Publications by authors named "Yun-Hee Chang"

Hole-transport layers (HTL) in perovskite solar cells (PSCs) with an n-i-p structure are commonly doped by bis(trifluoromethane)sulfonimide (TFSI) salts to enhance hole conduction. While lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopant is a widely used and effective dopant, it has significant limitations, including the need for additional solvents and additives, environmental sensitivity, unintended oxidation, and dopant migration, which can lead to lower stability of PSCs. A novel ionic liquid, 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (MMPyTFSI), is explored as an alternative dopant for 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD).

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That the highly trabeculated ventricular walls of the developing embryos transform to the arrangement during the fetal stages, when the mural architecture is dominated by the thickness of the compact myocardium, has been explained by the coalescence of trabeculations, often erroneously described as 'compaction'. Recent data, however, support differential rates of growth of the trabecular and compact layers as the major driver of change. Here, these processes were assessed quantitatively and visualized in standardized views.

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The top-gate structure is currently adopted in various flat-panel displays because of its diverse advantages such as passivation from the external environment and process compatibility with industries. However, the mobility of the currently commercialized top-gate oxide thin-film transistors (TFTs) is insufficient to drive ultrahigh-resolution displays. Accordingly, this work suggests metal-capped Zn-Ba-Sn-O transistors with top-gate structures for inducing mobility-enhancing effects.

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Shrews occupy the lower extreme of the seven orders of magnitude mammals range in size. Their hearts are large relative to body weight and heart rate can exceed a thousand beats a minute. It is not known whether traits typical of mammal hearts scale to these extremes.

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Background: Glucocorticoids (GCs) are anti-inflammatory drugs widely used to treat acute and chronic inflammatory diseases. However, despite their excellent efficacy, the long-term use of GCs is relatively limited owing to their adverse effects. Recent studies have sought to reduce these adverse effects by developing dissociated GCs that bind to GC receptors (GRs) to induce potent anti-inflammatory effects without the transcription of GC response element (GRE)-promoted genes.

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Article Synopsis
  • The coordination between small molecules and metalloporphyrins is essential for processes like bio-oxidation and catalytic activation, with their structures studied through various techniques for decades.
  • High-resolution scanning tunneling microscopy (STM) was used to capture images of small molecules (O2, NO2, NH3) coordinated to Co-porphyrin on a gold surface, revealing distinct structural arrangements for each molecule at low temperatures.
  • The observed symmetries in the STM images were successfully matched with density functional theory (DFT) calculations, demonstrating that high-resolution techniques can effectively visualize the structures of these coordinated small molecules.
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Background: Skin hydration is a common problem both in elderly and young people as dry skin may cause irritation, dermatological disorders, and wrinkles. While both genetic and environmental factors seem to influence skin hydration, thorough genetic studies on skin hydration have not yet been conducted.

Objective: We used a genome-wide association study (GWAS) to explore the genetic elements underlying skin hydration by regulating epidermal differentiation and skin barrier function.

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Oxygen-containing functional groups such as epoxy, hydroxyl, carboxylic, and carboxyl groups have a great influence on the luminescence properties of graphene oxide quantum dots (GOQDs). Understanding their roles is essential for the design and optimization of GOQD performance. Herein, we investigate the effect of epoxide functional groups in GOQDs on the luminescence mechanism through passivation of the epoxide functional groups using the alkyl ligand oleylamine.

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Based on density functional theory calculations, we investigated the axial bindings of diatomic molecules (NO, CO, and O) to metalloporphyrins and their spin switching behaviors. These binding reactions provide the ways to control molecular states and spins in metalloporphyrin systems that can be used in bio-sensing and spintronic applications. To microscopically understand the non-trivial axial binding structures and spin-switching behaviors of diatomic molecules (NO, CO, and O) adsorbed onto Co-tetraphenylporphyrin (CoTPP), we performed spin-polarized density functional theory (DFT) calculations for various CoTPP systems on Au(111), Ag(111), and Cu(111) substrates.

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Article Synopsis
  • The study explores the source of bright blue light emitted from graphene quantum dots (GQDs) due to their intrinsic properties.
  • Bright photoluminescence (PL) in GQDs is linked to the presence of specific structures made of four to seven carbon hexagons.
  • Weak and redshifted PL occurs when random, harsh oxidation disrupts the ideal formation of these subdomains.
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Background/objectives: Citrus and its peels have been used in Asian folk medicine due to abundant flavonoids and usage of citrus peels, which are byproducts from juice and/or jam processing, may be a good strategy. Therefore, the aim of this study was to examine antioxidant and anti-inflammatory effects of bioconversion of Jeju Hallabong tangor (Citrus kiyomi × ponkan; CKP) peels with cytolase (CKP-C) in RAW 264.7 cells.

