bluuebunny/crossref_metadata_2025_split huggingface dataset:
The study of models of space selenophysics using multi-parameter analysis and fractal geometry
Authors: Churkin K O , Andreev A O , Nefedyev Y A , Nefediev L A , Hudec R , Bagrov A V , Demina N Y 
Published: December 2020

Abstract
In this work, using multi-parameter harmonic analysis and expansion of altimetry into spherical functions, models of the Moon’s physical surface (digital lunar selenocentric map - DLSM) are built, and a comparison of similarity of chosen local areas of the complex lunar structure is performed. The constructed DLSM have radius-vectors of the surface points in accordance with the space measurements taken. As result, the averaged fractal dimension of the selenocentric surfaces profiles models was found to 1.345. The similarity and difference parameters were determined by the author’s method using fractal similarity coefficients. The analysis of macrosurfaces based on multi-parameter and fractal methods for the selenocentric models built in this work has not been conducted before.
Evaluating MHD parameters of relativistic shock waves with particle-in-cell modeling
Authors: Romansky V I , Bykov A M , Osipov S M 
Published: December 2020

Abstract
Relativistic plasma outflows are observed in gamma-ray burst sources, jets of active galactic nuclei, pulsar wind nebulae and supernovae explosions. Magnetohydrodynamical (MHD) shock waves inevitably result from interactions of such relativistic outflows with the ambient interstellar matter. The widely used single-fluid MHD description of relativistic shock waves is the main tool to study the global structure of such objects. However, to justify the validity of the global MHD models and to interpret the observed emission spectra of space objects with relativistic shocks, a kinetic description of electrons, positrons, and ions at microscales is needed. We model a plane relativistic shock propagating transverse to a regular magnetic field in the electron-ion plasmas with imposed turbulent fluctuations in the shock upstream. Namely we study the effect of the micro-scale plasma processes on macroscopic parameters of the mildly-relativistic shocks as the adiabatic index of the relativistic fluid in the shock downstream. The adiabatic index is a macroscopic parameter of the single-fluid MHD models commonly used for shock modeling at much longer hydrodynamical scales and it is especially important for the MHD modeling of the mildly-relativistic shocks.
The study of near Earth objects and meteor showers
Authors: Sergienko M V , Sokolova M G , Andreev A O , Nefedyev Y A 
Published: December 2020

Abstract
In this work, the physical parameters of near-Earth objects (NEO), i.e. small celestial bodies crossing the Earth’s orbit, are investigated. First of all, the study of NEO, whose number exceeds 15 thousand, is important in terms of asteroid threats. NEO are mainly stony and iron, but also could be comet nuclei that had lost the icy component under the influence of solar radiation. As a result of analyzing 14800 near-Earth asteroids from the Apollo group, in this work near-Earth objects closely genetically related to the existing meteor showers are determined. 2002LV and 2001MG1 asteroids are the closest to the Kappa-Cygnids by orbital elements. 2014RS17, 2006BF56, 2001YB5 asteroids are the closest to the Delta-Cancrids by orbital elements. 2008VL14, 2006UF17, 2010VF, 2000DO1, 2010CF55, 2010TN55, 2007EJ88, 481482 2007CA19 asteroids are the closest to the Virginids by orbital elements. The D-criterion method was used in the analysis.
Fluid–structure interaction modelling of the venous valve with elastic leaflets
Authors: Tikhomolova L G , Gataulin Y A , Yukhnev A D , Rosukhovskiy D A 
Published: December 2020

Abstract
The paper presents the results of a numerical study of the flow in a symmetric model of a healthy popliteal venous valve with different leaflet elasticity. The focus is on the analysis of the stagnant area under the valve leaflet. The stagnant area under the valve leaflet, as well as behind the valve, is of great practical interest to phlebologists in terms of the possibility of blood clots. The flow in the constructed simplified model of the venous valve gave good qualitative agreement with the clinical ultrasound data for a leaflet with Young modulus of 1.2 MPa.
Elastomer planar device for nucleic acids extraction
Authors: Germash N N , Esikova N A , Afonicheva P K , Antifeev I E , Petrov D G , Evstrapov A A 
Published: December 2020

