bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling of particle acceleration in the pulsar wind nebulae with bow shocks
Authors: Petrov A E , Bykov A M , Osipov S M 
Published: December 2020

Abstract
The observations of the pulsar wind nebulae (PWNe) indicate the presence of efficient acceleration of positrons and electrons in these sources. The Fermi acceleration in the colliding shock flows can explain the observed hard synchrotron emission spectra of PWNe with bow shocks (BSPWNe). This may result in their maximal luminosities in the far ultraviolet range (FUV; 1250 — 2000 Å, ∼ 6 — 10 eV) due to the synchrotron emission of pairs rather than due to the thermal emission of the shocked interstellar matter. Fine spectroscopic observations of sufficiently bright sources with Hubble Space Telescope could be applied to distinguish between these two scenarios. In this paper we simulate BSPWNe flows structure with the relativistic magnetohydrodynamic code PLUTO, consider particle transport and their synchrotron emission for a number of BSPWNe. We calculate the synchrotron FUV luminosities of these BSPWNe and discuss the prospective of their observation in FUV. We also consider possible contribution of PSR J1741-2054 to the positron excess detected by AMS-02 and PAMELA.
Solar activity reconstructed on the basis of radiocarbon data and climate change from 17000 to 5000 BC
Authors: Kudryavtsev I V , Dergachev V A 
Published: December 2020

Abstract
The data on the content of cosmogenic isotopes 14C and 10Be in the Earth’s atmosphere at a time interval of 15000-5000 BC were analyzed. On Earth at this time there was a transition from the ice age to the Holocene. The reconstruction of Wolf numbers based on radiocarbon data is presented, which describes solar activity and takes into account changes in the Earth’s climate during the period under consideration. The increase in global temperature during the transition to the Holocene was accompanied by a sequence of warming (for example, Meiendorf warming) and cooling. The obtained reconstruction of Wolf numbers indicates that at separate time intervals: 13600-13000, 9300-9000, 8300-8000 BC the Sun was in a state of deep minima of activity. We also note the activity minima at ≈ 10700 and 7500 BC. The periods of extremely high activity of the Sun were also distinguished, so at maxima ≈ 12350 and 6715 BC. Values of Wolf numbers could exceed 200. The duration of the first of these periods was several hundred years, and at that time Meiendorf warming took place on Earth (≈12500-11850 BC). The question arises: are these events related?
Powerful Solar Proton Events of January 2005 and their impact on intensity of the stratospheric polar vortex
Authors: Veretenenko S 
Published: December 2020

Abstract
In January 2005, a series of powerful Solar Proton Events (SPEs) associated with an increase of flare activity on the Sun was observed. Increases of solar proton fluxes with energies 165-500 MeV allowing particles to reach stratospheric altitudes (∼30 km and below) were registered during the events starting on 15, 16 and 17 January. The strongest event, with particle energies exceeding 500 MeV, took place on 20 January and was accompanied by an increase of the neutron monitor counting rate (Ground Level Enhancement). The events under study resulted in a considerable increase of stratospheric ionization. In this work an impact of these events on intensity of the stratospheric polar vortex playing an important part in the mechanism of solar-atmospheric links is studied. A noticeable intensification of the vortex (increase of western wind velocity) was revealed at all the stratospheric levels in the course of the SPE series under study. It was shown that auroral activity (precipitations of auroral electrons generating bremsstrahlung X-rays) is also a possible factor of the vortex intensification. The obtained results provide evidence that ionization changes associated with powerful SPEs and auroral activity may influence the state of the stratospheric polar vortex on the day-to-day time scale. A possible cause of the vortex intensification seems to be temperature variations associated with changes of chemical composition of the polar stratosphere due to ionisation changes.
The effect of electron screening on the structure of crystals in degenerate stars
Authors: Kozhberov A A 
Published: December 2020

