The nonlinear effects in 2DEG conductivity investigation by an acoustic method

The parameters of two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure were determined by an acoustical (contactless) method in the delocalized electrons region ($B\le$2.5T). Nonlinear effects in Surface Acoustic Wave (SAW) absorption by 2DEG are determined by the electron heating in the electric field of SAW, which may be described in terms of electron temperature $T_e$. The energy relaxation time $\tau_{\epsilon}$ is determined by the scattering at piezoelectric potential of acoustic phonons with strong screening. At different SAW frequencies the heating depends on the relationship between $\omega\tau_{\epsilon}$ and 1 and is determined either by the instantaneously changing wave field ($\omega\tau_{\epsilon}$$<1$), or by the average wave power ($\omega\tau_{\epsilon}$$>1$).Comment: RevTeX, 5 pages, 3 PS-figures, submitted to Physica Status Sol.(Technical corrections in PS-figs

The assessment of the level of digitalization and digital transformation of oil and gas industry of the Russian Federation

Digitalization and digital transformation of companies have turned from global trends to an urgent need. Thanks to digitalization and digital transformation, organizations can overcome the times of crisis, the times of lockdowns with less losses and respond more effectively to any adverse changes in the external environment. The assessment of the level of digitalization and digital transformation allows to determine how fast the processes of introducing digital technologies and optimizing processes with digital solutions proceed, both in companies and across the industry as a whole. The article provides an analysis with the systematization of foreign and domestic methods, methodological approaches, methods for assessing the digitalization level and digital transformation, as well as reveals their positive and negative aspects. Based on a comparative analysis, an improved author-developed methodological toolkit is proposed for assessing the level of digitalization and digital transformation, alleviating the disadvantages of the existing methodological experience. The approbation of the author-developed methodological toolkit was performed using the oil and gas industry as an example; the following companies, being the industry leaders, were analysed: PJSC “Lukoil”, PJSC “NK “Rosneft”, PJSC “Gazprom”, and PJSC “Tatneft”. According to the results, the digitalization and digital transformation processes of the domestic oil and gas industry are insufficiently dynamic. It was found that in the period from 2016 to 2020, the Russian Federation industry leaders were in the following order from the most advanced to the least advanced in terms of the digitalization level and digital transformation: PJSC “Gazprom” topped the list; PJSC “NK “Rosneft” was second; PJSC “Lukoil” was the third largest company, and PJSC “Tatneft” held the fourth position

Electron localization in sound absorption oscillations in the quantum Hall effect regime

The absorption coefficient for surface acoustic waves in a piezoelectric insulator in contact with a GaAs/AlGaAs heterostructure (with two-dimensional electron mobility $\mu= 1.3\times 10^5 cm^2/V\cdot s)$ at T=4.2K) via a small gap has been investigated experimentally as a function of the frequency of the wave, the width of the vacuum gap, the magnetic field, and the temperature. The magnetic field and frequency dependencies of the high-frequency conductivity (in the region 30-210 MHz) are calculated and analyzed. The experimental results can be explained if it assumed that there exists a fluctuation potential in which current carrier localization occurs. The absorption of the surface acoustic waves in an interaction with two-dimensional electrons localized in the energy "tails" of Landau levels is discussed.Comment: RevTeX 6 pages+6 EPS pic

MINERAL AND RAW MATERIALS BASE OF THE URAL FEDERAL DISTRICT: ON THE WAY TO A SUSTAINABLE SUBSOIL USE (USING SOLID COMMERCIAL MINERALS AS AN EXAMPLE)

Relevance. The process of sustainable use of mineral resources, which is one of the priority areas of both rehabilitation, extraction of natural resources, and the state policy in the field of national security, is of particular importance. Currently, the state regulation of subsoil use faces a number of pressing problems: first, the process of recovering the exhaustible resources of solid commercial minerals (SCM) is hampered; secondly, penetration the sixth techno-economic paradigm and the growing “fourth industrial revolution” dictate their terms for organizing a sustainable subsoil use, which implies achieving a balance of common development factors (resource, “green”, social, economic ones) using high technologies, artificial intelligence devices, robotics and other innovative solutions. In order to implement sustainable subsoil use at the regional and country levels, it is necessary to diagnose the state of the mineral resources base (MRB). This evaluation can become a functional tool for state regulation of subsoil use. Purpose of the work is to analyze the state of the mineral resource base of the subsoil use of the Ural Federal District (UFD) from the point of view of fulfilling the condition of balance (security). Results. The basic principle is defined – the condition for achieving a balance of subsoil use; peculiarities and problems in the management of subsoil use of the Ural Federal District on the basis of the analysis of the Ural Federal District and the system for financing geological exploration in the UFD; some possible directions for meeting the condition for achieving a balance are identified. Conclusion. The exhaustion of the region’s MRB of SCM and the priority of the extraction of fuel and energy raw materials contribute to a reduction in federal funding for the development of the MRB of SCM of the Ural Federal District. The subsoil users of the region are provided with reserves, to some extent, and they are not interested in carrying out further prospecting works. The foregoing demonstrates the need to develop and implement some balanced solutions for further stage of geological study of the MRB of SCM in the framework of public private partnerships using industry regulation mechanisms to achieve a sustainable supply of producers with their own raw materials

