• The Korean Journal of Physiology and Pharmacology
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• 제12권4호
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• pp.137-142
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• 2008

Ceramide has emerged as a novel second messenger for intracellular signalling. It is produced from sphingomyelin and is involved in the control of cell differntiation, proliferation, and apoptosis. $C_2$-ceramide, short chain ceramide, plays a role in mediating contraction of cat esophageal smooth muscle cells. We examined the effect of synthesized ceramide analogues on the $C_2$-ceramide and ACh-induced contraction in esophageal smooth muscle cells isolated with collagenase. CY3523, CY3525, or CY3723 inhibited $C_2$-ceramide induced contraction, in a time dependent manne. Each analogue also inhibited the contraction in concentration dependent manners. CY 3523, CY 3525, and CY 3723 had no effect to the contraction induced by PMA. The inhibition with CY3523, CY3525 and CY3723 on the $C_2$-ceramide induced contraction was recovered by PMA. These analogues decreased the density of MAPK bands (p44/42 or p38) in the western blot. These results suggest that ceramide analogues can inhibit $C_2$-ceramide induced contraction via PKC and MAPK dependent pathway.

• Journal of Nutrition and Health
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• 제46권3호
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• pp.239-249
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• 2013

Subclinical vitamin $B_{12}$ deficiency is common in the elderly worldwide. We investigated the change of serum vitamin $B_{12}$ concentration with aging and compared anthropometric data and clinical health indicators between normal (${\geq}$ 340 pg/mL) and low (< 340 pg/mL) serum vitamin $B_{12}$ groups in 470 Korean women aged 65 years and over living in a rural area. Serum vitamin $B_{12}$ concentration showed inverse correlation with age (r = -0.0992, p < 0.05). The normal $B_{12}$ group showed significantly (p < 0.05) higher red blood cell count, hemoglobin, and hematocrit compared to the low $B_{12}$ group, however, no difference in mean corpuscular volume was observed between the two groups. The normal $B_{12}$ group showed significantly lower serum homocysteine concentration (p < 0.01) and prevalence of vitamin D (p < 0.01) or folate deficiency (p < 0.001). Bone mineral density (T-score) was significantly higher (p < 0.05) in the normal $B_{12}$ group, compared with that in the low $B_{12}$ group, and showed positive correlation (r = 0.1490, p < 0.01) with serum vitamin $B_{12}$ concentration after adjusting for age, body weight, and body mass index. No differences in anthropometric data, physical activity, and smoking and drinking habits were observed between the two groups. In conclusion, it could be suggested that older female adults with normal serum vitamin $B_{12}$ level would be less anemic and osteoporotic and more resistant to hyperhomocysteinemia associated chronic diseases than those with low serum vitamin $B_{12}$ level.

• 한국항해학회지
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• 제23권1호
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• pp.23-28
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• 1999

With a rapid progress in electronic industry we enjoy various conveniences of life. As many kinds of information equipments are supplied even to most of individuals as to be called an information society, we are exchanging much information with one another surprisingly. Consequently the occupation density of microwave frequency band is highly increased, and electromagnetic environment is getting more seriously bad. It often gives fatal blow to even human life and thus becomes serious social problems. Electromagnetic wave absorbers for anechoic chamber are needed to broaden the effective frequency bandwidth, reduce the thickness, and decrease the weight. There are various absorbers proposed for the above conditions, but they could not decisively solve it the alone requirements. The Electromagnetic wave absorber made by a conventional ferrite tile has, for example, broadened the useful frequency bandwidth by the way of forming air layer(practically use urethane foam, etc.) on the ferrite tile. Therefore, an air layer is formed between a reflection plate and a sintered Ni-Zn ferrite tile of 7 mm in thickness, which has reflectivity less than -20 dB from 30 MHz to 400 MHz in bandwidth. Accordingly, in this paper, a broadened electromagnetic wave absorber are designed, which has the reflection characteristics less than -20 dB from 30 MHz to 6,000 MHz in the bandwidth. Then we achieved the goal by design the inserting square Ferrite Cylinders with the thickness less than 17.5 mm on existing grid type Ferrite absorber. The purpose of this research is on the development of very wide-band electromagnetic absorber for a universal anechoic chamber for measuring radiated electromagnetic wave or immunity of electronic equipments, GTEM-cell, wall material for preventing TV ghost, etc.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.137-141
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• 2002

