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Lee DU, Kayumov M, Park J, Park SK, Kang Y, Ahn Y, Kim W, Yoo SH, Park JK, Kim BG, Oh YS, Jeong IS, Choi DY. Antibiofilm and antithrombotic hydrogel coating based on superhydrophilic zwitterionic carboxymethyl chitosan for blood-contacting devices. Bioact Mater 2024; 34:112-124. [PMID: 38204564 PMCID: PMC10777421 DOI: 10.1016/j.bioactmat.2023.12.009] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 01/12/2024] Open
Abstract
Blood-contacting devices must be designed to minimize the risk of bloodstream-associated infections, thrombosis, and intimal lesions caused by surface friction. However, achieving effective prevention of both bloodstream-associated infections and thrombosis poses a challenge due to the conflicting nature of antibacterial and antithrombotic activities, specifically regarding electrostatic interactions. This study introduced a novel biocompatible hydrogel of sodium alginate and zwitterionic carboxymethyl chitosan (ZW@CMC) with antibacterial and antithrombotic activities for use in catheters. The ZW@CMC hydrogel demonstrates a superhydrophilic surface and good hygroscopic properties, which facilitate the formation of a stable hydration layer with low friction. The zwitterionic-functionalized CMC incorporates an additional negative sulfone group and increased negative charge density in the carboxyl group. This augmentation enhances electrostatic repulsion and facilitates the formation of hydration layer. This leads to exceptional prevention of blood clotting factor adhesion and inhibition of biofilm formation. Subsequently, the ZW@CMC hydrogel exhibited biocompatibility with tests of in vitro cytotoxicity, hemolysis, and catheter friction. Furthermore, in vivo tests of antithrombotic and systemic inflammation models with catheterization indicated that ZW@CMC has significant advantages for practical applications in cardiovascular-related and sepsis treatment. This study opens a new avenue for the development of chitosan-based multifunctional hydrogel for applications in blood-contacting devices.
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Affiliation(s)
- Dong Uk Lee
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Mukhammad Kayumov
- Department of Thoracic and Cardiovascular Surgery, Chonnam National University Hospital and Medical School, Gwangju, 61469, Republic of Korea
| | - Junghun Park
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Se Kye Park
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Yeongkwon Kang
- Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yejin Ahn
- Department of Organic and Nano System Engineering, Konkuk University, Seoul, 05029, Republic of Korea
| | - Woojin Kim
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Seung Hwa Yoo
- Department of Quantum System Engineering, Jeonbuk National University, Jeonju-si, 54896, Republic of Korea
| | | | - Bong-Gi Kim
- Department of Organic and Nano System Engineering, Konkuk University, Seoul, 05029, Republic of Korea
| | - Yong Suk Oh
- Department of Mechanical Engineering, Changwon National University, Changwon, 51140, Republic of Korea
| | - In-Seok Jeong
- Department of Thoracic and Cardiovascular Surgery, Chonnam National University Hospital and Medical School, Gwangju, 61469, Republic of Korea
| | - Dong Yun Choi
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
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Lee DU, Jeong SB, Lee BJ, Park SK, Kim HM, Shin JH, Lee SY, Kim G, Park J, Kim GM, Jung JH, Choi DY. Antimicrobial and Antifouling Effects of Petal-Like Nanostructure by Evaporation-Induced Self-Assembly for Personal Protective Equipment. Small 2024; 20:e2306324. [PMID: 37990401 DOI: 10.1002/smll.202306324] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/19/2023] [Indexed: 11/23/2023]
Abstract
Although the personal protective equipment (PPE) used by healthcare workers (HCWs) effectively blocks hazardous substances and pathogens, it does not fully rule out the possibility of infection, as pathogens surviving on the fabric surface pose a substantial risk of cross-infection through unintended means. Therefore, PPE materials that exhibit effective biocidal activity while minimizing contamination by viscous body fluids (e.g., blood and saliva) and pathogen-laden droplets are highly sought. In this study, petal-like nanostructures (PNSs) are synthesized through the vertical rearrangement of colloidal lamellar bilayers via evaporation-induced self-assembly of octadecylamine, silica-alumina sol, and diverse photosensitizer. The developed method is compatible with various fabrics and imparts visible-light-activated antimicrobial and superhydrophobic-based antifouling activities. PNS-coated fabrics could provide a high level of protection and effectively block pathogen transmission as exemplified by their ability to roll off viscous body fluids reducing bacterial droplet adhesion and to inactivate various microorganisms. The combination of antifouling and photobiocidal activities results in the complete inactivation of sprayed pathogen-laden droplets within 30 min. Thus, this study paves the way for effective contagious disease management and the protection of HCWs in general medical environments, inspiring further research on the fabrication of materials that integrate multiple useful functionalities.
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Affiliation(s)
- Dong Uk Lee
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Sang Bin Jeong
- Indoor Environment Center, Korea Testing Laboratory, Seoul, 08389, Republic of Korea
- Department of Mechanical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Byeong Jin Lee
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
- School of Mechanical Engineering, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Se Kye Park
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Hyoung-Mi Kim
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Jae Hak Shin
- Department of Mechanical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Seung Yeon Lee
- Department of Mechanical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Gunwoo Kim
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Junghun Park
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
| | - Gyu Man Kim
- School of Mechanical Engineering, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Jae Hee Jung
- Department of Mechanical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Dong Yun Choi
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
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Lee DU, Kim SC, Choi DY, Jung WK, Moon MJ. Basic amino acid-mediated cationic amphiphilic surfaces for antimicrobial pH monitoring sensor with wound healing effects. Biomater Res 2023; 27:14. [PMID: 36800989 PMCID: PMC9936651 DOI: 10.1186/s40824-023-00355-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 02/12/2023] [Indexed: 02/19/2023] Open
Abstract
BACKGROUND The wound healing process is a complex cascade of physiological events, which are vulnerable to both our body status and external factors and whose impairment could lead to chronic wounds or wound healing impediments. Conventional wound healing materials are widely used in clinical management, however, they do not usually prevent wounds from being infected by bacteria or viruses. Therefore, simultaneous wound status monitoring and prevention of microbial infection are required to promote healing in clinical wound management. METHODS Basic amino acid-modified surfaces were fabricated in a water-based process via a peptide coupling reaction. Specimens were analyzed and characterized by X-ray photoelectron spectroscopy, Kelvin probe force microscopy, atomic force microscopy, contact angle, and molecular electrostatic potential via Gaussian 09. Antimicrobial and biofilm inhibition tests were conducted on Escherichia coli and Staphylococcus epidermidis. Biocompatibility was determined through cytotoxicity tests on human epithelial keratinocytes and human dermal fibroblasts. Wound healing efficacy was confirmed by mouse wound healing and cell staining tests. Workability of the pH sensor on basic amino acid-modified surfaces was evaluated on normal human skin and Staphylococcus epidermidis suspension, and in vivo conditions. RESULTS Basic amino acids (lysine and arginine) have pH-dependent zwitterionic functional groups. The basic amino acid-modified surfaces had antifouling and antimicrobial properties similar to those of cationic antimicrobial peptides because zwitterionic functional groups have intrinsic cationic amphiphilic characteristics. Compared with untreated polyimide and modified anionic acid (leucine), basic amino acid-modified polyimide surfaces displayed excellent bactericidal, antifouling (reduction ~ 99.6%) and biofilm inhibition performance. The basic amino acid-modified polyimide surfaces also exhibited wound healing efficacy and excellent biocompatibility, confirmed by cytotoxicity and ICR mouse wound healing tests. The basic amino acid-modified surface-based pH monitoring sensor was workable (sensitivity 20 mV pH-1) under various pH and bacterial contamination conditions. CONCLUSION Here, we developed a biocompatible and pH-monitorable wound healing dressing with antimicrobial activity via basic amino acid-mediated surface modification, creating cationic amphiphilic surfaces. Basic amino acid-modified polyimide is promising for monitoring wounds, protecting them from microbial infection, and promoting their healing. Our findings are expected to contribute to wound management and could be expanded to various wearable healthcare devices for clinical, biomedical, and healthcare applications.
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Affiliation(s)
- Dong Uk Lee
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea
- Department of Industrial Chemistry, Pukyong National University, Busan, 48513, Republic of Korea
| | - Se-Chang Kim
- Major of Biomedical Engineering, Division of Smart Healthcare, College of Information Technology and Convergence and New-Senior Healthcare Innovation Center (BK21 Plus), Pukyong National University, Busan, 48513, Korea
- Marine Integrated Biomedical Technology Center, The National Key Research Institutes in Universities, Pukyong National University, Busan, 48513, Korea
| | - Dong Yun Choi
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, 38822, Republic of Korea.
| | - Won-Kyo Jung
- Major of Biomedical Engineering, Division of Smart Healthcare, College of Information Technology and Convergence and New-Senior Healthcare Innovation Center (BK21 Plus), Pukyong National University, Busan, 48513, Korea.
- Marine Integrated Biomedical Technology Center, The National Key Research Institutes in Universities, Pukyong National University, Busan, 48513, Korea.
- Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan, 48513, Republic of Korea.
| | - Myung Jun Moon
- Department of Industrial Chemistry, Pukyong National University, Busan, 48513, Republic of Korea.
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Heo KJ, Lee DU, Shin JH, Park J, Lee BJ, Shin J, Jeong SB, Hwang GB, MacRobert AJ, Parkin IP, Jung JH, Choi DY. Transparent, Robust, and Photochemical Antibacterial Surface Based on Hydrogen Bonding between a Si-Al and Cationic Dye. ACS Appl Mater Interfaces 2022; 14:53285-53297. [PMID: 36395463 DOI: 10.1021/acsami.2c16071] [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] [Indexed: 06/16/2023]
Abstract
Healthcare-associated infections can occur and spread through direct contact with contaminated fomites in a hospital, such as mobile phones, tablets, computer keyboards, doorknobs, and other surfaces. Herein, this study shows a transparent, robust, and visible light-activated antibacterial surface based on hydrogen bonds between a transparent silica-alumina (Si-Al) sol-gel and a visible light-activated photosensitizer, such as crystal violet (CV). The study of the bonding mechanisms revealed that hydrogen bonding predominantly occurs between the N of CV and Al-OH. Apart from CV, Si-Al can be combined with a variety of dyes, highlighting its potential for wide application. The Si-Al@CV film selectively generates singlet oxygen using ambient visible light, triggering potent photochemical antibacterial performance against Gram-positive and Gram-negative bacteria. Additionally, the Si-Al@CV film is stable even after mechanical stability tests such as tape adhesion, scratch, bending, and water immersion. In vitro cytotoxicity tests using C2C12 myoblast cells showed that the Si-Al@CV film is a biocompatible material. This work suggests a new approach for designing a transparent and robust touchscreen surface with photochemical antibacterial capability against healthcare-associated infections.
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Affiliation(s)
- Ki Joon Heo
- Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
- School of Mechanical Engineering, Chonnam National University, Gwangju61186, Republic of Korea
| | - Dong Uk Lee
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon38822, Republic of Korea
| | - Jae Hak Shin
- Department of Mechanical Engineering, Sejong University, Seoul05006, Republic of Korea
| | - Junghun Park
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon38822, Republic of Korea
| | - Byeong Jin Lee
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon38822, Republic of Korea
| | - Juhun Shin
- Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
| | - Sang Bin Jeong
- Department of Mechanical Engineering, Sejong University, Seoul05006, Republic of Korea
| | - Gi Byoung Hwang
- Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
| | - Alexander J MacRobert
- UCL Division of Surgery and Interventional Science, Royal Free Campus, LondonNW3 2PF, United Kingdom
| | - Ivan P Parkin
- Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
| | - Jae Hee Jung
- Department of Mechanical Engineering, Sejong University, Seoul05006, Republic of Korea
| | - Dong Yun Choi
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon38822, Republic of Korea
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Jeong SB, Lee DU, Lee BJ, Heo KJ, Kim DW, Hwang GB, MacRobert AJ, Shin JH, Ko HS, Park SK, Oh YS, Kim SJ, Lee DY, Lee SB, Park I, Kim SB, Han B, Jung JH, Choi DY. Photobiocidal-triboelectric nanolayer coating of photosensitizer/silica-alumina for reusable and visible-light-driven antibacterial/antiviral air filters. Chem Eng J 2022; 440:135830. [PMID: 35313452 PMCID: PMC8926436 DOI: 10.1016/j.cej.2022.135830] [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: 01/15/2022] [Revised: 02/25/2022] [Accepted: 03/13/2022] [Indexed: 06/14/2023]
Abstract
Outbreaks of airborne pathogens pose a major threat to public health. Here we present a single-step nanocoating process to endow commercial face mask filters with photobiocidal activity, triboelectric filtration capability, and washability. These functions were successfully achieved with a composite nanolayer of silica-alumina (Si-Al) sol-gel, crystal violet (CV) photosensitizer, and hydrophobic electronegative molecules of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOTES). The transparent Si-Al matrix strongly immobilized the photosensitizer molecules while dispersing them spatially, thus suppressing self-quenching. During nanolayer formation, PFOTES was anisotropically rearranged on the Si-Al matrix, promoting moisture resistance and triboelectric charging of the Si-Al/PFOTES-CV (SAPC)-coated filter. The SAPC nanolayer stabilized the photoexcited state of the photosensitizer and promoted redox reaction. Compared to pure-photosensitizer-coated filters, the SAPC filter showed substantially higher photobiocidal efficiency (∼99.99 % for bacteria and a virus) and photodurability (∼83 % reduction in bactericidal efficiency for the pure-photosensitizer filter but ∼0.34 % for the SAPC filter after 72 h of light irradiation). Moreover, after five washes with detergent, the SAPC filter maintained its photobiocidal and filtration performance, proving its reusability potential. Therefore, this SAPC nanolayer coating provides a practical strategy for manufacturing an antimicrobial and reusable mask filter for use during the ongoing COVID-19 pandemic.
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Affiliation(s)
- Sang Bin Jeong
- Department of Mechanical Engineering, Sejong University, Seoul 05006, Republic of Korea
- Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Dong Uk Lee
- Department of Industrial Chemistry, Pukyong National University, Busan 48513, Republic of Korea
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon 38822, Republic of Korea
| | - Byeong Jin Lee
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon 38822, Republic of Korea
- School of Mechanical Engineering, Andong National University, Andong 36729, Republic of Korea
| | - Ki Joon Heo
- Material Chemistry Research Centre, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom
| | - Dong Won Kim
- Research Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Gi Byoung Hwang
- Material Chemistry Research Centre, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom
| | - Alexander J MacRobert
- UCL Division of Surgery and Interventional Science, Royal Free Campus, London NW3 2PF, United Kingdom
| | - Jae Hak Shin
- Department of Mechanical Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Hyun Sik Ko
- Department of Mechanical Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Se Kye Park
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon 38822, Republic of Korea
- Department of Polymer Science and Engineering, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Yong Suk Oh
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - See Jo Kim
- School of Mechanical Engineering, Andong National University, Andong 36729, Republic of Korea
| | - Dong Yun Lee
- Department of Polymer Science and Engineering, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Seung-Bok Lee
- Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Inyong Park
- Department of Environmental Machinery, Korea Institute of Machinery and Materials, Daejeon 34103, Republic of Korea
| | - Sang Bok Kim
- Department of Environmental Machinery, Korea Institute of Machinery and Materials, Daejeon 34103, Republic of Korea
| | - Bangwoo Han
- Department of Environmental Machinery, Korea Institute of Machinery and Materials, Daejeon 34103, Republic of Korea
| | - Jae Hee Jung
- Department of Mechanical Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Dong Yun Choi
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon 38822, Republic of Korea
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Lee DU, Kim DW, Lee SY, Choi DY, Choi SY, Moon KS, Shon MY, Moon MJ. Amino acid-mediated negatively charged surface improve antifouling and tribological characteristics for medical applications. Colloids Surf B Biointerfaces 2022; 211:112314. [PMID: 35033790 DOI: 10.1016/j.colsurfb.2021.112314] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [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: 11/19/2021] [Revised: 12/23/2021] [Accepted: 12/30/2021] [Indexed: 11/18/2022]
Abstract
To prevent infections associated with biomedical catheters, various antimicrobial coatings have been investigated. However, those materials do not provide consistent antibacterial effects or biocompatibility, generally, due to degradation of the coating materials, in vivo. Additionally, biomedical catheters must have low surface friction to reduce tribological damage. In this study, we developed an antifouling surface composed of biocompatible amino acids (leucine, taurine, and aspartic acid) on polyimide, via modification using a series of facile immersion steps with waterborne reactions. The naturally derived amino acid could be formed highly biostable amide bonds on the polyimide surface like peptides. The amino acid-modified surface formed a water layer with antifouling performance through the hydrophilic properties of amino acids. Amino acid-mediated modification reduced adhesion up to 84.45% and 94.81% against Escherichia coli and Staphylococcus epidermidis, respectively, and exhibited an excellent prevention to adhesion against the proteins, albumin and fibrinogen. Evaluation of the surface friction of the catheter revealed a dramatic reduction in the tribological force after amino acid modification on polyimide that of 0.81 N to aspartic acid of 0.44 N. These results clearly demonstrate a reduced occurrence of infections, thrombi and tribological damage following the relatively facile surface modification of catheters. The proposed modification method can be used in a continuous manufacturing process via using the same time of modification steps for the easy producing the product. Moreover, the method uses biocompatible naturally derived materials and can be applied to medical equipment that requires biocompatibility and biofunctionality with polyimide surfaces.
