Silver nanoparticles were prepared in the channels of mesoporous silica SBA-15 through silver mirror reaction.The results of X-ray diffraction(XRD) and transmission electron microscopy(TEM) reveal that Ag nanoparticle...Silver nanoparticles were prepared in the channels of mesoporous silica SBA-15 through silver mirror reaction.The results of X-ray diffraction(XRD) and transmission electron microscopy(TEM) reveal that Ag nanoparticles with uniform size about 2-3 nm were dispersed inside the channels of mesoporous SBA-15.UV-Vis absorption spectra indicate the quantum size effect of the Ag nanoparticles.Bacteriological tests were performed in Luria-Bertani(LB) medium on solid agar plates and in liquid systems supplemented with different concentrations of Ag/SBA-15.This nanocomposite was shown to be an effective bactericide against Staphylococcus.展开更多
Generally, FD coefficients can be obtained by using Taylor series expansion （TE） or optimization methods to minimize the dispersion error. However, the TE-based FD method only achieves high modeling precision over a...Generally, FD coefficients can be obtained by using Taylor series expansion （TE） or optimization methods to minimize the dispersion error. However, the TE-based FD method only achieves high modeling precision over a limited range of wavenumbers, and produces large numerical dispersion beyond this range. The optimal FD scheme based on least squares （LS） can guarantee high precision over a larger range of wavenumbers and obtain the best optimization solution at small computational cost. We extend the LS-based optimal FD scheme from two-dimensional （2D） forward modeling to three-dimensional （3D） and develop a 3D acoustic optimal FD method with high efficiency, wide range of high accuracy and adaptability to parallel computing. Dispersion analysis and forward modeling demonstrate that the developed FD method suppresses numerical dispersion. Finally, we use the developed FD method to source wavefield extrapolation and receiver wavefield extrapolation in 3D RTM. To decrease the computation time and storage requirements, the 3D RTM is implemented by combining the efficient boundary storage with checkpointing strategies on GPU. 3D RTM imaging results suggest that the 3D optimal FD method has higher precision than conventional methods.展开更多
Organic templates of as-synthesized siliceous,MCM-41 and SBA-15 can be effectively removed by oxidation treatment.The highly ordered mesostructures and surface properties of inorganic frameworks were retained after th...Organic templates of as-synthesized siliceous,MCM-41 and SBA-15 can be effectively removed by oxidation treatment.The highly ordered mesostructures and surface properties of inorganic frameworks were retained after the template being removed.MCM-41 and SBA-15 obtained after oxidation treatment showed larger pores and richer silanol groups compared with those obtained by conventional calcinations at 550 ℃ in air.The removing ratios of templates of MCM-41 and SBA-15 were respectively 88% and 98%.展开更多
文摘利用1998-2008年56个气象台站降水资料,结合TRMM月降水产品,通过对TRMM3B43降水数据在不同气候区、不同时空尺度的精度对比分析,探讨了卫星遥感反演降水产品在中国西北内陆河流域的适应性.结果表明:TRMM探测的月降水数据与实测月降水数据在整体上具有较好的一致性和线性相关性,相关系数为0.76,效率系数为0.58,其探测的降水量比观测值略大;TRMM在高原气候区月降水量的探测效果要优于在西风带区的;TRMM数据所反映的降水量的年内变化过程和实测降水量结果基本一致,但在具体的量上有一定的差异,表现为对降水相对集中的5-9月低估实测降水量,而在降水较少的10月-次年4月高估实测降水量,反映了TRMM对较大强度降水量的探测能力不足.流域多年平均降水量呈现南、北部大,中部小的格局,降水量的高值中心主要出现在高山地区,高达300 mm;而受西风环流影响的塔里木盆地东南面的且末-若羌一带、吐鲁番盆地和受高原区影响的柴达木盆地为极端干旱少雨区,降水量均不足100 mm.
文摘Silver nanoparticles were prepared in the channels of mesoporous silica SBA-15 through silver mirror reaction.The results of X-ray diffraction(XRD) and transmission electron microscopy(TEM) reveal that Ag nanoparticles with uniform size about 2-3 nm were dispersed inside the channels of mesoporous SBA-15.UV-Vis absorption spectra indicate the quantum size effect of the Ag nanoparticles.Bacteriological tests were performed in Luria-Bertani(LB) medium on solid agar plates and in liquid systems supplemented with different concentrations of Ag/SBA-15.This nanocomposite was shown to be an effective bactericide against Staphylococcus.
基金supported by the National Natural Science Foundation of China(No.41474110)Shell Ph.D. Scholarship to support excellence in geophysical research
文摘Generally, FD coefficients can be obtained by using Taylor series expansion （TE） or optimization methods to minimize the dispersion error. However, the TE-based FD method only achieves high modeling precision over a limited range of wavenumbers, and produces large numerical dispersion beyond this range. The optimal FD scheme based on least squares （LS） can guarantee high precision over a larger range of wavenumbers and obtain the best optimization solution at small computational cost. We extend the LS-based optimal FD scheme from two-dimensional （2D） forward modeling to three-dimensional （3D） and develop a 3D acoustic optimal FD method with high efficiency, wide range of high accuracy and adaptability to parallel computing. Dispersion analysis and forward modeling demonstrate that the developed FD method suppresses numerical dispersion. Finally, we use the developed FD method to source wavefield extrapolation and receiver wavefield extrapolation in 3D RTM. To decrease the computation time and storage requirements, the 3D RTM is implemented by combining the efficient boundary storage with checkpointing strategies on GPU. 3D RTM imaging results suggest that the 3D optimal FD method has higher precision than conventional methods.
文摘Organic templates of as-synthesized siliceous,MCM-41 and SBA-15 can be effectively removed by oxidation treatment.The highly ordered mesostructures and surface properties of inorganic frameworks were retained after the template being removed.MCM-41 and SBA-15 obtained after oxidation treatment showed larger pores and richer silanol groups compared with those obtained by conventional calcinations at 550 ℃ in air.The removing ratios of templates of MCM-41 and SBA-15 were respectively 88% and 98%.
