检索结果-南通市图书馆

Soil Organic Carbon and Its Fractions Across Vegetation Types:Effects of Soil Mineral Surface Area and Microaggregates

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2009年第2期19卷 258-264页

作者： wu Qing-biao WANG Xiao-Ke OUYANG Zhi-Yun Forestry College of Guangxi University Nanning 530004 China Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Soil organic carbon(SOC)can act as a sink or source of atmospheric carbon dioxide;therefore,it is important to understand the amount and composition of SOC in terrestrial ecosystems,the spatial variation in SOC,and the underlying mechanisms that stabilize *** this study,density fractionation and acid hydrolysis were used to assess the spatial variation in SOC,the heavy fraction of organic carbon(HFOC),and the resistant organic carbon(ROC)in soils of the southern Hulun Buir region,northeastern China,and to identify the major factors that contribute to this *** results showed that as the contents of clay and silt particles(0–50μm)increased,both methylene blue(MB)adsorption by soil minerals and microaggregate contents increased in the 0–20 and 20–40 cm soil layers(P<0.05).Although varying with vegetation types,SOC,HFOC,and ROC contents increased significantly with the content of clay and silt particles, MB adsorption by soil minerals,and microaggregate content(P<0.05),suggesting that soil texture,the MB adsorption by soil minerals,and microaggregate abundance might be important factors influencing the spatial heterogeneity of carbon contents in soils of the southern Hulun Buir region.

关键词： carbon fractions microaggregates soil mineral surface area soil organic carbon vegetation

Mechanism of Mg2+ dissolution from olivine and serpentine: Implication for bioleaching of high-magnesium nickel sulfide ore at elevated pH

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1069-1079页

作者： Jian-zhi Sun Jian-kang Wen Bo-wei Chen biao wu National Engineering Laboratory of Biohydrometallurgy GRINM Group Corporation Limited

To inhibit the dissolution of Mg^2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bioleaching factors on the dissolution of Mg^2+ from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg^2+ from olivine and serpentine was temperature, followed by p H and particle size. A novel method of bioleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg^2+ and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.

关键词： olivine serpentine high-magnesium nickel sulfide ore bioleaching shrinking core model elevated pH

A novel approach to extract Nb,Y and Ce from a niobium-bearing ore of low grade by roasting KHSO_(4)-H_(2)SO_(4) system

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第7期40卷 1979-1986页

作者： Wen-Cheng Gao Jian-Kang Wen biao wu He Shang Xue Liu National Engineering Laboratory of Biohydrometallurgy GRIMAT Engineering Institute Co.LtdBeijing 101407China GRINM Resources and Environment Tech.Co. LtdBeijing 101407China

In this work,a novel approach of leaching valuable metals,such as niobium,yttrium and cerium,from a niobium-bearing ore of low grade by roasting KHSO_(4)-H_(2)SO_(4)system was experimentally *** the work,the effects of roasting temperature,roasting time,mass ratio of agents to ore and the types of leaching agents on the extraction of Nb,Y and Ce were investigated,and the roasting KHSO_(4)-H_(2)SO_(4)-ore system was thought as an effective method to extract these valuable *** was found that the recovery of Nb,Y and Ce can,respectively,reach 90.20%,97.22%and 98.41%in condition of roasting temperature of 300℃,roasting time of 2 h,mass ratio of KHSO_(4)-to-H_(2)SO_(4)to ore of 0.5:1:1,particle size of-74 lm(~95%),leaching solution of oxalic acid(30 g·L^(-1)),leaching temperature of 90℃and leaching liquid-to-solid ratio of 5:*** leaching kinetics of the calcined Nb-bearing ore in oxalic acid solution was successfully modeled by chemical reaction model,and the apparent activity energy was obtained to be14.16 kJ·mol^(-1).The results generated from this work will provide the fundamentals for extracting Nb,Y and Ce from a niobium-bearing ore of low grade and have potential applications value in future.

