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Rill erosion is recognized as an important process of water erosion on agricultural land. The objectives of this study are to examine the effects of rainfall intensity on rill network development and to present some indicators for a quantitative description of rill morphology. A soil pan (10 m long, 3 m wide and 0.5 m deep and with an adjustable slope gradient from 0 to 30°) was subjected to three successive rains under rainfall intensities of 50 and 100 mm h − 1 . The results showed that rainfall intensity significantly affected rill erosion, especially in the active period of rill network development. The magnitude of rill erosion was 28.5 and 33.1 kg m − 2 and contributed 78.6% and 76.2% to the soil loss under rainfall intensities of 50 and 100 mm h − 1 , respectively. The formation of rill network under the 50 mm h − 1 intensity was more complex than that under the 100 mm h − 1 intensity; for the latter rill networks developed fast and then varied slightly. The mean rill inclination angle ( δ mean ), rill density ( ρ ), degree of rill dissection ( μ ) and mean rill tortuosity complexity ( c mean ) increased with the increase of rains under the same rainfall intensity. The μ value was the optimal derivative morphological indicator to estimate rill erosion and morphology, which was followed in descending order by δ mean , c mean and ρ . [ABSTRACT FROM AUTHOR]

Abstract: Novel upconversion NaYF4:Yb3+,Er3+/TiO2 core–shell nanoparticles (NPs) are synthesized and used to prepare the photoelectrode (PE) of dye-sensitized solar cells (DSSCs). The morphology, structure, photoluminescence characterization of the NaYF4:Yb3+,Er3+/TiO2 core–shell NPs and the photoelectric performance, alternating current impedance spectroscopy of DSSCs are characterized using transmission electron microscopy, X-ray diffraction, upconversion luminescence (UCL) spectrofluorimetry and electrochemistry. Compared with the pure TiO2 PE or the NaYF4:Yb3+,Er3+ upconversion NPs and TiO2 simply mixed prepared PE as the volume ratio of the core–shell structure, the DSSCs with the upconversion core–shell PE show a greater photovoltaic efficiency. The energy conversion efficiency of the DSSCs with a NaYF4:Yb3+,Er3+/TiO2 PE is 23.1% higher than with a pure TiO2 PE and 99.1% higher than with a mixed PE using the same conditions. This enhancement is due to the UCL core extending the spectral response range of DSSCs to the infrared region and their particular shell structure, retaining its semiconductor character. This method represents a novel approach to increase the efficiencies of DSSCs. [Copyright &y& Elsevier]