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Synthesis and Characterization of Ladder-like Structured Polysilsesquioxane with Carbazole Group
최승석,Albert S. Lee,백경열,최동훈,황승상 한국고분자학회 2011 Macromolecular Research Vol.19 No.3
Poly(propyl carbazole silsesquioxane) (PPCSQ) with a high molecular weight (M_w = 10,200) was synthesized by the direct hydrolysis of 9-[3-(trimethoxysilyl) propyl]-9H-carbazole with K_2CO_3, followed by a condensation reaction in an H_2O/dimethylformamide (DMF) mixture solvent at 25℃. The obtained PPCSQ consisted of ladder-like structured siloxane bonds with carbarzole groups as the pendant group, where the distance between two carbarzole pendant groups through the siloxane backbone was 15.6 Å and the mean thickness of the siloxane backbone was 4.3 Å. This PPCSQ was thermally stable up to 450 ℃ and the glass transition temperature was ca. 95 ℃,showing good film formablity by spin casting.
최승석,유석근 대한성형외과학회 2002 Archives of Plastic Surgery Vol.29 No.6
Angiosarcoma is a rare malignant vascular tumor featuring endothelial cells. Angiosarcoma have four clinical manifestations that are angiosarcoma in the scalp and face, angiosarcoma in chronic lymphedematous areas, angiosarcoma in previously irradiated sites and malignant angioendothelioma. The most common lesions are those that occur in the scalp and in the face of elderly people. The male to female ratio is 2:1. In my case, a 65-years-old male presented progressively growing tumor on the left frontal scalp. The tumor began as an ill-defined bluish macule, which was initially mistaken for an old bruise. The rapidly growing lesion extended to form violaceousm compressible and hemorrhagic plaques. The mass was 6×4.5cm in size.Distinguishing features are the frequent occurrence of a peripheral erythematous ring, satellite nodules, the presence of intratumoral hemorrhage, and the tendency to bleed spontaneously, or after minimal trauma. Histologically the tumor comprised anaplastic pleomorphic endothelial cells with new vascular channels and irregular vascular spaces lined by plump endothelial cell's stroma among them. The lesion was diagnosed as angiosarcoma. No metastasis to other organs were found as evaluated by chest CT, bone and liver scan. We performed wide excision, skin graft, bilateral transposition flap, chemotherapy and radiation. The tumor was recurred at 4 months after surgical excision and with metastasis to the lung. The progress was characterized by an extremely rapid growth accompanied by distant metastasis. Surgery, irradiation and chemotherapy having no effect on the final outcome, the patient died 7 months after diagnosis.
Y2O3:Eu3+ 나노 형광체의 Eu 농도가 발광 특성에 미치는 영향
최승석,송요승,강상식,곽민기,남상희,한정인,홍성제 한국물리학회 2004 새물리 Vol.49 No.1
In this study, the dependeneces of the optical properties of nanosized Y$_2$O$_3$ : Eu$^{3+}$ on an amount of europium doping in yttria were investigated. Nano powders of Y$_2$O$_3$ : Eu (0.2 mol\%, 0.5 mol\%, 0.7 mol\%) were synthesized using a solution-combustion method. The samples were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectrometry(EDS), and photoluminescence spectroscopy. The structural results showed that cubic europium-doped anocrystalline yttria with some monoclinic phase was produced by our preparation. The particle sizes of our samples were in the range of 29.48 $\sim$ 39.34 nm. The fluorescence spectra after excitation at a wavelength of 254 nm into the charge transfer state was described by the $^5$D$_0$ $\rightarrow$ $^7$F$_\Box$ ($\Box$ = 0, 1, 2, $\cdots$) line emission of the Eu$^{3+}$ ion with the strongest emission at 610 nm. The luminescence of Y$_2$O$_3$ : Eu$^{3+}$ for an excitation wavelength of 254 nm showed an emission from $^5$D$_0$ to $^7$F$_\Box$ ($\Box$ = 0, 1, 2, $\cdots$) with a strong emission peak at 611 nm. No differences in line position due to the europium concentration were observed, but the emission Intensity, which had its the highest value for 0.2 mol\% europium-doped yttria, did depended on the doping concentration. From the excitation spectra for light emission at 611 nm, in the range of 220 $\sim$ 285 nm, excitation via the charge transfer state excitation depended strongly on an amount of europium, and the intensity of red-light emission was proportional to that excitation. 본 연구에서는 europium(Eu) 농도가 Y$_2$O$_3$ : Eu$^{3+}$ 나노 형광체의광학적 특성(optical properties)에 미치는 영향에 대하여 관찰하였다. 액상반응법을 이용하여 활성제(activator)인 Eu를 모체(Host)인 Y$_2$O$_3$에 각각 0.2 mol\%,0.5 mol\%, 0.7 mol\%로 도핑(doping)하여 나노 형광 분말을 합성하였다. 제조된 형광체의 XRD, EDS를 이용하여 분석한 결과, 대부분 입방정(cubic) 구조이며, 일부 단사정(monoclinic) 구조로 이루어진 Y$_2$O$_3$ : Eu$^{3+}$ 형광 분말이제조되었음을 알 수 있었다. FWHM(Full Width Half Maximum)에 의한 입자크기를 scherrer equation에 의해 계산한 결과 29.48 $\sim$ 39.34 nm 정도의 입자크기를 보였다. 광학적 특성(Optical properties)은 254 nm 여기에 의해 611 nm에서 $^5$D$_0$ $\rightarrow$ $^7$F$_2$로의 강한 발광 peak를 가지는 Eu$^{3+}$이온에의한 $^5$D$_0$ $\rightarrow$ $^7$F$_\Box$($\Box$ = 0, 1, 2, $\cdots$) 발광을 하였다. Eu 농도 변화에 따른 스펙트럼의 변화는 없었으나 발광 강도에 크게 의존적이었고, 0.2 mol\%에서 가장 높은 발광 강도를 보였다. 611 nm에 대한 여기스펙트럼은 220 nm와 285 nm 영역인 전하전달과정(charge transfer process)에 의한 여기가 Eu$^{3+}$의 농도에 크게 의존하였으며, 이 영역에서의 강도는 적색발광의 강도와 비례하였다.
최승석 대한성형외과학회 2007 Archives of Plastic Surgery Vol.34 No.4
Purpose: We experienced a patient with posttraumatic duplication of the sternoclavicular joint causing a protruding deformity, whose major complaint was aesthetic. The patients history, radiologic findings, and surgical treatment are reported.Methods: A 41-year-old bus driver complained a bony prominence at the left medial clavicle, which had developed after a fracture. The patient was annoyed by the protrusion, which was even visible, when he was wearing a pullover. A three dimensional CT scan showed that the medial head was split into two portions, of which the anterior portion was protruding. In general anesthesia the anterior portion of the medial head was excised.Results: The bony prominence was corrected successfully. Follow up three dimensional CT scans showed that the anterior cortex of the clavicle had regenerated completely at the resection line one year after the operation.Conclusion: Surgical interventions for complications after clavicular fracture are usually carried out, only if there is a limitation of function or if it is painful. We report of a patient with posttraumatic bifurcation of the medial clavicular head, most probably caused by malunion. Upon the patient's request, the deformity causing protrusion of the medial clavicular area was successfully resected for cosmetic reasons.