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Influence of Si on Interfacial Combination of SiCp/Al-Mg-Si Composite

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Journal of Rare Earths 2004年第Z2期22卷 69-72页

作者： Han Jianmin li ronghua li Mingwei Cui Shihai li Weijing Wang Jinhua School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

The scanning electron microscopy (SEM) analysis results of Si distribution in the interface between SiC reinforcements and aluminum matrix of a stir casting SiCp/Al-Mg-Si composite were presented. Results show that there is Si precipitation deposit on the interface of the composite and Si connects with SiC reinforcements in one side and connects with aluminum matrix in the other side. Si phase plays as a connecting bridge, which contributes to the interfacial combination of SiCp/Al composite.

关键词： interfacial combination Si SiCp/Al-Mg-Si composite

Immobilization of Lead and Cadmium in Contaminated Soil Using Amendments: A Review

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Pedosphere 2015年第4期25卷 555-568页

作者： Amanullah MAHAR WANG Ping li ronghua ZHANG Zengqiang College of Natural Resources and Environment Northwest A&F University Centre for Environmental Sciences University of Sindh

Since the inception of industrial revolution, metal refining plants using pyrometallurgical processes have generated the prodigious emissions of lead(Pb) and cadmium(Cd). As the core target of such pollutants, a large number of soils are nowadays contaminated over widespread areas, posing a great threat to public health worldwide. Unlike organic pollutants, Pb and Cd do not undergo chemical or microbial breakdown and stay likely in site for longer duration after their release. Immobilization is an in-situ remediation technique that uses cost-effective soil amendments to reduce Pb and Cd availability in the contaminated soils. The Pb and Cd contamination in the soil environment is reviewed with focus on source enrichment, speciation and associated health risks, and immobilization options using various soil amendments. Commonly applied and emerging cost-effective soil amendments for Pb and Cd immobilization include phosphate compounds, liming, animal manure, biosolids, metal oxides, and biochar. These immobilizing agents could reduce the transfer of metal pollutants or residues to food web(plant uptake and leaching to subsurface water) and their long-term sustainability in heavy metal fixation needs further assessment.

关键词： bioavailability biochar biosolids heavy metal public health remediation soil extraction

Research on PTFE Dispersions Filled with Nanometer ZnO

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Journal of Rare Earths 2004年第Z2期22卷 157-161页

作者： Han Jianmin li Weijing Cui Shihai Zhao Yang li ronghua Wang Jinhua School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

PTFE dispersion composites filled with nanometer ZnO were successfully prepared by controlling stirring speed and using ultrasonic mixture with no damage to PTFE dispersion. Properties of PTFE composites, such as wear rate, friction coefficient and thermal conductivity coefficient were tested respectively. Also, the grain size of nanometer filler in composites were observed by different methods, such as small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and dynamic light scattering particle size distribution analyzer (DLSPSDA). Results show that nanometer ZnO fillers can further improve properties of PTFE-based composite, and its properties varies with the content of the fillers.

关键词： PTFE dispersion nanometer ZnO composite wear property

Structure and Corrosion Resistance of Microarc Oxidation Coatings on AZ91D Magnesium Alloy

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Journal of Rare Earths 2004年第Z2期22卷 38-41页

作者： Cui Shihai Han Jianmin li Weijing li ronghua Zhu Xiaowen Wang Jinhua School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Magnesium alloys are widely used as shells of 3C (computer, mobile phone and consumer electronics) equipments for its impressive mechanical and physical properties, such as low density, good resistance to electromagnetic radiation, suitable for high pressure diecasting and easily recycling, etc. But poor corrosion resistance confines its extensively application. In this paper, protective coatings was successfully prepared on AZ91D magnesium alloys by micro-arc oxidation (MAO) and painting process. Microstructures and phases of MAO coatings were invesgated with scanning electron microscope (SEM) and X-Ray diffractometer. Mechanical properties of MAO coating, such as adhesive force and corrosion resistance, were also tested. Results showed that MAO coatings were a good base for painting process. MAO coatings with paint have good adhesive properties to base metal and excellent corrosion resistance. Micro-arc oxidation with painting process is a good kind of surface treatment to improve the corrosion resistance of mobile phone shell made of AZ91D magnesium alloys.

