bluuebunny/crossref_metadata_2025 huggingface dataset:
A search for gamma-ray counterparts to gravitational wave events in Konus-Wind data
Authors: Ridnaia A , Svinkin D , Frederiks D
Published: December 2020

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Using 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

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

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

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

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

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).
Bound states in the continuum in dielectric waveguides of finite size
Authors: Kutuzova Aleksandra A , Rybin Mikhail V
Published: December 2020

We study bound states in the continuum related supercavity modes in finite lattices of silicon rods. Two low-frequency symmetry-protected modes are examined. We find that Q factor has almost cubic dependence on the rod number and 50 rods are enough for Q exceeds 104. We discuss possible applications of these supercavity modes based on their electromagnetic field pattern. The structure surrounded by liquid media keeps its functionality by substitution silicon rods with rods made of Ge-Sb-Te.
Structure and luminescence properties of SiO2 sol-gel glass doped with Eu3+
Authors: Kravets V A , Ivanova E V , Zamoryanskaya M V
Published: December 2020

In this work, SiO2 sol-gel glass doped with Eu3+ was investigated its structural and luminescence properties. It was shown that a area containing crystallites of cristobalite with a size of about 45 nm is formed on the glass surface. The Eu3+ spectrum in surface area was obtained. It was demonstrated that the main part of the sample is X-ray amorphous; however, the Eu3+ spectrum in it demonstrates the presence of short-range order.
The GaAs laser photoconverter (λ 809 nm) current flow mechanisms at the temperature range of 100-420 K
Authors: Mintairov M A , Evstropov V V , Mintairov S A , Nakhimovich M V , Shvarts M Z , Kalyuzhnyy N A
Published: December 2020

The temperature dependences of the diffusion and recombination saturation currents and the energy gap have been obtained for a GaAs photoelectric converters. Saturation currents by IV characteristic analysis, and the energy gap by electroluminescence peak position have been determined. It has been shown that the relationship between saturation currents and energy band gap is characterized by the only parameter Jz (current invariant). At the temperature range of 100 -420 K this parameter does not depend on the temperature.
Gain spectra of lasers based on transitional dimension active region
Authors: Kornyshov G O , Gordeev N Yu , Payusov A S , Serin A A , Shernyakov Yu M , Mintairov S A , Kalyuzhnyy N A , Maximov M V , Zhukov A E
Published: December 2020

We present an experimental study of the optical gain of edge-emitting lasers based on a new type of quantum-sized InGaAs active medium grown on GaAs substrates, which we refer to as quantum-well-dots (QWDs). It is shown that the single layer QWD active region provide at least 33 cm−1 optical gain at 1030 nm comparable to the values typical for InGaAs quantum wells (QWs), and the width of the gain spectra characteristic for InAs quantum dots (QDs). Thus, QWD active region combines the advantages of both QW and QD heterostructures and has a great potential for improving characteristics of various semiconductor devices.
Vertical cavity surface emitting laser of 1.55 μm spectral range, manufactured by molecular beam epitaxy and wafer fusion technique
Authors: Blokhin S A , Bobrov M A , Maleev N A , Blokhin A A , Vasyl’ev A P , Kuzmenkov A G , Troshkov S I , Ustinov V M , Rochas S S , Gladyshev A G , Novikov I I , Karachinsky L Ya , Voropaev K O , Ionov A S , Egorov A Yu
Published: December 2020

The heterostructure design for 1.55 μm range VCSELs is proposed and realized. The wafer fusion technique was used to form the final heterostructure. The growth of AlGaAs/GaAs distributed Bragg reflectors (DBRs) on GaAs substrate and the optical cavity with an active region on InP substrate as well as a tunnel junction (TJ) regrowth was performed by molecular beam epitaxy (MBE). A key feature of the proposed design is the use of n++-InGaAs/p++-InGaAs/p++-InAlGaAs TJ, which allows, due to the effective removal of oxide from the InGaAs surface, to use MBE for re-growth of the TJ surface relief. Despite of the presence in heterostructure a narrow-gap InGaAs layers, a noticeable increase in internal optical loss in lasers can be avoided due to the short-wavelength shift of the edge of interband light absorption in ++-InGaAs layers (Burshtein-Moss effect). Fabricated VCSELs demonstrate single-mode operation with a threshold current less than 2 mA and a slope efficiency of ~ 0.46 W/A, which are comparable with characteristics of VCSELs with n++/p++-InAlGaAs TJ with a similar level of mirror losses.
Photoelectric properties of MIS structures on high-resistivity p-type silicon with aluminium nitride tunnelling insulator
Authors: Bazlov N V , Danishevskii A M , Derbin A V , Drachnev I S , Kotina I M , Konkov O I , Kuzmichev A M , Lasakov M S , Trushin M V , Unzhakov E V
Published: December 2020

