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- 저자 : Bongsoo Lee (검색결과 314 건)
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Lee, Wang Sik,Cho, Hyun-Ju,Kim, Eungwang,Huh, Yang Hoon,Kim, Hyo-Jeong,Kim, Bongsoo,Kang, Taejoon,Lee, Jeong-Soo,Jeong, Jinyoung The Royal Society of Chemistry 2019 Nanoscale Vol.11 No.7
<P>As nano- and micro-sized plastics accumulate in the environment and the food chain of animals, including humans, it is imperative to assess the effects of nanoplastics in living organisms in a systematic manner, especially because of their ability to adsorb potential toxicants such as pollutants, heavy metals, and organic macromolecules that coexist in the environment. Using the zebrafish embryo as an animal model, we investigated the bioaccumulation and <I>in vivo</I> toxicity of polystyrene (PS) nanoplastics individually or in combination with the Au ion. We showed that smaller PS nanoplastics readily penetrated the chorion and developing embryos and accumulated throughout the whole body, mostly in lipid-rich regions such as in yolk lipids. We also showed that PS nanoplastics induced only marginal effects on the survival, hatching rate, developmental abnormalities, and cell death of zebrafish embryos but that these effects were synergistically exacerbated by the Au ion in a dose- and size-dependent manner. Such exacerbation of toxicity was well correlated with the production of reactive oxygen species and the pro-inflammatory responses synergized by the presence of PS, supporting the combined toxicity of PS and Au ions. The synergistic effect of PS on toxicity appeared to relate to mitochondrial damage as determined by ultrastructural analysis. Taken together, the effects of PS nanoplastics were marginal but could be a trigger for exacerbating the toxicity induced by other toxicants such as metal ions.</P>
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Lee, Hyo-Sang,Lee, Joong Suk,Jung, A-Ra,Cha, Wonsuk,Kim, Hyunjung,Son, Hae Jung,Cho, Jeong Ho,Kim, BongSoo Elsevier 2016 Polymer Vol.105 No.-
<P><B>Abstract</B></P> <P>We synthesized a planar pDPPTTi-OD polymer based on diketopyrrolopyrrole (DPP) and thieno [2,3-<I>b</I>]thiophene (TTi) and investigated the electrical properties of the pDPPTTi-OD polymer. pDPPTTi-OD films displayed a low optical bandgap of 1.57 eV, and HOMO and LUMO levels of −5.40 and −3.74 eV, respectively. The 150°C-annealed pDPPTTi-OD films showed a high hole mobility of 0.16 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP> in organic thin-film transistor (OTFT) devices. The photovoltaic properties of polymer solar cells (PSCs) incorporating the pDPPTTi-OD were also measured. A pDPPTTi-OD:PC<SUB>71</SUB>BM blend film was spin-coated at 25, 70 and 90 °C. High-temperature processing significantly improved the power conversion efficiency of PSCs by effectively reducing the PC<SUB>71</SUB>BM domain sizes, which improved the miscibility between pDPPTTi-OD and PC<SUB>71</SUB>BM. This work demonstrated that the TTi moiety is a useful donor building block for high- performance D–A type polymers in OTFTs and PSCs, and that processing temperatures should be controlled to fully realize the materials' beneficial intrinsic properties.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A planar pDPPTTi-OD polymer based on diketopyrrolopyrrole (DPP) and thieno [2,3-<I>b</I>]thiophene (TTi) was synthesized. </LI> <LI> The 150 °C-annealed pDPPTTi-OD films showed a high hole mobility of 0.16 cm<SUP>2</SUP> V<SUP>−1</SUP>s<SUP>−1</SUP> in organic thin-film transistor devices. </LI> <LI> High-temperature processing significantly improved the power conversion efficiency of photovoltaic cells. </LI> <LI> A high voltage of 0.79 V was obtained, which is among the highest from DPP-based polymers. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Lee, JoongSuk,Son, Seon Kyoung,Song, Sanghoon,Kim, Hyunjung,Lee, Dong Ryoul,Kim, Kyungkon,Ko, Min Jae,Choi, Dong Hoon,Kim, BongSoo,Cho, Jeong Ho American ChemicalSociety 2012 Chemistry of materials Vol.24 No.7
