bluuebunny/crossref_metadata_2025 huggingface dataset:
Equation of state and composition of the inner crust of an accreting neutron star: multicomponent model
Authors: Shchechilin N N , Chugunov A I
Published: December 2019

Correct interpretation of X-ray observations of transiently accreting neutron stars requires modeling of nuclear-physical processes in these objects. We consider a chain of nuclear reactions that drives the crust composition in an accreting neutron star and heats up the star. We constructed multicomponent approach with the kinetics of nuclear reactions described in simplified stepwise manner. The redistribution of nucleons between nuclei by emission and capture of neutrons is shown to significantly affect the nuclear reaction chains and the composition of the inner crust. In particular, even if the outer crust has one-component composition, the appearance of free neutrons in the inner crust leads to branching of reaction chains and formation of the multicomponent composition. We apply the compressible liquid drop nuclear model, which includes effects of free neutrons on nuclear energies. It allows us to calculate the composition, the heating profile and the equation of state of matter up to densities ρ ≃ 2 × 1013 g cm−3.
Chandra measurements of the proper motion of the γ-ray pulsar J0633+0632
Authors: Danilenko A A , Karpova A V , Shibanov Yu A
Published: December 2019

We measured the proper motion of a γ-ray radio-quiet pulsar J0633+0632 using Chandra observations performed in 2009 and 2017. The measured proper motion is 53 ± 15 mas yr−1. We found that the proper motion direction does not follow the extension of the J0633+0632 pulsar wind nebula. The J0633+0632 pulsar wind nebula therefore can be a jet-like feature or a misaligned outflow. We also discuss a possible birth cite of the pulsar.
Analysis of the surfaces and gravitational fields of planets using robust modeling methods
Authors: Demina N Y , Andreev A O , Nefedyev Y A , Akhmedshina E N , Demin S A
Published: December 2019

The work focuses on the development of methods and algorithms for the simulation of celestial bodies’ dynamic and static states. There are 2 types of models: global and local ones. The creation of local simulation models (LSM) is complicated as the emergent properties of the system are getting lost. Nevertheless, LSM are of great importance when analyzing planetology processes. When areas are covered with reference points unevenly and the distance between them increases, the method used in the work provides the higher accuracy of model forecasting compared to the use of interpolation formulas. LSM allow investigating both the whole planetary system and its local parts and are aimed at the predictive determination of topographic, gravimetric, and magnetic parameters.
Jeans smoothing of the Ly forest absorption lines
Authors: Telikova K N , Balashev S A , Shternin P S
Published: December 2019

We investigate a contribution of the Jeans smoothing to the minimal width of Ly forest lines and discuss how the accounting for this additional broadening affects the inferred parameters of the intergalactic matter equation of state. We estimate a power-law index γ of the equation of state, a temperature at the mean density T
0 and a hydrogen photoionization rate Γ within 4 redshift bins. Furthermore, in each bin we obtain an upper limit on the scale-parameter f
J, which sets the relation between the Jeans length and the characteristic physical size of the absorber clouds.
Two tori of the Vela pulsar wind nebula
Authors: Ponomaryov G A , Levenfish K P , Petrov A E
Published: December 2019

In the frame of the axisymmetric relativistic magnetohydrodynamic simulations we show that the double-arc feature of the Vela pulsar wind nebula (PWN) visible in soft X-rays can be reproduced at high inclination (obliquity) of the Vela pulsar and low magnetization of its wind provided the turbulent and magnetic energies of the nebula dissipate effectively. In that case, the arcs represent the Doppler brightened regions of two persistent large-scale toroidal whirls of strongly magnetized plasma located below and above the wide low-magnetized equatorial belt of the nebula. If the long-term persistence of the large-scale magnetic structures would be confirmed in more realistic simulations, the difference in X-ray morphology of the Crab and Vela PWNe can be explained by the difference in spin-down and inclination of their parent pulsars, and not by the very different magnetization of their winds, as supposed earlier.
X-ray of the 2017 September 10 Solar Flare
Authors: Ovchinnikova E P , Charikov Yu E , Shabalin A N
Published: December 2019

The analysis of soft and hard X-ray radiation of behind the limb solar flare SOL2017-09-10T15:35 according to the RHESSI data was carried out. The plasma parameters were determined: emission measure, temperature, density. Sources of hard X-ray radiation >30 keV are observed for several hours after the maximum of the flare. It indicates the long-term processes of acceleration of electrons in the solar corona. The rise of the X-ray source during 6.5 hours was ∼70 arcsec. It was proposed also an alternative method for determining the plasma density, based on cross-correlation analysis of time series (time delay method).
R-mode stabilization in neutron stars with hyperon cores
Authors: Ofengeim D D , Gusakov M E , Haensel P , Fortin M
Published: December 2019

