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Lee YM, Choi DH, Park JH, Cheon MW, Kim JG, Kim JS, Choi T, Kim HR, Youn D. The Effects of Manual Acupuncture on Mitochondrial Fusion and Fission Gene Expression in Rat Spleen. J Acupunct Meridian Stud 2023; 16:49-55. [PMID: 37076179 DOI: 10.51507/j.jams.2023.16.2.49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/15/2022] [Accepted: 03/25/2023] [Indexed: 04/21/2023] Open
Abstract
Background A significant amount of research has been conducted to establish the validity of acupuncture, and it has been demonstrated through animal disease model studies that acupuncture influences mitochondrial changes. However, to more accurately examine the mechanisms of acupuncture treatment effectiveness in pathological models, it is crucial to investigate changes in disease-free animals. Among various hypotheses regarding the effects of acupuncture on the body, we focused on the result that acupuncture stimulation is related to mitochondria. Objectives We examined the effects of acupuncture mitochondrial fission and fusionrelated mediators in disease-free Sprague Dawley (SD) rats' spleen meridian acupoints. Methods SD rats were divided into control, SP1, SP2, SP3, SP5, and SP9 acupuncture groups. Acupuncture was performed at each point for 10 minutes daily for four days. Peroxisome proliferator-activated receptor-gamma coactivator 1-α (PGC-1α) and fission protein 1 (Fis1) levels were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR), while dynamin-related protein 1 (DRP1), optic atrophy-1 (OPA1), mitofusin-1 (MFN1), and mitofusin-2 (MFN2) levels were assessed via western blotting. Mitochondria protein concentrations and NADH dehydrogenase activity in spleen tissues were measured using enzyme-linked immunosorbent assay (ELISA). Results PGC-1α expression decreased in the SP1 (p < 0.01), SP5 (p < 0.05), and SP9 (p < 0.05) groups, while Fis1 expression increased in the SP1 (p < 0.01), SP5 (p < 0.01), and SP9 (p < 0.05) groups. DRP1, OPA1, MFN1, and MFN2 levels exhibited no significant changes. Mitochondrial protein concentrations decreased in the SP2 (p < 0.01), SP3 (p < 0.01), SP5 (p < 0.01), and SP9 (p < 0.01) groups, while NADH dehydrogenase activity decreased in the SP2 (p < 0.05) and SP9 (p < 0.05) groups. Conclusion Acupuncture at the SP9 acupoint influenced the mitochondrial fission pathway by modulating PGC-1α and Fis1 mediators in the rat spleen under non-disease conditions.
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Affiliation(s)
- Yu-Mi Lee
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Dong-Hee Choi
- Department of Korean Medicine, Dongshin University, Naju, Korea
| | - Jeong-Hye Park
- Department of Korean Medicine, Dongshin University, Naju, Korea
| | - Min-Woo Cheon
- Department of Health Administration, Dongshin University, Naju, Korea
| | - Jae Gwan Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Jeong-Sang Kim
- Department of Korean Medicine, Dongshin University, Naju, Korea
| | - Taejin Choi
- DongHaeng Convalescent Hospital, Gwangju, Korea
| | - Hye-Ran Kim
- Department of Korean Medicine, Dongshin University, Naju, Korea
| | - Daehwan Youn
- Department of Korean Medicine, Dongshin University, Naju, Korea
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Lee H, Choi T, Kim SJ, Bak J, Ahn DH, Kramarova NA, Park SS, Kim J, Koo JH. Validations of satellite ozone profiles in austral spring using ozonesonde measurements in the Jang Bogo station, Antarctica. Environ Res 2022; 214:114087. [PMID: 35961543 DOI: 10.1016/j.envres.2022.114087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 06/13/2022] [Accepted: 08/06/2022] [Indexed: 06/15/2023]
Abstract
Using ozonesonde measurements from 2015 to 2018 at the Jang Bogo station located in the southeastern Antarctic region, we evaluate ozone profiles retrieved from the three satellite measurements that are widely used: Ozone Monitoring Instrument (OMI), Microwave Limb Sounder (MLS), and Ozone Mapping Profiler Suite (OMPS) data. For the fair validation, ozonesonde profiles are smoothed using the weighting function of each satellite retrieval algorithm (i.e., convolution process). Compared with limb-viewing MLS and OMPS ozone profiles, the OMI ozone profiles are relatively less qualified: coarser vertical resolution and larger inter-annual variation. Nevertheless, our validation reveals that the quality of all three satellite ozone profiles looks comparable; In general, difference from ozonesonde profile is ∼1 ppm absolutely, and -20 to 30% relatively at maximum. This quantitative range well corresponds to previous work, meaning that our new validation confirms the reliability of satellite ozone profiles in the southeastern Antarctic region where the measurement data for the validation were not enough. Another interesting feature is the role of a priori ozone profile; Nadir-viewing OMI satellite can have qualified ozone profiles by a proper assumption of a priori ozone profile. Since the performance of limb-viewing ozone profiles is better, however, the careful usage of nadir-viewing ozone profile is still required. We think that the simultaneous usage of multiple satellite ozone profiles can contribute to better understanding of Antarctic ozone characteristics.
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Affiliation(s)
- Hana Lee
- Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea; Korea Meteorological Institute, Seoul, South Korea
| | - Taejin Choi
- Korea Polar Research Institute, Incheon, South Korea
| | | | - Juseon Bak
- Institute of Environmental Studies, Pusan National University, Busan, South Korea
| | - Dha Hyun Ahn
- Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea
| | | | - Sang Seo Park
- Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Jhoon Kim
- Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea
| | - Ja-Ho Koo
- Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea.
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Cho S, Heo C, Lim Y, Oh S, Minami D, Yu M, Chun H, Yun S, Seo H, Fang F, Park J, Ham C, Shin J, Choi T, Lim J, Kim H, Hong HR, Shibuya H, Yi J, Choi B, Park K. Small Molecule Based Organic Photo Signal Receiver for High-Speed Optical Wireless Communications. Adv Sci (Weinh) 2022; 9:e2203715. [PMID: 36192160 PMCID: PMC9661864 DOI: 10.1002/advs.202203715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/07/2022] [Indexed: 06/16/2023]
Abstract
The present work describes the development of an organic photodiode (OPD) receiver for high-speed optical wireless communication. To determine the optimal communication design, two different types of photoelectric conversion layers, bulk heterojunction (BHJ) and planar heterojunction (PHJ), are compared. The BHJ-OPD device has a -3 dB bandwidth of 0.65 MHz (at zero bias) and a maximum of 1.4 MHz (at -4 V bias). A 150 Mbps single-channel visible light communication (VLC) data rate using this device by combining preequalization and machine learning (ML)-based digital signal processing (DSP) is demonstrated. To the best of the authors' knowledge, this is the highest data rate ever achieved on an OPD-based VLC system by a factor of 40 over the previous fastest reported. Additionally, the proposed OPD receiver achieves orders of magnitude higher spectral efficiency than the previously reported organic photovoltaic (OPV)-based receivers.
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Affiliation(s)
- Seonghyeon Cho
- Dept. of Information and Telecommunication EngineeringIncheon National UniversityIncheon‐si22012Republic of Korea
| | - Chul‐Joon Heo
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Younhee Lim
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Seoyeon Oh
- Dept. of Information and Telecommunication EngineeringIncheon National UniversityIncheon‐si22012Republic of Korea
| | - Daiki Minami
- CSE teamInnovation CenterSamsung Electronics Co. Ltd.1 Samsungjeonja‐roHwasung‐siGyeonggi‐do18448Republic of Korea
| | - Minseok Yu
- Dept. of Information and Telecommunication EngineeringIncheon National UniversityIncheon‐si22012Republic of Korea
| | - Hyunchae Chun
- Dept. of Information and Telecommunication EngineeringIncheon National UniversityIncheon‐si22012Republic of Korea
- Energy Excellence & Smart City Lab., Incheon National UniversityIncheon‐si22012Republic of Korea
| | - Sungyoung Yun
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Hwijoung Seo
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Feifei Fang
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Jeong‐Il Park
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Cheol Ham
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Jisoo Shin
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Taejin Choi
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Juhyung Lim
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Hyeong‐Ju Kim
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Hye Rim Hong
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Hiromasa Shibuya
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Jeoungin Yi
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Byoungki Choi
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
| | - Kyung‐Bae Park
- Organic Materials LaboratorySamsung Advanced Institute of Technology (SAIT)Samsung Electronics Co. Ltd.130 Samsung‐ro, Yeongtong‐guSuwon‐siGyeonggi‐do443‐803Republic of Korea
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Jun SY, Choi J, Chambers SD, Oh M, Park SJ, Choi T, Kim SJ, Williams AG, Hong SB. Seasonality of Radon-222 near the surface at King Sejong Station (62°S), Antarctic Peninsula, and the role of atmospheric circulation based on observations and CAM-Chem model. Environ Res 2022; 214:113998. [PMID: 35940229 DOI: 10.1016/j.envres.2022.113998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 06/24/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
We examined the seasonal cycle of radon concentration observed at King Sejong Station (KSG, 62°S), Antarctic Peninsula, during the period 2013-2016. The distribution of monthly radon concentration was found to be highly positively skewed from March through October (austral autumn to spring) due to large numbers of short-lived periods of high radon concentration. The global atmospheric chemistry model (CAM-Chem), which includes all global terrestrial sources of radon except for those in Antarctica, well reproduces the observed seasonal cycle of monthly-mean radon concentration at KSG. Further offline experiments suggest that uncertainties in radon emissions over South America and the Southern Ocean should be improved for the simulations of radon in Antarctica. The results demonstrate that seasonally varying transport of radon in the boundary layer from South America substantially affects the seasonality of monthly mean radon concentration at KSG. The composite analyses further reveal that high radon events at KSG are the result of a distinct east-west dipole-like structure associated with surface cyclonic circulation over the Bellingshausen Sea and anticyclonic circulation in the Weddell Sea. This atmospheric pattern provides favorable conditions for radon transport into KSG from the northwest. The relationship between radon concentration at KSG and climate variability is also discussed in this study.
