Advanced Materials Research Vols. 236-238

Abstract: The cure kinetics of epoxy/epoxy-grafted nano-aluminum oxide using 4, 4'-diaminodiphenylsulphone (DDS) as the curing agent was studied by nonisothermal differential scanning calorimetry (DSC) at different heating rates. The activation energy (Ea) was determined by Flynn-Wall-Ozawa method, and kinetic model was predicted by Málek method. The Ea values of epoxy/nano-aluminum oxide/DDS systems are generally higher than those of epoxy /DDS. These imply that the addition of nano-aluminum oxide would inhibit the chain mobility of the epoxy resins. Furthermore, autocatalytic model was found to be appropriate to describe the kinetics of above mentioned reactions. The predicted curves fit well with the experimentally obtained curves.

Abstract: Mechanical properties of polyurethane coating were improved by multi-walled carbon nanotubes (MWNTs) via in situ polymerization and blending polymerization. Fourier transform infrared spectroscopy (FT-IR) measurement was employed to assess the influence of acid treatment on MWNTs. Mechanical properties analysis of polyurethane coatings including tensile strength, elastic modulus, hardness, flexibility, impact resistance were employed to assess the improvement of mechanical properties of polyurethane coating by MWNTs. The results indicated that MWNTs could improve the mechanical properties of polyurethane coatings, and the improvement of polyurethane coatings by MWNTs via in situ polymerization were better than via blending polymerization, and the improvement of polyurethane coatings by acid-treated MWNTs were better than by raw MWNTs.

Abstract: Five Fucoidan fractions from Laminaria japonica with different sulfate content and molecular weight were obtained by anion-exchange chromatography and mild acid hydrolysis. Their antioxidant effects on azo radicals AAPH- and AMVN -induced oxidation of human low-density lipoprotein (LDL) were evaluated by monitoring cholesteryl ester hydroperoxides (CHE-OOH) formation kinetics by HPLC analysis. Two antioxidants probucol and Vc were used as comparison. Fucoidan F-C with low molecular weight 2,000-8,000 and sulfate content 24.3% had much stronger protective antioxidant effects than other four Fucoidan fractions on both hydrophilic radical AAPH and lipophilic radical AMVN induced LDL oxidation. In AMVN induced LDL oxidation system, the other four Fucoidan fractions with molecular weight of 200,000 and 20,000 were able to modify the kinetics of LDL oxidation with the similar efficiency. However, the highly sulfated Fucoidan fraction L-B with molecular weight 20,000 was completely ineffective in protecting LDL from AAPH induced oxidation, whilst it effectively suppressed the oxidation of LDL induced by AMVN. The different protective antioxidant effects of Fucoidans on AAPH and AMVN induced LDL oxidation were due to their various structures and properties, and their capacities to interact with the different sites Fucoidans reacted on LDL.

Abstract: Ethyl carbamate is a pluripotent carcinogen, and most fermented foods and beverages, including table wine, contain trace amounts of ethyl carbamate. The optimized parameters of the solid phase microextraction of table wine were: sample pH was 10.2, and 9.0 mL sample and 2.0-2.5 g (20-25%) sodium chloride were added to the vial; A 70 μm CW/DVB fiber was inserted into the headspace for 35 min at 40°C, then the fiber removed from the sample vial and inserted into the injection port of the GC for 10 min. Under this extraction conditions, the recoveries and the precision were 93.4-101.0% and 3.73-7.10%, respectively. The limit of detection was 3.0 μg/L. The solid phase microextraction technique was successfully applied to determine the EC levels in table wines. The extraction method was rapid and simple, and without the need for any organic solvent. It was an environmental protecting extraction method.

Abstract: The introduction of biomineralization was coupled with the co-precipitation synthesis process of nano-hydroxyapatite with the addition of chondroitin sulfate as a template agent. The effect of a variety of processing conditions on the properties of final hydroxyapatite (HA) product was investigated by orthogonal design. The ratio of calcium to phosphorus was detected by chemical analysis, the phase composition was evaluated by X-ray diffraction (XRD), and the powder morphology was characterized by transmission electron microscope (TEM). The process scheme, moreover, was optimized by the analysis of four aspects which may have different extent of influence on product properties. It can be concluded from the results that product properties can be affected remarkably by the content of chondroitin sulfate and the pH value of reactant, less remarkably by the reaction temperature and slightly by the reaction time.

Abstract: Nanocrystalline ZnS particles were prepared by hydrothermal method and characterized by XRD, FT-IR, TEM and UV-vis DRS and their photocatalytic activities were evaluated by the photodegradation of Eosin B under visible light. The results showed that the ZnS nanoparticles we prepared were in hexagonal phase, their average size of the complex particles varies from 10 nm to 20 nm, and also revealed well photocatalytic activity under visible light, the photocatalytic decolouration rate of Eosin B in 3 h reached 70 %.

Abstract: Based on the anodic oxidation method, titanium dioxide thin films with different morphology were prepared through altering the potential applying mode, the initial potential, the temperature of the electrolyte and the oxidation time. The crystal structures of them were analyzed by X-ray diffractometer. The results indicated that the potential applying mode, the initial potential, the temperature of the electrolyte as well as the oxidation time all have no effect on the crystal structure of TiO₂ thin films. The TiO₂ thin films obtained under different conditions all show anatase-type, and have the same preferred orientation, but their particle sizes shows great differences.

Abstract: Here, we report the synthesis of nanoporous gold (NPG) with a uniform structure by chemical dealloying of an AlAu intermetallic compound under free corrosion conditions. The length scales of ligaments/channels in NPG can be tuned by changing the dealloying solution. We verify that Cl^- can accelerate the surface diffusion of Au atoms and induce the coarsening of ligaments/channels in NPG. In addition, a metastable intermediate Al₂Au₅ phase appears during the dealloying of AlAu.

Abstract: Size-tunable ZnS nanocrystals were obtained by electron sputtering. Almost sputtered nanocrystals were spherical and well-dispersed. The sizes of deposited ZnS nanocrystals appeared a good gradient distribution according to their distance away from the sputtering target. These nanocrystals had gradual changes in diameter from about 1 to 15 nm. This research may afford a simple and efficient method to prepare well-dispersed semiconductor nanocrystals in a small size range.

Abstract: The nano-scale Cu₂O-TiO₂ couple oxide photocatalyst was successfully synthesized by the homogeneous hydrolysation, followed by the solvothermal crystallization and ethylene glycol-thermal reduction process, respectively. The obtained photocatalysts were characterized by X-ray diffraction (XRD), showing that the crystal phase composition and the crystal size of the prepared photocatalyst were affected by the ethylene glycol-thermal reduction temperature. The photocatalytic activity of Cu₂O-TiO₂ was also evaluated by the degradation of methyl orange (MO) as a model compound. The results showed that the prepared Cu₂O-TiO₂ exhibited higher photocatalytic activity for the decomposition of MO than the pure Cu₂O and the commercial Degussa P25 TiO₂ under visible light irradiation.