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Bongsoo Lee,양지원,Gang-Guk Choi,Yoon-E. Choi,Minji Sung,Min S. Park 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.6
Microalgae-derived biomass has been considered as the most promising candidate for next generation biofueldue to its sustainability and biodegradability. In this study, microalgal strain Chlamydmonas reinhardtii was randomlymutagenized by using a chemical mutagen, ethyl methane sulfonate (EMS) to create mutants showing enhanced lipidproduction. We identified three random mutants that displayed high lipid production in the screening using Nile redstaining. Among those, mutant #128 was selected as candidate for further studies. Our flow cytometry and confocalmicroscopy analysis revealed that mutant #128 contains larger and more abundant lipid bodies than that of wild-type. Moreover, mutant #128 showed 1.4-fold increased fatty acid methyl ester (FAME) content compared to wild-type undernitrogen depleted condition. In addition, mutant #128 grew faster and accumulated more biomass, resulting in highlipid production. 2D gel electrophoresis and MALDI-TOF analysis used for gene targeting revealed that β-subunit ofmitochondrial ATP Synthase and two-component response regulator PilR may be involved in enhanced characteristicsof mutant #128. These results show the possibilities of EMS mediated random mutagenesis in generation of mutantsto produce high amount of lipid as well as further study for molecular mechanism of mutants.
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>
Lee, Hyo Sang,Song, Hyeng Gun,Jung, Hyeseung,Kim, Myung Hwa,Cho, Changsoon,Lee, Jung-Yong,Park, Sungnam,Son, Hae Jung,Yun, Hui-Jun,Kwon, Soon-Ki,Kim, Yun-Hi,Kim, BongSoo American Chemical Society 2016 Macromolecules Vol.49 No.20
<P>The photostability of donor-acceptor (D-A) polymers remains a critical issue despite recent improvements in the power conversion efficiencies (PCEs) of organic photovoltaic (OPV) cells. We report the synthesis of three highly photostable polymers (PDTBDT-BZ, PDTBDT-BZF, and PDTBDT-BZF(2)) and their suitability for use in high-performance OPV cells. Under 1 sunlight of illumination in air for 10 h, these polymer films demonstrated remarkably high photostability compared to that of PTB7, a representative polymer in the OPV field. While the PDTBDT-BZ, PDTBDT-BZF, and PDTBDT-BZF2 polymer films maintained 97, 90, and 96% photostability, respectively, a PTB7 film exhibited only 38% photo stability under the same conditions. We ascribed the high photostability of the polymers to both the intrinsically photostable chemical moieties and the dense packing of alkyl side chains and planar backbone polymer chains, which prevents oxygen diffusion into the PDTBDT-BZ films. This work demonstrates the high photostability of planar PDTBDT-BZ series polymers composed of photostable DTBDT and BZ moieties and suggests a design rule to synthesize highly photostable photovoltaic materials.</P>
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>
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>
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>
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>
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>