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Microstructure and mechanical properties of Mg-5Li-1Al sheets prepared by accumulative roll bonding

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Journal of Materials Science & Technology 2018年第2期34卷 317-323页

作者： Legan Hou Tianzi Wang Ruizhi Wu Jinghuai Zhang Milin Zhang Anping Dong Baode Sun sergey.betsofen Boris Krit Key Laboratory of superlight Materials &Surface Technology Ministry of Education Harbin Engineering University Harbin 150001 China Suzhou Changfeng Avionics Co. LTD. Suzhou 215151 China Shanghai Key Lab of Advanced High-temperature Materials and Precision Forming Shanghai Jiao Tong University. Shanghai 200240 China Moscow Aviation Institute National Research University Moscow 109383 Russia

Ultrafine-grain and high-strength Mg-SLi-1Al sheets were prepared by accumulative roll bonding （ARB） process. Evolution of microstructure and mechanical properties of ARB-processed Mg-5Li-1Al sheets was investigated. Results show that, during ARB process, the evolution of deformation mechanism oft Mg-5Li-1Al alloy is as follows： twinning deformation, shear deformation, forming macro shear zone, and finally dynamic recrystallization （DRX）. The grain refining mechanism changes from twin DRX to rotation DRX. With the increase in ARB cycles, strength of the Mg-5Li-1Al sheets is enhanced, whilst elongation varies slightly. With the increase in rolling cycles, anisotropy of mechanical properties decreases. It is conclusive that strain hardening and grain refinement dominate the strengthening mechanism of Mg-5Li-1Al alloy.

关键词： Mg-Li alloy Accumulative roll bonding Microstructure Mechanical property

The transformation of LPSO type in Mg-4Y-2Er-2Zn-0.6Zr and its response to the mechanical properties and damping capacities

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Journal of Magnesium and Alloys 2020年第3期8卷 793-798页

作者： Dan Wang Huajie Wu Ruizhi Wu Yang Wang Jinghuai Zhang sergey.betsofen Boris Krit Legan Hou Turahodjayev Nodir Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001PR China Key Laboratory of New Carbon-based Functional and Super-hard Materials of Heilongjiang Province School of Physics and Electronic EngineeringMudanjiang normal universityMudanjiang 157011PR China College of Science Heihe UniversityHeihe 164300PR China Coscow Aviation Institute National Research UniversityMoscow 109383Russia Department of Machine-Building Technology Tashkent State Technical UniversityTashkent 100106Uzbekistan

The transformation of LPSO type in Mg-4Y-2Er-2Zn-0.6Zr during heat treatment and its influence on damping and mechanical properties are reported in this *** to heat treatment,the alloy consisted of a-Mg matrix and lamellar 14H LPSO *** 510℃heat treatment,lamellae shortened,and their content *** 8h heat treatment,block 18R LPSO phases formed at the grain boundaries while 14H LPSO lamellae *** of block 18R LPSO phases improved mechanical and damping properties of the *** corresponding mechanisms of the influence of LPSO type and morphology on mechanical and damping capacities are discussed.

关键词： Heat treatment LPSO phases Mechanical properties Damping capacities

Influence of Voltage on the Corrosion and Wear Resistance of MicroArc Oxidation Coating on Mg-8Li-2Ca Alloy

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Acta Metallurgica Sinica(English Letters) 2019年第2期32卷 194-204页

作者： Bing-Yu Qian Wei Miao Min Qiu Fan Gao Dong-Hui Hu Jian-Feng Sun Rui-Zhi Wu Boris Krit sergey.betsofen College of Material Science and Engineering Heilongjiang University of Science and Technology Key Laboratory of Superlight Materials and Surface Technology Ministry of Education Harbin Engineering University College of Science Heihe University Moscow Aviation Institute National Research University

Calcium phosphate(CaP) coatings were prepared on Mg–8Li–2Ca magnesium alloy by micro-arc oxidation(MAO) in an alkaline Na_3PO_4–Ca[C_3H_7O_6P] base solution at the different applied voltages. Scanning electron microscope and X-ray diffraction were employed to characterize the microstructure and phase composition of the coatings, respectively. The corrosion resistance of the coatings was assessed by potential dynamic polarization curves, electrochemical impedance spectroscopy and hydrogen evolution experiment in simulated body fluids solution. The friction and wear properties were evaluated by friction and wear testing machine. The results demonstrate that the coating surface is porous and mainly composed of MgO, Ca_5(PO_4)_3(OH) and CaH_2P_2O_5. With the increase in voltage, the corrosion resistance and wear resistance of the MAO coating are both enhanced. The corrosion current density of the MAO coating decreases about two orders of the magnitude compared to the substrate. Additionally, wear and corrosion mechanisms are discussed.

