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Science China(Technological Sciences) 2018年第8期61卷 1217-1227页

作者： JU Yang LIU Peng ZHANG DongShuang DONG JiaBin RANJITH P.G. chang chun State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology School of Mechanics and Civil Engineering China University of Mining & Technology School of Resources and Safety Engineering China University of Mining & Technology Institute of Mechanics Chinese Academy of Science Department of Civil Engineering Monash University

The understanding and prediction of preferential fluid flow in porous media have attracted considerable attention in various engineering fields because of the implications of such flows in leading to a non-equilibrium fluid flow in the subsurface. In this study, a novel algorithm is proposed to predict preferential flow paths based on the topologically equivalent network of a porous structure and the flow resistance of flow paths. The equivalent flow network was constructed using Poiseuille's law and the maximal inscribed sphere algorithm. The flow resistance of each path was then determined based on Darcy's law. It was determined that fluid tends to follow paths with lower flow resistance. A computer program was developed and applied to an actual porous structure. To validate the algorithm and program, we tested and recorded two-dimensional(2 D) water flow using an ablated Perspex sheet featuring the same porous structure investigated using the analytical calculations. The results show that the measured preferential flow paths are consistent with the predictions.

关键词： preferential flow porous structure topological networks flow resistance Darcy's law experimental validation

Urban-Rural Disparity in Mortality Patterns of Respiratory Diseases Among Older Adults—China,1987-2021

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China CDC weekly 2023年第50期5卷 1125-1130页

作者： Panliang Zhong Yihao Zhao Yi Cao Chen Chen Junqing Xie chun chang School of Population Medicine and Public Health Chinese Academy of Medical Sciences/Peking Union Medical CollegeBeijingChina Department of Chronic Diseases School of Population Medicine and Public HealthChinese Academy of Medical Sciences/Peking Union Medical CollegeBeijingChina Center for Statistics in Medicine NDORMSUniversity of OxfordOxfordUK Department of Respiratory and Critical Care Medicine Peking University Third HospitalBeijingChina

What is already known about this topic?Respiratory diseases(RDs)are the primary cause of death in older adults in ***,there is limited evidence regarding the disparity in mortality rates of RDs between urban and rural areas among the elderly *** is added by this report?The age-standardized mortality rate(ASMR)due to RDs in the elderly population in both urban and rural areas of China has shown a consistent *** trend is observed in both males and ***,there was no significant change in the average annual percentage of ASMR for pneumonia among the urban elderly population and rural elderly men throughout the study *** are the implications for public health practice?Efforts should be made in China to reduce mortality from chronic lower respiratory disease and pneumonia among the elderly,particularly in urban populations.

关键词： mortality diseases death

Semi-industrial experimental study on bauxite separation using a cell-column integration process

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International Journal of Minerals,Metallurgy and Materials 2016年第1期23卷 7-15页

作者： Ning-ning Zhang chang-chun Zhou Long-fei Cong Wen-long Cao You Zhou School of Chemical Engineering and Technology China University of Mining & Technology Xuzhou 221116 China Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education) Xuzhou 221116 China

The cyclonic-static micro-bubble flotation column （FCSMC） is a highly efficient mineral processing equipment. In this study, a cell-column （FCSMC） integration process was investigated for the separation of bauxite and its feasibility was analyzed on a theoretical basis The properties of low-grade bauxite ore from Henan Province, China were analyzed. Parameters such as reagent dosage, scraping bubble time, and pressure of the circulating pump during the sorting process were investigated and optimized to improve the flotation efficiency. On the basis of these parameters, continuous separation experiments were conducted. Bauxite concentrate with an aluminum-to-silicon （A/S） mass ratio of 6.37 and a 77.63wt% recovery rate were achieved via a flow sheet consisting of ＂fast flotation using a flotation cell, one roughing flotation and one cleaning flotation using flotation columns＂. Compared with the full-flotation-cells process, the cell-column integration process resulted in an increase of the A/S ratio by 0.41 and the recovery rate by 17.58wt%. Cell-coltmm integration separation technology represents a new approach for the separation of middle-to-low-grade bauxite ore.

关键词： bauxite separation flotation flotation columns flotation cells

Altitudinal trends in δ^13C value,stomatal density and nitrogen content of Pinus tabuliformis needles on the southern slope of the middle Qinling Mountains,China

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Journal of Mountain Science 2016年第6期13卷 1066-1077页

作者： LIU Xian-zhao GAO chang-chun SU Qing ZHANG Yong Song Yan College of Architecture and Urban Planning Hunan University of Science and TechnologyXiangtan 411201China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China College of Life Science Hunan University of Science and TechnologyXiangtan 411201China

