52 results on '"Min Oh"'
Search Results
2. Enhanced Cycling Performance of a Li-Excess Li2CuO2 Cathode Additive by Cosubstitution Nanoarchitectonics of Ni and Mn for Lithium-Ion Batteries
- Author
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Taehee Kim, Junwon Lee, Min Jae You, Chang Hoon Song, Seung-Min Oh, Janghyuk Moon, Jung Ho Kim, and Min-Sik Park
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General Materials Science - Published
- 2023
3. Synergistic Inorganic/Inorganic Hybrid Approach for Fabricating a BTX Gas Adsorbent with High Performance and Thermal Stability
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Young Kyu Jeong, Su-Bin Lee, Sungjoon Kweon, Jeehun Jeong, Min Bum Park, Jae-Min Oh, and Jin Kuen Park
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Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Environmental Chemistry ,General Chemistry - Published
- 2023
4. Development of Isopropyl-Tailed Chalcones as a New Class of Selective MAO-B Inhibitors for the Treatment of Parkinson’s Disorder
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Sunil Kumar, Jong Min Oh, Mohamed A. Abdelgawad, Mohammed A.S. Abourehab, Anand Kumar Tengli, Ashutosh Kumar Singh, Iqrar Ahmad, Harun Patel, Bijo Mathew, and Hoon Kim
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General Chemical Engineering ,General Chemistry - Published
- 2023
5. Role of Oxygen in the Ti3AlC2 MAX Phase in the Oxide Formation and Conductivity of Ti3C2-Based MXene Nanosheets
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Su Bin Choi, Jung-Min Oh, Jagan Singh Meena, Hanjung Kwon, Seung-Boo Jung, and Jong-Woong Kim
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General Materials Science - Published
- 2023
6. Hybridization of Layered Titanium Oxides and Covalent Organic Nanosheets into Hollow Spheres for High-Performance Sodium-Ion Batteries with Boosted Electrical/Ionic Conductivity and Ultralong Cycle Life
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Minseop Lee, Min-Sung Kim, Jae-Min Oh, Jin Kuen Park, and Seung-Min Paek
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General Engineering ,General Physics and Astronomy ,General Materials Science - Published
- 2023
7. Synthesis of Alpha-Linked Glucosides from Soybean Isoflavone Aglycones Using Amylosucrase from Deinococcus geothermalis
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Young Sung Jung, Hyoung-Geun Kim, Seon Min Oh, Dae Young Lee, Cheon-Seok Park, Dae-Ok Kim, and Nam-In Baek
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General Chemistry ,General Agricultural and Biological Sciences - Published
- 2023
8. Highly Sensitive Interdigitated Capacitive Humidity Sensors Based on Sponge-Like Nanoporous PVDF/LiCl Composite for Real-Time Monitoring
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Enkhzaya Ganbold, Eun Seong Kim, Yang Li, Feifei Yin, Parshant Kumar Sharma, Jwa-Bin Jeon, Jong-Min Oh, Do Nam Lee, and Nam Young Kim
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General Materials Science - Published
- 2023
9. Surface-Modified Wrinkled Mesoporous Nanosilica as an Effective Adsorbent for Benzene, Toluene, Ethylbenzene, and Xylene in Indoor Air
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In-Keun Shim, Jeonghoon Kim, Jin Kyu Lee, Jae-Min Oh, and Jin Kuen Park
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General Materials Science - Published
- 2022
10. Recapitulating Tumor Hypoxia in a Cleanroom-Free, Liquid-Pinning-Based Microfluidic Tumor Model
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Jeong Min Oh, Hydari Masuma Begum, Yao Lucia Liu, Yuwei Ren, and Keyue Shen
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Male ,Oxygen ,Biomaterials ,Microfluidics ,Tumor Microenvironment ,Biomedical Engineering ,Humans ,Tumor Hypoxia ,Breast Neoplasms ,Microfluidic Analytical Techniques ,Hypoxia ,Article - Abstract
In tumors, the metabolic demand of cancer cells often outpaces oxygen supply, resulting in a gradient of tumor hypoxia accompanied with heterogeneous resistance to cancer therapeutics. Models recapitulating tumor hypoxia are therefore essential for developing more effective cancer therapeutics. Existing in vitro models often fail to capture the spatial heterogeneity of tumor hypoxia or involve high-cost, complex fabrication/handling techniques. Here, we designed a highly tunable microfluidic device that induces hypoxia through natural cell metabolism and oxygen diffusion barriers. We adopted a cleanroom-free, micromilling-replica-molding strategy and a microfluidic liquid-pinning approach to streamline the fabrication and tumor model establishment. We also implemented a thin-film oxygen diffusion barrier design, which was optimized through COMSOL simulation, to support both two-dimensional (2-D) and three-dimensional (3-D) hypoxic models. We demonstrated that liquid-pinning enables an easy, injection-based micropatterning of cancer cells of a wide range of parameters, showing the high tunability of our design. Human breast cancer and prostate cancer cells were seeded and stained after 24 h of 2-D and 3-D culture to validate the natural induction of hypoxia. We further demonstrated the feasibility of the parallel microfluidic channel design to evaluate dual therapeutic conditions in the same device. Overall, our new microfluidic tumor model serves as a user-friendly, cost-effective, and highly scalable platform that provides spatiotemporal analysis of the hypoxic tumor microenvironments suitable for high-content biological studies and therapeutic discoveries.
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- 2022
11. Homogenizing Silicon Domains in SiOx Anode during Cycling and Enhancing Battery Performance via Magnesium Doping
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Jeong-gyu Park, Jong-chan Lim, Ikcheon Na, Hyejeong Hyun, Hwiho Kim, Juwon Kim, Danwon Lee, Jongwoo Lim, Sungjae Seo, Seung-Min Oh, Jeong Woo Han, Sugeun Jo, Young-min Jeon, and Bonho Koo
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Materials science ,Silicon ,chemistry ,Chemical engineering ,Magnesium ,Physical vapor deposition ,Phase (matter) ,Doping ,chemistry.chemical_element ,General Materials Science ,Silicon oxide ,Faraday efficiency ,Anode - Abstract
SiOx (x ≈ 1) is one of the most promising anode materials for application in secondary lithium-ion batteries because of its high theoretical capacity. Despite this merit, SiOx has a poor initial Coulombic efficiency, which impedes its widespread use. To overcome this limitation, in this work, we successfully demonstrate a novel synthesis of Mg-doped SiOx via a mass-producible physical vapor deposition method. The solid-state reaction between Mg and SiOx produces Si and electrochemically inert magnesium silicate, thus increasing the initial Coulombic efficiency. The Mg doping concentration determines the phase of the magnesium silicate domains, the size of the Si domains, and the heterogeneity of these two domains. Detailed electron microscopy and synchrotron-based analysis revealed that the nanoscale homogeneity of magnesium silicates driven by cycling significantly affected the lifetime. We found that 8 wt % Mg is the most optimized concentration for enhanced cyclability because MgSiO3, which is the dominant magnesium silicate composition, can be homogeneously mixed with silicon clusters, preventing their aggregation during cycling and suppressing void formation.