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Affiliation(s)
- Dong Uk Lee
- Department of Industrial Chemistry, Pukyong National University, Busan 48513, Republic of Korea
| | - Dong Won Kim
- Research Institute for Green Energy Convergence Technology, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Seung Yeup Lee
- Department of Applied Bioscience, Dong-A University, Busan 49315, Republic of Korea
| | - Dong Yun Choi
- Biomedical Manufacturing Technology Center, Korea Institute of Industrial Technology, Yeongcheon, Gyeongbuk 38822, Republic of Korea
| | - Seung Yong Choi
- Department of Industrial Chemistry, Pukyong National University, Busan 48513, Republic of Korea
| | - Kyoung-Seok Moon
- Department of Materials Engineering and Convergence Technology, School of materials Science and Engineering, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Min Young Shon
- Department of Industrial Chemistry, Pukyong National University, Busan 48513, Republic of Korea.
| | - Myung Jun Moon
- Department of Industrial Chemistry, Pukyong National University, Busan 48513, Republic of Korea.
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Kim DW, Kim KT, Lee DU, Jung SH, Yu J. Synergetic enhancement in the reactivity and stability of surface-oxide-free fine Al particles covered with a polytetrafluoroethylene nanolayer. Sci Rep 2020; 10:14560. [PMID: 32883998 PMCID: PMC7471686 DOI: 10.1038/s41598-020-71162-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 03/31/2020] [Accepted: 08/03/2020] [Indexed: 11/15/2022] Open
Abstract
Surface oxide (Al2O3) of reactive fine aluminum (Al) particles for solid fuels, propellants, and brazing materials often restricted oxidative performance, though the passivation film acts to protect Al particles from exploding. Here, we report fine Al particles fully covered with a polytetrafluoroethylene (PTFE) layer instead of an Al2O3 film on the surface. This advance is based on the introduction of strong Al–F bonds, known to be an alternative to the Al–O bonds of surface oxides. The DSC results on the PTFE-coated Al particles exhibit higher reactive-exothermic enthalpy energy (12.26 kJ g−1) than 4.85 kJ g−1 by uncoated Al particles. The artificial aging test of the PTFE layer on the Al particles show long-time stability to the external circumstance compared to those by Al2O3. The activation energy for oxidation was investigated from cyclic voltammetry assessment and the measured peak potentials of the anode curve for PTFE/Al (− 0.45 V) and uncoated Al (− 0.39 V) are achieved, respectively. This means that the PTFE layer is more stable against a sudden explosion of Al particles compared to Al2O3. These results are very useful given its capability to control both the reactivity and stability levels during the oxidation of Al particles for practical applications.
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Affiliation(s)
- Dong Won Kim
- 3D Printing Materials Research Center, Korea Institute of Materials Science, 797 Changwondaero, Seongsan-gu, Changwon, Gyeongnam, 51508, Republic of Korea
| | - Kyung Tae Kim
- 3D Printing Materials Research Center, Korea Institute of Materials Science, 797 Changwondaero, Seongsan-gu, Changwon, Gyeongnam, 51508, Republic of Korea.
| | - Dong Uk Lee
- Department of Industrial Chemistry, Pukyong National University, 45 Yongsoro, Nam-gu, Busan, 48513, Republic of Korea
| | - Soo-Ho Jung
- 3D Printing Materials Research Center, Korea Institute of Materials Science, 797 Changwondaero, Seongsan-gu, Changwon, Gyeongnam, 51508, Republic of Korea
| | - Jihun Yu
- 3D Printing Materials Research Center, Korea Institute of Materials Science, 797 Changwondaero, Seongsan-gu, Changwon, Gyeongnam, 51508, Republic of Korea
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Vu TKO, Lee DU, Kim EK. The enhancement mechanism of photo-response depending on oxygen pressure for Ga 2O 3 photo detectors. Nanotechnology 2020; 31:245201. [PMID: 32066119 DOI: 10.1088/1361-6528/ab76f5] [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: 06/10/2023]
Abstract
We have optimized the responsivity and response speed of a β-Ga2O3-based photodetector. The β-Ga2O3 thin films were deposited on a glass substrate under various oxygen partial pressures from 0 to 50 mTorr using pulsed laser deposition. Time-response measurements show that the as-grown β-Ga2O3 at an oxygen partial pressure of 50 mTorr has the fastest response speed and decay times of 33 and 100 ms, which are better than those prepared at lower oxygen pressures. This sample also showed a high photoresponsivity of 5 A W-1 and detectivity of 1012 cmHz1/2/W. The high performance of the β-Ga2O3 detector grown at the oxygen partial pressure of 50 mTorr might be due to the reduction of oxygen vacancies caused by the increase in oxygen content during deposition. The results reveal the importance of the oxygen processing gas in promoting photodetector performance.
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Won H, Lee DU, Jang G, Noh YH, Lee SC, Choi HW, Yoon IJ, Yoo HS, Lee C. Generation and protective efficacy of a cold-adapted attenuated genotype 2b porcine epidemic diarrhea virus. J Vet Sci 2019; 20:e32. [PMID: 31364317 PMCID: PMC6669205 DOI: 10.4142/jvs.2019.20.e32] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/29/2019] [Accepted: 05/13/2019] [Indexed: 11/21/2022] Open
Abstract
The recent emergence and re-emergence of porcine epidemic diarrhea virus (PEDV) underscore the urgent need for the development of novel, safe, and effective vaccines against the prevailing strain. In this study, we generated a cold-adapted live attenuated vaccine candidate (Aram-P29-CA) by short-term passage of a virulent PEDV isolate at successively lower temperatures in Vero cells. Whole genome sequencing identified 12 amino acid changes in the cold-adapted strain with no insertions and deletions throughout the genome. Animal inoculation experiments confirmed the attenuated phenotype of Aram-P29-CA virus in the natural host. Pregnant sows were orally administered P29-CA live vaccines two doses at 2-week intervals prior to parturition, and the newborn piglets were challenged with the parental virus. The oral homologous prime-boost vaccination of P29-CA significantly improved the survival rate of the piglets and notably mitigated the severity of diarrhea and PEDV fecal shedding after the challenge. Furthermore, strong antibody responses to PEDV were detected in the sera and colostrum of immunized sows and in the sera of their offspring. These results demonstrated that the cold-adapted attenuated virus can be used as a live vaccine in maternal vaccination strategies to provide durable lactogenic immunity and confer passive protection to litters against PEDV.
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Affiliation(s)
- Hokeun Won
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea.,Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Dong Uk Lee
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea
| | - Guehwan Jang
- Animal Virology Laboratory, School of Life Sciences, BK21 plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Korea
| | - Yun Hee Noh
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea
| | | | - Hwan Won Choi
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea
| | - In Joong Yoon
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea
| | - Han Sang Yoo
- Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Changhee Lee
- Animal Virology Laboratory, School of Life Sciences, BK21 plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Korea.
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Park BW, Lee DU, Jung D, Yang WS, Oanh Vu TK, Shin TJ, Baik J, Hwang CC, Kim EK, Seok SI. Long-Term Chemical Aging of Hybrid Halide Perovskites. Nano Lett 2019; 19:5604-5611. [PMID: 31306574 DOI: 10.1021/acs.nanolett.9b02142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Because the power conversion efficiency (PCE) of hybrid halide perovskite solar cells (PSCs) could exceed 24%, extensive research has been focused on improving their long-term stability for commercialization in the near future. In a previous study, we reported that the addition of a number of ionized iodide (triiodide: I3-) ions during perovskite film formation significantly improved the efficiency of PSCs by reducing deep-level defects in the perovskite layer. Understanding the relationship between the concentration of these defects and the long-term chemical aging of PSCs is important not only for obtaining fundamental insight into the perovskite materials but also for studying the long-term chemical stability of PSCs. Herein we aim to identify the origin of the natural decay in PCE during long-term chemical aging of PSCs in the dark based on formamidinium lead triiodide by comparing the performance of control and low-defect (LD) devices. After aging for 200 days, the change in the PCE of the LD devices (1.3%) was found to be half that of the control devices (2.6%). We investigated this difference using grazing incidence wide-angle X-ray scattering, deep-level transient spectroscopy, scanning photoelectron microscopy, and high-resolution photoemission spectroscopy. The addition of I3- was found to reduce the amounts of hydroxide and Ox in the halide perovskites (HPs), affecting the migration of defects and the structural transformation of the HPs.
