bluuebunny/crossref_metadata_2025 huggingface dataset:
The multiparametric method of analyzing the lunar dynamic processes
Authors: Mubarakshina R R , Andreev A O , Nefedyev Y A , Borovskih V S , Churkin K O
Published: December 2019

The present paper focuses on studying the lunar dynamic processes. As selenophysics is a complex system and moonquakes are complex multi-parametric systems too, the analysis of moonquakes and the development of an analytical theory of such processes require the application of robust methods and using multiparametric calculations. Moreover, selenophysics is a more complex system than geophysics. In this connection, the study of lunar processes and determination of moonquakes parameters require reliable estimates of the results obtained and application of the methods of complex system physics. The observations from “Apollo” space mission were used in the study, and the multiparametric correlation method was developed for their processing. Currently, one uses various methods, similar to the ones for the Earth’s seismic process investigation, such as seismic interferometry for deep moonquakes, time scales analysis, seismic phenomena magnitude gradient change, solution of the inverse problem of signals reflection on “Apollo” stations. Now, on the basis of moonquakes data, the internal structure of the Moon is being studied. Using the moonquakes data, a model of the lunar tidal parameters had been developed and was later refined by “GRAIL” (gravitation), “LRO” (shape), and “LLR” (rotation) space missions’ data. As a result, in the areas where deep moonquakes occurred, the inner layer of the Moon with low viscosity was found. In the present work, the author’s method of analyzing moonquakes allowing to conduct multiparametric analysis of seismic time series observations was applied. The method was developed for the investigation of seismic processes occurring on the Earth using the space observations. In order to provide qualitative description of moonquakes dynamical parameters, the special software was developed.
Effect of sodium hypochlorite on nucleic acids of different primary and secondary structures
Authors: Osinnikova D N , Moroshkina E B , Mokronosova E S
Published: December 2019

The effect of sodium hypochlorite (NaClO) on nucleic acids (NAs) was investigated. The effect of biomolecular structure on resistance to hypochlorite was analysed: plasmid bacterial DNA, calf thymus DNA, synthetic polyadenylic-uridic acid samples were studied, as well as individual nucleotides (adenosine-5’-tetraphosphoric acid and guanosin-2’, 3-cyclophosphoric acid). The effect of sodium hypochlorite on DNA was investigated depending on the concentrations of the components. We have also performed detailed analysis of the kinetics of the reaction between the NAs and NaClO. It was found that both the destruction of the secondary structure of DNA (denaturation) and the chemical modification of nitrogenous bases, presumably chlorination, occur. Presence of a stable double-stranded structure of DNA slows down the chemical reaction of sodium hypochlorite with nitrogenous bases of DNA.
Study on the processes of nitrogen adsorption and capillary condensation in the powders of calcium hydroxyapatite
Authors: Khalugarova K. N. , Maraeva E. V. , Moshnikov V. A.
Published: December 2019

This work is devoted to the study of mesoporous structure parameters of calcium hydroxyapatite powders on the basis of data obtained by nitrogen thermal desorption method. The isotherms of nitrogen desorption/adsorption on the samples of hydroxyapatite and the changes in their porous structure parameters depending on the temperature of the heat treatment are discussed.
Detection and image processing after nucleic acid amplification in emulsion
Authors: Tupik A , Novikov L , Evstrapov A
Published: December 2019

To analyze the results of amplification in the emulsion, special software package was developed. It was used to process images of emulsions, in which digital loop mediated isothermal amplification (LAMP) was carried out. Program units made it possible to combine a set of images of a reaction chamber into a single image file, count the number of droplets in chamber, and obtain histograms of the size distribution and fluorescence intensity of the droplets. The data obtained are necessary at the stage of equipment development for the selection of design parameters and for improving of the experiment methodology.
Microfluidic device for hydroxyapatite crystals growth process study
Authors: Rusanov V S , Afonicheva P K , Koryakina I G , Evstrapov A A
Published: December 2019

Heart problems tend to occupy a leading position among elderly diseases. Organ-on-a-chip is suitable technology for researches of human body mechanisms without animal models. One of the widely spread diseases is valve calcification. To study growth of hydroxyapatite crystals a microfluidic device was created. For simulating the heart valve on microfluidic device COMSOL Multiphysics® was used. The device was fabricated from polydimethylsiloxan using spin-coating method for membrane which acts as a valve and soft lithography for the other parts.
Mathematical model of epileptic discharge propagation
Authors: Kozeletskaya M G , Chizhov A V
Published: December 2019

Mathematical modelling of epileptic activity of a nervous tissue is an open problem. The previously developed biophysical model Epileptor-2 which describes the excitability of the neural network and the ionic dynamics reproduces ictal (convulsive) and interictal (usually pre-convulsive) discharges as a spatially homogeneous activity. To describe the spatial propagation of the discharges across the cerebral cortex a generalization of the model is proposed, based on an elliptical equation that takes into account the propagation of neuronal impulses via axodendritic trees. Simulated spatio-temporal patterns of extracellular potassium concentration as of the main characteristic of spatial excitability reflect the wave-like nature of the discharge propagation and are comparable with experimental observations. The propagation of neural impulses via axo-dendritic trees may play the main role in the mechanism of propagation of ictal discharges.
Application of ultrasound thermometry technique in case of local HIFU heating of test-object
Authors: Ivanova Y F , Yukhnev A D , Gataulin Y A , Smirnov E M , Tarkhov D A , Berkovich A E
Published: December 2019

