Study of the matrix effects of tetrodotoxin and its content in cooked seafood by liquid chromatography with triple quadrupole mass spectrometry

Tetrodotoxin is a marine biotoxin with high acute toxicity. The levels in cooked seafood will help us to assess its intake in humans and may help assess the risk of toxicity. However, heavy matrices hinder the direct quantitation of tetrodotoxin. A quantitative method of measuring tetrodotoxin in cooked seafood using liquid chromatography with triple quadrupole mass spectrometry was established in this study. Tetrodotoxin was extracted from the sample matrix using 2% formic acid in methanol and cleaned using a cation exchange cartridge. The cleanup conditions were optimized. The matrix effects were determined using the postextraction spiking method and by comparing the slope of the linear regression equation in sample matrix to that in solvent. The limit of detection in the sample matrix was 5 μg/kg and the limit of quantification was 10 μg/kg. The mean recoveries at three spiking levels were 66.9–89.2% with relative standard deviations of 5.0–10.8% (n = 6) in five different matrices. Tetrodotoxin was found at concentrations of 26.1–2462 μg/kg in nine of 83 cooked seafoods tested in this study. Eight analogs of Tetrodotoxin were detected in the samples studied.     

离子色谱的抑制系统及相关技术的发展

抑制系统是抑制型(双柱型)离子色谱系统极为重要的一个组成部分,也是离子色谱有别于其它类型的液相色谱的最重要特点之一。抑制器的发展经历了多个发展时期,而目前商品化的离子色谱仪亦分别采用不同形式的抑制手段。近年来,还发展了一些特殊的辅助抑制器,如接在抑制器后面CO2除去装置,用于提高被测离子的信号或进一步降低背景电导值。     

箔式高阻值低压锰铜压阻应力计的设计及动态标定

设计了低压锰铜压阻传感器 ,并通过平板撞击实验标定了该传感器在 0 .3～ 9.4GPa范围内的压阻关系。标定曲线在 0 .3～ 1.5GPa范围内是线性的 ,对应的是传感器的弹性状态 ,而在 1.5～ 9.4GPa范围内是二次曲线。标定曲线的拐点在 1.5GPa附近 ,这与理论分析和他人的实验结果相接近。     

无机类富勒烯过渡金属硫化物纳米材料的合成及其摩擦学应用研究进展

评述了无机类富勒烯（IF）与过渡金属硫化物（WS2和MoS2等）纳米材料的合成技术及其摩擦学应用研究的最新进展，外型为球形或近似于球形并具有嵌套中空结构的IF－WS2和IF－MoS2纳米果粒具有潜在的摩擦学应用前景；对含有IF－WS2纳米颗粒的复合材料和Ni-P复合镀层的研究表明，其比含有石墨和层状2H－WS2粉末的固体润滑剂具有更优异的摩擦学性能。     

粘塑性薄壁管中复合应力波的传播特性研究

以本构关系一般理论为基础,导出了计及材料功硬化效应和应变率硬化效应的粘塑性薄壁管的本构关系及管中复合应力波的控制方程,应用有限差分方法研究了在压扭复合冲击载荷作用下粘塑性薄壁管中复合应力波的传播特性与演化规律,分析了复合应力波的耦合效应以及薄壁管中粘塑性参数和功硬化效应对复合应力波传播与演化规律的影响,并对有关现象进行了分析和解释。     

LY12铝疲劳裂纹在冲击载荷下的演化研究

对LY12铝合金在低周疲劳条件下的裂纹情况和随后进行的动态拉伸条件下裂纹的发展给予了观察和统计分析，发现裂纹的累积数密度分布在损伤演化过程中保持指数形式，用NAG模型对实验结果进行分析，得出该材料裂纹演化发展方程的各种参数。     

Conjugated turbulent heat transfer with axial conduction in wall and convection boundary conditions in a parallel-plate channel

The steady-state conjugated turbulent heat transfer with axial conduction in the wall and convection boundary conditions is solved with the generalized integral transform technique for the flow of Newtonian fluid in parallel-plate duct. A lumped wall model that neglects transverse temperature gradients in the solid but that takes into account the axial heat conduction along the wall is adopted. Highly accurate results are presented for the fluid bulk and wall temperatures and Nusselt number. The effects of the conjugation parameter, Biot number, and the dimensionless channel length on Nusselt number and fluid bulk and wall temperatures are systematically investigated.     

爆炸容器内冲击波系演化及壳体响应的数值研究

对中心装药爆炸后冲击波的产生、传播和壳体动态响应全过程进行了数值研究。认为RDX瞬时爆炸 ,爆炸近场采用自相似解 ;冲击波传播和波系演化采用PPM (the Piecewise Parabolic Method)格式求解Eu ler方程 ;壳体响应采用有限元方法求解拉氏坐标系下由虚功原理得到的动力学方程。壳体内壁面边界条件分别采用强耦合和弱耦合方法处理。结果表明 :(1)当装药量相同时 ,薄壁壳体振型比厚壁壳体复杂得多 ,振幅也大 ;(2 )当装药量不同 ,壳体厚度相同时 ,爆炸场冲击波的演化过程不同 ;(3)对少量装药 ,产生的冲击波强度低 ,壳体变形小 ,是否考虑内边界运动 ,对计算结果的影响不大 ;(4 )在本文条件下 ,爆炸容器封头顶点所受的载荷最大 ,是最易发生破坏的地方 ,侧壁与爆点所在横截面的交线 ,也易破坏。     

几种高性能纤维束的冲击动力学性能实验研究

利用直拉式Hopkinson装置研究了碳纤维、无碱E玻璃纤维、Kevlar 4 9/96 4 /96 4c、Twaron2 0 0 0、DyneemaSk6 6等纤维的动态拉伸性能。与准静态加载条件下相比 ,纤维束的拉伸强度基本与应变速率无关(玻璃纤维除外 ) ,而纤维束的弹性模量和失效应变随应变率的升高而明显变大。从高分子物理以及两种无机纤维的内部微观结构特征对纤维的力学性能与加载速率的关系进行了初步的物理阐释。讨论了实验数据的发散原因。     

Study on detection of mutation DNA fragment in gastric cancer by restriction endonuclease fingerprinting with capillary electrophoresis

The DNA fragment detection focusing technique has further enhanced the sensitivity and information of DNA targets. The DNA fragment detection method was established by capillary electrophoresis with laser‐induced fluorescence detection and restriction endonuclease chromatographic fingerprinting (CE‐LIF‐REF) in our experiment. The silica capillary column was coated with short linear polyarclarylamide (SLPA) using nongel sieving technology. The excision product of various restricted enzymes of DNA fragments was obtained by REF with the molecular biology software Primer Premier 5. The PBR322/BsuRI DNA marker was used to establish the optimization method. The markers were focused electrophoretically and detected by CE‐LIF. The results demonstrate that the CE‐LIF‐REF with SLPA can improve separation, sensitivity and speed of analysis. This technique may be applied to analysis of the excision product of various restricted enzymes of prokaryotic plasmid (pIRES2), eukaryote plasmid (pcDNA3.1) and the PCR product of codon 248 region of gastric cancer tissue. The results suggest that this method could very sensitively separate the excision products of various restricted enzymes at a much better resolution than the traditional agarose electrophoresis. Copyright © 2011 John Wiley & Sons, Ltd.