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Juraeva M, Kang DJ. Mixing Enhancement of a Passive Micromixer with Submerged Structures. Micromachines 2022; 13:mi13071050. [PMID: 35888870 PMCID: PMC9317626 DOI: 10.3390/mi13071050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 06/24/2022] [Accepted: 06/28/2022] [Indexed: 11/26/2022]
Abstract
A passive micromixer combined with two different mixing units was designed by submerging planar structures, and its mixing performance was simulated over a wider range of the Reynolds numbers from 0.1 to 80. The two submerged structures are a Norman window and rectangular baffles. The mixing performance was evaluated in terms of the degree of mixing (DOM) at the outlet and the required pressure load between inlet and outlet. The amount of submergence was varied from 30 μm to 70 μm, corresponding to 25% to 58% of the micromixer depth. The enhancement of mixing performance is noticeable over a wide range of the Reynolds numbers. When the Reynolds number is 10, the DOM is improved by 182% from that of no submergence case, and the required pressure load is reduced by 44%. The amount of submergence is shown to be optimized in terms of the DOM, and the optimum value is about 40 μm. This corresponds to a third of the micromixer depth. The effects of the submerged structure are most significant in the mixing regime of convection dominance from Re = 5 to 80. In a circular passage along the Norman window, one of the two Dean vortices burst into the submerged space, promoting mixing in the cross-flow direction. The submerged baffles in the semi-circular mixing units generate a vortex behind the baffles that contributes to the mixing enhancement as well as reducing the required pressure load.
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Escudero A, González-García L, Strahl R, Kang DJ, Drzic J, Kraus T. Correction to Large-Scale Synthesis of Hybrid Conductive Polymer-Gold Nanoparticles Using "Sacrificial" Weakly Binding Ligands for Printing Electronics. Inorg Chem 2022; 61:3361. [PMID: 35119846 DOI: 10.1021/acs.inorgchem.2c00179] [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: 11/29/2022]
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Escudero A, González-García L, Strahl R, Kang DJ, Drzic J, Kraus T. Large-Scale Synthesis of Hybrid Conductive Polymer-Gold Nanoparticles Using "Sacrificial" Weakly Binding Ligands for Printing Electronics. Inorg Chem 2021; 60:17103-17113. [PMID: 34735769 DOI: 10.1021/acs.inorgchem.1c02350] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We describe the gram-scale synthesis of hybrid gold nanoparticles with a shell of conductive polymers. A large-scale synthesis of hexadecyltrimethylammonium bromide (CTAB)-capped gold nanoparticles (AuNP@CTAB) was followed by ligand exchange with conductive polymers based on thiophene in a 10 L reactor equipped with a jacket to ensure a constant temperature of 40 °C and a mechanical stirrer. Slow and controlled reduction of the gold precursors and the presence of small amounts of silver nitrate are revealed to be the critical synthesis variables to obtain particles with a sufficiently narrow size distribution. Batches of approximately 10 g of faceted AuNP@CTAB with tunable average particle sizes from 54 to 85 nm were obtained per batch. Ligand exchange with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) in the same reactor then yielded hybrid Au@PEDOT:PSS nanoparticles. They were used to formulate sinter-free inks for the inkjet printing of conductive structures without the need for a sintering step.
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Affiliation(s)
- Alberto Escudero
- INM─Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.,Departamento de Química Inorgánica and Instituto de Investigaciones Químicas (IIQ), Universidad de Sevilla─CSIC, Calle Américo Vespucio 49, 41092 Seville, Spain
| | - Lola González-García
- INM─Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Robert Strahl
- INM─Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Dong Jin Kang
- INM─Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Juraj Drzic
- INM─Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Tobias Kraus
- INM─Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.,Colloid and Interface Chemistry, Saarland University, 66123 Saarbrücken, Germany
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Oh JH, Park SJ, Kang DJ, Kang YK, Shin JP, Park DH. Short-term Changes in Ocular Surface pH after 23-gauge Microincision Vitrectomy Surgery. J Korean Ophthalmol Soc 2021. [DOI: 10.3341/jkos.2021.62.2.216] [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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Juraeva M, Kang DJ. Mixing Performance of a Cross-Channel Split-and-Recombine Micro-Mixer Combined with Mixing Cell. Micromachines (Basel) 2020; 11:E685. [PMID: 32679732 PMCID: PMC7407565 DOI: 10.3390/mi11070685] [Citation(s) in RCA: 10] [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] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 11/17/2022]
Abstract
A new cross-channel split-and-recombine (CC-SAR) micro-mixer was proposed, and its performance was demonstrated numerically. A numerical study was carried out over a wide range of volume flow rates from 3.1 μL/min to 826.8 μL/min. The corresponding Reynolds number ranges from 0.3 to 80. The present micro-mixer consists of four mixing units. Each mixing unit is constructed by combining one split-and-recombine (SAR) unit with a mixing cell. The mixing performance was analyzed in terms of the degree of mixing and relative mixing cost. All numerical results show that the present micro-mixer performs better than other micro-mixers based on SARs over a wide range of volume flow rate. The mixing enhancement is realized by a particular motion of vortex flow: the Dean vortex in the circular sub-channel and another vortex inside the mixing cell. The two vortex flows are generated on the different planes perpendicular to each other. They cause the two fluids to change their relative position as the fluids flow into the circular sub-channel of the SAR, eventually promoting violent mixing. High vorticity in the mixing cell elongates the flow interface between two fluids, and promotes mixing in the flow regime of molecular diffusion dominance.
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Affiliation(s)
- Makhsuda Juraeva
- School of mechanical engineering, Yeungnam University, Gyungsan 712-749, Korea
| | - Dong Jin Kang
- School of mechanical engineering, Yeungnam University, Gyungsan 712-749, Korea
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Lee BM, Lee EM, Kang DJ, Seo JA, Choi HK, Kim YS, Lee DY. Discovery study of integrative metabolic profiles of sesame seeds cultivated in different countries. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109454] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kang DJ, Jüttke Y, González-García L, Escudero A, Haft M, Kraus T. Reversible Conductive Inkjet Printing of Healable and Recyclable Electrodes on Cardboard and Paper. Small 2020; 16:e2000928. [PMID: 32462772 DOI: 10.1002/smll.202000928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
Conductive inkjet printing with metal nanoparticles is irreversible because the particles are sintered into a continuous metal film. The resulting structures are difficult to remove or repair and prone to cracking. Here, a hybrid ink is used to obviate the sintering step and print interconnected particle networks that become highly conductive immediately after drying. It is shown that reversible conductive printing is possible on low-cost cardboard samples after applying standard paper industry coats that are adapted in terms of surface energy and porosity. The conductivity of the printed films approaches that of sintered standard inks on the same substrate, but the mobility of the hybrid particle film makes them less sensitive to cracks during bending and folding of the substrate. Damages that occur can be partially repaired by wetting the film such that particle mobility is increased and particles move to bridge insulating gaps in the film. It is demonstrated that the conductive material can be recovered from the cardboard at the end of its life time and be redispersed to recycle the particles and reuse them in conductive inks.
