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Understanding the mechanisms of friction stir welding based on computer simulation using particles

Defence Technology（防务技术） 2018年第6期14卷 643-656页

作者： A.Yu.Smolin e.v.shilko S.v.Astafurov e.A.Kolubaev G.M.eremina S.G.Psakhie Institute of Strength Physics and Materials Science SB RAS Tomsk634055Russia Tomsk State University Tomsk634050Russia Skolkovo Institute of Science and Technology Skolkovo143025Russia

Friction stir welding(FSW) is a novel technique for joining different materials without melting. In FSW the welded components are joined by stirring the plasticized material of the welded edges with a special rotating pin plunged into the material and moving along the joint line. From the scientific point of view,the key role of the FSW processes belongs to formation of the special plasticized conditions and activation of physical mechanisms of mixing the materials in such conditions to produce the strong homogeneous weld. But it is still a lack of complete understanding of what are these conditions and *** paper is devoted to understanding the mechanisms of material mixing in conditions of FSW based on a computer simulation using particles. The movable cellular automaton method(MCA), which is a representative of the particle methods in mechanics of materials, was used to perform all ***, material flow including material stirring in FSW is simulated using computational fluid mechanics or smoothed particle hydrodynamics, which assume that the material is a continuum and does not take into account the material structure. MCA considers a material as an ensemble of bonded particles. Breaking of inter-particle bonds and formation of new bonds enables simulation of crack nucleation and healing, as well as mass mixing and *** paper consists of two main parts. In the first part, the simulations in 2 D statements are performed to study the dynamics of friction stir welding of duralumin plates and influence of different welding regimes on the features of the material stirring and temperature distribution in the forming welded joints. It is shown that the ratio of the rotational speed to the advancing velocity of the tool has a dramatic effect on the joint quality. A suitable choice of these parameters combined with additional ultrasonic impact could considerably reduce the number of pores and microcracks in the weld without significa

关键词： Friction stir welding Plastic flow Deformation mechanisms Simulation Particle method

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Modeling mechanical behaviors of composites with various ratios of matrixeinclusion properties using movable cellular automaton method

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Defence Technology（防务技术） 2015年第1期11卷 18-34页

作者： A.Yu.SMOLIN e.v.shilko S.v.ASTAFUROv I.S.KONOvALeNKO S.P.BUYAKOvA S.G.PSAKHIe Institute of Strength Physics and Materials Science SB RAS Tomsk State University Institute of High Technology Physics Tomsk Polytechnic University Skolkovo Institute of Science and Technology

Two classes of composite materials are considered: classical metaleceramic composites with reinforcing hard inclusions as well as hard ceramics matrix with soft gel inclusions. Movable cellular automaton method is used for modeling the mechanical behaviors of such different heterogeneous materials. The method is based on particle approach and may be considered as a kind of discrete element method. The main feature of the method is the use of many-body forces of inter-element interaction within the formalism of simply deformable element approximation. It was shown that the strength of reinforcing particles and the width of particle-binder interphase boundaries had determining influence on the service characteristics of metaleceramic composite. In particular, the increasing of strength of carbide inclusions may lead to significant increase in the strength and ultimate strain of composite material. On the example of porous zirconia ceramics it was shown that the change in the mechanical properties of pore surface leads to the corresponding change in effective elastic modulus and strength limit of the ceramic sample. The less is the pore size, the more is this effect. The increase in the elastic properties of pore surface of ceramics may reduce its fracture energy.

