internal and free energies symmetrically, has been derived in the framework of the theory of vacancies. Dynamical nature of irreversible phenomena during formation and motion of defects (dislocations) has been analyzed by a computer experiment. Results of this simulation are then extended into a thermodynamic identity, involving the law of conservation of energy at interaction with an environment (the first law of thermodynamics) and the law of energy transformation in the internal degrees of freedom (relaxation). This identity is compared to the analogous Jarzynski identity. The approach is illustrated by simulation of processes during severe plastic deformation; the Rybin kinetic equation for this case has been derived. © 2010 The American Physical Society. Source

Zvyagin A.A.,Max Planck Institute For Physik Komplexer Systeme | Zvyagin A.A.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The characteristics of the nuclear magnetic resonance (NMR), the contributions to the spin-lattice relaxation rate, and Knight shift of the resonance position are calculated exactly for a model spin-1/2 XY chain with the magnetic impurity. It is shown that the deviations of the impurity's coupling to the chain and the effective impurity's g factor from the values in the host spin chain yield special features in the temperature and magnetic field behavior for these NMR characteristics. The role of impurity-induced local levels in the NMR low-energy spin dynamics of spin chains is determined. © 2012 American Physical Society. Source

Zaichenko N.V.,Ukrainian Academy of Sciences
Russian Journal of Biological Invasions | Year: 2015

The parasite fauna of Amur sleeper was investigated in three water bodies of Kyiv oblast. Sixteen species of parasites and forms not identified to species level, one of which is Gyrodactylus perccotti, a speciesspecific representative of the parasite fauna of sleeper from the native range, were revealed. Ciliates of the genus Trichodina were dominant in all water bodies under study, whose maximum level of invasion in some water bodies reached 100% and 1500 spec./org. The majority of the presented parasite species are widespread in water bodies of Europe and Asia, without restricted host specificity. © 2015, Pleiades Publishing, Ltd. Source

Sapaty P.S.,Ukrainian Academy of Sciences
Lecture Notes in Electrical Engineering | Year: 2011

We have been witnessing numerous world crises and disasters-from ecological to military to economic, with global dynamics likely to be increasing further. The paper highlights known holistic and gestalt principles mainly used for a single brain, extending them to any distributed systems which may need high integrity and performance in reaction to unpredictable situations. A higher organizational layer is proposed enabling any distributed resources to behave as an organism having global "consciousness" and pursuing global goals. This "over-operability" layer is established by implanting into key system points the same copy of a universal intelligent module, which can communicate with other such modules and interpret collectively global mission scenarios presented in a special Distributed Scenario Language. The behavioral scenarios can be injected from any module, and then self-replicate, self-modify, and self-spread throughout the system to be managed, tasking individual components, activating distributed resources, and establishing runtime infrastructures supporting system's integrity. Existing and prospective applications are outlined and discussed, confirming the paradigm's suitability for solving world problems. © 2011 Springer-Verlag Berlin Heidelberg. Source

Guz A.N.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2014

The basic results of establishing the foundations of the mechanics of fracture of homogeneous materials compressed along cracks and inhomogeneous (composite) materials compressed along interface cracks are analyzed. These results were obtained using elastic, plastic, and viscoelastic material models. This review consists of three parts. The first part discusses the basic concept that the start (onset) of fracture is the mechanism of local instability near the cracks located in a single plane or parallel planes. The fracture criterion and the basic problems arising in this division of fracture mechanics are also formulated. Two basic approaches to establishing the foundations of the mechanics of fracture of materials compressed along cracks are outlined. One approach, so-called beam approximation, is based on various applied theories of stability of thin-walled systems (including the Bernoulli, Kirchhoff-Love, Timoshenko-type hypotheses, etc.). This approach is essentially approximate and introduces an irreducible error into the calculated stresses. The other approach is based on the basic equations and methods of the three-dimensional linearized theory of stability of deformable bodies for finite and small subcritical strains. This approach does not introduce major errors typical for the former approach and allows obtaining results with accuracy acceptable for mechanics. The second part offers a brief analysis of the basic results obtained with the first approach and a more detailed analysis of the basic results obtained with the second approach, including the consideration of the exact solutions for interacting cracks in a single plane and in parallel planes and results for some structural materials. The third part reports new results for interacting cracks in very closely spaced (or coinciding, as an asymptotic case) planes. These results may be considered a transition from the second approach (three-dimensional linearized theory of elastic stability) to the first approach (beam approximation). This is how the accuracy of results produced by the first approach is evaluated and the boundary conditions near the crack tip are established in the second approach. © 2014 Springer Science+Business Media New York. Source

Brus V.V.,Ukrainian Academy of Sciences
Semiconductors | Year: 2012

A detailed analysis of the spectral dependences of the real and imaginary components of the measured impedance of a simulated silicon p-n junction is carried out within the framework of a conventional equivalent circuit (parallel R dC b chain and series resistance R s). A simple technique was proposed for determining the true value of the barrier capacitance of structures with a potential barrier (without surface electrically active states) on the basis of analysis of the spectral dependence for the imaginary part of the measured impedance. © 2012 Pleiades Publishing, Ltd. Source

Yurchenko V.B.,Ukrainian Academy of Sciences
Progress In Electromagnetics Research M | Year: 2012

A high-Q reflection notch method for measuring large dielectric losses in absorbing materials when using a stack resonator, which is a one-dimensional analogue of a capillary-in-a-waveguide technique, has been proposed. A detailed explanation of the effects that lay the basis of the method has been presented. The method is particularly accurate and sensitive for highly absorbing materials when other techniques are inadequate. The method can be used for dielectric spectroscopy of a broad range of liquid and solid materials, with applications in chemical, pharmaceutical and food industry, biomedical sciences, agriculture etc., in those frequency bands of infrared, millimeter wave and, especially, THz waves where dielectric losses are significant. Source

Barbashova G.A.,Ukrainian Academy of Sciences
Surface Engineering and Applied Electrochemistry | Year: 2012

The effect of the electric circuit inductance on the hydrodynamic processes during high-speed impact welding of two plates is numerically investigated. An analytical dependence of the electric power amplitude and the pressure force amplitude on the inductance is determined. © 2012 Allerton Press, Inc. Source

Lyashenko A.,Ukrainian Academy of Sciences
Asian Pacific Journal of Reproduction | Year: 2015

Objective: To improve the indicators of motility, survival and fertilizing ability of spermatozoa by optimizing temperature factors and the duration of exposure at unfreezing straws. Methods: Straws by volume 0.25 mL were thawed at water bath temperatures at 65 °C, 67 °C and 70 °C for 6-7 seconds and at 75 °C for 4-6 seconds. Impact of exposure time and temperature thawing in the water bath on motility and survival of spermatozoa were studied. Results: Studies indicate that for the procedure of defrost water bath straws in seven seconds for temperature conditions of 65 °C, 67 °C and 70 °C, indicators of progressive motility and absolute survival rate were significantly higher than for the control group an average on 11.4 % (. P<0.01). Optimum exposure time (6-7 seconds) and temperature range (65-70 °C) defrosting semen doses were defined. Conclusions: Owing obtained the positive result, method of thawing was developed which increases the indicators of motility, survival and fertilizing capacity of bull semen. © 2015 Hainan Medical College. Source