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Affiliation(s)
- Dong Jin Kang
- INM - Leibniz Institute for New Materials, Campus D2 2, Saarbrücken, 66123, Germany
| | - Yvonne Jüttke
- PTS - Papiertechnische Stiftung, Pirnaer Straße 37, Heidenau, 01809, Germany
| | - Lola González-García
- INM - Leibniz Institute for New Materials, Campus D2 2, Saarbrücken, 66123, Germany
| | - Alberto Escudero
- INM - Leibniz Institute for New Materials, Campus D2 2, Saarbrücken, 66123, Germany
| | - Marcel Haft
- PTS - Papiertechnische Stiftung, Pirnaer Straße 37, Heidenau, 01809, Germany
| | - Tobias Kraus
- INM - Leibniz Institute for New Materials, Campus D2 2, Saarbrücken, 66123, Germany
- Colloid and Interface Chemistry, Saarland University, Saarbrücken, 66123, Germany
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Kim SY, Kim SY, Lee SM, Lee DY, Shin BK, Kang DJ, Choi HK, Kim YS. Discrimination of Cultivated Regions of Soybeans ( Glycine max) Based on Multivariate Data Analysis of Volatile Metabolite Profiles. Molecules 2020; 25:E763. [PMID: 32050669 PMCID: PMC7036852 DOI: 10.3390/molecules25030763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 01/31/2020] [Accepted: 02/06/2020] [Indexed: 01/20/2023] Open
Abstract
Soybean (Glycine max) is a major crop cultivated in various regions and consumed globally. The formation of volatile compounds in soybeans is influenced by the cultivar as well as environmental factors, such as the climate and soil in the cultivation areas. This study used gas chromatography-mass spectrometry (GC-MS) combined by headspace solid-phase microextraction (HS-SPME) to analyze the volatile compounds of soybeans cultivated in Korea, China, and North America. The multivariate data analysis of partial least square-discriminant analysis (PLS-DA), and hierarchical clustering analysis (HCA) were then applied to GC-MS data sets. The soybeans could be clearly discriminated according to their geographical origins on the PLS-DA score plot. In particular, 25 volatile compounds, including terpenes (limonene, myrcene), esters (ethyl hexanoate, butyl butanoate, butyl prop-2-enoate, butyl acetate, butyl propanoate), aldehydes (nonanal, heptanal, (E)-hex-2-enal, (E)-hept-2-enal, acetaldehyde) were main contributors to the discrimination of soybeans cultivated in China from those cultivated in other regions in the PLS-DA score plot. On the other hand, 15 volatile compounds, such as 2-ethylhexan-1-ol, 2,5-dimethylhexan-2-ol, octanal, and heptanal, were related to Korean soybeans located on the negative PLS 2 axis, whereas 12 volatile compounds, such as oct-1-en-3-ol, heptan-4-ol, butyl butanoate, and butyl acetate, were responsible for North American soybeans. However, the multivariate statistical analysis (PLS-DA) was not able to clearly distinguish soybeans cultivated in Korea, except for those from the Gyeonggi and Kyeongsangbuk provinces.
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Affiliation(s)
- So-Yeon Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Korea; (S.-Y.K.); (S.Y.K.); (S.M.L.)
| | - So Young Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Korea; (S.-Y.K.); (S.Y.K.); (S.M.L.)
| | - Sang Mi Lee
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Korea; (S.-Y.K.); (S.Y.K.); (S.M.L.)
| | - Do Yup Lee
- Department of Agricultural Biotechnology, Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul 08779, Korea;
| | - Byeung Kon Shin
- National Agricultural Products Quality Management Service, Gimcheon 39660, Korea; (B.K.S.); (D.J.K.)
| | - Dong Jin Kang
- National Agricultural Products Quality Management Service, Gimcheon 39660, Korea; (B.K.S.); (D.J.K.)
| | | | - Young-Suk Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul 03760, Korea; (S.-Y.K.); (S.Y.K.); (S.M.L.)
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Lee EM, Park SJ, Lee JE, Lee BM, Shin BK, Kang DJ, Choi HK, Kim YS, Lee DY. Highly geographical specificity of metabolomic traits among Korean domestic soybeans (Glycine max). Food Res Int 2019; 120:12-18. [PMID: 31000221 DOI: 10.1016/j.foodres.2019.02.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [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: 09/21/2018] [Revised: 01/29/2019] [Accepted: 02/12/2019] [Indexed: 12/28/2022]
Abstract
Classification and characterization of agricultural products at molecular levels are important but often impractical with genotyping, particularly for soybeans that have numerous types of variety and landraces. Alternatively, metabolic signature, a determinant for nutritional value, can be the good molecular indicator, which reflects cultivation region-dependent factors such as climate and soil. Accordingly, we analyzed the integrative metabolic profiles of Korean soybeans cultivated in 7 different provinces (representative production areas), and explored the potential association with geographic traits. A total of 210 primary and secondary metabolites were profiled using gas-chromatography time-of-flight mass spectrometry (GC-TOF MS) and liquid-chromatography Orbitrap mass spectrometry (LC-Orbitrap MS). Despite the partial heterogeneity of the soybean varieties, the metabolomic phenotypic analysis based on multivariate statistics inferred the chemical compositional characteristics was primarily governed by the regional specificity. The OPLS-DA model proposed biomarker cluster re-composed with 5 metabolites (tryptophan, malonylgenistin, malonyldaidzin, N-acetylornithine, and allysine) (AUCs = 0.870-1.0). The most distinctive metabolic profiles were identified with the soybeans of Gunsan (middle-western coast) and Daegu (east-southern inland area), which were best characterized by the highest contents of isoflavones and amino acids, respectively. Further interrogation on geographic data suggested the combinatorial association of region-specific metabolic features with general soil texture and climate traits (total rainfall and average annual temperature).
