A novel molecularly imprinted method with computational simulation for the affinity isolation and knockout of baicalein from Scutellaria baicalensis

A novel molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization with baicalein (BAI) as the template and used as solid‐phase extraction (SPE) adsorbent, aiming at the affinity isolation and selective knockout of BAI from Scutellaria baicalensis Georgi (SB). We used computational simulation to predict the optimal functional monomer, polymerization solvent and molar ratio of template to functional monomer. Characterization and performance tests revealed that MIP exhibited uniform spherical morphology, rapid binding kinetics, and higher adsorption capacity for BAI compared with nonimprinted polymer (NIP). The application of MIP in SPE coupled with high‐performance liquid chromatography to extract BAI from SB showed excellent recovery (94.3%) and purity (97.0%). Not only the single BAI compound, but also the BAI‐removed SB extract was obtained by one‐step process. This new method is useful for isolation and knockout of key bioactive compounds from herbal medicines. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of a “Zn Bridge” on the Consecutively Tunable Retention Characteristics of Volatile Random Access Memory Materials

Polyimide memory materials with a donor–acceptor structure based on a charge-transfer mechanism exhibit great potential for next-generation information storage technology due to their outstanding high-temperature resistance and good dimensional and chemical stability. Precisely controlling memory performance by limited chemical decoration is one of core challenges in this field. Most reported work mainly focuses on designing novel and elaborate electron donors or acceptors for the expected memory behavior of polyimides; this takes a lot of time and is not always efficacious. Herein, we report a series of porphyrinated copolyimides coPI−Znx (x=5, 10, 20, 50, 80), where x represents the mole percentage of Zn ion in the central core of the porphyrin. Experimental and theoretical analysis indicate that the Zn ion could play a vital bridge role in promoting the formation and stabilization of a charge-transfer complex by enhancing the hybridization of local and charge transfer (HLCT) excitations of porphyrinated polyimides, endowing coPI−Znx with volatile random access memory performance and continuously tunable retention time. This work could provide one simple strategy to precisely regulate memory performance merely by altering the metal content in porphyrinated polyimides.     

三线摆振动周期与角振幅的关系

本根据机械能守恒定律推出了三线摆的振动周期和角振幅的关系，并据该关系式讨论了角振幅对周期的影响以及角振幅的确定。     

表面喷砂对有机玻璃沿面闪络性能影响

绝缘子表面粗糙处理是提升其沿面闪络性能的重要途径,表面粗糙化处理方式不当,极易带来表面结构不均匀,难以获得稳定耐压性能的绝缘材料。为提升绝缘子表面粗糙处理的均匀性,本文利用表面喷砂技术对圆柱形有机玻璃(PMMA)绝缘子进行了粗糙化处理研究,以球形二氧化硅(SiO2)颗粒为工作介质,研究了不同喷砂粒径、氢氟酸后处理等因素对绝缘材料表面形貌和组分的影响,并利用短脉冲高压测试平台对喷砂处理前后有机玻璃绝缘子样品进行了真空沿面闪络性能测试。研究结果表明,喷砂处理在有机玻璃表面形成了较为均匀的凹坑,HF酸能够有效去除表面残留的SiO2颗粒,具有表面喷砂粗糙结构的绝缘子沿面闪络电压得到了稳定提升,相较于未处理的绝缘子闪络电压提升了约80%。     

基于路径选择的深海水下运动目标被动深度估计

深海水下运动目标的深度估计是目标分辨与识别中的重要一环。基于深海运动目标在深海中的直达波与海面反射波的到达时延与位置之间的关系，寻找时延图上运动目标的候选路径，利用候选路径模拟目标的运动路径，提出了一种可用单水听器实现的水下运动目标深度估计方法。通过用候选路径的估计时延与实际接收时延的比较对路径进行筛选，从而减少了需要的位置先验信息。2018年在南海进行的深海实验数据处理的结果表明该估计方法可行，对于实验中距离15km以内的拖曳声源，深度相对估计误差可以达到15%以内。     

基于表面增强拉曼光谱的苹果毒死蜱残留无损检测方法

对表面增强拉曼光谱(Surface Enhanced Raman Spectroscopy, SERS)技术在苹果毒死蜱残留量无损快速准确检测中的应用进行了研究. 以银溶胶作为表面增强剂, 采用实验室搭建的拉曼光谱系统, 无损地采集苹果样品拉曼光谱. 分别采用二阶导数法(Secondary Derivative Transformation, SD)和极小极大值自适应缩放法(Min-max Signal Adaptive Zooming, MSAZ)扣除所得拉曼光谱的荧光背景以消除样品和环境的干扰, 从而提高检测的准确度. 对获取光谱后的苹果样品采用标准理化方法检测其毒死蜱含量, 在最优条件下, 建立拉曼光谱与15.52～0.064 mg/kg范围内毒死蜱含量的线性关系, 结果表明毒死蜱的两个主要特征峰强度和其浓度呈良好的线性关系, 预测集的相关系数为0.969, 预测均方根误差为1.24 mg/kg. 本研究所开发的方法为果蔬安全品质的无损快速检测提供了一种新思路.     

A consensus least squares support vector regression (LS-SVR) for analysis of near-infrared spectra of plant samples

Consensus modeling of combining the results of multiple independent models to produce a single prediction avoids the instability of single model. Based on the principle of consensus modeling, a consensus least squares support vector regression (LS-SVR) method for calibrating the near-infrared (NIR) spectra was proposed. In the proposed approach, NIR spectra of plant samples were firstly preprocessed using discrete wavelet transform (DWT) for filtering the spectral background and noise, then, consensus LS-SVR technique was used for building the calibration model. With an optimization of the parameters involved in the modeling, a satisfied model was achieved for predicting the content of reducing sugar in plant samples. The predicted results show that consensus LS-SVR model is more robust and reliable than the conventional partial least squares (PLS) and LS-SVR methods.     

单摆作谐振动的最大摆角的分析

本文根据实验上的微小偏差准则和试验中的最小可分辨时间来确定单摆作谐振动时的最大摆角     

Measurement and calculation of surface tension of molten Sn-Bi alloy

The surface tension of molten Sn-Bi (mole fraction X(Bi) = 0.455) alloy has been determined by the sessile drop method at oxygen partial pressure (P(O2)) of 1.0x10(-6) MPa and different temperatures. The experimental results have been analyzed and discussed, and the positive temperature coefficient of surface tension of molten Sn-Bi alloy has been elucidated. The surface tension of this molten alloy has also been obtained by calculation using STCBE based on Butler's equation and thermodynamic data. The experimental results agree well with the calculation values.