Utilization of 2D materials in aqueous zinc ion batteries for safe energy storage devices.

Aqueous rechargeable battery has been an intense topic of research recently due to the significant safety issues of conventional Li-ion batteries (LIBs). Amongst the various candidates of aqueous batteries, aqueous zinc ion batteries (AZIBs) hold great promise as a next generation safe energy storage device due to its low cost, abundance in nature, low toxicity, environmental friendliness, low redox potential, and high theoretical capacity. Yet, the promise has not been realized due to their limitations, such as lower capacity compared to traditional LIB, dendrite growth, detrimental degradation of electrode materials structure as ions intercalate/de-intercalate, and gas evolution/corrosion at the electrodes, which remains a significant challenge.

Pulmonary Rehabilitation Is Associated With Decreased Exacerbation and Mortality in Patients With COPD: A Nationwide Korean Study.

Background: Poor uptake to pulmonary rehabilitation (PR) is still challenging around the world. There have been few nationwide studies investigating whether PR impacts patient outcomes in COPD. We investigated the change of annual PR implementation rate, medical costs, and COPD outcomes including exacerbation rates and mortality between 2015 and 2019.

Near-UV light emitting diode with on-chip photocatalysts for purification applications.

A new design for light-emitting diodes (LEDs) with on-chip photocatalysts is presented for purification applications. An array of disk-shaped TiO, with a diameter of several hundred nanometers, combined with SiO pedestals was fabricated directly on the surface of an InGaN-based near-ultraviolet (UV) LED using a dry etching process. The high refractive-index contrast at the boundary and the circular shape can effectively confine the near-UV light generated from the LED through multiple internal reflections inside the TiO nanodisks.

Improved efficiency of InGaN/GaN light-emitting diodes with perpendicular magnetic field gradients.

The effect of magnetic fields on the optical output power of flip-chip light-emitting diodes (LEDs) with InGaN/GaN multiple quantum wells (MQWs) was investigated. Films and circular disks comprising ferromagnetic cobalt/platinum (Co/Pt) multilayers were deposited on a p-ohmic reflector to apply magnetic fields in the direction perpendicular to the MQWs of the LEDs. At an injection current of 20 mA, the ferromagnetic Co/Pt multilayer film increased the optical output power of the LED by 20% compared to an LED without a ferromagnetic Co/Pt multilayer.

Magnetically enhanced luminescence of CdSe/ZnS quantum dot light-emitting diodes using circular ferromagnetic Co/Pt multilayer disks.

We investigate the effect of a magnetic field on red, green, and blue CdSe/ZnS quantum dot light-emitting diodes (QDLEDs). Circular multilayer ferromagnetic cobalt/platinum (Co/Pt) disks are deposited on a MgF layer covering an Al electrode, and a perpendicular magnetic field is applied to the QDs in the active layer. Carriers injected into the active layer are then trapped and efficiently recombined inside the QDs because of strong carrier localization caused by the perpendicular magnetic field.

Polarized ultraviolet emitters with Al wire-grid polarizers fabricated by solvent-assisted nanotransfer process.

Polarized ultraviolet (UV) emitters are essential for various applications, such as photoalignment devices for liquid crystals, high-resolution imaging devices, highly sensitive sensors, and steppers. To increase the high polarization ratio (PR) of a UV emitter, the grating period should be decreased than that of the visible emitter. However, the fabrication of the short period grating directly on UV emitters is still limited.

Enhanced performance of InGaN/GaN MQW LED with strain-relaxing Ga-doped ZnO transparent conducting layer.

We report the enhanced optical and electrical properties of InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) with strain-relaxing Ga-doped ZnO transparent conducting layers (TCLs). Ga-doped ZnO was epitaxially grown on p-GaN by metal-organic chemical vapor deposition. The optical output power of a LED with a 500-nm- thick-Ga-doped ZnO TCL increased by 30.

Room temperature polariton lasing in quantum heterostructure nanocavities.

Ultralow-threshold coherent light emitters can be achieved through lasing from exciton-polariton condensates, but this generally requires sophisticated device structures and cryogenic temperatures. Polaritonic nanolasers operating at room temperature lie on the crucial path of related research, not only for the exploration of polariton physics at the nanoscale but also for potential applications in quantum information systems, all-optical logic gates, and ultralow-threshold lasers. However, at present, progress toward room temperature polariton nanolasers has been limited by the thermal instability of excitons and the inherently low quality factors of nanocavities.