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Affiliation(s)
- Eun Mi Lee
- Department of Bio and Fermentation Convergence Technology, BK21 Plus Program, Kookmin University, Seoul, Republic of Korea
| | - Soo Jin Park
- Department of Bio and Fermentation Convergence Technology, BK21 Plus Program, Kookmin University, Seoul, Republic of Korea
| | - Jung-Eun Lee
- Department of Bio and Fermentation Convergence Technology, BK21 Plus Program, Kookmin University, Seoul, Republic of Korea
| | - Bo Mi Lee
- Department of Bio and Fermentation Convergence Technology, BK21 Plus Program, Kookmin University, Seoul, Republic of Korea
| | - Byeung Kon Shin
- National Agricultural Products Quality Management Service, Gimcheon, Republic of Korea
| | - Dong Jin Kang
- National Agricultural Products Quality Management Service, Gimcheon, Republic of Korea
| | - Hyung-Kyoon Choi
- College of Pharmacy, Chung-Ang University, Seoul, Republic of Korea
| | - Young-Suk Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul, Republic of Korea.
| | - Do Yup Lee
- Department of Bio and Fermentation Convergence Technology, BK21 Plus Program, Kookmin University, Seoul, Republic of Korea.
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Abstract
Soft robotic systems are increasingly emerging as robust alternatives to conventional robotics. Here, we demonstrate the development of programmable soft actuators based on volume expansion/retraction accompanying liquid-vapor phase transition of a phase-change material confined within an elastomer matrix. The combination of a soft matrix (a silicone-based elastomer) and an embedded ethanol-impregnated polyacrylonitrile nanofiber (PAN NF) mat makes it possible to form a sealed compound device that can be operated by changing the actuator temperature above/below the boiling point of ethanol. The thermo-responsive actuators based on this principle demonstrate excellent bending ability at a sufficiently high temperature (>90 °C) - comparable with compressed air-based soft actuators. The actuator using the mechanism presented here is easy to manufacture and automate and is recyclable. Finally, the actuation mechanism can be incorporated into a wide variety of shapes and configurations, making it possible to obtain tunable and programmable soft robots that could have a wide variety of industrial applications.
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Affiliation(s)
- Dong Jin Kang
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor St., Chicago, Illinois 60607-7022, USA.
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Abstract
Here, model blister-like soft thermo-pneumatic artificial muscles with the embedded nanofibers impregnated with ethanol are developed. The muscles are essentially blister-like thermo-pneumatic soft actuators (BTSAs), which deflect in response to heat supplied to their bottom. The resulting deflections are on the scale of 1 cm, and the BTSAs are operational for several cycles. They are able to raise the artificial rigid scales, spines or fur/thin fibers attached to them emulating animals such as pangolin, hedgehog and porcupine. They are also capable of removing the stickiest adhesive tapes attached to them, and thus hold great promise for biomedical applications where artificially grown skin patches should be removed from an underlying substrate without being damaged. The theory of the BTSA proposed in this work is in reasonable agreement with the acquired experimental data.
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Affiliation(s)
- Seongpil An
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor St., Chicago, IL 60607-7022, USA.
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Kang DJ, Anand S. Nanoparticle synthesis via bubbling vapor precursors in bulk liquids. Nanoscale 2018; 10:12196-12203. [PMID: 29923585 DOI: 10.1039/c8nr01903g] [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
Conventional methods for preparing polymer nanoparticles and organic-inorganic composite nanoparticles use solution based top-down processes with surfactants and mechanical stirring. Examples of such processes include emulsion polymerization of monomers to produce polymer nanoparticles and sol-gel reactions involving hydrolysis of inorganic precursors to produce inorganic materials (such as silica and titanium nanoparticles). Here, we show that vaporized precursors of various compounds can be used as reactants to produce polymer, inorganic, and composite nanoparticles. The bubbling action of precursor vapor in a reactant vessel provides a constant supply of precursor species while aiding their rapid mixing in the bulk solution liquid. The vaporization and bubbling processes require only small amounts of energy to prepare nanoparticles or core-shell nanoparticles without forming unwanted side products. Compared to other available techniques, this approach enables precise control of nanoparticle size and shell thickness as functions of vapor supply time and temperature without surfactants. Our approach can potentially be applied to fabricate functional nanomaterials using organic and inorganic precursors for medical, electrical, optical, magnetic and/or catalytic applications.
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Affiliation(s)
- Dong Jin Kang
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Illinois 60605, USA.
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Abstract
Nanoparticle-stabilized (Pickering) emulsions are widely used in applications such as cosmetics, drug delivery, membranes, and material synthesis. However, formulating Pickering nanoemulsions remains a significant challenge. Herein, we show that Pickering nanoemulsions can be obtained in a single step even at very low nanoparticle loadings (0.2 wt %) by condensing water vapor on a nanoparticle-infused subcooled oil that spreads on water. Droplet nuclei spontaneously submerge within the oil after nucleating at the oil-air interface, resulting in the suppression of droplet growth by diffusion, and subsequently coalesce to larger sizes until their growth is curtailed by nanoparticle adsorption. The average nanoemulsion size is governed by the competition between nanoparticle adsorption kinetics and droplet growth dynamics, which are in turn a function of nanoparticle size, concentration, and condensation time. Controlling such factors can lead to the formation of highly monodisperse nanoemulsions. Emulsion formation via condensation is a fast, scalable, energy-efficient process that can be adapted for a wide variety of emulsion-based applications in biology, chemistry, and materials science.
