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Dielectric and Ferroelectric Properties of Complex Perovskite Ceramics Under Compressive Stress

材料科学与工程学报 2007年第6期25卷 833-836,849页

作者： r.Yimnirun n.Triamnak M.Unruan S.Wongsaenmai A.ngamjarurojana Y.Laosiritaworn S.Ananta Department of Physics Faculty of ScienceChiang Mai University

Dielectric and ferroelectric properties of complex perovskite PZT-PZn ceramic system were investigated under the influence of the compressive *** results showed that the dielectric properties,*** constant(ε_r)and dielectric loss(tan δ),and the ferroelectric characteristics,*** area of the ferroelectric hysteresis loops,the saturation polarization(P_ sat),and the remnant polarization(P_r)changed significantly with increasing compressive *** changes depended strongly on the ceramic *** experimental results on the dielectric properties could be explained by both intrinsic and extrinsic domain-related mechanisms involving domain wall motions,as well as the de-aging *** stress-induced domain wall motion suppression and non-180° ferroelectric domain switching processes were responsible for the changes observed in the ferroelectric *** addition,a significant decrease in those parameters after a cycle of stress was observed and attributed to the stress induced decrease in switchable part of spontaneous *** study clearly show that the applied stress had significant influence on the electrical properties of complex perovskite ceramics.

关键词：铁电性能介电性能钙钛矿陶瓷压力

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溶藻弧菌HY9901 vscH基因克隆及生物信息学分析

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广东海洋大学学报 2018年第4期38卷 85-91页

作者：梁彩凤庞欢瑛刘建勇广东海洋大学水产学院广东湛江524088

【目的】克隆溶藻弧菌(Vibrio alginolyticus)HY9901 vscH基因,并分析其序列结构。【方法】参照Gen Bank上的溶藻弧菌全基因组序列设计1对特异性引物,PCr扩增溶藻弧菌HY9901株的Ⅲ型输出蛋白Yop r核心家族蛋白vscH基因全长,用生物信息... 详细信息

【目的】克隆溶藻弧菌(Vibrio alginolyticus)HY9901 vscH基因,并分析其序列结构。【方法】参照Gen Bank上的溶藻弧菌全基因组序列设计1对特异性引物,PCr扩增溶藻弧菌HY9901株的Ⅲ型输出蛋白Yop r核心家族蛋白vscH基因全长,用生物信息学手段分析VscH序列,构建VscH系统进化树及亚基三维结构模型。【结果】vscH基因序列全长636 bp,编码211个氨基酸,推导的蛋白分子质量为24.09 ku。经预测,VscH不存在信号肽与跨膜区;含有2个ASn-糖基化位点,14个磷酸化位点,2个n-豆蔻酰化位点,2个内质网靶向序列及2个微体C-末端靶信号位点;有1个主要功能域,T3SS_needle_reg(第71-211氨基酸);α-螺旋占66.35%,无规则卷曲占23.22%,延伸链占5.69%,β-折叠占4.74%;可能的B细胞抗原优势表位,分别是第20~23,25~28,37~40,48~51和109~112区段。溶藻弧菌VscH系统进化树与弧菌(Vibrio)聚为一簇。VscH亚基三维结构模型与鼠疫耶尔森菌毒力因子Yop r蛋白的编码基因ysc H相似。

关键词：溶藻弧菌 vscH基因基因克隆生物信息学分析

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Multi-exponential model to describe pressure-dependent P-and S-wave velocities and its use to estimate the crack aspect ratio

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Journal of rock Mechanics and Geotechnical Engineering 2022年第2期14卷 385-395页

作者： Mihály Dobróka norbert Péter Szabó Tünde Edit Dobróka Mátyás Krisztián Baracza Department of Geophysics University of MiskolcMiskolc-Egyetemváros3515Hungary MTA-ME Geoengineering research Group University of MiskolcMiskolc-Egyetemváros3515Hungary research Institute of Applied Earth Sciences University of MiskolcMiskolc-Egyetemváros3515Hungary

We present new quantitative model describing the pressure dependence of acoustic P-and S-wave *** that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can contribute to the pressure-dependent change of the wave velocity,we order a characteristic pressure to all of them and allow a series of exponential terms in the description of the(pand S-waves)velocity-pressure *** estimate the parameters of the multi-exponential rock physical model in inversion procedures using laboratory measured P-and S-wave velocity *** is known,the conventional damped least squares method gives acceptable results only when one or two individual mechanisms are *** the number of exponential terms leads to highly nonlinear ill-posed inverse *** to this reason,we develop the spectral inversion method(SIM)in which the velocity amplitudes(the spectral lines in the characteristic pressure spectrum)are only considered as *** characteristic pressures(belonging to the velocity amplitudes)are excluded from the set of inversion unknowns,instead,they are defined in a set of fixed positions equidistantly distributed in the actual interval of the independent variable(pressure).Through this novel linear inversion method,we estimate the parameters of the multi-exponential rock physical model using laboratory measured P-and S-wave velocity *** characteristic pressures are related to the closing pressures of cracks which are described by well-known rock mechanical relationships depending on the aspect ratio of elliptical *** gives the possibility to estimate the aspect ratios in terms of the characteristic pressures.

关键词： Multi-exponential rock physical model Spectral inversion method(SIM) Crack aspect ratio Characteristic pressures

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