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Reversible phosphorylation of the 26S proteasome

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Protein & Cell 2017年第4期8卷 255-272页

作者： Xing Guo Xiuliang Huang Mark j. chen The Life Sciences Institute of Zhej.ang University Hangzhou 310058 China Ministry of Education Key Laboratory of Protein Science School of Life Sciences Tsinghua University Beijinq 100084 China Department of Bioinformatics and Computational Biology Genentech Inc. South San Francisco CA 94080 USA

The 26S proteasome at the center of the ubiquitin- proteasome system （UPS） is essential for virtually all cellular processes of eukaryotes. A common miscon- ception about the proteasome is that, once made, it remains as a static and uniform complex with sponta- neous and constitutive activity for protein degradation. Recent discoveries have provided compelling evidence to support the exact opposite insomuch as the 26S proteasome undergoes dynamic and reversible phos- phorylation under a variety of physiopathological con- ditions. In this review, we summarize the history and current understanding of proteasome phosphorylation, and advocate the idea of targeting proteasome kinases/ phosphatases as a new strategy for clinical interven- tions of several human diseases.

关键词： proteasome phosphorylation kinase,phosphatase protein degradation

IMPROVED COHESIVE ZONE MODEL AND ITS APPLICATION IN INTERFACE CONTACT ANALYSIS

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Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 295-302页

作者： Y. Wang j. chen H.B. Li National Die ＆ Mold CAD Engineering Research Center Shanghai Jiaotong University Shanghai 200030China

An improved interface cohesive zone model is developed for the simulation of interface contact, under mixed-mode loading. A new debonding initiation criterion and propagation of debonding law, taking into account the pressure stress influence on contact shear strength, is proposed. The model is implemented in a finite-element program using subroutine VUINTER of ABAQUS Explicit. An edge-notch four-point bending process and laminated vibration damping steel sheet punch forming test are simulated with the improved model in ABAQUS Explicit. The numerical predictions agree satisfactorily with the corresponding experimental results.

关键词： Cohesive zone model Mixed mode Damage criterion Contact stress

Effects of thermal boundary conditions on the j.ule heating of electrolyte in a microchannel

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j.urnal of Hydrodynamics 2016年第5期28卷 850-862页

作者： M. Y. ABDOLLAHZADEH j.MALABADI j. H. PARK M. M. RASHIDI j. M. chen Department of Ship Engineering Chabahar Maritime University Chabahar Iran Department of Aerospace and System Engineering Gyeongsang National University Jinju Korea . Engineering Faculty of Bu-Ali Sina University Hamedan Iran Department of Mechanical and Nuclear Engineering Kansas State University Manhattan USA

j.ule heating effects on a slit microcharmel filled with electrolytes are comprehensively investigated with emphasis on the thermal boundary conditions. An accurate analytical expression is proposed for the electrical field and the temperature distributions due to j.ule heating are numerically obtained from the energy balance equation. The results show that a thermal design based on the average electric potential difference between electrodes can cause severe underestimation of j.ule heating. In addition, the parame- tric study of thermal boundary conditions gives us an insight into the best cooling scenario for microfluidic devices. Other significant thermal characteristics, including Nusselt number, thermophoretic force, and entropy generation, are discussed as well. This study will provide useful information for the optimization of a bioMEMS device in relation to the thermal aspect.

关键词： microchannel electrolyte j.ule heating Nusselt number thermophoretic force entropy generation optimized thermaldesign

Evolution of deformation twins with strain rate in a mediummanganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V

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j.urnal of Iron and Steel Research International 2019年第9期26卷 983-990页

作者： j. chen j.j.Wang H.Zhang W.G.Zhang C.M.Liu Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819LiaoningChina School of Materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina Baosteel Special Steel Co. Ltd.Shanghai 200940China Northeastern Institute of Metal Materials Co. Ltd.Shenyang 110108LiaoningChina

