• Transactions of the Korean hydrogen and new energy society
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• v.18 no.2
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• pp.157-163
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• 2007

During PEMFC operation, low current and low humidity conditions accelerate the degradation of perfluorosulfonic acid membrane. But, there have been no studies that clearly explain why these conditions accelerate the membrane degradation. In this study, the hydrogen permeability through the membrane, I-V polarization of MEA, fluoride emission rate(FER) in effluent water were measured during cell operation under low current densities and low relative humidity(RH). The experimental results were evaluated with oxygen radical mechanism the most commonly known for membrane degradation. It seems that low RH of anode is a good condition for $H{\cdot}$ radical formation on the Pt catalyst and the low current condition accelerates the $H{\cdot}$ to form $HO_2{\cdot}$ radical attacking the polymer membrane.

• KSBB Journal
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• v.18 no.6
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• pp.435-439
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• 2003

Plant cell culture can be divide into two classes non-organic culture and organic culture. Non-organic culture such as suspension culture has many researches, however organic culture about recombinant protein production has little researches. Recombinant protein produced through organ culture is quite stable and it can make proteins by itself without any grow regulators. Therefore organ culture is much easier than other methods. In this research, we used transformed tobacco seed. At first we germinated the seed then separated stems and leaves from the grown plant. And raised in liquid medium by in vitro vegetative reproduction. Continuing most suitable conditions, we compared the Quantities of recombinant protein from intra cellular with from extra cellular. And adding some permeabilizing agents (Pluronic F-68, Triton X-100, DMSO, PEG8000), we increased the productivity of the recombinant protein.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.1
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• pp.29-35
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• 2016

It is important to uniformly supply the fuel gas into the reaction activity area in polymer electrolyte membrane fuel cell (PEMFC). Recent studies have shown that the cell performance can be significantly improved by employing metal foam gas distributor as compared with the conventional bipolar plate types. The metal foam gas distributor has been reported to be more efficient to fuel transport. In this study, three-dimensional computational fluid dynamics (CFD) simulations have been performed to examine the effects of metal foam flow field design on the fuel supply to the reaction site. Darcy's law is used for the flow in the porous media. By solving additional advection equation for fluid particle trajectory, the gas transport has been visualized and examined for various geometrical configuration of metal foam gas distributor.

• Macromolecular Research
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• v.15 no.5
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• pp.459-464
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• 2007

Polymer electrolyte membranes, featuring ionic channels, were prepared from sulfonated dextran/ poly(vinyl alcohol) (sD/PVA) membranes. A stiff sulfated dextran was chosen as the route for ionic transport, since ionic sites are located along the stiff dextran main chain. The sD/PVA blend membranes were annealed and then chemically crosslinked. The characteristics of the crosslinked sD/PVA membranes were investigated to determine their suitability as proton exchange membranes. The proton conductivity was found to increase with increasing amounts of sD inside the membrane, which reached a maximum and then decreased when the sD content exceeded 30 wt%, while the methanol permeability increased with increasing sD content. The good dispersion of sD inside the membrane, which serves as an ionic channels mimic, played a significant role in proton transportation.

• International Journal of Advanced Culture Technology
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• v.7 no.3
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• pp.10-24
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• 2019

This study aimed to investigate the effects and epidermis penetration system with polymer micelle of Red Pinus densiflora extract. In the antioxidant test, the total concentration of polyphenol compounds was determined to be $137.5163{\pm}7.70mg/g$ in ethanol extract, $133.956{\pm}1.57mg/g$ in hydrothermal extract. The DPPH radical scavenging effects were $95.29{\pm}0.15%$ in ethanol extract at 1,000 mg/L. Elastase inhibition rates were $100.00{\pm}2.85%$ in ethanol extract at 2,000 mg/L. The antimicrobial effect of the ethanol extraction was higher than that of hydrothermal extractions. In the epidermal permeability experiment, it was confirmed that the permeation of the polymer micelle containing the Red Pinus densiflora's ethanol extract and cell penetrating peptides was remarkable. Here, we confirmed that ethanol extract of Red Pinus densiflora displayed excellent the effects in antioxidant test and epidermis penetration system with polymer micelle. As a result, Red Pinus densiflora extract has potential to be used as a safe and natural cosmetic material in the future.

• Journal of Microbiology and Biotechnology
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• v.32 no.8
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• pp.1003-1010
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• 2022

The purpose of this study was to examine the phytochemical compounds and antibacterial activity of Coffea robusta leaf extract (RLE). The results indicated that chlorogenic acid (CGA) is a major component of RLE. The minimum inhibitory concentrations (MICs) of RLE against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella Typhimurium were 6.25, 12.5, 12.5, and 12.5 mg/ml, respectively. RLE effectively damages the bacterial cell membrane integrity, as indicated by the high amounts of proteins and nucleic acids released from the bacteria, and disrupts bacterial cell membrane potential and permeability, as revealed via fluorescence analysis. Cytotoxicity testing showed that RLE is slightly toxic toward HepG2 cells at high concentration but exhibited no toxicity toward Caco2 cells. The results from the present study suggest that RLE has excellent potential applicability as an antimicrobial in the food industry.

