• 대한의생명과학회지
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• 제28권4호
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• pp.237-246
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• 2022

Ischemia-reperfusion results in excess reactive oxygen species (ROS) that affect myocardial cell damage. ROS production inhibition is effectively proposed in treating cardiovascular diseases including myocardial hypertrophy. Studies have shown that oxidizing cultured cells in in vitro experiments gradually decreases the permeability of mitochondrial membranes time- and concentration-dependent, resulting in increased mitochondrial membrane damage due to secondary ROS production and cardiolipin loss. However, recent studies have shown that 5-iodo-6-amino-1,2-benzopyrone (INH₂BP), an anticancer and antiviral drug, inhibited peroxynitrite-induced cell damage in in vitro and alleviated partial or overall inflammation in animal experiments. Therefore, in this paper, we studied the preventive effect of INH₂BP on H9c2 cells derived from mouse heart damaged by oxidative stress using 700 μM of hydrogen peroxide. As a result of oxidative stress to H9c2 cells by hydrogen peroxide whether the treatment of INH₂BP or not, hydrogen peroxide caused serious damage in H9c2 cells. These results were confirmed with cell viability and Hoechst 33342 assays. And this damage was through cell death. However, it was confirmed that H9c2 cells pretreated with INH₂BP significantly reduced cell death by hydrogen peroxide. In addition, measurements with DCF-DA assay to determine whether ROS is produced in H9c2 cells treated with only hydrogen peroxide produced ROS significantly, but H9c2 cells pretreated with INH₂BP significantly reduced ROS production by hydrogen peroxide. Taken together, it is believed that INH₂BP can be useful for the prevention and treatment of cardiovascular diseases induced through oxidative stress such as heart damage caused by ischemia/reperfusion.

• 폴리머
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• 제34권1호
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• pp.45-51
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• 2010

본 연구는 직접메탄을 연료전지에 적용하기 위하여 poly(vinyl alcohol)를 주쇄부로 하여 poly(acrylic acid-co-maleic acid)(PAM)와 [3-(trihydroxysilyl)-1-propanesulfonic acid](THS-PSA)를 도입하여 열 가교된 막을 제조하였다. 제조된 막의 특성화를 평가하기 위하여 FT-IR, 열 중량분석, 함수율, 이온교환용량, 이온전도도, 메탄올 투과도 등의 측정을 실시하여 Nafion 115와 비교하였다. 제조된 막의 이온교환용량은 Nafion 115의 0.91 meq./g membrane보다 향상된 1.6~1.8 meq./g membrane을 얻었다. 또한, 이온전도도의 경우 THS-PSA을 도입하여 Nafion 115($0.024\;S{\cdot}cm^{-1}$)보다 우수한 $0.042{\sim}0.056\;S{\cdot}cm^{-1}$을 얻을 수 있었으며, 가교온도에 의하여 영향을 받는다는 것을 알 수 있었다. 또한, 메탄올투과도의 경우 PAM과 THS-PSA의 도입으로 인하여 이온교환용량 및 이온전도도가 증가한 반면에 메탄올투과도는 모든 막의 경우 Nafion 115의 경우보다 높은 메탄올투과도를 나타냄을 확인하였다.

• Macromolecular Research
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• 제13권4호
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• pp.314-320
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• 2005

Crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at various crosslinking temperatures using poly(acrylic acid-co-maleic acid) (PAM) containing different PAM contents. The thermal properties of these PVA/PAM membranes prepared at various reaction temperatures were characterized using differential scanning calorimetry (DSC). The proton conductivity and methanol permeability of PVA/PAM membranes were then investigated as PAM content was varied from 3 to 13 wt%. It was found that the proton and methanol transport were dependent on PAM content in their function both as crosslinking agent and as donor of hydrophilic -COOH groups. Both these properties decreased monotonously with increasing PAM concentration. The proton conductivities of these PVA/PAM membranes were in the range from $10^{-3}\;to\;10^{-2}S/cm$ and the methanol permeabilities from $10^{-7}\;to\;10^{-6}cm^{2}/sec$. In addition, the effect of operating temperature up to $80^{\circ}C$ on ion conductivity was examined for three selected membranes: 7, 9 and 11 wt% PAM membranes. Ion conductivity increased with increasing operating temperature and showed and S/cm at $80^{\circ}C$, respectively. The effects of crosslinking and ionomer group concentration were also examined in terms of water content, ion exchange capacity (IEC), and fixed ion concentration. In addition, the number of water molecules per ionomer site was calculated using both water contents and IEC values. With overall consideration for all the properties measured in this study, $7{\sim}9\;wt%$ PAM membrane prepared at $140^{\circ}C$ exhibited the best performance. These characteristics of PVA/PAM membranes are desirable in applications related to the direct methanol fuel cell (DMFC).

