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Nanoscale NiAl-NO3-LDHs with good crystallinity have been synthesized by a method, Separate Nucleation and Aging Steps (SNAS). An NiAI-NO3-LDHs/LDPE composite was prepared by blending NiAl-NO3-LDHs and LDPE in a heated double-roller mixer. The color of this composite changed from olive green to steel gray under UV irradiation. After heating at 80°C for 2 h, the color returned to olive green. The effect of varying the amount of added NiAI-NO3-LDHs and UV exposure time on the photochromic properties of the composite has been investigated. The results showed that the photochromic phenomenon becomes more apparent with increasing amount of NiAI-NO3-LDHs. When the amount reaches 5%, the composite exhibits good photochromic properties and reproducibility. The color change rate of the composite reaches a maximum when the irradiation time exceeds 20 min. The addition of LDPE improves the photochromic cyclability of NiAI-NO3-LDHs significantly. The addition of nanoscale NiAI-NO3-LDHs also improves the mechanical properties of LDPE to some extent. [ABSTRACT FROM AUTHOR]

Nano-MgO with various particle sizes, synthesized by different methods using Mg(NO3)2·6H2O, Na2CO3, Na2SO4, urea and ammonia solution as reactants, was used to carry out bactericidal experiments on Bacillus subtilis var. niger. The results were compared with the effect of TiO2, a common kind of photocatalytic material. The materials were characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), low temperature N2 adsorption-desorption measurements and FT-IR, and the results showed that the bactericidal ability of MgO increases with decreasing particle size. Nano-MgO and an interior wall-paint containing the material have better bactericidal effects than nono-TiO2 in both presence and absence of light. The bactericidal mechanism is discussed. The surface of MgO can generate high concentrations of O2- which ishighly active and can react with the peptide linkages in the coating walls of the spores. The spores are destroyed by the resulting damage to their structure. [ABSTRACT FROM AUTHOR]