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Bacterial diversity in soils around a lead and zinc mine

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Journal of Environmental Sciences 2007年第1期19卷 74-79页

作者： HU Qing QI Hong-yan zeng jing-hai ZHANG Hong-xun Department of Environmental Biotechnology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Five samples of soil collected from a lead and zinc mine were used to assess the effect of combined contamination of heavy metals on soil bacterial communities using a polyphasic approach including characterization of isolates by culture method, community level catabolic profiling in BIOLOG GN microplates, and genetic community fingerprinting by denaturing gradient gel electrophoresis of 16S rDNA fragments amplified by PCR from community DNA （PCR-DGGE）. The structure of the bacterial community was affected to a certain extent by heavy metals. The PCR-DGGE analysis of 16S rRNA genes showed that there were significant differences in the structure of the microbial community among the soil samples, which were related to the contamination levels. The number of bacteria and the number of denaturing gradient gel electrophoresis （DGGE） bands in the soils increased with increasing distance from the lead and zinc mine tailing, whereas the concentration of lead （Pb） and cadmium （Cd） was decreased. Heavily polluted soils could be characterized by a community that differs from those of lightly polluted soils in richness and structure of dominating bacterial populations. The clustering analysis of the DGGE profiles showed that the bacteria in all the five samples of soil belonged to three clusters. The data from the BIOLOG analysis also showed the same result. This study showed that heavy metal contamination decreased both the biomass and diversity of the bacterial community in soil.

关键词： BIOLOG system DGGE heavy metal microbial diversity soils

Financing Constraints and the Mode of Outward Foreign Direct Investment:Cross-Border Mergers and Acquisitions or Greenfield Investment

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China Finance and Economic Review 2020年第4期9卷 46-66页

作者： Guanhong Jiang jing zeng Department of International Economics and Business Xiamen University Shanghai Bank Master candidate

In this paper,two investment modes,greenfield investment and cross-border mergers and acquisitions,are introduced on the basis of Manova(2008),and it is found that enterprises with less financing constraints tend to choose cross-border mergers and ***,this paper takes Chinese industrial enterprises that conducted cross-border mergers and acquisitions and greenfield investment in 2003−2010 as examples to test the above *** result shows that enterprises with lower financing constraints are more likely to choose cross-border mergers and acquisitions,while those with stronger constraints choose greenfield *** specifi cally,a 1%reduction in financing constraints raises the probability of choosing cross-border mergers and acquisitions by 2.51%.The authors also find that the influence of financing constraints varies under different investment *** business service and production-related investment,enterprises with lower financing constraints tend to choose cross-border mergers and acquisitions;while for R&D investment,financing constraints have no impact on the choice of investment mode.

关键词： financing constraints outward foreign direct investment cross-border mergers and acquisitions greenfield investment

Short-Term Dynamic Radar Quantitative Precipitation Estimation Based on Wavelet Transform and Support Vector Machine

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Journal of Meteorological Research 2020年第2期34卷 413-426页

作者： Changjiang ZHANG Huiyuan WANG jing zeng Leiming MA Li GUAN College of Physics and Information Engineering Zhejiang Normal UniversityJinhua 321004 Shanghai Meteorological Center Shanghai 200030

Currently,Doppler weather radar in China is generally used for quantitative precipitation estimation(QPE)based on the Z–R ***,the estimation error for mixed precipitation is very *** order to improve the accuracy of radar QPE,we propose a dynamic radar QPE algorithm with a 6-min interval that uses the reflectivity data of Doppler radar Z9002 in the Shanghai Qingpu District and the precipitation data at automatic weather stations(AWSs)in East *** the time dependence and abrupt changes of precipitation,the data during the previous 30-min period were selected as the training *** reduce the complexity of radar QPE,we transformed the weather data into the wavelet domain by means of the stationary wavelet transform(SWT)in order to extract high and low-frequency reflectivity and precipitation *** the wavelet coefficients,we constructed a support vector machine(SVM)at all scales to estimate the wavelet coefficient of ***,via inverse wavelet transformation,we obtained the estimated *** comparing the results of the proposed method(SWTSVM)with those of Z=300×R1.4,linear regression(LR),and SVM,we determined that the root mean square error(RMSE)of the SWT-SVM method was 0.54 mm per 6 min and the average Threat Score(TS)could exceed 40%with the exception of the downpour category,thus remaining at a high *** speaking,the SWT-SVM method can effectively improve the accuracy of radar QPE and provide an auxiliary reference for actual meteorological operational forecasting.

