bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the origin of the interfacial superconductivity of Sb
2
Te
3
/Fe
1+y
Te heterostructures
Authors: Liang Jing , Zhang Yu Jun , Yao Xiong , Li Hui , Li Zi-Xiang , Wang Jiannong , Chen Yuanzhen , Sou Iam Keong
Published: December 2019

The recent discovery of the interfacial superconductivity (SC) of the Bi
2
Te
3
/Fe
1+y
Te heterostructure has attracted extensive studies due to its potential as a novel platform for trapping and controlling Majorana fermions. Here we present studies of another topological insulator (TI)/Fe
1+y
Te heterostructure, Sb
2
Te
3
/Fe
1+y
Te, which also has an interfacial 2-dimensional SC. The results of transport measurements support that reduction of the excess Fe concentration of the Fe
1+y
Te layer not only increases the fluctuation of its antiferromagnetic (AFM) order but also enhances the quality of the SC of this heterostructure system. On the other hand, the interfacial SC of this heterostructure was found to have a wider-ranging TI-layer thickness dependence than that of the Bi
2
Te
3
/Fe
1+y
Te heterostructure, which is believed to be attributed to the much higher bulk conductivity of Sb
2
Te
3
that enhances indirect coupling between its top and bottom topological surface states (TSSs). Our results provide evidence of the interplay among the AFM order, itinerant carries from the TSSs, and the induced interfacial SC of the TI/Fe
1+y
Te heterostructure system.
Approaches to genetically engineering flowering control in trees.
Authors: Meilan R. , Kirst M.
Published: December 2019

This chapter discusses approaches to flowering control in genetically engineered trees. The chapter covers the following topics: transgene confinement, engineering flowering control, excision systems, targeted mutagenesis and gene replacement, and prospects for flowering control.
Engineering tolerance to abiotic stresses.
Authors: Meilan R. , Kirst M.
Published: December 2019

Recent developments in high-throughput sequencing, genomics, transcriptomics, metabolomics, and proteomics in several forest tree species are providing tools and resources that will expedite the improvement of abiotic stress tolerance in trees. This chapter provides selected examples of how these advances can be utilized to introduce or enhance abiotic stress tolerance in trees.
Integrating perceptions of the school neighbourhood environment with constructs from the theory of planned behaviour when predicting transport‐related cycling among Chinese college students
Authors: Zhang Ru , Zhang Chun‐Qing , Wan Kang , Hou Yan‐Si , Rhodes Ryan E.
Published: December 2019

Aim: Using a longitudinal design, the purpose of this study was to test a model integrating perceptions of the school neighbourhood environment with constructs from the Theory of Planned Behaviour (TPB) to predict transport‐related cycling among Chinese college students.

Methods: A sample of 630 (M age = 18.95 years; SD = 1.16) Chinese college students completed baseline measures that included perceptions of the school neighbourhood environment, TPB constructs, transport‐related cycling, and covariates. Of those, 547 students (M age = 18.90 years; SD = 0.92) also completed measures of transport‐related cycling one month later.

Results: Findings showed that intention had a direct effect on students’ transport‐related cycling, while attitudes, subjective norm, and perceived behavioural control predicted cycling indirectly via intention. Perceptions of the school neighbourhood environment did not provide an indirect effect on cycling via the TPB constructs, although some perceived environmental factors had indirect effects on intention via attitudes and subjective norm. Further, those who perceived better street connectivity showed a larger intention‐cycling relationship than those who perceived less street connectivity.

Conclusions: Findings of this study highlight the importance of integrating perceptions of the school neighbourhood environment with the TPB constructs to explain transport‐related cycling through both intention formation and action control (i.e. translating intention into behaviour). The identified moderator of perceived street connectivity on the intention‐cycling relationship suggests that efficient cycling routes may impact action control of cycling. Future research applying dual process and action control models beyond TPB may contribute to the identification of the multilevel determinants of transport‐related cycling.
High value resistance comparison (SIM.EM-S15)
Authors: Castro Blanca I , Jarrett Dean G , Payagala Shamith U
Published: December 2019

This is a report of the results of an Interamerican Metrology System (SIM) comparison on high resistance values, performed to compare the measurement capabilities of National Institute of Standards and Technology (NIST) and (Instituto Costarrricense de Electricidad - Laboratorio Metrológico de Variables Eléctricas) ICE-LMVE and for establishing the degree of equivalence between those laboratories.

