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Tribological properties of cobalt-based alloy coating with different cobalt contents by electro-spark deposition

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Rare Metals 2013年第1期32卷 40-46页

作者： qi-Feng jing Ye-Fa Tan Engineering Institute of Engineering Corps PLA University of Science & Technology Unit 78649 of PLA

The cobalt-based alloy coating with different Co contents was deposited on 45 steel by electro-spark deposition with the self-made electrode. The coating has a compact and uniform microstructure with low porosity and no visible microcracks. When Co content increases grad- ually, oxygen content of coating samples 1-5 decreases first and then increases in the range of 2.52 wt%-3.05 wt%; sample 3 has the lowest oxygen content of 2.52 %. Mi- crohardness of the coating is improved remarkably com- pared with the substrate （HV 230.18）. With Co content increasing, microhardness of the coating samples 1-5 first rises slightly and then declines rapidly in the range of HV 580.61-1052.33. Sample 3 gets the maximum of HV 1052.33, which is about 4.6 times that of the substrate. The coating presents excellent wear resistance, which first increases and then decreases when Co content increases. Sample 3 shows the best wear resistance of about 6.4 times that of the substrate. Main wear mechanism of the coating is abrasive wear and fatigue wear, along with oxidation wear under high speed or heavy load conditions.

关键词： Electro-spark deposition Cobalt Content Microstructure Wear resistance Wear mechanism

Late-Time Evolution of the Phantom Scalar Perturbation in the Background of a Spherically Symmetric Static Black Hole

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Chinese Physics Letters 2010年第6期27卷 9-12页

作者： PAN qi-Yuan jing Ji-Liang Institute of Physics and Department of Physics Hunan Normal University Changsha 410081

The late-time evolution of the phantom scalar perturbation is investigated in the spacetime of a four-dimensionai spherically symmetric static black hole. It is revealed that the asymptotic tail of the phantom scalar field is dominated by the growth behavior t-（l＋3/2）eμt, which depends on the multipole moment l and the field moss but is independent of the mass M and charge Q of the black hole. This growth behavior is in strong contrast to the decaying tall of the usual massive scalar perturbation and shows that the external phantom scalar perturbation is unstable in the spherically symmetric static black hole spacetime.

关键词： PHANTOMS (Radiology) SCALAR field theory PERTURBATION (Quantum dynamics) COSMIC background radiation SYMMETRY (Physics) SUPERMASSIVE black holes

CCAAT/enhancer binding proteins play a role in oriLyt-dependent genome replication during MHV-68 de novo infection

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Protein & Cell 2011年第6期2卷 463-469页

作者： jing qi Danyang Gong Hongyu Deng CAS Key Laboratory of Infection and Immunity Institute of BiophysicsChinese Academy of SciencesBeijing 100101China Graduate School of the Chinese Academy of Sciences Beijing 100080China

Murine gammaherpesvirus 68(MHV-68),a member of the gammaherpesvirus family,replicates robustly in permissive cell lines and is able to infect laboratory ***-68 has emerged as a model for studying the basic aspects of viral replication and host–virus interactions of its human *** genome replication is mediated through a cis-element in the viral genome called the origin of lytic replication(oriLyt).A family of transcription factors,CCAAT/enhancer binding proteins(C/EBPs),assists in oriLyt-mediated DNA replication during gammaherpesvirus *** this study,we examined the role of C/EBPs in gammaherpesvirus DNA replication during de novo infection,using MHV-68 as a *** found that C/EBP α and β bind to the CCAAT boxes in the MHV-68 oriLyt core region both in vitro and in vivo,as demonstrated by electrophoretic mobility shift assay and chromatin immunoprecipitation assay.A dominant negative form of C/EBPs significantly impaired the lytic replication efficiency of MHV-68 on both the plasmid and genome levels in a replication assay,indicating that functional C/EBPs are required for maximal MHV-68 genome DNA ***,our data demonstrate that C/EBPs interact with the oriLyt core region and play an important role in MHV-68 lytic DNA replication during de novo infection.

