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Ivory Coast Intra Regional Trade： The Role of Infrastructure and Economic Environment

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Economics World 2017年第6期5卷 595-607页

作者： fe Doukoure Charles National School of Statistics and Applied Economics Economic Policy Analysis Unit of the Ivoirian Center of Economic and Social Research Abidjan Ivory Coast

Intra-regional trade dynamic can foster economic integration with a contribution of the lead economy. In that way, infrastructure and economic environment play an important role in expanding trade by reducing trade costs. This paper examines the role of infrastructure and the economic environment on Ivory Coast intra-regional trade. The study performs a transformed and advanced gravity model, using panel data over the period 1996 to 2013, modelling exports of Ivory Coast. The analysis shows experts towards the other member states of West African Economic and Monetary Union （WAEMU） depend significantly on the availability of transport and communication infrastructures developed as well as variables such as gross Domestic Product growth, economic similarity within countries, Foreign Direct Investment （FDI） net inflows in Ivory Coast. Estimations point out that indeed, the level of economic growth in the other member countries, Foreign Direct Investment （FDI） net inflows in Ivory Coast, the number of mobile phone subscribers per 100 inhabitants in Ivory Coast and the proportion of paved roads, have a positive impact on Ivory Coast intra-regional trade.

关键词： intra-regional trade infrastructure economic environment transformed gravity model

Improvement of Coercivity and Corrosion Resistance of Nd-fe-B Sintered Magnets with Cu Nano-particles Doping

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Journal of Materials Science & Technology 2012年第10期28卷 927-930页

作者： C.Sun W.Q.Liu H.Sun M.Yue x.F.Yi J.W.Chen College of Materials Science and Engineering Beijing University of TechnologyBeijing 100124China Earth-panda Advance Magnetic Material Co. Ltd.Anhui 231500China

Nd-fe-B permanent magnets with a small amount of Cu nano-particles doping have been prepared by con-ventional sintered method. Effects of Cu content on magnetic properties, corrosion resistance, and oxidation properties of the magnets have been studied. It shows that the coercivity rises gradually, while the remanence decreases simultaneously with increasing Cu doping amount. Microstructure observation reveals that Cu ele- ment enriches mainly the Nd-rich phase. Autoclave test results show that the corrosion rate of the magnets decreases with increasing Cu content. After oxidation, the maximum energy product loss of the magnets with 0 and 0.2 wt% Cu nano-particles doping are 6.13% and 0.g9%, respectively. Therefore, it is concluded that Cu nano-particles doping is a promising way to enhance the coercivity and corrosion resistance of sintered Nd-fe-B magnets.

关键词： Nd-fe-B Cu nano-particles Coercivity Corrosion resistance Oxidation

Macroeconomic and Social Impacts of Economic Partnership Agreements on Ivorian Economy： A New Assessment

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Economics World 2014年第5期2卷 291-302页

作者： fe Doukoure Charles National School of Statistics and Applied Economics Abidjan Ivory Coast

This study reassesses the macroeconomic and social impacts of Economic Partnership Agreements （EPAs） on Ivorian economy using Computable general Equilibrium （CgE） model with positive externalities of public investment in education, health, and economic infrastructure. Previous studies highlight negative effect of these agreements stressing particularly on losses in government revenues due to the removal of all tariffs on imports. This analysis aims to provide some insight into this question by refreshing the debate to show how this situation could be transformed into opportunities for Ivory Coast in order to promote growth and reduce poverty. To do so, this study postulates that government spending （investment） in economic infrastructure （roads, bridges, communication network, etc.）, in education and health sectors produces positive externalities in each industry. This assumption has not been set anymore in previous studies. Simulation results reveal that, despite this decline in government revenues, if it invests in economic infrastructure, health and education sector, EPAs will generate more revenue for government due to the rise in income tax on firms and households, and tax on overall production. Furthermore, household income will increase which will in turn stimulate （final） consumption. There won＇t also be a decline in economic growth.

