• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.113.2-113.2
• /
• 2010

세라믹 필터는 여러 종류의 분진제거 시스템에서 연소 배가스 정제를 위한 가장 적절한 소재로 알려져 있다. 현재까지 다양한 형태의 세라믹 필터가 개발되고 있는데, 캔들 타입(candle type), 튜브 타입(tubular type), 평판 타입(parallel flow type) 등이 그 예이다. 통상적으로 세라믹 캔들 필터는 가압유동층복합발전(PFBC, Pressurize Fluidized-Bed Combustion), 석탄가스화복합발전(IGCC, Integrated coal Gasification Combined Cycle), 석탄가스화연료전지복합발전(IGFC, Integrated coal Gasification Fuel cell Combined cycle)에서 고온 배가스 정제용으로 사용되고 있다. 일반적으로 IGCC나 CTL 합성가스 정제시스템의 경우에는 높은 고압(약 25기압)과 미세분진이 함유되어 있는 분위기에서 운전된다. 그러므로 이때 사용되는 초청정용 세라믹 집진필터는 고온, 고압 및 부식 환경에서 50 MPa 이상을 갖는 높은 강도와 내식성을 갖도록 개발되어야 하기 때문에 SiC(Silicon Carbide)가 가장 적절한 캔들 필터 소재로 적용되고 있다. 이에 따라 집진용 SiC 세라믹 캔들 필터를 개발하기 위해서는 고온에서 내산화성이 우수하고, 부피팽창에 의한 균열이 발생하지 않는 무기결합재의 선정 및 이를 통한 소재의 특성 최적화가 가장 중요한 부분이라 할 수 있다. 본 연구에서는 래밍성형 공정을 적용하여 1m급 탄화규소 세라믹 캔들 필터 시작품을 제조하였으며, 래밍성형 공정 이외에 정수압가압성형, 진공압출성형으로 제조되고 있는 세라믹 캔들 필터의 국내외 시장 및 그 전망을 분석하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.109.2-109.2
• /
• 2010

세라믹 필터는 여러 종류의 분진제거 시스템에서 연소 배가스 정제를 위한 가장 적절한 소재로 알려져 있다. 현재까지 다양한 형태의 세라믹 필터가 개발되고 있는데, 캔들 타입(candle type), 튜브 타입(tubular type), 평판 타입(parallel flow type) 등이 그 예이다. 통상적으로 세라믹 캔들 필터는 가압유동층복합발전(PFBC, Pressurize Fluidized-Bed Combustion), 석탄가스화복합발전(IGCC, Integrated coal Gasification Combined Cycle), 석탄가스화연료전지복합발전(IGFC, Integrated coal Gasification Fuel cell Combined cycle)에서 고온 배가스 정제용으로 사용되고 있다. 일반적으로 IGCC나 CTL 합성가스 정제시스템의 경우에는 높은 고압(약 25기압)과 미세분진이 함유되어 있는 분위기에서 운전된다. 그러므로 이때 사용되는 초청정용 세라믹 집진필터는 고온, 고압 및 부식 환경에서 50 MPa 이상을 갖는 높은 강도와 내식성을 갖도록 개발되어야 하기 때문에 SiC(Silicon Carbide)가 가장 적절한 캔들 필터 소재로 적용되고 있다. 이에 따라 집진용 SiC 세라믹 캔들 필터를 개발하기 위해서는 고온에서 내산화성이 우수하고, 부피팽창에 의한 균열이 발생하지 않는 무기결합재의 선정 및 이를 통한 소재의 특성 최적화가 가장 중요한 부분이라 할 수 있다. 본 연구에서는 IGCC나 CTL 공정에 적용하기 위한 SiC 캔들 필터 소재 개발을 위해 래밍성형 공정으로 1m급의 탄화규소 캔들 필터 시작품을 제작하여 SiC 출발입자 크기와 무기계 결합재인 스트론튬 카보네이트의 첨가량 변화에 따른 필터 소재의 특성 평가를 수행하였다.

