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Archaea, the tree of life, and cellular evolution in eukaryotes

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science China Earth sciences 2019年第3期62卷 489-506页

作者： Jing XIAO Lu FAN Dingfeng WU Yanbing XU Dengxun LAI William F.MARTIN Ruixin ZHU Chuanlun ZHANG Department of Bioinformatics Tongji University Shenzhen Key Laboratory of marine Archaea Geo-Omics Department of Ocean Science and Engineering Southern University of Science and Technology SUSTech Academy for Advanced Interdisciplinary Studies Southern University of Science and Technology Institute of Molecular Evolution Heinrich-Heine-University Universit?tsstr.1 Laboratory for marine Geology Qingdao National Laboratory for Marine Science and Technology

The early history of life harbours many unresolved evolutionary questions, none more important than the genomic origin and cellular evolution of eukaryotes. An issue central to eukaryote origin concerns the position of eukaryotes in the tree of life and the relationship of the host lineage that acquired the mitochondrion some two billion years ago to lineages of modern-day archaea. Recent analyses indicate that the host lineage branches within the Archaea, prompting the search for novel archaeal lineages that can improve our understanding of the cellular evolution of eukaryotes. Here we give a brief review of the studies on Archaea, the tree of life and the cellular evolution of eukaryotes, which is followed by an overview of recent progress fueled by new genomic technologies and recent status of archaeal research in China. Future directions for the study of early evolution are considered.

关键词： Archaea Tree of life Cellular evolution of eukaryotes Metagenomics Bioinformatics

Effect of trace HA on microstructure, mechanical properties and corrosion behavior of Mg-2Zn-0.5Sr alloy

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Journal of Materials science & Technology 2018年第2期34卷 299-310页

作者： Jian-Xing Li Yuan Zhang Jing-Yuan Li Jian-Xin Xie school of Materials science and engineering University of Science and Technology Beijing Institute for Advanced Materials and Technology University of Science and Technology Beijing

Effect of the addition of trace HA particles into Mg-2Zn-0.5Sr on microstructure, mechanical properties, and bio-corrosion behavior was investigated in comparison with pure Mg. Microstructures of the Mg-2Zn-0.5Sr-xHA composites （x= 0, 0.1 and 0.3 wt%） were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） equipped with energy dispersion spectroscopy （EDS） and X-ray diffraction （XRD）. Results of tensile tests at room temperature show that yield strength （YS） of Mg- 2Zn-0.5Sr/HA composites increases significantly, but the ultimate tensile strength （UTS） and elongation decrease with the addition of HA particles from 0 up to 0.3 wt%. Bio-corrosion behavior was investigated by immersion tests and electrochemical tests. Electrochemical tests show that corrosion potential （Ecorr） of Mg-2Zn-0.5Sr/HA composites significantly shifts toward nobler direction from -1724 to -1660 mVscE and the corrosion current density decreases from 479.8 to 280.8 ***^-2 with the addition of HA particles. Immersion tests show that average corrosion rate of ***/HA composites decreases from 11.7 to 9.1 mm/year with the addition of HA particles from 0 wt% up to 0.3 wt%. Both microstructure and mechanical properties can be attributed to grain refinement and mechanical bonding of HA particles with second phases and α-Mg matrix. Bio-corrosion behavior can be attributed to grain refinement and the formation of a stable and dense CaHPO4 protective film due to the adsorption of Ca^2＋ on HA particles. Our analysis shows that the Mg-2Zn-0.5Sr/0.3HA with good strength and corrosion resistance can be a good material candidate for biomedical applications.