The present work is aimed at development of a method for estimation of the accuracy of ultrasound thermometry (UST) when applying during local HIFU heating of a tissue-mimicking material (TMM). The method is based on comparison of the ultrasound measurement results with a temperature field reconstructed inside the TMM using data of the infrared (IR) camera surface measurements. In the case presented, the HIFU transducer heated up the TMM by 30 °C for 10 s in the focus area. Ultrasound signals were processed using an in-house UST application software. A 3D temperature field inside the TMM was reconstructed using a method based on the neural network approach. As a result, it has been achieved a good agreement between the UST measurement data and the reconstructed temperature field, especially for the points along the HIFU transducer axis.
Development of a multi-sensor analytical trainable system for non-invasive evaluation of adaptedness status of hazardous occupation specialists
Authors: Zaitseva A Yu , Kislyakova L P , Kislyakov Yu Ya , Avduchenko S A
Published: December 2019

Several studies have been conducted in order to develop a new method of non-invasive diagnostics of performance ability of hazardous occupation specialists in terms of the exhaled air condensate parameters with the use of an artificial multi-sensor trainable diagnostic system. The method is based on applying an array of poly-selective electrochemical sensors with cross sensitivity to main physiologically important components of a subject medium. Training of the system was implemented according to the principle of grouping test persons using mathematical methods of data processing and correlation with real adaptedness level data obtained during medical and biological examinations. After having been trained, the analytical system enabled subsequent recognition of the “image” of a testee and assigning them to an adaptedness level group. The results obtained prove feasibility of the new multi-sensor trainable complex, its suitability for adaptedness status evaluation of hazardous occupation specialists.
Amplification of the propagating plasmon in a periodical structure with an active graphene
Authors: Moiseenko I M , Mashinsky K V , Popov V V , Fateev D V
Published: December 2019

The amplification of the unidirectionally propagating plasmon modes excited by the incident terahertz wave in a periodical structure with an active graphene is studied theoretically. The effective excitation of propagating plasmon mode occurs due to the simultaneous excitation of “radiative” and “nonradiative” plasmon modes at the same frequency. The amplification of propagating plasmon modes is due to radiative recombination in inverted graphene.
Features of the construction of the noise compensation circuit of a small-sized active phased antenna array
Authors: Moroz A V , Davydov V V , Malanin K Yu , Krasnov A A , Rud’ V Yu
Published: December 2019

In an article the influence of active and passive interferences on the operation of X-band radar are considered. A new way to compensate for this interference is proposed. To implement this method, a new interference compensation unit based on horn antennas is developed. The experimental investigation results of unit work, as a separate device, and as part of the radar station are presented.
Anisotropic energy gap of low-frequency AFMR mode in FexGa1-xBO3 single crystals
Authors: Mogilenec Yu , Seleznyova K , Strugatsky M , Yagupov S , Drovosekov A , Kreines N , Kliava J
Published: December 2019

Diamagnetically diluted iron-gallium borate Fe
x
Ga
1-x
BO3 single crystals have been studied by Antiferromagnetic Resonance (AFMR) at 77 K in the frequency range of 17 to 25 GHz in magnetizing fields up to 10 kOe. Anisotropic energy gap of the low-frequency AFMR mode has been determined under the rotation of the magnetizing field in the basal plane of the crystals. The results show a reduction of the anisotropic energy gap with decreasing x.
Surface potential response from GaP nanowires synthesized with mixed crystal phases
Authors: Kyeyune B , Soboleva E , Geydt P , Khayrudinov V , Alekseev P , Lipsanen H , L¨ahderanta E
Published: December 2019

In this work, we investigate variations of surface potentials along a single gallium phosphide (GaP) nanowire (NW) synthesized with a mixed crystal phase along the growth direction. GaP NWs synthesized with both wurtzite (WZ) and zincblende (ZB) phases were studied. The measurements were performed on a standard Atomic Force Microscopy (AFM) set-up equipped with Kelvin Probe Force Microscopy (KPFM) module in PeakForce Tapping Mode. KPFM Measurements from two structures were analyzed. Variations of surface poten-tials were observed in a single GaP NW with WZ/ZB segments. An average difference in surface potential was 55±11 mV. This is explained by different crystal structures along the NW. The work expands the understanding of crystal structure-dependent electrical transport properties of GaP NWs.
Monte Carlo study of β-Ga2O3 conductivity
Authors: Abdrakhmanov V L , Konchenkov V I , Zav’yalov D V
Published: December 2019

Using semiclassical Monte Carlo simulations a conductivity of β-Ga2O3 is investigated considering a scattering of charge carriers on acoustical phonons, polar optical phonons and charged impurities. Modelling takes into account 12 IR active polar optical phonons modes. Dependence of mean collision frequency on energy of charge carriers is examined. The results are compared with the conclusions of other groups of researchers.
Model of hydrogen diffusion in titanium with the formation of hydride phases
Authors: Zaika Yu V , Denisov E A , Rodchenkova N I
Published: December 2019

