bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility of home-based HIV counselling and testing and linking to HIV services among women delivering at home in Geita, Tanzania: A household longitudinal survey
Authors: Adinan Juma , Adamou Bridgit , Amour Caroline , Shayo Aisa , Kidayi Paulo Lino , Msuya Levina
Published: July 2019

Background

Substantial number of women who deliver at home (WDH) are not captured in prevention of mother-to-child transmission (PMTCT) services. This delays HIV infection detection that negatively impacts endeavours to fight the HIV pandemic and the health of mothers and children. The study objective was to determine the feasibility of home-based HIV testing and linking to care for HIV services among WDH in Geita District Council, Tanzania.

Methods

A longitudinal household survey was conducted. The study involved all mentally-able women who delivered within two years (WDTY) preceding the survey and their children under the age of two. The study was conducted in Geita District Council in Geita Region, Tanzania from June to July 2017. Geita is among the region with high HIV prevalence and proportion of women delivering at home.

Results

Of the 993 women who participated in the study, 981 (98.8%) accepted household-based HIV counselling and testing (HBHCT) from the research team. HIV prevalence was 5.3% (52 women). HBHCT identified 26 (2.7%) new HIV infections; 23 (23.4%) were those tested negative at ANC and the remaining three (0.3%) were those who had no HIV test during the ANC visit. Among the 51 HIV+ women, 21 (40.4%) were enrolled in PMTCT services. Of the 32 HIV+ participants who delivered at home, eight (25.8%) were enrolled in the PMTCT compared to 100 percent (13/13) of the women who delivered at a health facility.

Conclusion

HBHCT uptake was high. HBHCT detected new HIV infection among WDH as well as seroconversion among women with previously negative HIV tests. The study findings emphasize the importance of extending re-testing to women who breastfeed. HBHCT can be used to improve PMTCT services among WDH.
Biomechanical comparison of stand-alone and bilateral pedicle screws fixation for oblique lumbar inter-body fusion surgery – a finite element analysis
Authors: Fang guofang , lin yunzhi , cui wenggang , guo lili , Zhang shihao , Sang Hongxun
Published: July 2019

Objectives: The aim of this study was to evaluate the biomechanical stability and safety in patients undergoing oblique lumbar inter-body fusion (OLIF) surgery with stand-alone (SA) and Bilateral pedicle screw fixation (BPSF).
Methods: A finite element model of L4-L5 spinal unit was established and validated. Based on the validated model technique, function surgical models corresponding to SA, BPSF were created. Simulations employing the models were performed to investigate the OLIF surgery. A bending moment of 7.5 Nm and a 500 N follower load were applied to the models in flexion, extension, axial rotation and lateral bending. Finite element(FE) models were developed to compare the biomechanics of the intact group, SA, BPSF group.
Results: Compared with the Range of motion (ROM) of the intact lumbar model, SA model decreased by 79.5% in flexion, 54.2% in extension, BPSF model decreased by 86.4% in flexion, 70.8% in extension. Compared with the BPSF, the maximum stresses of L4 inferior endplate (IEP) and L5 superior endplate (SEP) increased significantly in SA model, L4 IEP increased to 49.7MPa in extension, L5 SEP increased to 47.7MPa in flexion.
Conclusions: OLIF surgery with BPSF could reduce the max stresses of the endplate which may reduce cage sedimentation incidence. However, OLIF surgery with SA could not provide enough rigidity for the fusion segment in osteoporosis patients which may increase the cage sedimentation incidence.
Keywords: OLIF; Pedicle screw fixation; spinal fusion; finite element
Electronic Medical Record System Use in Canada: Integrating Physiology Flowsheets
Authors: Chowdhury Farah , Stenson Steven , Hait Nona , Graham Tim , Hayward Robert , Kalluri Meena , Wong Eric , Vethanayagam Dilini
Published: July 2019

Background: Longitudinal data of pulmonary physiology (pulmonary function tests, PFTs) is important in diagnosis and management of both respiratory and non-respiratory diseases that have secondary effects on lungs. Large amounts of data need to be amalgamated in physiology flowsheets within electronic medical records (EMR), which summarize trends of multiple PFT reports in one document. We present the process around evaluation and implementation of a physiology flowsheet with discreet data elements.

Methods: Alberta Health Services (AHS) has chosen a single vendor for its EMR, an Epic-based system (Epic Systems Corporation). A new clinical tool was written and implemented/piloted within the pulmonary department of the EMR. The physiology flowsheet was tested, modified, and real patient data was entered for those followed longitudinally within AHS Pulmonary Function Laboratories. A pre- and post-implementation survey was carried out with different front-line users to evaluate their experiences.

Results: From this pilot implementation, we found that majority of EMR users reported variable ease and satisfaction with the current access to PFT’s. Flowsheets were deemed helpful, once longitudinal data was available. Consistently respondents reported that the EMR slows patient encounters. Healthcare providers also reported flowsheets to be useful for patient education and their self-reflection related to disease processes. Patient surveys were not conducted.

