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238 results on '"Nekrasov, K. A."'

2. The structure of the logistics supply chains of the EU countries in the context of the Covid-19 pandemic.

Author

Nekrasov, K. V.

Subjects
*COVID-19 pandemic, *SUPPLY chains, *ECONOMIC stabilization, *TRANSPORTATION industry, *LOGISTICS, *COVID-19
Abstract

The article shows that the crisis phenomena taking place in the world have an impact on many socio-economic processes. The scale of these negative consequences affected not only the local markets of countries, but also made significant adjustments to the existing economic relations in supply chains and their structure on a global scale. The analysis of the current situation is based on reports and statistics from the European Union and the World Bank. An assessment of the sectors of the EU transport sector and the change in their share of participation in trade and economic relations of the EU member states during the COVID-19 pandemic was made. The main directions for overcoming the crisis were offered. [ABSTRACT FROM AUTHOR]

Published
2023
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3. Competitiveness based on logistics and supply chain in medical device industry during the Covid-19 period in Indonesia.

Author

Maemunah, S. and Nekrasov, K.

Subjects
*COVID-19 pandemic, *MEDICAL equipment, *MEDICAL supplies, *SUPPLY chains, *INFORMATION technology, *PERFORMANCE technology
Abstract

This study is about the influence of supply chain business strategy, logistics performance and information technology performance on the competitiveness of the medical device industry. The results obtained are that the supply chain business strategy has a direct effect on logistics performance, information technology performance on the supply chain competitiveness of the medical device industry during the COVID-19 period in Indonesia. Data was obtained by distributing questionnaires to 248 respondents as samples. Analysed the data using a structural equation modelling (SEM) analysis tool. The findings show that business strategy has a positive and significant effect on logistics performance, information technology performance on the competitiveness of medical devices in Indonesia. Based on these findings, to improve and maintain competitiveness are investment, availability, quality of hardware and software infrastructure in information technology, customer satisfaction, good relations with suppliers and reacting quickly and appropriately in all logistics and supply chain activities to excel in front of competitor. Originality is the competitiveness of the supply chain is determined based on the assessment of experts in the supply chain. Further research can be expanded to include indicators such as ROA (return on assets), ROI (return on investment) and market share. [ABSTRACT FROM AUTHOR]

Published
2023
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9. A mechanism of cation diffusion in ThO2 nanocrystal bulk. A molecular dynamic simulation.

Author

Seitov, D. D., Pitskhelaury, S. S., Nekrasov, K. A., Boyarchenkov, A. S., and Kupryazhkin, A. Ya.

Subjects
DYNAMIC simulation, MOLECULAR dynamics, VACANCIES in crystals, FREE surfaces, CATIONS
Abstract

A molecular dynamics simulation of the self-diffusion of thorium cations in ThO2 nanocrystals with a free surface is conducted. It is shown that a vacancy in the bulk of a crystal initiates a complex collective movement of cations, in which the interstitial positions surrounding the vacancy are involved. The diffusion coefficients of cations in the temperature range are calculated. The effective activation energy of diffusion is ED = (7.6 ± 0.7) eV. [ABSTRACT FROM AUTHOR]

Published
2022
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10. IMPACT OF THE PANDEMIC ON THE STRUCTURE OF THE LOGISTIC SUPPLY CHAIN AND TRADE OF THE EUROPEAN UNION

Author

Allahverdiyeva, G. Z. kyzy and Nekrasov, K. V.