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Affiliation(s)
- Byung-Wook Park
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology , 50 UNIST-gil, Eonyang-eup, Ulju-gun , Ulsan 44919 , Republic of Korea
| | - Dong Uk Lee
- NAND Product Engineering Group , SK hynix Inc. , Icheon 17336 , Republic of Korea
| | - Daesung Jung
- Beamline Research Division , Pohang Accelerator Laboratory , Pohang , 37673 , Republic of Korea
| | - Woon Seok Yang
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology , 50 UNIST-gil, Eonyang-eup, Ulju-gun , Ulsan 44919 , Republic of Korea
| | - Thi Kim Oanh Vu
- Department of Physics and Quantum Function Research Laboratory , Hanyang University , Seoul 04763 , Republic of Korea
| | - Tae Joo Shin
- UNIST Central Research Facilities & School of Natural Science , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil, Eonyang-eup, Ulju-gun , Ulsan 44919 , Republic of Korea
| | - Jaeyoon Baik
- Beamline Research Division , Pohang Accelerator Laboratory , Pohang , 37673 , Republic of Korea
| | - Chan-Cuk Hwang
- Beamline Research Division , Pohang Accelerator Laboratory , Pohang , 37673 , Republic of Korea
| | - Eun Kyu Kim
- Department of Physics and Quantum Function Research Laboratory , Hanyang University , Seoul 04763 , Republic of Korea
| | - Sang Il Seok
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology , 50 UNIST-gil, Eonyang-eup, Ulju-gun , Ulsan 44919 , Republic of Korea
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Yang WS, Park BW, Jung EH, Jeon NJ, Kim YC, Lee DU, Shin SS, Seo J, Kim EK, Noh JH, Seok SI. Iodide management in formamidinium-lead-halide-based perovskite layers for efficient solar cells. Science 2018; 356:1376-1379. [PMID: 28663498 DOI: 10.1126/science.aan2301] [Citation(s) in RCA: 1599] [Impact Index Per Article: 266.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/31/2017] [Indexed: 12/20/2022]
Abstract
The formation of a dense and uniform thin layer on the substrates is crucial for the fabrication of high-performance perovskite solar cells (PSCs) containing formamidinium with multiple cations and mixed halide anions. The concentration of defect states, which reduce a cell's performance by decreasing the open-circuit voltage and short-circuit current density, needs to be as low as possible. We show that the introduction of additional iodide ions into the organic cation solution, which are used to form the perovskite layers through an intramolecular exchanging process, decreases the concentration of deep-level defects. The defect-engineered thin perovskite layers enable the fabrication of PSCs with a certified power conversion efficiency of 22.1% in small cells and 19.7% in 1-square-centimeter cells.
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Affiliation(s)
- Woon Seok Yang
- Perovtronics Research Center, School of Natural Science, and School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Korea
| | - Byung-Wook Park
- Perovtronics Research Center, School of Natural Science, and School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Korea
| | - Eui Hyuk Jung
- Division of Advanced Materials, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Korea
| | - Nam Joong Jeon
- Division of Advanced Materials, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Korea
| | - Young Chan Kim
- Division of Advanced Materials, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Korea
| | - Dong Uk Lee
- NAND Product Engineering Group, SK Hynix Inc., Icheon 17336, Korea
| | - Seong Sik Shin
- Division of Advanced Materials, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Korea
| | - Jangwon Seo
- Division of Advanced Materials, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Korea
| | - Eun Kyu Kim
- Department of Physics and Quantum Function Research Laboratory, Hanyang University, Seoul 04763, Korea.
| | - Jun Hong Noh
- Division of Advanced Materials, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Korea. .,School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 136-713, Republic of Korea
| | - Sang Il Seok
- Perovtronics Research Center, School of Natural Science, and School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Korea. .,Division of Advanced Materials, Korea Research Institute of Chemical Technology, 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Korea
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Lee DU, Pak S, Lee D, Kim Y, Yang H, Hong S, Lee S, Kim EK. Reduction of interface traps between poly-Si and SiO 2 layers through the dielectric recovery effect during delayed pulse bias stress. Nanotechnology 2017; 28:225702. [PMID: 28488592 DOI: 10.1088/1361-6528/aa6a9d] [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: 06/07/2023]
Abstract
We investigate the interface trap behavior between tunneling oxide and poly-Si channel layer post erase/write cycling with a delayed pulse by using deep level transient spectroscopy. For comparison of the defect states depending on the stress pulses, a Schottky and a metal-oxide semiconductor device were fabricated. A defect state at about E c -0.51 eV in the Schottky device was measured before the annealing process. Three-hole trap states with activation energies of E v +0.28 eV, E v +0.53 eV, and E v +0.76 eV appeared after the post-annealing process. The electron trap was about E c -0.15 eV after erase/write 3000 cycling was applied at ±10 V for 100 ms at 25 °C and 85 °C. These defect states may have an effect on the charge loss behavior of the electrons localized in the charge trap layer at the retention mode of three-dimensional non-volatile memory devices. Dramatically, after the endurance stress was applied with a delayed pulse of 300 cycling at 85 °C for 50.4 h, no interface traps of the deep level transient spectroscopy spectra appeared. Dielectric recovery can decrease the density of the interface trap and improve the retention properties. This may have been caused by the passivation effect on the dangling bond of the interface traps.
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Affiliation(s)
- Dong Uk Lee
- NAND Product Engineering Group, SKhynix Inc., Icheon, 17336, Republic of Korea
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Lee DU, Kwon T, Je SH, Yoo SJ, Seo SW, Sunwoo SY, Lyoo YS. Wild boars harboring porcine epidemic diarrhea virus (PEDV) may play an important role as a PEDV reservoir. Vet Microbiol 2016; 192:90-94. [PMID: 27527769 PMCID: PMC7117357 DOI: 10.1016/j.vetmic.2016.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 07/01/2016] [Accepted: 07/06/2016] [Indexed: 02/04/2023]
Abstract
First detection of PEDV in wild boar population. PEDV positive samples were spread throughout the mainland of South Korea. Our results provide novel insight into the epidemiology of PEDV infection.
Porcine epidemic diarrhea virus (PEDV) is a burdensome pathogen in the swine industry. Wild boar population poses a high risk for reservoir of viral pathogen. Two hundred eighty seven samples from wild boar (Sus scrofa) collected in South Korea during 2010/11 were analyzed using RT-PCR, revealing a PEDV infection rate of 9.75% (28/287). PEDV positive samples were distributed throughout the mainland of South Korea, clustering at the northern border adjacent to the Demilitarized Zone (DMZ) and in mountainous regions. PEDV in wild boar was genetically similar to Chinese PEDV strains in phylogenetic investigations. Our results indicated that PEDV is circulating in the wild boar and provided a novel knowledge into epidemiology of PEDV infection.
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Affiliation(s)
- Dong Uk Lee
- Department of Immunopathology, College of Veterinary Medicine, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul, South Korea
| | - Taeyong Kwon
- Department of Immunopathology, College of Veterinary Medicine, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul, South Korea
| | - Sang H Je
- Department of Immunopathology, College of Veterinary Medicine, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul, South Korea
| | - Sung J Yoo
- Department of Immunopathology, College of Veterinary Medicine, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul, South Korea
| | - Sang Won Seo
- CTCBIO Inc., 4, Saengmyeonggwahakgwan-gil, Hongcheon-eup, Hongcheon-gun, Gangwon-do, South Korea
| | - Sun Young Sunwoo
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
| | - Young S Lyoo
- Department of Immunopathology, College of Veterinary Medicine, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul, South Korea.
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Qiu D, Lee DU, Park CS, Lee KS, Kim EK. Transport properties of unrestricted carriers in bridge-channel MoS2 field-effect transistors. Nanoscale 2015; 7:17556-17562. [PMID: 26446693 DOI: 10.1039/c5nr04397b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Unsuppressed carrier scattering from the underlying substrate in a layered two-dimensional material system is extensively observed, which degrades significantly the performance of devices. Beyond the material itself, understanding the intrinsic interfacial and surficial properties is an important issue for the analysis of a high-κ/MoS2 heterostructure. Here, we report on the electronic transport properties of bridge-channel MoS2 field-effect transistors fabricated by a contamination-free transfer method. After neglecting all the surrounding perturbations, it is possible to reveal the significant improvement of room-temperature mobility and subthreshold slope. A systematic study on variable-temperature transport measurements has quantified the trap density of states both in free-standing and SiO2-supported MoS2 systems. Compared to the bridge-channel MoS2 devices with an ideal interface, the unsuspended devices have a large amount of band tail states, and then the impact of their electronic states on the device performance is also discussed.
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Affiliation(s)
- Dongri Qiu
- Quantum-Function Research Laboratory and Department of Physics, Hanyang University, Seoul 133-791, South Korea.
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Abstract
Background Porcine bocavirus is classified within the genus Bocaparvovirus, family Parvoviridae. Unlike other parvoviruses, the members of genus Bocaparvovirus (bocaparvoviruses) encode an additional open reading frame (NP1). Many strains of PBoVs have been identified in domestic pigs and recognized as a potential emerging pathogen causing respiratory and gastrointestinal disease. Findings A new strain of porcine bocavirus (PBoV) that harbored the shortest NP1 gene among all currently characterized PBoVs (provisionally named as ‘PBoV-KU14’) was detected in domestic pigs. Almost the complete genome sequence was obtained, approximately 4,630 nucleotides in lengths with putative NS1, NP1, and VP1/2 genes of 1,908, 600, 1,851 bp, respectively. Phylogenetic and comparative analysis was performed using protein and nucleotide sequences. It was revealed that PBoV-KU14 belongs to the genus Bocaparvovirus and species Ungulate bocaparvovirus 4. However, phylogenetic incongruence was observed among species classifications based on the NS1, NP1 and VP1/2 proteins, which indicates a probability of crossover recombination. Conserved protein domains unique for genus Bocaparvovirus in NP1, VP1 protein were also detected. Conclusion NP1 gene truncation supposed to be caused by cross over recombination was detected in a new strain of PBoV (PBoV-KU14). Considering high rates of substitution and recombination in parvovirus, periodic surveillance study to monitor genomic variation and find new strainsof PBoVs seems to be needed.
