• 한국균학회지
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• 제8권1호
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• pp.59-62
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• 1980

Investigation on modification of aflatoxin structures by Pseudomonads was attempted as a biological detoxifiying process of mycotoxins. Firstly, when any variation of aflatoxin yield of Aspergillus parasiticus in a mixed culture with Pseudomonas aeruginosa was examined, there was no noticible effect by growth of Pseudomonads on aflatoxin yield of Asperillus sp. Secondly, when capacity of Pseudomonas aeruginosa utilizing aflatoxin as a carbon source for its growth was tested, there was some indication that aflatoxin might be used for growth of Pseudomonads. It was also noticed that the residual aflatoxin showed different migrating pattern compared with that of the intact aflatoxin by thin layer chromatography. Thirdly, the cell-free extract prepared from Pseudomonas aeruginosa grown in a glucose minimal medium supplemented with aflatoxin and the intact aflatoxins were incubated in the presence of $Mg^{++}$. After a certain length of incubation period, the reaction mixtures were applied on TLC plates. As a result, aflatoxins in the reaction mixture migrated differently as the control did. Such results may indicate that some changes of aflatoxin properties were induced by Pseudomonads.

• Advances in Traditional Medicine
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• 제9권3호
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• pp.225-231
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• 2009

The present study deals with the amelioration by Lagerstroemia speciosa Linn. leaf extract against hepatotoxicity induced by carbon tetrachloride ($CCl_4$), which was evaluated in terms of serum marker enzymes like serum glutamate pyruvate transaminase, serum glutamate oxaloacetate transaminase, alkaline phosphatase, serum total bilirubin, total protein levels along with concomitant hepatic and antioxidants like superoxide dismutase, catalase, glutathione, glutathione peroxidase and lipid peroxidation enzymes were monitored. These biochemical parameters altered by the single dose level of $CCl_4$ (0.75 ml/kg body weight, i.p). Pre treatment with L. speciosa prior to the administration of $CCl_4$, at the doses of 50 and 250 mg/kg. body weight/day, p.o. for 7 days, significantly restored all the serum and liver tissue parameters near to the normal levels, respectively. Silymarin was used as a reference standard, prior to the administration of $CCl_4$ to rats. These findings indicate the protective potential of L. speciosa against hepato toxicity which possibly involve mechanism related to its ability of selective inhibitors of (reactive oxygen species like antioxidants brought about significant inhibition of TBARS suggesting possible involvement of $O_2{\cdot}-$, $HO_2{\cdot}$, and ${\cdot}OH$. In conclusion, the amelioration may be attributed to the synergistic effects of its constituents rather than to any single factor as the leaves are rich in tannins, sterols, flavonoids, saponins etc.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.547-554
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• 2012

Chromium is generated from several industrial processes. It occurs in different oxidation states, but Cr(III) and Cr(VI) are the most common ones. Cr(VI) is a toxic, soluble environmental contaminant. Some bacteria are able to reduce hexavalent chromium to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of considerable interest. An indigenous chromium-reducing bacterial strain, Rb-2, isolated from a tannery water sample, was identified as Ochrobactrum intermedium, on the basis of 16S rRNA gene sequencing. The influence of factors like temperature of incubation, initial concentration of Cr, mobility of bacteria, and different carbon sources were studied to test the ability of the bacterium to reduce Cr(VI) under variable environmental conditions. The ability of the bacterial strain to reduce hexavalent chromium in artificial and industrial sewage water was evaluated. It was observed that the mechanism of resistance to metal was not due to the change in the permeability barrier of the cell membrane, and the enzyme activity was found to be inductive. Intracellular reduction of Cr(VI) was proven by reductase assay using cell-free extract. Scanning electron microscopy revealed chromium precipitates on bacterial cell surfaces, and transmission electron microscopy showed the outer as well as inner distribution of Cr(VI). This bacterial strain can be useful for Cr(VI) detoxification under a wide range of environmental conditions.