Anabaena variabilis ATCC 29413 grew in chromium (Cr) containing Chu-10 (basal) and nitrate-supplemented media, and the growth of the organism in $100{\mu}M$ chromium was found to be 50% of that in control medium. The growth in nitrate $({NO_3}^-)$ supplemented cultures was better as compared to cultures grown in basal medium. Free cells from basal and nitrate-supplemented media removed 5.2 and 7.4 nmol of chromium $mg^{-1}$protein in 8 h, respectively, from the medium containing $30{\mu}M$ chromium. The efficiency of chromium removal increased 7-fold in imidazole buffer (0.2 M, pH 7.0). A cell density equivalent to $100{\mu}g$ protein $ml^{-1}$ was found to be optimum for maximum Cr removal. Entrapment of cells in calcium-alginate beads did not affect the rate of Cr uptake by the cells. The efficiency of the laboratory-scale continuous flow bioreactor $(12.5{\times}2cm)$ loaded with alginate-immobilized cells (10 mg protein) and fed with $30{\mu}M$ chromium solution was compared at different flow rates. The efficiency of the bioreactor varied with flow rates. In terms of percent removal of Cr from influent, a flow rate of 0.1 ml $min^{-1}$ was found to be optimum for 6 h (54% Cr removal efficiency). Maximum amount of Cr (883 nmol) was removed by the cells in 3 h at a flow rate of 0.5 ml $min^{-1}$. The potential use of A. variabilis in removing Cr from industrial effluents is discussed.

• Journal of Microbiology and Biotechnology
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• 제20권2호
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• pp.271-280
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• 2010

Vibrio alginolyticus, a Gram-negative marine bacterium, is one of the causative agents of fish vibriosis. Its virulence factors and pathogenesis mechanism are barely known, except for some extracellular products (ECPs) that are known to be regulated by quorum sensing system. Therefore, the present study used a microarray to analyze the transcription profiles of the wild-type V. alginolyticus and a deletion mutant of luxO, the pivotal regulator in Vibrio quorum sensing systems, which resulted in the identification of a putative virulence factor, MviN. Quantitative real-time reverse transcription PCR confirmed that the transcription of mviN was upregulated in the luxO mutant when compared with wild-type, and down regulated in a luxO-con complemented strain. Furthermore, Western blotting indicated that MviN was greatly induced during the late-exponential and stationary phases of growth, indicating that the expression of MviN was cell-density dependent and quorum sensing regulated in V. alginolyticus. Meanwhile, the mviN null mutant displayed a much slower growth rate than the wild type, signifying the essential role of MviN in V. alginolyticus. Western blotting also revealed that MviN was present as an extracellular protein in V. alginolyticus. When epithelioma papulosum cyprini (EPC) cells were treated with the ECPs of the mviN mutant, no cytotoxicity was observed, whereas EPC cells treated with the wild type exhibited pathological changes, which increased with the ECPs concentration and treatment time. Therefore, the results demonstrated that MviN is a LuxO-regulated ECPs component and involved in the pathogenicity of V. alginolyticus.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.690-694
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• 2015

최근에 직접 액체 연료전지 중에서 직접 개미산 연료전지(Direct Formic Acid Fuel Cells, DFAFC)가 활발히 연구되고 있다. 불소계막을 대신할 저가의 탄화수소막이 DFAFC막으로 주목받고 있다. 본 연구에서는 sulfonated poly(ether ether ketone ketone, sPEEK)막과 Poly(arylene ether sulfone)(PAES)막을 사용해 Nafion 막과 그 특성을 DFAFC 조건에서 비교하였다. 탄화수소계막의 개미산 투과 전류밀도가 $240{\sim}250mA/cm^2$로 불소계인 Nafion 211 막의 $600mA/cm^2$보다 낮았다. sPEEK MEA(Membrane and Electrode Assembly)와 Nafion 211 MEA의 막 저항이 서로 비슷해 I-V 성능도 거의 같았다. 개미산 투과도가 낮은 sPEEK MEA가 Nafion 211 MEA보다 안정함을 보였다.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.667-671
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• 2015

Anode는 효소를 이용한 효소전극과 cathode는 PEMFC용 전극을 이용해 효소연료전지를 구동하였다. 효소 anode는 graphite 분말과 효소로서 글루코스 산화제, 전자매개체로 ferrocene을 혼합해 압축해서 만들고 Nafion 이오노머로 코팅하였다. Anode 제조조건을 변화시키며 성능을 측정해 효소 anode 제조 최적조건을 찾았다. 효소 anode 압축 시 최적 압력은 8.89 MPa이고, 효소 anode의 graphite 성분비가 60%일 때 최고의 출력밀도를 나타냈다. Anode 기질 용액의 최적 glucose 농도는 1.7mol/l이었다. 효소 anode는 Nafion 용액에 1초, 2회 침지에 의해 안정화되었다.

