RESUMO
Previous researches of covalent organic frameworks (COFs) have shown their potential as fluorescent probes, but the regulation of their optical properties and recognition characteristics still remains a challenge, and most of reports required complicated post-decoration to improve the sensing performance. In this context, we propose a novel in-situ strategy to construct uracil-conjugated COFs and modulate their fluorescence properties for sensitive and selective mercury(II) detection. By using 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) and 1,3,6,8-tetrakis(4-aminophenyl)pyrene (TAPPy) as fundamental blocks and 5-aminouraci (5-AU) as the functional monomer, a series of COFs (Py-COFs and Py-U-COFs-1 to Py-U-COFs-5) with tunable fluorescence were solvothermally synthesized through an in-situ Schiff base reaction. The π-conjugated framework serves as a signal reporter, the evenly and densely distributed uracil acts as a mercury(II) receptor, and the regular pores (channels) make the rapid and sensitive detection of the mercury(II) possible. In this research, we manage to regulate the crystalline structure, the fluorescence properties, and the sensing performance of COFs by simply changing the molar ratio of precursors. We expect this research to open up a new strategy for effective and controllable construction of functionalized COFs for environmental analysis.
RESUMO
Indoor stadium is an important place for physical exercise and sports practice, but few studies have considered the impact of indoor environment on exercise performance. Anaerobic exercise refers to exercise with high load intensity and instantaneous intensity. Many kinds of exercise performance are closely related to anaerobic exercise. Therefore, the purpose of this study was to examine the influence of temperature, relative humidity and CO2 concentration on anaerobic exercise performance. Sixteen healthy participants (21.5 ± 3.5 years) performed Wingate anaerobic test in 9 cases under the orthogonal experimental design. Temperature is a significant factor affecting peak power (p < 0.05) and average power (p < 0.05). The peak power at 22 °C and 25 °C is 5.4% and 5.1% higher than that at 28 °C, and the average power at 22 °C and 25 °C is 4.2% and 4.3% higher than that at 28 °C. Besides, temperature affected overall environmental satisfaction before and after exercise (p < 0.005, p < 0.005) as well as ear temperature in sedentary state and after warm-up exercise (p < 0.005, p < 0.005). The range of 22 °C-25 °C is closer to the neutral temperature, and it is suitable for anaerobic exercise. However, we did not find that changes in relative humidity and carbon dioxide concentration had an effect on anaerobic exercise performance.