关键词： externality economic growth free trade agreements imports macroeconomic and social impacts public investment tax

Nanocrystal Model for Liquid Metals and Amorphous Metals

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Journal of Materials Science & Technology 2010年第1期26卷 69-74页

作者： x.L. Tian, C.W. Zhan, J.x. Hou, x.C. Chen and J.J. Sun Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China Key Laboratory of Liquid Structure and Heredity of Materials Ministry of Education Shandong University Jinan 250061 China

A nanocrystal model for liquid metals and amorphous metals has been developed. With the nanocrystal model, the broadening peak profiles （BPPs） of Cu, Al, Al65Cu20fe15 alloy, Cu7oNi30 alloy and fe50Si50 alloy were gained by broadening the x-ray diffraction （xRD） peaks of a crystal lattice. By comparing the BPPs with the xRD intensity curves measured on the liquid metals, it is found that the BPPs are closely in agreement with the xRD intensity curves, respectively, except the fesoSiso alloy. Therefore, the nanocrystal model can be used to determine if the atomic cluster structure of the liquid metal is similar to the structure of its crystal lattice.

关键词： Liquid metal Atomic cluster Structure Crystal lattice

Towards the diffusion source cost reduction for NdfeB grain boundary diffusion process

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Journal of Materials Science & Technology 2020年第1期36卷 50-54页

作者： H.x.Zeng Z.W.Liu J.S.Zhang x.F.Liao H.Y.Yu School of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China

Aiming at improving the performance/cost ratio in grain boundary diffusion process(gBDP),the critical RE containing Pr-Al-Cu alloy,less expensive RE containing La-Al-Cu alloy and non-RE Al-Cu alloy were employed as the diffusion *** preliminary results show that the coercivity was successfully enhanced from 1000 kA/m to 1695,1156 and 1125 kA/m by Pr70Al20Cu10,La70Al20Cu10 and Al75Cu25(at.%) alloys diffusion,respectively,due to the formation of(Nd,Pr)-fe-B,La2 O3 and c-Nd2 O3 phases respectively,after *** is also found that the corrosion resistance can be improved by Al-Cu diffusion due to the positive effects of Al and Cu elements in grain *** present results demonstrated the various coercivity enhancement mechanisms for the gBDP based on different diffusion sources,and provided feasible solutions for cost reduction of gBDP and NdfeB production by saving RE resource.

关键词： grain boundary diffusion Cost reduction Coercivity Microstructure Corrosion resistance

Surface chemistry of nanoscale fe_3O_4 dispersed in magnetic fluids

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Science China Chemistry 2007年第6期50卷 754-758页

作者： Bernd güNTHER Fraunhofer Institut für fertigungstechnik und Angewandte Materialforschung D-28359 Bremen Germany

The interaction between stabilizers and nanoparticles is one of the important factors to prepare stable magnetic fluids. The magnetic nano-size fe3O4 core with single domain and the average grain size around 8-12 nm were prepared by chemical precipitation method. The O/fe molar ratio of the particle surface was measured by x-ray photoelectron spectroscopy (xPS). The heat effects of stabilizers ad- sorption on nanoparticles were measured by solution calorimetry. The excess amount of oxygen was possibly the result of the hydroxygen formed on the surface of the nanoparticles. The heat effects showed that compounds containing carboxyl groups can be adsorbed chemically on magnetite by forming chemical bonds. The other stabilizers involving NH-groups, such as polyethylene-imine, can be adsorbed physically. The exothermic value is about half of the former case.

关键词： nanoscale materials heat effect magnetic fluids surface chemistry

Adsorption of As on hydroxy-fe-montmorillonite complexes

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Science China Earth Sciences 2005年第12期48卷 2155-2165页

作者： Donald g. Fraser Department of Earth Sciences Oxford University Parks Road Oxford OX1 3PR UK

Arsenate has high affinity for soluble hydroxy-fe species and fe-oxyhydroxide pre-cipitates. In addition, the hydrolysis of fe(III) and the growth of the initially precipitated fe(III) phases are strongly influenced by the presence of montmorillonite. In this paper, the adsorption of As onto various hydroxy-fe-montmorillonite (H-F-M) complexes was studied. Three systems of samples were prepared by mixing montmorillonite, hydroxy-fe and arsenate in different se-quences: (1) Prior mixing of montmorillonite and hydroxy-fe before the addition of arsenate; (2) prior mixing of hydroxy-fe and arsenate before the addition of montmorillonite; and (3) prior mixing of montmorillonite and arsenate before the addition of hydroxy-fe. For each system, the effects of pH, ionic strength, temperature, initial fe and As concentrations and adsorption dura-tion on the overall uptake of As by H-F-M complexes were studied. Results showed that the up-take of As increased with increasing pH, temperature, initial fe concentration and adsorption duration, and decreased with increasing ionic strength and initial As concentration to different extents for the three systems. The variation of the As uptake of H-F-M complexes with pH in the range of study is opposite to that reported previously for fe-O-H systems in the absence of montmorillonite and similar to that reported for montmorillonite in the absence of hydroxy-fe. The marked influence of ionic strength on the As uptake of H-F-M complexes indicates that outer-sphere complexation plays an important role. This is quite different from the adsorption of As on the surface of either fe-oxyhydroxides or montmorillonite alone in which inner-sphere complexation dominates. Under all experimental conditions, the H-F-M complexes studied dis-played a very strong affinity for As, among which system 2 had the highest As adsorption capac-ity and system 1 the lowest. The authors attribute this to the differences in mixing sequence which resulted in more hy

