질소 도핑된 상호연결 구조의 다공성 탄소 나노시트의 간편한 제작과 산화환원 첨가제가 포함된 수용액 기반의 슈퍼커패시터에의 응용

학위논문 (석사) -- 서울대학교 대학원 : 융합과학기술대학원 융합과학부(나노융합전공), 2020. 8. 박원철.다공성 탄소 나노시트는 제작이 간단하며 효율적인 구조를 통해 전해질 이온의 빠른 이동을 가능케 한다는 점에서 전기 이중층 커패시터 전극물질로 많은 주목을 받고 있다. 그렇지만 정전기적 흡착으로 전하를 저장하는 탄소 물질의 특성으로 전극물질로 활용 시 상대적으로 낮은 커패시턴스를 보인다는 점이 지적받고 있다. 본 연구에서는 다공성 탄소 나노시트에 효과적인 열처리 방법을 통해 질소를 도핑함으로써 용량을 향상시켰고, 합성된 탄소 물질을 산화/환원반응 첨가제가 들어간 전해질에 접목시켜 추가적인 성능 향상을 꾀하였다. 먼저, 포타슘 사이트레이트를 열분해하여 다공성 탄소 나노시트가 상호 연결된 형태의 탄소 물질을 합성하였다. 합성된 탄소 물질에 질소 도핑을 하기 위해 질소 함유량이 풍부한 멜라민을 탄소 물질과 교반하여 열처리하였는데, 열처리 과정 중 특정 온도에서 머무는 시간을 설정함으로써 멜라민의 중합을 유도하였다. 열처리 과정 중 발생한 중합은 멜라민의 손실을 최소화하였고, 그 결과 최종 질소 도핑 비율은 2배 가량 향상되었다. 질소 도핑된 탄소 물질의 전기화학적 특성을 3전극 상황에서 확인해 본 결과, 1 A g-1에서 도핑되지 않은 탄소 물질 대비 25 % 증가한 360 F g–1의 용량을 보였다. 또한, 대칭 2전극 상황에서는 산화/환원 첨가제가 들어간 전해질과 접목되어 1 A g–1에서 468 F g–1의 더욱 향상된 용량을 발현하였다. 본 연구는 다공성 탄소 나노시트에 질소 도핑을 하기 위해 멜라민의 중합반응을 활용한 효율적인 방법을 제시했다는 점과, 질소 도핑 및 산화/환원 첨가제가 들어간 전해질을 활용해서 다공성 탄소 나노시트의 커패시턴스 향상을 이뤄냈다는 점에서 의의가 있다.N-doped porous carbon nanosheets have garnered research attention owing to their effective structure for fast ion diffusion and pseudocapacitive properties in supercapacitors. Herein, a facile method to incorporate nitrogen into interconnected porous carbon nanosheets with relatively high doping efficiency is proposed by inducing melamine condensation through appropriate dwell time. The as-prepared N-doped porous carbon material was studied as an electrode for the electrochemical double-layer capacitor. The carbon material delivered a specific capacitance of 350 F g-1 at a current density of 1 A g-1 in a three-electrode system. Furthermore, a symmetric supercapacitor device was fabricated using the N-doped interconnected carbon nanosheets with redox additives in aqueous electrolyte. Based on the redox reaction of the electrodes and electrolytes, the specific capacitance was measured 468 F g-1 at a current density of 1 A g-1 and 233 F g-1 at a relatively high current density of 20 A g-1. This research provided an efficient method for nitrogen-doping into interconnected porous carbon nanosheets using melamine and showed potential of carbon electrode material for high-performance supercapacitor applications with redox additives in aqueous electrolyte.1. Introduction 12 1.1. Supercapacitor 12 1.2. Porous carbon nanosheets 12 1.3. Nitrogen doping 13 1.4. Redox addictive in aqueous electrolyte 14 1.5. Objective 15 2. Experimental Section 16 2.1. Preparation of PCN 16 2.2. Preparation of N-doped PCN 16 2.3. Material characterizations 17 2.4. Electrochemical characterizations 18 3. Results and Discussion 20 3.1. Material analysis 20 3.2. Electrochemical analysis 37 4. Conclusions 47 References 48 국문 초록 (Abstract in Korean) 56Maste

