ABSTRACT
We demonstrate the rapid photodarkening (PD) phenomenon in Tm-doped fiber (TDF) core pumped by a laser at 1080 nm and the bleaching effect of deuterium (${{\rm D}_2}$D2) on PD TDF. By ${{\rm D}_2}$D2 loading for seven days, the PD-induced excess loss (PIEL) in the visible (VIS) and near-infrared (NIR) region have been largely eliminated, and no degradation was observed within 30 days. PD resistance of the ${{\rm D}_2}$D2 pretreated TDF has been investigated as well. The formation of color centers based on defects and precursors in the silica matrix and the mechanism of ${{\rm D}_2}$D2 bleaching are discussed.
ABSTRACT
We demonstrate the almost complete 2 µm laser power recovery of the gamma-ray-irradiated thulium (Tm)-doped silica fiber under deuterium loading. The optical-optical slope efficiency and the cladding absorption spectra of the Tm-doped fiber with gamma-ray irradiation and deuterium treatment have been measured for comparison. It was found that the slope efficiency of the irradiated Tm-doped fiber could be recovered to 96.1% of the pristine after deuterium bleaching, which significantly degraded from 60.7% to 25.3% after irradiation. Meanwhile, the additional absorption attenuation of the irradiated Tm-doped with D2 treatment completely vanished. Based on the comprehensive comparison of cladding absorption spectra, the probable mechanism of the deuterium bleaching effect on irradiated Tm-doped fiber has also been discussed.
ABSTRACT
It has been shown that oxidative stress plays an important role in the pathogenesis of ethanol-induced acute gastric mucosal injury, and phloroglucinol, a smooth muscle relaxant, has been reported to possess anti-oxidative properties. In this study, we explored the effect of phloroglucinol on ethanol-induced gastric mucosal injury and the possible underlying mechanisms. The rat model of gastric mucosal injury was induced by oral administration of acidified ethanol, and the gastric tissues were collected for analysis of gastric ulcer index (UI), cellular apoptosis, anti-O(2) Ë or OHË formation activity, malondialdehyde (MDA) content, and the activities of myeloperoxidase (MPO), catalase and glutathione peroxidase. The results showed that acute administration of ethanol significantly increased gastric UI concomitantly with the increased cellular apoptosis, MDA contents, MPO activity as well as the decreased activities of catalase and anti-O(2) Ë or OHË formation, which was reversed by pretreatment with phloroglucinol. Although ethanol treatment significantly decreased the activity of glutathione peroxidase, pretreatment with phloroglucinol did not significantly affect the activity of the same. The results suggest that phloroglucinol could protect the gastric mucosa against ethanol-induced injury, which is related to inhibiting the MPO activity and increasing the catalase activity in the gastric tissues.