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- 2021
12. Halogenated Coumarin–Chalcones as Multifunctional Monoamine Oxidase-B and Butyrylcholinesterase Inhibitors
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Ahmed Khames, Nicola Gambacorta, Nisha Abdul Rehuman, Bijo Mathew, Lekshmi R Nath, Rakesh Kumar Jat, Orazio Nicolotti, Jong Min Oh, Hoon Kim, and Mohamed A. Abdelgawad
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chemistry.chemical_classification ,General Chemical Engineering ,General Chemistry ,Coumarin ,Acetylcholinesterase ,Article ,In vitro ,Chemistry ,chemistry.chemical_compound ,Monoamine neurotransmitter ,Enzyme ,chemistry ,Biochemistry ,Monoamine oxidase B ,QD1-999 ,IC50 ,Butyrylcholinesterase - Abstract
A series of halogenated coumarin-chalcones were synthesized, characterized, and their inhibitory activities against monoamine oxidases (MAOs), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-site amyloid precursor protein cleaving enzyme 1 (BACE-1) were evaluated. Compound CC2 most potently inhibited MAO-B with an IC50 value of 0.51 μM, followed by CC1 (IC50 = 0.69 μM), with a selectivity index (SI) of >78.4 and >58.0, respectively, over MAO-A. However, none of the compounds effectively inhibited MAO-A, AChE, and BChE, except for CC2 and CC3 inhibiting BChE with IC50 values of 7.00 (SI > 5.73 over AChE) and 11.8 μM, respectively. CC1 and CC2 were found to be reversible and competitive inhibitors of MAO-B, with K i values of 0.50 ± 0.06 and 0.53 ± 0.04 μM, respectively, and CC2 was also a reversible and competitive inhibitor of BChE, with a K i value of 2.84 ± 0.09 μM. The parallel artificial membrane permeability assay (PAMPA) method showed that lead candidates can cross the blood-brain barrier (BBB). The in vitro toxicity analysis on the Vero cell line (Normal African green monkey kidney epithelial cells) by MTT confirmed that both CC1 and CC2 were nontoxic up to 100 μg/mL, which is almost equivalent to 100 times of their effective concentration used in biological studies. In addition, CC1 and CC2 attenuated H2O2-induced cellular damage via their reactive oxygen species (ROS) scavenging effect. These results suggest that CC1 and CC2 are selective and competitive inhibitors of MAO-B, and that CC2 is a selective and competitive inhibitor of BChE. Molecular docking studies of lead compounds provided the possible type of interactions in the targeted enzymes. Based on the findings, both compounds, CC1 and CC2, can be considered plausible drug candidates against neurodegenerative disorders.
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- 2021
13. One-Way Continuous Deposition of Monolayer MXene Nanosheets for the Formation of Two Confronting Transparent Electrodes in Flexible Capacitive Photodetector
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Jong-Woong Kim, Jung-Min Oh, and Hyun-Su Lim
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Supercapacitor ,Materials science ,business.industry ,02 engineering and technology ,Substrate (electronics) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Semiconductor ,Etching ,Monolayer ,Electrode ,Optoelectronics ,General Materials Science ,0210 nano-technology ,MXenes ,business ,Nanosheet - Abstract
MXenes based on titanium carbide are promising next-generation transparent electrode materials due to their high metallic conductivity, optical transparency, mechanical flexibility, and abundant hydrophilic surface functionality. MXene electrodes offer a much wider conductive surface coverage than metal nanowires, thereby gaining popularity as flexible electrode materials in supercapacitors and energy devices. However, given that monolayer MXene nanosheets are only a few nanometers thick, meticulous surface treatments and deposition technologies are required for a practical implementation of these transparent electrodes. Unfortunately, a capacitor produced by forming high-quality transparent MXene electrodes on both sides of a film has not yet been reported. We report the successful development of a one-way continuous deposition technology to form high-quality MXene nanosheet-based transparent electrodes on both surfaces of a polymer film without large physical stresses on the MXene nanosheets. One transparent electrode was formed by transferring MXene nanosheets predeposited on a temporary glass substrate to the film surface, while the other was directly deposited on the exposed film surface. The Ti3AlC2 precursor (MAX) was synthesized via a spark plasma sintering crystallization, and the MXene nanosheets were prepared via a subsequent Al-selective etching and delamination. We used this material to implement a capacitive photodetector consisting of two layers of opposing transparent electrodes. The flexible photodetector was based on poly(vinyl butyral) (PVB), which was solidly bonded with MXene nanosheets to serve as a free-standing binder for the Cu-doped ZnS semiconductor particles. The fabricated device exhibited excellent mechanical stability due to the high affinity between the MXene nanosheets and PVB. Furthermore, the device exhibited an initial capacitance of 2 nF, photosensitivity of 12.5 μF/W, and rise and decay times of 0.031 and 0.751 s, respectively. All these parameters were 1 to 2 orders of magnitude higher or faster than reported capacitive photodetectors. Overall, the proposed approach resolves the core issues associated with existing metal nanowire-based electrodes, and it is a breakthrough in the development of next-generation flexible devices comprising two layers of confronting transparent electrodes.
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- 2021
14. Correction to 'Role of Oxygen in the Ti3AlC2 MAX Phase in the Oxide Formation and Conductivity of Ti3C2-Based MXene Nanosheets'
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Su Bin Choi, Jung-Min Oh, Jagan Singh Meena, Hanjung Kwon, Seung-Boo Jung, and Jong-Woong Kim
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General Materials Science - Published
- 2023
15. Unique Noncontact Monitoring of Human Respiration and Sweat Evaporation Using a CsPb2Br5-Based Sensor
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Ik-Soo Kim, Jong-Min Oh, Chulhwan Park, Myung-Yeon Cho, Nam-Young Kim, Seok-Hun Kim, Sang-Wook Kim, and Sunghoon Kim
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Materials science ,business.industry ,Evaporation ,Humidity ,Interfacial polarization ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Capacitance ,0104 chemical sciences ,Transmission (telecommunications) ,Aerosol deposition ,Respiration ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Layer (electronics) - Abstract
Respiration monitoring and human sweat sensing have promising application prospects in personal healthcare data collection, disease diagnostics, and the effective prevention of human-to-human transmission of fatal viruses. Here, we have introduced a unique respiration monitoring and touchless sensing system based on a CsPb2Br5/BaTiO3 humidity-sensing layer operated by water-induced interfacial polarization and prepared using a facile aerosol deposition process. Based on the relationship between sensing ability and layer thickness, the sensing device with a 1.0 μm thick layer was found to exhibit optimal sensing performance, a result of its ideal microstructure. This sensor also exhibits the highest electrical signal variation at 0.5 kHz due to a substantial polarizability difference between high and low humidity. As a result, the CsPb2Br5/BaTiO3 sensing device shows the best signal variation of all types of breath-monitoring devices reported to date when used to monitor sudden changes in respiratory rates in diverse situations. Furthermore, the sensor can effectively detect sweat evaporation when placed 1 cm from the skin, including subtle changes in capacitance caused by finger area and motion, skin moisture, and contact time. This ultrasensitive sensor, with its fast response, provides a potential new sensing platform for the long-term daily monitoring of respiration and sweat evaporation.
- Published
- 2021
16. Cation–Anion and Anion–CO2 Interactions in Triethyl(octyl)phosphonium Ionic Liquids with Aprotic Heterocyclic Anions (AHAs)
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Seung-Min Oh, Oscar Morales-Collazo, Joan F. Brennecke, and Austin N. Keller
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chemistry.chemical_classification ,Steric effects ,010304 chemical physics ,Hydrogen bond ,Nuclear Overhauser effect ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Ylide ,0103 physical sciences ,Ionic liquid ,Materials Chemistry ,Hydrogen–deuterium exchange ,Phosphonium ,Physical and Theoretical Chemistry ,Two-dimensional nuclear magnetic resonance spectroscopy - Abstract
Ionic liquids with aprotic heterocyclic anions (AHAs) have been developed for postcombustion CO2 capture applications. The anions of AHA ILs play a significant role in tuning anion-CO2 complexation. In addition, AHAs are able to trigger the abstraction of acidic protons located at the α position of phosphonium cations by forming hydrogen bonds between cations and anions, eventually leading to cation-driven CO2 complexation. Here we investigate the role of the anion in cation-anion hydrogen bonding and ylide formation. Using CO2 uptake measurements, 31P nuclear magnetic resonance (NMR), attenuated total reflection-Fourier transform infrared (ATR-FTIR) deuterium exchange equilibrium and rates, two-dimensional nuclear Overhauser effect spectroscopy (2D NOESY), and density functional theory calculations, we show that the key is the proximity of the negatively charged nitrogen atoms on the anion to the α protons, which is governed not just by anion basicity but by sterics. Thus, we show that triethyl(octyl)phosphonium 3-methyl-5-trifluoromethylpyrazolide is much more effective in hydrogen-bonding with and deprotonating the cation than the equivalent [P2228] ILs with more basic 2-cyanopyrrolide and 3-trifluoromethylpyrazolide anions.