Subjects
ЛОГИСТИЧЕСКИЕ ТЕНДЕНЦИИ, ПАНДЕМИЯ, ЕВРОПЕЙСКИЙ СОЮЗ, LOGISTICS TRENDS, ECONOMY, ЭКОНОМИКА, PANDEMIC, EUROPEAN UNION
Abstract

This article focuses on the most relevant topics for the period 2019-2021 - the coronavirus pandemic. The pandemic in this article is the subject of influence on large areas, which are considered in the article-logistics and economics (using the example of the European Union). The importance of logistics as one of the key sectors of the world economy is determined. Attention is paid to the problems of the studied directions and the main development trends. Using available sources of information, the main indicators of industry performance are considered. Their dynamics and rates of change are determined. В данной статье уделяется внимание наиболее актуализированной тематике на период 2019-2021 годов- пандемии коронавируса. Пандемия в данной статье выступает предметом влияния на крупные направления, которые и рассматриваются в статье-логистика и экономика (на примере Европейского союза). Определяется значимость логистики как одного из ключевых секторов мировой экономики. Обращается внимание на проблематику изучаемых направлений и основные тенденции развития. Используя доступные источники информации, рассматриваются основные показатели деятельности отраслей. Определяются их динамика и темпы изменения.

Published
2021

11. Проблемы организации мультимодальных грузоперевозок в период пандемии

Author

Mokina, A. I., Nekrasov, K. V., Мокина, А. И., Некрасов, К. В., Mokina, A. I., Nekrasov, K. V., Мокина, А. И., and Некрасов, К. В.

Abstract

The article presents the trends in the logistics sector in 2020. A comparative analysis of the trade of the Russian Federation with foreign countries based on the results of previous years has been carried out. The concept of multimodal transportation has been investigated. The impact of the Covid-19 coronavirus infection on the work of enterprises was also considered., В статье представлены тенденции логистической сферы в 2020 году. Произведен сравнительный анализ торговли Российской Федерации с зарубежными странами по итогам прошлых лет. Исследовано понятие мультимодальных перевозок. Так же рассмотрено влияние коронавирусной инфекции Covid-19 на работу предприятий.

Published
2021

12. Влияние пандемии на структуру логистической цепи поставок и торговлю Евросоюза

Author

Allahverdiyeva, G. Z. kyzy, Nekrasov, K. V., Аллахвердиева, Г. З. кызы, Некрасов, К. В., Allahverdiyeva, G. Z. kyzy, Nekrasov, K. V., Аллахвердиева, Г. З. кызы, and Некрасов, К. В.

Abstract

This article focuses on the most relevant topics for the period 2019-2021 - the coronavirus pandemic. The pandemic in this article is the subject of influence on large areas, which are considered in the article-logistics and economics (using the example of the European Union). The importance of logistics as one of the key sectors of the world economy is determined. Attention is paid to the problems of the studied directions and the main development trends. Using available sources of information, the main indicators of industry performance are considered. Their dynamics and rates of change are determined., В данной статье уделяется внимание наиболее актуализированной тематике на период 2019-2021 годов- пандемии коронавируса. Пандемия в данной статье выступает предметом влияния на крупные направления, которые и рассматриваются в статье-логистика и экономика (на примере Европейского союза). Определяется значимость логистики как одного из ключевых секторов мировой экономики. Обращается внимание на проблематику изучаемых направлений и основные тенденции развития. Используя доступные источники информации, рассматриваются основные показатели деятельности отраслей. Определяются их динамика и темпы изменения.

Published
2021

13. Diffusion of Oxygen in Hypostoichiometric Uranium Dioxide Nanocrystals. A Molecular Dynamics Simulation

Author

Nekrasov, K. A., Galashev, A. E., Seitov, D. D., Gupta, S. K., Nekrasov, K. A., Galashev, A. E., Seitov, D. D., and Gupta, S. K.

Abstract

A molecular dynamic simulation of diffusion of intrinsic oxygen anions in the bulk of hypostoichiometric UO2-x nanocrystals with a free surface was carried out. The main diffusion mechanism turned out to be the migration of oxygen by the anionic vacancies. It is shown that in the range of values of the non-stoichiometry parameter 0.05 ≤x ≥ 0.275 the oxygen diffusion coefficient D is weakly dependent on temperature, despite the uniform distribution of the vacancies over the model crystallite. The reliable D values calculated for the temperature T = 923 K are in the range from 3∙10-9 to 7∙10-8 cm2/s, in quantitative agreement with the experimental data. The corresponding diffusion activation energy is in the range from 0.57 eV to 0.65 eV, depending on the interaction potentials used for the calculations.

