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Modeling size-dependent thermo-mechanical behaviors of shape memory polymer Bernoulli-Euler microbeam

Applied Mathematics and Mechanics(English Edition) 2019年第11期40卷 1531-1546页

作者： Bo ZHOU xueyao zheng Zetian KANG Shifeng XUE College of Pipeline and Civil Engineering China University of Petroleum (East China)

The objective of this paper is to model the size-dependent thermo-mechanical behaviors of a shape memory polymer (SMP) ***-dependent constitutive equations,which can capture the size effect of the SMP,are proposed based on the modified couple stress theory (MCST).The deformation energy expression of the SMP microbeam is obtained by employing the proposed size-dependent constitutive equation and Bernoulli-Euler beam *** SMP microbeam model,which includes the formulations of deflection,strain,curvature,stress and couple stress,is developed by using the principle of minimum potential energy and the separation of variables *** sizedependent thermo-mechanical and shape memory behaviors of the SMP microbeam and the influence of the Poisson ratio are numerically investigated according to the developed SMP microbeam *** show that the size effects of the SMP microbeam are significant when the dimensionless height is small ***,they are too slight to be necessarily considered when the dimensionless height is large *** bending flexibility and stress level of the SMP microbeam rise with the increasing dimensionless height,while the couple stress level declines with the increasing dimensionless *** larger the dimensionless height is,the more obvious the viscous property and shape memory effect of the SMP microbeam *** Poisson ratio has obvious influence on the size-dependent behaviors of the SMP *** paper provides a theoretical basis and a quantitatively analyzing tool for the design and analysis of SMP micro-structures in the field of biological medicine,microelectronic devices and micro-electro-mechanical system (MEMS) self-assembling.

关键词： shape memory polymer (SMP) size-dependent constitutive equation microbeam model size effect modified couple stress theory (MCST)

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Constitutive model for epoxy shape memory polymer with regulable phase transition temperature

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International Journal of Smart and Nano Materials 2021年第1期12卷 72-87页

作者： Fei Zhao xueyao zheng Shichen Zhou Bo Zhou Shifeng Xue Yi Zhang College of Pipeline and Civil Engineering China University of Petroleum(East China)QingdaoChina

The epoxy shape memory polymer(SMP)with adjustable phase transition temperature is a kind of high-performance shape mem-ory polymer,which can change its phase transition temperature and improve its mechanical properties through the process of photo *** epoxy SMP constitutive model combining phase transition and viscoelasticity is established by discretizing the epoxy SMP into several glass phase units and rubbery phase units in this *** model includes the viscoelastic constitutive equa-tions of glass phase units and rubber phase units,the parameter expression during shape memory process,and material parameter equation during photocuring *** the stress relaxation behavior of epoxy SMP at different temperatures and the change of material parameters during the photo-curing process are simu-lated numerically,and the simulation results perform consistency with the experimental *** model can not only relate shape memory effect and phase transformation in physics but also better characterize the viscoelastic properties of SMP and predict the shape memory response of SMP.

关键词： Epoxy shape memory polymer constitutive model regulable phase transition temperature photo curing

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Size-dependent behaviors of viscoelastic axially functionally graded Timoshenko micro-beam considering Poisson effects

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Journal of Southeast University(English Edition) 2020年第2期36卷 170-180页

作者： Zhou Bo zheng xueyao Kang Zetian Xue Shifeng College of Pipeline and Civil Engineering China University of Petroleum (East China) Qingdao 266580 China

A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial *** size effect is incorporated by employing the modified couple stress theory and Kelvin-Voigt viscoelastic model,so that viscous components are included in the stress and the deviatoric segments of the symmetric couple stress *** components of strain,curvature,stress and couple stress are formulated by combining them with the Timoshenko beam *** on the Hamilton principle,the governing differential equations and boundary conditions for the micro-beam are expressed with arbitrary beam section shape and arbitrary type of *** size effect,FG effect,Poisson effect,and the influence of the beam section shape on the mechanical behaviors of viscoelastic FG micro-beams are investigated by taking the simply supported micro-beam subjected to point load as an *** show that the size effect on deflection,normal stress and couple stress are obvious when the size of the micro-beam is small enough,and the FG effects are obvious when the size of the micro-beam is large ***,the Poisson ratio influences the size effect significantly and the beam section shape is also an important factor influencing the mechanical behavior of the micro-beam.

