Biosensor immunoassay for the screening of dioxin-like polychlorinated biphenyls in retail fish

Dioxin-like polychlorinated biphenyls (DL-PCBs) often make up the majority of the toxic equivalent (TEQ) contribution of dioxins found in fish samples. For the purpose of making risk assessments, it is therefore important to develop screening methods for determining TEQ concentrations of DL-PCBs in retail fish. We have developed a rapid biosensor immunoassay (BIA) for DL-PCBs that uses a surface plasmon resonance sensor (Biacore 3000). The BIA is highly specific for 2,3',4,4',5-pentachlorobiphenyl (PCB 118) that is generally the most abundant DL-PCB isomer found in fish. The fish extracts were first cleaned up on a multilayer silica gel column followed by an alumina column, then subjected to the assay. The quantitative limit of the assay was 1 ng PCB 118 per gram of tested sample. Dilution and recovery tests using purified fish extracts suggested that the matrix effect was minimized in the assay by diluting the analyzed samples. The assay results for retail fish samples (n=7) agreed well with those obtained by an enzyme-linked immunoassay (ELISA) using the same monoclonal antibody: ELISA has been already validated for determining DL-PCBs in fish samples, so BIA performs well in this analysis. Finally, BIA results for the TEQ concentrations of DL-PCBs in retail fish samples (n=10) correlated well with those obtained by high-resolution gas chromatography coupled to high-resolution mass spectrometry (r=0.89). Our method is therefore useful for screening retail fish to determine the TEQ concentrations of DL-PCBs.     

Differences between collisionally activated and electron-transfer dissociations found for CH(2)X(2)(X = Cl, Br, and I) by using alkali-metal targets

High-energy collisionally activated dissociation (HE-CAD) and high-energy electron- transfer dissociation (HE-ETD) on collisions with alkali-metal targets (Cs, K, and Na) were investigated for CH(2)X(2) (+) (X = Cl, Br, and I) ions by tandem mass spectrometry (MS/MS). In the HE-CAD spectra observed, peaks associated with CH(2)X(+) ions formed by a loss of a halogen atom are always predominant regardless of precursor ions and target metals. The observation of the predominant CH(2)X(+) ions is explained by the lowest energy levels of the fragments of CH(2)X(+) + X among the possible fragment energy levels and internal-energy distribution in HE-CAD. In the charge-inversion spectra, relative peak intensities of the negative ions formed by HE-ETD strongly depend on the precursor ions and the target metals. While the CHCl(2) (-) ion was predominant in the spectra of CH(2)Cl(2) (+) regardless of target species, the most intense peaks in those of CH(2)Br(2) (+) and CH(2)I(2) (+) were ascribed to either Br(-) or CH(2)Br(-) and either I(-) or I(2) (-), respectively, depending on the target metals. The dependence of the relative intensities of the fragment ions by HE-ETD on the precursor ions and target species are discussed on the basis of the energy levels of the neutral fragments and the narrow internal-energy distribution resulting from the near-resonant neutralization. It was demonstrated that HE-ETD using the alkali-metal targets provided rich information on the dissociation of the neutral species.     

Redox-Neutral Tetrafluoroethylation of Aryl Alkynes with 1,1,2,2-Tetrafluoroethane Sulfonic Acid Leading to α-Tetrafluoroethylated Acetophenones

The redox-neutral tetrafluoroethylation of alkynes with 1,1,2,2-tetrafluroroethanesulfonic acid (TFESA) and azobis(isobutyronitrile) (AIBN) proceeds via the formation of vinyl tetrafluoroethanesulfonates followed by a radical tetrafluoroethylation. Experimental and theoretical results support an intermolecular reaction.     

Two-photon actuation of crosslinked liquid-crystalline polymers utilizing energy transfer system

ABSTRACT

We prepared crosslinked azotolane liquid-crystalline polymer (LCP) films doped with a stilbene derivative (two-photon chromophore) utilizing an interpenetrating polymer network (IPN) structure. The IPN films bend toward the light source upon irradiation with femtosecond laser pulses at 600 nm, which can excite the stilbene derivative by two-photon absorption. The bending speed of the IPN films increases with the square of the laser pulse intensity, which is compelling evidence for the two-photon processes.     

Preparation and Determination of 4,8-Diethylbenzo-[1,2- d :4,5- d ′]bis[1,2,3]trithiole Dication [DEBBT(2+)]

Abstract

Preparation and detection of DEBBT(2+)-? S and DEBBT(2+)-? T are reported.     

Wavelet‐based data compression for flow simulation on block‐structured Cartesian mesh

A data compression method based on image encoding techniques is presented for a flow simulation data set. An input flow field data set is converted into the octree structure by discrete wavelet transform, and then quantized finely or coarsely depending on its importance in the flow field. Embedded zerotree wavelet encoding as the image encoding technique and entropy encoding reduce the data size by making use of the octree structure created previously. The present compression method is incorporated in a block‐structured Cartesian mesh method called Building‐Cube method. The Building‐Cube method gives not only good performance in the flow simulation but also consistency with the embedded zerotree wavelet encoding in the data compression. Three compression cases for incompressible and compressible flow simulations, including a large‐scale simulation with O(10 ⁸) mesh points, demonstrate that the present compression method gives both high compression ratios and good qualities of compressed data. Copyright © 2013 John Wiley & Sons, Ltd.     

Copolymerization of ethylene with 1,1‐disubstituted olefins catalyzed by ansa‐(fluorenyl)(cyclododecylamido)dimethyltitanium complexes

A series of titanium complexes with ansa‐(fluorenyl)(cyclododecylamido) ligands, Me₂Si(η³‐R)(N‐c‐C₁₂H₂₃)TiMe₂ [R = fluorenyl ( 5 ), 2,7‐^tBu₂fluorenyl ( 6 ), 3,6‐^tBu₂fluorenyl ( 7 )], was synthesized. The crystal structure of complex 6 revealed η³‐coordination of the fluorenyl moiety to the metal. Upon activation with trialkylaluminum‐free modified methylaluminoxane, complexes 5 – 7 as well as the corresponding ^tBu amide complexes, Me₂Si(η³‐R)(N^tBu)TiMe₂ [R = fluorenyl ( 2 ), 2,7‐^tBu₂fluorenyl ( 3 ), 3,6‐^tBu₂fluorenyl ( 4 )], were adopted as the catalysts for the copolymerization of ethylene (E) and isobutylene (IB). Among these complexes, complex 6 was found to achieve the highest IB incorporation to produce alternating E‐IB copolymers. Complex 6 system also achieved copolymerization of E and limonene. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013