Published
2021

14. Main Factors of the Spatial Development in Promoting and Hindering Agriculture Robotization in Russia

Author

Nabokov, V. I., Skvortsov, E. A., Sharapova, N. V., Ziablitckaia, N. V., Pryadilina, N. K., Nekrasov, K. V., Nabokov, V. I., Skvortsov, E. A., Sharapova, N. V., Ziablitckaia, N. V., Pryadilina, N. K., and Nekrasov, K. V.

Abstract

This research determines the significant differences in the level of robotization of agriculture in Russia. As the processes of robotization of agriculture can be associated with certain socio-economic characteristics of the spatial development of regions, this study aims to analyze the factors of the spatial development of regions that promote and hinder the robotization of agriculture. Having identified and systematized influencing factors makes it possible to reduce the impact of obstacles and intensify the influence of factors contributing to the introduction of robotics. A 2D projection of the characteristics of the expert group (the Phi contingency coefficient) and the results of the expert survey (the Pearson's correlation coefficient) was developed. The most significant factor in the spatial development of regions, which currently hinders the robotization of agriculture, is a share of profitable agricultural organizations in the region. According to the experts, the factors of the spatial development of region, hindering the robotization of agriculture are insufficient volumes of subsidies for the technical renewal of agriculture and investment risks in the region. The most significant factor in the spatial development of regions, contributing to the robotization of agriculture is the availability of a Developed network of servicing for robotics. Considering these factors will make it possible to choose the optimal measures of influence in order to intensify the activity in robotizing the production and rural areas. (C) 2021 INT TRANS J ENG MANAG SCI TECH.

Published
2021

16. BRAF status in сito-morphological diagnosis of thyroid nodules

Author

Tarashchenko, Yu. M., Kovalenko, A. Ye., Ostafiichuk, M. V., and Nekrasov, K. A.

Subjects
хірургічне лікування, мутация BRAF V600E, щитоподібна залоза, endocrine system diseases, тонкоигольная аспирационная пункционная биопсия, papillary thyroid, surgical treatment, BRAF V600E mutation, мутація BRAF V600E, digestive system diseases, тонкоголкова аспіраційна пункційна біопсія, хирургическое лечение, карцинома, fine needle aspiration biopsy, cancer, щитовидная железа, neoplasms
Abstract

