Fabrication of a vertically-stacked passive-matrix micro-LED array structure for a dual color display.

We report a color tunable display consisting of two passive-matrix micro-LED array chips. The device has combined vertically stacked blue and green passive-matrix LED array chips sandwiched by a transparent bonding material. We demonstrate that vertically stacked blue and green micro-pixels are independently controllable with operation of four color modes. Moreover, the color of each pixel is tunable in the entire wavelength from the blue to green region (450 nm - 540 nm) by applying pulse-width-modulation bias voltage. This study is meaningful in that a dual color micro-LED array with a vertically stacked subpixel structure is realized.

Ag nanoparticles-embedded surface plasmonic InGaN-based solar cells via scattering and localized field enhancement.

Ag nanoparticles are embedded in intentionally etched micro-circle p-GaN holes by means of a thermal agglomeration process to enhance the light absorption efficiency in InGaN/GaN multi-quantum-well (MQW) solar cells. The Ag nanoparticles are theoretically and experimentally verified to generate the plasmon light scattering and the localized field enhancement near the MQW absorption layer. The external quantum efficiency enhancement at a target wavelength region is demonstrated by matching the plasmon resonance of Ag nanoparticles, resulting in a Jsc improvement of 9.1%. Furthermore, the Ag-nanoparticle-embedded InGaN solar cell is effectively fabricated considering the carrier extraction that more than 70% of F.F. and 2.2 V of high Voc are simultaneously attained.

Size-controlled InGaN/GaN nanorod LEDs with an ITO/graphene transparent layer.

We introduce ITO on graphene as a current-spreading layer for separated InGaN/GaN nanorod LEDs for the purpose of passivation-free and high light-extraction efficiency. Transferred graphene on InGaN/GaN nanorods effectively blocks the diffusion of ITO atoms to nanorods, facilitating the production of transparent ITO/graphene contact on parallel-nanorod LEDs, without filling the air gaps, like a bridge structure. The ITO/graphene layer sufficiently spreads current in a lateral direction, resulting in uniform and reliable light emission observed from the whole area of the top surface. Using KOH treatment, we reduce series resistance and reverse leakage current in nanorod LEDs by recovering the plasma-damaged region. We also control the size of the nanorods by varying the KOH treatment time and observe strain relaxation via blueshift in electroluminescence. As a result, bridge-structured LEDs with 8 min of KOH treatment show 15 times higher light-emitting efficiency than with 2 min of KOH treatment.

Size-controlled InGaN/GaN nanorod array fabrication and optical characterization.

We demonstrate a cost-effective top-down approach for fabricating InGaN/GaN nanorod arrays using a wet treatment process in a KOH solution. The average diameter of the as-etched nanorods was effectively reduced from 420 nm to 180 nm. The spatial strain distribution was then investigated by measuring the high-resolution cathodoluminescence directly on top of the nanorods. The smaller nanorods showed a higher internal quantum efficiency and lower potential fluctuation, which can subsequently be exploited for high-efficiency photonic devices.

Efficiency improvement in InGaN-based solar cells by indium tin oxide nano dots covered with ITO films.

InGaN based MQW solar cells have been fabricated with 4 different transparent top electrode structures: (1)- ITO 200 nm, (2)-ITO nano dots only, (3)-ITO nano dots on ITO 50 nm and (4)-ITO nano dots on ITO 100 nm. The solar cell with the ITO 50 nm on ITO nano dots under AM 1.5 conditions showed the best results: 2.3 V for V(oc), 0.69 mA/cm(2) for J(sc), 41.8% for peak EQE, and 0.91% for conversion efficiency. Efficiency improvement was possible due to the decreased reflectance achieved by the ITO nano dots covered with an ITO film with optimized thickness.

Efficiency improvement in InGaN-based solar cells by indium tin oxide nano dots covered with ITO films.