The problem of predicting the behavior of structural materials in hydrogen-bearing media (including extreme operating environments) cannot be solved without a thorough understanding of the mechanisms of hydrogen accumulation and transfer inside these materials. This issue is especially pressing for hydride-forming materials, such as widely used titanium alloys. Titanium and its alloys are used, in particular, in designing power and chemical reactors, for the geological disposal of highly radioactive waste. The paper presents a nonlinear mathematical model of hydrogen permeability taking into account the possible formation of hydride phases (after certain concentrations of dissolved atomic hydrogen are attained), and the iterative method for solving the corresponding boundary value problem based on implicit difference schemes.
The phenomenon of nonstationary nutation in the system of two-level quantum wells of a periodic superlattice with strong magnetic quantization
Authors: Nikoghosyan H S , Manukyan V F , Nikoghosyan G H
Published: December 2019

We investigate the superposition of nonstationary nutation processes that arose during the interaction of two-level systems of quantum wells of a superlattice with two exciting coherent optical pulses with various resonance detunings. According to the model under consideration, dipole transitions in two-level systems of quantum wells under the action of exciting pulses occur between the Landau levels of the main mini-band of the superlattice conduction band. This gives a direct opportunity to study the controlled variation of the course of optical nutation processes, by changing the intensity of an external quantizing magnetic field.
Gold nanoclusters on GaAs(001) surface: atomic force microscopy and optical spectroscopy of plasmons
Authors: Berkovits V.L. , Alekseev P.A. , Kosobukin V.A. , Ulin V.P. , Soldatenkov F.Yu. , Zgerskii I.V.
Published: December 2019

Gold nanoclusters of two different kinds are found to occur on annealing of thin Au films deposited on either oxidized or nitridized GaAs(001) surfaces. The morphology of Au/GaAs interfaces is characterized, and the gold nanoclusters are established to cause two resonant peaks in optical reflectance spectra at the energies of 1.6 eV and 2.15 eV. Using the data of reflection spectroscopy and theoretical analysis, we assign the latter peak to localized plasmons of Au nanoislands located on Au/GaAs surface. The former peak is attributed to plasmons of prolate Au nanoclusters buried in GaAs crystal just near its surface. As well, plasmonic anisotropy of Au nanoclusters formed on nitridized GaAs surfaces is detected using reflectance anisotropy spectroscopy.
Resistive switching of CuO nanofibers embedded into hollow channels of SiO2 layer
Authors: Belov A.N. , Pavlova L.M. , Shevyakov V.I. , Pestov G.N. , Perevalov A.A. , Demidov Yu.A.
Published: December 2019

In this work, we have formed CuO memristive array embedded into porous SiO2 layer. Such an approach would create synaptic system on silicon substrate using standard integrated electronics operations. It also provides control over the geometric parameters of artificial synapses, which determines their synaptic weights. The results of synaptic behavior have shown that the value of synaptic weights and currents are dependent on the thickness of the CuO filled SiO2 porous layer.
Study of the formation of functional ceramic coatings on metals
Authors: Bykova A D , Markov M A , Krasikov A V , Belyakov A N , Makarov A M
Published: December 2019

The paper presents the results of experimental studies in the field of the formation of ceramic coatings using a complex method combining the benefits of microarc oxidation and cold gas-dynamic spraying. These coatings are characterized by high hardness, wear resistance and are an economical alternative to structural alumina ceramic materials for machine supports.
Silicon nanowires and their characterization in the process of metal-assisted chemical etching of c-Si using spectroscopic ellipsometry
Authors: Zharova Yu.A. , Tolmachev V. A. , Pavlov S.I. , Ermina A.A.
Published: December 2019

In this work, the preparation of c-Si nanowires was investigated using a two-stage metal-assisted chemical etching process. For characterization of structures at all stages of the process, spectroscopic ellipsometry was used and two approaches were used: a) determining and analysing the complex pseudo-dielectric function ε and b) determining parameters of simulated multilayer structures using the effective medium approximation. Taking into account the structure parameters measured from SEM images the spectra of ψ and Δ were calculated and fitted to the experimental ones to obtain best convergence. The study of metal-assisted chemical etching process the Si process is intended for the development of silicon technology for obtaining structures of various topology (morphology) with functional components and creating on their basis sensory elements for bio and chemical reagents, taking into account the possibility of integration with micro and nanodevices on the chip.
An investigation of the thermodynamic properties of long-chain molecular crystals and the possibility of their application as phase change materials
Authors: Borisov A K , Egorov V M , Marikhin V A
Published: December 2019

The thermodynamic properties of n-alkanes have been investigated by using differential scanning calorimetry. The impact of the chain length on the thermodynamic characteristics of the first order phase transitions in n-alkanes has been estimated. The n-alkanes homologous series has been analyzed using the theory of diffused phase transitions. The nuclei sizes of a new phase within the bulk of the initial phase have been estimated.
Effect of growth technological conditions on the heterointerface thickness in the InAs/GaSb strained-layer superlattices grown by MOCVD
Authors: Fedorov I V , Prasolov N D , Levin R V , Nevedomsky V N , Gordeeva A B , Pushnyi B V
Published: December 2019

