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HR-ICP-MS研究黄河三个连续区域段表层沉积物中重金属污染的空间分布和季节变化（英文）

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光谱学与光谱分析 2016年第8期36卷 2705-2711页

作者：马小玲邓凤玉刘颖中央民族大学生命与环境科学学院北京100081 中央民族大学北京市食品环境与健康工程技术研究中心北京100081

采用高分辨电感耦合等离子体质谱(HR-ICP-MS)和地积累指数法(I_(geo))对黄河甘肃、宁夏和内蒙古自治区连续三段表层沉积物中重金属(Cr,Pb,Cd,Cu,Zn和Ni)的空间分布和季节性波动(丰水期、枯水期和平水期)以及污染状况进行系统研究分析,... 详细信息

采用高分辨电感耦合等离子体质谱(HR-ICP-MS)和地积累指数法(I_(geo))对黄河甘肃、宁夏和内蒙古自治区连续三段表层沉积物中重金属(Cr,Pb,Cd,Cu,Zn和Ni)的空间分布和季节性波动(丰水期、枯水期和平水期)以及污染状况进行系统研究分析,研究结果表明:内蒙古段三个季节中沉积物重金属含量都高于甘肃和宁夏段,同时,除Cd外,丰水期所有点的沉积物重金属含量都高于枯水期和平水期,而枯水期和平水期的重金属含量相近。I_(geo)结果显示丰、枯水期的Cd,Cu和Cr元素的I_(geo)值在内蒙古段最高,而在甘肃段最低;所有重金属的I_(geo)值在丰水期高于枯水期,除Cd外,都在平水期降低,而I_(geo)^(Cd)在平水期各采样点明显上升;丰水期的甘肃段、枯水期的甘肃和宁夏段以及平水期的所有采样点中的Pb,Zn和Ni的I_(geo)值都小于0,表明这些元素在这些点几乎无污染。就研究区域而言,内蒙古段的重金属含量以及生态风险最高,Cr,Cd和Cu是最具有潜在风险的三个元素;就研究季节而言,丰水期的重金属含量和潜在风险高于枯水期和平水期,可能是跟丰水期沉积物的pH和总有机碳(TOC)含量较高有关。相关性分析(CCA)用来探究重金属与pH/TOC间的关系以及重金属的潜在来源。CCA的结果表明Pb,Cu,Zn和Ni互相相关,并且这四种元素容易受到周围环境pH和TOC的影响,除此之外,Cr,Cd以及TOC三者相关,且这两种元素受到人类活动影响较严重。该研究工作可为研究区域表层沉积物重金属在不同季节的环境行为提供有效的信息,同时,研究重金属、pH和TOC之间的相关性可有效揭示重金属的潜在来源。

关键词：空间分布季节变化重金属表层沉积物黄河

Nanomedicine sheds new light on cancer immunotherapy

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Medical Review 2023年第2期3卷 188-192页

作者： Yingying yu Liangzhu feng Zhuang liu Jiangsu Key Laboratory for Carbon-Based Functional Materials&Devices Institute of Functional Nano&Soft Materials(FUNSOM)Soochow UniversitySuzhouJiangsu ProvinceChina Jiangsu Key Laboratory for Carbon-Based Functional Materials&Devices Institute of Functional Nano&Soft Materials(FUNSOM)Soochow University199 Ren’ai RoadSuzhou 215123Jiangsu ProvinceChina

Cancer immunotherapy comprising of immune checkpoint blockade(ICB)therapy,immune cell therapies,cancer vaccines and many others represents a profound arsenal in the fight against different types of cancers.However,their overall clinical objective response rates,particularly against most solid tumors,are still not sufficient owing to a variety of reasons including the heterogenous expression of tumor antigens,limited tumor infiltration of effector immune cells,acquired tumor immunosuppression and some other factors.In recent years,various nanomedicine strategies have been proposed to assist cancer immunotherapy via distinct mechanisms,presenting new promises in many published studies.This perspective will thus provide a brief overview regarding the development of nanomedicine platforms for improving cancer immunotherapy.

关键词： cancer immunotherapy in situ cancer vaccine nanomedicine nanovaccine tumor microenvironment

Comparing COVID-19 Case Prediction Between ARIMA Model and Compartment Model—China,December 2019–April 2020

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China CDC weekly 2022年第52期4卷 1185-1188,I0006-I0010页

作者： Bangguo Qi Nankun liu Shicheng yu feng Tan Chinese Center for Disease Control and Prevention BeijingChina.

