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STEM (science, technology, engineering, and mathematics) education is recognized as the world's top education program. However, few STEM programs have been designed based on cultural-historical events. To explore this issue, the present study drew on the cultural-historical activity theory and the content analysis method by adopting the descriptive-interpretative approach to explore the STEM content of the Dujiangyan Irrigation System (DIS) in present-day Sichuan, China. As early as 2,275 years ago during the Warring States period, Li Bing, the governor of Shu Shire in the Qin state, implicitly implemented the STEM concept when building the irrigation system. The results of this study indicate that the DIS incorporates Science (e.g., the hydraulic principle), Technology (e.g., making a large cobblestone Bamboo-Cage for building Fish Mouth), Engineering (e.g., water-level measurement) and Mathematics (e.g., Calculation of sand discharge). Adopting an educational pedagogy proposed by UNESCO which emphasized learning concepts from daily life, the present study draws on a cultural-historical event to inform STEM learning. The method and results of this study can be applied in the design of STEM programs based on other cultural-historical events from around the world.

In order to understand the application of thermite, firstly, the development process is reviewed. Then, guided by practical application problems, the application of thermites in micro energetic devices (such as microigniters and microthrust-ers), energetic agents (such as pyrotechnics, propellants and their additives, primary explosives, and explosive additives), material preparation (including material preparation and synthesis, material welding), and other fields (such assafety devices, microbial killing, metal thermal cutting and oil well plugging) are reviewed. The safety issues (including sensitivity and toxici-ty) in the application of thermites are discussed. The shortcomings of the application of thermites research are summarized, such as the type of thermites with excellent performance are relatively simple, the development of new application scenarios is insufficient, and the safety research of thermite is not deep enough. Finally, the future research direction and development trend of thermite application research are prospected, and the development direction should be to develop new thermite, expand new application fields, and further study the application safety of thermite. With 124 references. [ABSTRACT FROM AUTHOR]

As most teleosts are unable to synthesize vitamin C, supplemental diets containing vitamin C diets play a crucial role in fish health. The aim of this study was to investigate the effect of dietary vitamin C on the intestinal enzyme activity and intestinal microbiota of silver pomfre (Pampus argenteus). Four experimental diets were supplemented with basic diets containing 300 mg of vitamin C/kg (group tjl3), 600 mg of vitamin C/kg (group tjl6), and 1200 mg of vitamin C/kg (group tjl12), as well as vitamin C-free supplemental basic diet (group tjl0), respectively. The four diets were fed to juvenile P. argenteus (average initial weight: 4.68 ± 0.93 g) for 6 weeks. The results showed that the activity of SOD (superoxide dismutase) and CAT (catalase) increased significantly while that of MDA (malondialdehyde) decreased significantly in group tjl3 compared to vitamin group tjl0. At the genus level, groups tjl0, tjl6, and tjl12 contained the same dominant microbial community, Stenotrophomonas, Photobacterium, and Vibrio, whereas group tjl3 was dominated by Stenotrophomonas, Delftia, and Bacteroides. Among the fish fed with a basic diet containing 300 mg of vitamin C/kg, the intestines exhibited a notable abundance of probiotic bacteria, including lactic acid bacteria (Lactobacillus) and Bacillus. The abundance of Aeromonas in groups tjl3 and tjl6 was lower than that of the vitamin C-free supplemental basic diet group, whereas Aeromonas was not detected in group tjl12. In addition, a causative agent of the disease outbreak in cultured P. argenteus, Photobacterium damselae subsp. Damselae (PDD) was the dominant microbiota community in groups tjl0, tjl6 and tjl12, whereas the abundance of PDD in group tjl3 was the lowest among the diets. Taken together, the diets supplied with vitamin C could influence the composition microbial community of P. argenteus. The low level of vitamin C (300 mg of vitamin C/kg per basic diet) supplementation could not only improve the antioxidant capacity but also resist the invasion of pathogenic bacteria. [ABSTRACT FROM AUTHOR]