• Analytical Science and Technology
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• v.17 no.1
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• pp.37-44
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• 2004

An alcohol oxidase from Hansenula polymorpha was strongly induced when cells were grown with 0.5% methanol supplementation as the carbon source. The induced Hansenula polymorpha alcohol oxidase was purified to electrophoretic homogeneity by using DEAE-Sephacel and Mono Q column chromatographys. The enzyme oxidized mainly primary aliphatic alcohols and exhibited high substrate specificity towards ethanol and methanol. The activity of the enzyme optimally proceeded at pH 8.5 and $50^{\circ}C$. The midpoint of the temperature-stability curve for the enzyme was approximately $52^{\circ}C$ and the enzyme was not completely inactivated even at $65^{\circ}C$ temperature. The enzyme showed resistance toward detergents and highly stable over 7 weeks of storage condition. This Hansenula polymorpha alcohol oxidase may be useful for the enzymatic determination of alcohol and for the industrial production of alcohols and aldehydes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.3
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• pp.293-299
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• 2023

Acne vulgaris is often associated with acne-related bacteria such as Cutibacterium acnes. In this study, we investigated the antibacterial effects of the methanol extract of the algae Ecklonia cava and its solvent-soluble extract against C. acnes. Among five solvent fractions, the ethyl acetate (EtOAc) fraction exhibited the strongest antibacterial activity against C. acnes. Furthermore, the EtOAc-soluble extract exhibited the highest total phenolic contents among the five solvent fractions tested. The EtOAc subfraction 07 (Fr. 07) extract showed the highest antibacterial effect against C. acnes and isolated C. acnes along with minimum inhibitory concentration (MIC) ranging from 32 to 64 ㎍/mL. Additionally, MICs of antibiotics against antibiotic-resistant C. acnes strains were substantially reduced when antibiotics were combined with Fr. 07, suggesting that Fr. 07 restore the antibacterial activity of the antibiotics. The fractional inhibitory concentration indices clearly revealed an additive synergistic effect of Fr. 07 with antibiotics. The results of the present study suggest a potential role for E. cava in the control of infections related to acne vulgaris.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.130-137
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• 1992

The Graft copolymerization of acrylonitrile(AN) and styrene(ST) onto chloroprene rubber(CR) were carried out with benzoyl peroxide(BPO) as an initiator. The synthesized graft copolymer(ACS) was separated from polymeric mixture by the extraction with ethyl acetate and n-hexane, acetone and methanol, dimethylformamide(DMF) and methanol mixed solvent systems. The graft copolymer obtained, acrylonitrile-chloroprene-styrene(ACS) was identified by IR spectrophotometer. The effect of mole ratio of styrene to acrylonitrile, reaction time and temperature, initiator concentration, CR content and solvents on graft copolymerization were examined. It was observed that the grafting efficiency increased with [ST]/[AN] mole ratio and reaction time. The grafting efficiency increased with increasing initiator concentration and CR content. The maximum grafting efficiency was obtained when the mole ratio of [ST]/[AN] was 1.5 and reaction was made at 40hrs, and $70^{\circ}C$ using chloroform/toluene mixed solvent. The thermal properties, light resistance and flammability of ACS were compared with those of ABS and AES. It was found that flame retardancy of related polymers increased in the order ACS>ABS>AES. The thermal stability of ACS was greatly improved when compared with ABS or AES. Morphology of ACS was also investigated by using a transmisson electron microscope(TEM).

• Clean Technology
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• v.13 no.4
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• pp.293-299
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• 2007

Direct coating of catalyst layer on the $Nafion^{(R)}$ membrane has been optimized in the process of fabrication of membrane electrode assembly (MEA) to enhance the performance of direct methanol fuel cell (DMFC). In this method, the contact resistance at the interface of the catalyst layer and the membrane was found to be low. The effect of catalyst loading, thickness of membrane and the gas diffusion layer (GDL) with or without the presence of micro-porous layer (MPL) on the performance of the MEA was also investigated. The MEA fabricated by the above-mentioned method exhibited a performance of $147\;mW/cm^2$ and $100\;mW/cm^2$ at $80^{\circ}C$ and $60^{\circ}C$, respectively, with the catalysts loading of $4\;mg/cm^2$.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.266-287
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• 2004

