Preparation of Prussian blue@Pt nanoparticles/carbon nanotubes composite material for efficient determination of H2O2

In this study, the fabrication of an efficient amperometric hydrogen peroxide sensor with favorable properties is presented. Prussian blue (PB) was catalytically synthesized by Pt nanoparticles (Pt-nano) from ferric ferricyanide aqueous solution to form PB@Pt-nano hybrid, and it was confirmed by transmission electron microscope (TEM) and optical spectra. The electrochemical behavior of PB@Pt-nano was highly improved through its integration with poly(diallyldimethylammonium chloride) modified carbon nanotubes (PCNTs).

Electrochemical chlorine sensor with multi-walled carbon nanotubes as electrocatalysts

It has been reported for the first time that an electrochemical gas sensor mdified with multi-walled carbon nanotubes (MWNTs) film as elctrocatalyst was fabricated for the determination of chlorine (Cl-2).Here, MWNTs and graphite were compared with each other in terms of their electrochemical properties using cyclic voltammetry. Cl-2 gas was allowed through the cathode surface of the sensor and the resulting galvanic effects were monitored. Results indicated that both of the MWNTs and graphite have the electrocatalytic activity for the reduction of Cl-2 while the MWNTs-modified electrode exhibited a higher accessible surface area in electrochemical reactions, excellent sensitivity, stable response, reproducibility and recovery for the determination of Cl-2.

A novel flow through optical fiber biosensor for glucose based on luminol electrochemiluminescence

A novel flow injection optical fiber biosensor for glucose based on luminol electrochemiluminescence (ECL) is presented. The sol-gel method is introduced to immobilize glucose oxidase (GOD) on the surface of a glassy carbon electrode. After optimization of the working conditions, glucose could be quantitated in the concentration ranges between 50 muM and 10 mM with a detection limit of around 26 muM. Signal reproducibility was about 3.62% relative standard deviation for 11 replicated measurements of 0.1 mM glucose. The ECL biosensor also showed good selectivity and operational stability. The proposed method can be applied to determination of glucose in soft drink samples.

Characterization of neodymium bisphthalocyanine Langmuir-Blodgett films for gas-sensibility

The deposition of Langmuir-Blodgett film of neodymium bisphthalocyanine derivatives is reported for the first time. Optical absorption data reveal that these films call be deposited in a reproducible manner; results are also presented showing the extreme sensitivity and selectivity of their electrical conductivity to NH3 in room temperature. The Nd bisphthalocyanine LB film is a sensitive, reproducible. rapid and stable gas sensor. Neodymium bisphthalocyanine derivatives will be candidates for thin film gas-sensitive materials. (C) 1998 Elsevier Science S.A. All rights reserved.

Cryoimmobilized enzyme for biosensor construction

A new immobilization material and an immobilization method for a glucose sensor with HEFc (hydroxyethylferrocene) as mediator is described. In the course of three months, the enzyme electrode shows almost no deterioration in its response characteristics. The response time is less than 30 s. The electrode has a wide linear range up to 10 mmol l(-1) with good repeatability. The kinetic parameters have also been calculated.

Thermal Properties Measurement of Micro-Electromechanical System Sensors by Digital Moire Method

The thermal properties of a micro-electromechanical system sensor were analysed by a novel digital moire method. A double-layer micro-cantilever sensor (60 mu m long, 10 mu m width and 2 mu dm thick) was prepared by focused ion beam milling. A grating with frequency of 5000 lines mm- I was etched on the cantilever. The sensor was placed into a scanning electron microscope system with a high temperature device. The observation and recording of the thermal deformation of the grating were realised in real-time as the temperature rose from room temperature to 300 degrees C at intervals of 50 degrees C. Digital moire was generated by interference of the deformed grating and a digital virtual grating. The thermal properties including strain distribution of the sensor and the linear expansion coefficient of polysilicon were accurately measured by the phase-shifted moire patterns.

Reduction Approaches for Vibration Control of Repetitive Structures

The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced.

Characterization of Air-Water Two-Phase Vertical Flow by Using Electrical Resistance Imaging

The characterization of air-water two-phase vertical flow in a 12 m flow loop with 1.5 m of vertical section is studied by using electrical resistance tomography (ERT). By applying a fast data collection to a dual-plane ERT sensor and an iterative image reconstruction algorithm, relevant information is gathered for implementation of flow characteristics, particularly for flow regime recognition. A cross-correlation method is also used to interpret the velocity distribution of the gas phase on the cross section. The paper demonstrates that ERT can now be deployed routinely for velocity measurements and this capability will increase as faster measurement systems evolve.

