[Mechanism of chlorogenic acid on apoptosis of rat nucleus pulposus cells induced by oxidative stress].

OBJECTIVE: To investigate the mechanism of chlorogenic acid (CGA) on H2O2-induced apoptosis in the rat nucleus pulposus cells (NPCs). METHODS: NPCs were isolated from SD rats and cultured in vitro. Cultured cells (P3) were randomly divided into normal control group, H2O2 group, CGA + H2O2 group, CGA group and LY294002 pretreatment group. The apoptosis and ROS production of rNPCs was detected by flow cytometry. The expressions of p-Akt, BCL-2 and Akt were analyzed by Western blot. RESULTS: Compared with normal control group, in the H2O2 group, the production of ROS and the apoptosis rate significantly increased in rNPCs; CGA treatment inhibited ROS production and cell apoptosis, while increased the expression of p-Akt and BCL-2; LY294002, a PI3Kinse inhibitor, not only decreased the expression of p-Akt and BCL-2, but also obviously increased ROS production and cell apoptosis. CONCLUSION: Chlorogenic acid can protect NPCs against apoptosis by oxidative stress through decreasing reactive oxygen species production and increasing anti-apoptotic protein BCL-2 expression in NPCs by activation of PI3K-Akt signaling pathways.

[Study on the absorption spectrum properties of flexible black silicon doped with sulfur and fluorine based on first-principles].

It is quite urgent to need a flexible photodetector in the ultraviolet-visible-near infrared region for building a miniaturization broadband spectrometer. In the present paper, one kind of flexible black silicon doped with sulfur and fluorine was proposed and the optical absorption spectrum was investigated in broadband region. Firstly, the electronic structure, band structure and the optical absorption properties of the flexible black silicon doped with sulfur and fluoride were calculated using the first-principles pseudo potential calculations based on density-functional theory. Then, the absorption spectrum model of the flexible black silicon was built based on both the first-principles and finite domain time difference method. The results show that the cut-off wavelength has a red shift as the band gap of doped material becomes narrower. The higher the doping concentration is, the higher the optical absorption coefficient is obtained. The absorption coefficient of flexible black silicon doped with 50% sulfur is 8.3 times higher than that of 1.5% sulfur doping sample at the wavelength of 1 500 nm while the ratio turns to be 3 times when doped with 50% and 1.5% fluoride. The black silicon with small-size surface microstructure has the highest absorptance in the near-infrared region at the same doping concentration of 50%. Finally, a sample of flexible black silicon was fabricated by the femtosecond laser auto scanning system. The test results indicate that the absorptance of the sample is higher than 95% both in the ultraviolet and visible region and is fluctuated from 70% to 80% in the near-infrared region. It shows that as a novel light-absorbing material in broadband region the flexible black silicon doped with Sulfur and Fluorine has an potential application in exploring miniaturization broadband spectroscopy.

[Quartz-enhanced photoacoustic spectroscopy trace gas detection system based on the Fabry-Perot demodulation].

An all-optical quartz-enhanced photoacoustic spectroscopy system, based on the F-P demodulation, for trace gas detection in the open environment was proposed. In quartz-enhanced photoacoustic spectroscopy (QEPAS), an optical fiber Fabry-Perot method was used to replace the conventional electronic demodulation method. The photoacoustic signal was obtained by demodulating the variation of the Fabry-Perot cavity between the quartz tuning fork side and the fiber face. An experimental system was setup. The experiment for detection of water vapour in the open environment was carried on. A normalized noise equivalent absorption coefficient of 2.80 x 10(-7) cm(-1) x W x Hz(-1/2) was achieved. The result demonstrated that the sensitivity of the all-optical quartz-enhanced photoacoustic spectroscopy system is about 2.6 times higher than that of the conventional QEPAS system. The all-optical quartz-enhanced photoacoustic spectroscopy system is immune to electromagnetic interference, safe in flammable and explosive gas detection, suitable for high temperature and high humidity environments and realizable for long distance, multi-point and network sensing.