During 2018, two resistance standards were used as traveling standards for measurements in those countries, with NIST-USA acting as the pilot laboratory. Results for four measurement points are presented as errors relative to a comparison reference value together with their uncertainty.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
BIPM comparison BIPM.RI(II)-K1.Fe-59 of activity measurements of the radionuclide 59Fe for the PTB (Germany), LNE-LNHB (France) and the NMIJ (Japan), and the linked APMP.RI(II)-K2.Fe-59 comparison
Authors: Michotte C , Ratel G , Courte S , Kossert K , Nähle O , Dersch R , Branger T , Bobin C , Yunoki A , Sato Y
Published: December 2019

Three new participations in the BIPM.RI(II)-K1.Fe-59 comparison have been added to the previous results and this has produced a revised value for the key comparison reference value (KCRV), calculated using the power-moderated weighted mean. A link has been made to the APMP.RI(II)-K2.Fe-59 comparison held in 2014 through the NMIJ who participated in both comparisons. Five NMIs used the K1 or K2 comparison to update their degree of equivalence. The degrees of equivalence between each equivalent activity measured in the International Reference System (SIR) and the KCRV have been calculated and the results are given in the form of a table for the remaining five NMIs in the BIPM.RI(II)-K1.Fe-59 comparison and the eight other participants in the APMP.RI(II)-K2.Fe-59 comparison. A graphical presentation is also given.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Final report, on-going key comparison BIPM.QM-K1, ozone at ambient level, comparison with KRISS, April 2019
Authors: Viallon Joële , Idrees Faraz , Moussay Philippe , Wielgosz Robert , Lee Jae Yong , Lee Sangil
Published: December 2019

As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of Korea maintained by the Korea Research Institute of Standards and Science (KRISS) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount-of-substance fraction range from 0 nmol/mol to 500 nmol/mol.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Legendre decomposition for tensors*
Authors: Sugiyama Mahito , Nakahara Hiroyuki , Tsuda Koji
Published: December 2019

We present a novel nonnegative tensor decomposition method, called Legendre decomposition, which factorizes an input tensor into a multiplicative combination of parameters. Thanks to the well-developed theory of information geometry, the reconstructed tensor is unique and always minimizes the KL divergence from an input tensor. We empirically show that Legendre decomposition can more accurately reconstruct tensors than other nonnegative tensor decomposition methods.
Equation of state and properties of fcc gold in macro and nano-sized state
Authors: Akhmedov E N
Published: December 2019

An approach to studying the state equation and the thermodynamic properties of both a macrocrystal and a nanocrystal from a unified standpoint is proposed. The calculation of th state equation for gold showed good agreement with the experimental data. Graphs of pressure dependences were obtained for the following properties: bulk modulus, thermal expansion coefficient, isochoric and isobaric heat capacities, surface energy. An isobaric (at P = 0) size dependence of the distance between the centers of the nearest atoms and the melting temperature of a gold nanocrystal is obtained. It was shown that the size dependence of the melting temperature in the case of the isobaric conditions increases with the change in the nanocrystal size more rapidly compared with the isochoric conditions.
Localized bending and longitudinal waves in rods interacting with external nonlinear elastic medium
Authors: Erofeev V I , Leonteva A V
Published: December 2019

This paper is concerned with the study of the propagation of bending and longitudinal waves in homogeneous rods interacting with a nonlinear elastic medium. The dynamic behaviour of the rods is determined by refined theories as follows: for a rod fixed on a nonlinear elastic foundation and executing bending vibrations we select the Tymoshenko model while for a rod immersed in a nonlinear elastic medium and performing longitudinal vibrations we choose the Mindlin-Hermann model. It is demonstrated that evolutionary equations are generalizations of the well-known Ostrovsky equation: the modified Ostrovsky equation with a cubic non-linear term and the Ostrovsky equation with an additional quadratic non-linear term. Both generalized equations have exact soliton solutions of the stationary wave class.
Tungsten and molybdenum nano-oxides as promising substrates for analytical method of giant Raman scattering
Authors: Borodina T I , Valyano G E , Karpukhin V T , Malikov M M
Published: December 2019

The article discusses the results of the experimental research into composition and crystal structures of tungsten and molybdenum nano-oxides. We prove that the starting material of nanostructures is amorphous, with particle sizes being less than 1-2 nm. These structures are able to serve as an effective substrate for the analytical method based on the surface enhanced Raman scattering (SERS).
Evaluating Stability Conditions for a Rotating Droplet in a Potential Flow
Authors: Sergeev M N , Evdokimov O A
Published: December 2019

The paper considers issues related to droplet fragmentation in air flow. We present the results of calculating the equilibrium conditions for a rotating droplet. The shape of the droplet is assumed to be ellipsoidal, and the flow is potential. The droplet equilibrium is determined by the balance of pressure due to the surface tension force, the centrifugal force and the aerodynamic effect force of the flow. We obtained an analytic expression linking the equilibrium values of the Weber number, the ellipsoid aspect ratio and the dimensionless swirl parameter. The calculation results showed that droplet swirling has a significant effect on the equilibrium conditions in a narrow range of variation in the ellipsoid aspect ratio. We obtained critical values of the Weber number and the aspect ratios for which the equilibrium state of the droplet becomes unstable.
Solution of loose medium movement problem on a curvilinear sifting surface
Authors: Kharitonov A , Busigina A , Maslennikov I
Published: December 2019

The paper presents the results of movement simulation of loose medium stratum on a curvilinear sifting surface using the program realizing a finite element method. The indicial equations represent an analogue describing fluid stratum movement under the theory of “shallow water”. The allocation of a part movement speed rate in the cross-section of a stratum is obtained. The presence of a braking underlayer on a sifting surface lowering efficiency of sifting process is detected.
Advanced methods and algorithms for rapid diagnosis of the organism
Authors: Berezhanskiy P V , Turchaninov S O
Published: December 2019

