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Electrochemical studies on interplay of mineralogical variation and particle size on bioleaching low grade complex sulphide ores

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中国有色金属学会会刊：英文版 2009年第5期19卷 1312-1325页

作者： P.A.OLUBAMBI j.h.potgieter S.NDLOVU j.O.BORODE Department of Chemical and Metallurgical Engineering Tshwane University of TechnologyPretoriaSouth Africa Chemistry and Materials Division School of BiologyChemistry and Health SciencesManchester Metropolitan UniversityUK School of Chemical and Metallurgical Engineering University of the WitwatersrandJohannesburgSouth Africa Department of Metallurgical and Materials Engineering Federal University of TechnologyAkureNigeria

The interplay of mineralogical variation and mineral phase distribution within varying particle sizes on the dissolution behaviour of a low grade complex sulphide ore was investigated through bioleaching experiments and electrochemical technique. Investigations were carried out utilizing mineralogical data on the variations in mineral and phase distribution within particle sizes of hilic cultures of Acidithiobacillus ferrooxidans,Acidithiobacillus thiooxidans and Leptospirillum *** behaviour was studied using particulate electrodes from the four varying particle sizes and from massive electrodes prepared from the two major sulphide mineral rich phases(sphalerite-rich and galena-rich)and a complex mineralogical phase of the bulk *** studies reveal the highest recoveries at a particle size of 75μm,while electrochemical investigations reveal the highest dissolution at particle size of 106μ*** results show that sphalerite rich phase has the highest dissolution rate while galena-rich complex phase has the *** studies confirm the highest bacterial attack at the sphalerite-rich *** discrepancies between the dissolutions within particle sizes obtained from bioleaching experiments and electrochemical studies are consistent with and attributed both to the physical and mineralogical *** behaviour is influenced and controlled by galvanic interaction resulting from mineralogical variation, while bioleaching behaviour is influenced by mineralogical variation as well as physical effect of particle size.

关键词：复杂硫化矿化学研究颗粒大小低品位浸出用电互作矿物

Study on the pre-treatment of oxidized zinc ore prior to flotation

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International journal of Minerals,Metallurgy and Materials 2018年第2期25卷 117-122页

作者： Dong-sheng he Yun Chen Ping Xiang Zheng-jun Yu j.h.potgieter School of Resource and Civil Engineering Wuhan Institute of TechnologyWuhan 430205China hunan huaqi Resources and Environment Science&Technology Development Co.Ltd. Zhuzhou 412005China School of Chemical and Metallurgical Engineering University of the WitwatersrandJohannesburg 2050South Africa

The pre-treatment of zinc oxide bearing ores with high slime content is important to ensure that resources are utilized optimally. This paper reports an improved process using hydrocyclone de-sliming, dispersion reagents, and magnetic removal of iron minerals for the pre-treatment of zinc oxide ore with a high slime and iron content, and the benefits compared to traditional technologies are shown. In addition, this paper investigates the damage related to fine slime and iron during zinc oxide flotation, the necessity of using hydrocyclone de-sliming together with dispersion reagents to alleviate the influence of slime, and interactions among hydrocyclone de-sliming, reagent dispersion, and magnetic iron removal. Results show that under optimized operating conditions the entire beneficiation technology results in a flotation concentrate with a Zn grade of 34.66% and a recovery of 73.41%.

关键词： zinc oxide ores flotation hydrocyclone de-sliming magnetic deferrization

A functional tacrolimus-releasing nerve wrap for enhancing nerve regeneration following surgical nerve repair

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Neural Regeneration Research 2025年第1期20卷 291-304页

作者： Simeon C.Daeschler Katelyn j.W.So Konstantin Feinberg Marina Manoraj jenny Cheung jennifer Zhang Kaveh Mirmoeini jPaul Santerre Tessa Gordon Gregory hBorschel SickKids Research Institute Neuroscience and Mental Health ProgramTorontoONCanada Institute of Biomaterials and Biomedical Engineering University of TorontoTorontoONCanada Indiana University School of Medicine IndianapolisINUSA Division of Plastic and Reconstructive Surgery the Hospital for Sick ChildrenTorontoONCanada Translational Biology and Engineering Program Ted Rogers Centre for Heart ResearchInstitute of Biomedical EngineeringFaculty of DentistryUniversity of TorontoTorontoONCanada

Axonal regeneration following surgical nerve repair is slow and often incomplete,resulting in poor functional recovery which sometimes contributes to lifelong ***,there are no FDA-approved therapies available to promote nerve *** accelerates axonal regeneration,but systemic side effects presently outweigh its potential benefits for peripheral nerve *** authors describe herein a biodegradable polyurethane-based drug delivery system for the sustained local release of tacrolimus at the nerve repair site,with suitable properties for scalable production and clinical application,aiming to promote nerve regeneration and functional recovery with minimal systemic drug *** is encapsulated into co-axially electrospun polycarbonate-urethane nanofibers to generate an implantable nerve wrap that releases therapeutic doses of bioactive tacrolimus over 31 *** and drug loading are adjustable for applications in small and large caliber nerves,and the wrap degrades within 120 days into biocompatible *** released from the nerve wrap promotes axon elongation in vitro and accelerates nerve regeneration and functional recovery in preclinical nerve repair models while off-target systemic drug exposure is reduced by 80%compared with systemic *** its surgical suitability and preclinical efficacy and safety,this system may provide a readily translatable approach to support axonal regeneration and recovery in patients undergoing nerve surgery.