Photoelectric properties of MIS tunnel diodes produced on high-resistive p-type silicon wafers with thin aluminium nitride AlN insulator layer and Pd or Al metal gate electrodes were investigated. It was found that synthesized AlN films possess a fixed positive charge, which leads to the creation of near-surface inversion layer in silicon substrate. The ratio of the photocurrent to the dark current K = Iph / Idark (on / off ratio) was found to depend on the gate electrode material, illumination intensity and the applied reverse bias. For studied MIS structures K ratio varied from 10 4 to 10 5 and was two orders of magnitude higher than that for the control MS structure without the insulator layer. High on / off ratio of such MIS structures with AlN tunnelling insulator promotes their application as an effective photodetectors in optoelectronics.
An experimental demonstration of the effect of mechanical stresses on the laser generation of acoustic vibrations in various materials
Authors: Glazov A L , Muratikov K L
Published: December 2020

The process of generating an acoustic signal during laser heating of metals and dielectrics is analyzed in the framework of the theory of thermoelasticity. A comparison of the experimental optoacoustic signal and the theoretical distribution of mechanical stresses for plates with a hole of aluminum alloy and silicon nitride is performed. It was found that the standard theory of thermoelasticity can qualitatively describe the dependence of the optoacoustic signal on the stress near the hole in the silicon nitride plate, but is not enough to correctly describe the dependence of the signal on the stress near the hole in the metal plate. It is noted that in order to achieve agreement between the obtained experimental and theoretical results for metals, in addition to the thermal effect of laser radiation on the lattice, it is necessary to take into account the additional effect of the electron system.
Investigation of time and frequency characteristics of the electrocaloric response in ferroelectric materials
Authors: Anokhin A S , Es’kov A V , Pakhomov O V , Semenov A A , Lähderanta E , Tselev A , Kholkin A L
Published: December 2020

Recently, much attention has been paid to the development of new microminiature solid-state cooling devices and heat energy converters based on the electrocaloric effect. But researchers pay little attention to aspects of the electrocaloric effect associated with its time and frequency characteristics. These phenomena must be taken into account when developing highly efficient thermodynamic cycles for solid-state cooling devices. In this work, we conducted an experimental study of the dependence of the electrocaloric response of a ferroelectric sample on the period and duty cycle of the control signal was studied. It was demonstrated, that value of electrocaloric response in studied ceramics may vary by more then 15% depending on period and duty cycle of electric pulses.
On the electrical conductivity of YCrO3 porous ceramics
Authors: Malcev D D , Sinelshchikova O Yu , Popkov V I
Published: December 2020

In this work, nanocrystalline yttrium orthochromite (YCrO3) was synthesized via the solution combustion method using metal nitrates and glycine. The resulting powder was used for sintering YCrO3 porous ceramics. The SEM, EDX, PXRD and TMA were used to examine structural and morphological features of both the preceramic powder and the sintered ceramics. The electroconductivity of the obtained porous ceramics was investigated in the temperature range from 25 to 1200 °C. YCrO3 bulk conductivity was found to depend on the microstructure and the pore volume fraction: at temperatures below 400 °C the electrical conductivity was higher than the values for high-density ceramics, while for temperatures above 800 °C the electrical conductivity of the resulting material approaches the values of high-density ceramics (σdc
= 1.97·10−2 S/cm at 1000 °C).
Peculiarities of the development of ionization instability of various scales in the air gas discharge
Authors: Lapushkina T A
Published: December 2020

In this work, the air gas discharge of constant voltage, organized in an unlimited chamber without the side walls, is experimentally studied, which leads to a stratification of the discharge region due to the development of ionization instability. Depending on the conditions of the discharge (pressure or magnitude of the gas discharge current), the scale of the ionization striations changes, which leads to the layered structure of the plasma medium and the possibility of creating layers of different thicknesses, where not only the electronic temperature, but also the gas temperature are different. Various types of discharge were obtained in the work, from large-scale structured ones (3-5 striations per discharge length) to small-scale ones (20-25 striations per discharge length), and the conditions for their occurrence and development were investigated. The main diagnostic parameters are gas pressure, the magnitude of the gas discharge current, which is changed by a change in the load resistance, the size and frequency of the ionization waves, estimation of electronic and gas temperatures at different points of the discharge. Gas discharges of this kind can be used to structuring the air environment, gas mixing and supersonic flows control.
Numerical simulation of turbulent wake of a flat plate subjected to adverse pressure gradient
Authors: Guseva E K , Strelets M Kh
Published: December 2020

