Confocal and scanning electron microscopic observations have previously shown the strong bacterial association of Microcystis aeruginosa cells on their surfaces. DNA-based analyses of the associated bacterial communities were carried out using two M. aeruginosa strains grown in the laboratory and eight newly collected cyanobacterial bloom samples. M. aeruginosa was the most predominant species (66–100%) within the phylum Cyanobacteria. Rhizobium, Hydrogenophaga and Brevundimonas species were commonly found, and Flavobacterium species were present in all the cyanobacterial bloom samples. In total, 396 colonies from various samples were screened, revealing that most culturable bacteria belonged to the class Alphaproteobacteria (19%) including Rhizobium, Brevundimonas, and Porphyrobacter species. The genetic variation among the M. aeruginosa strains and different habitat conditions may have led to the presence of distinct bacterial populations among the tested samples. Among all the tested seven culturable isolates, Rhizobium sp. MK23 showed the best growth-promotion effect on the axenic M. aeruginosa strains. H2O2 was observed to be produced during the growth of M. aeruginosa PCC7806 under light conditions, this strain was more resistant to H2O2 when associated with Rhizobium sp. MK23. Our data suggested that Rhizobium species along with other associated bacteria might help the growth of M. aeruginosa by decomposing H2O2 under the aerobic growing conditions.
In a high soil resistivity area, counterpoise wires are applied to decrease the grounding resistance of tower grounding devices. If the conductor of counterpoise wire is very long, although the power frequency grounding resistance of the tower grounding device is decreased, the lightning protection performance of the transmission line is still not good. The influences of the length of grounding electrodes on the lightning transient characteristic were analyzed. The dynamic and nonlinear effect of soil ionization around the grounding electrode was considered in the analysis model of transient characteristics for the grounding electrodes under lightning impulse. The counterpoise wire has an effective length when lightning passes through it. When the length of a grounding electrode exceeds the effective length, the grounding conductor will not be utilized effectively. The simulating experiments were performed to analyze influences of the length of the counterpoise wire on the impulse characteristics. The formulae to calculate the impulse effective lengths of counterpoise wires were proposed. The model proposed in the paper has been validated by comparing the numerical results with experimental tests.
A polycrystalline silicon thin-film transistor (TFT) technology, field-aided lateral crystallization (FALC), has been explored. Polycrystalline silicon thin film, as an active layer, was prepared by applying an electric field to amorphous silicon film during Ni metal-induced lateral crystallization (MILC). Compared with the conventional metal-induced lateral crystallization thin-film transistors (MILC TFTs), these field-aided lateral crystallization thin-film transistors (FALC TFTs) show a low off-state leakage current of 1.79×10−11 A at Vg=−10 V and a high on/off current ratio of 8.82×105. Moreover, the threshold voltage is lower and field-effect mobility is higher than those of MILC TFTs. Therefore, the possibility of high-performance and low-temperature (<500 °C) polycrystalline silicon TFTs was demonstrated by using FALC technology.
In this study, the effects of various metals on field aided lateral crystallization (FALC) behaviors of amorphous silicon (a-Si) were investigated. Under the influence of the electric field, some metals such as Cu, Ni and Co were found to induce the lateral crystallization toward the metal-free region while Au, Al and Cr were not able to induce the crystallization of a-Si. On the other hand, the effect of the electric field on the lateral crystallization was not obvious for Pd. These phenomenological differences could be interpreted in terms of the dominant diffusing species (DDS) in the reaction between the metal and Si. It is judged that the applied electric field can enhance the crystallization velocity by accelerating the diffusion of metal atoms because the occurrence of lateral crystallization is known to rely on the diffusion of metal atoms than that of Si atoms. Therefore, it is thought that the only metal-dominant diffusing species in the reaction between metal and Si can strongly result in the crystallization of a-Si in metal-free region.
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