关键词： Roasting Extraction Niobium Yttrium Cerium Low grade

Construction of maximally localized Wannier functions

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2017年第5期12卷 51-55页

作者： Junbo Zhu Zhu Chen biao wu International Center for Quantum Materials School of Physics Peking University Beijing 100871 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China Wilczek Quantum Center College of Science Zhejiang University of Technology Hangzhou 310014 China Synergetic Innovation Center for Quantum Effects and Applications （SICQEA） Hunan Normal University Changsha 410081 China

We present a general method for constructing maximally localized Wannier functions. It consists of three steps：（i） picking a localized trial wave function, （ii） performing a full band projection, and （iii） orthonormalizing with the LSwdin method. Our method is capable of producing maximally localized Wannier functions without further minimization, and it can be applied straightforwardly to random potentials without using supercells. The effectiveness of our method is demonstrated for both simple bands and composite bands.

关键词： Wannier function random potential~ cold atomic gases

Biodegradability of terephthalic acid in terylene artificial silk printing and dyeing wastewater

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2003年第3期15卷 296-301页

作者： GUAN Bao-hong wu Zhong-biao wu Zu-ceng XU Gen-liang TAN Tian-en Department of Environmental Engineering Zhejiang UniversityHangzhou 310027China.

As the characteristic pollutant, terephthalic acid(TA)was in charge of 40%—78% of the total COD of terylene artificial silk printing and dyeing wastewater(TPW-water). The studies on biodegradability of TA were conducted in a serial of activated sludge reactors with TPW-water. TA appeared to be readily biodegradable with removal efficiency over 96.5% under aerobic conditions, hardly biodegradable with removal efficiency below 10% under anoxic conditions and slowly biodegradable with a turnover between 31.4% and 56.0% under anaerobic conditions. TA also accounted for the majority of BOD in TPW-water. The process combined by anoxic, anaerobic and aerobic activated sludge reactor was suitable for TA degradation and TPW-water treatment. Further, the aerobic process was essentially much more effective than the anaerobic or anoxic one to degrade TA in TPW-water.

关键词： terephthalic acid biodegradability bio-treatment printing and dyeing wastewater terylene artificial silk

PdSe_(2)/MoSe_(2) vertical heterojunction for self-powered photodetector with high performance

在线全文

学校读者我要写书评

暂无评论

Nano Research 2022年第3期15卷 2489-2496页

作者： Jiahong Zhong biao wu Yassine MADOUNE Yunpeng Wang Zongwen Liu Yanping Liu School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast ProcessCentral South UniversityChangsha 410083China State Key Laboratory of High-Performance Complex Manufacturing Central South UniversityChangsha 410083China School of Chemical and Biomolecular Engineering The University of SydneyNSW 2006Australia The University of Sydney Nano Institute The University of SydneyNSW 2006Australia Shenzhen Research Institute of Central South University A510aVirtual University BuildingSouthern DistrictHigh-tech Industrial ParkYuehai StreetNanshan DistrictShenzhen 518057China

Van der Waals’two-dimensional(2D)material heterostructure engineering offers an effective strategy for the design of multifunctional and high-performance optoelectronic ***,2D heterostructure photodetectors with a photoconductive effect tend to suffer from high driving source-drain voltages and significant dark noise ***,a self-powered photodetector with high performance was fabricated based on vertically stacked graphene/MoSe_(2)/PdSe_(2)/graphene heterojunctions through a dry transfer *** fabricated device displays current rectification characteristics in darkness(on/off ratio>10^(3))and superior photovoltaic behaviors under *** addition,benefitting from the strong built-in field,the Gr/PdSe_(2)/MoSe_(2)/Gr heterojunction photodetector is able to respond to a broad spectrum from visible to near-infrared(NIR)with a remarkable responsivity of 651 mA·W^(−1),a high specific detectivity of 5.29×10^(11) Jones and a fast response speed of 41.7/62.5μ***,an enhanced responsivity of 1.16 A·W^(−1) has been obtained by a reverse voltage(−1 V)and further evaluation on image recognition has also demonstrated the great application potential of the Gr/MoSe_(2)/PdSe_(2)/Gr heterojunction *** findings are expected to bring new opportunities for the development of highly sensitive,high-speed and energy-efficient photodetectors for comprehensive applications.

