Studies on the sonochemical polymorphism of Sb2O3 on activated graphite for the electrochemical determination of imipramine

This work reports the simultaneous sonochemical activation of graphite and sonohydrolysis of antimony chloride (SbCl₃) in the alkaline medium. The experiments conducted by bath sonicator operated at 37 kHz of frequency and a maximum power of 150 W. The simple sonohydrolysis of SbCl₃ alone produced an orthorhombic phase of Sb₂O₃, whereas, it produced mixed phases of cubic and orthorhombic Sb₂O₃ when introduced with graphite. Herein, the activated graphite (aGR) provides the best support to the growth of cubic phase. This cubic Sb₂O₃ is grown only on the graphite basal planes, which confirmed by scanning electron microscope. Moreover, the phase changes have identified by the X-ray diffraction, Raman and X-ray photoelectron analysis. The prepared aGR-Sb₂O₃ composite has applied to the electroanalytical studies of anti-depressant drug imipramine (IMP). The results showed that aGR-Sb₂O₃ revealed better activity than Sb₂O₃; the reasons are discussed comprehensively. Furthermore, aGR-Sb₂O₃ exhibited comparable analytical results for the determination of IMP.     

基于图像处理的零件二维尺寸检测方法

为了提高零件二维尺寸测量精度和效率,提出一种基于图像处理的非接触式检测方法。对零件图像进行灰度化、采用自适应中值滤波算法来减小图像数据量以及除去噪声;通过最大类间方差法自动确定阈值获得二值图像;采用形态学梯度算子提取图像边缘,并用最小二乘法拟合像素尺寸;通过标准件法对系统进行标定获得零件尺寸。以6204-Z型深沟球轴承作为实验对象,获得轴承内、外径的尺寸。与游标卡尺测量结果比较,所提出的图像处理方法获得的内、外径平均误差达到9.6μm和0.7μm。通过实验对比与分析,方法快速有效,具有较高的准确性和良好的鲁棒性。     

基于开关二级检测的图像椒盐噪声滤波算法

鉴于开关中值滤波在椒盐噪声检测和去除方面的应用合理性,本文分别设计实现了基于信号局部差异性和基于信号方向差异性的椒盐噪声检测算法。这两种算法均属于二级噪声检测方法,且第一级检测手段都是基于灰度范围准则。两种算法的不同点主要体现在第二级检测算法上,前者基于局部差别准则,后者基于方向差别准则。在方法评价部分,首先通过分析和实验确定两种算法的最优参数设置;然后通过对不同噪声密度的测试图像去噪来评价两种算法的去噪效果。结果表明:基于方向差异性的算法比基于局部差异性的算法具有更好的性能,且两种算法的去噪效果都与噪声密度成反比。需要注意的是,这两种算法都容易将图像中的细微边缘或细节像素误判为噪声点,即在噪声的检测过程中,只能避免对图像中主要边缘和轮廓像素的误判,还无法对图像中的细微边缘和细节进行精确判定,这也是开关二级噪声滤波算法今后的主要改进方向。另外,算法效率测试结果表明两种算法具有相似的计算时间,从而验证了两者之间的算法结构相似性。     

Summary of ISO/TC 201 International Standard ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres and its implementation for imaging laboratory X-ray photoelectron spectrometers (XPS)

ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres revises ISO 18516:2006 Surface chemical analysis—Auger electron spectroscopy and X-ray photoelectron spectroscopy—Determination of lateral resolution. It implements three different methods delivering parameters useful to express the lateral resolution: (1) the straight edge method, (2) the narrow line method and (3) the grating method. The theoretical background of these methods is introduced in ISO/TR 19319:2013 Surface chemical analysis—Fundamental approaches to determination of lateral resolution and sharpness in beam-based methods. The revised International Standard ISO 18516 delivers standardized procedures for the determination of the (1) effective lateral resolution by imaging of square-wave gratings, the (2) lateral resolution expressed as the parameter D_12–88 characterizing the steepness of the sigmoidal edge spread function (ESF) determined by imaging a straight edge and (3) the lateral resolution expressed as the full width of half maximum of the line spread function (LSF), w_LSF, determined by imaging a narrow line. The last method also delivers information on the shape of the LSF, which characterizes an individual imaging instrument. Finally, the implementation of all three standardized methods in the field of imaging laboratory X-ray photoelectron spectroscopy (XPS) is shortly presented. This part of the letter is based on the use of a new test sample developed at ETH Zurich, Switzerland. This test sample displays a micrometre scaled pattern motivated by the resolving power of recent imaging XPS instruments.     

载波全息干涉图的自动分析

用正交相干相位检测法实现了载波全息干涉图的自动分析.讨论了分析载波条纹图的边界效应,提出了一种易于在微机上实现的条纹图外插算法.最后给出了一幅实时法载波全息图的分析结果.     

Thianthrene as an activating group for the synthesis of poly(aryl ether thianthrene)s by nucleophilic aromatic substitution

A method for the preparation of poly(aryl ether thianthrene)s has been developed in which the aryl ether linkage is generated in the polymer‐forming reaction. The thianthrene heterocycle is sufficiently electron‐withdrawing to allow fluoro displacement with phenoxides by nucleophilic aromatic substitution. The monomer for this reaction, 2,7‐difluorothianthrene, can be synthesized in a moderate yield by a simple reaction sequence. Semiempirical calculations at the PM3 level suggest that 2,7‐difluorothianthrene is sufficiently activated, whereas NMR spectroscopy (¹H and ¹³C) indicates that the monomer is only slightly activated or (¹⁹F) not sufficiently activated for nucleophilic aromatic substitution. Model reactions with p‐cresol have demonstrated that the fluorine atoms on 2,7‐difluorothianthrene are readily displaced by phenoxides in high yields, and the process has been deemed suitable for polymer‐forming reactions. High‐molecular‐weight polymers have been produced from bisphenol A, bisphenol AF, and 4,4′‐biphenol. The polymers have been characterized with gel permeation chromatography, NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The glass‐transition temperatures for the polymers of different compositions and molecular weights range from 138 to 181 °C, and all the polymers have shown high thermooxidative stability, with 5% weight loss values in an air environment approaching 500 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6353–6363, 2004     

圆柱面上微小后向台阶层流绕流场的数值研究

1前言钩体绕流是燃烧、传热领域基本的流动现象，具有流动分离、流态转被、旋涡脱落、涡致振动等复杂特性。降低钩体绕流阻力一直是人们关心的问题。自从Prandtl圆球绊线实验以来，Stuper，Roshko，Zukausks，Achenbach，Klebanoff等［‘一列从不同角度研究了钝体绕流阻力的构成因素及降低钝体绕流阻力的若干方法。一致的观点是：因绕流钝体必然伴随着流动分离，流动阻力可分为与粘性有关的摩擦阻力及与流动分离有关的压差阻力两部分，其中，压差阻力约占总阻力的90N95％，其大小与流动分离点的位置密切相关。若流动分离时边界层内为层流…     

局域功函数图像及其在Cu(111)-Au/Pd表面的应用

用扫描隧道显微镜（STM）对Cu(111)-Au和Cu(111)-Pd表面的局域功函数进行了研究.通过 测量隧道电流对针尖样品间距的响应，得到了与STM形貌图一一对应的表面局域功函数图像. 实验发现，Au/Pd覆盖层和Cu衬底间的功函数有明显的不同.Pd薄膜的功函数甚至超过了其体 本征值，且功函数在台阶处变小.用偶极子的形成解释了台阶处功函数的降低.这一工作表明 ，用测量局域功函数的方法容易区分表面上不同的元素，并具有纳米尺度的空间分辨率. 关键词： 扫描隧道显微镜 局域功函数 台阶