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- 2020
17. Dielectric Nanowire Hybrids for Plasmon-Enhanced Light–Matter Interaction in 2D Semiconductors
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Gwang Hwi An, Hyun Seok Lee, Jihoon Choi, Hye Min Oh, Young Hee Lee, Jung Ho Kim, and Jubok Lee
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Materials science ,business.industry ,General Engineering ,Nanowire ,General Physics and Astronomy ,02 engineering and technology ,Dielectric ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Semiconductor ,Transition metal ,Monolayer ,Optoelectronics ,General Materials Science ,Direct and indirect band gaps ,0210 nano-technology ,business ,Plasmon - Abstract
Monolayer transition metal dichalcogenides (TMDs) with a direct band gap are suitable for various optoelectronic applications such as ultrathin light emitters and absorbers. However, their weak light absorption caused by the atomically thin layer hinders more versatile applications for high optical gains. Although plasmonic hybridization with metal nanostructures significantly enhances light-matter interactions, the corrosion, instability of the metal nanostructures, and the undesired effects of direct metal-semiconductor contact act as obstacles to its practical application. Herein, we propose a dielectric nanostructure for plasmon-enhanced light-matter interaction of TMDs. TiO
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- 2020
18. Modulation of Junction Modes in SnSe2/MoTe2 Broken-Gap van der Waals Heterostructure for Multifunctional Devices
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Hobeom Jeon, Juchan Lee, Seungho Bang, Chulho Park, Mun Seok Jeong, Hye Min Oh, Duc Anh Nguyen, Ngoc Thanh Duong, and Jiseong Jang
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Materials science ,business.industry ,Mechanical Engineering ,Bioengineering ,Heterojunction ,02 engineering and technology ,General Chemistry ,Photovoltaic effect ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Backward diode ,Laser ,law.invention ,symbols.namesake ,law ,Modulation ,Tunnel diode ,symbols ,Optoelectronics ,General Materials Science ,Irradiation ,van der Waals force ,0210 nano-technology ,business - Abstract
We study the electronic and optoelectronic properties of a broken-gap heterojunction composed of SnSe2 and MoTe2 with gate-controlled junction modes. Owing to the interband tunneling current, our device can act as an Esaki diode and a backward diode with a peak-to-valley current ratio approaching 5.7 at room temperature. Furthermore, under an 811 nm laser irradiation the heterostructure exhibits a photodetectivity of up to 7.5 × 1012 Jones. In addition, to harness the electrostatic gate bias, Voc can be tuned from negative to positive by switching from the accumulation mode to the depletion mode of the heterojunction. Additionally, a photovoltaic effect with a fill factor exceeding 41% was observed, which highlights the significant potential for optoelectronic applications. This study not only demonstrates high-performance multifunctional optoelectronics based on the SnSe2/MoTe2 heterostructure but also provides a comprehensive understanding of broken-band alignment and its applications.
- Published
- 2020
19. Nanochemical Investigation of Degradation in Organic–Inorganic Hybrid Perovskite Films Using Infrared Nanoscopy
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Hyang Mi Yu, Hye Min Oh, Mun Seok Jeong, and Dae Young Park
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Materials science ,Infrared ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,Chemical engineering ,Organic inorganic ,Degradation (geology) ,Physical and Theoretical Chemistry ,Degradation process ,0210 nano-technology ,Perovskite (structure) - Abstract
The degradation of organic–inorganic hybrid perovskite (OHP) films is a crucial issue in OHP optoelectronics. Herein, we investigate the degradation process of OHP films by simultaneous measurement...
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- 2020
20. Multistage Degradation Mechanisms in Cu(In, Ga)Se2 Photovoltaic Modules Prepared by Co-Evaporation: Toward High Performances and Enhanced Stability
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Jong-Min Oh, Dong-Won Lee, Daeseok Lee, Hiesang Sohn, Won-Ju Cho, Myung-Yeon Cho, Ik-Soo Kim, Yong-Nam Kim, Sang-Mo Koo, and Chulhwan Park
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Materials science ,Photovoltaic system ,Energy Engineering and Power Technology ,Evaporation (deposition) ,Copper indium gallium selenide solar cells ,Durability ,Grain size ,chemistry.chemical_compound ,Aluminum doped zinc oxide ,chemistry ,Chemical engineering ,Materials Chemistry ,Electrochemistry ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering ,Copper indium gallium selenide - Abstract
This study compared the stability and durability of copper indium gallium selenide (CIGS)-type solar cells prepared using one-step and three-step co-evaporation methods by investigating the causes ...
- Published
- 2019
21. Polydopamine-Based Interfacial Engineering of Extracellular Matrix Hydrogels for the Construction and Long-Term Maintenance of Living Three-Dimensional Tissues
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Sunghee Estelle Park, Jeong Min Oh, Keon Woo Kwon, Dongeun Huh, and Andrei Georgescu
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Indoles ,Time Factors ,Materials science ,Polymers ,Microfluidics ,Cell Culture Techniques ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Organ-on-a-chip ,Article ,Extracellular matrix ,Humans ,General Materials Science ,Tissue Scaffolds ,Endothelial Cells ,Hydrogels ,Fibroblasts ,021001 nanoscience & nanotechnology ,In vitro ,Extracellular Matrix ,0104 chemical sciences ,Cell culture ,Printing, Three-Dimensional ,Self-healing hydrogels ,Biophysics ,Surface modification ,0210 nano-technology ,Interfacial engineering - Abstract
Diverse biological processes in the body rely on the ability of cells to exert contractile forces on their extracellular matrix (ECM). In three-dimensional (3D) cell culture, however, this intrinsic cellular property can cause unregulated contraction of ECM hydrogel scaffolds, leading to a loss of surface anchorage and the resultant structural failure of in vitro tissue constructs. Despite advances in the 3D culture technology, this issue remains a significant challenge in the development and long-term maintenance of physiological 3D in vitro models. Here, we present a simple yet highly effective and accessible solution to this problem. We leveraged a single-step surface functionalization technique based on polydopamine to drastically increase the strength of adhesion between hydrogel scaffolds and cell culture substrates. Our method is compatible with different types of ECM and polymeric surfaces and also permits prolonged shelf storage of functionalized culture substrates. The proof-of-principle of this technique was demonstrated by the stable long-term (1 month) 3D culture of human lung fibroblasts. Furthermore, we showed the robustness and advanced application of the method by constructing a dynamic cell stretching system and performing over 100 000 cycles of mechanical loading on 3D multicellular constructs for visualization and quantitative analysis of stretch-induced tissue alignment. Finally, we demonstrated the potential of our technique for the development of microphysiological in vitro models by establishing microfluidic 3D co-culture of vascular endothelial cells and fibroblasts to engineer self-assembled, perfusable 3D microvascular beds.
- Published
- 2019
22. Microphysiological Engineering of Self-Assembled and Perfusable Microvascular Beds for the Production of Vascularized Three-Dimensional Human Microtissues
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Hailey I Edelstein, Yoon-Suk Yi, Patrick Seale, Sunghee Estelle Park, Jeong Min Oh, Jungwook Paek, Keon Woo Kwon, Jacob W. Myerson, Dongeun Huh, Vladimir R. Muzykantov, Pavel Aprelev, Wenli Yang, Dwight Stambolian, Elizabeth D. Hood, Jeff Ishibashi, Qiaozhi Lu, Raisa Yu Kiseleva, Kyu-Tae Park, Minseon Cho, and Joseph W. Song
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Cell type ,Computer science ,Cell Culture Techniques ,General Physics and Astronomy ,Adenocarcinoma of Lung ,Context (language use) ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Organ-on-a-chip ,Self assembled ,Humans ,General Materials Science ,Cell Engineering ,Microcirculation ,General Engineering ,Endothelial Cells ,Hydrogels ,Fibroblasts ,Microfluidic Analytical Techniques ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Biopharmaceutical ,Drug delivery ,Nanomedicine ,Nanocarriers ,0210 nano-technology ,Biomedical engineering - Abstract
The vasculature is an essential component of the circulatory system that plays a vital role in the development, homeostasis, and disease of various organs in the human body. The ability to emulate the architecture and transport function of blood vessels in the integrated context of their associated organs represents an important requirement for studying a wide range of physiological processes. Traditional in vitro models of the vasculature, however, largely fail to offer such capabilities. Here we combine microfluidic three-dimensional (3D) cell culture with the principle of vasculogenic self-assembly to engineer perfusable 3D microvascular beds in vitro. Our system is created in a micropatterned hydrogel construct housed in an elastomeric microdevice that enables coculture of primary human vascular endothelial cells and fibroblasts to achieve de novo formation, anastomosis, and controlled perfusion of 3D vascular networks. An open-top chamber design adopted in this hybrid platform also makes it possible to integrate the microengineered 3D vasculature with other cell types to recapitulate organ-specific cellular heterogeneity and structural organization of vascularized human tissues. Using these capabilities, we developed stem cell-derived microphysiological models of vascularized human adipose tissue and the blood-retinal barrier. Our approach was also leveraged to construct a 3D organotypic model of vascularized human lung adenocarcinoma as a high-content drug screening platform to simulate intravascular delivery, tumor-killing effects, and vascular toxicity of a clinical chemotherapeutic agent. Furthermore, we demonstrated the potential of our platform for applications in nanomedicine by creating microengineered models of vascular inflammation to evaluate a nanoengineered drug delivery system based on active targeting liposomal nanocarriers. These results represent a significant improvement in our ability to model the complexity of native human tissues and may provide a basis for developing predictive preclinical models for biopharmaceutical applications.