关键词： magnesium alloy micro-arc oxidation microstructure corrosion resistance adhesive

Morphologies and Properties of Micro-Arc Oxidation on Plate and Cylinder 2024 Al Alloy

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Journal of Rare Earths 2004年第Z2期22卷 50-52页

作者： Zhu Xiaowen Han Jianmin Cui Shihai li ronghua li Weijing Wang Jinhua School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Samples with two different shapes of 2024 aluminum alloy were treated with micro-arc oxidation (MAO), and the formation process and mechanism of oxidation film was analyzed. The results show that different geometrical... 详细信息

关键词： micro-arc oxidation ceramic film aluminum alloy rare earths

Mechanical parameter evolutions and deterioration constitutive model for ductile-brittle failure of surrounding rock in high-stress underground engineering

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Underground Space 2024年第2期15卷 131-152页

作者： Zhi Zheng ronghua li Qiang Zhang Xiaohua Huang Wei Wang Shuling Huang State Key Laboratory of Featured Metal Materials and life-cycle Safety for Composite Structures Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang 110819China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai UniversityNanjing 210098China Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources Yangtze River Scientific Research InstituteWuhan 430010China

The deep surrounding rock is usually in the true triaxial stress state,and previous constitutive models based on the understanding of uniaxial and conventional triaxial test results have difficulty characterizing the degradation and fracture process of rock ductile–brittle failure under true triaxial stress ***,this study conducted a series of true triaxial tests to obtain the understanding of the ductile–brittle behaviour of rock,and then combined the test results and the Mogi–Coulomb strength criterion,and proposed calculation methods for the elastic modulus E,cohesion c and internal friction angle u and the evolution functions of E,c and u of rock under true triaxial *** the decreasing of the minimum principal stress r3 or increasing of the intermediate principal stress r2,the marble post-peak stress drop rate gradually increases,the ductility gradually weakens,and the brittleness significantly *** calculation method and evolution function of rock E,c and u under true triaxial stress were proposed.E decreased at first and then tended to remain stable with the increasing of equivalent plastic strain increment dep.c and u slowly increased at first and then rapidly *** a method of parameter degradation rate to realize post-peak stress drop rate to reflect the ductile–brittle characteristics,a new three-dimensional ductile–brittle deterioration mechanical model(3DBDM)was *** proposed model can accurately characterize the influence of r2 and r3 on mechanical parameters,the ductile–brittle behaviour of rock under true triaxial stresses,and the asymmetric failure characteristics of surrounding rock after excavation of deep underground *** proposed model can be reduced to elastic–perfectly plastic,elastic–brittle,cohesion weakening friction strengthening(CWFS),Mohr–Coulomb,and Drucker–Prager models.

关键词： True triaxial stress Post-peak characteristics 3D deterioration model Elastic modulus evolution Cohesion and friction angle evolution

Rice-duck co-culture benefits grain 2-acetyl-1-pyrroline accumulation and quality and yield enhancement of fragrant rice

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The Crop Journal 2019年第4期7卷 419-430页

作者： Meijuan li ronghua li Shiwei liu Jia'en Zhang Hao Luo Shuqing Qiu College of Natural Resources and Environment South China Agricultural University Guangzhou 510642 Guangdong China Guangdong Engineering Technology Research Centre of Modern Eco-agriculture and Circular Agriculture Guangzhou 510642 Guangdong China Key Laboratory of Agro-Environment in the Tropics Ministry of Agriculture Guangzhou 510642 Guangdong China

Rice-duck co-culture is an integrated farming technology that benefits rice production, grain quality, and ecological sustainability in paddy fields. However, little is known about the effects of rice-duck co-culture on enzyme activity involved in the biosynthesis of 2-acetyl-1-pyrroline (2-AP), the volatile that gives fragrant rice its' distinctive and sought-after aroma. The present study aimed to examine the influence of rice-duck co-culture on the photosynthesis, yield, grain quality, rice aroma, and the enzymes involved in 2-acetyl-1-pyrroline biosynthesis in the cultivar Meixiangzhan 2 during the early and late rice growing seasons of 2016 in Guangzhou, China. We compared the rice grown in paddy fields with and without ducks. We found that rice-duck co-culture not only improved the yield and quality of fragrant rice grain, but also promoted the precursors of 2-AP biosynthesis formation and 2-AP accumulation in the grain. Grain 2-AP content in rice-duck co-culture was noticeably increased with 9.60% and 20.81% in early and late seasons, respectively. Proline and pyrroline-5-carboxylic acid (P5C) (precursors of 2-AP biosynthesis) and the activity of enzymes such as proline dehydrogenase (ProDH), ornithine aminotransferase (OAT) and Δ1 pyrroline-5-carboxylic acid synthetase (P5CS) were all improved by 10.15%–12.99%, 32.91%–47.75%, 17.81%–26.71%, 6.25%–21.78%, and 10.58%–38.87% under rice-duck co-culture in both seasons, respectively. Overall, our results suggest that rice-duck co-culture is an environmentally-friendly and sustainable approach to improving rice aroma and grain quality of fragrant rice.