Abstract
In this paper a device that provides the nucleic acids extraction and loading into a microfluidic chip for subsequent analysis by amplification methods was performed. The device is made by soft lithography from Silastic T4. The mechanical properties of the material (Young’s modulus) and the contact angle after Ar plasma treatment were studied. The strength of the connection of the device elements was evaluated. The device usability was checked by nucleic acids extraction from E.coli samples and using model solutions of the GAPDH gene cDNA.
Dispersion-compensated waveguide for difference-frequency generation in quantum-cascade laser
Authors: Savchenko G M , Sokolovskii G S 
Published: December 2020

Abstract
The waveguide structure of a semiconductor quantum-cascade laser is presented, which provides compensation of material dispersion of the refractive index. This structure can be used to generate radiation with a frequency of 1.4 THz due to nonlinear light conversion.
Proton irradiation effects on GaN-based epitaxial structures
Authors: Lebedev A A , Davydov V Yu , Smirnov A N , Eliseyev I A , Davydovskaya K S , Zavarin E E , Zakheim D A , Lundin W V , Nikolaev A E , Sakharov A V , Tsatsulnikov A F , Zubov A V , Kozlovski V V 
Published: December 2020

Abstract
Radiation hardness of different types of GaN based epitaxial structures which can be used as elements of electronic devices is studied by Hall effect,CV and IV measurements, as well as photoluminescence and Raman scattering. It is shown that proton irradiation leads to formation of deep acceptor states reducing conductivity of high electron mobility transistors (HEMTs) and Si-doped layers and is accompanied by a redistribution of the defect-related lines in the photoluminescence spectra. Our results demonstrate that proton irradiation increases conductivity for GaN:C, while decreases it for GaN:Fe and GaN:(Fe+C) layers.
Explicit isometric embeddings of pseudo-Riemannian manifolds: ideas and applications
Authors: Sheykin A A , Markov M V , Fedulov Ya A , Paston S A 
Published: December 2020

Abstract
We study the problem of construction of explicit isometric embeddings of (pseudo)-Riemannian manifolds. We discuss the method, which is based on the idea that the exterior symmetry of the embedded surface and the interior symmetry of its metric must be the same. In case of high enough symmetry of the metric such method allows transforming the expression for induced metric, which is the one to be solved in order to construct an embedding, into a system of ODEs. It turns out that this method can be generalized to allow the surface to have lower symmetry as long as the above simplification occurs. This generalization can be used in the construction of embeddings for metrics, whose symmetry group is hard to analyze, and the construction of the isometrically deformed (bent) surface. We give some examples of the application of this method. In particular, we construct the embedding of spatially-flat Friedmann model and isometric bendings of a sphere, 3-sphere, and squashed AdS universe, which is related to the Godel universe.
Explicit isometric embeddings of black holes geometry with non-singular matter distribution
Authors: Kapustin A D , Paston S A 
Published: December 2020

Abstract
The work is devoted to the construction of explicit embeddings for the metrics of the black holes, formed by nonsingular matter distribution. One of the possible examples of such type of solutions is regular black holes. Using the existing classification of minimal symmetric embeddings of the Schwarzschild metric as a base, we construct embeddings for regular black holes with de Sitter interior. Another simple example is black hole, formed by collapsing homogeneous spherically symmetric cloud of dustlike matter. We discuss embeddings for two variants of such black holes -the one with the eternally existing horizon, when dust ball never leaves the interior of the horizon, and another variant with the dynamically forming horizon.
Study of instability of sapphire tubes growth by Stepanov method
Authors: Vasil’ev M G , Bakholdin S I , Krymov V M 
Published: December 2020

Abstract
The paper considers the experimentally observed instability of capillary shaping during the growth of thick-walled sapphire tubes by the Stepanov method. The explanation of this phenomenon is based on the theoretical model of radiative-conductive heat transfer in a crystal. An algorithm is developed for the asymptotic expansion of the problem based on the presence of two small parameters. It is shown that the spatial density of the radiation is inhomogeneous along the cross section of the tube and is maximum near its inner walls. This leads to their overheating and the meniscus separation from the inner edges of the shaper.
The limit shape of the height function in the six-vertex model with domain-wall boundary conditions
Authors: Belov P A 
Published: December 2020