- Published
- 2019
23. Discrete and Continuum Analyses of Confinement Effects of an Ionic Liquid on the EDL Structure and the Pressure Acting on the Wall
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Yu Dong Yang, In Seok Kang, Gi Jong Moon, and Jung Min Oh
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Materials science ,Continuum (measurement) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Physics::Fluid Dynamics ,Condensed Matter::Soft Condensed Matter ,chemistry.chemical_compound ,Molecular dynamics ,General Energy ,chemistry ,Chemical physics ,Ionic liquid ,Physics::Atomic and Molecular Clusters ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
We use both molecular dynamics (MD) and continuum models to analyze the electric double layer structure and pressure acting on the wall of a symmetrically valenced ionic liquid in a nanoconfinement...
- Published
- 2019
24. Scale-Up of a Semi-Batch Draft Tube Baffled Crystallizer for Hexanitrohexaazaisowurtzitane Based on Experiments and Computational Fluid Dynamics Simulation
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Min Oh, Kwang Joo Kim, Rak Young Jeon, Dong Hoon Oh, Jun Hyung Kim, and Chang Ha Lee
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Materials science ,010405 organic chemistry ,business.industry ,General Chemistry ,Computational fluid dynamics ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Draft tube ,Hexanitrohexaazaisowurtzitane ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,SCALE-UP ,General Materials Science ,Experimental work ,business - Abstract
In this study, experimental work was carried out for the production of microsized hexanitrohexaazaisowurtzitane (HNIW) in a 500 L draft tube baffled (DTB) crystallizer. Acetone and isopropanol were...
- Published
- 2018
25. Electrochemical Effects of Depositing Iridium Oxide Nanoparticles onto Conductive Woven and Nonwoven Flexible Substrates
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Shannon K. McGraw, Kwok-Fan Chow, Jung-Min Oh, Kris Senecal, and Dhanushka Wickramasinghe
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Materials science ,Energy Engineering and Power Technology ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,Iridium oxide ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Materials Chemistry ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering ,0210 nano-technology ,Electrical conductor - Abstract
This Article reports methods to deposit iridium oxide nanoparticles (IrOx NPs) onto flexible materials for charge storage and the stable charge–discharge mechanism. In this work, IrOx NPs were elec...
- Published
- 2018
26. Surface-Engineered Paper Hanging Drop Chip for 3D Spheroid Culture and Analysis
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Issac J. Michael, Yoon-Kyoung Cho, Junyoung Kim, Jung Min Oh, Sumit Kumar, and Dongyoung Kim
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Paper ,0301 basic medicine ,Materials science ,Surface Properties ,Drop (liquid) ,Cell Culture Techniques ,Spheroid ,Protein Corona ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Chip ,Fluid transport ,Nonspecific adsorption ,03 medical and health sciences ,Cellulose fiber ,030104 developmental biology ,Coated Materials, Biocompatible ,Spheroids, Cellular ,MCF-7 Cells ,Biophysics ,Humans ,General Materials Science ,0210 nano-technology ,Porosity - Abstract
Protein corona coated onto the hydrophilic cellulose fiber turns into hydrophobic upon UV irradiation without hindering the porosity of the paper while simultaneously reducing nonspecific adsorption. Taking advantage of the biofouling-resistant, hydrophobic, and fluid transport through property, we demonstrated hanging drop three-dimensional (3D) spheroid culture and in-site analysis, including drug testing, time-dependent detection of secreted protein, and fluorescence staining without disturbing the spheroids. This single hanging drop system can also be extended to a networked hanging drop chip to mimic in vivo microphysiology by combining with wax-patterned microfluidic channels, where well-to-well interaction can be accurately controlled in a passive manner. As a proof of concept, the effects of a concentration gradient of nutrient and variable dosage of anticancer drugs were studied in the 3D spheroids cultured on paper. The experimental results suggested that a complex network device could be fabricated on a large scale on demand at a minimal cost for 3D spheroid culture. Our method demonstrates a future possibility for paper as a low cost, high-throughput 3D spheroid-based "body-on-a-chip" platform material.
- Published
- 2018
27. Highly Enhanced Photoresponsivity of a Monolayer WSe2 Photodetector with Nitrogen-Doped Graphene Quantum Dots
- Author
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Hye Min Oh, Seungho Bang, Mun Seok Jeong, Seok Jun Yoon, Ngoc Thanh Duong, and Duc Anh Nguyen
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Electron mobility ,Materials science ,Photoluminescence ,business.industry ,Graphene ,Photodetector ,Heterojunction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Quantum dot ,Monolayer ,Optoelectronics ,Tungsten diselenide ,General Materials Science ,0210 nano-technology ,business - Abstract
Hybrid structures of two-dimensional (2D) materials and quantum dots (QDs) are particularly interesting in the field of nanoscale optoelectronic devices because QDs are efficient light absorbers and can inject photocarriers into thin layers of 2D transition-metal dichalcogenides, which have high carrier mobility. In this study, we present a heterostructure that consists of a monolayer of tungsten diselenide (ML WSe2) covered by nitrogen-doped graphene QDs (N-GQDs). The improved photoluminescence of ML WSe2 is attributed to the dominant neutral exciton emission caused by the n-doping effect. Owing to strong light absorption and charge transfer from N-GQDs to ML WSe2, N-GQD-covered ML WSe2 showed up to 480% higher photoresponsivity than that of a pristine ML WSe2 photodetector. The hybrid photodetector exhibits good environmental stability, with 46% performance retention after 30 days under ambient conditions. The photogating effect also plays a key role in the improvement of hybrid photodetector performanc...
- Published
- 2018
28. Controlled Crystal Growth of Two-Dimensional Layered Nanomaterials in Hydrogel via a Modified Electrical Double Migration Method
- Author
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Won-Jae Lee, So Youn Kim, Jae-Min Oh, Gyeong-Hyeon Gwak, Na Kyung Kwon, and Seung-Min Paek
- Subjects
Materials science ,Nanotechnology ,Crystal growth ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Uniform size ,01 natural sciences ,Homogeneous distribution ,0104 chemical sciences ,Nanomaterials ,chemistry.chemical_compound ,chemistry ,Agarose ,Hydroxide ,General Materials Science ,0210 nano-technology - Abstract
Layered double hydroxide (LDH) nanomaterials of uniform size and homogeneous distribution are successfully developed in agarose hydrogel through the electrical double migration method. To grow LDH ...
- Published
- 2017
29. Light Soaking Phenomena in Organic–Inorganic Mixed Halide Perovskite Single Crystals
- Author
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Hye Min Oh, Dae Young Park, Mun Seok Jeong, Gon Namkoong, and Hye Ryung Byun
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Materials science ,Photoluminescence ,business.industry ,Halide ,02 engineering and technology ,Trapping ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Photovoltaics ,Phase (matter) ,Organic inorganic ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Biotechnology ,Perovskite (structure) - Abstract
Recently, organic–inorganic mixed halide perovskite (MAPbX3; MA = CH3NH3+, X = Cl–, Br–, or I–) single crystals with low defect densities have been highlighted as candidate materials for high-efficiency photovoltaics and optoelectronics. Here we report the optical and structural investigations of mixed halide perovskite (MAPbBr3–xIx) single crystals. Mixed halide perovskite single crystals showed strong light soaking phenomena with light illumination conditions that were correlated to the trapping and detrapping events from defect sites. By systematic investigation with optical analysis, we found that the pseudocubic phase of mixed halide perovskites generates light soaking phenomena. These results indicate that photoinduced changes are related to the existence of multiple phases or halide migrations.