Phenotypes of Severe Cutaneous Adverse Reactions Caused by Nonsteroidal Anti-inflammatory Drugs.

Purpose: Nonsteroidal anti-inflammatory drugs (NSAIDs) are common cause of severe cutaneous adverse reactions (SCARs). The present study aimed to investigate the characteristics of SCARs induced by NSAIDs in the Korean SCAR registry.

Methods: A retrospective survey of NSAID-induced SCARs recorded between 2010 and 2015 at 27 university hospitals in Korea was conducted.

Crystal-Structure-Dependent Piezotronic and Piezo-Phototronic Effects of ZnO/ZnS Core/Shell Nanowires for Enhanced Electrical Transport and Photosensing Performance.

We report the crystal-structure-dependent piezotronic and piezo-phototronic effects of ZnO/ZnS core/shell nanowires (CS NWs) having different shell layer crystalline structures. The wurtzite (WZ) ZnO/WZ ZnS CS NWs showed higher electrical transport and photosensing properties under external strain than the WZ ZnO/zinc blende (ZB) ZnS CS NWs. The WZ ZnO/WZ ZnS CS NWs under a compressive strain of -0.

Radial multi-quantum well ZnO nanorod arrays for nanoscale ultraviolet light-emitting diodes.

Since semiconducting ZnO has attractive properties such as wide bandgap and large exciton binding energy, it has motivated us to realize efficient ultraviolet (UV) light-emitting diodes (LEDs). Furthermore, facile growth of ZnO nanostructures has triggered numerous research studies to examine them as nanoscale building blocks for optoelectronic devices. Here, we demonstrate the growth of ZnO-based core-shell p-n homojunction nanorod arrays with radial MgZnO/ZnO multiple quantum wells (MQWs) and report the characteristics of a core-shell ZnO nanorod LED.

Spontaneous and Selective Nanowelding of Silver Nanowires by Electrochemical Ostwald Ripening and High Electrostatic Potential at the Junctions for High-Performance Stretchable Transparent Electrodes.

Metal nanowires have been gaining increasing attention as the most promising stretchable transparent electrodes for emerging field of stretchable optoelectronic devices. Nanowelding technology is a major challenge in the fabrication of metal nanowire networks because the optoelectronic performances of metal nanowire networks are mostly limited by the high junction resistance between nanowires. We demonstrate the spontaneous and selective welding of Ag nanowires (AgNWs) by Ag solders via an electrochemical Ostwald ripening process and high electrostatic potential at the junctions of AgNWs.

Development of Prediction Equation of Diffusing Capacity of Lung for Koreans.

Background: The diffusing capacity of the lung is influenced by multiple factors such as age, sex, height, weight, ethnicity and smoking status. Although a prediction equation for the diffusing capacity of Korea was proposed in the mid-1980s, this equation is not used currently. The aim of this study was to develop a new prediction equation for the diffusing capacity for Koreans.

Self-standing ZnO nanotube/SiO core-shell arrays for high photon extraction efficiency in III-nitride emitter.

Self-standing ZnO nanotube (ZNT) arrays were fabricated on the surface of a GaN-based emitter with an indium tin oxide (ITO) transparent layer using a hydrothermal method and temperature cooling down process. For the greater enhancement of photon extraction efficiency, ZNT/SiO core-shell nanostructure arrays were fabricated on the emitter with a 430 nm wavelength. The optical output power of ZNT/SiO core-shell arrays on the emitter with ITO electrode was remarkably enhanced by 18.

Self-assembled indium tin oxide nanoball-embedded omnidirectional reflectors for high photon extraction efficiency in III-nitride ultraviolet emitters.

The control of the refractive index and electrical conductivity in the dielectric layer of omnidirectional reflectors (ODRs) is essential to improve the low efficiency of AlGaN-based UV emitters. Here, we report self-assembled indium tin oxide (ITO) nanoball-embedded omnidirectional reflectors (NODRs) for use in high-efficiency AlGaN-based UV emitters at 365 nm. These NODRs consisted of a reflective Al layer, a self-assembled conducting ITO nanoball layer for current injection and spreading, and nanovoids that provided a low refractive index to achieve highly efficient UV emitters.

