Atomic Layer Deposition of ZnO on CsPbBr Perovskite Nanocrystals: Surface-Dependent Mechanistic Insights.

In this study, we investigate the atomic layer deposition (ALD) process on all-inorganic CsPbBr perovskite nanocrystals (PNCs) to introduce an inorganic electron transport layer (ETL) in light-emitting diode (LED) devices. Two types of CsPbBr PNCs were synthesized with oleate (OA) and oleylammonium (OLA) ligands on the surface. We found that CsPbBr PNCs with Cs oleate surfaces experienced severe photoluminescence (PL) quenching after the ALD process, while those with oleylammonium bromide surfaces did not show any significant PL drop.

Spatial Control of Nickel Vacancies in Colloidal NiMgO Nanocrystals for Efficient and Stable All-inorganic Quantum Dot Light-Emitting Diodes.

Colloidal quantum dot (QD)-based light-emitting diodes (QD-LEDs) have reached the pinnacle of quantum efficiency and are now being actively developed for next-generation displays and brighter light sources. Previous research has suggested utilizing inorganic hole-transport layers (HTLs) to explore brighter and more stable QD-LEDs. However, the performance metrics of such QD-LEDs with inorganic HTLs generally lag behind those of organic-inorganic hybrid QD-LEDs employing organic HTLs.

Relationship between the use of hair products and urine benzophenone-3: the Korean National Environmental Health Survey (KoNEHS) cycle 4.

Background: Benzophenone-3 is a type of ketone with 2 benzene rings attached to a carbonyl group (C=O) and one benzene ring attached to a hydroxyl group (-OH). As an endocrine-disrupting chemical, benzophenone-3 is known to be associated with reproductive, developmental, thyroid, and endocrine toxicities. Benzophenone-3 is commonly used in hair products, cosmetics, and ultraviolet (UV) filters because of its characteristic property to absorb UV light.

Relationship between crustacean consumption and serum perfluoroalkyl substances (PFAS): the Korean National Environmental Health Survey (KoNEHS) cycle 4.

Background: Perfluoroalkyl substances (PFASs) are non-aromatic organic compounds, whose hydrogen atoms in the carbon chain substituted by fluorine atoms. PFASs exhibit developmental toxicity, carcinogenicity, hepatotoxicity, reproductive toxicity, immunotoxicity, and hormone toxicity. PFASs are used in the production of disposable food packages, aircraft and automobile devices, cooking utensils, outdoor gear, furniture and carpets, aqueous film forming foam (AFFF), cables and wires, electronics, and semiconductors.

Relationship between the use of plastics in refrigerator food storage and urine phthalate metabolites: the Korean National Environmental Health Survey (KoNEHS) cycle 3.

Background: Plastics are high-molecular-weight materials composed of long carbon chains. They are prevalent in daily life, present in various items such as food containers and microwavable packaging. Phthalates, an additive used to enhance their flexibility, are endocrine-disrupting chemicals.

Slanted Structure of Blue Phase II Self-Aligned on One-Dimensional Patterned Surfaces.

Orientation analysis of liquid crystal (LC) devices is important for understanding and controlling light propagation behavior in these devices. Blue phases (BPs)─unique LC phases that self-organize into three-dimensional helical structures─are candidate materials for LC-based reflective diffractors. We realized BPII deflectors with large diffraction angles using one-dimensional surface alignment patterns.

Relationship between shellfish consumption and urinary phthalate metabolites: Korean National Environmental Health Survey (KoNEHS) cycle 3 (2015-2017).

Background: Phthalates are endocrine disrupting chemicals that are widely used in the production of items of daily life such as in polyvinylchloride plastics, insecticides, and medical devices. This study aimed to determine the association between phthalate exposure and shellfish consumption using data from the Korean National Environmental Health Survey (KoNEHS) cycle 3 (2015-2017), which is a nationally representative survey.

Methods: In this study, we analyzed the KoNEHS cycle 3 data of 3,333 (1,526 men and 1,807 women) adults aged more than 19 years.

Electrocardiogram abnormalities in antimony exposed workers in the automotive brake lining manufacturing industry: a case report.

Background: Antimony is used in catalysts, pesticides, brake systems, pharmaceuticals, and synthetic fire retardants in the plastic, paint, and rubber industries. Accumulation of trivalent antimony compounds in the body can cause cardiotoxic effects and increase the risk of electrocardiogram (ECG) abnormalities and sudden death. Antimony exposure can result in action potential prolongation, causing a cardiac repolarization delay, which appears as QTc prolongation and T-wave abnormalities on the ECG.