The aim of study – to determine the significance of the BRAF V600E mutation presence in the cytomorphological diagnosis of thyroid nodules.Materials and methods. The study included 65 patients requiring surgical treatment for thyroid nodular pathology. Material to determine the BRAF V600E mutation was taken by means of a fine needle aspiration biopsy before surgery. The BRAF V600E mutation was detected by real-time PCR analysis.Results. A pathomorphological study of the removed thyroid nodules showed that all 22 benign nodules were BRAF-negative. Among the 43 papillary thyroid cancer only 20 were BRAF-positive (46.5 %). BRAF mutations were found more often (P < 0.001) in patients with classical and oxyphilic cell papillary thyroid cancer (60 % and 100 %, respectively) than in patients with follicular variant of PTC (6.7 %). Locally invasive tumors were more often BRAF-negative cases (P < 0.05) than non-invasive tumors and amounted to 75.0 % and 37.5 %, respectively. But, when comparing the morphological variant and invasive properties of the tumor, it was found that all cases of the follicular variant of the PC had signs of invasion and were significantly more often observed (P < 0.01) compared with the classical and oxyphilic cell variants. The BRAF V600E mutation was observed both in tumors with metastasis to the regional lymph nodes (55.0 %) and in tumors without metastases (37.5 %), with no significant difference.Conclusions. The presence of the BRAF V600E mutation is a diagnostic marker for papillary thyroid carcinoma, and its detection confirms the presence of malignancy. BRAF positive carcinomas were in 46.5 % of cases. The combination of BRAF-negative and the cytology of groups V and VI by Bethesda may indicate about a follicular variant of PTC. An increase in the number of molecular genetic markers in the preoperative diagnosis of thyroid cancer can significantly improve the quality of diagnosis and surgical treatment., Цель работы – определение значимости наличии мутации BRAF V600E в цитоморфологической диагностике тиреоидных узлов.Материалы и методы. В исследование включены 65 пациентов, нуждающихся в хирургическом лечении по поводу узловой патологии щитовидной железы (ЩЖ). Материал для определения мутации BRAF V600E брали путем тонкоигольной пункционной аспирационной биопсии на дооперационном этапе. Мутацию BRAF V600E определяли путем проведения анализа методом ПЦР в режиме реального времени.Результаты. Окончательное морфологическое исследование удаленных узлов показало отсутствие BRAF-мутаций во всех 22 доброкачественных узлах. Среди 43 папиллярных карцином (ПК) BRAF-положительными были 20 (46,5 %).BRAF-мутации достоверно чаще (p < 0,001) обнаружены у пациентов с классическим и оксифильноклеточным вариантами папиллярной карциномы (60 % и 100 % соответственно) по сравнению с фолликулярным вариантом (6,7 %). При оценке инвазивности опухолей обнаружено, что среди локально инвазивных ПК щитовидной железы достоверно чаще преобладали BRAF-отрицательные случаи (p < 0,05) над неинвазивными ПК (75,0 % и 37,5 % соответственно). В ходе анализа инвазивности опухоли и морфологического варианта установлено, что все случаи фолликулярного варианта ПК имели признаки инвазии, их достоверно чаще отмечали (p < 0,01) по сравнению с классическим и оксифильноклеточным вариантами. Мутация BRAF V600E обнаружена и в опухолях с метастазированием в регионарные лимфатические узлы шеи (55,0 %), и в опухолях без метастазов (37,5 %), без вероятной разницы.Выводы. Наличие мутации гена BRAF V600E – диагностический маркер папиллярной карциномы щитовидной железы, и ее установление подтверждает наличие злокачественности. BRAF-положительные карциномы отмечены в 46,5 % наблюдений. Отсутствие мутации гена BRAF V600E в сочетании с цитологическим заключением V и VI групп по Bethesda может свидетельствовать о наличии фолликулярного варианта ПК. Расширение количества молекулярно-генетических маркеров в дооперационный диагностике рака щитовидной железы может значительно улучшить качество диагностики и хирургического лечения., Мета роботи – визначення значущості наявності мутації BRAF V600E в цитоморфологічній діагностиці тиреоїдних вузлів.Матеріали та методи. У дослідження залучили 65 пацієнтів, які потребували хірургічного лікування з приводу вузлової патології щитоподібної залози (ЩЗ). Матеріал для визначення мутації BRAF V600E брали шляхом тонкоголкової пункційної аспіраційної біопсії на доопераційному етапі. Мутацію BRAF V600E визначали шляхом здійснення аналізу методом ПЛР у режимі реального часу.Результати. Остаточне морфологічне дослідження видалених вузлів показало відсутність BRAF-мутацій у всіх 22 доброякісних вузлах. Серед патогістологічно підтверджених 43 папілярних карцином (ПК) BRAF-позитивними були 20 (46,5 %).Аналізуючи наявність генетичних мутацій залежно від підтипів папілярних карцином ЩЗ, виявили: BRAF-мутації достовірно частіше (p < 0,001) визначали у пацієнтів із класичним та оксифільноклітинним варіантами папілярної карциноми (60 % і 100 % відповідно) порівняно з фолікулярним варіантом папілярної карциноми ЩЗ (6,7 %). Оцінюючи інвазивність пухлин, встановили, що серед локально інвазивних ПК ЩЗ вірогідно частіше переважали BRAF-негативні випадки (p < 0,05) над неінвазивними ПК (75,0 % і 37,5 % відповідно). Під час аналізу інвазивності пухлини залежно від її морфологічного варіанта виявили, що всі випадки фолікулярного варіанта ПК мали ознаки інвазії, їх вірогідно частіше визначали (p < 0,01) порівняно з класичним та оксифільноклітинними варіантами. Мутація BRAF V600E встановлена і в пухлинах із метастазуванням у реґіонарні лімфатичні вузли шиї (55,0 %), і в пухлинах без метастазів (37,5 %) без вірогідної різниці. Висновки. Наявність мутації гена BRAF V600E – діагностичний маркер папілярної карциноми щитоподібної залози, його виявлення підтверджує наявність злоякісності. BRAF-позитивні карциноми виявили в 46,5 % спостережень. Відсутність мутації гена BRAFV600E в поєднанні з цитологічними висновками груп V і VI за Bethesda може свідчити про наявність фолікулярного варіанта ПК. Розширення кількості молекулярно-генетичних маркерів у доопераційній діагностиці раку ЩЗ може значно поліпшити якість діагностики та хірургічного лікування.

