全氟辛烷磺酸水样的前处理技术及固相微萃取剂的研究进展

全氟辛烷磺酸及其盐(PFOS)广泛应用于纺织品、皮革、家具等上千种工业和日用生活用品的生产中,由于具有多脏器毒性,被列为继多氯联苯、有机氯农药和二噁英之后的又一种新型持久性有机污染物.因此,PFOS的准确监测对环境PFOS污染的预警预报具有重要的意义.PFOS在样品中含量低,因此样品前处理技术是准确分析的关键.本文对目...     

Strong convergence for sequences of asymptotically almost negatively associated random variables

In this article, the complete convergence for sequences of asymptotically almost negatively associated (AANA) random variables is studied. As applications, the Baum–Katz-type theorem, Hsu–Robbins-type theorem and Marcinkiewicz–Zygmund strong law of large numbers for sequences of AANA random variables are obtained.     

剩余为几乎2-正则的6-圈系

Let Kn be a complete graph on n vertices. In this paper, we find the necessary conditions for the existence of a 6-cycle system of Kn - L for every nearly 2-regular leave L of Kn. This condition is also sufficient when the number of vertices of L is n - 4.     

Characterization of gel grown iron‐manganese‐cobalt ternary levo‐tartrate crystals

In the present investigation, iron–manganese–cobalt ternary levo‐tartrate crystals of different compositions have been grown by single‐diffusion gel growth technique in silica hydrogel medium. The metallic composition in the crystals was estimated by EDAX. The coloration of the crystals changed with composition of metallic content. The powder XRD study suggested the crystalline nature and indicated the presence of some extra phases. The grown crystals were characterized by FT‐IR spectroscopy, TGA, dielectric and Vibrating Sample Magnetometer (VSM) studies. The FT‐IR study suggested the presence of O‐H, C=O, C‐O and metal‐oxygen bonds. The effect of composition of metallic content was observed in certain absorption regions in FT‐IR spectra. The thermal stability of the crystals was studied by thermogravimetry and the kinetic and thermodynamic parameters of dehydration were calculated. The effect of composition of ternary levo‐tartrate was observed in dielectric study. The dielectric study was carried out in the frequency range of applied field from 500 Hz to 1 MHz. The variations in dielectric constant, dielectric loss, a.c. resistivity and a.c. conductivity with frequency of applied field were studied. VSM study suggested that all crystals were of paramagnetic nature. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stochastic nanopore sensors for the detection of terrorist agents: Current status and challenges

Nanopore stochastic sensor works by monitoring the ionic current modulations induced by the passage of analytes of interest through a single pore, which can be obtained from a biological ion channel by self-assembly or artificially fabricated in a solid-state membrane. In this minireview, we overview the use of biological nanopores and artificial nanopores for the detection of terrorist agents including explosives, organophosphorus nerve agents, nitrogen mustards, organoarsenic compounds, toxins, and viruses. We also discuss the current challenge in the development of deployable nanopore sensors for real-world applications.     

Two-step stacking in capillary zone electrophoresis featuring sweeping and micelle to solvent stacking: I. Organic cations

Two-step stacking of organic cations by sweeping and micelle to solvent stacking (MSS) in capillary zone electrophoresis (CZE) is presented. The simple procedure involves hydrodynamic injection of a micellar sodium dodecyl sulfate solution before the sample that is prepared without the micelles. The micelles sweep and transport the cations to the boundary zone between the sample and CZE buffer. The presence of organic solvent in the CZE buffer induces the second stacking step of MSS. The LODs obtained for the four beta blocker and two tricyclic antidepressant test drugs were 20-50 times better compared to typical injection.     

A stainless steel multi‐well plate (SS‐MWP) for high‐throughput Raman analysis of dilute solutions

The use of Raman spectroscopy for the qualitative and quantitative analysis of dilute aqueous solutions is of interest to the biopharmaceutical manufacturing sector. However, the inherent weakness of the Raman effect, coupled with spectral variability due to spurious signals from sample holders, can produce significant problems for chemometric‐based high‐throughput assays. Therefore, there is a need for a multi‐well sample holder that ensures robust and repeatable measurements, in particular from dilute aqueous solutions such as cell culture media. Here we demonstrate the efficacy of a novel, electropolished, stainless steel multi‐well plate (SS‐MWP) sample holder with 96 wells for dilute aqueous solution analysis. A comprehensive study of the spectroscopic behaviour was carried out and comparisons made with multi‐well plates fabricated from polystyrene, polypropylene, and aluminium. A key factor in the validation studies is the use of intrinsically weak Raman scattering systems, e.g. water and dilute glucose solutions. The data collected show that the SS‐MWPs are much superior in terms of robustness, resistance to chemical attack, and measurement reproducibility and as such are the ideal sample holders for Raman analysis of dilute solutions. Copyright © 2010 John Wiley & Sons, Ltd.     

Physical properties of the probe electrospray ionization (PESI) needle applied to the biological samples

Probe electrospray ionization (PESI) is a recently developed technique that uses a fine solid needle as a probe for sampling biological materials. In this study, we quantified the volume of liquid sample picked up by the solid needle with the tip diameter of ～700 nm and the apex angle of ～60°. The amounts of low‐viscosity samples (rat urine) loaded on the tip of the needle by a single stroke were 0.35 ± 0.09 pl. Interestingly, the amount of liquid adhered to the tip did not significantly depend on the protein concentration, but viscosity and surface tension of the sample. Under these conditions, we successfully obtained mass spectra for each biological sample. Copyright © 2009 John Wiley & Sons, Ltd.