Dublenych Y.I.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

A continuum of ground states is shown to exist in a lattice-gas model with one particle species on a triangular lattice with finite-range interactions. The structures of the continuum can be divided into three groups: periodic (up to phason flips along some channels), multiple-twin, and aperiodic. We suppose that there are quasicrystalline structures among the latter. The growth mechanism for the structures consists in continuous formation and self-destruction of defects through the propagation of phasonic excitations. Our investigation sheds light on some fundamental questions in the theory of quasicrystals and infinitely adaptive structures. © 2012 American Physical Society. Source

Bryk T.,Ukrainian Academy of Sciences | Bryk T.,Kharkiv Polytechnic Institute | Belonoshko A.B.,KTH Royal Institute of Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

It is shown, that the embedded-atom potential nicely describing structural properties of high pressure Fe can be successfully used for description of collective dynamics of liquid iron. A combination of molecular dynamics simulations and a fit-free analysis based on the approach of generalized collective modes (GCM) is used for calculations of spectra of collective excitations and relaxing modes at 1843 K. The obtained spectrum of acoustic excitations in the long-wavelength region perfectly agrees with the experimental speed of sound and reproduces the dispersion estimated from inelastic X-ray scattering (IXS) experiments. Heat fluctuations in liquid Fe were studied and resulted in calculated ratio of specific heats γ-1.40 being in agreement with the IXS-experiment estimate. We report analysis of the wave-number dependence of relaxation processes and their contributions to dynamic structure factors. This permits estimation of most important relaxation processes contributing to the shape of dynamic structure factors of liquid Fe in different regions of wave numbers. © 2012 American Physical Society. Source

Stashchuk M.H.,Ukrainian Academy of Sciences
Materials Science | Year: 2012

To study the influence of elastic strains caused by the action of external forces and internal hydrogeninduced stresses in the metal on the redistribution of hydrogen near stress concentrators, we propose a system of gradient-type differential equations. On the basis of this system, we develop a general algorithm and analytic relations for the investigation of the accumulation of hydrogen near technological and structural defects. The redistribution of hydrogen near circular stress concentrators, cracks, and rigid inclusions under the action of external loads is studied for hydrogenated elastic bodies. © 2012 Springer Science+Business Media, Inc. Source

Gaidar G.P.,Ukrainian Academy of Sciences
Surface Engineering and Applied Electrochemistry | Year: 2012

Annealing of the main radiation defects in silicon (A-centers, E-centers, and divacancies, etc.) is theoretically described on the basis of the experimental data obtained by many authors. The parameters that characterize this process (the activation energies and frequency factors) have been ascertained, and various mechanisms and reactions that determine the conditions for the annealing of the defects were proposed. © 2012 Allerton Press, Inc. Source

Schlottmann P.,Florida State University | Zvyagin A.A.,Ukrainian Academy of Sciences | Zvyagin A.A.,Max Planck Institute For Physik Komplexer Systeme
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

A gas of ultracold 6Li atoms (effective spin 1/2) confined to an elongated trap with one-dimensional properties is a candidate to display three different phases: (i) fermions bound in Cooper-pair-like states, (ii) unbound spin-polarized particles, and (iii) a mixed phase in which Cooper bound states and unpaired particles coexist. It is of great interest to extend these studies to fermionic atoms with higher spin, e.g., for neutral 40K, 43Ca, 87Sr, or 173Yb atoms. Within the grand-canonical ensemble, we investigated the μ versus H phase diagram (μ is the chemical potential and H the external magnetic field) for S=3/2,...,9/2 for the ground state using the exact Bethe ansatz solution of the one-dimensional Fermi gas with an attractive δ-function interaction potential. There are N=2S+1 fundamental states: the particles can be either unpaired or clustered in bound states of 2, 3, 2S, and 2S+1 fermions. The rich phase diagram consists of these N states and various mixed phases in which combinations of the fundamental states coexist. Bound states of N fermions are not favorable in high magnetic fields, but always present if the field is low. For S=3/2, possible scenarios for phase separation are explored within the local density approximation. For S=3/2, the phase diagram for the superposition of a Zeeman and a quadrupolar splitting is also discussed. © 2012 American Physical Society. Source

Schlottmann P.,Florida State University | Zvyagin A.A.,Ukrainian Academy of Sciences | Zvyagin A.A.,Max Planck Institute For Physik Komplexer Systeme
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

In the context of a gas of ultracold atoms with effective spin S=3/2 confined to an elongated trap, we study the one-dimensional Fermi gas interacting via an attractive δ-function potential within the grand-canonical ensemble. The particles can be either unbound or clustered in bound states of two, three, and four fermions. The rich μ versus H ground-state phase diagram (μ is the chemical potential and H the external magnetic field) consists of the four basic states and the various possible mixed phases in which some these states coexist. Extending the analysis of K. Yang for S=1/2, we study the correlation functions of the generalized Cooper clusters of bound states of two, three, and four particles using conformal field theory and the exact Bethe Ansatz solution. The correlation functions consist of a power law with distance times a sinusoidal term oscillating with distance. In an array of tubes with weak Josephson tunneling, the type of superfluid order is determined by these correlation functions. The wavelength of the oscillations is related to the periodicity of a generalized Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state for higher spin particles. All the relevant states are analyzed for S=3/2. © 2012 American Physical Society. Source

Sosnitskii S.P.,Ukrainian Academy of Sciences
Advances in Space Research | Year: 2014

In the three-body problem, we consider the Lagrange and Hill stability including the Lagrange stability for the manifold of symmetric motions that exists in the case where two of three bodies have equal masses. To analyze the stability, in addition to integrals of energy and angular momentum we use the Lagrange-Jacobi equality. We prove theorems on the Lagrange and Hill stability. The theorem on the Hill stability has effective application in the case where the mass of a body is much less than masses of two other bodies. In this case, as it is known, the model of the restricted three-body problem is usually applied. © 2014 COSPAR. Published by Elsevier Ltd. All rights reserved. Source

Skobelev V.V.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2013

Some general properties of families of hash functions defined by strongly connected automata without output function over a finite ring are analyzed. The probabilities of randomly choosing a sequence for which a hash function assumes a given value and also two different sequences of the same length for which the values of a hash function coincide. The computational security of the investigated hash-functions is characterized. © 2013 Springer Science+Business Media New York. Source

Zvyagin A.A.,Max Planck Institute For Physik Komplexer Systeme | Zvyagin A.A.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We have investigated how the spin-orbit interaction can affect the properties of the Hubbard chain. Asymptotics for correlation functions are calculated in the framework of the conformal field theory. We show that the behavior of correlation functions of the Hubbard chain with the spin-orbit coupling drastically differs from that of the standard Hubbard chain. © 2012 American Physical Society. Source

Ivanova A.A.,Ukrainian Academy of Sciences
Metallurgist | Year: 2012

This article examines different numerical characteristics of the temperature field of a continuous-cast semifinished product and examines their sensitivity to parameters of the casting operation. A method is proposed for evaluating the thermal state of ingots. The method can be used both at the design stage and in the course of operation of a continuous caster's automated control system. © 2012 Springer Science+Business Media, Inc. Source