Abstract
The neutron stars crust and white dwarfs consist of a degenerate relativistic electron gas and atomic nuclei arranged into a crystal lattice. The type of lattice that ions form may depend on many parameters, for example, on the external magnetic field, temperature (T), and ion number density (n). In this paper, we consider the effect of electron background polarization on the type of lattice at T = 0. Two approximations are used to describe this background. If it is described by the Thomas-Fermi model, the influence of polarization is determined only by the parameter κTFa, where κ
TF is the Thomas-Fermi wave number, a = (4πn/3)−1/3 is the radius of the ion sphere and at κ
TF
a ⋦ 1 the bcc lattice has the lowest energy. On the other hand, if we use the random-phase approximation for the electron dielectric function, the energy of the static lattice will be a function of κ
TF and the relativistic electron parameter x
r. In this case, the bcc lattice possesses the lowest energy at κ
TF
a < 0.28 and any x
r, while at higher κ
TF
a the formation of other lattice in consideration (fcc and hcp) is possible.
The creation of a regression model of the Earth’s pole motion with a feature of dynamic prediction
Authors: Khairutdinova A N , Mubarakshina R R , Andreev A O , Nefedyev Y A , Demina N Y 
Published: December 2020

Abstract
This work is dedicated to the modern and relevant problem of predicting the Earth’s pole motion. Using regression modelling, we form a complex model, consisting of a set of optimal mathematical structures each describing the dependence of its step’s remnant on time. The comparison between the results produced in this paper with other works on the study of North pole dynamics has shown that the models obtained using adaptive regression modelling (ARM) approach allows predicting the Y-coordinate more accurately while conserving the accuracy of the X-coordinate. Our results confirm the promise of using the so called adaptive dynamic regressions developed currently for describing the Earth’s pole position’s dynamics. The ARM-approach compared to the classic methods for analyzing time series has a number of advantages: 1) an expansion of the concept of a mathematical model’s structure describing a certain dynamics could be performed; 2) the oscillations’ harmonics stable in time are isolated; 3) the accuracy of predicting changes over a certain time period increases several times, which has an important practical value.
A search for gamma-ray counterparts to gravitational wave events in Konus-Wind data
Authors: Ridnaia A , Svinkin D , Frederiks D 
Published: December 2020

Abstract
The recent discoveries in multi-messenger astronomy allow us to study the Universe in a new way. The Advanced LIGO and Advanced Virgo gravitational-wave (GW) detectors have opened the possibility for regular detection of transients from compact binary merger events. The Konus-Wind (KW) spectrometer continuously observes the whole sky and enables searches for transient events over various timescales from milliseconds to hours. It provides a unique opportunity to study high energy transients, in particular, gamma-ray counterparts to gravitational wave detections. In this paper, we present the methodology and results of the search for gamma-ray counterparts to 56 GW events in KW data. While no counterpart candidate was found in our search, we report upper limits on soft gamma-ray emission from these events, including several events not observed by other wide-field high-energy instruments such as Fermi-GBM, INTEGRAL-SPI-ACS and Swift-BAT. We finally discuss the potential of KW to detect bursts as weak as GRB 170817A.
Extremely strong damped Lyα systems at high redshifts
Authors: Telikova K N , Balashev S A , Noterdaeme P , Krogager J-K , Ranjan A 
Published: December 2020

Abstract
We present a spectroscopic analysis of seven Extremely Strong Damped Lyα systems at redshifts z = 2–3, obtained with the intermediate-resolution spectrograph X-shooter on the Very Large Telescope. For all systems we estimated column densities of the neutral atomic hydrogen HI, metal abundances and dust depletion. We firmly detected molecular hydrogen H2 in two systems in our sample; for the remaining systems we set a conservative upper limits on the H2 column densities. The properties of the obtained systems are in consistency with the sample of the Extremely Strong Damped Ly
α
systems available in the literature.
Precision study of mineralization features of enamel apatite in the development of fluorosis by means of optical spectroscopy
Authors: Goloshchapov D , Kashkarov V , Nikitkov K , Ippolitov I , Ippolitov Yu , Vongsvivut J , Savvateev M , Vaxtel A , Seredin P 
Published: December 2020

Abstract
We have investigated the molecular composition of the tooth enamel microregions in the normal and initial stages of the development of fluorosis by means of the IR and Raman spectroscopy. It has been shown that in the pathology of fluorosis, tooth mineralization takes place with the formation of calcium fluoroapaptite. It was found that an increased fluorine content causes a change in the characteristic profile of the bands and a redistribution of the intensity of the components of the υ1 PO4 and υ3 CO3 groups of the infrared and υ4 PO4 Raman spectra. The resulting IR and Raman spectra can be utilized as standards in the development of a new diagnostic approach of the early forms of the disease.
Interaction of HMGB-domain proteins from differentiated cells with DNA modified by cisplatin
Authors: Chikhirzhina E V , Starkova T Yu , Polyanichko A M 
Published: December 2020

