Deformation and fracture behavior of polymer alloy containing polyarylate and polystyrene

Maste

플루오로시클로부텐과 MXY (M=Ca,Sr,Ba ; X,Y =H,F,Cl,Br,I)분자 구조의 순이론적 연구

학위논문(석사) - 한국과학기술원 : 화학과, 1996.2, [ iii, 63 p. ]Unusually large discrepancy exists between the reported value of the experimental geometries of hexafluorocyclobutene determined from microwave spectroscopy (MW) and those from electron diffraction (ED). In an effort to explain the origin of the difference, the geometries of cyclobutene, 1,2-difluorocyclobutene, 3,3,4,4 -tetrafluorocyclobutene, hexafluorocyclobutene and 1,2-dichloro-3,3,4,4 -tetrafluorocyclobutene are optimized by ab initio calculations at the HF, MP2 and CISD levels of theory, and further refined for the higher correlation effects through the use of model calculations of ethane,ethene, fluoroethane and fluoroethene. Comparison of the calculated results with available MW and ED parameters imply that MW geometrical parameters are probably more accurate for hexafluorocyclobutene than ED ones. The difficultly associated with vibrational corrections for hexafluorocyclobutene appears to be responsible for the unusual pattern of the difference between ED and MW structures. For hetero-substituted molecules MXY (M = Ca, Sr, Ba ; X, Y = H, F, Cl, Br, I), the equilibrium geometries of the ground states have been optimized at the HF, MP2, and CISD levels of the theory using effective core potentials and extended valence basis sets. The bondings, bending potentials and structures characteristic of hetero-substituted MXY molecules are presented in this paper. Core polarization (influence of the subvalence) and s-d hybridization (influence of the valence shell), to varying extents, control the bending in $MX_2$ and MXY systems. The bending potentials of MXY compounds, however, are relatively flatter than those expected from $MX_2$ and $MY_2$, leading to all linear forms of CaXY and linear SrFBr, SrFI, SrFAt, SrClBr, SrClI, and SrClAt of SrXY.BaXY are all in the bent forms but their bending potentials are very flat. Natural Atomic Orbital and Natural Population Analysis are suitable tools for explanation to this phenomena.한국과학기술원 : 화학과

고삼투 환경에서 재조합 CHO 세포를 이용한 치료용 단백질 생산 향상 전략

학위논문(박사) - 한국과학기술원 : 생명과학과, 2011.2, [ viii, 78 p. ]During recombinant Chinese hamster ovary (rCHO) cell culture, various events, such as feeding with concentrated nutrient solutions or the addition of base to maintain an optimal pH, increase the osmolality of the medium. To examine the effect of hyperosmolality on therapeutic protein production, an interferon-β (IFN-β)-producing cell line was cultivated in hyperosmotic condition. For efficient production of native IFN-β in rCHO cell culture, the IFN-β molecular aggregation that occurs during culture needs to be minimized. To do so, we investigated the effect of hyperosmolality and hypothermia on IFN-β production and molecular ag-gregation. Both hyperosmolality (470 mOsm/kg) and hypothermia (32℃) increased specific native INF-β productivity (qIFN-β). Furthermore, they decreased the IFN-β molecular aggregation, although severe IFN-β molecular aggregation could not be avoided in the later phase of culture. To overcome growth suppression at hyperosmolality and hypothermia, cells were cultivated in a biphasic mode. Cells were first cultivated at 310 mOsm/kg and 37℃ for 2 days to rapidly obtain a reasonably high cell concentration. The temperature and osmolality were then shifted to 32℃ and 470 mOsm/kg, respectively, to achieve high qIFN-β and reduced IFN-β molecular aggregation. Due to the enhanced qIFN-β and delayed molecular aggregation, the highest native IFN-β concentration achieved on day 6 was 18.03 ± 0.61 mg/L, which was 5.30-fold higher than that in a control batch culture (310 mOsm/kg and 37℃). Taken together, a combination of hyperosmolality and hypothermia in a biphasic culture is a useful strategy for improved native IFN-β production from rCHO cells. The hyperosmotic condition has detrimental effect on cell growth despite its merit in $q_p$. To determine the effect of hyperosmotic stress on apoptosis, type Ⅰ programmed cell death (PCD), and autophagy, which can be type Ⅱ PCD or a survival mechanism, of rCHO cells, two rCHO cell lines, producing antibody ...한국과학기술원 : 생명과학과