The non infecting, plant associated bacteria have attracted increased attention for stimulating plant growth and as environmental friendly plant protecting agents. Pink-pigmented facultatively methylotrophic bacteria (PPFMs), classified as Methylobacterium spp., are persistent colonizers of plant leaf surfaces. As the leaves of most or all plants harbor PPFMs that utilize leaf methanol as their sole source of carbon and energy, which is a specific attribute of the genus Methylobacterium. Although they are not well known, these bacteria are co-evolved, interacting partners in plant metabolism. This claim is supported, for example, by the following observations: (1) PPFMs are seed-transmitted, (2) PPFMs are frequently found in putatively axenic cell cultures, (3) Low numbers of seed-borne PPFMs correlate with low germinability, (4) Plants with reduced numbers of PPFM show elevated shoot/root ratios, (5) Foliar application of PPFMs to soybean during pod fill enhances seed set and yield, (6) Liverwort tissue in culture requires PPFM-produced vitamin B12 for growth, (7) treated plants to suppress or decrease disease incidence of sheath blight caused by Rhizoctonia solani in rice, and (8) the PPFM inoculation induced number of stomata, chlorophyll concentration and malic acid content, they led to increased photosynthetic activity. Methylobacterium spp. are bacterial symbionts of plants, shown previously to participate in plant metabolism by consuming plant waste products and producing metabolites useful to the plant. There are reports that inform about the beneficial interactions between this group of bacteria and plants. Screening of such kind of bacteria having immense plant growth promoting activities like nitrogen fixation, phytohormone production, alleviating water stress to the plants can be successfully isolated and characterized and integration of such kind of organism in crop production will lead to increased productivity.

• Proceedings of the Plant Resources Society of Korea Conference
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• v.18 no.1
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• pp.41-51
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• 2005

We examined whether extracts from 14 local citrus spp. on Jeju Island (Korea) contained chemosensitizing activity that would increase the cytotoxic effect of vincristine(VCR) in drug-resistant cancer cells. We report that methanol extracts from fruits and flowers of some species had a chemosensitizing effect that reversed P-glycoprotein (Pgp)-mediated multidrug resistance (MDR). Using drug-sensitive AML-2/WT and drug-resistant AML-2/D100 in the absence of VCR in human acute myelogenous leukemia cells we found that fruit or flower extracts alone generally had low cytotoxicity $(IC_{50}>200\;{\mu}g/ml)$. In studies examining the effect of extracts on 120 ng/ml VCR cytotoxicity in drug-resistant AML-2/D100 cells, we found that immature fruit extracts had greater chemosensitizing activity than either extracts from mature fruit or flower. Of the 14 species examined, the immature fruit extract from Inchangkyool (Citrus ichangiensis) showed the hishest chemosensitizing index(CI) valus. Immature fruit extracts of Hongkyool(C. tachibana), Byungkyool(C. platymamma), Cheongkyool(C. nippokoreana) and Jinkyool (C. sunki) also strongly potentiated VCR cytotoxicity in AML-2/D100 cells. The chemosensitizing effect of peel extracts was 2-10-fold that of whole fruit extracts from Hongkyool (C. tachibana), Byungkyool (C. platymamma) and Inchangkyool (C. inchangiensis). The CI values for flower extracts were higher than those for mature fruit extracts, but lower than those for immature fruit extracts. These results indicate that immature citrus fruits contain compounds that do not exert their activity solely through cytotoxicity. In particular, Incahngkyool (C. inchangiensis), Byungkyool(C.platymamma), Cheongkyool(C. nippokoreana) and Hongkyool (C. tahibana) may be useful sources of chemosensitizing compounds.

• The Korean Journal of Community Living Science
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• v.22 no.4
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• pp.615-621
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• 2011

This study was conducted to evaluate of the protection efficiency in each part of developed pesticide-proof clothes by repeated washings. We investigated the effect of repeated laundering on mechanical properties of pesticide-proof clothes (not washed vs 5 times washed). We also examined pesticide infiltration rate into the pesticide-proof clothes by repeated laundering. The patches(TCL paper, surface area 50cm2)were attached to the inside of pesticide-proof clothes(head, chest, right upper-arm, right forearm, left thigh, left calf, back) which subjects had dressed in during pesticide spraying. The patches were detached from working clothes after work. For the extraction of pesticide in pesticide-proof clothes, sonication was applied for 30 min with methanol. The gas chromatography/mass spectrometry (GC/MS) was applied to identify the pesticide component. The results of this study are as follows: The force strength, water-vapour resistance and surface wetting resistance of pesticide-proof clothes decreased 5 times more in washed clothes. The concentration of pesticide was the highest in the head area of pesticide-proof clothes. In seven parts of TLC paper attached to the pesticide proof clothes, the concentration of pesticide was higher in the left thigh. The penetration part and concentration of pesticide increased as washing was repeated. Therefore the conclusion which can be drawn from this study is this: protection efficiency of pesticide-proof clothes decrease by repeated washings.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.16-19
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• 2006

