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A new design of dual-constituent triangular lattice metamaterial with unbounded thermal expansion

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Acta Mechanica Sinica 2019年第3期35卷 507-517页

作者： Y.c.zhang Y.J.Liang S.T.Liu Y.D.Su State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China New Functional Structural Design and Verification Key Laboratory of Aeronautical Technology Shenyang 110035China

Triangular lattice metamaterials composed of bi-layer curved rib elements (called the Lehman-Lakes lattice) possess unbounded thermal expansion, high stiffness and impossibility of thermal buckling, which are highly desirable in many engineering structural applications subjected to large fluctuations in temperature. However, the requirement of such lattice metamaterial is that it must be a hinged joint in order to achieve the bending deformation upon heating freely, which directly leads to poor manufacturability, especially in small dimensions. In this study, a new design of dual-constituent triangular lattice metamaterial (DTLM) with good manufacturability is proposed to achieve the identical unbounded thermal expansion. In this lattice, a special bi-layer curved rib element where layer one is partially covered by layer two is presented, where the hinge joints are not necessary because the flexural rigidity in the single-layer part is much smaller than that in the bi-layer part, and the desirable thermal bending deformation can be achieved. A sample fabricated by additive manufacturing is given in order to show the good manufacturability;simultaneously, the multifunctional performance of the tailored DTLM with zero, large positive or negative coefficient of thermal expansion (cTE) can remain excellent, as well as the Lehman-Lakes lattice. Examples illustrate that the DTLM with zero cTE has about 34.2% improvement in stiffness and meanwhile has 17% reduction in weight compared with the Lehman-Lakes lattice. The stiffness of the DTLM has a moderate reduction when achieving the same large positive or negative cTE. In addition, the thermomechanical properties of the DTLM are given by the closed-form analytical solution and their effectiveness is verified by the detailed numerical simulation.

关键词： Metamaterial Zero thermal expansion Lattice material Multifunctional design Additive manufacturing

Microstructure and Mechanical Properties of Fe-based Amorphous composite coatings Reinforced by Stainless Steel Powders

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Journal of Materials Science & Technology 2015年第1期31卷 43-47页

作者： H.Zhou c.zhang W.Wang M.Yasir L.Liu School of Materials Science and Engineering State Key Lab for Materials Processing and Die &Mould TechnologyHuazhong University of Science and Technology Huazhong University of Science and Technology Research Institute in Shenzhen

In this study,a few Fe-based amorphous matrix composite coatings reinforced with various portions(4,8 and16 vol.%) of 31 6L stainless steel powders have been successfully produced through high velocity oxy-fuel(HVOF) *** microstructure of the composite coatings was systematically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The main structure of composite coatings remained amorphous while 31 6L stainless steel splats were distributed homogeneously in the amorphous matrix and well connected with surrounding amorphous *** strength of coatings to the substrate was determined by 'pull-off' tensile *** results revealed that the31 6L stainless steel phase effectively improved the bonding strength of amorphous coatings,which is mainly contributed by the strong metallurgical bonding between stainless steel and amorphous *** addition of31 6L stainless steel also enhanced the ductility and fracture resistance of the coatings due to the ductile stainless steel phases,which can arrest crack propagation and increase energy dissipation.

关键词： Thermal spraying Fe-based amorphous coating Stainl

Nanomaterials for environmental burden reduction,waste treatment,and nonpoint source pollution control:a review

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Frontiers of Environmental Science & Engineering 2009年第3期3卷 249-264页

作者： Guobin SHAN Rao Y.SURAMPALLI Rajeshwar D.TYAGI Tian c.zhang INRS-ETE University of QuebecQuebecG1K 9A9Canada U.S.Environmental Protection Agency Kansas CityKS 66117USA civil Engineering University of Nebraska-LincolnOmahaNB 68182USA