关键词： viscoelastic functionally graded micro-beam size-dependent behaviors size effect functionally graded effect Poisson effect space

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基于修正偶应力理论的Euler-Bernoulli微梁的尺寸效应研究

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应用力学学报 2019年第6期36卷 1442-1450,I0013页

作者：郑雪瑶周博薛世峰中国石油大学(华东)储运与建筑工程学院

为研究Euler-Bernoulli微梁的尺寸效应,基于修正偶应力理论推导了梁的变形能计算公式,得到了反映尺寸效应的量纲归一化刚度公式;利用最小势能原理求解了Euler-Bernoulli微梁,得到了反映尺寸效应的量纲归一化挠曲线方程和量纲归一化最大... 详细信息

为研究Euler-Bernoulli微梁的尺寸效应,基于修正偶应力理论推导了梁的变形能计算公式,得到了反映尺寸效应的量纲归一化刚度公式;利用最小势能原理求解了Euler-Bernoulli微梁,得到了反映尺寸效应的量纲归一化挠曲线方程和量纲归一化最大应力方程。通过数值模拟计算,研究了Euler-Bernoulli微梁的刚度和强度等力学特性的尺寸效应,分析了泊松比对Euler-Bernoulli微梁的刚度和强度等力学特性的影响。分析结果表明:在微尺寸范围内Euler-Bernoulli微梁的刚度随尺寸的增大而减小,其强度则随尺寸的增大而增大,当量纲为一的高度大于20时,Euler-Bernoulli微梁的尺寸效应不明显,可忽略不计;泊松比越大,微梁强度越大,刚度越小,当量纲为一的高度大于20时,泊松比对微梁强度和刚度的影响可忽略不计。

关键词： Euler-Bernoulli微梁尺寸效应 MEMS 能量法变分法

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基于修正偶应力理论的Timoshenko微梁模型和尺寸效应研究

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应用数学和力学 2019年第12期40卷 1321-1334页

作者：周博郑雪瑶康泽天薛世峰中国石油大学(华东)储运与建筑工程学院

基于修正偶应力理论,将Timoshenko微梁的应力、偶应力、应变、曲率等基本变量,描述为位移分量偏导数的表达式.根据最小势能原理,推导了决定Timoshenko微梁位移场的位移场控微分方程.利用级数法求解了任意载荷作用下Timoshenko简支微梁... 详细信息

基于修正偶应力理论,将Timoshenko微梁的应力、偶应力、应变、曲率等基本变量,描述为位移分量偏导数的表达式.根据最小势能原理,推导了决定Timoshenko微梁位移场的位移场控微分方程.利用级数法求解了任意载荷作用下Timoshenko简支微梁的位移场控微分方程,得到了反映尺寸效应的挠度、转角及应力的偶应力理论解.通过对承受余弦分布载荷Timoshenko简支微梁的数值计算,研究了Timoshenko微梁的挠度、转角和应力的尺寸效应,分析了Poisson比对Timoshenko微梁力学行为及其尺寸效应的影响.结果表明:当截面高度与材料特征长度的比值小于5时,Timoshenko微梁的刚度和强度均随着截面高度的减小而显著提高,表现出明显的尺寸效应;当截面高度与材料特征长度的比值大于10时,Timoshenko微梁的刚度与强度均趋于稳定,尺寸效应可以忽略;材料Poisson比是影响Timoshenko微梁力学行为及尺寸效应的重要因素,Poisson比越大Timoshenko微梁刚度和强度的尺寸效应越显著.该文建立的Timoshenko微梁模型,能有效描述Timoshenko微梁的力学行为及尺寸效应,可为微电子机械系统(MEMS)中的微结构设计与分析提供理论基础和技术参考.

关键词： Timoshenko微梁尺寸效应位移场控方程级数法微电子机械系统

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Intermittent High Glucose Reduces Androgen Receptor Expression of HUVECs via PI3K/Akt/mTOR signaling Pathway

Intermittent High Glucose Reduces Androgen Receptor Expressi...

