• Applied Biological Chemistry
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• 제14권2호
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• pp.131-135
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• 1971

1. Aspergillus oryzae의 균체에는 L-tyrosine-${\alpha}$-ketoglutaric acid transaminase와 p-hydroxyphenlypyruvic acid oxidase가 존재해 있다. 2. L-Tyrosine 산화효소는 액침배양한 Aspergillus oryzae의 acetone powder, cell free extract 및 배양액에도 존재하며 L-tyrosine은 ${\alpha}$-ketoglutaric acid의 첨가로 더욱 빨리 전환되었다. 3. ${\alpha}$-Ketoglutaric acid와 pyridoxal phosphate는 transamination의 amino기의 수용체로 생각되었다. 4. 이들 효소계는 L-tyrosine와 p-hydroxyphenlypyruvic acid를 homogentisic acid로 산화시켰다. 5. Ascorbic acid는 p-hydroxyphenlypyruvic가 homogentisic acid로 산화되는데 특별한 역할을 하는 것 같다. 6. L-Tyrosine-${\alpha}$-ketoglutaric acid transaminase와 p-hydroxyphenlypyruvic acid oxidase의 최적 pH는 각 각 pH $6.0{\sim}6.5$와 pH 7.5이었다.

• Journal of Microbiology and Biotechnology
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• 제17권3호
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• pp.428-437
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• 2007

The potential for humic substances to serve as terminal electron acceptors in microbial respiration and the effects of humic substances on microbial azoreduction were investigated. The dissimilatory azoreducing microorganism Shewanella decolorationis S12 was able to conserve energy to support growth from electron transport to humics coupled to the oxidation of various organic substances or $H_2$. Batch experiments suggested that when the concentration of anthraquinone-2-sulfonate (AQS), a humics analog, was lower than 3 mmol/l, azoreduction of strain S12 was accelerated under anaerobic condition. However, there was obvious inhibition to azoreduction when the concentration of the AQS was higher than 5 mmol/l. Another humics analog, anthraquinone-2-sulfonate (AQDS), could still prominently accelerate azoreduction, even when the concentration was up to 12 mmol/l, but the rate of acceleration gradually decreased with the increasing concentration of the AQDS. Toxic experiments revealed that AQS can inhibit growth of strain S12 if the concentration past a critical one, but AQDS had no effect on the metabolism and growth of strain S12 although the concentration was up to 20 mmol/l. These results demonstrated that a low concentration of humic substances not only could serve as the terminal electron acceptors for conserving energy for growth, but also act as redox mediator shuttling electrons for the anaerobic azoreduction by S. decolorationis S12. However, a high concentration of humic substances could inhibit the bacterial azoreduction, resulting on the one hand from the toxic effect on cell metabolism and growth, and on the other hand from competion with azo dyes for electrons as electron acceptor.

• 상하수도학회지
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• 제24권3호
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• pp.341-349
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• 2010

It is well known that manganese is hard to oxidize under neutral pH condition in the atmosphere while iron can be easily oxidized to insoluble iron oxide. The purpose of this study is to identify removal mechanism of manganese in the D water treatment plant where is treating bank filtered water in aeration and rapid sand filtration. Average concentration of iron and manganese in bank filtered water were 5.9 mg/L and 3.6 mg/L in 2008, respectively. However, their concentration in rapid sand filtrate were only 0.11 mg/L and 0.03 mg/L, respectively. Most of the sand was coated with black colored manganese oxide except surface layer. According to EDX analysis of sand which was collected in different depth of sand filter, the content of i ron in the upper part sand was relatively higher than that in the lower part. while manganese content increased with a depth. The presence of iron and manganese oxidizing bacteria have been identified in sand of rapid sand filtration. It is supposed that these bacteria contributed some to remove iron and manganese in rapid sand filter. In conclusion, manganese has been simultaneously removed by physicochemical reaction and biological reaction. However, it is considered that the former reaction is dominant than the latter. That is, Mn(II) ion is rapidly adsorbed on ${\gamma}$-FeOOH which is intermediate iron oxidant and then adsorbed Mn(II) ion is oxidized to insoluble manganese oxide. In addition, manganese oxidation is accelerated by autocatalytic reaction of manganese oxide. The iron and manganese oxides deposited on the surface of the sand and then are aged with coating sand surface.