Nanomaterials are applicable in the areas of reduction of environmental burden,reduction/treatment of industrial and agricultural wastes,and nonpoint source(NPS)pollution ***,environmental burden reduction involves green process and engineering,emissions control,desulfurization/denitrification of nonrenewable energy sources,and improvement of agriculture and food ***,reduction/treatment of industrial and agricultural wastes involves converting wastes into products,groundwater remediation,adsorption,delaying photocatalysis,and ***,NPS pollution control involves controlling water *** alter physical properties on a nanoscale due to their high specific surface area to volume *** are used as catalysts,adsorbents,membranes,and additives to increase activity and capability due to their high specific surface areas and nano-sized ***,nanomaterials are more effective at treating environmental wastes because they reduce the amount of material needed.

关键词： nanomaterials industrial agricultural nonpoint source pollution environmental burden reduction

NUMERIcAL SIMULATION OF TEMPERATURE FIELD ON FLASH BUTT WELDING FOR HIGH MANGANESE STEELS

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 547-551页

作者： B.D. Yu W.D. Song F. c. zhang china Railway Shanhaiguan Bridge Group Limited company Shanhaiguan 066205 China college of Materials Science and Engineering Yanshan University Qinhuangdao 066004 China

An axial symmetry finite element model coupled with electricity-thermal effect was developed to study the temperature field distribution in process of the flash butt welding （FBW） of frog highmanganese steel. The influence of temperature dependent material properties and the contact resistance were taken into account in FEM ＇simulation. Meanwhile, the lost materials due to .splutter was resolved by using birth and death element. The result of analyzing data shows that the moddel in the FBW flashing is reasonable and feasible, and can exactly simulate the temperature field distribution. The modeling provides reference for analysis of welding technologies on the temperature field of high-manganese steel in FBW.

关键词： flash butt welding (FBW) numerical simulation high manganese steel,temperature field

Towards understanding the mechanisms of proton pumps in complex-I of the respiratory chain

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Biophysics Reports 2019年第Z1期5卷 219-234页

作者： Xuejun c.zhang Bin Li National Laboratory of Biomacromolecules CAS Center for Excellence in Biomacromolecules Institute of Biophysics Chinese Academy of Sciences college of Life Science University of Chinese Academy of Sciences

INTRODUcTION complex-I(i.e., nicotinamide adenine dinucleotide(NADH):ubiquinone(quinone or Q) oxidoreductase) of the respiratory chain is crucial for converting energy from its redox form(i.e., electron transfer) to t...

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Energy coupling mechanism of FO in a rotary ATP synthase:a model update

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Biophysics Reports 2019年第2期5卷 61-64页

作者： Xuejun c.zhang Min Liu National Laboratory of Biomacromolecules CAS Center for Excellence in Biomacromolecules Institute of Biophysics Chinese Academy of Sciences college of Life Science University of Chinese Academy of Sciences

INTRODUcTION In nearly all living cells, rotary ATP synthases of the F1 FOfamily are essential to inter-conversing of energy between the transmembrane electrochemical potential and the ATP form（Boyer 1997）. During ATP synthesis,the FOsector of the ATP synthase machinery converts the electrochemical energy of either protons or sodium ions into mechanical energy of a rotor; in turn, this energy is converted into chemical energy of ATP by the F1sector（Gruber et al. 2014; Nakamoto et al. 2008）.

关键词： Energy coupling Mechanism Proton Wire Unidirectional Rotation Half channel Proton Load

PHASE TRANSFORMATION AND cHARAcTERISTIcS IN FREcKLE AREAS FOR INcONEL 625 SUPERALLOY

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Acta Metallurgica Sinica(English Letters) 2005年第1期18卷 47-54页

作者： J.X.Dong M.c.zhang Y.P.Zeng X.S.Xie UniversityofScienceandTechnologyBeijing Beijing100083China

The freckle formation and their phase characterizatics in freckle areas were investigated by means of microstructure analysis approaches and a thermodynamic equilibrium phase calculation method in an Inconel 625 allay. These results show that in freckle areas a large number of M6c, Mc, Laves and δ phases precipitate in grain boundaries even within grain due to the enrichment and segregation of Mo and Nb during solidification, which results in almost of these freckle areas covered by these complex precipitated phases and induces small grains in freckle areas. Equilibrium phase and liquid segregation calculation can give a reasonable interpretation of the freckle feature for this alloy.

