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Phase field modeling for the morphological and microstructural evolution of metallic materials under environmental attack

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npj Computational Materials 2021年第1期7卷 1299-1319页

作者： Talha Qasim Ansari Haitao Huang San-qiang shi Department of Applied Physics and Research Institute of Smart Energy the Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SAR Department of Mechanical Engineering the Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SAR

The complex degradation of metallic materials in aggressive environments can result in morphological and microstructural *** phase-field(PF)method is an effective computational approach to understanding and predicting the morphology,phase change and/or transformation of *** models are based on conserved and non-conserved field variables that represent each phase as a function of space and time coupled with time-dependent equations that describe the *** report summarizes progress in the PF modeling of degradation of metallic materials in aqueous corrosion,hydrogen-assisted cracking,high-temperature metal oxidation in the gas phase and porous structure evolution with insights to future applications.

关键词： corrosion cracking metallic

Differentially private feature selection under MapReduce framework

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The Journal of China Universities of Posts and Telecommunications 2013年第5期20卷 85-90,103页

作者： CHEN Kai WAN Wen-qiang LI yun College of Computer Science Nanjing University of Posts and Telecommunications Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks Nanjing University of Posts and Telecommunications Institute of Computer Technology Nanjing University of Posts and Telecommunications

Privacy preserving data mining algorithms are crucial for the personal data analysis, such as medical and financial records. This paper focuses on feature selection and proposes a new privacy preserving distributed algorithm, which can effectively select features based on differential privacy and Gini index under the MapReduce framework. At the same time, the theoretic analysis for privacy guarantee is also presented. Some experiments are conducted on bench-mark datasets, the simulation results indicate that during the selection of important features, the proposed algorithm can preserve privacy information to a certain extent with less time cost than on centralized counterpart.

关键词： data mining feature selection differential privacy MapReduce

Recent progress in carbon/lithium metal composite anode for safe lithium metal batteries

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Rare Metals 2018年第6期37卷 449-458页

作者： Tao Li He Liu Peng shi qiang Zhang Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical Engineering Tsinghua University

Owing to their very high theoretical capacity, lithium （Li） metal anodes regain widespread attentions for their promising applications for next-generation high-energy-density Li batteries （e.g., lithium-sulfur batteries, lithium-oxygen batteries, solid-state lithium metal batter- ies）. However, the inherent bottleneck of Li metal anodes, especially the growth of Li dendrites and the related safety concerns, should be well addressed. Owing to their featured micro-/nano-porous structures and intriguing physical properties, nanocarbon materials have been applied as host materials for Li metal anodes. This review summarizes the recent progress in the development of porous nanocarbon materials for safe Li metal anodes. The perspectives regarding the challenges and future development of employing micro-/nano-porous carbon materials in Li metal anodes are also included.

关键词： Li metal anode Carbon nanomaterials Composite electrode Solid electrolyte interphase Rechargeable batteries Lithiophilic hosts Graphene

XAFS applications in semiconductors

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Nuclear Science and Techniques 2006年第6期17卷 370-388页

作者： WEI shi-qiang SUN Zhi-Hu PAN Zhi-yun ZHANG Xin-Yi YAN Wen-Sheng ZHONG Wen-Jie National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China Department of Physics Surface Physics Laboratory （National Key laboratory） and Synchrotron Radiation Research Center Fudan University Shanghai 200433. China

X-ray absorption fine structure (XAFS) has experienced a rapid development in the last three decades and has proven to be a powerful structural characterization technique nowadays. In this review, the XAFS basic principles including the theory, the data analysis, and the experiments have been introduced in detail. To show its strength as a local structure probe, the XAFS applications in semiconductors are summarized comprehensively, that is, thin films, quantum wells and dots, dilute magnetic semiconductors, and so on. In addition, certain new XAFS-related techniques, such as in-situ XAFS, micro-XAFS, and time-resolved XAFS are also shown.

关键词： XAFS应用半导体 X射线吸收基本原理

Influence of Iron Supplementation on DMT1(IRE)-induced Transport of Lead by Brain Barrier Systems in vivo

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Biomedical and Environmental Sciences 2015年第9期28卷 651-659页

作者： AN Dai Zhi AI Jun Tao FANG Hong Juan SUN Ru Bao shi yun WANG Li Li WANG qiang Institute of Disease Control and Prevention Academy of Military Medical Sciences Beijing Vocational College of Agriculture Beijing Tian Tan Hospital Capital Medical University

Objective To investigate the potential involvement of DMT1（IRE） protein in the brain vascular system in vivo during Pb exposure. Methods Three groups of male Sprague-Dawley rats were exposed to Pb in drinking water, among which two groups were concurrently administered by oral gavage once every other day as the low and high Fe treatment group, respectively, for 6 weeks. At the same time, the group only supplied with high Fe was also set as a reference. The animals were decapitated, then brain capillary-rich fraction was isolate from cerebral cortex. Western blot method was used to identify protein expression, and RT-PCR to detect the change of the m RNA. Results Pb exposure significantly increased Pb concentrations in cerebral cortex. Low Fe dose significantly reduced the cortex Pb levels, However, high Fe dose increased the cortex Pb levels. Interestingly, changes of DMT1（IRE） protein in brain capillary-rich fraction were highly related to the Pb level, but those of DMT1（IRE） m RNA were not significantly different. Moreover, the consistent changes in the levels of p-ERK1/2 or IRP1 with the changes in the levels of DMT1（IRE）. Conclusion These results suggest that Pb is transported into the brain through DMT1（IRE）, and the ERK MAPK pathway is involved in DMT1（IRE）-mediated transport regulation in brain vascular system in vivo.