关键词： heterostructure MoSe_(2) PdSe_(2) self-powered photodetector high performance

Joining of SiO2f/SiO2 composite to Nb using Ag-Cu-In-Ti brazing alloys

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第15期47卷 13-20页

作者： Bo Chen Wen-Jiang Zou Wen-Wen Li Shi-biao wu Hua-Ping Xiong Xin wu Welding and Plastic Forming Division Beijing Institute of Aeronautical MaterialsBeijing100095China

Three compositions of Ag-Cu-In-Ti system brazing alloys were designed for joining SiO2 f/SiO2 ceramic composite to Nb *** wettability of the three alloys on the composite was studied with the sessile drop *** results showed that after heating at 1073 K for 30 min,they exhibited contact angles of 74°,83° and 86°,*** brazing alloys were fabricated into foils by rapid solidification *** the three brazing filler alloys the joints brazed with AgCu-10 In-5 Ti at 1073 K for 10 min presented the maximum average shear strength of 30.9 *** the brazing process the active element Ti diffused strongly from the filler alloy to the composite surface and a reaction layer with a thickness of 2-3 μm was *** metallurgical bonding was also achieved at the Nb *** interface structure of the joint brazed with the AgCu-10 In-5 Ti alloy can be described as the following sequence:SiO2 f/SiO2→SiO2+Cu3 Ti3 O→SiO2+TiO+Ti5 Si4→Ag(s,s)+(Cu-Ti)→***,for the filler alloy with 4.0 wt% Ti content the joint strength was only 15.8 MPa.

关键词： Joining Composites Strength SiO2

Observation of interlayer excitons in trilayer type-Ⅱ transition metal dichalcogenide heterostructures

在线全文

学校读者我要写书评

暂无评论

Nano Research 2022年第10期15卷 9588-9594页

作者： biao wu Haihong Zheng Junnan Ding Yunpeng Wang Zongwen Liu Yanping Liu School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast ProcessCentral South UniversityChangsha 410083China State Key Laboratory of High-Performance Complex Manufacturing Central South UniversityChangsha 410083China School of Chemical and Biomolecular Engineering The University of SydneyNSW 2006Australia Shenzhen Research Institute of Central South University Shenzhen 518057China

Vertically stacked transition metal dichalcogenide(TMD)heterostructures provide an opportunity to explore optoelectronic properties within the two-dimensional *** such structures,spatially indirect interlayer excitons(IXs)can be generated in adjacent layers because of strong Coulomb ***,due to the complexity of the multilayered heterostructure(HS),the capture and study of the IXs in trilayer type-Ⅱ HSs have so far remained ***,we present the observation of the IXs in trilayer type-Ⅱ staggered band alignment of MoS_(2)/MoSe_(2)/WSe_(2) van der Waals(vdW)HSs by photoluminescence(PL)*** central energy of IX is 1.33 eV,and the energy difference between the extracted double peaks is 23 *** confirmed the origin of IX through PL properties and calculations by the density functional theory,we also studied the dependence of the IX emission peak on laser power and ***,the polarization-resolved PL spectra of HS were also investigated,and the maximum polarizability of the emission peak of WSe_(2) reached 11.40%at 6 *** findings offer opportunities for the study of new physical properties of excitons in TMD HSs and therefore are valuable for exploring the potential applications of TMDs in optoelectronic devices.

关键词： transition metal dichalcogenides interlayer exciton type-II band alignment trilayer heterostructure

Convergence ball and error analysis of Ostrowski-Traub’s method

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2010年第3期25卷 374-378页

作者： BI Wei-hong wu Qing-biao REN Hong-min Department of Mathematics Zhejiang University Hangzhou 310027 China Department of Information and Electronics Hangzhou Radio and TV University Hangzhou 310012 China

Under the hypotheses that the second-order and third-order derivatives of a function are bounded, an estimate of the radius of the convergence ball of Ostrowski-Traub＇s method is obtained. An error analysis is given which matches the convergence order of the method. Finally, two examples are provided to show applications of our theorem.

关键词： Ostrowski-Traub's method nonlinear equation convergence ball estimate of radius error analysis