Conclusions: Current data transfer of PFT results to EMR requires manual entry, which is time-consuming, though clinically useful. The incorporation of raw data from PFT software to EMR is of great importance in both clinical assessments and patient education; however, a systems-based approach is needed.
Supplementing Coursebooks--How, Why, and to What Effect: A Case Study
Authors: Harper John
Published: July 2019

This article reports on a case study of one instructor’s use of supplementary materials in an English as a Foreign Language course in China. Starting with the notion that no coursebook can be perfect and that supplementary materials therefore should form part of an English course, the study employed qualitative research methods to analyze the types of supplements used, the instructor’s rationale behind his use of the supplements, and the students’ interpretations of the supplements. Class observations, semi-structured interviews with the teacher, and focus-group discussions with students allowed for the triangulation of data. Findings indicated that the instructor provided a variety of types of supplementary materials in order to cater to different learner needs (specifically, affective needs, language-learning needs, course-content needs). While findings also indicated that learners generally appreciated the instructor’s use of supplementary materials, significant mismatches between instructor goals and learner interpretations suggested that the purpose of the supplements was not always clearly defined. The article addresses these mismatches and provides suggestions for their future avoidance.
The Existence of Kurds in Caucasia
Authors: BİÇER Bekir
Published: July 2019

The Kurdish people make up a nation that originated in the Middle East. It is largely accepted that the  Kurds’ mother country is in an area of Upper Mesopotamia to the southwest of Iran, meaning around the Zagros Mountains. In  truth,, many aspects of Kurdish history are still not entirely understood. For instance, subjects such as their initial emergence, how their ethnic structure formed, their relationships with the Persians, and the origin of the Kurdish language still remain unclear. One of the mysteries surrounding the Kurdish nation is the existence of Kurds in Caucasia. This paper attempts to find answers to the following questions: Is Caucasia the mother country of Kurds? When, from where, and how did Kurdish people come to Caucasia? In what area did the Kurds initially settle? Did they found a state and a military in Caucasia?
Reliability and efficiency of an advanced tertiary treatment process for wastewater reclamation
Authors: Xu Hongbin , de Koning Jaap , Geng Ying
Published: July 2019

A reliability study for the reclamation of wastewater treatment plant effluent using continuous sand filtration-multimedia filtration (CSF-MMF) combined with ultrafiltration (UF) and reverse osmosis (RO) has been conducted. The objectives of the research are two-fold: (1) effluent of CSF-MMF can be used for surface water supplementation and (2) permeate of UF-RO can be applied as greenhouse irrigation water. The removal efficiencies for nutrients and electric conductivity (EC) as well as some operational parameters of the pilot plant were investigated. The concentration of T-N, chemical oxygen demand (COD) and turbidity in the filtrate of CSF-MMF with external C-course methanol dosage and FeCl3 dosage could be kept at less than 2.2 mg/L, 35 mg/L and 0.9 NTU respectively. Average EC exceeded the required surface water standard by 10% and it was difficult to meet the low surface water standard for T-P (below 0.15 mg/L). The EC of RO permeate was below 20 μS/cm, which was much lower than the standard for greenhouse irrigation. With frequent back flushes, cleaning in place (CIP) and enhanced cleaning the UF could be operated with a constant permeability of 100 L/(m2·h·bar). An appropriate CIP resulted in a recovery of 47–52% of the RO. The protective cartridge filter prior to the RO should be replaced every 2 weeks.
Developing hydrological and reservoir models under deep uncertainty of climate change: robustness of water supply reservoir
Authors: Marton Daniel , Knoppová Kateřina
Published: July 2019

Adaptation of water resources to climate change, drought management strategies, and hydrological and reservoir modelling have become serious issues in the context of climate change uncertainty. The aim of this paper is to introduce methods and tools for hydrological analysis and robust reservoir performance evaluation in this time of deep uncertainty. Newly developed lumped water balance and reservoir simulation models will be used to perform hydrological analysis, and a robust reservoir storage capacity reliability assessment will also be conducted. The hydrological data in relation to climate change will be constructed using two climatological datasets created by statistical downscaling tools LARS WG and ENSEMBLE Downscaling Portal. The hydrological analysis and the temporal reliability of the assessment of reservoir storage capacity and robustness in the context of climate change uncertainty will be presented as a case study of the Vir I reservoir and the Svratka River basin in the Czech Republic, in central Europe. The resulting models show a decrease in long-term mean flow, ranging from 6% to 32%, and in reservoir outflow from 1.5% to 26%, depending on the timescale, downscaling tools and emission scenarios.
Влияние зарядового состояния ионов ксенона на профиль распределения по глубине при имплантации в кремний
Authors: Балакшин Ю.В. , Кожемяко А.В. , Petrovic S. , Erich M. , Шемухин А.А. , Черныш В.С.
Published: July 2019

AbstractExperimental depth distributions of the concentration of implanted xenon ions depending on their charge state and irradiation energy are presented. Xenon ions in charge states q = 1–20 and energies in the range from 50 to 400 keV are incorporated into single-crystal silicon. Irradiation is performed in the direction not coinciding with the crystallographic axes of the crystal to avoid the channeling effect. The ion fluence varies in the range of 5 × (10^14–10^15) ion/cm^2. The irradiation by singly charged ions and investigation of the samples by Rutherford backscattering spectroscopy is performed using an HVEE acceleration complex at Moscow State University. Multiply charged ions are implanted using a FAMA acceleration complex at the Vinća Institute of Nuclear Sciences. The depth distribution profiles of the incorporated ions are found using Rutherford backscattering spectroscopy. Experimental results are correlated with computer calculations. It is shown that the average projective path of multiply charged ions in most cases is shorter when compared with the average projected path of singly charged ions and the results of computer modeling.
Спин-орбитальное взаимодействие и подвижность носителей заряда в продольном автосолитоне в антимониде индия в магнитном поле
Authors: Камилов И.К. , Степуренко А.А. , Гумметов А.Э.
Published: July 2019

