KEYWORDS: Magnetism, Oxidation, Titanium dioxide, Photocatalysis, Oxygen, Scanning electron microscopy, Particles, Platinum, Transmission electron microscopy, Solar energy
Heterogenous photocatalysis has emerged as a sustainable and environmentally benign strategy since it converts solar energy into chemical energy. Though more research is exploring the magnetic field effect on photocatalysis, the mechanism is still ambiguous. Magnetic field-assisted and electric-assisted photocatalytic reactions were investigated in this study. In the first magnetic field-assisted experiment, the magnetic field effect on heterogenous photocatalysis was explored with TiO2 and Pt/TiO2. Isopropanol photocatalytic oxidation reaction was conducted. Two levels of dissolved oxygen concentration, magnitude of magnetic flux density and temperature were studied. The magnetic field positive effect was prominent, especially under higher dissolved oxygen concentration and greater magnitude of a magnetic field. For Pt/TiO2 photocatalyst at 10°C and dissolved oxygen concentration over 20 ppm, 450 Gauss increased isopropanol photooxidation by 10%, while 900 Gauss enhanced by 21%. For TiO2 photocatalyst at 10°C dissolved oxygen concentration over 20 ppm, 450 Gauss has no prominent effect, while 900 Gauss enlarged 18% isopropanol photooxidation. The statistical analysis demonstrated that dissolved oxygen with magnetic flux density interaction and DO were the top two influencing elements. The hyperfine mechanism results from the interaction between the electron spins with nuclear spins in atoms. It depends on the elements and the dwelling time of unpaired electrons with its nucleus. The mechanism would contribute to singlet (S) ⇄ triplet (T) intersystem crossing. It was possibly because the net Lorentz force acting on paramagnetic oxygen molecule and singlet-triplet intersystem crossing by magnetic field led to the enhancement of the photooxidation of isopropanol.
The core of the power inductor is made by powder metallurgy. By its nature, the powder-formed part has inherent nonuniform porosity pattern and parallel tool marks on the metal surface. In the past, the surface inspection of core is usually performed by using human eyes. However, the larger uncertainty of inspection will be induced while observing the defect image using human eyes. In the automated optical inspection process, the feature of defect is not easily separated from the image background by using the simple binarization method. This study develops an image processing method and employs a uniform diffuse illumination to build up a surface defect inspection system. Experiment result shows the distinguish rate is 95.5%, therefore it is clear that this system can successfully detects a set defect of the core of inductor.
KEYWORDS: Near field, Near field scanning optical microscopy, Super resolution, Near field optics, Thin films, Glasses, Surface plasmons, Image transmission, Optical microscopes, Interfaces
The near-field recording mechanism of the super resolution near-field structure, glass/ZnS-SiO2/AgOx/ZnS-SiO2, has been studied experimentally. Near-field optical effects of the glass/ZnS-SiO2/AgOx/ZnS-SiO2 have been observed by a tapping mode tuning-fork near-field scanning optical microscope (TMTF-NSOM) on the transmitting light spot. Laser-excited surface plasmon at the interfaces of AgOx/ZnS-SiO2 thin film was detected by this technique. Results showed that the transmitting focused light through the AgOx type super resolution near-field structure consists of a propagating term and an evanescent one resulted from the localized surface plasmon of the AgOx thin film. A strong enhancement of the near-field intensity and the dynamic localized enhancement of the transmitting focused light were observed as well.
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