Introduction:To compare the performance between the compartment model and the autoregressive integrated moving average(ARIMA)model that were applied to the prediction of new infections during the coronavirus disease 2019(COVID-19)epidemic.Methods:The compartment model and the ARIMA model were established based on the daily cases of new infection reported in China from December 2,2019 to April 8,2020.The goodness of fit of the two models was compared using the coefficient of determination(R2).Results:The compartment model predicts that the number of new cases without a cordon sanitaire,i.e.,a restriction of mobility to prevent spread of disease,will increase exponentially over 10 days starting from January 23,2020,while the ARIMA model shows a linear increase.The calculated R2 of the two models without cordon sanitaire were 0.990 and 0.981.The prediction results of the ARIMA model after February 2,2020 have a large deviation.The R2 of complete transmission process fit of the epidemic for the 2 models were 0.964 and 0.933,respectively.Discussion:The two models fit well at different stages of the epidemic.The predictions of compartment model were more in line with highly contagious transmission characteristics of COVID-19.The accuracy of recent historical data had a large impact on the predictions of the ARIMA model as compared to those of the compartment model.&Joint first authors.

关键词： ARIMA prediction starting

Materials design by generalized stability

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Journal of Materials Science & Technology 2023年第16期147卷 153-164页

作者： yu Zhang Haoran Peng Linke Huang feng liu State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityShaanxi 710072China Northwest Institute for Nonferrous Metal Research Xi’an 710016China Analytical&Testing Center Northwestern Polytechnical UniversityShaanxi 710072China

1.Introduction,Understanding and predicting microstructure and its relationship with the mechanical properties of metallic materials require detailed knowledge of phase transformations(PTs)and plastic deformations(PDs).These two processes,as central topics in material science,can be fundamentally described to a large extent by a framework of thermodynamic and kinetics(thermo-kinetics).The situation of PTs arises when the microstructure is losing phase stability,whereas the issue of PDs corresponds to the break of mechanical stability,all of which can be uniformly defined as the so-called loss of thermodynamic stability(TS).In this context,the higher TS will lead to the higher driving force G essentially required for the PT and/or PD forming and/or changing the microstructure.In the case of PTs,extensive examples showing the high TS can be found,such as martensite transformations(MTs)upon continuous cooling or strain[1,2],coherent precipitation[3,4],so-called Schwarz crystal[5],etc.

关键词： microstructure martensite stability

Waves Induced by the Appearance of Single-Point Heat Source in Constant Flow

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Advances in Applied Mathematics and Mechanics 2022年第4期14卷 989-1016页

作者： Changsheng yu Tiegang liu Chengliang feng School of Mathematics Beihang UniversityBeijing 100191China

Heating or cooling one-dimensional inviscid compressible flow can be modeled by the Euler equations with energy sources.A tricky situation is the sudden appearance of a single-point energy source term.This source is discontinuous in both the time and space directions,and results in multiple discontinuous waves in the solution.We establish a mathematical model of the generalized Riemann problem of the Euler equations with source term.Based on the double CRPs coupling method proposed by the authors,we determine the wave patterns of the solution.Theoretically,we prove the existence and uniqueness of solutions to both"heat removal"problem and"heat addition"problem.Our results provide a theoretical explanation for the effect of instantaneous addition or removal of heat on the fluid.

关键词： Hyperbolic balance law generalized Riemann problem singular source existence and uniqueness.

Theoretical study of reduction mechanism of Fe_(2)O_(3) by H_(2) during chemical looping combustion

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Chinese Journal of Chemical Engineering 2021年第9期34卷 175-183页

作者： feng liu Jing liu yu Li Ruixue Fang State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

An atomic-level insight into the H_(2)adsorption and oxidation on the Fe_(2)O_(3)surface during chemicallooping combustion was provided on the basis of density functional theory calculations in this study.The results indicated that H_(2)molecule most likely chemisorbs on the Fe_(2)O_(3)surface in a dissociative mode.The decomposed H atoms then could adsorb on the Fe and O atoms or on the two neighboring O atoms of the surface.In particular,the H_(2)molecule adsorbed on an O top site could directly form H_(2)O precursor on the O_(3)-terminated surface.Further,the newly formed H-O bond was activated,and the H atom could migrate from one O site to another,consequently forming the H_(2)O precursor.In the H_(2)oxidation process,the decomposition of H_(2)molecule was the rate-determining step for the O_(3)-terminated surface with an activation energy of 1.53 eV.However,the formation of H_(2)O was the ratedetermining step for the Fe-terminated surface with an activation energy of 1.64 eV.The Feterminated surface is less energetically favorable for H_(2)oxidation than that the O_(3)-terminated surface owing to the steric hindrance of Fe atom.These results provide a fundamental understanding about the reaction mechanism of Fe_(2)O_(3)with H_(2),which is helpful for the rational design of Fe-based oxygen carrier and the usage of green energy resource such as H_(2).

