• Archives of Pharmacal Research
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• v.18 no.3
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• pp.164-168
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• 1995

In order to elucidate the cytotoxicity-structure correlation of ginseng-derived components, several prosapogenins and sapogenins were prepared from Korean red ginseng (Panax ginseng) saponins by acid hydrolysis or alkaline cleveage, and their chemical structures were identified by a combination of spectral and physical methods. Some of these degradation products showed the cytotoxic activities against various cancer cell lines, A549, SK-OV-3, SK-Mel-2, P388, L1210 and K562. The significant difference in cytotoxicity between stereoisomers was not found and the activity was inversely proportional to the number of sugars linked to sapogenins. Diol-type prosapogenins and sapogenins showed higher cytotoxicity than triol-type ones.

• Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.91-97
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• 2012

To isolate a nonylphenol (NP)-degrading bacterium, we isolated a single colony from the NP-degrading microbial consortium SW-3, which was previously isolated from an aqueous environment. Ten colonies that exhibited different cell morphologies were isolated and the strains were named SW-3-A, -B, -C, -D, -E, -F1, -F2, -G, -H, and -I. The ability of isolates to degrade NP was evaluated by kinetic analysis by the constant of NP degradation rate ($k_1$) and the half-life time of NP degradation ($t_{1/2}$). SW-3-F1, -F2, -G, and -I strains were superior at degrading NP. The $k_1$ and $t_{1/2}$ values of the four strains were sixfold higher and one-sixth lower, respectively, than those of the consortium strain. Additionally, SW-3-F1, -G, and -I strains were tested for their ability to degrade NP during coculture. NP degradation by coculture with a combination of all three strains was inferior to that of culture conducted with single isolates, suggesting that the three strains are antagonistic toward each other during NP degradation.

• Journal of the Korean Ceramic Society
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• v.49 no.1
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• pp.11-18
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• 2012

The characteristic features of solid oxide fuel cells are reviewed from the viewpoint of the thermodynamic variables to be developed inside cells/stacks particularly in terms of gradients of chemical potential, electrical potential and temperature and corresponding flows of air, fuel, electricity and heat. Examples of abrupt destruction of SOFC systems were collected from failures in controlling their steady flows, while continuous degradation was caused by materials behaviors under gradients of chemical potentials during a long operation. The local equilibrium approximation has been adopted in NEDO project on the durability/reliability of SOFC stacks/systems; this makes it possible to examine the thermodynamic stability/reactivity as well as mass transfer under the thermodynamic variable gradients. Major results of the NEDO project are described with a focus on degradation/deterioration of electrolyte and electrode materials.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.43-48
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• 1997

Three strains capable of degrading a chlorophenol were isolated by selective enrichment from soils contaminated with industrial wastewater. A Pseudomonas solanacearum TCP114 could use 2,4,6-trichlorophenol (TCP) as sole carbon and energy source, while two strains of Pseudomonas testosteroni CPW301 and Arthrobacter ureafaciens CPR706 could use 4-CP. All isolates also grew well on phenol. The degradation of one component by a pure strain was strongly affected by the presence of other compounds in the medium, CPW301 and CPR706 entirely lost the ability to degrade 4-CP and phenol in the presence of TCP. TCP114 also lost the ability to degrade phenol when 4-CP was added to the culture medium. These restrictions on the degradability could be overcome by employing defined mixed cultures (TCP114 and one strain of 4-CP degrading strains). All three components were successfully degraded by defined mixed cultures through their cooperative activities. It was also demonstrated that defined mixed cultures could be immobilized by using calcium alginate for the semi-continuous degradation of the three component mixture. Immobilization could not only accelerate the degradation rate, but also allowed the reuse of the cell mass several times without loss of the cells' degrading capabilities.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.19-22
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• 2005

In order to achieve high capacity and reliable link quality in user communication, this paper proposes a new concept of virtual cell: the Dual Virtual Cell(DVC), and DVC employment strategy based on DWCS. The proposed system uses two kinds of virtual cell. One is the AVC(Active Virtual Cell) which exists for actual traffic and the other is the CVC(Candidate Virtual Cell) which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. And also this system aims to reduce MT's overloads and acheive a prompt link change successfuly by introducing DVC structure which makes it possible for network to monitor real-time channel and to conrol communication links. The proposed system constructs DVC by using antenna selection method and improves frame error performance with employing Space-Time Trellis Code(STTC).

• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.67-67
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• 2003

No Abstract, See Full Text

• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.68-77
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• 2006

The heartwood of cengal (Neobalanocarpus heimii) is known to have a high degree of decay resistance by virtue of its high extractive content. After 30 years in ground contact an utility pole of this tropical hardwood was found to be degraded only in the surface layers by cavity-forming soft rot fungi. The present work was undertaken 1) to characterize the degradation of cengal heartwood from the aspect of ultrastructure and chemistry and 2) to investigate the correlation between soft rot decay and its extractive microdistribution in wood tissues. The chemical analysis of cengal heartwood revealed the presence of a high amount of extractives as well as lignin. The wood contained a relatively high amount of condensed lignin and the guaiacyl units. Microscopic observations revealed that vessels, fibers and parenchyma cells (both ray and axial parenchyma) all contained extractives in their lumina, but in variable amounts. The lumina of fibers and most axial parenchyma were completely or almost completely filled with the extractives. TEM micrographs showed that cell walls were also impregnated with extractives and that pit membranes connecting parenchyma cells were well coated and impregnated with extractives. However, fungal hyphae were present in the extractive masses localized in cell lumina, and indications were that the extractives did not completely inhibit fungal growth. The extent of cell wall degradation varied with tissue types. The fibers appeared to be more susceptible to decay than vessels and parenchyma. Middle lamella was the only cell wall region which remained intact in all cell types which were severely degraded. The microscopic observations suggested a close correlation between extractive microdistribution and the pattern and extent of cell wall degradation. In addition to the toxicity to fungi, the physical constraint of the extractive material present in cengal heartwood cells is likely to have a profound effect on the growth and path of invasion of colonizing fungi, thus conferring protection to wood by restricting fungal entry into cell walls. The presence of relatively high amount of condensed lignin is also likely to be a factor in the resistance of cengal heartwood to soft rot decay.

• Journal of the Korean Wood Science and Technology
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• v.21 no.1
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• pp.39-50
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• 1993

The purpose of this study was to describe the micromorphological changes in Korean red pine (Pinus densiflora S. et Z.) wood decayed by a major brown-rot fungus, Lentinus lepideus, using scanning electron microscope and transmission electron microscope. At the end of the 12-week exposure to the fungus in soil block procedure(ASTM 1971), test blocks sustained 5.02% weight loss. The formation of bore hole by hyphae and penetration of hyphae through bordered pit were not observed. Instead, fungal hyphae appeared to penetrate axially tracheid luminar from the the ray cells via cross field pits. Hyphae were mainly found in lignin rich cell corner regions of tracheids, and also extensive degradation of tracheid wall occurred in this region. Extensive degradation of $S_2$ layer occurred without noticeable alteration of the $S_3$ layer, but warty layer and compound middle lamella remained relatively intact. Localized erosion, the characteristic of white rot, was observed in some cell wall and wall components including lignin were found to be decomposed.

• Journal of Microbiology and Biotechnology
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• v.10 no.6
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• pp.759-763
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• 2000

Cell-free culture broth of Phanerochaete chrysosporium has been adopted to biologically degrade 2,4,5-trichlorophenol. Two different medium compositions of nitrogen-sufficient and nitrogen-limited were compared for their distribution of isozymes, activity of lignin peroxidase, and production of oxalate. The two different culture broths were tested for their ability to degrade 2,4,5-trichlorophenol, and the biodegradation efficiency was estimated in terms of the disappearance of 2,4,5-trichlorophenol. The degradation efficiency for the nitrogen-limited culture broth was higher than that of the nitrogen-sufficient culture broth, since the nitrogen-limited culture broth induced lignin peroxidases (LiPs) and manganese peroxidases (MnPs), and contained sufficient oxalate for producing necessary radicals. Finally, the possible mechanism of 2,4,5-CP degradation using the nitrogen-limited culture broth was proposed.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.3
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• pp.187-191
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• 2003

Proteolytic enzymes existing in plant cell cultured media are the major reason for the loss of secreted human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The addition of pepstatin, aprotinin and PMSF relatively decreased the proteolytic degradation of hGM-CSF in a conditioned medium, but sufficient prevention against the proteolytic activity could not be obtained with chemical protease inhibitors. Gelatin, as a competitive substrate for protease, showed a stabilizing effect in a conditioned medium. Compared to the initial hGM-CSF concentration in a conditioned medium. with 10 g/L of gelatin, 68% of the hGM-CSF remained after 5 days. In a cell culture experiment, 5 g/L of gelatin significantly stimulated the hGM-CSF production and accumulation in culture media, with no growth inhibition. compared to the controls (4.72 $\mu\textrm{g}$/L), the extracellular hGM-CSF level could be increased to 39.78 $\mu\textrm{g}$/L with the addition of 5 g/L of gelatin.