Raichev O.E.,Ukrainian Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The effective 6×6 matrix Hamiltonian for two-dimensional states in HgTe/CdTe quantum wells is derived. The use of the extended basis (in contrast to the previously studied 4×4 matrix Hamiltonian) allows us to describe quantum wells with arbitrary orientation of interfaces and investigate the influence of in-plane magnetic field. The Hamiltonian is applied to calculation of energy spectra of both two-dimensional subbands and edge states in the range of well widths corresponding to the topological insulator phase. It is found that the in-plane magnetic field opens a gap in the edge-state spectrum, and the increase in the field causes disappearance of one of the edge-state branches. A strong (about 10 T) magnetic field induces a phase transition from the gapped state to a gapless two-dimensional state, with energy spectrum similar to that of bulk HgTe. An analytical expression for the transition field through the parameters of the effective Hamiltonian is obtained. © 2012 American Physical Society. Source

Kyryliv V.I.,Ukrainian Academy of Sciences
Materials Science | Year: 2012

A comparative investigation of the wear resistances of normalized steel 45 with surface nanostructure and ShKh15 steel after hardening and low-temperature tempering in an oil-abrasive medium is performed. It is shown that steel 45 has a higher wear resistance than ShKh15 steel. This enables one to replace an alloyed steel by a carbon steel with surface nanocrystalline structure in a friction unit and simultaneously improve the wear resistance of the carbon steel. © 2012 Springer Science+Business Media, Inc. Source

Using the analysis of state-of-the-art techniques of fretting fatigue studies and results of description of multi-stage fatigue crack propagation in fretting zone within fracture mechanics framework, we have refined the calculation-and-experimental technique earlier proposed by the author. This technique allows one to predict current values of the angle and rate of inclined crack propagation in the subsurface layers of material under fretting conditions using calculated stress intensity factors K I and K II for contact and bulk loads, as well as experimental crack resistance diagrams by K I and/or K II types. We have performed comparative analysis of various techniques for construction of crack resistance diagrams by K I and K II types and obtained the results for AMg6N and Al 7075-T6 aluminum alloys and VT9 titanium alloy. It is shown that the initial stage of crack propagation in the above alloys can occur in the maximal shear stress plane by shear mechanism or in the maximal tensile stress plane by cleavage mechanism according to the Otsuka two-parameter criterion or to the Richard empirical criterion. © 2010 Springer Science + Business Media, Inc. Source

Irina L.,Ukrainian Academy of Sciences
Immunology, Endocrine and Metabolic Agents in Medicinal Chemistry | Year: 2015

Rise in the frequency of age-related diseases (neurodegenerative and cardiovascular diseases, osteoporosis, etc.) has great socio-economic implications. Great pathogenetic significance of age changes in functioning of the immune and neuroendocrine systems and their relationship with dysfunction of the central organs (thymus and pineal gland) has been established. On the contrary, melatonin and thymic hormones not only inhibit age changes in functioning of the above systems and diminish the incidence of age-related diseases but also improve their clinical results. Inhibiting effects of thymus and pineal gland factors on the development of age-related diseases can also be explained by their action on biological properties (proliferating and differential potential) of proper stem cells of different types in the organism organs. Noteworthy, the effect of melatonin on certain types of stem cells is realized not only directly but also indirectly via alteration of thymic endocrine function and functioning of endocrine glands. Thus, the pineal gland can provide adaptive (rhythmical) changes of the proliferative and differential potential of proper stem cells. Transplantation of different types of stem cells is used as stem therapy during already developed disorders. Nevertheless, at these diseases, the age-related dysfunction of the thymus and pineal gland is enhanced along with the changes in body organs interrelations. Therefore, therapeutic effects of stem cells transplantation can show themselves or be enhanced against the background of renewal of rhythmicity of pineal-thymus interactions. Maintenance of immune-endocrine interactions involving thymus and pineal gland plays role in the stem cell therapy of age-related diseases. © 2015 Bentham Science Publishers. Source

Snopok B.A.,Ukrainian Academy of Sciences
Theoretical and Experimental Chemistry | Year: 2014

On the basis of current trends in the description of adsorption processes in complex media a conceptual analysis was made of the mechanisms of the appearance of nonexponential kinetics (stretched exponential function) in chemical reactions on a surface. A review of approaches ranging from a phenomenological description to a generalized fractal formalism is presented, and it was used to develop a model of adsorption in nonuniform media in terms of the concepts of the reaction space as a topological subject. By "geometric description" of the evolution of the surface reactions it is possible to unify the various types of effect in terms of a reaction space of required dimensionality and to establish a relationship between the parameters of macroscopic kinetics and features of the trajectory of the analyte in the nonuniform environment during its movement toward the receptor center. © 2014 Springer Science+Business Media New York. Source

Gavrish S.P.,Ukrainian Academy of Sciences
Journal of Computational Chemistry | Year: 2012

Fairly accurate approximate expressions for commonly used characteristics of non-planarity of trigonal sp 2-hybridized centers are reported. It is shown that the behavior of all these parameters as a function of bond angles (α, β, γ) is determined primarily by the square-root of the difference [360° - (α + β + γ)]. This quantity is proposed as a new versatile measure of pyramidalization. © 2012 Wiley Periodicals, Inc. Source

Kuksenko S.P.,Ukrainian Academy of Sciences
Russian Journal of Electrochemistry | Year: 2014

Comparative analysis of cycling performance of hybrid electrodes based on the MAG synthetic graphite mechanic mixtures with silicon nanopowder and "nano-Si/SiO2/hard carbon" ceramic frame-ordered composite in 1 M LiPF6 solution in a monofluoroethylene carbonate-ethyl methyl carbonate mixture (30: 70, v/v), added with 3 wt % vinylene carbonate and 2 wt % ethylene sulfite, is performed. The high capacity loading (up to 6.8 mA h cm-2 at the electrode layer thickness of 37 μm) and acceptable accumulated irreversible capacity of the composite-containing electrodes are achieved, due to the electrodes' high density and stable silicon-containing electrode/electrolyte interface formation. © 2014 Pleiades Publishing, Ltd. Source

Tolstov A.L.,Ukrainian Academy of Sciences
Theoretical and Experimental Chemistry | Year: 2014

Advances in the synthesis of polyurethane systems containing silver in the ionic and highly dispersed metallic forms are described, and the chemical and physicochemical principles of control of their formation process are discussed in detail. Special attention is paid to the interaction of the silver ions and nanoparticles with the polyurethane matrix and also to its effect on the phase structure and other characteristics of the obtained composite systems. © 2014 Springer Science+Business Media New York. Source

Selivanov M.F.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2010

The time variation in the stresses around an elliptic hole in a composite plate is studied. Solutions that characterize the effect of the time dependence of the relaxation moduli of the composite components on stresses are obtained. The solutions in the time domain are obtained from the elastic-viscoelastic analogy and the corresponding elastic solutions for the effective moduli of the composite and the stress field around an elliptic hole in an anisotropic plate. The inverse Laplace transformation is carried out by an effective numerical method. © 2010 Springer Science+Business Media, Inc. Source

