A single standard calibration module for flow analysis systems based on solenoid microdevices

Only two computer-controlled microsolenoid devices, namely two micropumps or one micropump and one microvalve, are sufficient for the construction of on-line dilution modules useful in several flow analytical systems for the calibration using single standard. Three simple constructions of such modules were tested and compared. The most promising is the one based on the concept of a microvalve controlling dilution ratio of the standard and a solenoid micropump playing a double role: solution pumping device and mixing segments homogenizer. All investigated modules were tested with paired emitter detector diode (PEDD) as photometric flow-through detector and bromothymol blue as a model analyte. The best module was implemented into more advanced flow-injection system dedicated for optical detection of alkaline phosphatase activity using UV-PEDD-based flow-through detector for the enzyme reaction product.     

Microfluidic device capable of sensing ultrafast chemiluminescence

Based on the principle of liquid core waveguide, a novel microfluidic device with micro-scale detection window capable of sensing flashlight emitted from rapid 1,1′-oxalyldi-4-methylimidazole (OD4MI) chemiluminescence (CL) reaction was fabricated. Light emitted from OD4MI CL reaction occurring in the micro-dimensional pentagonal detection window (length of each line segment: 900.0 μm, depth: 50.0 μm) of the microfluidic device with two inlets and one outlet was so bright that it was possible to take an image every 1/30 s at the optimal focusing distance (60 cm) using a commercial digital camera. Peaks obtained using a flow injection analysis (FIA) system with the micro-scale detection window and OD4MI CL detection show excellent resolution and reproducibility without any band-broadening observed in analytical devices having additional reaction channel(s) to measure light generated from slow CL reaction. Maximum height (H_max) and area (A) of peak, reproducibility and sensitivity observed in the FIA system with the microfluidic device and OD4MI CL detection depends on (1) the mole ratio between bis(2,4,6-trichlorophenyl) oxalate and 4-methyl imidazole yielding OD4MI, (2) the flow rate to mix OD4MI, H₂O₂ and 1-AP in the detection window of the microfluidic device, and (3) H₂O₂ concentration. We obtained linear calibration curves with wide dynamic ranges using H_max and A. The detection limit of 1-AP determined with H_max and A was as low as 0.05 fmole/injection (signal/background = 3.0).     

Patterning of neural stem cells on poly(lactic-co-glycolic acid) film modified by hydrophobin

Patterning of neural stem cells (NSCs) is of great importance for its potential applications in the therapy of nerve injuries. Due to the critical requirements and the great difficulty in NSCs cultivation, developing new methods for NSCs patterning is very challenging and has progressed slowly in recent years. In this study, we reported a new method for patterning NSCs on a hydrophobin II (HFBI) modified poly(lactic-co-glycolic acid) (PLGA) film by using microcontact printing (μCP) technique. HFBI modification converted the PLGA surface from hydrophobic to hydrophilic, which should facilitate the absorption of serum on it. Serum was transferred onto the modified PLGA film by microcontact printing (μCP) to promote NSCs adhesion on the PLGA surface. Since the serum-coated PLGA surface promoted NSCs adhesion and the serum-free PLGA surface inhibited NSCs adhesion, micro-patterns of NSCs were obtained by directly culturing NSCs on the PLGA surface patterned with serum. This method allows the precise control of NSCs adhesion on the PLGA film without using the conventional cell-repellent species, which is anticipated to make great contribution in the fields of therapy of nerve injuries.     

Pseudopotential multi-relaxation-time lattice Boltzmann model for cavitation bubble collapse with high density ratio

The dynamics of the cavitation bubble collapse is a fundamental issue for the bubble collapse application and prevention. In the present work, the modified forcing scheme for the pseudopotential multi-relaxation-time lattice Boltzmann model developed by Li Q et al. [ Li Q, Luo K H and Li X J 2013 Phys. Rev. E 87 053301] is adopted to develop a cavitation bubble collapse model. In the respects of coexistence curves and Laplace law verification, the improved pseudopotential multi-relaxation-time lattice Boltzmann model is investigated. It is found that the thermodynamic consistency and surface tension are independent of kinematic viscosity. By homogeneous and heterogeneous cavitation simulation, the ability of the present model to describe the cavitation bubble development as well as the cavitation inception is verified. The bubble collapse between two parallel walls is simulated. The dynamic process of a collapsing bubble is consistent with the results from experiments and simulations by other numerical methods. It is demonstrated that the present pseudopotential multirelaxation-time lattice Boltzmann model is applicable and efficient, and the lattice Boltzmann method is an alternative tool for collapsing bubble modeling.     