AbstractA version of the spin–orbit interaction of orbitally moving and spin-oriented electrons in a longitudinal autosoliton in indium antimonide under a longitudinal magnetic field is proposed and considered. The additional energy gained by spin–orbit electrons due to this interaction is determined. Expressions for the change in the mobility during the orbital motion of electrons under a magnetic field and the additive mobility of spin-oriented electrons are derived and calculated. The coefficients of the mutual influence of changing electron mobility in the case of orbital motion and the additive mobility of spin-oriented electrons are calculated.
Влияние рентгеновского излучения на оптические свойства фоторефрактивных кристаллов силиката висмута
Authors: Аванесян В.Т. , Писковатскова И.В. , Стожаров В.М.
Published: July 2019

AbstractThe results of investigations of the optical-absorption spectra of bismuth-silicate (Bi_12SiO_20) single crystals are presented. The band-gap width and the characteristic Urbach energy are determined. The effect of preliminary X -ray irradiation on the behavior of the experimental spectral dependences and the values of the characteristic parameters induced by the bismuth-silicate defect structure is established.
Некоторые физические свойства нового интерметаллида NbCd-=SUB=-2-=/SUB=-
Authors: Володин В.Н. , Тулеушев Ю.Ж. , Жаканбаев Е.А. , Мигунова А.А. , Ниценко А.В.
Published: July 2019

AbstractSolid solutions of cadmium in niobium and NbCd_2 phase are formed by magnetron sputtering and coprecipitation on substrates moving relative to the flow of Nb and Cd particles. The NbCd_2 phase can be described by a tetragonal unit cell with the parameters a = 0.84357 nm, c = 0.54514 nm, and c / a = 0.6426. A very high hole concentration in NbCd_2 is established by studying the coating absorption and transmission spectra corresponding to the intermetallic-compound composition near the fundamental absorption edge, determining the band gap, and measuring the carrier mobility. Such a concentration is characteristic of a strongly degenerate semiconductor or metal. The band gap is determined to be 1.26 eV. The variation in the concentration of carriers and their mobility depending on the cadmium concentration in coatings of the Nb–Cd system confirms the occurrence of the NbCd_2 phase.
Наноструктурированные покрытия ITO/SiO-=SUB=-2-=/SUB=-
Authors: Марков Л.К. , Павлюченко А.С. , Смирнова И.П.
Published: July 2019

AbstractThe influence of a SiO_2 layer deposited onto nanostructured transparent conductive films of indium and tin oxide (ITO) on their optical characteristics is investigated. For this purpose, SiO_2 films of various thicknesses are deposited by magnetron sputtering on samples with ITO films containing whiskers of preferentially vertical orientation and possessing steadily decreasing reflectance. It is shown that this makes it possible to attain noticeable coating antireflection under the condition of the uniform overgrowth of ITO whiskers by the SiO_2 layer. The influence of the SiO_2 layer on the optical characteristics of a dense unstructured ITO film is also investigated. The results for structured and unstructured ITO/SiO_2 coatings with identical material mass contents are compared. It is noted that due to the liability of ITO material to degradation during operation in the composition of transparent conductive contacts, the results can also be interesting for the formation of coatings more resistant to the effect of the environment.
Темплатный синтез монодисперсных сферических нанопористых частиц кремния субмикронного размера
Authors: Курдюков Д.А. , Феоктистов Н.А. , Кириленко Д.А. , Смирнов А.Н. , Давыдов В.Ю. , Голубев В.Г.
Published: July 2019

AbstractMonodisperse spherical nanoporous silicon ( np -Si) particles of submicrometer size are fabricated with mesoporous silica particles as a template. Silicon is synthesized within the mesopores of monodisperse silica particles by the thermal decomposition of monosilane. Then, the template material ( a -SiO_2) is removed by wet etching. The particles obtained have a small root-mean-square size scatter (no more than 10%) and large specific surface area (250 m^2 g^–1) and pore volume (0.5 cm^3 g^–1). It is shown that np -Si particles exhibit photoluminescence in the visible and near-IR (infrared) spectral ranges.
Исследование вольт-амперных характеристик новых гетероструктур MnO-=SUB=-2-=/SUB=-/GaAs(100) и V-=SUB=-2-=/SUB=-O-=SUB=-5-=/SUB=-/GaAs(100), прошедших термическую обработку
Authors: Сладкопевцев Б.В. , Котов Г.И. , Арсентьев И.Н. , Шашкин И.С. , Миттова И.Я. , Томина Е.В. , Самсонов А.А. , Костенко П.В.
Published: July 2019

AbstractComplex oxide films with a thickness of about 200 nm are formed during the thermal oxidation of GaAs with magnetron-deposited V_2O_5 and MnO_2 nanolayers. The electrical parameters of the films (reverse-bias breakdown voltage and current density) are determined by the method of current–voltage ( I – V ) characteristics at room temperature in the bias range from –5 to +5 V, and their composition and surface morphology are investigated. It is shown that V_2O_5 facilitates the more intense (in comparison with MnO_2) chemical bonding of arsenic at the internal interface with the formation of As_2O_5. As a result, thermally oxidized V_2O_5/GaAs heterostructures exhibit higher breakdown voltages.
Зависимость интенсивности спонтанной люминесценции наностержней ZnO от их длины
Authors: Грузинцев А.Н. , Редькин А.Н. , Якимов Е.Е.
Published: July 2019

AbstractThe influence of the length of ZnO nanorods (500 nm in diameter) on the mode structure and spontaneous luminescence in the ultraviolet spectral region is studied by optical luminescence microscopy. It is shown that individual nanorods with a metal mirror on one face exhibit only two or three laser modes in the case of short nanocavity lengths (8–30 μm). Different values of the optical losses of the longitudinal and transverse waveguide modes are established for a ZnO nanorod lying on a glassy substrate. The quadratic dependence of the spontaneous luminescence intensity on the rod length can be attributed to improvement of the optical quality factor Q of bound longitudinal modes of light within longer rods (the Purcell effect).
Энергетические затраты при формировании упругонапряженного состояния в слоях ступенчатого метаморфного буфера в гетероструктуре, выращенной на подложке (001) GaAs
Authors: Алешин А.Н. , Бугаев А.С. , Рубан О.А. , Сарайкин В.В. , Табачкова Н.Ю. , Щетинин И.В.
Published: July 2019

