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2,193 results on '"Lee, Sung-Gyu"'

4. Organic molecules as origin of visible-range single photon emission from hexagonal boron nitride and mica

Author

Neumann, Michael, Wei, Xu, Morales-Inostroza, Luis, Song, Seunghyun, Lee, Sung-Gyu, Watanabe, Kenji, Taniguchi, Takashi, Götzinger, Stephan, and Lee, Young Hee

Subjects
Physics - Optics, Condensed Matter - Materials Science, Quantum Physics
Abstract

The discovery of room-temperature single-photon emitters (SPEs) hosted by two-dimensional hexagonal boron nitride (2D hBN) has sparked intense research interest. Although emitters in the vicinity of 2 eV have been studied extensively, their microscopic identity has remained elusive. The discussion of this class of SPEs has centered on point defects in the hBN crystal lattice, but none of the candidate defect structures have been able to capture the great heterogeneity in emitter properties that is observed experimentally. Employing a widely used sample preparation protocol but disentangling several confounding factors, we demonstrate conclusively that heterogeneous single-photon emission ~2 eV associated with hBN originates from organic molecules, presumably aromatic fluorophores. The appearance of those SPEs depends critically on the presence of organic processing residues during sample preparation, and emitters formed during heat treatment are not located within the hBN crystal as previously thought, but at the hBN/substrate interface. We further demonstrate that the same class of SPEs can be observed in a different 2D insulator, fluorophlogopite mica., Comment: This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in ACS Nano, copyright \copyright\ 2023 American Chemical Society after peer review. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acsnano.3c02348

Published
2023
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7. A novel scoring system to predict short-term mortality after living donor liver transplantation for acute liver failure

Author

Sudhindran, Surendran, Yoshizumi, Tomoharu, Hatano, Etsuro, Okumura, Shinya, Hasegawa, Kiyoshi, Egawa, Hiroto, Obara, Hideaki, Yasui, Kazuya, Ogura, Yasuhiro, Jobara, Kanta, Nitta, Hiroyuki, Katagiri, Hirokatsu, Otsuka, Masayuki, Kuboki, Satoshi, Eguchi, Susumu, Hara, Takanobu, Eguchi, Hidetoshi, Sasaki, Kazuki, Aoki, Taku, Ohdan, Hideki, Ohira, Masahiro, Takada, Yasutsugu, Ogawa, Kohei, Fukumoto, Takumi, Kuramitsu, Kaori, Saiura, Akio, Ichida, Hirofumi, Hashimoto, Takuya, Marubashi, Shigeru, Sato, Naoya, Ushigome, Hidetaka, Harada, Shumpei, Soejima, Yuji, Masuda, Yuichi, Shimada, Mitsuo, Saitou, Yu, Taketomi, Akinobu, Goto, Ryoichi, Shimamura, Tsuyoshi, Mizuno, Shugo, Tanemura, Akihiro, Endo, Itaru, Unno, Michiaki, Miyagi, Shigehito, Okamura, Yukiyasu, Aramaki, Osamu, Hakamada, Kenichi, Ishido, Keinosuke, Kato, Yutaro, Takahara, Takeshi, Takatsuki, Mitsuhisa, Ono, Shinichiro, Shimata, Keita, Yoon, Young-In, Hibi, Taizo, Morinaga, Jun, Narayanan, Anila Kutty, Toshima, Takeo, Ito, Takashi, Akamatsu, Nobuhisa, Kotera, Yoshihito, Hong, Suk Kyun, Hasegawa, Yasushi, Umeda, Yuzo, Reddy, Mettu Srinivas, Ong, Aldwin De Leon, Sivaprasadan, Saraswathy, Varghese, Joy, Sugawara, Yasuhiko, Chen, Chao-Long, Nakayama, Nobuaki, Mochida, Satoshi, Tanaka, Atsushi, Suh, Kyung-Suk, Ikegami, Toru, Lee, Kwang-Woong, and Lee, Sung-Gyu

Published
2024
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9. Non-oxidized bare copper nanoparticles with surface excess electrons in air.

Author

Chung, Kyungwha, Bang, Joonho, Thacharon, Athira, Song, Hyun, Kang, Se, Jang, Woo-Sung, Dhull, Neha, Thapa, Dinesh, Ajmal, C, Song, Bumsub, Lee, Sung-Gyu, Wang, Zhen, Jetybayeva, Albina, Hong, Seungbum, Lee, Kyu, Cho, Eun, Baik, Seunghyun, Oh, Sang, Kim, Young-Min, Lee, Young, Kim, Seong-Gon, and Kim, Sung

Abstract

Copper (Cu) nanoparticles (NPs) have received extensive interest owing to their advantageous properties compared with their bulk counterparts. Although the natural oxidation of Cu NPs can be alleviated by passivating the surfaces with additional moieties, obtaining non-oxidized bare Cu NPs in air remains challenging. Here we report that bare Cu NPs with surface excess electrons retain their non-oxidized state over several months in ambient air. Cu NPs grown on an electride support with excellent electron transfer ability are encapsulated by the surface-accumulated excess electrons, exhibiting an ultralow work function of ~3.2 eV. Atomic-scale structural and chemical analyses confirm the absence of Cu oxide moiety at the outermost surface of air-exposed bare Cu NPs. Theoretical energetics clarify that the surface-accumulated excess electrons suppress the oxygen adsorption and consequently prohibit the infiltration of oxygen into the Cu lattice, provoking the endothermic reaction for oxidation process. Our results will further stimulate the practical use of metal NPs in versatile applications.

