Porous medium is a special type of material where voids are created in a solid medium. The introduction of pores into a bulk solid can profoundly affect its physical properties and enable

The fabrication process and performance characteristics of the laser lift-off ͑LLO͒ GaN light-emitting diodes ͑LEDs͒ were investigated. The LLO-GaN LEDs were fabricated by lifting off the GaN LED wafer structure grown on the original sapphire substrate by a KrF excimer laser at 248 nm wavelength with the laser fluence of 0.6 J/cm 2 and transferring it onto a Cu substrate. The LLO-GaN LEDs on Cu show a nearly four-fold increase in the light output power over the regular LLO-LEDs on the sapphire substrate. High operation current up to 400 mA for the LLO-LEDs on Cu was also demonstrated. Based on the emission wavelength shift with the operating current data, the LLO-LEDs on Cu show an estimated improvement of heat dissipation capacities by nearly four times over the light-emitting devices on sapphire substrate. The LLO process should be applicable to other GaN-based LEDs in particular for those high light output power and high operation current devices.

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The mechanism that regulates embryonic liver morphogenesis remains elusive. Progranulin (PGRN) is postulated to play a critical role in regulating pathological liver growth. Nevertheless, the exact regulatory mechanism of PGRN in relation to its functional role in embryonic liver development remains to be elucidated. In our study, the knockdown of progranulin A (GrnA), an orthologue of mammalian PGRN, using antisense morpholinos resulted in impaired liver morphogenesis in zebrafish (Danio rerio). The vital role of GrnA in hepatic outgrowth and not in liver bud formation was further confirmed using whole-mount in situ hybridization markers. In addition, a GrnA deficiency was also found to be associated with the deregulation of MET-related genes in the neonatal liver using a microarray analysis. In contrast, the decrease in liver size that was observed in grnA morphants was avoided when ectopic MET expression was produced by co-injecting met mRNA and grnA morpholinos. This phenomenon suggests that GrnA might play a role in liver growth regulation via MET signaling. Furthermore, our study has shown that GrnA positively modulates hepatic MET expression both in vivo and in vitro. Therefore, our data have indicated that GrnA plays a vital role in embryonic liver morphogenesis in zebrafish. As a result, a novel link between PGRN and MET signaling is proposed.

In this research nanoporous structures on p-type GaN:Mg and n-type GaN:Si surfaces were fabricated through a photoelectrochemical (PEC) oxidation and an oxide-removing process. The photoluminescence (PL) intensities of GaN and InGaN∕GaN multi-quantum-well (MQW) structures were enhanced by forming this nanoporous structure to increase light extraction efficiency. The PL emission peaks of an MQW active layer have a blueshift phenomenon from 465.5nm (standard) to 456.0nm (nanoporous) measured at 300K which was caused by partially releasing the compressive strain from the top GaN:Mg layers. The internal quantum efficiency could be increased by a partial strain release that induces a lower piezoelectric field in the active layer. The thermal activation energy of a nanoporous structure (85meV) is higher than the standard one (33meV) from a temperature dependent PL measurement. The internal quantum efficiency and light extraction efficiency of an InGaN∕GaN MQW active layer are significantly enhanced by this nanoporous GaN:Mg surface, and this PEC treated nanoporous structure is suitable for high-power lighting applications.