This paper deals with the methods of rapid biomedical diagnosis based on visualization of pathological states of the epithelium and microcirculatory bed, analysis of the exhaled air composition and algorithms which improve the accuracy of diagnosis with the definition of the boundaries of the medical norm for quantitative parameters.
Specifics of studying electrochlorination in a student chemistry practical
Authors: Kuznetsov N N , Bogoslovskii S Yu , Boldyrev V S
Published: December 2019

The suitability of the process of obtaining sodium hypochlorite by electrolytic chlorination of sodium chloride solution for the purposes in a chemical laboratory is shown. The process was carried out in a 1 l non-flowing cell with four bipolar titanium electrodes 6x10 cm with oxide-ruthenium anodes. The distance between the electrodes is 1 mm, the temperature of the initial solution is 7-8ºC. The concentration of sodium chloride 25 g/l is convenient for acquaintance with the basic electrochemical laws of the process since the dependence of the concentration of “active chlorine” on the electrolysis time is linear up to 9 g/l at a current density of 0.1 A / cm2. The study of the effect of side processes on the output of the target product is carried out at a current density of 0.125 and 0.15 A/cm2 (the dependence is nonlinear). The dependence at a concentration of 35 g/l, 0.1 A/cm2 is similar to the dependence at 25 g/l and 0.125 A/cm2. To determine the concentration of “active chlorine” the aliquot was taken from the reaction mixture at equal intervals, diluted by 25 times. The solution was acidified and titrated with methyl orange.
Numerical analysis of meniscus liner rigidity loss during its dynamic collapse
Authors: Baburin M A , Baskakov V D , Yeliseev S V , Karnaukhov K A , Tarasov V A , Zarubina O V
Published: December 2019

This paper describes a method of 3D computational modeling of the rigidity loss process in meniscus liners of variable thickness in circumferential direction using finite elements analysis for Lagrangian coordinates in the program complex LS-DYNA. Numerical calculations established the main consistent patterns in the process of rigidity loss in liners and the wrinkling process in the afterbody of the explosively formed projectiles formed during the dynamic collapse. Formation of a folded afterbody in explosively formed projectiles has been confirmed experimentally. The carried out research is of great interest to specialists in the field of physics of explosions and shock and impact, as well as to those involved in the analysis of rigidity loss in various constructions.
On some peculiarity in behavior of plasma with an arbitrary degree of degeneracy of electron gas in thin layer
Authors: Gordeeva N M , Yushkanov A A
Published: December 2019

In this study we considered the response of electron plasma with an arbitrary degree of degeneration to an alternating electromagnetic field. The electromagnetic field directed perpendicularly to the boundary of the plasma layer. We present an analytic solution of the boundary problem. The kinetic Boltzmann-Vlasov equation with the Bhatnagar–Gross–Krook collision integral and the Maxwell equation for the electric field are used. We consider the mirror boundary conditions for the reflections of electrons from the layer boundary. The boundary problem may be reduced to a one-dimensional problem with a single velocity. Separation of variables allow reducing the problem equations to a characteristic system of equations. The eigensolutions of the initial system, which correspond to the continuous spectrum, are Van Kampen mode. The eigensolutions corresponding to the adjoint and discrete spectra are Drude and Debye modes. We can construct the general solution. The Debye mode determines the plasma screening of the electric field. The behavior of this mode was analyzed. It depends on the parameters of the problem. In case of sufficiently high degrees of the electron gas degeneracy, the range of the Debye mode existence has a substantially nontrivial character, in which the ranges of existence and absence of this mode alternate with increasing electric field frequency.
Two-photon luminescence in POPOP and stilbene
Authors: Kupov M R , Gorelik V S , Sverbil P P , Lepnev L S
Published: December 2019

In this work, main results of spectral and energy dependences of two-photon luminescence in polycrystalline organic compounds are reported. The two-photon luminescence was excited by a repetitively pulsed laser on a yttrium aluminum garnet (YAG). This laser generated radiation at wavelengths of 266 and 532 nm. Two-photon luminescence and Raman scattering have been registered in a single measurement. We compared efficiency of two-photon luminescence and Raman scattering efficiency.
Raman scattering in diamond microcrystals and their composites
Authors: Romanovskaya A K , Gorelik V S , Bi Dongxue , Voinov Yu P
Published: December 2019

In this paper, the features of the Raman spectra in diamond microcrystals were investigated. The Raman spectra in microdiamonds were characterized by high intensity due to the effects of trapped radiation and total internal reflection. A characteristic line with a frequency of 1332 cm–1 and additional bands located in the overtone region of fundamental modes was registered in the observed spectra. Raman spectra in diamond-substances composites (diamond: K2Cr2O7, NaBrO3, NaNO2, HgI2, K2CrO4, PbO, KIO3, sulfur, iodine, stilbene, triglyceride sulfate, and POPOP) were detected.
Multi-frequency stimulated raman scattering in protium and deuterium water
Authors: Savelyeva A I , Gorelik V S , Voinov Yu P , Vodchits A I , Orlovich V A
Published: December 2019

