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103. Symmetry Transitions of Polymer-Grafted Nanoparticles: Grafting Density Effect

Author

Yun, Hongseok, primary, Yu, Ji Woong, additional, Lee, Young Jun, additional, Kim, Jin-Seong, additional, Park, Chan Ho, additional, Nam, Chongyong, additional, Han, Junghun, additional, Heo, Tae-Young, additional, Choi, Soo-Hyung, additional, Lee, Doh C., additional, Lee, Won Bo, additional, Stein, Gila E., additional, and Kim, Bumjoon J., additional

Published
2019
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106. The genome-scale metabolic network analysis of Zymomonas mobilis ZM4 explains physiological features and suggests ethanol and succinic acid production strategies

Author

Kim Tae, Park Jong, Lee Kyung, Yun Hongseok, and Lee Sang

Subjects
Microbiology, QR1-502
Abstract

Abstract Background Zymomonas mobilis ZM4 is a Gram-negative bacterium that can efficiently produce ethanol from various carbon substrates, including glucose, fructose, and sucrose, via the Entner-Doudoroff pathway. However, systems metabolic engineering is required to further enhance its metabolic performance for industrial application. As an important step towards this goal, the genome-scale metabolic model of Z. mobilis is required to systematically analyze in silico the metabolic characteristics of this bacterium under a wide range of genotypic and environmental conditions. Results The genome-scale metabolic model of Z. mobilis ZM4, ZmoMBEL601, was reconstructed based on its annotated genes, literature, physiological and biochemical databases. The metabolic model comprises 579 metabolites and 601 metabolic reactions (571 biochemical conversion and 30 transport reactions), built upon extensive search of existing knowledge. Physiological features of Z. mobilis were then examined using constraints-based flux analysis in detail as follows. First, the physiological changes of Z. mobilis as it shifts from anaerobic to aerobic environments (i.e. aerobic shift) were investigated. Then the intensities of flux-sum, which is the cluster of either all ingoing or outgoing fluxes through a metabolite, and the maximum in silico yields of ethanol for Z. mobilis and Escherichia coli were compared and analyzed. Furthermore, the substrate utilization range of Z. mobilis was expanded to include pentose sugar metabolism by introducing metabolic pathways to allow Z. mobilis to utilize pentose sugars. Finally, double gene knock-out simulations were performed to design a strategy for efficiently producing succinic acid as another example of application of the genome-scale metabolic model of Z. mobilis. Conclusion The genome-scale metabolic model reconstructed in this study was able to successfully represent the metabolic characteristics of Z. mobilis under various conditions as validated by experiments and literature information. This reconstructed metabolic model will allow better understanding of Z. mobilis metabolism and consequently designing metabolic engineering strategies for various biotechnological applications.

Published
2010
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125. Hydrogen Sensors Based on MoS2Hollow Architectures Assembled by Pickering Emulsion

Author

Park, Chan Ho, Koo, Won-Tae, Lee, Young Jun, Kim, Yoon Hwa, Lee, Jiyoung, Jang, Ji-Soo, Yun, Hongseok, Kim, Il-Doo, and Kim, Bumjoon J.

Abstract

For rapid hydrogen gas (H2) sensing, we propose the facile synthesis of the hollow structure of Pt-decorated molybdenum disulfide (h-MoS2/Pt) using ultrathin (mono- or few-layer) two-dimensional nanosheets. The controlled amphiphilic nature of MoS2surface produces ultrathin MoS2NS-covered polystyrene particles viaone-step Pickering emulsification. The incorporation of Pt nanoparticles (NPs) on the MoS2, followed by pyrolysis, generates the highly porous h-MoS2/Pt. This hollow hybrid structure produces sufficiently permeable pathways for H2and maximizes the active sites of MoS2, while the Pt NPs on the hollow MoS2induce catalytic H2spillover during H2sensing. The h-MoS2/Pt-based chemiresistors show sensitive H2sensing performances with fast sensing speed (response, 8.1 s for 1% of H2and 2.7 s for 4%; and recovery, 16.0 s for both 1% and 4% H2at room temperature in the air). These results mark the highest H2sensing speed among 2D material-based H2sensors operated at room temperature in air. Our fabrication method of h-MoS2/Pt structure through Pickering emulsion provides a versatile platform applicable to various 2D material-based hollow structures and facilitates their use in other applications involving surface reactions.