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Affiliation(s)
- Sang-Yoon Jun
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea
| | - Jung Choi
- School of Earth and Environmental Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea
| | - S D Chambers
- Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - Mingi Oh
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea
| | - Sang-Jong Park
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea
| | - Taejin Choi
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea
| | - Seong-Joong Kim
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea
| | - A G Williams
- Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - Sang-Bum Hong
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea.
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Shibuya H, Choi YS, Choi T, Yun S, Moon J, Matsuo Y. Synthesis of n-Type [60]Fullerene Derivatives with Sterically Bulky tert-Butyl Groups for Vacuum Deposition Processes. Chem Asian J 2022; 17:e202200609. [PMID: 35833622 DOI: 10.1002/asia.202200609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/12/2022] [Indexed: 11/11/2022]
Abstract
[60]Fullerene derivatives with high thermal stability can be used for vacuum deposition under heating to fabricate thin films for organic electronic devices. Here we investigated the thermal stability of [60]fullerene derivatives with various bulky substituents for thermal evaporation under vacuum by means of thermogravimetric analysis under reduced and normal pressure. We found sterically bulky groups such as tert -butyl groups of [60]fullerene derivatives lowered the vacuum deposition temperature. Also, we performed isothermal thermogravimetric analysis to examine the long-term thermal stability of the designed compounds under heating conditions. Furthermore, we investigated the UV-Vis absorption patterns of the deposited films. Absorption in the blue wavelength range, which was attributed to intermolecular HOMO-LUMO transitions among the molecular orbitals of adjacent [60]fullerenes, was dramatically modified. These results were associated with the prevention of aggregation among neighboring [60]fullerene by the sterically bulky groups. This concept could contribute to expanding the use of evaporable [60]fullerene derivatives in organic thin-film electronics research fields.
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Affiliation(s)
- Hiromasa Shibuya
- Samsung Advanced Institute of Technology, Material Research Center, 130 Samsung-ro, Yeongtong-gu, 443-803, Suwon, KOREA, REPUBLIC OF
| | - Yeong Suk Choi
- Samsung Advanced Institute of Technology, Material Research Center, 130 Samsung-ro, Yeongtong-gu, 443-803, Suwon, KOREA, REPUBLIC OF
| | - Taejin Choi
- Samsung Advanced Institute of Technology, Material Research Center, 130 Samsung-ro, Yeongtong-gu, 443-803, Suwon, KOREA, REPUBLIC OF
| | - Sungyoung Yun
- Samsung Advanced Institute of Technology, Material Research Center, 130 Samsung-ro, Yeongtong-gu, 443-803, Suwon, KOREA, REPUBLIC OF
| | - Juhee Moon
- Samsung Advanced Institute of Technology, Material Research Center, 130 Samsung-ro, Yeongtong-gu, 443-803, Suwon, KOREA, REPUBLIC OF
| | - Yutaka Matsuo
- Nagoya University: Nagoya Daigaku, Department of Chemical System Engineering, Graduate School of Engineering, Furo-cho, 464-8603, Nagoya, JAPAN
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Labanti C, Wu J, Shin J, Limbu S, Yun S, Fang F, Park SY, Heo CJ, Lim Y, Choi T, Kim HJ, Hong H, Choi B, Park KB, Durrant JR, Kim JS. Light-intensity-dependent photoresponse time of organic photodetectors and its molecular origin. Nat Commun 2022; 13:3745. [PMID: 35768429 PMCID: PMC9243077 DOI: 10.1038/s41467-022-31367-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 06/13/2022] [Indexed: 11/08/2022] Open
Abstract
Organic photodetectors (OPDs) exhibit superior spectral responses but slower photoresponse times compared to inorganic counterparts. Herein, we study the light-intensity-dependent OPD photoresponse time with two small-molecule donors (planar MPTA or twisted NP-SA) co-evaporated with C60 acceptors. MPTA:C60 exhibits the fastest response time at high-light intensities (>0.5 mW/cm2), attributed to its planar structure favoring strong intermolecular interactions. However, this blend exhibits the slowest response at low-light intensities, which is correlated with biphasic photocurrent transients indicative of the presence of a low density of deep trap states. Optical, structural, and energetical analyses indicate that MPTA molecular packing is strongly disrupted by C60, resulting in a larger (370 meV) HOMO level shift. This results in greater energetic inhomogeneity including possible MPTA-C60 adduct formation, leading to deep trap states which limit the low-light photoresponse time. This work provides important insights into the small molecule design rules critical for low charge-trapping and high-speed OPD applications.
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Affiliation(s)
- Chiara Labanti
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
- Centre for Processable Electronics, Imperial College London, London, SW7 2AZ, UK
| | - Jiaying Wu
- Centre for Processable Electronics, Imperial College London, London, SW7 2AZ, UK
- Department of Chemistry, Imperial College London, London, W12 0BZ, UK
- Advanced Materials Thrust, Function Hub, The Hong Kong University of Science and Technology, Nansha, Guangzhou, Guangdong, China
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Jisoo Shin
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Saurav Limbu
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
- Centre for Processable Electronics, Imperial College London, London, SW7 2AZ, UK
| | - Sungyoung Yun
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Feifei Fang
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Song Yi Park
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
- Centre for Processable Electronics, Imperial College London, London, SW7 2AZ, UK
| | - Chul-Joon Heo
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Younhee Lim
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Taejin Choi
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Hyeong-Ju Kim
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Hyerim Hong
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Byoungki Choi
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea
| | - Kyung-Bae Park
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, Korea.
| | - James R Durrant
- Centre for Processable Electronics, Imperial College London, London, SW7 2AZ, UK.
- Department of Chemistry, Imperial College London, London, W12 0BZ, UK.
| | - Ji-Seon Kim
- Department of Physics, Imperial College London, London, SW7 2AZ, UK.
- Centre for Processable Electronics, Imperial College London, London, SW7 2AZ, UK.
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Kim HJ, Jung IS, Jung S, Kim D, Minami D, Byun S, Choi T, Shin J, Yun S, Heo CJ, Park KB, Park SY, Lim SJ, Lee HS, Choi B. Harnessing Intramolecular Chalcogen-Chalcogen Bonding in Merocyanines for Utilization in High-Efficiency Photon-to-Current Conversion Optoelectronics. ACS Appl Mater Interfaces 2022; 14:4360-4370. [PMID: 34890196 DOI: 10.1021/acsami.1c16950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A novel series of donor (D)-π-acceptor (A) merocyanine molecules harnessed with intramolecular chalcogen bonding (ChaB) is designed, synthesized, and characterized. ChaB comprises periodic chalcogen atoms, S, Se, and Te, and a neighboring oxygen atom of a carbonyl moiety. Compared to the D-π-A merocyanine dye with nontraditional intramolecular hydrogen bonding, the novel molecules with an intramolecular ChaB exhibit remarkably smaller absorption spectral widths and higher absorption coefficients attributed to their cyanine-like characteristics approaching the resonance parameter (c2) ∼0.5; furthermore, they exhibit better thermal stabilities and electrical charge-carrier transport properties in films. These novel D-π-A merocyanines harnessed with intramolecular ChaB networks are successfully utilized in high-performance color-selective organic photon-to-current conversion optoelectronic devices with excellent thermal stabilities. This study reports that the unique intramolecular ChaB plays an essential role in locking the molecular conformation of merocyanine molecules and enhancing the optical, thermal, and optoelectronic properties of high-performance and high-efficiency organic photon-to-current conversion devices.
