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Tran TT, Lee Y, Roy S, Tran TU, Kim Y, Taniguchi T, Watanabe K, Milošević MV, Lim SC, Chaves A, Jang JI, Kim J. Synergetic Enhancement of Quantum Yield and Exciton Lifetime of Monolayer WS 2 by Proximal Metal Plate and Negative Electric Bias. ACS Nano 2024; 18:220-228. [PMID: 38127273 DOI: 10.1021/acsnano.3c05667] [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] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The efficiency of light emission is a critical performance factor for monolayer transition metal dichalcogenides (1L-TMDs) for photonic applications. While various methods have been studied to compensate for lattice defects to improve the quantum yield (QY) of 1L-TMDs, exciton-exciton annihilation (EEA) is still a major nonradiative decay channel for excitons at high exciton densities. Here, we demonstrate that the combined use of a proximal Au plate and a negative electric gate bias (NEGB) for 1L-WS2 provides a dramatic enhancement of the exciton lifetime at high exciton densities with the corresponding QY enhanced by 30 times and the EEA rate constant decreased by 80 times. The suppression of EEA by NEGB is attributed to the reduction of the defect-assisted EEA process, which we also explain with our theoretical model. Our results provide a synergetic solution to cope with EEA to realize high-intensity 2D light emitters using TMDs.
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Affiliation(s)
- Trang Thu Tran
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Yongjun Lee
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Shrawan Roy
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Thi Uyen Tran
- Department of Smart Fab. Technology, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Youngbum Kim
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Milorad V Milošević
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
- Instituto de Física, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso 78060-900, Brazil
| | - Seong Chu Lim
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Department of Smart Fab. Technology, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Andrey Chaves
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
- Departamento de Física, Universidade Federal do Ceará, Campus do Pici, C.P. 6030, 60455-900 Fortaleza, Ceará, Brazil
| | - Joon I Jang
- Department of Physics, Sogang University, Seoul 04107, Republic of Korea
| | - Jeongyong Kim
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
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Nguyen DA, Jo Y, Tran TU, Jeong MS, Kim H, Im H. Electrically and Optically Controllable p-n Junction Memtransistor Based on an Al 2 O 3 Encapsulated 2D Te/ReS 2 van der Waals Heterostructure. Small Methods 2021; 5:e2101303. [PMID: 34928036 DOI: 10.1002/smtd.202101303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Indexed: 06/14/2023]
Abstract
The exploration of memtransistors as a combination of a memristor and a transistor has recently attracted intensive attention because it offers a promising candidate for next-generation multilevel nonvolatile memories and synaptic devices. However, the present state-of-the-art memtransistors, which are based on a single material, such as MoS2 or perovskite, exhibit a relatively low switching ratio, require extremely high electric fields to modulate bistable resistance states and do not perform multifunctional operations. Here, the realization of an electrically and optically controllable p-n junction memtransistor using an Al2 O3 encapsulated 2D Te/ReS2 van der Waals heterostructure is reported. The hybrid memtransistor shows a reversible bipolar resistance switching behavior between a low resistance state and a high resistance state with a high switching ratio up to 106 at a low operating voltage (<10 V), high cycling endurance, and long retention time. Moreover, multiple resistance states are achieved by applying different bias voltages, gate voltages, or light powers. In addition, logical operations, including the inverter and AND/OR gates, and synaptic activities are performed by controlling the optical and electrical inputs. The work offers a novel strategy for the reliable fabrication of p-n junction memtransistors for multifunctional devices and neuromorphic applications.