A Trabecular Bone Explant Model of Osteocyte–Osteoblast Co-Culture for Bone Mechanobiology

The osteocyte network is recognized as the major mechanical sensor in the bone remodeling process, and osteocyte-osteoblast communication acts as an important mediator in the coordination of bone formation and turnover. In this study, we developed a novel 3D trabecular bone explant co-culture model that allows live osteocytes situated in their native extracellular matrix environment to be interconnected with seeded osteoblasts on the bone surface. Using a low-level medium perfusion system, the viability of in situ osteocytes in bone explants was maintained for up to 4 weeks, and functional gap junction intercellular communication (GJIC) was successfully established between osteocytes and seeded primary osteoblasts. Using this novel co-culture model, the effects of dynamic deformational loading, GJIC, and prostaglandin E-2 (PGE(2)) release on functional bone adaptation were further investigated. The results showed that dynamical deformational loading can significantly increase the PGE(2) release by bone cells, bone formation, and the apparent elastic modulus of bone explants. However, the inhibition of gap junctions or the PGE(2) pathway dramatically attenuated the effects of mechanical loading. This 3D trabecular bone explant co-culture model has great potential to fill in the critical gap in knowledge regarding the role of osteocytes as a mechano-sensor and how osteocytes transmit signals to regulate osteoblasts function and skeletal integrity as reflected in its mechanical properties.

高分辨率光纤光栅温度传感器的研究

报道了一种具有高分辨率和高效且价廉的解调系统的光纤布拉格光栅(FBG)温度传感器。提出了光纤光栅的金属槽封装技术，以提高传感光栅的温度灵敏性。研究了金属槽封装光栅的温度灵敏性，理论分析和实验结果表明，封装光栅的温度灵敏系数比普通裸光栅提高了3．6倍。系统利用一长周期光栅(LPG)作为线性滤波器，宽带光源经此长周期光栅调制后入射到传感光栅，可解调布拉格传感光栅的波长位移。理论分析与实验结果一致，系统可达到的温度分辨率为0．02℃。

ICF中可调法布里-珀罗滤波器间距稳定度研究

在神光Ⅱ第9路ICF高功率激光装置中，采用可调法布里-珀罗（F-P）滤波器对幅度调制效应进行补偿，根据补偿装置的技术要求，提出-种应用nm量级精度的电容式位移传感器对可调F-P滤波器间距稳定度进行监控的系统，详细论述了监控系统的结构与工作原理。给出了电容式位移传感器的驱动电路及数据处理与控制软件的设计方案，并对电容式位移传感器的精度进行了标定。实验结果表明，该位移监控系统能够使可调F—P滤波器的间距稳定度保持在15nm／h以内，使幅度调制效应的调制深度优于4％。

基于光时域反射计的全分布式光纤漏油传感器

报道了一种基于光时域反射计的全分布式光纤漏油传感器,该传感器能实现分布式实时监测长输油管道,及时发现小型的漏油事件.传感器沿管道铺设,利用光时域反射计实时测量光纤在长度上的损耗变化特点,及时发现并定位管道上的每一处泄漏事件.模拟实验证明了其实际操作的可行性,长期使用的稳定性和各种抗干扰性,能在15min内发现并定位漏油事件,且定位准确度为3m.

H-2-sensing characteristics of nanocrystalline La0.8Pb0.2FeO3 prepared by sol-gel method

Nanocrystalline La0.8Pb0.2FeO3 has been prepared by the sol-gel method. XRD patterns show that the nanocrystalline La0.8Pb0.2FeO3 is a perovskite phase with the orthorhombic structure and its mean crystallite size is about 19 nm. The influence of Pb ions which replaced the La ions on A-sites can be directly observed from the electrical and sensing properties to H-2 gas. The conductance of La0.8Pb0.2FeO3-based sensor is considerably higher than that of LaFeO3-based sensor, and Pb-doping can enhance the sensitivity to H2 gas. An empirical relationship of R = KCH2alpha with alpha = 0.668 was obtained.