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Photocatalysts use sustainable solar light energy to trigger various catalytic reactions. Metal-free nanomaterials have been suggested as cost-effective and environmentally friendly photocatalysts. In this work, we propose thickness-controlled graphite oxide (GO) as a metal-free photocatalyst, which is produced by exfoliating thick GO particles via stirring and sonication.

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Background/objectives: Citrus flavonoids have a variety of physiological properties such as anti-oxidant, anti-inflammation, anti-cancer, and anti-obesity. We investigated whether bioconversion of Citrus unshiu with cytolase (CU-C) ameliorates the anti-adipogenic effects by modulation of adipocyte differentiation and lipid metabolism in 3T3-L1 cells.

Materials/methods: Glycoside forms of Citrus unshiu (CU) were converted into aglycoside forms with cytolase treatment.

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A two-stage genomewide association (GWA) analysis was conducted to investigate the genetic factors influencing ultraviolet (UV)-induced skin pigmentation in Korean females after UV exposure. Previously, a GWA study evaluating ~500 000 single nucleotide polymorphisms (SNPs) in 99 Korean females identified eight SNPs that were highly associated with tanning ability. To confirm these associations, we genotyped the SNPs in an independent replication study (112 Korean females).

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Axial coordinations of diatomic NO molecules to metalloporphyrins play key roles in dynamic processes of biological functions such as blood pressure control and immune response. Probing such reactions at the single molecule level is essential to understand their physical mechanisms but has been rarely performed. Here we report on our single molecule dissociation experiments of diatomic NO from NO-Co-porphyrin complexes describing its dissociation mechanisms.

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Cardiac myxoma is rare in children and often associated with cerebrovascular events. Reported herein is the case of a 9-year-old boy who presented with acute obstruction of the aortic bifurcation associated with a huge left atrial (LA) myxoma, thereby leading to acute ischemia of the lower extremities. Immediate surgical removal of the LA myxoma with concomitant percutaneous embolectomy using a Forgathy catheter was done, with relief of ischemic symptoms.

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Objective: To determine whether listening to music during transrectal ultrasound (TRUS)-guided 12-core needle prostate biopsy decreases anxiety, pain and dissatisfaction among patients and results in a more comfortable and better tolerated procedure.

Patients And Methods: 76 male patients who underwent TRUS-guided prostate biopsy between March 2013 and June 2014 were randomized into the following groups: no music (group I, n = 38) or classical music (group II, n = 38) during the procedure. Before TRUS-guided prostate biopsy, lidocaine gel was instilled into the rectum.

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Objectives: We evaluated our clinical experiences on rehabilitation of native pulmonary arteries (PAs) with a central shunt using an expanded polytetrafluoroethylene (ePTFE) tube graft in management of pulmonary atresia with ventricular septal defect (VSD) and major aortopulmonary collateral arteries (MAPCAs) with diminutive PAs.

Methods: From March 1993 to June 2013, a total of 28 consecutive patients underwent surgery for pulmonary atresia with VSD and MAPCAs. We identified 15 patients who underwent a central shunt procedure using an ePTFE tube graft.

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Nitrated lipids such as nitrooleate (OLA-NO2) can act as endogenous peroxisome proliferator-activated receptor gamma (PPARγ) ligands to exert vascular protective effects. However, the molecular mechanisms regarding nitric oxide (NO) production and its regulation are not fully defined in the vasculature. Here, we show that OLA-NO2 increased endothelial NO release by modulating activation of endothelial nitric oxide synthase (eNOS) in endothelial cells.

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Objectives: Postoperative left pulmonary artery (LPA) kinking is problematic in repair of tetralogy of Fallot (TOF). We used angioplasty of the proximal LPA with an anterior wall flap of the main pulmonary artery (MPA) to prevent this problem.

Methods: We have used an anterior wall of the MPA as a flap for LPA angioplasty in 42 patients with TOF and pulmonary stenosis (26 males and 16 females) since February 2007.

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Nanoscale alloys attract enormous research attentions in catalysis, magnetics, plasmonics and so on. Along with multicomponent synergy, quantum confinement and extreme large surface area of nanoalloys offer novel material properties, precisely and broadly tunable with chemical composition and nanoscale dimension. Despite substantial progress of nanoalloy synthesis, the randomized positional arrangement and dimensional/compositional inhomogeneity of nanoalloys remain significant technological challenges for advanced applications.

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Background: Airway compression caused by an enlarged right pulmonary artery (RPA) in patients with a large shunt can usually be managed with intracardiac repair and concomitant anterior aortopexy. However, anterior aortopexy can be less effective or even dangerous in patients with coexisting arch anomaly due to excessive tension at the arch repair site. We have adopted anterior translocation of RPA without aortic transection in the group of patients with a high risk of postoperative airway compression.

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