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Affiliation(s)
- Hyeong-Ju Kim
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - In-Sun Jung
- Analytical Engineering Group, Autonomous Material Development Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Seyoung Jung
- Laboratory of Supramolecular Optoelectronic Materials, Department of Materials Science and Engineering, Seoul National University, ENG 445, Seoul 08826, South Korea
| | - Dongmin Kim
- Analytical Engineering Group, Autonomous Material Development Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Daiki Minami
- CSE Team, Data & Information Technology (DIT) Center, Samsung Electronics Co., Limited, 1 Samsungjeonja-ro, Hwasung-si, Gyeonggi-do 18448, South Korea
| | - Sunjung Byun
- Analytical Engineering Group, Autonomous Material Development Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Taejin Choi
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Jisoo Shin
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Sungyoung Yun
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Chul-Joon Heo
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Kyung-Bae Park
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Soo Young Park
- Laboratory of Supramolecular Optoelectronic Materials, Department of Materials Science and Engineering, Seoul National University, ENG 445, Seoul 08826, South Korea
| | - Seon-Jeong Lim
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Hyo Sug Lee
- Analytical Engineering Group, Autonomous Material Development Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
| | - Byoungki Choi
- Organic Material Laboratory, Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Limited, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
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Choi T, Pitus K, Boura J, Pearson C, Stav J. 72 Perceptions of the COVID-19 Vaccine Amongst Health Care Workers in a Southeast Michigan Hospital: A Cross-Sectional Survey. Ann Emerg Med 2021. [PMCID: PMC8335428 DOI: 10.1016/j.annemergmed.2021.07.074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Singha A, Willke P, Bilgeri T, Zhang X, Brune H, Donati F, Heinrich AJ, Choi T. Engineering atomic-scale magnetic fields by dysprosium single atom magnets. Nat Commun 2021; 12:4179. [PMID: 34234133 PMCID: PMC8263604 DOI: 10.1038/s41467-021-24465-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 06/16/2021] [Indexed: 11/08/2022] Open
Abstract
Atomic scale engineering of magnetic fields is a key ingredient for miniaturizing quantum devices and precision control of quantum systems. This requires a unique combination of magnetic stability and spin-manipulation capabilities. Surface-supported single atom magnets offer such possibilities, where long temporal and thermal stability of the magnetic states can be achieved by maximizing the magnet/ic anisotropy energy (MAE) and by minimizing quantum tunnelling of the magnetization. Here, we show that dysprosium (Dy) atoms on magnesium oxide (MgO) have a giant MAE of 250 meV, currently the highest among all surface spins. Using a variety of scanning tunnelling microscopy (STM) techniques including single atom electron spin resonance (ESR), we confirm no spontaneous spin-switching in Dy over days at ≈ 1 K under low and even vanishing magnetic field. We utilize these robust Dy single atom magnets to engineer magnetic nanostructures, demonstrating unique control of magnetic fields with atomic scale tunability.
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Affiliation(s)
- A Singha
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Ewha Womans University, Seoul, Republic of Korea.
- Max Planck Institute for Solid State Research, Stuttgart, Germany.
| | - P Willke
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Ewha Womans University, Seoul, Republic of Korea
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - T Bilgeri
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - X Zhang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Ewha Womans University, Seoul, Republic of Korea
| | - H Brune
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - F Donati
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea
| | - A J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea.
| | - T Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea.
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10
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Lim Y, Yun S, Minami D, Choi T, Choi H, Shin J, Park S, Heo CJ, Leem DS, Yagi T, Park KB, Kim S. Correction to "Green-Light-Selective Organic Photodiodes with High Detectivity for CMOS Color Image Sensors". ACS Appl Mater Interfaces 2021; 13:10664. [PMID: 33595269 DOI: 10.1021/acsami.1c01930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Younhee Lim
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Sungyoung Yun
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Daiki Minami
- Data & Information Technology (DIT) Center, Samsung Electronics, Co. Ltd, Hwaseong-si, Gyeonggido 18448, Korea
| | - Taejin Choi
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Hyesung Choi
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Jisoo Shin
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Sungjun Park
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Chul-Joon Heo
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Dong-Seok Leem
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Tadao Yagi
- MD-2 Lab, Samsung R&D Institute Japan-Yokohama (SRJ-Y), Samsung Electronics, Co. Ltd., 2-7, Sugasawa-cho, Tsurumi-ku, Yokohama 230-0027, Japan
| | - Kyung-Bae Park
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Sunghan Kim
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
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Lim Y, Yun S, Minami D, Choi T, Choi H, Shin J, Heo CJ, Leem DS, Yagi T, Park KB, Kim S. Green-Light-Selective Organic Photodiodes with High Detectivity for CMOS Color Image Sensors. ACS Appl Mater Interfaces 2020; 12:51688-51698. [PMID: 33164496 DOI: 10.1021/acsami.0c14237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Stacked structures employing wavelength-selective organic photodiodes (OPDs) have been studied as promising alternatives to the conventional Si-based image sensors because of their color constancy. Herein, novel donor (D)-π-acceptor (A) molecules are designed, synthesized, and characterized as green-light-selective absorbers for application in organic-on-Si hybrid complementary metal-oxide-semiconductor (CMOS) color image sensors. The p-type molecules, combined with two fused-type heterocyclic donors and an electron-accepting unit, exhibit cyanine-like properties that are characterized by intense and sharp absorption. This molecular design leads to improved absorption properties, thermal stability, and higher photoelectric conversion compared to those of a molecular design based on a nonfused ring. A maximum external quantum efficiency of 66% (λmax = 550 nm) and high specific detectivity (D*) of 8 × 1013 cm Hz1/2/W are achieved in an OPD consisting of a bulk heterojunction blend with two transparent electrodes on both sides. Finally, the green-light-detection capability of the narrow-band green-selective OPD is demonstrated by the optical simulation of an organic-on-Si hybrid, stacked-type, full-color photodetector comprising the green-light-selective OPD and a bottom Si photodiode with only blue and red color filters. Based on this molecular design, further optimization of the OPDs can allow the development of various optoelectronic sensors including 3D-stacked image sensors with enhanced sensitivities to replace the conventional Si-based CMOS image sensors.
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Affiliation(s)
- Younhee Lim
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Sungyoung Yun
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Daiki Minami
- Data & Information Technology (DIT) Center, Samsung Electronics, Co. Ltd, 1, Samsungjeonja-ro, Hwaseong-si, Gyeonggi-do 18448, Korea
| | - Taejin Choi
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Hyesung Choi
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Jisoo Shin
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Chul-Joon Heo
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Dong-Seok Leem
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Tadao Yagi
- MD-2 Lab, Samsung R&D Institute Japan-Yokohama (SRJ-Y), Samsung Electronics, Co. Ltd., 2-7, Sugasawa-cho, Tsurumi-ku, Yokohama 230-0027, Japan
| | - Kyung-Bae Park
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Sunghan Kim
- Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
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12
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Choi T, Im CH, Kim SJ, Kim H, Lee JM. Prediction Method of Walking Speed at Swing Phase using Soleus Electromyogram Signal at Previous Stance Phase. Annu Int Conf IEEE Eng Med Biol Soc 2019; 2018:2308-2311. [PMID: 30440868 DOI: 10.1109/embc.2018.8512867] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A recent research has proposed a prediction method of walking speed with soleus electromyogram (EMG) signal activation level at push-off phase. However, the prediction of walking speed at low speed is inaccurate and the coefficients of determination (R2 values) of the used linear regression model is low. In this study, we propose a new method for predicting walking speed during swing phase with soleus EMG signal activation levels at pre-load and push-off phases, and square root value is used as a feature. The proposed method is verified by walking experiment with 5 nondisabled subjects. (R2 values) of the new method is improved by 10.3 % than that of the method used in the previous study. And the proposed method improves accuracy mainly at low speed and precision at high speed to predict a correct walking speed throughout walking speed range. Thus, the proposed method enhances the performance of the prediction model of walking speed without being biased in the range of high or low speed. The proposed method has potential to be used to control the gait speed of a lower-limb exoskeleton according to wearer's gait intention.
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13
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Bae Y, Yang K, Willke P, Choi T, Heinrich AJ, Lutz CP. Enhanced quantum coherence in exchange coupled spins via singlet-triplet transitions. Sci Adv 2018; 4:eaau4159. [PMID: 30430136 PMCID: PMC6226279 DOI: 10.1126/sciadv.aau4159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/10/2018] [Indexed: 06/02/2023]
Abstract
Manipulation of spin states at the single-atom scale underlies spin-based quantum information processing and spintronic devices. These applications require protection of the spin states against quantum decoherence due to interactions with the environment. While a single spin is easily disrupted, a coupled-spin system can resist decoherence by using a subspace of states that is immune to magnetic field fluctuations. Here, we engineered the magnetic interactions between the electron spins of two spin-1/2 atoms to create a "clock transition" and thus enhance their spin coherence. To construct and electrically access the desired spin structures, we use atom manipulation combined with electron spin resonance (ESR) in a scanning tunneling microscope. We show that a two-level system composed of a singlet state and a triplet state is insensitive to local and global magnetic field noise, resulting in much longer spin coherence times compared with individual atoms. Moreover, the spin decoherence resulting from the interaction with tunneling electrons is markedly reduced by a homodyne readout of ESR. These results demonstrate that atomically precise spin structures can be designed and assembled to yield enhanced quantum coherence.
