• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.985-990
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• 1995

Grapefruit seed extracts(GFSE) have some unknown compounds which exhibit the antibiotic activities aganist microorganisms including bacteria and fungi. We have examined the effects of GFSE on the growth of Enterobacter pyrinus which was isolated from necrotic lesions of pear trees. During the cultivation, the growth of the bacteria was strongly inhibited at the low concentration(0.01%, w/w) of GFSE. Hydrophobic fraction extracted from GFSE by mixed solvents (chloroform : methanol : water, 1 : 2 : 0.8, v/v/v) had components which inhibited the growth of bacteria. There was, however, no inhibitory effect of GFSE on the activities of several enzymes including hexokinase, glucose 6-phosphate dehydrogenase, malate dehydrogenase and succinate dehydrogenase. $O-nitrophenyl-{\beta}-D-galactopyranoside(ONPG)$, the artificial substrate of ${\beta}-galactosidase$ was hydrolyzed in the presence of GFSE, indicating that the membrane was pertubated by the GFSE. From the results it was suggested that the antibiotic activity of GFSE is due to the change of membrane permeability of cell. GFSE was fractionated by high performance liquid chromatography equipped with $C_{18}$ reverse phase column. Among active fractions, three peaks were identified as 1-chloro-2-methyl-benzene (o-toluene), N,N-dimethyl-benzenemethaneamine, 1-[2-(2-ethylethoxy)ethoxy]-4- (1,1,3,3-tetramethyl)-bezene, respectively, while the other three remained unidentified.

• Journal of the Korean GEO-environmental Society
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• v.14 no.5
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• pp.33-39
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• 2013

A drilling exploration in deep sea is being processed to develop new energy resource in the world. In 2007, the presence of the gas hydrate had been confirmed during the UBGH1 (Ulleung Basin Gas Hydrate Expedition 1) in the Ulleung Basin. Geotechnical properties of the deep marine sediment are important factors for assessing the safety of gas production facility and productivity from the hydrate bearing sediment. In this study, comprehensive laboratory tests are conducted to investigate the geotechnical engineering characteristics of the deep marine sediments recovered from the hydrate occurrence regions during the UBGH2 (Ulleung Basin Gas Hydrate Expedition 2) in the Ulleung Basin, East Sea, Korea. The index properties of the specimens including the specific gravity, atterberg limits, specific surface, and particle size distribution are measured, and these are compared to the results reported by previous studies. A zero-lateral strain cell, which houses bender elements, is used to determine stress-dependant characteristics and shear wave velocities with the vertical effective stresses. Furthermore, the hydraulic conductivity is calculated based on the consolidation test results.

• Archives of Pharmacal Research
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• v.24 no.2
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• pp.126-135
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• 2001

Quinacrine (QU), a phospholipase-A2 (PLA-2) inhibitor has been used clinically as a chemotherapeutic adjuvant. To understand the mechanisms leading to its chemotherapeutic effect, we have investigated QU-induced apoptotic signaling pathways in human cervical squamous carcinoma HeLa cells. In this study, we found that QU induced cytochrome c-dependent apoptotic signaling. The release of pro-apoptotic cytochrome c was QU concentration- and time-dependent, and preceded activation of caspase-9 and -3. Flow cytometric FACScan analysis using fluorescence intensities of $DiOC_6$/ demonstrated that QU-induced cytochrome c release was independent of mitochondrial permeability transition (MPT), since the concentrations of QU that induced cytochrome c release did not alter mitochondrial membrane potential (${\blacktriangle}{\Psi}_m$). Moreover, kinetic analysis of caspase activities showed that cytochrome c release led to the activation of caspase-9 and downstream death effector caspase-3, Caspase-3 inhibitor (Ac-DEVD-CHO) partially blocked QU-induced apoptosis, suggesting the importance of caspase-3 in this apoptotic signaling mechanism. Supplementation with arachidonic acid (AA) sustained caspase-3 activation induced by QU. Using inhibitors against cellular arachidonate metabolism of lipooxygenase (Nordihydroxyguaiaretic Acid, NDGA) and cyclooxygenase (5,8,11,14-Eicosatetraynoic Acid, ETYA) demonstrated that QU-induced apoptotic signaling may be dependent on its role as a PLA-2 inhibitor. Interestingly, NDCA attenuated QU-induced cytochrome c release, caspase activity as well as apoptotic cell death. The blockade of cytochrome c release by NDCA was much more effective than that attained with cyclosporin A (CsA), a MPT inhibitor. ETYA was not effective in blocking cytochrome c release, except under very high concentrations. Caspase inhibitor z-VAD blocked the release of cytochrome c suggesting that this signaling event is caspase dependent, and caspase-8 activation may be upstream of the mitochondrial events. In summary, we report that QU induced cytochrome c-dependent apoptotic signaling cascade, which may be dependent on its role as a PLA-2 inhibitor. This apoptotic mechanism induced by QU may contribute to its known chemotherapeutic effects.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.187-192
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• 2006