关键词： Lead Iron Blood-brain barrier Divalent metal transporter 1 MAPK pathway

Flow structure and unsteady fluctuation with separation over a two-dimensional backward-facing step

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Journal of Hydrodynamics 2019年第6期31卷 1204-1217页

作者： Fang-fang Wang shi-qiang Wu Biao Huang State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China Smart Cities Institute Zhengzhou UniversityZhengzhou 450001China

The flow over a backward-facing step(BFS)is a typical separation and reattachment *** flow structures and unsteady mechanisms are still not well *** this paper,the global velocity fields of a BFS are obtained by a synchronous particle image velocimetry(PIV)system with Reh=5345(Reynolds number)and Er=2(expansion ratio).Flow structures are distinguished and defined by the fraction of the negative velocity(upn).The reattachment zone(Lr)is quantitatively defined as(u0.9,u/0.1)on the bottom *** distribution of the large-scale vortices couples well with the divided flow structures and their temporal evolution presenting four stages(forming,developing,shedding and redeveloping)when travel *** unsteady motions with various low frequencies are well explained by the coherent vortices and flow *** the unsteady low frequency motions,the Kelvin Helmholtz(KH)vortices and the oscillation of Xr(OX)come likely from the free shear *** KH vortices contribute to the unsteadiness of the temporal flow,and the OX is the primary response to the vortical fluctuations.

关键词： Backward-facing step flow structure large-scale vortices unsteady motion free shear layer

Seasonal and Annual Variations of CO_2 Fluxes in Rain-Fed Winter Wheat Agro-Ecosystem of Loess Plateau, China

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Journal of Integrative Agriculture 2013年第1期12卷 147-158页

作者： WANG Wen LIAO yun-cheng GUO qiang College of Agronomy Northwest A&F University

To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.

关键词： CO 2 flux carbon sequestration soil water content rainfall event rain-fed winter wheat agro-ecosystem

Probes and nano-delivery systems targeting NAD(P)H:quinone oxidoreductase 1:a mini-review

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Frontiers of Chemical Science and Engineering 2023年第2期17卷 123-138页

作者： Xuewen Mu yun Xu Zheng Wang Dunyun shi School of Pharmaceutical Science&Technology Tianjin UniversityTianjin 300072China Central Lab Shenzhen Second People’s Hospital/the First Affiliated Hospital of Shenzhen UniversityShenzhen 518035China Institute of Hematology Shenzhen Second People’s Hospital/the First Affiliated Hospital of Shenzhen UniversityShenzhen 518035China

The two-electron cytoplasmic reductase NAD(P)H:quinone oxidoreductase 1 is expressed in many ***(P)H:quinone oxidoreductase 1 is well-known for being highly expressed in most ***,it could be a target for cancer *** it is a quinone reductase,many bioimaging probes based on quinone structures target NAD(P)H:quinone oxidoreductase 1 to diagnose *** expression is higher in tumours than in normal tissues,and using target drugs such asβ-lapachone to reduce side effects in normal tissues can ***,the physicochemical properties ofβlapachone limit its *** problem can be solved by using nanosystems to deliverβ-*** minireview summarizes quinone-based fluorescent,nearinfrared and two-photon fluorescent probes,as well as nanosystems for delivering the NAD(P)H:quinone oxidoreductase 1-activating drugβ-*** review provides valuable information for the future development of probes and nano-delivery systems that target NAD(P)H:quinone oxidoreductase 1.

关键词： NAD(P)H:quinone oxidoreductase 1 cancer therapy target probe nanosystem

Analytical solution to one-dimensional mathematical model of flow and morphological evolution in open channels

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Science China(Technological Sciences) 2020年第12期63卷 2606-2616页

作者： DING yun LI ZuiSen shi YongZhong ZHONG DeYu State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310008China Zhejiang Provincial Key Laboratory of Hydraulic Disaster Prevention and Mitigation Hangzhou 310008China Joint-Sponsored State Key Laboratory of Plateau Ecology and Agriculture Qinghai UniversityXining 810016China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

The evolution of open-channel flow and morphology can be simulated by one-dimensional(1D) mathematical models. These models are typically solved by numerical or analytical methods. Because the behavior of variables can be explained by explicit mathematical determinations,compared to numerical solutions,analytical solutions provide fundamental and physical insights into flow and sediment transport mechanisms. The singular perturbation technique derives a hierarchical equation of waves and describes the evolutionary nature of disturbances in hyperbolic systems. The wave hierarchy consists of dynamic,diffusion,and kinetic waves. These three types of waves interact with each other in the process of propagation. Moreover,the Laplace transform is implemented to transform partial differential equations into ordinary differential equations. Analytical expressions in the wave front are subtracted by the approximation of kinetic and diffusion models. Moreover,an analytical solution consists of a linear combination of the kinetic wave front and the diffusion wave front expressions,pursuing to describe the physical mechanism of motion in open channels as completely as possible. Analytical solutions are presented as a combination of exponential functions,hyperbolic functions,and infinite series. The obtained analytical solution was further applied to the simulation of flood path and morphological evolution in the Lower Yellow River. The phenomenon of increased peak discharge in the downstream reach was successfully simulated. It was encouraging that the results were in good agreement with the observed data.

关键词： open channel mathematical model analytical solution Laplace transform morphological evolution