Improving MCM‐41 as a Nitrosamines Trap through a One‐Pot Synthesis

Copper oxide was incorporated into MCM‐41 by a one‐pot synthesis under acidic conditions to prepare a new mesoporous nitrosamines trap for protection of the environment. The resulting composites were characterized by XRD, N₂ adsorption–desorption, and H₂ temperature‐programmed reduction techniques, and their adsorption capabilities were assessed in the gaseous adsorption of N‐nitrosopyrrolidine (NPYR). The adsorption isotherms were consistent with the Freundlich equation. The copper salt was deposited onto MCM‐41 during the evaporation stage and was fixed on the host in the calcination process that followed. MCM‐41 was able to capture NPYR in air below 373 K but not at 453 K. Loading of copper oxide on MCM‐41 greatly improved its adsorption capability at elevated temperatures. The influence of the incorporation of copper into MCM‐41 samples and the adsorption behavior of these samples are discussed in detail.     

Nafion/Poly(sodium 4‐styrenesulfonate) Mixed Coating Modified Bismuth Film Electrode for the Determination of Trace Metals by Anodic Stripping Voltammetry

To improve the reproducibility, stability, and sensitivity of bismuth film electrode (BiFE), we studied the performances of a mixed coating of two cation‐exchange polymers, Nafion (NA) and poly(sodium 4‐styrenesulfonate) (PSS), modified glassy carbon BiFE (GC/NA‐PSS/BiFE). The characteristics of GC/NA‐PSS/BiFE were investigated by scanning electron microscopy and cyclic voltammetry. Various parameters were studied in terms of their effect on the anodic stripping voltammetry (ASV) signals. Under optimized conditions, the limits of detection were 71 ng L^?1 for Cd(II) and 93 ng L^?1 for Pb(II) with a 10 min preconcentration. The results exhibited that GC/NA‐PSS/BiFE can be a reproducible and robust tool for monitor of trace metals by ASV rapidly and environmentally friendly, even in the presence of surface‐active compounds.     

Two New Triterpene Lactones from the Stems of Kadsura polysperma

Two new triterpene lactones, polysperlactones A ( 2 ) and B ( 3 ), were isolated from the stems of Kadsura polysperma, together with the known compounds heteroclitalactone D ( 1 ) and schisanlactone E ( 4 ). Their structures were elucidated by spectroscopic methods, including 2D‐NMR and HR‐MS techniques. The configuration of 1 was confirmed by X‐ray analysis. Compounds 2 and 3 are members of a rare class of 3,4‐secolanostane metabolites with ring‐expanded or cyclized structures, respectively.     

Microwave-assisted solvent-free synthesis of substituted 2-quinolones

A rapid and efficient method for the preparation of a variety of substituted 2-quinolones has been developed through the reactions of o-aminoarylketones with ester compounds containing a reactive α-methylene moiety in the presence of a catalytic amount of cerium chloride heptahydrate under solvent-free conditions in high yields. The rate and yield of the reaction are considerably improved by employing microwave irradiation.     

A novel three-component reaction for the synthesis of new 4-azafluorenone derivatives

Reaction of arylidenemalononitriles, 1,3-indanedione, and mercaptoacetic acid or 4-methylbenzenethiol is successfully carried out using microwave heating. It is an efficient and promising synthetic strategy to build the indenopyridine skeleton.     

Studies on Chemical Constituents of Polygonum Ciliinerve Ohwi

Three new apianen lactones Maomailiaoine I ( 1 ), Maomailiaoine II ( 2 ) and Maoimaliaoine III ( 3 ), together with one known apianen lactone, five known flavonoids and three other known compounds were isolated from Polgonum ciliinerve Ohwi. Their structures were deduced from spectroscopic methods and 2D NMR techniques.     

Concise Synthesis and Antimicrobial Activities of New Substituted 5‐Isoxazolpenicillins

The synthesis of a series of new 5‐isoxazolpenicillins is described, which were obtained by coupling substituted isoxazoles with 6‐APA. Concise large‐scale synthesis of 3,5‐disubstituted isoxazoles by 1,3‐dipolar cycloaddition using copper(I) as catalyst was also investigated. Representative compounds were assayed for antimicrobial activities, showing satisfactory antimicrobial activities against Gram‐negative bacteria.     

A facile one‐pot synthesis of 2‐amino‐4‐arylbenzo[h]quinoline‐3‐carbonitrile derivatives without catalyst

A series of 2‐amino‐4‐arylbenzo[h]quinoline‐3‐carbonitrile derivatives were synthesized by one‐pot condensation of aromatic aldehyde, a‐naphthylamine and malononitrile in ethanol without catalyst. This multicomponent reaction has the notable advantages of short route, high yield and convenient operation.     

Investigation of the Gel Effect in Reactive Extrusion Processes for Free Radical Polymerization

The gel effect in the reactive extrusion process for free radical polymerization in a closely intermeshing co‐rotating twin screw extruder was investigated. First the reaction kinetic model was constructed mainly on the basis of entanglement theory. Next, numerical calculation expressions for the initiator and monomer concentrations, monomer conversion, average molecular weight and apparent viscosity were deduced. Finally, the evolution of the above variables were shown and discussed for the example of butyl methacrylate. The simulated results of the monomer conversion are in good agreement with experimental results.

     

Towards efficient electromagnetic interference shielding performance for polyethylene composites by structuring segregated carbon black/graphite networks

An electromagnetic interference (EMI) shielding composite based on ultrahigh molecular weight polyethylene (UHMWPE) loaded with economical graphite-carbon black (CB) hybrid fillers was prepared via a green and facile methodology, i.e., high-speed mechanical mixing combined with hot compression thus avoiding the assistance of the intensive ultrasound dispersion in volatile organic solvents. In this composite, the graphite-CB hybrid fillers were selectively distributed in the interfacial regions of UHMWPE domains resulting a typical segregated structure. Thanks to the specific morphology of segregated conductive networks along with the synergetic effect of large-sized graphite flakes and small-sized CB nanoparticles, a low filler loading of 7.7 vol% (15 wt%) yielded the graphite-CB/UHMWPE composites with a satisfactory electrical conductivity of 33.9 S/m and a superior shielding effectiveness of 40.2 dB, manifesting the comparable value of the pricey large-aspect-ratio carbon nanofillers (e.g., carbon nanotubes and graphene nanosheets) based polymer composites. More interestingly, with the addition of 15 wt% graphite-CB (1/3, W/W) hybrid fillers, the tensile strength and elongation at break of the composite reached 25.3 MPa and 126%, respectively; with a remarkable increase of 58.1% and 2420% over the conventional segregated graphite/UHMWPE composites. The mechanical reinforcement could be attributed to the favor of the small-sized CB particles in the polymer molecular diffusion between UHMWPE domains which in turn provided a stronger interfacial adhesion. This work provides a facile, green and affordable strategy to obtain the polymer composites with high electrical conductivity, efficient EMI shielding, and balanced mechanical performance.