Publications by authors named "Youngjin Ko"

The presence of oxygen vacancies (V) in electrocatalysts plays a significant role in improving the selectivity and activity of CO reduction reaction (CORR). In this study, 1D material with large surface area is utilized to enable uniform V formation on the catalyst. 1D structured indium selenoiodide (InSeI) is synthesized and used as an electrocatalyst for the conversion of CO to formate.

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Article Synopsis
  • 1D nanostructures, like tin iodide phosphide (SnIP), are effective electrocatalysts for converting carbon dioxide (CO) to formate due to their high surface area and efficient ion transport.
  • The electrochemical treatment of SnIP transforms its structure, creating more oxygen vacancies which enhance its catalytic activity and allow it to maintain performance in reducing environments.
  • The synthesized SnIP catalyst demonstrates impressive results with over 92% faradaic efficiency and excellent stability, showing potential for practical applications in CO reduction.
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To realize economically feasible electrochemical CO conversion, achieving a high partial current density for value-added products is particularly vital. However, acceleration of the hydrogen evolution reaction due to cathode flooding in a high-current-density region makes this challenging. Herein, we find that partially ligand-derived Ag nanoparticles (Ag-NPs) could prevent electrolyte flooding while maintaining catalytic activity for CO electroreduction.

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Introduction: With the availability of retrospective pharmacovigilance data, the common data model (CDM) has been identified as an efficient approach towards anonymized multicenter analysis; however, the establishment of a suitable model for individual medical systems and applications supporting their analysis is a challenge.

Objective: The aim of this study was to construct a specialized Korean CDM (K-CDM) for pharmacovigilance systems based on a clinical scenario to detect adverse drug reactions (ADRs).

Methods: De-identified patient records (n = 5,402,129) from 13 institutions were converted to the K-CDM.

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Faced with the prospect that the impact of the COVID-19 pandemic and climate change will be far-reaching and long-term, the international community is showing interest in urban green space (UGS) and urban green infrastructure utilization as a solution. In this study, we investigated how citizens' perceptions and use of UGS have changed during COVID-19. We also collected their ideas on how UGS can raise its usability.

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The electrosynthesis of formate from CO can mitigate environmental issues while providing an economically valuable product. Although stannic oxide is a good catalytic material for formate production, a metallic phase is formed under high reduction overpotentials, reducing its activity. Here, using a fluorine-doped tin oxide catalyst, a high Faradaic efficiency for formate (95% at 100 mA cm) and a maximum partial current density of 330 mA cm (at 400 mA cm) is achieved for the electroreduction of CO.

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Computational calculations and experimental studies reveal that the CoOOH phase and the intermediate-spin (IS) state are the key factors for realizing efficient Co-based electrocatalysts for the oxygen evolution reaction (OER). However, according to thermodynamics, general cobalt oxide converts to the CoO phase under OER condition, retarding the OER kinetics. Herein, we demonstrate a simple and scalable strategy to fabricate electrodes with maintaining Fe-CoOOH phase and an IS state under the OER.

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The diamond-graphite hybrid thin film with low-dimensional nanostructure (e.g., nitrogen-included ultrananocrystalline diamond (N-UNCD) or the alike), has been employed in many impactful breakthrough applications.

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The voltage reversal of water electrolyzers and fuel cells induces a large positive potential on the hydrogen electrodes, followed by severe system degradation. Applying a reversible multifunctional electrocatalyst to the hydrogen electrode is a practical solution. Ir exhibits excellent catalytic activity for hydrogen evolution reactions (HER), and hydrogen oxidation reactions (HOR), yet irreversibly converts to amorphous IrO at potentials > 0.

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Serotonin norepinephrine reuptake inhibitor (SNRI) has been increasingly administered, but the associated cardiovascular disease (CVD) related adverse events risk is not clearly understood. So, we conducted a cohort study to identified CVD-related adverse events risk of SNRI comparing to selective serotonin reuptake inhibitor (SSRI). We used Korea Health Insurance Review and Assessment data.

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Iron immobilized on supports such as silica, alumina, titanium oxide, and zeolite can activate hydrogen peroxide (HO) into strong oxidants. However, the role of the support and the nature of the oxidants produced in this process remain elusive. This study investigated the activation of HO by a TiO-supported catalyst (FeTi-ox).

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Single-atom catalysts (SACs) possess the potential to achieve unique catalytic properties and remarkable catalytic mass activity by utilizing low-coordination and unsaturated active sites. However, smaller particles tend to aggregate into clusters or particles owing to their high surface energy. In addition, support materials that have strong interactions with isolated metal atoms, extremely large surface areas, and electrochemical stability are required.

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Duloxetine has been increasingly administered, but the associated cardiovascular adverse event risk is not clearly understood. Therefore, we identified the association between duloxetine and cardiovascular adverse events through an analysis of heart rate and blood pressure change. We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials, ClinicalTrials.