- Published
- 2017
30. Long-Life Nickel-Rich Layered Oxide Cathodes with a Uniform Li2ZrO3 Surface Coating for Lithium-Ion Batteries
- Author
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Seung-Min Oh, Arumugam Manthiram, Wangda Li, and Bohang Song
- Subjects
Materials science ,Annealing (metallurgy) ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Cathode ,0104 chemical sciences ,law.invention ,Ion ,Surface coating ,Nickel ,Coating ,Chemical engineering ,chemistry ,law ,engineering ,General Materials Science ,0210 nano-technology ,Oxide cathode - Abstract
As nickel-rich layered oxide cathodes start to attract worldwide interest for the next-generation lithium-ion batteries, their long-term cyclability in full cells remains a challenge for electric vehicles. Here we report a long-life Ni-rich layered oxide cathode (LiNi0.7Co0.15Mn0.15O2) with a uniform surface coating of the cathode particles with Li2ZrO3. A pouch-type full cell fabricated with the Li2ZrO3-coated cathode and a graphite anode displays 73.3% capacity retention after 1500 cycles at a C/3 rate. The Li2ZrO3 coating has been optimized by a systematic study with different synthesis approaches, annealing temperatures, and coating amounts. The complex relationship among the coating conditions, uniformity, and morphology of the coating layer and their impacts on the electrochemical properties are discussed in detail.
- Published
- 2017
31. FAST: Size-Selective, Clog-Free Isolation of Rare Cancer Cells from Whole Blood at a Liquid–Liquid Interface
- Author
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Hyeongeun Kim, Hyunjin Jeong, Juhee Park, Gwang Ha Kim, Sungmok Jung, Minji Lim, Jung Min Oh, Byung Chul Kim, Yoon-Kyoung Cho, Hee Chul Park, Sun Ju Lee, Mi-Hyun Kim, Do Youn Park, Kyu-Sang Lee, and Tae-Hyeong Kim
- Subjects
0301 basic medicine ,Time Factors ,Isolation (health care) ,Liquid-Liquid Extraction ,Nanotechnology ,Cell Separation ,Analytical Chemistry ,03 medical and health sciences ,0302 clinical medicine ,Circulating tumor cell ,Cell Line, Tumor ,Neoplasms ,medicine ,Humans ,Liquid liquid ,General hospital ,Cell Size ,Whole blood ,Chemistry ,Cancer ,Equipment Design ,Microfluidic Analytical Techniques ,Neoplastic Cells, Circulating ,medicine.disease ,Rare cancer ,030104 developmental biology ,030220 oncology & carcinogenesis ,Size selective ,Biomedical engineering - Abstract
Circulating tumor cells (CTCs) have great potential to provide minimally invasive ways for the early detection of cancer metastasis and for the response monitoring of various cancer treatments. Despite the clinical importance and progress of CTC-based cancer diagnostics, most of the current methods of enriching CTCs are difficult to implement in general hospital settings due to complex and time-consuming protocols. Among existing technologies, size-based isolation methods provide antibody-independent, relatively simple, and high throughput protocols. However, the clogging issues and lower than desired recovery rates and purity are the key challenges. In this work, inspired by antifouling membranes with liquid-filled pores in nature, clog-free, highly sensitive (95.9 ± 3.1% recovery rate), selective (2.5 log depletion of white blood cells), rapid (3 mL/min), and label-free isolation of viable CTCs from whole blood without prior sample treatment is achieved using a stand-alone lab-on-a-disc system equipped with fluid-assisted separation technology (FAST). Numerical simulation and experiments show that this method provides uniform, clog-free, ultrafast cell enrichment with pressure drops much less than in conventional size-based filtration, at 1 kPa. We demonstrate the clinical utility of the point-of-care detection of CTCs with samples taken from 142 patients suffering from breast, stomach, or lung cancer.
- Published
- 2016
32. Modulating Electronic Properties of Monolayer MoS2 via Electron-Withdrawing Functional Groups of Graphene Oxide
- Author
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Hyun Jeong, Seung Yol Jeong, Si Young Lee, Ki Kang Kim, Sooyeon Jeong, Gang Hee Han, Hyun Kyu Kim, Doo Jae Park, Mun Seok Jeong, Jung Ho Kim, Hye Min Oh, and Young Hee Lee
- Subjects
Materials science ,Photoluminescence ,Exciton ,Inorganic chemistry ,Oxide ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,Photochemistry ,01 natural sciences ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,law ,Monolayer ,General Materials Science ,Diode ,Graphene ,Doping ,General Engineering ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,symbols ,0210 nano-technology ,Raman spectroscopy - Abstract
Modulation of the carrier concentration and electronic type of monolayer (1L) MoS2 is highly important for applications in logic circuits, solar cells, and light-emitting diodes. Here, we demonstrate the tuning of the electronic properties of large-area 1L-MoS2 using graphene oxide (GO). GO sheets are well-known as hole injection layers since they contain electron-withdrawing groups such as carboxyl, hydroxyl, and epoxy. The optical and electronic properties of GO-treated 1L-MoS2 are dramatically changed. The photoluminescence intensity of GO-treated 1L-MoS2 is increases by more than 470% compared to the pristine sample because of the increase in neutral exciton contribution. In addition, the A1g peak in Raman spectra shifts considerably, revealing that GO treatment led to the formation of p-type doped 1L-MoS2. Moreover, the current vs voltage (I–V) curves of GO-coated 1L-MoS2 field effect transistors show that the electron concentration of 1L-MoS2 is significantly lower in comparison with pristine 1L-MoS...
- Published
- 2016
33. Enzymatic Process for High-Yield Turanose Production and Its Potential Property as an Adipogenesis Regulator
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Cheon-Seok Park, Ji Ye Lim, Yuri Kim, Byung-Hoo Lee, Min Oh Park, Eunjin Lim, Hyeon Gyu Lee, Sang-Ho Yoo, and Hee Kwon Kang
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0106 biological sciences ,0301 basic medicine ,Sucrose ,Fructose ,Disaccharides ,01 natural sciences ,Turanose ,Mice ,03 medical and health sciences ,Amylosucrase ,chemistry.chemical_compound ,Functional food ,3T3-L1 Cells ,010608 biotechnology ,Animals ,fas Receptor ,Adipogenesis ,biology ,Chemistry ,Substrate (chemistry) ,Lipid metabolism ,General Chemistry ,Lipid Metabolism ,PPAR gamma ,030104 developmental biology ,Gene Expression Regulation ,Biochemistry ,Glucosyltransferases ,biology.protein ,Sterol Regulatory Element Binding Protein 1 ,General Agricultural and Biological Sciences ,Biotechnology - Abstract
Turanose is a sucrose isomer naturally existing in honey and a promising functional sweetener due to its low glycemic response. In this study, the extrinsic fructose effect on turanose productivity was examined in Neisseria amylosucrase reaction. Turanose was produced, by increasing the amount of extrinsic fructose as a reaction modulator, with high concentration of sucrose substrate, which resulted in 73.7% of production yield. In physiological functionality test, lipid accumulation in 3T3-L1 preadipocytes in the presence of high amounts of pure glucose was attenuated by turanose substitution in a dose-dependent manner. Turanose treatments at concentrations representing 50%, 75%, and 100% of total glucose concentration in cell media significantly reduced lipid accumulation by 18%, 35%, and 72%, respectively, as compared to controls. This result suggested that turanose had a positive role in controlling adipogenesis, and enzymatic process of turanose production has a potential to develop a functional food ingredient for controlling obesity and related chronic diseases.
