X射线荧光光谱法测定铁基合金中合金组分的通用工作曲线的制作——基本参数(FP)法虚拟合成标准样品的应用

应用基本参数(FP)法虚拟合成标准样品制作了X射线荧光光谱法测定不同类型的铁基合金中的26种元素的通用工作曲线。选择最佳的仪器工作条件和合理的待测元素的分析线系,测定了9种元素、受共存元素重叠干扰的校正系数,用瑞利散射线扣除背景及通道材料的影响。在设定虚拟合成标准样品中各元素的含量,并算得在此设定值下的理论荧光强度后,用FP法计算各元素在其定值下的最终强度,从而完成了FP法工作曲线。应用此虚拟合成单标工作曲线对多种标准样品进行测定,证明该工作曲线可用于各种类型的铁基合金的分析。     

Identification of potential Tpx inhibitors against pathogen-host interactions

Yersinia organisms cause many infectious diseases by invading human cells and delivering their virulence factors via the type three secretion system (T3SS). One alternative strategy in the fight against these pathogenic organisms is to interfere with their T3SS. Previous studies demonstrated that thiol peroxidase, Tpx is functional in the assembly of T3SS and its inhibition by salicylidene acylhydrazides prevents the secretion of pathogenic effectors. In this study, the aim was to identify potential inhibitors of Tpx using an integrated approach starting with high throughput virtual screening and ending with molecular dynamics simulations of selected ligands. Virtual screening of ZINC database of 500,000 compounds via ligand-based and structure-based pharmacophore models retrieved 10,000 hits. The structure-based pharmacophore model was validated using high-throughput virtual screening (HTVS). After multistep docking (SP and XP), common scaffolds were used to find common substructures and the ligand binding poses were optimized using induced fit docking. The stability of the protein–ligand complex was examined with molecular dynamics simulations and the binding free energy of the complex was calculated. As a final outcome eight compounds with different chemotypes were proposed as potential inhibitors for Tpx. The eight ligands identified by a detailed virtual screening protocol can serve as leads in future drug design efforts against the destructive actions of pathogenic bacteria.     

New peak broadening parameter for the characterization of separation capability in capillary electrophoresis

The influence of separation conditions on peak broadening is usually estimated by the number of theoretical plates. Using the data available in literature and experimental data, it is shown that in pressure‐assisted capillary electrophoresis the plate number is not directly related to the separation capability of conditions used. The experiments at different electrolyte flow velocities demonstrate that a higher plate number (the best separation efficiency) can be obtained with a lower peak resolution. Since ions are separated by electrophoresis due to the difference in electrophoretic mobilities, the peak width in terms of electrophoretic mobility is suggested as a new peak broadening parameter describing the separation capability of the conditions used. The parameter can be calculated using the tailing factor and the temporal peak width at 5% of the peak height. A simple equation for the resolution calculation is derived using the parameter. The advantage of the peak width in terms of mobility over other parameters is shown. The new parameter is recommended to be used not only in pressure‐assisted capillary electrophoresis but also in general capillary electrophoresis when in a number of runs the virtual separative migration distance and separation capability of the conditions used change widely.     

“高分子材料合成创新实验”线上教学探索与实践

Based on the platform of "QQ share screen + video live broadcast", through the combination of "online theory teaching", "development of home alternative experiment", "game type" experimental operation and "virtual simulation experiment", we carried out the online teaching of polymer material synthesis innovation laboratories, integrating "theory + practice" and "virtual + reality", which is also a good opportunity for labor education. These explorations and practices are expected to provide some references for online teaching of chemical laboratory courses during the COVID-19 epidemic.     

Design of fuzzy radial basis function-based polynomial neural networks

In this study, we introduce a new design methodology of fuzzy radial basis function-based polynomial neural networks. In many cases, these models do not come with capabilities to deal with granular information. With this regard, fuzzy sets offer several interesting and useful opportunities. This study presents the development of fuzzy radial basis function-based neural networks augmented with virtual input variables. The performance of the proposed category of models is quantified through a series of experiments, in which we use two machine learning data sets and two publicly available software development effort data.     

