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Mechanical Performance of Ti/Cu-8Ag/S20C Clad Composite Processed by High Pressure Torsioning (HPT)
Song, Jun Young,Ha, Jong Su,Kim, In Kyu,Hong, Sun Ig Trans Tech Publications 2012 Advanced materials research Vol.625 No.-
<P>Ti/Cu-8Ag/S20C composite were processed by High Press Torsioning(HPT) and the effect of post-HPT heat treatment on the interfacial reaction products and the mechanical performance were studied. Intremetallic compound layer with the thickness of 11 μm was observed at the interface between Ti and Cu-8Ag for the clad heat-treated at 600°Cfor 24hrs. On the other hand, no intermetallic compounds were observed at the Cu-8Ag/S20C interface. No cracks were observed to be emanated from the corner of the indentation mark on the intremetallic compound layer at the Ti/Cu-8Ag interface, suggesting those intermetallic compounds is not so brittle. The stress-strain curves exhibited two steps in as-HPTed clad samples and those heat-treated at 600°C for 24hrs. The careful examination of the fractured plates revealed that S20C plate fractured first and then Ti and Cu-8Ag layers fractured together, suggesting the bonding strength between two layers is fairly high in the presence of intermetallic layer between Ti and Cu-8Ag layers</P>
압연 제조된 STS439/Al1050/ STS304 Clad소재의 열처리에 따른 계면 반응과 기계적 특성에서의 계면 반응 효과
송준영 ( Jun Young Song ),김인규 ( In Kyu Kim ),이영선 ( Young Seon Lee ),홍순익 ( Sun Ig Hong ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.11
The microstructures and mechanical properties of roll-bonded STS439/Al1050/STS304 clad materials were investigated after an annealing process at various temperatures. Interfacial layer was developed at the STS439/Al1050 and Al1050/ STS304 interfaces at 550℃. STS439/Al1050/STS304 clad metals fractured suddenly in a single step and the fracture decreased with increasing annealing temperatures at 450℃. After annealing at 550℃, samples fractured in three steps with each layer fracturing independently. Interfacial layers formed at 550℃ with a high Vickers microhardness were found to be brittle. During tensile testing, periodic parallel cracks were observed at the interfacial reaction layer. Observed micro-void between Al1050 and the interfacial layer was found to weaken the Al1050/reaction layer interface, leading to the total separation between Al1050 and the reaction layer.
Widdrol induces apoptosis via activation of AMP-activated protein kinase in colon cancer cells.
Kang, Moo Rim,Park, Song-Kyu,Lee, Chang Woo,Cho, Ig Jun,Jo, Yeong Nang,Yang, Jeong Wook,Kim, Jin-Ah,Yun, Jieun,Lee, Ki Hoon,Kwon, Hyun Ju,Kim, Byung Woo,Lee, Kiho,Kang, Jong Soon,Kim, Hwan Mook National Hellenic Research Foundation 2012 Oncology Reports Vol.27 No.5
<P>Widdrol, a natural sesquiterpene present in Juniperus sp., has been shown to exert anticancer and antifungal effects. Emerging evidence has suggested that AMP-activated protein kinase (AMPK), which functions as a cellular energy sensor, is a potential therapeutic target for human cancers. In this study, we found that AMPK mediates the anticancer effects of widdrol through induction of apoptosis in HT-29 colon cancer cells. We showed that widdrol induced the phosphorylation of AMPK in a dose- and time-dependent manner. The selective AMPK inhibitor compound C abrogated the inhibitory effect of widdrol on HT-29 cell growth. In addition, we demonstrated that widdrol induced apoptosis and this was associated with the activation of caspases, including caspase?3/7 and caspase-9, in HT-29 cells. We also demonstrated that transfection of HT-29 cells with AMPK siRNAs significantly suppressed the widdrol-mediated apoptosis and the activation of caspases. However, cell cycle arrest induced by widdrol was not affected by transfection of HT-29 cells with AMPK siRNAs. Furthermore, widdrol inhibited HT-29 tumor growth in a human tumor xenograft model. Taken together, our results suggest that the anticancer effect of widdrol may be mediated, at least in part, by induction of apoptosis via AMPK activation.</P>
굽힘시험시의 Mg/Al/STS 3층 클래드재의 변형 및 파단특성 분석
김인규 ( In Kyu Kim ),송준영 ( Jun Young Song ),오기환 ( Oh Ki Hwan ),홍순익 ( Sun Ig Hong ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.5
A three-point bending test was performed on roll-bonded Mg/Al/STS clad-metal plates under two different testing conditions (Mg layer in tension, or STS in tension) and their mechanical response and fracture behavior were investigated. Bending strength was found to be greater under the condition of Mg layer in tension. Heat treatment at 200℃ increased the bending formability, suggesting the interfacial strength increased at 200℃. Under the condition of Mg in tension, the clad heat-treated at 300℃ and 400℃ fractured in two steps, with the first step associated with the interfacial fracture between Mg and Al, and the second the fracture of the Mg layer. STS/Al layers were found to be bent without complete fracture. Under the condition of STS in tension, the clad heat-treated at 300℃ and 400℃ exhibited a very small load drop at the displacement, which is similar to that of the first load drop associated with the interfacial fracture under the condition of Mg in tension. In this case, no interfacial cracks were found and the complete cut-through fracture of clad was observed at low temperature heat treatment conditions, suggesting excellent interfacial strength. When the heat treatment temperature was higher than 300℃, interfacial cracks were observed. The local stress condition and the position of the interface with respect to the surface were found to have a great influence on the fracture behaviors of clad metals.
Mg/Al/STS 3층 클래드재의 기계적 특성에 미치는 계면반응층의 영향
김인규 ( In Kyu Kim ),송준영 ( Jun Young Song ),이영선 ( Young Sun Lee ),홍순익 ( Sun Ig Hong ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.8
3-ply Mg/Al/STS clad-metal was fabricated by the roll bonding process. An interfacial reaction layer was formed at the Mg/Al interface at and above 300℃ whereas no interfacial reaction layer was observed up to 400℃. The effect of the interfacial reaction layer on the mechanical and fracture properties in clad metals after heat treatments were investigated The chemical compositions were analyzed at the Mg/Al interface by an Energy dispersive X-ray analysis (EDX). A tension test was performed to examine the interfacial cracking properties. The Mg layer fractured first, causing a sudden drop of the stress and Al/STS layer continued to deform until the final fracture. Periodic cracks and crack propagation was observed at the reaction layer between Mg and Al.