Published
2020
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126. Effect of Polymeric In SituStabilizers on Dispersion Homogeneity of Nanofillers and Thermal Conductivity Enhancement of Composites

Author

Lim, Hongjin, Islam, Md. Akherul, Hossain, Md Monir, Yun, Hongseok, Kim, Myung Jong, Seo, Tae Hoon, Hahn, Jae Ryang, Kim, Bumjoon J., and Jang, Se Gyu

Abstract

Boron nitride (BN) nanofiller-based polymer composites have been considered promising candidates for efficient heat-dissipating packaging materials because of their superior thermal conductivity, mechanical strength, and chemical resistance. However, strong aggregation of the BN nanofillers in the composite matrix as well as the difficulty in the modification of the chemically inert surface prevents their effective use in polymer composites. Herein, we report an effective method by using in situstabilizers to achieve homogeneous dispersion of boron nitride (BN) nanofillers in an epoxy-based polymeric matrix and demonstrate their use as efficient heat-dissipating materials. Poly(4-vinylpyridine) (P4VP) is designed and added into the epoxy resin to produce in situstabilizers during preparation of hexagonal BNs (h-BNs) and BN nanotubes (BNNTs) dispersion. In-depth experimental and theoretical studies indicated that the homogeneous distribution of BN nanofillers in epoxy composites achieved by using the in situstabilizer enhanced the thermal conductivity of the composite by ∼27% at the same concentration of the BN nanofillers. In addition, the thermal conductivity of the h-BN/epoxy composite (∼3.3 W/mK) was dramatically improved by ∼48% (4.9 W/mK) when the homogeneously dispersed BNNTs (∼1.8 vol %) were added. The concept of the proposed in situstabilizer can be further utilized to prepare the epoxy composites with the homogeneous distribution of BN nanofillers, which is critical for reproducible and position-independent composite properties.

Published
2020
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131. High-strength magnetically switchable plasmonic nanorods assembled from a binary nanocrystal mixture

Author

Zhang, Mingliang, primary, Magagnosc, Daniel J., additional, Liberal, Iñigo, additional, Yu, Yao, additional, Yun, Hongseok, additional, Yang, Haoran, additional, Wu, Yaoting, additional, Guo, Jiacen, additional, Chen, Wenxiang, additional, Shin, Young Jae, additional, Stein, Aaron, additional, Kikkawa, James M., additional, Engheta, Nader, additional, Gianola, Daniel S., additional, Murray, Christopher B., additional, and Kagan, Cherie R., additional

Published
2016
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133. Mechanisms for High Selectivity in the Hydrodeoxygenation of 5-Hydroxymethylfurfural over PtCo Nanocrystals

Author

Luo, Jing, primary, Yun, Hongseok, additional, Mironenko, Alexander V., additional, Goulas, Konstantinos, additional, Lee, Jennifer D., additional, Monai, Matteo, additional, Wang, Cong, additional, Vorotnikov, Vassili, additional, Murray, Christopher B., additional, Vlachos, Dionisios G., additional, Fornasiero, Paolo, additional, and Gorte, Raymond J., additional

Published
2016
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134. Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy

Author

He, Kai, primary, Zhang, Sen, additional, Li, Jing, additional, Yu, Xiqian, additional, Meng, Qingping, additional, Zhu, Yizhou, additional, Hu, Enyuan, additional, Sun, Ke, additional, Yun, Hongseok, additional, Yang, Xiao-Qing, additional, Zhu, Yimei, additional, Gan, Hong, additional, Mo, Yifei, additional, Stach, Eric A., additional, Murray, Christopher B., additional, and Su, Dong, additional

Published
2016
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136. Genetic Characteristics of Polycythemia Vera and Essential Thrombocythemia in Korean Patients

Author

Yoo, Eun-Hyung, primary, Park, Kyung-Jin, additional, Won, Hong-Hee, additional, Park, Jun-Hee, additional, Park, Jong-Ho, additional, Lee, Seung-Tae, additional, Kim, Hee-Jin, additional, Bang, Soo-Mee, additional, Chi, Hyun-Sook, additional, Jung, Chul Won, additional, Kim, Sun-Hee, additional, Yun, Hongseok, additional, Sun, Choong-Hyun, additional, Park, Inho, additional, Lee, Seungmook, additional, Lee, Clarence, additional, Merriman, Barry, additional, Luo, Raymond, additional, Tan, Eileen Hwee Hong, additional, Park, Keun-Joon, additional, Yoo, Na-Kyung, additional, Kang, Jason J., additional, and Kim, Jong-Won, additional

Published
2016
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138. Symmetry Transitions of Polymer-Grafted Nanoparticles: Grafting Density Effect

Author

Yun, Hongseok, Yu, Ji Woong, Lee, Young Jun, Kim, Jin-Seong, Park, Chan Ho, Nam, Chongyong, Han, Junghun, Heo, Tae-Young, Choi, Soo-Hyung, Lee, Doh C., Lee, Won Bo, Stein, Gila E., and Kim, Bumjoon J.