关键词： Chemical-looping combustion Fe_(2)O_(3)oxygen carrier H_(2)adsorption Density functional theory Reaction mechanism

Effects of connection types and elevated temperature on the impact behaviour of restrained beam in portal steel frame

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Defence Technology(防务技术) 2023年第7期25卷 174-191页

作者： yu-Xu Guo feng Xi Ying-Hua Tan feng liu Ya-Chao Hu School of Civil Engineering Shandong Jianzhu UniversityJinan250101PR China Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation Shandong University of Science and TechnologyQingdao266590PR China Key Laboratory of Building Structural Retrofitting and Underground Space Engineering Shandong Jianzhu UniversityJinan250101PR China

Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experimental measurement and numerical simulation techniques. Comprehensive parametric studies are carried out to discuss the influence of end connection types, temperature, impact velocity,impact mass and span-to-depth ratio(SDR) on the dynamic response of the beams. The characteristics of deformation, internal force and energy distribution about the restrained beams and its joints are investigated. A temperature dependent criterion for evaluating the frame joint performance is proposed to measure the degree of performance degradation and impact resistance of the joint. The dynamic displacement amplification factor in different temperature environments are proposed for the different beam end constraint types and SDRs. Results of the experimental and numerical analysis show that the welded connection(WC) of three typical joint types is the strongest, and the extended endplate connection(EEC) is the weakest in terms of the impact resistance performance. With regard to the failure mode of the joint, the failure positions of the WC and the welded-bolted connection are located in the inner web of the column. Meanwhile, the EEC is located in the connection position between the beam and the endplate. Three different internal force stages and two obvious critical temperature boundaries of the restrained beams emerge with the increase in temperature, and they have significant characteristics in terms of deformation trend, internal force transfer and energy distribution. During the impact, a phenomenon known as “compression arch action” develops into “catenary action” with the increase in deflection in the frame beam mechanism.

关键词： Restrained beam Connection Temperature Impact Failure modes Internal force mechanism

Waterbomb-origami inspired triboelectric nanogenerator for smart pavement-integrated traffic monitoring

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Nano Research 2022年第6期15卷 5450-5460页

作者： Yafeng Pang Xingyi Zhu Ying yu Shuainian liu yu Chen Yi feng Key Laboratory of Road and Traffic Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Civil and Environmental Engineering Shantou UniversityShantou 515063China School of Mechanical Engineering Tongji UniversityShanghai 200092China College of Electronic and Information Engineering Tongji UniversityShanghai 200092China

With a rapid development of intelligent transportation systems(ITSs),traffic monitoring has gained increasing attention.Here,we present a new kind of waterbomb-origami-inspired triboelectric nanogenerator(WO-TENG)as a traffic monitoring system to integrate smart pavement with lightweight,cost-effective,excellent deformability,flexibility,and self-rebounding properties.The electrical performance is significantly improved by more than 67%compared with current origami-based TENG,and multi tribo-pairs have great synchronicity.The fully-packaged self-driven WO-TENG is further developed to integrate smart pavement,which can successfully decouple the influence of vehicle speed and weight on the sensing accuracy.This phenomenon demonstrates the feasibility and stability of the WO-TENG for traffic monitoring.Independently of the voltage amplitude and time interval electrical wave,vehicle speed,number of vehicles,and types of vehicles can be further evaluated accurately.This work can not only address the challenge of traditional traffic monitoring system,but also promote the development of TENG based self-powered sensors in ITSs.

关键词： waterbomb-origami triboelectric nanogenerator smart pavement traffic monitoring

Linearized Double-Shock Approximate Riemann Solver for Augmented Linear Elastic Solid

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Numerical Mathematics(Theory,Methods and Applications) 2022年第1期15卷 141-164页

作者： Zhiqiang Zeng Chengliang feng Changsheng yu Tiegang liu LMIB and School of Mathematical Sciences Beihang UniversityBeijing 100191China

In this work,in order to capture discontinuities correctly in linear elastic solid,augmented internal energy is defined according to the first law of thermodynamics and Hooke’s law.The non-conservative linear elastic system is then rewritten into a conservative form with the help of an augmented total energy equation.We find that the non-physical oscillations occur to the popular HLL and HLLC approximate Riemann solvers when directly applied to simulate the augmented linear elastic solid.We analyze the intrinsic reason by defining a discrepancy factor which can be used to estimate the difference of the total stress across a contact discontinuity,where it is physically required to be continuous.We discover that non-physical oscillations inevitably appear in the vicinity of the contact discontinuity if this factor is away from zero for an approximate Riemann problem solver.In order to overcome this difficulty,we propose an approximate Riemann solver based on the linearized double-shock technique.Theoretical analysis and numerical results show that in comparison to the HLL and HLLC approximate Riemann solvers,the present linearized double-shock Riemann solver can eliminate the non-physical oscillations effectively.

关键词： Linear elastic solid approximate Riemann solver discrepancy factor