Evaluation and Improvement of Antioxidant Activity of Water-soluble Lignin Products from Steam Explosion Processing of Corn Stalk

In this study,corn stalk was pretreated by steam explosion under various processing conditions,and the antioxidant activity of hydrolysates in the post-process washing liquor was analyzed using the 1,1'-diphenyl-2-picrylhydrazyl(DPPH•)scavenging method.The yield and composition of the hydrolysates obtained under different treatment conditions were also determined;the results indicated that the steam explosion extent had a significant effect on both properties.Under optimized conditions(1.5 MPa,20 min),the obtained hydrolysate had the highest phenolic compound yield(18.6 mg/g untreated corn stalk)and the highest radical scavenging capacity(IC_(50)=0.24 mg/mL).To confirm the positive effect of phenolic compounds on the antioxidant activity of the hydrolysate,one-step ethanol fractionation was carried out.Due to the enrichment of phenolic compounds,the ethanolsoluble fraction(ESF)exhibited significantly enhanced antioxidant activity with an IC_(50) value of 0.06 mg/mL,which was close to that of butylated hydroxytoluene(BHT,IC_(50)=0.056 mg/mL).Consequently,this work indicated that phenolic compounds have a significant effect on the antioxidant activity of hydrolysate from steam-exploded corn stalk and that simple one-step ethanol fractionation is an effective way to enrich the phenolic compounds in the hydrolysate and improve the antioxidant activity.

FS-LASIK术中不同掀瓣时机进行静态眼球自旋识别成功率的对比

目的:探讨在飞秒激光辅助的准分子激光原位角膜磨镶术(FS-LASIK)中不同的掀瓣时机之间静态眼球自旋(SCC)定位识别成功率的差异。方法:前瞻性临床研究。选取2017年7-9月在南京医科大学附属明基医院眼科行角膜屈光手术的近视患者205例(410眼),其中行FS-LASIK的患者183例(366眼)为FS-LASIK组,行经上皮准分子激光角膜切削术(TransPRK)的患者22例(44眼)为TransPRK组。FS-LASIK组的366眼根据SCC定位识别时机不同分别为掀瓣前测量组(130眼)、掀瓣后测量组(126眼)和掀瓣后再覆盖测量组(110眼)。测量各组术眼的SCC方向和程度。采用卡方检验比较各组间SCC定位识别成功率差异。采用独立样本t检验和方差分析比较不同组别的SCC度数差异。结果:所有患者的SCC定位识别成功率为77.3%。FS-LASIK组和TransPRK组SCC成功率分别为74.9%和97.7%,2组比较差异有统计学意义(χ^2=11.71,P<0.001)。右眼SCC成功率为82.4%,左眼为72.2%,两眼间差异有统计学意义(χ^2=6.13,P=0.013)。性别在SCC成功率方面差异无统计学意义。掀瓣前测量组、掀瓣后测量组和掀瓣后再覆盖测量组SCC定位识别成功率分别为63.8%、84.1%和77.3%,3组间差异有统计学意义(χ^2=14.47,P<0.001)。所有识别成功患者(317眼)SCC度数为3.0°±2.3°。而性别、眼别在SCC度数方面差异无统计学意义。FS-LASIK组和TransPRK组SCC度数分别为3.1°±2.4°和2.2°±1.7°,组间比较差异有统计学意义(t=1.99,P=0.007)。掀瓣前测量组、掀瓣后测量组和掀瓣后再覆盖测量组SCC度数比较差异无统计学意义。SCC>2°的占59.3%,>4°的占28.7%,>6°的占9.2%。结论:在FS-LASIK术中,掀开角膜瓣后进行SCC定位识别的成功率较高。