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Journal of Materials Science & Technology 2016年第3期32卷 271-281页

作者： Yingshuang Guan Enze Liu Xiurong Guan zhi zheng School of Environmental and Chemical Engineering Shenyang Ligong University Shenyang 110159 China Superalloys Division Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The effect of Ru addition on solidification behavior, microstructure and hardness of Re-free Ni-based equiaxed superalloys with high Cr content has been investigated. With the increase of Ru, the solidus temperature of the alloys and the γ＂ solvus temperature decreased, respectively. However, the liquidus temperatures of the alloys bad no obvious change. The microstructure of the as-cast alloys was mainly composed of γ, γ＇, γ＇/γ＇ eutectic and MC carbides. The γ/γ＇ eutectic was completely dissolved after the heat treatment. The morphology of γ＇ was more cuboidal in heat-treated alloys with increasing Ru. Furthermore, the volume fraction of γ＇ in the as-cast and heat-treated alloys diminished upon the increase of Ru. It was noted that Ru addition changed the segregation behaviors of Cr and Mo in the alloys from positive segregation element to negative segregation element and promotes the segregation degree of W. As the Ru content increased, the magnitude of segregation of the positive segregation elements Ta and Ti increased accordingly. Meanwhile, the magnitude of Al segregation decreased and Ru tended to segregate in the dendrite core. In addition, the hardness of the alloys improved and their porosity reduced with increasing amount of Ru.

关键词： Ru Ni-based equiaxed superalloy Microstructure Segregation Hardness

Establishing an experimental rat model of photo-dynamically-induced retinal vein occlusion using erythrosin B

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International Journal of Ophthalmology(English edition) 2014年第2期7卷 232-238页

作者： Wei Chen Ying Wu Mi zheng Qing Gu zhi zheng Xin Xia Department of Ophthalmology Shanghai First People's Hospital School of Medicine Shanghai Jiaotong University Shanghai Key Laboratory of Fundus Diseases Shanghai Jiaotong University

AIM:To develop a reliable,reproducible rat model of retinal vein occlusion(RVO)with a novel photosensitizer(erythrosin B)and study the cellular responses in the retina.METHODS:Central and branch RVOs were created in adult male rats via photochemically-induced ischemia.Retinal changes were monitored via color fundus photography and fluorescein angiography at 1 and 3h,and 1,4,7,14,and 21d after irradiation.Tissue slices were evaluated histopathologically.Retinal ganglion cell survival at different times after RVO induction was quantified by nuclear density count.Retinal thickness was also observed.RESULTS:For all rats in both the central and branch RVO groups,blood flow ceased immediately after laser irradiation and retinal edema was evident at one hour.The retinal detachment rate was 100%at 3h and developed into bullous retinal detachment within 24h.Retinal hemorrhages were not observed until 24h.Clearance of the occluded veins at 7d was observed by fluorescein angiography.Disease manifestation in the central RVO eyes was more severe than in the branch RVO group.A remarkable reduction in the ganglion cell count and retinal thickness was observed in the central RVO group by 21d,whereas moderate changes occurred in the branch RVO group.CONCLUSION:Rat RVO created by photochemicallyinduced ischemia using erythrosin B is a reproducible and reliable animal model for mimicking the key features of human RVO.However,considering the 100%rate ofretinal detachment,this animal model is more suitable for studying RVO with chronic retinal detachment.

关键词： retinal vein occlusion ischemia laser photothrombosis rat model

Microstructural Evolution of a Ni-base Alloy DZ468 Joint Bonded with a New Co-base Filler

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Journal of Materials Science & Technology 2014年第5期30卷 480-486页

作者： Yanhong Jing zhi zheng Enze Liu Yi Guo Division of Superalloy Institute of Metal ResearchChinese Academy of Sciences

Ni-base alloy DZ468 has been joined by transient liquid phase bonding technique with a newly developed Co-based filler. The microstructures of the Co-base filler and the joint, the effects of heat treatment on microstructure and hardness of the joint have been investigated by various experimental methods. Results show that the Co-base filler consists of γ, M2B, M5B3 and M23B6 phases. Because of the interdiffusion between the base metal and the filler, γ, MC, M5B3 and M23B6 phases are formed in the bonding zone. And localized liquidation of substrate occurs in the diffusion affected zone, with MC and M3B2 precipitating in this area. During heat treatment, the volume of the intermetallic phases in the bonding zone resulting from incomplete isothermal solidification decreases obviously. On the contrary, the width of the diffusion affected zone increases at the solution stage and subsequently decreases at the aging stages.