Abstract

We examined the packing structure of polystyrene-coated gold nanoparticles (Au@PS) as a function of grafting density. A series of Au@PS nanoparticles with grafting densities in the range of 0.51–1.94 chains nm–2were prepared by a ligand exchange process using thiol-terminated PS and then self-assembled at a liquid–air interface. We observed a transition from disordered to body-centered cubic (bcc) to face-centered cubic (fcc) arrangements with increasing grafting density, even though the ligand length-to-core radius ratio (λ) was as high as 3.0, a condition that typically favors nonclose-packed bcc symmetry in the self-assembly of hard nanoparticles. To explain this phenomenon, we define λeffto include the concentrated polymer brush regime as part of the “hard core”, which predicts that the softness of Au@PS nanoparticles is reduced from 1.53 to 0.14 in a theta solvent as the grafting density increases from 0.51 to 1.94 chains nm–2. This new definition of λ can also predict the effective radii of nanoparticles using the established optimal packing model. The experimental findings are supported by a combination of coarse-grained molecular dynamics simulation and adaptive common neighbor analysis, which show that changes in grafting density can drive the observed transitions in nanoparticle packing. These studies provide new insights for controlling the self-assembled symmetries of polymer-coated nanocrystals using a simple ligand exchange process to tune particle softness.

Published
2024
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139. Analysis of clinical and genomic profiles of therapy-related myeloid neoplasm in Korea

Author

Yun, Jiwon, Song, Hyojin, Kim, Sung-Min, Kim, Soonok, Kwon, Seok Ryun, Lee, Young Eun, Jeong, Dajeong, Park, Jae Hyeon, Kwon, Sunghoon, Yun, Hongseok, and Lee, Dong Soon

Abstract

Background: Therapy-related myeloid neoplasm (T-MN) rarely occurs among cancer survivors, and was characterized by poor prognosis. T-MN has germline predisposition in a considerable proportion. Here, clinical characteristics and germline/somatic variant profiles in T-MN patients were investigated, and the findings were compared with those of previous studies. Methods: A review of medical records, cytogenetic study, targeted sequencing by next-generation sequencing, and survival analysis were performed on 53 patients with T-MN at a single institution in Korea. Results: The patients were relatively younger compared to T-MN patients in other studies. Our T-MN patients showed a high frequency of complex karyotypes, −5/del(5q), and −7/del(7q), which was similar to the Japanese study group but higher than the Australian study group. The most common primary disease was non-Hodgkin lymphoma, followed by breast cancer. The detailed distributions of primary diseases were different across study groups. Seven patients (13.2%) harbored deleterious presumed/potential germline variants in cancer predisposition genes (CPG) such as BRIP1, CEBPA, DDX41, FANCM, NBN, NF1, and RUNX1. In the somatic variant profile, TP53was the most frequently mutated gene, which was consistent with the previous studies about T-MN. However, the somatic variant frequency in our study group was lower than in other studies. Adverse factors for overall survival were male sex, older age, history of previous radiotherapy, previous longer cytotoxic therapy, and −5/del(5q). Conclusion: The findings of our study corroborate important information about T-MN patients. As well as a considerable predisposition to CPG, the clinical characteristics and somatic variant profile showed distinctive patterns. Germline variant testing should be recommended for T-MN patients. If the T-MN patients harbor pathogenic germline variants, the family members for stem cell donation should be screened for carrier status through germline variant testing to avoid donor-derived myeloid neoplasm. For the prediction of the prognosis in T-MN patients, sex, age, past treatment history, and cytogenetic findings can be considered.