AbstractOn the basis of data on X -ray structural analysis performed by the method of reciprocal-space mapping and investigations using secondary-ion mass spectrometry and transmission electron microscopy, it is shown that vertical compressive stresses also arise in a multilayer epitaxial heterostructure comprised of a step-graded metamorphic buffer along with lateral compressive stresses. The cause of the appearance of vertical stresses is the effect of interlayer hardening, which arises due to the deceleration of fragments of glide dislocations by interphase boundaries. Analysis performed within the framework of the linear theory of elasticity shows that the elastically stressed state of the buffer steps is similar to the state that can be achieved as a result of a two-stage deformation process: bulk and biaxial compression. Bulk compression leads to large energy expenditures in the formation of the structure of the buffer steps, which is reflected, in particular, in violation of the coherence between the dislocation-free and the underlying layers.
Исследование влияния термического отжига на фотоэлектрические свойства гетероструктур GaP/Si, полученных методом атомно-слоевого плазмохимического осаждения
Authors: Уваров А.В. , Зеленцов К.С. , Гудовских А.С.
Published: July 2019

AbstractThe effect of thermal annealing on the photovoltaic properties of a GaP/Si heterostructures obtained by plasma-enhanced atomic layer deposition under different conditions is examined. It is shown that in the structures containing amorphous GaP, annealing at 550°C leads to a sharp decrease in the quantum efficiency and open-circuit voltage, while in the structures with microcrystalline GaP on an epitaxial sublayer, the photovoltaic characteristics are improved. Annealing at a temperature of 750°C improves the photovoltaic characteristics in all the structures due to the diffusion of phosphorus atoms from GaP to Si and leads to the formation of a layer with n -type conductivity in the substrate. As the annealing temperature is increased to 900°C, the carrier lifetime in the silicon substrate decreases. It is shown that the atomic-layer-deposition technique is promising for the formation of a GaP nucleation layer on the surface of silicon before subsequent epitaxial growth.
Оценка вклада поверхностной рекомбинации в микродисковых лазерах с помощью высокочастотной модуляции
Authors: Жуков А.Е. , Моисеев Э.И. , Крыжановская Н.В. , Блохин С.А. , Кулагина М.М. , Гусева Ю.А. , Минтаиров С.А. , Калюжный Н.А. , Можаров А.М. , Зубов Ф.И. , Максимов М.В.
Published: July 2019

AbstractMicrodisk lasers 10–30 μm in diameter operating at room temperature without thermal stabilization and with an active region based on nanostructures of hybrid dimensionality—quantum wells–dots—are investigated. High-frequency measurements of the microlaser response are performed in the direct small-signal modulation mode, which makes it possible to establish the parameters of the operating speed and analyze their dependence on the microlaser diameter. It is found that the K factor is (0.8 ± 0.2) ns, which corresponds to optical losses of ~6 cm^–1, and no regular dependence on the diameter is observed. It is found that the low-frequency component of the damping coefficient of relaxation oscillations is inversely proportional to the diameter. This character of the dependence evidences a decrease in the carrier lifetime in small-diameter microcavities, which can be associated with the prevalence of nonradiative recombination on their side walls.
Влияние потерь на вывод излучения на динамические характеристики вертикально-излучающих лазеров спектрального диапазона 1.55 мкм, изготовленных методом спекания эпитаксиальных пластин
Authors: Блохин С.А. , Бобров М.А. , Блохин А.А. , Кузьменков А.Г. , Малеев Н.А. , Устинов В.М. , Колодезный Е.С. , Рочас С.С. , Бабичев А.В. , Новиков И.И. , Гладышев А.Г. , Карачинский Л.Я. , Денисов Д.В. , Воропаев К.O. , Ионов А.С. , Егоров А.Ю.
Published: July 2019

AbstractThe results of studying the dynamic characteristics of 1.55-μm single-mode vertical-cavity surface-emitting lasers (VCSELs) formed by the fusion of wafers of high-quality Bragg reflectors and an active region based on thin highly strained InGaAs/InAlGaAs quantum wells are presented. It is found that the proposed design of the active region and optical microcavity of the laser make it possible in principle to attain a high level of differential laser gain in the temperature range of 20°C–85°C, but weak electron localization leads to an increase in gain compression at elevated temperatures. Due to this fact, the VCSEL modulation bandwidth at 20°C can be increased from 9.2 to 11.5 GHz due to an increase in output optical losses, while the modulation bandwidth at 85°C does not exceed 8.5 GHz, depends weakly on the output optical losses, and is mainly limited by the optical-gain saturation.
Модуль фотоэлектрических преобразователей лазерного излучения (λ=1064 нм)
Authors: Хвостиков В.П. , Калюжный Н.А. , Минтаиров С.А. , Потапович Н.С. , Сорокина С.В. , Шварц М.З.
Published: July 2019