Abstract
Using UV absorption spectroscopy and circular dichroism, we studied the interaction of DNA-cisplatin complexes with nonhistone chromosomal proteins HMGB1 and HMGB2. It was shown that the presence of platinum ions affected the ability of HMGB2 to form large supramolecular complexes with DNA. The role of C-terminal domain of the HMGB1/2 proteins is discussed.
Application of megahertz ultrasound to isolate nucleic acids
Authors: Petrov D G , Antifeev I E , Djenloda R H , Germash N N , Makarova E D 
Published: December 2020

Abstract
The dependence of the yield of M. tuberculosis DNA from model solutions under the influence of megahertz ultrasound in the range from 1.2 to 3.0 W/cm2 on magnetic particles was studied. The dependences of the DNA yield upon sounding for 1, 5, and 10 minutes are obtained. Under ultrasound exposure, the maximum yield is 98%, which is 39% higher than the DNA yield in the absence of a similar effect. It was shown that the efficiency of DNA extraction on magnetic particles using ultrasound is not linearly dependent on the intensity of scoring. The result of the electrophoresis of the sample after ultrasonic treatment of different intensities in megahertz for 1, 5 and 10 minutes is also shown.
Influence of heating time and microwave radiation power on the microstructure and phase composition of calcium-phosphorus compounds during formation
Authors: Khalugarova K N , Maraeva E V , Zaikina A V , Matveev V A , Moshnikov V A 
Published: December 2020

Abstract
This work is devoted to experimental methods for producing calcium-phosphorus compounds, including calcium hydroxyapatite, using microwave radiation. Two types of synthesis were used: template method and chemical precipitation. During synthesis, the heating time and power were changed. The obtained samples were studied using scanning electron microscopy, X-ray diffraction analysis, and the BET (Brunauer-Emmett-Teller) sorption method.
Molecular and fibrillar structure collagen analysis by FTIR spectroscopy
Authors: Nashchekina Yu A , Starostina A A , Trusova N A , Sirotkina M Yu , Lihachev A I , Nashchekin A V 
Published: December 2020

Abstract
The main component of connective tissue and human organs — collagen protein is widely used in tissue engineering, regenerative medicine and cosmetology. The new methods search for assessing the structural and qualitative characteristics of collagen is currently an urgent area. This research is devoted to analyze by FTIR spectroscopy the various structural forms of collagen during the transition from molecular to fibrillar form and also collagen fibrils destruction.
It was shown that during the formation of fibrils in the IR spectra, a peak arise with a wavenumber of 1083 cm−1. The magnitude of this peak can be used to judge the degree of fibrillation of molecular collagen in vitro. It was shown that the addition of a hydrogen peroxide solution with concentrations of 0.6, 1.5, and 3% in the initial solution with fibrillar collagen leads to the destruction of fibrils, which manifests itself in a noticeable fading of the peak with a wavenumber of 1083 cm−1.
Emission properties of textured gallium nitride with high density of stacking faults
Authors: Mynbaeva M G , Ivanova E V , Kirilenko D A , Smirnov A N , Mynbaev K D 
Published: December 2020

Abstract
In this study we related structural properties of GaN grown on ceramic substrate and studied with transmission electron microscopy with the results of photo-and cathodoluminescence investigations. We found that stacking faults in the basal plane were responsible for both strong room temperature visible emission and exciton-related ultraviolet luminescence at cryogenic temperature.
Photonic crystal waveguide for second harmonic generation: exact solution
Authors: Savchenko G M , Cherotchenko E D , Sokolovskii G S 
Published: December 2020

Abstract
We provide the exact solution of the dispersion equation for a waveguided semiconductor structure with a photonic crystal core that provides the efficient second harmonic generation in the visible range. The comparison of the results with an approximate solution shows good agreement.
Two-stage compression of a plasma of multicharged ions created in a low-inductive high-current capillary Z-discharge as a method for pumping the active medium of short-wave lasers
Authors: Kalinin N , Timshina M , Burtsev V 
Published: December 2020

