Layered semiconductor InSe as a standard nanorelief in the metrology of nanoobjects

Intensive development of nanotechnology requires high-precision measurements on atomic and molecular levels by creating the metrological system for measurements, at the first turn, the length in the nanometer scale. Such measurements require standard samples of nanorelief surface. High chemical stability and the absence of dangling bonds (defects), low surface roughness of cleaved surface allows to use the Van der Waals surface of InSe single crystals as the standard nanorelief. This is evidenced by the research1es of morphology for Van der Waals surface by scanning tunneling microscopy in which images with atomic resolution were obtained. A single crystal InSe, was grown by vertical Bridgman-Stockbarger method. The crystal has --polytype rhombohedral structure . with periods a = 4.003 Å, and c = 24.9553 Å (in hexagonal axes). Thus InSe is appropriate standard nanorelief for probe microscopy. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2085

Spin-dependent part of ppˉp\bar{p} interaction cross section and Nijmegen potential

Low energy $p\bar{p}$ interaction is considered taking into account the polarization of both particles. The corresponding cross sections are calculated using the Nijmegen nucleon-antinucleon optical potential. Then they are applied to the analysis of the polarization buildup which is due to the interaction of stored antiprotons with polarized protons of a hydrogen target. It is shown that, at realistic parameters of a storage ring and a target, the filtering mechanism may provide a noticeable polarization in a time comparable with the beam lifetime.Comment: 10 pages, 3 figure

Polarization effects in non-relativistic epep scattering

The cross section which addresses the spin-flip transitions of a proton (antiproton) interacting with a polarized non-relativistic electron or positron is calculated analytically. In the case of attraction, this cross section is greatly enhanced for sufficiently small relative velocities as compared to the result obtained in the Born approximation. However, it is still very small, so that the beam polarization time turns out to be enormously large for the parameters of $e^{\pm}$ beams available now. This practically rules out a use of such beams to polarize stored antiprotons or protons.Comment: 9 pages; version accepted for publication in Nucl.Instr.Methods B where cross sections without averaging over directions of relative velocities are adde

Spin effects in ppˉp\bar p interaction and their possible use to polarize antiproton beams

Low energy $p\bar p$ interaction is considered taking into account the polarization of both particles. The corresponding cross sections are calculated using the Paris nucleon-antinucleon optical potential. Then they are applied to the analysis of the polarization buildup which is due to the interaction of stored antiprotons with polarized protons of a hydrogen target. It is shown that, at realistic parameters of a storage ring and a target, the filtering mechanism provides a noticeable polarization in a time comparable with the beam lifetime.Comment: 10 pages, 4 figure

Study of hydrodynamics in counterflow cooling tower with corrugated contact elements

Packing for liquid cooling with counter flow of liquid and gas phases had developed by authors of paper. This packing is different from other devices in that it has quite simple design where self distribution of liquid in apparatus working area is organized. In paper an estimating calculations of packing operating mode with maximum efficiency of performed heat and mass transfer processes had conducted. The performed numerical study is showing that at mean gas velocity up to 4 m/s, contact device width equal to 0.1 m and liquid column height on contact stage – 0.02 m the share of liquid that forced through by gas flow is not more then 2 %. Decreasing of holes diameter on inclined contact elements results in increasing of bubbled liquid share.The reported study was funded by grant of the President of the Russian Federation, project number MK-417.2019.8

Mass coupling and Q−1ofimpurity−limitednormalQ^{-1} of impurity-limited normal ^3$He in a torsion pendulum