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Affiliation(s)
- Dong Jin Kang
- Department of Mechanical and Industrial Engineering , University of Illinois at Chicago , Chicago , Illinois 60607 , United States
| | - Hassan Bararnia
- Department of Mechanical and Industrial Engineering , University of Illinois at Chicago , Chicago , Illinois 60607 , United States
| | - Sushant Anand
- Department of Mechanical and Industrial Engineering , University of Illinois at Chicago , Chicago , Illinois 60607 , United States
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Kang DJ, Kim HK. Clinical analysis of the factors contributing to pupillary optic capture after transscleral fixation of posterior chamber intraocular lens for dislocated intraocular lens. J Cataract Refract Surg 2016; 42:1146-50. [DOI: 10.1016/j.jcrs.2016.05.006] [Citation(s) in RCA: 12] [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] [Received: 04/04/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 11/26/2022]
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Affiliation(s)
- Dong Jin Kang
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
| | - Hong Kyun Kim
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
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Kwon YK, Kang DJ, Lim JC, Kim JH, Park DH, Shin JP. Fundus Autofluorescence, Fluorescein Angiography and Spectral Domain Optical Coherence Tomography Findings of Retinal Astrocytic Hamartomas in Tuberous Sclerosis. J Korean Ophthalmol Soc 2016. [DOI: 10.3341/jkos.2016.57.1.134] [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: 11/23/2022]
Affiliation(s)
- Young Ki Kwon
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
| | - Dong Jin Kang
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
| | - Jong Chan Lim
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
| | - Jong Ho Kim
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
| | - Dong Ho Park
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
| | - Jae Pil Shin
- Department of Ophthalmology, Kyungpook National University School of Medicine, Daegu, Korea
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Cho HH, Yang H, Kang DJ, Kim BJ. Surface engineering of graphene quantum dots and their applications as efficient surfactants. ACS Appl Mater Interfaces 2015; 7:8615-21. [PMID: 25825823 DOI: 10.1021/acsami.5b00729] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [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: 05/26/2023]
Abstract
The surface properties of graphene quantum dots (GQDs) control their dispersion and location within the matrices of organic molecules and polymers, thereby determining various properties of the hybrid materials. Herein, we developed a facile, one-step method for achieving systematic control of the surface properties of highly fluorescent GQDs. The surfaces of the as-synthesized hydrophilic GQDs were modified precisely depending on the number of grafted hydrophobic hexylamine. The geometry of the modified GQDs was envisioned by conducting simulations using density functional theory. In stark contrast to the pristine GQDs, the surface-modified GQDs can effectively stabilize oil-in-water Pickering emulsions and submicron-sized colloidal particles in mini-emulsion polymerization. These versatile GQD surfactants were also employed in liquid-solid systems; we demonstrated their use for tailoring the dispersion of graphite in methanol. Finally, the particles produced by the GQD surfactants were fluorescent due to luminescence of the GQDs, which offers great potential for various applications, including fluorescent sensors and imaging.
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Affiliation(s)
- Han-Hee Cho
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Hyunseung Yang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Dong Jin Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
| | - Bumjoon J Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
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Kang DJ, Cho HH, Lee I, Kim KH, Kim HJ, Liao K, Kim TS, Kim BJ. Enhancing mechanical properties of highly efficient polymer solar cells using size-tuned polymer nanoparticles. ACS Appl Mater Interfaces 2015; 7:2668-2676. [PMID: 25587815 DOI: 10.1021/am507710p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The low mechanical durability of polymer solar cells (PSCs) has been considered as one of the critical hurdles for their commercialization. We described a facile and powerful strategy for enhancing the mechanical properties of PSCs while maintaining their high power conversion efficiency (PCE) by using monodispersed polystyrene nanoparticles (PS NPs). We prepared highly monodispersed, size-controlled PS NPs (60, 80, and 100 nm), and used them to modify the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) anode buffer layer (ABL). The PS NPs played two important roles; i.e., they served as (1) binders in the PEDOT:PSS films, and (2) interfacial modifiers between ABL and the active layer, resulting in remarkable improvement of the mechanical integrity of the PSCs. The addition of PS NPs enhanced the inherent mechanical toughness of the PEDOT:PSS ABL due to their elastic properties, allowing the modified ABL to tolerate higher mechanical deformations. In addition, the adhesion energy (Gc) between the active layer and the modified PEDOT:PSS layer was enhanced significantly, i.e., by a factor of more than 1.5. The Gc value has a strong relationship with the sizes of the PS NP, showing the greatest enhancement when the largest size PS NPs (100 nm) were used. In addition, PS NPs significantly improve the air-stability of the PSCs by suppressing moisture adsorption and corrosion of the electrodes. Thus, the modification of ABL with PS NPs effectively enhances both the mechanical and the long-term stabilities of the PSCs without sacrificing their PCE values, demonstrating their great potential as applications in flexible organic electronics.
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Affiliation(s)
- Dong Jin Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
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Yang H, Kang DJ, Ku KH, Cho HH, Park CH, Lee J, Lee DC, Ajayan PM, Kim BJ. Highly Luminescent Polymer Particles Driven by Thermally Reduced Graphene Quantum Dot Surfactants. ACS Macro Lett 2014; 3:985-990. [PMID: 35610781 DOI: 10.1021/mz5003855] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the use of highly luminescent graphene quantum dots (GQDs) as efficient surfactants to produce Pickering emulsions and novel polymer particles. To generate the GQD surfactants, the surface properties of 10 nm sized, non-reduced GQDs (nGQDs), which have strong hydrophilicity, were synthesized and modified in a systematic manner by the thermal reduction of oxygen-containing groups at different treatment times. In stark contrast to the behavior of the nGQDs, thermally reduced GQDs (rGQDs) can produce highly stable Pickering emulsions of oil-in-water systems. To demonstrate the versatility of the rGQD surfactants, they were applied in a mini-emulsion polymerization system that requires nanosized surfactants to synthesize submicron-sized polystyrene particles. In addition, the use of rGQD surfactants can be extended to generating block copolymer particles with controlled nanostructures. Particularly, the polymer particles were highly luminescent, a characteristic produced by the highly fluorescent GQD surfactants, which has great potential for various applications, including bioimaging, drug delivery, and optoelectronic devices. To the best of our knowledge, this is the first report in which nanosized GQDs were used as surfactants.
