Search

The thermal degradation of gracilaria in nitrogen was studied by thermogravimetry analysis (TG). The results indicate that the degradation of gracilaria in nitrogen is one-step reaction, and the degradation temperatures increase with heating rates (B). Experimentally, the initial degradation temperature (T0) is 0.928B+211.1, the temperature at the maximum degradation rate (Tp) is 0.958B+271.8 and the final degradation temperature (Tf ) is 0.693B+360.8. Cp and Cf, the degradation rates at Tp and Tf, are not affected by B, and their average values are (30.27 ± 3.65)% and (52.0 ± 3.67)%, respectively. The peak height on a differential thermogravimetry (DTG) curve (Rp), increases with B, Rp=0.440B-0.520. The peak width on DTG curve (Tf-T0) decreases with B, Tf - T0 = -0.235B+149.7. The reaction activation energy (E) and frequency factor (A) vary with the increasing of degree of decomposition. The values of E and A increase obviously during the initial stage of the reaction, then keep relatively steady, and decrease during the last stage. The velocity constants (k) of the thermal degradation increase with the reaction temperature. [ABSTRACT FROM AUTHOR]

In this paper, ordered arrays of various ZnO nanostructures were fabricated on both Si and p-GaN substrates via a hydrothermal process by the self-assembled nanosphere lithography (NSL). The morphology and orientation evolution of ZnO nanostructures were well-monitored by varying seed-layer-thickness, solution concentration, and underlying substrate. On this basis, the heterojunction light emitting diode (LED) based on the highly oriented ZnO nanocone array on the p-GaN substrate was fabricated and studied in detail. It is found that the ZnO nanostructure-based LED exhibits a much stronger ultraviolet (UV) emission peaked at 388 nm compared with its counterparts based on ZnO film, which is attributed to the low density of interfacial defects, improved carrier injection efficiency through the nano-sized junction, and excellent waveguiding property of the ZnO nanostructure array. [ABSTRACT FROM AUTHOR]