关键词： C/EBPs murine gammaherpesvirus 68 oriLyt lytic replication

Adaptive Distributed Inference for Multi-source Massive Heterogeneous Data

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Acta Mathematica Sinica,English Series 2024年第11期40卷 2751-2770页

作者： Xin YANG qi jing YAN Mi Xia WU School of Mathematics and Statistics Zhengzhou UniversityZhengzhou450001P.R.China School of Mathematics Statistics and MechanicsBeijing University of TechnologyBeijing100124P.R.China

In this paper,we consider the distributed inference for heterogeneous linear models with massive *** that heterogeneity may exist not only in the expectations of the subpopulations,but also in their variances,we propose the heteroscedasticity-adaptive distributed aggregation(HADA)estimation,which is shown to be communication-efficient and asymptotically optimal,regardless of homoscedasticity or ***,a distributed test for parameter heterogeneity across subpopulations is constructed based on the HADA *** finite-sample performance of the proposed methods is evaluated using simulation studies and the NYC flight data.

关键词： Distributed estimation heterogeneity Levene’s test massive heterogeneous data

Interfacial engineering of perfluoroalkyl functionalized covalent organic framework achieved ultra-long cycled and dendrite-free lithium anodes

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Nano Research 2023年第7期16卷 9289-9298页

作者： Yongxin Yang Conghui Zhang Zhiyuan Mei Yongjiang Sun qi An qi jing Genfu Zhao Hong Guo International Joint Research Center for Advanced Energy Materials of Yunnan Province Yunnan Key Laboratory of Carbon Neutrality and Green Low-carbon TechnologiesSchool of Materials and EnergyYunnan UniversityKunming 650091China

The finite lithium-ion utilization,short cycling life,and lower capacity retention caused by irreversible dendrite growth become the maximum dilemma in lithium metal batteries’(LMBs’)***,a perfluoroalkyl-functionalized covalent organic framework(COF-F6)equipped with high stability and supernal proton conduction is introduced as an artificial solid electrolyte interface to stable the lithium metal *** from the strong electron-withdrawing effect of perfluoroalkyl,Li^(+)will be freed more by the competition of electronegative fluorine(F)and bis(trifluoromethanesulphonyl)imide anion(TFSI^(-)).The dissociation of LiTFSI and process of Li^(+)desolvation are easier to *** addition,high electronegative fluorine can also regulate local electron-cloud density to induce the fast immigration of Li^(+).All the above roles contribute to improving the Li^(+)transfer number(0.7)and achieving the goal of inhibiting Li *** a result,the perfluoroalkyl COF-F6 modified LMB presents outstanding cycling *** symmetric batteries accomplish an overlong life-span of more than 5000 h with a lower hysteresis voltage(11 mV)at 5 mA·cm^(-2).Also,no dendrites are observed when using an in-situ optical microscope to learn the process of Li ***,this dendrite-free protection tactic holds broad prospects for the practical application of Li metal anodes.

关键词： perfluoroalkyl-functionalized covalent organic framework(COF-F6) artificial solid electrolyte interface strong electronwithdrawing effect dendrite-free lithium metal anode

A comparative investigation into floatability of bastnaesite with three di/trialkyl phosphate surfactants

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Journal of Rare Earths 2021年第11期39卷 1442-1449,I0005页

作者： Hongli Fan Xianglin Yang jing qi Guangyi Liu jingqin qin College of Chemistry and Chemical Engineering Central South UniversityChangsha 410083China

Flotation separation and recovery of rare earth minerals(REM) have returned to an important position due to the growing strategy demand for rare earth elements(REE).In this paper,a comparative investigation into the floatability of bastnaesite((Ce,La)FCO3) was conducted by using three di/trialkyl phosphate collectors,di(2-ethylhexyl) phosphate(DEHPA),dibutyl phosphate(DBP) and tributyl phosphate(TBP).The density functional theory(DFT) computation recommends that the chemical activity of the three phosphate collectors is in order of DEHPA≥ DBP >> TBP,and their hydrophobization assuggested by the IgP(oil-water partition coefficient) value is in the order of DEHPA> TBP> *** micro-flotation indicates that the preferable pH values for flotation of bastnaesite with the three phosphate collectors are 7.0-8.0,and DEHPA achieves much higher flotation recovery of bastnaesite,followed by DBP,and then TBP,which coincides with their reactivity and hydrophobicity,the two prerequisites for froth *** contact angle,zeta potential,Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS) deduce that DEHPA likely reacts with the Ce(Ⅲ)atoms of bastnaesite interface through its O atom(s) of the P(=O)-O-group to generate the Ce-O-P bonds,and its two 2-ethylhexyl groups orient outside for attaching bubbles,resulting in flotation enrichment of ***,this investigation offers a novel strategy for developing collectors in selective beneficiation of REM.

