Effect of nanopore size on poly(dT)30 translocation through silicon nitride membrane

The nanopore size effect on translocation of poly(dT)30through Si3N4 membrane is investigated.In this paper,we report that the speed of the poly(dT)30 transport through Si3N4 nanopores can be slowed down by half through increasing the nanopore diameter from 4.8 nm to 10.8 nm.The results are consistent with our simulation results.Besides,the current blockage induced by DNA passing through the nanopore is less obvious as pore diameter is larger,which is in good agreement with the theoretical prediction.The conclusion about DNA transport through nanopores is beneficial for the design of DNA sequencing devices.     

纳米孔模板的透射电镜观察

该文利用透射电镜对阳极氧化法制备的纳米孔模板进行了观察。纳米孔薄膜的正面观察是把纳米孔膜从模板上取下后通孔并碎化,把微小碎片放在铜网上观察;纳米孔薄膜的侧面观察是把纳米孔薄膜在ultrotome-nova超薄切片机进行切片后进行观察。结果表明,通过该两种办法,能够清楚地观察到纳米氧化孔膜的正面、侧面及纳米孔膜底部的金属颗粒,为纳米孔膜及在纳米孔内部制备的其它纳米物体观察提供了透射电镜方法。     

Effect of chain length on the conformation and friction behaviour of DNA

Four double-stranded DNA films with different chain lengths were prepared on 3-aminopropyltriethoxysilane (APS)-modified mica surfaces in the NaCl solution with concentration ranging from 0.001 to 0.1 M. By using an atomic force microscope, the force-distance curves and friction behaviour of each DNA film were studied in the NaCl solution that was used in the sample preparation. When adsorbed on mica as films in salt solution, the conformation of DNA molecules would be a combination of loops and “train-like”. As the chain length increased from 50 to 20000 bp, the extension rate of DNA film increased from 7.1 to 11.5 in 0.001 mol/L NaCl solution, which suggested that the DNA molecule with long chain likely resulted in more extended conformation. In addition, under low normal load, low NaCl concentration could increase the friction of DNA film and the chain length revealed insignificant effect on the friction force of DNA film. Therefore, long chain DNA with low salt concentration is more conducive to the nanopore sequencing process, since extended conformation can make DNA molecules easier to reach into nanopore and the high friction can reduce the translocation speed. These results may benefit the development of the third-generation sequencing technique based on nanopore.     

Investigation on the interaction length and access resistance of a nanopore with an atomic force microscopy

Nanopore devices have attracted a lot of attention for their potential application in DNA sequencing. Here, we study how an occluding object placed near a nanopore affects its access resistance by integrating an atomic force microscopy with a nanopore sensor. It is found that there exists a critical hemisphere around the nanopore, inside which the tip of an atomic force microscopy will affect the ionic current. The radius of this hemisphere, which is a bit smaller than the theoretical capture radius of ions, increases linearly with the applied bias voltage and quadratically with the nanopore diameter, but is independent of the operation modes and scanning speeds of the atomic force microscopy. A theoretical model is also proposed to describe how the tip position and geometrical parameters affect the access resistance.     

功能玻璃特性及其研究进展

对最近几年新型功能玻璃的研究及发展进行了回顾，重点介绍了新型功能玻璃在通信、磁记录材料、非线性光学器件等方向的应用，作者认为，随着科学和技术的发展，这类新型功能材料将会发挥越来越重要的作用。     

Influence of addition of B2O3 on properties of Yb^3＋-doped phosphate laser glass

The three host glasses doped with Yb^3＋ were prepared by means of conventional melt quenching technology, and the influence on physical and spectral properties of phosphate glass due to addition of B2O3 was investigated and compared with silicate glass. The results show that due to the existence of OH^- impurities which induce the non-radiative route, the fluorescence lifetime of phosphate glass is shorter, so silicate glass has better spectral properties than phosphate glass. Silicate glass has more excellent thermal-mechanical properties than phosphate glass, but with the addition of B2O3, thermal-mechanical properties of phosphate glass are improved greatly without fluorescence quenching effect, and this kind of borophosphate glass will be the candidate to be used in high average power solid state laser.     