同轴波导虚阴极振荡器二极管参数优化的研究

采用粒子模拟研究了同轴波导虚阴极振荡器二极管参数对微波效率和频率的影响,得到了由二极管参数改变引起的二极管阻抗变化及其对微波效率的影响规律. 借鉴具有慢波结构的高功率微波器件中微波模式特性阻抗的计算方法,给出同轴波导虚阴极振荡器中微波主模式特性阻抗的理论计算公式. 将理论计算结果与由粒子模拟对器件进行优化后得到的二极管阻抗进行比较,发现当反映电子束特性的二极管阻抗与微波主模式特性阻抗匹配时,虚阴极振荡器具有较高的束波功率转换效率. 进一步用特性阻抗对其他几种典型结构的虚阴极振荡器进行分析,验证了该方法的合理性,为设计高效率虚阴极振荡器提供了理论指导. 关键词： 虚阴极振荡器 同轴波导 二极管参数 特性阻抗     

虚拟恒电位仪的研制及其在腐蚀电化学测量中的应用

恒电位仪是腐蚀电化学测量最重要的基本设备.虚拟恒电位仪用图形程序软件取代复杂硬件来实现恒电位功能.它的结构和参数灵活,构建简单,能满足多方面腐蚀电化学测试方法的需求,虚拟恒电位仪的实现是发展虚拟腐蚀电化学仪器的重要步骤.本文采用LabVIEW 2010编程系统和比例-积分-微分(PID)控制技术,研制了虚拟恒电位仪,并组建了VEC11-A腐蚀电化学测试系统,该系统能满足不同阻抗体系的腐蚀电化学测试需求.其腐蚀电位、稳态极化曲线、线性极化曲线、循环伏安、动电位扫描、恒电位阶跃等常规腐蚀电化学测量结果与2263电化学测试系统相近,能够满足常规腐蚀电化学测试要求,具有很大的发展空间.     

Identification of orthotropic elastic constants using the Eigenfunction Virtual Fields Method

The Virtual Fields Method (VFM – Pierron and Grediac, 2012), an inverse method based on the principle of virtual work (PVW), is being increasingly used to estimate mechanical properties of materials from full-field deformations obtained from techniques such as Digital Image Correlation, moiré and speckle interferometry and grid methods. By making specific choices for virtual fields (VFs) in PVW, one obtains a system of algebraic equations, which is then solved for the unknown material constants. Recently, a new variant of VFM, known as the Eigenfunction Virtual Fields Method (EVFM) has been proposed (Subramanian, 2013). In EVFM, principal components of the measured (i.e. true) strain fields are used to systematically generate VFs. We extend EVFM to orthotropic elastic materials in this work, and estimate the relevant material parameters from full-field strain data generated from a finite-element model of an unnotched Iosipescu test. Varying levels of Gaussian white noise are added to the synthetic strain data to evaluate the sensitivity of EVFM to input noise. It is observed that for low to moderate noise, the material properties estimated by the proposed method are relatively insensitive to noise. However, when noise levels are high, the proposed method yields large variance in some of the computed properties when compared to the state-of-the-art optimized piecewise continuous VFM (Toussaint et al., 2006; Pierron and Grediac, 2012). Some of the large variance in properties estimated from noisy data using EVFM is traced to the sensitivity of the third dominant eigenfunction and modifications to the proposed method to address this issue are suggested.     

Virtual queuing at airport security lanes

Airports continuously seek opportunities to reduce the security costs without negatively affecting passenger satisfaction. In this paper, we investigate the possibilities of implementing virtual queuing at airport security lanes, by offering some passengers a time window during which they can arrive to enter a priority queue. This process could result in a smoother distribution of arriving passengers, such that the required security personnel (costs) can be decreased. While this concept has received attention in a number of settings, such as theme parks, virtual queuing at airports bears an additional level of complexity related to the flight schedules, i.e., passengers can only be transferred forward in time to a limited extent, which we denote by the transfer time limit. We conducted a major simulation study in collaboration with a large international airport in Western Europe to determine the potential impact of virtual queuing and find that nearly one million Euro can be saved on security personnel cost without negatively impacting the passenger waiting time.