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Affiliation(s)
- Hyunseung Yang
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Dong Jin Kang
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Kang Hee Ku
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Han-Hee Cho
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Chan Ho Park
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Junhyuk Lee
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Doh C. Lee
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Pulickel M. Ajayan
- Department
of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005-1892, United States
| | - Bumjoon J. Kim
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
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Kim T, Kang H, Jeong S, Kang DJ, Lee C, Lee CH, Seo MK, Lee JY, Kim BJ. Au@polymer core-shell nanoparticles for simultaneously enhancing efficiency and ambient stability of organic optoelectronic devices. ACS Appl Mater Interfaces 2014; 6:16956-65. [PMID: 25226068 DOI: 10.1021/am504503q] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this paper, we report and discuss our successful synthesis of monodispersed, polystyrene-coated gold core-shell nanoparticles (Au@PS NPs) for use in highly efficient, air-stable, organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs). These core-shell NPs retain the dual functions of (1) the plasmonic effect of the Au core and (2) the stability and solvent resistance of the cross-linked PS shell. The monodispersed Au@PS NPs were incorporated into a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film that was located between the ITO substrate and the emitting layer (or active layer) in the devices. The incorporation of the Au@PS NPs provided remarkable improvements in the performances of both OLEDs and OPVs, which benefitted from the plasmonic effect of the Au@PS NPs. The OLED device with the Au@PS NPs achieved an enhancement of the current efficiency that was 42% greater than that of the control device. In addition, the power conversion efficiency was increased from 7.6% to 8.4% in PTB7:PC71BM-based OPVs when the Au@PS NPs were embedded. Direct evidence of the plasmonic effect on optical enhancement of the device was provided by near-field scanning optical microscopy measurements. More importantly, the Au@PS NPs induced a remarkable and simultaneous improvement in the stabilities of the OLED and OPV devices by reducing the acidic and hygroscopic properties of the PEDOT:PSS layer.
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Affiliation(s)
- Taesu Kim
- Department of Chemical and Biomolecular Engineering, ‡KI for the NanoCentury, ⊥Graduate School of Energy, Environment, Water, and Sustainability (EEWS), and #Department of Physics, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Korea
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Abstract
Nanoparticles (NPs) at the interface between two different polymer blends or fluid mixtures can function as compatibilizers, thereby dramatically improving the interfacial properties of the blends or the fluid mixtures. Their compatibilizing ability is strongly dependent on their size, shape, and aspect ratios (ARs), which determines their adsorption energy to the interface as well as their entropic penalty when they are being strongly segregated at the interface. Herein, we investigated the effect of the ARs of nanorod surfactants on the conducting polymer blend of poly(triphenylamine) (PTPA) templated by polystyrene (PS) colloids. The lengths of the polymer-coated CuPt nanorods (CuPt NRs) were 5, 15, and 32 nm with a fixed width of 5 nm, thus producing three different AR values of 1, 3, and 6, respectively. For quantitative analysis, the morphological and electrical behaviors of the polymer blends were investigated in terms of the volume fraction and AR of the NRs. The dramatic change in the morphological and electrical properties of the blend film was observed for all three NR surfactants at the NR volume fraction of approximately 1 vol %. Therefore, NR surfactants with larger ARs had better compatibilizing power for a given number of NRs in the blends. Also, they exhibited a stronger tendency to be aligned parallel to the PS/PTPA interface. Also, we demonstrated the successful use of the NR surfactants in the fabrication of conducting polymer blend film that requires only minimal concentrations of conducting polymers. To the best of our knowledge, this is the first report of an experiment on the AR effect of NR compatibilizers in polymer blends.
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Affiliation(s)
- Taegyun Kwon
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701 Republic of Korea
| | - Kang Hee Ku
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701 Republic of Korea
| | - Dong Jin Kang
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701 Republic of Korea
| | - Won Bo Lee
- Department
of Chemical and Biomolecular Engineering, Sogang University, Seoul, 121-742 Republic of Korea
| | - Bumjoon J. Kim
- Department
of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701 Republic of Korea
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Kang YT, Kang DP, Kang DJ, Chung ID. Synthesis and properties of nanohybrid materials with SiO2 and epoxy resin. J Nanosci Nanotechnol 2014; 14:3557-3560. [PMID: 24734587 DOI: 10.1166/jnn.2014.7797] [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: 06/03/2023]
Abstract
SiO2-epoxy nanohybrid materials were synthesized by hybridization of surface-modified colloidal silica nanoparticle (CS) and epoxy resin. The CS was surface-modified with either methyltrimethoxysilane (MTMS) or phenyltrimethoxysilane (PTMS) followed by the solvent exchange with dimethylacetamide (DMAc) to have a homogenous dispersion in epoxy resin. Various amounts of surface-modified CS were mixed with epoxy resin. The chemical structures of surface-modified CS were investigated with FT-IR spectroscopy. The particle sizes of CS and surface-modified CS were measured with DLS. The morphology of hybrid materials analyzed using FE-SEM and AFM showed homogeneous dispersion in epoxy resin. The optical and thermal properties of the hybrid materials determined by refractive index meter and DSC were lower in RI and higher in Tg than neat epoxy resin, respectively.
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Ali FB, Kang DJ, Kim MP, Cho CH, Kim BJ. Synthesis of biodegradable and flexible, polylactic acid based, thermoplastic polyurethane with high gas barrier properties. POLYM INT 2014. [DOI: 10.1002/pi.4662] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Fathilah Binti Ali
- Department of Chemical and Biomolecular Engineering; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 305-701 Republic of Korea
| | - Dong Jin Kang
- Department of Chemical and Biomolecular Engineering; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 305-701 Republic of Korea
| | - Minsoo P Kim
- Department of Chemical and Biomolecular Engineering; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 305-701 Republic of Korea
| | - Chul-Hee Cho
- Department of Chemical and Biomolecular Engineering; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 305-701 Republic of Korea
| | - Bumjoon J Kim
- Department of Chemical and Biomolecular Engineering; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 305-701 Republic of Korea
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Kang YT, Kang DP, Kang DJ, Chung ID. Effect of SiO2-acryl nanohybrid coating layers on transparent conducting oxide-poly(ethylene terephthalate) superstrate. J Nanosci Nanotechnol 2013; 13:3669-3673. [PMID: 23858925 DOI: 10.1166/jnn.2013.7241] [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: 06/02/2023]
Abstract
SiO2-acryl nanohybrid coating layers were produced by hybridizing acrylic resin and surface-modified colloidal silica (CS) nanoparticles. First, CS nanoparticles were modified with methyltrimethoxysilane (MTMS) and vinyltrimethoxysilane (VTMS) by a sol-gel process. The surface-modified CS nanoparticles were then solvent-exchanged to be homogeneous in acrylic resin. The Hybrid materials were mixed in variation with the amount of surface-modified CS nanoparticles, coated with poly(ethylene terephthalate) (PET), then finally cured by UV light to obtain a hybrid coating layer. Field emission scanning electron microscopy (FE-SEM), particle size analysis (using a Zetasizer), and atomic force microscopy (AFM) were performed to determine the morphology of the hybrid thin-films. Thermogravimetric analysis (TGA) was used to investigate the thermal properties. Fourier-transform infrared (FTIR), ultraviolet-visible (UVNis) spectroscopies, and pencil hardness were used to obtain the details of chemical structures, optical properties, and hardness, respectively. The hybrid thin films had shown to be enhanced properties compared to their urethane acrylate prepolymer (UAP) coating film.