关键词： Composites Metal ceramics Zirconia ceramics Gel Modeling Movable cellular automata Many-body interaction

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MicroRNAs as potential diagnostic biomarkers for bipolar disorder

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Neural Regeneration Research 2025年第6期20卷 1681-1695页

作者： Bridget Martinez Philip v.Peplow Department of Pharmacology University of Nevada-RenoRenoNVUSA Department of Medicine University of Nevada-RenoRenoNVUSA Department of Anatomy University of OtagoDunedinNew Zealand

Abnormal expression of microRNAs is connected to brain development and disease and could provide novel biomarkers for the diagnosis and prognosis of bipolar disorder. We performed a PubMed search for microRNA biomarkers in bipolar disorder and found 18 original research articles on studies performed with human patients and published from January 2011 to June 2023. These studies included microRNA profiling in bloodand brain-based materials. From the studies that had validated the preliminary findings,potential candidate biomarkers for bipolar disorder in adults could be miR-140-3p,-30d-5p,-330-5p,-378a-5p,-21-3p,-330-3p,-345-5p in whole blood, miR-19b-3p,-1180-3p,-125a-5p, let-7e-5p in blood plasma, and miR-7-5p,-23b-5p,-142-3p,-221-5p,-370-3p in the blood serum. Two of the studies had investigated the changes in microRNA expression of patients with bipolar disorder receiving treatment. One showed a significant increase in plasma miR-134 compared to baseline after 4 weeks of treatment which included typical antipsychotics, atypical antipsychotics, and benzodiazepines. The other study had assessed the effects of prescribed medications which included neurotransmitter receptorsite binders(drug class B) and sedatives, hypnotics, anticonvulsants, and analgesics(drug class C) on microRNA results. The combined effects of the two drug classes increased the significance of the results for miR-219 and-29c with miR-30e-3p and-526b* acquiring significance. MicroRNAs were tested to see if they could serve as biomarkers of bipolar disorder at different clinical states of mania, depression, and euthymia. One study showed that upregulation in whole blood of miR-9-5p,-29a-3p,-106a-5p,-106b-5p,-107,-125a-3p,-125b-5p and of miR-107,-125a-3p occurred in manic and euthymic patients compared to controls, respectively, and that upregulation of miR-106a-5p,-107 was found for manic compared to euthymic patients. In two other studies using blood plasma,downregulation of miR-134 was observed i

关键词： biomarker bipolar disorder blood leukocytes blood plasma blood plasma extracellular vesicles/exosomes blood serum brain tissue brain tissue extracellular vesicles/exosomes lymphoblastoid cell lines microRNA neural progenitor cells whole blood

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About the Features of Transient to Steady State Deformation of Solids

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Journal of Materials Science & Technology 1997年第1期13卷 69-72页

作者： S. G.Psakhie A. YU.Smolin e. v.shilko S.Yu.Korostelev, A.I.Dmitriev and S. v.Alekseev (Institute of Strength Physics and Materials Science of the Russian Academy of Sciences,Siberian Branch 634055, Tomsk, Russia) Institute of Strength Physics and Materials Science Russian Academy of Sciences Siberian Branch 634055 Tomsk Russian Federation

The features of transient to steady state deformation of solids are theoretically *** of various types of loading was carried out by the Movable Cellular Automata method.A stress state of material at the stage of transient to a steady state is shown to be essentially non-uniform, that may in its turn result in stable structures in velocity field of particles of the material. It may also influence development of deformation at the further stages.

关键词： About the Features of Transient to Steady State Deformation of Solids

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Simulation of the Crashing of Sandwich Structures under Impact Loads by Movable Cellular Automata

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Defence Technology（防务技术） 2005年第1期1卷 10-16页

作者：黄德武黄海宋毅 A I Dmitriev e.v.shilko S G Psakhie Shenyang Ligong University Shenyang Liaoning 110016 China Institute of Strength Physics and Materials Science SB RAS Tomsk 634021 Russia

Movable cellular automata (MCA) method is applied in the analysis of dynamic characters of ceramic armor composite structures under impact loading. As a new approach, MCA is different from the traditional numerical methods such as the finite element method and boundary element method. Based on the theory of particle mechanics, MCA is applied as a powerful tool in solving specific structural analysis of materials loss and penetrating damages. In this paper the method is used to study responses of multi-layered ceramic plates as a base of armor structures under impact loading, thus assisting further investigations in the crashing process and to improve ceramic armor structures.