• 한국산학기술학회논문지
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• 제18권3호
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• pp.681-686
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• 2017

태양광 모듈에서 태양전지를 연결해주는 인터커넥터로 리본 솔더로 SnPbAg가 사용되고, 옥외 태양광 발전에 장기간 노출시 리본의 부식으로 인한 열화가 흔히 관찰된다. 이러한 부식현상으로 인하여 리본과 태양전지의 접합이 약해져 접촉저항이 증가하고, 또한 리본 자체의 직렬 저항이 증가하게 되어 태양전지의 전압 전류 곡선에서 충진률 손실로 출력이 저하된다. 본 논문에서는 리본의 부식을 완화시킬 수 있는 방법으로 희생양극법을 이용하여 순수 알루미늄 및 아연, 알루미늄, 아연 그리고 마그네슘의 합금을 이용한 5가지 희생양극 소재의 부식에 의한 열화 저감을 연구하였다. 전기화학적 방법으로 희생양극 소재의 개방회로 전위와 폐쇄회로 전위를 측정하였고, 포텐시오다이나믹 분극 곡선을 측정하고, 영저항전류계를 이용하여 리본과 소재간의 갈바닉 전류를 측정하였다. 또한, 아세트산과, NaCl에 리본과 희생양극 소재의 부착 전후의 침지시험과 4셀 미니모듈로 제작한 후 1500시간 고온고습 시험 전후 출력을 평가하였다. 그 결과 Al-3Mg와 Al-3Zn-1Mg의 희생양극 소재가 부식속도가 느리고, 출력저하를 저감시킬 뿐만 아니라 장기 안정성에도 효과적인 것으로 평가된다.

• 한국태양에너지학회 논문집
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• 제23권1호
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• pp.1-8
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• 2003

Various efforts to combine new high-tech materials with solar system have been progressed nowadays in order to improve the performance of the existing passive solar system. TIM(Transparent Insulation Material) replacing the conventional outer building envelope glazing as well as the wall is good example for this trend. TI integrated wall is a thermal mass wall with a special shaped TIM instead of using typical envelope materials The tested TIM type is a small(diameter 4mm and thickness 50mm) capillary tube of Okalux model and cement brick(density 1500kg/m3). The purpose of this study was to analyze the thermal performance through the actual measurements performed in a test cell. This study was carried out to justify the following issues. 1) the impact of Tl-wall over the temperature variations 2) the impact of mass wall surface absorptance over the transient thermal behavior and 3) the impact of thermal mass wall thickness over the temperature variations. Finally, as results indicated that the peak time of room temperature was shifted about one hour early when absorptance of thermal mass wall changed from 60% to 95% for the 190mm thickness thermal mass wall test case. the temperature difference of both surfaces of thermal mass wall surface showed about $23^{\circ}C$ during a day of March for the 380mm thickness thermal mass wall case. However, the thermal mass wall was over-heated by outside temperature and solar radiation in a day of May the temperature difference of both surfaces of thermal mass wall surface was indicated $10^{\circ}C$ and inside temperature was observed more than average 22C.

• 박물관보존과학
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• 제2권
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• pp.27-34
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• 2000

다호리 출토 목재의 수종은 전체 24점 모두 활엽수 8종류로 상수리나무류(37.7%), 밤나무(8.3%), 벚나무속(8.3%), 감탕나무속(4.1%), 오리나무류(25%), 산복사류(4.1%), 느티나무(4.1%), 물푸레나무속(8.3%)으로 식별되었다. 출토목재의 물리적 특성은 현생재에 비해 높은 함수율과 수축율 그리고 현저한 밀도 감소를 나타내었다. 분해상태는 편광현미경 관찰결과 현생재에 비해 모든 출토목재의 도관을 제외한 나머지 부분에서 복굴절현상 감소가 뚜렷하게 나타났으며 주사전자현미경 관찰에서는 목섬유의 2차 세포벽을 포함한 구성조직이 현저하게 분해되었다. 분해가 많이 된 목재는 개방성이 확대되어 약제의 침투·확산이 용이하므로 처리기간이 짧고, PEG#4000(MW:3,350)을 적용한 고분자약제 함침처리가 유리하며 고농도의 함침 처리가 요구된다.