Multi-frequency stimulated Raman scattering spectra were recorded with excitation of infrared (λ0=1064 nm) emission of picosecond solid state laser. The registration of spectra was with the fiber-optic technique by minispectrometer at wide frequency region.
Multifrequency parametric processes in dielectric media
Authors: Skrabatun A V , Gorelik V S , Pyatyshev A Yu , Vodchits A I , Orlovich V A , Apanasevich P A
Published: December 2019

Multiple Stokes and anti-Stokes satellites were observed in the spectra of stimulated parametric Raman scattering of light in liquids and crystals when excited by picosecond laser pulses of a YAG: Nd3+ solid-state laser with generation wavelengths of 1064 and 532 nm. The Stokes combination satellites of the infrared range were detected as a result of their conversion into the visible spectral region. The results obtained are of interest for the development of the theory of parametric processes of stimulated Raman scattering of light in crystals and liquids, which is also important for creating efficient laser sources from the ultraviolet to the far infrared.
The formula for the resistance force during slow motion of a sphere in an ideal gas
Authors: Semikolenov A V
Published: December 2019

In this article the formula for the resistance force during slow motion of a sphere in an ideal equilibrium gas is discussed, taking into account the velocity distribution of molecules. Using the density function of the velocity distribution of molecules hitting the surface of the body during a certain period of time, an expression for the resistance force is obtained. The resulting expression is compared with the well-known expression in the Stokes law.
X-ray free electron lasers in the course of physics of Technical University
Authors: Smirnov E V
Published: December 2019

The article provides an overview of the X-ray sources based on synchrotron radiation sources of the generation of the four – X-ray free electron lasers (XFEL). The multipolar system of magnetic fields – undulator – allowing receiving high intensity beams of X-rays is considered. Important properties of the radiation emitted by XFEL are noted: ultra-high brightness, ultra short pulses, the high spatial coherence of the beam. There is an urgent need to include this material in the course of general physics and in the courses of X-ray optics for Russian Technical Universities.
Dynamic crushing of spacecraft landing gear with crash legs
Authors: Scheglov G A , Lukovkin R O
Published: December 2019

The paper describes spacecraft landing on a landing gear consisting of four crash legs supported by beam struts. The first part is dedicated to verification of low dimension shell finite element model parameters in the MSC Nastran SOL700 software. An elastoplastic crushing test problem of square aluminum specimens with various thickness is simulated. The comparison of simulation results with experimental data shows that the proposed mathematical model provides the error of less than 10% for the specimens with a width-to-thickness ratio C/s > 30. The second part of the paper discusses landing gear legs crushing during vertical landing on a rigid soil. An analysis of the results showed that it is possible to reduce the crash legs mass by 35 % and the landing gear will provide safe landing conditions with a limited level of peak loads acting on the spacecraft. The characteristic features of the crash leg dynamic deformation process open possibilities for further reduction the landing gear weight and design optimization. The paper opens up a new avenue in design of high energy absorption lightweight gear components for the spacecraft landing process.
Kramers-Kronig relations in spectral analysis of diffuse reflected radiation
Authors: Anfimov D R , Golyak Ig S , Tabalina A S , Fufurin I L
Published: December 2019

In this paper studied application of Kamers-Kronig relations in spectral analysis of diffuse reflected IR radiation. Two methods of the Kramers-Kronig relations calculation were considered: Maclaurin’s Formula (MF method) and Method of Peterson-Knight (PK method). Influence of using MF and PK methods on synthetic and real experimental spectra were studied. Accuracy and calculating time of these methods were compared. According to the results of numerical experiments, conclusions about the perspectives and application possibilities of the considered methods were discussed.
Features of the formation of an electric field in a non-uniform conducting medium
Authors: Timchenko S L , Zadorozhnyy N A
Published: December 2019

The paper considers the influence of the electric field of the current on the behaviour of a gas bubble in an electrically conductive melt. We propose a model which makes it possible to predict a change in the size of gas bubbles in a metal, provided that its crystallization occurs in the presence of an electric current. The model takes into account the interaction of the charge induced on the surface of the gas bubble — metal-gas interface — with the electric field of the current. The force that deforms the gas bubble is introduced. The magnitude of the force is determined by the charges induced on the surface of the bubble due to the action of the electric field of the current. The surface density of the charges is proportional to the square of the current density and depends on the geometry of the object that is affected, as well as on the material parameters of the medium, such as electrical resistivity and magnetic permeability. Additional forces of electrical nature acting on the surface of the gas bubble contribute to its deformation in the electric field of the current. In the presence of such forces, the interfaces between the media — liquid metal and gaseous — can be deformed. Under the conditions of an orderly motion of free electrons and their collisions with ions of the crystal lattice, the size of the interfaces between the media can be changed. The gas bubble under the action of additional forces is deformed and can subsequently be fragmented.
Dimers of triangular Ag nanoprisms: computer simulation of optical properties
Authors: Lobanova E M , Bochenkov V E , Shabatina T I
Published: December 2019