Kuksenko S.P.,Ukrainian Academy of Sciences
Russian Journal of Applied Chemistry | Year: 2010

A new parameter, "accumulated irreversible capacity," is suggested for assessing the suitability of a material as an active component for the anode of lithium-ion batteries. A comprehensive analysis of cycling parameters of silicon nanomaterials is made and ways for their improvement are considered. © 2010 Pleiades Publishing, Ltd. Source

Lebovka N.I.,Ukrainian Academy of Sciences
Advances in Polymer Science | Year: 2014

This chapter reviews the recent progress in aggregation of colloidal particles with long-range interactions, including simple colloids and polyelectrolytes. The relevant interactions between colloidal particles, including Born repulsion, van der Waals, electrostatic, structural solvation, hydrophobic hydrodynamic interactions and attraction between like-charge colloids, charge nonuniformity, and adsorbed polymer, are analyzed. The main types of computer models used for simulation of cluster morphology and aggregation kinetics of the different interacting species (similarly and oppositely charged particles and polyelectrolytes) are reviewed. The main scaling laws for different aggregating kernels that describe diffusion-limited, reaction-limited, gelling, and retarded aggregations are also presented and analyzed. Graphical Abstract: © Springer-Verlag Berlin Heidelberg 2012. Source

Putchkov A.,Ukrainian Academy of Sciences
ZooKeys | Year: 2011

A review of the ground beetles of the Ukrainian fauna is given. Almost 750 species from 117 genera of Carabidae are known to occur in the Ukraine. Approximately 450 species of ground beetles are registered in the Carpathian region. No less than 300 species of ground beetles are found in the forest zone. Approximately 400 species of Carabidae present in the forest-steppe zone are relatively similar in species composition to those in the forest territories. Some 450 species of Carabidae are inhabitants of the steppe zone. Representatives of many other regions of heterogeneous biotopes such as forest, semi desert, intrazonal, etc. can be found in the steppe areas. The fauna of Carabidae (ca. 100 species) of the lowlands of southern Ukraine (sandy biotopes), situated mostly in the Kherson region, is very peculiar. The fauna of the Crimean mountains contains about 300 species. Conservation measures for the Carabidae are discussed. © A. Putchkov. Source

Gvozdovskyy I.,Ukrainian Academy of Sciences
Liquid Crystals | Year: 2015

The phase transitions of pure cholesteric liquid crystals, based on right- or left-handed chiral dopants (ChDs) (enantiomers R-811 and S-811, Merck, Darmstadt, Germany) with various concentrations dissolving in the nematic liquid crystal mixture CHCA (ZhK-805, Russia, NIOPIK) were experimentally studied. For the first time, blue phases of cholesterics were found at the concentration range of ChDs 32–36 wt.%. Experimentally it was observed that during the cooling process the blue phase of cholesterics is stable over a wide temperature range about ~15°C including human body and near-room temperatures. Thermal phase transitions, spectral characteristics and electro-optical features of blue phases were examined. Planar and homeotropic alignment layers were used to study the influence of various boundary conditions on platelet textures of blue phases. © 2015 Taylor & Francis Source

Guzzinati G.,University of Antwerp | Schattschneider P.,Vienna University of Technology | Bliokh K.Y.,RIKEN | Bliokh K.Y.,Ukrainian Academy of Sciences | And 3 more authors.
Physical Review Letters | Year: 2013

Electron vortex beams carrying intrinsic orbital angular momentum (OAM) are produced in electron microscopes where they are controlled and focused by using magnetic lenses. We observe various rotational phenomena arising from the interaction between the OAM and magnetic lenses. First, the Zeeman coupling, proportional to the OAM and magnetic field strength, produces an OAM-independent Larmor rotation of a mode superposition inside the lens. Second, when passing through the focal plane, the electron beam acquires an additional Gouy phase dependent on the absolute value of the OAM. This brings about the Gouy rotation of the superposition image proportional to the sign of the OAM. A combination of the Larmor and Gouy effects can result in the addition (or subtraction) of rotations, depending on the OAM sign. This behavior is unique to electron vortex beams and has no optical counterpart, as Larmor rotation occurs only for charged particles. Our experimental results are in agreement with recent theoretical predictions. © 2013 American Physical Society. Source

Kushch V.I.,Ukrainian Academy of Sciences
International Journal of Engineering Science | Year: 2010

A complete solution of the conductivity problem has been obtained for the finite and infinite arrays of circular inclusions with interface arc cracks regarded as the models of fibrous composite with interface damage. By combining the multipole expansion technique with newly derived theoretical results, the model boundary-value problem has been reduced to a linear set of algebraic equations. An exact and finite form expression of the effective conductivity tensor has been found by integrating the local fields over the representative cell volume. The numerical data are given which show an accuracy and numerical efficiency of the proposed method and discover the way and extent to which the conductivity of fibrous composite is affected by the interface debonding. © 2009 Elsevier Ltd. All rights reserved. Source

Larin V.B.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2010

The path-planning problem for a compound robotic vehicle with three steerable wheels is solved. In the kinematic approximation, this problem is formulated as a variational problem with conditions prescribed at three points. The case of inertial motion is analyzed. The motion of a robot in an L-shaped holding alley is considered as an illustration of the algorithm proposed © 2010 Springer Science+Business Media, Inc. Source

Larin V.B.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2010

The motion-planning problem for a wheeled robotic vehicle with no steerable wheel is solved in both Cartesian and polar coordinate systems. The results are illustrated by examples © 2010 Springer Science+Business Media, Inc. Source

Pedenko Y.A.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2010

The statistical computer simulation of measuring elevation angles of low-level targets has been carried out by means of three-frequency monopulse radar above the rough sea under multipath conditions. It is shown that the use of three-frequency monopulse radar substantially decreases errors of elevation angles measurement in comparison with single-frequency version. The use of three-frequency monopulse radar also reduces the possibility of tracking loss. The dependence of these characteristics on frequency spacing has been investigated. © 2010 by Begell House, Inc. Source

Larin V.B.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2010

Exact formulas to determine the reactions of nonholonomic constraints for a two-link robotic vehicle with three steerable wheels are derived. The simplest (asymptotic) approximations of these formulas are presented. The results are illustrated by a numerical example © 2010 Springer Science+Business Media, Inc. Source

Tsvelykh A.N.,Ukrainian Academy of Sciences
Acta Zoologica Bulgarica | Year: 2011

Chaffinches from the south districts of Bulgaria were earlier considered not to belong to the nominate subspecies F. c. coelebs but to the subspecies F. c. solomkoi. These subspecies radically differentiate by sounding of rain-calls. The analysis of chaffinches' rain-calls from South-East Bulgaria shows that they do not indeed belong to the nominate subspecies. However, by rain-call sounding (and by morphological indexes) they do not belong to the subspecies F. c. solomkoi either. Their rain-calls correspond to the calls which are characteristic for another subspecies - F. c. caucasica inhabiting Caucasus and Asia Minor. The comparison of rain-call sonograms of chaffinches from south-eastern part of Bulgaria and birds of all three subspecies shows that the region is inhabited by the subspecies F. c. caucasica. Source

