반도체 양자점 형성의 메커니즘 연구

The semiconductor quantum dots (QDs) have attracted much attention from researchers due to many advantages such as ease of color tuning by quantum size effect. The research of synthesis and characterization about QDs nanocrystal has extensively developed, since L. E. Brus et al. had reported size effects in the excited electronic properties of semiconductor nanocrystals. The development of synthesis method has led to use synthetically convenient and safety chemicals such as CdO, 1-octadece and the single-molecular precursors have been used sources for the synthesis of semiconductor QDs.5-8 Beside the reaction kinetics of monomer formation prior to particle nucleation and shape evolution have led to synthesize quantum dots, rods and tetrapods of CdSe QDs and core-shell structure QDs Despite the development of synthesis method and application, the mechanistic study of nanocrystals formation has been properly made out. Commonly, the mechanism of colloidal nanocrystals synthesis based on the simulations is described that molecular precursors are reacted to produce active monomers. The rapid burst of these monomers creates a high supersaturation condition, which initiates nucleation of clusters or very small nanocrystals. As monomer concentration and temperature fall, the nucleated particles grow by interparticle Ostwald ripening. However, this mechanism have been not perfectly explained the conversion from precursors to nanocrystals and just understood the size distribution and selective plane growth after seed formation. In chapter 1, it explained historical background for semiconductor QDs nanocrystals from quantum physic to application. In chapter 2 and 3, we respectively propose a new mechanism for II-VI semiconductor QDs nanocrystals formation by heating-up and hot-injection methods on the basis of the results of studies conducted on the isolated intermediates and the side products obtained In chapter 4, we implemented basic kinetic study dealing with the measurement of formation reactivity of respective precursors and synthesized gradient alloy QDs nanorcrystals based on the kinetic study of precursors. Moreover, it was able to synthesize QDs in the range of full visible light by changing synthetic method a little. In chapter 5, we suggested surface modification on the QDs nanocrystals using the alkylcarboxylic acid metal salt for more stable QDs nanocrystals. The major disadvantages of semiconductor QDs about stability would be mitigated through the synthesis of highly stable and quantum efficiency semiconductor QDs nanocrystals by metal oxide treatment on the surface based on the thermal decomposition mechanism of metal carboxylates complex in the presence of alkylamine. Moreover, we have fabricated quantum dots enhancement film (QDEF) for application of highly stable CdO-coated QDs nanocrystals.반도체 양자점 나노입자는 양자제한 효과에 의한 크기에 따라 광학적, 물리적 특성이 변하는 성질로 인해, 많은 연구 그룹에 의한 양자점 제조방법 및 그 응용에 관한 연구를 수행해왔다. 그러나 이러한 연구의 발전에도 불구하고 양자점 형성에 대한 메커니즘에 대한 연구는 미비하였다. 최근 몇몇 연구 그룹에 의해 양자점을 포함한 다양한 나노입자 형성에 대한 메커니즘 연구를 진행하였으나, 대부분은 나노씨앗 형성 후 반응 속도 연구에 의한 균일한 나노입자 형성 및 나노입자 형성에 있어 특정 성장면 제어를 통한 다양한 모양을 갖는 나노입자 형성에 대한 연구에 국한되고 있다. 이에 따라 기존의 메커니즘 연군는 분자수준의 선구물질이 나노물질이 형성되는 정확한 반응 경로를 설명하지 못하고 있다. 이에 본 논문에서는 다양한 방법을 통한 반도체 양자점 나노입자 형성에 대한 메커니즘의 이해 및 이를 토대로 안정성과 효율이 향상된 반도체 양자점 나노입자의 합성 및 특성 연구를 진행 하였다. 1장에서는 반도체 양자점 나노입자에 대한 물리적 특성부터 응용에 이르는 배경 지식 및 본 연구에 대한 목표를 제시 하였으며, 2장 및 3장에서는 단 분자 선구물질 및 이종 선구물질의 열분해 방법 (승온합성 및 고온 주입법)에 의한 반도체 양자점 형성을 다양한 실험적 방법을 통하여 이해하고 이를 통해 새로운 메커니즘을 제안 하였다. 4장에서는 양자점을 구성하는 각각의 금속 선구물질과 칼코게나이드 선구물질 사이의 반응 속도 연구를 수행 하였으며, 이를 통한 핵과 껍질 구성 성분의 점진적 혼합 결정층이 형성된 양자점 나노입자의 구조적 분석 및 가시부 전 파장 영역 발광 반도체 양자점 나노입자 합성 연구를 설명하였다. 마지막으로 5장에서는 제안된 메커니즘을 응용한 반도체 양자점 표면의 금속 산화층 형성 방법 제안 및 금속 산화층이 형성된 반도체 양자점의 효율 및 안정성 향상에 대한 실험을 진행 하였다. 또한 흰색 LED 발광체 응용을 위한 고분자-반도체 양자점 필름를 제작하였으며, 이에 대한 내구성 테스트에 대한 실험적 결과를 설명하였다.Docto

Does performance of robot-assisted laparoscopic radical prostatectomy within 2 weeks of prostate biopsy affect the outcome?

OBJECTIVE: The aim of this study was to determine whether robot-assisted laparoscopic radical prostatectomy (RALP) performed within either 2 or 4 weeks of prostate biopsy is associated with surgical difficulty or immediate postoperative outcome. METHODS: Of the 121 patients that underwent RALP at our institution, 104 patients were prospectively included. Patients were sequentially divided into three groups: first patient in group A (interval from biopsy to RALP: 2 weeks), second patient in group B (2-4 weeks), third patient in group C (more than 4 weeks), fourth patient in group A, and so on. The clinical, operative, pathological, and postoperative functional data were collected. RESULTS: Group A consisted of 31 patients, group B of 33, and group C of 40 patients. Median patient age and median follow up were 61.1 years and 14.1 months, respectively. In group A, mean estimated blood loss was significantly higher than the other two groups, even though there was no significant difference in the mean console time. Postoperative complications did not make any difference among the groups. In the multivariable analysis, the interval from biopsy to surgery did not affect operative times or surgical margins, or the immediate postoperative outcomes (e.g. recovery of erectile function, continence, and biochemical recurrence). CONCLUSION: A short interval for less than two weeks between the prostate biopsy and the RALP seems to be feasible and safe. Further studies with larger samples are needed to corroborate these findings.ope