[Fractional vegetation cover and topographic effects in Pisha sandstone area of Northwest China in 2000-2018].

Based on MODIS-EVI data and binary pixel model, we calculated fractional vegetation coverage (FVC) in Pisha sandstone area of Northwest China from 2000 to 2018. The topographic effects on fractional vegetation coverage was analyzed from elevation, slope, and aspect using digital elevation model (DEM) data. From 2000 to 2018, FVC in Pisha sandstone area of Northwest was relatively low, which increased with a rate of 2.

Role of NO in Hg(0) oxidation over a commercial selective catalytic reduction catalyst V2O5-WO3/TiO2.

Experiments were conducted in a fixed-bed reactor that contained a commercial catalyst, V2O5-WO3/TiO2, to investigate mercury oxidation in the presence of NO and O2. Mercury oxidation was improved by NO, and the efficiency was increased by simultaneously adding NO and O2. With NO and O2 pretreatment at 350°C, the catalyst exhibited higher catalytic activity for Hg(0) oxidation, whereas NO pretreatment did not exert a noticeable effect.

Mechanism of Hg(0) oxidation in the presence of HCl over a commercial V2O5-WO3/TiO2 SCR catalyst.

Experiments were conducted in a fixed-bed reactor containing a commercial V2O5/WO3/TiO2 catalyst to investigate mercury oxidation in the presence of HCl and O2. Mercury oxidation was improved significantly in the presence of HCl and O2, and the Hg(0) oxidation efficiencies decreased slowly as the temperature increased from 200 to 400°C. Upon pretreatment with HCl and O2 at 350°C, the catalyst demonstrated higher catalytic activity for Hg(0) oxidation.

Preparation and luminescence properties of LaMgAl11O19:Eu3+ phosphor powder.

LaMgAl11O19, is a kind of rare earth aluminate with the hexagonal structure, which has been used as a host material for the luminescence of various rare earth and magnet-like ions. LaMgAl11O19:Eu3+ phosphors have been prepared through the one-pot method. X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the resulting phosphors.

Study on energy transfer and energy migration of Ca2Gd8(SiO4)6O2:Dy3+ phosphor films.

Being a kind of rare-earth-metal silicate with oxidapatite structure, Ca2R8(SiO4)6O2 (R = Y, Gd, La) is a promising material doped with rare earth, and widely used as phosphors. In this thesis, Ca2Gd8(SiO4)6O2:Dy3+ films were prepared by the sol-gel method. X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting films.

Direct synthesis of ultrafine tetragonal BaTiO3 nanoparticles at room temperature.

A large quantity of ultrafine tetragonal barium titanate (BaTiO3) nanoparticles is directly synthesized at room temperature. The crystalline form and grain size are checked by both X-ray diffraction and transmission electron microscopy. The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized.