[Ecological network construction and optimization in Foshan City, China]. / 佛山市生态网络构建及优化.

Under the background of rapid urbanization, the problem of fragmented habitat patches in economically developed areas is particularly prominent, where biodiversity is seriously threa-tened. Therefore, the construction of ecological network is an important measure to connect habitat patches and protect biological habitats. We extracted ecological source areas of Foshan City by using the connectivity index and morphological spatial pattern analysis (MSPA). Potential ecological corridors were identified based on InVEST model and minimal cumulative resistance (MCR). Combining the radiation channels extracted from hydrological analysis to build an ecological network in Foshan City. The ecological network was optimized by adding ecological source areas, stepping stones, and identifying fracture points. Finally, the network before and after optimization was evalua-ted from the aspects of both structure and function based on network analysis method and circuit theory. The results showed that ecological network in Foshan City was composed of 10 ecological source areas, 8 important corridors, 37 general corridors, and 11 radiation channels. After optimization, 7 new ecological source areas, 17 planning corridors, 13 stepping stones, and 80 fracture points were added. After optimization, the ecological network closure, the line rate index and the connection degree index were 0.59, 1.94, and 0.73, respectively. The maximum current density increased from 1.39 to 9.66 after optimization, indicating that the optimized ecological network structure was more perfect and highly connective.

[Preparation of La(2)Zr(2)O(7) Powder with Combustion Method and Its Spectral Properties].

La(2)Zr(2)O(7) powder was prepared with combustion method with La(2)O(3), Zr(NO(3))(4) and glycine as raw materials. La(2)Zr(2)O(7) powders were characterized with ICP-AES, EDAX, XRD, IR and TG-DTA techniques, respectively. Effects of heat treatment temperature on the XRD spectra and IR spectra of La(2)Zr(2)O(7) powders were studied. The X-ray diffraction pattern of La(2)Zr(2)O(7) powder after heat treatment at 600 ℃ has one diffraction peak, and the diffraction peak is quite broad, therefore, the crystal structure of the La(2)Zr(2)O(7) powder is semi-crystal structure. With the increase of heat treatment temperature, diffraction peaks become gradually sharp and increase. The crystal structure of the La(2)Zr(2)O(7) powders after heat treatment in 750～800 ℃ are pyrochlore structure. Analysis results of IR spectra of La(2)Zr(2)O(7) powders after heat treatment in 650～750 ℃ show that the crystal structure of the La(2)Zr(2)O(7) powders after heat treatment at 750 ℃ is pyrochlore structure, and the analysis results of XRD and IR are the same. Analysis results of TG-DTG of La(2)Zr(2)O(7) powders show that the crystal structure of the La(2)Zr(2)O(7) powders are stability in 120～1 600 ℃.