Investigation of Trapezoidal Well for Improving the Light Efficiency in AlGaInP-Based Light-Emitting Diodes.

We investigated high-brightness light emitting diodes appropriate for general lighting applications in terms of their optical behaviors and device performances according to the insertion of the sloped barrier between the well and the barrier and changing the sloped barrier thickness. As the sloped barrier thickness was increased from 0 to 5 nm, radiative recombination efficiency and device performances significantly improved, due to the suppression of carrier overflow by the stronger capture of carriers and the shortening of the carrier lifetime in the active region owing to the built-in quasi-electric field. At a further increase in the sloped barrier thickness to 10 nm, however, the optical and device performances started to degrade because of the loosening of the quantum confinement effect in the active region and due to the saturation of the improvement of the carrier capture by the sloped barrier region.

Holmium laser lithotripsy under direct peroral cholangioscopy by using an ultra-slim upper endoscope for patients with retained bile duct stones (with video).

BACKGROUND: Direct peroral cholangioscopy (POC) by using an ultra-slim endoscope provides direct visualization of the bile duct and allows for therapeutic intervention. Holmium laser lithotripsy can be effective for retained bile duct stones, but it requires direct visualization during the procedure for safe and effective fragmentation. Direct POC by using an ultra-slim endoscope may facilitate holmium laser lithotripsy. OBJECTIVE: To evaluate the feasibility, success rates, and complications of holmium laser lithotripsy under direct POC by using an ultra-slim endoscope for retained bile duct stones. DESIGN: Observational clinical feasibility study. SETTING: Tertiary-care referral center. PATIENTS: This study involved 13 patients with retained bile duct stones whose treatment failed by a conventional lithotripsy method involving mechanical lithotripsy. INTERVENTION: Holmium laser lithotripsy under direct POC by using an ultra-slim endoscope. MAIN OUTCOME MEASUREMENTS: Success rate of complete stone removal and procedure-related complications. RESULTS: Holmium laser lithotripsy under direct POC by using an ultra-slim endoscope was successful in 11 of 13 patients (84.6%). Although direct POC was successful, holmium laser lithotripsy failed in 2 patients because of inaccurate targeting of the laser fiber to stones. There were no procedure-related complications except one case of mild pancreatitis. LIMITATIONS: A small number of patients and no comparison with other lithotripsy systems. CONCLUSION: Holmium laser lithotripsy under direct POC by using an ultra-slim endoscope was feasible and can be a safe endoscopic management method for retained bile duct stones.

Clinical feasibility of direct peroral cholangioscopy-guided photodynamic therapy for inoperable cholangiocarcinoma performed by using an ultra-slim upper endoscope (with videos).

BACKGROUND: Photodynamic therapy (PDT) has emerged as a promising palliative treatment for inoperable cholangiocarcinoma. Cholangioscopy-guided PDT can be useful for identification of tumor margins, determination of the appropriate location for placement of the diffuser, and evaluation of the patient's response to therapy. OBJECTIVE: To evaluate the feasibility of PDT under direct peroral cholangioscopy (POC) by using an ultra-slim upper endoscope in patients with inoperable cholangiocarcinoma. DESIGN: Prospective, observational, pilot study. SETTING: Single tertiary-care referral center. PATIENTS: This study involved 9 patients with inoperable extrahepatic cholangiocarcinoma. INTERVENTION: Photofrin II was administered intravenously 48 hours before PDT. Additional PDT was performed up to 48 hours after the initial application of therapy. A successful direct POC-guided PDT was defined as advancement of the endoscope into the distal margin of the tumor and maintenance of endoscope position until PDT was completed. MAIN OUTCOME MEASUREMENTS: The clinical feasibility, usefulness, and complications of direct POC for PDT. RESULTS: Seventeen sessions of direct POC for PDT were performed in 9 patients. PDT was performed successfully in 15 of 17 sessions (88.2%) and 7 of 9 patients (77.8%). Biliary drainage under direct POC, if necessary after PDT, was possible in 100% of patients (7/7). Follow-up direct POC confirmed significant tumor ablation after PDT in 5 patients. One patient reported mild skin redness; no major procedure-related complications were observed. LIMITATIONS: Small sample size, pilot study. CONCLUSION: Direct POC-guided PDT by using an ultra-slim upper endoscope seems to be both feasible and safe in select patients with inoperable extrahepatic cholangiocarcinoma.