碱性强弱染色非变性聚丙烯酰胺凝胶对微卫星DNA检测效果的影响

非变性聚丙烯酰胺凝胶电泳常用于分离不同分子质量和空间构象的DNA或RNA等生物大分子，由于分辨率可以达到2个碱基对，因此非变性聚丙烯酰胺凝胶对于微卫星DNA有很好的检测效果。利用非变性聚丙烯酰胺凝胶电泳对黄牛微卫星DNA的检测表明：碱性强弱的控制对于染色的效果和效率有显著的影响。弱碱性环境下，具有背景浅、条带明显和检测灵敏度高的优势，但是染色过程较复杂繁琐，适合于少量样品的精细检测；在强碱性环境下，对于微卫星DNA的灵敏度相对弱碱性环境下降低，但是染色过程简便、快捷且成本相对较低，适合于大规模样品的检测。     

基于改进Zernike矩的玻璃瓶亚像素边缘检测算法

图像的边缘检测精度决定了实际尺寸的测量精度,为了提高测量精度,提出了一种基于改进的Zernike矩的测量玻璃瓶实际尺寸的算法。将传统的Zernnike矩算法与Otsu自适应阈值法相结合,得到改进的快速算法;利用该快速算法对采集的玻璃瓶图像进行亚像素级边缘检测;运用最小二乘法根据亚像素坐标对瓶口与瓶底所形成的椭圆进行拟合;应用标准块规对系统进行标定并得到玻璃瓶实际的测量尺寸。实验结果表明,该方法不仅可使边缘检测达到亚像素级精度,还避免了人工反复选择阈值而造成的低效率与误判,实现了快速、准确、无接触测量实际尺寸的功能。     

浸没式UV-C技术对念珠藻"水华"的抑制效应

以“水华”蓝藻中常见的念珠藻Nostoc7120为受试藻种，分别设计了浸没式UV—C技术抑藻实验、细胞形态观察实验和SDS—PAGE电泳实验等，最后分别从群体、细胞、分子水平对此技术除藻抑藻效应的机理予以阐释。     

一种基于机器视觉的玻璃质量在线检测系统

对玻璃缺陷识别原理进行了介绍,并对基于机器视觉的运动图像实时处理算法进行了研究。由此,提出了玻璃质量在线检测系统的总体设计方案,并提出了一种基于自适应阈值选取的图像二值化分割、缺陷特征提取并通过神经网络分类器识别不同种类缺陷的新算法。在此基础上,研制开发了一个玻璃质量在线检测系统,并将其运行于工业现场。实际使用情况表明该系统是可行且有效的。     

基于数字图像的混凝土道路裂缝检测方法综述

裂缝的实时监测在混凝土结构设施维护中具有重要的作用。基于数字图像的自动检测技术具有快速、精确、智能等特点，已被广泛运用于道路裂缝检测。文章从硬件、软件2方面对公路、隧道和桥梁3种不同类型混凝土道路裂缝检测方法的研究现状进行了全面分析与总结，指出现有检测方法在系统完善性、通用性、精确性等方面普遍存在不足，急需开发更高效、稳定、智能的裂缝自动检测系统，这也将是混凝土裂缝检测的研究热点之一。     

基于机电阻抗与超声导波综合技术的复合材料板损伤定位

为了提高检测能力,将机电阻抗与超声导波技术相结合用于复合材料板中损伤检测和定位.基于机电阻抗技术的结构健康监测具有局部灵敏度高、无需模型分析等优点,在新型材料结构的在线监测领域具有独特的优势,例如飞机、航天器上大面积使用的复合材料结构等.超声导波技术具有检测效率高、检测范围广、检测速度快等优点,特别适合板状结构的健康监测.该机电阻抗与超声导波综合技术将机电阻抗技术的局部灵敏度高与超声导波检测技术的范围广的优点相结合.结果表明:局部均值成像算法和数据融合算法可用于复合材料板结构健康监测的数据处理和融合,实现了整个复合材料板中缺陷的定位及成像.     

计算机拟合技术优化氯氰菊酯GC检测条件的研究

借助均匀设计法合理安排试验及应用计算机拟合技术科学地进行了氯氰菊酯的毛细管气相色谱检测条件的设计与优化的研究,建立了相关的数学模型.成功地求出了柱温258.8℃、压力17.3Pa时能够满足出峰时间快、峰型好的气相色谱检测条件,优化色谱条件的方法具有广泛的应用价值.     

