CCD阵列检测-激光诱导荧光光度法测定食品中锌

利用自行组装的激光诱导荧光 CCD阵列检测器 计算机联用装置 ,建立了测定食品中锌的灵敏方法。在乙酸 乙酸铵缓冲溶液 (pH 4 )中 ,Zn(Ⅱ )与SCN- 、若丹明B(RhB)反应生成Zn SCN RhB配合物 ,经乙醚萃取后 ,在激发波长 5 32nm和发射波长 5 80nm进行荧光强度测定。研究了表面活性剂对Zn SCN RhB配合物荧光强度的影响 ,优化了荧光反应及食品样品的处理条件 ,并用于食品试样中锌的测定。方法的检出限为 4ng·ml- 1,加标回收率为 90 .0 %～ 110 .0 % ,相对标准偏差为 2 .0 %～ 9.7% ,能满足食品卫生检验的要求。     

声光可调滤光片作原子吸收光谱法波长选择器的初步研究

本文以微波等离子体炬 (MPT)为原子化器 ,以声光可调滤光片为波长选择系统 ,用原子吸收光谱法测定了Na元素。实验中考察了观察高度、微波功率、MPT工作气流量对Na吸收信号强度的影响。在最优化操作参数下测定Na的检出限为 0 2 3μg·mL- 1 ,测定精密度为 2 6 %。     

Exploring the possible interlinked structures in single‐wall carbon nanotubes under pressure by Raman spectroscopy

High‐pressure Raman measurements on single‐wall carbon nanotubes (SWNTs) have been carried out in a diamond anvil cell by using two wavelength lasers: 830 and 514.5 nm. Irrespective of using a pressure transmitting medium (PTM) or not, we found that nanotubes undergo similar transformations under pressure. The pressure‐induced changes in Raman signals at around 2 and 5 GPa are attributed to the nanotube cross‐section transitions from circle to ellipse and then to a flattened shape, respectively. Especially with pressure increasing up to 15–17 GPa, we observed that the third transition takes place in both the Raman wavenumber and the linewidth of G‐band. We propose explanations that the interlinked configuration with sp³ bonds forms in the bundles of SWNTs under pressure, which was the cause for the occurrence of those Raman anomalies, similar to the structural‐phase transition of graphite above 14 GPa. Our TEM observations and Raman measurements on the decompressed samples support this transition picture. Copyright © 2012 John Wiley & Sons, Ltd.     

直觉梯形模糊语言Frank算子及其在决策中的应用

本文在直觉梯形模糊语言集的基础上,引入了Frank算子,提出一组新的算子——直觉梯形模糊语言Frank集结算子,并将其应用到多属性决策中。首先,本文提出了直觉梯形模糊语言集Frank算子的表达式,并给出相应的运算规则。然后提出了直觉梯形模糊语言Frank加权算术平均(ITrFLFWA)算子、直觉梯形模糊语言Frank加权几何平均(ITrFLFWG)算子、直觉梯形模糊语言Frank广义加权平均(ITrFLGFWA)算子等,并证明了其具有幂等性、有界性、单调性等性质。最后,通过实例验证了直觉梯形模糊语言Frank算子可以有效解决直觉梯形模糊语言环境下的多属性决策问题。     

不确定区间隶属度语言变量及其应用

基于不确定语言变量和区间模糊数,提出了不确定区间隶属度语言变量的概念,定义了不确定区间隶属度语言变量的运算规则、大小比较方法,给出了不确定区间隶属度语言变量的加权算术平均算子、加权几何平均算子及其相应性质,并将这些算子应用于属性权重确知且属性值以不确定区间隶属度语言变量形式给出的不确定多属性群决策问题中,通过示例验证了基于不确定区间隶属度语言变量信息的多属性群决策方法的有效性和可行性。     

Carboxymethylated polyethylenimine modified magnetic nanoparticles specifically for purification of His‐tagged protein

