East European Journal of Physics

5

Authors: P. I. Gladkikh, A. A. Kalamaiko, I. M. Karnaukhov, A. O. Mytsykov, A. Y. Zelinsky

NESTOR is the hard X-ray source that is under commissioning at NSC KIPT. NESTOR based on the Compton scattering of laser photons on relativistic electrons. The structure of the facility can be represented as the following components: a linear accelerator, a transport channel, a storage ring, and a laser-optical system. Electrons are stored in the storage ring for energy of 40-200 MeV. Inevitable alignment errors of magnetic elements are strongly effect on the beam dynamics in the storage ring. These errors lead to a shift of the equilibrium orbit relative to the ideal one. Significant shift of the equilibrium orbit could lead to loss of the beam on physical apertures. Transverse sizes of electron and laser beams are only few tens of microns at the interaction point. The shift of electron beam at the interaction point could greatly complicate the operation adjustment of storage ring without sufficient beam position diagnostic system. This article presents the simulation results of the efficiency of electron beam accumulation in the NESTOR storage ring. Also, this article is devoted to electron beam dynamics due to alignment errors of magnetic element in the ring.

7

Authors: A. E. Kokorev, V. M. Trusova, K. O. Vus, U. K. Tarabara, G. P. Gorbenko

Amyloid fibrils are highly ordered insoluble protein aggregates that are involved in molecular etiology of a number of severe disorders, including Alzheimer's, Parkinson’s and prion’s diseases, some types of systemic amyloidosis, etc. One of the most effective approaches to detecting the amyloid fibrils is based on monitoring the spectral behavior of specific fluorescent dye Thioflavin T (ThT). Using the molecular docking and molecular dynamics tools, such as PatchDock, FireDock, CreateFibril and GROMACS, the model of twisted K-peptide fibril that supposedly represent the core region of lysozyme amyloid fibrils, has been constructed and analyzed. The effect of fibril twisting angle on the binding characteristics of ThT has been evaluated. The results obtained strongly suggest that ThT specificity for the twisted ribbon fibril polymorphs is primarily determined by the curvature effects rather than amino acid composition of fibril grooveswhich accomodate ThT molecule.

8

Authors: Yu. V. Kulish, E. V. Rybachuk

It is shown that an integral corresponding to the contribution of one particle to equal-time commutator of quantized scalar fields diverges in a reality, contrary to usual assumption that this integral vanishes. It means that commutator of scalar fields does not vanish for space-like intervals between the field coordinates. In relation with this divergence the generalization of the Klein-Gordon equation is considered. The generalized equation is presented as products of the operators for the Klein-Gordon equation with different masses. The solutions of derived homogeneous equations are sums of fields, corresponding to particles with the same values of the spin, the electric charge, the parities, but with different masses. Such particles are grouped into the kinds (or families, or dynasties) with members which are the particle generations. The commutator of fields for the kinds of particles can be presented as sum of the products of the commutators for one particle and the definite coefficients. The sums of these coefficients for all the generation equal zero. The sums of the products of these coefficients and the particle masses to some powers equal zero too, i.e., for these coefficients some relations exist. In consequence of these relations the commutators of the fields for the particle generations vanish on space-like intervals. Thus, the locality (the microcausality) is valid for the fields of the particle kinds. It is possible if the number of the generations is greater than two.

11

Authors: V. B. Ivanskyi, O. N. Letuchyy, А. N. Orobinskyi, V. E. Ostrovskykh, H. V. Siroko

The energy and pulse height spectrums after passage of neutron radiation through samples of materialsmost often used to protect against neutron radiation (paraffin, paraffin with boric acid, paraffin with boric acid and lead, polyethylene, polyethylene with boron and boron carbide) are measured using a PuBe neutron source using a NEMUS spectrometer on Bonner spheres with 3He -counter. The values of linear attenuation coefficients and neutron relaxation lengths in these materials, neutron spectra for these materials are given. The percentage of neutrons in the energy subbands is determined according to the radiation weighting factor. The neutron flux density, the ambient dose equivalent power, the absorbed dose rate in the neutron radiation air, the transition coefficients from the neutron fluence to the ambient dose equivalent and average neutron radiation energy are measured. Calculation of energy spectrum, basic characteristics of neutron radiation and extended uncertainties is performed by the MAXED (maximum entropy and deconvolution), applying the Bayes theorem, method using the UMG_3.3 software.

