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Investigation on abnormal group velocities in 1D coaxial photonic crystals

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Chinese Science Bulletin 2006年第11期51卷 1281-1286页

作者： TONG Yuanwei zhang yewen HE Li LI Hongqiang CHEN Hong Pohl Institute of Solid State Physics Tongji University Shanghai 200092 China School of Electronics and Information Engineering Tongji UniversityShanghai 200092 China University of Shanghai for Science and Technology Shanghai 200093 China

In this paper, the group velocities of electromagnetic wave for a one-dimensional coaxial photonic crystal in the stop bands with and without defect mode are studied. The results show that the group velocities exceed c (the speed of light in vac- uum) in the stop band and it tends to be very slow in the defect mode. The group velocities also are ob- tained using the method of the transmission line and transmission matrix. The simulating results agree well with the experimental.

关键词：同轴晶体群速度超光速固体物理

Action of space charge on aging and breakdown of polymers

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Chinese Science Bulletin 2001年第10期46卷 796-800页

作者： LI Jixiao zhang yewen XIA Zhongfu QIN Xiaoqiu PENG Zongren Pohl Institute of the Solid State Physics Tongji UniversityShanghai 200092China State Key Laboratory of Electrical Insulation for Power Equipment Xi’an UniversityXi’an 710049China

The study on how space charges affect aging and breakdown of polymers becomes one of the most important domains. Most of the models are based on the injected charges increasing the local field to induce the breakdown of polymers and breaking the large molecule chains. These models ignore the effects of space charge on the microstruc-ture of dielectric materials. In this review, with the calculation of the electromagnetic energy and the electromechanical energy around a trapped charge and with some new experimental results, it is proved that aging and breakdown in polymers are caused during the detrapping of the trapped charges. Aging and breakdown of the polymers are related to the release of the electromechanical energy around trapped charges.

关键词： space charge breakdown polymer.

Biomass Carbon Improves the Adsorption Performance of Gangue-Based Ceramsites:Adsorption Kinetics and Mechanism Analysis

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Journal of Renewable Materials 2023年第12期11卷 4161-4174页

作者： Haodong Li Huiling Du Le Kang yewen zhang Tong Lu Yuchan zhang Lan Yang Shijie Song College of Materials Science and Engineering Xi’an University of Science and TechnologyXi’an710054China Shccig Yulin Chemical Co. Ltd.Management Committee of Yushen Industrial ZoneYulinChina

The large accumulation of coal gangue,a common industrial solid waste,causes severe environmental problems,and green development strategies are required to transform this waste into high-value-added *** this study,low-cost ceramsites adsorbents were prepared from waste gangue,silt coal,and peanut shells and applied to remove the organic dye methylene blue from *** investigated the microstructure of ceramsites and the effects of the sintering atmosphere,sintering temperature,and solution pH on their adsorption *** ceramsites sintered at 800℃under a nitrogen atmosphere exhibited the largest three-dimensional-interconnected hierarchical porous structure among the prepared ceramsites;further,it exhibited the highest methylene blue adsorption performance,with an adsorption capacity of 0.954 mg·g^(−1),adsorption efficiency of over 95%,and adsorption equilibrium time of 1 h at a solution pH of *** removal efficiency remained greater than 75%after five adsorption *** adsorption kinetics data were analyzed using various models,including the pseudosecond-order kinetic model and Langmuir equation,and the adsorption was attributed to electrostatic interactions between the dyes and ceramsites,n-interactions,and hydrogen *** prepared coal gangue ceramsites exhibited excellent adsorption capacities,removal rates,and cyclic stabilities,demonstrating their promising application prospects for the comprehensive utilization of solid waste and for wastewater treatment.