<P>We investigated the performance of ambipolar field-effecttransistors based on a seriesof alternating low band gap polymers of oligothiophene and diketopyrrolopyrrole(DPP). The polymers contain oligothiophene units of terthiophene [T3]and thiophene-thienothiophene-thiophene [T2TT] and DPP units carryingbranched alkyl chains of 2-hexyldecyl [HD] or 2-octyldodecyl [OD].The structural variation allows us to do a systematic study on therelationship between the interchain stacking/ordering of semiconductingpolymers and their resulting device performance. On the basis of synchrotronX-ray diffraction and atomic force microscopy measurements on polymerfilms, we found that longer branched alkyl side chains, i.e., OD,and longer and more planar oligothiophene, i.e., T2TT, generate themore crystalline structures. Upon thermal annealing, the crystallinityof the polymers was largely improved, and polymers containing a longerbranched alkyl chain responded faster because longer alkyl chainshave larger cohesive forces than shorter chains. For all the polymers,excellent ambipolar behavior was observed with a maximum hole andelectron mobility of 2.2 and 0.2 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>, respectively.</P><P>We investigated the performance of ambipolarfield-effecttransistors based on a series of alternating low band gap polymersof oligothiophene and diketopyrrolopyrrole (pDPPT3-HD, pDPPT3-OD,pDPPT2TT-HD, and pDPPT2TT-OD). Herein, we report the high carriermobilities and the good correlation between the interchain stackingof polymers and their device performance.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2012/cmatex.2012.24.issue-7/cm2037487/production/images/medium/cm-2011-037487_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm2037487'>ACS Electronic Supporting Info</A></P>
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Bongsoo Lee,Kyoung Won Jang,Dong Hyun Cho,Wook Jae Yoo,Sang Hun Shin,Gye-Rae Tack,Soon-Cheol Chung,Sin Kim,Hyosung Cho,Byung Gi Park,Joo Hyun Moon,Siyong Kim IEEE 2008 IEEE transactions on nuclear science Vol.55 No.5
<P>In this study, a one-dimensional fiber-optic scintillating detector was developed for electron-beam therapy dosimetry. Each fiber-optic detector contains an organic scintillator as a sensitive volume and it is embedded and arrayed in a plastic phantom to measure one-dimensional high-energy electron-beam profiles of clinical linear accelerators. Plastic optical fibers guide the scintillating light which each detector probe generates to a photodiode array. The one-dimensional electron-beam profiles in the plastic phantom were measured in two different field sizes and for two electron-beam energies. Also, isodose and two-dimensional dose distributions in the plastic phantom were obtained using the one-dimensional scintillating detector array with two different electron beam energies.</P>
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Measurements of Cerenkov Lights Using Optical Fibers
Bongsoo Lee,Kyoung Won Jang,Wook Jae Yoo,Sang Hun Shin,Jinsoo Moon,Ki-Tek Han,Dayeong Jeon IEEE 2013 IEEE transactions on nuclear science Vol.60 No.2
<P>Optical fibers can be a medium to produce Cerenkov light due to their dielectric components, and radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, we measured and characterized gamma-ray induced Cerenkov light in silica optical fibers, a plastic optical fiber, and a plastic wavelength shifting fiber in order to select the adequate optical fiber for producing Cerenkov light. Also, we measured the intensity of Cerenkov light as functions of irradiated length, irradiation angle, and thickness of various scatterers using the chosen optical fiber.</P>
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Lee, Miyeon,Park, Changjun,Lee, Hyoban,Kim, Hongki,Kim, Sang Youl,In, Insik,Kim, Bongsoo IOP 2016 Nanotechnology Vol.27 No.47
<P>We report the characterization and formation of catechol-terminated molecules immobilized on gold nanoplates (Au NPLs) using N-(3,4-dihydroxyphenethyl)-2-mercaptoacetamide (Cat-EAA-SH). Single-crystalline Au NPLs, synthesized using a one-step chemical vapor transport method, have ultraclean and ultraflat surfaces that make Cat-EAA-SH molecules aligned into a well-ordered network of a large-scale. Topographic study of the catechol-terminated molecules on Au NPLs using atomic force microscopy showed more orderly orientation and higher density, leading to significantly higher adhesion as observed from local force–distance curves than those on other Au surfaces. These coherently aligned catechol-terminated molecules on the atomically smooth gold surface led to significanty more reproducible and thus more physico-chemically meaningful measurements than was possible before by employing rough gold surfaces.</P>