R-mode oscillations of neutron stars are known to be generally unstable with respect to the emission of gravitational waves. This instability can be suppressed by dissipative processes in the neutron star core. The standard minimal nucleonic model of the core cannot stabilize r-modes for many observed neutron stars, at the same time the probability to observe them unstable should be very low. One of the solutions to this problem is to account for possible presence of hyperons in the stellar core. Hyperons strongly enhance bulk viscosity in the core, which effectively suppresses the r-mode instability. We revisit the bulk viscosity calculations in the non-superfluid hyperon matter and briefly discuss the effect of baryon superfluidity. Our results suggest that the hyperon solution to the r-mode problem is more promising than it was thought before.
The cold neutral phase of the interstellar medium in high redshift galaxies
Authors: Balashev S A , Klimenko V V , Noterdaeme P , Krogager J K , Ledoux C , Ivanchik A V , Varshalovich D A , Petitjean P
Published: December 2019

We present the results of spectroscopic analysis of seven new H2-bearing damped Ly- systems in redshift range z=2.5 − 3. These systems were originally selected from SDSS catalog using a direct search for H2 and followed up with X-SHOOTER spectrograph at 8-m Very Large Telescope observatory. We measured the column densities of HI, H2 on various rotational levels, and metals species in different ionization stages and excitation levels. We used the rotational excitation of H2 molecules together with the fine-structure levels of neutral carbon to constrain the physical conditions in the associated medium. We found typical values for the kinetic temperature T ∼ 80 − 120 K, hydrogen density n
H
∼ 30 − 400 cm−3 and UV radiation field ξUV
∼ 0.4 − 5 times of the Draine field. These values along with estimated thermal pressure are in agreement with expected values from the theoretical calculation of the cold neutral interstellar medium.
Kerr black hole shadow: non-parametric description and analytic methods of spin extraction
Authors: Kraav Kirill
Published: December 2019

In this paper we study the asymmetry of the shadow cast by a rotating Kerr black hole. Using Bardeen parametric formulas we plot contours of black hole shadows for different values of black hole’s angular momentum and different observer’s positions. In the case of the equatorial observer we present an equation that explains the behaviour of the numeric Hioki-Maeda curve, which is used to measure the black hole angular momentum from it’s shadow. Also in this case we introduce a new observable of the shadow and derive a simple formula that allows to constrain the black hole spin via measuring this observable. Finally we come out with the formula that provides the non-parametric description of the black hole shadow.
Influence of non-gravitational effects on the orbits of a few potentially hazardous asteroids
Authors: Martyusheva A
Published: December 2019

Observations of Mars and Venus-crossing asteroid (5131) 1990 BG and the near-Earth approaching asteroid (13553) Masaakikoyama 1992 JE were made using ZA-320M and MTM-500M telescopes of the Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo. Evolution of their orbits was investigated taking into account the Yarkovsky effect, as well as the solar radiation pressure influence for various values of albedo of these objects. The obtained results were summarized and compared with results of the Yarkovsky effect for (308635) 2005 YU55, (418094) 2007 WV4, 2017 VR12 and (276033) 2002 AJ129, which had been studied earlier. Conclusions about non-gravitational effects on the motion of potentially hazardous asteroids were drawn.
Geophysical effects of solar activity: long-term variations in occurrences of magnetic storms with sudden and gradual commencements
Authors: Veretenenko S , Ogurtsov M , Obridko V
Published: December 2019

Magnetic storms with sudden and gradual commencements are related to different agents of solar activity and form two independent populations. Coronal mass ejections which are more frequently related to active regions on the Sun (local magnetic fields with closed configuration) give rise, as a rule, to magnetic storms with sudden commencements. High-speed streams of solar wind related to solar coronal holes (regions of magnetic fields with open configuration) give rise to magnetic storms with gradual commencements. In this work we studied annual occurrences of magnetic storms with sudden and gradual commencements on the base of the data from IZMIRAN and Slutsk (Pavlovsk) magnetic observatories for the period 1878-2015, the correlation and spectral analysis being used. It was found that the occurrences of large and moderate magnetic storms with gradual commencements are characterized by long-term variations at the multidecadal and secular time scales. Wavelet spectra of occurrences of these storms reveal a dominant periodicity of ∼36 years (close to the Brückner cycle) and less pronounced ∼60-year and ∼90-year periodicities on the entire time interval under study. It was found that ∼11-year variations in occurrences of storms with gradual commencements were the most statistically significant in ∼1900-1920 and ∼1980-2000, but they were not observed in ∼1940-1960. The occurrence of magnetic storms with sudden commencements is characterized by a dominant ∼11-year periodicity almost on the entire interval of observations, whereas long-term variations are less pronounced. The obtained results provide evidence for a different time evolution of global and local solar magnetic fields.
The X-ray polarimeter of solar flares for the Interhelioprobe mission: a study of the characteristics of the physical model using radioisotope radiation sources
Authors: Savchenko M I , Kruglov E M , Lazutkov V P , Skorodumov D V , Shishov I I
Published: December 2019

The paper describes the physical model of the PING-P polarimetry unit of the PING-M X-ray polarimeter. The polarimeter is developed jointly by the Ioffe Institute and the Institute of Astrophysics of the Moscow Engineering Physics Institute for the Interhelioprobe mission. The model (PING-P-FM), made by the Ioffe Institute, represents the detector part of the polarimeter. The polarization degree is determined by the measurement of the asymmetry of the scattered radiation field. The device uses active scatterers based on paraterphenyl crystals for detecting the events of Compton scattering. A useful signal is the coincidence of pulses from one of the active scatterers (detector-scatterer) and one detector-receiver of scattered radiation. The polarimetry unit contains 3 detector-scatterers and 6 detector-receivers, thus resulting in 18 measurement channels. The requirements for instrument symmetry and stability of the measuring channels are high. The paper presents the results of an experimental study of the parameters of the measuring channels of the PING-P-FM model and their calibrations at different X-ray energies using Cd-109, Am-241, and Ba-133 isotope sources.
Gamma-ray lines in solar flares with proton spectra measured by PAMELA experiment
Authors: Lysenko A L , Bogomolov E A , Vasiliev G I , Ovchinnikova E P
Published: December 2019