Published
2020

17. THE INTERPARTICLE POTENTIALS FOR MOLECULAR DYNAMIC SIMULATION OF THE IMPACT OF COLLISION CASCADES ON GAS BUBBLES IN PLUTONIUM DIOXIDE

Author

Seitov, D. D., Pitskhelaury, S. S., Nekrasov, K. A., Kupryazhkin, A. Ya., and Пицхелаури, С. C.

Abstract

The influence of interaction potentials choice on the molecular dynamics simulation of radiogenic gas bubble resolution under the collision cascades impact in PuO2 crystal is studied. This choice is shown to fundamentally affect the amount of energy transferred to a bubble from the fast particles. Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 19-32-90274.

Published
2020

18. A MOLECULAR DYNAMICS SIMULATION OF URANIUM CARBONITRIDE CRYSTALS USING A MODIFIED EMBEDDED ATOM MODEL METHOD

Author

Pitskhelaury, S. S., Seitov, D. D., Nekrasov, K. A., Gupta, S. K., and Пицхелаури, С. C.

Abstract

A molecular dynamic simulation of uranium carbonitrides is carried out. Parameters and potentials for dynamic variation of particle charges are proposed. The lattice constant, bulk modulus, heat capacity dependences on temperature and the melting points are determined in the framework of the model. Исследование выполнено при финансовой поддержке РФФИ в рамках научного про-екта №16-52-48008 ИНД_оми. С.К. Гупта также благодарит Департамент науки и технологии (Индия) и РФФИ за поддержку по гранту INT/RUS/RFBR/IDIR/P-6/2016.

Published
2020

19. HELIUM DIFFUSION ALONG A RING DISLOCATION IN URANIUM DIOXIDE. A MOLECULAR DYNAMICS SIMULATION

Author

Shekunov, G. S. and Nekrasov, K. A.

Abstract

A simulation of helium migration along a ring dislocation in uranium dioxide is done. Two sets of He interaction potentials are compared, fundamentally differing in the strength of binding of the atom to uranium ions. Helium diffusion coefficients are obtained at temperatures from 375 to 1000 K. Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 16-52-48008 ИНД_оми.

Published
2020

20. The density of robotization of agriculture in Russia and its regions

Author

Nabokov, V. I., Semin, A. N., Pryadilina, N. K., Skvortsov, E. A., Gusev, A. S., Nekrasov, K. V., Nabokov, V. I., Semin, A. N., Pryadilina, N. K., Skvortsov, E. A., Gusev, A. S., and Nekrasov, K. V.

Abstract

According to the Rosstat data a share of agricultural organizations which introduce technological innovations is low (2.7%). The study aims to determine the density of agricultural robotization in Russia and its regions. The density of agricultural robotization is influenced by the average annual number of employees in the industry, which was 5802 thousand people in 2013-2019 and decreased by 22% over the studied period. The data show that 435 units of robotics were introduced in agricultural organizations in the Russian Federation in 2006-2019. The vast majority of robotics used in agriculture in Russia is milking robots mainly by European manufacturers. Robotics is used in the agricultural sector in the Central (185 units), Volga (95 units), NorthWest (66 units) and Ural (68 units) federal districts. The introduction of robotics in agriculture in the Southern, Siberian and North Caucasian federal districts is practically not carried out. The highest density of agricultural robotization is observed in the Kaluga (42.67 robots per 10 thousand employees in the industry), the Ryazan (14.8), the Sverdlovsk (6.32) and the Vologda Region (6.21). The results of the study will allow development of a mechanism that promotes priority robotization of rural areas where robotization is slow or is not carried out to prevent their technological lagging behind and the further development of a stagnation processes. The scientific significance of the research results will contribute to the development of theoretical aspects of robotics application in agriculture and the spatial aspects of robotization. © 2020, World Scientific and Engineering Academy and Society. All rights reserved., The study was funded by RFBR, a project number is 20-010-00636 А «Spatial development of agricultural robotization in Russia: trends, factors, mechanisms»