Abstract
The height function of the six-vertex model with the domain-wall boundary conditons in the free fermion point is computed by the Monte Carlo algorithm. The numerical results are in good agreement with the analytical expression for the limit shape height function. This paper is a “warm up” for the forthcoming one, where the two-point correlation function for the height function is calculated.
The effect of the n-alkane evenness on structural phase transitions
Authors: Gureva S A , Marikhin V A , Myasnikova L P , Volchek B Z , Medvedeva D A 
Published: December 2020

Abstract
The kinetics of the first-order solid-state structural transition in monodisperse n-alkanes samples of odd tricosane C23H48 and even tetracosane C24H50 was studied by FTIR spectroscopy. The initial nuclei location of the new phase was revealed. The process of crystal structure rearrangement is initiated in the interlayers between neighboring lamellar for odd tricosane, while the nanonuclei in even tetracosane arise in the crystalline lamellas cores. Thus, the influence of the number evenness of carbon atoms in the n-alkanes chains on the first-order structural phase transition has been proved.
Incoherent grain boundaries in CuO nanowhiskers
Authors: Berminova M S , Kalmykov A E , Myasoedov A V , Sorokin L M , Dorogov M V 
Published: December 2020

Abstract
An array of CuO nanowhiskers have been fabricated by heating of copper coatings formed on stainless steel mesh substrate in air. Cross-sections of the nanowhiskers were studied by transmission electron microscopy. It was established that whiskers consist of two or more grains with incoherent boundaries. The mechanism of the formation of incoherent boundary is revealed. An important role of the incoherent boundaries in the formation of the nanowhiskers is discussed.
Computer simulation of three-layer ferromagnetic nanosystems in magnetic field
Authors: Belim S V , Belim S S 
Published: December 2020

Abstract
A computer modelling of magnetization behavior in ultrathin ferromagnetic films, divided by antiferromagnetic film is carried out. The exchange integral value is different for each ferromagnetic films. One of the films is magnetohard, the second one is magnetosoft. The situation where magnetosoft film has the exchange integral value twice smaller than the value of magnetohard film is investigated. Heisenberg model is used. Calculations are made using Metropolis algorithm. The phase transition temperature is obtained for all three films. The magnetic field was applied along the film plane. The simulation showed that magnetizations of ferromagnetic films first become perpendicular to the direction the staggered magnetization vector in the antiferromagnetic film. With a higher magnetic field value, the magnetization vectors of the ferromagnetic films become mutually perpendicular. Thus, in these multi-layer systems, it is possible to control the orientation of the substances spins, which is an important property for implementing spintronics devices.
Investigation of the influence of the nano-nuclei habit on the specifics of phase transitions in long-chain molecular crystals and polymers
Authors: Borisov A K , Egorov V M , Marikhin V A 
Published: December 2020

Abstract
The thermodynamic parameters of a long chain molecular crystals (LCMCs) set are analyzed. We revealed the dependence of LCMC’s melting points with a different chain length on the habitus of the first-order phase transition’s elementary volume. It was shown that LCMCs with the same chemical structure of the “core” (normal alkanes {CH3(CH2)nCH3}, normal alkanols {CH3(CH2)nCOH}, diols {COH(CH2)nCOH}, carboxylic {CH3(CH2)nCOOH} and dicarboxylic {COOH(CH2)nCOOH} acids) lose their individual thermodynamic properties and approach the properties of polymethylene with an increase in the number of –CH2– groups.
Investigation of optical and structural properties of three-dimensional InGaPAs islands formed by substitution of elements of the fifth group
Authors: Andryushkin V V , Gladyshev A G , Babichev A V , Kolodeznyi E S , Novikov I I , Karachinsky L Ya , Nevedomskii V N , Egorov A Yu 
Published: December 2020

Abstract
We propose a new method to obtain the three-dimensional quantum-sized object arrays with reduced surface density. These arrays are formed by elastic transformation of the InGaPAs layer grown on the GaAs surface. We present the results on influence of the InGaP layer thickness, the substrate temperature, and exposure time in the arsenic flow on the optical and structural properties of the formed three-dimensional islands.
Effect of the composition and temperature of the subphase on the surface potential of the Langmuir monolayer of 8CB liquid crystal
Authors: Begletsova N N , Mironyuk V N , Santer S , Smirnova A I , Usol’tseva N V , Glukhovskoy E G 
Published: December 2020