In this article, we investigated the effect of technological growth parameters by metal-organic chemical vapor deposition (MOCVD) method on the thickness of the transition layers, which affect the value of tensile strain in the structure, in the InAs/GaSb superlattice. We consider that the thickness of transition layers depends on the roughness of the growth surface and the technological conditions of growing single layers in the superlattice. At the first stage, we have determined the optimal annealing parameters for the minimization of the substrate roughness as T = 650 °C and t = 8 min, with a minimum value of 1.1 nm. At the second stage, studies were carried out on the effect of the sequence of elements and the delay time of reagent supply during the growth of InAs and GaSb layers on the quality of heterointerface. The stress analysis of the obtained structures was performed by reflectance anisotropy spectroscopy. It was shown that a superlattice becomes less tense with the increase in the number of pairs of alternating layers.
Elastic properties of Ti and its alloys nanostrctured due to severe plastic deformation
Authors: Kardashev B K , Narykova M V , Betekhtin V I , Kadomtsev A G
Published: December 2019

Studies of elastic properties of titanium and its alloys processed by severe plastic deformation are presented. The evolution of the modulus of elasticity resulting from the transformation from a coarse-grained state to an ultrafine-grained one due to severe plastic deformation (SPD) was investigated. The acoustic composite oscillator technique was used to measure the elastic modulus in a wide strain amplitude range. The microstructure was studied in detail by scanning electron microscopy and electron backscatter diffraction methods. Parameters of nanoscale porosity were measured by small-angle X-ray scattering before and after treatment with a high hydrostatic pressure (1.5 GPa). In addition, densities of titanium and its alloys in various structural states were determined by the precision method of hydrostatic weighing. As experiments showed, noticeable changes in the elastic properties resulting from the change in the grain state can be attributed to several factors, such as dislocations, nanoporosity, high internal stresses, and the structure of the materials before SPD processing.
In situ study of elastic strain relaxation in metamorphic InAs(Sb)/In(Ga,Al)As/GaAs heterostructures by using reflection high energy electron diffraction
Authors: Fominykh N A , Solov’ev V A , Chernov M Yu , Ivanov S V
Published: December 2019

We report on a comparative study of the elastic strain relaxation in InAs(Sb)/In(Ga,Al)As heterostructures grown by molecular beam epitaxy on GaAs substrates via InAlAs metamorphic buffer layer (MBL) with and without a highly strained 5 nm-thick GaAs insertion. Reflection high energy electron diffraction was used forin situmonitoring an in-plane lattice parameter of the epitaxial layers during growth. As a result, critical thickness of the initial stage of the InAlAs metamorphic buffer layer as well as its corresponding composition were determined for the structures with different position of the GaAs insertion within the MBL. The structure with 5 nm-thick GaAs layer inserted in the InAlAs MBL directly after achieving the In content of 37 mol.% demonstrates the highest room temperature photoluminescence at a wavelength of about 3.5 μm.
Synthesis and optical properties study of GaAs epitaxial nanoparticles on silicon
Authors: Sapunov G A , Koval O Yu , Sharov V A , Dvoretckaia L N , Mitin D M , Bolshakov A D
Published: December 2019

The integration of direct bandgap III-V materials on Si is one of the main tasks on the way to the development of cheap and highly effective optoelectronic devices. The goal of this work is to study the morphology and optical properties of GaAs nanoparticles grown on Si(111) by molecular beam epitaxy (MBE). Nanostructure morphology is studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties are studied by photoluminescence (PL) and Raman spectroscopy. Interestingly, despite large lattice mismatch between the silicon substrate and GaAs no sufficient change of Raman spectra was observed for both continuous layer and nanoparticles indicating that they are relaxed. The room temperature PL signal in the red spectral range was obtained from the epitaxial structure. It is demonstrated that high pump optical excitation of the nanostructures can lead to sufficient change of the PL signal typical for photo-oxidized GaAs.
Characterization of optically inhomogeneous polymer layers with silver nanoparticles by spectroscopic ellipsometry
Authors: Lihachev A I , Brunkov P N , Nashchekin A V , Tolmachev V A , Vasileva M V
Published: December 2019

In this work it was shown the applicability of the spectroscopic ellipsometry technique for characterization of an optically inhomogeneous polymer film with silver NPs. The histogram of silver NPs distribution based on SEM images shows the largest number of NPs have a size in the range 15-35 nm and the filling factor as large as 6%. By using the possibilities of ellipsometry it was suggested a 3-layer inhomogeneous structure with different sizes of silver NPs covered by thin polyamide-6 film. Also existence of localized plasmon resonance in such NPs was observed by optical absorption measurements.
Clustering kinetics of fullerene C60 in a composite of polymethylmethacrylate – fullerene
Authors: Bogdanov Alexander A
Published: December 2019

The paper presents the results of studying the absorption spectra of a composite polymethylmethacrylate – fullerene C60. In this composite, a gradual process of fullerene clustering upon heating is registered. This made it possible to determine the diffusion coefficient of C60 molecules in this polymer.
AgInS2/ZnS nanocrystals as an active medium for cobalt detection
Authors: Korepanov O A , Mazing D S , Aleksandrova O A , Moshnikov V A
Published: December 2019

In this work, the effect of photoluminescence (PL) quenching of ternary chalcogenide AgInS2 nanocrystals (NCs), as well as the core/shell structure, with variation of the cobalt ions (Co2+) concentration in aqueous solution, was studied. The quenching effect is described using the Stern-Volmer equation. The PL spectra were modelled in the range of 450–800 nm using four Gaussian functions, which makes it possible to identify several bands of the PL spectrum.
Si(Li) detector with ultra-thin entrance window on the diffusive lithium side
Authors: Bazlov N. V. , Derbin A. V. , Drachnev I. S. , Gicharevich G. E. , Kotina I. M. , Konkov O. I. , Pilipenko N. V. , Chmel E. A. , Abolmasov S. N. , Terukov E. I. , Unzhakov E. V.
Published: December 2019