AbstractThe results of a study and the development of a module designed for energy transmission via atmospheric channels are presented. The four-cell module based on single-junction metamorphic InGaAs/GaAs converters grown by metal-organic vapor-phase epitaxy has an open-circuit voltage of ~3 V. It is shown that the monochromatic efficiency (at a wavelength of 1064 nm) of this module is 31.5% under exposure to a Xe-lamp with a radiation power of 1.5 W/cm^2.
Молекулярно-пучковая эпитаксия двухмерных слоев GaSe на подложках GaAs(001) и GaAs(112): структурные и оптические свойства
Authors: Сорокин С.В. , Авдиенко П.С. , Седова И.В. , Кириленко Д.А. , Яговкина М.А. , Смирнов А.Н. , Давыдов В.Ю. , Иванов С.В.
Published: July 2019

AbstractThe results of studies of the structural and optical properties of two-dimensional GaSe layers grown by molecular-beam epitaxy on GaAs(001) and GaAs(112) substrates using a valve cracking cell for the Se source are reported. The influence of the MBE growth parameters (the substrate temperature, Ga flux intensity, Se/Ga incident flux ratio) on the surface morphology of the layers is studied. By means of transmission electron microscopy, electron diffraction technique, and Raman spectroscopy, it is shown that the structure of the GaSe layers corresponds to the γ-GaSe polytype. From X-ray diffraction analysis, it is established that there exist α-Ga_2Se_3 inclusions in the GaSe layers grown under conditions of high enrichment of the growth surface with Se.
Особенности и закономерности процессов плавления и кристаллизации двухкомпонентных металлических сплавов
Authors: Спивак Л.В. , Щепина Н.Е.
Published: July 2019

The processes of melting and crystallization in some two-component alloys based on the Ag-Cu model system have been investigated using high resolution differential scanning calorimetry. During crystallization or melting jumps in the heat flow upon reaching the liquidus line were detected. It is assumed that during crystallization, these phenomena are associated with the formation of a large number of local microvolumes (concentration fluctuations) in the liquid, enriched with the component leading to crystallization. Their appearance precedes the beginning of the processes of spontaneous formation and growth of numerous crystals of the new phase.
The necessity of correcting the existing ideas about the crystallization and melting of two-component metal alloys is revialed.
Semiconductor behavior and room temperature ferromagnetism in e-beam evaporated Co/TiO-=SUB=-2-=/SUB=- multilayer thin films
Authors: Hossain Faruk , Nahid M.A.I. , Pervez Sarwar , Islam M.A.
Published: July 2019

AbstractThe Co/TiO_2 multilayer thin films have been deposited by e-beam evaporation method on glass substrates in vacuum and annealed in air at 773 K for 1 h. The crystal structure, surface morphology, optical properties, electrical properties and magnetic properties of Co/TiO_2 multilayer thin films have been systematically investigated. The results showed that the particle sizes were significantly reduced when the samples are annealed and the enlargement of particle size occurred when the samples thickness is increased. The spectroscopic analysis exhibited enhanced transmittance and higher optical band gap of annealed sample than the as-deposited one and it was decreased with sample thickness. The resistivity measurement confirmed resistivity decreament with temperature. Furthermore, by investigating the magnetic properties, room temperature ferromagnetism was observed.
Сравнительное исследование коэффициента Нернста--Эттингсгаузена в нормальной фазе в системах Y-=SUB=-1-x-=/SUB=-Pr-=SUB=-x-=/SUB=-Ba-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-y-=/SUB=- и Y-=SUB=-0.85-x-=/SUB=-Pr-=SUB=-x-=/SUB=-Ca-=SUB=-0.15-=/SUB=-Ba-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-y-=/SUB=-
Authors: Гасумянц В.Э. , Мартынова О.А.
Published: July 2019

In this paper, we present the results of a comparative study of the modification of the temperature dependences of the normal-state Nernst coefficient, Q, under praseodymium doping for two sample series of the Y1-xPrxBa2Cu3Oy and Y0.85-xPrxCa0.15Ba2Cu3Oy compositions. Peculiarities of the Q(T) and Q300 K(x) dependences induced by the presence of additional calcium ions in the YBa2Cu3Oy lattice are revealed and analyzed. It is shown that both the Q(T) dependences and the thermopower temperature dependence obtained earlier for the same samples can be fully described on the basis of a narrow-band model. The values of the charge-carrier mobility and the degree of a dispersion law asymmetry are determined by the quantitative analysis of the experimental results. The presence of additional calcium ions in the lattice is shown to not influence a variation of the dispersion law asymmetry with increasing praseodymium doping but to affect strongly the mobility behavior. The observed dependence of the mobility on the doping level in both investigated systems, as well as a difference in variation of the thermopower and Nernst coefficient values in the Y0.85-xPrxCa0.15Ba2Cu3Oy system are explained based on analyzing mechanisms of the influence of the energy spectrum parameters on the mobility value in the YBa2Cu3Oy system.
Магнитоэлектрический эффект в парамагнитной области в Gd-=SUB=-0.15-=/SUB=-Mn-=SUB=-0.85-=/SUB=-Sе
Authors: Аплеснин С.С. , Кретинин В.В. , Бегишева О.Б.
Published: July 2019

In the region of the percolation concentration in the GdxMn1-xSe solid solution, the electric polarization without a field and in 12 kOe magnetic field in the temperature range of 80–380 K was measured . For the composition with x = 0.15, the polarization hysteresis and the dependence of the residual polarization on the magnetic field and temperature were found. The hysteresis is explained in the model of migration polarization and the magnetoelectric effect in the Maxwell-Wagner model.
Пути политипных превращений в карбиде кремния
Authors: Кукушкин С.А. , Осипов А.В.
Published: July 2019

