http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Lateral reinforcement of welded SMA rings for reinforced concrete columns
Choi, E.,Park, S.H.,Cho, B.S.,Hui, D. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.577 No.suppl1
This study conducts a series of compressive tests of concrete cylinders confined by shape-memory alloy (SMA) rings to provide lateral confinement for reinforced concrete columns. Ni<SUB>50</SUB>Ti<SUB>41</SUB>Nb<SUB>9</SUB> (at. %) SMA bars with a diameter of 3mm and a length of 446mm were prepared and strained to 7% before welding. Three of the six confined cylinders were heated to 200<SUP>o</SUP>C to introduce recovery stress in the SMA rings, which was predicted to provide active confinement of concrete. The behavior of two welded bars with a resulting diameter of 6mm were tested and compared with that of the continuous SMA bars without welding. The continuous SMA bars showed the typical behavior of martensitic SMAs, such as an elastic range, a transformed state, and hardening behavior due to austenite. However, the welded bars were fractured at the welding point at or just after elastic range. The concrete cylinders confined by the SMA rings showed greater peak strength and larger failure strain compared to the plain concrete cylinders. However, the stress-strain curves of the confined cylinders showed stepping behavior due to the sequential fracturing of the SMA rings. The heated SMA ring cylinders did not show greater peak strength than the unheated SMA ring cylinders, indicating that active confining was not effective.
Choi, E.,Chung, Y.S.,Park, K.,Jeon, J.S. IPC Science and Technology Press ; Elsevier Scienc 2013 Engineering structures Vol.48 No.-
In this study, the bond behavior between steel reinforcing bars and concrete confined via steel wrapping jackets is estimated. Lateral bending tests are conducted for the reinforced concrete columns with continuous longitudinal reinforcement or lap-spliced longitudinal bars confined by the steel wrapping jackets. It is found that the jackets increase the bond strength and ductile behavior due to the transfer of splitting bonding failure to pull-out bonding failure. In the column tests, the steel wrapping jackets increase the flexural strength and ultimate drift for the lap-spliced column. However, the jacket for the column with continuous longitudinal reinforcement only increases the ultimate drift since the flexural strength depends on the yield of reinforcement. Finally, this study suggests a basic concept for determination of the thickness of the steel wrapping jackets which is different from the conventional method.
BRCA2 Fine-Tunes the Spindle Assembly Checkpoint through Reinforcement of BubR1 Acetylation
Choi, E.,Park, P.G.,Lee, H.o.,Lee, Y.K.,Kang, G.,Lee, J.,Han, W.,Lee, H.,Noh, D.Y.,Lekomtsev, S.,Lee, H. Cell Press 2012 Developmental cell Vol.22 No.2
Germline mutations that inactivate BRCA2 promote early-onset cancer with chromosome instability. Here, we report that BRCA2 regulates the spindle assembly checkpoint (SAC). Previously, we reported that BubR1 acetylation is essential for SAC activity. In this study we show that BRCA2 recruits the PCAF acetyltransferase and aids in BubR1 acetylation during mitosis. In the absence of BRCA2, BubR1 acetylation is abolished, and the level of BubR1 decreases during mitosis. Similarly, Brca2-deficient mouse embryonic fibroblasts exhibited weak SAC activity. Transgenic mice that were engineered to have interruptions in the BRCA2-BubR1 association exhibited marked decrease of BubR1 acetylation, weakened SAC activity, and aneuploidy. These transgenic mice developed spontaneous tumors at 40% penetrance. Moreover, immunohistochemical analyses of human breast cancer specimens suggested that BRCA2 mutation and BubR1 status is closely linked. Our results provide an explanation for how mutation of BRCA2 can lead to chromosome instability without apparent mutations in SAC components.