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Pretreatment and thiosulfate leaching of refractory gold-bearing arsenosulfide concentrates

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Journal of University of Science and Technology Beijing 2005年第5期12卷 385-389页

作者： yuqun Meng Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A hydrometallurgical process for refractory gold-bearing arsenosulfide concentrates at ambient temperature and pressure was presented, including fine grinding with intensified alkali-leaching （FGIAL）, enhanced agitation alkali-leaching （EAAL）, thiosulfate leaching and displacement. Experimental results on a refractory gold concentrate showed that the total consumption of NaOH in alkaline leaching is only 41% of those theoretically calculated under the conditions of full oxidization for the same amount of arse- nides and sulfides transformed into arsenates and sulfates, and 72.3% of gold is synchro-dissoluted by thiosulfate self-generated during alkaline leaching. After alkaline leaching, thiosulfate leaching was carried out for 24 h. The dissolution of gold is increased to 91.9% from 4.6% by cyanide without the pretreatment. The displacement of gold by zinc powder in the solution gets to 99.2%. Due to an amount of thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal.

关键词： refractory gold-bearing arsenosulfide concentrates pretreatment alkaline leaching self-leaching of gold thiosulfate leaching

Response of antioxidase in viscera of Pagrosuma Major larvae to water soluble fraction of hydrocarbons in No.0 diesel oil

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Journal of Environmental Sciences 2003年第1期15卷 47-54页

作者： yuqun ZHENGWei－yun 等 KeyLaboratoryofMarineEnvironmentalScienceforMinistryofEducation EnvironmentalScienceResearchCenterXiamenUniversityXiamen361005China KeyLaboratoryofMarineEnvironmentalScienceforMinistryofEducation E

Pagrosomus major larvae were exposed to the water soluble fraction of hydrocarbon in No.0 diesel oil (corresponding to No.2 fuel oil) at concentrations of 0, 0 17, 1.22 and 8 82 mg/L for up to 15 days. Larvae were sampled on days 9 and l5 of the experiment. Supernatants of viscera tissue extractions were assayed for biochemical response in terms of oxidative stress superoxide dismutase(SOD), activity of selenium dependant glutathione peroxidase(Se GPx) and catalase(Ca), and the concentration of reduced glutathione(GSH). On day 9 of exposure, statistically significant dose related increases in Se GPx and SOD activity, and GSH concentration were observed in all cases except for Se GPx activity under the highest dosage of hydrocarbon. However, on day l5 of exposure, a similar dose related response was only observed for Se GPx activity. GSH concentration decreased and SOD activity showed no statistical difference as compared to controls. However, a significant decrease in compared to day 9 Se GPx activity and GSH concentration, in contrast to increase SOD activity at day 15 as indicates an accelerated accumulation of H 2O 2 and potential oxidative damage under long term exposure of larvae to hydrocarbons. No statistical changes were observed in Ca activity throughout the experiment, possibly owing to the high efficiency of Se GPx. A recovery experiment was performed on indicating that the response of antioxidants measured tending to return to their control levels. These results prove the function of the antioxidant defense system of the larvae to the water soluble fraction of hydrocarbons in No.0 diesel oil.

关键词： antioxidant system water soluble fraction of hydrocarbon Pagrosomus major larvae

On Formulas and Some Combinatorial Properties of Schubert Polynomials

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Algebra Colloquium 2017年第4期24卷 647-672页

作者： Zerui Zhang yuqun Chen School of Mathematical Sciences South China Normal University Guangzhou 510631 China

By applying a Grobner-Shirshov basis of the symmetric group Sn, we give two formulas for Schubert polynomials, either of which involves only nonnegative monomials. We also prove some combinatorial properties of Schubert polynomials. As applications, we give two algorithms to calculate the structure constants for Schubert polynomials, one of which depends on Monk＇s formula.

关键词： divided difference Schubert polynomial Grobner-Shirshov basis

A New Composition-Diamond Lemma for Dialgebras

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Algebra Colloquium 2017年第2期24卷 323-350页

作者： Guangliang Zhang yuqun Chen School of Mathematical Sciences South China Normal University Guangzhou 510631 China

Bokut, Chen and Liu in 2010 gave a Composition-Diamond lemma for dialge- bras. In this paper, by introducing an arbitrary monomial-center ordering, we give a new Composition-Diamond lemma for dialgebras which makes the two conditions in Bokut, Chen and Liu＇s result equivalent. The new lemma is more useful and convenient than the one Bokut, Chen and Liu got. We show that every ideal of the free dialgebra generated by a set X has a unique reduced GrSbner-Shirshov basis. As applications, we give a method to find normal forms of elements of an arbitrary disemigroup, in particular, two Zhuchoks＇ normal forms of the free commutative disemigroups and the free abelian disemigroups, and normal forms of the free left （right） commutative disemigroups.

关键词： GrSbner-Shirshov basis normal form dialgebra disemigroup commutativedise migroup

Adult Neural Stem Cells: Constant Extension from Embryonic Ancestors

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Neuroscience Bulletin 2019年第6期35卷 1120-1122页

作者： yuqun Cai Zhengang Yang State Key Laboratory of Medical Neurobiology Institutes of Brain Science Ministry of Education Frontier Center for Brain Science Department of Neurology Zhongshan Hospital Fudan University

Adult neural stem cells(a NSCs)primarily exist in two regions:the subventricular zone(SVZ)of the lateral ventricle(LV)and the subgranular zone(SGZ)in the hippocampal dentate gyrus(DG)[1].It has been revealed that a NSCs in the SVZ(called type B cells)originate from embryonic NSCs mainly before embryonic day 15.5(E15.5),and are set aside for postnatal neurogenesis after diverging[2,3].

