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Akin S, Kim S, Song CK, Nam SY, Jun MBG. Fully Additively Manufactured Counter Electrodes for Dye-Sensitized Solar Cells. Micromachines (Basel) 2024; 15:464. [PMID: 38675275 PMCID: PMC11052471 DOI: 10.3390/mi15040464] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/28/2024]
Abstract
In dye-sensitized solar cells (DSSCs), the counter electrode (CE) plays a crucial role as an electron transfer agent and regenerator of the redox couple. Unlike conventional CEs that are generally made of glass-based substrates (e.g., FTO/glass), polymer substrates appear to be emerging candidates, owing to their intrinsic properties of lightweight, high durability, and low cost. Despite great promise, current manufacturing methods of CEs on polymeric substrates suffer from serious limitations, including low conductivity, scalability, process complexity, and the need for dedicated vacuum equipment. In the present study, we employ and evaluate a fully additive manufacturing route that can enable the fabrication of CEs for DSSCs in a high-throughput and eco-friendly manner with improved performance. The proposed approach sequentially comprises: (1) material extrusion 3-D printing of polymer substrate; (2) conductive surface metallization through cold spray particle deposition; and (3) over-coating of a thin-layer catalyzer with a graphite pencil. The fabricated electrodes are characterized in terms of microstructure, electrical conductivity, and photo-conversion efficiency. Owing to its promising electrical conductivity (8.5 × 104 S·m-1) and micro-rough surface structure (Ra ≈ 6.32 µm), the DSSCs with the additively manufactured CEs led to ≈2.5-times-higher photo-conversion efficiency than that of traditional CEs made of FTO/glass. The results of the study suggest that the proposed additive manufacturing approach can advance the field of DSSCs by addressing the limitations of conventional CE manufacturing platforms.
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Affiliation(s)
- Semih Akin
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Sungdo Kim
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA;
- Department of Mechanical Engineering, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Chul Ki Song
- School of Mechanical Engineering, ERI, Gyeongsang National University, Jinju 52828, Republic of Korea;
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea;
| | - Martin Byung-Guk Jun
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA;
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2
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Jang HS, Jeong HN, Eom SM, Han SM, Kim SH, Kwon HW, Im KS, Vijayakumar V, Nam SY. Robust anion exchange membranes based on ionic liquid grafted chitosan/polyvinyl alcohol/quaternary ammonium functionalized silica for polymer electrolyte membrane fuel cells. Int J Biol Macromol 2024; 262:129979. [PMID: 38331065 DOI: 10.1016/j.ijbiomac.2024.129979] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/29/2024] [Accepted: 02/01/2024] [Indexed: 02/10/2024]
Abstract
In this study, 1-bromohexyl-1methylpiperidinium bromide (Br-6-MPRD) ionic liquid grafted quaternized chitosan (QCS) and polyvinyl alcohol (PVA) blends were composited with glycidyl trimethyl ammonium chloride (GTMAC) quaternized silica (QSiO2) at different dosages. Glutaraldehyde (GA) crosslinked the membranes and then processed into hydroxide form with an aqueous potassium hydroxide solution. The resultant IL-QCS/PVA/QSiO2 membranes exhibit significantly improved ionic conductivity, moderate water absorption and swelling ratio compared with the pristine IL-QCS/PVA anion exchange membrane (AEM). Among them, the hydroxide ion conductivity and power density of IL-QCS/PVA/QSiO2-7 membrane can reach up to 78 mS cm-1 at 80 °C and 115 mW cm-2 at 60 °C respectively. In addition, IL-QCS/PVA/QSiO2 membranes have excellent thermal, mechanical, and chemical stabilities, which can meet the application requirements of AEM for fuel cells.
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Affiliation(s)
- Hak Su Jang
- Department of Polymer Science and Engineering, School of Materials Science and Engineering, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Ha Neul Jeong
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Sang Min Eom
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Seong Min Han
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Seong Heon Kim
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Hyun Woong Kwon
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Kwang Seop Im
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Vijayalekshmi Vijayakumar
- Research Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea.
| | - Sang Yong Nam
- Department of Polymer Science and Engineering, School of Materials Science and Engineering, Gyeongsang National University, Jinju 52828, Republic of Korea; Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea; Research Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea.
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3
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Nah G, Jeong JR, Lee JH, Soh SY, Nam SY. The complete chloroplast genome of Philodendron hederaceum (Jacq.) Schott 1829 (Alismatales: Araceae). Mitochondrial DNA B Resour 2024; 9:262-266. [PMID: 38348093 PMCID: PMC10860476 DOI: 10.1080/23802359.2024.2311748] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 01/24/2024] [Indexed: 02/15/2024] Open
Abstract
Philodendron hederaceum (Jacq.) Schott 1829, a species of the Araceae family, is a foliage plant of ornamental value. The complete chloroplast genome sequence of Philodendron hederaceum was obtained by the de novo assembly of NovaSeq 6000 (Illumina Co., San Diego, CA) paired-end short reads and Oxford Nanopore long reads. The complete chloroplast genome of P. hederaceum was 168,609 bp in length, with a large single-copy (LSC) region of 94,393 bp, a small single-copy (SSC) region of 25,774 bp, and a pair of identical inverted repeat regions (IRs) of 24,221 bp. The genome contained a total of 129 genes, including 85 protein-coding genes, 36 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. The phylogenetic analysis of P. hederaceum with 19 related species and two outgroup species revealed the closest taxonomical relationship with Philodendron lanceolatum in the Araceae family.
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Affiliation(s)
- Gyoungju Nah
- Genome Analysis Center at National Instrumentation Center for Environmental Management, Seoul National University, Seoul, South Korea
| | - Ji Ran Jeong
- Genome Analysis Center at National Instrumentation Center for Environmental Management, Seoul National University, Seoul, South Korea
| | - Jae Hwan Lee
- Department of Environmental Horticulture, Sahmyook University, Seoul, South Korea
- Natural Science Research Institute, Sahmyook University, Seoul, South Korea
| | - Soon Yil Soh
- Natural Science Research Institute, Sahmyook University, Seoul, South Korea
| | - Sang Yong Nam
- Department of Environmental Horticulture, Sahmyook University, Seoul, South Korea
- Natural Science Research Institute, Sahmyook University, Seoul, South Korea
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Park JR, Kim EG, Jang YH, Nam SY, Kim KM. Investigation of the Relationship between Genetic and Breeding Characteristics of WBPH Behavior according to Resistant Materials in Rice. Plants (Basel) 2023; 12:2821. [PMID: 37570975 PMCID: PMC10421494 DOI: 10.3390/plants12152821] [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] [Received: 07/14/2023] [Revised: 07/29/2023] [Accepted: 07/29/2023] [Indexed: 08/13/2023]
Abstract
Rice accounts for most of the calories consumed by the world's population. However, the whitebacked planthopper (WBPH), Sogatella furcifera (Horvath), is an insect that can cause rice yield loss. WBPH sucks the stems of rice and negatively affects yield and grain quality. Therefore, numerous insecticides have been developed to control WBPH in rice fields. However, chemical pesticides cause serious problems such as environmental pollution and ecosystem disturbance. Here, we research the possibility of using previously reported rice extracts obtained using methanol, Chrysoeriol 7(C7) and Cochlioquinone-9 (cq-9), as potential insect repellents. WBPH was caged with C7 or cq-9 and monitored, and the WBPH behavior was recorded. The number of WBPHs approaching the periphery of the C7 and cq-9 was very low. In cages containing the C7 and cq-9, only 13 and 7 WBPHs out of 100, respectively, walked around the material. In addition, foliar spraying with C7 and cq-9 did not negatively affect the plant height. The expression level of genes related to resistance was maintained at a high level in the resistant lines when treated with WBPHs alone, but was at a similar level to those of the controls when treated with C7 or cq-9. Interfering with WBPH access did not adversely affect the plant phenotype. Recently, people's interest in the environment has increased, and the use of plant-derived materials is also increasing. There is a new trend towards using plant extracts as an environmentally friendly means of managing resistance to WBPH during the rice cultivation period, while also avoiding environmental pollution.