Microstructure evolutions of the medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V (in wt.%) with stacking-fault energy of 22 mj.m-2 during deformation at strain rate ranging of 10^-2-1 s^-1 were analyzed by means of X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicate that the twinning-induced plasticity effect is the main strengthening mechanism of the studied steel, whilst the transformation-induced plasticity effect only occurs at high strain rate. With an increase in strain rate, volume fraction of the deformation twins, in particular that of the secondary twins, increases significantly along with decreasing average size. When applied strain rate is higher than 10^-1 s^-1, the parallel deformation twins are turned into a crossing morphology, and the original straight twin boundaries exhibit a ladder feature, which is attributed to the interactions between regular dislocations and twin dislocations at the twin boundary. The critical strain, a key indicator of the initiation of deformation twin, decreases with increasing strain rate. In addition, the ductility and strength of medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V are mainly determined by the shape and volume fraction of deformation twins.

关键词： Medium-manganese wear-resistant steel Stacking fault Twinning-induced plasticity effect Secondary twin Strain hardening rate

ANALYSIS OF THREE-DIMENSIONAL UPSETTING PROCESS BY THE RIGID-PLASTIC REPRODUCING KERNEL PARTICLE METHOD

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 371-378页

作者： Y. H. Liu j. chen S. Yu X. W. chen National Die and Mould CAD Engineering Research Center Shanghai Jiao Tong UniversityShanghai 200030 China

A meshless approach, called the rigid-plastic reproducing kernel particle method （RKPM）, is presented for three-dimensional （3D） bulk metal forming simulation. The approach is a combination of RKPM with the flow theory of 3D rigid-plastic mechanics. For the treatments of essential boundary conditions and incompressibility constraint, the boundary singular kernel method and the modified penalty method are utilized, respectively. The arc-tangential friction model is employed to treat the contact conditions. The compression of rectangular blocks, a typical 3D upsetting operation, is analyzed for different friction conditions and the numerical results are compared with those obtained using commercial rigid-plastic FEM （finite element method） software Deform^3D. As results show, when handling 3D plastic deformations, the proposed approach eliminates the need of expensive meshing and remeshing procedures which are unavoidable in conventional FEM and can provide results that are in good agreement with finite element predictions.

关键词： meshless reproducing kernel particle method(RKPM) three-dimensional upsetting incompressibility modified penalty method

STUDY ON THE NUMERICAL SIMULATION OF MULTI-STAGE ROTARY FORGING OF A NON-AXISYMMETRIC PART AND THE CAE ANALYSIS OF THE DIE STRENGTH

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Acta Metallurgica Sinica(English Letters) 2005年第5期18卷 627-634页

作者： H. Tian j. Wang W.P. Dong j. chen Z. Zhao G.M. Wu National Die ＆ Mold CAD Engineering Research Center Shanghai Jiaotong UniversityShanghai 200030 China

Traditionally a rotary forging process is a kind of metal forming method where a conic upper die, whose axis is deviated an angle from the axis of machine, forges a billet continuously and partially to finish the whole deformation. For the rotary forging process simulation, more researches were focused on simulating the simple stage forming process with axisymmetric part geometry. Whereas in this paper, the upper die is not cone-shaped, and the billet is non-axisymmetric. So the movement of the punch is much more complicated than ever. The 3D FEM simulation models for the preforming ＆ final forming processes are set up aider carefully studying the complicated movement pattern. Deform-3D is used to simulate the material flow, and the boundary nodal resisting forces calculated by the final stage process simulation is used to analyze the final forming die strength. The CAE analysis of the die shows that the design of the final forming die is not reasonable with lower pre-stress which is easy to crack at the critical corners. An optimum die design is also provided with higher pre-stress, and verified by CAE analysis.

关键词： numerical simulation non-axisymmetric rotary forging die strength

Ultrafast solid-liquid-vapor irradiated by femtosecond phase change of a thin gold fi laser pulses and pulse trains

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Frontiers in Energy 2012年第1期6卷 1-11页

作者： j.ng HUANG Yuwen ZHANG j. K. chen Mo YANG Department of Mechanical and Aerospace Engineering University of Missouri Columbia MO 65211 USA College of Energy and Power Engineering University of Shanghai forScience and Technology Shanghai 200093 China