关键词： Transient liquid phase （TLP） bonding Microstructure evolution Ni-base alloy Co-base rifler

定量评估气候变化对长江中下游地区植被GPPGS变化的影响

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环境科学 2024年第3期45卷 1615-1628页

作者：徐勇盘钰春邹滨郑志威郭振东桂林理工大学测绘地理信息学院桂林541006 中南大学地球科学与信息物理学院长沙410083

在区域和植被类型尺度上定量厘定气候因子对长江中下游地区生长季植被GPP(GPP_(GS))的直接、间接和综合影响,可为全球气候变化背景下区域植被资源管理与恢复提供科学依据.利用MODIS GPP数据、气象数据和植被类型数据,结合Theil-Sen Med... 详细信息

在区域和植被类型尺度上定量厘定气候因子对长江中下游地区生长季植被GPP(GPP_(GS))的直接、间接和综合影响,可为全球气候变化背景下区域植被资源管理与恢复提供科学依据.利用MODIS GPP数据、气象数据和植被类型数据,结合Theil-Sen Median趋势分析和Mann-Kendall显著性检验探究长江中下游地区植被GPP_(GS)时空变化特征,并通过通径分析揭示气候因子对长江中下游地区整体和不同类型植被GPP_(GS)变化的直接影响、间接影响和综合影响.结果表明:(1)2000~2021年长江中下游地区植被GPP_(GS)呈波动上升趋势,上升速率(以C计,下同)为2.70 g·(m^(2)·a)^(-1)(P<0.01).不同类型植被GPP_(GS)均呈极显著上升趋势(P<0.01),其中,灌丛上升速率最高,为3.31 g·(m^(2)·a)^(-1),栽培植被上升速率最低,为2.54 g·(m^(2)·a)^(-1).(2)长江中下游地区GPP_(GS)呈上升趋势的面积占比为88.11%.不同类型植被GPP_(GS)呈上升趋势的面积占比均大于84%.(3)通径分析结果表明,降水和最高气温对植被GPP_(GS)的直接影响呈显著正向影响(P<0.05),而太阳辐射呈不显著正向影响(P≥0.05).最高气温、降水和太阳辐射对植被GPP_(GS)的间接影响均呈非显著负向影响(P≥0.05).在直接影响和间接影响的综合作用下,降水和最高气温对植被GPP_(GS)呈不显著正向影响(P≥0.05),而太阳辐射对植被GPP_(GS)呈不显著负向影响(P≥0.05);不同植被类型上,降水是影响栽培植被GPP_(GS)变化的主要气候因子,最高气温是影响针叶林、阔叶林、灌丛和草丛GPP_(GS)变化的主要气候因子.(4)长江中下游地区植被GPP_(GS)变化主要受最高气温、降水和太阳辐射的直接影响,降水的直接影响对植被GPP_(GS)变化的主导区域占56.72%.研究结果可为量化长江中下游地区植被固碳潜力和全球气候变化背景下制定因地制宜的生态恢复治理政策提供参考.

关键词：总初级生产力(GPP) 不同类型植被生长季通径分析气候因子直接影响间接影响

Overcome Debye Length Limitations for Biomolecule Sensing Based on Field Effective Transistors

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Chinese Journal of Chemistry 2021年第4期39卷 999-1008页

作者： zhi zheng Hongyuan Zhang Tianyou Zhai Fan Xia Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and ChemistryChina University of GeosciencesWuhanHubei430074 China State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhanHubei 430074Chino

Biosensors based on field effective transistor(FET)have aroused tremendous attention in the past few years owning to their huge application in drug discovery,disease diagnosis and environmental monitoring.The FET biosensors possess small volume,high sensitivity at ultra-low concentration,considerable mechanical strength,as well as excellent stability in solution,which plays a vital role in the point of care testing(POCT)systems.Recent advances have summarized some progress involved in the improvement of morphology and structure of channel materials,the functionalization of organic molecule,the influence of device operation and sensing environment on the detecting performance.However,for FET biosensors,the charge screening phenomena were inevitable in the solution,which seriously degrade the device performance.In this article,we summarize recent advances to overcome debye length limitations for biomolecule sensing based on FET.We will firstly describe the charge screening mechanism,then focous on the strategy to overcome charge screening,including synthesizing special channel materials with crumpled morphology,designing aptamer binding mode,and modulating device measurement.Finally,we discuss the major challenges and perspectives about overcoming debye length limitations of FET biosensors.These summaries provide further insights to realize real-time,lable-free,high-sensitivity FET sensors for medical healthcare.