During the solar flares protons and heavier ions are accelerated up to GeV energies. Accelerated ions can escape the Sun and be registered directly on spacecraft or penetrate into the solar atmosphere and then produce gamma-ray lines as the result of nuclear reactions. Previous studies revealed very poor correlation between fluxes of interplanetary ions and gamma-ray line emission. In this work we focus on joint observations of interplanetary solar energetic particles registered by PAMELA experiment and gamma-ray emission registered by Konus-Wind instrument in hard X-ray and soft gamma-ray ranges. This study confirmed the previous results: during the period from 2006 to 2014 there were only two solar flares registered both by PAMELA and Konus-Wind at energies above 1 MeV. We analyze gamma-ray spectrum for one of these flares and make suggestions about the reasons for the low correlation between interplanetary solar accelerated ions and accelerated ions interacted in the solar atmosphere.
Analysis of the dynamic coordinate system using photoelectric lunar occultations
Authors: Churkin K O , Andreev A O , Nefedyev Y A , Mubarakshina R R , Borovskih V S
Published: December 2019

In this work we propose the determination of the astrophysical dynamic coordinate system’s orientation in relation to HCRF (Hipparcos Celestial Reference Frame) using photoelectric lunar occultation. The photoelectric method of recording an occultation that allows obtaining occultations moment with the accuracy up to 0.001s (i.e. 100 times more accurate than by visual method) was found to be the most accurate. Apart from the tasks of space geodesy, photoelectric observations allow carrying out other interesting researches, too. These tasks include determination of amendments to orbital longitude and latitude of the Moon and amendments to ephemeris time. The photoelectric observations of occultation are valuable materials for solving some astrophysical tasks. If one records changes in magnitude at the moment when a star is occultated by the Moon, then one may obtain diameter of the occultated star through the spectrum of those changes. Other important problems are detecting double and multiple systems of stars and measuring angular distances between their components.
Genetic analysis of the meteor showers and asteroids
Authors: Sergienko M V , Sokolova M G , Andreev A O , Nefedyev Y A
Published: December 2019

Using the video catalogues of the Perseids, Ursids, and Lyrids meteor showers having genetic connections with comets, the Geminids, Alpha Capricorni, and Taurids having genetic connections with asteroids, and the Kappa Cygnids and Delta Cancrids of unknown origin, the objects with magnitude higher than +3 were studied. The analysis of coordinates of the meteor showers’ radiant distribution in relation to their magnitudes showed that the Lyrids has the smallest ellipse of the spread of the radiant positions, with 4° by 8°; for the k-Cygnids the deviation is the greatest, with 28° by 28°; for the other showers, it is between 7° and 10°. The main attention is paid to the determination of structural parameters of the Lyrids meteor shower.
Deep minima of the Sun’s activity according to data of solar paleoastrophysics
Authors: Ogurtsov M G
Published: December 2019

Twenty paleoreconstructions of the Sun’s activity, obtained using the data on both cosmogenic isotopes and auroral records, are generalized over a time interval 1402-1850. Final reconstruction of sunspot number is obtained by means of normalization of the generalized record by the instrumentally measured seriesSN. Comparison of average levels of solar activity during the periods of solar minima of Spoerer (1415-1545), Maunder (1645-1715) and Daltona (1792-1827) is made. Discussion of the results is presented.
Microwave frequency standard on Hg-199 ions for space stations and vehicles
Authors: Lukashev N A , Davydov V V , Rud’ V Yu
Published: December 2019

In the paper the design of a magnetic trap for low mass-dimensional microwave frequency standards is presented. The dependencies between the number of registered photons by PMT and magnetic field values are established. The new algorithm for optical processing is developed. For different designs of microwave standard on 199Hg+ ions the results comparison of experimental Allan deviation researches is performed.
Fluorescent labeling of bacteriophage T7 by CRISPR-Cas9
Authors: Znobishcheva E A , Morozova N E , Khodorkovskii M A
Published: December 2019

The objective of this work was to develop a simple method for coupling a fluorescent protein with a bacteriophage capsid. The Escherichia coli bacteriophage T7 was chosen as a model one. The method, based on CRISPR-Cas9 system and the λ-Red recombination, allowed to insert the gene of enhanced yellow fluorescent protein into the phage genome.
Study of the dependence of the structural defects and bulk inhomogeneities of nanocrystalline hydroxyapatite on the conditions of production using a biological source of calcium
Authors: Goloshchapov D L , Savchenko D V , Kashkarov V M , Khmelevskiy N O , Aksenenko A Yu , Seredin P V
Published: December 2019