玻璃缺陷在线检测系统的研究

针对当前国内玻璃生产企业在生产中对玻璃的结石、裂纹等重要缺陷检测方法的不足,提出了一套玻璃质量在线检测系统的总体技术方案。利用面向对象VC＋＋编程工具,结合图像处理技术,实现了对玻璃缺陷的实时检测、识别和分类,缺陷检测准确率达90％以上。     

现代生物技术在环境科学研究中的应用

随分子生物学和遗传工程技术的迅速发展,现代生物技术在环境科学研究中的应用越来越广泛．笔者较系统地概述了与环境科学密切相关的现代生物学技术,如核酸探针检测技术、PCR技术、基因重组技术、基因芯片技术、生物酶技术、生物传感器,及其在环境监测、环境污染防治中的应用．     

Preparation and properties of fiber optic oxygen sensing material by thermo-polymerization method

A new kind of fiber optic oxygen sensing material based on the fluorescence quenching of Ru（bpy）3Cl2 was prepared by the themo-polymerization method. The ruthenium dye was immobilized in N, N-methylene bisacrylamide（MBBA） polymer by physically trapping while MBBA was covalently crosslinked on the glass micro-beads by NaHSO3-O2-MnSO4 initiator system. The lock-in amplifyication technology was used for the detection of their sensing properties. The influences of indicator concentration, glass micro-beads diameter, post polymerization time, concentration and reaction time of glutaraldehyde on the properties of sensing materials were studied. To optimize the influencing factors to the sensing materials, the indicator concentration of 0.7 g/L, glass micro-beads diameter of 0.3 mm, post polymerization time of 5 h were achieved. The immobilization stability of ruthenium dye and the performance of the sensing materials were improved by the new polymerization system. An absolute detection limit of 3×10-6 （V/V） and the response time of 10 s were obtained. This kind of sensing materials has good stability and their life time is 2 years.     

一种测量光学玻璃应力的光谱方法

光学玻璃的应力使其出现双折射性质,严重影响成像质量和导致波面形变,因此需要进行精确定量的测量。为了满足高精度玻璃应力测量的需求,文章提出了一种测量应力的新方法:在光谱扫描法测量系统的基础上,加入半波片作为延迟量基准,根据插入被测玻璃前后延迟量的变化,精确、定量地得到被测玻璃的应力。实验测量了1块立方体玻璃不同区域的应力。分析表明,光谱扫描精度为0.25nm时,系统测量误差小于0.4nm。     

计算机视觉布料瑕疵检测方法综述

长久以来,布料的瑕疵检测工作一直由质检员完成,瑕疵判别过程受主观因素影响大,存在检测效率低、成本高等问题。随着计算机视觉技术的发展,基于视觉技术的布料瑕疵检测系统逐渐成为取代人工质检的重要解决方案。针对基于视觉技术的布料瑕疵检测,从行业发展情况、通用检测标准、系统整体结构、检测算法的关键技术等方面进行了综述,介绍了目前市面上已经存在的基于视觉技术的布料瑕疵检测产品,分析了目前常用的瑕疵检测标准与检测系统的基本结构,梳理并对比了近年来图像处理与深度学习技术在布料瑕疵检测领域的研究现状。最后,总结了各方面尚待解决的关键问题,并探讨了未来可能的发展方向。     

Integrated solid-state nanopore devices for third generation DNA sequencing

Third generation DNA sequencing relies on monitoring the ionic current blockage during the DNA molecule’s threading through a nanoscale pore.It is still really tough to attain the single base discrimination on a DNA strand by merely analyzing the ionic current due to speedy DNA translocation and low spatial resolution.More integrated configurations are pursued to present versatile comparative dissimilarities of the four bases by enhancing the spatial resolution within a DNA molecule translocation event,such as transverse tunneling current,local potential change,and capacitance oriented voltage resonance.In this mini review,the insight is provided into the status quo on several functionalized techniques and methodologies for DNA sequencing and furthermore concluding remark and outlook are presented.     

基于酶联适体竞争法检测谷物制品中真菌毒素的研究

核酸适体作为一种新型分子识别元件,具有可体外合成、易修饰、稳定性好等优势,被认为是抗体的良好替代物.自玉米赤霉烯酮(ZEA)核酸适体被成功筛选以来,基于核酸适体与靶标的高特异性结合,构建了酶联适体间接竞争法检测玉米赤霉烯酮的新方法.ZEA与ZEA适体互补链DNA1竞争性结合酶标板上固定的ZEA适体,未结合的DNA1链被...