Grigor'eva L.O.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2010

The methods of characteristics and difference schemes are used to study the nonstationary thickness vibrations of a piezoelectric layer polarized across the thickness and subjected to electrical and mechanical loads. The propagation of waves under loading of various types is studied. The dynamic electroelastic state of the layer is analyzed. It is established that the characteristics of the electroelastic state are in a linear relationship. ©2010 Springer Science+Business Media, Inc. Source

Avramov K.V.,Ukrainian Academy of Sciences
Strength of Materials | Year: 2010

A model for self-excited vibrations of a single-disk asymmetric rotor with short sliding bearings is proposed, which is reduced to a system of four ordinary differential equations of the second order. The obtained dynamic system is described by the Shaw-Pierre nonlinear normal modes. © 2010 Springer Science+Business Media, Inc. Source

Lila D.M.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2010

A method of setting up a matrix-valued Lyapunov function for a system of differential equations with quasiperiodic coefficients is proposed. This function is used to establish asymptotic-stability conditions for some class of mechanical systems described by nonlinear systems of equations. The stability of motion of these systems in critical cases is analyzed. ©2010 Springer Science+Business Media, Inc. Source

Kiselyov V.K.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2010

The paper is devoted to elaboration of the theoretical and experimental basis, methods and recommendations aimed at the development of a new trend in the experimental radio physics -physical quasi-optical waveguide modeling (QWM) of the processes of electromagnetic scattering in the near millimeter (NMM) and submillimeter (SMM) wavelength ranges. The methods of experimental research of the electromagnetic scattering processes in the quasi-optical (QO) directional structures of a hollow dielectric waveguide (HDW) class have been developed and generalized. The basis for development of the radio measurement facilities used for physical electromagnetic modeling (EMM) of the object's scattering characteristics in the NMM and SMM wavelength bands has been elaborated. © 2010 by Begell House, Inc. Source

We discuss the methods of assessment of stress-strain state and stress gradient in nonuniformly stressed structural components under elastic and elastic-plastic cyclic deformation. We systematize the research findings on fatigue of metals and alloys, including the stress concentration case, as well as the methods that describe the dependence of fatigue characteristics on the stress gradient. Source

Khalameyda D.D.,Ukrainian Academy of Sciences
Telecommunications and Radio Engineering (English translation of Elektrosvyaz and Radiotekhnika) | Year: 2010

The possibility is analyzed of using an interferometer which receives radio signals from a geostationary satellite for estimating, within an exponential troposphere model, the path-integrated gradient of the tropospheric refraction index. The factors influencing the accuracy of angle-of arrival measurements are discussed and evaluated (including receiver noise, instability of the antenna phase center, and variations of the feeder line parameters). Performance requirements to the interferometer are considered. © 2010 by Begell House, Inc. Source

Avramov K.V.,Ukrainian Academy of Sciences
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2010

Equations of motion for a four-degree-of-freedom dynamical system describing the vibrations of a one-disc elastic rotor taking into account gyroscopic moments on a non-linear flexural base are derived. A new version of the multiple scales method is developed and applied to analyse the non-linear dynamics of such a system for different resonances. The steady motions of the rotor are analysed. From the asymptotic analysis, it is shown that out-of-plane motions of the disc exist in the symmetric rotor. Source

Shul'Ga M.O.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2010

A mixed system of six equations of elasticity is represented as a Hamiltonian (canonical) operator system in one of the spatial coordinates. It is shown that this system is the Euler equations for the Hellinger-Reissner principle with an appropriately modified integrand. One more functional with an operator integrand from which the canonical operator system can be derived is set up © 2010 Springer Science+Business Media, Inc. Source

Gunther U.,Helmholtz Center Dresden | Kuzhel S.,Ukrainian Academy of Sciences
Journal of Physics A: Mathematical and Theoretical | Year: 2010

Gauged PT quantum mechanics (PTQM) and corresponding Krein space setups are studied. For models with constant non-Abelian gauge potentials and extended parity inversions compact and noncompact Lie group components are analyzed via Cartan decompositions. A Lie-triple structure is found and an interpretation as PT-symmetrically generalized Jaynes-Cummings model is possible with close relation to recently studied cavity QED setups with transmon states in multilevel artificial atoms. For models with Abelian gauge potentials a hidden Clifford algebra structure is found and used to obtain the fundamental symmetry of Krein space-related J-self-adjoint extensions for PTQM setups with ultra-localized potentials. © 2010 IOP Publishing Ltd. Source

Nedostup V.I.,Ukrainian Academy of Sciences
High Temperature | Year: 2013

The configurations and properties of the characteristic curves on the thermodynamic surface of a real gas, that is, of locus points where the configuration component of a thermodynamic property becomes zero, have been analyzed. The relation of asymptotic properties of the curves with a virial equation of state at ρ → 0 and with a hypothetical fluid system overcooled to 0 K at T → 0 has been studied. The correlation of asymptotic properties of the curves manifesting themselves, in particular, in the direct relationship of coordinates of characteristic points of ideal curves on a thermodynamic surface with an intermolecular interaction potential has been demonstrated. © 2013 Pleiades Publishing, Ltd. Source

Godlevsky A.B.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2010

In modelling attribute transition systems, classes of their states can be described in a given signature of functional and predicate symbols. A procedure is developed for transforming such formulas by assignment operators and the obtained formulas are proved to correspond to strongest postconditions. A peculiarity of this paper is that functional-type attributes can be used in specifying transition systems, in particular, their array-type attributes. © 2010 Springer Science+Business Media, Inc. Source

Chebotarev A.N.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2010

A method is proposed to transform an FSM specification in the language L*into a specification in the language L. Using additional predicate symbols, the former specification is first transformed into a specification of an FSM with finite memory. Then this specification is transformed into an automata equivalent specification in the language L. © 2010 Springer Science+Business Media, Inc. Source

Abramov A.,CAS Shenzhen Institutes of Advanced Technology | Abramov A.,Ukrainian Academy of Sciences
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2015

We present an effective numerical procedure to calculate the binding energies and wave functions of the hydrogen-like impurity states in a quantum dot (QD) with parabolic confinement. The unknown wave function was expressed as an expansion over one-dimensional harmonic oscillator states, which describes the electron's movement along the defined z-axis. Green's function technique used to obtain the solution of Schredinger equation for electronic states in a transverse plane. Binding energy of impurity states is defined as poles of the wave function. The dependences of the binding energy on the position of an impurity, the size of the QD and the magnetic field strength are presented and discussed. © 2014 Published by Elsevier B.V. Source

Cherniha R.,Ukrainian Academy of Sciences | Cherniha R.,National University of Kyiv-Mohyla Academy
Journal of Physics A: Mathematical and Theoretical | Year: 2010

New definitions of Q-conditional symmetry for systems of PDEs are presented, which generalize the standard notation of non-classical (conditional) symmetry. It is shown that different types of Q-conditional symmetry of a system generate a hierarchy of conditional symmetry operators. A class of twocomponent nonlinear reaction-diffusion systems is examined to demonstrate the applicability of the definitions proposed and it is shown when different definitions of Q-conditional symmetry lead to the same operators. © 2010 IOP Publishing Ltd. Source

