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Consolidation mechanism of gold concentrates containing sulfur and carbon during oxygen-enriched air roasting

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International Journal of Minerals,Metallurgy and Materials 2017年第4期24卷 386-392页

作者： Qian Li Fang-zhou Ji Bin Xu Jian-jun Hu Yong-bin Yang Tao Jiang School of Minerals Processing and bioengineering Central South University Changsha 410083 China

Consolidation in calcines is a common problem in the oxygen-enriched air roasting of refractory gold concentrates containing sulfur and carbon when the initial temperature is greater than 600°C. To determine the phases that caused consolidation, gold concentrates were roasted under different conditions and the calcines were mainly detected by X-ray diffraction (XRD). The possible underlying mechanism was then studied through comparisons of the XRD patterns of different calcines. The results indicated that the generation of calcium magnesium silicate, iron-doped calcium aluminosilicate, and calcium aluminate caused the consolidation. Furthermore, an enriched oxygen atmosphere accelerated the oxidation reaction and the emitted heat increased the local temperature in calcines. The local temperature was inferred to have increased to the generation temperature zone of the corresponding liquid phases. Oxidation of the pyrite and decomposition of the dolomite and muscovite mainly occurred at the initial stage of oxygen-enriched air roasting. Calcium was confirmed to be essential to the consolidation process. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

关键词： Calcination Calcium Consolidation Gold Mechanisms Mica Oxygen Silicates Sulfur X ray diffraction

On the development of optical peripheral nerve interfaces

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Neural Regeneration Research 2019年第3期14卷 425-436页

作者： Hans E.Anderson Richard F.ff.Weir Department of bioengineering University of Colorado Denver|Anschutz Medical Campus

Limb loss and spinal cord injury are two debilitating conditions that continue to grow in prevalence. Prosthetic limbs and limb reanimation present two ways of providing affected individuals with means to interact in the world. These techniques are both dependent on a robust interface with the peripheral nerve. Current methods for interfacing with the peripheral nerve tend to suffer from low specificity, high latency and insufficient robustness for a chronic implant. An optical peripheral nerve interface may solve some of these problems by decreasing invasiveness and providing single axon specificity. In order to implement such an interface three elements are required:(1) a transducer capable of translating light into a neural stimulus or translating neural activity into changes in fluorescence,(2) a means for delivering said transducer and(3) a microscope for providing the stimulus light and detecting the fluorescence change. There are continued improvements in both genetically encoded calcium and voltage indicators as well as new optogenetic actuators for stimulation. Similarly, improvements in specificity of viral vectors continue to improve expression in the axons of the peripheral nerve. Our work has recently shown that it is possible to virally transduce axons of the peripheral nerve for recording from small fibers. The improvements of these components make an optical peripheral nerve interface a rapidly approaching alternative to current methods.

关键词： peripheral nerve interfaces optogenetics optical neural interface optical peripheral nerve interface GCaMP ArcLight adenoassociated viral vector lentiviral vectors viral vectors implantable microscopy

Hydrothermal synthesis of zeolites-calcium silicate hydrate composite from coal fly ash with co-activation of Ca(OH)_(2)-NaOH for aqueous heavy metals removal

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International Journal of Mining Science and Technology 2022年第3期32卷 563-573页

作者： Guanghui Li Min Li Xin Zhang Pengxu Cao Hao Jiang Jun Luo Tao Jiang School of Minerals Processing and bioengineering Central South UniversityChangsha 410083China

Coal fly ash is a typical secondary aluminum/silicon *** preparation of zeolite-type absorbent is a potential way for its value-added utilization,while the purity and adsorption property of zeolite are limited due to the occurrence of side reactions in the synthesis *** this study,a designated composite consisted of crystalline zeolites and amorphous calcium silicate hydrate was selected,which was direct synthesized from fly ash under conditions of a Ca/Si molar ratio of 0.8,an initial NaOH concentration of 0.5 mol/L,a hydrothermal temperature of 170℃and a liquid–solid ratio of 15 mL/*** results indicated that this composite had superior adsorption property for a variety of heavy metals,which was based on the exchange of calcium and sodium ions in zeolites and calcium silicate *** adsorption capacities for Pb^(2+),Ni^(2+),Cd^(2+),Zn^(2+),Cu^(2+)and Cr^(3+)attained 409.4,222.4,147.5,93.2,101.1 and 157.0 mg/g,respectively,in single solution with a pH of *** regulating the synthesis conditions,the transformation of amorphous calcium silicate hydrate into crystallized tobermorite weakened the adsorption capacity of the ***,due to the competitive adsorption in a multiple ions solution,the adsorption capacities for these heavy metals had a reduction.