Effects of different parameters on the melting, vaporization and resolidification processes of thin gold film irradiated by femtosecond pulses and pulse train were systematically studied. The classical two-temperature model was adopted to depict the non-equilibrium heat transfer in electrons and lattice, the melting and resolidification processes, which was~ characterized by the solid-liquid interfacial velocity, as well as elevated melting temperature and depressed solidifcation tempera- ture, was obtained by considering the interfacial energy balance and nucleation dynamics. Vaporization process which leads to ablation was described by tracking the location of liquid-vapor interface with an iterative procedure based on energy balance and gas kinetics law. The parameters in discussion included film thickness, laser fluence, pulse duration, pulse number, repetition rate, pulse train number, etc. Their effects on the maximum lattice temperature, melting depth and ablation depth were discussed based on the simulation results.

关键词： melting evaporation nucleation dynamics,nanoscale heat transfer

Multistage serrated flow behavior of a medium-manganese high-carbon steel

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j.urnal of Iron and Steel Research International 2020年第9期27卷 1064-1072页

作者： j.chen Y.Zhang j.j.Wang C.M.Liu S.X.Zhao Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819LiaoningChina Shenyang Industrial Transformation Upgrading Promotion Center Shenyang 110083LiaoningChina The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina School of Materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina Central Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999China

The deformation mechanisms and the flow stress behavior of a medium-manganese high-carbon steel during cold deformation at a strain rate of 10×5 s^-1 were explored using a universal testing machine,an X-ray diffractometer,a field emission scanning electron microscope and a high-resolution transmission electron *** results show that continuous step-up serrated flow behavior appears after the yielding point,and the true stress-strain curve is roughly divided into five stages based on distinctive densities and amplitudes of *** strengthening mechanisms of the experimental steel involve Cottrell atmosphere,twinning-induced plasticity(TWIP)efect and transformation-induced plasticity(TRIP)*** effect is the dominant deformation mechanism,and deformation twins formed by TWIP effect comprise primary,secondary and ***,TRIP effect arises in the local high-strain *** element plays a key role in the transformation of the deformation mechanism.A small amount of carbide precipitates around twin boundaries lead to the formation of local carbon-poor regions,and Md temperature and stacking fault energy of medium-manganese high-carbon steel are propitious to the occurrence of TRIP *** addition,the contributions of various deformation mechanisms to plasticity are calculated,and that of TWIP effect is the greatest.

关键词： Serrated flow Deformation mechanism Deformation twin Twinning-induced plasticity Transformation-induced plasticity

Interfacial bonding mechanism in Al/coated steel dissimilar refill friction stir spot welds

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j.urnal of Materials Science & Technology 2019年第6期35卷 1027-1038页

作者： Z. Shen Y. Ding j. chen B. Shalch Amirkhiz j.Z. Wen L. Fu A.P. Gerlich School of Materials Science and Engineering Northwestern Poly technical University Xi'an 710072 China Shanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi'an 710072 China State Key Laboratory of Solidification Processing Northwestern Poly technical University Xi'an 710072 China Centre of Advance Materials j.ining Department of Mechanical and Mechatronics Engineering University of Waterloo 200 University Ave. Waterloo N2L3G1 Ontario Canada CanmetMATERIALS Natural Resources Canada Hamilton L8P 0A5 Canada

Defect-free dissimilar Al/zinc coated steel and Al/AlSi coated steel welds were successfully fabricated by refill friction stir spot welding. However, Al alloy and uncoated steel could not be welded under the same welding condition. Al-Zn eutectic layer formed at the Al/zinc coated steel interface showed nonuniformity in thickness and nanoscale intermetallic(IMC) produced was discontinuous. The bonding formation between the Al-Zn layer and the surrounding materials was attributed to a liquid/solid reaction mechanism. Bonding formation at Al alloy and AlSi coated steel interface was attributed to a solid/solid reaction mechanism, as the j.ining process did not involve with melting of base metals or AlSi coating materials. Kissing bond formed at the weld boundary acted as a crack initiation and propagation site,and the present study showed that weld strength of Al 5754/AlSi coated steel was greatly influenced by properties of original IMC layer.

关键词： Refill friction stir spot welding Al alloy Steel Coated materials j.ining mechanism