背景:随着对干细胞技术研究的深入,如何使其准确归巢成为临床应用中的一大难题。除药物和趋化因子等信号的诱导外,电场也被广泛应用于指导干细胞的定向迁移,并可增强其迁移速度和定向性。目的:旨在分析总结电场对干细胞迁移特性的影响,...背景:随着对干细胞技术研究的深入,如何使其准确归巢成为临床应用中的一大难题。除药物和趋化因子等信号的诱导外,电场也被广泛应用于指导干细胞的定向迁移,并可增强其迁移速度和定向性。目的:旨在分析总结电场对干细胞迁移特性的影响,同时综述可能的作用机制。方法:通过检索Pub Med和中国知网数据库,收集截至2024年3月的相关文献,英文检索词:“stem cells,direct current electric field,pulsed electric field,migration,electric field device,mechanism”;中文检索词:“干细胞,直流电场,脉冲电场,迁移,电场装置,机制”。排除不能获取全文和与主题无关的文献。结果与结论:根据筛选要求共纳入58篇文献,包括中文文献15篇及英文文献43篇。文献以脂肪间充质干细胞、骨髓间充质干细胞、神经干细胞、表皮干细胞、人胚胎干细胞和人诱导性多功能干细胞为研究对象,在迁移装置中研究电场的不同参数对上述干细胞迁移的影响及其机制。(1)电场作为一种简单、无创且稳定的干预方式在指导干细胞定向迁移的过程中起着积极作用;(2)不同类型的干细胞发生趋电性迁移的方向不同,同时大部分干细胞的迁移速度和定向性是随着电场强度增加而增加的;(3)不同的电场装置在观测干细胞迁移时的侧重点不同,可根据实验目的而择优选择相关装置;(4)不同干细胞趋电性迁移的机制不完全相同,多数干细胞迁移过程中有MAPK通路、ROCK活化以及PI3K功能的参与,同时还有其他蛋白质复合物与信号通路参与调控该过程;(5)除电场参数不同之外,细胞本身的衰老情况和培养环境也会对趋电性迁移的结果产生影响。总而言之,电场作为一种影响干细胞迁移特性的重要信号,与其他新兴材料结合在组织工程应用中展现出了一定的潜力,有望在指导干细胞归巢方面发挥更加重要的作用,促进骨组织再生和修复以及神经系统、自身免疫系统以及肿瘤等疾病的研究取得更大的突破。展开更多
针对电力需求响应机制下电动汽车(electric vehicle,EV)共享充电调度场景中多元主体决策间的复杂博弈关系,该文提出了一种基于电-碳联合机制的EV共享充电两阶段博弈协同调度策略。首先,依据电-碳联合市场交易利润导向,构建第一阶段完全...针对电力需求响应机制下电动汽车(electric vehicle,EV)共享充电调度场景中多元主体决策间的复杂博弈关系,该文提出了一种基于电-碳联合机制的EV共享充电两阶段博弈协同调度策略。首先,依据电-碳联合市场交易利润导向,构建第一阶段完全信息动态博弈的电-碳联合竞价策略;其次,依据电-碳联合市场分配导向,构建第二阶段序贯博弈的电-碳联合分配策略。该两阶段策略分别采用交替方向乘子(alternating direction method of multipliers,ADMM)和最优响应算法进行优化,确保多主体共享充电最优均衡。算例分析表明,该策略可促进各主体参与电-碳联合市场交易,在确保自身利益最大化的前提下,实现EV充电负荷和共享充电设施合理匹配,降低充电成本,优化EV共享充电期间的碳排放量,其对“碳达峰、碳中和”政策实施意义重大。展开更多
During the test, the seed yield, Iabor efficiency, harvesting costs and eco-nomic benefits were compared and analyzed between mechanical harvesting tech-noIogy and traditional artificial harvesting technoIogy of Chine...During the test, the seed yield, Iabor efficiency, harvesting costs and eco-nomic benefits were compared and analyzed between mechanical harvesting tech-noIogy and traditional artificial harvesting technoIogy of Chinese miIk vetch seeds to studied the mechanical harvesting technoIogy and appIication effects. The resuIts showed that mechanical harvesting technoIogy increased the yield of 92.7 kg/hm2, reducing the seeds Ioss. It improved the Iabor efficiency and reduced the harvesting cost. For exampIe, a rice combine harvester was the equal of 18-20 person in the harvest quantity in one day, which directIy reduced the Iabor cost of 2 175-3 000 yuan/hm2 and increased the economic income of 3 307-4 099 yuan/hm2. So it wiI pIay an important roIe in soIving the shortage of Chinese miIk vetch seeds and ac-ceIerating the deveIopment of Chinese miIk vetch green manure crop in south China rice region.展开更多
Epoxy resin is widely used in the support,insulation,and packaging components of electrical equipment owing to their excellent insulation,thermal,and mechanical properties.However,epoxy-resin insulation often suffers ...Epoxy resin is widely used in the support,insulation,and packaging components of electrical equipment owing to their excellent insulation,thermal,and mechanical properties.However,epoxy-resin insulation often suffers from thermal and mechanical stresses under extreme environmental conditions and a compact design,which can induce electrical tree degradation and insulation failure in electrical equipment.In this study,the photoelastic method is employed to investigate the thermal-mechanical coupling stress dependence of the electrical treeing behavior of epoxy resin.Typical electrical tree growth morphology and stress distribution were observed using the photoelastic method.The correlation between the tree length and overall accumulated damage with an increase in mechanical stress is determined.The results show that compressive stress retards the growth of electrical trees along the electric field,while tensile stress has accelerating effects.This proves that the presence of thermal stress can induce more severe accumulated damage.展开更多