In this work, two main polytypic transformations in silicon carbide, namely, 2H→6H and 3C→6H, were studied using ab initio methods. It is shown that intermediate states with trigonal symmetry P3m1 and monoclinic symmetry Cm greatly simplify the movement of close-packed layers during such transitions, breaking them up into separate stages. It was found that the two polytypic transformations occur quite differently. During the 2H→6H transition, the displaceable bonds are noticeably tilted compared to the initial position, which makes it possible to reduce the compression of SiC bonds in the (112 ̅0) plane. The 3C→6H transition takes place through the formation of auxiliary Si – Si and C – C bonds that live for a short time and help the tightly packed layers exchange places. As a result, the activation barrier for the conversion of 2H→6H (1.7 eV/atom) is significantly less than the activation barrier for the conversion of 3C→6H (3.6 eV/atom), which means that the second transition must occur at temperatures of 750-800 ℃ higher than the first one. The energy profiles of these polytypic transformations, as well as the geometry of all intermediate and transitional phases, are calculated. It is shown that all transition states have monoclinic symmetry.
Магнитная анизотропия и сверхвысокочувствительный стресс-магнитоимпеданс в микропроводах с положительной магнитострикцией
Authors: Неъматов М.Г. , Панина Л.В. , Джумъазода А. , Юданов Н.А. , Морченко А.Т. , Джураев М.А.
Published: July 2019

AbstractIn glass-coated Co_71Fe_5B_11Si_10Cr_3 amorphous ferromagnetic microwires subjected to current annealing, a record sensitivity of the magnetoimpedance (MI) to mechanical tensile stresses (stress MI) up to 100% at 100 MPa in the absence of additional magnetic bias fields is achieved. The current annealing, combining the effect of Joule heating and a circular magnetic field, induces a specific helicoidal/circular-type magnetic anisotropy and, thus, allows one to control the behavior of the MI and stress MI, making the wires more suitable for use in sensor devices. As a result of changing the direction of the easy anisotropy axis, external mechanical stresses lead to a change in the direction of the static magnetization, which causes an increase in the sensitivity of stress MI.
Намагниченность и гигантское магнетосопротивление поликристаллов TbSb при низких температурах
Authors: Волков М.П. , Степанов Н.Н.
Published: July 2019

On the terbium antimonide TbSb polycrystals, the dependences of the magnetization M and the resistance R on the temperature T in the range of 2 ÷ 300 K and on the magnetic field H up to H = 14 T have been studied. On the dependences M (H) at each temperature, a feature (kink) was observed associated with the metamagnetic phase transition. Giant positive magnetoresistance of TbSb in the region of the antiferromagnetic phase has been found.
Влияние глубины переохлаждения на релаксацию доменной структуры триглицинсульфата
Authors: Мазур О.Ю. , Стефанович Л.И.
Published: July 2019

The process of formation and evolution of the domain structure in triglycine sulfate (TGS) crystals after rapid cooling in the vicinity of the Curie point of the ТС has been considered. An analytical expression for the time dependence of the characteristic average size of the domain, which allows us to trace the process of enlargement of the domain structure at all stages of its relaxation to the state of thermodynamic equilibrium has been obtained. It was shown that the average size of a domain grows according to the square root law, which is in good agreement with known experimental data. It was established that the growth rate of the domain structure depends on the undercooling depth of the sample. The dependence of the characteristic average size of the domain on time obtained in this work allows us to determine the radius of the intermolecular interaction of the crystals under study.
Реакция диэлектрических параметров пленок (110)SrTiO-=SUB=-3-=/SUB=- на формирование в их объеме сегнетоэлектрических доменов
Authors: Бойков Ю.А. , Данилов В.А.
Published: July 2019

AbstractThree-layer SrRuO_3/SrTiO_3/SrRuO_3 heterostructures were grown by laser evaporation on (110)LaAlO_3 substrates. Photolithography and ion etching are used to form plane-parallel film capacitors, in which a layer of strontium titanate is placed between two film electrodes of strontium ruthenate. Data on the structure and orientation of the intermediate SrTiO_3 layer in the grown heterostructures were obtained. The variation of the dielectric constant and dielectric loss of the SrTiO_3 intermediate layer upon varying the temperature and intensity of an external electric field was studied.
Диэлектрический отклик керамических твердых растворов 16BiScO-=SUB=-3-=/SUB=--42PbMg-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--42PbTiO-=SUB=-3-=/SUB=- в электрическом поле
Authors: Камзина Л.С. , Таланов М.В. , Буш А.А. , Спицин А.И.
Published: July 2019

AbstractSome results of studying the dielectric and electromechanical properties of ceramic 16BiScO_3–42PbMg_1/3Nb_2/3O_3–42PbTiO_3 relaxor ferroelectric samples in electrical fields (0 < E < 20 kV/cm) are presented. An appreciable decrease in the dielectric permittivity with time, and the disappearance of hysteresis in the dependence of the longitudinal strain on the electrical field intensity were revealed in the fields exceeding the coercive field ( E > 10 kV/cm) and explained by the induced ferroelectric phase transition. The field-induced phase (presumably, tetragonal) was shown to be unstable and partially ordered. A nonmonotonical character demonstrated by the dielectric permittivity–time dependences of the studied ceramics unlike the other relaxor ferroelectrics was explained by the coexistence of glassy and ferroelectric phases.
Усиление нанокомпозитов полимер/2D-нанонаполнитель: базовые постулаты
Authors: Козлов Г.В. , Долбин И.В.
Published: July 2019

AbstractIt has been shown that almost every theoretical model known to date allows for correctly describing the properties of polymer nanocomposites on the condition that the real not nominal characteristics of their components are used. These real characteristics are always related to the formation of the interfacial regions in the mentioned nanomaterials. This means that the efficiency of the filler in polymer nanocomposites is controlled by its ability to generate interfacial regions.
Optical analysis using effective medium theory and finite element method to study the enhanced light absorption in porous BaMgAl-=SUB=-10-=/SUB=-O-=SUB=-17-=/SUB=- : Eu-=SUP=-2+-=/SUP=- phosphor
Authors: Liang Ying-Lin , Yin Liang-Jun , Bui Hao-Van , Jian Xian , Yang Guang , Ding Jie-Xiong
Published: July 2019