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Affiliation(s)
- Y. Bae
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - K. Yang
- IBM Almaden Research Center, San Jose, CA 95120, USA
| | - P. Willke
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - T. Choi
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - A. J. Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - C. P. Lutz
- IBM Almaden Research Center, San Jose, CA 95120, USA
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Kim DH, Shin S, Kim N, Choi T, Choi S, Choi Y. Carotid ultrasound measurements for assessing fluid responsiveness in spontaneously breathing patients: corrected flow time and respirophasic variation in blood flow peak velocity. Br J Anaesth 2018; 121:541-549. [DOI: 10.1016/j.bja.2017.12.047] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/21/2017] [Accepted: 03/13/2018] [Indexed: 10/17/2022] Open
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15
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Kim JG, Cha MC, Lee J, Choi T, Chang JY. Preparation of a Sulfur-Functionalized Microporous Polymer Sponge and In Situ Growth of Silver Nanoparticles: A Compressible Monolithic Catalyst. ACS Appl Mater Interfaces 2017; 9:38081-38088. [PMID: 28994573 DOI: 10.1021/acsami.7b14807] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report a compressible monolithic catalyst based on a microporous organic polymer (MOP) sponge. The monolithic MOP sponge was synthesized via Sonogashira-Hagihara coupling reaction between 1,4-diiodotetrafluorobenzene and 1,3,5-triethynylbenzene in a cosolvent of toluene and TEA (2:1, v/v) without stirring. The MOP sponge had an intriguing microstructure, where tubular polymer fibers having a diameter of hundreds of nanometers were entangled. It showed hierarchical porosity with a Brunauer-Emmett-Teller (BET) surface area of 512 m2 g-1. The MOP sponge was functionalized with sulfur groups by the thiol-yne reaction. The functionalized MOP sponge exhibited a higher BET surface area than the MOP sponge by 13% due to the increase in the total pore and micropore volumes. A MOP sponge-Ag heterogeneous catalyst (S-MOPS-Ag) was prepared by in situ growth of silver nanoparticles inside the sulfur-functionalized MOP sponge by the reduction of Ag+ ions. The catalytic activity of S-MOPS-Ag was investigated for the reduction reaction of 4-nitrophenol in an aqueous condition. When S-MOPS-Ag was compressed and released during the reaction, the rate of the reaction was considerably increased. S-MOPS-Ag was easily removed from the reaction mixture owing to its monolithic character and was reused after washing and drying.
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Affiliation(s)
- Jong Gil Kim
- Department of Materials Science and Engineering, College of Engineering, Seoul National University , Seoul 08826, Korea
| | - Min Chul Cha
- Department of Materials Science and Engineering, College of Engineering, Seoul National University , Seoul 08826, Korea
| | - Jeongmin Lee
- Department of Materials Science and Engineering, College of Engineering, Seoul National University , Seoul 08826, Korea
| | - Taejin Choi
- Department of Materials Science and Engineering, College of Engineering, Seoul National University , Seoul 08826, Korea
| | - Ji Young Chang
- Department of Materials Science and Engineering, College of Engineering, Seoul National University , Seoul 08826, Korea
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Chung SH, Choi T, Hwang Y, Kim H, Kim SJ, Chun MH, Lee JM. Walking speed intention model using soleus electromyogram signal of nondisabled and post-stroke hemiparetic patients. IEEE Int Conf Rehabil Robot 2017; 2017:308-313. [PMID: 28813837 DOI: 10.1109/icorr.2017.8009265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
It is well known that the activation of plantar flexors have a strong influence on the walking speed. If the gait speed can be predicted using this relationship, a post-stroke hemiparetic patient could control a gait rehabilitation robot according to his or her gait intention, and the robotic gait rehabilitation effect could be further improved. To find out this relationship, 9 nondisabled subjects and 4 chronic post-stroke hemiparetic subjects performed overground level walking at a comfortable pace, a slow pace, a fast pace, and an increasing pace with electromyogram sensors attached on plantar flexors. Soleus among plantar flexors showed the most stable relationship with walking speed. The relationship between maximum activation level of soleus electromyogram during stance phase before toe-off and walking speed during swing phase after the same toe-off was modeled by a polynomial regression model. The model outputs were then compared to the measured walking speeds using coefficients of determination (R2). The average R2 values are 0.594 and 0.692 for 1st· and 2nd order models respectively in the nondisabled subjects. The average R2 values are 0.598 and 0.623 for the unaffected side and 0.388 and 0.394 for the affected side in the chronic subjects. The results show the feasibility of applying the soleus-walking speed relationship to control the robot gait speed at will. A walking speed estimation method is proposed using only a walking step in real time.
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Mahboob A, Choi T, Park B, Park MN, Choy YH. 199 Genetic correlation between body weights and frame size measures in Hanwoo. J Anim Sci 2017. [DOI: 10.2527/asasann.2017.199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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18
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Choy YH, Mahboob A, Choi T, Park B, Park MN. 200 Genetic correlation between yearling body size traits and carcass traits in Hanwoo steers. J Anim Sci 2017. [DOI: 10.2527/asasann.2017.200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Chong E, Choi T, Kim H, Kim SJ, Hwang Y, Lee JM. Informative sensor selection and learning for prediction of lower limb kinematics using generative stochastic neural networks. Annu Int Conf IEEE Eng Med Biol Soc 2017; 2017:2043-2046. [PMID: 29060298 DOI: 10.1109/embc.2017.8037254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We propose a novel approach of selecting useful input sensors as well as learning a mathematical model for predicting lower limb joint kinematics. We applied a feature selection method based on the mutual information called the variational information maximization, which has been reported as the state-of-the-art work among information based feature selection methods. The main difficulty in applying the method is estimating reliable probability density of input and output data, especially when the data are high dimensional and real-valued. We addressed this problem by applying a generative stochastic neural network called the restricted Boltzmann machine, through which we could perform sampling based probability estimation. The mutual informations between inputs and outputs are evaluated in each backward sensor elimination step, and the least informative sensor is removed with its network connections. The entire network is fine-tuned by maximizing conditional likelihood in each step. Experimental results are shown for 4 healthy subjects walking with various speeds, recording 64 sensor measurements including electromyogram, acceleration, and foot-pressure sensors attached on both lower limbs for predicting hip and knee joint angles. For test set of walking with arbitrary speed, our results show that our suggested method can select informative sensors while maintaining a good prediction accuracy.
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Kwon H, Kim SW, Lee S, Park SJ, Choi T, Jeong JH, Kim SJ, Kim BM. A Numerical Simulation Study of Strong Wind Events at Jangbogo Station, Antarctica. Atmosphere 2016. [DOI: 10.14191/atmos.2016.26.4.617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ko KY, Song JG, Kim Y, Choi T, Shin S, Lee CW, Lee K, Koo J, Lee H, Kim J, Lee T, Park J, Kim H. Improvement of Gas-Sensing Performance of Large-Area Tungsten Disulfide Nanosheets by Surface Functionalization. ACS Nano 2016; 10:9287-9296. [PMID: 27666720 DOI: 10.1021/acsnano.6b03631] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising gas-sensing materials due to their large surface-to-volume ratio. However, their poor gas-sensing performance resulting from the low response, incomplete recovery, and insufficient selectivity hinders the realization of high-performance 2D TMDC gas sensors. Here, we demonstrate the improvement of gas-sensing performance of large-area tungsten disulfide (WS2) nanosheets through surface functionalization using Ag nanowires (NWs). Large-area WS2 nanosheets were synthesized through atomic layer deposition of WO3 followed by sulfurization. The pristine WS2 gas sensors exhibited a significant response to acetone and NO2 but an incomplete recovery in the case of NO2 sensing. After AgNW functionalization, the WS2 gas sensor showed dramatically improved response (667%) and recovery upon NO2 exposure. Our results establish that the proposed method is a promising strategy to improve 2D TMDC gas sensors.
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Affiliation(s)
| | | | | | | | | | | | | | - Jahyun Koo
- Department of Physics, Konkuk University , 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
| | - Hoonkyung Lee
- Department of Physics, Konkuk University , 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
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Choi T, Neven A, Al Hadithy AFY. [A disulfiram-alcohol reaction after inhalation of a salbutamol aerosol: a plausible interaction?]. Tijdschr Psychiatr 2016; 58:407-410. [PMID: 27213641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
An asthmatic patient (male, aged 47) being treated for his alcohol dependence complained of experiencing mild symptoms of disulfiram-alcohol reaction after using of pressurised metered-dose inhaler containing ethanol. It has been reported in the literature that the disulfiram-alcohol reaction may occur after a patient has been exposed to only minimal amounts of ethanol. This is why, in daily practice, physicians are generally reluctant to prescribe preparations containing ethanol and why they usually switch patients to an alternative. However, close evaluation of the biopharmaceutical and pharmacokinetic aspects of ethanol suggests that subjective disulfiram-alcohol reactions following the use of inhalers containing ethanol cannot be explained rationally from a clinical pharmacological perspective.