• Herbal Formula Science
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• v.21 no.2
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• pp.63-71
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• 2013

Objectives : Artemisia princeps is used as moxa in moxibustion and traditional herbal medicine. And its extracts or compounds is known to have an efficacy of antioxidant, anti-diabete, anti-cancer, anti-inflammation and neuroprotection. This study was performed to investigate the cytoprotective effect of Artemisia princeps extract (APE) against arachidonic acid (AA)+iron-induced oxidative stress on HepG2 cell. Methods : The effects of APE on cell viability has been assessed using MTT assay. And flow cytometric analysis was performed to estimate APE's effects on mitochondrial function. To investigate its underlying mechanism, related protein was analysed by using immunoblot analysis. Results : Treatment of APE increased relative cell viability, prevented a decline of B-cell lymphoma-extra large (Bcl-xL) and cleavage of poly(ADP-ribose) polymerase (PARP) and procaspase-3, and also protected mitochondrial membrane permeability (MMP) against oxidative stress induced by AA+iron. In addition, APE treatment increased phosphorylation of AMP-activated protein kinase (AMPK) exerts a cytoprotective effect. Conclusions : This results demonstrate that APE has an ability to activation of AMPK which protects cells from AA+iron-induced oxidative stress and restores MMP.

• Herbal Formula Science
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• v.25 no.2
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• pp.155-166
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• 2017

Objectives : Polygoni Multiflori Ramulus has been widely used as a traditional medicinal herb for the treatment of insomnia, limb pain and itch. The extract of Polygoni Multiflori Ramulus (PMRE) is known to have a modulatory effect of many inflammatory responses. This study was performed to investigate the hepatoprotective effect of PMRE against arachidonic acid (AA) + iron-induced oxidative stress on HepG2 cell and carbon tetrachloride ($CCl_4$)-induced liver injury on mice. Methods : The effects of PMRE on cell viability was assessed by MTT assay. And flow cytometric analysis was performed to estimate the effects on mitochondrial function. To investigate its underlying mechanism, apoptosis-related proteins were analysed by using immunoblot analysis. In addition, ICR mouse were administrated (po) with the PMRE (30, 100 mg/kg) for 3 days and then, injected (ip) with $CCl_4$ (0.5 ml/kg body weight) to induce acute liver damage. The level of pro-caspase-3 was measured. Results : Treatment of PMRE increased relative cell viability, prevented a cleavage of poly (ADP ribose) polymerase and pro-caspase-3, and also reduced mitochondrial membrane permeability against AA + iron-induced oxidative stress. In addition, PMRE treatment decreased liver injury induced by $CCl_4$, as evidenced by increases in pro-caspase-3 level. Conclusions : These results demonstrate that PMRE has an ability to anti-oxidant and hepatoprotective effect against AA + iron-induced oxidative stress and $CCl_4$-induced liver injury.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.2
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• pp.404-409
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• 2006

Cimicifuga racemosa (Black cohosh) has been used as therapeutics for pain and inflammation in Korean folk medicine. The potential effects of cimicifuga racemosa extract on mast cell dependent allergy reaction, however, have not been well elucidated yet. In the present study, we investigated the effect of cimicifuga racemosa extract on the allergy reaction using mast cell dependent in vivo and in vitro models. The oral administration of cimicifuga racemosa extract showed inhibitory potential on the compound 48/80 induced active systemic anaphylactic shock. cimicifuga racemosa extract also significantly inhibited the anti DNP IgE induced passive cutaneous anaphylaxis (PCA) reaction and acetic acid induced vascular permeability. In addition, cimicifuga racemosa extract inhibited the beta hexosaminidase release and TNF alpha and IL 4 mRNA induction by DNP HSA in rat leukemia mast cells, RBL 2H3. but cimicifuga racemosa extract didn't affected to RBL 2H3 cell viability. These results demonstrated that cimicifuga racemosa extract has an anti allergic potential and it may be due to the inhibition of histamine release and cytokine gene expression in the mast cells.

• Journal of Pharmacopuncture
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• v.18 no.3
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• pp.32-41
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• 2015

Objectives: Condurango (Gonolobus condurango) extract is used by complementary and alternative medicine (CAM) practitioners as a traditional medicine, including homeopathy, mainly for the treatment of syphilis. Condurango bark extract is also known to reduce tumor volume, but the underlying molecular mechanisms still remain unclear. Methods: Using a cervical cancer cell line (HeLa) as our model, the molecular events behind condurango extract's (CE's) anticancer effect were investigated by using flow cytometry, immunoblotting and reverse transcriptase-polymerase chain reaction (RT-PCR). Other included cell types were prostate cancer cells (PC3), transformed liver cells (WRL-68), and peripheral blood mononuclear cells (PBMCs). Results: Condurango extract (CE) was found to be cytotoxic against target cells, and this was significantly deactivated in the presence of N-acetyl cysteine (NAC), a scavenger of reactive oxygen species (ROS), suggesting that its action could be mediated through ROS generation. CE caused an increase in the HeLa cell population containing deoxyribonucleic acid (DNA) damage at the G zero/Growth 1 (G0/G1) stage. Further, CE increased the tumor necrosis factor alpha ($TNF-{\alpha}$) and the fas receptor (FasR) levels both at the ribonucleic acid (RNA) and the protein levels, indicating that CE might have a cytotoxic mechanism of action. CE also triggered a sharp decrease in the expression of nuclear factor kappa-light-chain-enhancer of activated B cells ($NF-{\kappa}B$) both at the RNA and the protein levels, a possible route to attenuation of B-cell lymphoma 2 (Bcl-2), and caused an opening of the mitochondrial membrane's permeability transition (MPT) pores, thus enhancing caspase activities. Conclusion: Overall, our results suggest possible pathways for CE mediated cytotoxicity in model cancer cells.