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Silver sulfide leaching with a copper-thiosulfate solution in the absence of ammonia

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Rare Metals 2011年第2期30卷 105-109页

作者： CUI Yiqi TONG Xiong Alejandro Lopez-Valdivieso faculty of land and resource engineering Kunming University of Science and Technology Kunming 650093 China Instituto de Metalurgia UniversidadAutonoma de San Luis Potosi San Luis Potosi C.P. 78210 Mexico

Leaching from silver *** a copper-thiosulfate solution in the absence of ammonia was investigated. It is found that silver sulfide could be effectively dissolved in the copper-thiosulfate system without ammonia. The effects of thiosulfate concentration, cop- per-to-thiosulfate ratio, agitation vigorousness, pH values, and dissolved gases on the leaching of silver sulfide with the copper-thiosulfate solution were studied. A maximum extraction of 95.1% was achieved with the 0.12 mol/L thiosulfate and the 0.048 rnol/L copper sulfate. It is shown that copper-to-thiosulfate ratio is an important factor in silver sulfide dissolution and oxygen is not needed to leach silver sulfide, which leads to the instability of the leaching system at high copper-to-thiosulfate ratio. On the other hand, the silver extraction is not affected by the pulp pH values.

关键词： extraction silver leaching copper sulfate thiosulfate

Frequency Analysis of Multiple Layered Cylindrical Shells under Lateral Pressure with Asymmetric Boundary Conditions

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Chinese Journal of Mechanical engineering 2014年第1期27卷 23-31页

作者： ISVANDZIBAEI Mohammad Reza JAMALUDDIN Hishamuddin RAJA HAMZAH Raja Ishak faculty of Mechanical engineering Universiti Teknologi Malaysia

Natural frequency characteristics of a thin-walled multiple layered cylindrical shell under lateral pressure are studied. The multiple layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum. The multiple layered shell equations with lateral pressure are established based on Love＇s shell theory. The governing equations of motion with lateral pressure are employed by using energy functional and applying the Ritz method. The boundary conditions represented by end conditions of the multiple layered cylindrical shell are simply supported-clamped（SS-C）, free-clamped（F-C） and simply supported-free（SS-F）. The influence of different lateral pressures, different thickness to radius ratios, different length to radius ratios and effect of the asymmetric boundary conditions on natural frequency characteristics are studied. It is shown that the lateral pressure has effect on the natural frequency of multiple layered cylindrical shell and causes the natural frequency to increase. The natural frequency of the developed multilayered cylindrical shell is validated by comparing with those in the literature. The proposed research provides an effective approach for vibration analysis shell structures subjected to lateral pressure with an energy method.

关键词： multiple layered ritz method lateral pressure shell boundary conditions

On the accuracy of higher order displacement discontinuity method(HODDM) in the solution of linear elastic fracture mechanics problems

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Journal of Central South University 2016年第11期23卷 2941-2950页

作者： Abolfazl Abdollahipour Mohammad Fatehi Marji Alireza Yarahmadi Bafghi Javad Gholamnejad faculty of Mining and Metallurgical engineering Yazd University

The higher order displacement discontinuity method(HODDM) utilizing special crack tip elements has been used in the solution of linear elastic fracture mechanics(LEFM) problems. The paper has selected several example problems from the fracture mechanics literature(with available analytical solutions) including center slant crack in an infinite and finite body, single and double edge cracks, cracks emanating from a circular hole. The numerical values of Mode Ⅰ and Mode Ⅱ SIFs for these problems using HODDM are in excellent agreement with analytical results(reaching up to 0.001% deviation from their analytical results). The HODDM is also compared with the XFEM and a modified XFEM results. The results show that the HODDM needs a considerably lower computational effort(with less than 400 nodes) than the XFEM and the modified XFEM(which needs more than 10000 nodes) to reach a much higher accuracy. The proposed HODDM offers higher accuracy and lower computation effort for a wide range of problems in LEFM.

关键词： accuracy higher order displacement discontinuity method LEFM mode Ⅰ stress intensity factor mode Ⅱ stress intensity factor

Effects of Welding and rotational speeds on the Microstructure and Hardness of Friction Stir Welded Single-Phase Brass

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 766-771页

作者： Sajjad Emami Tohid Saeid Materials engineering faculty Sahand University of Technology

This study focuses on the effects of rotational and welding speeds on the microstructure and hardness of joints in friction stir welded single-phase brass. Welds were achieved under low heat input conditions at rotational and welding speeds of 400-800 r/min and 100-300 mm/min, respectively. In order to characterize the obtained welds, optical microscopy and Vickers hardness measurements were taken on the weld cross sections. According to the obtained results, increasing the welding speed and/or decreasing the rotational speed caused the grain size of the stir zone to decrease and, hence, improved the average hardness of this region. These results are discussed with respect to the interplay between the welding parameters and the peak temperature in the weld thermal cycle.

