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Igniting autophagy through the regulation of phase separation

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Signal Transduction and Targeted Therapy 2020年第1期5卷 1911-1912页

作者： Shouheng jin jun Cui MOE Key Laboratory of Gene Function and Regulation State Key Laboratory of BiocontrolSchool of Life SciencesSun Yat-sen University510275 GuangzhouGuangdongChina

A recent paper published in Nature by Fujioka et *** that the Atg1(also known as ULK1 in mammals)complex undergoes phase separation to form a liquid-like biomolecular condensate,thereby promoting the formation of a preautophagosomal structure(PAS)to activate autophagy in yeast.1 This research discovered the details of a mechanism of phase separation underlying autophagy initiation and provided a better understanding of the biological condensates.

关键词： separation phase details

Sediment-copper distributions in hyper-concentrated turbulent solid-liquid system

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Journal of Environmental Sciences 2007年第1期19卷 123-127页

作者： YANG jun NI jin-ren Department of Environmental Engineering Beihang University Beijing 100083 China College of Environmental Sciences Peking University Key Laboratory for Water and Sediment Sciences Ministry of Education Beijing 100871 China

This study presents a special problem on vertical distribution for sediment and copper in hyper-concentrated turbulent solid-liquid system that is essentially different from the ordinary low-concentrated turbulent system. A resonance type turbulent simulation equipment is used for the experimental study in which a vertically uniform turbulent field of the mixture of loess and water is produced in a testing cylinder with a grille stirrer that moves up and down harmoniously with varying vibration frequencies, in order to compare the variations of the vertical profiles of sediment and copper in low- and hyper-concentratod solid-liquid system, different scenarios for input sediment content ranging from 5 to 800 kg/m^3 was considered in the experimental studies. It was found that solids copper content increases with input sediment content, So, and reaches its peak as So goes to 10 kg/m^3 and then decreases rapidly with increasing input sediment content. Such a behavior is possibly resulted from the joint effect of the specific adsorption of copper on loess, precipitation of carbonate and hydroxide of copper due to high carbonate content in the loess and the so-called ＂particulate concentration effect＂ due to the present of the sediment variation in water. The vertical sediment concentration distribution resulted from the uniform turbulence is generally uniform, but slight non-uniformity does occur as sediment concentration exceeds certain value. However, the vertical concentration distributions of soluble copper seem not to be affected much by the variation of sediment concentrations.

关键词： hyper-concentrated system loess copper vertical sediment distribution

Simulation of dual transponder carrier ranging measurements

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第10期10卷 1395-1403页

作者： Xiang-yu ZHA Xiao-jun jin Zhong-he jin Department of lnformation Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

The most dominant error source for microwave ranging is the frequency instability of the oscillator that generates the carrier phase signal. The oscillator noise is very difficult to filter due to its extremely low frequency. A dual transponder carrier ranging method can effectively minimize the oscillator noise by combing the reference phase and the to-and-fro measurement phase from the same single oscillator. This method does not require an accurate time tagging system, since it extracts phases on the same satellite. This paper analyzes the dual transponder carrier ranging system by simulation of the phase measurements with comprehensive error models. Both frequency domain and time domain noise transfer characteristics were simulated to compare them with dual one-way ranging. The simulation results in the two domains conformed to each other and demonstrated that a high level of accuracy can also be achieved by use of the dual transponder carder ranging system, with relatively simple instruments.

关键词： Dual transponder carrier ranging Dual one-way ranging Oscillator noise Transfer characteristic

Microstructures and mechanical properties of titanium-reinforced magnesium matrix composites: Review and perspective

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Journal of Magnesium and Alloys 2022年第9期10卷 2311-2333页

作者： Hong Yang Xianhua Chen Guangsheng Huang Jiangfeng Song Jia She jun tan Kaihong Zheng Yiming jin Bin Jiang Fusheng Pan National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China Southwest Technology and Engineering Research Institute Chongqing 400039China

