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天山北坡中段草地类型α多样性研究

干旱区研究 2005年第2期22卷 225-230页

作者：冯缨许鹏安沙舟刘长娥孙宗玖中国科学院新疆生态与地理研究所新疆乌鲁木齐830011 新疆农业大学草业工程学院新疆乌鲁木齐830052

定量比较天山北坡中段乌鲁木齐地区各草地植被垂直带中具代表性的16个主要草地类型的植物多样性指数、物种丰富度指数和均匀度指数。从各草地类型多样性指数大小来看,山地草甸>草甸草原>典型草原>荒漠草原>亚高山草甸>高寒草甸>荒漠。... 详细信息

定量比较天山北坡中段乌鲁木齐地区各草地植被垂直带中具代表性的16个主要草地类型的植物多样性指数、物种丰富度指数和均匀度指数。从各草地类型多样性指数大小来看,山地草甸>草甸草原>典型草原>荒漠草原>亚高山草甸>高寒草甸>荒漠。其中分布于山地草甸的鸭茅+草原老鹳草+杂类草的草地类型和草原老鹳草+杂类草+禾草的草地类型的物种多样性指数最大,而分布于荒漠带土质生境的散枝猪毛菜+角果藜的草地类型和小蓬草地类型的物种多样性指数最小。其结果反映了生境异质性沿着水、热生态梯度变化的规律;从草地物种多样性的角度,揭示了不同草地类型在组成、结构、功能和动态的差异;通过指数间相关关系的分析,探讨草地类型多样性与草地生产力的相互影响,可为该地区的生物多样性资源保护提供科学依据。

关键词：草地类型天山北坡多样性研究中段物种多样性指数乌鲁木齐地区山地草甸植被垂直带均匀度指数物种丰富度亚高山草甸生境异质性草地生产力生物多样性定量比较高寒草甸荒漠草原典型草原草甸草原梯度变化

The important role of Turbidity Maximum Zone in sedimentary dynamic of estuarine mangrove swamp

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Frontiers of Earth Science 2024年第1期18卷 219-226页

作者： Tao liu Ying liu Baoqing HU Key laboratory of Environment change and Resources Use in Beibu Gulf(Ministry of Education) Nanning Normal UniversityNanning 530001China School of Civil Engineering and Architecture Guangxi UniversityNanning 530004China

Sedimentation is a key process affecting wetland sustainability and carbon burial *** context of sea level rise,climate change and human activities,further understanding about the sedimentary dynamic in wetland is critical in predicting the landscape evolution or the change in carbon burial *** this study,based on the field hydrological observation in a mangrove system in the Nanliu River estuary,we found the net flux of suspended sediment to mangrove is 39−72 kg/m in tidal cycles with Turbidity Maximum Zone(TMZ)forming in surface layer and only is 9−18 kg/m in tidal cycles without *** higher net flux of suspended sediment to mangrove in tidal cycles with TMZ forming in surface layer is attributed to high SSC in rising tide and intense flocculation in *** significant discrepancy in sedimentation rate in the mangrove patches also can be explained by the probability of TMZ forming in the surface layer of *** future,rapid sea level rising may lead to the change of TMZ pattern in estuary,which will result in non-negligible variation in sedimentation rate in *** to the present data of sedimentation rate in wetlands,the fragility of wetlands in river estuary may be miscalculated.

关键词： mangrove wetland sedimentation Turbidity Maximum Zone Nanliu River

Effect of heat treatment on microstructure and mechanical properties of selective laser-melted PH13-8Mo stainless steel

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Journal of Iron and Steel Research International 2024年第4期31卷 945-955页

作者： Yuan Zhang Xiang liu Chang-jun Wang Chang liu School of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093YunnanChina Central Iron&Steel Research Institute Co. Ltd.Beijing 100081China

PH13-8Mo stainless steel powder with high sphericity and well fluidity was prepared by the plasma rotating electrode *** formed parts with ultra-high purity were manufactured by selective laser *** tensile and impact mechanical properties of the printed parts under three heat treatment regimes were compared to those without heat *** microstructure,grain orientation and phase composition were characterized by electron-backscatter diffraction,X-ray diffraction and transmission electron *** characterization results reveal that the addition of heat treatment makes the grains enlarge,and after different heat treatments,the average grain size from 1.51μm in the printed state increases to 2.78,3.09 and 2.06μm,*** formed parts are mainly composed of martensite and retained ***,the NiAl and M23C precipitates form,which are the major strengthening phases of PH13-8Mo stainless *** optimal heat treatment process is 925℃×1 h water cooling(WC)+0℃×2 h air cooling(AC)+540℃×4 h *** this heat treatment process,PH13-8Mo formed parts have the optimal comprehensive mechanical properties:the tensile strength,yield strength and impact energy KU2 are 1492 MPa,1432 MPa and 63 J,*** strengthening and toughening via heat treatment are mainly attributed to dislocation strengthening,the formation of NiAl and M23Co precipitates and the change of volume fraction of the retained austenite.

