The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

The effect of strongly-imbalanced carrier concentration and mobility on efficiency droop is studied by comparing the onset voltage of high injection, the onset current density of the droop, and the magnitude of the droop, as well as their temperature dependence, of GaInN-based blue and green light-emitting diodes (LEDs). An n-to-p asymmetry factor is defined as sigma(n)/sigma(p), and was found to be 17.1 for blue LEDs and 50.1 for green LEDs. Green LEDs, when compared to blue LEDs, were shown to enter the high-injection regime at a lower voltage, which is attributed to their less favorable p-type transport characteristics. Green LEDs, with lower hole concentration and mobility, have a lower onset current density of the efficiency droop and a higher magnitude of the efficiency droop when compared to blue LEDs. The experimental results are in quantitative agreement with the imbalanced carrier transport causing the efficiency droop, thus providing guidance for alleviating the phenomenon of efficiency droop.114sciescopu

Subcutaneous Sacrococcygeal Myxopapillary Ependymoma in Asian Female:A Case Report

Subcutaneous sacrococcygeal myxopapillary ependymoma is extremely rare tumor that has a tendency to develop in children and adolescents. There have been several case reports and sporadic reports in the literature. However, no case has been reported in an Asian patient, to the best of our knowledge. We describe a 25-year-old Asian female patient with a subcutaneous sacrococcygeal myxopapillary ependymoma that had been clinically diagnosed as a pilonidal cyst. The tumor was treated successfully by surgical excision and the patient is doing well without evidence of local recurrence or distant metastasis at 2 years after surgery.

Spatial-temporal Vehicle Re-identification

Vehicle re-identification (ReID) in a large-scale camera network is important in public safety, traffic control, and security. However, due to the appearance ambiguities of vehicle, the previous appearance-based ReID methods often fail to track vehicle across multiple cameras. To overcome the challenge, we propose a spatial-temporal vehicle ReID framework that estimates reliable camera network topology based on the adaptive Parzen window method and optimally combines the appearance and spatial-temporal similarities through the fusion network. Based on the proposed methods, we performed superior performance on the public dataset (VeRi776) by 99.64% of rank-1 accuracy. The experimental results support that utilizing spatial and temporal information for ReID can leverage the accuracy of appearance-based methods and effectively deal with appearance ambiguities.Comment: 10 pages, 6 figure

Enhanced overall efficiency of GaInN-based light-emitting diodes with reduced efficiency droop by Al-composition-graded AlGaN/GaN superlattice electron blocking layer

AlxGa1-xN/GaN superlattice electron blocking layers (EBLs) with gradually decreasing Al composition toward the p-type GaN layer are introduced to GaInN-based high-power light-emitting diodes (LEDs). GaInN/GaN multiple quantum well LEDs with 5- and 9-period Al-composition-graded AlxGa1-xN/GaN EBL show comparable operating voltage, higher efficiency as well as less efficiency droop than LEDs having conventional bulk AlGaN EBL, which is attributed to the superlattice doping effect, enhanced hole injection into the active region, and reduced potential drop in the EBL by grading Al compositions. Simulation results reveal a reduction in electron leakage for the superlattice EBL, in agreement with experimental results. (C) 2013 AIP Publishing LLC.open1133sciescopu

Massive transfusion protocol: the reason it is necessary

Objective. The purpose of this study is to identify problems of emergency transfusion at the bedside and to determine need for massive transfusion protocol. Methods. We included patients who met the criteria for “trauma team activation” and were admitted to division of trauma. The amount of blood product transfused in each unit was investigated for balanced transfusion. We also investigated the compliance with assessment of blood consumption score. The correlation between the time elapsed from patient visit to first transfusion order and time elapsed from first transfusion order to transfusion start was analyzed. Finally, we investigated various factors which serve to influence the decision-making process regarding early transfusion order. Results. Ratio of packed Red blood cells (pRBC): Fresh frozen plasma (FFP) was well-balanced, but platelet transfusion done was much lower than pRBC and FFP in emergency room. The application of emergency blood release did not match the criteria of assessment of blood consumption (ABC) score. The time from the first transfusion order to the transfusion start was found to be constant irrespective of time from patient visit to first transfusion order. And, the time from the first transfusion order to transfusion start did not differ significantly among patients with early transfusion order and delayed transfusion order. Only systolic blood pressure of < 90 mmHg was identified as a major predictor for early transfusion order. Conclusion. Balanced transfusion is not easy and emergency transfusion could be delayed at the bedside. Integrated and systematic structures for massive transfusion protocol would be invaluable and indispensable

Polyelectrolyte complex micelles by self-assembly of polypeptide-based triblock copolymer for doxorubicin delivery

AbstractPolyelectrolyte complex micelles were prepared by self-assembly of polypeptide-based triblock copolymer as a new drug carrier for cancer chemotherapy. The triblock copolymer, poly(l-aspartic acid)-b-poly(ethylene glycol)-b-poly(l-aspartic acid) (PLD-b-PEG-b-PLD), spontaneously self-assembled with doxorubicin (DOX) via electrostatic interactions to form spherical micelles with a particle size of 60–80 nm (triblock ionomer complexes micelles, TBIC micelles). These micelles exhibited a high loading capacity of 70% (w/w) at a drug/polymer ratio of 0.5 at pH 7.0. They showed pH-responsive release patterns, with higher release at acidic pH than at physiological pH. Furthermore, DOX-loaded TBIC micelles exerted less cytotoxicity than free DOX in the A-549 human lung cancer cell line. Confocal microscopy in A-549 cells indicated that DOX-loaded TBIC micelles were transported into lysosomes via endocytosis. These micelles possessed favorable pharmacokinetic characteristics and showed sustained DOX release in rats. Overall, these findings indicate that PLD-b-PEG-b-PLD polypeptide micelles are a promising approach for anti-cancer drug delivery