• Ocean Science Journal
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• 제42권3호
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• pp.165-170
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• 2007

The structure of the nematodes communities has been studied in the sediments on two sites located outside and under the layer of Ahnfeltia tobuchiensis (Kanno and Matsubara 1932; Makijenko 1970). Bottom sediments at the stations were represented by sands with a different degree of silting. Specific structure of nematodes at the stations was significantly different under the similar environmental conditions (water depth, dissolved oxygen saturation, salinity, temperature of the bottom layer and organic carbon content inside of the sediment). Nematodes dominated (75.7 %) in meiobenthos community under the layer of A. tobuchiensis where concentration of silt particles was 12 %. Representatives of the family Comesomatidae were dominant. Low index of species diversity and high Simpson domination index were detected in this community. Under a layer of A. tobuchiensis with the thickness of 30 cm concentration of the silt particles was 5.39 %; nematodes density was low and made 32.1 % of the general density of meiobenthos. Species of the families Xyalidae and Monoposthiidae were dominant. Outside of A. tobuchiensis, field percentage of silt particles was minimal (3.1 %) and representatives of families Cyatholaimidae and Axonolaimidae dominated. The specific structure of nematodes in this type of the ground is characterized by high index of species diversity and low level of domination.

• Natural Product Sciences
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• 제18권2호
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• pp.76-82
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• 2012

Stamens of Mesua ferrea L. are a well-known herbal drug used in Indian System of Traditional Medicine to treat various diseases. The claimed activity of this plant part is necessitated to investigate antioxidant and hepatoprotective activity. Authenticated plant sample was extracted with hexane, ethanol (EtOH) and water (aq.) using ASE 100 accelerated solvent extractor. Antioxidant activity was evaluated by means of different in vitro assays. Hepatoprotective effect was investigated on carbon tetrachloride induced oxidative stress in liver slice culture model. Cytotoxic marker lactate dehydrogenase (LDH) released in culture medium and the activity of lipid peroxidation along with antioxidant enzymes (AOEs) namely superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) were estimated. Hexane and EtOH extracts were significantly inhibited DPPH, NO, SOD and $ABTS^+$ radical in dose dependent manner. The trade of phenol content was: aq. extract < hexane extract < EtOH extract. A significant correlation was shown by total phenol content and free radical scavenging activity of extracts. The culture system treated with hexane extract, EtOH extract or ascorbic acid exhibited significant depletion in LDH, lipid peroxidation, antioxidative enzymes SOD, CAT and GR. Hexane extract and EtOH extracts of stamen of M. ferrea protected liver slice culture cells by alleviating oxidative stress induced damage to liver cells.

• Tribology and Lubricants
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• 제5권1호
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• pp.44-50
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• 1989

High strength steel is similar to carbon steel in its composition. This material is developed originally for special uses such as aerospace and automobile due to its high strength and shock-free property in spite of lightness. But the chemical attraction of high strength steel is serious, which includes comminution of formation, metalization and strengthening. Machining results in built-up edge between this material and the tool. Especially the work hardening behavior results in tool life shortening, which was caused by temperature generation during machining. In this study, cooling system was made in which liquid nitrogen is supplied to circulate in order to make up for these weaknesses. Machining of high strength steels, which is recognized as difficult to machine materials, was conducted after tool is cooled at -195$\circ$C. Experimental results showed that the tool was cooled down rapidly below -195$\circ$C in about 200 seconds. The tool temperature of machining with cooling system was lowered by 60~95$\circ$C than that of machining in room temperature. The hardness of the surface of chip is decreased by machining with cooling system. And the machining using the cooling system made it possible to increase shear angle, to retain smooth surface on chip without built-up-edge and to get a better roughness.

