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Population is a major production factor in rural development in China, which makes the study of rural population distribution patterns at different times and the factors influencing the population distribution an important foundation for understanding the issues in rural China and moving forward with the implementation of rural revitalization strategies. This paper analyzed the spatial evolution of the population in rural China based on population census data for the People's Republic of China by county in 1990, 2000 and 2010. Applying the geographical detector method, this paper also delved into the contributing factors that influenced the distribution based on the natural, social and economic data, such as the potential crop productivity, the average slope, the urbanization rate and the time cost to reach the nearest cities. The results indicate that the migration of the population from the rural areas into the cities, which was a result of rapid urbanization, did not change the original population distribution in rural China significantly. The rural population was still concentrated in the eastern plains, basins and deltas, and the North China Plain and Sichuan Basin still house the bulk of rural residents, but the population density of rural residents in the North China Plain and Sichuan Basin decreased from 1990 to 2010. The rural population in China tended to be distributed around the cities. Seventy-four percent of the rural population lived in an area within a 60-minute driving distance from the surrounding cities. The areas with dense rural population were basically consistent with the locations of the current major urban agglomerations in China. The current distribution of the rural population in China was a result of natural, social and economic conditions and location factors. Among them, natural factors such as the potential crop productivity and the degree of surface fragmentation had the most significant influence.

Photocatalytic organic transformation derived by functionalized polyoxometalate (POM)-based metal−organic frameworks provides a feasible route for fine chemical synthesis. Herein, three kinds of photoactive threedimensional silver-containing polyoxotungstate frameworks are synthesized with the formulasIn compounds 1−3, the cationic Ag−triazole clusters with diverse nuclei serve as nodes to assemble with rigid bridging ligands (L) and polyoxoanions to extend into stable three-dimensional frameworks, in which Keggin-type anions act as guests or pendants. When using them as heterogeneous photocatalysts, compounds 1−3 show high catalytic activity and selectivity for the photocatalytic aerobic oxidation of benzyl alcohol to benzoic acid under 10 W 365 nm light irradiation. Among them, compound 1 exhibits the highest performance with ca. 99% benzyl alcohol conversion and 99% selectivity of benzoic acid in 9 h. Compounds 2 and 3 show ca. 79 and 88% conversions of benzyl alcohol, respectively, which are higher than those of the individual Keggin-type precursors. Moreover, mechanism investigation suggests that the synergistic cooperation occurring between cationic Ag−triazole clusters and Keggin-type polyoxoanions modulates the energy band structures of compounds 1−3, resulting in the efficient separation of photogenerated carriers and accelerating the aerobic oxidation of benzyl alcohol. This work provides some important guidance for the design and development of efficient POM-based photocatalysts for practical organic transformation.