ATR-FTIR study of Bacillus sp. and Escherichia coli settlements on the bare and Al2O3 coated ZnSe internal reflection element

FTIR-ATR has been used for understanding the interaction between bacteria and surfaces in the adsorption progress.     

水中氯苯类污染物的顶空液相微萃取 GC-MS法测定

研究了用顶空液相微萃取GC-MS法测定水中的痕量氯苯类有机污染物。通过实验选择正辛醇为萃取剂,考察了萃取剂的体积、萃取温度、萃取时间、搅拌速度、样品顶空体积以及盐效应等对萃取的影响。在最佳萃取和测定条件下,方法的线性范围为0.1~800μg/L,检出限(S/N=3)为0.05~0.1μg/L。用本方法测定了实际样品及回收率,结果满意。     

Design and fabrication of 2 kHz nematic liquid crystal variable retarder with reflection mode

ABSTRACT

This study proposes a simple method of designing a high-speed liquid crystal variable retarder (LCVR) with reflection mode. First, a series of simple formulas is provided for analysing the effects of tilt incidence and birefringence of the liquid crystal on the phase retardation and response time of the LCVR. Then, a reflective LCVR is fabricated to validate the theoretical analysis. Measured results show that the response speed can reach 2.7 kHz with a phase retardation of 1 λ. Furthermore, the theoretical curve is close to the measured curve while the incident angle is less than 10°. However, the theoretical and measured values show a considerable difference under a large incident angle. This problem is discussed, and a modified method is given. This work is helpful for the design and fabrication of high-speed LCVR.     

一例可分离的双核铁氢自由基阳离子

成功分离得到了一例双核铁氢自由基阳离子盐cis-[Fe₂Cp₂（μ-H）（μ-PPh₂）（CO）₂]^·+[Al（OC（CF₃）₃）₄]^-（cis-1^·+[Al（OC（CF₃）₃）₄]^-）晶体，并使用单晶X射线衍射、电子顺磁共振、红外光谱、紫外-可见光谱以及密度泛函理论对它进行了表征和理论计算。电子顺磁共振和密度泛函理论计算分析表明，自由基的自旋密度主要均等分布于2个铁原子上。     

Effect of Ce<Superscript>3+</Superscript> on spectral characteristic of D1/D2/Cytb559 complex from spinach

It was studied by spectroscopy that PSII reaction center complex consisting of three polypeptides, D₁, D₂ and Cytb559, were purified from PSII particle of CeCl₃ treated spinach. The results of the experiment show that Ce³⁺ could improve the growth of spinach, and accelerate electron transport of PSII particles. Of chl-a of UV-Vis spectrum of D1/D2/Cytb559 complex, Soret band was blue-shifted by 3 nm and Q band by 2 nm, respectively, and the fluorescence emission peak was blue-shifted by 5 nm in CeCl₃-treated spinach compared with the one in control. By the extended X-ray absorption fine structure (EXAFS) spectroscopy methods, it has been found that Ce³⁺ is coordinated with 8 nitrogen atoms in the first coordination shell with Ce-N bond length of 0.253 nm, and Ce³⁺ with 6 oxygen atoms in the second coordination shell with Ce-O bond length of 0.32 nm. However, the secondary structure of D1/D2/Cytb559 complex by circular dichroism (CD) spectroscopy has no significant change after CeCl₃ treated. It might be that Ce³⁺ binds to porphyrin rings of chlorophyll and oxygen of amino acid residue of polypeptide in D1/D2/Cytb559 complex, and then accelerates the primary reaction of PSII, intensifies function of P680⁺ primary electron donor of D1/D2/Cytb559, but there is little change in conformation of PSII reaction center complex.     

A Line Search SQP-type Method with Bi-object Strategy for Nonlinear Semidefinite Programming

We propose a line search exact penalty method with bi-object strategy for nonlinear semidefinite programming. At each iteration, we solve a linear semidefinite programming to test whether the linearized constraints are consistent or not. The search direction is generated by a piecewise quadratic-linear model of the exact penalty function. The penalty parameter is only related to the information of the current iterate point. The line search strategy is a penalty-free one. Global and local converg...     

含有偏好的DEA-BWM评价方法研究

针对传统的DEA模型在评估过程中并未考虑决策者对相关指标权重的偏好,将最优最差方法(BWM)嵌入到传统DEA模型中,基于决策者偏好排序的判断矩阵,构建一种含有偏好的DEA-BWM评价方法。首先在保持传统DEA方法的优势基础上,构建了CCR-BWM评价模型对各DMU进行评价。同时考虑为了便于各决策单元在统一权重基础上相互比较,构建了CSW-BWM公共权重模型。另外考虑决策单元自评和互评,构建了NCE-BWM中立型交叉效率。然后采用min-max方法分别将上述三种多目标评价模型转换为单目标线性规划进行求解。最后,选择一组算例对三种模型的有效性与合理性进行验证。     

Rapid detection of Escherichia coli by flow injection analysis coupled with amperometric method using an IrO2–Pd chemically modified electrode

An amperometric method for the rapid detection of Escherichia coli (E. coli) by flow injection analysis (FIA) using an IrO₂–Pd chemically modified electrode (CME) was developed in this paper. The method is based on a good marker β-d-galactosidase which was found in E. coli strains. β-d-galactosidase was produced by the induction of isopropyl β-d-thiogalactopyranoside (IPTG) and released from E. coli cells through the permeabilization of both polymyxin B nonapeptide and lysozyme to E. coli cells wall. The released β-d-galactosidase could catalyze the hydrolysis of the substrate p-aminophenyl β-d-galactopyranoside (PAPG) in the culture medium to produce 4-aminophenol which was proportional to the concentration of E. coli. Hence, E. coli could be detected by the determination of 4-aminophenol. An IrO₂–Pd CME, which showed high sensitivity in determination of 4-aminophenol, was prepared as the electro-detector in FIA. The amplified response current of 4-aminophenol obtained at the IrO₂–Pd CME was linear with the concentration of E. coli ranging from 2.0 × 10² to 1.0 × 10⁶ cfu/mL, the detection limit of this method to E. coli was 150 cfu/mL and the complete assay could be performed in 3 h.     

Noncovalent fluorous interactions for the synthesis of carbohydrate microarrays

A surface patterning method based on noncovalent immobilization of fluorous-tagged sugars on fluorous-derivatized glass slides allows the facile fabrication of carbohydrate microarrays. To expand the scope of these arrays, the first syntheses are reported of arabinose, rhamnose, lactose, maltose, and glucosamine tagged with a single C₈F₁₇-tail for ease of purification as well as array formation. Screening of these carbohydrate microarrays against lectins from Triticum vulgaris (WGA) and Arachis hypogaea (PNA) demonstrate that the noncovalent fluorous–fluorous interaction is sufficient to retain not only mono- but also disaccharides under the biological assay conditions.