Tunable polarization volume gratings based on blue phase liquid crystals.

A large-angle polarization volume grating (PVG) with circular-polarization selectivity is demonstrated using a three-dimensional chiral liquid crystal with simple cubic symmetry - the blue phase (BP) II. We confirm defect-free alignment of the BP crystal on a periodically patterned substrate down to a period of 700 nm, with Kossel diagrams and far-field diffraction patterns suggesting that the lattice becomes slanted within the cell to accommodate to the imprinted pattern. We further demonstrate a tunable PVG by exploiting the external field-responsivity of BPs, making this PVG attractive for a wide range of applications from tunable photonics to augmented reality.

Relationship between shift work and age-related macular degeneration: a cross-sectional analysis of data from the 5th Korea National Health and Nutrition Examination Survey (2010-2012).

Background: Age-related macular degeneration (AMD) is the leading cause of blindness. Shift work has well-known adverse effects on health. However, few studies have investigated the relationship between shift work and AMD.

High-Resolution Colloidal Quantum Dot Film Photolithography via Atomic Layer Deposition of ZnO.

High-resolution patterning of quantum dot (QD) films is one of the preconditions for the practical use of QD-based emissive display platforms. Recently, inkjet printing and transfer printing have been actively developed; however, high-resolution patterning is still limited owing to nozzle-clogging issues and coffee ring effects during the inkjet printing and kinetic parameters such as pickup and peeling speed during the transfer process. Consequently, employing direct optical lithography would be highly beneficial owing to its well-established process in the semiconductor industry; however, exposing the photoresist (PR) on top of the QD film deteriorates the QD film underneath.

In Situ Optical Characterization of Twinning in Liquid Crystalline Blue Phases.

Crystal twinning is an intergrowth of two or more single crystals of the same species with specific crystallographic relations in their orientations. Here, we perform microscopic optical characterization of (211) twins in the three-dimensional liquid crystalline phase known as the blue phase (BP), with I432 space group symmetry. We describe the effect of twinning on the optical diffraction pattern-Kossel pattern-of blue phases and analyze the patterns to deduce structural information such as the twin elements and the previously unnoticed deviations from the perfect cubic structure at zero electric field.

Association of work-life balance with occupational injury and work-related musculoskeletal pain among Korean workers.

Background: The concept of work-life balance (WLB) has become an important issue in workers' health and safety. This study aims to investigate the relationship between WLB and occupational injury and work-related musculoskeletal pain.

Method: The study included 27,383 workers who participated in the Fifth Korean Working Conditions Survey.

Bragg-Berry flat reflectors for transparent computer-generated holograms and waveguide holography with visible color playback capability.

Various approaches are being pursued to realize compact optical elements with the ability to manipulate light, but it is difficult to simultaneously achieve high reflectivity and the ability to see through the element. Here, we present a reflective computer-generated hologram that is completely transparent in the visible, based on the Berry (geometric) phase in a self-organizing Bragg reflector. The Bragg reflector has a helical dielectric tensor distribution with the phase information imprinted in the distribution of the optic axis on the substrate.

Sheet Resistance Analysis of Interface-Engineered Multilayer Graphene: Mobility Versus Sheet Carrier Concentration.

Both interlayer-undoped and interlayer-doped multilayer graphenes were prepared by the multiple transfers of graphene layers with multiple Cu etching (either dopant-free or doped during etching) and transfer, and the effect of interface properties on the electrical properties of multilayer graphene was investigated by varying the number of layers from 1 to 12. In both the cases, the sheet resistance decreased with increasing number of layers from 700 to 104 Ω/sq for the interlayer-undoped graphene and from 280 to 25 Ω/sq for the interlayer-doped graphene. Further, Hall measurements revealed that the origins of the sheet resistance reduction in the two cases are different.

Effect of nitrogen-doping on drain current modulation characteristics of an indium-gallium-zinc oxide thin-film transistor.

The effect of nitrogen-doping (N-doping) in an indium-gallium-zinc oxide (IGZO) channel layer on the analog, linear, and reversible drain current modulation in thin-film transistors (TFTs) with Al-top-gate/SiO/TaO/IGZO stack is investigated for potential application to artificial synaptic devices. The N-doped devices exhibit a more linear increase of drain current upon repeating positive gate biasing, corresponding to synaptic potentiation, while the undoped device shows a highly non-linear and abrupt increase of drain current. Distinct from the increase of drain current at positive biasing for potentiation, the decrease of drain current for depression behavior at negative biasing is found to be the same.