Magnetic-field-dependent zero-bias diffusive anomaly in Pb oxide-n-InAs structures: Coexistence of two- and three-dimensional states

The results of experimental and theoretical studies of zero-bias anomaly (ZBA) in the Pb-oxide-n-InAs tunnel structures in magnetic field up to 6T are presented. A specific feature of the structures is a coexistence of the 2D and 3D states at the Fermi energy near the semiconductor surface. The dependence of the measured ZBA amplitude on the strength and orientation of the applied magnetic field is in agreement with the proposed theoretical model. According to this model, electrons tunnel into 2D states, and move diffusively in the 2D layer, whereas the main contribution to the screening comes from 3D electrons.Comment: 8 double-column pages, REVTeX, 9 eps figures embedded with epsf, published versio

Interaction effects and phase relaxation in disordered systems

This paper is intended to demonstrate that there is no need to revise the existing theory of the transport properties of disordered conductors in the so-called weak localization regime. In particular, we demonstrate explicitly that recent attempts to justify theoretically that the dephasing rate (extracted from the magnetoresistance) remains finite at zero temperature are based on the profoundly incorrect calculation. This demonstration is based on a straightforward evaluation of the effect of the electron-electron interaction on the weak localization correction to the conductivity of disordered metals. Using well-controlled perturbation theory with the inverse conductance $g$ as the small parameter, we show that this effect consists of two contributions. First contribution comes from the processes with energy transfer smaller than the temperature. This contribution is responsible for setting the energy scale for the magnetoresistance. The second contribution originates from the virtual processes with energy transfer larger than the temperature. It is shown that the latter processes have nothing to do with the dephasing, but rather manifest the second order (in $1/g$) correction to the conductance. This correction is calculated for the first time. The paper also contains a brief review of the existing experiments on the dephasing of electrons in disordered conductors and an extended qualitative discussion of the quantum corrections to the conductivity and to the density of electronic states in the weak localization regime.Comment: 34 pages, 13 .eps figure

Использование результатов радиационного мониторинга окружающей среды для контроля источника выбросов йода-131 предприятием

The analysis was performed, whether the following characteristics correspond with each other: data on the annual release of the radionuclide by the enterprise, the calculation model used for establishing the annual permissible release levels of radionuclides, and the annual average volume activity of the radionuclide, determined using the data of routine radiation monitoring of the surface air. Such analysis was carried out for the release of 131I from the L.Ya. Karpov Scientific Research Institute of Physics and Chemistry (Obninsk) in 2013–2022. It is shown that for the enterprise release in 2013–2022, the results of environmental radiation monitoring confirm both the data of radiation control of the 131I release source and the correctness of the radionuclide air transfer calculation model. The average annual meteorological dilution factor of the 131I for the enterprise release in the surface layer of the atmosphere, estimated from monitoring data, does not exceed the model calculated value. Strong correlation was revealed between the average annual volume activity of 131I in the surface air, obtained using measurement results, and data on annual air releases of the enterprise. No correlation was found for the variability of the dilution factor estimated by the transfer model and monitoring data. It may be caused by the heterogeneity of the 131I releases by the enterprise during the year.Выполнен анализ взаимного соответствия данных о годовом выбросе радионуклида предприятием, расчетной модели переноса примеси, использующейся при установлении нормативов предельно допустимых выбросов, и среднегодовой объемной активности радионуклида, определенной с использованием данных радиационного мониторинга приземного слоя воздуха, на примере выброса 131I акционерным обществом «Научно-исследовательский физико-химический институт им. Л.Я. Карпова» (г. Обнинск). Показано, что для выброса предприятия в 2013–2022 гг. результаты радиационного мониторинга окружающей среды подтверждают как данные радиационного контроля источника выброса 131I, так и адекватность расчетной модели переноса примеси. Среднегодовой метеорологический фактор разбавления выброса 131I предприятием в приземном слое атмосферы, оцененный с использованием данных мониторинга, не превышает значение, полученное с помощью модели расчета переноса примеси. Выявлена сильная корреляция среднегодовой объемной активности 131I в приземном воздухе, полученной с использованием результатов измерений, и данных радиационного контроля годовых выбросов предприятия. Отсутствует корреляция изменчивости фактора разбавления по расчетным оценкам и данным мониторинга, что может быть связано с неоднородностью выброса 131I предприятием в течение года