The study of structural and bulk defects in nanocrystalline samples of hydroxyapatite with a developed surface was carried out. The XRD method established distortions in the crystal lattice of the synthesized samples of hydroxyapatite (HAP), which are associated with the inclusion of impurity atoms present in the eggshell of birds used as a biological source of calcium. The presence of impurity atoms of magnesium, sodium, and fluorine in the obtained materials was determined by X-ray photoelectron spectroscopy. Applying ESR and Raman spectroscopy it was found the presence of CO3 complex in the structure. Studies of the morphological organization of the samples found a large number of surface defects – nanopores – in crystalline HAP. At the same time, the size of these 3D defects depends on the conditions of preparation and is determined by the content of phosphate groups in the initial solution.
Epileptic seizures regularities, revealed from encephalograms time series by nonlinear mechanics methods
Authors: Hilarov V L
Published: December 2019

Recurrence quantification analysis and multifractal method were used for investigation of the encephalograms time series of the children with epileptic seizures. It has been shown that epileptic seizures are accompanied by an increase in determinism of the brain electric process due to neuron activity synchronization. This behavior is typical for nonlinear systems catastrophes of different nature
Magnetic beads-based nucleic acids extraction in microfluidic chip
Authors: Afonicheva P K , Esikova N A , Tupik A N , Evstrapov A A
Published: December 2019

The dominant trend in molecular genetic methods research of biological samples is the automation of all stages, the most valuable of which is preparation of the sample. The use of microfluidic technologies provides not only full control of all operations at this stage, but also reduces the impact of the environment on the sample preparation process. Magnetic beads technology is one of the methods for extracting RNA and DNA with subsequent analysis. The paper presents magnetic beads-based nucleic acids extraction in the microfluidic chip via automatic mode with further registration by real-time polymerase chain reaction. We have shown that efficiency of DNA extraction in microchip is compared to that in case of conventional manual extraction and allows further improvement by means of automation.
Interaction of thermally evaporated dipeptides with keV-energy α-particles
Authors: Basalaev A A , Buzykin A G , Kuz’michev V V , Panov M N , Smirnov O V
Published: December 2019

Fragmentation of isolated molecular ions of dipeptides produced by alpha-particles was studied by an experimental technique based on time-of-flight analysis of the charge and mass composition of the fragment ions. The study has shown that the N-Glycylglycine sublimation results in the molecule decomposition into cyclo(GlycylGlycyl) and H2O molecule. We have examined a mass-spectrum of the fragments arising in the cyclo(GlycylGlycyl) interaction with α-particles. By analyzing the temperature dependence of the cyclo(GlycylGlycyl) vapor pressure, we have determined sublimation enthalpy ΔHsubl(453K) = (213 ± 9) kJ/mol.
In vivo optical clearing of human skin under the effect of aqueous solutions of some monosaccharides
Authors: Berezin K V , Dvoretsky K N , Chernavina M L , Nechaev V V , Likhter A M , Shagautdinova I T , Antonova E M , Tuchin V V
Published: December 2019

The results of in vivo optical immersion clearing of human skin under the effect of aqueous solutions of some immersion agents (monosaccharides of ribose, glucose and fructose, as well as glycerol, a triatomic alcohol) were obtained with the use of the OCT method. Values of average velocity of scattering coefficient change, obtained through an averaged A-scan of the OCT signal in the region of derma with the depth of 350 to 700 µm, were determined to evaluate the optical clearing efficiency. The velocity of scattering coefficient change and the optical clearing potential value appeared to be well correlated. The complex molecular modeling of a number of immersion clearing agents with a mimetic peptide of collagen (GPH)3, carried out with the use of the methods of classical molecular dynamics and quantum chemistry, allowed to identify correlations between the optical clearing efficiency and the energy of intermolecular interaction of clearing agents with a collagen peptide fragment.
Regulation of type II restriction-modification system Esp1396I
Authors: Antonova D A , Morozova N E , Shiryaeva A A , Khodorkovskii M A
Published: December 2019

Fluorescence microscopy is a powerful tool which enables to observe a large number of processes at the level of single cells. A protein of interest could be selectively labeled using fluorescent proteins, thereby allowing direct observation of its accumulation in living cells. This work is devoted to study a restriction-modification system which is a protective system of bacteria against foreign DNA. The action of such a system is based on DNA degradation by an enzyme — restriction endonuclease — and is strongly regulated to prevent host cell DNA damaging. In current study, the restriction-modification system contains controller protein, which regulates amount of restriction-modification system enzymes. Changes in amount of restriction-modification system proteins may cause a change in protection level of bacteria against viruses. We use fluorescence microscopy for direct observation of restriction-modification protein levels and their changes depending on the amount of controller protein in bacterial cells.
Multi-resonance cyclotron-undulator electron acceleration
Authors: Oparina Yu S , Savilov A V , Bandurkin I V
Published: December 2019