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中华医学会第十一次全国内分泌学学术会议

作者： Lin Li,xueyao YIN,FENGPING zheng,FANG WU,JIAQIANG ZHOU,HONG LI Department of Endocrinology,the Affiliated Sir Run Run Shaw Hospital,School of Medicine,Zhejiang University

Objective To elucidate the effect of intermittent high glucose on androgen receptor(AR) expression and the PI3K/Akt/ roTOR signaling pathway in human umbilical vein endothelial cells(HUVECs). Methods HUVECs were cultured in endothelial cell growth media(ECM) with supplemental fetal bovine serum(5%),endothelial cell growth supplement(IX),penicillin(10U/mL) and streptomycin(10μg/mL).HUVECs were incubated in media with different glucose concentrations:5.5mmol/L(N),30mmol/ L(H),or alternating 5.5 and 30mmol/1 glucose twice a day(F)

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Transcriptome analysis reveals dynamic changes in the salt stress response in Salix

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Journal of Forestry Research 2020年第5期31卷 1851-1862页

作者： Jie Zhou Jing Huang xueyao Tian Jiwei zheng Xudong He Jiangsu Academy of Forestry Nanjing 211153People’s Republic of China Nanjing Forestry University Nanjing 210037People’s Republic of China

Soil salinization is a serious ecological problem worldwide and information regarding the salt tolerance mechanisms of Salix is *** elucidate the dynamic changes in the molecular mechanisms of Salix under salt stress,we generated gene expression profiles and examined changes in the expression of those ***-Seq was used to produce six cDNA libraries constructed from the leaves of Salix ×jiangsuensis CL‘J2345’treated with NaCl for 0,2,6,12,24 and 48 *** total,249 million clean reads were assembled into 12,739 unigenes,all of which were clustered into 10 profiles based on their temporal expression *** analysis revealed that as an early defense response,the biosynthesis pathways of cutin,suberin and wax,which are involved in cell wall structure,were activated beginning at 2 *** expression of secondary metabolism genes,including those involved in the phenylpropanoid,flavonoid,stilbenoid,diarylheptanoid and gingerol pathways,peaked at 6 h and 24 h;the upregulated genes were mainly involved in plant hormone pathways and beta-alanine,galactose and betalain *** identified roles of key phytohormones and found ETH to be the major signaling molecule activating TFs at 12 h;ETH,ABA,IAA and SA were the key molecules at 24 ***,we found that the upregulated genes were associated with elevated levels of amino acids,sucrose,inositol,stress proteins and ROS-scavenging enzymes,contributing to the maintenance of water *** research constitutes the first detailed analysis of salt stress-related mechanisms in Salix and identifies potential targets for genetic manipulation to improve yields.

关键词： De novo assembly RNA-Seq profiling Salix Salt stress Temporal specificity

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Improving model performance in mapping cropland soil organic matter using time-series remote sensing data

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Journal of Integrative Agriculture 2024年第8期23卷 2820-2841页

作者： Xianglin Zhang Jie Xue Songchao Chen Zhiqing Zhuo zheng Wang xueyao Chen Yi Xiao Zhou Shi Institute of Applied Remote Sensing and Information Technology College of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China Department of Land Management Zhejiang UniversityHangzhou 310058China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311215China Institute of Digital Agriculture Zhejiang Academy of Agricultural SciencesHangzhou 310021China Key Laboratory of Spectroscopy Sensing Ministry of Agriculture and Rural AffairsHangzhou 310058China

Faced with increasing global soil degradation,spatially explicit data on cropland soil organic matter(SOM)provides crucial data for soil carbon pool accounting,cropland quality assessment and the formulation of effective management *** a spatial information prediction technique,digital soil mapping(DSM)has been widely used to spatially map soil information at different ***,the accuracy of digital SOM maps for cropland is typically lower than for other land cover types due to the inherent difficulty in precisely quantifying human *** overcome this limitation,this study systematically assessed a framework of“information extractionfeature selection-model averaging”for improving model performance in mapping cropland SOM using 462 cropland soil samples collected in Guangzhou,China in *** results showed that using the framework of dynamic information extraction,feature selection and model averaging could efficiently improve the accuracy of the final predictions(R^(2):0.48 to 0.53)without having obviously negative impacts on *** the dynamic information of the environment was an efficient way to generate covariates that are linearly and nonlinearly related to SOM,which improved the R^(2)of random forest from 0.44 to 0.48 and the R^(2)of extreme gradient boosting from 0.37to *** recursive feature selection(FRFS)is recommended when there are relatively few environmental covariates(500).The Granger-Ramanathan model averaging approach could improve the prediction accuracy and average *** the structures of initial prediction models are similar,increasing in the number of averaging models did not have significantly positive effects on the final *** the advantages of these selected strategies over information extraction,feature selection and model averaging have a great potential for high-accuracy soil mapping