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Affiliation(s)
- Y T Kang
- Advanced Materials and Application Research Division, Korea Electrotechnology Research Institute, Changwon 642-120, Korea
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Kang DJ, Kang H, Cho C, Kim KH, Jeong S, Lee JY, Kim BJ. Efficient light trapping in inverted polymer solar cells by a randomly nanostructured electrode using monodispersed polymer nanoparticles. Nanoscale 2013; 5:1858-1863. [PMID: 23338854 DOI: 10.1039/c2nr33160h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The randomly nanotextured back electrode provides a simple and efficient route for enhancing photocurrent in polymer solar cells (PSCs) by light trapping, which can increase light absorption within a finite thickness of the active layer. In this study, we incorporated mono-disperse 60 nm polystyrene nanoparticles (PS NPs) into a 50 nm thick poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) anode buffer layer (ABL) to create a randomly nanotextured back electrode with 10 nm height variations in inverted-type PSCs. The roughened interface between the PS NP-PEDOT:PSS ABL and the Ag electrode scatters light in the visible range, leading to efficient light trapping within the device and enhanced light absorption in the active layer. Inverted PSCs with randomly nanotextured electrodes (φ(NP) = 0.31) showed short-circuit current density (J(SC)) and power conversion efficiency (PCE) values that were 15% higher than those of control devices with flat electrodes. External quantum efficiency, reflectance, and optical light scattering as a function of ϕ(NP) were examined to determine the origin of the enhancement in J(SC) and PCE.
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Affiliation(s)
- Dong Jin Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
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Kang DJ, Kang H, Kim KH, Kim BJ. Nanosphere templated continuous PEDOT:PSS films with low percolation threshold for application in efficient polymer solar cells. ACS Nano 2012; 6:7902-7909. [PMID: 22880844 DOI: 10.1021/nn3022926] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nanometer-sized monodisperse polystyrene nanospheres (PS NS) were designed as an opal template for the formation of three-dimensionally continuous poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films. The resultant films were successfully applied as the anode buffer layer (ABL) to produce highly efficient polymer solar cells (PSCs) with enhanced stability. The conductivity of the PS NS-PEDOT:PSS films was maintained up to ø(PS) = 0.75-0.80, indicating that the formation of continuous PEDOT:PSS films using PS NS templates was successful. To demonstrate the applicability of the PS NS-PEDOT:PSS film for organic electronics, the PS NS-PEDOT:PSS films were used as ABLs in two different PSCs: P3HT:PCBM and P3HT:OXCBA. The photovoltaic performances of both PSCs were maintained up to ø(PS) = 0.8. In particular, the power conversion efficiency of the P3HT:OXCBA PSC with a PS NS-PEDOT:PSS ABL (ø(PS) = 0.8) was greater than 5% and the air stability of the device was significantly enhanced.
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Affiliation(s)
- Dong Jin Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
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Kang DJ, Seo YJ, Saito T, Suzuki H, Ishii Y. Uptake and translocation of cesium-133 in napiergrass (Pennisetum purpureum Schum.) under hydroponic conditions. Ecotoxicol Environ Saf 2012; 82:122-126. [PMID: 22710264 DOI: 10.1016/j.ecoenv.2012.05.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 05/25/2012] [Accepted: 05/25/2012] [Indexed: 06/01/2023]
Abstract
The present study reports the potential remediation of cesium (Cs) using napiergrass, which produces the largest biomass among the herbaceous plants in hydroponic culture containing stable Cs (Cs-133) at concentrations of 50, 150, 300, 1000, and 3,000 μM using cesium chloride (CsCl), with 0 μM Cs as a control concentration. Plant height was significantly decreased in higher Cs-treated conditions (300, 1000, and 3000 μM Cs) at 7 weeks after treatment (WAT), but tiller numbers tended to increase compared with the control plant. No significant difference was observed in the aboveground dry matter weight in all Cs treatments throughout the study period. Cs content in the roots, leaf blades, and leaf sheaths clearly increased with increasing Cs concentration in the solutions. Cs content in the aboveground parts (leaf blades and leaf sheaths) was consistently higher than in the roots at concentration of 3,000 μM. Total Cs contents in the aboveground parts were 6305 and 26,365 mg kg(-1) at 7WAT in 1000- and 3000-μM Cs treatments, respectively. Mean values of transfer factors (TFs) in the aboveground parts were 50 μM=0.78, 150 μM=1.02, 300 μM=0.86, 1,000 μM=0.68, and 3,000 μM=0.94, respectively at 7WAT. Due to its high Cs content and high TF in the aboveground parts, napiergrass may be a candidate plant with high potential for phytoremediation of Cs from Cs-137-contaminated soil.
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Affiliation(s)
- Dong Jin Kang
- Teaching and Research Center for Bio-coexistence, Faculty of Agriculture and Life Science, Hirosaki University, Gosyogawara 037-0202, Japan.
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Kim MP, Kang DJ, Jung DW, Kannan AG, Kim KH, Ku KH, Jang SG, Chae WS, Yi GR, Kim BJ. Gold-decorated block copolymer microspheres with controlled surface nanostructures. ACS Nano 2012; 6:2750-2757. [PMID: 22352689 DOI: 10.1021/nn300194z] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Gold-decorated block copolymer microspheres (BCP-microspheres) displaying various surface morphologies were prepared by the infiltration of Au precursors into polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) microspheres. The microspheres were fabricated by emulsifying the PS-b-P4VP polymers in chloroform into a surfactant solution in water, followed by the evaporation of chloroform. The selective swelling of the P4VP domains in the microspheres by the Au precursor under acidic conditions resulted in the formation of Au-decorated BCP-microspheres with various surface nanostructures. As evidenced by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) measurements, dotted surface patterns were formed when microspheres smaller than 800 nm were synthesized, whereas fingerprint-like surface patterns were observed with microspheres larger than 800 nm. Au nanoparticles (NPs) were located inside P4VP domains near the surfaces of the prepared microspheres, as confirmed by TEM. The optical properties of the BCP-microspheres were characterized using UV-vis absorption spectroscopy and fluorescence lifetime measurements. A maximum absorption peak was observed at approximately 580 nm, indicating that Au NPs are densely packed into P4VP domains on the microspheres. Our approach for creating Au-NP-hybrid BCP-microspheres can be extended to other NP systems such as iron-oxide or platinum NPs. These precursors can also be selectively incorporated into P4VP domains and induce the formation of hybrid BCP-microspheres with controlled surface nanostructures.