Abstract
The possibility of stepwise formation of the active laser medium on a plasma of multicharged ions is shown based on the numerical simulation results. Practically, such compression can be carried out with a high-voltage generator, storage and forming lines. It is presented that at conditions Im ≥ 200kA in stepwise pumping mode, it is possible to obtain Xe-plasma parameters with an electron temperature Te>400 eV and a concentration Ne>1020 cm−3. Such plasma is a good medium for amplification of spontaneous radiation at several transitions in the spectral region λ≈10 nm in a Xe-plasma of Ni-like ions: it can provide a gain at the transitions g+~ ∼ 1-2 cm−1.
Change of the topological surface states induced by ferromagnetic metals deposited on BiSbTeSe2
Authors: Kaveev A K , Terpitskiy A N , Tereshchenko O E , Golyashov V A , Estyunin D A , Shikin A M , Schwier E F 
Published: December 2020

Abstract
The energy gap was revealed in the Dirac cone of the BiSbTeSe2 topological insulator after the submonolayer deposition of a ferromagnetic metal. As a ferromagnet, cobalt and manganese were used. Such way of the energy gap opening is novel in comparison to the bulk ferromagnetic doping of topological insulators.
Intercalation of graphene formed on silicon carbide with iron, cobalt and silicon atoms
Authors: Grebenyuk G S , Lobanova E Yu , Smirnov D A , Pronin I I 
Published: December 2020

Abstract
Intercalation of graphene formed on silicon carbide surface with iron, cobalt and silicon has been used to form the graphene/silicides/SiC interfaces. The experiments were carried out in situ in ultrahigh vacuum conditions. The elemental composition and chemical state of the sample surfaces, as well as their atomic structure, were controlled by high-energy-resolution photoelectron spectroscopy and low-energy electron diffraction. The nominal thicknesses of the deposited iron, cobalt and silicon layers varied in the range of 2-20 Å, and the temperature of the sample annealing was changed from room temperature to 600°C. It is shown, that the intercalation of graphene/Fe/SiC with Si leads to the formation of Fe-Si solid solution layer covered with surface silicide Fe3Si, while intercalation of graphene/Co/SiC with Si results in the formation of a Co-Si solid solution and CoSi silicide covered with Co3Si surface phase. The obtained silicide layers are reliably protected by graphene, making it compatible for nanoscale applications at ambient conditions.
Epitaxial synthesis of single-domain gallium phosphide on silicon
Authors: Sapunov G A , Koval O Yu , Fedorov V V , Bolshakov A D 
Published: December 2020

Abstract
The aim of the work is to investigate different approaches for the growth of planar gallium phosphide layers on silicon by molecular beam epitaxy. Atomic force microscopy and reflection high energy electron diffraction were used to study surface morphology and estimate the film domain structure. Developed growth technique with the use of a low-temperature AlGaP/GaP seeding layer allowed us to achieve atomically flat pseudomorphic single-phase GaP on Si(001).
Bipolar resistive switching properties of titanium dioxide thin films deposited by different techniques
Authors: Gerasimova M , Ivanov A , Mazing D , Chigirev D , Andreeva N 
Published: December 2020

Abstract
A comparative study of bipolar resistive switching in thin films of titanium dioxide, fabricated by different techniques, was carried out by analysis of current-voltage characteristics (I-V). For this purpose metal-insulator-metal (MIM) structures were formed with 60-nm-thick titanium dioxide layer deposited by atomic layer deposition (ALD) or RF magnetron sputtering. Based on the analysis of resistance switching characteristics, it was found that the deposition technique of titanium dioxide thin films influences the reproducibility of high-resistance state (HRS) at cycling measurements, the on-resistance (low resistance state)/off-resistance (HRS) ratio, the average values of SET [switching the resistance from a HRS to a low resistance state (LRS)] and RESET [switching the resistance from LRS to HRS] voltages and the number of resistive switching cycles. The results of study of the thin film topography performed by atomic force microscopy (AFM) suggest that the difference in resistive switching parameters could be caused by structural properties of titanium dioxide layers deposited by different techniques.
Method and unit for dynamic control of conversion characteristics of spectrometric paths for multichannel charged particle registration systems
Authors: Tuboltsev Yu V , Bogdanov A A , Chichagov Yu V , Eremin I V , Eremin V K , Verbitskaya E M 
Published: December 2020