关键词： ventricular ventricle Extension

Numerical Research on the Influence of Deborah Number on Flow and Heat Transfer of Maxwell Fluid in a Tube with Laminar Pulsating Flow

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Journal of Thermal Science 2020年第4期29卷 972-981页

作者： WANG Zhipeng CHENG Shuhao ZHUO yuqun Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Beijing Engineering Research Center for Ecological Restoration and Carbon Fixation of Saline–alkaline and Desert Land Tsinghua UniversityBeijing 100084China China Institute of Atomic Energy Beijing 102413China

The flow and heat transfer characteristics of Maxwell fluid in a pipe under pulsating pressure gradient were studied. The governing equations were made dimensionless. The Rubin boundary condition was adopted. The flow field was solved theoretically and the temperature field was obtained using finite volume method. A general model suitable for various fluctuating characteristics and physical parameters was established. The Deborah number(De) was used to characterize the fluidity of the fluid. The influence of De on flow and temperature fields was evaluated. The Nusselt number and start-up process of Maxwell fluid were studied. Results showed that the influence of De on flow field was greater than that on temperature field. The effect of De on Nusselt number was irregular and related to the oscillation parameters. The over-shooting amplitude and oscillation time of axis center velocity in start-up flow grow larger with De.

关键词： Maxwell fluid pulsating flow Hagen-Poiseuille law Deborah number start-up flow

Fate of mercury in flue gas desulfurization gypsum determined by Temperature Programmed Decomposition and Sequential Chemical Extraction

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Journal of Environmental Sciences 2016年第5期28卷 169-176页

作者： Zhenwu Zhu yuqun Zhuo Yaming Fan Zhipeng Wang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua University

A considerable amount of Hg is retained in flue gas desulfurization（FGD） gypsum from Wet Flue Gas Desulfurization（WFGD） systems. For this reason, it is important to determine the species of Hg in FGD gypsum not only to understand the mechanism of Hg removal by WFGD systems but also to determine the final fate of Hg when FGD gypsum is disposed. In this study, Temperature Programmed Decomposition（TPD） and Sequential Chemical Extraction（SCE） were applied to FGD gypsum to identify the Hg species in it. The FGD gypsum samples were collected from seven coal-fired power plants in China, with Hg concentrations ranging from 0.19 to 3.27 μg/g. A series of pure Hg compounds were used as reference materials in TPD experiments and the results revealed that the decomposition temperatures of different Hg compounds increase in the order of Hg_2Cl_2〈 HgCl_2〈 black HgS 〈 Hg_2SO_4〈 red HgS 〈 HgO 〈 HgSO_4. The Hg compounds existing in FGD gypsums identified by TPD included HgCl_2, Hg_2Cl_2, Hg_2SO_4, black HgS and red HgS, of which mercury sulfides were the primary compounds. The results of SCE indicated that Hg was mainly distributed in the strongly complexed phase. The low Hg content in FGD gypsum increases the ambiguity of assigning extraction fractions to certain Hg species by SCE. The fact that the primary compounds in FGD gypsum are HgS phases leads the leaching of Hg in the natural environment to be quite low, but a considerable amount of Hg may be released during the industrial heating process.

关键词： Mercury speciation FGD gypsum Thermal desorption Sequential Chemical Extraction

Experimental Research on Mercury Catalytic Oxidation over Ce Modified SCR Catalyst

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Energy Engineering 2022年第1期119卷 35-47页

作者： Yadi Qin Qiyu Weng yuqun Zhuo Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing100084China

In order to improve the ability of SCR catalyst to catalyze the oxidation of gaseous elemental mercury,a series of novel Ce modified SCR(Selection Catalytic Reduction,V_(2)O_(5)-WO_(3)/TiO_(2))catalysts were prepared via two-step ultrasonic impregnation *** performance of Ce/SCR catalysts on Hg^(0)oxidation and NO reduction as well as the catalytic mechanism on Hg^(0)oxidation was also *** XRD,BET measurements and XPS were used to characterize the *** results showed that the pore volume and pore size of catalyst was reduced by Ce doping,and the specific surface area decreased with the increase of Ce content in *** performance on Hg^(0)oxidation was promoted by the introduction of CeO_(2).Ce_(1)/SCR(1%Ce,wt.%)catalyst exhibited the best Hg^(0)oxidation activity of 21.2%higher than that of SCR catalyst at 350℃,of which the NO conversion efficiency was also higher at 200-400℃.Furthermore,Ce_(1)/SCR showed a better H_(2)O resistance but a slightly weaker SO_(2)resistance than SCR *** chemisorbed oxygen and weak absorbed oxygen on the surface of catalyst were increased by the addition of CeO_(2).The chemisorbed oxygen and weak absorbed oxygen on the surface of catalyst were increased by the addition of CeO_(2).The Ce_(1)/SCR possed better redox ability compared with SCR *** was the most effective gas responsible for the Hg^(0)oxidation,and the redox cycle(V^(4+)+Ce^(4+)←→V^(5+)+Ce^(3+))played an important role in promoting Hg^(0)oxidation.

关键词： Mercury catalytic oxidation SCR catalyst Ce doping reaction mechanism

Free Products of Trialgebras

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Algebra Colloquium 2024年第1期31卷 25-40页

作者： Juwei Huang yuqun Chen Zerui Zhang School of Mathematics and Statistics Huizhou University HuizhouGuangdong 516007China School of Mathematical Sciences South China Normal University Guangzhou 510631China

We apply the method of Grobner-Shirshov bases for replicated algebras devel-oped by Kolesnikov to offer a general approach for constructing free products of associative trialgebras(or trioids).In particular,the open p... 详细信息

关键词： Grobner-Shirshov basis trialgebra trioid dimonoid free product