关键词： short-term dynamic radar quantitative precipitation estimation stationary wavelet transform(SWT) support vector machine(SVM) Z-R relationship Threat Score

NaV6O15:A promising cathode material for insertion/extraction of Mg^2+with excellent cycling performance

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Nano Research 2020年第2期13卷 335-343页

作者： Dongzheng Wu jing zeng Haiming Hua Junnan Wu Yang Yang Jinbao Zhao Collaborative Imnovation Center of Chemistry for Energy Materials State Key Lab of Physical Chemistry of Solid SurfacesState Province Joint Engineering Laboratory of Power Source Technology for New Energy VehicleEngineering Research Center of Electrochemical TechnologyMinistry of EducationCollege of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005China School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou 510006China

The rechargeable magnesium batteries(RMBs)are getting more and more attention because of their high-energy density,high-security and ***,the high charge density of Mg^2+makes the diffusion of Mg2+in the conventional cathodes very slow,resulting in a lack of appropriate electrode materials for *** this work,we enlarge the layer spacing of V2Os by introducing Na^2+in the crystal structure to promote the diffusion kinetics of Mg^2+.The NaVeO15(NVO)synthesized by a facile method is studied as a cathode material for RMBs with the anhydrous pure Mg^2+*** a result,the NVO not only exhibits high discharge capacity(119.2 mAh:g^-1 after 100 cycles at the current density of 20 mA:g^-1)and working voltage(above 1.6 V ***^2+/Mg),but also expresses good rate ***,the eX-situ characterizations results reveal that the Mg^2+storage mechanism in NVO is based on the intercalation and *** density functional theory(DFT)calculation results further indicate that Mg^2+tends to occupy the semi-occupied sites of Na^+in the ***,the galvanostatic intermittent titration technique(GITT)demonstrates that NVO electrode has the fast diffusion kinetics of Mg^2+during discharge process ranging from 7.55×10^-13 to2.41×10^-11 cm^2·s^-*** work proves that the NVO is a potential cathode material for RMBs.

关键词： NaV6O15 alkali metal pre-intercalation rechargeable magnesium battery cathode electrochemical mechanism

Parametric analysis of wheel wear in high-speed vehicles

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Journal of Modern Transportation 2014年第2期22卷 76-83页

作者： Na Wu jing zeng State Key Laboratory of Traction Power Southwest Jiaotong University

In order to reduce the wheel profile wear of highspeed trains and extend the service life of wheels, a dynamic model for a high-speed vehicle was set up, in which the wheelset was regarded as flexible body, and the actual measured track irregularities and line conditions were considered. The wear depth of the wheel profile was calculated by the well-known Archard wear law. Through this model, the influence of the wheel profile, primary suspension stiffness, track gage, and rail cant on the wear of wheel profile were studied through multiple iterafive calculations. Numerical simulation results show that the type XP55 wheel profile has the smallest cumulative wear depth, and the type LM wheel profile has the largest wear depth. To reduce the wear of the wheel profile, the equivalent conicity of the wheel should not be too large or too small. On the other hand, a small primary vertical stiffness, a track gage around 1,435-1,438 mm, and a rail cant around 1：35-1：40 are beneficial for dynamic performance improvement and wheel wear alleviation.

关键词： Parametric analysis Wheel profile wear Flexible wheelset High-speed railway Vehicle dynamicmodel Finite element method

Angle-independent responsive organogel retroreflective structural color film for colorimetric sensing of humidity and organic vapors

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Chinese Chemical Letters 2021年第11期32卷 3584-3590页

作者： Cuiping Ji jing zeng Sijia Qin Min Chen Limin Wu Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers Fudan UniversityShanghai 200433China

The angle dependence of photonic crystals(PCs)dramatically limits their practical applications in the colorimetrical sensing of humidity and volatile organic compound(VOC)*** addition,it is challenging for inverse opal PCs to colorimetrically distinguish between vapors with similar refractive *** from the mechanism of PC-based sensors,here,we report an angle-independent polyacrylamide(PAAm)organogel structural color film based on the mechanisms of retroreflection,total internal reflection(TIR)and interference with a shape similar to a single-sided“egg waffle”.During the process of responding to humidity and VOC vapors,the color of the film remains angle-independent in the normal angle range of 0°to 45°under coaxial illumination and observation *** the same time,the film can colorimetrically distinguish between vapors with similar refractive indices,such as methanol and ethanol,which is mainly due to the differences in their polarity and solubility *** film shows good stability,reversibility and selectivity when exposed to vapors.A colorimetric sensor with a new response mechanism is proposed and has the potential to effectively distinguish between vapors with similar refractive ***,this responsive retroreflective structural color film(RRSCF)provides a universal strategy to develop targeted angle-independent structural color sensors by selecting optimized materials.