- Published
- 2016
34. Photochemical Reaction in Monolayer MoS2 via Correlated Photoluminescence, Raman Spectroscopy, and Atomic Force Microscopy
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Jung Jun Bae, Hye Min Oh, Gang Hee Han, Mun Seok Jeong, Hyun Kim, and Young Hee Lee
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Materials science ,Photoluminescence ,Exciton ,General Engineering ,Analytical chemistry ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,Laser ,01 natural sciences ,0104 chemical sciences ,law.invention ,symbols.namesake ,Physisorption ,Chemisorption ,law ,Monolayer ,symbols ,General Materials Science ,Irradiation ,0210 nano-technology ,Raman spectroscopy - Abstract
Photoluminescence (PL) from monolayer MoS2 has been modulated using plasma treatment or thermal annealing. However, a systematic way of understanding the underlying PL modulation mechanism has not yet been achieved. By introducing PL and Raman spectroscopy, we analyze that the PL modulation by laser irradiation is associated with structural damage and associated oxygen adsorption on the sample in ambient conditions. Three distinct behaviors were observed according to the laser irradiation time: (i) slow photo-oxidation at the initial stage, where the physisorption of ambient gases gradually increases the PL intensity; (ii) fast photo-oxidation at a later stage, where chemisorption increases the PL intensity abruptly; and (iii) photoquenching, with complete reduction of PL intensity. The correlated confocal Raman spectroscopy confirms that no structural deformation is involved in slow photo-oxidation stage; however, the structural disorder is invoked during the fast photo-oxidation stage, and severe structural degradation is generated during the photoquenching stage. The effect of oxidation is further verified by repeating experiments in vacuum, where the PL intensity is simply degraded with laser irradiation in a vacuum due to a simple structural degradation without involving oxygen functional groups. The charge scattering by oxidation is further explained by the emergence/disappearance of neutral excitons and multiexcitons during each stage.
- Published
- 2016
35. Naked-Eye Coulometric Sensor Using a Longitudinally Oriented Ag Band Electrode in a Microfluidic Channel
- Author
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Jung-Min Oh and Kwok-Fan Chow
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Auxiliary electrode ,Microchannel ,Working electrode ,Chemistry ,010401 analytical chemistry ,Analytical chemistry ,010402 general chemistry ,01 natural sciences ,Glass electrode ,Reference electrode ,0104 chemical sciences ,Analytical Chemistry ,law.invention ,Quinhydrone electrode ,law ,Electrode ,Palladium-hydrogen electrode - Abstract
In this Article, we report a coulometric sensing platform that is capable of sensing analytes on a working electrode and providing a visual readout of the analyte concentration on a silver (Ag) band counter electrode in a microchannel. The display mechanism relies on the electro-oxidation of metallic Ag as a complementary reaction to the sensing reduction reaction. The Ag band counter electrode is arranged longitudinally in a microchannel while the frontal tip of the band electrode directly faces a gold (Au) working electrode, which lies across the microchannel. The Ag oxidation always occurs at the band electrode's tip region that faces the working electrode due to the Ohmic potential drop across the solution in the microchannel. The decrement of the Ag electrode, which is clearly measurable with the naked eye, correlates linearly with an analyte concentration (e.g., 0.1-2.5 mM p-benzoquinone) and with an analyte feeding rate (i.e., a sample solution flow rate of 1.0-75.0 μL min(-1)). The platform design is also effective for a model analyte of horseradish peroxidase (HRP)-avidin in the dynamic range of 0.1-3.0 μg mL(-1).
- Published
- 2016
36. Semiconductor–Insulator–Semiconductor Diode Consisting of Monolayer MoS2, h-BN, and GaN Heterostructure
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Hyun Jeong, Gilles Lerondel, Ki Kang Kim, Seungho Bang, Sung Jin An, Hyun Kim, Hye Min Oh, Young Hee Lee, Mun Seok Jeong, Gang Hee Han, Hyeon Jun Jeong, Jin Cheol Park, Laboratoire de Nanotechnologie et d'Instrumentation Optique (LNIO), Institut Charles Delaunay (ICD), Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS), Sungkyunkwan University [Suwon] (SKKU), Dongguk University (DU), and Department of Energy Science
- Subjects
diode carrier tunneling ,Materials science ,Photoluminescence ,business.industry ,semiconductor−insulator−semiconductor ,General Engineering ,General Physics and Astronomy ,Heterojunction ,Chemical vapor deposition ,Epitaxy ,7. Clean energy ,GaN ,monolayer MoS2 ,symbols.namesake ,Semiconductor ,Monolayer ,symbols ,Optoelectronics ,General Materials Science ,h-BN ,[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics ,business ,Raman spectroscopy ,Diode - Abstract
International audience; We propose a semiconductor–insulator–semiconductor (SIS) heterojunction diode consisting of monolayer (1-L) MoS2, hexagonal boron nitride (h-BN), and epitaxial p-GaN that can be applied to high-performance nanoscale optoelectronics. The layered materials of 1-L MoS2 and h-BN, grown by chemical vapor deposition, were vertically stacked by a wet-transfer method on a p-GaN layer. The final structure was verified by confocal photoluminescence and Raman spectroscopy. Current–voltage (I–V) measurements were conducted to compare the device performance with that of a more classical p–n structure. In both structures (the p–n and SIS heterojunction diode), clear current-rectifying characteristics were observed. In particular, a current and threshold voltage were obtained for the SIS structure that was higher compared to that of the p–n structure. This indicated that tunneling is the predominant carrier transport mechanism. In addition, the photoresponse of the SIS structure induced by the illumination of visible light was observed by photocurrent measurements.
- Published
- 2015
37. Synthesis of Centimeter-Scale Monolayer Tungsten Disulfide Film on Gold Foils
- Author
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Hye Min Oh, Gang Hee Han, Seok Joon Yun, Young Hee Lee, Mun Seok Jeong, Ki Kang Kim, Joo Song Lee, Sang Hoon Chae, Hyun Kim, Jinbong Seok, Jin Cheol Park, Jihoon Park, and Soo Min Kim
- Subjects
Electron mobility ,Materials science ,business.industry ,Tungsten disulfide ,Inorganic chemistry ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,Chemical vapor deposition ,Substrate (electronics) ,Tungsten ,chemistry.chemical_compound ,chemistry ,Monolayer ,Optoelectronics ,General Materials Science ,Field-effect transistor ,business ,FOIL method - Abstract
We report the synthesis of centimeter-scale monolayer WS2 on gold foil by chemical vapor deposition. The limited tungsten and sulfur solubility in gold foil allows monolayer WS2 film growth on gold surface. To ensure the coverage uniformity of monolayer WS2 film, the tungsten source-coated substrate was placed in parallel with Au foil under hydrogen sulfide atmosphere. The high growth temperature near 935 °C helps to increase a domain size up to 420 μm. Gold foil is reused for the repeatable growth after bubbling transfer. The WS2-based field effect transistor reveals an electron mobility of 20 cm(2) V(-1) s(-1) with high on-off ratio of ∼10(8) at room temperature, which is the highest reported value from previous reports of CVD-grown WS2 samples. The on-off ratio of integrated multiple FETs on the large area WS2 film on SiO2 (300 nm)/Si substrate shows within the same order, implying reasonable uniformity of WS2 FET device characteristics over a large area of 3 × 1.5 cm(2).
- Published
- 2015
38. High Capacity O3-Type Na[Li0.05(Ni0.25Fe0.25Mn0.5)0.95]O2 Cathode for Sodium Ion Batteries
- Author
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Yang-Kook Sun, Seung-Taek Myung, Bruno Scrosati, Khalil Amine, Jang Yeon Hwang, and Seung-Min Oh
- Subjects
Materials science ,Coprecipitation ,General Chemical Engineering ,Sodium ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Cathode ,law.invention ,Anode ,chemistry ,Transition metal ,law ,Electrode ,Materials Chemistry ,Layer (electronics) ,Carbon - Abstract
In this work we report Na[Li0.05(Ni0.25Fe0.25Mn0.5)0.95]O2 layered cathode materials that were synthesized via a coprecipitation method. The Na[Li0.05(Ni0.25Fe0.25Mn0.5)0.95]O2 electrode exhibited an exceptionally high capacity (180.1 mA h g–1 at 0.1 C-rate) as well as excellent capacity retentions (0.2 C-rate: 89.6%, 0.5 C-rate: 92.1%) and rate capabilities at various C-rates (0.1 C-rate: 180.1 mA h g–1, 1 C-rate: 130.9 mA h g–1, 5 C-rate: 96.2 mA h g–1), which were achieved due to the Li supporting structural stabilization by introduction into the transition metal layer. By contrast, the electrode performance of the lithium-free Na[Ni0.25Fe0.25Mn0.5]O2 cathode was inferior because of structural disintegration presumably resulting from Fe3+ migration from the transition metal layer to the Na layer during cycling. The long-term cycling using a full cell consisting of a Na[Li0.05(Ni0.25Fe0.25Mn0.5)0.95]O2 cathode was coupled with a hard carbon anode which exhibited promising cycling data including a 76% ca...