Enhanced optical output and reduction of the quantum-confined Stark effect in surface plasmon-enhanced green light-emitting diodes with gold nanoparticles.

We report the optical properties of localized surface plasmon (LSP)-enhanced green light-emitting diodes (LEDs) containing gold (Au) nanoparticles embedded in a p-GaN layer. The photoluminescence (PL) and electroluminescence (EL) intensities of a green LED with Au nanoparticles were enhanced by the coupling between excitons and LSPs. Excitation power-dependent PL and injection current-dependent EL measurements revealed that the blue-shift of PL and EL peaks with increasing carrier density was smaller for the LSP-enhanced LED compared with that for a conventional LED.

Titanium oxide nanotube arrays for high light extraction efficiency of GaN-based vertical light-emitting diodes.

TiO2 nanotube (NT) arrays were fabricated on the surface of n-GaN through a liquid-phase conversion process using ZnO nanorods (NRs) as a template for high-efficiency InGaN/GaN multiple quantum well (MQW) vertical light-emitting diodes (VLEDs). The optical output power of the VLEDs with TiO2 NTs was remarkably enhanced by 23% and 189% at an injection current of 350 mA compared to those of VLEDs with ZnO NRs and planar VLEDs, respectively. The large enhancement in optical output is attributed to a synergistic effect of efficient light injection from the n-GaN layer of the VLED to TiO2 NTs because of the well-matched refractive indices and superior light extraction into air at the end of the TiO2 NTs.

Enhanced optical output power of InGaN/GaN light-emitting diodes grown on a silicon (111) substrate with a nanoporous GaN layer.

We report the growth of InGaN/GaN multiple quantum wells blue light-emitting diodes (LEDs) on a silicon (111) substrate with an embedded nanoporous (NP) GaN layer. The NP GaN layer is fabricated by electrochemical etching of n-type GaN on the silicon substrate. The crystalline quality of crack-free GaN grown on the NP GaN layer is remarkably improved and the residual tensile stress is also decreased.

MgxZn1-xO/Ag/MgxZn1-xO Multilayers As High-Performance Transparent Conductive Electrodes.

We report on the optical and electrical properties of MgxZn1-xO/Ag/MgxZn1-xO transparent conductive electrodes. The transmittance and sheet resistance of MgxZn1-xO/Ag/MgxZn1-xO multilayers deposited at room temperature were strongly dependent on the thickness and surface morphology of Ag layer. The optical absorption edge of MgxZn1-xO/Ag/MgxZn1-xO showed a blue shift with increasing Mg composition due to the increased band gap of MgxZn1-xO.

Light-Emitting Diodes with Hierarchical and Multifunctional Surface Structures for High Light Extraction and an Antifouling Effect.

Bioinspired hierarchical structures on the surface of vertical light-emitting diodes (VLEDs) are demonstrated by combining a self-assembled dip-coating process and nanopatterning transfer method using thermal release tape. This versatile surface structure can efficiently reduce the total internal reflection and add functions, such as superhydrophobicity and high oleophobicity, to achieve an antifouling effect for VLEDs.

Enhanced optical output of InGaN/GaN near-ultraviolet light-emitting diodes by localized surface plasmon of colloidal silver nanoparticles.

We report on the characteristics of localized surface plasmon (LSP)-enhanced near-ultraviolet light-emitting diodes (NUV-LEDs) fabricated by using colloidal silver (Ag) nanoparticles (NPs). Colloidal Ag NPs were deposited on the 20 nm thick p-GaN spacer layer using a spray process. The optical output power of NUV-LEDs with colloidal Ag NPs was increased by 48.

Vertically stacked color tunable light-emitting diodes fabricated using wafer bonding and transfer printing.

We report on the vertically stacked color tunable light-emitting diodes (LEDs) fabricated using wafer bonding with an indium tin oxide (ITO) layer and transfer printing by the laser lift-off process. Employing optically transparent and electrically conductive ITO as an adhesion layer enables to bond the GaN-based blue and AlGaInP-based yellow LEDs. We find out that the interdiffusion of In, O, and Ga at the interface between ITO and GaP allows the strong bonding of the heterogeneous optoelectronic materials and the integration of two different color LEDs on a single substrate.