The preparation and characterization of new polymer composite membranes containing polyphenylene oxide (PPO) thin films with hetropoly acid (HPA) are presented. PPO thin films with phosphotungstic acid (PWA) or phosphomolybdic acid (PMA) have been prepared by using the solvent mixture. The PWA and PPO can be blended using the solvent mixture, because PPO and PWA are not soluble in the same solvent. In this study, methanol was used as a solvent dissolving PWA and chloroform was used as a solvent dissolving PPO. PPO-PWA solutions were cast onto a glass plate with uniform thickness. The composite membranes were prepared by casting Nafion mixture on porous PPO-PWA films. The morphology and structure of these PPO-PWA films were observed with scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The composite membranes were characterized by measuring their ion conductivity and methanol permeability. The performance was evaluated with composite membranes as electrolytes in fuel cell conditions. The methanol cross-over of composite membranes containing PPO-PWA barrier films in the DMFC reduced by 66％.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.1
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• pp.43-50
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• 2008

Ceramides, a constituent of stratum corneum lipids, play a crucial role in the formation and maintenance of the epidermal permeability barrier. As in many other skin disorders, atopic dermatitis and psoriasis show decrease and transformation of the ceramides. The application of ceramide has been demonstrated to be efficient in the repair of these skin disorders. Nevertheless, natural ceramides are still too expensive and small in quantity to be used as a cosmetic ingredient. Although a lot of pseudo-ceramides have been developed and on the market until now, those pseudo-ceramides did not fully meet the consumer's needs, therefore, there is still a demand for a novel pseudo-ceramides. We synthesized a novel pseudo-ceramide BPC-16 from 2-(2-amino-ethylamino)-ethanol(AEEA), which was characterized by structures having both amide bonds and hydroxyl groups as hydrophilic units, as well as two long alkyl chains. We formulated emulsion with BPC-16, cholesterol, stearic acid, and other components to make an emulsion. These emulsion showed a typical optical anisotropy on cross-polarized microscopy. This 'Maltese cross' appearance is a characteristic figure observed in concentric lamellar emulsion under cross-polarized microscopy. In cytotoxicity assay using MTT in monolayer and three dimension(3D) cell culture, a BPC-16 showed only negligible cytotoxicity up to the effective concentration for barrier repair and moisturization(less than 10 mM). In the measurement of TEWL, this BPC-16 showed significant recovery of water-retaining properties when it was topically applied to either SDS-induced dry skin or normal skin compared to that of base cream. This novel pseudo-ceramide BPC-16 showed as effective in skin barrier repair and moisturization as natural ceramides.

• YAKHAK HOEJI
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• v.49 no.2
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• pp.185-191
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• 2005

The absorption of a P-gp substrate, rhodamine 123, from a liposomal dosage form was investigated across Caco-2 cell monolayers, rat intestines and rat intestinal Peyer's patches in Ussing chamber, Rhodamine 123 was incorporated into liposomes according to the standard evaporation method, which led to a production of liposomes with a mean diameter of 71.3 nm. The permeability (Papp of rhodamine 123 from a water solution across the monolayer was $2.45{\times}10^{-6}$ cm/s for $A{\leftrightarrow}B$ (apical to basal) and $14.0{\times}10^{-6}$ cm/s for $B{\leftrightarrow}A$ (basal to apical) directions, consistent with the fact that rhodamine 123 is one of the P-gp substrates. The transport of rhodamine 123 from the liposomal dosage form was much lower for both directions compared to the solution of rhodamine 123. The transport of rhodamine 123 across the rat intestine was also significantly decreased for both directions, I.e., influx and efflux, by the liposomal incorporation of the compound. The transport of rhodamine 123 across the Peyer's patch was substantially reduced by liposomal incorporation. No difference was found in the transport between the Peyer's patch and non-Peyer's patch. These observations suggest that the contribution of transport via Peyer's patches in the uptake of liposomes may be minimal, especially for rapidly absorbed compounds like rhodamine 123. Therefore, the increased absorption of P-gp substrates does not appear to be feasible by incorporating the compounds in liposomes, due to negligible involvement of Peyer's patches in the uptake of particulate dosage forms like liposomes. Liposomes may rather represent a sustained release dosage form of incorporated compounds.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.1-5
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• 2018