The characteristic of negative differential resistance(NDR) is decreased current when the applied voltage is increased. The NDR is potentially very useful in molecular electronics device schemes. Here, we investigated the NDR characteristic of self-assembled 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate, which has been well known as a conducting molecule. Self-assembly monolayers(SAMs) were prepared on Au(111), which had been thermally deposited onto $pre-treatment(H_2SO_4:H_2O_2=3:1)$ Si. The Au substrate was exposed to a 1 mM/1 solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing the sample, it was exposed to a 0.1 ${\mu}M/l$ solution of 4.4'-di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene in dimethylformamide(DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. After the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_2Cl_2,$ and finally blown dry with N_2. Under these conditions, we measured electrical properties of self-assembly monolayers(SAMs) using ultra high vacuum scanning tunneling microscopy(UHV-STM). The applied voltages were from -2 V to +2 V with 298 K temperature. The vacuum condition was $6{\time}10^{-8}$ Torr. As a result, we found the NDR voltage of the 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate were $-1.61{\pm}0.26$ V(negative region) and $1.84{\pm}0.33$ V(positive region). respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.613-618
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• 2005

This study was carried out to examine the effects of gamma irradiation on the cytotoxicity and multidrug-resistance reversing activity of methanol extracts from Coix lachryma-jobi L. var. me-yuen Stapf seed. The seed was irradiated with doses of 1, 4, 8, 16, 32 and 64 Gy of the gamma radiation, and then extracted by methanol. The extracts were examined for cytotoxicity on the human cancer cell lines, MCF-7 (human breast adenocarcinoma pleural effusion), Calu-6 (human pulmonary carcinoma) and SNU-601 (human gastric carcinoma) cells, and investigated for multidrug-resistance reversing activity using drug sensitive AML-2/WT and multidrug-resistant AML-2/D100 cells. The growth inhibitory activity of irradiated seed extracts on human cancer cell lines was higher than that of the control. In the case of Calu-6 cell line, the effect of cytotoxicity was observed in the extracts of 4, 8 and 16 Gy. $IC_{50}$ value in the MCF-7 cell line was measured in the only 8 Gy extract. And in the SNU-601 cell line as Calu-6, the effect of cytotoxicity was observed in the extracts of 4, 8 and 16 Gy. But the extracts of gamma-irradiated seed over 32 Gy showed little growth inhibitory effect against human cancer cell lines. In this result, 8 Gy extract had significant growth inhibitory in all human cancer cell lines $(Calu-6:\;633\;{\mu}g/mL,\;MCF-7:\;653\;{\mu}g/mL\;and\;SNU-601:\;683\;{\mu}g/mL)$. The extracts of 4, 8 and 16 Gy strongly potentiated vincristine cytotoxicity in AML-2/D100 cells. The reversal fold (RF) of 4, 8 and 16 Gy extracts was 1.7, 1.8 and 1.6, respectively. But their cytotoxicities to both sensitive AML-2/WT and resistant AML-2/D100 cells were in the same order of magnitude. These results indicate that the above samples would contain some principles which have cytotoxicity and multidrug-resistance reversing activity. Irradiation technology can be applied to promote physiological activities of medicinal plant seeds.

• Natural Product Sciences
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• v.14 no.2
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• pp.113-117
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• 2008

Saururus chinensis is a commonly used folk herb for the treatment of edema and liver diseases in Korea. To study the biological activity of Saururus chinensis in bone metabolism, we evaluated the effect of its extracts on osteoclast differentiation in vitro using primary mouse bone marrow-derived macrophages. Methanol extract (ME) from dried roots of Saururus chinensis was partitioned into methylene chloride (MF), ethyl acetate (EF), n-butanol (BF) and water fractions (WF). Tartrate-resistance acid phosphatase (TRAP) activity assay and western blot analysis were performed to determine the effect on osteoclast differentiation and mitogen-activated protein (MAP) kinases activation. ME, MF and EF dramatically inhibited receptor activator of ${NF-kB}$ ligand (RANKL)-induced formation of multinucleated osteoclasts and activation of MAP kinases. This study firstly demonstrated that ME, MF and EF of Saururus chinensis have the potential to inhibit the osteoclast differentiation, which results from the inhibition of MAP kinases activations in part.