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Affiliation(s)
- Jae-Ryoung Park
- Crop Breeding Division, National Institute of Crop Science, Rural Development Administration, Wanju 55365, Republic of Korea;
- Coastal Agriculture Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea; (E.-G.K.); (Y.-H.J.)
| | - Eun-Gyeong Kim
- Coastal Agriculture Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea; (E.-G.K.); (Y.-H.J.)
| | - Yoon-Hee Jang
- Coastal Agriculture Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea; (E.-G.K.); (Y.-H.J.)
| | - Sang Yong Nam
- Department of Environmental Horticulture, Graduate School of Sahmyook University, Seoul 01795, Republic of Korea
- Natural Science Research Institute, Sahmyook University, Seoul 01795, Republic of Korea
| | - Kyung-Min Kim
- Coastal Agriculture Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea; (E.-G.K.); (Y.-H.J.)
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
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Ye H, Ryu KY, Kwon HJ, Lee H, Wang R, Hong J, Choi HH, Nam SY, Lee J, Kong H, Kim SH. Amorphous Fluorinated Acrylate Polymer Dielectrics for Flexible Transistors and Logic Gates with High Operational Stability. ACS Appl Mater Interfaces 2023. [PMID: 37376772 DOI: 10.1021/acsami.3c02010] [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: 06/29/2023]
Abstract
Fluorinated amorphous polymeric gate-insulating materials for organic thin-film transistors (OTFTs) not only form hydrophobic surfaces but also significantly reduce traps at the interface between the organic semiconductor and gate insulator. Therefore, these polymeric materials can enhance the OTFT's operation stability. In this study, we synthesized a new polymeric insulating material series composed of acrylate and fluorinated functional groups (with different ratios) named MBHCa-F and used them as gate insulators for OTFTs and in other applications. The insulating features of the MBHCa-F polymers, including surface energy, surface atomic content properties, dielectric constant, and leakage current, were clearly analyzed with respect to the content of the fluorinated functional groups. At higher fluorine-based functional group content, the polymeric series exhibited higher fluorine-based contents at the surface and superior electrical properties, such as field-effect mobility and driving stability, at OTFTs. Therefore, we believe that this study provides a substantial method for synthesizing polymeric insulating materials to enhance the operational stability and electrical performance of OTFTs.
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Affiliation(s)
- Heqing Ye
- Department of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea
| | - Ka Yeon Ryu
- Research Institute for Green Energy Convergence Techonology, Gyeongsang National University, Jinju 52828, Republic of Korea
- Department of Chemistry and Research Institute of Nature Science, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Hyeok-Jin Kwon
- Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Hyunji Lee
- Research Center for Advanced Specialty Chemicals, Korea Research Institute of Chemical Technology, Ulsan 44412 Republic of Korea
| | - Rixuan Wang
- Department of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea
| | - Jisu Hong
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Hyun Ho Choi
- Research Institute for Green Energy Convergence Techonology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Sang Yong Nam
- Research Institute for Green Energy Convergence Techonology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Jihoon Lee
- Department of Polymer Science and Engineering, Korea National University of Transportation, Chungju 27469, Republic of Korea
| | - Hoyoul Kong
- Department of Chemistry and Research Institute of Nature Science, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Se Hyun Kim
- School of Chemical Engineering, Konkuk University, Seoul 05029, Korea
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Kim J, Gupta NS, Bezek LB, Linn J, Bejagam KK, Banerjee S, Dumont JH, Nam SY, Kang HW, Park CH, Pilania G, Iverson CN, Marrone BL, Lee KS. Biodegradation Studies of Polyhydroxybutyrate and Polyhydroxybutyrate- co-Polyhydroxyvalerate Films in Soil. Int J Mol Sci 2023; 24:ijms24087638. [PMID: 37108799 PMCID: PMC10146786 DOI: 10.3390/ijms24087638] [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: 03/24/2023] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
Due to increased environmental pressures, significant research has focused on finding suitable biodegradable plastics to replace ubiquitous petrochemical-derived polymers. Polyhydroxyalkanoates (PHAs) are a class of polymers that can be synthesized by microorganisms and are biodegradable, making them suitable candidates. The present study looks at the degradation properties of two PHA polymers: polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-polyhydroxyvalerate (PHBV; 8 wt.% valerate), in two different soil conditions: soil fully saturated with water (100% relative humidity, RH) and soil with 40% RH. The degradation was evaluated by observing the changes in appearance, chemical signatures, mechanical properties, and molecular weight of samples. Both PHB and PHBV were degraded completely after two weeks in 100% RH soil conditions and showed significant reductions in mechanical properties after just three days. The samples in 40% RH soil, however, showed minimal changes in mechanical properties, melting temperatures/crystallinity, and molecular weight over six weeks. By observing the degradation behavior for different soil conditions, these results can pave the way for identifying situations where the current use of plastics can be replaced with biodegradable alternatives.
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Affiliation(s)
- Jihyeon Kim
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Nevin S Gupta
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Lindsey B Bezek
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Jacqueline Linn
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Karteek K Bejagam
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Shounak Banerjee
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Joseph H Dumont
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Hyun Woo Kang
- Department of Energy Engineering, Future Convergence Technology Research Institute, Gyeongsang National University, Jinju 52725, Republic of Korea
| | - Chi Hoon Park
- Department of Energy Engineering, Future Convergence Technology Research Institute, Gyeongsang National University, Jinju 52725, Republic of Korea
| | - Ghanshyam Pilania
- Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- General Electric Global Research Center, Niskayuna, NY 12309, USA
| | - Carl N Iverson
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Babetta L Marrone
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Kwan-Soo Lee
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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Kang H, Cheon M, Lee CH, Kim TH, Hong YT, Nam SY, Park CH. Mesoscale Simulation Based on the Dynamic Mean-Field Density Functional Method on Block-Copolymeric Ionomers for Polymer Electrolyte Membranes. Membranes (Basel) 2023; 13:258. [PMID: 36984645 PMCID: PMC10054894 DOI: 10.3390/membranes13030258] [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: 12/30/2022] [Revised: 02/16/2023] [Accepted: 02/18/2023] [Indexed: 06/18/2023]
Abstract
Block copolymers generally have peculiar morphological characteristics, such as strong phase separation. They have been actively applied to polymer electrolyte membranes for proton exchange membrane fuel cells (PEMFCs) to obtain well-defined hydrophilic regions and water channels as a proton pathway. Although molecular simulation tools are advantageous to investigate the mechanism of water channel formation based on the chemical structure and property relationships, classical molecular dynamics simulation has limitations regarding the model size and time scale, and these issues need to be addressed. In this study, we investigated the morphology of sulfonated block copolymers synthesized for PEM applications using a mesoscale simulation based on the dynamic mean-field density functional method, widely applied to investigate macroscopic systems such as polymer blends, micelles, and multi-block/grafting copolymers. Despite the similar solubility parameters of the monomers in our block-copolymer models, very different morphologies in our 3D mesoscale models were obtained. The model with sulfonated monomers, in which the number of sulfonic acid groups is twice that of the other model, showed better phase separation and water channel formation, despite the short length of its hydrophilic block. In conclusion, this unexpected behavior indicates that the role of water molecules is important in making PEM mesoscale models well-equilibrated in the mesoscale simulation, which results in the strong phase separation between hydrophilic and hydrophobic regions and the ensuing well-defined water channel. PEM synthesis supports the conclusion that using the sulfonated monomers with a high sulfonation degree (32.5 mS/cm) will be more effective than using the long hydrophilic block with a low sulfonation degree (25.2 mS/cm).
