STRUCTURE OF THERMOTROPIC LIQUID CRYSTALLINE VANILLIC ACID/P-HYDROXYBENZOIC ACID/ETHYLENE TEREPHTHALATE VHE TERPOLYESTERS

Thermotropic liquid crystalline VHE terpolyesters made from vanillic acid (V),p-hydroxybenzoic acid (H) and poly(ethylene terephthalate) (E) were studied by 400 MHz NMR spectra, wide angle X-ray diffraction,scanning electron and polarizing microscopes.It was found that the VHE terpolyesters had random sequence distribution.The VHE terpolyester films exhibited highly oriented fibrillar structure.

Optimizing the crystallinity and acidity of H-SAPO-34 by fluoride for synthesizing Cu/SAPO-34 NH_3-SCR catalyst

A series of H-SAPO-34 zeolites were synthesized by a hydrothermal method in fluoride media.The as-synthesized H-SAPO-34 zeolites were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,N_2 physisorption,temperature-programmed desorption of NH_3（NH_3-TPD） and nuclear magnetic resonance（NMR） measurements.The results showed that a certain concentration of F- anions promoted the nucleation and crystallization of H-SAPO-34.The H-SAPO-34 synthesized in the fluoride media showed high crystallinity,uniform particle size distribution,large specific surface area and pore volume,and enhanced acidity.Therefore,Cu/SAPO-34 based on the fluoride-assisted zeolite showed a broadened temperature window for the selective catalytic reduction of NO by NH_3（NH_3-SCR） reaction due to the enhanced acidity of the zeolite and the improved dispersion of copper species.

Assessing the effects of surface-bound humic acid on the phototoxicity of anatase and rutile TiO_2 nanoparticles in vitro

In this study,the cytotoxicity of two different crystal phases of TiO2 nanoparticles,with surface modification by humic acid（HA）,to Escherichia coli,was assessed.The physicochemical properties of TiO2 nanoparticles were thoroughly characterized.Three different initial concentrations,namely 50,100,and 200 ppm,of HA were used for synthesis of HA coated TiO2 nanoparticles（denoted as A/RHA50,A/RHA100,and A/RHA200,respectively）.Results indicate that rutile（LC50（concentration that causes 50%mortality compared the control group）=6.5）was more toxic than anatase（LC50=278.8）under simulated sunlight（SSL）irradiation,possibly due to an extremely narrow band gap.It is noted that HA coating increased the toxicity of anatase,but decreased that of rutile.Additionally,AHA50 and RHA50had the biggest differences compared to uncoated anatase and rutile with LC50of 201.9 and21.6,respectively.We then investigated the formation of reactive oxygen species（ROS）by TiO2 nanoparticles in terms of hydroxyl radicals（OH）and superoxide anions（O2^-）.Data suggested that O2^- was the main ROS that accounted for the higher toxicity of rutile upon SSL irradiation.We also observed that HA coating decreased the generation of OH and O2^- on rutile,but increased O2^- formation on anatase.Results from TEM analysis also indicated that HA coated rutile tended to be attached to the surface of E.coli more than anatase.