• Korean Chemical Engineering Research
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• 제45권3호
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• pp.304-309
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• 2007

본 연구에서는 감압법 및 열자극법에 의한 메탄하이드레이트 생산실험을 수행하기 위해 고압의 다중공 평판형 셀기기를 설계 제작하였다. 이 실험장비를 이용하여 고투과성 미고결 시료 공극시스템에서 감압법과 열자극법에 의한 생산실험을 수행하여 생산메카니즘을 분석하였다. 감압법에 의한 생산실험 결과, 일반 가스전과는 달리 하이드레이트 해리에 의한 공극내에서의 소스효과로 인해 일시적으로 압력이 상승하고 또한 흡열반응으로 인해 온도가 하강함을 확인 하였으며, 열자극 생산실험을 수행한 결과에서는 감압법의 경우 열자극법에 비해 해리속도가 느리게 진행되어 가스생산이 낮은 상태로 지속되는 것으로 나타났다. 한편, 열자극법 중 열을 가한 후 곧바로 생산하는 경우, 주입지점 주변에서만 해리되고 또한 그 지역에서만 투과도가 커지는 것으로 나타났으며, 생산초반 이후 해리속도는 soaking까지 시행한 경우에 비해 해리가 느리게 진행됨을 알 수 있다. 한편, 본 연구의 낮은 하이드레이트 포화도를 갖는 미고 결시료 공극시스템에서 열자극법의 적정 soaking 시간 규명실험을 통해 압력과 생산거동을 고찰하였다. 그 결과, 6분간 soaking 한 경우, 온도 하강에 의한 하이드레이트의 재형성으로 2분 및 4분간 soaking한 경우보다 낮은 회수율을 보였다. 본 연구의 실험결과는 향후 높은 하이드레이트 포화도를 갖는 고결 시료 공극시스템에서의 실험을 통해 더욱 확연히 드러날 것으로 예상된다.

• 대한본초학회지
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• 제32권2호
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• pp.87-95
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• 2017

Objectives : Infectious diseases by Methicillin-Resistant Staphylococcus aureus (MRSA) are a growing problem worldwide. Characteristic of MRSA is endlessly mutation to resist antibiotics. Daehwanggo (DHG) is one of the oriental medicine prescriptions contained in Principles and Practice of Eastern Medicine. Daehwanggo was mainly used for external preparation from old times. The purpose of this study is to confirm possibility as supplementary drug of DHG about antibiotics through observation of synergy effect between DHG and commercial antibiotics and to observe restriction on growth of MRSA on any pathway through observation of mechanism. Methods : The minimum inhibitory concentration (MIC) of DHG against MRSA is $500{\sim}2000{\mu}g/m{\ell}$ by broth dilution method. In the checkerboard method, the combinations of DHG with antibiotics has partial synergistic effect or synergy effect and DHG markedly reduced the MICs of the antibiotics oxacillin (OX), gentamicin (GT) against MRSA. In the inhibition of resistance mechanism of DHG against MRSA, the expression of resistance gene and protein about ${\beta}-lactam$ antibiotic was reduced. Also, we observed the effect of DHG about cell membrane permeability against MRSA, and confirmed that DHG suppressed growth of strains by increasing cell membrane permeability. Results : Basis on the result, we speculate that DHG increase antibacterial activity of antibiotics against MRSA by changing the structure of cell wall of MRSA. Conclusions : These data suggest that Daehwanggo possesses possibility as supplementary drug about antibiotics against MRSA.

• 전기화학회지
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• 제12권2호
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• pp.173-180
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• 2009

DMFC (Direct Methanol Fuel Cell)용의 새로운 고분자 전해질 멤브레인을 개발하기 위하여 스티렌 단량체를 poly(tetrafluoroethylene perfluoropropyl vinyl ether) (PFA) 필름에 그라프트 중합 반응시킨 후에 술폰화 반응을 진행하였다. $\Upsilon$-ray를 이용하여 방사선 그라프트 중합 반응시킨 방사선 그라프트 필름의 술폰화 반응은 chlorosulfonic acid/dichloroethane (5 v/v%) 혼합 용액에서 진행하였다. PFA 그라프트 폴리스티렌 멤브레인 (PFA-g-PSSA)의 화학적, 물리적, 전기화학적 및 형태의 특성은 푸리에 변환 적외선 분광기 (FTIR), 이온전도도 측정기 및 주사전자현미경 (SEM)으로 분석하고 함수율과 메탄올 투과도도 측정하였다. PFA-g-PSSA 멤브레인으로 제작한 MEA의 단위전지 성능을 평가하였고, 전지의 셀 저항은 임피던스 분석 장치를 이용하여 측정하였다. PFA-g-PSSA 멤브레인으로 제조한 MEA는 Nafion 112로 제조한 MEA보다 우수한 DMFC 성능을 나타내었다.