关键词： Debye length Interactions Field effective transistors Biosensors Biomolecule

Diagnostic performance of Neutrophil CD64 index,procalcitonin,and C-reactive protein for early sepsis in hematological patients

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World Journal of Clinical Cases 2022年第7期10卷 2127-2137页

作者： Yu-Xi Shang zhi zheng Min Wang Hui-Xia Guo Yi-Juan Chen Yue Wu Xing Li Qian Li Jian-Ying Cui Xiao-Xiao Ren Li-Ru Wang Department of Hematology Fuxing HospitalEighth Clinical Medical CollegeCapital Medical UniversityBeijing 100038China Department of General Surgery Xuanwu HospitalCapital Medical UniversityBeijing 100053China

BACKGROUND Patients with hematological diseases are immunosuppressed due to various factors,including the disease itself and treatments,such as chemotherapy and immunotherapy,and are susceptible to infection.Infections in these patients often progress rapidly to sepsis,which is life-threatening.AIM To evaluate the diagnostic efficacy of the neutrophil CD64(nCD64)index,compared to procalcitonin(PCT)and high-sensitivity C-reactive protein(hs-CRP),for the identification of early sepsis in patients with hematological diseases.METHODS This was a prospective analysis of patients with hematological diseases treated at the Fuxing Hospital affiliated with Capital Medical University,between March 2014 and December 2018.The nCD64 index was quantified by flow cytometry and the Leuko64 assay software.The factors which may affect the nCD64 index levels were compared between patients with different infection statuses(local infection,sepsis,and no infection),and the control group and the nCD64 index levels were compared among the groups.The diagnostic efficacy of the nCD64 index,PCT,and hs-CRP for early sepsis was evaluated among patients with hematological diseases.RESULTS A total of 207 patients with hematological diseases(non-infected group,n=50;locally infected group,n=67;sepsis group,n=90)and 26 healthy volunteers were analyzed.According to the absolute neutrophil count(ANC),patients with hematological diseases without infection were divided into the normal ANC,ANC reduced,and ANC deficiency groups.There was no statistically significant difference in the nCD64 index between these three groups(P=0.586).However,there was a difference in the nCD64 index among the non-infected(0.74±0.26),locally infected(1.47±1.10),and sepsis(2.62±1.60)groups(P<0.001).The area under the diagnosis curve of the nCD64 index,evaluated as the difference between the sepsis and locally infected group,0.777,which was higher than for PCT(0.735)and hs-CRP(0.670).The positive and negative likelihood ratios were also better for the nCD64 index than either

关键词： CD64 index Hematological diseases Sepsis Procalcitonin C-reactive protein

Research Progress and Future Perspectives on Rechargeable Na-O_(2) and Na-CO_(2) Batteries

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Energy & Environmental Materials 2021年第2期4卷 158-177页

作者： zhi zheng Chang Wu Qinfen Gu Konstantin Konstantinov Jiazhao Wang Institute for Superconducting and Electronic Materials University of WollongongWollongong NSW 2522Australia The Australian Synchrotron(ANSTO) 800 Blackburn RoadClayton VIC 3168Australia

Rechargeable sodium–oxygen(Na-O_(2))and sodium–carbon dioxide(Na-CO_(2))batteries have attracted intensive research attention in recent years owing to their advantages of high theoretical energy density,modest cost,abundance of sodium resources,and promising potential for achieving real sodium–air batteries in large-scale energy storage systems.Nevertheless,current research on Na-O_(2)and Na-CO_(2)batteries is facing enormous challenges,such as low energy efficiency and limited cycle life,which are restricting their progress at the initial stage.Therefore,understanding their working principles,and the chemical and electrochemical reactions of the electrodes is indispensable to achieve their practical application and even the goal of true sodium–air batteries.This review aims to provide an overview of the research developments and future perspectives on Na-O_(2)and Na-CO_(2)batteries,which include the major aspects,such as working mechanisms,air cathode materials design strategies,sodium anode protection,and electrolyte stability.Moreover,the remaining issues and future research directions are also thoroughly discussed and presented.