In this work, we propose a method of particle acceleration by the electromagnetic wave pulse propagating in the waveguide. The method is based on a “superposition” the electron cyclotron oscillations in the uniform longitudinal magnetic field and their bounce-oscillations in the periodical transverse magnetic field (undulator). Correspondingly, two mechanisms of the electron accelerations by the wave are provided simultaneously, namely, the well-known cyclotron acceleration and the undulator acceleration in the regime of the inversed free-electron laser. The multi-resonance character of this system leads to a chaotic behaviour of the electron motion in the field of the wave. In the process of this motion, electrons can get a very high energy (as compared to the case of the purely cyclotron acceleration by the same wave pulse.
Frequency modulation, amplification and compression of microwave pulses in a system with helically corrugated waveguides as a dispersive elements
Authors: Yurovskiy L A , Ginzburg N S , Zotova I V , Vilkov M N , Samsonov S V , Sergeev A S
Published: December 2019

We consider the possible implementations of the Chirped Pulse Amplification (CPA) technique widely used in optics for the microwave frequency band. We propose using helically-corrugated waveguides for pulse stretching and compressing as their dispersion properties strongly depend on geometrical parameters. For stretched pulse amplification, a helical-waveguide gyro-TWT can be used as a broadband amplifier. Simulations with parameters of the experimentally realized 30 GHz gyro-TWT show that for a 300 W, 200 ps incident pulse, amplification up to 6 MW can be achieved in this system, while in the linear regime of the same gyro-TWT the output power is only about 250 kW.
Spontaneous coherent cyclotron emission from photo-injector electron bunches: superradiation and two-frequency regime
Authors: Oparina Yu S , Pershin D S
Published: December 2019

Short dense electron bunches are attractive from the viewpoint to use them for the implementation of powerful and compact radiation source based on the spontaneous mechanism of radiation. The regime of spontaneous radiation is realized, when the bunch phase size is smaller than 2π. Modern photo-injectors insure formation of mildly relativistic dense electron bunches with duration less than 1 ps. Such bunches are “ready” to radiate waves at terahertz frequencies in the spontaneous regime. However, the repulsion of particles caused by a strong Coulomb field inside the dense electron bunch strictly limits the duration of the radiation process due to the increase in the bunch length. We propose two mechanism of cyclotron radiation to solve this problem. The first one is the regime of group synchronism of particles with the radiated wave; in this case compensation of Coulomb repulsion in the phase space takes place. The second proposed solution is to use compression of bunch by radiated electromagnetic fields.
Precision silicon doping with acceptors by temperature gradient zone melting
Authors: Seredin B M , Kuznetsov V V , Lomov A A , Zaichenko A N , Martyushov S Yu
Published: December 2019

We present the results of optimization of the temperature gradient zone melting technique, also known as the thermomigration (ThM) technique, aimed on improvement of the quality of p-layers and formation of p-n junctions with sharper boundaries compared to those obtained by conventional thermal diffusion technique. In addition, ThM allows an expansion of the range of doping of silicon substrates with an acceptor impurity, usually limited by the solidus value. The ternary Al-Ga-Si and Al-Sn-Si melts were used as ligatures. The dependences of the migration rate of the liquid zones on temperature and composition for the Al-Ga and Al-Sn solvent metal are presented. The possibility of changing the acceptor concentration from 2·1019 cm−3 to 6·1019 cm−3 is shown. A threshold temperature of 1400 K was experimentally found for the ThM process with stable migration of triple liquid zones in a crystal. X-ray diffractional rocking curves and projection topography confirmed high structural quality of the Si(Al) p-layer with a thickness of 25 µm, obtained by ThM with stable moving liquid zones. The experimentally measured strain Δd/d=2.3×10−5 for the p-layer and the silicon substrate was used in the substitution model to estimate the Al concentration of 1×1019 cm−3. X-ray topographic images of the layers did not reveal both growth S-defects and misfit dislocations, confirming the high structural perfection of the layers and phase boundaries.
Features of the 1640 cm−1 band in the Raman spectra of radiation-damaged and nano-sized diamonds
Authors: Khomich A A , Averin A A , Poklonskaya O N , Bokova-Sirosh S N , Dzeraviaha A N , Khmelnitsky R A , Vlasov I I , Shenderova O , Poklonski N A , Khomich A V
Published: December 2019

Raman spectra of irradiated with fast neutrons or MeV ion-implanted radiation-damaged natural and CVD diamonds and chemically purified detonation nanodiamonds are investigated. The influence of radiation damage level and effects of high-temperature annealing on the intensity and spectral shape of the 1640 cm−1 band is studied. It is shown that in radiation-damaged diamonds this band consists of at least six Gaussian peaks, the intensity of which varies one to one both with the level of radiation disordering and the temperature of the subsequent annealing. The “1640” band in radiation-damaged diamonds is completely annealed at temperatures above 1000 °C, while in detonation nanodiamonds annealing up to 1200 °C does not significantly affect its shape and intensity.
The one-dimensional model of non-Newtonian hemodynamics
Authors: Verigina M A , Krivovichev G V
Published: December 2019

The one-dimensional model of the blood flow in large vessels is considered. The non-Newtonian nature of blood is modeled by the friction force and Boussinesq coefficient value. The power law rheological model of fluid is used. The comparison with the models of blood as ideal and Newtonian fluid is realized. The nonlinear problems of single-pulse propagation in a single vessel and in a vessel with bifurcation are considered. It is demonstrated, that non-Newtonian effects play an important role in the obtained solutions.
Application of the random matrix theory to the boson peak in glasses
Authors: Conyuh D A , Beltukov Y M , Parshin D A
Published: December 2019