Ileal Mucormycosis Diagnosed by Colonoscopy in a Patient with Acute Myeloid Leukemia

Gastrointestinal mucormycosis is an uncommon opportunistic fungal infection often presents in immunocompromised patients. Direct invasion of the intestinal walls by spores from ingested food is the main pathogenetic mechanism of this disease, which usually takes place in stomach and colon. Early diagnosis is critical, especially in vascular invasive types, due to its high mortality rate close to 100%. In the past when appropriate diagnostic tools were not available, mucormycosis were frequently found with autopsy. The advance in current endoscopic technology has increased diagnostic rate and made successful management available with appropriate treatments such as debridement of contaminated tissues. In this case report, we discussed a case of ileal mucormycosis diagnosed by colonoscopy and treated with anti-fungal agent successfullyope

Efficacy of early immunomodulator therapy on the outcomes of Crohn’s disease

BACKGROUND: The natural course of Crohn's disease (CD), with continuing relapses and remissions, leads to irreversible intestinal damage. Early adoption of immunomodulator therapy has been proposed in order to address this; however, it is still uncertain whether early immunomodulator therapy could affect the natural course of the disease in real practice. We evaluated the efficacy of such therapy on the prognosis of newly diagnosed patients with CD. METHODS: This retrospective study included 168 patients who were newly diagnosed with CD and who started treatment at Severance Hospital, Seoul, Korea between January 2006 and March 2013. The short- and long-term outcomes were compared between patients treated with early immunomodulator therapy and those treated with conventional therapy. RESULTS: A Kaplan-Meier analysis identified that administration of immunomodulators within 6 months after diagnosis of CD was superior to conventional therapy in terms of clinical remission and corticosteroid-free remission rates (P=0.043 and P=0.035). However, P=0.827). Patients with a baseline elevated CRP level were more likely to relapse (P<0.005). Drug-related adverse events were more frequent in the early immunomodulator therapy group than in the conventional therapy group P=0.029). CONCLUSIONS: Early immunomodulator therapy was more effective than conventional therapy in inducing remission, but not in preventing relapse. Baseline high CRP level was a significant indicator of relapse.ope

Clinical outcomes and predictive factors for response after the first course of corticosteroid therapy in patients with Crohn's disease

BACKGROUND/AIMS: This study sought to determine the natural course of Crohn's disease (CD) and identify predictors that could indicate responsiveness to corticosteroid (CS) therapy. METHODS: Patients with active CD who were treated with oral CS at a single institution between August 1994 and February 2008 were retrospectively reviewed. The clinical outcomes at 1 month, 4 months, and 1 year after the treatment, as well as clinical and biochemical parameters at the time of CS initiation, were evaluated. RESULTS: A total of 96 patients with CD were enrolled. In this study, 37 patients achieved complete remission (38.5%), 49 achieved partial remission (51.0%), and 10 (10.4%) showed no response at 1 month after the initiation of CS treatment. At 4 months and 1 year after treatment, 66 (69.5%) and 47 (56.6%) patients showed prolonged response, 22 (23.2%) and 20 (24.1%) showed steroid dependency, and 7 (7.4%) and 16 (19.3%) showed refractoriness, respectively. Nonstricturing and nonpenetrating behaviors and a lower CD activity index demonstrated clinical significance for mid-term or mid- and long-term steroid responses, respectively. CONCLUSIONS: The short-term response rate to initial oral CS therapy in CD was considerably high, but responsiveness thereafter showed a tendency to decrease with time. Clinical parameters reflecting mild inflammation were associated with responsiveness after CS treatment.ope

Infliximab versus Cyclosporine Treatment for Severe Corticosteroid-Refractory Ulcerative Colitis: A Korean, Retrospective, Single Center Study

