• The Korean Journal of Physiology and Pharmacology
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• 제10권1호
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• pp.51-58
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• 2006

The promoting effect of hydrogen peroxide ($H_2O_2$) against the cytotoxicity of 1-methyl-4-phenylpyridinium ($MPP^+$) in differentiated PC12 cells was assessed by measuring the effect on the mitochondrial membrane permeability. Treatment of PC12 cells with $MPP^+$ resulted in the nuclear damage, decrease in the mitochondrial transmembrane potential, cytosolic accumulation of cytochrome c, activation of caspase-3, increase in the formation of reactive oxygen species (ROS) and depletion of GSH. Addition of $H_2O_2$ enhanced the $MPP^+-induced$ nuclear damage and cell death. Catalase, Carboxy-PTIO, Mn-TBAP, N-acetylcysteine, cyclosporin A and trifluoperazine inhibited the cytotoxic effect of $MPP^+$ in the presence of $H_2O_2$. Addition of $H_2O_2$ promoted the change in the mitochondrial membrane permeability, ROS formation and decrease in GSH contents due to $MPP^+$ in PC12 cells. The results show that the $H_2O_2$ treatment promotes the cytotoxicity of $MPP^+$ against PC12 cells. $H_2O_2$ may enhance the $MPP^+$-induced viability loss in PC12 cells by promoting the mitochondrial membrane permeability change, release of cytochrome c and subsequent activation of caspase-3, which is associated with the increased formation of ROS and depletion of GSH. The findings suggest that $H_2O_2$ as a promoting agent for the formation of mitochondrial permeability transition may enhance the neuronal cell injury caused by neurotoxins.

• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.313-320
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• 2010

Carbon cloth was impregnated into PTFE emulsion. PTFE is a fluoropolymer used as a coating material in various fields due to its hydrophobicity and excellent mechanical properties. In this study, PTFE emulsion was prepared different particle size of 5~500 nm and $3{\sim}5{\mu}m$. FE-SEM and FT-IR spectroscopy were used microscopic observation and investigation of chemical structure change after PTFE coating. Mass variations, gas permeability and water contact angles were analyzed to determine a GDL performance of PTFE coated carbon cloth. PTFE coated carbon cloth show different mass increase according as PTFE concentration and the number of coating times. Water contact angle of PTFE coated carbon cloth was not effected by size of PTFE particle and the number of coating time; meanwhile, gas permeability was rapidly changed at carbon cloth coated by emulsion with size of $3{\sim}5{\mu}m$ PTFE particle.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.424-431
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• 2009

Treatment for water repellency on the carbon supports of GDL which composed a part of MEA has been suggested as a solution to prevent flooding. PTFE is a fluoropolymer that has hydrophobic property and a PTFE emulsion was selected as waterproof agent in this investigation. Carbon paper was coated by PTFE emulsion with different particle size of 5~500 nm and 3~$5\;{\mu}m$ as various concentration. PTFE coated carbon paper has difference in weight variation changed proportionally at PTFE concentration and coating times. Then gas permeability of the coated carbon paper with emulsion of 3~$5\;{\mu}m$ PTFE was changed vastly. Characteristics of carbon paper coated with different PTFE emulsion were analyzed by FE-SEM, FT-IR spcetroscopy and were evaluated by weight variations, gas permeability and water contact angle.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.25-28
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• 2003

Low cost composite metallic membranes for the hydrogen separation and production have been prepared by using thin Pd-Ag foils reinforced by metallic (stainless steel and nickel) structures. Especially, “supported membranes” have been obtained by a diffusion welding procedure in which Pd-Ag thin foils have been joined with perforated metals (nickel) and expanded metals (stainless steel): in these membranes the thin palladium foil assures both the high hydrogen permeability and the perm-selectivity while the metallic support provides the mechanical strength. A second studied method of producing "laminated membranes" consists of coating non-noble metal sheets with very thin palladium layers by diffusion welding and cold-rolling. Palladium thin coatings over these metals reduce the activation energy of the hydrogen adsorption process and make them permeable to the hydrogen. In this case, the dense non-noble metal has been used as a support structure of the thin Pd-Ag layers coated over its surfaces: a proper thickness of the metal assures the mechanical strength, the absence of defects (cracks, micro-holes) and the complete hydrogen selectivity of the membrane. membrane.

• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.264-270
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• 2010

Recently, the most promising methods for high purity hydrogen production are membranes separation such as polymer, metal, ceramic and composites. It is well known that Pd and Pd-alloys membranes have excellent properties for hydrogen separation. However, it has hydrogen embrittlement and high cost for practical applications. Therefore, most scientists have studied new materials instead of Pd and Pd-alloys. On the other hand, TiN powders are great in resistance to acids and chemically stable under high operating temperature. In order to get specimens for hydrogen permeation, the TiN powders synthesized were consolidated together with Co, Ni powders by hot press sintering (HPS). During the consolidation of powders at HPS, heating rate was 10 K/min and the pressure was 10 MPa. It was characterized by XRD, SEM. Also, we estimated the hydrogen permeability by Sievert's type hydrogen permeation membrane equipment.