关键词： High-strength stainless steel-Selective laser melting-Heat treatment Microstructure Mechanical property

Asymmetrically coordinated single atom Cu catalyst with unsaturated C-Cu-N structure for CO_(2) reduction to CO

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Nano Research 2024年第5期17卷 3911-3918页

作者： Zheng liu Yuxuan liu Jingqiao Zhang Ting Cao Zhiyi Sun Juzhe liu Huishan Shang State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China SEPA Key Laboratory of Eco-Industry Chinese Research Academy of Environmental SciencesBeijing 100012China The Key Laboratory of Resources and Environmental System Optimization Ministry of EducationCollege of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China

Single atom catalysts(SACs)play a crucial role in energy catalysis due to their distinct coordination environment and high atomic utilization *** study focuses on the synthesis of a monatomic Cu catalyst with Cu-N1C1 coordination anchored to N-doped Ti_(3)C_(2)T_(x) MXene(Cu SA@N-Ti_(3)C_(2)T_(x))to achieve efficient reduction of CO_(2) to *** characterization,including morphology and multispectral analysis,confirmed the uniform distribution of asymmetrically coordinated Cu atoms in unsaturated C-Cu-N bridge fragments on Ti_(3)C_(2)T_(x).The Cu SA@N-Ti_(3)C_(2)T_(x) catalyst exhibited an excellent CO selectivity with Faraday efficiency of 97.4%at-0.58 V *** hydrogen electrode(RHE)and satisfactory *** in situ X-ray absorption fine structure(XAFS)results confirmed that the carbon dioxide reduction reaction(CO_(2)RR)product distribution is mainly affected by potential-dependent valence change of Cu *** findings highlight the extensive potential of tuning coordination structure of MXene-based single-atom catalysts for CO_(2) reduction reactions.

关键词： cooper single atom atomic regulation MXene Ti_(3)C_(2)T_(x) CO_(2)reduction

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地下核电站裂隙岩体中核素运移分析

人民长江 2016年第3期47卷 49-55页

作者：张志国钮新强陈胜宏刘嫦娥长江勘测规划设计研究有限责任公司湖北武汉430010 长江勘测规划设计研究院湖北武汉430010 武汉大学水利水电学院湖北武汉430072

地下核电站将反应堆等涉核建筑物布置于稳定的山体中,在厂址选择时必须评价极端严重事故工况下可能的地下水污染对外界环境的影响。结合地下核电站洞室群赋存岩体特征,提出采用以三维渗透系数张量表示的等效连续介质模型模拟裂隙岩体渗... 详细信息

地下核电站将反应堆等涉核建筑物布置于稳定的山体中,在厂址选择时必须评价极端严重事故工况下可能的地下水污染对外界环境的影响。结合地下核电站洞室群赋存岩体特征,提出采用以三维渗透系数张量表示的等效连续介质模型模拟裂隙岩体渗流特性,建立"隐含断层"渗流模型,求解洞室群三维渗流场。并以该渗流场为基础,进行核素运移计算。对某初选的地下核电站厂址进行模拟计算表明:在渗控措施作用下,地下洞室群工程区处于"疏干"状态;即使在严重事故工况下,向反应堆洞室内注入冷却水后,洞室内外渗流场不连通,核素不会随消防水渗入外界。

关键词：裂隙岩体渗流核素运移地下核电站

慢病毒介导的CYP3A11基因knock-down小鼠的建立

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第三军医大学学报 2010年第5期32卷 422-426页

作者：庞浩刘昌峨刘勤王露露郭科男王勇魏泓第三军医大学基础医学部实验动物学教研室重庆400038

目的构建和筛选小鼠P4503A11基因miR RNAi慢病毒载体,建立CYP3A11基因knock-down小鼠。方法利用Ravi Sachidanandam's Lab的在线软件设计沉默小鼠P4503A11基因的miRNA所对应的shRNA序列,PCR扩增后克隆到PCI-GFP-MiR质粒中,其再与慢病毒载体FUW进行重组。将psPAX2和pMD2.G两个载体和FUW-GFP-MiR-shRNA重组慢病毒载体共转染293FT细胞,包装成病毒。用包装好的病毒液感染293FT细胞后,并利用GFP蛋白表达水平进行滴度测定。将上述重组慢病毒载体分别转染FVB/N小鼠肝细胞,转染48h后,检测P4503A11基因mRNA表达水平的变化。选取干扰效果最好的FUW-GFP-MiR-shRNA1重组慢病毒载体进行制备基因knock-down小鼠模型。用显微注射法将浓缩的shRNA1病毒液注射至FVB/N小鼠12细胞期胚胎透明带下。将注射后发育至22细胞期的胚胎移植至假孕受体母鼠,得F0代小鼠。在紫外光照射下利用滤光片观察GFP在小鼠活体内的表达水平。结果DNA测序结果显示3个重组慢病毒载体均与所设计的shRNA序列一致。检测的3个浓缩前慢病毒悬液的滴度均≥106TU/ml,经过高速离心对病毒进行浓缩和纯化,其滴度达到109TU/ml以上。转染FUW-GFP-MiR-shRNA1、2的2组肝细胞的P4503A11基因mRNA表达水平相对于空白对照组均显著下降(P<0.05),而转染阴性对照FUW-GFP-MiR-shRNA-NC的肝细胞P4503A11基因mRNA表达水平相对于空白对照组无明显改变。选用FUW-GFP-MiR-shRNA1慢病毒载体制备的F0代3A11基因knock-down小鼠,在紫外光照射下,阳性小鼠可见较强的荧光。结论构建并筛选出小鼠P4503A11基因有效的靶向miR RNAi慢病毒载体,并成功建立CYP3A11基因knock-down小鼠。