12

Authors: V. Trusova, G. Gorbenko, U. Tarabara, K. Vus, O. Ryzhova

The protolytic and partition equilibria of the indicator dyes in the model lipid and protein-lipid systems have been analyzed. A methodological approach has been developed allowing the partition coefficients of the protonated and deprotonated dye forms to be derived from the spectrophotometric measurements. The partitioning of the indicator dye bromothymol blue into the model bilayer membranes composed of phosphatidylcholine and cardiolipin (9:1, mol:mol) has been examined. The partition coefficient of the protonated dye species into a lipid phase has been found to be 5 orders of magnitude higher than that of the deprotonated dye form. This effect has been interpreted in terms of the differences in the charge distribution over the protonated and deprotonated dye ions, preventing the hydrophobic dye-lipid interactions in the latter case. The reduction of the bromothymol blue partitioning into lipid bilayer in the presence of hemoglobin has been attributed to the protein-induced changes in the structure and physicochemical characteristics of the interfacial membrane region. In the practical aspect, the obtained findings may prove of significance in the design of hemosome-based blood substitutes and elucidating the role of hemoglobin in the molecular etiology of the amyloid disorders, particularly, Alzheimer's disease.

5

Authors: I. M. Pankratov, V. Y. Bochko

The energy of disruption generated runaway electrons can reach as high as tens of megaelectronvolt and they can cause a serious damage of plasma-facing-component surfaces in large tokamaks like International Thermonuclear Experimental Reactor (ITER). The synchrotron radiation diagnostic allows a direct observation of such runaway electrons and an analysis of their parameters and promotes the safety operation of present day large tokamaks and future ITER. Only this diagnostic will be applied in ITER. In the paper detail analysis of the synchrotron radiation spectra of runaway electrons for the recent Experimental Advanced Superconducting Tokamak (EAST, Institute of Plasma Physics of Chinese Academy of Sciences) experiment parameters has been presented. The calculations are carried out on the base of precise expression for synchrotron radiation spectral density. They make more precise spectra analysis of the previous paper by Zhou R.J., Pankratov I.M., Hu L.Q., et al. (Physics of Plasmas, 2014, Vol. 21, No. 6, 063302). Obtained results are important for correct interpretation of runaway EAST experiments and runaway experiments in other tokamaks.

5

Authors: V. G. Kirichenko, V. A. Kobylnik, T. A. Kovalenko, O. A. Usatova

The study of phase transformations in intermetallic phases, which are released in the form of fine-dispersed inclusions in binary alloys based on zirconium Zr - 1.03 at. % Fe; Zr - 0.51 at. % Fe; after ion irradiation and subsequent isothermal annealing was carried out. Mössbauer spectroscopy on 57Fe nuclei in backscattering geometry with registration of internal conversion electrons, X-ray spectral analysis, X-ray diffraction analysis and electron microscopy were used. As a result, the observed segregation and phase composition of the intermetallic phases in the surface layer change under ion irradiation. Subsequent isothermal annealing after irradiation leads to a change in the concentration of inclusions of intermetallic phases and phase modification in the surface layer.

6

Authors: O. A. Bizyukov, O. D. Chibisov, O. I. Kutenko

The evaporation possibility of micro sized metallic particles during them passage through the region of a magnetized plasma with a Maxwellian velocity distribution with the electron temperature in the range Te=1...100eV at presence of an ion beam with the energy in the range εb=1...6keV is studied theoretically. The floating potential of a macroparticle is obtained using the OML theory, the effect of the electron temperature and the energy of the ion beam on its magnitude is studied. The equation of energy balance on the macroparticle surface is obtained, such energy exchange mechanisms as collisions of particles of an ion beam and plasma particles with the macroparticle, thermal radiation of the macroparticle, as well as cooling due to the evaporation of substance from the macroparticle surface are taken into account. The effect of the temperature of plasma electrons and the ion beam energy on the stationary temperature of the macroparticle is studied. It is shown that for the given plasma and ion beam parameters, the temperature of the copper macroparticle is below the boiling point so that the evaporation of the macroparticle occurs at temperatures below the boiling point. The dependences of the macroparticle evaporation time on the electron temperature and the energy of the ion beam have been obtained.