关键词： Rice-duck co-culture 2-AP Proline Yield Grain quality Fragrant rice

Shear failure behaviors and degradation mechanical model of rockmass under true triaxial multi-level loading and unloading shear tests

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International Journal of Mining Science and Technology 2024年第10期34卷 1385-1408页

作者： Zhi Zheng ronghua li Pengzhi Pan Jinghua Qid Guoshao Su Hong Zheng State Key Laboratory of Featured Metal Materials and life-cycle Safety for Composite Structures Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China China Energy Engineering Group Guangxi Electric Power Design Institute Co.Ltd. Nanning 530007China State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China

The redistribution of three-dimensional(3D)geostress during underground tunnel excavation can easily induce to shear failure along rockmass structural plane,potentially resulting in engineering ***,the current understanding of rockmass shear behavior is mainly based on shear tests under2D stress without lateral stress,the shear fracture under 3D stress is unclear,and the relevant 3D shear fracture theory research is ***,this study conducted true triaxial cyclic loading and unloading shear tests on intact and bedded limestone under different normal stress σ_(n) and lateral stressσ_(p)to investigate the shear strength,deformation,and failure *** results indicate that under differentσ_(n)and σ_(p),the stress–strain hysteresis loop area gradually increases from nearly zero in the pre-peak stage,becomes most significant in the post-peak stage,and then becomes very small in the residual stage as the number of shear test cycles *** shear peak strength and failure surface roughness almost linearly increase with the increase inσ_(n),while they first increase and then gradually decrease asσ_(p)increases,with the maximum increases of 12.9%for strength and 15.1%for *** shear residual strength almost linearly increases withσ_(n),but shows no significant change withσ_(p).Based on the acoustic emission characteristic parameters during the test process,the shear fracture process and microscopic failure mechanism were *** the shear stressτincreases,the acoustic emission activity,main frequency,and amplitude gradually increase,showing a significant rise during the cycle near the peak strength,while remaining almost unchanged in the residual *** true triaxial shear fracture process presents tensile-shear mixture failure characteristics dominated by microscopic tensile *** on the test results,a 3D shear strength criterion considering the lateral stress effect was proposed,and the determination met

关键词： True triaxial shear test Lateral stress effect Acoustic emission monitoring Shear parameters evolution Shear degradation mechanical model

Dynamic metabolite alterations of Portunus trituberculatus during larval development

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Journal of Oceanology and limnology 2019年第1期37卷 361-372页

作者： SHI Ce ZENG Tinglan li ronghua WANG Chunlin YE Yangfang MU Changkao Key Laboratory of Applied Marine Biotechnology Ningbo University Chinese Ministry of Education Collaborative Innovation Center for Zhejiang Marine High-effi ciency and Healthy Aquaculture

A mass mortality often occurs from molting to the megalopa stage during the larval development of the swimming crab Portunus trituberculatus. Larvae with insuffcient nutrient accumulation during the zoeal stages are probably unable to develop into juvenile swimming crabs. However, the nutritional information such as the primary metabolites is scarce for P. trituberculatus larvae. The aim of this work is to obtain an insight into the metabolite traits of P. trituberculatus at early developmental stages. 1 H nuclear magnetic resonance spectroscopy coupled with multivariate data analysis was used to determine how the metabolite pro?les shift during larval development in P. trituberculatus. Our results show that the trend of total metabolites exhibited a rise from zoea 1 to zoea 3, followed by a drop from zoea 4 to megalopa and recovery during the ?rst juvenile stage. A large-scale depletion of total metabolites in the zoea 4 and megalopa stages suggests a deep depression of metabolic activity, which may be linked to the mass mortality from molting to the megalopa stage. These ?ndings provided essential metabolic information about the larval development of P. trituberculatus and important clues for understanding the nutritional requirements of P. trituberculatus in early developmental stages.

关键词： Portunus trituberculatus larval development metabolite phenotype nuclear magnetic resonance(NMR)