芝麻叶中多酚的提取、成分分析及抗氧化活性

为了对芝麻叶的开发提供参考，以芝麻叶超微粉为原料，以芝麻叶多酚提取率为指标，通过单因素实验和响应面实验优化超声微波协同辅助提取芝麻叶多酚的工艺条件。采用HPLC测定了芝麻叶多酚中绿原酸、咖啡酸、对香豆酸、阿魏酸、柚皮苷含量，并测定了芝麻叶多酚的DPPH·、ABTS⁺·清除能力和Fe³⁺还原力。结果表明：芝麻叶多酚最佳提取工艺条件为料液比1∶30、乙醇体积分数70%、浸提温度45℃、超声功率160 W、超声时间25 min、微波功率400 W、微波时间2 min,在此条件下芝麻叶多酚提取率为4.46%;芝麻叶多酚中阿魏酸含量最高，为2.068 mg/g,未检出对香豆酸；芝麻叶多酚能够有效清除DPPH·及ABTS⁺·,也具有一定的Fe³⁺还原力。综上，芝麻叶多酚具有一定的抗氧化活性，可以通过超声微波辅助的方法从芝麻叶中高效提取。     

Microwave-Assisted Synthesis of Highly Active Single-Atom Fe/N/C Catalysts for High-Performance Aqueous and Flexible All-Solid-State Zn-Air Batteries

The development of low-cost single-atom electrocatalysts for oxygen reduction reaction (ORR) is highly desired but remains a grand challenge. Superior to the conventional techniques, a microwave-assisted strategy is reported for rapid production of high-quality Fe/N/C single-atom catalysts (SACs) with profoundly enhanced reaction rate and remarkably reduced energy consumption. The as-synthesized catalysts exhibit an excellent ORR performance with a positive half-wave potential up to 0.90 V, a high turnover frequency of 0.76 s⁻¹, as well as a satisfied stability with a lost half-wave potential of just 27 mV over 9000 cycles (much better than that of Pt/C with 107 mV lost) and good methanol resistance. The open-circuit voltages of as-constructed aqueous and flexible all-solid-state Zn-air batteries (ZABs) are 1.56 and 1.52 V, respectively, higher than those of 20% Pt/C-based ones (i.e., 1.43 and 1.38 V, respectively). Impressively, they afford a peak power density of 235 mW cm⁻², which exceeds that of Pt/C (i.e., 186 mW cm⁻²), and is comparable to the best ones of Fe/N/C-based ZABs ever reported.