The density of vibrational states g(ω) of an amorphous system is studied by using the random-matrix theory. Taking into account the most important correlations between elements of the random matrix of the system, equations for the density of vibrational states g(ω) are obtained. The analysis of these equations shows that in the low-frequency region the vibrational density of states has the Debye behavior g(ω) ∼ ω2. In the higher frequency region, there is the boson peak as an additional contribution to the density of states. The obtained equations are in a good agreement with the numerical results and allow us to find an exact shape of the boson peak.
Summation of divergent field-theoretical series for exact and variable values of asymptotic parameters: numerical estimates for the ground-state energy of a cubic anharmonic oscillator
Authors: Varnashev K B
Published: December 2019

Using, as an example, the calculation of the ground-state energy of a cubic anharmonic oscillator, we demonstrate a new approach to summation of divergent series. Our approach based on the Borel-Leroy transformation in combination with a conformal mapping does not require the knowledge of exact values of asymptotic parameters that determine the large-order behaviour of the series. Resumming field-theoretical expansions by varying the asymptotic parameters in a wide range of their exact values, we postulate the independence of the result of numerical analysis from the asymptotic parameters and based on this criterion we give a numerical estimate of the ground state energy of the cubic anharmonic oscillator for different values of the parameters of expantion and anisotropy, taking into account various orders of perturbation theory. We demonstrate good agreement between the results of our numerical calculations and the estimates obtained in the framework of the resummation technique using exact values of the asymptotic parameters. The results we achieved for the simplest anisotropic model allow us to apply this approach to investigate more complicated field-theoretical models describing real phase transitions in condensed matter physics or elementary particle theory, where the perturbation theory used has no small parameter of expansion and the exact values of the asymptotic parameters of the model are unknown.
Wave-mechanical phenomena in optical coupled-mode structures
Authors: Zloshchastiev Konstantin G.
Published: December 2019

We derive a formal mapping between Schrödinger equations and certain classes of Maxwell equations describing the classical electromagnetic wave’s propagation inside coupled-modes waveguides. This mapping reveals a phenomenon, which is not visible in the original form of Maxwell equations: multiple solutions occur which satisfy same boundary conditions but correspond to different eigenvalues of a certain operator; the latter is analogous to Hamiltonian operators which occur in quantum systems. If one deals with normalized state vectors then a proper analogy with the conventional wave mechanics is established: solutions form a Hilbert space which is somewhat similar to that in the quantum mechanics. Therefore, coupled-mode configurations should possess certain wave-mechanical features, which can be formally studied using a formalism of quantum mechanics or, at least, its mathematical part. We notice also that the occurring Hamiltonian operators always possess a skew-adjoint part if one deals with normalized state vectors – even if permittivity and permeability are real-valued. This leads to the “dressing” effect of propagation constants, which indicates presence of additional gain or loss processes in the coupled-mode systems.
Intermittent particle transport with arbitrary distributions of duration of motional phases
Authors: Rukolaine Sergey
Published: December 2019

Intermittent transport of biological objects, including ballistic and Brownian motion, Brownian motion with drift, occurs universally in various forms and scales. In many instances models of intermittent transport imply that the distribution of duration of motional phases is exponential. However, this is by no means always the case. In this paper we generalize the model of intermittent transport, proposed in Bressloff P C and Newby J M 2013 Rev. Mod. Phys.
85 135–196, to the general case of arbitrary distributions of duration of motional phases. We derive also an asymptotic approximation to the model in the assumption that transitions between the phases are frequent.
The structure of the screening layer near the cylindrical bodies emitting charged particles in a deep vacuum
Authors: Gunko Yu F , Gunko N A
Published: December 2019

The purpose of this paper is the exploration of the electric field structure near cylinrical bodies. The solution of the problem is reduced to solving the equation for the potencial of a self-consistent electric field written in dimensionless form.

The behavior of the potential is found by the combined method (at the initial stage, analytically, and then numerically). In contrast to the works devoted to this subject, the dependence of the potential on the coordinates is determined at various values of the electric field strength on the surface of the bodies, which is considered as a parameter.

Such an approach made it possible to distinguish different regimes of electron flows motion: motion in an accelerating field, motion in a field with a minimum of the potential, and returned flow. Determining the position of the boundary between the second and third regimes made it possible to find the thickness of the shielding layer near isolated cylindrical bodies under conditions of deep vacuum.

Knowledge of the potential and magnitude of the screening layer have a practical value: for radio communications, for the smooth operation of electronic equipment on artificial celestial bodies, for studying the mechanisms of lunar soil erosion caused by electric fields, for studying the behavior of potential in complex dusty crystalline structures, as well as for constructing cylindrical diodes working in a given mode.
Analytical solutions of the problems for equations of one-dimensional hemodynamics
Authors: Tkachenko P S , Krivovichev G V
Published: December 2019

The paper is devoted to the construction of an analytical solution of the initial problem for the one-dimensional system of equations of non-Newtonian hemodynamics. In the model, the blood is considered as the power-law fluid. The perturbation method for the solution is proposed. The cases of the first and second perturbations are considered. The obtained solutions can be used for the comparison of different rheological models of blood or for the testing of programs, which realize the numerical algorithms.
Modification of Godunov method for calculations of discontinuous two-temperature flows of low-temperature rare gas plasma
Authors: Kurakin Yu A
Published: December 2019