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Affiliation(s)
- Duc Anh Nguyen
- Division of Physics and Semiconductor Science, Dongguk University, Seoul, 04620, Republic of Korea
| | - Yongcheol Jo
- Division of Physics and Semiconductor Science, Dongguk University, Seoul, 04620, Republic of Korea
| | - Thi Uyen Tran
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Mun Seok Jeong
- Department of Physics, Department of Energy Engineering, Hanyang University, Seoul, 04763, Republic of Korea
| | - Hyungsang Kim
- Division of Physics and Semiconductor Science, Dongguk University, Seoul, 04620, Republic of Korea
| | - Hyunsik Im
- Division of Physics and Semiconductor Science, Dongguk University, Seoul, 04620, Republic of Korea
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Tran TU, Suzuki K, Okadome H, Ikezaki H, Homma S, Ohtsubo K. Detection of changes in taste of japonica and indica brown and milled rice (Oryza sativa L.) during storage using physicochemical analyses and a taste sensing system. J Agric Food Chem 2005; 53:1108-1118. [PMID: 15713027 DOI: 10.1021/jf049064+] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Changes in the taste of japonica, hybrid, and indica brown and milled rice, stored for 10 months at low (5 degrees C, 65-70% relative humidity) and room temperatures were observed by physicochemical analyses and a novel method using a taste sensing system. During storage, some properties increased or decreased while others were fairly constant. The main taste components of cooked rice such as sweetness (sucrose) and umami tastes (glutamic acid and aspartic acid) were reduced during storage, whereas glucose and fructose increased. The increase of fat acidity and consequent decrease of the pH value of the cooking solution may contribute to the off-taste of cooked stored rice. A taste sensing system with 10 lipid membrane sensors was also used to classify new and old rice samples using principal component analysis. Fresh and room temperature stored japonica and indica rice could be clearly distinguished; however, it was not possible to differentiate the samples stored at low temperature.
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Affiliation(s)
- Thi Uyen Tran
- Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyo, Tokyo 112-8610, Japan
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Doan HN, Taylor WRJ, Nguyen DT, Tran TU, Fryauff DJ, Susanti I, Gómez-Saladín E, Le DC, Baird JK. Short report: in vivo sensitivity of Plasmodium falciparum to halofantrine in southern central Vietnam. Am J Trop Med Hyg 2003; 69:553-4. [PMID: 14695095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
Drug-resistant Plasmodium falciparum is present in Vietnam. We assessed the in vivo sensitivity of P. falciparum to halofantrine in two villages in the southern part of central Vietnam. Halofantrine (8 mg/kg x 3 doses) was administered to 37 patients with either P. falciparum (n = 32) or mixed P. falciparum/P. vivax malaria (n = 5). End points were parasite sensitivity or resistance (RI/RII/RIII) determined by parasite clearance, persistence, or recurrence during 28 days of follow-up. By day 28, 31 (93.9%) of 33 (95% confidence interval = 79.8-99.2%) patients were sensitive. Two patients had recurrent P. falciparum parasitemia on days 14 and 21. Halofantrine effectively treated uncomplicated P. falciparum malaria in these Vietnamese patients.
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Affiliation(s)
- Hanh Nhan Doan
- U. S. Naval Medical Research Unit No. 2, Jakarta, Indonesia
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Lönnroth K, Tran TU, Thuong LM, Quy HT, Diwan V. Can I afford free treatment?: Perceived consequences of health care provider choices among people with tuberculosis in Ho Chi Minh City, Vietnam. Soc Sci Med 2001; 52:935-48. [PMID: 11234866 DOI: 10.1016/s0277-9536(00)00195-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Vietnam has a well-organised National TB Control Programme (NTP) with outstanding treatment results. Excellent prospect of cure is provided free of charge. Still, some people prefer to pay for their TB treatment themselves in private clinics. This is a potential threat to TB control since no notification of cases treated in the private sector occurs, and there is no control of the effectiveness of treatment provided in private clinics. Using a qualitative approach within a grounded theory framework, this study explores health-seeking behaviour among people with TB, applying a specific focus on reasons for choices of private versus pubic health care providers. The study identifies a number of characteristics of private TB care, which both seem attractive to patients and at the same time contrast sharply with the structure of the NTP strategy. These include flexible diagnostic procedures, no administrative procedures to establish eligibility for treatment, flexible choices of drug regimens, non-supervised treatment (no DOT), no tracing of defaulters in the household, no official registration of TB cases and thus less threat to personal integrity. A possibility to demand individualised service through the use of fee-for-service payments directly to physicians also seems attractive to many patients. A number of the components of the NTP strategy that have been put in place in order to secure optimal public health outcomes are lacking in the private sector. A dilemma for TB control is that this seems to be an important reason for why many people with TB opt for private providers where quality of care is virtually uncontrolled. The global threat of TB has led to calls for forceful measures to control TB. However, based on the findings in this study it is argued that the use of rigid approaches to TB control that do not encompass a strong component of responsiveness towards the needs of individuals may be counterproductive for public health.
