Damage to epitaxial GaN layer on Al2O3 by 290-MeV 238U32+ ions irradiation

Micro-structural characteristics and electrical properties of an n-type GaN epilayer on Al₂O₃ irradiated by 290-MeV ²³⁸U³²⁺ ions to various fluences were investigated using atomic force microscopy (AFM), scanning electron microscopy (SEM), high-resolution X-ray diffraction (HRXRD), and Raman scattering spectroscopy. AFM images show that the nano-hillocks generated, and the diameter and density of the nano-hillocks, increase obviously with increasing ion fluence, accompanied by an increase in surface roughness. SEM images display that the Al, O, and C elements appear on the GaN surface, along with a spiral-like, layered volcanic-cone structure formed at the highest-fluence irradiation. HRXRD reveals that the dislocation density increases, as the lattices gradually expand, and that Ga₂O₃ was produced with increasing ion fluence. Raman scattering spectra show that no N and Ga vacancies were produced, the free-carrier concentration decreases, while its mobility first increases and then exhibits a significant reduction with increasing ion fluence.

Cloning and characterization of DELLA genes in Artemisia annua

Gibberellins (GA) are some of the most important phytohormones involved in plant development. DELLA proteins are negative regulators of GA signaling in many plants. In this study, the full-length cDNA sequences of three DELLA genes were cloned from Artemisia annua. Phylogenetic analysis revealed that AaDELLA1 and AaDELLA2 were located in the same cluster, but AaDELLA3 was not. Subcellular localization analysis suggested that AaDELLAs can be targeted to the nucleus and/or cytoplasm. Real-time PCR indicated that all three AaDELLA genes exhibited the highest expression in seeds. Expression of all AaDELLA genes was enhanced by exogenous MeJA treatment but inhibited by GA3 treatment. Yeast two-hybrid assay showed that AaDELLAs could interact with basic helix-loop-helix transcription factor AaMYC2, suggesting that GA and JA signaling may be involved in cross-talk via DELLA and MYC2 interaction in A. annua.

Evaluation of transdermal permeability of pentoxifylline gel: in vitro skin permeation and in vivo microdialysis using Wistar rats

The aim of the present work was to evaluate the transdermal permeability of pentoxifylline gel in vitro and in vivo. Gel was prepared with carbomer 934 as the base, and the Wistar rat was chosen as an animal model. The effects of percutaneous enhancers on the transdermal permeability of pentoxifylline gel were investigated by in vitro permeation experiments. Cumulative permeation at different times was determined by HPLC. 3% Azone and 5% propylene glycol were used as collaborative enhancers in an optimal formulation. Topical concentrations at different times were measured by microdialysis in vivo. The transdermal process of pentoxifylline fits to a zero-order kinetic equation, and its release profile remains of the zero-order despite the addition of enhancers. In addition, a good in-vitro-in-vivo correlation was achieved.