• Korean Chemical Engineering Research
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• 제58권4호
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• pp.524-529
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• 2020

고분자전해질 연료전지의 기계적 내구성을 높이기 위해 고분자막에 지지체를 넣은 강화막이 사용되고 있다. 지지체는 주로 e-PTFE를 사용하는데 소수성이고 이온전달이 안되므로 성능저하의 원인이 될 수 있다. 그래서 본 연구에서는 e-PTFE 지지체가 PEMFC 성능과 전기화학적 내구성 미치는 영향에 대해 연구하였다. 본연구에서는 지지체가 들어간 강화막과 들어가지 않은 단일막(비강화막)을 비교하였는데, 지지체의 소수성 때문에 강화막의 물 확산계수가 단일막보다 낮았다. 강화막은 물확산 계수가 낮아 이온의 막 이동 저항이 단일막보다 높았다. 지지체의 낮은 수소투과도 때문에 강화막의 OCV가 단일막보다 높았다. 지지체가 수소투과도를 감소시킴으로서 라디칼 발생속도를 감소시켜 강화막의 전기화학적 내구성도 향상시킴을 보였다.

• 멤브레인
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• 제22권5호
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• pp.318-325
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• 2012

PTMSP에 20 wt% PMMH dendrimer와 10, 20, 30, 40 wt% NaY zeolite를 가하여 PTMSP-PMMH-NaY zeolite 복합막을 제조하였다. 복합막의 물리화학적 특성을 FT-IR, TGA, SEM을 사용하여 조사하였고, $H_2$와 $N_2$ 기체에 대한 투과도와 선택도 성질을 고찰하였다. PTMSP-PMMH-NaY zeolite 복합막의 투과도는 zeolite 함량이 증가함에 따라 증가하였고, 수소와 질소의 투과도는 각각 3,950~592,000 barrer와 1,550~143,000 barrer를 보였다. 질소에 대한 수소의 선택도는 0~30 wt%에서는 뚜렷한 차이가 나타나지 않았고, 30~40 wt%에서는 2.2~4.2 범위로 증가하는 경향을 보였다.

• Korean Chemical Engineering Research
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• 제60권2호
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• pp.217-222
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• 2022

고분자 전해질 연료전지(PEMFC) 고분자 막의 전기화학적 내구성을 가속적으로 평가하는 개회로 전위 유지(OCV holding) 과정에서 OCV 변화 거동을 해석하는 것은 매우 중요하다. 본 연구에서는 내구성이 각기 다른 세 종류의 MEA(membrane electrode assembly)의 실험데이터를 이용한 실험식을 만들어 비교 및 검토하였다. 막 내부에 라디칼 제거제가 없는 강화막 MEA의 내구 평가시간은 383 h, 막 내부에 라디칼 제거제가 있는 강화막 MEA의 내구 평가시간은 각각 1,000, 1,650 h이었다. 고분자 막의 열화는 활성화에 의해 회복이 가능한 가역적 열화와 회복이 되지 않은 비가역적 열화로 구분했다. 고분자 막의 비가역적 열화는 수소투과도 증가로 나타나는데 수소투과도 변화가 세 MEA 모두 비가역적 열화 상수 c와 유사한 형태를 보였다. 회복이 되지 않은 비가역적 열화가 시작되는 것은 수소투과도 증가로 나타나고, 수소투과도 증가로 인해 OCV가 회복되지 않아서 OCV 회복선의 기울기가 감소하고 이를 실험식의 상수 c 값의 증가로 확인할 수 있었다.

• Journal of Magnetics
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• 제6권1호
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• pp.13-18
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• 2001

Permalloy soft magnets have been produced by the powder injection molding process. Rheological characteristics of mixtures, debinding conditions, and the magnetic properties of permalloy after sintering have been investigated. A permalloy soft magnet with a permeability of 14200 could be obtained by preparing a mixture with a powder loading of 65.4 vol % and a PP/PEG binder systems solvent extraction, thermal debinding, and subsequent sintering at 1350$\^{C}$ in hydrogen. The permalloy soft magnet sintered in hydrogen had 95% of theoretical density and a magnetic induction of 13.2 kG in an applied magnetic field of 50 Oe.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.217-227
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• 2000

The permalloy soft magnet was produced by powder injection molding process. Rheological characteristics of mixtures, debinding conditions and the magnetic properties of permalloy after sintering ware investigated. The permalloy soft magnet with a permeability of 14200 could be obtained by preparing a mixture with a powder loading of 65.4 vol.% and PP/PEG binder system, solvent extraction, thermal debinding and subsequent sintering at 1350 $^{\circ}C$ in hydrogen. The permalloy soft magnet sintered in hydrogen showed a 95 % of theoretical density and a magnetic induction of 13.2 kG at the applied magnetic field of 50 Oe