field-grading composite with a low switching field,stable nonlinear conductivity performance,and excellent mechanical and thermal properties was prepared by using hybrid ZnO micro-spherical varistors of different part...field-grading composite with a low switching field,stable nonlinear conductivity performance,and excellent mechanical and thermal properties was prepared by using hybrid ZnO micro-spherical varistors of different particle sizes as the fillers and silicone rubber as the matrix.The hybrid effects of particle size on the electrical,mechanical,and thermal properties of ZnO micro-spherical varistors composites are investigated.An increase in the ZnO micro-spherical varistor size in the composites will lower the switching field but lead to degradation of the mechanical properties and stability of the nonlinear conductivity properties.The silicone rubber is incorporated with a mixture of hybrid ZnO micro-spherical varistors of different sizes at an optimal mass ratio range exhibited low switching field,stable nonlinear conductivity performance,and excellent mechanical and thermal properties.Our findings are helpful to comprehensively regulate performance of advanced field-grading materials and increase stability and durability of electronic and electrical devices.展开更多
A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial ten...A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial tension/compression and bending/shearing couplings as well as the mutual reactions of fiber yarns. The method determining microstructure by using woven parameters is described for a typical 3D woven composite material. An analytical cell, constructed by a minimum periodic section of yarn and interlayer matrix, is adopted. Micro stresses in the cell under in-plane tensile loading are obtained by using the proposed beam model and macro modulus is then obtained by the averaging method. Material tests and a 2D micro FEM analysis are made to evaluate this model. Analyses reveal that micro stress caused by tensile/bending coupling effect is not negligible in the stress analysis.展开更多
In spite of their extraordinary performance, AlGaN/GaN high electron mobility transistors (HEMTs) still lack solid reliability. Devices under accelerated DC stress tests (off-state, VDS = 0 state, and on-state step...In spite of their extraordinary performance, AlGaN/GaN high electron mobility transistors (HEMTs) still lack solid reliability. Devices under accelerated DC stress tests (off-state, VDS = 0 state, and on-state step-stress) are investigated to help us identify the degradation mechanisms of the AlGaN/GaN HEMTs. All our findings are consistent with the degradation mechanism based on crystallographic-defect formation due to the inverse piezoelectric effects in Ref. [1] (Joh J and del Alamo J A 2006 IEEE IDEM Tech. Digest p. 415). However, under the on-state condition, the devices are suffering from both inverse piezoelectric effects and hot electron effects, and so to improve the reliability of the devices both effects should be taken into consideration.展开更多