We present results of the $Q^{-1}$ and period shift, $\Delta P$, for $^3$He confined in a 98% nominal open aerogel on a torsion pendulum. The aerogel is compressed uniaxially by 10% along a direction aligned to the torsion pendulum axis and was grown within a 400 $\mu$m tall pancake (after compression) similar to an Andronikashvili geometry. The result is a high $Q$ pendulum able to resolve $Q^{-1}$ and mass coupling of the impurity-limited $^3$He over the whole temperature range. After measuring the empty cell background, we filled the cell above the critical point and observe a temperature dependent period shift, $\Delta P$, between 100 mK and 3 mK that is 2.9$$ of the period shift (after filling) at 100 mK. The $Q^{-1}$ due to the $^3$He decreases by an order of magnitude between 100 mK and 3 mK at a pressure of $0.14\pm0.03$ bar. We compare the observable quantities to the corresponding calculated $Q^{-1}$ and period shift for bulk $^3$He.Comment: 8 pages, 3 figure

Расчетное обоснование механической безопасности Конгресс-холла в Челябинске

Aims of research. The article is devoted to actual problems of computational analysis of stress-strain state, strength and stability of load-bearing structures with allowance for the main and special combinations of loads and impacts, comparison of the results of alternative structural analysis of unique cultural and business complex “Congress Hall” in Chelyabinsk. The natural conditions of the area of location of this object and main load-bearing structures of the object are described. Besides, characteristic and design loads, their combinations, formulation of objectives of computational research and methods of solution are presented. Methods. Space discretization and solution of the corresponding problems of mathematical (numerical) and computer modelling of the considering unique building were carried out with the use of finite element method. Detailed finite element models of the coupled system “combined foundation - loadbearing structures” and its fragments (subsystems) were developed and verified. They adequately reflect geometric-stiffness, inertial and load parameters of the object and the resulting stress-strain state. Progressive collapse analysis are under consideration as well. Licensed, certified and verified (by the Russian Academy of Architecture and Construction Sciences) finite element software package “ANSYS Mechanical” was used. Results. The resulting parameters of stress-strain state, strength and dynamics of load-bearing structures of the building with allowance for design (in accordance with design codes) combinations of vertical and wind loads are considered. Besides, information about results of progressive collapse analysis is presented. Thus, a reasonable conclusion is made about the reliability of the criterion parameters of strength, stability and dynamics of the load-bearing structures of the object.Цели. Статья посвящена актуальным вопросам расчетных исследований напряженно-деформированного состояния (НДС), прочности и устойчивости основания и несущих конструкций при основных и особых сочетаниях нагрузок и воздействий, сравнительного анализа результатов альтернативных расчетов уникального проектируемого объекта строительства - общественно-делового центра «Конгресс-холл» в Челябинске. Описаны природные условия района расположения здания, устройство комбинированного основания, фундаментов и несущих конструкций объекта, основные и особые нагрузки (расчетные и нормативные) и их сочетания, постановка задач расчетных исследований, инструментарий их решения и полученные результаты. Методы. Дискретизация по пространству и решение результирующих задач математического (численного) моделирования состояния объекта осуществлялись методом конечных элементов в перемещениях. Построены, разработаны и проверены подробные конечноэлементные модели системы «комбинированное основание - несущие конструкции здания» и отдельных подсистем, адекватно отражающие геометрико-жесткостные, инерционные и нагрузочные характеристики объекта и результирующее НДС, проанализирована устойчивость против прогрессирующего обрушения. Все основные расчеты проведены с использованием лицензионного конечноэлементного программного комплекса ANSYS Mechanical, верифицированного в Российской академии архитектуры и строительных наук (РААСН). Результаты. Рассмотрены результирующие параметры НДС, прочности и динамики основания и несущих конструкций объекта при нормативно-регламентированных сочетаниях вертикальных и ветровых нагрузок, а также результаты расчетов на устойчивость против прогрессирующего обрушения. В заключении делается обоснованный вывод о достоверности полученных расчетами критериальных параметров, определяющих прочность, устойчивость и динамику несущих конструкций объекта

Attitude to antibiotic therapy in dentists conducting therapeutic treatment of patients