The paper presents the implementation of Godunov method for shocked flows of two-temperature rare gas plasma. An algorithm for cell edge convective fluxes calculation was developed. Algorithm is based on the solution of Riemann problem in rare gas plasma and includes accurate consideration of electrons adiabatic expansion. The theory uses the assumption that ionization and electrons-molecules collisional heat exchange rates are compatible with the characteristic time of the flow and can be neglected in Riemann problem solution.
Application of hyper-chaotic Lorenz system for data transmission
Authors: Kondrashov A V , Grebnev M S , Ustinov A B , Perepelovskii V V
Published: December 2019

A novel method of digital data transmission is developed and experimentally investigated. The main idea of the method is to convert digital data into a chaotic spectrum, mix it with a background signal and transmit to receiver using TCP/IP protocol. The hyper-chaotic Lorenz system of differential equations is used as a source for carriers of the chaotic spectrum. Chaotic synchronization is not used in the method, that allows to improve stability of data transmission. Human voice is used as the background signal. Therefore, the method allows one to use single communication channel for transmission of different signals without losses. Numerical investigations approved that the chaotic signal transformation does not change chaotic nature of the Lorenz system. Thus, developed method demonstrates high privacy level.
Study of influence of volumetric radiating overcooling of a melt on the form of front of crystallization by means of numerical modeling processes of heat transfer at growth of sapphire crystals from the melt
Authors: Vasil’ev M G , Bakholdin S I , Krymov V M
Published: December 2019

It is lead numerical modeling of processes of heat exchange at growth of crystals of sapphire from a melt by Stepanov and Czochralski methods. The influences of volumetric radiating overcooling of a melt and of growth speed on the form of front of crystallization and distribution of temperature near to it is studied. It is shown, that the account of absorption of thermal radiation in a melt can lead to formation of volumetric supercooled areas near to crystallization front and to appreciable change of its shape.
The scanning probe microscopy of the structural, elastic and conductive properties of two-component phthalocyanines
Authors: Gushchina E V , Dunaevskiy M S , Lahderanta E
Published: December 2019

Thin films of two-component H2Pc, PdPc, PbPc, CuPc phthalocyanines were studied by scanning probe microscopy methods. Young’s modulus values of the phthalocyanines films were measured, which made it possible to optimize the regimes for studying soft phthalocyanine films and to select suitable probes with proper stiffness and the magnitude of the force acting onto the surface. For all films, the electric field induced reversible local conductivity switching effect was studied. It is shown that under room conditions it is possible to reversibly change the value of the local conductivity of a copper phthalocyanine film approximately by an order of magnitude. When conducting the experiment under vacuum conditions, a significant weakening of this effect occurs. It has been established that for a CuPc film, a pressure of 20 mbar is the lower boundary value for creating regions of increased conductivity. The observed effect is explained by the penetration of OH− ions (from the surface adsorbed water film) into the phthalocyanine film with the subsequent formation of oxygen-containing complexes that increase conductivity.
Monodisperse spherical mesoporous nanocomposite mSiO2/C-dots/Eu3+ particles with broadband luminescence in the visible spectral range
Authors: Eurov D A , Kurdyukov D A , Medvedev A V , Tomkovich M V , Golubev V G
Published: December 2019

A facile template synthesis has been developed to obtain monodisperse spherical mesoporous nanocomposite mSiO2/C-dots/Eu3+ particles of submicron size exhibiting bright broadband luminescence in the visible spectral range. The use of europium ions made it possible to increase the integrated emission intensity of the nanocomposite particles in the reddish-orange region. The particles have a specific surface area of 540 m2/g, pore volume of 0.35 cm3/g, and average pore diameter of 2.7 nm. The obtained particles are promising for application in nanomedicine as nanocontainers simultaneously serving as biomarkers.
Transient carrier transport and rearrangement of space charge layers under the bias applied to ferroelectric M/PZT/M structures
Authors: Delimova L A , Yuferev V S
Published: December 2019

A drift-diffusion model of unsteady carrier transport in M/PZT/M structure is proposed to account for the formation of the current peak in the current –voltage curves, which is not caused by the domain switching and observed only when the bias and polarization directions coincide. In the model, electrons generated by oxygen vacancies are trapped by titanium deep centers at room temperature and can move by hopping between titanium atoms in the electric field. The polarization is constant across the film thickness while it is zero within defective layers near the contacts. It is shown that a pronounced current peak is formed when an accumulated space-charge layer appears near one of the contacts under the action of the polarization and this effect is purely unstationary.
Giant injection magnetoresistance induced by femtosecond laser pulses in semiconductor / granular film heterostructures with cobalt nanoparticles
Authors: Lutsev L V , Shelukhin L A
Published: December 2019

