The effect of an electron blocking layer (EBL) on the efficiency droop in InGaN/GaN multiple quantum well light-emitting diodes (LEDs) is investigated. At low current density, the LEDs with a p-AlGaN EBL show a higher external quantum efficiency (EQE) than LEDs without an EBL. However, the EQE of LEDs without an EBL is higher than LEDs with an EBL as injection current density is increased. The improved EQE of LEDs without an EBL at high current density is attributed to the increased hole injection efficiency.

We demonstrate the surface plasmon-enhanced blue light-emitting diodes (LEDs) using Ag nanoparticles embedded in p-GaN. A large increase in optical output power of 38% is achieved at an injection current of 20 mA due to an improved internal quantum efficiency of the LEDs. The enhancement of optical output power is dependent on the density of the Ag nanoparticles. This improvement can be attributed to an increase in the spontaneous emission rate through resonance coupling between the excitons in multiple quantum wells and localized surface plasmons in Ag nanoparticles embedded in p-GaN.

Block copolymers that combine a side-group liquid crystalline polymer (SGLCP) block and a pH-responsive hydrophilic block, poly(acrylic acid) (PAA), are shown to confer pH-dependent anchoring of the director orientation at the aqueous/LC interface. The SGLCP block, poly-(4-cyanobiphenyl-4-oxyundecylacrylate), was chosen based on its ability to influence the director field of the 5CB (4-cyano-4 0 -pentylbiphenyl). At low pH the PAA block collapses and the inherent, planar alignment tendency of 5CB at a water interface prevails. As pH increases, the polyelectrolyte block becomes increasingly charged and expands, producing a change to homeotropic anchoring. The change in anchoring occurs as quickly as the buffer can be changed (within $2 s) and is reversible, with a response that is repeatable over as many cycles as were tested (approximately 20 cycles). The polymer-mediated anchoring persists for 6 days, indicating that the SGLCP block secures the self-assembled layer on the 5CB, even under conditions that cause repulsive interactions among the PAA blocks. Thus, SGLCP blocks can translate conformational changes of a responsive hydrophilic block into rapid, reversible changes in the director field.

Objective: To evaluate whether mandibular setback surgery (MSS) for Class III patients would produce gradients of three-dimensional (3D) soft tissue changes in the vertical and transverse aspects. Materials and Methods: The samples consisted of 26 Class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalograms and 3D facial scan images were taken before and 6 months after MSS, and changes in landmarks and variables were measured using a Rapidform 2006. Paired and independent t-tests were performed for statistical analysis. Results: Landmarks in the upper lip and mouth corner (cheilion, Ch) moved backward and downward (respectively, cupid bow point, 1.0 mm and 0.3 mm, P , .001 and P , .01; alar curvature-Ch midpoint, 0.6 mm and 0.3 mm, both P , .001; Ch, 3.4 mm and 0.8 mm, both P , .001). However, landmarks in stomion (Stm), lower lip, and chin moved backward (Stm, 1.6 mm; labrale inferius [Li], 6.9 mm; LLBP, 6.9 mm; B9, 6.7 mm; Pog9, 6.7 mm; Me9, 6.6 mm; P , .001, respectively). Width and height of upper and lower lip were not altered significantly except for a decrease of lower vermilion height (Stm-Li, 1.7 mm, P , .001). Chin height (B9-Me9) was decreased because of backward and upward movement of Me9 (3.1 mm, P , .001). Although upper lip projection angle and Stm-transverse projection angle became acute (Ch Rt -Ls-Ch Lt , 5.7u; Ch Rt -Stm-Ch Lt , 6.4u, both P , .001) because of the greater backward movement of Ch than Stm, lower lip projection angle and Stm-vertical projection angle became obtuse (Ch Rt -Li-Ch Lt , 10.8u; LsStm-Li, 23.5u, both P , .001) because of the larger backward movement of Li than labrale superius (Ls). Conclusions: Three-dimensional soft tissue changes in Class III patients after MSS exhibited increased gradients from upper lip and lower lip to chin as well as from Stm to Ch. (Angle Orthod. 2010;80:896-903.)

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