Delay-dependent fault detection for switched linear systems with time-varying delays—the average dwell time approach

In this paper, the fault detection problem is investigated for a class of discrete-time switched linear systems with time-varying delays. The main purpose is to design a fault detection filter such that, for all unknown inputs, control inputs and time delays, the estimation error between the residual and fault is minimized in an exponential way. The fault detection problem is converted into an exponential H_∞ filtering problem. By using a newly constructed Lyapunov functional and the average dwell time scheme, a novel delay-dependent sufficient condition for the solvability of this problem is established in terms of linear matrix inequalities (LMIs). A numerical example is given to demonstrate the effectiveness of the developed theoretical results.     

Synthesis and fluorescence properties of dysprosium‐coordinated with high‐Tg polyaryletherketones containing carboxyl side groups

A series of novel dysprosium coordination polymers were synthesized using new high‐T_g carboxyl‐containing polyaryletherketones (PEKs) as macromolecular ligands and a small molecule, 1,10‐phenanthroline, as co‐ligand. The FTIR, WAXD, and UV–Vis results indicated that the dysprosium ions were coordinated simultaneously with carboxyl group of PEKs and 1,10‐phenanthroline, and homogeneously distributed along the polymer backbone. These obtained dysprosium coordination polymers showed excellent film‐formation properties. Moreover, all the dysprosium coordination polymers could exhibit the intense characteristic emission of dysprosium ions under UV excitation. Meanwhile, the emission intensity increased with increasing dysprosium ion content, and no obvious fluorescence quenching happened at the Dy³⁺ ion content up to 10.71 wt%, which was attributed to the very rigid structure of PEK and synergistic coordination effect of PEK and 1,10‐phenanthroline. Copyright © 2009 John Wiley & Sons, Ltd.     

A Novel Nanoparticle‐Based Disposable Electrochemical Immunosensor for Diagnosis of Exposure to Toxic Organophosphorus Agents

A novel disposable electrochemical immunosensor for highly selective and sensitive detection of organophosphorylated butyrylcholinesterase (OP‐BChE), a specific biomarker for exposure to toxic organophosphorus agents, is presented. In this new approach, zirconia nanoparticles (ZrO₂) were employed to selectively capture the OP moiety of OP‐BChE adducts, followed by quantum dot (QD)‐tagged anti‐BChE antibodies for amplified quantification. The captured CdSe‐QD tags can be sensitively detected by stripping voltammetry using an in situ bismuth‐plating method. The OP agent, diisopropylfluorophosphate (DFP), was selected to prepare OP‐BChE adducts in various matrices. The formation of OP‐BChE adducts in plasma sample was confirmed using mass spectroscopy. The developed electrochemical immunosensor demonstrates a highly linear voltammetric response over the range of 0.1 to 30 nM OP‐BChE, with a detection limit of 0.03 nM (based on signal/noise = 3), coupled with a good reproducibility (relative standard deviation 4.5%). Moreover, the immunosensor has been validated with biomonitoring of OP‐BChE adducts in the plasma samples. This novel nanoparticle‐based electrochemical immunosensor thus provides an alternative way for designing a sensitive and cost‐effective sensing platform for on‐site screening/evaluating exposure to a variety of OP agents.     

A New Rearrangement Reaction of 2-Phenyl Substituted Benzothiazepine with Ethoxycarbonyl Carbene─Mechanism of the Reaction and Structure of the Product

Intheprevi0usaFticlesl-2wehavereportedthatthereacti0n0fbenz0diazepinewithethoxycarbonylcarbenemayobtainnormal[2 l]cycIoadditi0npr0ductsregardlessthe2-substitUentismethyl0rphenyl.Howeverunderthesamec0nditi0nsthereaction0fbenzothiazepinewithethoxycarbonylcarbeneunderwentrearrangementreacti0n.Forexample,whenthe2-substituentismethyl,thereacti0nofbenzothiazepinewithethoxycarbonylcarbenegivearing-openingproductIIatroomorhightemperature'.Whenthe2-substituentisphenyl,weunexpectedlyfoundan0thernewrea…     