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Affiliation(s)
- Hoseong Kang
- Department of Energy Engineering, Future Convergence Technology Research Institute, Gyeongsang National University (GNU), Jinju 52725, Republic of Korea
| | - Muyeong Cheon
- Department of Energy Engineering, Future Convergence Technology Research Institute, Gyeongsang National University (GNU), Jinju 52725, Republic of Korea
| | - Chang Hyun Lee
- Energy Engineering Department, College of Engineering, Dankook University, Cheonan 31116, Republic of Korea
| | - Tae-Ho Kim
- Center for Membranes, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea
| | - Young Taik Hong
- Center for Membranes, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University (GNU), Jinju 52725, Republic of Korea
| | - Chi Hoon Park
- Department of Energy Engineering, Future Convergence Technology Research Institute, Gyeongsang National University (GNU), Jinju 52725, Republic of Korea
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Jung JH, Vijayakumar V, Haridas AK, Ahn JH, Nam SY. Effect of Cross-Linking and Surface Treatment on the Functional Properties of Electrospun Polybenzimidazole Separators for Lithium Metal Batteries. ACS Omega 2022; 7:47784-47795. [PMID: 36591163 PMCID: PMC9798493 DOI: 10.1021/acsomega.2c05472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
In this work, electrospun PBI separators with a highly porous structure and nanofiber diameter of about 90-150 nm are prepared using a multi-nozzle under controlled conditions for lithium metal batteries. Cross-linking with α, α-dibromo-p-xylene and surface treatment using 4-(chloromethyl) benzoic acid successfully improve the electrochemical as well as mechanical properties of the separators. The resulting separator is endowed with high thermal stability and excellent wettability (1080 to 1150%) with commercial liquid electrolyte than PE and PP (Celgard 2400) separators. Besides, attractive cycling stability and rate capability in LiFePO4/Li cells are attained with the modified separators. Prominently, CROSSLINK PBI exhibits a stable Coulombic efficiency of more than 99% over 100 charge-discharge cycles at 0.5 C, which is superior to the value of cells using commercial PE and PP (Celgard 2400) separators. The half cells assembled using the CROSSLINK PBI separator can deliver a discharge capacity of 150.3 mAh g-1 at 0.2 C after 50 cycles corresponding to 88.4% of the theoretical value of LiFePO4 (170 mAh g-1). This work offers a worthwhile method to produce thermally stable separators with noteworthy electrochemical performances which opens new possibilities to improve the safe operation of batteries.
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Affiliation(s)
- Ji Hye Jung
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju52828, Republic
of Korea
| | - Vijayalekshmi Vijayakumar
- Research
Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju52828, Republic
of Korea
| | - Anupriya K. Haridas
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju52828, Republic
of Korea
| | - Jou-Hyeon Ahn
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju52828, Republic
of Korea
- Department
of Chemical Engineering, Gyeongsang National
University, Jinju52828, Republic of Korea
| | - Sang Yong Nam
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju52828, Republic
of Korea
- Research
Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju52828, Republic
of Korea
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Vijayakumar V, Nam SY. A Review of Recent Chitosan Anion Exchange Membranes for Polymer Electrolyte Membrane Fuel Cells. Membranes (Basel) 2022; 12:1265. [PMID: 36557172 PMCID: PMC9783247 DOI: 10.3390/membranes12121265] [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: 11/09/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Considering the critical energy challenges and the generation of zero-emission anion exchange membrane (AEM) sources, chitosan-based anion exchange membranes have garnered considerable interest in fuel cell applications owing to their various advantages, including their eco-friendly nature, flexibility for structural modification, and improved mechanical, thermal, and chemical stability. The present mini-review highlights the advancements of chitosan-based biodegradable anion exchange membranes for fuel cell applications published between 2015 and 2022. Key points from the rigorous literature evaluation are: grafting with various counterions in addition to crosslinking contributed good conductivity and chemical as well as mechanical stability to the membranes; use of the interpenetrating network as well as layered structures, blending, and modified nanomaterials facilitated a significant reduction in membrane swelling and long-term alkaline stability. The study gives insightful guidance to the industry about replacing Nafion with a low-cost, environmentally friendly membrane source. It is suggested that more attention be given to exploring chitosan-based anion exchange membranes in consideration of effective strategies that focus on durability, as well as optimization of the operational conditions of fuel cells for large-scale applications.
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Affiliation(s)
- Vijayalekshmi Vijayakumar
- Research Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Sang Yong Nam
- Research Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
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Nah G, Jeong JR, Lee JH, Soh SY, Nam SY. The complete chloroplast genome of Echeveria lilacina Kimnach & Moran 1980 (Saxifragales: Crassulaceae). Mitochondrial DNA B Resour 2022; 7:889-891. [PMID: 35692710 PMCID: PMC9176349 DOI: 10.1080/23802359.2022.2077668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Echeveria lilacina Kimnach & Moran 1980 is a succulent plant having ornamental and ecological importance. In this study, the first complete chloroplast genome of Echeveria lilacina, a species belonging to the Crassulaceae family, was characterized from the de novo assembly of Illumina NovaSeq 6000 paired-end sequencing data. The chloroplast genome of E. lilacina is 150,080 bp in length, which includes a large single-copy (LSC) region of 81,741 bp, a small single-copy (SSC) region of 16,747 bp, and a pair of identical inverted repeat regions (IRs) of 25,796 bp each. The genome annotation revealed a total of 138 genes, including 87 protein-coding genes, 41 transfer RNA (tRNA) genes, and 10 ribosomal RNA (rRNA) genes. The phylogenetic analysis with 15 complete chloroplast genome sequences including outgroup showed that E. lilacina formed the closest taxonomical relationship with Graptopetalum amethystinum in the Crassulaceae family.
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Affiliation(s)
- Gyoungju Nah
- Genome Analysis Center at National Instrumentation Center for Environmental Management, Seoul National University, Seoul, Korea
| | - Ji Ran Jeong
- Genome Analysis Center at National Instrumentation Center for Environmental Management, Seoul National University, Seoul, Korea
| | - Jae Hwan Lee
- Department of Environmental Horticulture, Sahmyook University, Seoul, Korea
- Natural Science Research Institute, Sahmyook University, Seoul, Korea
| | - Soon Yil Soh
- Natural Science Research Institute, Sahmyook University, Seoul, Korea
| | - Sang Yong Nam
- Department of Environmental Horticulture, Sahmyook University, Seoul, Korea
- Natural Science Research Institute, Sahmyook University, Seoul, Korea
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Al Munsur AZ, Lee J, Chae JE, Kim HJ, Park CH, Nam SY, Kim TH. Hexyl quaternary ammonium- and fluorobenzoyl-grafted SEBS as hydrophilic–hydrophobic comb-type anion exchange membranes. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2021.120029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Kim DH, Lee SJ, Theerthagiri J, Choi M, Jung J, Yu Y, Im KS, Jung HJ, Nam SY, Choi MY. In-situ thermal phase transition and structural investigation of ferroelectric tetragonal barium titanate nanopowders with pseudo-cubic phase. Chemosphere 2021; 283:131218. [PMID: 34147976 DOI: 10.1016/j.chemosphere.2021.131218] [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: 05/17/2021] [Revised: 06/04/2021] [Accepted: 06/10/2021] [Indexed: 06/12/2023]
Abstract
Optimization and miniaturization of existing electronic devices require the development of advanced nanostructured materials with high phase and structural purity. Over the past decade, barium titanate (BaTiO3) has attracted considerable attention due to its outstanding ferroelectric and dielectric properties. The present study involved the investigation of the phase transition and structural stability of tetragonal BaTiO3 nanopowders with pseudo-cubic phase using an in-situ high resolution and high temperature X-ray diffraction method. Under ambient conditions, the coexistence the tetragonal and cubic phases with weight fractions of 75.7% and 24.3%, respectively, was determined in BaTiO3. In the temperature range of 25 °C-300 °C, phase boundaries of BaTiO3 (180 nm in size) exhibiting several phases were detected. The phase transformation behavior, relative crystal phase content, lattice parameters, crystallite size, and tetragonality of the BaTiO3 nanopowders were established by the Rietveld refinement method at the onset temperature from 25 °C to 300 °C. Up to 150 °C, the nanopowders exhibited a complete transition of the cubic phase. Additionally, a complete tetragonal to cubic transformation was accomplished by a decrease of tetragonality at 125 °C and an increase in the crystallite size at 300 °C.
