A label-free amperometric immunosenor based on multi-layer assembly of polymerized o-phenylenediamine and gold nanoparticles for determination of Japanese B encephalitis vaccine

A label-free amperometric immunosensor for fast and sensitive assay of Japanese B encephalitis vaccine is presented. Antiserum of Japanese B encephalitis were immobilized on bilayer nano-Au/o-phenylenediamine polymer film with deposited Prussian blue as an electronic mediator on the Pt electrode. The electrochemical behavior of the biosensor was studied with Fe^2+/3+ as probe on the Pt surface using cyclic voltammetry technique. The variation of amperometric response to the concentration of Japanese B encephalitis vaccine, the target antigen, was evaluated by cyclic voltammetry in PBS. The immunosensor showed a specific response to Japanese B encephalitis vaccine in the range 1.1 × 10⁻⁸ to 1.9 × 10⁻⁶ lg pfu/ml (pfu/ml is plaque forming unit and lg is common logarithm) with a detection limit of 6 × 10⁻⁹ lg pfu/ml. The correlation coefficient is 0.9955. The incubation time, incubation temperature, pH, reproducibility and stability of the immunosensor were also studied. The present work supplied a promising test method for biological products.     

Circularly Polarized Luminescence of Achiral Carbon Dots in Bi-Solvent Systems Triggered by Supramolecular Self-Assembly

An innovative strategy for circularly polarized luminescence (CPL) of carbon dots (CDs) has been developed: The achiral CDs displayed contrary supramolecular chirality and opposite CPL in two different bi-solvent systems, which are due to the formation of self-assembled helical nanostructures with two diverse assembly modes (P and M) in aggregate state via intermolecular π-π interactions and differential hydrogen bonding (H-bonding) without the need of any additional element of chirality.     

Enhancement of giant magneto-impedance effect in Ni80Fe20/SiO2/Cu composite wires

Ni₈₀Fe₂₀/SiO₂/Cu composite wires of Cu core 60 μm in diameter and coated with layers of SiO₂ and Ni₈₀Fe₂₀ were prepared by RF magnetron sputtering. The influences of the insulator layer thickness, the measurement mode and the magnitude of the driving current on the giant magneto-impedance (GMI) effect were investigated. The results showed that there was an optimum thickness of the insulator layer and the driving current can influence the shape of the MI curve. Resonance enhancement of the GMI was found in the new measurement mode. The results are discussed by taking account of the electromagnetic interactions.     

Application of dispersive liquid-liquid microextraction for the analysis of triazophos and carbaryl pesticides in water and fruit juice samples

In this work, a simple, rapid and sensitive sample pretreatment technique, dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography-fluorescence detection (HPLC-FLD), has been developed to determine carbamate (carbaryl) and organophosphorus (triazophos) pesticide residues in water and fruit juice samples. Parameters, affecting the DLLME performance such as the kind and volume of extraction and dispersive solvents, extraction time and salt concentration, were studied and optimized. Under the optimum extraction conditions (extraction solvent: tetrachloroethane, 15.0 μL; dispersive solvent: acetonitrile, 1.0 mL; no addition of salt and extraction time below 5 s), the performance of the proposed method was evaluated. The enrichment factors for the carbaryl and triazophos were 87.3 and 275.6, respectively. The linearity was obtained in the concentration range of 0.1-1000 ng mL⁻¹ with correlation coefficients from 0.9991 to 0.9999. The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, ranged from 12.3 to 16.0 pg mL⁻¹. The relative standard deviations (RSDs, for 10 ng mL⁻¹ of carbaryl and 20 ng mL⁻¹ of triazophos) varied from 1.38% to 2.74% (n = 6). The environmental water (at the fortified level of 1.0 ng mL⁻¹) and fruit juice samples (at the fortified level of 1.0 and 5.0 ng mL⁻¹) were successfully analyzed by the proposed method, and the relative recoveries of them were in the range of 80.4-114.2%, 89.8-117.9% and 86.3-105.3%, respectively.     

