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Ni 도핑을 통한 정방성이 높은 벌크 PbTiO3 세라믹 합성
선정우,조재현,조욱 한국전기전자재료학회 2022 전기전자재료학회논문지 Vol.35 No.4
Bulk-sized PbTiO3 (PT), which is widely known as a high-performance ferroelectric oxide but cannot be fabricated into a monolithic ceramic due to its high c/a ratio, was successfully prepared with a high tetragonality by partially substituting Ni ions for Pb ions using a solid-state reaction method. We found that Ni-doped PT was well-fabricated as a bulk monolith with a significant c/a ratio of ~1.06. X-ray diffraction on as-sintered and crushed samples revealed that NiTiO3 secondary phase was present at the doping level of more than 2 at.%. Scanning electron microscopic study showed that NiTiO3 secondary phase grew on the surface of PT specimens regardless of the doping level possibly due to the evaporation of Pb during sintering. We demonstrated that an unconventional introduction of Ni ions into A-site plays a key role on the fabrication of bulk PT, though how Ni ion functions should be studied further. We expect that this study contributes to a further development of displacive ferroelectric oxides with a high c/a ratio.
멜라닌세포성 모반과 악성 흑색종의 p16과 p21발현에 관한 면역조직화학적 연구
선정우(Jung Woo Sun),정병수(Byoung Soo Chung) 대한피부과학회 2000 大韓皮膚科學會誌 Vol.38 No.11
Background:p16 and p21 belong to the family of cyclin dependent kinase inhibitors, which are important negative regulators of the cell cycle. Loss of normal cell cycle regulation contributes to the development and progression of malignancies. Typical acquired melanocytic nevi appear to follow a life cycle characterized by active growth, maturation, and progressive involution. In contrast, congenital melanocytic nevi have a different course and prognosis with potential for development of melanoma, and metastatic spread is very common in malignant melanoma. Objective:We investigated the expression patterns of p16 and p21 in acquired and congenital melanocytic nevi, and malignant melanoma by immunohistochemical technique. Method:Formalin-fixed and paraffin-embeded tissue from 3 junctional nevi, 5 compound nevi, 7 intradermal nevi, 5 congenital melanocytic nevi, and 5 malignant melanoma were immunolabeled with monoclonal antibodies directed against p16 and p21. Result:The benign melanocytic nevi showed a high expression for p16, and the expression of p21 was low or undetectable in benign melanocytic nevi with the exception of positive staining in junctional nevus, involuting intradermal nevus, and nevus cells in deep dermis of congenital meanocytic nevi. In malignant melanoma, the expression of p21 was higher than p16 expression with variable intensity of staining in different areas of the tumor. These findings suggest that the loss of p16 and expression of p21 seem to be related to tumorigenesis of melanocytic tumors. The expression of p21 which is induced by feedback mechanism in attempt to halt increased cell proliferation, might not be enough to restrict tumor progression and may be involved in the regressive changes of the intradermal nevi. (Korean J Dermatol 2000;38(11):1492~1498)
유육종성 육아종(sarcoidal granuloma) 소견을 보인 피부 결절 2예
이명기,선정우,정병수 조선대학교 부설 의학연구소 1999 The Medical Journal of Chosun University Vol.24 No.2
Sarcoidosis is an antigen-mediated disease defined by granuloma formation in different organs. Cutaneous lesions of sarcoidosis may be specific, showing histologically noncaseating granulomas, or nonspecific, showing typically erythema nodosum. If systemic garcoidosis cannot be demonstrated, a long-term follow-up should be undertaken, since some of these patients will develop systemic involvement later in the course of the disease. Some authors classify these lesions as local sarcoidal reactions. However, since skin lesions in the sarcoidal reaction and sarcoidosis do not differ in clinical or histological manifestations, other authors believe that these cases should be accepted as true sarcoidosis limited to the skin. We report two cases of cutaneous sarcoidosis limited to the skin without systemic involvement.
여드름 환자에서 adapalene 겔과 tretinoin 크림의 split-face 비교 연구
김영조,선정우,정병수,최규철 조선대학교 부설 의학연구소 2000 The Medical Journal of Chosun University Vol.25 No.1
Background : Adapalene is a new synthetic naphtholic acid derivative with potent retinoid and antiinflammatory properties, developed for the topical treatment of acne vulgaris. Objective : This study was designed to compare the efficacy and safety of 0.1% adapalene gel with tretinoin cream(0.025% and 0.05%) in the treatment of grade I to V facial acne vulgaris. Methods : Forty acne patient volunteers were enrolled in this investigatormasked, left-right comparison, randomized, controlled, intraindividual study. 0.1% adapalene gel and tretinoin cream(0.025% or 0.05%) were applied once a day to one halfface by the volunteers for 30 consecutive days. Efficacy and cutaneous tolerance were accessed at baseline and week 1, 2, 3, and 4. Efficacy was determined by investigator counts of inflammatory papules and pustules, and non-inflammatory open and closed comedones, as well as global improvement. Clinical signs(erythema, desquamation, dryness) and subjective symptoms(pruritus, burning) were evaluated and scored weekly. Result : 0.1% Adapalene gel was more effective in treating acne lesions than tretinoin cream(p<0.05). Cutaneous side effect was limited to a mild retinoid dermatitis occurring in all treatment groups. However, patients treated with adapalene gel tolerated this therapy significantly better than those treated with tretinoin cream. Conclusion : 0.1% adapalene gel applied once daily was significantly more effective in reducing acne lesions and was better tolerated than tretinoin cream in the treatment of acne vulgaris.