Previous studies have shown that the mechanical effects of vegetation roots on slope stability can be classified as additional cohesion effects and anchorage effects. The present study investigated the combined mechanical effects (additional cohesion effects and anchorage effects) of vegetation on a slope with coarse-grained soil in the mountainous region (significantly prone to slope failure) of Gansu Province, China. A detailed survey of tree density, root system morphology and slope profiles was conducted, and we also assessed the soil cohesion provided by the root systems of monospecific stands of Robinia pseudoacacia growing in different locations on the slope. The measured data were incorporated into a numerical slope model to calculate the stability of the slope under the influence of trees. The results indicated that it was necessary to consider the anchoring effect of coarse roots when estimating the mechanical effects of trees on slope stability. In particular, the FoS (factor of safety) of the slope was increased by the presence of trees. The results also demonstrated that vegetation increased slope stability. The reinforcing effects were most significant when the trees were planted along the entire slope. Although the reinforcing effects contributed by trees were limited (only 4–11%), they were essential for making optimal use of vegetation for enhancing slope stability. Overall, vegetation development can make a major contribution to ecosystem restoration in the study region.

To achieve high-value utilization of rare earth resources and meet the demands for nitrogen oxide (NO _x ) pollution control, this study focuses on the Ce-rich Bayan Obo rare earth mineral, aiming to develop efficient mineral-based denitration catalysts and elucidate the underlying mechanisms. Although this type of mineral is rich in Ce with catalytic potential, the associated Ca severely restricts the intrinsic activity of Ce and the overall denitration performance. In this work, acid leaching was applied to selectively remove Ca, and combined with multiple characterization techniques, we systematically clarified how Ca removal optimizes the speciation and surface properties of Ce, thereby significantly enhancing the selective catalytic reduction (NH ₃ -SCR) activity. The results indicate that the modified catalyst exhibits a notably increased specific surface area, an optimized Ce ³⁺ /Ce ⁴⁺ redox pair ratio, an increased oxygen vacancy concentration, and a predominant presence of Ce species in low-polymerization states. The NO _x conversion rate at 350 °C was dramatically improved from 18.9% for the raw ore to 82.1%, while maintaining excellent N ₂ selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy ( in situ DRIFTS) further confirmed that Ca removal exposes more Ce active sites and enhances the synergistic effect between Brønsted and Lewis acid sites. The established correlation system of ‘Ca removal–Ce speciation–denitration reaction mechanism’ in this work provides a solid theoretical foundation for the design of high-performance rare earth mineral-based catalysts.