Published
2020

21. Ab initio calculations of pure and Co+2-doped MgF2 crystals

Author

Usseinov, A. B., Gryaznov, D., Popov, A. I., Kotomin, E. A., Seitov, D., Abuova, F., Nekrasov, K. A., Akilbekov, A. T., Usseinov, A. B., Gryaznov, D., Popov, A. I., Kotomin, E. A., Seitov, D., Abuova, F., Nekrasov, K. A., and Akilbekov, A. T.

Abstract

Ab initio calculations of the atomic, electronic and vibrational structure of a pure and Co+2 doped MgF2 crystals were performed and discussed. We demonstrate that Co+2 (3d7) ions substituting for Mg is in the high spin state. In particular, the role of exact non-local exchange is emphasized for a proper reproduction of not only the band gap but also other MgF2 bulk properties. It allows us for reliable estimate of the dopant energy levels position in the band gap, and its comparison with the experimental data. Thus, the present ab initio calculations and experiment data demonstrate that the Co+2 ground state level lies at ≈2 eV above the valence band top. © 2020 Elsevier B.V.

Published
2020

32. Fuel loading optimization into the active zone of the BN-800 reactor for the purpose of the most balanced distribution of the energy releasing field

Author

Osanova, E. R. and Nekrasov, K. A.

Abstract

During the research, the optimization of fuel loading into the active zone of the BN-800 reactor was conducted using the simplest method by the mass of fissile material without the possibility of installing different types of fuel in one zone. The simulation was carried out in the software-hardware complex GEFEST-800.

Published
2019

33. Ab-initio calculations of CO2 adsorption on nonpolar (100) ZnO surface

Author

Usseinov, A., Akilbekov, A., Dauletbekova, A., Geniyatova, Sh., Soltanbek, N., Nekrasov, K., and Seitov, D.

Subjects
Condensed Matter::Materials Science, Physics::Chemical Physics
Abstract

In this paper, the ab-initio calculations of the CO2 molecule adsorption on the nonpolar ZnO surface were carried out in order to find the equilibrium configuration of the adsorbed molecule, as well as we studied the effect of impurity concentration and the presence of native point defects onto binding energy of molecule. Also, the potential for-mation of a new molecular complex is considered. All results were compared with known experimental data.

Published
2019

34. Molecular Dynamic Simulation of Helium Diffusion in Ring Dislocation in UO2 Nanocrystal.

Author

Shekunov, G. S., Nekrasov, K. A., and Gupta, S. K.

Subjects
*DYNAMIC simulation, *HELIUM atom, *HELIUM, *DIFFUSION, *DIFFUSION processes
Abstract

Molecular dynamic simulation of helium diffusion within a ring dislocation inside stoichiometric UO2 nanocrystal was carried out. During the computational experiments (2.7 ns) in the temperature range from 525 to 1000 K, the dislocation was stable and the helium atom was contained inside the dislocation core. The magnitudes of the diffusion coefficient varied from 4.1·10–6 to 6.6·10–5 cm²/s. The diffusion process could be characterized by the constant activation energy ED = (0.25 ± 0.05) eV. [ABSTRACT FROM AUTHOR]

Published
2019
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35. Energetic Stability and Tuned Electronic Properties of Boron-Doped Carbon Phosphide Monolayer.

Author

Kansara, Shivam, Gupta, Sanjeev K., Sonvane, Yogesh, and Nekrasov, K. A.