Present work reports the results of activities intended to reach thin Si(Li) detector entrance window on the diffusive lithium layer side. It was established that the new n-contact represented by a heterostructure of unalloyed amorphous n-type silicon a-Si:H allows one to achieve the entrance window thickness 3 – 4 orders of magnitude smaller than the lithium-side entrance window of standard Si(Li) detectors. The films of amorphous silicon were synthesized with MASD (magnetron assisted silane decomposition) method in mixture of SiH4 (25%) and Ar (75%) gases. Lithium layer surface resistivity and silicon target type (n- or p-) affection on electrical properties of Si(Li) detector contact produced were studied. The investigation performed had led to a technology of Si(Li) detector production with thickness of the entrance window on the diffusive lithium layer side below 0.1 µm.
Crystallization kinetics and luminescent properties of chromium-doped borate glass-ceramics
Authors: Babkina A N , Zyryanova K S , Agafonova D A , Nuryev R K , Kolobkova E V , Ignatiev A I
Published: December 2019

Chromium-doped alkali alumina borate glass was synthesized. The DSC studies exhibited glass transition temperature to be 425°C and glass crystallization temperature to locate in the 600 – 700°C range. After isothermal treatment of glass samples at temperatures from 540 to 700°C the chromium-doped borate glass-ceramics was obtained. The two bands of the glass absorption spectra shifted towards small wavelength region after the heat treatment with changing the glass colour. The XRD studies revealed the LiAl7B4O17: Cr3+ nanocrystals nucleation with the mean size of 12 – 25 nm. The glass-ceramics photoluminescence spectra possessed three intense bands in the 685 – 715 nm spectral region indicating high symmetrical environment around the chromium ions. The maximum value of the quantum yield was obtained after the heat treatment at 700°C was 50%.
Raman spectra of interface phonons in long-period AlN/GaN superlattices as a tool for determination of the structure period
Authors: Davydov V Yu , Smirnov A N , Eliseyev I A , Rodin S I , Zavarin E E , Lundin W V , Pankin D V , Smirnov M B
Published: December 2019

AlN/GaN superlattices (SL) grown by metalorganic vapor-phase epitaxy with the period of SLs varied from 20 nm to 140 nm, and the thickness of the structures ranged from 0.7 to 1 µm were studied by polarized Raman spectroscopy technique. The peaks within a complex spectral feature of the symmetry A1(TO) observed at about 580 cm−1, were assigned to the interface and quasi-confined phonons. Frequency splitting between the peaks was found monotonously increasing along with the SL period. This dependence was explained using the dielectric continuum model. A method based on this finding was proposed for estimating the period SL using Raman spectroscopy. This method extends the traditional approach based on the studies of folded acoustic phonons in the short-period SLs.
Phonons in short-period (GaN)m(AlN)n superlattices: ab initio calculations and group-theoretical analysis of modes and their genesis
Authors: Davydov V Yu , Roginskii E M , Kitaev Yu E , Smirnov A N , Eliseyev I A , Nechaev D V , Jmerik V N , Zavarin E E , Lundin W V
Published: December 2019

The results of experimental and theoretical studies of phonon modes in short-period (GaN)
m
(AlN)
n
superlattices (SLs) grown by MOVPE and PA MBE on the (0001) Al2O3 substrate are reported. Using a comprehensive group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals has been established, which is important for interpreting the SL Raman spectrum. In the framework of Density Functional Theory, the lattice dynamics and the structural properties of (GaN)
m
(AlN)
n
SLs (m+n⩽12) were studied. An analysis of the eigenvectors of the phonon modes made it possible to reveal their microscopic nature. We established that the E(TO) modes are localized in the layers constituting the SL. It is shown that the localized nature of this mode is kept even in the SLs with the thinnest layers (m+n=4). In turn, the A
1(TO) mode demonstrates a delocalized nature and reflects the averaged characteristics of the SL as a whole. A combined analysis of the ab initio calculations and Raman data was performed. Thus, the above studies open new possibilities for analyzing the structural properties of GaN/AlN SLs by Raman and IR spectroscopy.
Dielectric metamaterials with quasicrystal structure
Authors: Maslova E E , Rybin M V
Published: December 2019

Three types of quasicrystal lattices based on the Penrose tiling are considered. We analyze the maximum filling fraction of these structures and find a design with the filling fraction corresponding to the case of periodic lattices. By using simulations of a Gaussian beam propagation through the quasicrystal structure we obtain a homogeneous field distribution that is a hallmark of near-zero regimes in metamaterials.
Optical confocal spectroscopy of SiC and AlN interfaces using Raman scattering and Optically Detected Magnetic Resonance
Authors: Breev I D , Anisimov A N , Baranov P G , Mokhov E N
Published: December 2019