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Taniguchi Y, Takahashi Y, Toba T, Yamada S, Yokoi K, Kobayashi S, Okajima S, Shimane A, Kawai H, Yasaka Y, Smanio P, Oliveira MA, Machado L, Cestari P, Medeiros E, Fukuzawa S, Okino S, Ikeda A, Maekawa J, Ichikawa S, Kuroiwa N, Yamanaka K, Igarashi A, Inagaki M, Patel K, Mahan M, Ananthasubramaniam K, Mouden M, Yokota S, Ottervanger J, Knollema S, Timmer J, Jager P, Padron K, Peix A, Cabrera L, Pena Bofill V, Valera D, Rodriguez Nande L, Carrillo Hernandez R, Mena Esnard E, Fernandez Columbie Y, Bertella E, Baggiano A, Mushtaq S, Segurini C, Loguercio M, Conte E, Beltrama V, Petulla' M, Andreini D, Pontone G, Guzic Salobir B, Dolenc Novak M, Jug B, Kacjan B, Novak Z, Vrtovec M, Mushtaq S, Pontone G, Bertella E, Conte E, Segurini C, Volpato V, Baggiano A, Formenti A, Pepi M, Andreini D, Ajanovic R, Husic-Selimovic A, Zujovic-Ajanovic A, Mlynarski R, Mlynarska A, Golba K, Sosnowski M, Ameta D, Goyal M, Kumar D, Chandra S, Sethi R, Puri A, Dwivedi SK, Narain VS, Saran RK, Nekolla S, Rischpler C, Nicolosi S, Langwieser N, Dirschinger R, Laugwitz K, Schwaiger M, Goral JL, Napoli J, Forcada P, Zucchiatti N, Damico A, Damico A, Olivieri D, Lavorato M, Dubesarsky E, Montana O, Salgado C, Jimenez-Heffernan A, Ramos-Font C, Lopez-Martin J, Sanchez De Mora E, Lopez-Aguilar R, Manovel A, Martinez A, Rivera F, Soriano E, Maroz-Vadalazhskaya N, Trisvetova E, Vrublevskaya O, Abazid R, Kattea M, Saqqah H, Sayed S, Smettei O, Winther S, Svensson M, Birn H, Jorgensen H, Botker H, Ivarsen P, Bottcher M, Maaniitty T, Stenstrom I, Saraste A, Pikkarainen E, Uusitalo V, Ukkonen H, Kajander S, Bax J, Knuuti J, Choi T, Park H, Lee C, Lee J, Seo Y, Cho Y, Hwang E, Cho D, Sanchez Enrique C, Ferrera C, Olmos C, Jimenez - Ballve A, Perez - Castejon MJ, Fernandez C, Vivas D, Vilacosta I, Nagamachi S, Onizuka H, Nishii R, Mizutani Y, Kitamura K, Lo Presti M, Polizzi V, Pino P, Luzi G, Bellavia D, Fiorilli R, Madeo A, Malouf J, Buffa V, Musumeci F, Rosales S, Puente A, Zafrir N, Shochat T, Mats A, Solodky A, Kornowski R, Lorber A, Boemio A, Pellegrino T, Paolillo S, Piscopo V, Carotenuto R, Russo B, Pellegrino S, De Matteis G, Perrone-Filardi P, Cuocolo A, Piscopo V, Pellegrino T, Boemio A, Carotenuto R, Russo B, Pellegrino S, De Matteis G, Petretta M, Cuocolo A, Amirov N, Ibatullin M, Sadykov A A, Saifullina G, Ruano R, Diego Dominguez M, Rodriguez Gabella T, Diego Nieto A, Diaz Gonzalez L, Garcia-Talavera J, Sanchez Fernandez P, Leen A, Al Younis I, Zandbergen-Harlaar S, Verberne H, Gimelli A, Veltman C, Wolterbeek R, Bax J, Scholte A, Mooney D, Rosenblatt J, Dunn T, Vasaiwala S, Okuda K, Nakajima K, Nystrom K, Edenbrandt L, Matsuo S, Wakabayashi H, Hashimoto M, Kinuya S, Iric-Cupic V, Milanov S, Davidovic G, Zdravkovic V, Ashikaga K, Yoneyama K, Akashi Y, Shugushev Z, Maximkin D, Chepurnoy A, Volkova O, Baranovich V, Faibushevich A, El Tahlawi M, Elmurr A, Alzubaidi S, Sakrana A, Gouda M, El Tahlawi R, Sellem A, Melki S, Elajmi W, Hammami H, Okano M, Kato T, Kimura M, Funasako M, Nakane E, Miyamoto S, Izumi T, Haruna T, Inoko M, Massardo T, Swett E, Fernandez R, Vera V, Zhindon J, Fernandez R, Swett E, Vera V, Zhindon J, Alay R, Massardo T, Ohshima S, Nishio M, Kojima A, Tamai S, Kobayashi T, Murohara T, Burrell S, Van Rosendael A, Van Den Hoogen I, De Graaf M, Roelofs J, Kroft L, Bax J, Scholte A, Rjabceva I, Krumina G, Kalvelis A, Chanakhchyan F, Vakhromeeva M, Kankiya E, Koppes J, Knol R, Wondergem M, Van Der Ploeg T, Van Der Zant F, Lazarenko SV, Bruin VS, Pan XB, Declerck JM, Van Der Zant FM, Knol RJJ, Juarez-Orozco LE, Alexanderson E, Slart R, Tio R, Dierckx R, Zeebregts C, Boersma H, Hillege H, Martinez-Aguilar M, Jordan-Rios A, Christensen TE, Ahtarovski KA, Bang LE, Holmvang L, Soeholm H, Ghotbi AA, Andersson H, Ihlemann N, Kjaer A, Hasbak P, Gulya M, Lishmanov YB, Zavadovskii K, Lebedev D, Stahle M, Hellberg S, Liljenback H, Virta J, Metsala O, Yla-Herttuala S, Saukko P, Knuuti J, Saraste A, Roivainen A, Thackeray J, Wang Y, Bankstahl J, Wollert K, Bengel F, Saushkina Y, Evtushenko V, Minin S, Efimova I, Evtushenko A, Smishlyaev K, Lishmanov Y, Maslov L, Okuda K, Nakajima K, Kirihara Y, Sugino S, Matsuo S, Taki J, Hashimoto M, Kinuya S, Ahmadian A, Berman J, Govender P, Ruberg F, Miller E, Piriou N, Pallardy A, Valette F, Cahouch Z, Mathieu C, Warin-Fresse K, Gueffet J, Serfaty J, Trochu J, Kraeber-Bodere F, Van Dijk J, Mouden M, Ottervanger J, Van Dalen J, Jager P, Zafrir N, Ofrk H, Vaturi M, Shochat T, Hassid Y, Belzer D, Sagie A, Kornowski R, Kaminek M, Metelkova I, Budikova M, Koranda P, Henzlova L, Sovova E, Kincl V, Drozdova A, Jordan M, Shahid F, Teoh Y, Thamen R, Hara N, Onoguchi M, Hojyo O, Kawaguchi Y, Murai M, Udaka F, Matsuzawa Y, Bulugahapitiya DS, Avison M, Martin J, Liu YH, Wu J, Liu C, Sinusas A, Daou D, Sabbah R, Bouladhour H, Coaguila C, Aguade-Bruix S, Pizzi M, Romero-Farina G, Candell-Riera J, Castell-Conesa J, Patchett N, Sverdlov A, Miller E, Daou D, Sabbah R, Bouladhour H, Coaguila C, Smettei O, Abazid R, Boulaamayl El Fatemi S, Sallam L, Snipelisky D, Park J, Ray J, Shapiro B, Kostkiewicz M, Szot W, Holcman K, Lesniak-Sobelga A, Podolec P, Clerc O, Possner M, Liga R, Vontobel J, Mikulicic F, Graeni C, Benz D, Herzog B, Gaemperli O, Kaufmann P. Poster Session 1: Sunday 3 May 2015, 08:30-18:00 * Room: Poster Area. Eur Heart J Cardiovasc Imaging 2015. [DOI: 10.1093/ehjci/jev051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Kim M, Cho A, Lim HS, Hong SG, Kim JH, Lee J, Choi T, Ahn TS, Kim OS. Highly heterogeneous soil bacterial communities around Terra Nova Bay of Northern Victoria Land, Antarctica. PLoS One 2015; 10:e0119966. [PMID: 25799273 PMCID: PMC4370865 DOI: 10.1371/journal.pone.0119966] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 01/18/2015] [Indexed: 11/19/2022] Open
Abstract
Given the diminished role of biotic interactions in soils of continental Antarctica, abiotic factors are believed to play a dominant role in structuring of microbial communities. However, many ice-free regions remain unexplored, and it is unclear which environmental gradients are primarily responsible for the variations among bacterial communities. In this study, we investigated the soil bacterial community around Terra Nova Bay of Victoria Land by pyrosequencing and determined which environmental variables govern the bacterial community structure at the local scale. Six bacterial phyla, Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi, Cyanobacteria, and Bacteroidetes, were dominant, but their relative abundance varied greatly across locations. Bacterial community structures were affected little by spatial distance, but structured more strongly by site, which was in accordance with the soil physicochemical compositions. At both the phylum and species levels, bacterial community structure was explained primarily by pH and water content, while certain earth elements and trace metals also played important roles in shaping community variation. The higher heterogeneity of the bacterial community structure found at this site indicates how soil bacterial communities have adapted to different compositions of edaphic variables under extreme environmental conditions. Taken together, these findings greatly advance our understanding of the adaption of soil bacterial populations to this harsh environment.