关键词： anode protection cathode materials electrolytes Na-CO_(2)batteries Na-O_(2)batteries

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数字普惠金融对农村相对贫困的影响

改革 2024年第5期 80-94页

作者：郑志龙李雨臻郑州大学政治与公共管理学院

基于2011—2022年北京大学数字普惠金融指数等经验数据实证检验了数字普惠金融对农村相对贫困的影响效果、机制与异质性。研究结果表明,数字普惠金融显著缓解了农村相对贫困;进一步通过变更系统GMM估计方法、替换变量处理以及样本期间... 详细信息

基于2011—2022年北京大学数字普惠金融指数等经验数据实证检验了数字普惠金融对农村相对贫困的影响效果、机制与异质性。研究结果表明,数字普惠金融显著缓解了农村相对贫困;进一步通过变更系统GMM估计方法、替换变量处理以及样本期间波动性问题处理等方式进行检验,研究结论依然稳健;机制分析表明,数字普惠金融通过显著增加信贷规模、改善信贷结构和提高信贷质量等信贷供给机制缓解农村相对贫困,还通过显著促进创新创业缓解农村相对贫困;异质性分析表明,在非农经济比重较高、经营性收入占比较高和受教育程度较高的省份,且在数字普惠金融覆盖率、使用深度和数字化程度较高的组别,数字普惠金融的农村相对贫困缓解效应更为显著。

关键词：数字普惠金融农村相对贫困信贷供给创新创业

Dependence structure between LIBOR rates by copula method

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Frontiers of Mathematics in China 2015年第1期10卷 147-183页

作者： Yijun WU zhi zheng Shulin ZHOU Jingping YANG LMEQF Department of Financial Mathematics Center for Statistical Science Peking University Beijing 100871 China LMAM Department of Mathematics Peking University Beijing 100871 China

This paper discusses the correlation structure between London Interbank Offered Rates （LIBOR） by using the copula function. We start from one simplified model of A. Brace, D. Gatarek, and M. Musiela （1997） and find out that the copula function between two LIBOR rates can be expressed as a sum of an infinite series, where the main term is a distribution function with Gaussian copula. Partial differential equation method is used for deriving the copula expansion. Numerical results show that the copula of the LIBOR rates and Gaussian copula are very close in the central region and differ in the tail, and the Gaussian copula approximation to the copula function between the LIBOR rates provides satisfying results in the normal situation.

关键词： London Interbank Offered Rate （LIBOR） copula function partialdifferential equation （PDE）

Hot deformation behavior and microstructure evolution of an Fe–30Cr–2Mo ultra-pure super ferritic stainless steel

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Journal of Iron and Steel Research(International) 2021年第10期28卷 1291-1304页

作者： Yang-yang Zhu Li-kui Ning Tong-zheng Xin En-ze Liu Jian Tong zheng Tan Yang-tao Zhou zhi zheng Institute of Metal Research Chinese Academy of SciencesShenyang110016LiaoningChina School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016LiaoningChina School of Materials Science and Engineering University of New South WalesSydneyNSW2052Australia

The hot deformation behavior and microstructure evolution of an Fe–30Cr–2Mo ultra-pure super ferritic stainless steel were investigated at the temperature range of 950–1150℃ and strain rate varying from 0.01 to 10 s^(−1).A strain compensated constitutive equation based on the Arrhenius-type model was established to predict the flow stress.The hot processing map based on the dynamic materials model was achieved to identify the optimum processing parameters.In addition,the features of microstructure evolution combined with the processing map were systematically investigated.The experimental results revealed that the flow stress increased with decreasing deformation temperature or increasing strain rate.Dynamic recovery was confirmed to be the predominant softening mechanism.The values of flow stress predicted by the strain compensated constitutive equation agreed well with the experimental values.The extent of dynamic recrystallization and recrystallized grain size increased with increasing deformation temperature or decreasing strain rate,and the continuous dynamic recrystallization was attributed to be the predominant mechanism of recrystallization during hot deformation.The optimum hot working parameters were determined to be the deformation temperature of 1070–1150℃ and strain rate of 0.1–1 s^(−1) with a peak power dissipation efficiency of 42%.

关键词： Super ferritic stainless steel Hot compression Constitutive equation Processing map Microstructure evolution