Employing immobilized metal‐ion affinity chromatography and magnetic separation could ideally provide a useful analytical strategy for purifying His‐tagged protein. In the current study, a facile route was designed to prepare CMPEI‐Ni²⁺@SiO₂@Fe₃O₄ (CMPEI=carboxymethylated polyethyleneimine) magnetic nanoparticles composed of a strong magnetic core of Fe₃O₄ and a Ni²⁺‐immobilized carboxymethylated polyethyleneimine coated outside shell, which was formed by electrostatic interactions between polyanionic electrolyte of carboxymethylated polyethyleneimine and positively charged surface of 3‐(trimethoxysilyl)propylamin modified SiO₂@Fe₃O₄. The resulting CMPEI‐Ni²⁺@SiO₂@Fe₃O₄ composite nanoparticles displayed well‐uniform structure and high magnetic responsiveness. Hexa His‐tagged peptides and purified His‐tagged recombinant retinoid X receptor alpha were chosen as the model samples to evaluate the adsorption, capacity, and reusability of the composite nanoparticles. The results demonstrated the CMPEI‐Ni²⁺@SiO₂@Fe₃O₄ nanoparticles possessed rapid adsorption, large capacity, and good recyclability. The obtained nanoparticles were further used to purify His‐tagged protein in practical environment. It was found that the nanoparticles could selectively capture His‐tagged recombinant retinoid X receptor protein from complex cell lysate. Owing to its easy synthesis, large binding capacity, and good reusability, the prepared CMPEI‐Ni²⁺@SiO₂@Fe₃O₄ magnetic nanoparticles have great potential for application in biotechnological fields.     

基于广义变分正则化的闪光照相图像重建算法

 针对闪光照相图像信噪比低的特点,提出了一种基于广义变分正则化的图像重建算法,该方法采用p-范数取代目前广泛采用的全变分范数作为正则项,构造了用于图像重建的展平泛函,将图像重建问题转化为目标泛函最优化问题,采用固定点迭代法求解图像重建的最优解。数值计算结果表明,该算法在重建过程中能够有效抑制图像噪声,并加大对图像边缘的保持能力,从而提高了图像重建质量,是一种有效且性能优良的闪光照相图像重建算法。     

微波脉冲与不同形状带矩形孔缝腔体耦合的数值模拟

 利用时域有限差分法对微波脉冲与带矩形孔缝的矩形和圆柱形腔体两种系统的线性耦合过程进行了研究。首先用数值方法分析了耦合过程中的场增强现象、脉宽展开现象和腔体调制现象,并发现了耦合过程中微波脉冲存在频谱分离现象。当微波脉冲的电场与孔缝窄边平行时,借助耦合函数对两个系统内部耦合场的分布特性进行了研究,结果表明在与孔缝窄边垂直的平面内,越靠近腔体壁,耦合场越弱。此外,两种腔体内部的耦合场在腔体截面内均呈现准周期振荡分布,矩形腔体内部耦合场振荡的幅值较均匀,而圆柱形腔体内部耦合场幅值在其截面中心附近区域最大;除了孔缝附近区域外,圆柱腔体轴线两端的耦合场远大于矩形腔体相应的耦合场。最后,研究了孔缝耦合共振频率与孔缝尺寸的关系,结果表明系统耦合共振频率不只与孔缝尺寸有关,而是由孔缝尺寸和腔体形状及其对微波脉冲的反射特性共同决定。     

New problems of particle transfer in ferrocolloids: Magnetic Soret effect and thermoosmosis

The paper deals with critical reviewing of the experiments on thermodiffusion in ferrocolloids. The observed magnetic Soret effect is much stronger than that predicted theoretically. It is shown that the main reason of that is the influence of the magnetic field on mass diffusion. Besides, some measurements are affected by uncontrolled thermal and solutal magnetic convection. In porous media, when macroscopic convection is suppressed, thermodiffusion is accompanied by thermoosmosis as well as by a microconvective mass transfer induced by particle magnetophoresis on filter grains.     

Quantized charge pumping by surface acoustic waves in ballistic quasi-1D channels

Adiabatic pumping of electrons induced by surface acoustic waves (SAWs) in a ballistic quasi-1D quantum channel is considered using an exactly solvable tight-binding model for non-interacting electrons. The single-electron degrees of freedom, responsible for acoustoelectric current quantization, are related to the transmission resonances. We study the influence of experimentally controllable parameters (SAW power, gate voltage, source-drain bias, amplitude and phase of a secondary SAW beam) on the plateau-like structure of the acoustoelectric current. The results are consistent with existing experimental observations.Received: 24 February 2004, Published online: 12 July 2004PACS: 73.23.-b Electronic transport in mesoscopic systems - 73.50.Rb Acoustoelectric - magnetoacoustic effects - 73.40.Ei Rectification