Microsensor Chip Integrated with Gold Nanoparticles‐Modified Ultramicroelectrode Array for Improved Electroanalytical Measurement of Copper Ions

This paper presents a microsensor chip integrated with a gold nanoparticles‐modified ultramicroelectrode array (UMEA) as the working electrode for the detection of copper ions in water. The microsensor chip was fabricated with Micro‐Electromechanical System technique. Gold nanoparticles were electrodeposited onto the surface of UMEA at a constant potential of ?0.3 V. The ratio d/R_b of interelectrode spacing (d) over the individual electrode’s radius (R_b) was investigated to improve the electrochemical performance. The UMEA with a d/R_b of 20 showed the best hemispherical diffusion mode, resulted in fast response time and high current response. The gold nanoparticles increased the active surface area of UMEA by not changing the geometries of UMEA, and the current response was increased further. Incorporating the optimized characteristic of UMEA and gold nanoparticles, the microsensor showed a good linear range from 0.5 to 200 µg L^?1 of copper ions in the acetate buffer solutions with the method of square wave stripping voltammetry. Compared with the gold nanoparticles‐modified disk electrode, the gold nanoparticles‐modified UMEA showed higher sensitivity (0.024 µA mm^?2 µg^?1 L) and lower limit of detection (0.2 µg L^?1). Water samples from river water and tap water were analyzed by the microsensor chip with recovery ranging from 100.7 % to 107.8 %.     

CuS/TiO2纳米管异质结阵列的制备及光电性能

利用水热反应制备了CuS/TiO2纳米管异质结阵列,采用场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和X射线衍射谱(XRD)等手段表征了异质结阵列的表面形貌和晶体结构.电流-电压曲线结果表明,CuS/TiO2纳米管异质结阵列具有明显的整流效应.根据表面光电压谱和相位谱,在376～600 nm之间,CuS/TiO2纳米管异质结阵列表现为p型半导体特征,电子在表面聚集;在300～376 nm之间表现为n型半导体特征,空穴在表面聚集;在376 nm处异质结阵列的表面光伏响应为零.CuS/TiO2和CuS/ITO之间界面电场的不同导致异质结在不同波长范围内表面电荷聚集的差异.光电化学性能测试发现,以CuS/TiO2纳米管异质结阵列为光阳极组成的光化学太阳电池,在大气质量AM 1.5G,100 mW/cm2标准光强作用下具有0.4%的光电转换能力.     

Trace gas detection of benzene,toluene, p-, m- and o-xylene with a compact measurement system using cantilever enhanced photoacoustic spectroscopy and optical parametric oscillator

A compact measurement system based on a novel combination of cantilever enhanced photoacoustic spectroscopy (CEPAS) and optical parametric oscillator (OPO) was applied to the gas phase measurement of benzene, toluene, and o-, m- and p-xylene (BTX) traces. The OPO had a band width (FWHM) of 1.3 nm, was tuned from 3237 to 3296 nm in steps of 0.1 nm and so spectra of BTX at different concentrations were recorded. The power emitted by the OPO increased from 88 mW at 3237 nm to 103 mW at 3296 nm. The univariate detection limits (3σ, 0.951 s) for benzene, toluene, p-, m- and o-xylene at 3288 nm were 12.0, 9.8, 13.2, 10.1 and 16.0 ppb, respectively. Multivariate data analysis using science-based calibration was used to resolve the interference of the analytes. The multivariate detection limits (3σ, 3237–3296 nm, 591 spectral points each 0.951 s) for benzene, toluene, p-, m- and o-xylene in the multi-compound sample, where all other analytes and water interfere were 4.3, 7.4, 11.0, 12.5 and 6.2 ppb, respectively. Without interferents, the multivariate detection limits varied between 0.5 and 0.6 ppb. The sum of the cross-selectivities (3237–3296 nm, 591 spectral points, each 0.951 s) per analyte were below 0.05 ppb/ppb, with an average of 0.038 ppb/ppb. The cross-selectivity of water to the analytes was on average 1.22 × 10⁻⁴ ppb/ppb. The OPO is small in size (L × W × H 125 × 70 × 45 mm), commercially available, and easy to operate and integrate to setups. The combination with sensitive CEPAS enables compact measurement systems for industrial as well as environmental trace gas monitoring.     