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Affiliation(s)
- Sung J Yoo
- Department of Pathology, College of Veterinary Medicine, Konkuk University, 120 Neung-dong Street, Gwangjin-gu, Seoul, 143-701 South Korea
| | - Sun Young Sunwoo
- Department of Pathology, College of Veterinary Medicine, Konkuk University, 120 Neung-dong Street, Gwangjin-gu, Seoul, 143-701 South Korea ; Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506 USA
| | - Seong Sik Ko
- Department of Pathology, College of Veterinary Medicine, Konkuk University, 120 Neung-dong Street, Gwangjin-gu, Seoul, 143-701 South Korea
| | - Sang H Je
- Department of Pathology, College of Veterinary Medicine, Konkuk University, 120 Neung-dong Street, Gwangjin-gu, Seoul, 143-701 South Korea
| | - Dong Uk Lee
- Department of Pathology, College of Veterinary Medicine, Konkuk University, 120 Neung-dong Street, Gwangjin-gu, Seoul, 143-701 South Korea
| | - Young S Lyoo
- Department of Pathology, College of Veterinary Medicine, Konkuk University, 120 Neung-dong Street, Gwangjin-gu, Seoul, 143-701 South Korea
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Lee DU, Kim D, Lee KS, Kim EK. Memory effect by carrier trapping into V3Si nanocrystals among SiO2 layers on multi-layered graphene layer. J Nanosci Nanotechnol 2014; 14:8654-8658. [PMID: 25958579 DOI: 10.1166/jnn.2014.9985] [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
We report the electrical characteristics and conduction mechanism of a resistive switching memory device consisting of V3Si nanocrystals embedded in the SiO2 layer on multi-layered graphene. The V3Si nanocrystals with average size of 5 nm were formed between the SiO2 layers by thin film deposition and post-annealing process at 800 degrees C for 5 s. The current values of high (HRS) and low resistance states (LRS) at 1 V were measured to be about 3.26 x 10(-9) A and 3.11 x 10(-8) A, respectively. The ratio of the HRS and LRS after applying sweeping bias of ± 6 V appeared to be about 9.54 at 1 V. The resistance switching could originate from the effect of carrier trap and emission into the V3Si nanocrystals via the tunneling, space charge limited current, and thermionic emission mechanisms controlled by the modulation of the Fermi level of the graphene layer. The V3Si nanocrystals memory device has a strong possibility for the application of nonvolatile memory devices.
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Pak SW, Cho SG, Lee DU, Kim EK. Thermal annealing effects on ZnO films grown on graphene buffered Si substrates. J Nanosci Nanotechnol 2014; 14:8804-8807. [PMID: 25958607 DOI: 10.1166/jnn.2014.9986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
ZnO films deposited on SiO2/Si substrate with a graphene single layer (GSL) were studied by using an ultra-high vacuum sputter. The as-prepared films were annealed at temperature ranges from 500 degrees C to 800 degrees C for 1 min under ambient N2 gas. When the annealing temperature was increased up to 800 degrees C, the root mean square roughness of the ZnO/Si sample surface decreased down to 3.4 nm, and the grain sizes increased about 50.8 nm with a clear grain boundary. From the photoluminescence (PL) spectra, the high intensity of near-band-edge UV emission at 380 nm (3.26 eV) and the broad band emission between 450 and 650 nm, known as the visible defect related PL band, decreased with increasing annealing temperature up to 800 degrees C. The ZnO thin films on the growth on the GSL and post-annealing at 700 degrees C for 1 min under ambient N2 gas had the best structural and optical properties.
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Lee KS, Kim SP, Lee DU, Kim EK. Emission enhancement of InGaN/GaN light emitting diode by using Ag nanoparticles. J Nanosci Nanotechnol 2014; 14:7830-7834. [PMID: 25942875 DOI: 10.1166/jnn.2014.9395] [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
We have studied the effect of surface plasmon (SP) coupling to enhance emission efficiency of light emitting diode (LED) with multiple quantum wells (MQWs) structure by positioning Ag nanoparticles on the line-arrayed patterns. The line-arrayed patterns were fabricated by photolithography and inductively coupled plasma reactive ion etching process. The Ag nanoparticles were formed by thermal annealing at 300 degrees C and 400 degrees C for 30 min for Ag films with thickness of 10 nm and 15 nm deposited on the patterned LED structures, respectively. The photoluminescence (PL) emission intensity of line-patterned LED with Ag nanoparticles was overall enhanced. According to the spectra of time resolved PL, carrier life times of line-patterned LED with and without Ag nanoparticles appeared about 0.47 and 5.47 ns, respectively.
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Lee DU, Yong DK, Lee HK, Choi SJ, Yoo JJ, Lee HI, Kim SH, Lee KY, Lee SG. Study on the Morphology of the PC/ABS Blend by High Shear Rate Processing. Korean Chemical Engineering Research 2014. [DOI: 10.9713/kcer.2014.52.3.382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Cho SG, Lee DU, Kim EK. Electrical and optical characteristics of n-Zno/p-GaN hetero-junction diode fabricated by ultra-high vacuum sputter. J Nanosci Nanotechnol 2013; 13:6443-6446. [PMID: 24205679 DOI: 10.1166/jnn.2013.7619] [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: 06/02/2023]
Abstract
We investigated the electrical and optical properties of n-ZnO/p-GaN hetero-junction diode fabricated by an ultra-high vacuum radio frequency magnetron sputter. A physical relationship between the rotation rate during deposition process and post annealing conditions after deposited ZnO layer on p-GaN layer was discussed. When the rotation rates during deposition process of n-ZnO layer were 5 rpm and 15 rpm, the full width at half maximum of photoluminescence spectra of ZnO layer on the p-GaN layer was about 106 and 133 meV, respectively. Also, the ratio of deep level emission to near band edge emission was dramatically increased as increasing the rotation rate from 5 to 15 rpm. The n-ZnO/p-GaN hetero-junction diode grown at 5 rpm has a higher ratio of forward to reverse currents than the diode grown at 15 rpm. Also, the 600 degrees C-annealed diodes with 5 rpm showed good rectifying behavior with the barrier height of 0.74 eV, the ideality factor of 12.2, and the forward to reverse current ratio of 614 at +/- 8 V.
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Affiliation(s)
- Seong Gook Cho
- Quantum-Function Research Laboratory and Department of Physics, Hanyang University, Seoul 133-791, Republic of Korea
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Lee DU, Kim SP, Kim EK, Cho WJ, Kim YH, Im H. Resistive-switching memory effect of hybrid structures with polyimide and SnO2 nanocrystals. J Nanosci Nanotechnol 2012; 12:5449-5452. [PMID: 22966588 DOI: 10.1166/jnn.2012.6235] [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: 06/01/2023]
Abstract
Hybrid memory devices with polyimide and SnO2 nanocrystals on a flexible polyethersulphone substrate have shown a memristor behavior from current-voltage (I-V) measurements. The resistive-switching effects with a current bistability appeared during cycling voltage sweeping within the range of +/- 4 V. This I-V switching effect might have originated from a resistance fluctuation due to the charge trapping into the SnO2 nanocrystals as well as the oxygen vacancies of the ZnO layer and aluminum oxides that were formed between the polyimide and the interface of the Al gate electrode. In the bipolar resistance-switching behavior, the ratio of the high- and low-resistance state currents was about 3.7 x 10(4) at 1 V.
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Affiliation(s)
- Dong Uk Lee
- Department of Physics and Research Institute for Natural Science, Hanyang University, Seoul 133-791, Republic of Korea
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You JH, Kim DH, Lee DU, Yoo KH, Park CY, Park KW, Jang SJ, Lee YT, Kim TW. Effect of temperature on optical and electronic properties of InGaP/InGaAIP multiple quantum wells. J Nanosci Nanotechnol 2012; 12:5843-5846. [PMID: 22966667 DOI: 10.1166/jnn.2012.6246] [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: 06/01/2023]
Abstract
The optical and electronic properties in an InGaP/InGaAIP multiple quantum well (MQW) grown by using molecular-beam epitaxy utilizing the digital alloy technique were investigated through temperature-dependent photoluminescence (PL) measurements and numerical calculations. The high-resolution transmission electron microscopy images showed that the sample clearly displayed the InGaP wells and the InGaAIP barriers and separate confinement heterostructure layers. The PL measurements at various temperatures were performed to investigate the interband transitions of the InGaP/InGaAIP MQW. The electronic subband energies and the wavefunctions in the InGaP/InGaAIP MQW at several temperatures were determined by using a finite element method employing the standard 8-band k x p Lagrangian. The numerical results for optical interband transition energies from the ground state electron subband to the ground state heavy-hole subband of the InGaP/InGaAIP MQW at various temperatures were in reasonable agreement with the excitonic transition energies observed in the PL measurements.