关键词： Porous ceramsites adsorption biological carbon kinetic analysis adsorption mechanism

Comparison Between Thermally Stimulated Discharge Method and Photo-stimulated Discharge Method for Measuring Space Charge Traps Energy

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高电压技术 2013年第8期39卷 1845-1851页

作者： ZHU Zhi'en zhang yewen AN Zhenlian ZHENG Feihu LEI Qingquan Department of Electrical Engineering Tongji University Shanghai 201804 China NARI Group Corporation (State Grid Electric Power Research Institute) Nanjing 210003 China State Key Laboratory Breeding Base of Dielectrics Engineering Harbin University of Science and Technology Harbin 150080 Chinat

The space charge behavior of a dielectric under HVDC is influenced by the charge trap energy distribution in it. Hence, we in- vestigated the charge trap distributions in several kinds of typical polymer materials using thermally stimulated discharge (TSD) and photo-stimulated discharge (PSD) methods, respectively. The experimental results show that,there is a significant difference between the trap energy distributions obtained by the two methods, but the difference decreases with the increase of the melting point of polymers. This is attributed to the change of the trap center environment during TSD caused by the increasing movements of both main chains and branched chains in polymers. PSD method is more accurate for investigating charge trap distribution in dielectrics, especially for polymers with low melting points.

关键词：陷阱分布空间电荷热刺激放电放电方法光刺激电法测量电介质材料能源

绝缘电介质薄膜中空间电荷分布测量技术的研究进展

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高电压技术 2020年第7期46卷 2460-2470页

作者：郑飞虎张冶文同济大学电气工程系上海201804

绝缘电介质薄膜广泛用作为高压电气设备中的绝缘材料和传感器件中电介质功能材料,如果用在直流高压应用条件下,空间电荷分布是其重要的特性表征。如果用于功能电介质,空间电荷分布是其功能实现的决定性因素之一。为此总结了厚度为数微... 详细信息

绝缘电介质薄膜广泛用作为高压电气设备中的绝缘材料和传感器件中电介质功能材料,如果用在直流高压应用条件下,空间电荷分布是其重要的特性表征。如果用于功能电介质,空间电荷分布是其功能实现的决定性因素之一。为此总结了厚度为数微米至几十微米的薄膜电介质中空间电荷分布测量方法的研究进展,按照测量的空间分辨率分别介绍了压力波法、热扰动法、电声反射法和基于飞秒脉冲激光器光电测量方法的测量原理。比较了这几种测量方法的特点,讨论了影响测量分辨率的几个关键因素:如对介质的扰动方式、对介质响应信号的探测方式以及对响应信号处理的解卷积方法。压力波法和热扰动法是其中较为成熟有效的测量方法,分辨率介于亚微米及数微米之间,扰动方法及信号监测都相对容易实现,而热扰动法虽然较容易实现亚微米分辨率,但数据处理较为繁琐。目前还处于试探阶段的电声反射法的测量基于网络分析仪,具微米级空间分辨率。基于飞秒脉冲激光器光电测量法是对传统压力波法或电声脉冲法的改进,通过太赫兹窄脉冲扰动,利用光电方式实现极高带宽测量,能够实现数十纳米级空间分辨率。

关键词：薄膜电介质空间电荷分布空间分辨率压力波法热扰动法电声反射法光电测量法

Percutaneous penetration enhancement effect of essential oil of mint (Mentha haplocalyx Briq.) on Chinese herbal components with different lipophilicity

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Journal of Traditional Chinese Medical Sciences 2014年第2期1卷 109-119页

作者： Jingyan Wang Yi Lan Hui Li yewen zhang Qing zhang Yanfeng Cao Qing Wu Department of Pharmaceutics School of Chinese Materia MedicaBeijing University of Chinese MedicineBeijing 100102China Department of Pharmacy and Forensic Science King’s College LondonLondon WC2R2LSUK

Objective:To investigate the percutaneous penetration effect of essential oil of mint from Mentha haplocalyx *** the complex active components in Chinese herbal external preparations,and assess its toxicity on the skin ***:The cytotoxicity of mint oil on HaCaT keratinocytes and CCC-ESF-1 fibroblasts was measured using an MTT *** model drugs with a wide range of lipophilicity,namely osthole,tetramethylpyrazine,ferulic acid,puerarin,and geniposide,were tested using in vitro permeation studies to investigate the percutaneous penetration enhancement effect of mint *** structure alterations of skin stratum corneum(SC)were measured using Fourier transform infrared spectroscopy(FTIR).Saturation solubilities and SC/vehicle partition coefficients of the five model drugs with and without mint oil were also determined to understand the potential mechanisms of the essential ***:Half maximal inhibitory concentration(IC50)values of mint oil were significantly higher in HaCaT and CCC-ESF-1 cell lines than values in the well-established and standard penetration enhancer ***:Mint oil at proper concentration could effectively facilitate percutaneous penetration of both lipophilic and hydrophilic drugs,and exhibit higher efficiency for moderate hydrophilic *** of penetration enhancement by mint oil could be explained with saturation solubility,SC/vehicle partition coefficient and the secondary structure change of SC.

