Quantitative Detection of Copper Ions in Water via Feature-Level Fusion of UV-Vis Absorption and Fluorescence Spectra with Optimized XGBoost. - Zhang, Meng; Shen, Jikun; Tang, Ju; Xu, Tianqi; Xu, Wu; Zhang, Fan; Chen, Guo; Zhou, Chengjiang (Coatings (2079-6412), 2026)