关键词： Friction stir welding Single-phase brass Dynamic recrystailization Hardness

Effect of foundation flexibility on ductility reduction factors for R/C stack-like structures

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Earthquake engineering and engineering Vibration 2011年第2期10卷 277-290页

作者： Amir M.Halabian Shabnam Kabiri faculty of Civil engineering Isfahan University of Technology

The most important parameter used to determine force reduction factors in force-based design procedures adopted in the current seismic codes is the structural ductility. For a structure supported on a flexible foundation, the ductility factor could be affected by foundation compliances. The ductility factors given in the current codes are mostly assigned ignoring the effect of SSI and therefore the objective of this research is to assess the significance of SSI phenomenon on ductility factors of stack-like structures. The deformed configuration of stack-fike structures is idealized as an assemblage of beam elements considering nonlinear moment-curvature relations, while a linear sway-rocking model was implemented to model the supporting soil. Using a set of artificial records, repeated linear and nonlinear analyses were performed by gradually increasing the intensity of acceleration to a level where the first yielding of steel in linear and nonlinear analyses is observed and a level corresponding to the stack collapse in the nonlinear analysis. The difference between inelastic and elastic resistance in terms of displacement ductility factors has been quantified. The results indicate that foundation flexibility can decrease the ductility of the system and neglecting this phenomenon may lead to erroneous conclusions in the prediction of the seismic performance of flexibly-supported R/C stack-like structures.

关键词： soil-structure interaction R/C stack-like structures ductility

Infection-responsive long-term antibacterial bone plates for open fracture therapy

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Bioactive Materials 2023年第7期25卷 1-12页

作者： Lujiao Zhang Yurun Yang Yan-Hua Xiong Yu-Qing Zhao Zongpeng Xiu Hui-Min Ren Kai Zhang Shun Duan Ying Chen Fu-Jian Xu State Key Laboratory of Chemical resource engineering Key Lab of Biomedical Materials of Natural Macromolecules(Beijing University of Chemical Technology)Ministry of EducationBeijing Laboratory of Biomedical MaterialsBeijing Advanced Innovation Center for Soft Matter Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China Department of Orthopaedic Surgery China-Japan Friendship HospitalBeijing100029China

The infections in open fracture induce high morbidity ***,developing efficient anti-infective orthopedic devices is of great *** this work,we designed a kind of infection-responsive long-term antibacterial bone *** a facile and flexible volatilization method,a multi-aldehyde polysaccharide derivative,oxidized sodium alginate,was crosslinked with multi-amino compounds,gentamycin and gelatin,to fabricate a uniform coating on Ti bone plates via Schiff base reaction,which was followed by a secondary crosslinking process by *** double-crosslinked coating was stable under normal condition,and could responsively release gentamycin by the triggering of the acidic microenvironment caused by bacterial metabolism,owning to the pH-responsiveness of imine *** thickness of the coating was ranging from 22.0μm to 63.6μ*** coated bone plates(Ti-GOGs)showed infection-triggered antibacterial properties(>99%)and high *** being soaked for five months,it still possessed efficient antibacterial ability,showing its sustainable antibacterial *** in vivo anti-infection ability was demonstrated by an animal model of infection after fracture fixation(IAFF).At the early stage of IAFF,Ti-GOGs could inhibit the bacterial infection(>99%).Subsequently,Ti-GOGs could promote recovery of fracture of *** work provides a convenient and universal strategy for fabrication of various antibacterial orthopedic devices,which is promising to prevent and treat IAFF.