基于数字式MEMS传感器的声阵列成像系统设计*

常规驻极体传声器阵列成像系统存在数据采集系统复杂、体积大的问题,因而阵列传感器数量一般不超过60个,成像质量较差。为此,本文以数字式MEMS声传感器基础设计了260个传感器的声阵列,数据采集系统由FPGA控制,并嵌入到前端阵列中,后端是在另一个FPGA控制下的1个DSP芯片和2个PC104模块组成的集成系统,其中高速DSP芯片完成阵列信号处理以实现声成像功能。该系统能够实现对普通车间环境下机械设备噪声、气体泄漏噪声的现场成像测试,形成动态声像图。测试表明,该系统抗干扰能力强、声像分辨率高、成像速度快,实用效果良好。     

Trapped modes along a periodic array of freely floating obstacles

We consider the coupled problem describing the motion of a linear array of three‐dimensional obstacles floating freely in a homogeneous fluid layer of finite depth. The interaction of time‐harmonic waves with the floating objects is analyzed under the usual assumptions of linear water‐wave theory. Quasi‐periodic boundary conditions and a simplified reduction scheme turn the system into a linear spectral problem for a self‐adjoint operator in Hilbert space. Based upon the operator formulation, we derive a sufficient condition for the nonemptiness of its discrete spectrum. Various examples of obstacles that generate trapped modes are given. Copyright © 2014 John Wiley & Sons, Ltd.     

CuInS2纳米纸阵列薄膜的制备及生长机理

采用溶剂热合成技术,以氯化铜、硝酸铟和硫脲为反应物,十六烷基三甲基溴化铵(CTAB)为阳离子表面活性剂,草酸为还原剂,无水乙醇为溶剂,直接在掺氟的SnO2透明导电玻璃(FTO)衬底上合成CuInS2(CIS)薄膜.采用扫描电子显微镜(SEM)、高分辨率透射电子显微镜(HRTEM)、X射线衍射(XRD)、拉曼光谱、能量色散谱(EDS)、紫外-可见(UV-Vis)反射光谱和透射光谱对样品的形貌、结构、成分和光学性能进行分析.结果表明,在适当的反应物浓度下,在FTO衬底上形成了垂直衬底生长的、具有良好结晶性能的黄铜矿结构的CIS纳米纸阵列薄膜.CIS薄膜中Cu,In,S的原子比为1.1∶1∶2.09,在紫外-可见和近红外波段具有良好的光吸收特性,禁带宽度约1.51 eV.结合不同反应时间制备的CIS薄膜的形貌、结构和成分分析,讨论了CIS纳米纸阵列薄膜的生长机理.     

ZnO纳米管有序阵列与Cu2O纳米晶核壳结构的光电化学性能及全固态纳米结构太阳电池研究简

采用电化学方法在铟锡氧化物(ITO)导电玻璃基底上制备了高度有序的ZnO纳米管阵列,然后在ZnO纳米管阵列上电化学沉积Cu2O纳米晶颗粒,获得了一维有序Cu2O/ZnO核壳式纳米阵列结构,通过控制Cu2O纳米晶的沉积电量得到不同厚度的Cu2O壳层,并对该核壳式纳米阵列的形貌和结构进行了分析. 以Cu2O/ZnO一维核壳式纳米阵列结构为光电极组装全固态纳米结构太阳电池,研究了Cu2O壳层厚度对光电极光吸收性能、光电性能以及组装电池光伏性能的影响,优化了电池中对电极材料的喷金厚度. 结果表明,以Cu2O沉积电量为1.5 C的Cu2O/ZnO为光活性层,以4 mA电流下真空镀金20~25 min的铜基底为对电极组装的简易太阳电池最高可获得0.013%的光电转换效率.     