Currently, many gratifying signs of progress have been made in magnesium(Mg) matrix composites(MMCs) by virtue of their high mechanical properties both at room and elevated temperatures. Although the commonly used reinforcements in MMCs are ceramic particles,they often provide improved yield and ultimate stresses by a significant loss in ductility. Therefore, hard metallic phases were introduced as alternative candidates for the manufacturing of MMCs, especially titanium(Ti). It has a high melting point, high Young’s modulus, high plasticity, low level of mutual solubility with Mg matrix, and closer thermal expansion coefficient to that of Mg metal than that of ceramic particles. It is highly preferable to provide both high ultimate stress and ductility in Mg matrix. However, many critical challenges for the fabrication of Ti-reinforced MMCs remain, such as Ti’s homogeneity, low recovery rate, and the optimization of interfacial bonding strength between Mg and Ti, etc. Meanwhile, different fabrication methods have various effects on the microstructures, mechanical properties, and the interfacial strength of Ti-reinforced MMCs. Hence, this review placed emphasis on the microstructural characteristics and mechanical properties of Ti-reinforced MMCs fabricated by different techniques. The influencing factors that govern the strengthening mechanisms were systematically compared and discussed. Future research trends, key issues, and prospects were also proposed to develop Ti-reinforced MMCs.

关键词： Magnesium matrix composites Ti Microstructures Mechanical properties Fabrication techniques

Facile synthesis of a Ni_(3)S_(2)@C composite using cation exchange resin as an efficient catalyst to improve the kinetic properties of MgH_(2)

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Journal of Magnesium and Alloys 2022年第12期10卷 3628-3640页

作者： Liang Zeng Zhiqiang Lan Baobao Li Huiren Liang Xiaobin Wen Xiantun Huang jun tan Haizhen Liu Wenzheng Zhou jin Guo Guangxi Novel Battery Materials Research Center of Engineering Technology Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related TechnologySchool of Physical Science and TechnologyGuangxi UniversityNanning530004PR China School of Materials Science and Engineering Baise UniversityBaise533000PR China National Engineering Research Center for Magnesium Alloys College of Materials Science and EngineeringChongqing UniversityChongqing400044PR China

Carbon materials have excellent catalytic effects on the hydrogen storage performance of MgH2. Here, carbon-supported Ni3S2(denoted as Ni3S2@C) was synthesized by a facile chemical route using ion exchange resin and nickel acetate tetrahydrate as raw materials and then introduced to improve the hydrogen storage properties of MgH2. The results indicated the addition of 10 wt.% Ni3S2@C prepared by macroporous ion exchange resin can effectively improve the hydrogenation/dehydrogenation kinetic properties of MgH2. At 100 ℃,the dehydrogenated MgH2-Ni3S2@C-4 composite could absorb 5.68 wt.% H2. Additionally, the rehydrogenated MgH2-Ni3S2@C-4 sample could release 6.35 wt.% H2at 275 ℃. The dehydrogenation/hydrogenation enthalpy changes of MgH2-Ni3S2@C-4 were calculated to be 78.5 k J mol-1/-74.7 k J mol-1, i.e., 11.0 k J mol-1/7.3 k J mol-1lower than those of MgH2. The improvement in the kinetic properties of MgH2was ascribed to the multi-phase catalytic action of C, Mg2Ni, and Mg S, which were formed by the reaction between Ni3S2contained in the Ni3S2@C catalyst and Mg during the first hydrogen absorption–desorption process.

关键词： Magnesium Hydrogen storage performance Catalytic effect Carbon-based catalyst

Development of an ultrahard nanotwinned cBN micro tool for cutting hardened steel

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Science China(Technological Sciences) 2016年第6期59卷 876-881页

作者： CHEN jun Yun jin Tian Ye TIAN Yong jun College of Vehicles and Energy Yanshan University College of Mechanical Engineering Yanshan University State Key Laboratory of Metastable Materials Science & Technology Yanshan University