关键词： Antibacterial Open fracture Infection-responsive Coating Orthopedic medical device

A seismic elastic moduli module for the measurements of low-frequency wave dispersion and attenuation of fluid-saturated rocks under different pressures

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Petroleum Science 2024年第1期21卷 162-181页

作者： Yan-Xiao He Shang-Xu Wang Gen-Yang Tang Chao Sun Hong-Bing Li San-Yi Yuan Xian Wei Li-Deng Gan Xiao-Feng Dai Qiang Ge Peng-Peng Wei Hui-Qing Zhang National Key Laboratory of Petroleum resources and engineering CNPC Key Lab of Geophysical ExplorationCollege of GeophysicsChina University of Petroleum(Beijing)Beijing102249China School of resources and Geosciences China University of Mining and TechnologyXuzhou221116JiangsuChina Research Institute of Petroleum Exploration and Development CNPCBeijing100083China Beijing Vocational College of Labour and Social Security Beijing100029China PetroChina Dagang Oilfield Exploration and Development Research Institute CNPCTianjin300280China

Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and time-lapse seismic surveillance of both conventional and unconventional reservoir and overburden performances.A Seismic Elastic Moduli Module has been developed,based on the forced-oscillations method,to experimentally investigate the frequency dependence of Young's modulus and Poisson's ratio,as well as the inferred attenuation,of cylindrical samples under different confining pressure *** with three standard samples showed that the measured elastic moduli were consistent with the published data,indicating that the new apparatus can operate reliably over a wide frequency range of f∈[1-2000,10^(6)]*** Young's modulus and Poisson's ratio of the shale and the tight sandstone samples were measured under axial stress oscillations to assess the frequency-and pressure-dependent *** dry condition,both samples appear to be nearly frequency independent,with weak pressure dependence for the shale and significant pressure dependence for the *** particular,it was found that the tight sandstone with complex pore microstructure exhibited apparent dispersion and attenuation under brine or glycerin saturation conditions,the levels of which were strongly influenced by the increased effective *** addition,the measured Young's moduli results were compared with the theoretical predictions from a scaled poroelastic model with a reasonably good agreement,revealing that the combined fluid flow mechanisms at both mesoscopic and microscopic scales possibly responsible for the measured dispersion.

关键词： Low-frequency measurements Dispersion and attenuation Rock physics Fluid flow

Experimental study on preferential solution flow during dump leaching of low-grade ores

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中南工业大学学报：英文版 2007年第4期14卷 584-588页

作者：尹升华吴爱祥苏永定张杰 School of Civil and Environment engineering University of Science and Technology Beijing School of resource and Safety engineering Central South University

The phenomenon of preferential solution flow during dump leaching of low-grade ores was *** formative mechanism of preferential solution flow was investigated through analyzing the relationship between permeability and ore diameter,and the relationship between surface tension and ore *** preferential solution flow happened within the fine ore area when the dump was *** it could happen within the coarse ore area when the dump became *** results of experiment show that the outflow of coarse ore area increases sharply with higher applied *** outflow of fine ore area is greater than that of coarse ore area when the applied rate is below 3.2 L/min,and the preferential solution flow happens in fine ore *** the preferential solution flow happens in coarse ore area when the applied rate is higher than 3.2 L/*** result of the experiment is consistent with the mechanism analyzing.

关键词：低等级矿石渗透性表面张力排土场

Electrodeposition of nanostructured Ti/(Ru+Ti+Ce)O_2 coatings

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Rare Metals 2018年第1期37卷 13-20页

作者： Seyed Mostafa Peyghambari Mardali Yousefpour faculty of Materials and Metallurgical engineering Semnan University

A nanostructured ternary coating of Ti/（Ru ＋ Ti ＋ Ce）O2 was prepared by the conventional electrodeposition on the titanium substrate as the cathode with different numbers of coating layers. The main objective of this work was to study nanostructured coatings of ceramic materials. For this purpose, the amount of precursor materials in the electrolyte was a variable parameter. Furthermore, the salt of TiCl4/RuCl3·xH2 O/Ce（NO3）3·6 H2 O with different amounts, hydrogen peroxide, methanol, and distilled water were used as an aqueousunaqueous bath. In addition, the coated samples were put to heat at 300, 450, 650, and 850℃ in an electric furnace for1 h. The crystalline phase of the coating was characterized by X-ray diffraction（XRD）. The chemical composition and microstructure of the coating were studied using energydispersive spectroscopy（EDS） and scanning electron microscopy analysis（SEM）. Moreover, the electrochemical measurement of Ti/（Ru ＋ Ti ＋ Ce）O2 coatings was carried out. Results show that with the increase in the number of coating layers, the quality of morphology is ***, the best quality of coatings is obtained at six layers on the titanium substrate with electrolyte including TiO2/RuO2/CeO2 with the molar ratio of 70：5：25 after heat treatment at 450 ℃ for 1 h. Besides,with the increase in Ce02 content from 5 wt% to 25 wt% and the number of coating layers, higher thickness of about（20.0±0.1） μm and minimum over potential for chlorine evolution were obtained.

关键词： Oxides Coating Heat treatment Interface Thin films