Effect of O2 and H2O on the tri-reforming of the simulated biogas to syngas over Ni-based SBA-15 catalysts

A series of Ni/SBA-15 catalysts with Ni contents from 7.5 wt% to 15 wt% were prepared by impregnation method. The effect of O2 and H2O on the combined reforming of the simulated biogas to syngas was investigated in a continuous flow fixed-bed micro-reactor. The stability of the catalyst was tested at 800 ℃. The results indicated that 10 wt%Ni/SBA-15 catalyst exhibited the highest catalytic activities for the combined reforming of the simulated biogas to syngas. Under the reaction conditions of the feed gas molar ratios CH4/CO2/O2/H2O = 2/1/0.6/0.6, GHSV = 24000 ml•g{cat}-1\cdoth-1 and the reaction temperatureT = 800 ℃, the conversions of CH4 and CO2 were 92.8% and 76.3%, respectively, and the yields of CO and H2 were 99.0% and 82.0%, respectively. The catalytic activities of the catalyst did not decrease obviously after 100 h reaction time on stream.     

磁控溅射制备Ni/Ti多层膜表面粗糙度

采用磁控溅射方法制备了周期数分别为10,30,50和75的Ni/Ti多层膜,利用X射线掠入射反射测量了多层膜表面和界面的状态,并用原子力显微镜测量了多层膜的表面粗糙度,研究了不同周期数的Ni/Ti多层膜表面粗糙度的变化规律。结果表明:Ni/Ti多层膜表面粗糙度随着膜层数增加而增加,当Ni/Ti多层膜的周期数从10变化到75时,其表面粗糙度由0.80 nm增大到1.69 nm。实验数据拟合表明:Ni/Ti多层膜表面粗糙度与周期数成3次方关系;但在周期数较小时,粗糙度与周期数成线性关系。     

基于高分辨质谱的化妆品中20种香料的高通量检测

基于静电场轨道阱高分辨质谱技术,建立化妆品中20种香料成分的高通量检测方法,并应用于实际样品中香料成分的筛查与定量分析。利用香料成分标准品通过高分辨质谱正负离子切换FullMS/ddM S^2扫描方式分析,获得多种香料成分的保留时间、一级母离子和二级碎片离子精确质量数,构建香料成分筛查谱库。样品用甲醇超声提取后,经超高效色谱柱分离,采用高分辨质谱分析,利用TraceFinder软件对化妆品中的香料成分与谱库相关信息匹配,实现目标物的高通量筛查确证,筛查确认后利用一级母离子外标法进行香料成分的定量分析。经验证该方法的线性关系良好(R^2>0.99),方法的检出限(0.1~10μg/g)、回收率(89.6%~109.1%)和精密度(3.1%~9.2%)能够满足欧盟对香料成分标注的限量要求,可用于同时测定化妆品中多种香料成分。     

Cell Morphology Variations of Klebsiella pneumoniae Induced by Acetate Stress Using Biomimetic Vesicle Assay

Supplementation with acetate under low levels was used as a novel approach to control the morphological development of Klebsiella pneumoniae aimed to improve 1,3-propanediol (1,3-PD) production. A full range of morphological types formed from rod shape to oval shape even round shape in response to different concentrations of acetate. The cell growth and 1,3-PD productions in the shake flasks with 0.5 g/L acetate addition were improved by 9.4 and 28.37 %, respectively, as compared to the control, while the cell became shorter and began to lose its original shape. The cell membrane penetration by acetate was investigated by the biomimetic vesicles, while higher concentration of acetate led to more moderate colorimetric transitions. Moreover, the percentage composition of unsaturated fatty acid (UFA) was increased as well as the increased concentrations of acetate, whereas higher UFA percentage, higher fluidity of bacterial cell membrane.     

Investigation of ultra-short-period W/C multilayers for soft X-ray optics

Ultra-short-period W/C multilayers having periodic thickness range of 1.15-3.01 nm have been fabricated for soft X-ray optics using the high vacuum direct current (DC) magnetron sputtering system.