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차체구조용 박육부재의 정적 압궤특성에 관한 실험적 연구
임성훈,김태식,양광영 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.1
In this paper, collapse test of thin-walled structural member widely used for automobiles is carried out under static compression load to observe the effects of cross-sectional shape and material on the absorbing-energy capacity in the viewpoint of crashworthiness. specimens tested consist of two sorts(Aluminium, CFRP) and configurations(Cylinder, Square) with variation in thickness. Also, comparisons of Al cylinder and square specimens are made th find the influence of difference in shape on the absorbing-energy capability according as the thickness of specimen varies.
Gwang Sig Yu,Ha Na Yu,Yun Hui Choe,최준식,Tai Hwan Ha,Sang Jae Son 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.2
We synthesized a novel cationic dendrimer consisting of a poly(amidoamine) dendrimer (PAMAM, generation 4) backbone with both L-arginine (Arg) at the termini and 6-aminohexanoic acid (Ahx) between the original core polymer and the peripheral Arg units. The sequential chemical modification of PAMAM G4 with Ahx and Arg resulted in higher transfection efficiency with much less cytotoxicity. PAMAM G4-Ahx-Arg formed stable polyplexes at weight ratios of 8:1 or higher (polymer: plasmid DNA), and the mean polyplex diameter was 180 ± 20 nm. PAMAM G4-Ahx- Arg showed much higher transfection ability than PAMAM G4 or PAMAM G4-Ahx. Furthermore, PAMAM G4-Ahx-Arg was much less cytotoxic than PEI25KD and PAMAM G4-Arg. In addition to Arg grafting of the PAMAM dendrimer, which endows a higher transfection capability, the addition of Ahx spacer increased dendrimer hydrophobicity,introduced flexibility into the conjugated amino acids, and reduced cytotoxicity. Overall, it appears that the concomitant modification of PAMAM with Ahx and Arg could lead to new PAMAM conjugates with better performances.
Yu, Gwang-Sig,Yu, Ha-Na,Choe, Yun-Hui,Son, Sang-Jae,Ha, Tai-Hwan,Choi, Joon-Sig Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.2
We synthesized a novel cationic dendrimer consisting of a poly(amidoamine) dendrimer (PAMAM, generation 4) backbone with both L-arginine (Arg) at the termini and 6-aminohexanoic acid (Ahx) between the original core polymer and the peripheral Arg units. The sequential chemical modification of PAMAM G4 with Ahx and Arg resulted in higher transfection efficiency with much less cytotoxicity. PAMAM G4-Ahx-Arg formed stable polyplexes at weight ratios of 8:1 or higher (polymer: plasmid DNA), and the mean polyplex diameter was $180{\pm}20nm$. PAMAM G4-Ahx-Arg showed much higher transfection ability than PAMAM G4 or PAMAM G4-Ahx. Furthermore, PAMAM G4-Ahx-Arg was much less cytotoxic than PEI25KD and PAMAM G4-Arg. In addition to Arg grafting of the PAMAM dendrimer, which endows a higher transfection capability, the addition of Ahx spacer increased dendrimer hydrophobicity, introduced flexibility into the conjugated amino acids, and reduced cytotoxicity. Overall, it appears that the concomitant modification of PAMAM with Ahx and Arg could lead to new PAMAM conjugates with better performances.
Preparation of cationic polydiacetylene nanovesicles for in vitro gene delivery.
Yu, Gwang Sig,Choi, Hye,Bae, Yun Mi,Kim, Jumi,Kim, Jong-Man,Choi, Joon Sig American Scientific Publishers 2008 Journal of nanoscience and nanotechnology Vol.8 No.10
<P>Here, we report novel cationic polydiacetylene-containing nanovesicle system and its application to gene delivery in vitro. The nanovesicle was constructed using a cationic diacetylene monomer lipid (DADMDPA-bis-PCDA) which contains a quaternary ammonium head group. The cationic character of this monomer leads to the electrostatic interaction with genetic materials such as plasmid DNA forming complexes and the diacetylene groups on its hydrophobic moiety provides the further polymerization functionality upon UV irradiation forming polydiacetylene-linkages within the nanovesicle. In the present study, the characteristics of nanovesicle/DNA interaction, and the transfection efficiency and cytotoxicity for the human embryonic kidney cells were characterized and compared between the nonpolymerized and polymerized nanovesicles.</P>
Yu, Gwang Sig,Bae, Yun Mi,Choi, Hye,Kong, Bokyung,Choi, Insung S.,Choi, Joon Sig American Chemical Society 2011 Bioconjugate chemistry Vol.22 No.6
<P>In this study, we introduced histidine residues into <SMALL>l</SMALL>-arginine grafted PAMAM G4 dendrimers to enhance proton buffering capacity and evaluated the physicochemical characteristics and transfection efficacies in vitro. The results showed that the synthesized PAMAM G4 derivatives effectively delivered pDNA inside cells and the transfection level improved considerably as the number of histidine residues increased. Grafting histidine residues into the established polymer vector PAMAM G4-arginine improved their proton buffering capacity. The cytotoxicity of PAMAM G4 derivatives was tested and it was confirmed that they displayed relatively lower cytotoxicity compared to PEI25KD in various cell lines. Also, confocal microscopy results revealed that PAMAM G4 derivatives effectively delivered pDNA into cells, particularly into the nucleus. These PAMAM dendrimer derivatives conjugated with histidines and arginines may provide a promising polymeric gene carrier system.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bcches/2010/bcches.2010.22.issue-6/bc100479t/production/images/medium/bc-2010-00479t_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/bc100479t'>ACS Electronic Supporting Info</A></P>