Published
2023
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141. A scientific treatment approach for acute mast cell leukemia: using a strategy based on next-generation sequencing data

Author

Youk, Jeonghwan, primary, Koh, Youngil, additional, Kim, Ji-Won, additional, Kim, Dae-Yoon, additional, Park, Hyunkyung, additional, Jung, Woo June, additional, Ahn, Kwang-Sung, additional, Yun, Hongseok, additional, Park, Inho, additional, Sun, Choong-Hyun, additional, Lee, Seungmook, additional, and Yoon, Sung-Soo, additional

Published
2016
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142. Synthesis and characterization of transition metal based metal oxide and metallic nanocrystals for AC magnetic devices and catalysis

Author

Yun, Hongseok and Yun, Hongseok

Abstract

The d-block elements are very important in magnetics, electronics, catalysis, and biological systems. The synthesis and characterization of nearly monodisperse d-block element based nanocrystals with a precise control over the size, composition, and shape are important to utilize the nanocrystals in such applications. The goals of my thesis are to synthesize d-block transition metal based nanocrystals and understand their magnetic and catalytic properties. I present the size- and composition-dependent AC magnetic permeability of superparamagnetic iron oxide nanocrystals for radio frequency applications. The nanocrystals are synthesized through high-temperature solvothermal decomposition, and their stoichiometry is determined by Mössbauer spectroscopy. Size-dependent magnetic permeability is observed in maghemite nanocrystals, while as-synthesized, magnetite-rich, iron oxide nanocrystals do not show size dependence due to the inhomogeneous crystal structure of the as-synthesized nanocrystals. The saturation magnetization of iron oxide nanocrystals is increased by doping of non-magnetic Zn2+ into A site of ferrite, resulting the enhancement of the real part of the magnetic permeability of Zn0.25Fe2.75O4 nanocrystals by twofold compared to that of similarly sized ferrite nanocrystals. The integration of 12.3 nm Zn0.25Fe2.75O4 nanocrystals into a microfabricated toroidal inductor and a solenoid inductor yield higher quality factors than air core inductors with the same geometries. The ligand exchange with dendrimers reduces the blocking temperature of Mn0.08Zn0.33Fe2.59O4 nanocrystal, indicating the decrease of dipolar coupling between nanocrystals. The study on MnxFe3-xO4 and CoxFe3-xO4 nanocrystals shows a clear difference in DC and AC magnetic behaviors of soft and hard magnetic nanocrystals. The inductor with zinc ferrite nanocrystal core is embedded into a power converter and its temperature dependent energy efficiency is measured. The energy efficiency of a power

Published
2015

144. Integrated genomic analyses identify frequent gene fusion events and VHL inactivation in gastrointestinal stromal tumors

Author

Kang, Guhyun, primary, Yun, Hongseok, additional, Sun, Choong-Hyun, additional, Park, Inho, additional, Lee, Seungmook, additional, Kwon, Jekeun, additional, Do, Ingu, additional, Hong, Min Eui, additional, Van Vrancken, Michael, additional, Lee, Jeeyun, additional, Park, Joon Oh, additional, Cho, Jeonghee, additional, Kim, Kyoung-Mee, additional, and Sohn, Tae Sung, additional

Published
2015
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145. Fluorescent Block Copolymer-MoS2 Nanocomposites for Real-Time Photothermal Heating and Imaging.

Author

Park, Chan Ho, Yun, Hongseok, Yang, Hyunseung, Lee, Junhyuk, and Kim, Bumjoon J.

Subjects
*BLOCK copolymers, *CHEMICAL synthesis, *MOLYBDENUM sulfides, *SYNTHESIS of Nanocomposite materials, *FLUORESCENT polymers, *LIGHT scattering, *PHOTOTHERMAL spectroscopy
Abstract

Novel self-monitoring photothermal (PT) agents are developed using optothermally responsive block copolymer-MoS2 composites (BCP-MoS2), which enable simultaneous PT heating and imaging of temperature profiles. In particular, upon near-infrared light exposure, PT energy from MoS2 successfully increases local temperature and induces thermally activated conformational transitions of the BCP on MoS2. This leads to fluorescent signal changes caused by distance-dependent Förster resonance energy transfer between the BCP and MoS2. Importantly, it is demonstrated that the use of BCP-MoS2 for PT heating and optical mapping is fully reversible with excellent stability. The detailed mechanism of the responsive behavior of BCP-MoS2 is elucidated by measurements of time-resolved fluorescence and dynamic light scattering. In addition, the BCP-MoS2 system is integrated into organogel matrices to demonstrate its potential as aportable, self-monitoring PT system suitable for biological and environmental applications. [ABSTRACT FROM AUTHOR]

Published
2017
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146. Korean Precision Medicine Networking Group study of molecular profiling guided therapy based on genomic alterations in advanced solid tumors (KOSMOS) II (KCSG AL 22-09).