关键词： Magnesium alloy Micro-arc oxidation Electrochemical impedance Wear mechanisms

Corrosion behavior of Mg−Li alloys:A review

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Transactions of Nonferrous Metals Society of China 2021年第11期31卷 3228-3254页

作者： Xiao-chun MA Si-yuan JIN Rui-zhi WU Jia-xiu WANG Gui-xiang WANG Boris KRIT sergey.betsofen Key Laboratory of Superlight Materials&Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin 150001China College of Science Heihe UniversityHeihe 164300China Moscow Aviation Institute National Research UniversityMoscow 125993Russia

It has been known that the lack of excellent corrosion resistance is the key problem restricting the wide application of Mg−Li *** on a quantity of literature about corrosion behavior of Mg−Li alloys,this review elaborates the factors affecting the corrosion behavior of Mg−Li alloys and the processing methods for improving corrosion *** corrosion characteristics of Mg−Li alloys are described ***,it is explained that the grain size,orientation,second phase,and surface film strongly influence corrosion performance,which can be tailored by alloying,plastic deformation,and heat *** in-depth discussion about the corrosion mechanisms for Mg−Li alloys was also ***,important points of improving corrosion resistance are suggested.

关键词： Mg−Li alloy corrosion behavior microstructure surface film alloying plastic deformation heat treatment

Radiation of a TM mode from an open end of a three-layer dielectric capillary

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Chinese Physics B 2024年第7期33卷 311-318页

作者： sergey NGalyamin Alexandr MAltmark St.Petersburg State University 7/9Universitetskayanab.St.Petersburg 199034Russia St.Petersburg Electrotechnical University“LETI” 5ProfessoraPopovaSt.Petersburg 197022Russia

Modern trends in beam-driven radiation sources include the interaction of Cherenkov wakefields in open-ended circular waveguides with complicated dielectric linings, with a three-layer dielectric capillary recently proposed to reduce radiation divergence being a representative example [Opt. Lett. 45 5416(2020)]. We present a rigorous approach that allows for an analytical description of the electromagnetic processes that occur when the structure is excited by a single waveguide TM mode. In other words, the corresponding canonical waveguide diffraction problem is solved in a rigorous formulation. This is a continuation of our previous papers which considered simpler cases with a homogeneous or two-layer dielectric filling. Here we use the same analytical approach based on the Wiener–Hopf–Fock technique and deal with the more complicated case of a three-layer dielectric lining. Using the obtained rigorous solution, we discuss the possibility of manipulating the far-field radiation pattern using a third layer made of a low permittivity material.

关键词： diffraction radiation open-ended waveguide Wiener–Hopf technique Cherenkov radiation

Analytical solution of axisymmetric contact problem about indentation of a circular indenter into a soft functionally graded elastic layer

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Acta Mechanica Sinica 2013年第2期29卷 196-201页

作者： sergey Volkov sergey Aizikovich Yue-Sheng Wang Igor Fedotov Research and Education Center "Materials" Don State Technical University South Federal University Research Institute of Mechanics and Applied Mathematics Institute of Engineering Mechanics Beijing Jiaotong University Department of Mathematical Technology Tshwane University of Technology

The paper addresses a contact problem of the theory of elasticity,i.e.,the penetration of a circular indenter with a flat base into a soft functionally graded elastic *** elastic properties of a functionally graded layer arbitrarily vary with depth,and the foundation is assumed to be elastic,yet much harder than a *** analytical solution is constructed,and it is shown that the solutions are asymptotically exact both for large and small values of characteristic dimensionless geometrical parameter of the *** examples are analyzed for the cases of monotonic and nonmonotonic variations of elastic *** results for the case of homogeneous layer are compared with the results for nondeformable foundation.