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Affiliation(s)
- J H You
- Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791, Korea
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Lee DU, Kim SP, Han DS, Lee HJ, Kim EK, You HW, Cho WJ. Thermal stability of metal-silicide nanocrystal nonvolatile memory with barrier engineered tunnel layers. J Nanosci Nanotechnol 2011; 11:9181-9184. [PMID: 22400320 DOI: 10.1166/jnn.2011.4302] [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: 05/31/2023]
Abstract
WSi2 nanocrystal nonvolatile memory devices were fabricated with a silicon oxide-nitride-oxide (SiO2: 2 nm/Si3N4:2 nm/SiO2:3 nm) tunnel layer. WSi2 nanocrystals of 2.5 nm diameters and a density of 3.6 x 10(12) cm(-2) were formed using radio frequency magnetron sputtering and annealing processes. The WSi2 nanocrystal nonvolatile memory device exhibited strong thermal stability during writing/erasing operations at temperatures up to 125 degrees C. When the writing/erasing voltages were applied at +10 V/-10 V for 500 ms, the memory window of the initial approximately 2.6 V decreased by approximately 1.1 V at 25 degrees C and 0.4 V at 125 degrees C after 10(4) sec, respectively. These results show that WSi2 nanocrystals with barrier-engineered tunnel layers are possible for application in nonvolatile memory devices.
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Affiliation(s)
- Dong Uk Lee
- Quantum-Function Research Laboratory and Department of Physics, Hanyang University, Seoul 133-791, Korea
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Han DS, Lee DU, Lee HJ, Kim EK, You HW, Cho WJ. Nonvolatile-memory characteristics of SiC nanocrystals with variable oxide thickness and crested tunnel barriers. J Nanosci Nanotechnol 2011; 11:5883-5886. [PMID: 22121625 DOI: 10.1166/jnn.2011.4330] [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: 05/31/2023]
Abstract
The electrical characteristics of SiC nanocrystal nonvolatile-memory devices with variable oxide and crested tunnel barriers consisting of a SiO2/Si3N4/SiO2 (ONO) and a Si3N4/SiO2/Si3N4 (NON) layer, respectively, were investigated. The equivalent oxide thickness of the ONO and NON tunnel barriers were about 5.6 nm and 5.2 nm, respectively. When the +/- 13 V bias voltage was applied for 500 ms, the threshold voltage shifts of the SiC-nanocrystal-embedded memory devices with ONO and NON tunnel barriers were about 2.4 V. The operation speeds of the memories with ONO and NON tunnel barriers under the +/- 10 V applied pulse bias were approximately 5 and 20 ms, respectively. The field sensitivity of the ONO tunnel barrier was higher than that of the NON tunnel barrier during electron injection. The tunneling efficiency during the programming/erasing processes could be improved by the engineered tunnel barrier layer. Therefore, the SiC-nanocrystal-embedded memory device with an ONO tunnel barrier can be applied to nonvolatile-memory devices.
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Affiliation(s)
- Dong Seok Han
- Department of Physics and Research Institute for Natural Scieneces, Hanyang University, Seoul 133-791, Korea
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Lee DU, Kim SP, Han DS, Kim EK, Park GH, Cho WJ, Kim YH. In2O3 nanocrystal memory with the barrier engineered tunnel layer. J Nanosci Nanotechnol 2011; 11:437-440. [PMID: 21446471 DOI: 10.1166/jnn.2011.3164] [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: 05/30/2023]
Abstract
In2O3 nanocrystal memories with barrier-engineered tunnel layers were fabricated on a p-type Si substrate. The structure and thickness of the barrier-engineered tunnel layers were SiO2/Si3N4/SiO2 (ONO) and 2/2/3 nm, respectively. The equivalent oxide thickness of the ONO tunnel layers was 5.64 nm. The average size and density of the In2O3 nanocrystals after the reaction between BPDA-PDA polyimide and the In thin film were about 8 nm and 4 x 10(11) cm(-2), respectively. The electrons were charged from the channel of the memory device to the quantum well of the In2O3 nanocrystal through the ONO tunnel layer via Fowler-Nordheim tunneling. The memory window was about 1.4 V when the program and erase conditions of the In2O3 nanocrystal memory device were 12 V for 1 s and -15 V for 200 ms.
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Affiliation(s)
- Dong Uk Lee
- Quantum-Function Spinics Laboratory and Department of Physics, Hanyang University, Seoul 133-791, Korea
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Seo KB, Lee DU, Han SJ, Kim SP, Kim EK. Nonvolatile memory characteristics of WSi2 nanocrystals embedded in SiO2 dielectrics. J Nanosci Nanotechnol 2011; 11:441-444. [PMID: 21446472 DOI: 10.1166/jnn.2011.3165] [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: 05/30/2023]
Abstract
A nano-floating gate capacitor with WSi2 nanocrystals embedded in SiO2 dielectrics was fabricated. The WSi2 nanocrystals were created from ultrathin WSi2 film during rapid thermal annealing process and their average size and density were about 2.5 nm and 3.59 x 10(12) cm(-2), respectively. The flat-band voltage shift due to the carrier charging effect of WSi2 nanocrystals were measured up to 5.9 V when the gate voltage sweep in the range of +/- 9 V. The memory window was decreased from 3.7 V to 1.9 V after 1 h and remained about 3.7 V after 10(5) programming/erasing cycles. These results show that there is a possibility for the WSi2 nanocrystals to be applied to nonvolatile memory devices.
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Affiliation(s)
- Ki Bong Seo
- Quantum-Function Spinics Laboratory and Department of Physics, Hanyang University, Seoul 133-791, Korea
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Shin JW, Lee JY, Lee DU, Oh DH, Kim DH, Kim TW, Cho WJ, Jin S. Irradiation-induced shrinkage and expansion mechanisms of SiO2 circle membrane nanopores. Nanotechnology 2009; 20:075703. [PMID: 19417431 DOI: 10.1088/0957-4484/20/7/075703] [Citation(s) in RCA: 3] [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: 05/27/2023]
Abstract
20 nm diameter SiO(2) nanopore arrays on gradient-thickness membranes were formed by a focused electron beam with in situ transmission electron microscopy (TEM). Nanopore shrinkage was seen in nanopores on thicker membranes, with the rate of diameter change remaining constant during the shrinkage process. In contrast, pore expansion was observed in thinner membranes, with the expansion rate being constant at the initial stage but with a slight increase at the later stage. The geometry model of shrinkage and expansion of the nanopores in relation to the electron irradiation time was investigated by utilizing the TEM tilting method.
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Affiliation(s)
- J W Shin
- Department of Materials Science and Engineering, KAIST, Daejeon, Korea
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Lee DU, Woo SH, Svoronos S, Park SJ, Koopman B. Apparatus and method for achieving reproducible measurements of diauxic lag length and anoxic net maximum specific growth rate. Environ Technol 2008; 29:731-738. [PMID: 18697514 DOI: 10.1080/09593330801987228] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An apparatus for continuous growth of pure bacterial cultures under oxic conditions followed by a switch to anoxic batch conditions was designed. The application of this apparatus gave variability of measured parameters (diauxic lag length, anoxic net maximum specific growth rate) which were significantly lower than the variability of previously reported data. The improvement is attributed to more consistent nitrate reductase levels as a result of achieving steady state under oxic condition prior to switching to anoxic batch conditions.
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Affiliation(s)
- D U Lee
- Jones Edmunds, 730 NE Waldo Rd, Gainesville, FL 32641, USA
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29
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Kim JH, Lee DU, Park SC, Kim MJ, Lee DJ, Lee SH. A case of malignant Brenner tumor developed at an ovary after contralateral oophorectomy. ACTA ACUST UNITED AC 2007. [DOI: 10.3802/kjgo.2007.18.2.150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jin Hee Kim
- Department of Obstetrics and Gynecology, Yeungnam University School of Medicine, Daegu, Korea
| | - Dong Uk Lee
- Department of Obstetrics and Gynecology, Yeungnam University School of Medicine, Daegu, Korea
| | - Sung Chul Park
- Department of Obstetrics and Gynecology, Yeungnam University School of Medicine, Daegu, Korea
| | - Mi Jin Kim
- Department of Obstetrics and Gynecology, Yeungnam University School of Medicine, Daegu, Korea
| | - Doo Jin Lee
- Department of Obstetrics and Gynecology, Yeungnam University School of Medicine, Daegu, Korea
| | - Sung Ho Lee
- Department of Obstetrics and Gynecology, Yeungnam University School of Medicine, Daegu, Korea
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Iwasa K, Kuribayashi A, Sugiura M, Nishiyama Y, Ichimaru M, Moriyasu M, Lee DU. Bioconversion studies in cultured cells of Corydalis species. Pharmazie 2004; 59:480-3. [PMID: 15248465] [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] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Structural analysis of the metabolites of dopamine and salsolinol in cultured cells of Corydalis species was carried out using the combination of LC-MS and LC-NMR techniques. Metabolic pathways were clarified without the need to isolate the individual metabolites.