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Affiliation(s)
- Dong Hyun Kim
- Electronic Convergence Division, Korea Institute of Ceramic Engineering & Technology, 101, Soho-Ro, Jinju, 52851, Republic of Korea
| | - Seung Jun Lee
- Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Jayaraman Theerthagiri
- Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Moonhee Choi
- Electronic Convergence Division, Korea Institute of Ceramic Engineering & Technology, 101, Soho-Ro, Jinju, 52851, Republic of Korea
| | - Jongsuk Jung
- MLCC Development Group, R&D Center, Samsung Electro-Mechanics, 150, Maeyeong-Ro, Suwon, 16674, Republic of Korea
| | - Yiseul Yu
- Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Kwang Seop Im
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Hyeon Jin Jung
- Electronic Convergence Division, Korea Institute of Ceramic Engineering & Technology, 101, Soho-Ro, Jinju, 52851, Republic of Korea.
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju, 52828, Republic of Korea.
| | - Myong Yong Choi
- Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea.
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Kim M, Ko H, Nam SY, Kim K. Study on Control of Polymeric Architecture of Sulfonated Hydrocarbon-Based Polymers for High-Performance Polymer Electrolyte Membranes in Fuel Cell Applications. Polymers (Basel) 2021; 13:3520. [PMID: 34685282 PMCID: PMC8539910 DOI: 10.3390/polym13203520] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 09/14/2021] [Revised: 10/06/2021] [Accepted: 10/09/2021] [Indexed: 01/23/2023] Open
Abstract
Polymer electrolyte membrane fuel cell (PEMFC) is an eco-friendly energy conversion device that can convert chemical energy into electrical energy without emission of harmful oxidants such as nitrogen oxides (NOx) and/or sulfur oxides (SOx) during operation. Nafion®, a representative perfluorinated sulfonic acid (PFSA) ionomer-based membrane, is generally incorporated in fuel cell systems as a polymer electrolyte membrane (PEM). Since the PFSA ionomers are composed of flexible hydrophobic main backbones and hydrophilic side chains with proton-conducting groups, the resulting membranes are found to have high proton conductivity due to the distinct phase-separated structure between hydrophilic and hydrophobic domains. However, PFSA ionomer-based membranes have some drawbacks, including high cost, low glass transition temperatures and emission of environmental pollutants (e.g., HF) during degradation. Hydrocarbon-based PEMs composed of aromatic backbones with proton-conducting hydrophilic groups have been actively studied as substitutes. However, the main problem with the hydrocarbon-based PEMs is the relatively low proton-conducting behavior compared to the PFSA ionomer-based membranes due to the difficulties associated with the formation of well-defined phase-separated structures between the hydrophilic and hydrophobic domains. This study focused on the structural engineering of sulfonated hydrocarbon polymers to develop hydrocarbon-based PEMs that exhibit outstanding proton conductivity for practical fuel cell applications.
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Affiliation(s)
| | | | | | - Kihyun Kim
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Korea; (M.K.); (H.K.); (S.Y.N.)
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Vijayakumar V, Kim JH, Nam SY. Piperidinium functionalized poly(2,6 dimethyl 1,4 phenylene oxide) based polyionic liquid/ionic liquid (PIL/IL) composites for CO2 separation. J IND ENG CHEM 2021. [DOI: 10.1016/j.jiec.2021.04.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Vijayakumar V, Son TY, Im KS, Chae JE, Kim HJ, Kim TH, Nam SY. Anion Exchange Composite Membranes Composed of Quaternary Ammonium-Functionalized Poly(2,6-dimethyl-1,4-phenylene oxide) and Silica for Fuel Cell Application. ACS Omega 2021; 6:10168-10179. [PMID: 34056171 PMCID: PMC8153668 DOI: 10.1021/acsomega.1c00247] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
Anion exchange membranes (AEMs) with good alkaline stability and ion conductivity are fabricated by incorporating quaternary ammonium-modified silica into quaternary ammonium-functionalized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO). Quaternary ammonium with a long alkyl chain is chemically grafted to the silica in situ during synthesis. Glycidyltrimethylammoniumchloride functionalization on silica (QSiO2) is characterized by Fourier transform infrared and transmission electron microscopic techniques. The QPPO/QSiO2 membrane having an ion exchange capacity of 3.21 meq·g-1 exhibits the maximum hydration number (λ = 11.15) and highest hydroxide ion conductivity of 45.08 × 10-2 S cm-1 at 80 °C. In addition to the high ion conductivity, AEMs also exhibit good alkaline stability, and the conductivity retention of the QPPO/QSiO2-3 membrane after 1200 h of exposure in 1 M potassium hydroxide at room temperature is about 91% ascribed to the steric hindrance offered by the grafted long glycidyl trimethylammonium chain in QSiO2. The application of the QPPO/QSiO2-3 membrane to an alkaline fuel cell can yield a peak power density of 142 mW cm-2 at a current density of 323 mA cm-2 and 0.44 V, which is higher than those of commercially available FAA-3-50 Fumatech AEM (OCV: 0.91 V; maximum power density: 114 mW cm-2 at current density: 266 mA cm-2 and 0.43 V). These membranes provide valuable insights on future directions for advanced AEM development for fuel cells.
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Affiliation(s)
- Vijayalekshmi Vijayakumar
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic
of Korea
| | - Tae Yang Son
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic
of Korea
| | - Kwang Seop Im
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic
of Korea
| | - Ji Eon Chae
- Fuel
Cell Research Center, Korea Institute of
Science and Technology, Seoul 02792, Republic of Korea
| | - Hyoung Juhn Kim
- Fuel
Cell Research Center, Korea Institute of
Science and Technology, Seoul 02792, Republic of Korea
| | - Tae Hyun Kim
- Organic
Material Synthesis Laboratory, Department of Chemistry, Incheon National University, Incheon 22012, Republic of Korea
| | - Sang Yong Nam
- Department
of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju 52828, Republic
of Korea
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16
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Ko TH, Yun JS, Son TY, Nam SY. Preparation and Characterization of Pore Filled Hybrid Composite Membrane Composed of Cation Exchange Materials and Polyethylene Support. J Nanosci Nanotechnol 2020; 20:6802-6806. [PMID: 32604517 DOI: 10.1166/jnn.2020.18789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This study investigated ion exchange membranes for application to seawater desalination processes. This can provide better energy efficiency than the conventional reverse osmosis process. In this experiment, the problem of decreasing ion exchange performance when the ion exchange composite membrane was prepared could be improved through nanoparticles. The nanoparticle added ion exchange hybrid membrane showed ion exchange capacity similar to that of the conventional pristine film. In addition, the polymer having a high ion exchange capacity has poor mechanical strength, but has excellent mechanical strength of 30 MPa or more by the introduction of a polyethylene support.
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Affiliation(s)
- Tae Ho Ko
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Jun Seong Yun
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Tae Yang Son
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
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Son TY, Yun JS, Kim K, Nam SY. Electrochemical Performance Evaluation of Bipolar Membrane Using Poly(phenylene oxide) for Water Treatment System. J Nanosci Nanotechnol 2020; 20:6797-6801. [PMID: 32604516 DOI: 10.1166/jnn.2020.18788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This study describes the use of poly(phenylene oxide) polymer-based ion-exchange polymers, polystyrene-based ion-exchange particles and a porous support for fabricating bipolar membranes and the results of an assessment of the applicability of these materials to water splitting. In order to achieve good mechanical as well as good ion-exchange properties, bipolar membranes were prepared by laminating poly(phenylene oxide) and polystyrene based ion-exchange membranes with a sulfonated polystyrene-block-(ethylene-ran-butylene)-block-polystyrene) (S-SEBS) modified interface. PE pore-supported ion-exchange membranes were also used as bipolar membranes. The tensile strength was 13.21 MPa for the bipolar membrane which utilized only a cation/anion-exchange membrane. When ion-exchange nanoparticles were introduced for high efficiency, a reduction in the tensile strength to 6.81 MPa was observed. At the same time, bipolar membrane in the form of a composite membrane using PE support exhibited the best tensile strength of 32.41 MPa. To confirm the water-splitting performance, an important factor for a bipolar membrane, pH changes over a period of 20 min were also studied. During water slitting using CA-P-PE-BPM, the pH at the CEM part and the AEM part changed from 5.4 to 4.18 and from 5.4 to 5.63, respectively.
