Single‐Walled Carbon Nanotubes on Tungsten Wires: A New Class of Microelectrochemical Sensors

This paper reports the fabrication and the outstanding performance characteristics of novel microelectrodes consisting of tungsten (W) wires coated with homogeneous layers of single‐walled C nanotubes (SWNT). A series of studies using cyclic voltammetry indicate that the SWNT‐modified W electrodes possess interesting electrochemical features. In fact, they are able to catalyse electron transfer reactions involving a series of inorganic and biological molecules. These electrodes are characterized by a fast electron transfer, a wide working potential window, and a low background current. Moreover they demonstrate excellent reproducibility, good stability in various chemical media, and very high sensitivity towards a series of inorganic and organic compounds. The SWNT modified microelectrodes have been tested for the capacity to electrochemically detect ferrocene monocarboxylic acid and potassium hexacyanoferrate as well of a series of interesting biological molecules which include catechol, caffeic acid, DOPAC, ascorbic acid, L ‐tyrosine, acetaminophen, guanine, uric acid, and the neurotransmitters dopamine, epinephrine, and serotonin (5‐HT) hydrochloride. The advantages of the SWNT‐modified W electrodes are illustrated by comparing their analytical performance with that of conventional electrodes.     

A Novel Amperometric Nitric Oxide Sensor Based on Polythionine / Nation Modified Glassy Carbon Electrode

A novel amperometric sensor for the determination of nitric oxide was developed by coating polythionine / nafion on a glassy carbon electrode. This sensor exhibited a great enhancement to the oxidation of nitric oxide. The oxidation peak currents were linear to the concentration of nitric oxide over the wide range from 3.6×10-7 to 6.8×10-5 mol.L-1, and the detection limit was 7.2×10-8 mol.L-1. Experimental results showed that this nitric oxide sensor possessed excellent selectivity and longer stability. NO releasing from rat kidney was monitored by this sensor.     

Anodic voltammetric behaviors of methotrexate at a glassy carbon electrode and its determination in spiked human urine

The anodic voltammetric behavior of methotrexate was studied at glassy carbon electrode in acetate buffer (pH = 3.6) solution using cyclic, square-wave voltammetric and chronocoulometric techniques. The oxidation of methotrexate is an irreversible diffusion-controlled process. The oxidation mechanism was proposed and discussed in this work. The dependence of the current on pH, the concentration and nature of buffer, and instrumental parameters were investigated to optimize the experimental conditions for the determination of methotrexate. It was found that in the range of 8.0 × 10⁻⁷–2.0 × 10⁻⁵ mol/L, the currents measured by square-wave voltammetry presented a good linear property as a function of the concentrations of methotrexate. In addition, validation parameters, such as reproducibility, sensitivity and recovery were evaluated as well. The proposed method was also successfully applied for the determination of methotrexate in diluted human urine with good satisfactory.     

衰减信道下的决策融合问题

本文针对国际上近几年兴起的研究热点——无线传感器网络在信道衰减下的决策融合问题进行探讨。分析了已有传感器决策融合问题算法的结构,在已知信道传输错误概率的条件下,将信道无传输错误的分析方法推广到信道衰减的情况,对传输错误和融合律的关系进行了深入分析。对给定融合律的网络决策融合问题,获得了最优容错传感器观测量化器的必要条件并设计了迭代算法。在没有增加问题的计算复杂度的情况下,得到了最优观测量化器。与国际上现有结果不同,新结果不要求传感器决策条件独立,也不要求各传感器与融合中心之间的信道相互独立,具有更加广泛的使用范围。     

Flow-through solid-phase based optical sensor for the multisyringe flow injection trace determination of orthophosphate in waters with chemiluminescence detection