Kaminsky A.A.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2014

Theoretical and experimental studies on the deformation and delayed fracture of viscoelastic bodies due to slow subcritical crack growth are reviewed. The focus of this review is on studies of subcritical growth of cracks with well-developed fracture process zones, the conditions that lead to their critical development, and all stages of slow crack growth from initiation to the onset of catastrophic growth. Models, criteria, and methods used to study the delayed fracture of viscoelastic bodies with through and internal cracks are analyzed. Experimental studies of the fracture process zones in polymers using physical and mechanical methods as well as theoretical studies of these zones using fracture mesomechanics models that take into account the structural and rheological features of polymers are reviewed. Particular attention is given to crack growth in anisotropic media, the effect of the aging of viscoelastic materials on their delayed fracture, safe external loads that do not cause cracks to propagate, the mechanism of multiple-flaw fracture of viscoelastic bodies with several cracks and, especially, processes causing cracks to coalesce into a main crack, which may result in a break of the body. Methods and results of solving two- and three-dimensional problems of the mechanics of delayed fracture of aging and non-aging viscoelastic bodies with cracks under constant and variable external loads, wedging, and biaxial loads are given. © 2014, Springer Science+Business Media New York. Source

The results obtained by Ukrainian researchers on the justification, development, and application of ultrasonic nondestructive methods (UNDMs) for evaluating stresses in structural members and near-surface layers of materials are briefly discussed. A distinguishing feature of Ukrainian methods is that they are capable of determining triaxial (including biaxial and uniaxial as partial cases) stresses, unlike non-Ukrainian methods applicable only to uniaxial stresses. The UNDMs are based on the laws of wave propagation in solids with initial (residual) stresses, including the laws of Rayleigh wave propagation. The results discussed were obtained in the National Academy of Sciences of Ukraine (S. P.Timoshenko Institute of Mechanics and E. O. Paton Institute of Electric Welding) © 2014 Springer Science+Business Media New York. Source

Naidyuk Y.G.,Ukrainian Academy of Sciences | Gloos K.,University of Turku
Solid State Communications | Year: 2014

Andreev reflection (AR) and Yanson point-contact spectroscopy (PCS) have been applied simultaneously to study the superconducting (SC) gap and the electron-phonon interaction (EPI) in a Zn single crystal. The correlation between SC gap value and EPI spectrum allowed us to establish the anisotropy of the SC gap. Evidence for multiband superconductivity in Zn is present with two gaps related as 1:1.3. We also found that the AR features are more robust against the point-contact quality than the EPI ones, possibly, due to the large coherence length in Zn compared to the typical PC size. Even for the PCs close to the ballistic regime with intense EPI spectra, the transmission coefficient evaluated from the AR spectra is near the one predicted theoretically for the diffusive regime of a current flow in the PC. Understanding those phenomena would provide a more reliable basis to apply both types of spectroscopies to study more complex SCs. © 2014 Elsevier Ltd. Source

Miniati F.,ETH Zurich | Elyiv A.,University of Liege | Elyiv A.,Ukrainian Academy of Sciences
Astrophysical Journal | Year: 2013

The stability properties of a low-density ultrarelativistic pair beam produced in the intergalactic medium (IGM) by multi-TeV gamma-ray photons from blazars are analyzed. The problem is relevant for probes of magnetic field in cosmic voids through gamma-ray observations. In addition, dissipation of such beams could considerably affect the thermal history of the IGM and structure formation. We use a Monte Carlo method to quantify the properties of the blazar-induced electromagnetic shower, in particular the bulk Lorentz factor and the angular spread of the pair beam generated by the shower, as a function of distance from the blazar itself. We then use linear and nonlinear kinetic theory to study the stability of the pair beam against the growth of electrostatic plasma waves, employing the Monte Carlo results for our quantitative estimates. We find that the fastest growing mode, like any perturbation mode with even a very modest component perpendicular to the beam direction, cannot be described in the reactive regime. Due to the effect of nonlinear Landau damping, which suppresses the growth of plasma oscillations, the beam relaxation timescale is found to be significantly longer than the inverse Compton loss time. Finally, density inhomogeneities associated with cosmic structure induce loss of resonance between the beam particles and plasma oscillations, strongly inhibiting their growth. We conclude that relativistic pair beams produced by blazars in the IGM are stable on timescales that are long compared with the electromagnetic cascades. There appears to be little or no effect of pair beams on the IGM. © 2013. The American Astronomical Society. All rights reserved. Source

Krivoruchko V.N.,Ukrainian Academy of Sciences
Low Temperature Physics | Year: 2014

Experimental and theoretical studies of the physics of the metal-insulator (MI) transition in manganites with colossal magnetoresistance are reviewed. The emphasis is on the properties of these systems caused by inhomogeneities in the electronic and magnetic states of the manganites near the Curie temperature. Experimental data supporting the existence of the Griffiths phase and theoretical treatments of the MI transition as a specific realization of a ferromagnetic-Griffiths phase transition in substituted manganites are discussed. © 2014 AIP Publishing LLC. Source

Vinogradov A.A.,Ukrainian Academy of Sciences
Journal of Superhard Materials | Year: 2016

The paper addresses the available methods of determination of the chip flow angle h on the tool face in oblique free cutting of ductile metals. A method for assessing this angle by the chip contraction is put forward; it is based on determination of the effecting (working) rake γeff of the tool in the plane normal to cutting plane and passing through the chip flow direction. Comparative calculation results are given; it is noted that the proposed method offers advantages of simplicity and accuracy of determination of the angle η. © 2016, Allerton Press, Inc. Source

Gozhik P.,Ukrainian Academy of Sciences | Lindner L.,University of Warsaw | Marks L.,University of Warsaw
Quaternary International | Year: 2012

The area of southern Poland and the Ukraine was occupied by ice sheets of the South Polish or Oka s.l. (Elsterian) Glaciation, comprising 3 separate glacial advances, that is, the Nidanian (Tursky), Sanian 1 (Vyzhivsk, Don) and Sanian 2 (Krukienice, Oka s.s.). An ice sheet of the Nidanian Glaciation reached its southernmost point in the interfluve of the upper Odra and the upper Vistula. An ice sheet of the Sanian 1 Glaciation advanced furthest to the south in south-eastern Poland and in south-western Ukraine. The Sanian 2 Glaciation (Oka s.s.) ice sheet was smaller in Poland but it was more widespread in the lower Pryp'iat and the middle Dnieper drainage basins. Distinctive lobate margins of the ice sheets were mostly due to adjustments to the relief of their forefields, and can be explained in terms of specific glacial dynamics in this part of Europe. © 2010 Elsevier Ltd and INQUA. Source

Kashirina N.I.,Ukrainian Academy of Sciences | Lakhno V.D.,Russian Academy of Sciences
Physics-Uspekhi | Year: 2010