The light-induced giant injection magnetoresistance in SiO2(Co)/GaAs heterostructures, where the SiO2(Co) structure is the granular SiO2 film with Co nanoparticles, has been studied. It is found that the photocurrent are accompanied by relaxation oscillations caused by the Coulomb influence and transitions between the photocurrent and electrons on the highest level in the interface quantum well. The light-induced magnetoresistance reaches its maximum value in the avalanche onset region and has the local minimum at the higher voltage. The local minimum is explained by delocalization of the highest level in the interface quantum well and by decrease of the probability of the backscattering process of injected electrons on deeper levels.
Stress evolution during growth of AlN templates on c-Al2O3 substrates by plasma-assisted molecular beam epitaxy
Authors: Koshelev O A , Nechaev D V , Brunkov P N , Ratnikov V V , Troshkov S I , Ivanov S V , Jmerik V N
Published: December 2019

We describe stress evolution during plasma-assisted molecular beam epitaxy (PAMBE) of AlN nucleation and buffer layers on c-Al2O3 substrates at varying growth temperatures of 780 and 850°C. Moreover, different mechanisms of stress generation in the growing AlN films, related to the processes of grain coalescence and impact of Me-excess during PA MBE by migration enhanced epitaxy and metal-modulated epitaxy, are considered.
Investigation of the emission properties of a silicon blade-type cathode
Authors: Filippov S V , Kolosko A G , Popov E O , Demin G D , Makhiboroda M A , Djuzhev N A , Gryazneva T A , Korotkov S Yu
Published: December 2019

The present paper describes the properties of a silicon blade-type cathode with high technological reproducibility. The emission characteristics were obtained using a modern computerized method for studying field emission cathodes in a non-destructive pulsed mode with a flat anode. The technique includes an assessment of the emission current stability, an estimate of the magnitude of the effective parameters of the cathode (field enhancement and emission area) and the degree of their fluctuations over time. A numerical analysis of the glow patterns of the field emission projector was also performed, representing of the distribution of the current load along the edge of blade-type field emitter.
Tamm plasmon-based cavity with a quasicrystalline type structuration
Authors: Morozov K M , Gubaydullin A R
Published: December 2019

We have theoretically investigated Tamm plasmon structure covered by a quasicrystal symmetry subwavelength grating. We show that such structures can support plenty of high-Q hybrid optical eigenstates. The structure consists of a GaAs/Al0.95Ga0.05As Bragg reflector covered with a subwavelength Fibonacci silver/resist sequence. For the F
5 type coverage, two different operation regimes controlled by filling factor value were shown. We demonstrate the anti-crossing behaviour of these states spectral position. The considered system can be useful to enhance the emission of broadband light-emitting materials such as organic dyes and small molecules.
Structural and morphological characteristics of GaN-based hybrid heterostructures grown on por-Si
Authors: Zolotukhin D , Lenshin A , Goloshchapov D , Mizerov A , Arsentyev I , Leiste H , Seredin P
Published: December 2019

GaN/Si(111) heterostructures were grown by plasma-assisted molecular beam epitaxy on usual Si(111) substrates and compliant por-Si/Si(111) substrates without using AlN buffer layer. The positive influence of the high-temperature nitridation step, as well as the usage of a compliant substrate on crystalline quality, was confirmed. We got a crack-free 850-nm-thick GaN layer at room temperature by using the low-temperature GaN buffer layer with nanocolumnar morphology.
Electronic structure and optical characteristics of the hybrid GaN/por-Si heterostructures
Authors: Zolotukhin D , Lenshin A , Goloshchapov D , Mizerov A , Arsentyev I , Leiste H , Rinke M , Seredin P
Published: December 2019

GaN/Si(111) heterostructures grown by plasma-assisted molecular beam epitaxy on routine Si(111) substrates and compliant por-Si/Si(111) substrates without using AlN buffer layer was studied by using various structural and spectroscopy methods of analysis. XPS study revealed that the layer is grown on the compliant substrate of por-Si being closer to the stoichiometric composition. The shift of the A1(LO) mode in the Raman spectrum confirms the lattice-matched growth type on the compliant substrate in comparison with the routine c-Si substrate. The experimentally determined value of the optical bandgap width for the epitaxial GaN layer grown on por-Si substrate exceeds that of the layer grown on single-crystalline silicon c-Si by 0.1 eV
Determination of the fractal dimension of mesopores in metal-oxide structures obtained via sol-gel synthesis
Authors: Maraeva E V , Permiakov N V , Khalugarova K N , Abrashova E V
Published: December 2019

The work is devoted to the development of a combined method of analyzing the porous structure of metal oxide materials. The method is based on a combination of fractal analysis from data obtained by the sorption method using a thermodynamic approach and fractal analysis of atomic force microscopy images. The objects under research are optically transparent materials of the SiO2 – SnO2 – ZnO system, obtained by the sol-gel technology.
Spinodal decomposition with formation of composition oscillations at low temperature GaInP - GaAs synthesis
Authors: Moskvin P P , Skurativskyi S I , Kuznetsov V V
Published: December 2019

The Cahn-Hillard equation is adapted to consider the spinodal decomposition process of semiconductor solid solutions. The obtained differential equation for the decomposition of a material is used to describe the composition modulation effect observed during the synthesis of GaxIn1-xP-GaAs heterostructures. The numerical simulation of the process of spinodal decomposition of the GaxIn1-xP solid solution is performed. The intervals of the thermodynamic parameters for the technological process of the structures synthesis, in which the composition modulation effect should appear, are found.