Effects of physical activity on sleep quality among university students: chain mediation between rumination and depression levels.

Background: Colleges and universities are currently facing the major public health issue of poor sleep quality. Sleep quality must be taken seriously to maintain the students' emotional and physical well-being. Thus, this study sought to determine how university students' levels of physical activity related to the quality of their sleep, as well as to explore the mechanisms via which physical activity affects sleep and provide suggestions for improving it.

Relative humidity sensor based on a silver nano-grating made from DVD discs.

A relative humidity sensor based on a silver nano-grating was proposed. By stripping and cleaning commercially available CD and DVD discs, polycarbonate plates with different grating periods are obtained. These plates as templates are coated with a layer of sputtered silver film to form silver nano-gratings, which exhibit refractive index sensing sensitivities of 517 nm/RIU and 742.