Author

Kim, Sun Young, Kim, Jee Hyun, Kim, Tae-Yong, Park, Sook Ryun, Yoon, Shinkyo, Lee, Soohyeon, Lee, Se-Hoon, Kim, Tae Min, Han, Sae-Won, Yun, Hongseok, Lee, Sejoon, Kim, Jihun, Choi, Yoon-La, Choi, Kui Son, Chae, Heejung, Ryu, Hyewon, Lee, Gyeong-Won, Zang, Dae Young, and Ahn, Joong

Published
2023
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147. A Technology Overview of the PowerChip Development Program

Author

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology. Microsystems Technology Laboratories, Massachusetts Institute of Technology. Research Laboratory of Electronics, Perreault, David J., Araghchini, Mohammad, Jin, Donghyun, Lim, Seungbum, Lu, Bin, Piedra, Daniel, Sun, Min, del Alamo, Jesus A., DesGroseilliers, Gary, Lang, Jeffrey H., Otten, David M., Palacios, Tomas, Chen, Jun, Doan-Nguyen, Vicky, Harburg, Daniel V., Kim, Jungkwun, Kim, Min Soo, Qiu, Jizheng, Ranson, John, Yu, Xuehong, Yun, Hongseok, Allen, Mark G., Herrault, Florian, Levey, Christopher G., Murray, Christopher B., Sullivan, Charles R., Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology. Microsystems Technology Laboratories, Massachusetts Institute of Technology. Research Laboratory of Electronics, Perreault, David J., Araghchini, Mohammad, Jin, Donghyun, Lim, Seungbum, Lu, Bin, Piedra, Daniel, Sun, Min, del Alamo, Jesus A., DesGroseilliers, Gary, Lang, Jeffrey H., Otten, David M., Palacios, Tomas, Chen, Jun, Doan-Nguyen, Vicky, Harburg, Daniel V., Kim, Jungkwun, Kim, Min Soo, Qiu, Jizheng, Ranson, John, Yu, Xuehong, Yun, Hongseok, Allen, Mark G., Herrault, Florian, Levey, Christopher G., Murray, Christopher B., and Sullivan, Charles R.

Abstract

The PowerChip research program is developing technologies to radically improve the size, integration, and performance of power electronics operating at up to grid-scale voltages (e.g., up to 200V) and low-to-moderate power levels (e.g., up to 50W) and demonstrating the technologies in a high-efficiency light-emitting diode driver, as an example application. This paper presents an overview of the program and of the progress toward meeting the program goals. Key program aspects and progress in advanced nitride power devices and device reliability, integrated high-frequency magnetics and magnetic materials, and high-frequency converter architectures are summarized.

Published
2014

149. Size- and Composition-Dependent Radio Frequency Magnetic Permeability of Iron Oxide Nanocrystals

Author

Yun, Hongseok, primary, Liu, Xiyu, additional, Paik, Taejong, additional, Palanisamy, Duraivelan, additional, Kim, Jungkwun, additional, Vogel, William D., additional, Viescas, Arthur J., additional, Chen, Jun, additional, Papaefthymiou, Georgia C., additional, Kikkawa, James M., additional, Allen, Mark G., additional, and Murray, Christopher B., additional

Published
2014
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150. A Technology Overview of the PowerChip Development Program

Author

Araghchini, Mohammad, primary, Chen, Jun, additional, Doan-Nguyen, Vicky, additional, Harburg, Daniel V., additional, Jin, Donghyun, additional, Kim, Jungkwun, additional, Kim, Min Soo, additional, Lim, Seungbum, additional, Lu, Bin, additional, Piedra, Daniel, additional, Qiu, Jizheng, additional, Ranson, John, additional, Sun, Min, additional, Yu, Xuehong, additional, Yun, Hongseok, additional, Allen, Mark G., additional, Alamo, Jesús A., additional, DesGroseilliers, Gary, additional, Herrault, Florian, additional, Lang, Jeffrey H., additional, Levey, Christopher G., additional, Murray, Christopher B., additional, Otten, David, additional, Palacios, Tomás, additional, Perreault, David J., additional, and Sullivan, Charles R., additional

Published
2013
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