• Childhood Kidney Diseases
• /
• 제16권1호
• /
• pp.21-31
• /
• 2012

초점성 분절성 사구체 경화증(focal segmental glomerulosclerosis; FSGS)은 경화증을 주 병변으로 하는 질환으로서 일차성 사구체 질환의 하나이면서 진행된 사구체 질환의 형태적 변화를 기술하는 단어로도 사용되고 있다. 사구체에는 경화증, 유리질 형성, 거품세포의 출현, 발세포의 공포화, 광륜형성 등이 보이고, 간질의 섬유화와 염증세포의 침윤, 세뇨관의 위축, 혈관의 비후 및 내막 섬유화 등을 특징으로 한다. 면역형광검사에서 부분적으로 IgM과 C3 등의 침착을 보이지만 면역관련 질환은 아니다. 전자현미경 검사에서는 발세포의 손상 현상으로 세포질 내의 공포화와 족돌기가 상실되는 것이 중요 소견이다. 2004년 표준화 된 FSGS의 분류는 과거의 형태학적 변형들을 모아서 임상과의 상관관계를 지웠다. 그 결과 tip형이 가장 예후가 좋으며, collapsing형이 가장 나쁜 것으로 알려졌다. 그러나 이 분류가 증례에 따라서는 적용하기가 애매한 경우가 많고, collapsing형을 FSGS에 분류하는 것에 대한 반론 등이 제기되고 있다. 한편, 임상적으로는 FSGS를 원인에 따라 분류하여 거꾸로 형태학적 공통점을 찾으려는 노력을 하고 있다. 사구체의 수가 적어서 일어나는 과여과로 인한 FSGS는 perihilar형이 많고 유전적 질환에 의한 것은 diffuse mesangial sclerosis가 특징인 것으로 주장되고 있다. FSGS는 이와 같이 아직도 밝혀져야 할 것이 많은 질환이며, 계속적인 연구가 이루어져야 할 필요가 있다.

• Archives of Plastic Surgery
• /
• 제35권3호
• /
• pp.333-336
• /
• 2008

Purpose: Adenoid cystic carcinoma is a rare type of eccrine sweat gland carcinoma. Although it is mostly known as a neoplasm of the salivary gland, it could occur as a primary skin tumor. We present a patient with a primary cutaneous adenoid cystic carcinoma at the genital area. Methods: A 60-year-old man had a slowly growing 1 cm sized single tender mass near the left scrotum and he underwent excisional biopsy at a local clinic. A diagnosis of adenoid cystic carcinoma was made and thus he was transferred to our hospital. In physical examination, other specific findings were not detected except a linear scar caused by a previous skin biopsy near the left scrotum. In CT scan, PET-CT scan and endoscopy, there was no evidence of neoplasm in other organs. It was diagnosed as the primary cutaneous adenoid cystic carcinoma and then wide excisions were performed including total 4.5 cm margin of normal skin. Results: Microscopic findings revealed proliferation of tumor cell islands with cribriform or tubular patterns containing several round, pseudocystic structures. The tumor cells showed basaloid cells with uniform and small nuclei. Tumor cells infiltrated into the dermis and upper portion of subcutaneous tissue. There was multifocal perineural invasion of tumor cells. In postoperative 6 months, we found no recurrence and other complications. Conclusion: Herein we found a rare case of primary cutaneous adenoid cystic carcinoma at the genital area.

• 대한의용생체공학회:의공학회지
• /
• 제34권3호
• /
• pp.111-116
• /
• 2013

Finite element analysis(FEA) has been extensively applied in the analyses of biomechanical properties of stents. Geometrically, a closed-cell stent is an assembly of a number of repeated unit cells and exhibits periodicity in both longitudinal and circumferential directions. This study concentrates on various parameters of the FEA models for the analysis of drug-eluting biodegradable polymeric stents for application to the treatment of coronary artery disease. In order to determine the mechanical characteristics of biodegradable polymeric stents, FEA was used to model two different types of stents: tubular stents(TS) and helicoidal stents(HS). For this modeling, epigallocatechin-3-O-gallate (EGCG)-eluting poly[(L-lactide-co-${\varepsilon}$-caprolactone), PLCL] (E-PLCL) was chosen as drug-eluting stent materials. E-PLCL was prepared by blending PLCL with 5% EGCG as previously described. In addition, the effects of EGCG blending on the mechanical properties of PLCL were investigated for both types of stent models. EGCG did not affect tensile strength at break, but significantly increased elastic modulus of PLCL. It is suggested that FEA is a cost-effective method to improve the design of drug-eluting biodegradable polymeric stents.