• Progress in Superconductivity
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• 제7권1호
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• pp.69-76
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• 2005

Complex single buffer composed of yttrium and samarium oxide was deposited on the metallic substrates by MOCVD (metal organic chemical vapor deposition) method using single liquid source. Two different types of the substrates with in-plane textures of about $8{\sim}10$ degree of Ni and $3at.\%W-Ni$ alloy were used. Y(tmhd: 2,2,6,6-tetramethyl-3,5-heptane dionate)$_3$:Sm(tmhd)$_3$ of liquid source was adjusted to 0.4:0.6 to minimize the lattice mismatch between the complex single buffer and the YBCO. The epitaxial growth of $(Y_{x}Sm_{1-x})_{2}O_3$ was achieved at the temperature higher than $500^{\circ}C$ in $O_2$ atmosphere. However, it was found that the formation of NiO accelerated with increasing deposition temperature. By supplying $H_{2}O$ vapor, this oxidation of the substrate could be suppressed throughout the deposition temperatures. We could get the epitaxial growth on pure Ni substrate without the formation of NiO. The competitive (222) and (400) growths were observed at the deposition temperatures of $650\~750^{\circ}C$, but the (400) growth became dominant above $800^{\circ}C$. The $(Y_{x}Sm_{1-x})_{2}O_3$-buffered metallic substrates can be used as the buffer for YBCO coated conductor.

• Nutritional Sciences
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• 제7권4호
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• pp.189-195
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• 2004

1bis study investigated the antioxidative effect in kidney of senescence-accelerated prone SAMP8 mice with calorie restriction. 4-weeks-old SAMP8 female mice were divided into 4 groups according to the experimental feeding period: for 4, 8, 12 month, and at natural death. Each group was subdivided into 2 groups, with thirteen mice each one, as ad libitum group and as dietary restriction group (60% of ad libitum feeding amount). After feeding for a given period, the mice were sacrificed to get the following results: among the experimental groups, there wereno significant differences in xanthine oxidase (XOD) activity in their kidney tissues. The contents of cytochrome $P_{450}$ decreased in ad libitum group and dietary restriction group by age. The activity of NADPH-cytochrome $P_{450}$ reductase showed a trend similar to cytochrome $P_{450}$. Superoxide radical content increased with age. At the 4th, 8th and 12 months of the experimental period, the activity in the dietary restriction group was less than that of ad libitum group by as much as 17% 14% and 14% respectively. For hydrogen peroxide, the contents were increased in the ad libitum group with age, while no correlation between content and age was observed in the dietary restriction group. In the 8th and 12th months of the experimental period, the were in the dietary restriction group less than that of ad libitum group counterpart as much as 17% and 20o/c, respectively. For the cellular membrane stability of the kidney, no significant correlation with age was observed in either the dietary restriction group or the ad libitum group. However at the 12th month of the experiment, however, the stability in the dietary restriction group was 11 % higher than that in the ad libitum group. In conclusion, with these results obtained from the SAMP8 mouse model, we demonstrate that dietary restriction has the effects of anti-oxidation and anti-senescence in the kidney.

• 대한기계학회논문집A
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• 제27권8호
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• pp.1398-1408
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• 2003

Tensile and LCF(low cycle fatigue) tests were carried out in air at wide temperature range 20$^{\circ}C$-750$^{\circ}C$ and strain rates of 1${\times}$10$\^$-4//s-1${\times}$10$\^$-2/ to ascertain the influence of strain rate on tensile and LCF properties of prior cold worked 316L stainless steel, especially focused on the DSA(dynamic strain aging) regime. Dynamic strain aging induced the change of tensile properties such as strength and ductility in the temperature region 250$^{\circ}C$-600$^{\circ}C$ and this temperature region well coincided with the negative strain rate sensitivity regime. Cyclic stress response at all test conditions was characterized by the initial hardening during a few cycles, followed by gradual softening until final failure. Temperature and strain rate dependence on cyclic softening behavior appears to result from the change of the cyclic plastic deformation mechanism and DSA effect. The DSA regimes between tensile and LCF loading conditions in terms of the negative strain rate sensitivity were well consistent with each other. The drastic reduction in fatigue resistance at elevated temperature was observed, and it was attributed to the effects of oxidation, creep and dynamic strain aging or interactions among them. Especially, in the DSA regime, dynamic strain aging accelerated the reduction of fatigue resistance by enhancing crack initiation and propagation.

• 한국식품영양과학회지
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• 제35권2호
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• pp.182-186
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• 2006