In this paper the properties of a nanostructure comprised of a pair of distorted triangular Ag nanoparticles are studied using computer simulation. It is shown that upon excitation of localized surface plasmon resonance the electromagnetic field enhancement can reach the value | E | / | E0 | = 48.
Peculiarities of mathematical modeling of combustion of hydrogen-air mixtures
Authors: Kiverin A D , Melnikova K S , Minaev K O , Smygalina A E , Yakovenko I S
Published: December 2019

Paper presents a comprehensive study of contemporary opportunities in the numerical analysis of transient combustion regimes on the example of the topical problem of hydrogen combustion. The elementary processes determining the development of combustion under different conditions are considered. In view of this analysis, it is concluded that the most appropriate for numerical modeling of classic deflagration inside confined space is the low-dissipation numerical schemes of low (second) order of approximation. For near-critical conditions where distinct mechanisms determine the combustion development one is able to utilize the simplifications such as low Mach number approximation.
Simulation of viscoelastic flow past circular airfoil by using the modified LS-STAG immersed boundary method
Authors: Puzikova Valeria V
Published: December 2019

The LS-STAG immersed boundary cut-cell method modification for viscoelastic flow computations is presented. Rate type viscoelastic flow models (linear and quasilinear) are considered. Rate type viscoelastic flow models (linear and quasilinear) are considered. The obtained numerical method is implemented in the LS-STAG software package developed by the author. This software allows to simulate viscous incompressible flows by using the LS-STAG method and it modifications. The LS-STAG-discretization of extra-stress equations for viscoelastic Maxwell, Jeffreys, upper-convected Maxwell, Maxwell-A, Oldroyd-B, Oldroyd-A, Johnson Segalman fluids was developed. Formulae for differential types of convected time derivatives (Oldroyd, Cotter — Rivlin, Jaumann — Zaremba — Noll derivatives) the LS-STAG discretization was obtained. Normal non-newtonian stresses are computed at the centers of base LS-STAG mesh cells and shear non-newtonian stresses are computed at the cell corners. Time-stepping algorithm is based on the first order predictor-corrector scheme. To validate developed numerical method the test problem about viscoelastic Oldroyd-B flow past a circular airfoil was used. Computational experiments were carried out at Weissenberg number in the range from 0 to 4. The computed values of the drag coefficients and the wake length are in good agreement with the experimental data.
Spatial localization of thermal structures
Authors: Martinson L K , Pozdyshev M L , Andreev A G
Published: December 2019

The Cauchy problem for the integro-differential equation of nonlinear heat conduction, which describes the evolution of a finite temperature field in a medium in the presence of volumetric heat absorption, is discussed in the paper. A feature of such one-dimensional and three-dimensional processes is the spatial localization of heat, when thermal perturbations evolve in a finite spartial domain.
Comparison of combusting pellets of agro and wood biomass in different fluidized bed conditions
Authors: Kaczyński K , Kaczyńska K , Pełka P
Published: December 2019

The rise in pellet consumption has resulted in a wider variety of materials for pellet manufacture. Thus, pellet industry has started looking for alternative products in relation to wood biomass, such as wastes from agricultural activities, and related industries, along with the combination thereof, obtaining a broad range of these products. The results of the experiment showed significant differences between the analyzed biomass fuels burned under different operating conditions in a laboratory reactor with a model circulating bed. These differences are mainly associated with problematic phenomena during combustion, including sintering of ashes.
Experimental and numerical analysis of multi-disc heat exchanger efficiency in adsorption chillers powered with waste heat
Authors: Sosnowski M
Published: December 2019

The thermally-powered adsorption cooling systems capable to utilize industrial waste heat sources and environmentally friendly refrigerants are an effective way to decrease electricity demand due to cooling. The design of the heat exchanger combined with the sorption bed is crucial to enhance the heat transfer within the bed and in consequence, significantly contributes to the adsorption chiller efficiency. Therefore, the aim of the carried out research was to investigate the possibility of implementing the innovative multi-disc heat exchanger in an adsorption cooling technology. The logarithmic mean temperature difference, as well as temperature distribution within the investigated heat exchanger, were obtained with experimental and numerical research.
Microlasers based on GaAs and Si
Authors: Zhukov A E , Maximov M V , Kryzhanovskaya N V
Published: December 2019

Results are presented on microlasers with quantum dot active region grown on either GaAs or Si substrates. The optical resonator of these lasers represents a microdisk supporting whispering-gallery modes with a Q-factor in excess of 30’000. When operating in continuous-wave mode without temperature stabilization, the microlasers have the threshold currents of mA-range with the minimal threshold current density of 250 A/cm2. Under direct small-signal modulation, the -3dB modulation bandwidths were measured to be above 6 GHz with a little effect of self-heating on the performance. The consumed electric power was estimated to be about 2 pJ/bit. The achieved performance is a significant breakthrough in realization of low-threshold high-speed temperatrure-stable operation of microlasers compared with the previously reported parameters for the devices of comparable sizes.
Anomalous lasing in VCSEL with double oxide current apertures
Authors: Bobrov M A , Blokhin S A , Maleev N A , Kuzmenkov A G , Ustinov V M
Published: December 2019

