Objective To study the oxidative damage on testis of male rats induced by micro-nano-scale SiO2. Methods Male Wistar rats were exposed to nanometer SiO2(20-40 nm) and micro-meter SiO2(1-10 ?m)by intratracheal injection once two days. The rats were killed after 5 weeks of exposure. Some indicators related to the oxidative damage in the serum and the testis were determined. Results The activity of GSH-Px and SOD in the high dose groups decreased significantly and the MDA levels increased compared to the control group;The MDA levels of nano-silicon dioxide high dose group increased in the serum. Conclusion Nano-silicon dioxide may cause lipid peroxidation in the testis with a tendency of higher toxicity than that of micro-SiO2 at the same exposed level,the detail mechanism needs further discussion.

Cognitive ability assessment and cognitive enhancement techniques play an important role in maintaining and improving human cognitive function,psychological and emotional stability,and in enhancing work efficiency.This paper begins by introducing the theory of cognitive ability,influencing factors and cognitive assessment methods before summa-rizing the latest progress in current cognitive enhancement strategies and technological paths and analyzing their prospects of applications in order to provide reference for the development and application of personnel cognitive assessment and cog-nitive enhancement technology in the future.