• Nutrition Research and Practice
• /
• 제8권2호
• /
• pp.220-226
• /
• 2014

BACKGROUND/OBJECTIVES: Arsenic, which causes human carcinogenicity, is ubiquitous in the environment. This study was designed to evaluate modulation of arsenic induced cancer by resveratrol, a phytoalexin found in vegetal dietary sources that has antioxidant and chemopreventive properties, in arsenic trioxide ($As_2O_3$)-induced Male Wistar rats. MATERIALS/METHODS: Adult rats received 3 mg/kg $As_2O_3$ (intravenous injection, iv.) on alternate days for 4 days. Resveratrol (8 mg/kg) was administered (iv.) 1 h before $As_2O_3$ treatment. The plasma and homogenization enzymes associated with oxidative stress of rat kidneys were measured, the kidneys were examined histologically and trace element contents were assessed. RESULTS: Rats treated with $As_2O_3$ had significantly higher oxidative stress and kidney arsenic accumulation; however, pretreatment with resveratrol reversed these changes. In addition, prior to treatment with resveratrol resulted in lower blood urea nitrogen, creatinine and insignificant renal tubular epithelial cell necrosis. Furthermore, the presence of resveratrol preserved the selenium content ($0.805{\pm}0.059{\mu}g/g$) of kidneys in rats treated with $As_2O_3$. However, resveratrol had no effect on zinc level in the kidney relative to $As_2O_3$-treated groups. CONCLUSIONS: Our data show that supplementation with resveratrol alleviated nephrotoxicity by improving antioxidant capacity and arsenic efflux. These findings suggest that resveratrol has the potential to protect against kidney damage in populations exposed to arsenic.

• The Korean Journal of Physiology and Pharmacology
• /
• 제17권4호
• /
• pp.259-265
• /
• 2013

The anti-apoptotic effect of (-)-epigallocatechin-3-gallate (EGCG) during unilateral testicular torsion and detorsion (TT/D) was established in our previous study. In mice, the smallest inhibitor of apoptosis, survivin, is alternatively spliced into three variants, each suggested to have a unique function. Here, we assessed how EGCG exerts its protective effect through the expression of the different survivin splice variants and determined its effect on the morphology of the seminiferous tubules during TT/D. Three mouse groups were used: sham, TT/D+vehicle and TT/D treated with EGCG. The expression of the survivin variants (140 and 40) and other apoptosis genes (p53, Bax and Bcl-2) was measured with semi-quantitative RT-PCR. Histological analysis was performed to assess DNA fragmentation, damage to spermatogenesis and morphometric changes in the seminiferous tubules. In the TT/D+vehicle group, survivin 140 expression was markedly decreased, whereas survivin 40 expression was not significantly different. In parallel, there was an increase in the mRNA level of p53 and the Bax to Bcl-2 ratio in support of apoptosis induction. Histological analyses revealed increased DNA fragmentation and increased damage to spermatogenesis associated with decreased seminiferous tubular diameter and decreased germinal epithelial cell thickness in the TT/D+vehicle group. These changes were reversed to almost sham levels upon EGCG treatment. Our data indicate that EGCG protects the testis from TT/D-induced damage by protecting the morphology of the seminiferous tubules and modulating survivin 140 expression.