Published
2022

15. Observation of an exceptional point in a non-Hermitian metasurface

Author

Park, Sang Hyun, Lee, Sung-Gyu, Ha, Taewoo, Lee, Sanghyup, Baek, Soo-Jeong, Min, Bumki, Zhang, Shuang, Lawrence, Mark, and Kim, Teun-Teun

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Exceptional points, also known as non-Hermitian degeneracies, have been observed in parity-time symmetric metasurfaces as the parity-time symmetry breaking point. However, the parity-time symmetry condition puts constraints on the metasurface parameter space, excluding full examination of the unique properties that stem from an exceptional point. Here, we thus design a general non-Hermitian metasurface with a unit cell containing two orthogonally oriented split-ring-resonators with overlapping resonance but different scattering rates and radiation efficiencies. Such a design grants us full access to the parameter space around the exceptional point. The parameter space around the exceptional point is first examined by varying the incident radiation frequency and coupling between split-ring resonators. We further demonstrate that the exceptional point is also observable by varying the incident radiation frequency along with the incident angle. Through both methods we validate the existence of an exceptional point by observing unique level crossing behavior, eigenstate swapping under encirclement and asymmetric transmission of circularly polarized light., Comment: 7 pages, 4 figures

Published
2019
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18. A Multicenter, Randomized, Open-Label Study to Compare the Efficacy and Safety of Tacrolimus and Corticosteroids in Combination With or Without Mycophenolate Mofetil in Liver Transplantation Recipients Infected With Hepatitis B Virus

Author

Park, Jeong-Ik, Song, Gi-Won, Ryu, Je Ho, Choi, Sang-Tae, Choi, Nam-Gyu, Jung, Bo-Hyun, Chu, Chong Woo, Kim, Keon-Kuk, Jung, Dong-Hwan, Ha, Tae-Yong, Moon, Deok-Bog, Yang, Kwangho, Shin, Min-Ho, Chung, Yong-Kyu, Hwang, Shin, Yoon, Young-In, and Lee, Sung-Gyu

Published
2023
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42. Over 500 Liver Transplants Including More Than 400 Living-Donor Liver Transplants in 2019 at Asan Medical Center

Author

Moon, Deok-Bog, Lee, Sung-Gyu, Chung, Yong-Kyu, Kang, Woo-Hyoung, Kim, Ki-Hun, Song, Gi-Won, Jung, Dong-Hwan, Ha, Tae-Yong, Ahn, Chul-Soo, Park, Gil-Chun, Hwang, Shin, Yoon, Young-In, Cho, Hwui-Dong, Kang, Sang-Hyun, Choi, Jin-Uk, Jeong, I-Jy, Na, Byeong-Gon, Kim, Min-Jae, Kim, Sang-Hoon, Sung, Kyu-Bo, Ko, Gi-Young, Kwon, Dong-Il, Lee, Sung-Koo, Oh, Dong-Wook, Hwang, Gyu-Sam, Song, Jun-Gol, Jun, In-Gu, Moon, Young-Jin, Lee, Sang-Oh, Kim, Sung-Han, and Huh, Jin-Won

Published
2021
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46. Antioxidative and Anti-Atopic Dermatitis Effects of Peptides Derived from Hydrolyzed Sebastes schlegelii Tail By-Products.

Author

Lee, Sung-Gyu, Hwang, Jin-Woo, and Kang, Hyun

Abstract

Atopic dermatitis (AD) is a chronic inflammatory skin disorder associated with significant morbidity, including pruritus, recurrent skin lesions, and immune dysregulation. This study aimed to investigate the antioxidative and anti-AD effects of peptides derived from hydrolyzed Sebastes schlegelii (Korea rockfish) tail by-products. Hydrolysates were prepared using various enzymes, including Alcalase, Flavourzyme, Neutrase, and Protamex. Among them, Protamex hydrolysates demonstrated the highest ABTS radical scavenging activity with an RC50 value of 69.69 ± 0.41 µg/mL. Peptides were further isolated from the Protamex hydrolysate using dialysis, fast protein liquid chromatography (FPLC), and high-performance liquid chromatography (HPLC). The most active peptide, STPO-B-II, exhibited a single peak and was identified as a sequence of Glu-Leu-Ala-Lys-Thr-Trp-His-Asp-Met-Lys, designated as MP003. In vivo experiments were conducted using a 2,4-dinitrochlorbenzene (DNCB)-induced AD model in NC/Nga mice. The isolated peptide, MP003, showed significantly reduced AD symptoms, including erythema, lichenification, and collagen deposition. Additionally, MP003 decreased epidermal and dermal thickness, eosinophil, and mast cell infiltration and downregulated the expression of pro-inflammatory cytokines IL-1β, IL-6, and IgE in serum and skin tissues. These findings suggest that peptides derived from Sebastes schlegelii tail by-products may serve as potential therapeutic agents for AD. [ABSTRACT FROM AUTHOR]

Published
2024
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