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Affiliation(s)
- Mincheol Kim
- Arctic Research Center, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Ahnna Cho
- Division of Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
- Department of Environmental Science, Kangwon National University, Chuncheon, Republic of Korea
| | - Hyoun Soo Lim
- Department of Geological Sciences, Pusan National University, Busan, Republic of Korea
| | - Soon Gyu Hong
- Division of Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Ji Hee Kim
- Department of New Antarctic Station, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Joohan Lee
- Department of New Antarctic Station, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Taejin Choi
- Division of Climate Change, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Tae Seok Ahn
- Department of Environmental Science, Kangwon National University, Chuncheon, Republic of Korea
| | - Ok-Sun Kim
- Division of Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
- * E-mail:
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Kim H, Choi T, Park J, Jae H, Hur S, Jung H, Kim H. The safety and clinical outcome of chemoembolization in Child-Pugh class C patients with hepatocellular carcinoma. J Vasc Interv Radiol 2015. [DOI: 10.1016/j.jvir.2014.12.081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Park J, Lee W, Choi T, Hwang SH, Myoung JM, Jung JH, Kim SH, Kim H. Layer-modulated synthesis of uniform tungsten disulfide nanosheet using gas-phase precursors. Nanoscale 2015; 7:1308-1313. [PMID: 25361429 DOI: 10.1039/c4nr04292a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The synthesis of layered transition-metal-disulfide (MS2, M = Mo, W) nanosheets with layer controllability and large-area uniformity is an essential requirement for their application in electronic and optical devices. In this report, we describe a synthesis process of WS2 nanosheets with layer controllability and high uniformity using chemical vapor deposition (CVD) and WCl6 and H2S as gas-phase precursors. Through this process, we can systematically modulate the thickness of WS2 nanosheets by controlling the duration of the reaction between WCl6 and H2S. The CVD-grown WS2 nanosheets exhibit good stoichiometry as well as dependencies of a clear Raman shift and bandgap on the number of layers. These properties are confirmed by X-ray photoemission spectroscopy, Raman spectroscopy, and photoluminescence measurements. The number of layers of WS2 nanosheets is confirmed by atomic force microscopy. Finally, we demonstrate the fabrication and performance of a photodetector based on a hybrid structure consisting of graphene and a WS2 nanosheet.
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Affiliation(s)
- Jusang Park
- School of Electrical and Electronics Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul, 120-749, Republic of Korea.
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Choi T, Kim SH, Lee CW, Kim H, Choi SK, Kim SH, Kim E, Park J, Kim H. Synthesis of carbon nanotube–nickel nanocomposites using atomic layer deposition for high-performance non-enzymatic glucose sensing. Biosens Bioelectron 2015; 63:325-330. [DOI: 10.1016/j.bios.2014.07.059] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 07/18/2014] [Accepted: 07/18/2014] [Indexed: 01/29/2023]
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Davar D, Choi T, Kirkwood J. Reply to the letters to the editor ‘Differential influence of vemurafenib and dabrafenib on patients' lymphocytes despite similar clinical efficacy in melanoma’ by Schilling et al. Ann Oncol 2015; 26:251-252. [DOI: 10.1093/annonc/mdu512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Chen J, Kamiya Y, Polur I, Xu M, Choi T, Kalajzic Z, Drissi H, Wadhwa S. Estrogen via estrogen receptor beta partially inhibits mandibular condylar cartilage growth. Osteoarthritis Cartilage 2014; 22:1861-8. [PMID: 25046534 PMCID: PMC4252977 DOI: 10.1016/j.joca.2014.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 07/01/2014] [Accepted: 07/10/2014] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Temporomandibular joint (TMJ) diseases predominantly afflict women, suggesting a role for female hormones in the disease process. However, little is known about the role of estrogen receptor (ER) signaling in regulating mandibular condylar cartilage growth. Therefore, the goal of this study was to examine the effects of altered estrogen levels on the mandibular condylar cartilage in wild type (WT) and ER beta Knockout (KO) mice. MATERIALS AND METHODS 21-day-old female WT (n = 37) and ER beta KO mice (n = 36) were either sham operated or ovariectomized, and treated with either placebo or estradiol. The mandibular condylar cartilage was evaluated by histomorphometry, proliferation was analyzed by double ethynyl-2'-deoxyuridine/bromodeoxyuridine (EdU/BrdU) labeling, and assays on gene and protein expression of chondrocyte maturation markers were performed. RESULTS In WT mice, ovariectomy caused a significant increase in mandibular condylar cartilage cell numbers, a significant increase in Sox9 expression and a significant increase in proliferation compared with sham operated WT mice. In contrast, ovariectomy did not cause any of these effects in the ER beta KO mice. Estrogen replacement treatment in ovariectomized WT mice caused a significant decrease in ER alpha expression and a significant increase in Sost expression compared with ovariectomized mice treated with placebo. Estrogen replacement treatment in ovariectomized ER beta KO mice caused a significant increase in Col2 expression, no change in ER alpha expression, and a significant increase in Sost expression. CONCLUSION Estrogen via ER beta inhibits proliferation and ER alpha expression while estrogen independent of ER beta induces Col2 and Sost expression.
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Affiliation(s)
- J. Chen
- Division of Orthodontics, Columbia University College of Dental Medicine, New York, NY, USA
| | - Y. Kamiya
- Division of Orthodontics, Columbia University College of Dental Medicine, New York, NY, USA
| | - I. Polur
- Division of Orthodontics, Columbia University College of Dental Medicine, New York, NY, USA
| | - M. Xu
- Division of Orthodontics, Columbia University College of Dental Medicine, New York, NY, USA
| | - T. Choi
- Columbia University College of Dental Medicine, New York, NY, USA
| | - Z. Kalajzic
- Division of Orthodontics, School of Dental Medicine, University of Connecticut Health Center, Farmington, CT, USA
| | - H. Drissi
- Department of Orthopedic Surgery, University of Connecticut Health Center, Farmington, CT, USA
| | - S. Wadhwa
- Division of Orthodontics, Columbia University College of Dental Medicine, New York, NY, USA
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Park B, Choi T, Kim S, Oh SH. National genetic evaluation (system) of hanwoo (korean native cattle). Asian-Australas J Anim Sci 2014; 26:151-6. [PMID: 25049770 PMCID: PMC4093164 DOI: 10.5713/ajas.2012.12439] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/05/2012] [Accepted: 10/04/2012] [Indexed: 12/02/2022]
Abstract
Hanwoo (Also known as Korean native cattle; Bos taurus coreanae) have been used for transportation and farming for a long time in South Korea. It has been about 30 yrs since Hanwoo improvement began in earnest as beef cattle for meat yield. The purpose of this study was to determine the trend of improvement as well as to estimate genetic parameters of the traits being used for seedstock selection based on the data collected from the past. Hanwoo proven bulls in South Korea are currently selected through performance and progeny tests. National Hanwoo genetic evaluations are implemented with yearling weight (YW), carcass weight (CW), eye muscle area (EMA), backfat thickness (BF) and marbling score (MS). Yearling weights and MS are used for selecting young bulls, and EMA, BF, and MS are used for selecting proven bulls. One individual per testing room was used for performance tests, and five individuals per room for progeny tests. Individuals tested were not allowed to graze pasture, but there was enough space for them to move around in the testing room. Feeds including roughages and minerals were fed ad libitum, and concentrates were provided at the rate of about 1.8% of individual weight. Overall means of the traits were 352.8±38.56 kg, 335.09±44.61 kg, 77.85±8.838 cm2, 8.6±3.7 mm and 3.293±1.648 for YW, CW, EMA, BF and MS. Heritabilities estimated in this study were 0.30, 0.30, 0.42, 0.50 and 0.63 in YW, CW, EMA, BF and MS, respectively, which are similar to results from previous research. Yearling weight was 315.54 kg in 1998, and had increased to 355.06 kg in 2011, resulting in about 40 kg of improvement over 13 yrs. YW and CW have improved remarkably over the past 15 yrs. Breeding values between 1996 and 2000 decreased or did not change much, but have moved in a desirable direction since 2001. These improvements correspond with the substantial increase in use of animal models since the late 1990s in Korea. Hanwoo testing programs have practically contributed to the improvement in aspects of quality and quantity. In sum, the current selection system is good enough to accommodate circumstances where fewer sires are used on many more cows. Although progeny tests take longer and cost more, they seem to be appropriate under the circumstances of the domestic market with its higher requirement for better meat quality. Consequently, accumulative data collection, genetic evaluation model development, revision of selection indices, as well as cooperation among farms, associations, National Agricultural Cooperative Federation, universities, research institutes, and government agencies must be applied to the Hanwoo selection program. All these efforts will assist the domestic market to secure a competitive position against imported beef under Free Trade Agreement trade system and will provide farmers with higher profits as well as the public with a higher quality of beef.
