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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>
Kim Yeji,Kim Jihoo,Kim Won June,Lee Eok Kyun,Choi Insung S. 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.5
3D graph convolutional network (3DGCN) is a graph neural network (GNN) variant that utilizes the 3D bond information on molecules for chemical tasks. In 3DGCN, the pooling operation extracts the molecular features from the atomic features for molecule embedding and dimensionality reduction. In this work, we investigated the pooling effects on the performance of 3DGCN in the classification of protein–ligand binding events, especially when a ligand is rotated with respect to a target protein in the 3D Cartesian coordinate. 3DGCN showed the general ability for recognizing the ligand rotation, and its prediction accuracy was found to be pooling-dependent. For example, 3DGCN with max pooling did not recognize the rotations of known active ligands for human β-secretase 1 faithfully, compared with the other pooling operations (sum, avg, and set2set). This work would contribute to augmented architecture evolution of 3DGCN for the chemical tasks that require the 3D molecular information including chirality.
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>