The thesis contains the investigation of transition layer between AlN and SiC and the investigation of AlN Raman peaks evolution with distance till interface. Moreover, ODMR spatial research of nonuniformly irradiated 4H-SiC was performed together with PL spatial spectroscopy.
Analysis of the mineral component for cortical bone tissue by Raman spectroscopy after ovariectomy and its treatment with allogeneic hydroxyapatite
Authors: Timchenko E , Timchenko P , Pisareva E , Vlasov M , Volova L , Fedorova I , Tumchenkova A , Gorchenkova M , Subatovich A
Published: December 2019

In the work results of experimental researches of mineral component of cortical tissue after ovariectomy and estimation of correction using allogeneic hydroxyapatite (HAP) by the method of Raman spectroscopy are presented. A comparative analysis of bone samples from non-ovariectomized and ovariectomized animals after HAP injection was carried out using the Raman spectra. Coefficients which allow to estimate resorption of cortical tissue after ovariectomy and correction using HAP was entered. Introduction of HAP suspension showed that the consequences of ovariectomy can be almost compensated for the cortical tissue.
Holographic formation of photon structures by Bessel-like and Gaussian light fields in photopolymer materials taking into account two-beam interaction and small contrasts
Authors: Dolgirev V O , Sharangovich S N , Semkin A O , Dudnik D I
Published: December 2019

This paper presents a theoretical model of the holographic formation of photon structures (PS) in a photopolymer material (PPM) by Bessel-like and Gaussian light beams, taking into account the self-diffraction of recording light beams in areas of low contrast of the interference pattern. It was demonstrated by numerical simulation and experiment that the influence of the self-diffraction effect leads to an increase in the level of the side maxima of the diffracted light beam.
Selective volumetric modification of transparent dielectric media by femtosecond laser radiation
Authors: Chernikov A S , Chkalov R V , Kochuev D A , Khorkov K S , Prokoshev V G , Davydov N N
Published: December 2019

The paper describes the possibility of modifying transparent solid media by ultrashort laser pulses of femtosecond duration. The mechanism of fabricating second- and third-order fiber Bragg gratings in a standard single-mode Corning SMF-28e+ fiber is considered. Examples of multilayer ordered structures formation in a bulk of the glass samples are show.
Roughness measurement with nanoscale resolution by symmetric array of optical vortices
Authors: Sokolenko B V , Poletaev D A , Shostka N V , Karakchieva O S , Ismailov I A , Fitaev I , Shevchenko A I , Kudrian N V , Halilov S I
Published: December 2019

In present report we review the principles and applications of interference vortex method for the real time determination of polished optical surface roughness for transparent and reflecting materials with using of symmetric Laguerre-Gaussian array as a probe beams and reference beams with low topological charge. High spatial resolution caused by interference of vortices and their phase sensitivity, which is automatically analyzable to retrieve the 2D and 3D shape of micro- and nanostructured surfaces is applicable for non-destructive roughness testing of thin films and solid microstructures. The longitudinal and transverse resolution down to 1.75 nm and 7 nm respectively for visible light sources is achieved by the proposed method. The dependence of the rotational angle of the resulting interference pattern in form of two-petal laser beams on the optical path difference and sample thickness for two singular beams superposition is considered in detail.
Merging resonant frequencies and changing the sign of the g-factors of different atoms with frequent spin exchange
Authors: Okunevich A I , Dovator N A
Published: December 2019

The paper discusses the high-temperature spin-exchange of a mixture of vapors of alkali metals. It is shown that in a small magnetic field, an increase in temperature can lead to a sharp decrease in the frequency of transverse relaxation and to a significant decrease in the frequency of oscillation of the angular moments of atomic sublevels. Such changes in relaxation and frequency are well known in the case of a vapor of a single alkali metal. New in the case of a mixture was the merging of the resonance frequencies of different atoms into one frequency, which is the frequency of rotation of the total angular momentum of the atoms of the mixture. It also turned out that with an increase in temperature, the sign of the g-factors of atoms changes.
Impact of refractive index profile of nanostructured ITO films on light extraction efficiency
Authors: Pavluchenko A.S. , Markov L.K. , Smirnova I.P. , Levitsky V.S.
Published: December 2019

In this paper, we study composite nanostructured ITO films with different refractive index profiles, obtained by e-beam evaporation and magnetron sputtering, which can be used as a transparent conducting contacts in a wide variety of optoelectronic devices, e.g. AlInGaN light-emitting diodes. The composite ITO films that comprise of an underlying dense layer and a structured layer deposited on a glass substrate surface have been fabricated. Reflectance and transmittance spectra were measured. Numerical calculations have been utilized to obtain refractive index profiles of the studied films. Light extraction efficiencies of the studied films have been calculated.
Dispersion properties of uniform trapezoidal optical waveguides
Authors: Cheplagin N.A. , Zaretskaya G.A.
Published: December 2019

A method for calculation of the propagation constant of guided modes in the optical waveguides with trapezoidal cross-sections is proposed. The method enables to calculate a propagation constant correction factor that arises due to perturbations of the cross-section of a reference rectangular waveguide. The correction factor is analytically calculated within the framework of the coupled-mode theory. A refined form of the coupling coefficient is obtained owing to the application of a concept of effective excitation sources and accurate account of boundary conditions. An impact of the waveguide cross-section shape on its dispersion properties is analysed. The necessity to take into account the proposed form of the coupling coefficient is demonstrated by comparison of the simulation results with other methods of dispersion calculation.
Digital holographic testing of the optical fiber at welding area
Authors: Prisiazhniuk A V , Sokolenko B V , Poletaev D A , Shostka N V
Published: December 2019

