Copolymer architecture effects on the morphology and surface performance of epoxy thermosets containing fluorinated block copolymers

The architecture effects on phases and surface enrichment behaviors of epoxy nanocomposites containing fluorinated block copolymers are investigated by the incorporation of two novel copolymers composed of poly (2, 2, 2‐trifluoroethyl methacrylate) (PTFEMA) and poly (ε‐caprolactone) (PCL), PCL‐b‐PTFEMA and PTFEMA‐b‐PCL‐b‐PTFEMA, with identical molecular weight and composition. These fluorinated copolymers in epoxy display distinguished self‐assembled structures, as evidenced by dynamic laser scattering and scanning electron microscopy measurements. Static contact angle detection suggests that the nanocomposites display an obvious improvement in surface water repellency and a reduction in surface free energy. The enhancement in surface hydrophobicity is attributed to the enrichment of PTFEMA blocks at the nanocomposite surface and to the formation of the specific surface morphology, as confirmed by atomic force microscopy. The different architectures of the two block copolymers give rise to differences in phase‐structures, and the ultimate surface performances of composites. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1037–1045     

The Application of TD/GC/NICI–MS with an Al2O3-PLOT-S Column for the Determination of Perfluoroalkylcycloalkanes in the Atmosphere

A modified method for the quantitative determination of atmospheric perfluoroalkylcycloalkanes (PFCs) using thermal desorption coupled with gas chromatography and detection by negative ion chemical ionization–mass spectrometry was developed. Using an optimized analytical system, a commercially available Al₂O₃ porous layer open tubular (PLOT) capillary column (30 m × 0.25 mm) deactivated with Na₂SO₄ was used for separation of PFCs. Improvements in the separation of PFCs, the corresponding identification and the limit of detection of PFCs using this method and column are presented. The method was successfully applied to determine the atmospheric background concentrations of a range of PFCs from a number of samples collected at a rural site in Germany. The results of this study suggest that the method outlined using the Al₂O₃-PLOT-S capillary column has good sensitivity and selectivity, and that it can be deployed in a routine laboratory process for the analysis of PFCs in the future research work. In addition, the ability of this column to separate the isomers of one of the lower boiling PFCs (perfluorodimethylcyclobutane) and its ability to resolve perfluoroethylcyclohexane offer the opportunity for single-column analysis for multiple PFCs.     

Dual Palladium(II)/Tertiary Amine Catalysis for Asymmetric Regioselective Rearrangements of Allylic Carbamates

The streamlined catalytic access to enantiopure allylic amines as valuable precursors towards chiral β‐ and γ‐aminoalcohols as well as α‐ and β‐aminoacids is desirable for industrial purposes. In this article an enantioselective method is described that transforms achiral allylic alcohols and N‐tosylisocyanate in a single step into highly enantioenriched N‐tosyl protected allylic amines via an allylic carbamate intermediate. The latter is likely to undergo a cyclisation‐induced [3,3]‐rearrangement catalysed by a planar chiral pentaphenylferrocene palladacycle in cooperation with a tertiary amine base. The otherwise often indispensable activation of palladacycle catalysts by a silver salt is not required in the present case and there is also no need for an inert gas atmosphere. To further improve the synthetic value, the rearrangement was used to form dimethylaminosulfonyl‐protected allylic amines, which can be deprotected under non‐reductive conditions.     

Identification of antibacterial and antioxidant constituents of the essential oils of Cynanchum chinense and Ligustrum compactum

The aim of this research was to determine the chemical composition, antioxidant and antibacterial properties of the essential oils from Cynanchum chinense and Ligustrum compactum and isolation of antioxidant and antibacterial constituents from the essential oils. Thirty-eight components were identified in essential oils. Based on bioactivity-guided fractionation, guaiacol, linalool and 2-phenylethanol were isolated and identified as active constituents. Both L. compactum flower oil and 2-phenylethanol showed high antibacterial performance, with inhibition zone from 22.8 ± 0.8 to 11.9 ± 2.0 mm at highest concentration, and minimum inhibitory concentration values ranging from 0.25% to 1%. In both DPPH and ABTS assay, the active constituent guaiacol (IC₅₀ = 4.15 ± 0.72 and 9.12 ± 0.98 μg mL^? 1, respectively) exhibited high antioxidant activity, and the oils showed moderate antioxidant activity. These results indicate potential efficacy of active constituents and essential oils of L. compactum and C. chinense to control food-borne pathogenic and spoilage bacteria.     