关键词： Magnesium alloys Bio-composites Hydroxyapatite Microstructure Mechanical property Bio-corrosion behavior

Characteristics of Mechanical Properties and Microstructure for 316L Austenitic Stainless Steel

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Journal of Iron and Steel Research International 2011年第11期18卷 53-59页

作者： SONG Ren-bo XIANG Jian-ying HOU Dong-po school of Materials science and engineering University of Science and Technology Beijing Beijing 100083 China

A comparative study on mechanical properties and microstructure of 316L austenitic stainless steel between solution treated specimen and hot rolled specimen was conducted. After a specimen was subjected to solution treatment at 1 050 ℃ for 6 min, its mechanical properties were determined through tensile and hardness tests. Based on the true stress vs true strain and engineering stress vs engineering strain flow curves, the work hardening rate has been explored. The results show that the solution treated specimen has an excellent combination of strength and elongation, and that this steel is easy to work-hardening during deformation. Optical microscope, scanning electron micro- scope, transmission electron microscope and X-ray diffraction examinations were conducted, these reveal that twins in 316L austenitic stainless steel can be divided into suspended twin and transgranular twin which have different for mation mechanisms in growth, and that the deformation induced martensite nucleated and grown in the shear band intersections can be observed, and that the fracture surfaces are mainly composed of dimples and exhibit a tough fracture character.

关键词： 316L mechanical property twin martensite fracture morphology

Resonance properties of THz plasmonic dipole-bowtie antenna array: The critical role of the substrate

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Chinese Physics B 2014年第12期23卷 568-572页

作者：杨玉平 Ranjan Singh 张伟力 school of science Minzu University of China school of Electrical and Computer engineering Oklahoma State University

Subwavelength arrays of dipole-bowtie antennas are designed and characterized using terahertz time-domain spectroscopy（THz-TDS） and finite element method（FEM） simulations. Two different substrates, silicon and mylar with an order of magnitude difference between their thickness values are used to study the resonance properties of the *** 640-μm thick silicon substrate supports a sharper fundamental mode resonance. We discover that higher-order Fabry–Perot resonances can be excited only in 24-μm thin mylar substrates and show much higher sensitivity to dielectric changes in the environment and the geometrical parameters of the antennas than the fundamental dipole resonance.

关键词： THz-TDS dipole-bowtie antennas plasmonic resonator

Optimization design of resistance spot welding parameters of magnesium alloy

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China Welding 2008年第1期17卷 49-56页

作者：郎波孙大千吴琼宣兆志 school of Materials science and engineering Jilin University

By means of the quadratic regression combination design process, the regression equations of nugget diameter and tensile shear load of spot welded joint were established. Effects of welding parameters on the nugget diameter and the tensile shear load were investigated. The results show that effect of welding current on nugget diameter is the most evident. And higher welding current will result in bigger nugget diameter. Besides, interaction effect of electrode force and welding current on tensile shear load is the most evident compared with others. The optimum welding parameters corresponding to the maximum of tensile shear load have been obtained by programming using Matlab software, which is 4, 7 kN electrode force, 28 kA welding current and 4 cycle welding time. Under the condition of the optimum welding parameters, the joint having no visible defects can be obtained, nugget diameter and tensile shear load being 6. 8 mm and 3 256 N, respectively.

关键词： resistance spot welding magnesium alloy quadratic regression combination design welding parameter

Effects of Si alloying and T6 treatment on mechanical properties and wear resistance of ZA27 alloys

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China Foundry 2016年第2期13卷 93-100页

作者： Rui Zhang Guang-lei Liu Nai-chao Si Yu-yang Peng Hao Wan Ting Liu school of Materials science and engineering Jiangsu University

To improve the mechanical properties and wear resistance of ZA27 alloy, Si was introduced to the alloy, and the effect of Si alloying and T6 heat treatment on the microstructure, mechanical properties and wear resistance was investigated. The results show that with 0.55% Si, the microstructure of the alloy can be refined effectively, which leads to the increase of hardness. But the tensile strength and elongation decrease because Si undermines the integrity of the matrix. On the other hand, the dendrites are transformed into a desired α+η+(α+η)mixture with T6 heat treatment, which introduces a remarkable increase to the elongation and hardness of the alloy. The wear resistance of the ZA27 alloy with Si alloying is significantly better than that of the ZA27 alloy without Si. With the increase of Si addition, the wear resistance of the alloy firstly increases and then *** the alloy without Si alloying, severe plastic deformation and large delamination were observed on the worn surface of the alloy. However, with the increase of Si, the main wear mechanism transformed to abrasive wear gradually. In addition, the T6 treatment can further improve the wear resistance of the alloy with Si alloying.