Preparation and evaluation of solid-self-emulsifying drug delivery system containing paclitaxel for lymphatic delivery

Solid-self-emulsifying drug delivery system (S-SEDDS) of paclitaxel (Ptx) was developed by the spray drying method with the purpose of improving the low bioavailability (BA) of Ptx. 10% oil (ethyl oleate), 80% surfactant mixture (Tween 80: Carbitol, 90: 10, w/w), and 10% cosolvent (PEG 400) were chosen according to their solubilizing capacity. The mean droplet size, zeta potential, and encapsulation efficiency of the prepared S-SEDDS were 16.9 &plusmn; 1.53 nm, 12.5 &plusmn; 1.66 mV, and 56.2 &plusmn; 8.1%, respectively. In the S-SEDDS, Ptx presents in the form of molecular dispersion in the emulsions or is distributed in an amorphous state or crystalline with very small size. The prepared S-SEDDS formulation showed 70 and 75% dissolution in 60 and 30 min in dissolution medium pH 1.2 and 6.8, respectively. Significant increase (P &le; 0.05) in the peak concentration (C m a x), the area under the curve (A U C 0 - &infin;), and the lymphatic targeting efficiency of Ptx was observed after the oral administration of the Ptx-loaded S-SEDDS to rats (20 mg/kg as Ptx). Our research suggests the prepared Ptx-loaded S-SEDDS can be a good candidate for the enhancement of BA and targeting drug delivery to the lymphatic system of Ptx

Optical repumping of triplet PP-states enhances magneto-optical trapping of ytterbium atoms

Radiative decay from the excited $^1P_1$ state to metastable $^3P_2$ and $^3P_0$ states is expected to limit attainable trapped atomic population in a magneto-optic trap of ytterbium (Yb) atoms. In experiments we have carried out with optical repumping of $^3P_{0,2}$ states to $^3P_1$, we observe enhancement of trapped atoms yield in the excited $^1P_1$ state. The individual decay rate to each metastable state is measured and the results show an excellent agreement with the theoretical values.Comment: 5 pages, 5 figure

Energy bandgap variation in oblique angle-deposited indium tin oxide

Indium tin oxide (ITO) thin films deposited using the oblique angle deposition (OAD) technique exhibit a strong correlation between structural and optical properties, especially the optical bandgap energy. The microstructural properties of ITO thin films are strongly influenced by the tilt angle used during the OAD process. When changing the tilt angle, the refractive index, porosity, and optical bandgap energy of ITO films also change due to the existence of a preferential growth direction at the interface between ITO and the substrate. Experiments reveal that the ITO film&apos;s optical bandgap varies from 3.98 eV (at normal incident deposition) to 3.87 eV (at a 60 tilt angle). 2-10 OAD is generally associated with physical vapor deposition of thin films (prepared through, e.g., electron-beam or thermal evaporation), in which the material vapor flux arrives at the substrate surface at an oblique angle. Tilted and columnar nanostructures are the most typical morphological characteristics of OAD thin films. 1, Deposition of ITO films on soda lime glass and silicon substrates was conducted with an E-beam evaporation system using an ITO source composed of 90 wt. % In 2 O 3 and 10 wt. % SnO 2 . Prior to the deposition, all substrates were sequentially cleaned in acetone, isopropyl alcohol, and deionized water and dried under nitrogen flow. The apparatus used in our OAD process has a sample stage (onto which the substrate was loaded), allowing for control of the polarangle as well as azimuthal rotation. The distance between the substrate and evaporation source material was approximately 50 cm. The sample stage was positioned at a fixed polar angle so that the substrate had a certain tilt angle (deposition angle) with respect to the vapor-flux direction. The chamber was evacuated to a pressure less than 1.0 Â 10 À6 Torr, and substrates were held at room temperature. During the deposition, the deposition rate was held steady at 0.2 nm/s, as measured by a quartz crystal monitor inside the chamber. The low growth rate on the substrate at higher deposition angles 11 was compensated by increasing the deposition time to keep the same film thickness for all samples. The ITO films unloaded from the E-beam evaporation system were annealed in O 2 at 550 C for 1 min in a rapid thermal annealing system in order to compensate a deficiency of oxygen in the films. Optical transmittance measurements of the ITO thin films were performed using non-polarized light at normal incidence in the wavelength range of 280-780 nm using a JASCO UV-VIS spectrophotometer. The refractive index (n) was measured using a spectroscopic ellipsometry system, in which absorption is neglected during fitting. A film thickness was measured first by ellipsometry, and then confirmed by a scanning electron microscope (SEM, Hitachi S-4300). The porosity and optical bandgap energy values of the ITO thin films were calculated using theoretical models developed by Poxson et al. 11 and Tauc, 13 respectively. The morphological features of the films were examined using an optical microscope and SEM. Several regions on the sample surface were investigated in order to produce representative images. Furthermore, the crystallographic structure of the ITO thin films was examined by X-ray diffraction (XRD) using the nickel-filtered Ka emission of copper. Figures 1(a) and 1(b) show optical microscope images of the ITO films deposited on (a) silicon (Si) and (b) glass substrates at tilt angles ranging from 0 to 60 . A color difference of the ITO thin films is clearly evident, which can result from a variation in thickness and/or refractive index. In this case, because the thicknesses of all films are the same (about 210 nm), the variation in refractive index is the cause for the color variation. It is well known that the refractive index of a a