- Published
- 2014
39. Surfactant-Assisted Synthesis of Fe2O3 Nanoparticles and F-Doped Carbon Modification toward an Improved Fe3O4@CFx/LiNi0.5Mn1.5O4 Battery
- Author
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Shu Tian, Yang-Kook Sun, Hai Ming, Seung-Min Oh, Hui Huang, Qun Zhou, Junwei Zheng, and Jun Ming
- Subjects
Materials science ,Polyvinylpyrrolidone ,Carbonization ,Inorganic chemistry ,technology, industry, and agriculture ,Nanoparticle ,Lithium-ion battery ,Anode ,chemistry.chemical_compound ,chemistry ,Pulmonary surfactant ,Chemical engineering ,Bromide ,medicine ,General Materials Science ,Ethylene glycol ,medicine.drug - Abstract
A simple surfactant-assisted reflux method was used in this study for the synthesis of cocklebur-shaped Fe2O3 nanoparticles (NPs). With this strategy, a series of nanostructured Fe2O3 NPs with a size distribution ranging from 20 to 120 nm and a tunable surface area were readily controlled by varying reflux temperature and the type of surfactant. Surfactants such as cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (F127) and sodium dodecyl benzenesulfonate (SDBS) were used to achieve large-scale synthesis of uniform Fe2O3 NPs with a relatively low cost. A new composite of Fe3O4@CFx was prepared by coating the primary Fe2O3 NPs with a layer of F-doped carbon (CFx) with a one-step carbonization process. The Fe3O4@CFx composite was utilized as the anode in a lithium ion battery and exhibited a high reversible capacity of 900 mAh g(-1) at a current density of 100 mA g(-1) over 100 cycles with 95% capacity retention. In addition, a new Fe3O4@CFx/LiNi(0.5)Mn(1.5)O4 battery with a high energy density of 371 Wh kg(-1) (vs cathode) was successfully assembled, and more than 300 cycles were easily completed with 66.8% capacity retention at 100 mA g(-1). Even cycled at the high temperature of 45 °C, this full cell also exhibited a relatively high capacity of 91.6 mAh g(-1) (vs cathode) at 100 mA g(-1) and retained 54.6% of its reversible capacity over 50 cycles. Introducing CFx chemicals to modify metal oxide anodes and/or any other cathode is of great interest for advanced energy storage and conversion devices.
- Published
- 2014
40. High Electrochemical Performances of Microsphere C-TiO2 Anode for Sodium-Ion Battery
- Author
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Jun Lu, Illias Belharouak, Seung-Min Oh, Khalil Amine, Jang Yeon Hwang, Yang-Kook Sun, and Chong Seung Yoon
- Subjects
Materials science ,Sodium ,Composite number ,chemistry.chemical_element ,Sodium-ion battery ,Electrochemistry ,law.invention ,Anode ,chemistry ,law ,Electrode ,General Materials Science ,Calcination ,Composite material ,Carbon ,Nuclear chemistry - Abstract
High-power, long-life carbon-coated TiO2 microsphere electrodes were synthesized by a hydrothermal method for sodium ion batteries, and the electrochemical properties were evaluated as a function of carbon content. The carbon coating, introduced by sucrose addition, had an effect of suppressing the growth of the TiO2 primary crystallites during calcination. The carbon coated TiO2 (sucrose 20 wt % coated) electrode exhibited excellent cycle retention during 50 cycles (100%) and superior rate capability up to a 30 C rate at room temperature. This cell delivered a high discharge capacity of 155 mAh g(composite)(-1) at 0.1 C, 149 mAh g(composite)(-1) at 1 C, and 82.7 mAh g(composite)(-1) at a 10 C rate, respectively.
- Published
- 2014
41. Geomechanical and Thermal Responses of Hydrate-Bearing Sediments Subjected to Thermal Stimulation: Physical Modeling Using a Geotechnical Centrifuge
- Author
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Changho Lee, Kang-Ryel Lee, Tae-Min Oh, Gye-Chun Cho, Tae-Hyuk Kwon, and Yun Wook Choo
- Subjects
Centrifuge ,Fuel Technology ,Electrical resistance and conductance ,Shear (geology) ,General Chemical Engineering ,Clathrate hydrate ,Thermal ,Energy Engineering and Power Technology ,Sediment ,Geotechnical engineering ,Softening ,Geology ,Pressure vessel - Abstract
The geomechanical and thermal responses of sediments can be significantly affected by the dissociation of gas hydrates via various emergent phenomena such as fluid volume expansion, free gas generation, gas migration, and sediment softening. This study explores the geomechanical and thermal responses of hydrate-bearing sediments subjected to thermal stimulation, using physical modeling with a geotechnical centrifuge that enables the simulation of near-seafloor sediment conditions. A water-saturated and CO2 hydrate-bearing sand column was prepared in a large cylindrical pressure vessel, and a linear stress gradient for a near-seafloor condition was created by increasing centrifugal acceleration. The hydrate-bearing sand column was subjected to thermal stimulation, and changes in temperature, pressure, compressional wave velocity (VP), shear wave velocity (VS), and electrical resistance were monitored at various locations across the column. It was found that VP and electrical resistance were good indicators...
- Published
- 2013
42. Mesoporous Carbon/Zirconia Composites: A Potential Route to Chemically Functionalized Electrically-Conductive Mesoporous Materials
- Author
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Jung-Min Oh, Amar Kumbhar, Olt E. Geiculescu, and Stephen E. Creager
- Subjects
Thermogravimetric analysis ,Nanocomposite ,Materials science ,chemistry.chemical_element ,Surfaces and Interfaces ,Porosimetry ,Condensed Matter Physics ,Mesoporous organosilica ,chemistry ,Chemical engineering ,Electrochemistry ,General Materials Science ,Cubic zirconia ,Porosity ,Mesoporous material ,Carbon ,Spectroscopy - Abstract
Mesoporous nanocomposite materials in which nanoscale zirconia (ZrO(2)) particles are embedded in the carbon skeleton of a templated mesoporous carbon matrix were prepared, and the embedded zirconia sites were used to accomplish chemical functionalization of the interior surfaces of mesopores. These nanocomposite materials offer a unique combination of high porosity (e.g., ∼84% void space), electrical conductivity, and surface tailorability. The ZrO(2)/carbon nanocomposites were characterized by thermogravimetric analysis, nitrogen-adsorption porosimetry, helium pychnometry, powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Comparison was made with templated mesoporous carbon samples prepared without addition of ZrO(2). Treatment of the nanocomposites with phenylphosphonic acid was undertaken and shown to result in robust binding of the phosphonic acid to the surface of ZrO(2) particles. Incorporation of nanoscale ZrO(2) surfaces in the mesoporous composite skeleton offers unique promise as a means for anchoring organophosphonates inside of pores through formation of robust covalent Zr-O-P bonds.
- Published
- 2012
43. Cellular Uptake Mechanism of an Inorganic Nanovehicle and Its Drug Conjugates: Enhanced Efficacy Due To Clathrin-Mediated Endocytosis
- Author
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Jae-Min Oh, Soo Jin Choi, Jin-Ho Choy, and Sang-Tae Kim
- Subjects
musculoskeletal diseases ,Cell Survival ,media_common.quotation_subject ,Endocytic cycle ,Biomedical Engineering ,Pharmaceutical Science ,Antineoplastic Agents ,Bioengineering ,Endocytosis ,Clathrin ,Cell Line ,X-Ray Diffraction ,immune system diseases ,Humans ,heterocyclic compounds ,skin and connective tissue diseases ,Internalization ,Chromatography, High Pressure Liquid ,Dynamin ,media_common ,Pharmacology ,chemistry.chemical_classification ,biology ,Chemistry ,Organic Chemistry ,G1 Phase ,Receptor-mediated endocytosis ,Nanostructures ,Biochemistry ,Transferrin ,Drug delivery ,Microscopy, Electron, Scanning ,biology.protein ,Biophysics ,Biotechnology - Abstract
We present the mechanism for the cellular uptake of layered double hydroxide (LDH) nanoparticles that are internalized into MNNG/HOS cells principally via clathrin-mediated endocytosis. The intracellular LDHs are highly colocalized with not only typical endocytic proteins, such as clathrin heavy chain, dynamin, and eps15, but also transferrin, a marker of the clathrin-mediated process, suggesting their specific internalization pathway. LDHs loaded with an anticancer drug (MTX-LDH) were also prepared to confirm the efficacy of LDHs as drug delivery systems. The cellular uptake of MTX was higher in MTX-LDH-treated cells than in MTX-treated cells, giving a lower IC50 value for MTX-LDH than for MTX only. The inhibition of the cell cycle was greater for MTX-LDH than for MTX only. This result clearly shows that the internalization of LDH nanoparticles via clathrin-mediated endocytosis may allow the efficient delivery of MTX-LDH in cells and thus enhance drug efficacy.