光导纤维pH传感器的光化学pH敏感高分子膜及pH响应性能

pH指示剂在高分子载体上的固定化研究是应光导纤维pH传感器的发展要求而发展起来的新的研究领域。pH指示剂在高分子固态载体上的固定直接决定着光导纤维pH传感器的灵敏度、响应时间、寿命等性能。迄今，吸附、包埋和化学键合三利，固定方法已得到广泛应用。吸附法与包埋法简单易行，但因指示剂易于逸出而无法保证试剂相的使用稳定性及寿命；化学键合法目前仅限于对含氨基等高反应活性基团的指示剂固定。另外，这三种固定技术均存在试剂相与分析对象呈现固／液两相分离的问题，它严重制约了传感器响应性能，成为pH指示剂固定技术发展的“瓶颈”。改善、发展与寻找新的指示剂／载体固定配对体系已成为本领域的研究焦点。本论文针对上述问题，开拓与发展了一系列指示剂固定于固态高分子载体上的新体系。（一）首先开拓与发展了酚红／交联聚乙烯醇与邻甲酚红／交联聚乙烯醇固定对的新体系。在酸性条件下，以甲醛做交联剂，通过在玻璃板上倾涂聚乙烯醇甲醛的凝胶溶液制备了高亲水性的交联聚乙烯醇载体膜；然后采用接枝共聚反应将丙烯酞胺单体与通过酸碱反应接枝有酚红或邻甲酚红的丙烯酞胺混合物接枝固定到交联聚乙烯醇薄膜上，首次将不含氨基的酚红、邻甲酚红在高亲水性的聚乙烯醇载体上固定。利用紫外可见光光谱仪测试了其响应性能。结果表明，固定化指示剂的光谱行为与其相应的水溶液的光谱行为不一致，这可能是固定化过程中新的化学键生成以及载体与指示剂之间的相互作用如氢键的作用等引起的。这也导致了其pH响应范围与相应指示剂水溶液的响应范围的差异。固定酚红交联聚乙烯醇pH敏感膜的pH响应范围为pH=6.72～8.49；固定邻甲酚红交联聚乙烯醇pH敏感膜的两个响应范围分别为［H~+］=0.1mol／L～5mol／L和pH7.97～12.26。这种方式制备的这两种pH敏感薄膜均表现出优异的可重复使用性、可逆性、稳定性及易于制备的特点。更突出的优点在于，与以聚丙烯酰胺为基质直接固定酚红的薄膜（PAM-PR）相比，这种固定技术制备的敏感膜，当其与分析剂溶液接触时，其接枝于表面的水溶性高分子溶解，呈现“液态”，在固态基质表面形成一“液膜”层，从而消除了试剂相与分析剂之间的相界面，克服了指示剂固定化技术中的“瓶颈”问题，大幅度地提高了其响应速度与灵敏度，使响应时间从PAM-PR的数十分钟降至30秒以下。（二）开拓了刚果红醋酸纤维素包埋对的pH敏感膜（CCM）及刚果红／环氧氯丙烷交联聚乙烯醇（PECM）和甲醛交联聚乙烯醇（PFCM）的三种pH敏感膜新体系，测试并比较了三种膜的响应性能。结果表明，固定化刚果红的光谱性质和响应范围与刚果红水溶液不一致，而且用不同载体固定的刚果红的光谱特征与响应范围也各不相同。CCM的响应范围为pH＝2.5～4.5，PECM的响应范围在［H~+］=2mol/L～pH＝6.8之间，PFCM响应范围为pH＝2.90～5.48。这也可能是固定化过程中的氢键效应、空间位阻、指示剂与载体间发生的化学反应不同及载体本身结构的差异等引起的。这三种膜也具有良好的重现性、可逆性及响应迅速（平均响应时间低于25秒）的特点。另外发现醋酸纤维素包埋刚果红的敏感膜具有特殊的稳定性。对这种特殊的稳定性原因的分析表明选择合适尺寸分子的指示剂与载体配对将可能克服包埋技术中指示剂逸出的缺点。（三）对制备的pH敏感膜及对应的水溶液的pH线性响应范围给出了相应的线性回归方程（R＞98.2）。结果表明这些敏感膜对响应范围内的pH均具有良好的线性响应关系。这些结果与思想不仅丰富了光导pH传感器的试剂相内容，也为后续工作提供了一些有益的借鉴。

气相氧电化学传感器及动脉血氧的透皮检测方法

本论文采用气体扩散电极，以气相氧传感器为起点，以动脉血氧的透皮检测为目的，先后探讨了通用的气相氧检测毛细管型氧传感器、气体薄层电极电解及气相流动注射等氧分析方法，最后，为了克服经皮氧测量的困难，找到了用灵敏度高的镀金膜电极，并能有效降低其响应气／皮差别的脉冲偏压暂态分析法。