BACKGROUND/AIMS: In patients with corticosteroid-refractory ulcerative colitis (UC), cyclosporine or infliximab may be added to the treatment regimen to induce remission. Here, we aimed to compare the efficacy of cyclosporine and infliximab. METHODS: Between January 1995 and May 2012, the medical records of 43 patients with corticosteroid-refractory UC who received either infliximab or cyclosporine as a rescue therapy at a tertiary care hospital in Korea were reviewed. RESULTS: Among the 43 patients, 10 underwent rescue therapy with cyclosporine and the remaining 33 patients received infliximab. A follow-up of 12 months was completed for all patients. The colectomy rate at 12 months was 30% and 3% in the cyclosporine and the infliximab groups, respectively (p=0.034). However, the Cox proportional hazard model indicated that the treatment of rescue therapy was not an independent associate factor for preventing colectomy (p=0.164). In the subgroup analysis, infliximab with azathioprine was superior to cyclosporine for preventing colectomy (hazard ratio of infliximab with azathioprine compared with cyclosporine only, 0.073; 95% confidence interval, 0.008 to 0.629). CONCLUSIONS: No difference between infliximab and cyclosporine with respect to preventing colectomy was noted. However, infliximab with azathioprine may be more effective than cyclosporine alone for preventing colectomy.ope

A Case of Ileal Mucormycosis in a Patient with Gastrointestinal Behcet’s Disease

Zygomycosis (mucormycosis) is a rare fungal infectious disease, usually found in association with an immunocompromised state. Gastrointestinal mucormycosis is extremely rare and fatal, thus it is important to detect and manage this disease at an early stage in an effort to improve survival. To date, no cases of mucormycosis superimposed on gastrointestinal Behcet’s disease have been reported. Herein we report a case in which gastrointestinal mucormycosis occurred in a 17-year-old-female with Behcet’s disease. The patient recovered from her disease after undergoing an ileocecectomyope

Clinical Efficacy of Nonsurgical Treatment of Crohn`s Disease-related Intraabdominal Abscess

Background/Aims: This study was conducted to compare the clinical efficacy between surgical and nonsurgical treatments for patients with Crohn`s disease-related intraabdominal abscess. Methods: A retrospective review of medical records was performed for patients admitted to a single institution due to Crohn`s disease-related intra-abdominal abscess from February, 1996 to February, 2008. Clinical outcomes were compared between surgical and nonsurgical groups in terms of treatment responses and recurrences. Results: A total of 47 episodes of intra-abdominal abscesses in 43 patients (12.7%) were identified from 339 patients with Crohn`s disease. Of these, initially, 18 cases (38.3%) underwent surgical treatment and 29 (61.7%) were treated medically (antibiotic treatments with or without percutaneous drainage). The overall treatment response rates of surgical and nonsurgical group were 100% versus 89.7% (p=0.11) and recurrence rates were 27.8% versus 30.8% (p=1.00). Three patients in nonsurgical group (10.3%) showed no response to therapy and ultimately received surgical drainages. The median length of hospitalization in nonsurgical group was shorter than in surgical group (12 and 29.5 days, respectively. p=0.02). Conclusions: Nonsurgical treatment might be as effective as surgical treatment for the treatment of Crohn`s disease-related intraabdominal abscess, especially considering shorter hospital stayope

스틸의 깊은 미세 구멍 드릴링 시 추력 모니터링을 이용한 peck 드릴링과 이를 통한 드릴 수명 연장

Thesis(doctor`s)--서울대학교 대학원 :기계항공공학부,2006.Docto

Robust QFD: Framework and Robust Prioritization Methods

Docto

Response rate to oral steroid therapy in patients with Crohn's disease and its clinical predictive factors