In this study,a coniferous tree species(Pinus tabuliformis Carr.) was investigated at a moderate-altitude mountainous terrain on the southern slope of the middle Qinling Mountains(QLM) to detect the trends in carbon isotope ratio( δ^(13)C),leaf nitrogen content(LNC) and stomatal density(SD) with altitude variation in northsubtropical humid mountain climate zone of *** results showed that LNC and SD both significantly increased linearly along the altitudinal gradient ranging from 1000 to 2200 m,whereas leafδ^(13)C exhibited a significantly negative correlation with the *** a correlation pattern differs obviously from that obtained in offshore low-altitude humid environment or inland high-altitude semi-arid environment,suggesting that the pattern of increasing δ^(13)C with the altitude cannot be *** negative correlation between δ ^(13)C and altitude might be attributed mainly to the strengthening of carbon isotope fractionation in plants caused by increasing precipitation with ***,there was a remarkable negative correlation between leaf δ ^(13)C and *** possible reason was that increasing precipitation that operates to increase isotopic discrimination with altitude overtook the LNC in determining the sign of leaf δ ^(13)*** significant negative correlation between leaf δ ^(13)C and SD over altitudes was also found in the present study,indicating that increases in SD with altitude would reduce,rather than enhance plant δ^(13)C values.

关键词： Carbon isotope ratio Nitrogen content Stomatal density Altitudinal variation QinlingMountains

Prospects of Carboniferous Shale Gas Exploitation in the Eastern Qaidam Basin

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Acta Geologica Sinica(English Edition) 2014年第2期88卷 620-634页

作者： LI Yingjie SUN Yanling ZHAO Yan chang chun YU Qingchun MA Yinsheng School of Water Resources and Environment China University of Geosciences Institute of Geomechanics Chinese Academy of Geological Sciences

Shale gas is a resource of emerging importance in the energy *** countries in the world have been making big financial investments in this *** shale in the eastern Qaidam Basin shows good exploration prospects,but limited research and exploration work for shale oil and gas resources has been *** analyses were performed on shale derived from the Upper Carboniferous Hurleg Formation in the eastern Qaidam Basin,Qinghai Province,and secondary electron imaging capability of a Field Emission scanning electron microscope （FE-SEM） was used to characterize the microstructure of the *** reservoir and exploitation potential of the studied shale was assessed by comparison with research results obtained from the Barnett Formation shale in Fort Worth Basin,North America and the Basin shale of Sichuan *** results indicate that the eastern Qaidam Basin Carboniferous shale is high-quality source *** are four major microstructural types in the study area：matrix intergranular pores,dissolution pores,intergranular pores,and *** size of the micropores varies from 6-633 nm,the majority of which is between 39-200 nm,with a relatively small number of micro-scale pores ranging from 0.13-1 μ*** pore characteristics of the studied shales are similar to the North American and Sichuanese shales,indicating that they have good reservoir *** micropores are present in the organic matter,which is induced by its composition; instead we found an important lamellar structure in the organic *** micropores and microfractures are abundant,and are connected to natural visible cracks that form the network pore system,which controls the storage and migration of shale *** connectivity is favorable for shale gas exploitation,providing great scientific potential and practical value.

关键词： Scanning microscopy pore structure organic geochemistry Carboniferous shale gas Hurleg Formation Qinghai-Tibet plateau

A near-infrared fluorescent probe for monitoring fluvastatin-stimulated endogenous H_2S production

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Chinese Chemical Letters 2017年第2期28卷 218-221页

作者： Li-Li Zhang Hui-Kun Zhu chun-chang Zhao Xian-Feng Gu Key Laboratory for Advanced Materials and Institute of Fine Chemicals East China University of Science and Technology Department of Medicinal Chemistry School of Pharmacy Fudan University

Most reported fluorescent probes have limitations in practical applications in living systems due to the strong autofluorescence background,construction of probes with near-infrared（NIR） fluorescence emission is an accessible approach for addressing this *** here designed a NIR fluorescent probe for monitoring the endogenous production of H2S in living *** designed probe showed significant NIR fluorescence turn-on response to H2S with high selectivity,enabling the sensitive detection ***,the probe could be applied in monitoring the endogenous production of H2S in raw 264.7 *** study showed that fluvastatin can promote the activity of cystathionineγ-lyase（CSE） for generation H2S.

关键词： Fluorescent probe Near-infrared fluorescence emission Endogenous H2S detection Fluvastatin

Investigation on the biodegradation levels of super heavy oils by parameter-striping method and refined Manco scale: a case study from the Chepaizi Uplift of Junggar Basin

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Petroleum Science 2021年第2期18卷 380-397页

作者： Xiang-chun chang Bing-Bing Shi Zhong-Quan Liu Yue Wang You-De Xu College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao266590China Laboratory for Marine Mineral Resources Pilot National Laboratory for Marine Science and TechnologyQingdao266071China Research Institute of Petroleum Exploration and Development Shengli Oil CompanySinopecDongying257001China

The Carboniferous volcanic reservoir in the Chepaizi Uplift became an exploration hot target in recent years for its substantial amount of oils discovered. However, most of the Carboniferous heavy oils were biodegraded to PM7 or higher with orders of magnitude variation in oil viscosities. Two oil groups (I and II) exactly corresponding to the western and eastern Chepaizi Uplift were distinguished according to their source diagnose. Furthermore, three oil families (II1, II2 and II3), with the biodegradation level of PM7, PM8–8+, PM9+, respectively, were classified based on molecular compositions and parameter-stripping method of strongly bioresistant parameters. Allowing for this extremely high biodegradation case, more biodegradation refractory compound class were added to establish a refined Manco scale to quantitatively evaluate the biodegradation extent. Refined Manco number (RMN2) positively correlated with the oil density, NSO contents, and absolute concentrations of diasteranes and gammacerane, negatively correlated with the absolute concentrations of diahopane, summed tricyclic terpanes and pentacyclic terpanes. This refined scale showed higher resolution than the PM one to differentiate the biodegradation extent of Carboniferous heavy oils from the Chepaizi Uplift, especially those with same PM values but different oil viscosities.