Abstract
A method and unit for dynamic control of conversion characteristics of spectrometric paths of multichannel charged particle registration systems based on specialized microchip with a large degree of integration similar to IDE1140 in structure is proposed. The conversion characteristics are controlled during operation of the device by auto-adjusting the offset and gain of the scaling amplifier. The proposed method allows to use the entire dynamic range of the analog-to-digital converter and adjust the temperature drift for each channel at the hardware level during operation of the device.
Spectral analysis of bone tissue of rats exposed to hyperthermia and mineral bone component injection
Authors: Timchenko E V , Timchenko P E , Pisareva E V , Vlasov M Y , Volova L T , Frolov O O , Fedorova Y V , Gorchenkova M Y , Daniel M A , Yagofarova E F 
Published: December 2020

AbstractUsing the method of Raman spectroscopy the study of bone tissue of rats has been made in this work after hyperthermia and injection of allogenic hydroxyapatite. It has been established that the process of thermal treatment of bone material up to 70°C for 15 minutes allows preserving organic components of biomaterials
Physical and mathematical modeling and formation of the optical signal transducer on the basis of gradient lithium niobate
Authors: Galutskiy V V , Kuzora V F , Shmargilov S A , Stroganova E V 
Published: December 2020

Abstract
The present research focuses on modeling and analyzing a PPLN-transducer as a logical element, taking into account the heterogeneity in dispersion of group velocities along its length, and aims at the creation of a gradient PPLN. Within the framework of the research, a model has been built and logical elements AND, OR, XOR have been simulated on the example of periodically poled waveguide structure of lithium niobate with gradient composition.
UV pulsed irradiation effect on the exciton luminescence of CuCl nanocrystals in borate glass
Authors: Babkina A N , Zyryanova K S , Egorova Y B , Nuryev R K 
Published: December 2020

Abstract
Heat treatment conditions effect on the characteristics of the Z3-exciton resonant luminescence of CuCl nanocrystals in potassium-aluminaborate glass is studied. The observed patterns of luminescence buildup are explained by the participation of thermal effects in recombination processes. The size effect in the resonance emission of Z3-excitons at 80 K is confirmed. The inverse dependence of the defectiveness of CuCl crystals in glass on the luminescence buildup rate of Z3-excitons is established.
Investigation of the interaction of a pair of bright optical spatial pyroelectric solitons during their in-phase propagation in an undoped lithium niobate crystal at a wavelength of 532 nm
Authors: Perin A S , Gapparova M N , Romanenko D K , Sokolnikov A V , Okunev D V , Mandel A E 
Published: December 2020

Abstract
The formation of two-dimensional bright spatial solitons by in-phase laser beams with a wavelength of 532 nm propagating in the bulk of photorefractive lithium niobate crystal under the reversal of the sign of the nonlinear optical response of the material with the contribution of the pyroelectric effect has been experimentally demonstrated. It is shown that varying the distance between the beams at the input face of the crystal leads to the interaction of pyroelectric solitons, which allows the formation of non-rectilinear propagation paths of light beams.
Polarization features of asymmetric TE and TM vortex modes
Authors: Egorov Yu A , Bretsko M V , Akimova Ya E , Volyar A V 
Published: December 2020

Abstract
This study is devoted to a new section in the field of singular optics-to beams carrying a fractional topological charge. A feature of this type of beams is structural instability, and with the slightest external perturbation, these beams form arrays of optical vortices. These vortices can be connected and, as it were, form an integral picture, or disintegrate due to the fact that during the propagation each of the vortices receives an additional phase incursion. These studies were based on a theoretical calculation and experimental study of the vector structure of beams transporting optical vortices with a fractional topological charge and the proof of the process of forming asymmetric TE (transversely electrical) and TM (transverse magnetic) modes in free space, and the study of the features of their “thin” vector structures in free space.
Optical glass-ceramics based on nanosized crystals of magnesium aluminate spinel doped with iron ions
Authors: Bukina V , Dymshits O , Alekseeva I , Tsenter M , Zapalova S , Khubetsov A , Zhilin A , Basyrova L , Volokitina A , Serres J M , Mateos X , Loiko P 
Published: December 2020

Abstract
Transparent glass-ceramics of magnesium aluminum silicate system based on nanosized MgAl2O4 spinel crystals nucleated by TiO2 and doped with Fe2O3 were developed. Their structure and spectroscopic properties were studied. The glass-ceramics are important as reference samples in development of saturable absorbers in the short-wave infrared spectral range (2-3 μm).