Electroanalytical Detection of Cr(VI) and Cr(III) Ions Using a Novel Microbial Sensor

A microbial sensor, namely carbon paste electrode (CPE) modified with Citrobacter freundii (Cf–CPE) has been developed for the detection of hexavalent (Cr(VI)) and trivalent (Cr(III)) chromium present in aqueous samples using voltammetry, an electroanalytical technique. The biosensor developed, demonstrated about a twofold higher performance as compared to the bare CPE for the chosen ions. Using cyclic voltammetry and by employing the fabricated Cf–CPE, the lowest limit of detection (LLOD) of 1x10⁻⁴ M and 5x10⁻⁴ M for Cr(VI) and Cr(III) ions respectively could be achieved. By adopting the Differential Pulse Cathodic Stripping Voltammetric technique, the LLOD could be further improved to 1x10⁻⁹ M and 1x10⁻⁷ M for Cr(VI) and Cr(III) ions respectively using the biomodified electrodes. The reactions occurring at the electrode surface‐chromium solution interface and the mechanisms of biosorption of chromium species onto the biosensor are discussed. The stability and utility of the developed biosensor for the analysis of Cr(VI) and Cr(III) ions in chromite mine water samples has been evaluated.     

基于拉曼光谱散射的新型分布式光纤温度传感器及应用

介绍了分布式光纤拉曼温度传感器(DTS)的基本原理、发展趋势和工程应用研究状况,研究了分布式光纤拉曼温度传感器的关键技术,全面提升了DTS的性能。将拉曼放大技术应用于DTS系统,用拉曼增益部分抵偿光纤的传输损耗,使系统的传感长度达到50 km;对脉冲激光器进行211位循环编码,在接收时采用相关运算解调,显著提高系统的信噪比,使测温不确定度达到1 ℃;采用双波长自校正技术提高了系统的空间分辨率,达到2 m;在DTS系统中嵌入光开关,使测温通道成倍扩展,有效延伸了传感光纤的总长度,组成光纤传感网络。     

Synthesis, characterization and radiolytic properties of bis(oxalato)borate containing ionic liquids

Previously unreported bis(oxalato)borate (BOB) ionic liquids (ILs) containing imidazolium, pyridinium, and pyrrolidinium cations were prepared from the corresponding halide salts by reaction with sodium bis(oxalato)borate (NaBOB), and their properties are reported. Pulse radiolysis experiments revealed that the BOB anion scavenges solvated electrons with rate constants of 3×10⁸ M⁻¹ s⁻¹ in the ionic liquid C₄mpyrr NTf₂ and 2.8×10⁷ M⁻¹ s⁻¹ in water. This reactivity indicates that BOB ILs may be too sensitive to be used as neat solvents for nuclear separations processes in high radiation fields but may still be useful for preventing criticality while processing relatively “cold” fissile actinides.     

Evaluation of Multiple Corona Reactor Modes and the Application in Odor Removal

Effects of multiple corona reactor modes on pulse characteristics, energy transfer efficiency, and odor (H₂S and NH₃) removal were investigated experimentally by the wire-plate corona reactor(s). The removal efficiency of H₂S was only 91% and the energy consumption was 16.1 Wh m⁻³ by the single mode with a gas-flow rate of 23 m³ h⁻¹ and an initial concentration of 200 mg m⁻³. At the same experimental conditions, almost 100% removal efficiency was achieved and the energy consumption was only 12.8 and 14.9 Wh m⁻³ by the series and parallel modes. In the case of 50 mg m⁻³ NH₃ removal at the same gas-flow rate, the removal efficiencies with the single mode, the series and parallel modes were 64, 92 and 70%, respectively. The energy requirement did not increase at the same residence time under the experimental conditions of the single mode with a gas-flow rate of 11.5 m³ h⁻¹ and the series or parallel mode with a gas-flow rate of 23.0 m³ h⁻¹. The experimental results indicate that the series and parallel modes are effective in saving energy consumption, improving removal ability and efficiency, especially for the series mode.     

脉冲泵浦掺镱双包层光纤激光器的动力学研究

对脉冲泵浦的掺镱双包层光纤激光器进行了实验研究.采用重复频率1-10 kHz、脉宽100 μs的976 nmLDs泵浦,实现了脉宽小于10 ns的稳定激光脉冲输出.并对该激光器的动力学过程进行了分析,首次提出了在脉冲泵浦光纤激光器中产生ns脉冲是瑞利散射和受激布里渊散射共同作用的结果.     

改进冷端换热器的大功率脉冲管制冷机

依据热力学非对称理论对脉冲管制冷机冷端的热力学过程进行分析 ,对脉冲管制冷机制冷功率的提高提出了改进方案 ,搭建了单级低频大功率脉冲管制冷机的实验台 ,在实验中首次采用新型的填料烧结型换热器作为脉冲管的冷头 ,对这种换热器的效率在不同实验条件下进行了计算 ,并通过实验验证了这种新型换热器在脉冲管制冷机中应用的可行性。实验表明 :改进冷端换热器是提高脉冲管制冷机制冷效率的关键问题。在使用烧结换热器的单级脉冲管制冷机实验台上 ,采用输出功率 3k W的压缩机在 80 K时得到了 35W的制冷量 ,在效率上属国内领先水平。     

强双折射光纤中暗孤子的传输特性研究

从光纤双折射参量、背景光宽度、孤子脉冲宽度三方面探讨暗孤子在双折射光纤中远距离传输特性研究表明:相对于亮孤子,暗孤子对光纤双折射的自适应能力较弱;背景光宽度越大,暗脉冲与背景光对比度越好,暗孤子越能保持原来黑孤子状态;暗孤子脉冲宽度越大,偏振脉冲之间的差分群时延越大,诱导的灰孤子震荡结构越明显,越不利于暗孤子远距离传输.     

Elastodynamic analysis of a thin layer bonded on a visco-elastic medium under combined in-plane and lateral pulse loads

An analytic solution of a thin layer bonded on a visco-elastic medium under the action of in-plane and lateral pulse loads is presented. The analysis is based on double integral transforms with respect to space and time. Representative examples are studied and discussed to determine the influence of the (a) damping and elastic coefficients of visco-elastic medium, and (b) in-plane compression and stretching of the thin layer on wave propagation.