Objective. To assess practicing dentists who treat patients conservatively attitude to antibiotic therapy in general, the degree of awareness of the rules for prescribing antibiotics, approaches to prescribing antibiotics for various dental diseases and therapeutic and preventive manipulations. Materials and Methods. The questionnaire was developed and an anonymous survey-questionnaire of 173 practical dentists conducting therapeutic reception of patients was carried out. The questionnaire included a list of diseases, therapeutic and prophylactic manipulations in which respondents consider the use of antibiotics indicated and questions to assess the respondents’ awareness of modern methods of antibiotic therapy and their views on the rules for prescribing antibiotics. Results. A statistical analysis showed that antibiotics using is considered inappropriate: in the conservative treatment of pulpitis after root canal filling (83.2%), during the conservative treatment of chronic apical periodontitis (66.5%, 95% CI: 59,4-73,5%), in patients with chronic catarrhal gingivitis (69.4%, 95% CI: 62,5-76,2%), in patients with chronic generalized periodontitis mild degree (without exacerbation) (75.1%, 95% CI: 68,7-81,6%), during professional cleaning of teeth (75.1%, 95% CI: 68,7-81,6%). The use of antibiotics is considered obligatory: in the treatment of acute apical periodontitis/exacerbation of chronic periodontitis (with suppuration from root canals) – 37.0% of respondents (95% CI: 29,8-44,2%); ulcerative necrotic gingivitis – 50.3% (95% CI: 42,8-57,7%), with chronic generalized periodontitis in the acute stage – 71.1% (95% DI: 64,3-77,9%), with professional cleaning of teeth in patients with concomitant pathology – 38.2% (95% DI: 30.9-45.4%) Conclusions. Insufficient awareness of practical dentists, leading the conservative reception of patients, about modern methods of antibiotic therapy was revealed. The problems of the current dentistry situation are identified under such conditions of legally approved standards of care and clinical recommendations absence, as well as absence of organizational opportunities to conduct tests to determinate the sensitivity of microflora to antimicrobial drugs before prescribing antibiotics in outpatient dentistry are identified

On-chip waveguide coupling of a layered semiconductor single photon source

Fully integrated quantum technology based on photons is in the focus of current research, because of its immense potential concerning performance and scalability. Ideally, the single-photon sources, the processing units, and the photon detectors are all combined on a single chip. Impressive progress has been made for on-chip quantum circuits and on-chip single-photon detection. In contrast, nonclassical light is commonly coupled onto the photonic chip from the outside, because presently only few integrated single-photon sources exist. Here, we present waveguide-coupled single-photon emitters in the layered semiconductor gallium selenide as promising on-chip sources. GaSe crystals with a thickness below 100 nm are placed on Si3N4 rib or slot waveguides, resulting in a modified mode structure efficient for light coupling. Using optical excitation from within the Si3N4 waveguide, we find nonclassicality of generated photons routed on the photonic chip. Thus, our work provides an easy-to-implement and robust light source for integrated quantum technology

Magnetotransport in two-dimensional electron gas at large filling factors

We derive the quantum Boltzmann equation for the two-dimensional electron gas in a magnetic field such that the filling factor $\nu \gg 1$. This equation describes all of the effects of the external fields on the impurity collision integral including Shubnikov-de Haas oscillations, smooth part of the magnetoresistance, and non-linear transport. Furthemore, we obtain quantitative results for the effect of the external microwave radiation on the linear and non-linear $dc$ transport in the system. Our findings are relevant for the description of the oscillating resistivity discovered by Zudov {\em et al.}, zero-resistance state discovered by Mani {\em et al.} and Zudov {\em et al.}, and for the microscopic justification of the model of Andreev {\em et al.}. We also present semiclassical picture for the qualitative consideration of the effects of the applied field on the collision integral.Comment: 28 pages, 19 figures; The discussion of the role of the effect of the microwave field on the distribution function is revised (see also cond-mat/0310668). Accepted in Phys. Rev.