关键词： Mint Essential oil Penetration enhancer Transdermal delivery Fourier transform infrared spectroscopy

Effect of co-existent components in CO2 supercritical fluid extract of Angelica Sinensis Radix on metabolism of Z-ligustilide after oral administration in rats

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Journal of Traditional Chinese Medical Sciences 2014年第2期1卷 126-134页

作者： Bochen Zhao Qing zhang Hongmei Lin Qingguo Ru Qian Kang Hui Li yewen zhang Qing Wu Beijing University of Chinese Medicine Beijing 100029China

Objective:To establish a basis for Angelica Sinensis Radix(ASR)as a dietary supplement for colorectal cancer chemoprevention,the effect of co-existent components in supercritical fluid extract(SFE)of ASR on the pharmacokinetics of Z-ligustilide after oral administration was investigated in vitro and in ***:Incubation in gastrointestinal contents and incubation in rat liver tissue homogenates post-mitochondrial supernatant(PMS)experiments were used to study changes in the levels of Z-ligustilide in ***:Within 4 hours,the level of Z-ligustilide in SFE declined at a slower rate than in its pure *** of Z-ligustilide after administration in its pure form was significantly slower than that of SFE of ASR(CL,0.96±0.16 mL·min/kg versus 1.24±0.21 mL·min/kg P<0.05;AUC,243.37±16.84 versus 176.69±12.59 mg·min/L).Conclusion:These phenomena may be attributed to the interactions between the co-existent components in SFE of ASR and Z-ligustilide enhancing the stability of *** results suggest that the bioavailability of Z-ligustilide in SFE of ASR is ***,stabilization of plasma concentration was not sustained,so that the efficacy of active components could not be ***,further processing of SFE of ASR is required.

关键词： Angelica Sinensis Radix Supercritical fluid extract Z-ligustilide Metabolism

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应力对诱发空间电荷击穿的作用

电工技术学报 2006年第2期21卷 31-34页

作者：郑飞虎张冶文肖春同济大学波耳固体物理研究所上海200092

电介质在生产和使用过程中通常会受到各种应力的作用,而应力作用与电介质的老化和击穿密切相关。本文利用电子束辐照的方法将空间电荷引入聚甲基丙烯酸甲酯(PMMA)和低密度聚乙烯(LDPE)样品中,在无外加电场下通过外加应力,可能诱发空间... 详细信息

电介质在生产和使用过程中通常会受到各种应力的作用,而应力作用与电介质的老化和击穿密切相关。本文利用电子束辐照的方法将空间电荷引入聚甲基丙烯酸甲酯(PMMA)和低密度聚乙烯(LDPE)样品中,在无外加电场下通过外加应力,可能诱发空间电荷脱陷导致树枝化击穿。讨论了应力诱发空间电荷击穿的机理,分析了影响应力诱发的空间电荷击穿的诸多因素,如样品中空间电荷分布情况,机械应力的作用形式(如压缩应力或是拉伸应力),样品中的水份,样品的介电常数等因素在空间电荷树枝化击穿过程的作用。

关键词：树枝化击穿应力诱发空间电荷

Formation and migration of space charge packet in low density polyethylene

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Science China(Technological Sciences) 2005年第3期48卷 354-360页

作者： ZHENG Feihu 1 , zhang yewen 1 , GONG Bin 1 , ZHU Jianwei 1 & WU Changshun 2 1. Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, China 2. China National Center for Quality Supervision and Test of Electric Ware and Cable, Shanghai 200093, China Pohl Institute of Solid State Physics Tongji University Shanghai China China National Center for Quality Supervision and Test of Electric Ware and Cable Shanghai China

Pressure wave propagation (PWP) method was utilized to observe the space charges packet-like behavior in sheet samples of low-density polyethylene (LDPE) under the relative low electric field. The experimental results show that space charge packets are always generated at the anode and move across the sample to the cathode regardless of the polarity of DC voltage. This paper discusses the migration of space charge packets at 30–40°C, the possible charge resource of space charge packets carriers and trap level of the space charge.

关键词： solid dielectric,low-density polyethylene,space charge packet,trap.