Results of thrombectomy in lower-extremity ischemia in patients with COVID-19 and respiratory failure of different severity

Aim. To analyze the results of thrombectomy in lower-extremity ischemia in patients with coronavirus disease 2019 (COVID-19) and respiratory failure of different severity.Material and methods. This retrospective, cohort, comparative study for the period from May 1, 2020 to March 1, 2022 included 305 patients with acute lower-extremity ischemia and COVID-19. Depending on the type of oxygen support, three groups of patients were formed: group 1 (n=168) — nasal oxygen insufflation; group 2 (n=92) — non-invasive ventilation (NIV); group 3 (n=45) — artificial ventilation (AV). Thrombectomy was carried out according to the standard technique using Fogarty catheters (3F-6F — depending on the vessel size). After the diagnosis was established before and after the start of surgical treatment, all patients received the following therapy: Unfractionated IV heparin infusion at an initial rate of 1000 U/r, adjusted to maintain the activated partial thromboplastin time at 2-3 times the normal value; 2. Oral acetylsalicylic acid 125 mg; 3. Analgesics.Results. Myocardial infarction and ischemic stroke were not detected in the total sample. The highest number of deaths (group 1: 5,3%, n=9; group 2: 72,8%, n=67; group 3: 100%, n=45; p&lt;0,0001), retrombosis (group 1 : 18,4%, n=31; group 2: 69,5%, n=64; group 3: 91,1%, n=41; p&lt;0,0001) and limb amputations (group 1: 9,5%, n=16; group 2: 56,5%, n=52; group 3: 91,1%, n=41; p&lt;0,0001) was recorded in group 3 patients.Conclusion. In patients receiving mechanical ventilation, COVID-19 have more aggressive course, which is expressed in an increase in laboratory para- meters (C-reactive protein, ferritin, interleukin-6, D-dimer), the severity of pneumonia and location of thrombosis in the tibial arteries. Among patients with COVID-19 receiving mechanical ventilation, the greatest number of rethromboses (91,1%), limb amputations (91,1%), and deaths (100%) are noted, which suggests the expediency of abandoning open thrombectomy in favor of anticoagulant/antiplatelet therapy in this cohort of patients. The development of arterial thrombosis in patients with COVID-19 receiving mechanical ventilation is an indicator of a high risk of death. Open thrombectomy in combination with anticoagulant/antiplatelet therapy is most effective in patients on nasal oxygen insufflation or NIV

To the question of improving the outcomes of surgical treatment of genital prolapse in postmenopausal women

Currently, the frequency of genital prolapse in the structure of common gynecological diseases has no tendency to decrease and may take up to 15% of large gynecological operations. With the aim of improving outcomes of surgical treatment of this category of patients, at the stage of preoperative preparation and the postoperative period used vaginal capsules containing Lactobacillus + progesterone 2 mg + estriol 0.2 mg (Triozhinal). The study included 239 patients in postmenopausal women with genital prolapse and phenomena cystourethroscopy and vaginal atrophy. Of these, the main group consisted of 122 women who underwent the proposed scheme of preoperative preparation and postoperative period. Group comparisons were presented 117 patients admitted to the gynecological Department for surgical treatment of prolapse with traditional preoperative and postoperative management. The results of the study showed that in the group of patients receiving local therapy estriola in combination with progesterone and lactobacilli, was observed a significant improvement of the clinical picture of urinary disorders, quality of life, symptoms of urogenital atrophy during surgical correction of urinary incontinence or genital prolapse, and this tactic can be recommended as in the pre-and postoperative periods.В настоящее время частота пролапса гениталий в структуре гинекологических заболеваний не имеет тенденции к снижению и занимает до 15% гинекологических операций. С целью улучшения исходов хирургического лечения данной категории пациенток, на этапе предоперационной подготовки и в период послеоперационной реабилитации использованы вагинальные капсулы, содержащие лактобактерии + прогестерон 2мг + эстриол 0,2 мг (триожиналь). Под наблюдением находились 239 пациенток в постменопаузе с пролапсом гениталий и явлениями вагинальной и цистоуретральной атрофии. Из них основную группу составили 122 женщины, которым проводилась предложенная нами схема ведения предоперационной подготовки и послеоперационного периода. Группа сравнения была представлена 117 пациентками, поступившим в гинекологическое отделение с традиционной предоперационной подготовкой и послеоперационным ведением. Результаты исследования показали, что в группе пациенток, получающей локальную терапию эстриолом в сочетании с прогестероном и лактобактериями, наблюдалось значимое улучшение клинической картины расстройств мочеиспускания, показателей качества жизни, симптомов урогенитальной атрофии при хирургической коррекции недержания мочи или пролапса гениталий, и такая тактика может быть рекомендована как в пред-, так и в послеоперационном периодах