Publications by authors named "Dong Hwan Choi"

Tunable electrical phase transitions based on the structural and quantum-state phase transitions in two-dimensional transition-metal dichalcogenides have attracted attention in both semiconducting electronics and quantum electronics applications. Here, we report gate-voltage-induced reversible electrical phase transitions in MoWSe (MoWSe) field-effect transistors prepared on SiO/Si substrates. In gate-induced depletion regions of the 2H phase, an electrical current resumes flow at 150 K < < 200 K with decreasing irrespective of the layer number () for MoWSe when < 20.

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The present study aimed to compare the clinical characteristics and outcomes between pregnant women and non-pregnant women of childbearing age (20-49 years old) diagnosed with coronavirus disease 2019 (COVID-19) during the initial stage of the COVID-19 pandemic in the Republic of Korea. This nationwide observational study included the information of COVID-19 patients collected by the Korea Disease Control and Prevention Agency from January 2020 to April 2021. Among 5,647 COVID-19 patients, 2,444 (43.

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The electrical phase transition in van der Waals (vdW) layered materials such as transition-metal dichalcogenides and BiSrCaCuO (Bi-2212) high-temperature superconductor has been explored using various techniques, including scanning tunneling and photoemission spectroscopies, and measurements of electrical resistance as a function of temperature. In this study, we develop one useful method to elucidate the electrical phases in vdW layered materials: indium (In)-contacted vdW tunneling spectroscopy for 1T-TaS, Bi-2212 and 2H-MoS. We utilized the vdW gap formed at an In/vdW material interface as a tunnel barrier for tunneling spectroscopy.

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Chestnut inner shell (CIS) is rich in phenols and flavonoids such as gallic acid and ellagic acid, which are known to exhibit effective antioxidant and anti-obesity properties. Fermentation using lactic acid bacteria can enhance the physiological activity by increasing the contents of such functional ingredients. In this study, we evaluated the anti-obesity effects of a CIS extract subjected to a fermentation process (fermented CIS [FCIS]).

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Various intriguing quantum transport measurements for carbon nanotubes (CNTs) based on their unique electronic band structures have been performed adopting a field-effect transistor (FET), where the contact resistance represents the interaction between the one-dimensional and three-dimensional systems. Recently, van der Waals (vdW) gap tunneling spectroscopy for single-walled CNTs with indium-metal contacts was performed adopting an FET device, providing the direct assignment of the subband location in terms of the current-voltage characteristic. Here, we extend the vdW gap tunneling spectroscopy to multi-walled CNTs, which provides transport spectroscopy in a tunneling regime of ~1 eV, directly reflecting the electronic density of states.

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Introduction: We compared the performance of a fluorescence lateral flow assay (ichroma™ IGRA-TB) with the QuantiFERON-TB Gold PLUS (QFT-PLUS) for the diagnosis of latent tuberculosis infection (LTBI) in patients with immune-mediated inflammatory diseases (IMID) prior to receiving biologics therapy.

Method: The comparability of the ichroma™ IGRA-TB assay with the QFT-PLUS assay for the diagnosis of LTBI was determined in prospectively enrolled patients with IMID prior to receiving biologics between August 2018 and October 2019. To determine the best cut-off value of the ichroma™ IGRA-TB, an ROC curve analysis was performed.

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We demonstrate a gate-tunable quantum dot (QD) located between two potential barriers defined in a few-layer MoS. Although both local gates used to tune the potential barriers have disorder-induced QDs, we observe diagonal current stripes in current resonant islands formed by the alignment of the Fermi levels of the electrodes and the energy levels of the disorder-induced QDs, as evidence of the gate-tunable QD. We demonstrate that the charging energy of the designed QD can be tuned in the range of 2-6 meV by changing the local-gate voltages in ∼1 V.

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Purpose: This study aimed to evaluate ichroma™ IGRA-TB, a novel point-of-care platform for assaying IFN-γ release, and to compare it with QuantiFERON-TB Gold In-Tube (QFT-GIT) for identifying () infection.

Materials And Methods: We recruited 60 healthy subjects, and blood samples were obtained in QFT-GIT blood collection tubes. The blood collection tubes were incubated at 37°C, and culture supernatant was harvested after 18-24 hours.

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A gold nanorod (GNR) based LSPR sensor has been developed for label-free detection of C-reactive protein (CRP). The sensor utilizes a single chain variable fragment (scFv) as a receptor to bind CRP. The results of this effort show that CRP in human serum can be quantitatively detected at lower than 1 ng mL(-1).

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For signal amplification without an additional operation step in a gold nanoparticle (AuNP)-based lateral flow assay (LFA), a new and simple method utilizing two AuNP-antibody conjugates was developed. The 1st conjugate was the AuNP immobilized with an anti-troponin I antibody and blocked with bovine serum albumin (BSA), and the 2nd conjugate was the AuNP immobilized with an anti-BSA antibody and blocked with human serum albumin. The two conjugates were encapsulated in different pads, respectively.

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Single-chain Fv antibodies (scFv) genetically fused with polystyrene-binding peptides (PS-tags, (PS19-1; RAFIASRRIRRP, PS19-6; RIIIRRIRR)) were generated by recombinant Escherichia coli for direct and site-specific immobilization of scFv on polystyrene supports with high antigen-binding activity. PS-tag-fused scFvs (scFv-PS-tags) specific for human C-reactive protein (CRP) were successfully over-expressed as an inclusion body and were refolded using the batch-dilution method. When scFv-PS-tags were immobilized on a hydrophilic PS (phi-PS) plate in the presence of Tween 20, they showed high antigen-binding activity comparable to, or greater than, that of a whole monoclonal antibody (mAb) on a hydrophobic PS (pho-PS) plate, which has been the exclusive method for enzyme-linked immunosorbent assay (ELISA).

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A rational strategy for the rapid establishment of a sensitive sandwich enzyme linked immunosorbant assay was developed. The kinetic properties required for the solid-phase and enzyme-conjugated antibodies of sandwich ELISA were determined rationally on the basis of a kinetic model describing antibody-antigen interaction. Some antibodies possessing the required kinetic properties against a model antigen, C-reactive protein (CRP), were successfully isolated from a phage antibody library under the screening conditions that were designed on the basis of simulation results.

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The limit of detection (LOD) and range of quantitation (ROQ) of competitive enzyme-linked immunosorbent assay (ELISA) were determined from a model describing the calibration curve and precision profile of the assay. The calibration curve is given by solving the differential equations describing the change in the concentrations of an antigen-antibody complex and an enzyme-conjugated antigen-antibody complex by a Runge-Kutta method. The precision profile is described in terms of possible error sources such as the pipetting volumes of the analyte, enzyme-conjugated antigen, antibody and substrate solutions, calibration curve and inherent absorbances between the wells in an ELISA plate.

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The mathematical model for predicting the precision, limit of detection (LOD) and range of quantitation (ROQ) in a competitive enzyme-linked immunosorbent assay (ELISA) proposed by Hayashi et al. (Anal. Chem.

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