A method to analyse of optical fibers inhomogeneity in welding junction using digital holography is proposed. The method utilizes lens-less Gabor scheme for recording of a digital hologram with numerical reconstruction by angular spectrum approach. Qualitative image analysis applied on the intensity distribution of specimen after hologram reconstruction enables to evaluate the structural defects inside the fiber core and cladding after welding procedure, which are not observable with conventional microscopy. The opportunities of presented method were approved with a wavelength-division multiplexing fibers of known defects introduced by axial misalignment of welded parts. A compact in-line digital holographic recording set-up for express and robust optical fiber analysis was developed through its application to a welding quality testing. It is shown how the value of axial misalignment of welding fibers lead to a variation of artificial intensity distribution around the joint in reconstructed image.
Three-wavelength optoelectronic system for hemodialysis monitoring
Authors: Konoplev G A , Stepanova O S , Frorip A , Gerasimchuk R P
Published: December 2019

Novel spectrophotometric method and optoelectronic spectral equipment for automatic on-line monitoring of hemodialysis treatment are introduced. The method allows determination of the concentrations of uric acid and creatinine in effluent dialysate by measuring ultraviolet (UV) absorption at three wavelengths. An optoelectronic spectral sensor with three deep ultraviolet light emitting diodes (LED), a flow-through quartz cuvette connected to the outlet of a dialysis machine, and a solar-blind UV photodetector was designed. Dedicated software for sensor control, spectral data acquisition, and spectral analysis was developed. The results of preliminary clinical trials of the developed system are presented.
Optical materials for lens concentrators of solar radiation
Authors: Shvarts M Z , Emelyanov V M , Nakhimovich M V , Soluyanov A A
Published: December 2019

“Solar” Abbe number is proposed to operate in assessing the suitability of optical materials at sunlight concentrators manufacture. Comparative results are presented for materials practically used in concentrator photovoltaics from the point of view of designing Fresnel lenses from them with a high average concentration in the focal spot of the minimum size and at the same time with minimum focal length.
Current Distribution in GaAs Solar Cell with Carbon Nanotube Transport Layer
Authors: Mitin D M , Raudik S A , Mozharov A M , Bolshakov A D , Fedorov V V , Nepokh V V , Mikhailovskii V Y , Rajanna P M , Nasibulin A G , Mukhin I S
Published: December 2019

Numerical simulation and EBIC measurements of GaAs-based solar cells with metal grid and CNT transport layer were performed. Influence of CNT transport layer properties on lateral current distribution was analyzed. In accordance with electron beam induced current measurements it was shown that CNT demonstrates perfect transport properties leading to good charge carrier’s collection.
Triboelectric current generation in InP
Authors: Sharov V A , Alekseev P A , Dunaevskiy M S , Reznik R R , Cirlin G E
Published: December 2019

Energy harvesting is an area that presents the greatest potential for powering wireless low-energy electronics. Development of semiconductor-based energy harvesting is of interest. Herein we focus on studying two different energy harvesting mechanisms in indium phosphide. Piezoelectric harvesting was checked by bending vertical InP nanowires with conductive atomic force microscope (AFM) probe and simultaneously detecting current passing through the probe. No current pulses were observed that we associate with surface trapping of piezoinduced carriers. Triboelectric generation was studied by creating frictional contact between AFM tip and metal-dielectric-semiconductor (MIS) interface formed by InP layer covered with native oxide. Current peaks of 320 pA amplitude corresponding to the current density around 2.3 kA/m2 were observed under sliding reciprocating motion of the tip during AFM scanning. Achieved current density was higher than in polymer- and silicon-based triboelectric structures. The open-circuit voltage value exceeded 15 mV and the output electric power was 35 W/m2.
Studies of the thermovoltaic effect in semiconductors in the medium temperature range
Authors: Kaminskii V V , Soloviev S M , Sudak N M , Zaldastanishvili M I , Sharenkova N V , Kazanin M M
Published: December 2019

The possibilities of increasing the voltage generated due to the thermovoltaic effect in semiconductors by increasing the generation temperature are considered. It is shown on the example of SmS that an increase in voltage can be achieved by increasing the depth of impurity donor levels in semiconductors. The magnitude of the generated voltage is 0.15V in SmS/Sm0.7Eu0.3S as against 0.05 V in undoped SmS. The possibility of obtaining generation due to the thermovoltaic effect is also considered on a classical PbTe semiconductor operating in a higher-temperature region compared to SmS. Generation value of 0.11V was obtained.
On modelling optical parameters of InAs quantum dots for cascade GaInP / GaAs / Ge solar cells
Authors: Panchak A N , Mintairov S A , Mintairov M A , Salii R A , Shvarts M Z , Kalyuzhnyy N A
Published: December 2019

Triple-junction solar cells InGaP/GaAs/Ge usually are manufactured using MOCVD technology. However, the potential of such structures is investigated in the laboratory on samples made using MBE. One of the ways to increase efficiency is the implanting of InAs quantum dots in GaAs cascade. In this paper the approaches to the mathematical modeling of Ga (In) As structures grown by MOCVD and MBE are studied.
Laser-induced magnetization precession in the magnetite Fe3O4 in the vicinity of a spin-reorientation transition
Authors: Karpovsky I O , Kazenwadel D L , Shelukhin L A , Balbashov A M , Pisarev R V , Kalashnikova A M
Published: December 2019

