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This study investigates optical properties and carrier dynamics of InGaN-based light-emitting diodes grown on cone-shaped patterned sapphire (CSPS) and planar sapphire substrates. Edge-type threading dislocations were dramatically reduced in InGaN multiple quantum wells (MQWs) on CSPS substrates compared to the case of planar substrates. We observed a smaller Stokes shift and enhanced quantum efficiency for CSPS substrates. From time-resolved optical analysis, we found that the non-radiative (radiative) recombination rate of MQWs on CSPS is lower (higher) than that of MQWs on planar substrates, which is consistent with improved crystal quality (strain relaxation) of the MQWs on CSPS. [ABSTRACT FROM AUTHOR]

Abstract: Using slice patch clamp recording, we examined the effects of general anesthetic propofol (2,6-diisoprophlphenol) on dual modality of GABAA inhibition in supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs): conventional quantal synaptic transmission (IPSCs, I phasic) and persistent tonic form of inhibitory current (I tonic). Propofol (10μM) enhanced I tonic as shown by an inward shift in I holding (16.46±2.93pA, n =27) and RMS increase (from 3.37±0.21pA to 4.68±0.33pA, n =27) in SON MNCs. Propofol also prolonged the decay time of IPSCs with decreased IPSCs frequency but no significant changes in IPSCs amplitude. Overall, propofol (1–10μM) caused much smaller increase in mean I phasic than mean I tonic at all tested concentrations. In consistent with the enhancement of GABAA currents, propofol attenuated ongoing firing activities of SON MNCs by ∼65% of control. Selective inhibition of I phasic by a GABAA antagonist, gabazine (1μM), failed to block the propofol suppression of the firing activities, while inhibition of I tonic and I phasic by bicuculline (20μM) efficiently blocked the propofol-induced neurodepression in SON MNCs. Taken together, our results showed that propofol facilitated I tonic with marginal increase in mean I phasic, and this could be a mechanism reducing the intrinsic SON MNCs excitability during propofol anesthesia. [Copyright &y& Elsevier]