Subjects
MONOMOLECULAR films, DENSITY functionals, DYNAMIC stability, CHARGE carrier mobility, ELECTRIC fields, ELECTRONIC equipment
Abstract

We have investigated two-dimensional (2D) monolayer structures composed of p-group binary elements. Here, we have focused on the dynamic stability and bandgap tuning of novel boron (B) doped carbon phosphide (CP) monolayer by implementing external perpendicular electric fields to the layer using ab initio method based on density functionals theory (DFT). First, we have optimized boron doped CP monolayer and analyzed direct band gap 0.65 eV at M-point. With increasing of the applied electric fields for ±0.5 V/Å to ±1.5 V/Å; the bandgap continuously decreases up to metallic nature. The low effective mass is showing the high carrier mobility. The changing to the atomic distance and corresponding charges could be responsible to the semiconductor to metal behavior. This study is relevant for the fabrication of novel electronic and photonic devices. [ABSTRACT FROM AUTHOR]

Published
2019
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36. Electronic Structure of ZnO/CdX (X= S, Se, Te) Core/Shell Nanowires: DFT Study.

Author

Shukla, Rishit S., Gupta, Sanjeev K., Gajjar, P. N., Nekrasov, K. A., and Kupryazhkin, A. Ya.

Subjects
ELECTRONIC structure, NANOWIRE devices, ELECTRONIC band structure, NANOWIRES, FERMI level, VALENCE bands, TELLURIUM
Abstract

A density functional theory (DFT) based computation was conducted to study the electronic band structure, electron density of states (DOS) and partial DOS of ZnO/CdX core/shell nanowires (NWs), where X= S, Se, Te. The band structures calculations show a direct band gap of approximately 1.555 eV, 1.167 eV and 0.833 eV for ZnO/CdS, ZnO/CdSe and ZnO/CdTe, respectively at Γ-point, using generalized gradient approximation (GGA). The TDOS and PDOS calculations predict that a sharp peak is obtained at -9 eV below the Fermi level, in the valence band (VB) due to the possible hybridization between Zn-s, O-p and X-p orbitals. Also, it was observed that the contributions to the total DOS at the conduction band (CB) are mainly dominated by Zn-s and Cd-s orbitals, hinting at possible strong hybridization between them. Also, the low band gaps of ZnO/CdSe and ZnO/CdTe NWs predict the opacity of these NWs at room temperatures while the relatively high band gap of ZnO/CdS NW could suggest their use in fabrication of high operating voltage devices. Our conjecture hint at the applications of these NWs in devices where selective absorbance is a desired characteristic. [ABSTRACT FROM AUTHOR]

Published
2019
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37. The first principles calculations of CO2 adsorption on (101̅0 ) ZnO surface.

Author

Usseinov, A. B., Akilbekov, A. T., Kotomin, E. A., Popov, A. I., Seitov, D. D., Nekrasov, K. A., Giniyatova, Sh. G., and Karipbayev, Zh. T.

Subjects
BINDING energy, SURFACE defects, ADSORPTION (Chemistry), GAS mixtures, CARBON dioxide, ZINC oxide synthesis
Abstract

Atomistic understanding of the interaction between defects and active surface of the sensor is necessary for the developing devices detecting bio-and gas mixtures. We performed first principles computer simulations of the carbon dioxide (CO2) molecule adsorption on a ZnO surface in various configurations and location on the surface. It is shown that the tridentate configuration is the most energetically favorable, the binding energy of the molecule weakly depends on the surface coverage. The presence of intrinsic defects on the surface, such as an oxygen vacancy, leads to a small reduction of the binding energy. The observed data from the NEXAFS experiment and hypothetical formation of a new compound H2CO on the surface are discussed in the light of our calculations. [ABSTRACT FROM AUTHOR]

Published
2019
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38. Sintering of Uranium Dioxide Nanoparticles. A Molecular Dynamics Simulation.