关键词： hydroxy-fe, montmorillonite, complex, arsenate adsorption.

Succession of Bacterial Community Inhabited Acid Mine Drainage under High fe（Ⅱ） Concentration

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Journal of Environmental Science and Engineering 2010年第8期4卷 46-55页

作者： M.x. Wan Y. Yang W.M. Zeng J.L. xia x.D. Liu W.Q. Qin g.Z. Qiu School of Minerals Processing and Bioengineering Central South University Hunan 410083 China Department of Chemical ＆ Biomolecular Engineering Johns Hopkins University MD 21218 USA Key Laboratory of Biometalhtrgy of Ministry of Education Hunan 410083 China CSIRO Process Science and Engineering Clayton VIC 3168 Australia

To reveal the effects of fe2＋ on bacterial communities in the early stages of minerals dissolution, two different acid mine drainage （AMD） samples were collected at Dabaoshan Mine and Shenbu Mine. Community successions of AMD niches were analyzed by Amplified Ribosomal DNA Restriction Analysis （ARDRA）, sequencing, and phylogenetic analysis in original AMD samples and their subculture under fe2＋ concentrations. Although geochemical properties and community structures were greatly different between the two original AMD samples, bacterial community successions were still very similar under high fe2＋ concentrations. The results showed that Acidithiobacillus ferrooxidans have competitive relationship with other bacterial species living in the AMD, including species that were also capable of oxidizing ferrous ion. A competitive relationship among different At. ferrooxidans strains likewise existed. Some of At. ferrooxidans can grow first under conditions of high ferrous ion concentration, and other At. ferrooxidans species decreased gradually and disappeared. This suggested that these species of At. ferrooxidans are most acidophilic bacteria and afford fe3＋ to leach other metallic ion in the early stages of minerals dissolution.

关键词： Bacterial diversity succession acid mine drainage amplified ribosomal DNA restriction analysis.

Mechanical property and structural changes by thermal cycling in phase-separated metallic glasses

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Journal of Materials Science & Technology 2021年第19期78卷 144-154页

作者： Y.Tang H.B.xiao x.D.Wang Q.P.Cao D.x.Zhang J.Z.Jiang International Center for New-Structured Materials(ICNSM) Laboratory of New-Structured MaterialsState Key Laboratory of Silicon Materialsand School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China State Key Laboratory of Modem Optical Instrumentation Zhejiang UniversityHangzhou.310027China

Nondestructive cryogenically thermal cycling has been a simple but effective treatment to enhance mechanical properties of glassy ***,how the structural heterogeneities on nanometer scales are affected by thermal cycling is still an ***,we report the response of spatial heterogeneities in three selected Ti_(41)Zr_(25)Be_(28)fe_(6),Zr_(56)Co_(14)Cu_(14)Al_(16)and Zr_(42)Y_(14)Co_(22)Al_(22)(at.%)metallic glasses(Mgs)with different compositions to the thermal cycling,which show significantly different structure and properties after the same treatments and could be ascribed to the joint contribution of relaxation and rejuvenation induced by thermal *** rejuvenation is initially prevailed in a Zr-Y-containing Mg,whereas the relaxation is dominant in a Cu-Co-containing Mg,both eventually entering into a dynamic equilibrium *** employing nanometer-scale structural models,the intrinsic correlation between the spatial heterogeneity and thermal cycling is *** discovery could provide the fundamental understanding of the role of spatial heterogeneity in influencing the macroscopic properties of Mgs via thermal cycling and help design high-performance glassy materials by tailoring their atomic structures with suitable thermal treatments.

关键词： Thermal cycling Metallic glass Spatial heterogeneity Relaxation Rejuvenation