ZnO thin films were prepared by electrophoretic deposition on stainless steel wire sieve, using zinc acetate as a precursor. The film was sintered and characterised by Scanning Electron Microscopy （SEM）, X-Ray Diffr...ZnO thin films were prepared by electrophoretic deposition on stainless steel wire sieve, using zinc acetate as a precursor. The film was sintered and characterised by Scanning Electron Microscopy （SEM）, X-Ray Diffraction （XRD） and chemisorption of oxygen. A culture bacterial consortium composed by gram negative rod-shaped microbes was prepared in a liquid agar in a flask. It was transported by air through a reactor equipped with a UV lamp with 3 and 5 sieves of a stainless steel wire coated with ZnO film. It was exposed in continuous in five experiments to photocatalytic advanced oxidation. The experiments showed a total efficiency for colony forming unit reduction of a maximum of 99.66% for a residence time of 20 seconds with 5 stainless steel wire where exposed in continuous to UV. Also they were evaluated at 7.5 seconds, observing that the contribution of residence time and amount of catalytic for the CFU reduction was quite similar. Variance analysis showed that the efficiency was significant with the no parametric Kruskal-Wallis test with P 〈 0.05. This technology could be used to clean indoor air of closed environments such as hospitals, crowded buildings or public transportation systems where airborne bacteria has been documented.展开更多
Characterizing the three-dimensional （3D） shape of a nanostructure by con- ventional imaging techniques in scanning electron microscopy and transmission electron microscopy can be limited or complicated by various f...Characterizing the three-dimensional （3D） shape of a nanostructure by con- ventional imaging techniques in scanning electron microscopy and transmission electron microscopy can be limited or complicated by various factors, such as two-dimensional （2D） projection, diffraction contrast and unsure orientation of the nanostructure with respect to the electron beam direction. In this paper, in conjunction with electron diffraction and imaging, the 3D morphologies of ZnO nanowires and nanobelts synthesized via vapor deposition were reconstructed by electron tomography in a scanning transmission electron microscope （STEM）. The cross-sections of these one-dimensional （1D） nanostructures include triangle, hexagonal, and rectangle shapes. By combining the reconstructed shape with the crystalline information supplied by electron diffraction patterns recorded from the same nanowire/nanobelt, the growth direction and its exposed surfaces were uniquely identified. In total, three different growth directions were confirmed. These directions are 〈 0001 〉, 〈21 10 〉 and 〈21 13 〉, corresponding to 〈001〉, 〈100〉 and 〈101〉 orientations in three-index notation. The 〈0001〉 growth nanowires show triangle or hexagonal cross-sections, with exposed {01]-0} side surfaces. The dominant surfaces of the 〈21 10〉 growth nanobelt are _＋（0001） planes. Both hexagonal and rectangle cross-sections were observed in the 〈 2]-13 〉 growth ZnO nanostructures. Their surfaces include the {01]-0}, {]-101} and {2112} planes. The nanobelts with a large aspect ratio of ~10 normally grow along the 〈 21 10 〉 direction, while nanobelts with small aspect ratio grow along 〈21 13 〉 growth direction. The approach and methodology demonstrated here can be extended to any nanostructures that even amorphous. can be crystalline, polycrystalline or展开更多
Electron beam （e-beam） irradiation is an inev- itable, but crucial issue for electron microscopy. Our investigation results show the e-beam-induced in situ structural transformations in silicon （Si） nanowires and ...Electron beam （e-beam） irradiation is an inev- itable, but crucial issue for electron microscopy. Our investigation results show the e-beam-induced in situ structural transformations in silicon （Si） nanowires and zinc oxide （ZnO） nanowires （NWs）, respectively. Crystal to amorphous structure transition was revealed in Si NWs utilizing high resolution electron microscopy and electron energy loss spectroscopy. Reconstruction at the （1010） surface of ZnO NWs was also observed in the transmission electron microscope （TEM） using aberration-corrected electron microscopy. These e-beam-induced in situ struc- tural transformations prove that the electron beam irradi- ation effect is able to be used for the local modification of one-dimensional nanomaterials.展开更多
文摘ZnO thin films were prepared by electrophoretic deposition on stainless steel wire sieve, using zinc acetate as a precursor. The film was sintered and characterised by Scanning Electron Microscopy （SEM）, X-Ray Diffraction （XRD） and chemisorption of oxygen. A culture bacterial consortium composed by gram negative rod-shaped microbes was prepared in a liquid agar in a flask. It was transported by air through a reactor equipped with a UV lamp with 3 and 5 sieves of a stainless steel wire coated with ZnO film. It was exposed in continuous in five experiments to photocatalytic advanced oxidation. The experiments showed a total efficiency for colony forming unit reduction of a maximum of 99.66% for a residence time of 20 seconds with 5 stainless steel wire where exposed in continuous to UV. Also they were evaluated at 7.5 seconds, observing that the contribution of residence time and amount of catalytic for the CFU reduction was quite similar. Variance analysis showed that the efficiency was significant with the no parametric Kruskal-Wallis test with P 〈 0.05. This technology could be used to clean indoor air of closed environments such as hospitals, crowded buildings or public transportation systems where airborne bacteria has been documented.
文摘Characterizing the three-dimensional （3D） shape of a nanostructure by con- ventional imaging techniques in scanning electron microscopy and transmission electron microscopy can be limited or complicated by various factors, such as two-dimensional （2D） projection, diffraction contrast and unsure orientation of the nanostructure with respect to the electron beam direction. In this paper, in conjunction with electron diffraction and imaging, the 3D morphologies of ZnO nanowires and nanobelts synthesized via vapor deposition were reconstructed by electron tomography in a scanning transmission electron microscope （STEM）. The cross-sections of these one-dimensional （1D） nanostructures include triangle, hexagonal, and rectangle shapes. By combining the reconstructed shape with the crystalline information supplied by electron diffraction patterns recorded from the same nanowire/nanobelt, the growth direction and its exposed surfaces were uniquely identified. In total, three different growth directions were confirmed. These directions are 〈 0001 〉, 〈21 10 〉 and 〈21 13 〉, corresponding to 〈001〉, 〈100〉 and 〈101〉 orientations in three-index notation. The 〈0001〉 growth nanowires show triangle or hexagonal cross-sections, with exposed {01]-0} side surfaces. The dominant surfaces of the 〈21 10〉 growth nanobelt are _＋（0001） planes. Both hexagonal and rectangle cross-sections were observed in the 〈 2]-13 〉 growth ZnO nanostructures. Their surfaces include the {01]-0}, {]-101} and {2112} planes. The nanobelts with a large aspect ratio of ~10 normally grow along the 〈 21 10 〉 direction, while nanobelts with small aspect ratio grow along 〈21 13 〉 growth direction. The approach and methodology demonstrated here can be extended to any nanostructures that even amorphous. can be crystalline, polycrystalline or
基金supported by the NationalBasic Research Program of China(2009CB623701)the National Natural Science Foundation of China(11374174,51390471)
文摘Electron beam （e-beam） irradiation is an inev- itable, but crucial issue for electron microscopy. Our investigation results show the e-beam-induced in situ structural transformations in silicon （Si） nanowires and zinc oxide （ZnO） nanowires （NWs）, respectively. Crystal to amorphous structure transition was revealed in Si NWs utilizing high resolution electron microscopy and electron energy loss spectroscopy. Reconstruction at the （1010） surface of ZnO NWs was also observed in the transmission electron microscope （TEM） using aberration-corrected electron microscopy. These e-beam-induced in situ struc- tural transformations prove that the electron beam irradi- ation effect is able to be used for the local modification of one-dimensional nanomaterials.