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Affiliation(s)
- Minsoo P Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
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Kwon T, Kim T, Ali FB, Kang DJ, Yoo M, Bang J, Lee W, Kim BJ. Size-Controlled Polymer-Coated Nanoparticles as Efficient Compatibilizers for Polymer Blends. Macromolecules 2011. [DOI: 10.1021/ma2020134] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Taegyun Kwon
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Taesu Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Fathilah binti Ali
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Dong Jin Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Misang Yoo
- Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea
| | - Joona Bang
- Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea
| | - Wonbo Lee
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 121-742, Republic of Korea
| | - Bumjoon J. Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
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Kang DJ, Kwon T, Kim MP, Cho CH, Jung H, Bang J, Kim BJ. Creating opal-templated continuous conducting polymer films with ultralow percolation thresholds using thermally stable nanoparticles. ACS Nano 2011; 5:9017-9027. [PMID: 21961852 DOI: 10.1021/nn203209c] [Citation(s) in RCA: 18] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We propose a novel and robust strategy for creating continuous conducting polymer films with ultralow percolation thresholds using polymer-coated gold nanoparticles (Au NPs) as surfactant. Continuous poly(triphenylamine) (PTPA) films of high internal phase polymeric emulsions were fabricated using an assembly of cross-linked polystyrene (PS) colloidal particles as template. Polymer-coated Au NPs were designed to be thermally stable even above 200 °C and neutral to both the PS and PTPA phases. Therefore, the Au NPs localize at the PS/PTPA interface and function as surfactant to efficiently produce a continuous conducting PTPA polymer film with very low percolation thresholds. The volume fraction threshold for percolation of the PTPA phase with insulating PS colloids (as measured by electron microscopy and conductivity measurements) was found to be 0.20. In contrast, with the addition of an extremely low volume fraction (φ(p) = 0.35 vol %) of surfactant Au NPs, the volume fraction threshold for percolation of the PTPA phase was dramatically reduced to 0.05. The SEM and TEM measurements clearly demonstrated the formation of a continuous PTPA phase within the polyhedral phase of PS colloids. To elucidate the influence of the nanoparticle surfactant on the blend films, the morphology and conductivity of the blends at different PS colloid/PTPA volume ratios were carefully characterized as a function of the Au NP concentration. Our approach provides a methodology for a variety of applications that require a continuous phase for the transport of molecular species, ions, or electrons at low concentrations and a second phase for mechanical support or the conduction of a separate species.
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Affiliation(s)
- Dong Jin Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
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Kang DJ, Pal K, Bang DS, Kim JK. Synergistic effect on crystalline structure of polyvinylidene fluoride nanocomposites with multiwalled carbon nanotube loading by a twin screw extruder. J Appl Polym Sci 2011. [DOI: 10.1002/app.33524] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Liu XG, Geng DY, Jiang JJ, Du J, Yang F, Xie ZG, Kang DJ, Zhang ZD. High dielectric loss in graphite-coated Ti nanocapsules. J Nanosci Nanotechnol 2010; 10:2366-2369. [PMID: 20355435 DOI: 10.1166/jnn.2010.2159] [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: 05/29/2023]
Abstract
Graphite-coated Ti nanocapsules, with Ti nanoparticles as core and onion-like graphite layers as shell, have been prepared by a modified arc-discharge method in ethanol atmosphere, and characterized by means of X-ray diffraction, transmission electron microscopy and Raman spectroscopy. The dielectric properties of the graphite-coated Ti nanocapsules have been investigated in the 2-18 GHz range. An equivalent circuit model was used to interpret the non-linear dielectric resonance behavior of the graphite-coated Ti nanocapsules. The high dielectric loss is mainly attributed to conductance loss and dipole-relaxation loss in the graphite-coated Ti nanocapsules. The graphite-coated Ti nanocapsules exhibit promising properties for application as a new type of shield or absorbent of electromagnetic waves.
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Affiliation(s)
- X G Liu
- Shenyang National Laboratory for Material Science, Institute of Metal Research, and International Centre for Material Physics, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, People's Republic of China
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Pal K, Kang DJ, Zhang ZX, Kim JK. Synergistic effects of zirconia-coated carbon nanotube on crystalline structure of polyvinylidene fluoride nanocomposites: electrical properties and flame-retardant behavior. Langmuir 2010; 26:3609-3614. [PMID: 19908892 DOI: 10.1021/la903022j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Pristine multiwalled carbon nanotubes (MWNTs) and zirconia-coated multiwalled carbon nanotubes (ZrO(2)/MWNTs) by isothermal hydrolysis and the traditional chemical precipitation method have been dispersed into polyvinylidene fluoride (PVDF) copolymer by solution mixing in N,N-dimethylformamide (DMF). The effect of ZrO(2)-coated MWNTs on morphological properties, electrical properties, and flame-retardant behavior has been studied in comparison with virgin PVDF and PVDF/MWNTs nanocomposites. Due to the improved dispersion of the coated nanotubes, the incorporation of 3 wt % of ZrO(2)-coated MWNTs leads to an increase of the thermal stability and dielectric properties and a decrease of the peak heat-release rate.
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Affiliation(s)
- Kaushik Pal
- Polymer Science and Engineering, School of Nano and Advanced Materials Engineering, Gyeongsang National University, Gyeongnam, Jinju, 660-701, South Korea.