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Affiliation(s)
- B Park
- National Institute of Animal Science, Cheonan, Korea
| | - T Choi
- National Institute of Animal Science, Cheonan, Korea
| | - S Kim
- National Institute of Animal Science, Cheonan, Korea
| | - S-H Oh
- National Institute of Animal Science, Cheonan, Korea
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Diwakar D, Choi T, Tawbi TH, Kirkwood JM. Re: Differential influence of vemurafenib and dabrafenib on patients' lymphocytes despite similar clinical efficacy in melanoma. Ann Oncol 2014; 25:1670-1. [PMID: 24890848 DOI: 10.1093/annonc/mdu196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- D Diwakar
- Division of Hematology-Oncology, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, USA
| | - T Choi
- Division of Hematology-Oncology, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, USA
| | - T H Tawbi
- Division of Hematology-Oncology, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, USA
| | - J M Kirkwood
- Division of Hematology-Oncology, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, USA
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Islam R, Campbell WC, Choi T, Clark SM, Conover CWS, Debnath S, Edwards EE, Fields B, Hayes D, Hucul D, Inlek IV, Johnson KG, Korenblit S, Lee A, Lee KW, Manning TA, Matsukevich DN, Mizrahi J, Quraishi Q, Senko C, Smith J, Monroe C. Beat note stabilization of mode-locked lasers for quantum information processing. Opt Lett 2014; 39:3238-3241. [PMID: 24876022 DOI: 10.1364/ol.39.003238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We stabilize a chosen radio frequency beat note between two optical fields derived from the same mode-locked laser pulse train in order to coherently manipulate quantum information. This scheme does not require access or active stabilization of the laser repetition rate. We implement and characterize this external lock, in the context of two-photon stimulated Raman transitions between the hyperfine ground states of trapped 171Yb(+) quantum bits.
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Choi T, Debnath S, Manning TA, Figgatt C, Gong ZX, Duan LM, Monroe C. Optimal quantum control of multimode couplings between trapped ion qubits for scalable entanglement. Phys Rev Lett 2014; 112:190502. [PMID: 24877921 DOI: 10.1103/physrevlett.112.190502] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Indexed: 06/03/2023]
Abstract
We demonstrate entangling quantum gates within a chain of five trapped ion qubits by optimally shaping optical fields that couple to multiple collective modes of motion. We individually address qubits with segmented optical pulses to construct multipartite entangled states in a programmable way. This approach enables high-fidelity gates that can be scaled to larger qubit registers for quantum computation and simulation.
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Affiliation(s)
- T Choi
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - S Debnath
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - T A Manning
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - C Figgatt
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - Z-X Gong
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - L-M Duan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - C Monroe
- Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA
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Choi T, Cho SY. Comment on "Aharonov-Casher and scalar Aharonov-Bohm topological effects". Phys Rev Lett 2014; 112:158901. [PMID: 24785079 DOI: 10.1103/physrevlett.112.158901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Indexed: 06/03/2023]
Affiliation(s)
- T Choi
- Division of General Education, Seoul Women's University, Seoul 139-774, Korea
| | - S Y Cho
- Center for Modern Physics and Department of Physics, Chongqing University, Chongqing 400030, China
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Choi T, Badal M, Loth S, Yoo JW, Lutz CP, Heinrich AJ, Epstein AJ, Stroud DG, Gupta JA. Magnetism in single metalloorganic complexes formed by atom manipulation. Nano Lett 2014; 14:1196-1201. [PMID: 24490665 DOI: 10.1021/nl404054v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The magnetic properties of molecular structures can be tailored by chemical synthesis or bottom-up assembly at the atomic scale. We used scanning tunneling microscopy to study charge and spin transfer in individual complexes of transition metals with the charge acceptor, tetracyanoethylene (TCNE). The complexes were formed on a thin insulator, Cu2N on Cu(100), by manipulation of individual atoms and molecules. The Cu2N layer decouples the complexes from Cu electron density, enabling direct imaging of the TCNE molecular orbitals as well as spin-flip inelastic electron tunneling spectroscopy. Results were obtained at low temperature down to 1 K and in magnetic fields up to 7 T in order to resolve splitting of spin states in the complexes. We also performed spin-polarized density functional theory calculations to compare with the experimental data. Our results indicate that charge transfer to TCNE leads to a change in spin magnitude, Kondo resonance, and magnetic anisotropy for the metal atoms.
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Affiliation(s)
- T Choi
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
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Jung H, Park J, Oh IK, Choi T, Lee S, Hong J, Lee T, Kim SH, Kim H. Fabrication of transferable Al(2)O(3) nanosheet by atomic layer deposition for graphene FET. ACS Appl Mater Interfaces 2014; 6:2764-2769. [PMID: 24483324 DOI: 10.1021/am4052987] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Without introducing defects in the monolayer of carbon lattice, the deposition of high-κ dielectric material is a significant challenge because of the difficulty of high-quality oxide nucleation on graphene. Previous investigations of the deposition of high-κ dielectrics on graphene have often reported significant degradation of the electrical properties of graphene. In this study, we report a new way to integrate high-κ dielectrics with graphene by transferring a high-κ dielectric nanosheet onto graphene. Al2O3 film was deposited on a sacrificial layer using an atomic layer deposition process and the Al2O3 nanosheet was fabricated by removing the sacrificial layer. Top-gated graphene field-effect transistors were fabricated and characterized using the Al2O3 nanosheet as a gate dielectric. The top-gated graphene was demonstrated to have a field-effect mobility up to 2200 cm(2)/(V s). This method provides a new method for high-performance graphene devices with broad potential impacts reaching from high-frequency high-speed circuits to flexible electronics.
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Affiliation(s)
- Hanearl Jung
- Nanodevice Laboratory, School of Electrical and Electronic Engineering, and §Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University , Seodaemun-Gu, Seoul 120-749, Republic of Korea
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Song JG, Park J, Lee W, Choi T, Jung H, Lee CW, Hwang SH, Myoung JM, Jung JH, Kim SH, Lansalot-Matras C, Kim H. Layer-controlled, wafer-scale, and conformal synthesis of tungsten disulfide nanosheets using atomic layer deposition. ACS Nano 2013; 7:11333-40. [PMID: 24252136 DOI: 10.1021/nn405194e] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The synthesis of atomically thin transition-metal disulfides (MS2) with layer controllability and large-area uniformity is an essential requirement for their application in electronic and optical devices. In this work, we describe a process for the synthesis of WS2 nanosheets through the sulfurization of an atomic layer deposition (ALD) WO3 film with systematic layer controllability and wafer-level uniformity. The X-ray photoemission spectroscopy, Raman, and photoluminescence measurements exhibit that the ALD-based WS2 nanosheets have good stoichiometry, clear Raman shift, and bandgap dependence as a function of the number of layers. The electron mobility of the monolayer WS2 measured using a field-effect transistor (FET) with a high-k dielectric gate insulator is shown to be better than that of CVD-grown WS2, and the subthreshold swing is comparable to that of an exfoliated MoS2 FET device. Moreover, by utilizing the high conformality of the ALD process, we have developed a process for the fabrication of WS2 nanotubes.
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Affiliation(s)
- Jeong-Gyu Song
- School of Electrical and Electronics Engineering and §Department of Materials Science and Engineering, Yonsei University , Seoul 120-749, Korea
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39
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Müller T, Choi T, Hellmüller S, Ensslin K, Ihn T, Schön S. A circuit analysis of an in situ tunable radio-frequency quantum point contact. Rev Sci Instrum 2013; 84:083902. [PMID: 24007074 DOI: 10.1063/1.4817306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A detailed analysis of the tunability of a radio-frequency quantum point contact setup using a C - LCR circuit is presented. We calculate how the series capacitance influences resonance frequency and charge-detector resistance for which matching is achieved as well as the voltage and power delivered to the load. Furthermore, we compute the noise contributions in the system and compare our findings with measurements taken with an etched quantum point contact. While our considerations mostly focus on our specific choice of matching circuit, the discussion of the influence of source-to-load power transfer on the signal-to-noise ratio is valid generally.