• 동의생리병리학회지
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• 제22권1호
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• pp.82-88
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• 2008

We evaluated the potential protective activity of the traditional Korean medicinal herb, Corni fructus (CF), in an experimental model of hepatotoxicity induced by carbontetrachloride $(CCl_4)$. The CF exhibited a hepatoprotective activity against Chang cell. And The expression of cytochrome P450 2E1 (CYP2E1), measured by RT-PCR and western blot, was significantly decreased in the CF treated Chang cell. But $CCl_4$ and CF has no significant effect on 1A1 and 3A1 isoform of cytochrome P450. Based on these findings, it is suggested that hepatoprotective effects of CF possibly related to antioxidative effects and downregulation of CYP2E1 expression.

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1077-1083
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• 2005

Electro-Active Paper (EAPap) is one of attractive electro-active polymer (EAP) materials for artificial muscles due to its many advantages such as light weight, biologically degradable, low cost, large displacement output, low actuation voltage and low power consumption. However, drawbacks of EAPap actuators include low force output and humidity dependence. To enhance the performance of EAPap, conductive polymer (PPy) and SWNT/conductive polymer (PANI) are coated on EAPap PPy as conductive polymer is coated on cellulose EAPap by means of electrochemical deposition. Two different dopants are used in PPy through conducting polymer processing. SWNTS are mixed with PANI in emeraldine base along with different dopants. The compound materials are coated on cellulose EAPap using spin coating system. The performance of PPy/EAPap and SWNT/PANI/EAPap are evaluated in terms of bending displacement, blocked force, and the effects of dopants, humidity, coaling time, voltage and frequency are investigated. Comparing with EAPap actuators, SWNT/PANI/EAPap actuators show $200\%$ improvement of bending displacement and $300\%$ increment of blocked force.

• 한국버섯학회지
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• 제11권4호
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• pp.181-186
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• 2013

${\gamma}$-Aminobutyric acid(GABA) is a four carbon non-protein amino acid that has several well-known physiological functions, such as a postsynaptic inhibitory neurotransmitter in the brain and induction of hypotensive and tranquilizer effects. A lactic acid bacterium was isolated from button mushroom bed, which is showing high GABA productivity by TLC or HPLC analysis. The strain was identified as Lactobacillus hilgardii by analysis of 16S rDNA gene sequence. When the maximum production of GABA by L. hilgardii was investigated with various concentration of monosodium glutamate, the yield of GABA reached to be 53.65 mM at 1% mono sodium glutamate (MSG) in flask cultivation. A Glutamate decarboxylase (GAD) enzyme, which was known to convert MSG to GABA, was purified from a cell-free extract of L. hilgardii and the molecular weights of purified GAD was estimated to 60,000 by SDS-PAGE. The optimum pH and temperature of GAD were at pH4.6 and at $37^{\circ}C$, respectively. The GAD activity was increased by the addition of sulfate ions such as ammonium sulfate, sodium sulfate and magnesium sulfate, indicating that the increase of hydrophobic interaction causes the increase of GAD activity.

• 미생물학회지
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• 제22권3호
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• pp.135-142
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• 1984

The effect of biotin on the growth and sporulation of Bacillus subtilis SNU816 was investigated. When B. subtilis SNU816 was cultured on glucose as a sole carbon source, the growth was retarded markedly and usually ceased at early log phawe. But by addition of biotin to this medium, normal, rapid growth was restored. The growth rate was increased proportionally according to the concentration of exogenous biotin until it reached to 0.05㎍/ml, at which about three fold rapid growth was achieved. Also biotin was required for optimum sporulation for it facilitated the complete utilization of both glucose(Glc) and glutamic acid(Glu). Without biotin in Glc+Glu medium, about 40% of glutamic acid was remained unutilized. The dipicolinic acid content of cells cultured in Glc+Glu medium without biotin was markedly small and sporulation was suppressed before free spore release. Since biotin could be partiallyreplaced by one of TCA cycle intermediates such as oxalacetic acid, citric acid, or glutamic acid in enhancing growth in Glc medium, it was postulated that this strain might have a defect in converting pyruvate to oxalacetate which process is known to be mediated by pyruvate carboxylase that requires biotin as a cofactor.