Selective Atomic Layer Deposition of Metals on Graphene for Transparent Conducting Electrode Application.

Although graphene has considerable potential as a next-generation transparent conducting electrode (TCE) material owing to its excellent optical transparency and flexibility, its electrical properties require further improvement for industrial application. This study reports a pathway of doping graphene by selective atomic layer deposition (ALD) of metals to elevate the electrical conductivity of graphene. Introduction of a novel Pt precursor [dimethyl(,-dimethyl-3-butene-1-amine-)platinum(II); CHNPt; DDAP] facilitates a low-temperature (165 °C) process.

Electrical properties of graphene/InO bilayer with remarkable uniformity as transparent conducting electrode.

A graphene/InO bilayer (termed as GI-bilayer) is proposed as a transparent conducting electrode with remarkably improved areal-uniformity. To fabricate this new structure, an InO layer with a thickness of less than 50 nm was grown by atomic layer deposition and then a graphene layer was grown by chemical vapor deposition and subsequently transferred onto the as-grown InO layer. Electrical and optical properties of the GI-bilayer were systematically studied to verify effects of the underlying InO layer.

Highly Miscible Hybrid Liquid-Crystal Systems Containing Fluorescent Excited-State Intramolecular Proton Transfer Molecules.

Doping of luminescent molecules in a nematic liquid-crystal (LC) host is a convenient approach to develop light-emitting LC displays that would be a promising alternative to conventional LC displays. The requirements for the luminescent guest molecules include high miscibility in the host LC, high-order parameters in the host LC media to show anisotropic luminescence, lack of self-absorption, transparency in the visible region, and a large photoluminescence quantum yield independent of its concentration. To address these issues, here, we newly synthesize a highly miscible and fluorescent excited-state intramolecular proton transfer molecule, , based on 2-(2-hydroxyphenyl)benzothiazole (HBT).

Atomic Layer Deposition of Nickel Using a Heteroleptic Ni Precursor with NH and Selective Deposition on Defects of Graphene.

Atomic layer deposition (ALD) of Ni was demonstrated by introducing a novel oxygen-free heteroleptic Ni precursor, (η-cyclohexenyl)(η-cyclopentadienyl)nickel(II) [Ni(Chex)(Cp)]. For this process, non-oxygen-containing reactants (NH and H molecules) were used within a deposition temperature range of 320-340 °C. Typical ALD growth behavior was confirmed at 340 °C with a self-limiting growth rate of 1.

Influence of indium-tin-oxide and emitting-layer thicknesses on light outcoupling of perovskite light-emitting diodes.

Metal halide perovskite light-emitting diodes (PeLEDs) are emerging as a promising candidate for next-generation optoelectronic devices. The efficiency of PeLEDs has developed explosively in a short time, but their overall efficiency is still low. This is strongly related to the high refractive indexes of indium-tin-oxide (ITO) and perovskite emitting layers.

Comparison of Growth Behavior and Electrical Properties of Graphene Grown on Solid and Liquid Copper by Chemical Vapor Deposition.

We study the graphene growth behavior above and below the copper (Cu) melting point (1083 °C) by only changing the growth temperature from 1020 °C to 1100 °C at intervals of 40 °C, to investigate the effect of the Cu phase as a catalyst layer in graphene growth. We investigate the graphene growth behavior by observing the changes in nucleation density and grain size with growth time. As the phase of the Cu catalyst changes from solid to liquid, the grain size of graphene increases by 2 orders of magnitude from 0.

Optimal Nitrogen Incorporation in Nickel Silicide for Thermally Stable Contact Formation.

Nickel silicide (NiSi) is commonly used as a contact material for metal junctions but the poor thermal instability of NiSi above 600 °C has limited the further scaling down of devices and the implementation of novel schemes, such as monolithic 3-dimensional integration. This paper suggests a process to improve the thermal stability of NiSi through nitrogen incorporation during the silicidation process. The optimal level of nitrogen incorporation in NiSi reduced the nickel diffusion rate and enhanced the thermal stability by preventing the formation of a nickel disilicide phase.

Difference in health status of Korean farmers according to gender.

Background: The objective of this study was to compare differences in lifestyle diseases, musculoskeletal pain, psychosocial stress, and self-health awareness according to gender in Korean farmers.

Methods: The study population comprised 436 farmers residing in rural areas in Korea. A self-administered questionnaire was used to survey demographic characteristics, health-related behaviors, and musculoskeletal pain.