Papers by Author: Xiao Dong Li

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Authors: Hai Ni, Xiao Dong Li
Abstract: Amorphous and crystalline (rhombohedral structure with [111] growth direction) boron nanobelts were synthesized by the vapor-liquid-solid technique. Their structure and chemical compositions were studied by various electron and atomic force microscopy techniques. Most amorphous and crystalline belts have a width to thickness ratio of 2 and are covered with a layer of amorphous silicon oxide. The crystalline belt cores are defect-free single crystals. Gold catalyst thickness and synthesis temperature are the two prominent parameters determining structure of the synthesized nanobelts. The elastic modulus and hardness were measured using nanoindentation and atomic force microscopy three-point bending techniques. The indentation elastic modulus and hardness were measured to be 92.84.5 GPa and 8.40.6 GPa for amorphous belts, and 72.73.9 GPa and 6.80.6 GPa for crystalline ones, respectively. The three-point bending elastic moduli were found to be 87.83.5 GPa and 72.22.4 GPa for amorphous and crystalline, respectively. The measured mechanical properties are 4-5 times lower than those of the counterpart bulk materials.
Authors: Shu Jie Yang, Xiao Dong Li, Shou Gang Yan
Abstract: Using methods of spatial autocorrelation analysis and trend analysis, the paper studies the spatial distribution pattern of NDVI based on the GIMMS NDVI dataset (1998-2008), in Western Jilin. The maximum value for 15d is got through the method of MAX processing. Results show that: the NDVI in growing season shows a rising trend in western Jilin in 1998-2008. In the study area, the NDVI in Western Jilin shows positive spatial autocorrelation in the whole region, but the partial NDVI is apt to scattered distribution, which means the vegetation cover of Western Jilin is generally fragmental.
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