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Affiliation(s)
- Tae Yang Son
- Department of Materials Engineering and Convergence Technology, Engineering Research Insitute, Gyeongsang National University, Jinju, 52828, Korea
| | - Jun Seong Yun
- Department of Materials Engineering and Convergence Technology, Engineering Research Insitute, Gyeongsang National University, Jinju, 52828, Korea
| | - Kihyun Kim
- Department of Polymer Science and Engineering, Engineering Research Institute, Gyeonsang National University, Jinju, 52828, Republic of Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Engineering Research Insitute, Gyeongsang National University, Jinju, 52828, Korea
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Lee JW, Im KS, Nam SY. Investigation of Formation for Poly(vinylidene fluoride) Membrane Using Thermally Induced Phase Separation. J Nanosci Nanotechnol 2020; 20:7140-7144. [PMID: 32604572 DOI: 10.1166/jnn.2020.18829] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this study, thermally induced phase separation (TIPS) was used to fabricate a water treatment membrane composed of poly(vinylidene fluoride) (PVDF) and silica. Dioctyl phthalate (DOP) and dibutyl phthalate (DBP) were used as diluents. Crystallization temperature, cloud point, and morphology were observed to investigate the conditions of PVDF/silica/diluent membrane preparation. SEM revealed that the porosity of the membranes was increased with an increase in silica content. Phase diagram and morphology results revealed that 50 wt% PVDF+silica with a PVDF:silica weight ratio of 4.5:1 is the best composition for manufacturing a porous membrane.
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Affiliation(s)
- Jeong Woo Lee
- Department of Material Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Korea
| | - Kwang Seop Im
- Department of Material Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Korea
| | - Sang Yong Nam
- Department of Material Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Korea
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Son TY, Kim DJ, Vijayakumar V, Kim K, Kim DS, Nam SY. Anion exchange membrane using poly(ether ether ketone) containing imidazolium for anion exchange membrane fuel cell (AEMFC). J IND ENG CHEM 2020. [DOI: 10.1016/j.jiec.2020.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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20
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21
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Vijayakumar V, Son TY, Kim HJ, Nam SY. A facile approach to fabricate poly(2,6-dimethyl-1,4-phenylene oxide) based anion exchange membranes with extended alkaline stability and ion conductivity for fuel cell applications. J Memb Sci 2019. [DOI: 10.1016/j.memsci.2019.117314] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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22
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23
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Hossain I, Nam SY, Rizzuto C, Barbieri G, Tocci E, Kim TH. PIM-polyimide multiblock copolymer-based membranes with enhanced CO2 separation performances. J Memb Sci 2019. [DOI: 10.1016/j.memsci.2018.12.084] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lim H, Lee B, Yun D, Al Munsur AZ, Chae JE, Lee SY, Kim HJ, Nam SY, Park CH, Kim TH. Poly(2,6-dimethyl-1,4-phenylene oxide)s with Various Head Groups: Effect of Head Groups on the Properties of Anion Exchange Membranes. ACS Appl Mater Interfaces 2018; 10:41279-41292. [PMID: 30380830 DOI: 10.1021/acsami.8b13016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Poly(2,6-dimethyl-1,4-phenylene oxide)s (PPOs)-based anion exchange membranes (AEMs) with four of the most widely investigated head groups were prepared. Through a combination of experimental and simulation approaches, the effects of the different types of head groups on the properties of the AEMs, including hydroxide conductivity, water content, physicochemical stability, and fuel cell device performance were fully explored. Unlike other studies, in which the conductivity was mostly investigated in liquid water, the conductivity of the PPO-based AEMs in 95% relative humidity (RH) conditions as well as in liquid water was investigated. The conductivity trend in 95% RH condition was different from that in liquid water but corresponded well with the actual cell performance trend observed, suggesting that the AEM fuel cell performance under in situ cell conditions (95% RH, 60 °C, H2/O2) is more closely related to the conductivity measured ex situ under 95% RH conditions (60 °C) than in liquid water. On the basis of the conductivity data and molecular simulation results, it was concluded that the predominant hydroxide ion-conducting mechanism in liquid water differs from that in the operating fuel cell environment, where the ionomers become hydrated only as a result of water vapor transported into the cells.
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Affiliation(s)
| | | | | | | | - Ji Eon Chae
- Fuel Cell Research Center , Korea Institute of Science and Technology , Seoul 136-791 , Korea
| | - So Young Lee
- Fuel Cell Research Center , Korea Institute of Science and Technology , Seoul 136-791 , Korea
| | - Hyoung-Juhn Kim
- Fuel Cell Research Center , Korea Institute of Science and Technology , Seoul 136-791 , Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute , Gyeongsang National University , Jinju 660-701 , Korea
| | - Chi Hoon Park
- Department of Energy Engineering , Gyeongnam National University of Science and Technology , Jinju 52725 , Korea
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Lee BN, Son TY, Park CH, Kim TH, Nam SY. Preparation and Characterization of Various Poly(ether ether ketone) Containing Imidazolium Moiety for Anion Exchange Membrane Fuel Cell Application. J Nanosci Nanotechnol 2018; 18:6447-6454. [PMID: 29677812 DOI: 10.1166/jnn.2018.15681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this study, various poly(ether ether ketone) were synthesized using three different monomers and the imidazolium group was introduced into synthesized poly(ether ether ketone)s by using substitution reaction. Synthesized polymers were used to prepare anion exchange membranes and to evaluate its properties. Thermal, chemical and structural properties were carried out using thermogravimetric analysis, nuclear magnetic resonance. The anion exchange membranes with different imidazolium moieties were characterized by several different analytical techniques such as water up take, ion exchange capacity, hydroxide conductivity for checking the possibility to apply the anion exchange membrane fuel cell. Consequently, results of characterization were studied to understand the correlation between stabilities of the membrane and functional group and polymer backbone structures. And we confirm membrane performance was improved by increasing imidazolium cation groups.
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Affiliation(s)
- Byeol-Nim Lee
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Tae Yang Son
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Chi Hoon Park
- Department of Energy Engineering, Gyeongsang National University of Science and Technology (GNTECH), Jinju, 52725, Korea
| | - Tae Hyun Kim
- Organic Material Synthesis Laboratory, Department of Chemistry, Incheon National University, Incheon, 22012, Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
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28
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Son TY, Jeong MA, Nam SY. Amorphous Fluoropolymer Membrane for Gas Separation Applications. J Nanosci Nanotechnol 2018; 18:6206-6212. [PMID: 29677768 DOI: 10.1166/jnn.2018.15641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Amorphous fluoropolymers have been studied in the past few decades and received extensive attention due to their unique and useful properties. One of the remarkable properties of amorphous fluoropolymers is high fractional free volume (FFV), and they tend to retain large amounts of solvent inside their polymer chains. In this study, amorphous flouoropolymer membranes were employed to examine the influences of the residual solvent and drying condition on the thermal properties, gas permeation behavior, and structure change by the polymer chains. Thermal properties of the produced membranes were characterized by differential scanning calorimetry (DSC) and a thermogravimetric analysis (TGA) to verify the effects of residual solvent. The residual solvent content and the glass transition temperature (Tg) of amorphous fluoropolymer membranes prepared with both solvents decrease with increasing drying temperature. The effect of the thermal treatment method on the d-spacing between the polymer chains of the prepared membranes was investigated using X-ray diffraction (XRD). The d-spacing decreased with drying below the Tg whereas it drastically increased near the Tg because of chain relaxation. From these phenomena, the helium permeability of the membranes treated at 120 °C radically increased. However, the oxygen and nitrogen permeability decreased with decreasing residual solvent content. The glass transition range shifted to higher temperature, from 75 °C to 133 °C, depending on the reduced amount of residual solvent.