关键词： biodegradable local drug delivery nerve injury nerve regeneration nerve wrap tacrolimus

high-Throughput Phenotyping of Dynamic Canopy Traits Associated with Stay-Green in Grain Sorghum

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Plant Phenomics 2020年第1期2卷 269-278页

作者： j.D.Liedtke C.h.hunt B.George-jaeggli K.Laws j.Watson A.B.potgieter A.Cruickshank D.R.jordan University of hohenheim 70593 StuttgartGermany Agri-Science Queensland Department of Agriculture and FisheriesWarwickQLD 4370Australia Queensland Alliance for Agriculture and Food Innovation The University of QueenslandWarwickQLD 4370Australia Queensland Alliance for Agriculture and Food Innovation The University of QueenslandGatton CampusToowoomba QLD 4343Australia

Drought is a recurring phenomenon that puts crop yields at risk and threatens the livelihoods of many people around the ***-green is a drought adaption phenotype found in sorghum and other *** expressing this phenotype show less drought-induced senescence and maintain functional green leaves for longer when water limitation occurs during grain fill,conferring benefits in both yield per se and *** physiological causes of the phenotype are postulated to be water saving through mechanisms such as reduced canopy size or access to extra water through mechanisms such as deeper *** sorghum breeding programs,stay-green has traditionally been assessed by comparing visual scores of leaf senescence either by identifying final leaf senescence or by estimating rate of leaf *** this study,we compared measurements of canopy dynamics obtained from remote sensing on two sorghum breeding trials to stay-green values(breeding values)obtained from visual leaf senescence ratings in multienvironment breeding trials to determine which components of canopy development were most closely linked to the stay-green ***,canopy size as estimated using preflowering canopy parameters was weakly correlated with stay-green values for leaf senescence while postflowering canopy parameters showed a much stronger association with leaf *** study suggests that factors other than canopy size have an important role in the expression of a stay-green phenotype in grain sorghum and further that the use of UAVs with multispectral sensors provides an excellent way of measuring canopy traits of hundreds of plots grown in large field trials.

关键词： breeding drought hundreds

Plasma density measurement and downstream etching of silicon and silicon oxide in Ar/NF3 mixture remote plasma source

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Plasma Science and Technology 2019年第6期21卷 52-57页

作者： h j YEOM D h ChOI Y S LEE j h KIM D j SEONG S j YOU h C LEE Korea Research Institute of Standards and Science(KRISS) Daejeon 34113 Republic of Korea Department of Physics Chungnam National University Daejeon 34134 Republic of Korea

In this study,plasma density measurements were performed near the plume region of the remote plasma source (RPS) in Ar/NF3 gas mixtures using a microwave cutoff *** measured plasma density is in the range of 1010-1011 cm-3 in the discharge conditions with RPS powers of 2-4 kW and gas pressures of 0.87-4 *** plasma density decreased with increasing gas pressures and RPS powers under various Ar/NF3 mixing *** decrease in the plasma density measured at the fixed measurement position (plume region) can be understood by the reduction of the electron energy relaxation length with increases in the gas pressures and mixing ratio of NF3/(Ar/NF3).We also performed downstream etching of silicon and silicon oxide films in this *** etch rate of the silicon films significantly increases while the silicon oxide is slightly etched with the gas pressures and *** was also found that the etch rate strongly depends on the wafer position on the processing chamber electrode,and that the etch selectivity reached 96-131 in the discharge conditions of RF powers (3730-4180 W) and gas pressures (3.6-4 Torr).

关键词： remote plasma source electron density cutoff probe downstream etch

A structural topological optimization method for multi-displacement constraints and any initial topology configuration

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Acta Mechanica Sinica 2010年第5期26卷 735-744页

作者： j. h. Rong j. h. Yi School of Automotive and Mechanical Engineering Changsha University of Science and TechnologyChangsha 410076 China

In density-based topological design, one expects that the final result consists of elements either black （solid material） or white （void）, without any grey areas. Moreover, one also expects that the optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization method for multidisplacement constraints is proposed in this paper. In the proposed method, the whole optimization process is divided into two optimization adjustment phases and a phase transferring step. Firstly, an optimization model is built to deal with the varied displacement limits, design space adjustments, and reasonable relations between the element stiffness matrix and mass and its element topology variable. Secondly, a procedure is proposed to solve the optimization problem formulated in the first optimization adjustment phase, by starting with a small design space and advancing to a larger deign space. The design space adjustments are automatic when the design domain needs expansions, in which the convergence of the proposed method will not be affected. The final topology obtained by the proposed procedure in the first optimization phase, can approach to the vicinity of the optimum topology. Then, a heuristic algorithm is given to improve the efficiency and make the designed structural topology black/white in both the phase transferring step and the second optimization adjustment phase. And the optimum topology can finally be obtained by the second phase optimization adjustments. Two examples are presented to show that the topologies obtained by the proposed method are of very good 0/1 design distribution property, and the computational efficiency is enhanced by reducing the element number of the design structural finite model during two optimization adjustment phases. And the examples also show that this method is robust and practicable.