快速去除硝酸和亚硝酸对氢化物发生原子荧光法测定砷的干扰

为了避免繁琐、耗时的"赶酸"操作, 研究了尿素结合NaOH除去微波消解液中过量的HNO3和HNO2的干扰,继用L-半胱氨酸在低酸度下将As(Ⅴ)还原为As(Ⅲ)的样品消化和预还原方法.用氢化物发生-原子荧光法准确、快速地测定了食品中痕量砷.该方法的检出限为0.03 μg/L;连续11次测定4 μg/L As(Ⅲ)标准溶液的相对标准偏差为1.6%; 测定国家标准物质的结果与标准值非常吻合.     

Thermosensitive graphene nanocomposites formed using pyrene‐terminal polymers made by RAFT polymerization

Thermosensitive graphene‐polymer composites have been prepared by attaching poly(N‐isopropylacrylamide) (PNIPAAm) onto the basal plane of graphene sheets via π‐π stacking. Pyrene‐terminated PNIPAAm was synthesized using reversible addition fragmentation chain transfer (RAFT) polymerization via a pyrene‐functional RAFT agent. Aqueous solutions of the graphene‐polymer composites were stable and thermosensitive. The lower critical solution temperature (LCST) of pyrene‐terminated PNIPAAm was measured to be 33 °C. When the pyrene‐functional polymer was attached to graphene the resultant composites were also thermosensitive in aqueous solutions exhibiting a reversible suspension behavior at 24 °C. Atomic force microscopy (AFM) analysis revealed that the thickness of a graphene‐PNIPAAm (M_n: 10,000 and PDI: 1.1) sheet was ～5.0 nm. The surface coverage of polymer chains on the graphene basal plane was calculated to be 7.2 × 10^?11 mol cm^?2. The graphene‐PNIPAAm composite material was successfully characterized using X‐ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR‐IR) spectroscopy, and thermogravimetric analysis (TGA). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 425–433, 2010     

Structure elucidation of four prenylindole derivatives from Streptomyces sp. isolated from Ailuropoda melanoleuca feces

Four new prenylindole derivatives, (R)‐6‐(2,3‐dihydroxy‐3‐methylbutyl)indole (1), (R)‐6‐(2,3‐dihydroxy‐3‐methylbutyl)indolin‐2‐one (2), and an unseparated mixture of (Z)‐6‐(4‐hydroxy‐3‐methylbut‐2‐en‐1‐yl)indolin‐2‐one (3a) and (E)‐6‐(4‐hydroxy‐3‐methylbut‐2‐en‐1‐yl)indolin‐2‐one (3b) with a ratio of 3 : 2, were isolated from the culture broth of a streptomycete isolated from Ailuropoda melanoleuca feces. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic techniques. The absolute configuration of 1 was determined by Mosher's method. Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous determination of phthalates and adipates in human serum using gas chromatography–mass spectrometry with solid‐phase extraction

A gas chromatography–mass spectrometry assay was developed and validated for the simultaneous determination of phthalates and adipates in human serum. The phthalates and adipates studied were dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzylbutyl phthalate, di‐2‐ethylhexyl phthalate, di‐n‐octyl phthalate, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis(2‐butoxyethyl) adipate and di‐2‐ethylhexyl adipate, with diisooctyl phthalate as internal standard. The extraction and cleaning up procedure was carried out with solid‐phase extraction cartridges containing dimethyl butylamine groups, which showed extraction efficiencies over 88% for each analyte and the internal standard. The calibration curves obtained were linear with correlation coefficients greater than 0.98. For all analytes, the assay gave CV% values for intra‐day precision from 4.9 to 13.3% and mean accuracy values from 91.4 to 108.4%, while inter‐day precision was 5.2–13.4% and mean accuracy 91.0–110.2%. The limits of detection for the assay of phthalates and adipates were in the range 0.7–4.5 ng/mL. The method is simple, sensitive and accurate, and allows for simultaneous determination of nanogram levels of phthalates and adipates in human serum. It was successfully applied to an investigation on the level of phthalates and adipates in a non‐occupationally exposed population.