7

Authors: V. M. Svishch

The entrainment of the light flux by a uniaxial anisotropic medium and its influence on the measurement of stellar aberration are analyzed. The influence of the entrainment of the light flux by an isotropic medium on the measurement of stellar aberration was considered by Fresnel early. The absence of such influence was confirmed by Erie's experience when filling the telescope tube with water. The formula itself was perfectly confirmed by Fizeau's experiments with moving water and the repetition of this experiment with an increase in the accuracy of measurements by Michelson, Zeeman, and others. G.A. Lorentz already on the basis of the electromagnetic theory specified the formula with allowance for the frequency dispersion of the light flux. A. Einstein made an analysis of the schemes of experiments for determining the drag coefficient, covering all possible variants of similar experiments. As a result, he obtained Fresnel and Lorentz formulas, taking into account the frequency dispersion of light, starting from the theory of relativity. The entrainment of light and its influence on the measurement of stellar aberration by a uniaxial anisotropic medium have not been considered anywhere. An analysis of such influence is carried out. The results of the analysis indicate the possibility of measuring the current value of stellar aberration using a uniaxial anisotropic medium. The concept of active light aberration is introduced. The proposed schemes of experiments of using the entrainment of a light flux by an anisotropic substance for measuring the current value of stellar aberration are investigated. It is concluded that it is possible to study the determination of the current velocity of an inertial system relative to the light flux.

7

Authors: P. I. Gladkikh, A. A. Kalamaiko, I. M. Karnaukhov

NESTOR is the hard X-ray source that is under commissioning at NSC KIPT. NESTOR based on the Compton scattering of laser photons on relativistic electrons. The structure of the facility can be represented as the following components: a linear accelerator, a transport channel, a storage ring, and a laser-optical system. Electrons are stored in the storage ring for energy of 40-225 MeV, laser photons are accumulated in the optical resonator. The frequencies of laser and electron bunches are synchronized, the interaction point located in the optical resonator. The measurements showed that parameters of the manufactured bending magnets different from the design ones. The bending magnets have different field index, besides the vertical focusing forces are significantly lower than designed ones. The beam dynamics simulation showed that due to decreasing of the vertical focusing the vertical betatron frequency becomes close to the frequency of the integer resonance Q = 2, as a result the vertical motion in the ring is unstable [1]. The second reason for optimization is the need to increase the length of the drift space for optical resonator. The results of optimization are presented in this paper.

8

Authors: K. Vus, U. Tarabara, K. Semenova, V. Viter, O. Nikitina, V. Trusova, G. Gorbenko

The applicability of Auramine O to the detection and characterization of lysozyme and serum albumin amyloid fibrils has been assessed using the fluorimetric titration and molecular docking. The parameters of the dye binding to native and fibrillar proteins were estimated in terms of the Langmuir adsorption model. It was found that Auramine O displays the high affinity for amyloid fibrils, being of the same order of magnitude as that of the classical amyloid markers. The dye also showed greater fluorescence response to lysozyme fibrils and lower sensitivity to the native protein, than Thioflavin T. Furthermore, unlike Thioflavin T, Auramine O was able to detect the morphological differences between lysozyme and albumin fibrils due to the shifts in the position of the emission maxima of the fibril-incorporated fluorophore. The molecular docking studies revealed that Auramine O and Thioflavin T form the most stable complexes with the G54_L56/S60_W62 groove of lysozyme fibrils, running parallel to the fibril axis. The results obtained suggest the contribution of both hydrophobic and electrostatic interactions to the stabilization of the dye complexes with amyloid fibrils.

14

Authors: Yu. M. Poluektov, A. A. Soroka

For the ideal Fermi gas that fills the space inside a cylindrical tube, there are calculated the thermodynamic characteristics in general form for arbitrary temperatures, namely: the thermodynamic potential, energy, entropy, equations of state, heat capacities and compressibilities. All these quantities are expressed through the introduced standard functions and their derivatives. The radius of the tube is considered as an additional thermodynamic variable. It is shown that at low temperatures in the quasi-one-dimensional case the temperature dependencies of the entropy and heat capacities remain linear. The dependencies of the entropy and heat capacities on the chemical potential have sharp maximums at the points where the filling of a new discrete level begins. The character of dependencies of thermodynamic quantities on the tube radius proves to be qualitatively different in the cases of fixed linear and fixed total density. At the fixed linear density these dependencies are monotonous and at the fixed total density they have an oscillating character.

