28 research outputs found
Temperature-dependent steady and transient emission properties of InGaN/GaN multiple quantum well nanorods
We observed different temperature-dependent behaviors of steady and transient
emission properties in dry-etched InGaN/GaN multiple-quantum-well (MQW)
nanorods and the parent MQWs. To clarify the impacts of nanofabrication on the
emission properties, time-resolved photoluminescence spectra were recorded at
various temperatures with carrier density in different regimes. The confinement
of carrier transport was observed to play an important role to the emission
properties in nanorods, inducing different temperature-dependent
photoluminescence decay rates between the nanorods and MQWs. Moreover, together
with other effects, such as surface damages and partial relaxation of the
strain, the confinement effect causes faster recombination of carriers in
nanorods.Comment: 13 pages, 4 figure
A Prediction Rule to Identify Severe Cases among Adult Patients Hospitalized with Pandemic Influenza A (H1N1) 2009
The purpose of this study was to establish a prediction rule for severe illness in adult patients hospitalized with pandemic influenza A (H1N1) 2009. At the time of initial presentation, the baseline characteristics of those with severe illness (i.e., admission to intensive care unit, mechanical ventilation, or death) were compared to those of patients with non-severe illnesses. A total of 709 adults hospitalized with pandemic influenza A (H1N1) 2009 were included: 75 severe and 634 non-severe cases. The multivariate analysis demonstrated that altered mental status, hypoxia (PaO2/FiO2 †250), bilateral lung infiltration, and old age (℠65 yr) were independent risk factors for severe cases (all P < 0.001). The area under the ROC curve (0.834 [95% CI, 0.778-0.890]) of the number of risk factors were not significantly different with that of APACHE II score (0.840 [95% CI, 0.790-0.891]) (P = 0.496). The presence of ℠2 risk factors had a higher sensitivity, specificity, positive predictive value and negative predictive value than an APACHE II score of ℠13. As a prediction rule, the presence of ℠2 these risk factors is a powerful and easy-to-use predictor of the severity in adult patients hospitalized with pandemic influenza A (H1N1) 2009
32 Ă 32 Pixelated High-Power Flip-Chip Blue Micro-LED-on-HFET Arrays for Submarine Optical Communication
This work proposes the use of integrated high-power InGaN/GaN multiple-quantum-well flip-chip blue micro light-emitting diode (ÎŒ-LED) arrays on an AlGaN/GaN-based heterojunction field-effect transistor (HFET), also known as a high electron mobility transistor (HEMT), for various applications: underwater wireless optical communication (UWOC) and smart lighting. Therefore, we demonstrate high-power ÎŒ-LED-on-HEMT arrays that consist of 32 Ă 32 pixelated ÎŒ-LED arrays and 32 Ă 32 pixelated HEMT arrays and that are interconnected by a solder bump bonding technique. Each pixel of the ÎŒ-LED arrays emits light in the HEMT on-state. The threshold voltage, the off-state leakage current, and the drain current of the HEMT arrays are â4.6 V, <~1.1 Ă 10â9 A at gate-to-source voltage (VGS) = â10 V, and 21 mA at VGS = 4 V, respectively. At 12 mA, the forward voltage and the light output power (LOP) of ÎŒ-LED arrays are ~4.05 V and ~3.5 mW, respectively. The LOP of the integrated ÎŒ-LED-on-HEMT arrays increases from 0 to ~4 mW as the VGS increases from â6 to 4 V at VDD = 10 V. Each pixel of the integrated ÎŒ-LEDs exhibits a modulated high LOP at a peak wavelength of ~450 nm, showing their potential as candidates for use in UWOC
Stretchable, alternating-current-driven white electroluminescent device based on bilayer-structured quantum-dot-embedded polydimethylsiloxane elastomer
In this work, we demonstrate neutral/pure/cool white light due to color conversion from quantum dot (QD)-embedded, polydimethylsiloxane (PDMS)-based alternating-current-driven electroluminescent (ACEL) devices. White light generation is achieved by the spontaneously formed bilayer-structure emitting layer (b-EML) comprising QDs embedded in PDMS containing Cu-doped zinc sulfide (ZnS:Cu) particles (EL emitting layer), without ZnS:Cu (color conversion layer). Red light is generated by CdSe/CdZnS QDs, which partially absorbs electrically excited blue-green EL. This study examines the use of spontaneously formed b-EML as a means of alleviating the problems resulting from QD aggregation in PDMS and its effects on electro-optical performance of ACEL devices under stretching conditions. © The Royal Society of Chemistry.1