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Affiliation(s)
- K Iwasa
- Kobe Pharmaceutical University, Kobe, Japan.
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31
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Dziurla MA, Leroy P, Strünkmann GW, Salhi M, Lee DU, Camacho P, Heinz V, Müller JA, Paul E, Ginestet P, Audic JM, Block JC. Measurement of glutathione in activated sludges. Water Res 2004; 38:236-244. [PMID: 14630122 DOI: 10.1016/j.watres.2003.08.028] [Citation(s) in RCA: 4] [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] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Thermal, electric, mechanical or oxidative stress seem a promising way to reduce the production of excess activated sludge during biological wastewater treatment. However, the adaptation and the resistance of the sludge microbial ecosystem to stress conditions is a major question as it may definitively limit the effect of some treatments. Defence mechanisms developed by aerobic organisms, in particular, in response to oxidative stress involve various antioxidant activities and compounds such as glutathione. An HPLC method was developed for measuring reduced and total glutathione (GSH and GSHt) in perchloric acid sludge extracts. The method was sensitive, highly specific and validated for linearity, precision and recovery. Considering the extraction yield and the oxidation of GSH during extract storage, the measured GSH concentration was estimated to represent 60% of the GSH content from activated sludges. GSHt ranged from 0.32 to 3.34micromolg(-1) volatile solids and the GSH/GSHt ratio ranged from 32% to 91%. Measurements performed on sludges stressed in precise conditions selected to reach a reduction of sludge production showed a decrease of GSH and GSHt concentrations with thermal, mechanical, electric and ozone stress.
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Affiliation(s)
- M A Dziurla
- Laboratoire de Chimie, Physique et Microbiologie pour l'Environnement-LCPME, Unité Mixte de Recherche-UMR 7564, CNRS-Université Henri Poincaré, Nancy 1, Faculté de Pharmacie-Pôle de l'eau, 15, avenue du Charmois, 54500 Vandoeurve-les-Nancy, France
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Lee DU, Casasús-Zambrana A, Hamilton R, Svoronos S, Lee SI, Koopman B. Significance of denitrifying enzyme dynamics in biological nitrogen removal processes: a simulation study. Water Sci Technol 2004; 49:265-272. [PMID: 15137433] [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] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Activated Sludge Model No. 1 (ASM1) was extended to include the enzyme kinetics of denitrifying bacteria switching between oxygen and nitrate as electron acceptors. The extended ASM1 (eASM1) model was applied to two different periodic process configurations, fed-batch and Biodenipho, commonly used for nitrogen removal from wastewater. Predictions of optimal unaerated volume fraction (UVF) by eASM1 were similar to those by ASM1 for both the fed-batch and Biodenipho processes. However, eASM1 predicted substantially longer optimal cycle lengths than ASM1 for both processes. Predictions of optimal UVF and cycle length for the Biodenipho process by eASM1 were closer to current operational values for the University of Florida Biodenipho process than predictions by ASM1.
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Affiliation(s)
- D U Lee
- Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611, USA.
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Affiliation(s)
- Tae Rim Shin
- Department of Internal Medicine, Catholic University of Daegu, Daegu, Korea
| | - Dong Uk Lee
- Department of Physiology, Catholic University of Daegu, Daegu, Korea
| | - Yoon-Yub Park
- Department of Physiology, Catholic University of Daegu, Daegu, Korea
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Ha JH, Shin SM, Lee SK, Kim JS, Shin US, Huh K, Kim JA, Yong CS, Lee NJ, Lee DU. In vitro effects of hydroxybenzaldehydes from Gastrodia elata and their analogues on GABAergic neurotransmission, and a structure-activity correlation. Planta Med 2001; 67:877-880. [PMID: 11745032 DOI: 10.1055/s-2001-18844] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The present study was designed to characterize the modulatory effects of the constituents of Gastrodia elata and their analogues on the GABAergic neurotransmission. 4-Hydroxybenzaldehyde (1) and 4-hydroxy-3-methoxybenzaldehyde (4) inhibited potently the activity of GABA transaminase (IC(50) = 4.1 and 5.4 microg/ml, respectively), while the activity of another constituent, 4-hydroxybenzyl alcohol (2), was very weak. Further investigation with 10 analogues revealed a structure-activity correlation, suggesting that the aldehyde group and the hydroxy group at C-4 are necessary for the inhibitory effect on the enzyme activity. Some potent enzyme inhibitors were examined for the effect on the radioligands to the GABA(A) receptor complexes of rat cerebral cortices. Among them, the component 4 dose-dependently increased (20 - 30 %) the binding of [(3)H]flunitrazepam in the presence of GABA.
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Abstract
Kinetic studies on the isothermal high hydrostatic pressure (HHP) inactivation of Escherichia coli in liquid whole egg (LWE) were performed at 5 and 25 degrees C in the pressure range of 250-400 MPa. The characteristic tailing inactivation curves were described by a first-order biphasic model. As compared to a previous rheological study, it is suggested that the phase change of LWE during pressure treatment affects the inactivation rate of E. coli. Within the processing criteria where the rheological properties of LWE were still comparable to those of fresh LWE, HHP treatments at 5 degrees C induced more E. coli inactivations than those at 25 degrees C. From the results of approximately 3 log reductions of E. coli and over 5 log reductions of Pseudomonas and Paenibacillus, HHP treatment of LWE at 5 degrees C is regarded to be as effective as conventional thermal pasteurization. However, no post-process contamination and the consistency of temperature during preparation, HHP treatment, and storage provide clear processing advantages.
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Affiliation(s)
- D U Lee
- Department of Food Biotechnology and Food Process Engineering, Berlin University of Technology, Königin-Luise-Strasse 22, D-14195 Berlin, Germany
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Abstract
In vitro cytotoxic activities of 24 quaternary protoberberine alkaloids related to berberine have been evaluated using a human cancer cell line panel coupled with a drug sensitivity database. Extending the alkyl chain at position 8 or 13 strongly influenced the cytotoxic activity, that is, relative lipophilicity as well as the size of the substituent affects cytotoxicity. The highest level of activity was observed in 8- or 13-hexyl-substituted derivatives of berberine. Structure-activity relationships are described.
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Affiliation(s)
- K Iwasa
- Kobe Pharmaceutical University, 4-19-1 Motoyamakita, Higashinada-ku, Kobe 658-8558, Japan.
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Abstract
Acori graminei Rhizoma (AGR) is shown to exhibit a number of pharmacological actions including sedation and anticonvulsive action. To further characterize its actions in the CNS, the present study evaluated the effects of essential oils (EO) from AGR on the excitotoxic neuronal cell death induced in primary rat cortical cell cultures. EO inhibited the glutamate-induced excitotoxicity in a concentration-dependent manner, with the IC50 of 0.241 mg/ml. EO exerted more potent neuroprotection against the toxicity induced by NMDA (IC50 = 0.139 mg/ml). In contrast, the AMPA-induced toxicity was not inhibited by EO. Receptor-ligand binding studies were performed to investigate the neuroprotective action mechanism. EO dramatically inhibited the specific bindings of a use-dependent NMDA receptorion channel blocker [3H]MK-801, indicating an NMDA receptor antagonist-like action. However, the bindings of [3H]MDL 105,519, a ligand selective for the glycine binding site of NMDA receptor, were not considerably inhibited. These results demonstrated that EO extracted from AGR exhibited neuroprotective effects on cultured cortical neurons through the blockade of NMDA receptor activity, and that the glycine binding site appeared not to be the major site of action.
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Affiliation(s)
- J Cho
- Department of Pharmacology, College of Medicine, Dongguk University, Kyongju, Kyongbuk, Korea.
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Ha JH, Lee DU, Lee JT, Kim JS, Yong CS, Kim JA, Ha JS, Huh K. 4-Hydroxybenzaldehyde from Gastrodia elata B1. is active in the antioxidation and GABAergic neuromodulation of the rat brain. J Ethnopharmacol 2000; 73:329-333. [PMID: 11025174 DOI: 10.1016/s0378-8741(00)00313-5] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ether fraction of G. elata methanol extract significantly inhibited the recovery time and severity induced by pentylenetetrazole (PTZ) treatment. Pretreatment of ether fraction of G. elata methanol extract successfully prevented diminution of brain GABA level in subconvulsive dose of PTZ-treated rats. 4-Hydroxybenzaldehyde, an analogue of p-hydroxybenzyl alcohol, showed an inhibitory effect on the GABA transaminase, and its inhibitory activity was higher than that of valproic acid, a known anticonvulsant. In the brain of PTZ-treated rats, brain lipid peroxidation was significantly increased, while it recovered to the control level after treatment with 4-hydroxybenzaldehyde. It may be concluded that antioxidation and positive modulation of GABAergic neuromodulation of 4-hydroxybenzaldehyde partially contribute to an antiepileptic and anticonvulsive activity of G. elata B1.
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Affiliation(s)
- J H Ha
- Department of Pharmacology, College of Medicine, Yeungnam University, 705-717, Taegu, South Korea.