Results are presented of a numerical study of the flat plate wake evolving under adverse pressure gradient. They include both results of the computational experiments aimed at supporting high accuracy of the performed scale-resolving simulations of the flow and results of the simulations aimed at quantitative evaluating of the effect of the adverse pressure gradient on the mean flow and statistical characteristics of the wake.
An experimental study of the effect of a shock wave front on a permeable material
Authors: Masyukevich A V , Bulovich S V
Published: December 2020

The interaction of shock wave with granulated layer of spherical particles was experimentally investigated in the atmospheric shock tube. There was a gap between porous layer and the end wall of tube. Two different cases were considered. In the first the structure and position of porous layer remained unchanged. In the second case, after the impact of the incident shock wave on the granular layer, the structure was destroyed and it turned into a moving particle cloud. For both cases, wave structures that occur both in front of porous layer of granular particles and in the gap between the layer and the end wall of the shock tube are obtained and analyzed.
Investigation of wood ash melting by AC plasma torch
Authors: Subbotin D I , Kirillova A A , Godina E P
Published: December 2020

One of the methods for processing ash from waste incineration can be plasma treatment. In most cases, studies are carried out with inert gas systems. The size of the processed pieces of sintered ash is 10-50 mm. The power of the plasma torch is 75 kW at an air flow rate of 8.8 g/s. Temperature control on the ash surface is carried out using a two-beam pyrometer. The total melting time is 7 hours. The temperature of the least heated part of the melt is 1300°C. Liquid slag is cooled in a large number of cold water. Upon contact of the hot molten slag with water, glass-like pieces 2-3 mm in size are formed. The composition and properties of the slag are studied using a scanning electron microscope with an attachment for elemental analysis and an X-ray diffractometer.
Numerical simulation of gravity-driven mono- and polydisperse bubbly flows in a three-dimensional column in the framework of the Euler-Euler approach
Authors: Chernyshev A S , Schmidt A A
Published: December 2020

The paper presents a comparison of the results of numerical modeling of the three-dimensional flow of mono- and polydisperse media in a rectangular bubble column reactor. The mathematical model used in the paper is based on the Euler – Euler description of a multiphase medium taking into account interphase momentum transfer, turbulence modeling of the carrier phase with bubble induced turbulence and polydispersity in the framework of the inhomogeneous multiple-size group (MUSIG) model. The comparison is carried out of the mono- and polydisperse approaches under the conditions studied for simplified and full formulations. Numerical results are compared with the available experimental data and simulations of other authors.
Compounding and technological methods for increasing the efficiency of wood matrix mineralization
Authors: Kilyusheva N V , Danilov V E , Ayzenshtadt A M , Belyaev A O
Published: December 2020

This paper presents the results of a study of the efficiency of mineralization of the plant matrix of pine wood samples by immersion of experimental samples in an organo-mineral water suspension (dispersion medium) and holding for 24 hours under natural conditions, as well as under autoclave impregnation at an excess pressure of up to 1.5 MPa. To create the necessary working pressure in the autoclave, an inert gas (argon) was used. As working fluids, we used an aqueous solution of arabinogalactan, aqueous suspension containing polymineral sand, pre-dispersed to a fine state and a soluble complex obtained by mechanical mixing of the above components. Prototypes were made from ordinary pine wood. The effectiveness of impregnation was evaluated by increasing the density of samples. In addition, data on changes in Brinell hardness, compressive strength of samples along the fibers, and water absorption of impregnated wood were obtained. It was found that autoclaving in the studied mode leads to an increase in the density of samples by more than two times, reduces their water absorption, and increases strength by 84%.
Formation of clathrate structures in surface layers of heavily diluted aqueous solutions
Authors: Shostka V I , Shostka N V , Halilov S I , Vershitsky V I
Published: December 2020