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Background: In order to ensure safer use of non-vitamin K antagonist oral anticoagulants (NOACs), continuously detecting unexpected adverse drug reactions (ADRs) after market approval is necessary.

Methods: We performed disproportionality analysis to evaluate association between ADRs and NOACs including apixaban, dabigatran, and rivaroxaban using data from the Korea Institute of Drug Safety and Risk Management-Korea Adverse Event Reporting System database (KIDS-KD) between 2012 and 2016. There was no significant signal other than bleeding when considering quantity, signal strength, seriousness, and causality.

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Surveillance remains an important tool for timely outbreak detection and response. Many countries, including Korea, have established national infectious disease surveillance systems with clinical notification. We aimed to evaluate the National Health Insurance Claims-based Surveillance (NHICS) compared to conventional passive report-based National Infectious Diseases Surveillance (NIDS).

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The purpose of this study was to report surgical tips and techniques on the use of additional medial buttress plate fixation in proximal humeral fractures with unstable medial column restoration after lateral locking compression plate fixation. Between April 2011 and January 2017, 17 patients with medial cortical deficiency were treated using this technique. The average follow-up period was 30 (range, 12-81) months.

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The number of reported varicella cases is continuously increasing in Korea; however, associated medical utilization is declining. The ratio between varicella insurance claims and reports of passive infectious disease surveillance has gradually increased to > 80% since the second half of 2017. The recent increase in reported varicella cases is influenced by improved reporting.

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Article Synopsis
  • Chromate is a toxic water contaminant that affects both human and animal health, prompting the search for effective adsorbents to meet strict chromium regulations in water.
  • The study explored using a polypyrrole coating on carbon black with a focus on pyrrolic nitrogen to enhance chromate adsorption, achieving a significant increase in capacity as pyrrole content rose.
  • Mechanistic analysis showed that the adsorption of Cr(III) and Cr(VI) occurs via different pathways, with Cr(III) involving a two-step process including a reaction with pyrrolic nitrogen, while Cr(VI) adsorbs through hydrogen bonding to the pyrrol N sites.
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Background: To evaluate oral anticoagulant (OAC) utilization in patients with atrial fibrillation after the changes in the health insurance coverage policy in July 2015.

Methods: We used the Health Insurance Review and Assessment Service-National Patient Samples (HIRA-NPS) between 2014 and 2016. The HIRA-NPS, including approximately 1.

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Article Synopsis
  • Onion-like carbon (OLC) was created from nanodiamond and tested for its ability to remove chromate ions from water.
  • The study analyzed how temperature affects oxygen-carbon bonds and water that is chemically attached to the OLC using advanced techniques like X-ray photoelectron spectroscopy.
  • Findings show that the types of carbon-oxygen bonds and carbon dangling bonds play a crucial role in effectively adsorbing chromate and other anionic heavy metals from wastewater.
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We analyzed the nanodiamond-derived onion-like carbon (OLC) as function of synthesis temperature (1000~1400 °C), by high-resolution electron microscopy, electron energy loss spectroscopy, visible-Raman spectroscopy, ultraviolet photoemission spectroscopy, impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry. The temperature dependences of the obtained properties (averaged particle size, tensile strain, defect density, density of states, electron transfer kinetics, and electrochemical oxidation current) unanimously coincided: they initially increased and saturated at 1200 °C. It was attributed to the inherent tensile strains arising from (1) the volume expansion associated with the layer-wise diamond-to-graphite transformation of the core, which caused forced dilation of the outer shells during their thermal synthesis; (2) the extreme curvature of the shells.

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The importance of adherence to antihypertensive treatments for the prevention of cardiovascular disease has not been well elucidated. This study evaluated the effect of antihypertensive medication adherence on specific cardiovascular disease mortality (ischemic heart disease [IHD], cerebral hemorrhage, and cerebral infarction). Our study used data from a 3% sample cohort that was randomly extracted from enrollees of Korean National Health Insurance.

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The potential role of visceral adipose tissue (VAT) as a prognostic factor in patients with diffuse large B cell lymphoma (DLBCL) treated with frontline rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) immunochemotherapy was explored. Total adipose tissue and VAT were measured by analyzing positron emission tomography (PET)/computed tomography (CT) images obtained during the initial staging of patients with DLBCL. The VAT ratio was calculated as follows: VAT ratio = VAT area/total adipose tissue area.

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Purpose: The aim of this study was to compare the public perceptions of the incidence rates and survival rates for common cancers with the actual rates from epidemiologic data.

Materials And Methods: We conducted a survey of Korean adults without history of cancer (n=2,000). The survey consisted of questions about their perceptions regarding lifetime incidence rates and 5-year survival rates for total cancer, as well as those of eight site-specific cancers.

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