关键词：细胞色素P-450 CYP3A knock-down 微RNAs 慢病毒小鼠

Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO_(2)fracturing

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Particuology 2024年第7期90卷 149-163页

作者： Boyu liu Jun Yao Research Center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266000China

The non-uniform temperature distribution in supercritical CO_(2)(Sc-CO_(2))fracturing influences the density,viscosity,and volume expansion or shrinkage rate of Sc-CO_(2),impacting proppant *** study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall,proppant-fluid,and fluid-wall on the fluid and proppant temperature *** Sc-CO_(2)volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO_(2)*** factors,including proppant size,shape,thermal conductivity,concentration,temperature difference,and injection velocity,are carefully analyzed to elucidate their *** findings elucidate the existence of four distinct zones in the fluid temperature *** zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant *** fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity(governing the heating duration),the temperature difference between fluid and formation(impacting the magnitude of heat flux),and the proppant bed shape(controlling the effective heating area).Additionally,the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B,showing a strong correlation with proppant thermal conductivity,proppant size,injection velocity,and temperature *** proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

关键词： CFD-DEM Heat transfer Compressible fluid CO_(2)sequestration Proppant transport

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卫星导航信号质量监测系统及应用

全球定位系统 2009年第6期34卷 60-63页

作者：王宏兵刘昌洁北京5136信箱北京100094 南开大学信息技术科学学院天津30071

卫星导航信号质量监测是卫星导航系统设计和运行过程中的重要环节。在介绍国外已建立并运行的卫星导航信号监测系统组成和任务的基础上,从导航信号结构组成入手,阐述了导航信号质量监测的主要内容、系统的设备组成、工作模式,并介绍了... 详细信息

卫星导航信号质量监测是卫星导航系统设计和运行过程中的重要环节。在介绍国外已建立并运行的卫星导航信号监测系统组成和任务的基础上,从导航信号结构组成入手,阐述了导航信号质量监测的主要内容、系统的设备组成、工作模式,并介绍了该系统在导航信号质量监测中的实际应用。

关键词：卫星导航导航信号信号质量监测

Mass transfer characteristics of chiral pharmaceuticals on membrane used for polar organic chemical integrative sampler

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Journal of Environmental Sciences 2024年第2期136卷 670-681页

作者： Liyang Wang Ruixia liu Youya Zhou Peng Yuan Xiaoling liu Hongjie Gao College of Water Science Beijing Normal UniversityBeijing 100018China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental ScienceBeijing 100012China Technical Centre for Soil Agriculture and Rural Ecology and EnvironmentMinistry of Ecology and EnvironmentBeijing 100012China

Passive sampling technology has good application prospects for monitoring trace pollutants in aquatic *** research on the sampling mechanism of this technology is essential to improve the measurement accuracy and extend the application scope of this *** this study,adsorption and permeation experiments were performed to investigate the sorption and mass transfer properties of five chiral pharmaceuticals at the enantiomeric level on polyethersulfone(PES)and polytetrafluoroethylene(PTFE)membranes used in a polar organic chemical integrative *** adsorption experiments showed that the PES membrane had an adsorption phenomenon for most selected pollutants and an insignificant sorption behavior was observed for all selected pharmaceuticals on the PTFE membrane except for R(S)-*** diffusion coefficients of selected pharmaceuticals onto the PTFE membrane were approximately one order of magnitude higher than those onto the PES *** permeation experiment indicated that under different hydraulic conditions,the change of the relative pollutant concentration through the PTFE membrane for the composite pollutant system was more obvious than that for the single pollutant system,and mass transfer hysteresis exists for both contaminant systems through PES *** the first-order equation or 3-component model to estimate the overall mass transfer coefficients,the results showed that the overall mass transfer coefficient values of pollutants in the composite pollutant system onto both membranes were higher than those in the single pollutant *** parameter was mainly influenced by the synergistic effects of the multi-analyte interaction and diminished water boundary layers during the mass transfer process.

关键词： Sorption phenomenon Permeation behavior Mass transfer properties Modeling calculation Chiral pharmaceuticals PES and PTFE membrane