The paper presents the results of experimental studies related to the formation of clathrate structures in highly diluted hydrophilic aqueous solutions. A method based on the interference of laser beams transmitted through a water lens of various configurations is applied. It shown that the studied solutions have properties associated with the self-organization of the structure in clathrate states due to the cooperative effect of changes in the inhomogeneous network of hydrogen bonds. It is found that in the range of small concentrations of dissolved substances in aqueous solutions, in spite of some stabilization of the structures in the formed clathrates depending on the number of interacting molecules, the formation of associates of various shapes is possible. An increase in the content of dissolved substances in aqueous solutions leads to the destruction of the ordered structure, and the excess molecules of the hydrophilic substance, combined together, form complex aggregates or their “islands”.
Electron-stimulated desorption of potassium atoms from a potassium layer adsorbed on a tungsten covered with a gold film
Authors: Gromov I A , Kuleshova T A , Kuznetsov Yu A , Lapushkin M N , Samsonova N S
Published: December 2020

For the first time, electron-stimulated desorption (ESD) of K atoms from the K layer adsorbed on W covered with an Au film was detected and recorded, and the ESD yield was measured by a direct method depending on the electron energy, concentration K, and the thickness of the Au film. A model is proposed that explains the processes of ESD of potassium atoms from the surface.
Technology of nanoplanar surface preparation of GaSb and InP substrates
Authors: Zhirnov A M , Marichev A E , Epoletov V S , Prasolov N D , Levin R V , Pushnyi B V
Published: December 2020

In this work, we studied the surface quality dependence of GaSb and InP substrates prepared by various methods of pre-epitaxial preparation, specifically, etching, annealing, and growing a buffer layer. Our main goal was to obtain the most efficient method of pre-epitaxial treatment, which allows preparing substrates with the best surface quality. The experimental results were evaluated by the parameter of the average roughness of the substrate. As a result a combination of the methods of pre-epithelial preparation of GaSb and InP substrates was selected, which made it possible to obtain a root-mean-square surface roughness about 0.6–0.8nm.
Paramagnetism on the temperature-magnetization dependences in a superconducting semiconductor solid solution (PbzSn1-z)1-xInxTe
Authors: Denisov D V , Mikhailin N Yu , Shamshur D V , Parfeniev R V
Published: December 2020

In this work we studied magnetic properties of the semiconductor solid solution (PbzSn1-z)1-xInxTe in superconducting state. Peak-effect in magnetization vs magnetic field dependences was observed, and a paramagnetic response was obtained in superconducting state at certain magnetic fields and temperatures in a range of compounds. Possible relation between those effects is considered.
Supramolecular textures formed on polymer coating surface of solids: a mean-field study
Authors: Maksimova O G , Smirnov V V , Osipov S V , Menshikov E V , Egorov V I , Maksimov A V
Published: December 2020

We developed a mean-field model describing a system of interacting polymer chains in the contact with a spherical granule surface. It is shown that the size of supramolecular structures formed by macromolecules near the granules does not depend on the size of these granules but depends on the temperature and properties of polymer chains. We revealed that the size dependence of supramolecular formations on the mean molecular field changes sharply at the certain critical field value which depends on the temperature.
The change of the Earth Pole oscillational mode under the Lunar-Solar perturbations
Authors: Yu Barkin M , Bondarenko V V , Perepelkin V V
Published: December 2020

This article investigates conversion between different modes of the Earth Pole oscillational process which influence the precision of the Pole position forecast. It identifies the perturbing harmonic that leads to the saltatory change of the average velocity of Earth Pole motion and to the change of its oscillational mode. It also shows the qualitative conformity between the four-frequency model of the Pole motion and observation data based on the graph of phase variation of the polar angle of the Pole rotation around the average position.
An analytical calculation and applications of the kinematic characteristics of the motor vehicle movement at an oblique hitting the side of a cable barrier
Authors: Kolesnikova G P
Published: December 2020

An analytical calculation of the kinematic characteristics of a motor vehicle allows both checking the correctness of the developed FE model of cable barriers and can be used to study the movement of a motor vehicle directly during the construction of the FE model. In the article it has been provided recommendations on the procedure for conducting a virtual test in order to verify the correctness of the construction of the finite element (FE) model of the cable barriers, and also it has been analyzed the possibility of using analytical trajectories in the study of passive safety of the driver/passenger. FE modeling has been performed using the LS-Dyna multipurpose finite element complex. The present work continued researches which has been published as [1] and [2].
Three-parameter Model for Predicting the Earth pole Trajectory
Authors: Yu Barkin M , Perepelkin V V , Pochukaev V N , Filippova A S
Published: December 2020

