Superconductivity in the silicon clathrate compound (Na,Ba)xSi46

A new silicon clathrate compound containing barium, (Na,Ba)xSi46, becomes a type-II superconductor with a critical temperature (Tc) of about 4 K. In the compound, the silicon atoms are bonded tetrahedrally with about the same bond distances as in ordinary cubic diamond Si, but form 12- and 14-hedral cages which are linked by shared faces. The metal atoms are located in the center of the polyhedra. This is the first superconductor consisting of a Si sp3 covalent network

Characteristics of physical activity during beginner-level group tennis lessons and the effect daily activity

Kawakami R., Yamakawa S., Konda S., et al. Characteristics of physical activity during beginner-level group tennis lessons and the effect daily activity. Scientific Reports 14, 249 (2024); https://doi.org/10.1038/s41598-023-46843-0.Tennis is a popular leisure sport, and studies have indicated that playing tennis regularly provides many health benefits. We aimed to clarify the characteristics of physical activity during beginner-level group tennis lessons and daily physical activity of the participants. Physical activity was measured using an accelerometer sensor device for four weeks, including the 80-min duration tennis lessons held twice a week. Valid data were categorized for tennis and non-tennis days. The mean physical activity intensity during the tennis lesson was 3.37 METs. The mean ratio of short-bout rest periods to the tennis lesson time in 90 and 120 s was 7% and 4%, respectively. The mean physical activity intensity was significantly higher (p < 0.0001) and the duration of vigorous-intensity physical activity (VPA) was increased in 76% of participants on days with tennis lessons compared to without tennis lessons. Beginner-level tennis lesson has characteristics of less short-bout rest physical activity than previously reported competitive tennis match and increased the duration of VPA in daily activity compared to without tennis lessons, suggesting that beginner-level tennis lessons contribute physical activity of health benefits