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Affiliation(s)
- Tae Yang Son
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju, 52828, Korea
| | - Mi Ae Jeong
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju, 52828, Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju, 52828, Korea
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Kim SJ, Lee JW, Nam SY. Fabrication of Cellulose Triacetate Hollow Fiber Membranes for Forward Osmosis-Nanofiltration. J Nanosci Nanotechnol 2018; 18:6180-6188. [PMID: 29677764 DOI: 10.1166/jnn.2018.15640] [Citation(s) in RCA: 1] [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: 06/08/2023]
Abstract
In this study, hollow fiber membranes for forward osmosis using cellulose triacetate were prepared using the non-solvent phase separation method, and the water purification properties of the prepared membranes were tested. In order to optimize the membrane morphology, which affects the membrane performance, 1,4-dioxane and lithium chloride were used as additives. Using the forward osmosis process, the properties of the membrane were investigated according to changes in the factors such as the salt type, salt concentration, and solution temperature. In the nanofiltration process, the water flux was found to increase and the salt rejection to decrease with increasing air gaps, regardless of the type of salt. In contrast, in the forward osmosis process, the water flux increased and the solute rejection value increased in a manner similar to the increasing concentration of solute.
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Affiliation(s)
- Se Jong Kim
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Jeong Woo Lee
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute, Gyeongsang National University, Jinju, 52828, Republic of Korea
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Kim EK, Lee SY, Nam SY, Yoo SJ, Kim JY, Jang JH, Henkensmeier D, Kim HJ, Lee JC. Synthesis of high molecular weight polybenzimidazole using a highly pure monomer under mild conditions. POLYM INT 2017. [DOI: 10.1002/pi.5426] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Eun-Ki Kim
- Fuel Cell Research Center, Korea Institute of Science and Technology; Seoul Republic of Korea
- School of Chemical and Biological Engineering; Seoul National University; Republic of Korea
| | - So Young Lee
- Fuel Cell Research Center, Korea Institute of Science and Technology; Seoul Republic of Korea
| | - Sang Yong Nam
- Department of Materials Engineering and Convergence Technology, Engineering Research Institute; Gyeongsang National University; Jinju Korea
| | - Sung Jong Yoo
- Fuel Cell Research Center, Korea Institute of Science and Technology; Seoul Republic of Korea
| | - Jin Young Kim
- Fuel Cell Research Center, Korea Institute of Science and Technology; Seoul Republic of Korea
| | - Jong Hyun Jang
- Fuel Cell Research Center, Korea Institute of Science and Technology; Seoul Republic of Korea
| | - Dirk Henkensmeier
- Fuel Cell Research Center, Korea Institute of Science and Technology; Seoul Republic of Korea
| | - Hyoung-Juhn Kim
- Fuel Cell Research Center, Korea Institute of Science and Technology; Seoul Republic of Korea
| | - Jong-Chan Lee
- School of Chemical and Biological Engineering; Seoul National University; Republic of Korea
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Whang YB, Kim SY, Nam SY, Yeo SG, Park DC. Ectopic pregnancy occurring in the remnant tube of a previous adnexectomy: a case report. CLIN EXP OBSTET GYN 2017; 44:146-147. [PMID: 29714886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ectopic pregnancy occurring in the same region is a comparatively rare disease, but sometimes it is very serious to patients if it is delayed. The authors present a case of spontaneous ectopic pregnancy occurring in the ipsilateral salpingectomy stump of a previous adnexectomy that was successfully removed via laparoscopic surgery without complication. This case may support the idea of intrauterine transmigration of a fertilized egg as an etiology of spontaneous ectopic pregnancy. Thus, the potential for ectopic pregnancy in the tubal remnant in cases of previous salpingectomy or adnexectomy needs to be carefully considered.
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Meiburger KM, Nam SY, Chung E, Suggs LJ, Emelianov SY, Molinari F. Skeletonization algorithm-based blood vessel quantification usingin vivo3D photoacoustic imaging. Phys Med Biol 2016; 61:7994-8009. [DOI: 10.1088/0031-9155/61/22/7994] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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33
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Gong EJ, Kim DH, Ahn JY, Choi KS, Jung KW, Lee JH, Choi KD, Song HJ, Lee GH, Jung HY, Kim JH, Roh JL, Choi SH, Nam SY, Kim SY. Routine endoscopic screening for synchronous esophageal neoplasm in patients with head and neck squamous cell carcinoma: a prospective study. Dis Esophagus 2016; 29:752-759. [PMID: 26471351 DOI: 10.1111/dote.12404] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [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] [Indexed: 12/11/2022]
Abstract
Early detection of synchronous esophageal squamous cell neoplasm (ESCN) in head and neck squamous cell carcinoma (HNSCC) patients can significantly affect their prognosis. We investigated the prevalence of synchronous ESCN and the risk factors for developing ESCN in patients with HNSCC, and evaluated the effect of routine endoscopic screening in these patients. Subjects who were diagnosed as HNSCC from May 2010 to January 2014 were eligible. All patients underwent conventional white light endoscopic examinations with narrow band imaging and Lugol chromoendoscopy. Among 458 subjects screened, 28 synchronous ESCN were detected in 24 patients (5.2%). The prevalence of ESCN was greatest in patients with hypopharyngeal cancer (20.9%). In multivariate analysis, pyriform sinus involvement was independent risk factor for developing synchronous ESCN (odds ratio 171.2, P < 0.001). During the follow-up period (median, 24 months), the 3-year overall survival rates was significantly lower in patients with ESCN than in patients without ESCN (54.2% vs. 78.3%, P = 0.0013). Routine endoscopic screening for detecting synchronous ESCN should be recommended for patients with HNSCC, especially those with pyriform sinus involvement.
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Affiliation(s)
- E J Gong
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - D H Kim
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
| | - J Y Ahn
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - K-S Choi
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - K W Jung
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - J H Lee
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - K D Choi
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - H J Song
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - G H Lee
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - H-Y Jung
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - J H Kim
- Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - J-L Roh
- Department of otolaryngology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - S-H Choi
- Department of otolaryngology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - S Y Nam
- Department of otolaryngology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - S Y Kim
- Department of otolaryngology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
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Koo HJ, Lee JH, Kim GY, Choi YJ, Baek JH, Choi SH, Nam SY, Kim SY, Suh DC. Ethanol and/or radiofrequency ablation to treat venolymphatic malformations that manifest as a bulging mass in the head and neck. Clin Radiol 2016; 71:1070.e1-1070.e7. [PMID: 27076254 DOI: 10.1016/j.crad.2016.03.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/13/2016] [Accepted: 03/14/2016] [Indexed: 12/18/2022]
Abstract
AIM To evaluate the efficacy of ultrasound (US)-guided ethanol ablation (EA) and radiofrequency ablation (RFA) for treating venolymphatic malformations (VLM) of the head and neck. MATERIALS AND METHODS US-guided EA and/or RFA were performed on 17 patients with VLM of the head and neck. Computed tomography (CT) or magnetic resonance imaging (MRI) was used to locate the cranial nerves and salivary gland ducts that were close to targets, and these were avoided during the procedures. Treatment response was assessed using volume reduction and cosmetic grading scoring. RESULTS Nine VLMs were located close to the functional structures: Stensen's duct (n=3), cranial nerve branch (n=3), or both (n=3). All patients demonstrated >50% volume reduction, except one patient with a microcystic lymphatic malformation that was abutting the facial nerve. Median cosmetic grading scores improved from 4 to 1 (p<0.001). CONCLUSION US-guided EA and/or RFA are effective and safe treatment methods in patients with VLMs of the head and neck. Treatment selection of EA and/or RFA could be performed based on the composition of VLMs as assessed at CT and MRI.