Author

Seitov, D. D., Gracheva, Y. Y., Nekrasov, K. A., Kupryazhkin, A. Ya., Gupta, S. K., and Akilbekov, A. T.

Subjects
MOLECULAR dynamics, URANIUM, SINTERING, DIFFUSION processes, NANOPARTICLES
Abstract

A molecular dynamics simulation of sintering of two octahedral uranium dioxide nanocrystals contacting in the vertex region is carried out. Two main stages of the sintering process are observed. At the beginning of the simulation, the neck between the crystallites is formed due to the mutual attraction of the adjacent (111) faces. Further increase in the neck thickness occurs due to transport of the material from the surface of the crystallites in a much slower diffusion process. The estimate of the activation energy of this process is in the range from 11 to 14 eV. [ABSTRACT FROM AUTHOR]

Published
2019
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39. A Unified Ionic Model for Molecular Dynamics Simulation of UC, U2C3 and UC2 Crystals.

Author

Pitskhelaury, S. S., Borisenko, D. S., Knyazeva, E. N., and Nekrasov, K. A.

Subjects
LATTICE constants, IONIC crystals, CRYSTALS, MOLECULAR models, BULK modulus, THERMAL expansion, MOLECULAR dynamics
Abstract

A technique is proposed for the recovery of pair potentials for the interaction of intrinsic ions in crystals. Using this approach, a unified set of empirical pair interaction potentials for simulation of uranium carbide crystals UnCm in the ionic approximation by the method of molecular dynamics is obtained. The potential parameters are determined from the experimental values of the lattice constant and the UC, U2C3, UC2 bulk compression moduli, as well as the linear expansion coefficient of UC crystal at room temperature. The temperature dependences of the lattice constants and the coefficients of linear expansion of the model uranium carbide nanocrystals are calculated using the suggested potentials. The dependence of the melting temperature of the model nanocrystals on composition is also discussed. [ABSTRACT FROM AUTHOR]

Published
2019
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40. A SIMULATION OF THE CRYSTAL U(C,N) IN THE IONIC APPROXIMATION BY THE METHOD OF MOLECULAR DYNAMICS

Author

Pitskhelaury, S. S., Nekrasov, K. A., Borisenko, D. S., and Knyazeva, E. N.

Abstract

A set of empirical pair interaction potentials for simulation of uranium carbonitride crystals in the ionic approximation by the method of molecular dynamics is suggested. Potential parameters are determined using the experimental values of the lattice constant and the UN and UC bulk compression modulus, as well as the linear expansion coefficient UN crystal. The dependences of the lattice constant, the coefficient of linear expansion, and the heat capacity of nanocrystals U (C, N) are calculated. The melting points of model nanocrystals are obtained also.

Published
2018

41. MOLECULAR DYNAMICS SIMULATION OF KRYPTON DIFFUSION IN UO2 NANOCRYSTALS

Author

Keller, N. V. and Nekrasov, K. A.

Abstract

Within the framework of molecular dynamics, the process of diffusion of single krypton atoms in UO2 nanocrystals was studied. The nanocrystals had a free surface and were isolated in a vacuum. Interstitial migration of atoms was observed, as well as the capture of atoms in the cation sublattice sites. Diffusion coefficients were obtained in the temperature range from 1000 K to 2000 K. The effective activation energy of diffusion was (0.89  0.06) eV. Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта №16-52-48008 ИНД_оми.

Published
2018

42. SIMULATION OF THE PROCESS OF SINTERING OF OXIDE NUCLEAR FUEL NANOCRYSTALLS BY THE METHOD OF MOLECULAR DYNAMICS

Author

Некрасов, К. A., Gracheva, Y. Y., and Nekrasov, K. A.

Abstract

A molecular-dynamic simulation of sintering of (U,Pu)O2 nanocrystals with parallelization of the computations on the graphics processing units of the CUDA architecture was carried out. Based on the temperature dependence of the energy of the system, the dependence of the sintering rate on the mutual orientation of the nanocrystals, the ratio of the cations of uranium and plutonium, and the temperature were obtained. Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта №16-52-48008 ИНД_оми.

Published
2018

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