Detail measurements and full-vector three-dimensional FDTD technique were used to analyze anomalous mode behavior in double-aperture oxide-confined 850 nm VCSELs with large gain-to-cavity detuning.
Reactor materials for high purity HVPE GaN growth: a thermodynamic analysis
Authors: Voronenkov Vladislav , Bochkareva Natalia , Zubrilov Andrey , Leonidov Andrey , Shreter Yuri
Published: December 2019

The chemical resistance of quartz, aluminum oxide, boron nitride, molybdenum, and platinum in the environment of the hydride vapor phase epitaxy of gallium nitride was estimated by chemical equilibrium calculation. The interaction of materials with hydrogen, hydrogen chloride, chlorine, ammonia, and gallium chlorides was analyzed. The conditions in which the use of each material is permissible were determined.
Selective area epitaxy of n+-GaN layers on SiO2 patterned GaN/c-Al2O3 templates by PA MBE
Authors: Shubina K Yu , Mizerov A M , Timoshnev S N , Mokhov D V , Nikitina E V , Kim I , Bouravleuv A D
Published: December 2019

The n+-GaN epilayers were synthesised by PA MBE on the SiO2 patterned GaN/c-Al2O3 templates, grown by MOCVD. Formation of the polycrystalline GaN atop of the SiO2 mask during PA MBE was observed. It was found that macroscopic voids at the interface polycrystalline GaN/SiO2/n-GaN template appeared during the PA MBE process. The polycrystalline GaN film was completely removed by etching in hot aqueous KOH solution. Hall measurements have shown that the value of electron concentration in n+-GaN contact layer is about ne∼4.6×1019 cm-3.
Structure of V-defects in a-GaN films grown on r-sapphire substrate
Authors: Savchuk A , Akhmerov Yu , Chelny A , Abdullaev O , Rabinovich O , Mezhenny M , Zharkova A , Aluyev A , Zakusov M , Kourova N , Murashev V , Didenko S
Published: December 2019

The a-GaN films were successfully grown on the r-sapphire substrate by MOCVD method. The structure of V-defects was investigated by AFM and SEM. The dependence of V-defects density on growth temperature of a-GaN film at a constant hydrogen flow through a TEG source was studied. The influence of V/III ratio on V-defects structure was investigated. Methods of V-defects density minimisation were purposed.
The two-stage electrochemical deposition of a manganese-doped silicon-carbon film onto the silicon (100) substrate
Authors: Mikhailova T S , Grigoryev M N , Myasoedova T N
Published: December 2019

Manganese-doped silicon-carbon films with a thickness about 100 nm were deposited on a silicon substrate by using the electrochemical route from the methanol, hexamethyldisilazane and manganese sulfate (CH3OH, (CH3)3-Si-NH-Si-(CH3)3 (HMDSN), MnSO4·5H2O) solution. At the first stage, the current density decreased from 51 mA/cm2 to less than 37 mA/cm2 with increasing the deposition time and slightly increased at the second stage when manganese sulfate was added. The analysis derived from the X-ray diffraction pattern indicates that Mn atoms interact with Si atoms and form mainly Mn5Si2 and Mn22,6Si5,4C4 phases.
In situ study of structural transformation of the (TeO)x(Mo,V,Nb)5O14 mixed oxide nanocatalyst with a tunnel structure
Authors: Derevyannikova E. , Kardash T , Marchuk A , Simanenko A. , Svintsitsikiy D. , Lazareva E.
Published: December 2019

The nano oxides (TeO)x(Mo,V,Nb)5O14 with so-called M1 structure are highly attractive objects due to unsurpassed catalytic properties. In situ X-ray powder diffraction method with high time resolution (0.4 seconds per diffraction pattern) was applied to study the structure stability and the mechanism of phase transformation under heating in the reductive conditions. It was shown that M1 structure gradually transforms into the rutile-type (Mo,V,Nb)O2 phase without intermediate phases and/or amorphisation at temperatures >480°C in a reductive media. The process is initiated by tellurium reduction and its sublimation to the gas phase.
Crystal lattice tilt analysis in gradient composition layers by electron and X-ray diffraction
Authors: Snigirev L A , Kirilenko D A , Pirogov E.V. , Baidakova M V , Bert N A
Published: December 2019

The combination of X-ray tilt-azimuth figure, reciprocal space map and transmission electron microscopy in selected area electron diffraction mode was applied to analyse the tilt of the MBE-grown 1.2-μm thick convex-graded InxAl1-xAs (x=0.05-0.80) metamorphic buffer layer on singular GaAs (001) substrate. The combination of the techniques is demonstrated to enable the determination of the tilt angle as well as the tilt direction together with monitoring of the tilt development along the growth direction. For the studied metamorphic buffer layer as an example, the tilt direction was deduced to be 20° off the (110) GaAs substrate crystallographic plane. The tilt angle of (002) buffer layer planes was observed to rapidly rise to 0.6° near the layer-substrate interface and then to slowly increase to 1.4° with the approach toward the surface.
Formation peculiarities of silver dendritic structures for photocatalysts of the visible radiation range
Authors: Sigaev A P , Averin I A , Pronin I A , Karmanov A A , Yakushova N D , Moshnikov V A
Published: December 2019