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Affiliation(s)
- H J Koo
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - J H Lee
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
| | - G Y Kim
- University of Missouri-Kansas City, School of Medicine, Kansas City, MO, USA
| | - Y J Choi
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - J H Baek
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - S-H Choi
- Department of Otorhinolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - S Y Nam
- Department of Otorhinolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - S Y Kim
- Department of Otorhinolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - D C Suh
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
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Yu DM, Nam SW, Yoon S, Kim TH, Lee JY, Nam SY, Hong YT. Edge protection using polyacrylonitrile thin-films for hydrocarbon-based membrane electrode assemblies. J IND ENG CHEM 2015. [DOI: 10.1016/j.jiec.2015.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lee HJ, Han SH, Nam SY. Gas permeation properties of poly(sulfone-co-ethylene glycol) membranes containing bis(phenyl)fluorene moieties. J Memb Sci 2015. [DOI: 10.1016/j.memsci.2015.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Kim SU, Yu DM, Kim TH, Hong YT, Nam SY, Choi JH. Effect of sulfonated poly(arylene ether sulfone) binder on the performance of polymer electrolyte membrane fuel cells. J IND ENG CHEM 2015. [DOI: 10.1016/j.jiec.2014.08.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lee BM, Kim DJ, Nam SY. Effect of Bulky and Hydroxyl Groups on Gas Separation Performance of Polyimide Membranes. J Nanosci Nanotechnol 2015; 15:2351-2355. [PMID: 26413666 DOI: 10.1166/jnn.2015.10260] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A series of polyimides were synthesized by a polycondensation reaction using various aromatic dianhydrides and diamines containing bulky cardo and hydroxyl groups. The imidization and chemical structure of the polyimides were confirmed by NMR and FT-IR. The thermal and gas properties of the polyimides were measured by time-lag, XRD, TGA, and DSC studies. The polyimides showed excellent solubility in common organic solvents and high thermal stability. The CO2 selectivity of HPI membrane was higher than traditional polyimides. In particular, the incorporation of hydroxyl groups improved the CO2 permeability of the polyimide due to increased carbon dioxide solubility. The HPI was thermally converted to polybenzoxazole (PBO) at 450 °C.
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Lee HJ, Kim DJ, Nam SY. CO2 Gas Transport Property of Sulfonated Poly(Arylenen Ether Sulfone) Copolymer Membrane. J Nanosci Nanotechnol 2015; 15:2547-2551. [PMID: 26413703 DOI: 10.1166/jnn.2015.10259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The effect of functional groups such as sulfuric acid group and metal ions on the CO2 gas transport property of membranes was investigated. Sulfonated poly(arylene ether sulfone) (SPAES) was prepared by direct copolymerization with a non-sulfonated monomer and sulfonated monomer. The sulfonation degree of SPAES was controlled from 0 to 50%. Metal ions such as lithium and sodium were substituted for the protons of the -SO3H group. The thermal properties, microstructure of polymer chains, and the permeability and selectivity of membranes were evaluated. The solubility coefficient of CO2 gas increased with an increase in sulfonation degree. But the diffusivity was largely decreased and the CO2/N2 selectivity of the membrane substituted for metal ions was increased.
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Eom HJ, Lee JH, Ko MS, Choi YJ, Yoon RG, Cho KJ, Nam SY, Baek JH. Comparison of fine-needle aspiration and core needle biopsy under ultrasonographic guidance for detecting malignancy and for the tissue-specific diagnosis of salivary gland tumors. AJNR Am J Neuroradiol 2015; 36:1188-93. [PMID: 25678480 DOI: 10.3174/ajnr.a4247] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 11/25/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND PURPOSE Diagnostic test accuracy studies for ultrasonography-guided fine-needle aspiration and ultrasonography-guided core needle biopsy have shown inconclusive results due to their heterogenous study designs. Our aim was to compare the diagnostic accuracy of ultrasonography-guided fine-needle aspiration versus ultrasonography-guided core needle biopsy for detecting malignant tumors of the salivary gland and for the tissue-specific diagnosis of salivary gland tumors in a single tertiary hospital. MATERIALS AND METHODS This retrospective study was approved by our institutional review board and informed consent was waived. Four hundred twelve patients who underwent ultrasonography-guided fine-needle aspiration (n = 155) or ultrasonography-guided core needle biopsy (n = 257) with subsequent surgical confirmation or clinical follow-up were enrolled. We compared the diagnostic accuracy of ultrasonography-guided fine-needle aspiration and ultrasonography-guided core needle biopsy regarding malignant salivary gland tumors and the correct tissue-specific diagnosis of benign and malignant tumors. We also tested the difference between these procedures according to the operator's experience and lesion characteristics. RESULTS The inconclusive rates of ultrasonography-guided fine-needle aspiration and ultrasonography-guided core needle biopsy were 19% and 4%, respectively (P < .001). The overall accuracy of ultrasonography-guided core needle biopsy for diagnosing malignant tumors was significantly higher than that of ultrasonography-guided fine-needle aspiration (P = .024). The correct tissue-specific diagnosis rates of ultrasonography-guided fine-needle aspiration and ultrasonography-guided core needle biopsy were 95% versus 97% for benign tumors (P = .648) and 67% versus 80% for malignant tumors (P = .310). Trainees showed significantly lower accuracy with ultrasonography-guided fine-needle aspiration than with ultrasonography-guided core needle biopsy for diagnosing malignant tumors (P = .021). There was no difference between the diagnostic accuracy of ultrasonography-guided fine-needle aspiration and ultrasonography-guided core needle biopsy according to the internal composition of the lesions. There were no complications requiring intervention or hospitalization in our patients. CONCLUSIONS Ultrasonography-guided core needle biopsy is superior to ultrasonography-guided fine-needle aspiration in detecting and characterizing malignant tumors of the salivary gland and could emerge as the diagnostic method of choice for patients presenting with a salivary gland mass.
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Affiliation(s)
- H-J Eom
- From the Department of Radiology and Research Institute of Radiology (H.-J.E., J.H.L., Y.J.C., R.G.Y., J.H.B.)
| | - J H Lee
- From the Department of Radiology and Research Institute of Radiology (H.-J.E., J.H.L., Y.J.C., R.G.Y., J.H.B.)
| | - M-S Ko
- Departments of Health Medicine (M.-S.K.)
| | - Y J Choi
- From the Department of Radiology and Research Institute of Radiology (H.-J.E., J.H.L., Y.J.C., R.G.Y., J.H.B.)
| | - R G Yoon
- From the Department of Radiology and Research Institute of Radiology (H.-J.E., J.H.L., Y.J.C., R.G.Y., J.H.B.)
| | | | - S Y Nam
- Otolaryngology (S.Y.N.), Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - J H Baek
- From the Department of Radiology and Research Institute of Radiology (H.-J.E., J.H.L., Y.J.C., R.G.Y., J.H.B.)
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Kim SY, Kim MS, Lee MK, Kim JS, Yi HK, Nam SY, Lee DY, Hwang PH. PPARγ induces growth inhibition and apoptosis through upregulation of insulin-like growth factor-binding protein-3 in gastric cancer cells. ACTA ACUST UNITED AC 2015; 48:226-33. [PMID: 25590353 PMCID: PMC4381942 DOI: 10.1590/1414-431x20144212] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 10/13/2014] [Indexed: 12/23/2022]
Abstract
Peroxisome proliferator activator receptor-gamma (PPARγ) is a ligand-activated
transcriptional factor involved in the carcinogenesis of various cancers.
Insulin-like growth factor-binding protein-3 (IGFBP-3) is a tumor
suppressor gene that has anti-apoptotic activity. The purpose of this study was to
investigate the anticancer mechanism of PPARγ with respect to
IGFBP-3. PPARγ was overexpressed in SNU-668 gastric cancer cells
using an adenovirus gene transfer system. The cells in which PPARγ was overexpressed
exhibited growth inhibition, induction of apoptosis, and a significant increase in
IGFBP-3 expression. We investigated the underlying molecular
mechanisms of PPARγ in SNU-668 cells using an IGFBP-3 promoter/luciferase reporter
system. Luciferase activity was increased up to 15-fold in PPARγ transfected cells,
suggesting that PPARγ may directly interact with IGFBP-3 promoter to induce its
expression. Deletion analysis of the IGFBP-3 promoter showed that luciferase activity
was markedly reduced in cells without putative p53-binding sites (-Δ1755, -Δ1795).
This suggests that the critical PPARγ-response region is located within the
p53-binding region of the IGFBP-3 promoter. We further demonstrated an increase in
PPARγ-induced luciferase activity even in cells treated with siRNA to silence p53
expression. Taken together, these data suggest that PPARγ exhibits its anticancer
effect by increasing IGFBP-3 expression, and that IGFBP-3 is a significant tumor
suppressor.