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Affiliation(s)
- T Müller
- Solid State Physics Laboratory, ETH Zürich, 8093 Zürich, Switzerland
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40
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Kim H, Choi T, Cha MC, Chang JY. Preparation of a Porous polymer by a catalyst-free diels-alder reaction and its structural modification by post-reaction. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/pola.26763] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hyungwoo Kim
- Department of Materials Science and Engineering; College of Engineering, Seoul National University; Seoul 151-744 Korea
| | - Taejin Choi
- Department of Materials Science and Engineering; College of Engineering, Seoul National University; Seoul 151-744 Korea
| | - Min Chul Cha
- Department of Materials Science and Engineering; College of Engineering, Seoul National University; Seoul 151-744 Korea
| | - Ji Young Chang
- Department of Materials Science and Engineering; College of Engineering, Seoul National University; Seoul 151-744 Korea
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Lee S, Hong J, Koo JH, Lee H, Lee S, Choi T, Jung H, Koo B, Park J, Kim H, Kim YW, Lee T. Synthesis of few-layered graphene nanoballs with copper cores using solid carbon source. ACS Appl Mater Interfaces 2013; 5:2432-2437. [PMID: 23465382 DOI: 10.1021/am3024965] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report the fabrication of graphene-encapsulated nanoballs with copper nanoparticle (Cu NP) cores whose size range from 40 nm to 1 μm using a solid carbon source of poly(methyl methacrylate) (PMMA). The Cu NPs were prone to agglomerate during the annealing process at high temperatures of 800 to 900 °C when gas carbon source such as methane was used for the growth of graphene. On the contrary, the morphologies of the Cu NPs were unchanged during the growth of graphene at the same temperature range when PMMA coating was used. The solid source of PMMA was first converted to amorphous carbon layers through a pyrolysis process at the temperature regime of 400 °C, which prevented the Cu NPs from agglomeration, and they were converted to few-layered graphene (FLG) at the elevated temperatures. Raman and transmission electron microscope analyses confirmed the synthesis of FLG with thickness of approximately 3 nm directly on the surface of the Cu NPs. X-ray diffraction and X-ray photoelectron spectroscopy analyses, along with electrical resistance measurement according to temperature changes showed that the FLG-encapsulated Cu NPs were highly resistant to oxidation even after exposure to severe oxidation conditions.
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Affiliation(s)
- Sanggeun Lee
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 120-749, Republic of Korea
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Lee SH, Jang I, Chae N, Choi T, Kang H. Organic layer serves as a hotspot of microbial activity and abundance in Arctic tundra soils. Microb Ecol 2013; 65:405-414. [PMID: 22983497 DOI: 10.1007/s00248-012-0125-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 09/03/2012] [Indexed: 06/01/2023]
Abstract
Tundra ecosystem is of importance for its high accumulation of organic carbon and vulnerability to future climate change. Microorganisms play a key role in carbon dynamics of the tundra ecosystem by mineralizing organic carbon. We assessed both ecosystem process rates and community structure of Bacteria, Archaea, and Fungi in different soil layers (surface organic layer and subsurface mineral soil) in an Arctic soil ecosystem located at Spitsbergen, Svalbard during the summer of 2008 by using biochemical and molecular analyses, such as enzymatic assay, terminal restriction fragment length polymorphism (T-RFLP), quantitative polymerase chain reaction (qPCR), and pyrosequencing. Activity of hydrolytic enzymes showed difference according to soil type. For all three microbial communities, the average gene copy number did not significantly differ between soil types. However, archaeal diversities appeared to differ according to soil type, whereas bacterial and fungal diversity indices did not show any variation. Correlation analysis between biogeochemical and microbial parameters exhibited a discriminating pattern according to microbial or soil types. Analysis of the microbial community structure showed that bacterial and archaeal communities have different profiles with unique phylotypes in terms of soil types. Water content and hydrolytic enzymes were found to be related with the structure of bacterial and archaeal communities, whereas soil organic matter (SOM) and total organic carbon (TOC) were related with bacterial communities. The overall results of this study indicate that microbial enzyme activity were generally higher in the organic layer than in mineral soils and that bacterial and archaeal communities differed between the organic layer and mineral soils in the Arctic region. Compared to mineral soil, peat-covered organic layer may represent a hotspot for secondary productivity and nutrient cycling in this ecosystem.
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Ko M, Park T, Lee J, Kang B, Moon T, Choi J, Choi T, Lee M. 2.152 INTEROBSERVER RELIABILITY OF PULSE DIAGNOSIS USING TRADITIONAL KOREAN MEDICINE FOR STROKE PATIENTS. Parkinsonism Relat Disord 2012. [DOI: 10.1016/s1353-8020(11)70524-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Abstract
Although a number of methods using scanning probe lithography to pattern graphene have already been introduced, the fabrication of real devices still faces limitations. We report graphite patterning using scanning probe lithography with control of the gas environment. Patterning processes using scanning probe lithography of graphite or graphene are normally performed in air because water molecules forming the meniscus between the tip and the sample mediate the etching reaction. This water meniscus, however, may prevent uniform patterning due to its strong surface tension or large contact angle on surfaces. To investigate this side effect of water, our experiment was performed in a chamber where the gas environment was controlled with methyl alcohol, oxygen or isopropanol gases. We found that methyl alcohol facilitates graphite etching, and a line width as narrow as 3 nm was achieved as methyl alcohol also contains an oxygen atom which gives rise to the required oxidation. Due to its low surface tension and highly adsorptive behavior, methyl alcohol has advantages for a narrow line width and high speed etching conditions.
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Affiliation(s)
- Joonkyu Park
- Faculty of Nanotechnology and Advanced Material Engineering, and Graphene Research Institute, Sejong University, Seoul, 143-747, Korea
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Yi HT, Choi T, Choi SG, Oh YS, Cheong SW. Mechanism of the switchable photovoltaic effect in ferroelectric BiFeO3. Adv Mater 2011; 23:3403-3407. [PMID: 21681986 DOI: 10.1002/adma.201100805] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/19/2011] [Indexed: 05/27/2023]
Affiliation(s)
- H T Yi
- Rutgers Center for Emergent Materials, Dept. Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
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Roulleau P, Baer S, Choi T, Molitor F, Güttinger J, Müller T, Dröscher S, Ensslin K, Ihn T. Coherent electron–phonon coupling in tailored quantum systems. Nat Commun 2011; 2:239. [DOI: 10.1038/ncomms1241] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 02/16/2011] [Indexed: 11/09/2022] Open
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Abstract
The model based on Gaussian process (GP) prior and a kernel covariance function can be used to fit nonlinear data with multidimensional covariates. It has been used as a flexible nonparametric approach for curve fitting, classification, clustering, and other statistical problems, and has been widely applied to deal with complex nonlinear systems in many different areas particularly in machine learning. However, it is a challenging problem when the model is used for the large-scale data sets and high-dimensional data, for example, for the meat data discussed in this article that have 100 highly correlated covariates. For such data, it suffers from large variance of parameter estimation and high predictive errors, and numerically, it suffers from unstable computation. In this article, penalized likelihood framework will be applied to the model based on GPs. Different penalties will be investigated, and their ability in application given to suit the characteristics of GP models will be discussed. The asymptotic properties will also be discussed with the relevant proofs. Several applications to real biomechanical and bioinformatics data sets will be reported.
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Affiliation(s)
- G Yi
- School of Mathematics & Statistics, Newcastle University, United Kingdom Department of Statistics, Korea University, South Korea
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Wu W, Guest JR, Horibe Y, Park S, Choi T, Cheong SW, Bode M. Polarization-modulated rectification at ferroelectric surfaces. Phys Rev Lett 2010; 104:217601. [PMID: 20867135 DOI: 10.1103/physrevlett.104.217601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2010] [Indexed: 05/29/2023]
Abstract
By correlating room temperature conductive atomic force microscopy with low temperature electrostatic force microscopy images of the same sample region, we demonstrate that nanoscale electric conduction between a sharp tip and the surface of ferroelectric HoMnO3 is intrinsically modulated by the polarization of ferroelectric domains. Conductance spectra reveal that the electric conduction is described by polarization-induced Schottky-like rectification at low bias, but dominated by a space-charge limited conduction mechanism at high bias. Our observation demonstrates visualization of ferroelectric domain structure by electric conduction, which may be used for nondestructive readout of nanoscale ferroelectric memories and/or ferroelectric sensors.
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Affiliation(s)
- Weida Wu
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
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Choi T, Horibe Y, Yi HT, Choi YJ, Wu W, Cheong SW. Insulating interlocked ferroelectric and structural antiphase domain walls in multiferroic YMnO3. Nat Mater 2010; 9:253-258. [PMID: 20154694 DOI: 10.1038/nmat2632] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Accepted: 01/05/2010] [Indexed: 05/28/2023]
Abstract
Hexagonal YMnO(3) shows a unique improper ferroelectricity induced by structural trimerization. Extensive research on this system is primarily due to its candidacy for ferroelectric memory as well as the intriguing coexistence of ferroelectricity and magnetism. Despite this research, the true ferroelectric domain structure and its relationship with structural domains have never been revealed. Using transmission electron microscopy and conductive atomic force microscopy, we observed an intriguing conductive 'cloverleaf' pattern of six domains emerging from one point--all distinctly characterized by polarization orientation and structural antiphase relationships. In addition, we discovered that the ferroelectric domain walls and structural antiphase boundaries are mutually locked and this strong locking results in incomplete poling even when large electric fields are applied. Furthermore, the locked walls are found to be insulating, which seems consistent with the surprising result that the ferroelectric state is more conducting than the paraelectric state. These fascinating results reveal the rich physics of the hexagonal system with a truly semiconducting bandgap where structural trimerization, ferroelectricity, magnetism and charge conduction are intricately coupled.
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Affiliation(s)
- T Choi
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
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50
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Shen S, Yang X, Abeyta M, Choi T, Cedars M, Rosen M. Maximize day 3 frozen embryo's implantation potential using closed vitrification method. Fertil Steril 2009. [DOI: 10.1016/j.fertnstert.2009.07.1409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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