Binderless nanotwinned cubic boron nitride(nt-cBN) synthesized from onion-structured BN precursors under high pressure and high temperature shows a very fine microstructure consisting of densely lamellar nanotwins(average thickness of 4 nm) within nanograins. The unique nanotwinned microstructure offers high hardness, wear resistance, fracture toughness, and thermal stability which are essential for advanced cBN tool materials. Thus, a circular micro tool of nt-cBN was fabricated using femtosecond laser contour machining followed by focused ion beam precision milling. Thereafter turning tests were performed on hardened steel using the studied micro tool. To evaluate the cutting performance, the machined surface quality and subsurface damage of the hardened steel were characterized. The wear mechanism of the nt-cBN micro tool was also investigated. It is found that the fabricated nt-cBN micro tool can generate high quality surface with surface roughness less than 7 nm and nanograin subsurface of about 500 nm deep. In addition, abrasive wear is found to be the dominant wear mechanism of the nt-cBN micro tool in turning hardened steel. These results indicate that nt-cBN has outstanding potential for ultra-precision cutting hardened steel.

关键词： nanotwinned cBN tool fabrication cutting tool micro machining hardened steel

Synchronization of networked multibody systems using fundamental equation of mechanics

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Applied Mathematics and Mechanics(English Edition) 2016年第5期37卷 555-572页

作者： jun LIU jinchen JI jin ZHOU Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai 200072China Department of Mathematics Jining UniversityQufu 273155Shandong ProvinceChina Faculty of Engineering and Information Technology University of Technology SydneyNSW 2007Australia Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai 200072China

From the analytical dynamics point of view, this paper develops an optimal control framework to synchronize networked multibody systems using the fundamental equation of mechanics. A novel robust control law derived from the framework is then used to achieve complete synchronization of networked identical or non-identical multibody systems formulated with Lagrangian dynamics. A distinctive feature of the developed control strategy is the introduction of network structures into the control requirement. The control law consists of two components, the first describing the architecture of the network and the second denoting an active feedback control strategy. A corresponding stability analysis is performed by the algebraic graph theory. A representative network composed of ten identical or non-identical gyroscopes is used as an illustrative example. Numerical simulation of the systems with three kinds of network structures, including global coupling, nearest-neighbour, and small-world networks, is given to demonstrate effectiveness of the proposed control methodology.

关键词： fundamental equation of mechanics analytical dynamics synchronization,networked multibody system gyrodynamics coordinate control

TWO-SCALE FEM FOR ELLIPTIC MIXED BOUNDARY VALUE PROBLEMS WITH SMALL PERIODIC COEFFICIENTS

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Journal of Computational Mathematics 2001年第5期19卷 549-560页

作者： jin-ru Chen jun-zhi Cui School of Mathematics and Computer Sciences Nanjing Normal UniversityNanjing 210097China ICMSEC Academy of Mathematics and Systems SciencesChinese Academy of SciencesBeijing 100080China

Presents a study which proposed a dual approximate expression of the exact solution for mixed boundary value problems of second order elliptic partial differential equation with small periodic coefficients. Dual appro... 详细信息

关键词： two-scale FEM mixed boundary value small periodic coefficients

Third-order elastic, piezoelectric, and dielectric constants

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Applied Mathematics and Mechanics(English Edition) 2019年第12期40卷 1831-1846页

作者： Yanming ZHANG jun jin Hongping HU Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Huazhong University of Science and TechnologyWuhan 430074China

The definitions of the third-order elastic,piezoelectric,and dielectric constants and the properties of the associated tensors are *** on the energy conservation and coordinate transformation,the relations among the third-order constants are ***,the relations among the third-order elastic,piezoelectric,and dielectric constants of the seven crystal systems and isotropic materials are listed in *** third-order constants relations play an important role in solving nonlinear problems of elastic and piezoelectric *** is further found that all third-order piezoelectric constants are 0 for 15 kinds of point groups,while all third-order dielectric constants are 0 for 16 kinds of point groups as well as isotropic *** reason is that some of the point groups are centrally symmetric,and the other point groups are high *** results provide the foundation to measure these constants,to choose material,and to research nonlinear ***,these results are helpful not only for the study of nonlinear elastic and piezoelectric problems,but also for the research on flexoelectric effects and size effects.

关键词： third-order elastic constant third-order piezoelectric constant nonlinear third-order dielectric constant crystal coordinate transformation tensor