A three-parameter model for forecasting the Earth pole motion is considered - a model with the minimum possible number of independent parameters and a satisfactory forecasting accuracy. The results of numerical simulation of the Earth pole oscillatory motion are compared with the observational data from the International Earth Rotation and Reference Systems Service. An analysis of the model accuracy is given.
Analysis of the effect of the physicomechanical properties of composite materials of carrier layers on the stress state of sandwich shells with rectangular cutouts
Authors: Bakulin V N
Published: December 2020

A model is described for studying the effect of the physicomechanical characteristics of composite carrier layers on the stress and strain state of sandwich cylindrical shells weakened by rectangular cutouts. The finite element model considered allows us to perform the layer-by-layer analysis of the stress in a wide range of physicomechanical characteristics of the layers. To obtain effective approximations leading to a high convergence rate of numerical solutions and to build the finite element of the carrier layers, the equations of the general sell theory are used. To build the finite element model of the filler, the elasticity theory equations for a three-dimensional body and the carrier layer finite element approximations obtained are applied. The effect of the physicomechanical characteristics of composite carrier layers on the stress and strain state for sandwich cylindrical shells with rectangular cutouts is studied.
Generalized multiparametric models for predicting the physical and mechanical properties of composites when exposed to extreme environmental factors
Authors: Gusev E L , Bakulin V N
Published: December 2020

Based on the formulated principle of model multiplicity forecasting and the introduced concept of optimal forecasting models difficulties in the framework of variational statements the questions of development are investigated effective refined forecasting methods that determine the physical-mechanical characteristics of structures made of composite materials. A system of additional ratios has been developed, including them in the structure of the initial tasks allowed us to significantly reduce the dimension the original variational statements of the inverse problems of forecasting and significantly narrow down the original set of valid model options predictions.
PAPR Performance of Carrier Interferometry OFDM by Wavelet Transform in Cooperative Relay Networks
Authors: Ciflikli Cebrail , Yazlik Bilgin
Published: December 2020

Cooperative diversity has spatial diversity effects on wireless communication systems to combat fading effects by using idle antennas as relays which are already located in the system. OFDM based cooperative communication is widely used in wireless communication systems and promises high data rate. However, OFDM has high PAPR problem. The high PAPR causes the interference and performance loss. Carrier interferometry codes boost overall performance of OFDM communication systems and decrease the level of PAPR. FFT can be used to realize carrier interferometry with no performance degradation. In this paper PAPR performance of the carrier interferometry OFDM by wavelet transform is analysed in a cooperative relay network. The results show that, the system which is a novel design of CI-OFDM has obviously better performance than traditional systems in terms of both BER and PAPR with the assist of wavelet transform.
Application Status and Analysis of BIM in Pit Engineering
Authors: Li Xiaojun , Zhang Xianyu , Shen Yi , Bai Yun , Yang Guanghui
Published: December 2020

BIM has developed rapidly in recent years, but there are still problems in the field of pit engineering, such as lack of standards, missing data, and incompatibility of software. The keyword co-occur net and the publication status from CNKI and web of science are overviewed, and the application cases of design, construction and monitoring phases are analysed. Then some typical problems are summarized, such as the difficulty in establishing the interfaces between BIM and FEM software, low utilization in a project and the BIM platform problem. And suggestions for the development in pit engineering are introduced, including formulating standards and codes, developing localization geotechnical BIM software and further research on BIM/FEM integration.
A Research on Key Technologies in All-Optical Label Switching Networks
Authors: Yan Yuchen
Published: December 2020

With the rapid development of Internet technology, the capacity of communication system is increasing rapidly and traditional switching technology based on optical-electrical-optical (O/E/O) conversion cannot satisfy requirements for information exchange. Construction of a high-speed, large-capacity, high-bandwidth all-optical switching network will be the future direction of communication systems. In this paper, the key technologies in all-optical label switching networks are investigated. First, five kinds of optical label technologies are studied. The principles and implementation methods of them are analyzed and compared. Then, optical switching fabrics based on different kinds of optical switches are discussed. Next, a 160Gb/s Optical Time Division Multiplexing (OTDM) signal 1 × 8 packet switching experiment is introduced. Finally, the research work is summarized, and the design of core nodes in optical packet switching network is prospected.
Plant-derived anthocyanin extract for qualitative test of food additives and preservatives
Authors: Do Thi-An-Sa , Thach-Nguyen Roya , Lam Hoa-Hung , Dang-Bao Trung
Published: December 2020