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Lee, Kee Doo,Seo, Se Won,Lee, Doh-Kwon,Kim, Honggon,Ko, Min Jae,Kim, BongSoo,Kim, Dong Hwan,Kim, Jin Young The Electrochemical Society 2013 ECS transactions Vol.50 No.51
<P>The effect of the heating rate during the sulfurization process on the properties of Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> (CZTS) thin film solar cells was investigated. A moderate heating rate of ~10 <SUP>o</SUP>C/min was found to result in a modest solar cell performance (2 %), whereas the higher heating rates resulted in worse performances. In the CZTS thin films annealed with the highest heating rate, the segregation of Cu atoms towards the outer surface of the films, which is believed to lead to shunting of the solar cells.</P>
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Lee, Sung-Sik,Kim, Bongsoo,Lee, Sungyul American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.36
<P>We present the structures, bonding characteristics, and infrared spectra of the gold surface (111)–Arg-Cys (Arg-Cys@Au(111)) complex calculated by a periodic plane wave DFT technique. We examine the detailed features of bonding between the gold surface and dipeptide. The dipeptide is revealed to form a covalent bond via the −SH group with 2–3 gold atoms, and also weak noncovalent interactions via the carboxyl and guanidine side chain lying more or less parallel to the gold surface. The S–H bond dissociates as a result of the S<SUP>–</SUP>–(Au)<SUB><I>n</I></SUB> bond formation, with the hydrogen atom binding to the guanidine moiety. The acidic proton stays at the carboxyl group in the most stable structure of Arg-Cys@Au(111). The calculated infrared spectra are compared with experimental observations reported by Petoral and Uvdal (<I>Colloids Surf., B</I> <B>2002</B>, <I>25</I>, 335).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-36/jp412438f/production/images/medium/jp-2013-12438f_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp412438f'>ACS Electronic Supporting Info</A></P>
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Lee, Myeongjae,Kim, Min Je,Ro, Suhee,Choi, Shinyoung,Jin, Seon-Mi,Nguyen, Hieu Dinh,Yang, Jeehye,Lee, Kyung-Koo,Lim, Dong Un,Lee, Eunji,Kang, Moon Sung,Choi, Jong-Ho,Cho, Jeong Ho,Kim, BongSoo American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.34
<P>High carrier mobilities have recently been achieved in polymer field effect transistors (FETs). However, many of these polymer FET devices require the use of chlorinated solvents such as chloroform (CF), chlorobenzene (CB), and odichlorobenzene (DCB) during fabrication. The use of these solvents is highly restricted in industry because of health and environmental issues. Here, we report the synthesis of a low band gap (1.43 eV, 870 nm) semiconducting polymer (PDPP2DT-F2T2) having a planar geometry, which can be readily processable with nonchlorinated solvents such as toluene (TOL), o-xylene (XY), and 1,2,4-trimethylbenzene (TMB). We performed structural characterization of PDPP2DT-F2T2 films prepared from different solvents, and the electrical properties of the films were measured in the context of FETs. The devices exhibited an ambipolar behavior with hole dominant transport. Hole mobilities increased with increasing boiling point (bp) of the nonchloririated solvents: 0.03, 0.05, and 0.10 cm(2) V-1 s' for devices processed using TOL, XY, and TMB, respectively. Thermal annealing further improved the FET performance. TMB-based polymer FETs annealed at 200 degrees C yielded a maximum hole mobility of 1.28 cm(2) s(-1), which is far higher than the 0.43 cm(2) V-1 s(-1) obtained from the CF-based device. This enhancement was attributed to increased interchain interactions as well as improved long-range interconnection between fibrous domains. Moreover, all of the nonchlorinated solutions generated purely edge-on orientations of the polymer chains, which is highly beneficial for carrier transport in FET devices. Furthermore, we fabricated an array of flexible TMBprocessed PDPP2DT-F2T2 FETs on the plastic PEN substrates. These devices demonstrated excellent carrier mobilities and negligible degradation after 300 bending cycles. Overall, we demonstrated that the organized assembly of polymer chains can be achieved by slow drying using high bp nonchlorinated solvents and a post thermal treatment. Furthermore, we showed that polymer FETs processed using high bp nonhalogenated solvents may outperform those processed using halogenated solvents.</P>
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