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마그네슘을 6 wt.% 함유한 알루미늄 합금의 저항 점용접성 평가
김민규(Mingyu Kim),김세현(Sehyeon Kim),황인성(Insung Hwang),김동윤(Dong-Yoon Kim),김영민(Young-Min Kim),이승환(Seung Hwan Lee),유지영(Jiyoung Yu) 대한용접·접합학회 2021 대한용접·접합학회지 Vol.39 No.5
To ensure safety and reduce the weight of vehicles, studies are being actively conducted on different aluminum alloys that have strength higher than conventional aluminum alloys. The development of high-performance aluminum alloys through magnesium content control is underway. Research on manufacturing techniques, such as, welding for application to the car body parts of these materials is required. In this study, the resistance spot weldability of an aluminum alloy with 6 wt.% magnesium (Al-6Mg) was evaluated and compared with the commercial aluminum alloy 5052, 6061 (Al5052, Al6061). The suitable welding range of the Al-6Mg was found to have a welding current of 24 ㎄ to 28 ㎄, and a similar level of Al6061. The welding heat input was almost the same for the three materials, which resulted in no difference in the diameter of the nuggets. There was no significant difference of the porosity ratio between Al-6Mg and Al5052; however, the porosity ratio of Al6061 was higher. The alloy with the highest tensile shear strength, hardness and energy absorption of a welded joint was Al-6Mg. The low porosity ratio and high hardness of the Al-6Mg alloy caused the relatively high tensile shear strength and energy absorption of the welded joint.
Kim, Young-Rang,Kim, Young Hye,Kim, Sung Woo,Lee, Yong Ju,Chae, Dong-Eon,Kim, Kyung-A,Lee, Zee-Won,Kim, Nam Doo,Choi, Jong-Soon,Choi, Insung S.,Lee, Kyung-Bok The Royal Society of Chemistry 2016 Chemical communications Vol.52 No.79
<P>Herein, we present a simple readout of the binding between a chemical drug and its target proteins in the cytoplasm by using a two-step bioorthogonal labeling method combined with spatially-localized expression of proteins. Dasatinib was modified with transcyclooctene (TCO), and its cytoplasmic target kinases were expressed in intracellular compartments, such as endosomes and F-actins. After bioorthogonal labeling, the colocalization between Dasatinib and its target proteins was observed in intracellular compartments.</P>
Kim, Bo-Eun,Choi, Soon Won,Shin, Ji-Hee,Kim, Jae-Jun,Kang, Insung,Lee, Byung-Chul,Lee, Jin Young,Kook, Myoung Geun,Kang, Kyung-Sun Cognizant Communication Corp. 2018 CELL TRANSPLANTATION Vol. No.
<P>Neural stem cells (NSCs) are a prominent cell source for understanding neural pathogenesis and for developing therapeutic applications to treat neurodegenerative disease because of their regenerative capacity and multipotency. Recently, a variety of cellular reprogramming technologies have been developed to facilitate <I>in vitro</I> generation of NSCs, called induced NSCs (iNSCs). However, the genetic safety aspects of established virus-based reprogramming methods have been considered, and non-integrating reprogramming methods have been developed. Reprogramming with <I>in vitro</I> transcribed (IVT) mRNA is one of the genetically safe reprogramming methods because exogenous mRNA temporally exists in the cell and is not integrated into the chromosome. Here, we successfully generated expandable iNSCs from human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) via transfection with IVT mRNA encoding SOX2 (SOX2 mRNA) with properly optimized conditions. We confirmed that generated human UCB-MSC-derived iNSCs (UM-iNSCs) possess characteristics of NSCs, including multipotency and self-renewal capacity. Additionally, we transfected human dermal fibroblasts (HDFs) with SOX2 mRNA. Compared with human embryonic stem cell-derived NSCs, HDFs transfected with SOX2 mRNA exhibited neural reprogramming with similar morphologies and NSC-enriched mRNA levels, but they showed limited proliferation ability. Our results demonstrated that human UCB-MSCs can be used for direct reprogramming into NSCs through transfection with IVT mRNA encoding a single factor, which provides an integration-free reprogramming tool for future therapeutic application.</P>
Cytoprotective Alginate/Polydopamine Core/Shell Microcapsules in Microbial Encapsulation
Kim, Beom Jin,Park, Taegyun,Moon, Hee Chul,Park, So‐,Young,Hong, Daewha,Ko, Eun Hyea,Kim, Ji Yup,Hong, Jong Wook,Han, Sang Woo,Kim, Yang‐,Gyun,Choi, Insung S. WILEY‐VCH Verlag 2014 Angewandte Chemie Vol.126 No.52