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Affiliation(s)
- S Y Kim
- Department of Pediatrics, Chonbuk National University Hospital, Jeonju, Korea
| | - M S Kim
- Department of Pediatrics, Chonbuk National University Hospital, Jeonju, Korea
| | - M K Lee
- Department of Pediatrics, Chonbuk National University Hospital, Jeonju, Korea
| | - J S Kim
- Department of Biochemistry, School of Dentistry, Chonbuk National University, Jeonju, Korea
| | - H K Yi
- Department of Biochemistry, School of Dentistry, Chonbuk National University, Jeonju, Korea
| | - S Y Nam
- Department of Alternative Therapy, Jeonju University, Jeonju, Korea
| | - D Y Lee
- Department of Pediatrics, Chonbuk National University Hospital, Jeonju, Korea
| | - P H Hwang
- Department of Pediatrics, Chonbuk National University Hospital, Jeonju, Korea
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Woo SM, Chung YS, Lee SY, Nam SY. Preparation and properties of hollow fiber membranes for removing virus and bacteria. J Nanosci Nanotechnol 2014; 14:9628-9631. [PMID: 25971110 DOI: 10.1166/jnn.2014.10192] [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: 06/04/2023]
Abstract
In this study, polysulfone hollow fiber membrane was successfully prepared by phase inversion method for separation of virus and bacteria. When we prepare the hollow fiber membrane, we controlled various factors such as the polymer concentration, air gap and internal coagulation to investigate effect to membrane property. Morphology of surface and cross section of membrane were measured by field emission scanning electron microscope (FE-SEM). Water flux of membrane was measured using test modules. Mean pore diameter of membrane was calculated using rejection of polystyrene (PS) latex beads for separation of virus and bacteria. Flux and mean flow pore diameter of prepared membrane show 800 L/mh, 0.03 μm at 1.0 kgf/cm2. The bacteria removal performance of prepared UF membranes was over 6 logs
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Yim WJ, Lee KC, Nam SY. Colored polystyrene particles with a surface charge influenced by suspension polymerization. J Nanosci Nanotechnol 2014; 14:8964-8968. [PMID: 25970991 DOI: 10.1166/jnn.2014.10074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Blue polystyrene (PS) particles copolymerized with poly (ethylene glycol) ether methyl methacrylate (PEG-MA, Mn = 300, 475, 950) were prepared by suspension polymerization in this study. 0-10 wt% PEG-MA was copolymerized with 100-90 wt% styrene by suspension polymerization. These blue PS particles were characterized using SEM, IR, UV, DSC, and zeta potential measurements. The T(g) data results for the suspension copolymers and a solubility test in THF along with the matching IR spectroscopy results showed that copolymerization proceeded during the polymerization process. The poly[styrene-co-(PEG-MA)] latices were 30-60 nm in size, with T(g) values of 341-385 degrees K, zeta- potential values of 51.5-162 mV, and electrophoretic mobility values ranging from 3.3 to 10.9 x 10(-6) cm2/Vs. Blue dye incorporated into the polystyrene particles existed at levels that exceeded 85% based on the UV absorbance results.
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Abstract
Stem cell-based therapies have demonstrated improved outcomes in preclinical and clinical trials for treating cardiovascular ischemic diseases. However, the contribution of stem cells to vascular repair is poorly understood. To elucidate these mechanisms, many have attempted to monitor stem cells following their delivery in vivo, but these studies have been limited by the fact that many contrast agents, including nanoparticles, are commonly passed on to non-stem cells in vivo. Specifically, cells of the reticuloendothelial system, such as macrophages, frequently endocytose free contrast agents, resulting in the monitoring of macrophages instead of the stem cell therapy. Here we demonstrate a dual gold nanoparticle system which is capable of monitoring both delivered stem cells and infiltrating macrophages using photoacoustic imaging. In vitro analysis confirmed preferential labeling of the two cell types with their respective nanoparticles and the maintenance of cell function following nanoparticle labeling. In addition, delivery of the system within a rat hind limb ischemia model demonstrated the ability to monitor stem cells and distinguish and quantify macrophage infiltration. These findings were confirmed by histology and mass spectrometry analysis. This work has important implications for cell tracking and monitoring cell-based therapies.
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Affiliation(s)
- L M Ricles
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712
| | - S Y Nam
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712. ; Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX 78712
| | - E A Treviño
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712
| | - S Y Emelianov
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712. ; Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX 78712
| | - L J Suggs
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712
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Yun HJ, Park JM, Jeon CW, Nam SY, Shin SC, Hwang J, Kim YH. Synthesis and characterization of a new poly(octathiophene) based copolymer for organic thin-film transistor. J Nanosci Nanotechnol 2014; 14:5942-5946. [PMID: 25936032 DOI: 10.1166/jnn.2014.8806] [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] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new poly(octathiophene) based copolymer was designed and synthesized by the palladium catalyzed Suzuki coupling reaction. The structure of the newly obtained copolymer was confirmed by 1H-NMR and IR. The number-average molecular weight (M(n)) of the polymer was 36,000 with a poly-dispersity index of 1.15. The polymer has good solubility in common solvents such as chloroform, toluene, chlorobenzene, dichlorobenzene and tetrahydrofuran at room temperature. The optical, thermal and electrochemical properties of the polymer were characterized by UV-vis absorption, TGA and DSC and cyclovoltametry, respectively. A thin film transistor using the new polymer as an organic semiconductor was found to exhibit typical p-channel FET characteristics with a hole mobility of 5 x 10(-4) cm2/Vs.
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Park SM, Kang I, Ma JY, Nam SY, Hwang J, Kim YH. Organic semiconductor based on asymmetric naphthalene-thiophene molecule for organic thin film transistor. J Nanosci Nanotechnol 2014; 14:6172-6176. [PMID: 25936081 DOI: 10.1166/jnn.2014.8805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The new asymmetric semiconductor 5-(6-decylnaphthalen-2-yl)-5'-(naphthalene-2-yl)-2,2'-bithiophene (NBTND) was synthesized by Suzuki coupling reaction for an organic thin film transistor (OTFT) material. This asymmetric molecule was characterized by H-NMR, IR, HRMS, UV-visible spectroscopy, cyclovoltammetry, thermogravimetric analysis, differential scanning calorimetry. The thin film transistor using new asymmetric semiconductor exhibited the field effect mobility of 2.68 x 10(-2) cm2 V(-1) s(-1).
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Park GC, Lee M, Roh JL, Choi SH, Nam SY, Kim SY, Cho KJ. Phospho-Rb (Ser780) as a biomarker in patients with cervical lymph node metastases from an unknown primary tumour: a retrospective cohort study. Clin Otolaryngol 2014; 38:313-21. [PMID: 23731755 DOI: 10.1111/coa.12138] [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] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2013] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Cervical lymph node metastases from an unknown primary tumour are a heterogeneous disease entity with various clinical features. There are many controversies regarding treatment methods and treatment response predictions. Therefore, we examined the prognostic significance of biomarkers in patients with cervical metastasis of unknown primary tumour. DESIGN A molecular study of retrospective cohorts. SETTING University teaching hospital. MAIN OUTCOME MEASURES Metastatic cervical lymph nodes of 36 patients with cervical unknown primary metastasis of squamous cell carcinoma were assessed by in situ hybridisation for human papillomavirus and immunohistochemistry for p16, retinoblastoma protein (phospho-Ser780), hypoxia-inducible factor-1α, glucose transporter 1 and carbonic anhydrase 9 expression. Clinicopathological factors and biomarkers were analysed for their associations with disease-free survival and overall survival. RESULTS Univariate analysis showed that nodal extracapsular spread was associated with poor overall survival (P = 0.049), nodal-positive retinoblastoma protein staining were significantly associated with poor outcomes of both disease-free survival (P = 0.035) and overall survival (P = 0.019), Multivariate analysis revealed that nodal positivity of retinoblastoma protein and nodal extracapsular spread were the significant predictors of overall survival (P = 0.049, hazard ratio = 6.21, 95% confidence interval = 1.01-38.35 and P = 0.037, hazard ratio = 4.34, 95% confidence interval = 1.09-17.21, respectively). CONCLUSION The retinoblastoma protein expression of metastatic lymph nodes represents an independent prognostic indicator in patients with cervical metastasis of unknown primary tumour.
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Affiliation(s)
- G C Park
- Department of Otolaryngology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
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