AbstractThe main objective of this paper is to reveal the mechanism of enhanced excitation light absorption in nano-pores structure BaMgAl_10O_17:Eu^2+ (BAM) phosphor by optical analysis. The optical refractive index of the BAM was calculated from the reflectance spectra by Kramers–Kronig dispersion relation. And based on the effective medium theory, the anisotropic optical properties of porous BAM layer and its relations of absorption enhancement with porosity and thickness were investigated. A finite element simulation model was used for study the influence of pores size on optical properties. All the numerically evaluated results were match the experimental data.
Влияние спекающей добавки Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- на электропроводность протонного электролита CaZr-=SUB=-0.95-=/SUB=-Sc-=SUB=-0.05-=/SUB=-O-=SUB=-3-delta-=/SUB=-
Authors: Дунюшкина Л.А. , Мещерских А.Н. , Халиуллина А.Ш. , Балакирева В.Б. , Панкратов А.А.
Published: July 2019

The effect of the sintering additive Al2O3 on the electrical conductivity of a polycrystalline proton electrolyte based on calcium zirconate, CaZr0.95Sc0.05O3-δ (CZS) was studied. It is shown that the introduction of the sintering additive Al2O3 makes it possible to obtain dense ceramics by the combustion method at a relatively low temperature (1470 ° С). The introduction of 0.1–0.5 wt% Al2O3 leads to an increase in the grain size of ceramics from 100 nm to 1-2 μm. Al2O3 additives up to 0.3 wt% increase the electrolyte conductivity. It has been established that with the introduction of Al2O3, calcium aluminates are formed at the grain boundaries. The proton character of charge transfer was revealed both in the volume of grains and at the grain boundaries of the electrolyte in humid air.
Фазовый переход металл--диэлектрик в тонких пленках диоксида ванадия, легированного вольфрамом
Authors: Андреев В.Н. , Климов В.А.
Published: July 2019

AbstractThe electrical conductivity of thin polycrystalline V_(1 – _ x )W_ x O_2 has been studied in a wide temperature range, which covers the regions of both the metallic and insulator phases. An increase in the tungsten concentration is shown to shift the metal–insulator phase transition toward lower temperatures, while the temperature range of the coexistence of the phases monotonically increases as the impurity concentration increases. The temperature dependence of the conductivity of the insulator phase of V_(1 – _ x )W_ x O_2 is explained using the hopping conduction model that takes into account the influence of thermal vibrations of atoms on the resonance integral. Parameter ε in the dependence on the level of doping VO_2 has been calculated.
Электронно-стимулированная десорбция атомов цезия с графена на иридии, интеркалированного и не интеркалированого цезием
Authors: Кузнецов Ю.А. , Лапушкин М.Н. , Рутьков Е.В. , Галль Н.Р.
Published: July 2019

Electron stimulated desorption (ESD) of neutral atomic Cs from graphene on Ir has been studied for two cases: when Cs intercalation does present and when it does not take place. Two peaks have been found at desorbed atom energy distribution: high-energy (HE) at the energy of 0.36 eV and low-energy (LE) one at the energy of 0.13 eV. HE peak has been observed for both cases, we attribute it with excitation of 2s carbon core level. LE peak was observed only when intercalation does not take place; we attribute it with excitation of 4f and 5p core levels of Ir. A model is put forward to describe atomic Cs ESD; we proposed that graphene on Ir acts as dielectric in the processes discussed above.
Поверхностные плазмон-поляритоны в тонкой пленке "графен-полупроводник-графен"
Authors: Абрамов А.С. , Евсеев Д.А. , Семенцов Д.И.
Published: July 2019

In this work for far-infrared range we investigated the dispersion properties of surface plasmon polaritons in a structure «graphene plate-thin semiconductor film graphene plate». It is shown the ability of control the propagation modes by changing the chemical potential on one or both plates. It were received the dispersion relations for waves with TE- and TM-polarization and the distribution of wave field and energy fluxes along the transverse axes relate to propagation wave. It is shown that there is the spectral range, which characterized by negative group velocity.
Эффект Шоттки в Bi-=SUB=-0.95-=/SUB=-Sm-=SUB=-0.05-=/SUB=-FeO-=SUB=-3-=/SUB=-
Authors: Митаров Р.Г. , Каллаев С.Н. , Омаров З.М. , Резниченко Л.А.
Published: July 2019

AbstractThe temperature dependence of the specific heat of the Bi_0.95Sm_0.05FeO_3 multiferroic has been studied in the temperature range 130–780 K. The substitution of samarium ions for bismuth ions in the bismuth ferrite is found to lead to the appearance of additional specific heat component that is due to the manifestation of the Schottky effect for three-level states and multiplet structure of 4 f electrons of samarium ions.
Кольцевые волны на поверхности жидкости в кулоновском поле
Authors: Ширяева С.О. , Григорьев А.И.
Published: July 2019