본 연구에서는 연잎 추출분획물의 항산화 활성을 비교, 검토하고자 하였다. $70\%$ ethanol로 추출한 추출수율은 $8.16\%$였으며 이를 hexane, chloroform, ethyl acetate, butanol, water로 순차 분획한 수율은 butanol층이 $36.12\%$로 가장 높은 수율을 보였으나 대체적으로 극성이 높을수록 높은 분획수율을 나타내었다. 분회물간 총 페놀함량 측정결과 ethyl acetate 분획물의 총 페놀함량이 가장 높게 나왔으며 전자공여능 측정결과 또한 ethyl acetate 분획물에서 가장 우수한 결과를 나타내었다. Ethyl acetate 분획물의 전자공여능은 BHA, BHT와 비교한 결과 BHA와 유사한 결과를 나타내었으며 BHT보다 우수한 값을 나타내었다. 항산화 활성이 높게 나타난 ethyl acetate 분획물을 취하여 TBA가에 의한 지질과산화를 측정한 결과 BHA가 가장 우수한 활성을 보여 주었으며 ethyl acetate 분획물은 BHT보다도 활성이 떨어졌으나 이는 ethyl acetate 분획물이 단일물질로 분리정제가 이루어지지 않은 것으로 malonaldehyde 이외 다른 성분이 BHA와 반응하여 발색한 것으로 추측되어 졌다. AV와 POV 측정 결과 BHA가 가장 우수한 활성을 보여주었으나 ethyl acetate 분획물과 유의적인 차이는 없었으며 BHT에 비해서는 우수한 활성을 나타내었다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.231-232
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• 1998

The purpose of this study was to examine whether the precipitation of calcium phosphate on titanium surface was affected by surface modification. To improve the bone conductivity, of titanium, samples were devided into 4 groups. Group 1 was immersed in 5M-NaOH solution at $60^{\circ}C$ for 24 hours. Group 2 was immersed in 5M-NaOH solution at $60^{\circ}C $ for 24 hours and heat-treated at $600^{\circ}C$ for 1 hour. Group 3 was anodized in Hanks' solution at 1V, $25^{\circ}C$ for 1 hour. Group 4 was anodized in Hanks' solution at 5V, $80^{\circ}C$ for 5 minutes. And then, all specimens were immersed in the MEM Eagle's medium whose composition was similar to that of extracellular fluid for 30 days. The precipitation of the calcium phosphate on implant surface was increased by the immersion in the NaOH solution, and more highly accelerated by heat treatment at $600^{\circ}C$. The precipitation of the calcium phosphate on titanium implant was increased with the treatment of the anodic oxidation in Hanks' solution at 5V, $80^{\circ}C$.

• Journal of Forest and Environmental Science
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• 제13권1호
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• pp.143-152
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• 1997

백색부후균인 Fomes pini (Thore) Lloyd에 의해 처리된 chip을 anthraquinone(AQ)을 첨가하여 화학 펄프화를 실시하여 얻은 결과를 미처리재의 것과 비교하였다. 균처리함에 의해 카파값 20에서의 H factor는 소다와 크라프트 증해에서 각각 17%와 15%가 감소되었다. 이러한 결과는 목재를 백색부후균으로 처리함으로 인해 탈리그닌이 용이해졌음을 나타내는 것이다. 비페놀성 ${\beta}$-O-4 화합물인 veratrylglycerol-${\beta}$-guaiacyl ether(I)와 페놀성 ${\beta}$-O-4 화합물인 syringylglycerol-${\beta}$-syringyl ether(III)에 백색부후균을 작용시키면 반응생성물로서 각각 ${\alpha}$-guaiacoxy-${\beta}$-hydroxypropioveratrone(II)과 ${\alpha}$-syringyloxy-${\beta}$-hydroxypropiosyringone(IV)이 생성됨이 밝혀졌다. 따라서 목재에 균처리를 함으로서 카르보닐기가 리그닌의 측쇄 ${\alpha}$ 위에 도입되어 그로 인해 탈리그닌이 용이하게 된 것으로 여겨진다.

• Journal of Ginseng Research
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• 제42권3호
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• pp.320-326
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• 2018

Background: Explosive puffing can induce changes in the chemical, nutritional, and sensory quality of red ginseng. The antioxidant properties of ethanolic extracts of red ginseng and puffed red ginseng were determined in bulk oil and oil-in-water (O/W) emulsions. Methods: Bulk oils were heated at $60^{\circ}C$ and $100^{\circ}C$ and O/W emulsions were treated under riboflavin photosensitization. In vitro antioxidant assays, including 2,2-diphenyl-1-picrylhudrazyl, 2,2'-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid, ferric reducing antioxidant power, total phenolic content, and total flavonoid content, were also performed. Results: The total ginsenoside contents of ethanolic extract from red ginseng and puffed red ginseng were 42.33 mg/g and 49.22 mg/g, respectively. All results from above in vitro antioxidant assays revealed that extracts of puffed red ginseng had significantly higher antioxidant capacities than those of red ginseng (p < 0.05). Generally, extracts of puffed red and red ginseng had high antioxidant properties in riboflavin photosensitized O/W emulsions. However, in bulk oil systems, extracts of puffed red and red ginseng inhibited or accelerated rates of lipid oxidation, depending on treatment temperature and the type of assay used. Conclusion: Although ethanolic extracts of puffed red ginseng showed stronger antioxidant capacities than those of red ginseng when in vitro assays were used, more pro-oxidant properties were observed in bulk oils and O/W emulsions.