Abstract
The effect of the composition and temperature of the subphase on the effective dipole moment of the Langmuir monolayers of a liquid crystal 4-n-octyl-4’-cyanobiphenyl on the surface of pure water and an aqueous solution containing copper nanoparticles was studied. It is shown that the presence of nanoparticles in the subphase leads to increase of the area occupied by the monolayer in the condensed state, increase of the collapse pressure, and reduce of the surface potential at the end of monolayer compression. The effective dipole moments of liquid crystal molecules were calculated for monolayers formed under various conditions.
Features of hydrogen diffusion through an amorphous Fe92Si6B2 alloy membrane
Authors: Pluzhnikova T N , Fedorov V A , Balybin D V , Berezner A D , Fedotov Yu D , Pluzhnikov S N 
Published: December 2020

Abstract
In this work, the hydrogen diffusion through an amorphous Fe92Si6B2 alloy membrane has been investigated. It has been established that the hydrogen diffusion decreases with the growth of the acidity of the environment at the constant ionic force of solution. The probable mechanisms of the blocking of hydrogen flow through the membrane have been discussed. An insignificant variation of the mechanical characteristics (ultimate tensile strength, microhardness, Young’s modulus) of Fe92Si6B2 amorphous alloy has been detected.
Improvement of single walled carbon nanotubes layer conductivity by texturing
Authors: Mitin D M , Vorobyev A A , Raudik S A , Mozharov A M , Nasibulin A G , Mukhin I S 
Published: December 2020

Abstract
This work is aimed at finding and developing new ways to improve and optimize the characteristics of transparent conductive electrodes based on SWCNT by forming a texture in a continuous layer by combination of lithography and oxygen plasma treatment. A theoretical and an experimental justification for choosing thickness of a textured pattern, together with the experimental results of optical and electrophysical measurements were presented. The resistance of the textured electrode was 187.5 Ohm/sq, which is 17.5% lower than resistance of the electrode made from a continuous SWCNT layer with a same transparency of 95%. An analytical calculation showed that the use of extremely absorbing SWCNT films for texturing allows to obtain ∼ 54% gain in the resistance of a textured electrode compared to a continuous SWCNT’s layer.
Light-activation of gas sensitive layers based on zinc oxide nanowires
Authors: Nalimova S S , Ryabko A A , Maximov A I , Moshnikov V A 
Published: December 2020

Abstract
In this work, a sensor layer based on zinc oxide nanowires was synthesized by low-temperature hydrothermal method. The gas sensitivity of sample to isopropyl alcohol vapor was studied both during heating and under ultraviolet radiation. It was shown that depending on the presence of moisture on the surface of zinc oxide nanowires, isopropyl alcohol vapor can act as a reducing or oxidizing gas upon activation of gas sensitivity by ultraviolet irradiation. It was shown that there is an optimal intensity of irradiation, which determines the maximum response of sample. The gas sensitivity under moist air conditions demonstrates the possibility of practical application of adsorption resistive gas sensors with light-activation at room temperature.
Raman scattering and low-frequency noise in epitaxial graphene chips
Authors: Eliseyev I A , Usikov A S , Lebedev S P , Roenkov A D , Puzyk M V , Zubov A V , Makarov Yu N , Lebedev A A , Shabunina E I , Dementev P A , Smirnov A N , Shmidt N M 
Published: December 2020

Abstract
Graphene is considered as a promising candidate for manufacturing of sensors due to its extreme sensitivity to molecule absorption. In this work, we show the connection between the electrical and optical properties of epitaxial graphene chips grown on 4H-SiC and intended for the production of protein-based sensors. Using of a complex of techniques, including Raman spectroscopy, atomic force microscopy, Kelvin probe microscopy, study of I-V characteristics and low-frequency noise, it is shown that the character of frequency dependence of the spectral density of voltage fluctuations and its value at a frequency of 1 Hz can be used for classification and selection of graphene chips for their application as sensors. Classification of the graphene chips will allow more efficient development of graphene-based biosensors.
Comparative analysis of proton production as a function of quark content and collision geometry
Authors: Larionova D M , Berdnikov A Ya , Berdnikov Ya A , Kotov D O , Mitrankov Yu M 
Published: December 2020