关键词：运动单元自动控制法陶瓷装甲夹心结构撞击仿真有限元边界元

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Prolonged intermittent theta burst stimulation restores the balance between A_(2A)R-and A_(1)R-mediated adenosine signaling in the 6-hydroxidopamine model of Parkinson's disease

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Neural Regeneration Research 2025年第7期20卷 2053-2067页

作者： Milica Zeljkovic Jovanovic Jelena Stanojevic Ivana Stevanovic Milica Ninkovic Tihomir v.Ilic Nadezda Nedeljkovic Milorad Dragic Laboratory for Neurobiology Department of General Physiology and BiophysicsFaculty of BiologyUniversity of BelgradeBelgradeSerbia Medical Faculty of Military Medical Academy University of DefenceBelgradeSerbia

An imbalance in adenosine-mediated signaling,particularly the increased A_(2A)R-mediated signaling,plays a role in the pathogenesis of Parkinson's *** therapeutic approaches fail to alter disease progression,demonstrating the need for novel approaches in *** transcranial magnetic stimulation is a non-invasive approach that has been shown to improve motor and non-motor symptoms of Parkinson's ***,the underlying mechanisms of the beneficial effects of repetitive transcranial magnetic stimulation remain *** purpose of this study is to investigate the extent to which the beneficial effects of prolonged intermittent theta burst stimulation in the 6-hydroxydopamine model of experimental parkinsonism are based on modulation of adenosine-mediated *** with unilateral 6-hydroxydopamine lesions underwent intermittent theta burst stimulation for 3 weeks and were tested for motor skills using the Rotarod ***,quantitative reverse transcription polymerase chain reaction,immunohistochemistry,and biochemical analysis of components of adenosine-mediated signaling were performed on the synaptosomal fraction of the lesioned caudate *** intermittent theta burst stimulation improved motor symptoms in 6-hydroxydopamine-lesioned animals.A 6-hydroxydopamine lesion resulted in progressive loss of dopaminergic neurons in the caudate *** with intermittent theta burst stimulation began 7 days after the lesion,coinciding with the onset of motor *** treatment with prolonged intermittent theta burst stimulation,complete motor recovery was *** improvement was accompanied by downregulation of the e N/CD73-A_(2A)R pathway and a return to physiological levels of A_(1)R-adenosine deaminase 1 after 3 weeks of intermittent theta burst *** results demonstrated that 6-hydroxydopamine-induced degeneration reduced the expression of A_(1)R and elevated the expression of A_(2A)***

关键词： A_(1)R A_(2A)R adenosine receptors adenosine ecto-5′-nucleotidase intermittent theta burst stimulation non-invasive brain stimulation Parkinson's disease purinergic signalling

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Photoluminescence properties of eu3+-doped MgAl2O4 nanoparticles in various surrounding media

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Journal of Rare earths 2019年第8期37卷 806-811,I0001页

作者： I.e.Kolesnikov e.v.Golyeva e.v.Borisov e.Yu Kolesnikov e.Lahderanta A.v.Kurochkin M.D.Mikhailov St.Petersburg State University St.PetersburgRussia Lappeenranta University of Technology LUT LappeenrantaFinland Peter the Great St.Petersburg Polytechnic University St.PetersburgRussia Scientific and Technological Institute of Optical Material Science VNTs S.I.Vavilov State Optical InstituteSt.PetersburgRussia volga State University of Technology Yoshkar-OlaRussia

eu3+-doped MgAl2O4 nanoparticles were prepared by modified Pechini method.X-ray diffraction analysis shows pure tetragonal spinel phase without any *** average size of synthesized nanoparticles was determined to be about 50-60 nm using scanning electron microscopy and static light scattering *** and excitation spectra as well as lifetimes of MgAl2O4:eu3+ nanophosphors were explored in surrounding media with different refractive *** medium does not affect luminescence bands position,whereas 5D0 lifetime monotonically decreases along with increase of medium refractive *** of surrounding media on radiative and nonradiative decay rates,which were calculated using 4f-4f intensity theory,was studied and *** factor of prepared nanoparticles is defined using both radiative and observed lifetimes.