InGaN based MQW solar cells have been fabricated with 4 different transparent top electrode structures: (1)- ITO 200 nm, (2)-ITO nano dots only, (3)-ITO nano dots on ITO 50 nm and (4)-ITO nano dots on ITO 100 nm. The solar cell with the ITO 50 nm on ITO nano dots under AM 1.5 conditions showed the best results: 2.3 V for V(oc), 0.69 mA/cm(2) for J(sc), 41.8% for peak EQE, and 0.91% for conversion efficiency. Efficiency improvement was possible due to the decreased reflectance achieved by the ITO nano dots covered with an ITO film with optimized thickness.

Valve Sparing Aortic Root Replacement in Children with Loeys-Dietz Syndrome.

Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder that is characterized by aggressive arterial and aortic disease, often involving the formation of aortic aneurysms. We describe the cases of two children with LDS who were diagnosed with aortic root aneurysms and successfully treated by valve-sparing aortic root replacement (VSRR) with a Valsalva graft. VSRR is a safe and suitable operation for children that avoids prosthetic valve replacement.

Venovenous Extracorporeal Membrane Oxygenation for Postoperative Acute Respiratory Distress Syndrome.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) has recently attracted interest as a treatment for severe acute respiratory distress syndrome (ARDS). However, the outcomes of this procedure in post-surgical settings have not yet been characterized. In this study, we evaluated the outcomes of ECMO in patients with severe postoperative ARDS. METHODS: From January 2007 to December 2012, a total of 69 patients (aged 58.3±11.5 years, 23 females) who underwent venovenous ECMO to treat severe postoperative ARDS were reviewed. Of these patients, 22 (31.9%) had undergone cardiothoracic surgery, 32 (46.4%) had undergone liver transplantation, and 15 (21.7%) had undergone other procedures. RESULTS: Thirty-four patients (49.3%) were successfully weaned from ECMO, while the other 35 patients (50.7%) died on ECMO support. Among the 34 patients who were successfully weaned from ECMO, 21 patients (30.4%) eventually died before discharge from the hospital, resulting in 13 hospital survivors (18.8%). Multivariable analysis showed that the duration of pre-ECMO ventilation was a significant independent predictor of death (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.29 to 3.90; p=0.004), whereas the concomitant use of continuous venovenous hemodialysis (CVVHD) was associated with improved survival (OR, 0.55; 95% CI, 0.31 to 0.97; p=0.038). CONCLUSION: Although the overall survival rate of patients treated with ECMO for postoperative ARDS was unfavorable, ECMO offered an invaluable opportunity for survival to patients who would not have been expected to survive using conventional therapy. CVVHD may be beneficial in improving the outcomes of such patients, whereas a prolonged duration of pre-ECMO ventilator support was associated with poor survival.

Translocation of the aortic arch with norwood procedure for hypoplastic left heart syndrome variant with circumflex retroesophageal aortic arch.

Retroesophageal aortic arch, in which the aortic arch crosses the midline behind the esophagus to the contralateral side, is a rare form of vascular anomaly. The complete form may cause symptoms by compressing the esophagus or the trachea and need a surgical intervention. We report a rare case of a hypoplastic left heart syndrome variant with the left retroesophageal circumflex aortic arch in which the left aortic arch, retroesophageal circumflex aorta, and the right descending aorta with the aberrant right subclavian artery encircle the esophagus completely, thus causing central bronchial compression. Bilateral pulmonary artery banding and subsequent modified Norwood procedure with extensive mobilization and creation of the neo-aorta were performed. As a result of the successful translocation of the aorta, the airway compression was relieved. The patient underwent the second-stage operation and is doing well currently.

Tuberculous aortitis complicated with pseudoaneurysm formation in the descending thoracic aorta: a case report.

A 51-year-old male with sustained fever was diagnosed with military tuberculosis and tuberculous aortitis complicated with pseudoaneurysm formation at the proximal descending aorta. A follow-up computed tomography evaluation showed an increased size of the pseudoaneurysm in this area, suggestive of a contained rupture. Consequently, the patient underwent emergency excision and replacement of the aorta using a left heart bypass. The patient was discharged without postoperative complications on post-operative day 12. During the one-year follow-up period, the patient was free of any complications or recurrence of tuberculosis. We report a case of pseudoaneurysm of the descending aorta that was successfully surgically repaired.