Rapid quantitative analysis of individual anthocyanin content based on high‐performance liquid chromatography with diode array detection with the pH differential method

A new quantitative technique for the simultaneous quantification of the individual anthocyanins based on the pH differential method and high‐performance liquid chromatography with diode array detection is proposed in this paper. The six individual anthocyanins (cyanidin 3‐glucoside, cyanidin 3‐rutinoside, petunidin 3‐glucoside, petunidin 3‐rutinoside, and malvidin 3‐rutinoside) from mulberry (Morus rubra) and Liriope platyphylla were used for demonstration and validation. The elution of anthocyanins was performed using a C₁₈ column with stepwise gradient elution and individual anthocyanins were identified by high‐performance liquid chromatography with tandem mass spectrometry. Based on the pH differential method, the high‐performance liquid chromatography peak areas of maximum and reference absorption wavelengths of anthocyanin extracts were conducted to quantify individual anthocyanins. The calibration curves for these anthocyanins were linear within the range of 10–5500 mg/L. The correlation coefficients (r²) all exceeded 0.9972, and the limits of detection were in the range of 1–4 mg/L at a signal‐to‐noise ratio ≥5 for these anthocyanins. The proposed quantitative analysis was reproducible with good accuracy of all individual anthocyanins ranging from 96.3 to 104.2% and relative recoveries were in the range 98.4–103.2%. The proposed technique is performed without anthocyanin standards and is a simple, rapid, accurate, and economical method to determine individual anthocyanin contents.     

铂修饰的{001}面暴露的二氧化钛纳米片阵列的制备和光催化性能

采用有机溶剂热法在FTO衬底上制备{001}面暴露的单晶锐钛矿相TiO2纳米片阵列,通过FESEM和XRD研究样品的形貌和晶体结构. 与水热法制备的纳米片阵列相比,有机溶剂热法制备的样品取向性更好. 采用光沉积方法在纳米片阵列上沉积Pt,所得到的Pt纳米颗粒粒径更为均匀,并且更容易沉积在{001}面上. 所负载的Pt 纳米颗粒增强了TiO2纳米片的光吸收性能,同时大大减弱了光致发光强度. 在光催化性能测试中,具有最优负载量的样品催化性能提高了一倍. 与传统的Pt负载相比,{001}面的最优负载量显得相当小,这可能源于高活性{001}面的原子结构.     

Pd增强缺陷态TiO2纳米管阵列的光催化产氢性能

通过光还原沉积法, 利用氧空位诱导作用, 在Ni掺杂的缺陷态TiO₂纳米管阵列(TNT-Ni)上得到金属 Pd含量不同的Pd-TNT-Ni催化剂. 采用场发射扫描电子显微镜(SEM)、 X射线光电子能谱(XPS)、 紫外-可见 漫反射(UV-Vis DRS)、 表面光电压(SPV)、 光致发光光谱(PL)和电化学测试等表征手段, 探究了Pd与Ni掺杂的缺陷态TiO₂纳米管阵列之间的强相互作用对其光吸收特性和载流子分离及传输效率的影响, 阐明了强相互 作用对材料光催化活性的调控机理, 提出了Pd增强Pd-TNT-Ni光催化性能的作用机理. 结果表明, 通过光还 原法制备的Pd纳米颗粒尺寸为10~20 nm的Pd₁₂₀-TNT-Ni样品的光响应值为4.22 mA/cm², 是未负载Pd样品光 响应值(1.14 mA/cm²)的3.7倍, 其具有最佳的平均产氢速率(5.16 mmol·g^?1·h^?1), 是TNT样品平均产氢速率 (0.45 mmol·g^?1·h^?1)的12倍, 表明Pd与缺陷态TiO₂纳米管阵列之间的强相互作用驱动了载流子的分离及传输, 且Pd作为电子捕获势阱及反应活性位点, 显著提高了材料的光催化性能.