• Animal cells and systems
• /
• 제11권2호
• /
• pp.141-146
• /
• 2007

Cantharidin is produced by blister beetles (Coleoptera: Meloidae) and smaller oedemerid beetles (Coleopetra: Oedemeridae) and is found in hemolymph and various tissues. The function of cantharidin in the courtship behaviour of meloids had never been fully established. Our studies show a correlation between density of cuticular pores and cantharidin titre of the scape and pedicel segments of male specimens of the East African species of Epicauta nyassensis (Haag-Rutenberg, 1880) (Coleoptera: Meloidae). Light microscopy of semi-thin cross sections of the male scape and pedicel indicates that there are many canal shaped structures that stretch from the antennal hemolymph to the antennomere surface. These structures may be tubules, which transport cantharidin circulating in the hemolymph to the surface, where the compound can be released via cuticular pore openings. Analyses of the head capsule and antennal segments of E. nyassensis females which had been copulated with males revealed low titre of cantharidin in the first two antennal segments. The density of the scape and pedicel pores of females was to some extent higher than the density of these pores on flagellum; however it was considerably lower than that of the males. Interestingly, no tubular cell or other transport structures were found in the cross sectioning of the female antennomeres or on the integument surface. During mating, male antennomeres, as well as cantharidin containing pores which are located on the $1^{st}\;and\;2^{nd}$ antennomeres, come into direct contact with the female antennae and may release cantharidin to their surface. Female E. nyassensis may be able to discriminate the opposite sex with abundant reserves of cantharidin prior to mating. This is another evidence that cantharidin function in close range sexual selection.

• International Journal of Oral Biology
• /
• 제37권2호
• /
• pp.77-83
• /
• 2012

We investigated the pulpal response to direct pulp capping in rat molar teeth using mineral trioxide aggregate (MTA) and calcium hydroxide (CH). A palatal cavity was prepared in rat maxillary molar teeth. Either MTA or CH was placed on the exposed pulp and all cavities were restored with composite. Rats were sacrificed for histological evaluation after 12 hours and at 2, 7, 14 and 21 days. In both the MTA and CH groups, reparative dentin formation was clearly observed on histology after 14 days. The MTA-capped pulps were found to be mostly free from inflammation, and hard tissue of a tubular consistent barrier was observed. In contrast, in CH-capped teeth, excessive formation of reparative dentin toward residual pulp was evident. The pulpal cell response beneath the reparative dentin layer was examined by immunofluorescence using antibodies against DSP. After 2 days, a few DSP immunopositive cells, most of which showed a cuboidal shape, appeared beneath the predentin layer. At 7 days, DSP-immunopositive cells with columnar odontoblast-like cells were seen beneath the newly formed hard tissues. At 14 and 21 days, DSP was more abundant in the vicinity of the odontoblastic process along the dentinal tubules than in the mineralized reparative dentin. The CH group showed strong expression patterns in terms of DSP immunoreactivity. Our results thus indicate that MTA may be a more effective pulp capping material as it induces the differentiation of odontoblast-like cells and the formation of reparative dentin without the loss of residual pulp functions.

• 대한세포병리학회지
• /
• 제6권1호
• /
• pp.18-26
• /
• 1995

In order to compare cytologic findings ol breast carcinoma in fine needle aspiration cytology (FANC) with histologic findings and prognostic factors including histologic grading, lymph node metastasis and stage, 79 cases of infiltrating ductal carcinoma diagnosed by FANC and confirmed by histology were analysed. We especially attempted to col relate nuclear grade, cellularity and smear pattern with histologic grade, type, status of lymph node metastasis and stage. The results are as fellows. 1. High nuclear grade was correlated with high histologic grade, lymph node metastasis and advanced stage. 2. Individual cell pattern was more frequently identified in high histologic grade and scirrhous or solid-tubular type than in low histolgic grade and papillotubular type. 3. Cellularity increased with higher histologic grade and lymph node metastsis. However cellularity was low in scirrhous type. 4. There is no relationship between nuclear grade and histologic type, between smear pattern and lymph node metastasis or stage, and between cellularity and stage. These results suggest that cytologic findings of breast carcinoma such as nuclear grade, cellularity and smear pattern are indicative of histologic findings in relation to histolgic grade and type. Especially, nuclear grade of FANC may yield valuable prognostic information.