关键词： cropland soil organic matter digital soil mapping machine learning feature selection model averaging

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Intermittent High Glucose Potentiates Palmitate Induced Apoptosis of Hepatocytes Via Mitochondrial Permeability Transition

Intermittent High Glucose Potentiates Palmitate Induced Apop...

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中华医学会第十二次全国内分泌学学术会议

作者： xueyao Yin Qianqian Pan Saifei Zhang fenping zheng Hong Li The Affiliated Sir Run Run Shaw Hospital School of MedicineZhejiang University

Aim To clarify the effect of glucose fluctuation on the hepatocytes apoptosis induced by palmitate(PA),and the potential mechanisms related with mitochondrial permeability transition (mPTP). Methods Hepatocytes L02 we...

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寒地桑叶多糖化学组成及其生物活性分析

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食品科学 2024年第15期45卷 59-66页

作者：韩晓云郑丹张雪瑶杜宝昌孙庆申黑龙江大学生命科学学院农业微生物技术教育部工程研究中心黑龙江省寒区植物基因与生物发酵重点实验室黑龙江省普通高校分子生物学重点实验室黑龙江省普通高校微生物重点实验室黑龙江哈尔滨150080 甘南林场黑龙江齐齐哈尔162100

为探究龙桑一号(Morus abla *** 1)桑叶多糖(mulberry leaf polysaccharide,MLP)的结构及功能性质,采用水提法提取其MLP,并对该多糖的结构性质以及体外降糖、抗氧化和免疫活性进行分析。结果表明:提取MLP得率为(16.16±0.30)mg/g,其中... 详细信息

为探究龙桑一号(Morus abla *** 1)桑叶多糖(mulberry leaf polysaccharide,MLP)的结构及功能性质,采用水提法提取其MLP,并对该多糖的结构性质以及体外降糖、抗氧化和免疫活性进行分析。结果表明:提取MLP得率为(16.16±0.30)mg/g,其中总糖质量分数为(57.16±4.00)%,糖醛酸质量分数为(30.97±2.06)%。凝胶渗透色谱测得MLP分子质量主要分布在21.74 kDa,其单糖组成主要包括葡萄糖、鼠李糖、半乳糖、木糖、糖醛酸(包括葡萄糖醛酸、半乳糖醛酸和甘露糖醛酸)、甘露糖,物质的量比为59.17∶22.31∶10.44∶2.65∶2.28∶1.07。通过傅里叶变换红外光谱和原子力显微镜分析发现MLP是一种吡喃糖,具有分支和相互交织、螺旋聚集的特点。MLP对α-葡萄糖苷酶和α-淀粉酶抑制作用的半数有效浓度(concentration for 50%of maximal effect,EC_(50))分别为1.81 mg/mL和2.91 mg/mL,其活性相当于阿卡波糖的49.17%和37.80%;MLP清除1,1-二苯基-2-三硝基苯肼自由基、2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基和羟自由基的EC_(50)分别为0.54、0.60 mg/mL和1.77 mg/mL,清除自由基的效果分别相当于抗坏血酸的4.77%、38.03%和19.94%;MLP可以作用于小鼠巨噬细胞RAW264.7,使其促炎因子NO、肿瘤坏死因子-α、白细胞介素-6和白细胞介素-1β的分泌量增加,增强巨噬细胞增殖作用和提高吞噬能力,从而增强免疫调节作用。本研究结果可为寒地桑叶的应用和功能评价提供实验数据。

关键词：寒地桑叶多糖结构特性免疫活性

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