In this work, we study the ion conductivity by analyzing the impedance to the high current density range that the PEMFC (Proton Exchange Membrane Fuel Cell) is actually operated. The effect of GDL (Gas Diffusion Layer)presence on impedance was investigated indirectly by measuring hydrogen permeability. When the RH (Relative Humidity)was higher than 60% in the low current range (< $80mA/cm^2$), the moisture content of the polymer membrane was sufficient and the ion conductivity of the membrane was not influenced by the current change. However, when RH was low, ion conductivity increased due to water production as current density increased. The ion conductivity of the membrane obtained by HFR (High Frequency Resistance) in the high current region ($100{\sim}800mA/cm^2$)was compared with the measured value and simulated value. At RH 100%, both experimental and simulated values showed constant ion conductivity without being influenced by current change. At 30~70% of RH, the ionic conductivity increased with increasing current density and tended to be constant.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.24-28
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• 2018

The redox flow battery (RFB) is a large-capacity energy storage equipment, and the vanadium redox flow cell is a typical RFB, but VRFB is expensive. Iron-chrome RFBs are economical because they use low-cost active materials, but their low performance is a urgent problem. In this study, the crossover of iron and chromium ion through Nafion membrane and the stability of Nafion membrane in HCl solution were investigated. The permeability of iron and chrome ion through Nafion were $5.5{\times}10^{-5}$ and $6.0{\times}10^{-5}cm^2/min$, respectively, which was 18.9~20.7 times higher than that of vanadium ion ($2.9{\times}10^{-6}cm^2/min$). The crossover of iron and chromium ions were shown to be a cause of performance decrease in Iron-chrome RFB. As the temperature increases, the crossover increases rapidly (activation energy 38.8 kJ/ mol), indicating that operation at low temperature is a methode to reduce the performance loss due to crossover. Nafion membranes were relatively stable in 3 M HCl solution.

• Mycobiology
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• v.45 no.4
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• pp.297-311
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• 2017

Saprolegniasis is one of the most devastating oomycete diseases in freshwater fish which is caused by species in the genus Saprolegnia including Saprolegnia parasitica. In this study, we isolated the strain of S. parasitica from diseased rainbow trout in Korea. Morphological and molecular based identification confirmed that isolated oomycete belongs to the member of S. parasitica, supported by its typical features including cotton-like mycelium, zoospores and phylogenetic analysis with internal transcribed spacer region. Pathogenicity of isolated S. parasitica was developed in embryo, juvenile, and adult zebrafish as a disease model. Host-pathogen interaction in adult zebrafish was investigated at transcriptional level. Upon infection with S. parasitica, pathogen/antigen recognition and signaling (TLR2, TLR4b, TLR5b, NOD1, and major histocompatibility complex class I), pro/anti-inflammatory cytokines (interleukin $[IL]-1{\beta}$, tumor necrosis factor ${\alpha}$, IL-6, IL-8, interferon ${\gamma}$, IL-12, and IL-10), matrix metalloproteinase (MMP9 and MMP13), cell surface molecules ($CD8^+$ and $CD4^+$) and antioxidant enzymes (superoxide dismutase, catalase) related genes were differentially modulated at 3- and 12-hr post infection. As an anti-Saprolegnia agent, plant based lawsone was applied to investigate on the susceptibility of S. parasitica showing the minimum inhibitory concentration and percentage inhibition of radial growth as $200{\mu}g/mL$ and 31.8%, respectively. Moreover, natural lawsone changed the membrane permeability of S. parasitica mycelium and caused irreversible damage and disintegration to the cellular membranes of S. parasitica. Transcriptional responses of the genes of S. parasitica mycelium exposed to lawsone were altered, indicating that lawsone could be a potential anti-S. parasitica agent for controlling S. parasitica infection.

• Journal of Bio-Environment Control
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• v.12 no.1
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• pp.7-11
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• 2003

Cellular glass foam (CGF), the reprocessed glass, has a possibility to be used as a medium component in plug culture of horticultural crops due to the its excellent air and water permeability as comparable to perlite. An experiment was conducted to investigate growth of plug seedlings of Lycopersicum esculentum 'Segye' as influenced by irrigation frequency in various medium combinations of CGF (2.0-4.0 mm particle size) and peatmoss. Seeds were sown in 200-cell plug trays, filled with mixtures of CGF and peatmoss either at 33：67 or 25：75 (％. v/v) and were germinated on a fogged propagation bed. The irrigation frequencies used were one, two or three times per every two days. A commercial plug medium (Tosilee medium) was used as the control, and the irrigation frequency in the control was one time per day. Growth of seedlings, and medium pH and EC were measured at 33 days after sowing. The medium composition had little influence on overall growth of seedlings. Irrigation frequency very significant affected number of leaves, leaf area, chlorophyll concentration, fresh and dry weights of shoots and roots, and dry matter. Growth of seedlings was the greatest with the highest irrigation frequency in the 25% CGF＋75% peatmoss mixture.