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Han YH, Ham JH, Lee NJ, Park CH, Shin YH, Lee DU. Antimutagenic activity of 5alpha-cholest-7-en-3beta-ol, a new component from the starfish asterina pectinifera. Biol Pharm Bull 2000; 23:1247-9. [PMID: 11041261 DOI: 10.1248/bpb.23.1247] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [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: 11/22/2022]
Abstract
From the butanol fraction of the starfish Asterina pectinifera Müler et Troschel (Asteriidae), we have isolated a new component, 5alpha-cholest-7-en-3beta-ol. Its antigenotoxic and antimutagenic activities were examined by the SOS chromotest with Escherichia coli PQ37 and by Ames test with Salmonella typhimurium TA1538, respectively. 5alpha-Cholest-7-en-3beta-ol showed potent antigenotoxic activity against the mutagens, both MNNG and NQO. For 100% of antigenotoxicity, the concentration of the compound applied against MNNG and NQO were 10 microg and 5 microg per reaction tube, respectively. Its antimutagenic activity with S. typhimurium TA1538 against the mutagen MNNG was very effective. When its concentrations were varied from 1 up to 10 microg dose per plate, the inhibition ratio of revertant CFU of TA1538 per plate was increased accordingly, from 25.2 to 99.2%. These results suggest that 5alpha-cholest-7-en-3beta-ol possesses antigenotoxic and antimutagenic activity and might be useful as a chemopreventive agent.
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Affiliation(s)
- Y H Han
- Department of Biology, Dongguk University, Kyongju, Kyongbuk, Republic of Korea
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Lee DU, Kang SI, Yoon SH, Budesinsky M, Kasal A, Mayer KK, Wiegrebe W. A new steroidal alkaloid from the roots of Cynanchum caudatum. Planta Med 2000; 66:480-482. [PMID: 10909275 DOI: 10.1055/s-2000-8578] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A new steroidal alkaloid, 12-O-nicotinoylsarcostin, gagamine (1), was isolated from the roots of Cynanchum caudatum Max. (Asclepiadaceae), together with a known alkaloid, gagaminine (2). Their structures were established using spectroscopic methods, some 13C-NMR data of 2 have to be revised.
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Lee YS, Ha JH, Yong CS, Lee DU, Huh K, Kang YS, Lee SH, Jung MW, Kim JA. Inhibitory effects of constituents of Gastrodia elata Bl. on glutamate-induced apoptosis in IMR-32 human neuroblastoma cells. Arch Pharm Res 1999; 22:404-9. [PMID: 10489882 DOI: 10.1007/bf02979066] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [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: 10/21/2022]
Abstract
The inhibitory effects of the constituents of Gastrodia elata Bl. (GE) on glutamate-induced apoptosis in human neuronal cells were investigated using IMR32 human neuroblastoma cells. Glutamate (GLU) induced DNA fragmentation, a hallmark of apoptosis, in a dose-dependent manner. GLU also induced a slow and sustained increase in intracellular Ca2+ concentration. Treatment with EGTA, an extracellular Ca2+ chelator, in a nominal Ca2+-free buffer solution abolished the GLU-induced intracellular Ca2+ increase, indicating that GLU stimulated Ca2+ influx pathway in the IMR32 cells. BAPTA, an intracellular Ca2+ chelator, significantly inhibited the GLU-induced apoptosis assessed by the flow cytometry measuring hypodiploid DNA content indicative of apoptosis, implying that intracellular Ca2+ rise may mediate the apoptotic action of GLU. Vanillin (VAN) and p-hydroxybenzaldehyde (p-HB), known constituents of GE, significantly inhibited both intracellular Ca2+ rise and apoptosis induced by GLU. These results suggest that the apoptosis-inhibitory actions of the constituents of GE may account, at least in part, for the basis of their antiepileptic activities. These results further suggest that intracellular Ca2+ signaling pathway may be a molecular target of the constituents of GE.
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Affiliation(s)
- Y S Lee
- Department of Physiology, College of Medicine, Kwandong University, Kangnung, Korea
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Abstract
13-Alkyl derivatives (2-6 and 8-12) of berberine (1) and palmatine (7) were subjected to in vitro antibacterial activity tests against Bacillus subtilis and Salmonella enteritidis. Antibacterial activity increased as the length of the C-13 aliphatic side chain increased. The effects of the oxygen-substituents on aromatic rings A, C, and D of protoberberinium salts 13-20 on the antimicrobial activity against Staphylococcus aureus, B. subtilis, S. enteritidis, Escherichia coli, and Candida albicans are also discussed. The change in lipophilicity of the protoberberinium salts caused by modification of the substituents appears to influence the antibacterial activity. 13-Hexylberberine (6) and 13-hexylpalmatine (12) exhibited the greatest antibacterial activity.
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Iwasa K, Lee DU, Kang SI, Wiegrebe W. Antimicrobial activity of 8-alkyl- and 8-phenyl-substituted berberines and their 12-bromo derivatives. J Nat Prod 1998; 61:1150-1153. [PMID: 9748388 DOI: 10.1021/np980044+] [Citation(s) in RCA: 60] [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: 05/22/2023]
Abstract
The 8-alkyl- (3-6), 8-phenyl- (7), 12-bromo- (8), 8-alkyl-12-bromo- (9-12), and 12-bromo-8-phenyl- (13) berberine derivatives were prepared and tested for their antimicrobial activity in vitro to evaluate structure-activity relationships. Introduction of the alkyl or phenyl group and the bromine atom into the C-8 and C-12 positions of berberine (1), respectively, led to significant increases of the antimicrobial activity. In both the 8-alkyl- and 8-alkyl-12-bromo-berberines (3-6 and 9-12, respectively), the antibacterial activity increased as the length of the aliphatic chain increased. The exception was the activity against Candida albicans and Escherichia coli, which did not always increase as the alkyl side chain lengthened. Among the compounds tested, 12-bromo-8-n-hexylberberine (12) was 64, 256, 128, 16, and 32 times more active against Staphylococcus aureus, Bacillus subtilis, Salmonella enteritidis, E. coli, and C. albicans, respectively, in comparison to the clinically used berberine. Compound 12 was also found to be 8, 16, and 128 times more active against S. aureus, S. enteritidis, and C.albicans, respectively, than kanamycin sulfate, but was of the same order of activity against B. subtilis, and only one-fourth as active against E. coli.
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Affiliation(s)
- K Iwasa
- Kobe Pharmaceutical University, 4-19-1 Motoyamakita, Higashinada-ku, Kobe 658-8558, Japan.
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Lee DU, Shin US, Huh K. Structure-activity relationships of gagaminine and its derivatives on the inhibition of hepatic aldehyde oxidase activity and lipid peroxidation. Arch Pharm Res 1998; 21:273-7. [PMID: 9875443 DOI: 10.1007/bf02975287] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 10/21/2022]
Abstract
In order to determine the structure-activity relationships for antioxidative effects of gagaminine, a steroidal alkaloid isolated from the roots of Cynanchum wilfordi (Asclepiadaceae), two derivatives identified as sarcostin and penupogenin were prepared from gagaminine by hydrolysis and reduction. These compounds were evaluated for the inhibitory effects on the aldehyde oxidase activity and on lipid peroxidation in vitro. Furthermore, their effects were compared with those of gagaminine and the related compounds, cinnamic acid and nicotinic acid. The results of this study prove that the cinnamoyl group in the structure of gagaminine is critical in inhibition of the aldehyde oxidase activity while the nicotinoyl group may be necessary for anti-lipid peroxidation of the compound.
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Affiliation(s)
- D U Lee
- Department of Biochemistry, College of Natural Science, Dongguk University, Kyongju, Korea
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Lee DU, Shin US, Huh K. Inhibitory effects of gagaminine, a steroidal alkaloid from Cynanchum wilfordi, on lipid peroxidation and aldehyde oxidase activity. Planta Med 1996; 62:485-7. [PMID: 17252491 DOI: 10.1055/s-2006-957953] [Citation(s) in RCA: 9] [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: 05/13/2023]
Abstract
Gagaminine, a steroidal alkaloid, was isolated for the first time from the root of Cynanchum wilfordi Hemsley (Asclepiadaceae), and its effects on lipid peroxidation and the activity of aldehyde oxidase (EC. 1.2.3.1) were investigated in vitro. This alkaloid suppressed significantly the formation of lipid peroxides in rat liver tissues and potently inhibited the hepatic aldehyde oxidase activity in a dose-dependent manner, with IC50 value of 0.8 microM (0.5 microg/ml). These results indicate that gagaminine is a potent natural antioxidant and may be useful for clinical tests.
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Affiliation(s)
- D U Lee
- Department of Biochemistry, Dongguk University, Kyongju, Kyongbuk 780-714, Korea
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Lee DU, Horikawa K, Arata Y. Quantitative assessment of root shape on fatigue strength of welded joint with backing strip. ACTA ACUST UNITED AC 1988. [DOI: 10.2207/qjjws.6.158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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