Research on the polaron-polaron interaction and the theory of large-radius bipolarons are reviewed. The difference between the two-center and one-center continuum bipolaron models in isotropic and anisotropic crystals is discussed. It is shown that the inclusion of electron-electron correlations can significantly reduce the bipolaron and D--center energies as well as the energies of exchange-bound pairs of shallow hydrogen-like centers. The two-center bipolaron configuration corresponds to a shallow secondary minimum and is unstable. The phonon-mediated exchange interaction between Pekar polarons has an antiferromagnetic nature and exceeds the ferromagnetic interaction due to the Coulomb interaction of electrons localized in polaron potential wells. The possibility that the superfluidity of bipolarons can give rise to high-temperature superconductivity is discussed and problems related to the Wigner crystallization of a polaron gas are examined. © 2010 Uspekhi Fizicheskikh Nauk, Russian Academy of Sciences. Source

Pilyugin L.S.,Ukrainian Academy of Sciences | Pilyugin L.S.,University of Heidelberg | Grebel E.K.,University of Heidelberg | Mattsson L.,Copenhagen University
Monthly Notices of the Royal Astronomical Society | Year: 2012

We suggest a new way of determining abundances and electron temperatures in Hii regions from strong emission lines. Our approach is based on the standard assumption that Hii regions with similar intensities of strong emission lines have similar physical properties and abundances. A 'counterpart' for a studied Hii region may be chosen among Hii regions with well-measured abundances (reference Hii regions) by comparison of carefully chosen combinations of strong-line intensities. Then the abundances in the investigated Hii region can be assumed to be the same as those in its counterpart. In other words, we suggest to determine the abundances in Hii regions 'by precedent'. To get more reliable abundances for the considered Hii region, a number of reference Hii regions are selected and then the abundances in the target Hii region are estimated through extrapolation/interpolation. We will refer to this method of abundance determination as the counterpart method or, for brevity, the C method. We define a sample of reference Hii regions and verify the validity of the C method. We find that this method produces reliable abundances. Finally, the C method is used to obtain the radial abundance distributions in the extended discs of the spiral galaxies M83, NGC4625 and NGC628. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. Source

Dzyublik A.Ya.,Ukrainian Academy of Sciences
Physical Review C - Nuclear Physics | Year: 2013

We described the nuclear excitation by electron transition (NEET) by using strict collision theory combined with quantum electrodynamics. All stages of the process are considered, which include ionization of the atom by an x-ray photon with the formation of the hole in an inner electronic shell, its decay accompanied by the excitation of the nucleus, and the subsequent deexcitation of the nucleus. The cross sections for the NEET and photoabsorption of x rays are calculated near the threshold. We also analyzed the fine structure of the NEET curve analogous to the extended x-ray-absorption fine structure, well known in x-ray optics. The results agree with the findings of Kishimoto. © 2013 American Physical Society. Source

Shevchuk B.M.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

This paper proposes an approach to improving the efficiency of packet data transmission in computer radio networks on the basis of implementation of a complex of algorithms for operative compact data encoding and protection. The algorithms are implemented by subscribers of a network and provide the encryption and noise protection of binary sequences in noisy channels and formation and adaptive transmission of highly informative and noise-immune data packets consisting of interval code-signal sequences with a variable base. © 2016 Springer Science+Business Media New York Source

Palagin A.V.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2016

Principles of concretization and development of the noosphere paradigm are formulated as applied to problems of modern scientific research. It is shown that it is precisely the transdisciplinary approach to such investigations and also an efficient cooperation of teams of professionals representing different subject areas that provide the possibility of construction of a scientific picture of the world and a global knowledge network that form the basis of noospheregenesis. At the same time, the ontological approach to the representation and integration of scientific knowledge makes it possible to create efficient tools for the construction of systems and a technological base for the systemology of transdisciplinary interaction and ontological engineering. © 2016 Springer Science+Business Media New York Source

Babenko L.P.,Ukrainian Academy of Sciences
Mikrobiolohichnyǐ zhurnal (Kiev, Ukraine : 1993) | Year: 2012

The CeO2 sol with the size of nanoparticles 2-4 nm has been synthesized. It has been determined that the synthesized nanocrystalline cerium has antibacterial activity in vitro against different groups of opportunistic microorganisms: clinical strains of Escherichia coli, Staphylococcus aureus and Candida albicans. The rate of viability depression of test-cultures depends on the concentration of cerium dioxide nanoparticles and time of incubation. It is shown that the sol interacts with the bacterial cell surface. It is suggested that the observed differences of antibacterial action of nanocrystalline cerium dioxide can be related to the structural characteristics of the cell surface. Source

Kulik T.V.,Ukrainian Academy of Sciences
Journal of Physical Chemistry C | Year: 2012

The interaction of acetic, propionic, butyric, isobutyric, valeric, nonanoic, decanoic, and pivalic acids with the surface of fumed silica was investigated by temperature-programmed desorption mass spectrometry (TPD-MS). Mechanisms of the formation of ketenes from chemisorbed fragments of carboxylic acids on the surface of fumed silica were proposed and the kinetic parameters of the reaction were calculated. The Taft correlation equation and the reaction parameter ρ could be obtained by application of the linear free energy relationship (LFER) principle for this reaction series. The applicability of the LFER method to the study of reactions of adsorbed organic molecules on mineral surfaces occurring during TPD-MS experiments was demonstrated using a series of acids. © 2011 American Chemical Society. Source

Kuksenko S.P.,Ukrainian Academy of Sciences
Russian Journal of Applied Chemistry | Year: 2013

Within the framework of the novel strategy of the arrangement of silicon particles in a rigid matrix framework, hybrid electrodes were fabricated from mixtures of synthetic graphite with small additions of nanosilicon/solid carbon and microsilicon, natural graphite/solid carbon composites. The electrode cycling parameters achieved (high loading capacity and low accumulated irreversible capacity) are due to high density of the electrodes and formation of stable electrode|electrolyte interface. © 2013 Pleiades Publishing, Ltd. Source

Stanislavsky A.,Ukrainian Academy of Sciences | Weron K.,Wroclaw University of Technology
Physical Chemistry Chemical Physics | Year: 2013

Many chemical reactions demonstrate a very similar evolution of reagent concentrations in time, although their species are quite different. This can be linked with a universal stochastic behavior of reagents. In this paper we show what role in understanding chemical kinetics stochastic models play. To support this concept, we consider two interesting cases known in the literature as first- and second-order reactions. The former has a stretched exponential decay in time for its reagent concentration, and the latter evolves hyperbolically. We have established that the behavior can be explained by limit theorems of probability theory. The reaction evolution is directly connected with different behavior motivations in reagent populations. The reason for the universal kinetics is found in the indices of the corresponding probability distribution functions. They are macroscopic parameters measured in chemical experiments. Such an approach allows ones to discover what happens with molecular populations in microscopic dynamics. This journal is © 2013 the Owner Societies. Source

Korol N.A.,Ukrainian Academy of Sciences
Mikrobiolohichnyǐ zhurnal (Kiev, Ukraine : 1993) | Year: 2012

