Experimental and Numerical Investigation on Strain Rate-Dependent Tensile Behavior of ZrB2–SiC Ceramic Composite

In this study,the strain rate-dependent dynamic tensile behavior of ZrB2-20%SiC ceramic composite was investigated using experimental and numerical approaches.The split Hopkinson pressure bar apparatus was used to measure the dynamic splitting tensile response at strain rates of 17-67 s^?1.The experiment results demonstrate a significant strain rate dependence of the dynamic tensile behavior of the ZrB2-SiC ceramic composite.The dynamic tensile strength increased linearly with the strain rate,from 288 MPa at 17 s^?1to 654 MPa at 67 s^?1.Moreover,a strain rate-dependent tensile strength was introduced into a modified JH-2 model to describe the dynamic tensile behavior and fracture process of ZrB2-SiC ceramics.The numerical results of dynamic tensile strength agree well with the experimental result.Moreover,the fracture process of ZrB2-SiC ceramics under dynamic tension was further studied by combining high-speed images and numerical results.The effect of strain rate on the fracture process and failure patterns of the ZrB2-SiC ceramic composite could be verified by the modified JH-2 model.     

La1/8Ca7/8MnO3/Sr0.95Nb0.05TiO3异质结的整流特性和磁输运性质

在5%Nb掺杂的SrTiO3衬底上用磁控溅射法外延生长了La1/aCa7/aMnO3薄膜形成异质结,该异质结有类似于传统P-n结的整流特性.磁场下扩散电压减小,当温度低于130 K以下,扩散电压的减小非常明显.这和在此温度以下,La1/8Ca7/aMnO3出现自旋倾斜态密切相关.我们计算出异质结的结电阻和磁致电阻(MR),在不同大小的正负偏压,不同磁场下,都得到负的MR值.我们给出界面附近的La1/8Ca7/8MnO3的能带结构并分析了外加磁场对洪德耦合,Jahn-Teller畸变等机制的作用,来解释该异质结的磁输运行为.结果有助于了解高Ca掺杂锰氧化物异质结的性质.     

基于LabVIEW的超导磁体数采与测控系统研究

根据研制的大口径、高场强的超导强磁装置的特点,选择基于LabVIEW的数据采集和测控系统。低温传感器共六支,分别安装于磁体氦槽和冷屏不同位置,其中碳电阻温度计Cernox三支,铂电阻温度计Pt100两支、Pt1000一只,用于监测磁体温度;超导氦液面计一个,用于监测氦液面高度;根据磁体参数匹配研制了一套可调励磁速率的磁体专用直流电源及其失超保护系统,保证磁体安全运行。所有数据通过NI公司内插DAQ6251数据采集卡的PX I采集,用LabVIEW编写数据采集程序和人机界面。     

Ameliorating the interfacial issues of all-solid-state lithium metal batteries by constructing polymer/inorganic composite electrolyte

Lithium metal is one of the most promising anodes for next-generation batteries due to its high capacity and low reduction potential.However,the notorious Li de...     

基于硅基硼掺金刚石电极的电化学-原位核磁共振波谱电解池的设计、制备与可行性研究

电化学与核磁共振波谱联用技术(EC-NMR)可以实时监测电化学反应过程,从分子水平阐释反应机理,是一种非常有前景的无损在线检测技术.本文首次报道以硅基硼掺金刚石(Si/BDD)作为工作电极的原位EC-NMR三电极单室电解池的设计和制作.研究表明,由于尺寸12.5 mm×1.2 mm×0.5 mm的Si/BDD电极在核磁...     