关键词： freckle superalloy Inconel 625 thermodynamic calculation

Structural study of the cdc25 domain from Ral-specific guanine-nucleotide exchange factor RalGPS1a

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Protein & cell 2011年第4期2卷 308-319页

作者： Wei Peng Jiwei Xu Xiaotao Guan Yao Sun Xuejun c.zhang Xuemei Li Zihe Rao National Laboratory of Biomacromolecules Institute of BiophysicsChinese Academy of SciencesBeijing 100101China

The guanine-nucleotide exchange factor(GEF)RalGPS1a activates small GTPase Ral proteins such as RalA and RalB by stimulating the exchange of Ral bound GDP to GTP,thus regulating various downstream cellular ***1a is composed of an Nterminal cdc25-like catalytic domain,followed by a PXXP motif and a c-terminal pleckstrin homology(PH)*** cdc25 domain of RalGPS1a,which shares about 30%sequence identity with other cdc25-domain proteins,is thought to be directly engaged in binding and activating the substrate Ral *** we report the crystal structure of the cdc25 domain of *** bowl shaped structure is homologous to the cdc25 domains of SOS and *** most remarkable difference between these three cdc25 domains lies in their active sites,referred to as the helical hairpin *** with previous enzymological studies,the helical hairpin of RalGPS1a adopts a conformation favorable for substrate binding.A modeled RalGPS1a-RalA complex structure reveals an extensive binding surface similar to that of the SOS-Ras ***,analysis of the electrostatic surface potential suggests an interaction mode between the RalGPS1a active site helical hairpin and the switch 1 region of substrate RalA distinct from that of the SOS-Ras complex.

关键词： RalGPS1a RalA cdc25 domain crystal structure

crystal structures and biochemical studies of human lysophosphatidic acid phosphatase type 6

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Protein & cell 2013年第7期4卷 548-561页

作者： Jun Li Yu Dong Xingru Lü Lu Wang Wei Peng Xuejun c.zhang Zihe Rao National Laboratory of Biomacromolecules Institute of BiophysicsChinese Academy of SciencesBeijing 100101China University of chinese Academy of Sciences Beijing 100049China Structure Biology Laboratory Tsinghua UniversityBeijing 100084China Tianjin Key Laboratory of Protein Science College of Life SciencesNankai UniversityTianjin 300071China

Lysophosphatidic acid(LPA)is an important bioac-tive phospholipid involved in cell signaling through G-protein-coupled receptors *** is also involved in balancing the lipid composition inside the cell,and modulates the function of lipid rafts as an intermediate in phospholipid *** of its involvement in these important processes,LPA degradation needs to be regulated as precisely as its ***-tidic acid phosphatase type 6(AcP6)is an LPA-specifi c acid phosphatase that hydrolyzes LPA to monoacylglyc-erol(MAG)and ***,we report three crystal structures of human AcP6 in complex with malonate,L-(+)-tartrate and tris,*** analyses revealed that AcP6 possesses a highly conserved Rossmann-fold-like body domain as well as a less conserved cap *** vast hydrophobic substrate-binding pocket,which is located between those two domains,is suitable for ac-commodating LPA,and its shape is different from that of other histidine acid phosphatases,a fact that is consistent with the observed difference in substrate *** analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its *** structure also indicates a water-supplying channel for substrate *** structural data are consistent with the fact that the enzyme is active as a *** combination with additional mutagenesis and enzyme activity studies,our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of AcP6.

关键词： lysophosphatidic acid histidine acid phos-phatase crystal structure