百香果皮总黄酮提取工艺优化及其抗氧化活性研究

采用超声辅助溶剂法提取百香果皮中的总黄酮。基于单因素实验结果,以浸膏得率、总黄酮含量和清除DPPH自由基能力多指标为响应值,应用响应面法综合优化总黄酮提取工艺。结果表明,总黄酮最佳工艺为液料比40∶1,乙醇百分含量67%,超声时间30 min。此条件下浸膏得率为12.58%,总黄酮含量为11.56 mg RT/g DW,清除DPPH自由基SC_(50)值为0.19 mg/mL。最优提取工艺下的百香果皮黄酮提取物具有较好的清除ABTS自由基((0.17±0.01)mmol/L TE/g)和铁离子还原能力((2.35±0.03)mmol/L Fe^(2+)/g)。

The Surface Photovoltage Mechanism of a Silicon Nanoporous Pillar Array

The surface photovoltage(SPV)mechanism of a silicon nanoporous pillar array(Si-NPA)is investigated by using SPV spectroscopy in different external electric fields.Through comparisons with the SPV spectrum of single crystal silicon(sc-Si),the silicon nano-crystallite(nc-Si)/SiO_(x) nanostructure of Si-NPA is proved to be capable of producing obvious SPV in the wavelength range 300–580 nm.The SPV for the sc-Si layer and the nc-Si/SiO_(x) nanostructure has shown certain contrary characters in different external electric fields.Through analysis,the localized states in the amorphous SiO_(x) matrix are believed to dominate the SPV for the nc-Si/SiO_(x) nanostructure.

The Surface Photovoltaic and Photoluminescent Evolution of a Silicon Nanoporous Pillar Array for Different Etching Times

A series of silicon nanoporous pillar array(Si-NPA)samples are prepared with different times of hydrothermal etching,and their surface morphologies are characterized.A systematic study on the evolution trend of the surface photovoltage and photoluminescence spectra discloses that the adoption of a prolonged etching time will increase the native degree of oxidation and decrease the interfacial states density localized in the SiO𝑥matrix.These results might be helpful for designing Si-NPA-based semiconductor nanosystems with optimized physical properties.