关键词： Super heavy oil Biodegradation Parameter-striping method Refined Manco scale Junggar Basin

Enzymatic Conversion of Biobased Levulinic Acid into an Alternative Biofuel Candidate--Methyl Levulinate

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China Petroleum Processing & Petrochemical Technology 2020年第1期22卷 8-16页

作者： Xu Yanli Li Pan chang chun Xu Guizhuan Du Zeji Wang Zihua School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001 Henan Center for Outstanding Overseas Scientists Zhengzhou 450001 College of Mechanical and Electrical Engineering Henan Agricultural UniversityZhengzhou 450002

Methyl levulinate(ML)is a promising green candidate for bio-based diesel fuel and fuel *** efficient enzyme-catalyzed process to synthesize ML from levulinic acid(LA)in methanol was *** catalytic activity of a series of lipases including Novozyme 435(N435),NRTL IM,and 40086 was screened,and the N435 was identified as the optimal biocatalyst for the *** effects of lipase amount,methyl tert-butyl ether(MTBE)volume,methanol to LA molar ratio,reaction temperature,and magnetic stirrer speed on LA conversion and ML yield were *** response surface methodology was adopted to optimize the enzymatic conversion process,and the model validation experiments showed that the predicted values corresponded well with the experimental values.A LA conversion of 90.1%and a ML yield of 89.8%were achieved under reaction conditions covering:a temperature of 45°C,a reaction time of 4.6 h,a N435 dosage of 26 mg,a methanol to LA molar ratio of 3.6:1,a MTBE volume of 3.85 mL,and a stirrer speed of 150 r/*** N435 recycling experiment indicated that the lipase activity was quite high after 12 ***,upon using crude LA prepared from carbohydrates as the reactant,the conversion of LA and the ML yield decreased due to impurities existing in the crude LA.

关键词： enzyme methyl levulinate levulinic acid biomass

Full filling of mesoporous carbon nanotubes by aqueous solution at room temperature

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Chinese Physics B 2019年第3期28卷 304-308页

作者： Xiao-Na Ren Min Xia Qing-Zhi Yan chang-chun Ge School of Materials Science and Technology University of Science and Technology Beijing

Carbon nanotubes(CNTs) have the ideal structure to be used as templates for nanomaterials, especially for nanowires,and the tungsten nanowire is an important nanomaterial that is used as a strengthening phase. Therefore, we have proposed to apply mesoporous CNT(mCNT) as a template to prepare tungsten nanowires. However, the tungsten precursor should fill the hollow tube of mCNT firstly, and very few related studies have been reported. In this paper, we have systematically studied the filling process of ammonium metatungstate(AMT) aqueous solution. The results reveal that owing to the mesopores in the mCNT sidewall, the AMT can be encapsulated into the tube at room temperature(RT) and we can fully fill it without destroying the structure. In addition, vibration and solute concentration are also important factors. Besides,the mesoporous sidewall and hollow tubular core structure of mCNT are prerequisites to realize full filling. Furthermore,tungsten nanowires have been obtained after reduction of AMT in mCNTs.

关键词： mesoporous carbon nanotube(mCNT) capillarity aqueous solution tungsten nanowire

Fabrication of solid-phase-sintered Si C-based composites with short carbon fibers

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International Journal of Minerals,Metallurgy and Materials 2014年第11期21卷 1141-1145页

作者： Xian-hui Li Qing-zhi Yan Yong-jun Han Mei-qi Cao chang-chun Ge Institute of Special Ceramics and Powder Metallurgy University of Science and Technology Beijing

Solid-phase-sintered Si C-based composites with short carbon fibers（Csf/SSi C） in concentrations ranging from 0 to 10wt% were prepared by pressureless sintering at 2100°C. The phase composition, microstructure, density, and flexural strength of the composites with different Csf contents were investigated. SEM micrographs showed that the Csf distributed in the SSi C matrix homogeneously with some gaps at the fiber/matrix interfaces. The densities of the composites decreased with increasing Csf content. However, the bending strength first increased and then decreased with increasing Csf content, reaching a maximum value of 390 MPa at a Csf content of 5wt%, which was 60 MPa higher than that of SSi C because of the pull-out strengthening mechanism. Notably, Csf was graphitized and damaged during the sintering process because of the high temperature and reaction with boron derived from the sintering additive B4C; this graphitization degraded the fiber strengthening effect.

关键词： fiber-reinforced composites silicon carbide carbon fibers solid phase sintering microstructure