Potential Value of Wood Tar as a Natural Fungicide against Valsa mali

The Valsa canker caused by Valsa mali seriously harmed the production of East Asian apples and caused very significant economic losses. Considering the chemical residues and the improvement of people’s awareness of environmental protection, there is a need for screening new green pesticides for the control of Valsa canker. Therefore, we conducted systematic evaluations on the antifungal activity of wood tar. In this research, the effective concentration (EC₅₀) of six strains of V. mali to wood tar was determined, and the EC₅₀ ranged from 69.54 to 92.81 μg/mL. After treatment with wood tar, the hyphae of V. mali broke, swelled, and deformed; the permeability of the cell membrane increased; and the activity of pectinase reduced. Moreover, the expression levels of five genes related to pectinase also decreased significantly. In addition, the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD) of apple leaves treated with wood tar also increased. On detached apple branches, wood tar also showed therapeutic and protective activities. In the 2016–2019 field experiments, wood tar also showed good efficacy against Valsa canker and promoted the formation of callus. (In the experiments from 2016 to 2019, it can be seen that the control effect of 50% wood tar and 100% wood tar in the field is above 75% and promoted the formation of callus.) This study is the first to report the bidirectional efficacy of wood tar against Valsa mali and for trunk wound healing. The above results evidenced that wood tar has great potential to be developed as a natural alternative to commercial fungicides for the management of apple Valsa canker.     

Indole-Based Tubulin Inhibitors: Binding Modes and SARs Investigations

Tubulin inhibitors can interfere with normal cell mitosis and inhibit cell proliferation through interfering with the normal structure and function of microtubules, forming spindle filaments. Indole, as a privileged pharmacological skeleton, has been widely used in anti-cancer inhibitors. A variety of alkaloids containing an indole core obtained from natural sources have been proven to inhibit tubulin polymerization, and an ever-increasing number of synthetic indole-based tubulin inhibitors have been reported. Among these, several kinds of indole-based derivatives, such as TMP analogues, aroylindoles, arylthioindoles, fused indole, carbazoles, azacarbolines, alkaloid nortopsentin analogues and bis-indole derivatives, have shown good inhibition activities towards tubulin polymerization. The binding modes and SARs investigations of synthetic indole derivatives, along with a brief mechanism on their anti-tubulin activity, are presented in this review.     

固相萃取-离子色谱-积分脉冲安培法测定人血清中游离氨基酸

比较了磺基水杨酸和无水甲醇沉淀人血清中蛋白质的效果,优化了国产732型阳离子交换树脂进行固相萃取净化的条件和Dionex-600离子色谱分析系统的梯度淋洗条件。用该离子色谱仪检测了谷氨酰胺等14种氨基酸,结果表明,峰面积-浓度的校正曲线的相关系数为0.9900~0.9995,检出限为0.02~0.59mg/L;峰面积的相对标准偏差为1.9%~10.4%;回收率为80.6%~114.8%。     

血清一阶导数荧光光谱诊断早期恶性肿瘤

利用Wistar大鼠接种恶性肉瘤模拟人患上癌症。取Wistar大鼠眼静脉血制备血清,并用乙醇简单处理得上层清液,扫描获得其一阶导数荧光光谱,确定上层清液原卟啉发射带(630 nm附近)的峰高,观察到健康Wistar大鼠与癌变大鼠的血清样存在明显差异,10例癌变样假阳性率为0,而20例正常样中仅有1例假阳性达到了恶性肿瘤早期诊断的目的。     

氯化钾水溶液微观结构的分子动力学模拟研究

氯化钾水溶液不同于氯化钠的,其在低温下只能形成无水盐和冰.现有研究表明在氯化钠水溶液中不仅存在着水分子连续分布的区域与离子团簇,而且这二者的物质组成也与该溶液所形成晶体的分别对应.为了探寻其他溶液中是否存在此类对应关系,并考察溶液的微观结构,本文采用分子动力学方法对氯化钾水溶液进行了研究,表明了该溶液的一些性质.氯化钾水溶液中K⁺-K⁺和Cl^--Cl^-径向分布函数的特征具有一致性,峰的最大值所对应的位置都分别相同,明显不同于氯化钠水溶液的.系列时刻下瞬态图像内O到其最近离子距离中最大值的统计结果表明氯化钾水溶液中存在着一定大小的水分子连续分布的区域,其平均尺寸至少为2.26 nm;瞬态图像中K⁺与其最近邻Cl^-之间的距离主要分布在0.28 nm～0.38 nm之间,占比约为97.4%;溶液中存在着较大和较小两类离子团簇,较大团簇的平均尺寸为1.73nm,平均离子数是25.0,其内部的离子与周围离子之间具有与氯化钾晶体类似的结构;这些结果表明氯化钾水溶液中也...