The techniques for synthesis of silver structures in the form of a polyhedral array, as well as in the form of self-similar objects, spatially organized by the type of dendrites, are presented. The mechanisms that potentially determine the formation peculiarities of such structures are considered. Prospects of using this type of structures alongside with wide band gap semiconductor oxides, as highly efficient photocatalysts of the visible radiation range, are demonstrated.
Critical pressure during the formation of carbon nanotubes by the method of plasma chemical vapor deposition
Authors: Klimin V S , Rezvan A A , Morozova J V
Published: December 2019

The critical pressure of acetylene required for the formation of nanotubes on nickel catalytic centers of a given size was calculated by plasma chemical vapor deposition. It has been established that for a stable growth of carbon nanotubes on a catalytic center with a diameter of 20 nm, the critical pressure of acetylene should be 1.9 Pa, while the growth time of carbon nanotubes in length of 5 μm is 131 sec. Nickel was used as a material for the formation of catalytic centers. In the calculations, the averaged parameters of carbon nanotubes were used. This analysis allowed to form a number of criteria for the materials of the underlayer and catalytic centers, to obtain an array of carbon nanotubes with a high degree of verticality.
Application of the atomic layer etching technique for the formation of SiC-based field emitters
Authors: Klimin V S , Kots I N , Tominov R V , Rezvan A A , Varzarev Y N , Ageev O A
Published: December 2019

This paper presents the technology of obtaining graphene films on the surface of SiC using a combination of methods of focused ion beams and plasma-chemical etching in a fluorine containing environment. For the formation of nanoscale structures with lateral dimensions of 280 nm, the method of focused ion beams was used. Nano sized structures were formed on the surface of silicon carbide by an ion beam, which were subsequently placed in the reactor. In the reactor, the structures on silicon carbide were processed in fluoride plasma. The depth of the structures was 900 nm. SF6 was used for atomic layer etching operations. The study of the surface topology at each iteration was carried out using scanning electron microscopy. Electrical characteristics were measured by atomic force microscopy.
Combined scanning probe nanolithography and liquid etching techniques for profiled nanostructures formation
Authors: Polyakova V V , Kots I N , Avilov V I , Parshina N V , Smirnov V A
Published: December 2019

The results of studies of the effect of technological modes of nanoscale silicon substrate surface profiling by local anodic oxidation (LAO). The effect of relative humidity and the amplitude of the voltage applied to the tip-substrate system with LAO on the geometric parameters of the oxide nanostructures (ONS) and profiled nanostructures (PNS). It has been shown that increasing the voltage amplitude to the probe substrate 10 to the system 20 causes an increase in the height of the ONS 0.6 ± 0.2 to 2.0 ± 0.3 nm at 70% relative humidity. Investigations of the possibility of using ONS as a mask during the silicon etching liquid. It has been shown that increasing the silicon etching time from 10 to 80 seconds in the KOH + IPA causes increased silicon PNS height of 100 ± 10 nm and 350 ± 30 nm. The results can be used in the development of technological processes of manufacturing of nanoelectronics components based on silicon base using the probe nanotechnologies.
InGaN nanostructures of a branched morphology on silicon substrate: MBE synthesis and properties
Authors: Reznik R R , Kotlyar K P , Khrebtov A I , Kryzhanovskaya N V , Cirlin G E
Published: December 2019

A possibility of InGaN nanostructures of a branched morphology MBE growth on Si substrate has been demonstrated. The results of morphological studies have shown that InGaN synthesis occurs in several stages. InGaN nanostructures turned out to be optically active at room temperature and have a wide radiation visible range.
ZnO thin films synthesis by RF magnetron sputtering deposition
Authors: Gridchin V.O. , Kotlyar K.P. , Vershinin A.V. , Kryzhanovskaya N.V. , Pirogov E.V. , Semenov A.A. , Belyavskiy P.Y. , Nashchekin A.V. , Cirlin G.E. , Soshnikov I.P.
Published: December 2019

Investigation of ZnO thin films synthesis using RF magnetron sputtering deposition in the Ar/O2 plasma gas mixture at different O2 composition and at different growth temperatures is presented. The effect growth process on structural (morphology and orientation films, grain sizes, lattice parameters) and optical (transmittance, absorption, refractive index, photoluminescence) properties are examined. It is shown that synthesized ZnO thin films at a temperature from 200 to 300 °C are polycrystal and textured. Notice that ZnO thin films, which are synthesized using pure Ar plasma gas, are porosity. The optical transmittance and absorption spectra have an absorption edge near 380 nm. The PL spectra of synthesized ZnO films show exciton peaks at 370-400 nm and the wide emission at the yellow and red spectral regions.
Modeling the formation of InP/GaxIn1-xP axial nanowire heterostructures
Authors: Koryakin A A , Leshchenko E D , Dubrovskii V G
Published: December 2019

