原子吸收光谱法测定重金属铬的含量

以火焰原子吸收光谱法测定重金属铬含量为宗旨,考察了雾化器流量、乙炔流量、氧化剂流量、燃烧头高度、基本改进剂等因素,结果发现,通过实验条件优化,校正系数从0.998265提高到0.999998,该方法能最大程度改善火焰原子吸收光谱法测定铬元素灵敏度低的问题,具有快速、准确、灵敏度高等优点,为与人类密切相关的食品、药品、化妆品、医疗器械等产品中重金属铬含量测定提供一定的参考。     

磁固相萃取与胶体金免疫层析试纸条联用检测食品中氯霉素

本文建立了磁固相萃取前处理与胶体金免疫层析试纸条联用检测食品中氯霉素(CAP)的分析方法。蜂蜜和鸡蛋样品经磁固相萃取后,再用检测牛奶样品中CAP的胶体金免疫层析试纸条检测。结果表明:两者联用后使得只能用于检测牛奶样品中CAP的试纸条也能应用于蜂蜜和鸡蛋等样品,而且方法的检出限在蜂蜜和鸡蛋样品中低至0.2ng/g。该联用方法扩大了CAP试纸条的应用范围,同时降低了检测成本。     

Comparability of analytical results obtained in proficiency testing based on a metrological approach

A “yes–no” type of criterion is proposed for the assessment of comparability of proficiency testing (PT) results when the PT scheme is based on a metrological approach, i.e. on the use of a reference material as the test sample, etc. The criterion tests a null hypothesis concerning the insignificance of a bias of the mean of the results from a traceable value certified in the reference material used for the PT. Reliability of such assessment is determined by the probabilities of not rejecting the null hypothesis when it is true, and rejecting it when it is false (the alternative hypothesis is true). It is shown that a number of chemical, metrological and statistical reasons should be taken into account for careful formulation of the hypotheses, enabling the avoidance of an erroneous assessment of the comparability. The criterion can be helpful for PT providers and laboratory accreditation bodies in analysis of PT results.     

Book Reviews

Room temperature glass containing copper nitrate was produced using the microemulsion-gel method. Ultraviolet-visible spectroscopy and x-ray diffraction spectra were used to demonstrate the presence of copper nitrate in the gel samples. The samples were examined using optical microscopy, with and without polarized filters, and scanning electron microscopy with energy dispersive x-ray analysis, before and after the extraction of the surfactant with an organic solvent. The results indicated that copper nitrate was present throughout the silicate network formed and was associated with the microemulsion components, i.e., the interstitial liquid, remaining in the bulk material.     

基于新型量子点荧光微球的氯霉素免疫层析试纸条的制备和应用

以羧基化CdTe/ZnSe量子点荧光微球为标记物,通过1-乙基-(3-二甲基氨基丙基)碳二亚胺/N-羟基琥珀酰亚胺(EDC/NHS)活化法将氯霉素(CAP)单克隆抗体与量子点荧光微球偶联制备荧光探针.氯霉素全抗原(CAP-HS-BSA)及羊抗鼠二抗分别喷涂硝酸纤维素膜,形成检测线(T线)和质控线(C线),组装成新型氯霉素量子点荧光微球免疫层析试纸条,建立了快速、定量检测牛奶中CAP的方法.本研究开发的量子点荧光微球试纸条可在15 min内完成牛奶样品中CAP的定量检测,线性范围为0.1~100.0μg/L,检出限为0.1μg/L.牛奶样品CAP的加标回收率为93.3%~97.9%,相对标准偏差在4.9%~6.9%之间.     

先进超导导体测试装置设计分析

针对聚变工程大型超导导体样品在高场下的性能测试需求,设计了内径0.6m、磁场13T的背景磁体系统。磁体系统由6层12个分离式超导线圈组成,线圈采用常规的螺线管结构,由外至内分别使用NbTi、Nb₃Sn和YBCO三种超导材料绕制而成;在直径500mm的测试区域范围内产生最高达13.22T的背景磁场,均匀性不低于95%。介绍了磁体线圈主要设计参数,用有限元软件完成电磁、结构分析。结果表明,设计合理可靠,能够满足导体测试装置的需求。     

Redesign of a soft conductive rubber strip electrode for measurement of surface resistance according to IEC 60079-32-2 within the context of the PTB Ex Proficiency Testing Scheme

To ensure worldwide quality and homogeneity in the field of explosion protection, not only uniform rules in the form of IEC standards but also the active participation in interlaboratory comparisons are necessary. The “PTB Ex Proficiency Testing Scheme” is the first global proficiency testing program of its kind in the field of explosion protection. It serves as proof of competence and provides laboratories with a complete system for their own performance evaluation.In 2015, the program “Electrostatic Charge - Test Round 2015” was launched within the PTB Testing Scheme. The participants of the program performed surface resistance and transferred charge tests according to IEC 60079-0 and IEC 60079-32-2 on various types of test samples. The new standard IEC 60079-32-2 proposes different kinds of electrodes for the user, such as conductive silver paint electrodes, soft conductive rubber strip electrodes on spring-mounted metal tongues or conductive foam strips mounted on an insulating support, depending on the geometry of the sample. These different types of electrodes as well as the construction latitude for each electrode could lead to deviations between the results of different test laboratories due to better or worse electrode contact with the test sample.Therefore, the proficiency team and electrostatic experts at PTB decided to design an accurate and user-friendly electrode which meets the requirements of IEC 60079-32-2. This paper provides information about the electrodes' design as well as the results of comparable measurements.     

Möbius strip versus linear and cyclic polyacenes: a Hückel and semiempirical investigation

The electronic structure of finite and infinite linear, cyclic and M?bius strip polyacenes has been investigated by adopting Hückel and semiempirical schemes. Using the Hückel approach, it turns out that the M?bius belting process modifies the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap in such a way its evolution with chain length is similar to the linear polyacenes rather than their cyclic analogs. These results are corroborated at the Austin model 1 (AM1) level, where the geometry relaxation effects are taken into account. The optimized AM1 structures show that the M?bius defect is localized and extends over a third of the ring. With respect to the Hückel approach, accounting for geometry distortion at the AM1 levels results in an increase in the HOMO–LUMO gap of the M?bius strip relative to the linear and cyclic finite-size structures. On the other hand, when including electron-hole correlation at the configuration interaction singles/Zerner's intermediate neglect of differential overlap level the behavior with system size of the first excitation energy of cyclic and M?bius polyacenes differs from their linear analogs and leads to smaller singlet excitation energies. Received: 20 September 2000 / Accepted: 21 September 2000 / Published online: 28 February 2001     

Experimental study on employing flexural wave measurement to characterize delamination in beams

Flexural wave analysis has been applied to the detection and quantitative assessment of delaminations in structures. To validate analytical methods, an extensive experimental study is conducted. The test beam is of infinite length, and a delamination of prescribed length is artificially created at predetermined locations. Using two different types of excitations and measurements, the effect on the beam response of delamination length and depth, the beam material, excitation frequencies and location of excitation are analyzed. A technique for predicting the location and size of the delamination is also proposed. On each case, good comparison between analytical and experimental results is achieved.