The vast variety of bacteriophages and the uniqueness of their individual representatives dictate to perform the detailed study of the actual phage-cell interactions, the virion morphogenesis and morphopoiesis in particular. An analysis of the complete genome sequence of the temperate phage ZF40 Pectobacterium carotovorum has shown that it is a representative of a unique group of phages of the Myoviridae family [Comeau A. M, Tremblay D., Moineau S., Rattei T., Kushkina A. I, Tovkach F I., H.M. Krisch, H.W. Ackermann Phage Morphology Recapitulates Phylogeny: The Comparative Genomics of a New Group of Myoviruses // PLoS ONE.--July 2012. - 7. - N 7. - e40102]. Characteristic features of these viruses are a small length of the tail compared with the diameter of the capsid and a complicated pattern of the tail sheath, leading to its criss-cross striation. In the presented article the major proteins were identified by means of the SDS-PAGE method: the head proteins (mp2: 33.9 kDa), the sheath (mp1: 39.2 kDa) and the tail tube ones (mp3: 19.9 kDa). It was proved that the mp2 molecular weight is the same with the gp46, the putative major capsid protein derived from the results of the genome sequencing. Therefore, it is still not determined whether the gp46 (mp2) of the virulent mutant 421 of the phage ZF40 is exposed to post-translational modification in the course of the phage particle maturation during its development in the cells of the strain M2-4/50RI P. carotovorum. To study the morphogenetic development pathways it was proposed to use the phage variants that form an excess of individual components of the virion: capsids, procapsids and separate tails propagated on different hosts. Source

On models of motoneurons of the n. abducens nucleus with reconstructed dendritic arborizations having an active membrane, we investigated features of the relationships between passive transfer properties and dynamics of excitation states of asymmetrical dendrites during generation of complex periodical and stochastic impulse patterns (output neuronal codes). Various patterns were obtained by varying the intensity of tonic synaptic excitation homogeneously distributed over the dendrites. The electrical states of sites belonging to branches of the same dendrite or different dendrites were compared. For this comparison, branches were selected, which, according to the earlier performed cluster analysis, were assigned to the groups (electrotonic clusters) with a high and a low effectiveness of passive transfer of the somatopetal current. The selection took into account features of the dendritic structure of neurons of the exemined type. These were: (i) the presence of groups of the asymmetrical branches differing from each other according to their belonging to different clusters (high or low transfer effectiveness) in different dendrites, and (ii) the presence of branches belonging to different dendrites characterized by significantly different orientations in three-dimensional space of the brainstem within each electrical cluster. Comparative analysis showed that, in a given dendrite during generation of a complex periodical pattern, the asymmetrical branches belonging to high- or low-efficiency clusters were characterized by being in different states (high or low depolarization) in different phases of generation of repeated sequences of action potentials (APs). This relationship was consistent with those previously detected in neurons of other types and in other specimens of neurons of the above-mentioned type. During generation of such periodical spike patterns, the branches of different dendrites belonging to the same electrotonic cluster were in similar states. Similar relationships between the states of the branches of the same dendrite belonging to different clusters were also observed during generation of complex stochastic (non-periodical) impulse patterns. In the latter case, however, the essential feature was that the branches of different dendrites belonging to the same electrotonic cluster were often in opposite states. Thus, the number of combinations of discrete electrical states of asymmetrical parts of the dendritic arborization was much greater. Probably, it is precisely this circumstance that determined the quasi-stochastic nature of the output impulse pattern. © 2012 Springer Science+Business Media, Inc. Source

The differences in the acid-base properties and nucleophilic reactivity within a series of 1-methyl-3-alkyl-2-(oximinomethyl)imidazolium halides in the dissociation of 4-nitrophenyl diethyl phosphate were analyzed. The positive deviation of points for comicellar systems derived from compounds of this series from the Brønsted plot was shown to be related to a decrease in the values of pKappa of the oximate fragment of the functional surfactants due to the action of the added cationic codetergent (CTAB). © 2011 Springer Science+Business Media, Inc. Source

Puzii A.M.,Ukrainian Academy of Sciences
Theoretical and Experimental Chemistry | Year: 2011

The paper presents a review of methods for the production of phosphorylated carbon adsorbents, their structure, and their physicochemical characteristics. It was shown that the phosphorylated carbons contain phosphoric acid residues (condensed phosphates) attached to the carbon matrix mainly by a C-O-P bond and, to a lesser degree, by a C-P bond. The presence of the condensed phosphates in the structure of the carbon determines the hydrophilicity and the acidic characteristics and also the ability to absorb cations. The acidic characteristics of the surface of the phosphorylated carbons gives rise to their high catalytic activity in acid catalysis. The presence of the phosphates/polyphosphates improves the electrochemical characteristics of carbon materials for use as electrodes in supercapacitors. Potential fields for the practical application of phosphorylated carbons are the purification of water from heavy metal ions, the acceleration of reactions of the acid-base type, and the accumulation and storage of energy in double-layer capacitors. © 2011 Springer Science+Business Media, Inc. Source

Larin V.B.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2016

The navigation problem for the simplest wheeled robotic vehicle is solved by just measuring kinematical parameters, doing without accelerometers and angular-rate sensors. It is supposed that the steerable-wheel angle sensor has a bias that must be corrected. The navigation parameters are corrected using the GPS. The approach proposed regards the wheeled robot as a system with nonholonomic constraints. The performance of such a navigation system is demonstrated by way of an example © 2016 Springer Science+Business Media New York Source

Goncharenko A.V.,Academia Sinica, Taiwan | Goncharenko A.V.,Ukrainian Academy of Sciences | Nazarov V.U.,Academia Sinica, Taiwan
Optics Express | Year: 2015

We show how to achieve a giant permittivity combined with negligible losses in both the visible and the near-IR for composites made of alternating layers of plasmonic and gain materials as the electric field is directed normally to the layers. The effects of nonlocality are taken into account that makes the method quite realistic. Solving the dispersion equation for eigenmodes of an infinite layered composite, we show that both propagating and nonpropagating modes can be excited, that leads to the realization of a giant nonlocal permittivity. Both phase and group velocities for the propagating eigenmode have been calculated showing that slow light can be achieved in the system under study. The results obtained open new possibilities for designing nanolaser, slow-light, superresolution imaging devices, etc. © 2015 Optical Society of America. Source

Berezovskyi O.A.,Ukrainian Academy of Sciences
Cybernetics and Systems Analysis | Year: 2012

The paper briefly reviews the well-known partial results on the accuracy of dual bounds proposed by N. Z. Shor for quadratic extremum problems. The necessary and sufficient condition for the accuracy of the dual bound for a quadratic problem of general form is presented. © 2012 Springer Science+Business Media, Inc. Source

Yesylevskyy S.O.,Ukrainian Academy of Sciences
Journal of Computational Chemistry | Year: 2012

An open-source Pteros library for molecular modeling and analysis of molecular dynamics trajectories for C++ programming language is introduced. Pteros provides a number of routine analysis operations ranging from reading and writing trajectory files and geometry transformations to structural alignment and computation of nonbonded interaction energies. The library features asynchronous trajectory reading and parallel execution of several analysis routines, which greatly simplifies development of computationally intensive trajectory analysis algorithms. Pteros programming interface is very simple and intuitive while the source code is well documented and easily extendible. Pteros is available for free under open-source Artistic License from. © 2012 Wiley Periodicals, Inc. Source

Khoroshun A.S.,Ukrainian Academy of Sciences
International Applied Mechanics | Year: 2016