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집속이온빔을 이용한 탄소나노튜브 팁의 조작 및 성능평가
윤여환(Yeo-Hwan Yoon),신영현(Young-Hyun Shin),한창수(Chang-Soo Han) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
We report the structural modification of carbon nanotube (CNT) tip for Atomic force microscopy (AFM) based on ion beam irradiation. In general, CNT tip assembled by dielectrophoresis would often have non-vertical angle, very crooked shape or too lengthy one. Therefore, these tips should be modified to the appropriate shape to use as an AFM tip. We found that the ion beam could contribute to merge the bundled CNTs, to make the CNT diameter uniform as well as to make the wavy shape of CNT straight. In addition, we could cut the free-standing CNT on a Si tip using focused ion beam(FIB). We measured anodic aluminum oxide sample and trench structure to estimate the performance of FIB-modified tip and compared with those of conventional Si tip. We demonstrate that FIB modified tip in non contact mode had superior characteristics than conventional tip in the respects of wear, image resolution and sidewall measurement.
대식세포에서 수련환(茱連丸) 물추출물의 항염증작용에 관한 연구
윤여환 ( Yeo Hwan Yoon ),김성배 ( Sung Bae Kim ),강옥화 ( Ok Hwa Kang ),문수현 ( Su Hyun Mun ),서윤수 ( Yun Soo Seo ),양다운 ( Da Wun Yang ),강다혜 ( Da Hye Kang ),위경 ( Gyeong Wi ),임재수 ( Jae Soo Lim ),김마룡 ( Ma Ryong Kim ) 대한본초학회 2014 大韓本草學會誌 Vol.29 No.6
Objectives : Suryeon-hwan (SRH) exhibits potent anti-inflammatory activity with an unknown mechanism. However, there has been a lack of studies regarding the effects of SRH on the inflammatory activities and effector inflammatory disease mechanism about macrophage before is not known. So, the investigation focused on whether SRH inhibited nitric oxide (NO) and prostaglandin E2 (PGE2) productions, as well as the expressions of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and mitogen-activated protein kinases (MAPKs) in LPS-stimulated RAW 264.7 cells. Methods : Cells were treated with 200 ng/mL of LPS 30 min prior to the addition of SRH. Cell viability was measured by MTS assay. The production of nitric oxide (NO) was determined by reacting cultured medium with Griess reagent. The content of level of cytokines (PGE, IL-6) in media from LPS-stimulated Raw 264.7 cells was analyed by ELISA kit. The expression of COX-2, iNOS and MAPKs was investigated by Western blot, RT-PCR. Results : We found that SRH inhibited LPS-induced NO, PGE2 and IL-6 productions as well as the expressions of iNOS and COX-2. Furthermore, SRH suppressed the LPS-induced phosphorylation of MAPK and extracellular signal-regulated kinase 1/2 (ERK 1/2) activation. Conclusions : These results suggest that SRH has inhibitory effects on LPS-induced PGE2, NO, and IL-6 production, as well as the expressions of iNOS and COX-2 in the murine macrophage. These inhibitory effects occur through blockades on the phosphorylation of MAPKs following activation.
Focus Ion Beam을 이용한 탄소나노튜브 팁의 조작
윤여환(Y. H. Yoon),한창수(C. S. Han) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
This paper reports on the development of a scanning probe microscopy(SPM) tip with caborn nanotubes. We used an electric field which causes dielectrophoresis(DEP), to align and deposit CNTs on a metal-coated SPM tip. Using the CNT attached SPM tip, we have obtained an enhanced resolution and wear property compared to that from the bare silicon tip through the scanning of the surface of the bio materials. The carbon nanotube tip align toward the source of the ion beam allowing their orientation to be changed at precise angles. By this technique, metal coated carbon nanotube tips that are several micrometer in length are prepared for scanning probe microscopy.
전기방사 방법을 사용한 기능화된 탄소나노튜브 강화 고분자 나노섬유의 배향에 관한 연구
윤여환(Yuhwan. Yoon),곽정춘(Jeungchoon Goak),박주혁(Joohyuk Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Multi-walled carbon nanotubes were purified by using the nitric acid after the mechanical cutting, which carboxylic group might be introduced into the surface of nanotubes. To enhance the dispersion of CNTs, carboxylic groups were substituted in the reaction with octadecyl amine containing a long alkyl group. Nanofibers were manufactured by electrospinning, the solution that mixed with PMMA and ODA-fuctionalized CNTs in dimethyl formamide and dispersed with ultrasonication. Diameter and alignment of nanofibers with various electrospinning parameters, such as the CNT and PMMA concentration in solution, the applied voltage, and the distance to the collector were investigated. As a result, the nanofiber diameter was increased with the increment of PMMA concentration, whereas it was reduced as the applied voltage and the spinning distance was increased. The spinning area became smaller with the distance. The nanofibers were formed without the defect on surface and well aligned in a specific concentration of PMMA and nanotubes.