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Xin ZX, Zhang ZX, Pal K, Kim KJ, Kang DJ, Kim JK, Bang DS. Microcellular Structure of PP/Waste Rubber Powder Blends with Supercritical CO2 by Foam Extrusion Process. J CELL PLAST 2009. [DOI: 10.1177/0021955x09342937] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A new approach towards the recycling of waste ground rubber tire (WGRT) powder was demonstrated in this study by introducing the polypropylene/ waste ground rubber tire (PP/WGRT) foaming method by using CO2 as the foaming agent in an extrusion foaming process. The regression models were constructed to study the relationships between the foam structure (i.e., void fraction, average cell size, and cell density) of foamed PP/WGRT blends, the processing parameters (extruder’s die temperature and CO2 concentration), and WGRT content by applying a three-factor central composite design (CCD) statistical approach. The response surface plots generated using the regression models allow the rapid selection of the proper process parameters to obtain microcellular PP/WGRT blends with the desired density and morphology.
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Affiliation(s)
- Zhen Xiang Xin
- Key Laboratory of Rubber-plastics (Qingdao University of Science and Technology), Ministry of Education Qingdao 266042, People's Republic of China; School of Nano and Advanced Materials Engineering, Gyeongsang National University, Gyeongnam, Jinju 660-701, South Korea
| | - Zhen Xiu Zhang
- Key Laboratory of Rubber-plastics (Qingdao University of Science and Technology), Ministry of Education Qingdao 266042, People's Republic of China; School of Nano and Advanced Materials Engineering, Gyeongsang National University, Gyeongnam, Jinju 660-701, South Korea
| | - Kaushik Pal
- School of Nano and Advanced Materials Engineering, Gyeongsang National University, Gyeongnam, Jinju 660-701, South Korea
| | - Kwang-Jea Kim
- Key Laboratory of Rubber-plastics (Qingdao University of Science and Technology), Ministry of Education Qingdao 266042, People's Republic of China; Department of Polymer Engineering University of Akron, Akron OH 44325-0301, USA
| | - Dong Jin Kang
- School of Nano and Advanced Materials Engineering, Gyeongsang National University, Gyeongnam, Jinju 660-701, South Korea
| | - Jin Kuk Kim
- School of Nano and Advanced Materials Engineering, Gyeongsang National University, Gyeongnam, Jinju 660-701, South Korea,
| | - Dae-Suk Bang
- Department of Polymer Engineering and Science, Kumoh National Institute of Technology, Gyungbuk, 730-701, South Korea
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Sridhar V, Xiu ZZ, Xu D, Lee SH, Kim JK, Kang DJ, Bang DS. Fly ash reinforced thermoplastic vulcanizates obtained from waste tire powder. Waste Manag 2009; 29:1058-1066. [PMID: 18838261 DOI: 10.1016/j.wasman.2008.08.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 07/31/2008] [Accepted: 08/13/2008] [Indexed: 05/26/2023]
Abstract
Novel thermoplastic composites made from two major industrial and consumer wastes, fly ash and waste tire powder, have been developed. The effect of increasing fly ash loadings on performance characteristics such as tensile strength, thermal, dynamic mechanical and magnetic properties has been investigated. The morphology of the blends shows that fly ash particles have more affinity and adhesion towards the rubbery phase when compared to the plastic phase. The fracture surface of the composites shows extensive debonding of fly ash particles. Thermal analysis of the composites shows a progressive increase in activation energy with increase in fly ash loadings. Additionally, morphological studies of the ash residue after 90% thermal degradation shows extensive changes occurring in both the polymer and filler phases. The processing ability of the thermoplastics has been carried out in a Monsanto processability testing machine as a function of shear rate and temperature. Shear thinning behavior, typical of particulate polymer systems, has been observed irrespective of the testing temperatures. Magnetic properties and percolation behavior of the composites have also been evaluated.
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Affiliation(s)
- V Sridhar
- Elastomer Laboratory, Department of Polymer Science and Technology, Gyeongsang National University, Jinju 660-701, South Korea
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Cha SN, Song BG, Jang JE, Jung JE, Han IT, Ha JH, Hong JP, Kang DJ, Kim JM. Controlled growth of vertically aligned ZnO nanowires with different crystal orientation of the ZnO seed layer. Nanotechnology 2008; 19:235601. [PMID: 21825796 DOI: 10.1088/0957-4484/19/23/235601] [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: 05/31/2023]
Abstract
A novel synthesis and growth method achieving vertically aligned zinc oxide (ZnO) nanowires on a silicon dioxide (SiO(2)) coated silicon (Si) substrate is demonstrated. The growth direction of the ZnO nanowires is determined by the crystal structure of the ZnO seed layer, which is formed by the oxidation of a DC-sputtered Zn film. The [002] crystal direction of the seed layer is dominant under optimized thickness of the Zn film and thermal treatment. Vertically aligned ZnO nanowires on SiO(2) coated Si substrate are realized from the appropriately thick oxidized Zn seed layer by a vapor-solid growth mechanism by catalyst-free thermal chemical vapor deposition (CVD). These experimental results raise the possibility of using the nanowires as functional blocks for high-density integration systems and/or photonic applications.
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Affiliation(s)
- S N Cha
- Samsung Advanced Institute of Technology, PO Box 111, Suwon 440-600, Korea
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Stevenson R, Milner RG, Richards D, Arias AC, MacKenzie JD, Halls JJ, Friend RH, Kang DJ, Blamire M. Fluorescence scanning near-field optical microscopy of polyfluorene composites. J Microsc 2001; 202:433-8. [PMID: 11309108 DOI: 10.1046/j.1365-2818.2001.00871.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fluorescence scanning near-field optical microscopy (SNOM) is used to investigate binary polyfluorene-based composites of varying composition. The samples investigated contain blends of the polymer poly(9,9'-dioctylfluorene-cobenzothiadiazole), F8BT, with similar polyfluorenes of wider band gap. Images acquired from a film containing 50% by weight F8BT exhibit a high degree of correlation between the topography and fluorescence, with an F8BT-rich phase which protrudes from the surface of the film forming isolated regions with sizes from hundreds of nanometres to several micrometres. A film containing 10% by weight F8BT also has micrometre-size F8BT-rich regions, but also present are small and locally varying proportions of F8BT in the other polyfluorene component phase, indicating a hierarchy of phases within this sample. The fluorescence and topographic images of a third sample studied, containing 90% by weight F8BT, display no correlation, demonstrating that it is not always appropriate to use topographic information to determine the phase structure within polymer blends. The fluorescence SNOM images acquired from these samples are able to assist our understanding of the photovoltaic efficiency of devices fabricated from these films, which are governed by the extent of the interfacial area between these two constituent polymers.
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Affiliation(s)
- R Stevenson
- Department of Physics, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, U.K
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