关键词： Contact problems·Indentation·Functionally graded layer

Updated Kimura-Takemoto classification of atrophic gastritis

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World Journal of Clinical Cases 2021年第13期9卷 3014-3023页

作者： sergey M Kotelevets sergey A Chekh sergey Z Chukov Department of Therapy Medical InstituteNorth Caucasus State Academy for Humanities and TechnologiesCherkessk 369000Russia Department of Software Development Institute of Applied Mathematics and Information TechnologyNorth Caucasus State Academy of Humanities and TechnologiesCherkessk 369000Russia Department of Mathematics Institute of Applied Mathematics and Information TechnologyNorth Caucasus State Academy of Humanities and TechnologiesCherkessk 369000Russia Department of Pathological Anatomy Stavropol State Medical UniversityStavropol 355017Russia

BACKGROUND The Updated Sydney system for visual evaluation of gastric mucosal atrophy viaendoscopic observation is subject to sampling error and interobserver *** Kimura-Takemoto classification system was developed to overcome *** compare the morphological classification of atrophic gastritis between theKimura-Takemoto system and the Updated Sydney *** total of 169 patients with atrophic gastritis were selected according to diagnosisby the visual endoscopic Kimura-Takemoto method. Following the UpdatedKimura-Takemoto classification system, one antrum biopsy and five gastriccorpus biopsies were taken according to the visual stages of the Kimura-Takemoto system. The Updated Kimura-Takemoto classification system was thenapplied to each and showed 165 to have histological mucosal atrophy;theremaining 4 patients had no histological evidence of atrophy in any biopsy. The Updated Kimura-Takemoto classification was verified as a referencemorphological method and applied for the diagnosis of atrophic gastritis. Addingone more biopsy from the antrum to the six biopsies according to the Updated Kimura-Takemoto classification, constitutes the updated combined Kimura-Takemoto classification and Sydney *** sensitivity for degree of mucosal atrophy assessed by the Updated Sydneysystem was 25% for mild, 36% for moderate, and 42% for severe, when comparedwith the Updated Kimura-Takemoto classification of atrophic gastritis formorphological diagnosis. Four types of multifocal atrophic gastritis wereidentified: sequential uniform (type 1;in 28%), sequential non-uniform (type 2;in7%), diffuse uniform (type 3;in 23%), diffuse non-uniform (type 4;in 24%), and"alternating atrophic – non-atrophic" (type 5;in 18%). The pattern of the spread ofatrophy, sequentially from the antrum to the cardiac segment of the stomach,which was described by the Updated Kimura-Takemoto system, washistologically confirmed in 82% of cases ***

关键词： Updated Sydney system Kimura-Takemoto classification Prevention Gastric cancer Atrophic gastritis Morphology

Reactivation of hepatitis B virus infection – an important aspect of multifaceted problem

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World Journal of Gastroenterology 2024年第26期30卷 3193-3197页

作者： sergey Morozov sergey Batskikh Department of Gastroenterology Hepatology and NutritionFederal Research Center of NutritionBiotechnology and Food SafetyMoscow 115446Russia Department of Hepatology Moscow Clinical Scientific Center N.A.A.S.LoginovMoscow 111123Russia

In this editorial we comment on the article published in the recent issue of the W orld Journal of *** focus specifically on the problem of occult hepatitis B virus(HBV)infection,that is a result of previous hepatitis B(PHB)and a source for reactivation of *** prevalence of PHB is underestimated due to the lack of population testing ***,this condition not only com-plicate anticancer treatment,but may be responsible for the development of other diseases,like cancer or autoimmune *** we unveil possible mecha-nisms responsible for realization of these processes and suggest practical approa-ches for diagnosis and treatment.

关键词： Occult hepatitis B virus infection Hepatitis B virus reactivation Previous hepatitis B Cancer Autoimmune disorders

A Note on Transition Kernels for the Most UnfavourableMixed Strategies of the Market

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Journal of the Operations Research Society of China 2024年第1期12卷 35-50页

作者： sergey N.Smirnov Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State UniversityMoscowRussian Federation 119991

We consider a deterministic model of market evolution with trading constraints andapply a game-theoretic approach to the superhedging *** obtain sufﬁcientconditions for the game equilibrium and prove under these conditions the existenceof a Borel-measurable transition kernel describing dependence on price prehistory ofthe most unfavourable mixed strategy of the market.

关键词： Superhedging Guaranteed deterministic approach Optimal mixedstrategies of the market Borel-measurable transition kernel Game equilibrium