In this work, a novel flow-through solid-phase based chemiluminescence (CL) optical sensor is described for the trace determination of orthophosphate in waters exploiting the multisyringe flow injection analysis (MSFIA) concept with multicommutation. The proposed time-based injection flow system relies upon the in-line derivatisation of the analyte with ammonium molybdate in the presence of vanadate, and the transient immobilisation of the resulting heteropolyacid in a N-vinylpyrrolidone/divinylbenzene copolymer packed spiral shape flow-through cell located in front of the window of a photomultiplier tube. The simultaneous injection of well-defined slugs of luminol in alkaline medium and methanol solution towards the packed reactor is afterwards performed by proper switching of the solenoid valves. Then, the light emission from the luminol oxidation by the oxidant species retained onto the sorbent material is readily detected. At the same time, the generated molybdenum-blue compound is eluted by the minute amount of injected methanol, rendering the system prepared for a new measuring cycle. Therefore, the devised sensor enables the integration of the solid-phase CL reaction with elution and detection of the emitted light without the typical drawbacks of the molybdenum-blue based spectrophotometric procedures regarding the excess of molybdate anion, which causes high background signals due to its self-reduction. The noteworthy features of the developed CL-MSFIA system are the feasibility to accommodate reactions with different pH requirements and the ability to determine trace levels of orthophosphate in high silicate content samples (Si/P ratios up to 500). Under the optimised conditions, a dynamic linear range from 5 to 50 μg P l⁻¹ for a 1.8 ml sample, repeatability better than 3.0% and a quantification limit of 4 μg P l⁻¹ were attained. The flowing stream system handles 11 analysis h⁻¹ and has been successfully applied to the determination of trace levels of orthophosphate in environmental samples such as mineral, ground, tap and pond waters as well as samples from a water-steam cycle of an incineration plant. The t-test comparison of the means for the developed optical sensor and the molybdenum-blue spectrophotometric APHA/AWWA/WPCF reference method revealed that there is no evidence of significant differences between the obtained results at the 95% confidence level.     

内螺纹挤压加工温度及其变化规律的实验研究

采用自制的温度传感器,使用不同规格、不同结构的挤压丝锥,在不同的工件材料、不同预制孔径、不同挤压速度、不同切削液的实验条件下,对内螺纹挤压加工温度及其变化规律进行了实验研究.从降低挤压加工温度出发,提出延长挤压丝锥寿命、提高内螺纹质量的优化措施.     

光纤Fabry-Perot谐振腔的精细度对相位灵敏度的影响

分析了光纤Fabry-Perot谐振腔的工作原理及其工作点的选择问题，推导了谐振腔的光学相位灵敏度与精细度的关系，给出了理论公式及曲线，并与光纤Math-Zehnder干涉进行了对比，指出了在相位灵敏度上两者的巨大差距，证明了光纤Fabry-Perot干涉的独特优点.介绍了光纤Fabry-Perot干涉的实验系统，提出了检测及计算Fabry-Perot谐振腔有效精细度的方法，实验结果与理论仿真基本吻合.     

激光衍射测量中应用插值细分的可行性分析

激光衍射测微的精度关键在于衍射图样暗纹间距的精确测量，暗纹间距的测量目前主要采用高位数、小中心距的固体图象传感器线阵，为此，提出了一种硬件插值细分的方法。介绍了激光衍射的测量原理，分析了图像传感器的功能，根据采样和恢复定理，对输出的视频信号进行间距插值细分的可行性进行了论证，给出了插值细分的电路框图。分析表明其测量精度不受器件中心距大小的限制，为低位数、大中心距的固体图象传感器线阵的应用提供了方便。     

Interaction between α-actinin and negatively charged lipids membrane investigated by surface plasmon resonance and electrochemical methods

α-Actinin has been shown to be capable of interacting with some special membrane phospholipids directly, which is important for its function. In this study, hybrid bilayer membranes composed of negatively charged lipids are constructed on the surface plasmon resonance gold substrate and on the gold electrode, respectively, and the interaction between α-actinin and negatively charged lipids membrane is investigated by surface plasmon resonance, cyclic voltammetry and electrochemical impedance spectroscopy methods. α-Actinin is proved to be able to interact with the negatively charged lipids membrane directly. It can also insert at least partly into the membrane or lead to some defect or lesion in the membrane, which increase the permeability of the membrane. This study would bring some insight on the interaction between the α-actinin and the cell membranes in vivo.     

结构光焊缝检测传感器设计理论的研究

对电弧光的干扰进行了深入的研究，建立了电弧干扰的光照模型，依据透视变换理论，给出了光源倾斜照射和摄像机斜接收情况下，被检测物体与摄像机这间的一般坐标变换数学模型，这两个模型对结构光传感器的设计具有非常重要的指导意义，基于这两个模型设计的结构光传感已在自动焊接实验中获得了成功的应用。