7

Authors: A. V. Glushchenko, M. Y. Kovalevsky

The paper studies the dynamic description of non-equilibrium processes in single-sublattice and multisublattice magnets with the spin s=1. In case of magnets with the spin s=1 and SU(3) symmetry of the exchange interaction, there are eight magnetic integrals of motion: the spin and the quadrupole matrix. If there are multiple sublattices, the number of additional magnetic quantities characterizing the state increases to sixteen. The presence of the Casimir invariants makes it possible to reduce the number of independent degrees of freedom. Exchange energy models are presented in terms of Casimir invariants corresponding to SO(3) or SU(3) symmetry groups for all four types of magnetic degrees of freedom. For the homogeneous part of the exchange energy, we have found conditions for the existence of local minima, which correspond to equilibrium values of the magnet. Along with the known waves (quadrupole and Goldstone – for the spin nematic), spectra of collective excitations that take into account ferro-quadrupole excitation, quadro-nematic, quadro- antiferromagnetic, and antiferro-nematic waves excitation, are also obtained. In the case of many-sublattice magnetic systems, we have shown that the selected form of the homogeneous energy model allows us to find possible magnetic orderings and to investigate them for stability.

8

Authors: D. S. Bondar, I. P. Levchuk, V. I. Maslov, I. N. Onishchenko

Earlier, the authors found a mechanism for the sequence of short relativistic electron bunches, which leads to resonant excitation of the wakefield, even if the repetition frequency of bunches differs from the plasma frequency. In this case, the synchronization of frequencies is restored due to defocusing of the bunches which get into the bad phases with respect to the plasma wave. However, in this case, the bunches are lost, which as a result of this do not participate in the excitation of the wakefield. In this paper, numerical simulation was used to study the dynamics of electron bunches and the excitation of the wakefield in a magnetized plasma by a long sequence of short bunches of relativistic electrons. When a magnetic field is used, the defocussed bunches return to the region of interaction with the field after a certain time. In this case, the electrons of the bunches, returning to the necessary phases of the field, participate in the excitation of the wakefield. Also, the use of a magnetic field leads to an increase of the frequency of the excited wave relative to the repetition frequency of bunches. The latter increases the time for maintaining the resonance and, consequently, leads to an increase of the amplitude of the excited wakefield.

8

Authors: O. Ivashtenko

The greenhouse is a tool for the accumulation of solar energy and its conversion into heat. The article investigates the heating of the greenhouse caused by the difference in the transmissivity of glass in different wavelength ranges. Firstly, some facts from the history of the phenomenon investigation are presented. The principle of greenhouse operation is considered. Then we explain the greenhouse effect theoretically using a simplified model, and carry out an experiment. In our experiment, the heating of a 1 m² surface greenhouse model has been observed. The temperature changes have been registered, and the ultimate temperature has been measured. Further, a model of an ideal greenhouse is proposed in order to reduce heat losses. The main principles and generalizations of the greenhouse effect are discussed. The role of the glass transmission spectrum, which is one of the most important factors determining the maximum temperature is investigated. Maximum temperatures for different spectra are compared. We calculate theoretically the maximum temperature, which can be achieved in an ideal greenhouse under ideal conditions. Then we consider other factors limiting temperature growth. Finally, the ways of application of the greenhouse effect in the development of solar collectors are indicated.

10

Authors: U. Tarabara, K. Vus, S. Girnyk, N. Kamneva, O. Lavryk, M. Mikhailyuta, V. Trusova, G. Gorbenko

The influence of the lysozyme and serum albumin in their native and amyloid forms on the electrokinetic behavior of the negatively charged uni- and multilamellar liposomes from the zwitterionic lipid phosphatidylcholine and anionic lipid cardiolipin has been investigated using the microelectrophoresis technique. The zeta - potential, the surface electrostatic potential and surface charge density of the lipid vesicles have been determined upon varying the lipid-to-protein molar ratio. The complex dependencies of the electrophoretic mobility on the protein concentration and reversal of the surface charge observed for the multilamellar vesicles have been explained by the multilayer protein adsorption on the liposomal surface. It has been found that the native and fibrillar proteins differ in their ability to modify the charge state of the model membranes.