Abstract
Quark gluon plasma (QGP) is one of the most discussable objects in modern particle physics. One of the ways to study QGP is to measure production of different particles in various relativistic ion collisions. Nuclear modification factors (Rab) for protons were previously measured in symmetric Au+Au collisions at

s

N
N

= 200 GeV and U+U collisions at

s

N
N

= 200 GeV. Asymmetric Cu+Au system in comparison with Au+Au results allows to study the influence of collision geometry on proton production. This report presents invariant transverse momentum (p
T) spectra, Rab values of protons obtained in Cu+Au collisions at the energy of

s

N
N

= 200 GeV and U+U collisions at

s

N
N

= 200 GeV and the results of comparative analysis of proton (three valence quarks) and φ, π0-mesons (quark antiquark pairs) production as a function of quark content and collision geometry (Cu+Au and Au+Au).
X-ray spectral studies of calcium copper titanates
Authors: Nekipelov S V , Zhuk N A , Mingaleva A E , Petrova O V , Sivkov D V , Sivkov V N 
Published: December 2020

Abstract
XPS and NEXAFS spectroscopy were used to study calcium copper titanates (CCTO) solid solutions doped with iron and nickel atoms. The CCTO compound spectra analysis shows that titanium atoms have +4 charge state, and copper and calcium atoms – +2, and their valency does not change when doped with iron and nickel atoms at the concentration of the latter up to 6 atomic percent. In this case, doping atoms are mainly embedded into the positions of titanium atoms and have Fe 3+ and Ni 2,5+ charge states.
Control of topological structure of solitons in a laser with saturable absorption
Authors: Rosanov N N , Fedorov S V , Veretenov N A 
Published: December 2020

Abstract
We present a theoretical and numerical investigation of effect of a weak coherent holding radiation on transverse field structures in a wide-aperture laser with fast saturable absorption. In the absence of the coherent driving, the laser is able to support various types of “free” bright solitons. We show that even weak driving can control their topology making the scheme promising for topologically protected information processing.
OV-bearing modes with ℓ = 2 of twisted anisotropic optical fibres
Authors: Alexeyev C N , Barshak E V , Vikulin D V , Lapin B P , Yavorsky M A 
Published: December 2020

Abstract
We investigated the high-order mode structure of a weakly guiding twisted anisotropic optical fibre. An analytical solution of the vector wave equation for this case is presented. We obtained analytical expressions for the higher-order modes with an azimuthal number ℓ = 2 and their propagation constants of such a fibre, considering the mutual effect of linear anisotropy of fibre’s material, twisting, including torsional mechanical stress, and spin-orbital interaction. We showed that optical vortex beams with topological charge ±2 are the modes of the fibres considered.
Change of the defects density distribution profile over the area of the InGaN/GaN light-emitting heterostructures during current tests
Authors: Frolov I V , Radaev O A , Sergeev V A 
Published: December 2020

Abstract
A method for measuring of the defects density distribution profile over the area of the LED chip is presented. Using the blue commercial LEDs as an example, it is shown that the emission power decreases when LEDs testing under the increased density pulsed current for 190 h. The decrease of the LEDs emission power is accompanied by a change in the defects density distribution profile. It was determined that during the degradation process a non-uniform increase in the defects density occurs in various regions of the heterostructure: in regions with a higher defect density, the increment in the density of defects is larger.
Thermal quantum efficiency droop in blue InGaN/GaN LEDs
Authors: Shabunina E I , Chernyakov A E , Ivanov A E , Kartashova A P , Talnishnikh N A , Shmidt N M , Zakgeim A L 
Published: December 2020

Abstract
The contribution of several mechanisms to the external quantum efficiency (EQE) droop in blue InGaN/GaN LEDs occur at different current densities j and voltages in MQWs situated inside and outside of a depletion region around p-n junction. It is clarified that an increase in EQE droop at 300-400 K (j < 10 A/cm2) is due to non-radiative losses related to an enhancement in trap-assisted tunneling. It is also associated with a growth in the concentration of delocalized carriers. The main source of the EQE droop under direct current and at pulse mode when j > 30 A/cm2 is non-equilibrium filling of lateral regions of different size within MQWs placed outside of depletion region by delocalized carriers activated by injection when voltage exceed a threshold value (U > Uth). This leads to a decrease in localized potential and to the blue shift of EQE maximum over wavelengths followed by the EQE droop.