<P><B>Abstract</B></P><P>Chemical encapsulation of microbes in threedimensional polymeric microcapsules promises various applications, such as cell therapy and biosensors, and provides a basic platform for studying microbial communications. However, the cytoprotection of microbes in the microcapsules against external aggressors has been a major challenge in the field of microbial microencapsulation, because ionotropic hydrogels widely used for microencapsulation swell uncontrollably, and are physicochemically labile. Herein, we developed a simple polydopamine coating for obtaining cytoprotective capability of the alginate capsule that encapsulated <I>Saccharomyces cerevisiae</I>. The resulting alginate/ polydopamine core/shell capsule was mechanically tough, prevented gel swelling and cell leakage, and increased resistance against enzymatic attack and UV‐C irradiation. We believe that this multifunctional core/shell structure will provide a practical tool for manipulating microorganisms inside the microcapsules.</P>
Control of Microbial Growth in Alginate/Polydopamine Core/Shell Microbeads
Kim, Beom Jin,Park, Taegyun,Park, So-Young,Han, Sang Woo,Lee, Hee-Seung,Kim, Yang-Gyun,Choi, Insung S. Wiley (John WileySons) 2015 Chemistry - An Asian Journal Vol.10 No.10
<P>Microbial microencapsulation not only protects microorganisms from harmful environments by physically isolating them from the outside media but also has the potential to tailor the release profile of the encapsulated cells. However, the microbial release has not yet been controlled tightly, leading to undesired detrimental exposure of microorganisms to the outside. In this work, we suggest a simple method for controlling the cell release by suppressing the microbial growth in the microbeads. Alginate microbeads, encapsulating yeast cells, were coated with ultrathin but robust polydopamine shells, and the resulting core/shell structures effectively reduced the growth rate, while maintaining the cell viability.</P>
Enzymatic film formation of nature-derived phenolic amines
Kim, Ji Yup,Kim, Won Il,Youn, Wongu,Seo, Jeongyeon,Kim, Beom Jin,Lee, Jungkyu K.,Choi, Insung S. The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.28
<P>An enzyme-instructed method is developed for material-independent, cytocompatible coating of phenolic amines, inspired by melanogenesis found in nature. Tyrosinase-based film formation proceeds smoothly in an aqueous solution at neutral pH, and can use various phenolic amines including catecholamines, such as tyrosine, tyramine, dopamine, norepinephrine, and DOPA, as a coating precursor. Compared with polydopamine coating, the method is fast and efficient, and forms uniform films. Its high cytocompatibility is advantageously applied to cell-surface engineering, where chemically labile Jurkat cells are coated individually without any noticeable decrease in viability. Considering the huge potential of polyphenolic-based coatings, the strategy developed herein will provide an advanced tool for manipulating biological entities, including living cells, in biomedical and medicinal applications.</P>
Biomimetic Micropatterning of Silica by Surface-Initiated Polymerization and Microcontact Printing
Kim, Dong ,Jin,Lee, Kyung-Bok,Lee, Tae ,Geol,Shon, Hyun ,Kyong,Kim, Wan-Joong,Paik, Hyun-jong,Choi, Insung ,S. WILEY-VCH Verlag 2005 Small Vol.1 No.10
<P>Micropatterns of silica on a gold substrate were generated by a biomimetic approach, namely, the biosilicification of silicic acids. The procedure consists of three simple steps: pattern generation of a polymerization initiator, (BrC(CH<SUB>3</SUB>)<SUB>2</SUB>COO(CH<SUB>2</SUB>)<SUB>11</SUB>S)<SUB>2</SUB>, by microcontact printing; surface-initiated, atom-transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) from the patterned area; and polycondensation of silicic acids. The tertiary amine-containing polymer, pDMAEMA, aided in the spatially controlled polycondensation of silicic acids on surfaces in the presence of phosphate ions, and micropatterns of silica on a gold substrate were successfully generated in combination with the technique of microcontact printing. The procedure could be extended to the controlled fabrication of silica patterns with any size, shape, or thickness.</P> <B>Graphic Abstract</B> <P>A synthetic counterpart to silaffins in diatoms, pDMAEMA, was grown from a gold surface by pattern generation of a polymerization initiator and surface-initiated, atom-transfer radical polymerization. The patterns of pDMAEMA were utilized to generate patterns of silica on the surface by a biomimetic approach (see optical images). <img src='wiley_img/16136810-2005-1-10-SMLL200400157-content.gif' alt='wiley_img/16136810-2005-1-10-SMLL200400157-content'> </P>