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CVD 법에 의한 Y - Ba - Cu - O 고온초전도 박막의 제조와 열처리에 따른 특성변화
신형식,조익준 한국화학공학회 1993 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.31 No.1
β-diketonate chelate 화합물을 원료물질로 하여 890℃에서 SrTiO₃(100) 기판에 CVD법으로 T_(c, onset)=91 K (△T_c=2K)인 Y-Ba-Cu-O 고온초전도 박막을 제조하였다. 그 박막을 아르곤 또는 산소분위기에서 열처리하였을 때, 산소의 확산이 박막의 전기적 특성값과 결정격자상수에 미치는 영향을 조사하였으며, 또 XPS를 이용하여 Y 3d, Ba 3d_(5/2), Cu 2p_(3/2) 및 O 1s core-level의 광전자 방출로부터 산소확산에 의한 이들 각각의 core level line shape의 변화를 고찰하였다. 열처리조건에 따른 미세구조의 변화는 확인할 수 없었으나 T_c변화는 현저하였으며, 재 산화 처리에도 처음의 T_(c, zero)값으로는 회복되지 않았다. 박막구성원소들의 XPS core-level spectrum은 박막의 질(quality), 표면오염 정도에 따라서도 변하고 있으나, 근본적으로 초전도상의 산소함량에 따라 크게 영향을 받는 것을 알 수 있었다. The 91 K(T_(c, onset), △T_c=2K) Y-Ba-Cu-O thin films were prepared by CVD method on SrTiO₃(100) substrates at 890℃ using β-diketonate chelate compounds of Y(thd)₃, Ba(thd)₂ and Cu(thd)₂ as source materials. The characteristic changes such as T_c, crystallinity, and XPS core spectra due to oxygen out-and in-diffusion induced by heat treatment were measured by use of AC-four prove technique, XRD and SEM. We have analyzed the spectral changes observed in the XPS core spectra of Y 3d, Ba 3d_(5/2), Cu 2p_(3/2) and O 1s before and after heating Y-Ba-Cu-O films. The experimental results showed that T_c, crystal structure, and core-level line shape of the elements in the probed surface region were influenced by the oxygen content, which varied by heating in Ar or O₂ atmosphere. It is likely that the observed spectral changes are related to the oxygen deficiency as well as to the film quality and extrinsic contamination of the surface.
치주조직 유관세포에서의 Nitric Oxide 및 Nitric Oxide Synthetase의 생물학적 특성에 관한 연구
신형식,윤형진 원광대학교 치의학연구소 1998 圓光齒醫學 Vol.8 No.1
Bone remodeling is characterized by the coupling of osteoclast-mediated bone resorption and osteoblast-mediated bone formation. The process is tightly regualted at the local level by an incompletely known netwotk of peptide and non-peptide fators. Nitric oxide(NO), synthesized by nitric oxide synthetase(NOS) from L-arginine, is becoming recognized as an important bio-regualtory molecule in a variety of tissue, but little is known about its possible role in periodontal tissue. The purpose of this study is to investigate the expression of nitric oxide synthetase(NOS) in inflamed gingiva and the effects of cytokine on the expression of NOS protein. The expression of NOS in gingival tissue was evaluated by immunohistochemical staining for NOS,, NOS2, NOS3. The effect of cytokine on the expression of NOS in human periodontal ligament cells and osteoblast-like HOS cells by western blot analysis. Further, we studied that NO functions in periodontal ligment cells as a regulatory molecule. PDL cells incubated with NOS inhibitor and donor. The protein expression, type I collagen & non-collagenous protein, nitrate production and cell proliferation were evaluated. The results were as follows. 1. NOS_1, NOS_2, NOS_3 was rarely distributed in healthy gingiva, but stronger stained in gingival epithelium, endothelial cells, and mononuclear cells of inflammed gingiva. 2. The cytokine stimulated NOS_1, and NOS_3 protein were not inducing or inhibitory effect to compared with control in PDL and HOS cells. 3. Incubation of cells with combination of TNF-α, IFN-γ, LPS result in a time dependant increase in NOS_2 expression, reaching a maximal level after 24 hours of stimulation. 4. The osteonectin protein inhibitory effect of NMA, inhibitor of NOS, was reversed by L-arginine in dose dependant manner. 5. NMA decreased cell proliferation and nitrate production, but the inhibitory efffect of NMA was also prevented by the NO donor, sodium nitropruiside. These results suggest that exogenously synthesized NO was playing a stimulating effect on cell proliferation or on non-collagenous protein expression. Therefore NO have an important role in mediation of localized bone destruction associated inflammatory bone disease such as periodontitis.
방문간호사업의 경제적 효과 분석 : 서울시 22개 자치구 보건소를 중심으로
양봉민,이태진,신형식 서울大學校保建大學院 1993 國民保健硏究所硏究論叢 Vol.3 No.1
Visiting Nurse Program in Seoul was established in 1991, with the purpose assuring health right of low income citizens. Now, with shortages of health manpower and financing, the operation is in jeopardy. This study aims to analyze the economic efficiency of the program. Such an evaluation is neccessary in judging whether further resource allocation on the program will be justified or not. Data from health authorities was used, and the beneift of the program was compared with its cost. The results show that program's benefit barely outweighs its cost. However, when the program settles down in the future, one can expect much greater benefit from such a primary care project.