关键词： di(2-ethylhexyl)phosphoric acid Bastnaesite Flotation Mechanism Activity Rare earths

In-depth understanding of transport behavior of sulfided nano zerovalent iron/reduced graphene oxide@guar gum slurry: Stability and mobility

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Journal of Environmental Sciences 2024年第10期144卷 1-14页

作者： Yuheng Ma Wenhui You Zijiang Yang Zhongyu Ren qi jing Faculty of Architecture Civil and Transportation EngineeringBeijing University of TechnologyBeijing 100124China

Nanoscale zero-valent iron(NZVI),which has the advantages of small particle size,large specific surface area,and high reactivity,is often injected into contaminated aquifers in the form of ***,the prone to passivation and agglomeration as well as poor stability andmobility of NZVI limit the further application of this technology in ***,sulfided NZVI loaded on reduced graphene oxide(S-NZVI/rGO)and guar gum(GG)with shearthinning properties as stabilizers were used to synthesize S-NZVI/rGO@GG ***,TEM,and FT-IR confirmed that the dispersion and anti-passivation of NZVI were optimized in the coupled *** stability and mobility of the slurry were improved by increasing the GG concentration,enhancing the pH,and decreasing the ionic strength and the presence of Ca^(2+)ions,respectively.A modified advection-dispersion equation(ADE)was used to simulate the transport experiments considering the strain and physicochemical deposition/***,colloidal filtration theory(CFT)demonstrated that Brownian motion plays a dominant role in themigration of S-NZVI/rGO@GG slurry,and the maximummigration distance can be increased by appropriately increasing the injection ***-Derjaguin-Landau-Verwey-Overbeek(XDLVO)theory showed that the excellent stability and migration of S-NZVI/rGO@GG slurry mainly came from the GG spatial *** study has important implications for the field injection of S-NZVI/rGO@GG *** to the injection parameters,the injection range of S-NZVI/rGO@GG slurry is effectively controlled,which lays the foundation for the promotion of application in actual fields.

关键词： S-NZVI rGO Guar gum Transport Stability

A Finite Volume Method Based on the Constrained Nonconforming Rotated Q_(1)-Constant Element for the Stokes Problem

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Advances in Applied Mathematics and Mechanics 2012年第1期4卷 46-71页

作者： jing qi Wanfu Tian Yonghai Li Jilin University Changchun 130012China School of Mathematics Jilin UniversityChangchun 130012China School of Science Shenyang Aerospace UniversityShenyang 110136China

We construct a finite volume element method based on the constrained nonconforming rotated Q_(1)-constant element(CNRQ_(1)-P_(0))for the Stokes *** meshes are needed,which are the primal mesh and the dual *** approximate the velocity by CNRQ_(1)elements and the pressure by piecewise *** errors for the velocity in the H^(1)norm and for the pressure in the L^(2)norm are O(h)and the error for the velocity in the L^(2)norm is O(h^(2)).Numerical experiments are presented to support our theoretical results.

关键词： Stokes problem finite volume method constrained nonconforming rotated Q_(1)element

Mixing regime shapes the community assembly process,microbial interaction and proliferation of cyanobacterial species Planktothrix in a stratified lake

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Journal of Environmental Sciences 2022年第5期34卷 103-113页

作者： Junwen Chen Huacong Liu Yaohui Bai jing qi Weixiao qi Huijuan Liu Jianfeng Peng Jiuhui Qu Center for Water and Ecology State Key Joint Laboratory of Environment Simulation and Pollution ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

Lake mixing influences aquatic chemical properties and microbial community composition,and thus,we hypothesized that it would alter microbial community assembly and *** clarify this issue,we explored the community assembly processes and cooccurrence networks in four seasons at two depths(epilimnion and hypolimnion)in a mesotrophic and stratified lake(Chenghai Lake),which formed stratification in the summer and turnover in the *** the stratification period,the epilimnion and hypolimnion went through contrary assembly processes but converged to similar assembly patterns in the mixing *** a highly homogeneous selection environment,species with low niche breadth were filtered,resulting in decreased species *** mixing in the winter homogenized the environment,resulting in a simpler microbial cooccurrence ***,we observed a high abundance of the cyanobacterial genus Planktothrix in the winter,proba-bly due to nutrient redistribution and Planktothrix adaptivity to the winter environment in which mixing played important *** study provides deeper fundamental insights into how environmental factors influence microbial community structure through community assembly processes.

关键词： Stratified lake Water mixing Microbial community assembly Microbial interaction Planktothrix