基于未修饰纳米金及无标记单链DNA的Pb~(2+)比色测定

根据纳米金对ss DNA和G-四联体结构的DNA的不同吸附能力,设计了一种简单的Pb2+比色传感器。富含G的无标记ss DNA可以通过静电作用吸附于Au NPs表面,保护Au NPs在高盐浓度溶液中仍呈分散态;当Pb2+存在时,DNA与Pb2+结合形成Pb2+-G-四联体结构,使得Au NPs失去DNA的保护而发生聚集,溶液颜色由红色变成蓝色,最大吸收峰发生红移。通过优化条件,得到溶液吸光度比值(A630/A520)与Pb2+浓度在0.1~10μmol/L范围内呈良好的线性关系,检出限可达50 nmol/L。其他金属离子对Pb2+的检测几乎无干扰。该方法灵敏度高,选择性好,且无需复杂的Au NPs表面修饰过程及DNA标记,制备和操作简便、成本低、响应快(1 min),非常适合于现场实时应用。     

InP Based PD/EAM Integrated Photonic Switch

A new compact three-port InP based PD/EAM （photo-detector/electro-absorption modulator） integrated photonic switch is reported. The device demonstrates bi-directional wavelength conversion over 20nm at 2.5 Gbit/s with a low input optical power of about 20mW.     

Monolithic Integration of Sampled Grating DBR with Electroabsorption Modulator by Combining Selective-Area-Growth MOCVD and Quantum-Well Intermixing

We present the monolithic integration of a sampled-grating distributed Bragg reflector （SG-DBR） laser with a quantum-well electroabsorption modulator （QW-EAM） by combining ultra-low-pressure （55 mbar） selectivearea-growth （SAG） metal-organic chemical vapour deposition （MOCVD） and quantum-well intermixing （QWI） for the first time. The QW-EAM and the gain section can be grown simultaneously by using SAG MOCVD technology. Meanwhile, the Q WI technology offers an abrupt band-gap change between two functional sections, which reduces internal absorption loss. The experimental results show that the threshold current Ith = 62 mA, and output power reaches 3.6roW. The wavelength tuning range covers 3Ohm, and all the corresponding side mode suppression ratios are over 30dB. The extinction ratios at available wavelength channels can reach more than 14dB with bias of-5 V.     

A double wavelength DFB laser with an identical active area for CWDM

A novel distribute feedback (DFB) laser which gave two different wavelengths under two distinct work conditions was fabricated. The laser consists of two Bragg gratings with different periods corresponding to wavelength spacing of 20 nm in an identical active area. When driving current was injected into one of the different sections separately, two different wavelengths at 1542.4 and 1562.5 nm were realized. The side mode suppression ratio (SMSR) of 45 dB or more both for the two Bragg wavelengths were achieved. The fabricating process of the laser was just the samp as that of traditional DFB laser diode. This device can be potentially used in coarse wavelength division multiplexer (CWDM) as a promising light source and the technology idea can be used to enlarge the transmission capacity in metro area network (MAN).     

Offset quantum-well method for tunable distributed Bragg reflector lasers and electro-absorption modulated distributed feedback lasers

Tunable distributed Bragg reflector (DBR) lasers are essential components for future optical fiber communi- cation systems[1]. A tunable laser can replace a large number of distributed feedback (DFB) lasers as sparing source in wavelength division multiplexing (WDM) sys- tems. Moreover they allow flexible switching and routing for distributed data in future network[2]. There are several methods for integrating gain sec- tion with DBR section, such as butt-joint method, bundle method, and …     

High-Power Electroabsorption Modulator Using Intrastep Quantum Well

An electroabsorption modulator using the intrastep quantum well （IQW） active region is fabricated for optical network systems. The strain-compensated InGaAsP/InGaAsP IQW shows good material quality and improved modulation properties, high extinction ratio efficiency IOdB/V and low capacitance （〈 0.42 pF）, with which an ultra high frequency （〉 15 GHz） can be obtained. High-speed measurement under high-power excitation shows no power saturation up to excitation power of 21 dBm. To our knowledge, the input optical power is the highest reported for multi-quantum well EAMs without heat sinks.     

Ta2O5绝缘层厚度对ZnO基薄膜晶体管器件性能的影响

报道了不同厚度TaO5栅绝缘层对氧化锌薄膜晶体管器件性能的影响.在室温下用射频磁控溅射分别制备了100,85,60,40 nm厚度的Ta2O5薄膜作为绝缘层的一组底栅氧化锌薄膜晶体管器件.从实验结果可以得出如下结论:随着Ta2O5栅绝缘层厚度的增加,相应器件的场效应迁移率下降,其数值分别是50.5,59.3,63.8,...     

基于MEMS惯性传感器的人体多运动模式识别

针对人体多运动模式识别中识别精度低的问题,提出一种基于MEMS惯性传感器的人体多运动模式识别算法。该算法选取MEMS加速度传感器的时域特征作为模式识别特征量,提取MEMS角速度传感器的时域特征作为二次识别的特征量,能够准确识别走、跑、站立、上楼、下楼、趴倒、躺倒、倒退多种运动模式。识别过程采用分层识别算法,同时使用支持向量机识别区分难度较大的两类行为动作。嵌入式消防单兵定位系统平台的实验验证表明,利用该算法能够识别消防单兵的多运动模式,平均识别精度达到94%以上。     

离子色谱法快速分析饮用水中的四种阴离子

用Dionex DX-120离子色谱仪对饮用水中F^-1、Cl^-1、NO3^-1及SO4^2- 4种阴离子进行测定,分析中采用了Dionex AS14阴离子分离柱对上述4种阴离子进行分离。作者等对Dionex公司所建议的色谱条件作了修改和改进,使方法的分析效能大大提高,达到了快速分析的要求。按改进后的色谱条件,4种离子的分离度达到了3．9的数值,4种阴离子测定结果的相对标准偏差值均小于2．5％,回收率在94％-108%之间。对有标准值的水样用此文的方法和国家标准方法同时进行比较分析,并用卜检验法对两方法的结果的可靠性,以及与标准值的比较,结果表明各离子（Cl^-1、NO3^-1及SO4^2-）的测定结果之间均无显著性差异。     

ZnO纳米线薄膜的合成参数、表面形貌和接触角关系研究

水浴法合成ZnO纳米线薄膜的工艺参数直接影响其表面形貌, 并使其接触角及润湿性能发生变化. 本文仿真分析了轮廓算数平均偏差、偏斜度、峭度、相关长度等特征参数对随机粗糙表面特性的影响规律; 改变生长时间、种子层溶液和生长液的浓度, 批量制备了表面形貌不同的ZnO纳米线薄膜; 提出了取样长度的确定方法, 并基于扫描电镜图像和Matlab图像处理算子对ZnO纳米线薄膜表面形貌的特征参数进行了提取; 将表面形貌高度和水平方向的特征参数引入Wenzel模型, 分析了合成参数、表面形貌特征参数与接触角的影响关系. 结果表明, 合成参数变化时, 选择取样长度5.0 μm为宜; 生长液浓度大于0.125 mol/L时, ZnO纳米线之间发生重结晶, 并呈现疏水性; 改变种子层溶液浓度和生长时间, 均得到超亲水表面. 上述结论可用于不同氧化酶、细胞等在ZnO纳米线薄膜上的有效吸附及相应传感器测试性能的进一步提高. 关键词： ZnO纳米线 水浴合成 表面形貌 接触角