Regularities of realization of instability of ring waves on the surface of conductive liquid in the Coulomb field are investigated. The relation for connection of frequency of ring capillary and gravitational waves on a surface of liquid in non-uniform electrostatic field of a dot charge with physical parameters of a task and with an analog of wave number is brought. By analogy with the field parameter of Tonks-Frenkel the field parameter characterizing stability of a surface of conductive liquid in the non-uniform Coulomb field is determined. It is found that critical conditions of realization of instability of ring waves on the surface of conductive liquid in the Coulomb field are more soften than critical conditions of realization of instability of Tonks-Frenkel.
Исследование испарения лазерно-нагретых железо-углеродных наночастиц при помощи анализа их теплового излучения
Authors: Гуренцов Е.В. , Еремин А.В. , Мусихин С.А.
Published: July 2019

AbstractEvaporation of iron nanoparticles in carbon shells under pulsed laser irradiation is analyzed. Iron–carbon nanoparticles are synthesized in a shock tube reactor with the aid of pyrolysis of the 0.25% Fe(CO)_5 + 0.25% C_6H_6 mixture in argon. Laser radiation is used for additional heating to temperatures that exceed the evaporation threshold of the iron core of nanoparticles. Time profiles of the thermal radiation of laser-heated nanoparticles are measured. The two-color pyrometry is used to determine the evaporation temperature of nanoparticles, and the laser extinction makes it possible to monitor the loss of volume fraction of the condensed phase upon evaporation. Approximation of experimental signals of laser-heated nanoparticles using model curves is employed to determine effective enthalpy of evaporation of iron–carbon nanoparticles. It is shown that the iron core of nanoparticles is evaporated through the carbon shell and the energy spent by such a process is approximately twice greater than the evaporation enthalpy of bulk iron with free surface.
Импульсное намагничивание короткозамкнутой катушки из ВТСП
Authors: Бражник П.А. , Картамышев А.А. , Коротков В.С. , Красноперов Е.П. , Бишаев А.А. , Козинцева М.В.
Published: July 2019

In this paper is described the pulsed magnetization of a 20-turn short-circuited coil from a stabilized HTSC-2G tape. The trapped field in the coil is close to the value obtained at the field cooling (FC) process and varies only slightly with a 5-fold increase in the amplitude of the magnetizing pulse. The copper coating of the tape significantly reduces the effects of pulsed heating. The relaxation of the current in the initial stage is determined by the flow of current between the superconducting and normal layer and the type of the current-voltage characteristic. At large times (t> 100 s), attenuation is determined by the contact resistance of the junction.
Неупругость и наноструктурная дислокационная деформация сплава алюминия с кремнием с супермодифицированной эвтектической структурой
Authors: Никаноров С.П. , Кардашев Б.К. , Осипов В.Н. , Каминский В.В. , Шаренкова Н.В.
Published: July 2019

AbstractYoung’s modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well as the subgrain size and residual stresses in the strontium modified alloy of aluminum with 15 wt % silicon have been studied. The alloy was obtained with a solidification rate of 1 mm/s at the shifted eutectic point. The dependence of inelastic dislocation deformation on the applied oscillating stress has been obtained and analyzed. The effect of strontium modification on the microstrain diagram can be accounted for by transformation of the lamellar fiber structure of eutectic silicon into a superfine fiber structure.
Исследования стабильности тонкопленочных структур Cu-As-=SUB=-2-=/SUB=-S-=SUB=-3-=/SUB=- и Ag-As-=SUB=-2-=/SUB=-S-=SUB=-3-=/SUB=-
Authors: Настас А.М.
Published: July 2019

AbstractThin-film Cu–As_2S_3 and Ag–As_2S_3 structures obtained by successively evaporating Cu(Ag) and As_2S_3 in vacuum on glass substrates have been studied. Samples of these structures have been kept in air at room temperature in the dark for 6 months, and transmission spectra have been periodically taken of these samples. The logarithm of inverse transmission coefficient in the transparency domain of As_2S_3 has been used as a measure that is proportional to the thickness of the metal film. It has been found that for Ag–As_2S_3 the thickness of the metal film varies with storage time linearly, whereas for Cu–As_2S_3 this dependence can be described by two different linear sections. From the decrease in metal film thickness, it has been concluded that the Ag–As_2S_3 structure is more stable than Cu–As_2S_3. It has been supposed that silver, unlike copper, does not react with As_2S_3 when the structures are stored in the dark, although it permanently diffuses into As_2S_3 during storage.
Метод рециркуляции сигналов в задаче наблюдения точечного объекта над металлической поверхностью
Authors: Чапурский В.В. , Калинин В.И. , Бугаев А.С. , Разевиг В.В.
Published: July 2019

In the problem of localizing the position of a point object over a metal reflecting surface, the application of an ultra-wideband signal in the centimeter wavelength range is analyzed using the method of signal recirculation in the loops of spatial recirculation of «emitter – target receiving element of antenna array emitter." The determination of the object coordinate over the metal surface is based on the calculation of the generalized correlation integral in spectral form for the frequency coefficients of the recirculation loops over all receiving elements, taking into account the coordinates of the true object, its mirror reflection and the reference point of space. The comparison of sounding results in the presence and absence of recirculation is given.
Исследование процессов зарядки ионно-имплантированных диэлектриков под воздействием электронного облучения
Authors: Рау Э.И. , Татаринцев А.А. , Зыкова Е.Ю. , Зайцев С.В.
Published: July 2019

AbstractThe charging kinetics of Al_2O_3 (sapphire) and SiO_2 (α-quartz) dielectrics irradiated by inert gas ions (Ar^+), metal ions (Ga^+), and protons (H^+) has been studied. It has been found that charging kinetics depends considerably on the type of irradiating ion. Also, it has been established that preirradiation of a dielectric target by an ionizing corpuscular radiation (protons, ions) substantially changes the charge characteristics of the dielectric surface. These differences depend on irradiating ion energy, which governs the depth of an accumulated negative charge layer versus the depth of ion preimplantation.