- Published
- 2006
44. Investigation of Crystallization in a Jet Y-Mixer by a Hybrid Computational Fluid Dynamics and Process Simulation Approach
- Author
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Hyoun-Soo Kim, Young-Jae Choi, Sung-Taik Chung, and Min Oh
- Subjects
Jet (fluid) ,Supersaturation ,business.industry ,Chemistry ,Nucleation ,Thermodynamics ,Crystal growth ,General Chemistry ,Computational fluid dynamics ,Condensed Matter Physics ,law.invention ,law ,Fluid dynamics ,General Materials Science ,Crystallization ,Diffusion (business) ,business - Abstract
A hybrid approach incorporating a computational fluid dynamics (CFD) package and process simulation tool was employed to simulate the steady-state crystallization of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in a Y-mixer crystallizer. Mixing effect was intensively investigated through the three-dimensional spatial distributions of velocity, supersaturation, kinetic rates, mean crystal size, coefficient of variation, and yield. The hybrid approach could predict the literature experimental data on mean crystal size, coefficient of variation, and production rate at the exit of the outlet tube reasonably by adjusting three factors (K, Ehet, and f) for nucleation and crystal growth that are difficult to determine by experiment or theory. It was found that even in a small-scale Y-mixer crystallizer a mixing effect was evident and that nuclei were generated dominantly by primary homogeneous nucleation and were grown at the rate controlled by both bulk diffusion and surface integration for the experimental supersaturation range.
- Published
- 2005
45. Structure of New Layered Oxides MII0.5LaTiO4 (M = Co, Cu, and Zn) Synthesized by the Ion-Exchange Reaction
- Author
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† Jong-Min Oh, ‡ and Jung-Chul Park, Sun Young Kim, and Song-Ho Byeon
- Subjects
Ion exchange ,Rietveld refinement ,General Chemical Engineering ,Inorganic chemistry ,Neutron diffraction ,chemistry.chemical_element ,General Chemistry ,Crystal structure ,Copper ,Ion ,Tetragonal crystal system ,Crystallography ,chemistry ,Materials Chemistry ,Cobalt - Abstract
New layered oxides MII0.5LaTiO4 (M = Co, Cu, and Zn) were synthesized via the ion-exchange reaction of parent NaLaTiO4 in molten salts at 300−450 °C. Eutectic-like mixtures of MCl2 (M = Co and Cu) and KCl were required for the 1:2 exchange reaction of divalent cobalt and copper ions for monovalent sodium ion at low temperature. The structures of these phases were determined by Rietveld refinement of the powder X-ray and neutron diffraction data. The bright violet (M = Co), bright brown (M = Cu), and white (M = Zn) compounds crystallize in the tetragonal structure (space group P4/nmm) with cell constants a = 3.71379(6), 3.73606(9), and 3.7234(1) A and c = 12.7016(2), 12.0736(3), and 12.7488(6) A, respectively. Similarly to the structure of parent NaLaTiO4, a strongly distorted coordination environment for the Ti atom is revealed. In contrast, the transition metal atoms statistically occupy one-half of the distorted tetrahedral sites rather than the nine-coordinated sites in the interlayer spaces. Successfu...
- Published
- 2002
46. Enzymatic Process for High-Yield Turanose Production and Its Potential Property as an Adipogenesis Regulator
- Author
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Park, Min-Oh, primary, Lee, Byung-Hoo, additional, Lim, Eunjin, additional, Lim, Ji Ye, additional, Kim, Yuri, additional, Park, Cheon-Seok, additional, Lee, Hyeon Gyu, additional, Kang, Hee-Kwon, additional, and Yoo, Sang-Ho, additional
- Published
- 2016
- Full Text
- View/download PDF
47. Efficient Biocatalytic Production of Cyclodextrins by Combined Action of Amylosucrase and Cyclodextrin Glucanotransferase
- Author
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Koh, Dong-Wan, primary, Park, Min-Oh, additional, Choi, Seong-Won, additional, Lee, Byung-Hoo, additional, and Yoo, Sang-Ho, additional
- Published
- 2016
- Full Text
- View/download PDF
48. Synthesis of ABA Triblock Copolymers of Styrene and p-Methylstyrene by Living Cationic Polymerization Using the Bifunctional Initiating System 1,4-Bis(1-chloroethyl)benzene/SnCl4 in the Presence of 2,6-Di-tert-butylpyridine
- Author
-
Sam-Kwon Choi, Jae-Min Oh, Su-Jin Kang, and Oh-Sig Kwon
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,Organic Chemistry ,2,6-Di-tert-butylpyridine ,Polymer ,Living cationic polymerization ,Styrene ,Inorganic Chemistry ,chemistry.chemical_compound ,Monomer ,chemistry ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Benzene ,Bifunctional - Abstract
ABA triblock copolymers of styrene and p-methylstyrene were prepared by living cationic polymerization using a bifunctional initiating system in the presence of 2,6-di-tert-butylpyridine, which, as a proton-trapping agent, suppressed the initiation by adventitious impurities and thus enhanced the livingness of the styrene monomers. By using these characteristics, triblock copolymers of styrene and p-methylstyrene could be prepared easily. The polymers showed the same molecular weight as the theoretical value and narrow and unimodal molecular weight distributions (MWDs)
- Published
- 1995
49. Synthesis of Unsymmetrically .alpha.-Substituted Poly(dipropargyl ether) Derivatives by Metathesis Catalysts
- Author
-
Won-Chul Lee, Hyung-Jong Lee, Yeong-Soon Gal, Sam-Kwon Choi, Jae-Min Oh, and Sung-Ho Jin
- Subjects
Chloroform ,Polymers and Plastics ,Organic Chemistry ,Ether ,Metathesis ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,Monomer ,chemistry ,Polymer chemistry ,Propargyl ,Materials Chemistry ,Solubility ,Tetrahydrofuran - Abstract
Soluble and unsymmetrically cyclized poly(dipropargyl ether) derivatives bearing α-substituents were synthesized and characterized. The monomers were propargyl α-substituted (methyl, pentyl, methyl phenyl, cyclohexyl) propargyl ethers. Polymerizations were carried out with transition metal catalysts. It was found that MoCl 5 -based catalysts were very effective for the cyclopolymerization of α-substituted dipropargyl ethers. The solubility of poly(dipropargyl ether)s was remarkably improved by incorporation of α-substituent groups. The resulting polymers exhibited good solubility in common organic solvents such as tetrahydrofuran, chloroform, DMF. The structure of the products was confirmed by IR, UV-visible, and 1 H- and 13 C-NMR spectroscopy. All of the polymers were amorphous, reddish solids and their weight average molecular weights were in the range of 24.3 x 10 3 -73 x 10 3 . The oxidative stability was dependent on the α-substituent groups of the poly(dipropargyl ether)s. The electrical conductivities of iodine-doped poly(dipropargyl ether) derivatives were 10 -4 -10 -2 s/cm.
- Published
- 1995
50. Synthesis and Characterization of a Novel Electron-Acceptor Polymer Based on a Poly(1,6-heptadyine) Main Chain
- Author
-
Jongwook Park, Jae-Min Oh, Ji-Hoon Lee, and Sam-Kwon Choi
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,Chemistry ,Organic Chemistry ,Nitro compound ,Polymer ,Electron acceptor ,Metathesis ,Characterization (materials science) ,Catalysis ,Inorganic Chemistry ,Chain (algebraic topology) ,Transition metal ,Polymer chemistry ,Materials Chemistry - Abstract
The synthesis and charge transfert complex properties of a nover electron acceptor polymer (poly[2-([3,5-dinitrobenzoyl]oxy)ethyl dipropergyl acetate]), obtained by metathesis cyclopolymerization with various transition metal catalysts, are described
- Published
- 1995
Catalog
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