Annealing of an AlN buffer layer in N2-CO for growth of a high-quality AlN film on sapphire

The annealing of an AlN buffer layer in a carbon-saturated N2–CO gas on a sapphire substrate was investigated. The crystal quality of the buffer layer was significantly improved by annealing at 1650–1700 °C. An AlN buffer layer with a thickness of 300 nm was grown by metalorganic vapor phase epitaxy (MOVPE), and was annealed at 1700 °C for 1 h. We fabricated a 2-µm-thick AlN layer on the annealed AlN buffer layer by MOVPE. The full widths at half maximum of the (0002)- and ($10\bar{1}2$)-plane X-ray rocking curves were 16 and 154 arcsec, respectively, and the threading dislocation density was 4.7 × 108 cm−2

A preliminary study on protective effect of L-citrulline against ischemia-reperfusion induced gastric mucosal lesions in rat

Objectives: This study was designed to investigate the gastroprotective effect of L-citrulline against gastric ischemia-reperfusion injury. Materials and Methods: Sodium pentobarbital-anesthetized rats underwent occlusion of the celiac artery for 30 min, followed by 60 min of reperfusion. Sixty minutes before ischemia, L-citrulline at doses of 300, 600, 900 mg/kg was administered intragastrically. Based on this animal model of gastric ischemia-reperfusion injury, the gastroprotective effect of L-citrulline was assessed by determining and comparing the ulcerative index and the estimation of myeloperoxidase (MPO) activity and malondialdehyde (MDA) level in the gastric mucosal tissues. Moreover, the expression of inducible nitric oxide synthase (iNOS), neuronal nitric oxide synthase (nNOS), and endothelial nitric oxide synthase (eNOS) protein was also determined. Results: Intragastric administration of L-citrulline (600 and 900 mg/kg) 60 min before ischemia significantly ameliorated the gastric mucosal damage and inhibited the increase in MPO and MDA contents. Also, the increase in expression of iNOS protein was also prevented by L-citrulline. The expression of nNOS and eNOS was not affected significantly by I/R or L-citrulline. Conclusion: The results suggest that L-citrulline, administered exogenously, exhibits gastric protection by inhibition of neutrophil infiltration in rats, which may be related in prevention of the increase in iNOS activity