Fiber bragg gratings made with a phase mask and 800-nm femtosecond radiation

High-quality retroreflecting fiber Bragg gratings were written in standard Ge-doped telecom fiber (Corning SMF-28) after a few minutes exposure with pulsed 800-nm, 120-fs laser radiation by use of a deep-etch silica zero-order nulled phase mask optimized for 800 nm. Induced index modulations of 1.9 x 10(-3) were achieved with peak power intensities of 1.2 x 10(13) W/cm2 without any fiber sensitization. The fiber gratings are stable and did not erase after 2 weeks at 300 degrees C. The primary mechanism of induced index change results from a structural modification to the fiber core.     

利用单模激光Lorenz系统实现混沌反控制

利用Lyapunov函数方法，对混沌反控制问题进行了研究.以单模激光Lorenz系统和描述心脏搏动的Bonhoeffer-Van der Pol系统为例，设计了一种控制器，成功地使Bonhoeffer-Van der Pol系统混沌化.给出了控制器的具体设计方案以及单模激光Lorenz系统与Bonhoeffer-Van der Pol系统状态之间误差系统的结构.仿真结果表明，在控制器的作用下，Bonhoeffer-Van der Pol系统所有状态变量严格地跟踪了单模激光Lorenz系统的混沌轨迹，对应的相空间中Bonhoeffer-Van der Pol系统的轨迹也由极限环转变为与单模激光Lorenz系统的轨迹完全相同的混沌吸引子，Bonhoeffer-Van der Pol系统严格地跟踪了单模激光Lorenz系统混沌的动态行为.     

Simultaneous Determination of High-Density Lipoprotein,Very Low-Density Lipoprotein and Low-Density Lipoprotein Subclass in Human Serum by Microchip CE

Lipoproteins, especially high-density lipoproteins (HDL), very low-density lipoproteins (VLDL) and small, dense low-density lipoprotein (sdLDL), are believed to play an important role in the development of atherosclerosis. In this work, a simple, selective and sensitive method for the simultaneous monitoring of these lipoproteins in human serum using microchip capillary electrophoresis was developed. Gold nanoparticles were used as an additive to the running buffer to obtain the absolute separation of the lipoproteins. Under optimised conditions, the linear ranges of large buoyant low-density lipoproteins, sdLDL, VLDL and HDL were 10–800, 10–800, 40–1,000 and 20–800 μg L⁻¹, and their limits of detection were 5, 5, 15 and 8 μg L⁻¹, respectively. The intraassay and interassay relative standard deviation of lipoprotein peak areas were in the range of 3.8–7.4%. For practical application, variations in the serum lipoprotein of coronary heart disease patients were monitored by microchip-based CE. The results showed that the method was applicable for routine clinical use and allowed the rapid detection of different lipoprotein classes as well as their subclasses, thus greatly improving the analysis of atherosclerotic risk factors.

     

电磁学教学必须重视演示实验

阐述了电磁学演示实验的重要性及提高高校电磁学演示实验水平的途径.     

A novel colorimetric chemosensor based on quinoline for the sequential detection of Fe3+ and PPi in aqueous solution

A novel quinoline-functionalized Schiff-base derivative PY was designed and synthesized. Sensor PY displayed highly selective and sensitive fluorescence enhancement and naked-eye color change to Fe³⁺ in the presence of other competing cations. The mechanisms have been supported by Job’s plot evaluation, FT-MS and theoretical calculations. The in situ generated PY-Fe³⁺ complex solution exhibited a high selectivity toward PPi via Fe³⁺ displacement approach. The detection limits of sensor PY to Fe³⁺ and PY-Fe³⁺ complex to PPi were estimated to be 4.24 × 10^?8 M and 8.18 × 10^?8 M, respectively. This successive recognition feature of sensor PY makes it has a potential utility for Fe³⁺ and PPi detection in aqueous solution. A B3LYP/6-31G(d,p) basis set was employed for optimization of PY and PY-Fe³⁺ complex.     

ELASTIC WAVES IN 3-D DISCRETE GRIDS

Wave motion in finite element models presents some characteristics different from thoseof wave motion in continuum,which leads to the errors and other special phenomena in finite elementsimulation of wave motion.The wave propagation in a 3-D finite element model is studied by utilizingthe formal solution in the paper,and the corresponding dispersion relations are derived.Then the mainproperties of wave motion in 3-D grids such as dispersion,cut-off frequency and polarization drift arediscussed.Characteristics different from those of wave motion in 2—D grids are revealed.     

三维离散网格中的弹性波动

本文采用形式解法研究三维有限元离散模型中波动的传播规律。文中由波动方程得到它的特征方程，进而给出了三维离散网格中波的频散关系，分析了三维网格中平面波、非匀匀波、寄生振荡及其它可能存在的运动形式的基本特点；详细讨论了平面波的频散、截止频率及偏振漂移等重要的不同于连续介质中的波动传播性质的特点，提示了其中不同于低维网格中 波动的现象。     

Gene Cloning,Overexpression, and Characterization of the Nitrilase from <Emphasis Type="Italic">Rhodococcus rhodochrous</Emphasis> tg1-A6 in <Emphasis Type="Italic">E. coli</Emphasis>

A DNA fragment containing the entire coding sequence of nitrilase gene was amplified from Rhodococcus rhodochrous tg1-A6 with high nitrilase activity using PCR and sequenced. The open reading frame of the nitrilase gene contains 1,101 base pairs, which encodes a putative polypeptide of 366 amino acid residues. The nitrilase gene was cloned into an expression vector pET-28a and expressed in an Escherichia coli strain BL21(DE3). The enzymatic activity of nitrilase, which converts various nitriles to the corresponding carboxylic acids, was detected to reach 24.5 U/ml at 9 h in the recombinant bacteria.     

Determination of phthalate esters in soil by microemulsion electrokinetic chromatography coupled with accelerated solvent extraction

A novel method using microemulsion electrokinetic chromatography combining accelerated solvent extraction was developed for quantitative analysis of six phthalate esters (PAEs) including dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, as well as dioctyl phthalate. The effect of each individual component within the microemulsions, i.e. oil phase, surfactant and co-surfactant on resolution of the analytes was systematically studied. Baseline separation of six PAEs was achieved within 26?min by using the microemulsion buffer containing a 60?mmol/L borate buffer at pH 9.0, 0.5% v/v n-octane as oil droplets, 100?mmol/L sodium cholate as surfactant and 5.0% v/v 1-butanol as co-surfactant. The purposed accelerated solvent extraction-microemulsion electrokinetic chromatography method was successfully applied to the determination of trace amount of PAEs in soil samples collected from three different fields in areas of Fujian Province and the contents of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate and dioctyl phthalate were 0.63-0.68, 0.32-0.63, 2.53-3.96, 0-1.75, 7.32-11.7 and 0-3.46mg/kg, respectively. It was validated that the results were consistent with those obtained by GC-MS method.