As an important component of nanodevices and nanomachine constructions, the mechanical performance of nanowires (NWs) has been a subject of intense research efforts due to gaining relevance in controlling functional...As an important component of nanodevices and nanomachine constructions, the mechanical performance of nanowires (NWs) has been a subject of intense research efforts due to gaining relevance in controlling functionality of nanoelectromechanical systems (NEMS); meanwhile, one of the characteristics of the NEMS is the dependence of the functionality of the systems upon the applied electric field. The study of the electric effects on the Young's modulus of nanostructures is of certain usefulness in the design of NEMS and the precise measurement of mechanical properties of one-dimensional nanostructures. This paper reviews the origin of the size-dependence of the elastic property of NWs and the factors influencing the discrepancies and inconsistencies in the measured values of the Young's modulus for the NW, besides the surface effects, nonlinear effects, the electromechanical coupling effects as a possible effect responsible for the differences in quantitative and qualitative performance of the measured Young's modulus for the NWs versus the diameter are clarified.展开更多
文摘背景:随着对干细胞技术研究的深入,如何使其准确归巢成为临床应用中的一大难题。除药物和趋化因子等信号的诱导外,电场也被广泛应用于指导干细胞的定向迁移,并可增强其迁移速度和定向性。目的:旨在分析总结电场对干细胞迁移特性的影响,同时综述可能的作用机制。方法:通过检索Pub Med和中国知网数据库,收集截至2024年3月的相关文献,英文检索词:“stem cells,direct current electric field,pulsed electric field,migration,electric field device,mechanism”;中文检索词:“干细胞,直流电场,脉冲电场,迁移,电场装置,机制”。排除不能获取全文和与主题无关的文献。结果与结论:根据筛选要求共纳入58篇文献,包括中文文献15篇及英文文献43篇。文献以脂肪间充质干细胞、骨髓间充质干细胞、神经干细胞、表皮干细胞、人胚胎干细胞和人诱导性多功能干细胞为研究对象,在迁移装置中研究电场的不同参数对上述干细胞迁移的影响及其机制。(1)电场作为一种简单、无创且稳定的干预方式在指导干细胞定向迁移的过程中起着积极作用;(2)不同类型的干细胞发生趋电性迁移的方向不同,同时大部分干细胞的迁移速度和定向性是随着电场强度增加而增加的;(3)不同的电场装置在观测干细胞迁移时的侧重点不同,可根据实验目的而择优选择相关装置;(4)不同干细胞趋电性迁移的机制不完全相同,多数干细胞迁移过程中有MAPK通路、ROCK活化以及PI3K功能的参与,同时还有其他蛋白质复合物与信号通路参与调控该过程;(5)除电场参数不同之外,细胞本身的衰老情况和培养环境也会对趋电性迁移的结果产生影响。总而言之,电场作为一种影响干细胞迁移特性的重要信号,与其他新兴材料结合在组织工程应用中展现出了一定的潜力,有望在指导干细胞归巢方面发挥更加重要的作用,促进骨组织再生和修复以及神经系统、自身免疫系统以及肿瘤等疾病的研究取得更大的突破。
文摘针对电力需求响应机制下电动汽车(electric vehicle,EV)共享充电调度场景中多元主体决策间的复杂博弈关系,该文提出了一种基于电-碳联合机制的EV共享充电两阶段博弈协同调度策略。首先,依据电-碳联合市场交易利润导向,构建第一阶段完全信息动态博弈的电-碳联合竞价策略;其次,依据电-碳联合市场分配导向,构建第二阶段序贯博弈的电-碳联合分配策略。该两阶段策略分别采用交替方向乘子(alternating direction method of multipliers,ADMM)和最优响应算法进行优化,确保多主体共享充电最优均衡。算例分析表明,该策略可促进各主体参与电-碳联合市场交易,在确保自身利益最大化的前提下,实现EV充电负荷和共享充电设施合理匹配,降低充电成本,优化EV共享充电期间的碳排放量,其对“碳达峰、碳中和”政策实施意义重大。
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201103005)National Green manure Germplasm Resources Platform(2012-019)+1 种基金Crop Germplasm Resources Conservation and Utilization Project(NB2013-2130135-34)International Plant Nutrition Institute(IPNI)Project(Hunan-16)~~
文摘During the test, the seed yield, Iabor efficiency, harvesting costs and eco-nomic benefits were compared and analyzed between mechanical harvesting tech-noIogy and traditional artificial harvesting technoIogy of Chinese miIk vetch seeds to studied the mechanical harvesting technoIogy and appIication effects. The resuIts showed that mechanical harvesting technoIogy increased the yield of 92.7 kg/hm2, reducing the seeds Ioss. It improved the Iabor efficiency and reduced the harvesting cost. For exampIe, a rice combine harvester was the equal of 18-20 person in the harvest quantity in one day, which directIy reduced the Iabor cost of 2 175-3 000 yuan/hm2 and increased the economic income of 3 307-4 099 yuan/hm2. So it wiI pIay an important roIe in soIving the shortage of Chinese miIk vetch seeds and ac-ceIerating the deveIopment of Chinese miIk vetch green manure crop in south China rice region.