Synthesis and antifungal activity of chalcone derivatives

In the present study, using chalcone as a lead compound, a series of its derivatives (compounds 1–30) were designed and synthesised. Their activity of anti-pathogenic fungi of plants has been evaluated. It is found that these compounds have good antifungal activity against Sclerotinia sclerotiorum, Helminthosprium maydis, Botrytis cinerea, Rhizoctonia solani and Gibberella zeae. Among them, the inhibition of growth for compound 30 against S. sclerotiorum showed 89.9%, with the median effective concentrations (EC₅₀) of 15.4 μg mL^? 1. The inhibition of growth for compounds 28, 29 and 30 at a concentration of 100 μg mL^? 1 against H. maydis is 90.3%, 90.7% and 91.1%, with EC₅₀ of 15.1, 18.3 and 18.1μg mL^? 1, respectively.     

Preparation of 17β‐estradiol‐imprinted material by surface‐initiated atom transfer radical polymerization and its application

A novel 17β‐estradiol molecularly imprinted polymer was grafted onto the surface of initiator‐immobilized silica by surface‐initiated atom transfer radical polymerization. The resulting molecularly imprinted polymer was characterized by elemental analysis and thermogravimetric analysis. The binding property of molecularly imprinted polymer for 17β‐estradiol was also studied with both static and dynamic methods. The results showed that the molecularly imprinted polymer possessed excellent recognition capacity for 17β‐estradiol (180.65 mg/g at 298 K), and also exhibited outstanding selectivity for 17β‐estradiol over the other competitive compounds (such as testosterone and progesterone). Then, the determination of trace 17β‐estradiol in beef samples was successfully developed by using molecularly imprinted polymer solid‐phase extraction coupled with high‐performance liquid chromatography. The limit of detection was 0.25 ng/mL, and the amount of 17β‐estradiol in beef samples was detected at 2.83 ng/g. This work proposed a sensitive, rapid, reliable, and convenient approach for the determination of trace 17β‐estradiol in complicated beef samples.     

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.     

Highly stable and reusable imprinted artificial antibody used for in situ detection and disinfection of pathogens

Sandwich ELISA methods have been widely used for biomarker and pathogen detection because of their high specificity and sensitivity. However, the main drawbacks of this assay are the cost, the time-consuming procedure for the isolation of antibodies and their poor stability. To overcome these restrictions, we herein fabricated artificial antibodies based on imprinting technology and developed a sandwich ELISA for pathogen detection. Both the capture and detection antibodies were obtained via an in situ method, with simplicity, rapidity and low cost. The peroxidase mimics, the CeO₂ nanoparticles, as signal generators were integrated with the detection antibody. The fabricated artificial antibodies exhibited not only natural antibody-like binding affinities and selectivities, but also superior stability and reusability. The detection limit was about 500 CFU mL^–1, which is much lower than that of traditional ELISA methods (10⁴ to 10⁵ CFU mL^–1). Furthermore, the capture antibody can disinfect pathogens in situ.     

A New Fluorescence Turn-On Probe for Aluminum(III) with High Selectivity and Sensitivity,and its Application to Bioimaging

The development of novel selective probes with high sensitivity for the detection of Al³⁺ is widely considered an important research goal due to the importance of such probes in medicine, living systems and the environment. Here, we describe a new fluorescent probe, N′-(4-diethylamino-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (1), for Al³⁺. Probe 1 was evaluated in a solution of acetonitrile/water (1:1 v/v). Compared with previously reported probes for Al³⁺, probe 1 can be synthesized easily and in high yield. A Job plot confirmed that probe 1 is able to complex Al³⁺ in a 1:1 ratio, and the binding constant was determined to be 4.25×10⁸ m⁻¹. Moreover, the detection limit was as low as 6.7×10⁻⁹ m, suggesting that probe 1 has a high sensitivity. Common coexistent metal ions, such as K⁺, Co²⁺, Ca²⁺, Ba²⁺, Ni²⁺, Pb²⁺, Hg²⁺, Ce²⁺, Zn²⁺, Cd²⁺, Fe³⁺, showed little or no interference in the detection of Al³⁺ in solution, demonstrating the high selectivity of the probe. Finally, the ability of probe 1 to act as a fluorescent probe for Al³⁺ in living systems was evaluated in Gram-negative bacteria, Escherichia coli, and confocal laser scanning microscopy confirmed its utility. The results of this study suggest that 1 has appropriate properties to be developed for application as a fluorescent probe of Al³⁺ for use in biological studies.