의학과/석사[한글]스테로이드는 활동성 크론병 환자에서 단기적인 치료효과가 입증된 이래 널리 사용되고 있으나, 장기적인 사용에 따른 부작용 등을 고려할 때 치료 후 임상 경과의 예측이 필요하다. 본 연구에서는 활동성 크론병 환자에서 첫번째 경구 스테로이드 사용에 따른 단기, 장기적인 자연 임상 경과를 확인하고, 그 예측인자를 분석해 보고자 하였다. 1994년 8월부터 2008년 2월까지 세브란스병원에 활동성 크론병으로 내원한 239명의 의무기록을 후향적으로 분석하였다. 이중, 진단 후 세브란스병원에서 처음으로 경구 스테로이드를 사용하고 최소한 4개월 이상 경과를 관찰하였던 96명을 대상으로 1개월, 4개월, 1년째의 치료 경과 및 치료 시작 시 임상 지표를 분석하였다. 대상 환자 96명에서 남자 75명, 크론병 진단 당시 나이 중앙값 23세(12-64), 유병 기간의 중앙값 5개월(0-156)이었으며, 크론병의 해부학적 위치로 회장 말단과 대장을 침범한 경우(L3)가 63명(65.6%), 질병 행태 상 염증형(B1)이 53명(55.2%)으로 가장 많았다. 초기에 사용한 스테로이드의 용량 중앙값은 0.59mg/kg (0.31-0.95)였다. 1개월 치료반응은 관해 37예(38.5%), 호전 48예(50%), 무반응 11예(11.5%)였다. 4개월 치료반응이 확인된 95예 중 지속 반응 68예(71.6%), 스테로이드 의존 20예(21.1%) 였으며 스테로이드 불응성을 보인 7예 중 6예는 수술, 1예는 면역억제제 추가가 이루어졌다. 1년 치료반응이 확인된 84예에서는 49예(58.3%)에서 지속반응, 스테로이드 의존 19예(22.6%), 스테로이드 불응성 16예(19%)였다(수술 8예, 면역억제제사용 5예, infliximab 3예). 스테로이드 반응군과 비반응군을 비교하였을 때 임상 지표 상 Crohn’s disease activity index (CDAI)만이 비반응군에서 통계적으로 유의하게 높았다(p=0.007/0.000/0.010, 1개월/4개월/1년). 결론적으로 크론병 환자에서 첫번째 경구 스테로이드 사용에 대한 단기 반응률은 88.5%로 높았으나 1년 후에는 58.3%로 감소하는 경향을 보였으며, 치료 시작 당시 CDAI가 높은 경우 치료 반응이 좋지 않은 경향을 보였다. [영문]Objectives: The aim of this study was to determine the natural course of Crohn’s disease patients who were first treated with oral corticosteroids, and to find the predictive factors that can indicate their responsiveness to such steroid therapy. Methods: Among patients with active Crohn’s disease diagnosed and treated at a single center, those who had been treated with oral steroid from August, 1994 to February 2008 were enrolled and their medical records were retrospectively reviewed. Clinical outcome was evaluated every 1 month, 4 months, and 1 year after treatment. The clinical and biochemical parameters were compared between patients who showed responses to steroid treatment and those who did not. Results: A total of 96 patients were enrolled from 239 patients with Crohn’s disease. There were 75 males, and the median age at diagnosis was 23 years (12-64). The most common location of Crohn’s disease was the ileocolon (65.6%) by Vienna classification and the most common behavior type was the non-stricturing, non-penetrating type (55.2%). The median dosage of steroid was 0.59mg/kg (0.31-0.95). There were 37 cases with complete remission (38.5%), 48 with partial remission (50.0%), and 11 patients (11.5%) showed no response to oral steroid therapy after 1 month post-treatment. After 4 months from the treatment, 68 (71.6%) showed prolonged response, 20 (21.1%) showed steroid dependency, and 7 (7.4%) showed refractoriness, respectively. After 1 year from the treatment, 49(58.3%) patients showed prolonged response, 19 (22.6%), steroid dependency, and 16, refractoriness (19.0%). There were no significant differences between steroid responders and non-responders in any parameters except in the Crohn’s disease activity index (CDAI) (p=0.007/0.000/0.010, 1 month/4 month/1 year after treatment). Conclusion: Short-term response rate to initial oral steroid therapy in Crohn’s disease was high (88.5% after 1 month from treatment), but the responses showed tendency along with time (58.3% after 1year from treatment). And CDAI was significantly high in steroid non-responders than steroid responders.ope