光电跟踪系统稳定精度测试方法研究

针对光电跟踪系统稳定精度测试需求,提出一种稳定精度动态测试方法。该方法基于光学自准直原理,采用面阵CCD探测器,结合图像求取质心算法,实现被测系统的动态测试,通过该装置获得了稳定精度测试结果。结果表明:测试50 rad级两轴两框架系统动态稳定精度,通过该测试方法测出其稳定精度最大为48 rad。     

基于CCD检测器的便携式液体阴极辉光放电光谱仪快速测定卤水中的锂

锂是绿色能源和轻质合金的理想材料,作为一种重要的战略资源而备受各国重视.锂主要来源于盐湖卤水,我国盐湖卤水资源丰富,但主要分布在西部偏远地区,现场勘探和开采急需便携分析仪器的支持,然而目前现有实验分析技术均达不到野外现场分析的目标.近十年来,基于大气压液体阴极辉光放电光谱仪(SCGD-AES)因无需燃气,载气等气流条件及真空环境而受到关注.在前人研究基础上,自行开发了基于CCD光谱仪检测系统的便携式大气压液体阴极辉光放电光谱仪(简称Li-K分析仪),仪器长,宽,高分别为35,19和27 cm,重约为10 kg,十分有利于便携.选择Li的分析谱线波长为67078 nm,以取自西藏两种不同卤水水化学类型样品为研究对象,建立了卤水中Li的快速分析方法.在最佳工作条件下测得Li的检出限为4 ng·mL-1,方法的精密度(RSD)＜2％.研究表明,不同稀释倍数时,Li的分析结果与ICP-MS分析结果相差较大,这可能与溶液的基体效应有关,而采用标准加入法可有效减小基体效应的影响,获得了与ICP-MS较为一致的分析结果,可提高分析结果的准确度.大量实验结果表明,标准加入法只需2个点即可得到Li准确的分析结果,大大减少了实验工作量,为便携式Li-K分析仪在野外现场测定盐湖卤水中的Li奠定了方法学基础.     

基于旋转SURF算子的图像配准新方法

针对SURF算法中快速Hessian矩阵行列式检测出的特征点的不连续现象,从而造成的旋转,模糊和光照变化适应性较差的不足,提出一种旋转SURF检测算子的图像配准新方法。该算法通过将SURF算法的积分图像盒子滤波模板逆时针旋转45度,引入一种可以检测角度旋转的滤波核提升检测算子对不同图像变换的匹配性能,保证新的检测算子与原算法较好的结合,同时利用改进的单纯形算法依据输入图像进行参数优化。仿真结果表明,该方法不仅保留了算法的速度优势,缩短了配准时间,而且在图像模糊变换,光照变换和JPEG压缩变换方面性能有明显的提升,此外对视角变换以及小尺度变换性能也有提高。     

一种环金属铱、铂双核配合物的合成及光电性能

设计合成了一种双核环金属铱,铂配合物二[N,N-2-(2,4-二氟苯基吡啶)C3,N1](吡啶甲酸)合铱(Ⅲ)-C₆-[苯基吡啶-C3,N1](吡啶甲酸)合铂(Ⅱ)(FIrPPyPt)。 通过核磁共振仪、元素分析仪、紫外-可见吸收光谱仪和光致发光光谱仪对其结构和性能进行了表征。 结果表明,配合物FIrPPyPt的紫外-可见吸收位于250~450 nm之间,荧光发射峰位于465和493 nm。 将配合物FIrPPyPt以质量分数1%~8%掺杂到主体材料聚乙烯基咔唑(PVK)+2-(联苯-4-芳基)-5-(4-叔丁基苯)-1,3,4-噁二唑(PBD)(30%)中制作了电致发光器件,在不同电压下电致发光光谱中,显现出铱配合物和铂配合物的特征峰,波峰位于400、500和530 nm蓝绿光区发射区。 该双核配合物用于单掺杂有机白光电致发光器件具有制作简单、色稳定性和重复性好等特点,为单掺杂白光发光器件提供了一种好的思路。     

运用图示思维提升化学素养的教学案例研究

通过教学实践,引导学生运用图示思维,学习化学学科核心知识,提高获取信息,分析问题和解决问题的能力,深入理解化学学科本质,有效提升化学素养。     

Surface diffuse discharge mechanism of well-aligned atmospheric pressure microplasma arrays

A stable and homogeneous well-aligned air microplasma device for application at atmospheric pressure is designed and its electrical and optical characteristics are investigated. Current-voltage measurements and intensified charge coupled device(ICCD) images show that the well-aligned air microplasma device is able to generate a large-area and homogeneous discharge at the applied voltages ranging from 12 kV to 14 kV, with a repetition frequency of 5kHz, which is attributed to the diffusion effect of plasma on dielectric surface. Moreover, this well-aligned microplasma device may result in the uniform and large-area surface modification of heat-sensitive PET polymers without damage, such as optimization in hydrophobicity and biocompatibility. In the biomedical field, the utility of this well-aligned microplasma device is further testified. It proves to be very efficient for the large-area and uniform inactivation of E. coli cells with a density of 103/cm~2 on LB agar plate culture medium, and inactivation efficiency can reach up to 99% for 2-min treatment.