关键词： Coal fly ash Adsorption material Zeolite Calcium silicate hydrate Heavy metals

Surface modification of coconut-based activated carbon by SDS and its effects on Pb^(2+) adsorption

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Journal of Central South University 2013年第5期20卷 1156-1160页

作者：宋晓岚张铭婉张颖黄书涛耿柏杨蒙让彬杨屹朝钟一顺刘宏燕 School of Minerals Processing and bioengineering Central South University

Coconut-based activated carbons were modified with sodium dodecyl sulfate (SDS). The activated carbons, which were modified by different concentrations of SDS, were characterized by acid/base titrations, textural analysis (BET), atomic absorption spectrochemical analysis and Zeta potential measurements. The effects of SDS modification on Pb2+ absorption were studied further. The results indicate that after the modification of SDS, there are new functional groups on the surface of modified activated carbons and the number of functional group has changed remarkably, the total acidity decreases observably, but the total alkalinity increases dramatically. With the increase of surface load with SDS, the Pb2+ adsorption mass of activated carbons increases and the optimal pH for Pb2+ adsorption of the SDS modified activated carbons is 5. The experimental data are simulated better by Freundlich isotherm model for the modified activated carbons, and the experimental data are simulated better by Langmuir isotherm model for unmodified ones.

关键词： activated carbon surface modification sodium dodecyl sulfate Pb2+ absorption

Removal and utilization of calcite existed in scheelite by preparation of calcium sulfate whiskers

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International Journal of Mining Science and Technology 2017年第6期27卷 1005-1010页

作者： Guan Qingjun Sun Wei Hu Yuehua Guan Changping Yin Zhigang Zhang Chenhu School of Mineral Processing and bioengineering Central South University Changsha 410083 China

In order to eliminate the effect of calcite associated with scheelite on the scheelite flotation, hydrochloric acid was used to dissolve the calcite, and the soaking solution was used to prepare CaSO_4 whiskers by hydrothermal reaction with sulfuric acid at ambient pressure. First, the condition experiments of preparing CaSO_4 whiskers by using CaCl_2 and H_2SO_4 were carried out to optimize reaction parameters of the crystallization process. The optimal conditions were: at 102 ℃ reaction temperature, 0,5 mol/L reactant concentration and 60 min reaction time. Then based on the condition experiments and considering keeping acid concentration stable for achieving HCl recycling, Calcium sulfate whiskers with the average diameter of 1.41 μm and the average aspect ratio of 109 were prepared by the soaking solution after evaporating to half of its volume and 1.0 mol/L H_2SO_4 at 102 ℃ for 60 min: After ion exchange processing,the filtrate could be used as HCl in the process of HCl dissolution.

关键词： Calcium sulfate whiskers Scheelite Calcite HCl Hydrothermal reaction

Flotation of kaolinite and diaspore with hexadecyl dimethyl benzyl ammonium chloride

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Journal of Central South University of Technology 2008年第3期15卷 378-381页

作者：胡岳华欧阳魁曹学锋张丽敏 School of Resources Processing and bioengineering Central South University

Tertiary amine was synthesized from fatty amine and formaldehyde. And then the synthesized tertiary amine was used to react with benzyl chloride to synthesize hexadecyl dimethyl benzyl ammonium chloride (1627) at ambient pressure. Using the synthesized 1627 as collector,the flotation properties of diaspore and kaolinite were investigated by single mineral and mixed mineral test. The flotation mechanism of diaspore,kaolinite and 1627 was discussed based on FTIR spectra. The results show that the mass ratio of aluminum to silicate achieves 15.02 and the recovery of alumina in concentrate is 43.07% using 1627 as a collector. The 1627 is found to be a more effective and a promising collector for reverse flotation to remove aluminum-silicate minerals from bauxite.