关键词： Angle-independent structural color Colorimetric sensing Responsive retroreflective structural color film Humidity sensing VOC vapor sensing

High-rate performance magnesium batteries achieved by direct growth of honeycomb-like V_(2)O_(5)electrodes with rich oxygen vacancies

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Nano Research 2023年第4期16卷 4880-4887页

作者： Dongzheng Wu Yichao Zhuang Fei Wang Yang Yang jing zeng Jinbao Zhao College of Chemistry and Chemical Engineering State-Province Joint Engineering Laboratory of Power Source Technology for New Energy VehicleState Key Laboratory of Physical Chemistry of Solid SurfacesEngineering Research Center of Electrochemical TechnologyMinistry of EducationCollaborative Innovation Center of Chemistry for Energy MaterialsXiamen UniversityXiamen 361005China School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou 510006China

Rechargeable magnesium batteries(RMBs)have emerged as a promising next-generation electrochemical energy storage technology due to their superiority of low price and high ***,the practical applications of RMBs are severely limited by immature electrode ***,the high-rate cathode materials are highly ***,we propose a dualfunctional design of V_(2)O_(5)electrode with rational honeycomb-like structure and rich oxygen vacancies to enhance the kinetics *** result demonstrates that oxygen vacancies can not only boost the intrinsic electronic conductivity of V_(2)O_(5),but also enhance the Mg^(2+)diffusion kinetics inside the cathode,leading to the good high-rate ***,ex-situ X-ray diffraction(XRD),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS)characterizations reveal that Mg^(2+)is mainly intercalated from the(101)plane of V_(2)O_(5)−X based on the insertion-type electrochemical mechanism;meanwhile,the highly reversible structure evolution during Mg^(2+)insertion/extraction is also *** work proposes that the dual-functional design of electrode has a great influence in enhancing the electrochemical performance of cathode materials for RMBs.

关键词： V2O5 rechargeable magnesium batteries oxygen vacancies kinetics electronic conductivity

Purifying Fe-based amorphous alloys to enhance glass-forming ability by designing a novel refining slag

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Journal of Materials Science & Technology 2023年第12期143卷 189-197页

作者： Shuai Mo jing zeng Hua Zhang Yinan Wu Tao Liu Hongwei Ni The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China The Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081China Wuhan Research Institute of Metallurgical Construction Ltd.MCCWuhan 430081China

Designing low melting point and low basicity refining slag suitable for Fe-based amorphous alloys and understanding the inclusions’formation,removal,influencing mechanisms are quite vital in the fields of metallurgy and *** this study,a novel 13%SiO_(2)-32%CaO-30%Al_(2)O_(3)-25%B_(2)O_(3)(wt.%)refining slag was designed after careful calculations of the liquid phase region,slag-metal equilibrium,surface tension,viscosity,deoxidation capability and sulfur distribution *** refining with our designed slag,the content of impurities and the number density of inclusions in a representative Fe_(83)Si_(2)B_(15)(at.%)amor-phous alloy were significantly ***,the glass-forming ability(GFA)of the alloy was also enhanced,enabling the preparation of amorphous ribbons with a lower cooling *** on the impu-rities in Fe-based amorphous alloys as well as the calculated oxide and sulfide free energy diagrams,CaO,SiO_(2),Al_(2)O_(3) oxides and CaS,TiS,MnS sulfides will form in the master *** high melting point in-clusions in the melt are generally removed via a floatation-separation-absorption process and the Mn,Ti,S impurities are removed via slag-metal interface reactions during *** for the detrimental effect of inclusions on glass formation,the small lattice disregistry between Ti,Mn-containing inclusions and primaryα-Fe gains reveal that these inclusions are effective in promoting the heterogeneous nucleation,and therefore greatly deteriorate the *** findings are important and provide an ideal solution to purifying the Fe-based amorphous alloys by refining and enhancing the GFA for industrial production.

关键词： Fe-based amorphous alloy Refining slag design Inclusion Lattice disregistry Heterogeneous nucleation

NUMERICAL ANALYSIS OF NONLINEAR STABILITY FOR RAILWAY PASSENGER CARS

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Chinese Journal of Mechanical Engineering 2001年第2期14卷 97-101页

作者： zeng jing National Traction Power Laboratory, Southwest Jiaotong University 西南交通大学牵引动力国家重点实验室四川成都

The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equilibrium points and the saddle node bifurcation point are computed through employing a variable step Runge Kutta method and the Poincaré map. Finally, numerical simulations are carried out for the stability of a high speed passenger car operating on straight and large radius curved tracks. The influences of the radius of curvature and the superelevation of the track on the stability of the vehicle system are investigated.

关键词： Railway passenger car Stability Bifurcation Limit cycle Critical speed