关键词： eu3+ Nanoparticles Filling factor Luminescence Lifetime Rare earths

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Cross section of the Coulomb excitation of ^(229m)Th by low energy muons

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Chinese Physics C 2021年第9期45卷 143-147页

作者： e.v.Tkalya P.N.Lebedev Physical Institute of the Russian Academy of Sciences 11999153 Leninskiy pr.MoscowRussia National Research Nuclear University MePhI 115409Kashirskoe shosse 31MoscowRussia Nuclear Safety Institute of RAS Bofshaya Tulskaya 52Moscow 115191Russia

The inelastic scattering cross section for muons,μ^(-),with energies e=9-100 ev from the ^(229)Th nuclei is calculated in the framework of the second order of the perturbation theory for quantum *** dominant contribution to the excitation of the low energy isomer ^(229m)Th(3/2^(+),8.19±0.12 ev)originates from the e2 *** excitation cross section reaches the value of 10^(-21) cm^(2) in the range e≈10 *** value is four to five orders of magnitude larger than the electron excitation cross section and is sufficient for the efficient excitation of ^(229m)Th on the muon beam at the next generation of muon colliders.

关键词： cross section muon Coulomb excitation Th-229

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Quantum-dot microlasers based on whispering gallery mode resonators

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Light(Science & Applications) 2021年第5期10卷 785-795页

作者： A.e.Zhukov N.v.Kryzhanovskaya e.l.Moiseev M.v.Maximov Laboratory of quantum optoelectronics National Research University Higher School of EconomicsKantemirovskaya 3ASt.Petersburg 194100Russia Nanophotonics laboratory Alferov UniversityKhlopina 8/3St.Petersburg 194021Russia

The subject of this paper is microlasers with the emission spectra determined by the whispering gallery *** to the total internal reflection of light on the sidewalls,a high Q-factor is achieved until the diameter is comparable to the *** light emission predominantly occurs in the plane of the structure,which facilitates the microlaser integration with other *** focus on microdisk lasers with various types of the In(Ga)As quantum dots(QDs).Deep localization of charge carriers in spatilly separated regions suppresses the lateral diffusion and makes it possible to overcome the undesirable effect of non-adiative recombination in deep ***,using conventional epitaxial structures and relatively simple post-growth processing methods,it is possible to realize small microlasers capable of operating without temperature stabilization at elevated *** low sensitivity of QDs to epitaxial and manufacturing defects allows fabricating microlasers using IIv heterostructures grown on silicon.

关键词： Quantum mode overcome

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Influence of Ti Powder Characteristics on Combustion Synthesis of Porous NiTi Alloy

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Journal of Materials Science & Technology 2002年第3期18卷 248-250页

作者： YonghuaLI v.e.Gunther 等 InstituteofMetalResearch ChineseAcademyofScienceskShenyang110016China ScientificResearchInstituteofMedicalMaterialsandShapeMemoryImplats Tomsk634034Russia

Porous NiTi shape memory alloy (SMA) is a novel biomedical material used for human hard tissue implant. The influence of elemental titanium powder characteristics such as powder morphology, particle size and specific surface area (SSA) on the minimal ignition temperature, combustion temperature and final product of porous NiTi SMA fabricated by combustion synthesis method was investigated in this paper by scanning electron microscopy (SeM) and laser diffraction. The preliminary data indicated that the titanium powder characteristics had a strong effect on combustion synthesis of porous NiTi SMA.

关键词： Porous NiTi shape memory alloy Combustion synthesis Titanium powder characteristics

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