关键词： kaolinite diaspore hexadecyl dimethyl benzyl ammonium chloride dodecyl amine reverse floatation infra-red spectrum

Efficient Activity Enhancement of a Lipase from Sporisorium reilianum for the Synthesis of a Moxifloxacin Chiral Intermediate via Rational Design

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Engineering 2022年第12期19卷 207-216页

作者： Xue Cai Jiang-Wei Shen Yu Qiang Jing Hua Zhang-Qi Ma Zhi-Qiang Liu Yu-Guo Zheng The National and Local joint Engineering Research Center for Biomanufacturing of Chiral Chemicals Zhejiang University of TechnologyHangzhou 310014China Key Laboratory of Bioorganic Synthesis of Zhejiang Province College of Biotechnology and BioengineeringZhejiang University of TechnologyHangzhou 310014China

Lipase-catalyzed stereoselective resolution of cis-(±)-dimethyl 1-acetylpiperidine-2,3-dicarboxylate(cis-(±)-1)is an attractive route for the synthesis of(S,S)-2,8-diazobicyclo[4.3.0]nonane,an important chiral intermediate of the fluoroquinolone antibiotic,*** our previous study,a lipase from Sporisorium reilianum(SRL)was identified to possess excellent thermostability and pH ***,the low enzymatic activity of the SRL is a challenge that must be addressed.A rational design was initially employed for SRL tailoring according to the engineered Candida antarctica lipase B(CALB),resulting in a beneficial variant called SRL-I194N/***,two key amino acid residues in loop 6,L145 and L154,which might modulate the lid conformation between open and closed,were identified.A tetra-site variant,SRL-I194N/V195L/L145V/L154G(V13),with a significantly enhanced activity of 87.8 U∙mg^(−1) was obtained;this value was 2195-fold higher than that of wild-type *** V13 was used to prepare optically pure(2S,3R)-dimethyl 1-acetylpiperidine-2,3-dicarboxylate((2S,3R)-1),resolving 1 mol∙L^(−1) cis-(±)-1 with a conversion of 49.9%in 2 h and absolute stereoselectivity(E>200).Excellent stability with a half-life of 92.5 h was also observed at 50℃.Overall,the study findings reveal a lipase with high activity toward cis-(±)-1 at an industrial level and may offer a general strategy for enhancing the enzyme activity of other lipases and other classes of enzymes with a lid moiety.

关键词： Lipase Sporisorium reilianum Site-directed mutagenesis Molecular dynamics simulation Rational design Moxifloxacin

Chemical composition and surface charge properties of montmorillonite

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Journal of Central South University of Technology 2008年第2期15卷 193-197页

作者：刘晓文胡敏胡岳华 School of Resources Processing and bioengineering Central South University

The effects of the cell parameter and chemical composition on the surface charge properties of five kinds of different colour montmorillonites were studied. The results indicate that the surface isoelectric point（IEP） of the montmorillonite shows positive correlation with the mass fractions of Fe203 and K20, but it has little relation to the mass fractions of other chemical compositions. At around pH=6.8, the surface zeta potential of the montmorillonite shows the negative relationship with the mass fractions of Fe203 and MgO, but it does not linearly correlate to the mass fractions of other chemical compositions. Cell parameter（bo） of the montmorillonite expresses negative linear relationship with mass fractions of K2O and Na2O, so does cosinβ with mass fractions of SlOE and Fe2O3. And there is no specific relationship between bo and IEP of different montmorillonites, but there is positive correlation between cosinβ and IEP of different montmorillonite samples.

关键词： surface charge property zeta potential cell parameter montmorillonite

Photocatalytic activity of bauxite-tailings supported nano-TiO_2

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Journal of Central South University 2010年第4期17卷 755-759页

作者：卢清华胡岳华王梦 School of Resources Processing and bioengineering Central South University

TiO2/bauxite-tailings （TiO2/BTs） composites were prepared via a chemical liquid deposition method and characterized by X-ray diffractometry （XRD）, scanning electronic microscopy （SEM） and N2 adsorption analysis. The photocatalytic performance of TiO2/BTs composites was evaluated with UV-Vis spectrophotometer following the changes of phenol concentration under different illumination time. Effects of the calcination temperature, the pH and the cycles on the photocatalytic activity of TiO2/BTs composites were investigated. The composites calcined at 500 and 600 ℃ exhibit the best photocatalytic performance, and the phenol degradation ratios reacting for 40 and 160 rain reach 35% and 78% respectively under the same conditions, higher than those of 29% and 76% of the Degussa P25（TiO2）. The ability of TiO2/BTs500 （BTs500 represents bauxite-tailings calcined at 500 ℃） composites to degrade phenol increases with decreasing pH.

关键词： TiO2 bauxite-tailings phenol photocatalytic activity