基金Supported by the National Natural Science Foundation of China(52377153)and Science and Technology Project of Hebei Education Department(QN2023073).
文摘Epoxy resin is widely used in the support,insulation,and packaging components of electrical equipment owing to their excellent insulation,thermal,and mechanical properties.However,epoxy-resin insulation often suffers from thermal and mechanical stresses under extreme environmental conditions and a compact design,which can induce electrical tree degradation and insulation failure in electrical equipment.In this study,the photoelastic method is employed to investigate the thermal-mechanical coupling stress dependence of the electrical treeing behavior of epoxy resin.Typical electrical tree growth morphology and stress distribution were observed using the photoelastic method.The correlation between the tree length and overall accumulated damage with an increase in mechanical stress is determined.The results show that compressive stress retards the growth of electrical trees along the electric field,while tensile stress has accelerating effects.This proves that the presence of thermal stress can induce more severe accumulated damage.
基金supported by the National Key R&D Program of China (2018YFE0200100)Natural Science Foundation of China (51921005)National Postdoctoral Program for Innovative Talents (BX20200204).
文摘field-grading composite with a low switching field,stable nonlinear conductivity performance,and excellent mechanical and thermal properties was prepared by using hybrid ZnO micro-spherical varistors of different particle sizes as the fillers and silicone rubber as the matrix.The hybrid effects of particle size on the electrical,mechanical,and thermal properties of ZnO micro-spherical varistors composites are investigated.An increase in the ZnO micro-spherical varistor size in the composites will lower the switching field but lead to degradation of the mechanical properties and stability of the nonlinear conductivity properties.The silicone rubber is incorporated with a mixture of hybrid ZnO micro-spherical varistors of different sizes at an optimal mass ratio range exhibited low switching field,stable nonlinear conductivity performance,and excellent mechanical and thermal properties.Our findings are helpful to comprehensively regulate performance of advanced field-grading materials and increase stability and durability of electronic and electrical devices.
文摘A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial tension/compression and bending/shearing couplings as well as the mutual reactions of fiber yarns. The method determining microstructure by using woven parameters is described for a typical 3D woven composite material. An analytical cell, constructed by a minimum periodic section of yarn and interlayer matrix, is adopted. Micro stresses in the cell under in-plane tensile loading are obtained by using the proposed beam model and macro modulus is then obtained by the averaging method. Material tests and a 2D micro FEM analysis are made to evaluate this model. Analyses reveal that micro stress caused by tensile/bending coupling effect is not negligible in the stress analysis.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CBA00600)the National Natural Science Foundation of China (Grant No. 61106106)the Fundamental Research Funds for the Central Universities (Grant No. K50510250006)
文摘In spite of their extraordinary performance, AlGaN/GaN high electron mobility transistors (HEMTs) still lack solid reliability. Devices under accelerated DC stress tests (off-state, VDS = 0 state, and on-state step-stress) are investigated to help us identify the degradation mechanisms of the AlGaN/GaN HEMTs. All our findings are consistent with the degradation mechanism based on crystallographic-defect formation due to the inverse piezoelectric effects in Ref. [1] (Joh J and del Alamo J A 2006 IEEE IDEM Tech. Digest p. 415). However, under the on-state condition, the devices are suffering from both inverse piezoelectric effects and hot electron effects, and so to improve the reliability of the devices both effects should be taken into consideration.
基金supported by the National Basic Research Program of China (No2007CB607506)the NSFC's program(No90405005)+1 种基金the PhD Fund (No20050730016)the Fund of the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology)(NoWUT2005Z04)
文摘As an important component of nanodevices and nanomachine constructions, the mechanical performance of nanowires (NWs) has been a subject of intense research efforts due to gaining relevance in controlling functionality of nanoelectromechanical systems (NEMS); meanwhile, one of the characteristics of the NEMS is the dependence of the functionality of the systems upon the applied electric field. The study of the electric effects on the Young's modulus of nanostructures is of certain usefulness in the design of NEMS and the precise measurement of mechanical properties of one-dimensional nanostructures. This paper reviews the origin of the size-dependence of the elastic property of NWs and the factors influencing the discrepancies and inconsistencies in the measured values of the Young's modulus for the NW, besides the surface effects, nonlinear effects, the electromechanical coupling effects as a possible effect responsible for the differences in quantitative and qualitative performance of the measured Young's modulus for the NWs versus the diameter are clarified.