Using time-resolved magneto-optical pump-probe technique we demonstrate excitation of magnetization precession in a single crystalline bulk magnetite Fe3O4 below and in the vicinity of the Verwey and spin-reorientation (SR) phase transitions. Pronounced temperature dependence of the precession amplitude is observed suggesting that the excitation occurs via laser-driven spin-reorientation transition. Similarity observed between the characteristic features of the laser-induced ultrafast SR and Verwey transitions suggests that they both rely on the same microscopic processes.
Conductive AFM study of the local current in thin ferroelectric sol-gel PZT films
Authors: Gushchina E V , Zaitseva N V , Delimova L A , Seregin D S , Vorotilov K A
Published: December 2019

The local current distribution across the grains and their boundaries in ferroelectric PZT films are studied using conductive AFM. The films were formed with various grain structures and different lead excess content by chemical solution deposition. C-AFM measurements have shown the influence of the lead excess and seed sublayer crystallization conditions on the grain-boundary conductivity. PZT films with fixed 0-15 wt% Pb excess demonstrate non-conductive grain boundaries, whereas in films with fixed 30 wt% Pb excess the grain-boundary conductivity is found to be much higher than that of the grains themselves. Conductive grain-boundaries was also found in PZT films without lead excess in crystallized sublayer. A study of the transient current at varied preliminary polarization revealed the current peaks in the current-voltage curves. The appearance conditions and magnitude of these peaks depend on the grain-boundary conductivity. The correlation between the grain-boundary conduction and the current polarization dependences is confirmed.
Electrocaloric effect and dielectric properties in ferroelectric ceramics based on solid solution of barium-calcium titanate
Authors: Anokhin A S , Es’kov A V , Pakhomov O V , Semenov A A , Lähderanta E
Published: December 2019

Barium titanate based ceramics is the most common class of lead-free ceramics due to its high values of dielectric constant, polarization, piezo- and electrocaloric effects. In this paper dielectric properties and electrocaloric effect in ceramics based on solid solution of barium-calcium titanate had been studied. It was shown, that increasing of calcium titanate in solid solution leads to increasing of dielectric constant and electrocaloric effect, simultaneouslyit leads to decreasing of leakage currents. While increasing fraction of calcium titanate from 0% to 10%, dielectric constant at frequency of 1 kHz rises from 10500 to 13600, maximum adiabatic electrocaloric response at ΔE = 1.3 V/μm rises from 0.5 K to 0.7 K.
Carrier mobility in the channel of AlGaN/(AlN)/GaN and InAlN/(AlN)/GaN heterostructures, limited by different scattering mechanisms: experiment and calculation
Authors: Arteev D S , Sakharov A V , Lundin W V , Zakheim D A , Zavarin E E , Tsatsulnikov A F
Published: December 2019

Calculational analysis of different scattering mechanisms of two-dimensional electron gas in AlGaN/(AlN)/GaN and InAlN/(AlN)/GaN high-electron mobility transistors was carried out. It was found that the mobility of AlGaN-based structures at room temperature is mainly limited by inherent scattering mechanisms (namely, optical and acoustic phonon scattering), while the mobility in our InAlN-based structures is limited by the interface roughness scattering. The low-temperature mobility is found to be limited by the interface roughness scattering for both AlGaN- and InAlN-based structures.
The effect of transverse rectification of electromagnetic waves in a two-dimensional superlattice
Authors: Konchenkov V I , Myachkova A A , Zav’yalov D V
Published: December 2019

Using the constant-collision frequency approximation, an analytical expression was obtained for the direct current density occurring in a two-dimensional superlattice when two waves with mutually perpendicular polarization planes are exposed to the sample, the frequency ratio of which is 2.
Effect of coherent population trapping in a compact microfabricated Cs gas cell pumped by intra-cavity contacted VCSELs with rhomboidal oxide current aperture
Authors: Bobrov M A , Blokhin S A , Maleev N A , Blokhin A A , Vasyl’Ev A P , Kuzmenkov A G , Gladyshev A G , Novikov I I , Petrenko M V , Ospennikov A M , Ermak S V , Ustinov V M
Published: December 2019

Miniature laser source based on intracavity-contacted vertical-cavity surface-emitting laser with rhomboidal oxide current aperture was investigated for coherent population trapping (CPT) resonance excitation in microfabricated 133Cs gas cell filled with Ne buffer gas under the pressure of 300 torr. The cell operation temperature was 90°C. The laser output power was 550 μW at bias current of 3.2 mA and 65°C. The short-term stability of ∼2.5·10-11 at the measurement time of 1 sec was estimated from CPT resonance signal measurements.
New 50-keV neutral beam injector for the Globus-M2 spherical tokamak
Authors: Telnova A Yu , Minaev V B , Shchegolev P B , Bakharev N N , Shikhovtsev I V , Varfolomeev V I
Published: December 2019

A design of the new neutral beam injector and the process of generation of a high-energy atomic beam are described in detail. The injector is fully prepared for experiments on auxiliary heating of the Globus-M2 tokamak plasma. The docking of injector with tokamak vacuum vessel is completed. The predictions for non-inductive current drive by 50 keV 1 MW neutral beam in the Globus-M2 are presented.