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Affiliation(s)
- K Lönnroth
- Deportment of Social Medicine, Göteborg University, Vasa Hospital, Sweden.
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Taylor WR, Doan HN, Nguyen DT, Tran TU, Fryauff DJ, Gómez-Saladín E, Kain KC, Le DC, Baird JK. Assessing drug sensitivity of Plasmodium vivax to halofantrine or choroquine in southern, central Vietnam using an extended 28-day in vivo test and polymerase chain reaction genotyping. Am J Trop Med Hyg 2000; 62:693-7. [PMID: 11304056 DOI: 10.4269/ajtmh.2000.62.693] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Chloroquine-resistant Plasmodium vivax malaria is emerging in Oceania, Asia, and Latin America. We assessed the drug sensitivity of P. vivax to chloroquine or halofantrine in two villages in southern, central Vietnam. This area has chloroquine-resistant Plasmodium falciparum but no documented chloroquine-resistant P. vivax. Standard dose chloroquine (25 mg/kg, over 48 hours) or halofantrine (8 mg/kg, 3 doses) was administered to 29 and 25 patients, respectively. End points were parasite sensitivity or resistance determined at 28 days. Of the evaluable patients, 23/23 100% (95% confidence interval [CI] 85.1-100) chloroquine and 21/24 (87.5%) (95% CI 67.6-97.3) halofantrine-treated patients were sensitive. Three halofantrine recipients had initial clearance but subsequent recurrence of their parasitemias. Genotyping of the recurrent and Day 0 parasitemias differed, suggesting either new infections or relapses of liver hypnozoites from antecedent infections. Among these Vietnamese patients, P. vivax was sensitive to chloroquine and halofantrine. Genotyping was useful for differentiating the recurrent vivax parasitemias.
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Zarrabian S, Buts JP, Fromont G, Tran TU, Macry J, Mendy F, Roger L, Cèzard JP. Effects of alimentary intact proteins and their oligopeptide hydrolysate on growth, nitrogen retention, and small bowel adaptation in inflammatory turpentine rat. Nutrition 1999; 15:474-80. [PMID: 10378203 DOI: 10.1016/s0899-9007(99)00054-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effects of dietary proteins given as whole proteins (WP) or as a peptide hydrolysate (PH) on growth, nitrogen retention, and small bowel adaptation were assessed using two groups of male Wistar rats. Measurements were made 18, 42, and 66 h after acute inflammation induced by subcutaneous injections of 0.125 mL turpentine and in two control groups (n = 12). The two diets had the same caloric, nitrogen, vitamin, and mineral content. The WP diet resulted in better weight gain, nitrogen retention, and small intestinal adaptation by control rats than did the PH diet. Loss of body weight after 18 h of acute inflammation was significantly lower and nitrogen retention significantly higher in animals on the WP diet than in those on the PH diet. Small intestine morphology was maintained with the WP diet, whereas villus height was significantly lower after 66 h, and there were fewer mitoses per crypt in the rats on the PH diet. Glucoamylase activity at all times, and N-aminopeptidase activity at 18 h, were significantly higher in rats on the WP diet. The putrescine (at 42 h) and spermidine (at 18 h) concentrations in the mucosa were higher in the rats on the WP diet. These data suggest that synthetic diets should be tested for their nutritional value during acute inflammation before they are used in human nutrition.
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Affiliation(s)
- S Zarrabian
- INSERM U458, Robert Debrè Hospital, Paris, France
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