关键词： Topological optimization Displacement constraint Continuum structure Design space adjustment Rational approximation material model

Large signal of h → μτ within the constraints of e_(i) → e_(j)γ decays in the 3-3-1 model with neutral leptons

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Chinese Physics C 2022年第12期46卷 106-125页

作者： h.T.hung D.T.Binh h.V.Quyet Department of Physics Hanoi Pedagogical University 2Phuc YenVinh Phuc 15000Vietnam Institute of Theoretical and Applied Research Duy Tan UniversityHanoi 10000Vietnam Faculty of Natural Science Duy Tan UniversityDa Nang 50000Vietnam

In the framework of the 3-3-1 model with neutral leptons,we investigate lepton-flavor-violating sources based on the higgs mass spectrum,which has two neutral higgs identified with the corresponding ones of the two-higgs-doublet *** note that at the 13TeV scale of the LhC,the parameter space regions satisfy the experimental limits of e_(i)→e_(j)γ*** regions depend heavily on the mixing of exotic leptons but are predicted to have large h_(1)^(0)→μτ*** also show that Br(h_(1)^(0)→μτ)can reach a value of 10^(-4).

关键词： higgs boson electroweak interaction beyond the SM LFV decays

Optimal use of mobile cooling units in a deep-level gold mine

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International journal of Mining Science and Technology 2020年第4期30卷 547-553页

作者： h.j.van Staden j.F.van Rensburg h.j.Groenewald Centre for Research and Continued Engineering Development North-West UniversityPretoria 0081South Africa

The South African gold mining sector remains a significant contributor to the country’s *** several challenges that hinder the realisation of South Africa’s full mineral potential,the sector’s sustainability and profitability can be enhanced through implementing operational improvement *** cooling units(MCUs)were identified as a potential focus area for operational *** are used as tertiary or in-stope cooling in hot underground *** this paper,a method was presented to characterise the performance of existing MCUs based on three key performance indicators(KPIs),namely,the wet-bulb temperature ratio(WTR),efficiency and *** strategies were then elected and implemented based on these *** implementation of this method in a South African gold mine attained a reduction in pumped water volumes,reduced operating costs through electricity cost savings and improvements in underground ventilation air temperatures.

关键词： Mobile cooling units Optimisation Mine cooling performance Electricity cost savings Spot cooling

MODIFICATION OF SODIUM SALT OF PARTIALLY CARBOXYMEThYLATED TAMARIND KERNEL POWDER ThROUGh GRAFTING WITh ACRYLONITRILE: SYNThESIS, ChARACTERIZATION AND SWELLING BEhAVIOR

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Chinese journal of Polymer Science 2013年第12期31卷 1670-1684页

作者： j.h.Trivedi j.R.jivani K.h.Patel h.C.Trivedi P.G.Dept.of Chemistry Sardar Patel UniversityVallabh Vidyanagar Amneal Phamaceuticals

A graft copolymer of polyacrylonitrile （PAN） with sodium salt of partially carboxymethylated tamarind kernel powder （Na-PCMTKP, DS ^-= 0.15） was synthesized by using ceric ammonium nitrate （CAN） as a redox initiator in an aqueous medium. The optimum reaction conditions for affording maximum percentage of grafting were established by successively varying reaction conditions such as concentrations of nitric acid, CAN, monomer （AN） as well as reaction time, temperature and amount of substrate. The influence of these reaction conditions on the grafting yields was discussed. The kinetic scheme of free radical graft copolymerization was proposed and the experimental results were found to agree very well with the proposed kinetic scheme. The graft copolymer （Na-PCMTKP-g-PAN, percentage of grafting G = 413.76% and percentage of grafting efficiency GE = 96.48%） sample synthesized under the established optimized reaction conditions was hydrolyzed by 0.7 mol-L l NaOh solution at 90-95 ℃ to yield the superabsorbent hydrogel, h-Na-PCMTKP-g-PAN. The swelling behavior of the hydrogel was studied by carrying out its absorbency measurements in low conductivity water, 0.15 mol·L^-1 salt （NaCl, CaCl2 and AlCl3） solutions and simulated urine （SU） solution at different timings. FTIR, TGA and SEM techniques were used to characterize the products.

关键词： Sodium salt of partially carboxymethylated tamarind kernel powder Acrylonitrile Graft copolymerization Superabsorbent hydrogels Swelling behavior.