关键词： ZA27 alloy Si alloying mechanical properties wear resistance

An approach to error elimination for multi-axis CNC machining and robot manipulation

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science China(Technological sciences) 2007年第5期50卷 560-574页

作者： XIONG CaiHua school of Mechanical science and engineering Huazhong University of Science and Technology Wuhan 430074 China

The geometrical accuracy of a machined feature on a workpiece during machining processes is mainly affected by the kinematic chain errors of multi-axis CNC ma- chines and robots, locating precision of fixtures, and datum errors on the work- piece. It is necessary to find a way to minimize the feature errors on the workpiece. In this paper, the kinematic chain errors are transformed into the displacements of the workpiece. The relationship between the kinematic chain errors and the dis- placements of the position and orientation of the workpiece is developed. A map- ping model between the displacements of workpieces and the datum errors, and adjustments of fixtures is established. The suitable sets of unit basis twists for each of the commonly encountered types of feature and the corresponding locating di- rections are analyzed, and an error elimination (EE) method of the machined feature is formulated. A case study is given to verify the EE method.

关键词： error elimination, multi-axis machine, robot manipulation, kinematic chain, twist

Preparation and Properties of Guiqi Polysaccharides/Chitosan/Alginate Composite Hydrogel Microspheres

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Journal of Renewable Materials 2019年第12期7卷 1321-1332页

作者： Xiaoliang Zhao Yuting Wang Xiuying Pu Jianzhong Ma Feifan Leng Yonggang Wang Yanling Wang Shuhong Yang Fen Ran Weijie Zhang school of Life science and engineering Lanzhou University of TechnologyLanzhou730050China school of Material science and engineering Lanzhou University of TechnologyLanzhou730050China

A series of the Guiqi polysaccharides/chitosan/alginate composite hydrogel microspheres(GPcM)with different particle sizes were prepared with Guiqi polysaccharides(GP),chitosan(CS)and sodium alginate(Alg).The optimum preparation process was also determined by single factor and orthogonal experiment *** GPcM were characterized by fourier transform infrared spectroscopy(FT-IR),scanning electron microscope(SEM),drug loading efficiency test(LE),encapsulation efficiency test(EE)and in vitro release *** results showed that the Guiqi polysaccharides chitosan hydrogel(GPCH)and sodium alginate hydrogel(SAH)formed a crossover system in *** GPcM have a uniform particle size ranging from 395.1μm to 841.5μ*** drug loading efficiency and encapsulation efficiency of the GPcM were 56.3%and 72.6%,*** bovine serum albumin(BSA)loaded in the GPcM released slowly within 180 *** results suggested that the GPcM may have potential application value in drug sustained and controlled release system.

关键词： Guiqi polysaccharides composite hydrogel microspheres cross-linker drug loading

TiO2/g-C3N4 heterojunctions： In situ fabrication mechanism and enhanced photocatalytic activity

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Frontiers of Materials science 2016年第3期10卷 310-319页

作者： Li-Cheng WU Hang ZHAO Li-Guo JIN Huan-Yan XU school of Materials science and engineering Harbin University of Science and Technology Harbin 150040 China

In situ fabrication of TiO21g-C3N4 （TCN） heterojunctions was achieved by a modified sol-gel method. TG analysis was employed to determine the content of Ti02 in TCN composites. XRD, FTIR, TEM and HRTEM were used to analyze the phase composition, functional groups, morphology and microstructure of as-obtained pro- ducts, respectively. Based on the measurement of surface Zeta potential of g-C3N4, a possible mechanism on in situ fabrication of TCN heterojunctions was concluded. The control experiments indicated that TCN heterojunctlons exhibited better photocatalytic performance than either Ti02 or g-C3N4, suggesting that the enchanced photocatalytic activity could be realized by TCN heterojunctionso Then, the evaluation of parameters affecting the photocatalytic performance of TCN heterojunctions was investigated. Even after five cycles, TCN heterojunctions still maintained high photocatalytic activity, exhibiting the good photocatalytic stability. UV-vis absorption spectra showed that almost all MB molecules were decomposed in the photocatalytic process. Finally, the possible mechanism on enhanced photocatalytic performance of TCN heterojunctions was discussed.

关键词： TiO2 g-C3N4 heterojuncUons photocatalytic mechanism