13

Authors: V. B. Ivanskyi, O. N. Letuchyy, А. N. Orobinskyi, H. V. Siroko

The energy and pulse height spectrum of PuBe and 238PuBe neutron sources are measured without taking into account scattered radiation, taking into account this radiation (without the shadow cone) and own scattered radiation from these sources (with a shadow cone) using a NEMUS spectrometer on Bonner spheres with 3He -counter. An analytical solution of the likelihood function equation is given, taking into account the fact that the counting rate of pulses obeys the chi-square distribution used to estimate the variances, the discrete Poisson distribution, and the normal distribution, using the Bayes theorem and the Lagrange multiplier method. The values of the main characteristics of neutron radiation are measured: neutron flux density, ambient dose rate equivalent, individual dose rate equivalent and average neutron radiation energy. Extensive uncertainties were obtained in the measurement of these characteristics with a confidence level of 0.95. Calculation of energy spectrum, basic characteristics of neutron radiation and extended uncertainties is performed by the MAXED (maximum entropy and deconvolution) method using the UMG_3.3 software.

5

Authors: A. V. Levenets, I. V. Kolodiy, N. V. Berezhnaya, Y. S. Lipovskaya

The structure and mechanical properties of high-entropy CoCrFeMnNi (equiatomic) and Co20Cr26Fe20Mn20Ni14 alloys, which differ significantly in the stacking-fault energy, are studied. The structure of the alloys was investigated in three states – as-cast, after homogenizing annealing at T = 1000 °C for 24h and after annealing at T = 850 °C. It was found that in the cast state and after homogenizing annealing at 1000 °C both alloys are single-phase solid solutions with a FCC lattice. Annealing at 850 °C preserves the single-phase state in the equiatomic CoCrFeMnNi alloy, but leads to the appearance of a σ-phase in the Co20Cr26Fe20Mn20Ni14 alloy. The mechanical properties of these alloys were studied in a single-phase state by uniaxial compression tests and hardness measurements. It was discovered, that both alloys in a single-phase state had high plasticity and tendency to force strain hardening. The behavior of hardening coefficients in the area of true strains e = 0.05 – 0.17 vary considerably. This may be due to a significant difference in the stacking-fault energy of the investigated alloys. As a result, in Co20Cr26Fe20Mn20Ni14 alloy along with dislocation deformation mechanism there is a high probability of implementation the twinning mechanism.

8

Authors: V. N. Bondarenko, A. V. Goncharov, V. I. Sukhostavets, T. Kh. Salikhov, A. A. Abdurahmonov

A technique for infrared thermometry remote monitoring of temperature of area of a polymer film under ion irradiation is described. Calculation part of the technique takes into account the case when the irradiated area is significantly smaller than the instrument field of view. Temperature measurements were carried out with 20 μm polyimide films irradiated by 1000 to 1600 keV protons, with 1…5 μA/cm2 current density. A model for calculation of temperature depth distribution in the irradiated film is developed. The model is also applicable for the case of ion irradiation in gaseous atmosphere, and takes into account temperature dependence of the polymer substance thermal conductivity, of the emissivity coefficient, and of the convective heat transfer coefficient. The calculated data are compared with the temperature measurements.

10

Authors: V. M. Kuklin, D. N. Litvinov, S. M. Sevidov, A. E. Sporov

In this paper, the self-consistent model was considered, consisting of a system of oscillators, the coupling between them was assumed to be integral (due to the fields formed as a result of their co-radiation). With the help of this model, the features of synchronization by waves of finite amplitude of a system of oscillators were refined, the initial phase values of which are random. The effect of nonlinearity, in particular, due to the change in the mass of the oscillator due to relativistic effects, was taken into account. It was shown that the nonlinearity does not violate the nature of the energy exchange between the wave and the oscillator system, leading only to a slight decrease in the efficiency of such an exchange.

24

Authors: M. I. Kopp, A. V. Tur, V. V. Yanovsky

We found a new large-scale instability, which arises in the rotating conductive fluid with small-scale turbulence. Turbulence is generated by small-scale external force with a low Reynolds number. The theory is built simply by the method of multiscale asymptotic expansions. Nonlinear equations for vortex and magnetic perturbations obtained in the third order for small Reynolds number. It is shown that the combined effects of the Coriolis force and the small external forces in a rotating conducting fluid possible large-scale instability. The large-scale increments of the instability, correspond to generation as the vortex and magnetic disturbances. This type of instability is classified as hydrodynamic and MHD alpha-effect. We studied the stationary regimes of nonlinear equations of magneto-vortex dynamo. In the limit of weakly conducting fluid found stationary solutions in the form of helical kinks. In the limit of high conductivity fluid was obtained stationary solutions in the form of nonlinear periodic waves and kinks.