In this study, anthocyanin was extracted from purple cabbage and skin of vigna cylindrica skeels in aqueous solution at room temperature. The anthocyanin extracts indicated the pH-dependent color changes, envisaging the detection of the chemicals involving urea, nitrite, benzoate, formaldehyde and borax. The response time of the tests was quickly (either immediately or less than 5 min) and the solution colors were stable until 1 hour, offering the good sensitivities towards formaldehyde (detection limit of 250 ppm) and borax (detection limit of 10 ppm).
Study of the influence of substrate bias voltage on the texture of Nb coatings deposited on a Cu substrate
Authors: Lozovan A A , Betsofen S Ya , Labutin A A , Lenkovets A S , Grushin I A , Aleksandrova S S
Published: December 2020

The phase composition and texture of Nb coatings deposited using an inverted magnetron at voltages on the Cu substrate from 0 to –300 V were investigated by an X-ray method. With an increase in the voltage on the substrate, the thickness of the coating decreases from 9–10 μm at voltages up to –100 V and decreases to 2 μm at –250 V. The texture of the coatings varies non-monotonically from (110) to (111), while at high voltages on the substrate in the range from –250 to –300 V, the Nb coating is characterized by a textureless state.
Influence of nanoparticle additions to the electrolyte on the structure, composition and corrosion resistance of oxide layers formed by PEO on cast Mg alloy
Authors: Polunin A V , Cheretaeva A O , Borgardt E D , Shafeev M R , Katsman A V , Krishtal M M
Published: December 2020

The effect of various nanoparticles (NPs) added to the electrolyte on the composition, structure, and properties of oxide layers formed by plasma electrolytic oxidation (PEO) on a cast magnesium alloy AZ81A was studied in this work. The oxide layers were obtained by alternating adding silicon dioxide SiO2, silicon nitride Si3N4, yttrium oxide Y2O3, tungsten carbide WC, and titanium carbide TiC NPs to the electrolyte. The obtained oxide layers were studied by scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDXMA), X-ray diffraction analysis (XRD), instrumental indentation and potentiodynamic polarization (PDP). The thickness, roughness, microhardness, adhesion and corrosion resistance of the oxide layers were determined. The greatest increase in the oxide layer thickness, in its hardness and corrosion resistance was observed for TiC and WC NPs added to the electrolyte during PEO. The addition of Si3N4 NPs leads to a decrease in the oxide layer thickness and its hardness, while the corrosion resistance is comparable to the one of the uncoated magnesium alloy.
The effect of crater creation on the surface of steel targets under irradiated of high-current pulsed electron beams
Authors: Teryaev D A
Published: December 2020

The present paper reviews the experimental results dedicated by the effect of the irradiation conditions by intense pulsed electron beams on crater creation taking place on the surface of EP866sh refractory steel targets. The most probable mechanisms of crater creation are also described.
Parameterization of the characteristics of the melt pool using the video diagnostics of the laser metal deposition process
Authors: Zavalov Yu N , Dubrov A V , Makarova E S
Published: December 2020

The dependences of the geometric characteristics of the melt bath on the scanning velocity and radiation power during laser metal deposition (LMD) are shown. The data were obtained experimentally at different values of the intensity Is up to 60 kW/cm2 in the range of changes in the specific energy per unit surface area Es (20…60) j/mm2 using the high-speed video camera installed in coaxial scheme. A powder (40…100) microns of PR-Kh18N9 austenitic steel with a mass flow rate of 8.4 g/min was used. It is found that the length of the melt pool L increases with the growth of Is and practically does not depend on the scanning velocity in the range (5…10) mm/s. The melt volume is estimated taking into account the measured track height. At the same velocity, the volume of the melt increases with the value of the Is exceeding the threshold. The value of threshold increases with increasing velocity. The volume of the melt increases with the specific energy Es. The relationship between the geometric characteristics of the melt bath and the shape of the track formed in the LMD process is shown.
Fuel metering and control optimization based on combustion state diagnosis
Authors: Wang X H , Chen H T , Zhu X X , Zhang J L , Liu W L , He H H
Published: December 2020

It is hard to accurately meter the fuel feed into the furnace for a double-in and double-out pulverizing system, which affects the fuel control quality and also the main steam pressure of a boiler. A correction method for the indirect measurement model of the coal metering feed into the furnace for double-in and double-out pulverizing system is proposed based on the combustion state diagnosis of a burner using fuzzy C-mean clustering method, of which is applied in a 620MW super critical power unit. The engineering application results suggested that the method of this work is effective to improve the fuel control quality during the mill start and stop process. By using the method of this work, the controlling deviation between the target value and the measured value of the main steam pressure is within 0.2 MPa, while it is about 0.6 MPa when the fuel control is without correction.