A model is developed to depict the formation of InP/GaxIn1-xP axial heterostructures in self-catalyzed GaxIn1-xP nanowires. The composition profiles of the InP/GaxIn1-xP axial heterostructure are calculated taking into account elastic stresses. It is shown that the InP/GaxIn1-xP axial heterojunction width at the growth temperature of 450°C is larger than 12 monolayers for nanowires with the radius larger than 10 nm. Also, the comparison with GaxIn1-xAs system is performed and reveals that the InP/GaxIn1-xP axial heterojunction width is approximately two times smaller than the InAs/GaxIn1-xAs axial heterojunction width.
Role of the wetting layer in the crystallization stage during droplet epitaxy of InAs/GaAs nanostructures
Authors: Balakirev S V , Eremenko M M , Chernenko N E , Ageev O A , Solodovnik M S
Published: December 2019

In this paper, we present the results of experimental study of the role of the wetting layer in the crystallization stage of droplet nanostructures in the lattice-mismatched InAs/GaAs material system. We demonstrate that the thickness of the wetting layer can significantly affect the characteristics of nanostructures formed during crystallization in the arsenic flux. While the surface density of InAs nanostructures does not increase relatively to the initial droplet density obtained at 300 °C, a significant increase of the nanostructure density is observed after crystallization of droplets obtained at 200 °C. This behaviour is attributed to the additional stress-driven Stranski-Krastanov quantum dot formation and confirmed by the 2D-3D transformation of indium layer obtained at 100 °C.
Nondestructive 3D-evaluation of human dentin by microtomography using synchrotron radiation
Authors: Gudkina Z V , Argunova T S , Gutkin M Yu
Published: December 2019

Results of Synchrotron Radiation (SR) microtomography of human dentin specimens subjected to compression tests are presented. A special attention is paid to cracks formed in the samples under compression. In all the samples, the dominant crack paths were observed to deviate and deflect around certain areas at or near to dentinal tubules. It is confirmed that secondary (satellite) cracks play an important role in dominant crack blunting. It is shown that microtomography is an effective method for investigation of the formation of satellite cracks and crack-tubule interactions over surface areas and across the whole depth of a dentin specimen. These processes can be visualized and evaluated using reconstructed 2D slices. A qualitative model for the formation of secondary cracks opening at stress concentrators that are dentinal tubules is suggested. It is shown that on the surface of the tubules, which are the closest to the tip of a mode II crack, the tensile circumferential stress can reach extremely high values that are more than enough for generation of secondary cracks.
Highly hydrophilic and stable polylactic acid surface achieved by argon plasma treatment
Authors: Romashkin A V , Polikarpov Yu A , Struchkov N S , Silakov G O , Petukhov V A , Levin D D , Nevolin V K
Published: December 2019

The effect of modifying additives such as low molecular weight polylactide (PLA) and benzyl alcohol (BA) on the degree of hydrophilicity of high molecular weight PLA before and after plasma treatment with low density and specific power per area was investigated. The lowest water contact angle (WCA) after modification was about 17°. A comparative evaluation of the formed functional groups amount, the hydrophilicity and stability of the plasma modification was carried out. WCA measurements of ageing of modified samples over time up to one year was carried out. It was found that plasma treated PLA films, obtained from tetrahydrofuran solution of high-molecular weight PLA and BA, demonstrated one of the highest ageing stability at high hydrophilicity. At the same time, the increase of the oxygen-containing functional groups amount on the modified PLA surface (about 40%, estimated by XPS) is close to the critical value in point of view of ensuring both high hydrophilicity and stability of the PLA surface after the modification.
Test object as a subject of biometric studies of eye reaction
Authors: Bikberdina N , Bobrova D , Boronenko M
Published: December 2019

Interest in detecting the psychophysical state of a person according to various biometric data (KGR, pupillography and profiling, etc.) is becoming more widespread every year. The most statistically reliable and resistant to counterfeiting systems are the identification of a person by the iris and face. Biometric identification systems can be combined. This paper presents proposals for improving the existing systems of recognition of the psychophysical state of a person.
Measurement and analysis of the recombination coefficients distribution on the area of light-emitting InGaN/GaN heterostructures
Authors: Frolov I V , Radaev O A , Sergeev V A
Published: December 2019

A method and an installation for evaluation the profile of distribution of recombination coefficients and current density over the area of light-emitting heterostructures at low injection levels based on local values of the 3 dB frequency are described. Using the example of measuring the parameters of commercial blue InGaN/GaN-based LEDs, it is shown that the current density is higher in those areas of the chip where the 3 dB frequency is lower.
Simulation of current-voltage characteristics and power-voltage characteristics of «space» solar cells based porous silicon in the Comsol Multiphysics package
Authors: Shishkin I A , Lizunkova D A , Latukhina N V
Published: December 2019

To analyze the characteristics of solar modules based on porous silicon involved in the flight experiment aboard a small spacecraft AIST 2D, the method of computer simulation of solar cell characteristics was used. The paper presents the procedure for developing a simulation model of photovoltaic modules in Comsol Multyphysics. The developed model allows us to investigate the current-voltage and voltage-watt characteristics of solar modules and determine the main parameters. The discrepancy between the experimental data obtained from the telemetry data from the AIST-2D with the simulation results does not exceed 5%.