• Clinical and Experimental Reproductive Medicine
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• 제14권2호
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• pp.93-100
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• 1987

To determine the effect of calcium on the preimplantational development of mouse two-cell embryo, the various concentrations of calcium were added into the culture media and the rate of blastocyst formation was observed. Also, to examine the effect of trifluoperazine, an inhibitor of calmodulin which is involved in the several intracellular calcium functions, embryos were cultured for 48 hours at the various concentrations of this inhibitor. An additional 24 hour culture was done to examine the effect of this drug on the transformation from morula to blastocyst. The results are as following ; 1. About 1.71mM of extracellular calcium is adequate for blastocyst formation and the higher concentrations of calcium (3.43mM and 8.55mM) do not affect on the blastocyst formation and the degenerating rate. 2. Trifluoperazine $100{\mu}M$ presents the inhibitory effect on the blastocyst formation while $1{\mu}M$ and $10{\mu}M$ do not so. 3. After an additional 24 hour culture, there is transformation of morula to blastocyst and the degenerating rate of embryo is increased all together.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.90.2-90.2
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• 2010

The coated metallic bipolar plates are getting attractive due to their good feasibility of mass production, low contact resistance, high electrical/thermal conductivity, low gas permeability and good mechanical strength comparing with graphite materials. Yet, metallic bipolar plates for polymer electrolyte membrane(PEM) fuel cells typically require coatings for corrosion protection. Other requirements for the corrosion protective coatings include low electrical contact resistance between metallic bipolar plate and gas diffusion layer, good mechanical robustness, low mechanical and fabrication cost. The authors have evaluated a number of protective coatings deposited on stainless steel substrate by electroplating. The coated metallic bipolar plates are investigated with an electrochemical polarization tests, salt dipping tests, adhesion tests for corrosion resistance and then the contact resistance was measured. The results showed that the selective samples electroplated with optimized method, satisfied the DOE target for corrosion resistance and contact resistance, and also were very stabilized in the typical fuel cell environments in the long-term.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.87.1-87.1
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• 2010

Metallic bipolar plate is the one of the promising candidate material for PEMFC because of mechanical strength, low gas permeability, electrical and thermal conductivity. However, the corrosion is the main obstacle of metallic bipolar plate, and many investigations, especially coating on base metal, have been carried out to avoid corrosion. Gold is considered as the one of the best coating material because of its corrosion resistance and electrical conductivity. In this study, gold coated metallic bipolar plate was developed and evaluated. Due to our coating process, gold can be well-adhere to the base material, and hydrophobic material on its gold surface was coated by dipping method for better water management. To verify coating reliability, a single fuel cell(50cm2) was evaluated, and its durability over 4000hrs was demonstrated.

• BMB Reports
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• 제32권3호
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• pp.273-278
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• 1999

Cytolysin produced by Vibrio vulnificus has been known to be lethal to mice by increasing vascular permeability and neutrophil sequestration in the lung. In the present study, a cytotoxic mechanism of V. vulnificus cytolysin on the neutrophil was investigated. Cytolysin rapidly bound to neutrophils and induced cell death, as determined by the trypan blue exclusion test. V. vulnificus cytolysin caused the depletion of cellular ATP without the release of ATP or lactate dehydrogenase. Formation of transmembrane pores was evidenced by the rapid efflux of potassium and 2-deoxy-D-[$^3H$]glucose from cytolysin-treated neutrophils. It was further confirmed by the rapid flow of monovalent ions in the patch clamp of cytolysin-treated neutrophil membrane. The pore formation was accompanied by the oligomerization of cytolysin monomers on the neutrophil membrane as demonstrated by immunoblot, which exhibited a 210 kDa band corresponding to a tetramer of the native cytolysin of $M_r$ 51,000. These findings indicate that V. vulnificus cytolysin rapidly binds to the neutrophil membrane and oligomerizes to form small transmembrane pores, which induce the efflux of potassium and the depletion of cellular ATP leading to cell death without cytolysis.