• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1100-1105
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• 2020

We investigated the driving force and the required charges for spontaneous reduction of metal nanoparticles (NPs) on a scotch tape induced by mechanochemical activation. The charges were analyzed based on anodic stripping voltammetry (ASV) of silver, which is proportional to the number of charge identities on the tape. The results supported that the driving force is mechanochemical radicals rather than ions in the light of the high charge density on the tape.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1293-1296
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• 2005

Nitrite plays an important role in the formation of carcinogenic nitrosamine. In order to effectively inhibit the formation of carcinogenic nitrosamine in food and biological systems, scavenging of residual nitrite is necessary. In screening test of nitrite-scavenging effect of seaweed, The methanol extract from Phaeophyta was more effective than those from Rhodophyta and Chlorophyta. Among the brown algae family, Laminariaceae, A. cribrosum (90.4$\%$) and E. cava (80.1$\%$), E. stolonifera (79.0$\%$) that belong to genus Ecklonia showed marked nitrite-scavenging effect at pH 1.2. Furthermore, these algae showed potent reducing power and radical scavenging activity. The nitrite-scavenging effect was correlated with level of reducing power.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.829-832
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• 2014

This study was conducted to investigate antioxidative and physiological activities of ethanol extracts concentration from Monascus-Fermented Chinese Yam (MFCY). The ethanol extracts from MFCY were measured to examine pigments, DPPH radical scavenging activity, reducing power and monacolin K contents. As a results show that Monascus sp. MK805, with Dioscorea japonica as the substrate can produce pigments (yellow, orange and red), DPPH radical scavenging activity, reducing power and monacolin K content at 29.6 (yellow), 15.1 (orange), 20.4 (red), 72.8%, 1.74(OD at 700nm), 480.6 mg/kg in EtOH extract, respectively. Therefore, fermented chinese yam (Dioscorea japonica) was estimated to be effective biological activity material.

• Applied Biological Chemistry
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• v.49 no.1
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• pp.60-64
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• 2006

The effect of far-infrared (FIR) irradiation and heat treatment on the antioxidant activity of extracts from citrus pomaces (CP) was evaluated. CP were placed in pyrex petri dishes (8.0 cm diameter) and irradiated at $100^{\circ}C$ and $150^{\circ}C$ for 5, 10, 15, 20, 40 or 60 min with a FIR heater or simple heater, respectively. After FIR irradiation or simple heat treatment, 70% ethanol extracts (EE) and water extracts (WE) of CP were prepared and radical scavenging activity (RSA) and reducing power of the extracts were determined. The antioxidant activities of the extracts increased as the time of heating or FIR-irradiation increased. When CP were FIR-irradiated at $100^{\circ}C$ far 30min, the values of RSA and reducing power of EE increased from 14.9% to 44.2%, and 0.290 to 0.886, respectively, compared to the untreated control. Simple heat treatment of CP at $100^{\circ}C$ for 60 min also increased RSA and reducing power of EE to 44.7%, and 1.045, respectively. FIR irradiation and heat treatment increased RSA and reducing power of WE from CP, too. These results indicated the antioxidant activity of CP extracts was significantly affected by FIR irradiation and heating temperature and duration on CP, and that the FIR irradiation and heat treatment process can be used as a tool for increasing the antioxidant activity of CP.

• Journal of Life Science
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• v.27 no.10
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• pp.1121-1129
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• 2017

The authors evaluated the scavenging activities of ABTS+ radical, hydroxy radical (OH), nitric oxide (NO), and ferric ion reducing antioxidant power (FRAP) from ethanol extracts of four edible alga, Enteromorpha linza, Porphyra tenera, Sargassum fusiforme, and Undaria pinnatifida. ABTS+ scavenging activity was analyzed according to the method of Brand-Williams et al. ABTS+ scavenging activity of S. fusiforme was evaluated to 61.8% at 8.0 mg/ml. ABTS+ scavenging activity of P. tenera was evaluated to 35.7% at 8.0 mg/ml. P. tenera and U. pinnatifida showed similar inhibitions of ABTS+ scavenging activity. According to the results of the OH assay in seaweed, inhibitory activities were in the order of S. fusiforme > P. tenera > U. pinnatifida > E. linza. The results showed scavenging activity for NO in the following order of potency: S. fusiforme > P. tenera > U. pinnatifida > E. linza with concentration values of 8.0 mg/ml. The NO scavenging activities of dough, which was instant noodles mixed with S. fusiforme and 3.5% salt, were 27.2% at 8.0 mg/ml. After boiling for 5 minutes, FRAP scavenging activity of instant noodles mixed with extracts of U. pinnatifida was evaluated to 31.5% at 8.0 mg/ml. S. fusiforme showed the highest inhibition activity of ABTS+, OH, NO, and FRAP among the four algae. Thus, these findings provide evidence that P. tenera, U. Pinnatifida, S. fusiforme, and E. linza extracts could become sources of natural antioxidants.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.31-34
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• 1990

Dibenzothiophene, crude oil and bunker C oil were used in the microbial desulfurization experiments using thermophilic and mesophilic strains of Desulfovibrio and Desulfotomaculum. Mesophilic Desulforvibrio desulfuricans M6 showed the degrees of sulfur removal about 42% and 17% from dibenzothiophene and crude oil, respectively. Thermophilic Desulfovibrio thermophilus showed the degrees of sulfur removal about 68% and 33% from dibenzothiophene and bunker C oil. The strains of Desulfotomaculum were much less efficient than strains of Desulfovibrio. The latter have more complex and stronger gydrogen metabolism. These results showed that desulfurization is closely related to the hydrogen metabolism of the sulfate reducing bacteria.

• The Korean Journal of Food And Nutrition
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• v.26 no.4
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• pp.693-699
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• 2013

This study examines the antioxidant activities and quality characteristics of fermented Codonopsis lanceolata tea according to the heating temperature and time. The browning, turbidity, reducing sugar, total polyphenol and total flavonoid contents all increased with increasing of heating temperature and time, but the pH decreased within the range of error. In particular, the total polyphenol contents of the heat treatment sample for 15 minutes at $200^{\circ}C$ are increased to about 4.5 times of 713.71mg/100ml as compared to the control group. From the results of the antioxidant activity test, as both the heating temperature and time increases, the antioxidant activity was increased for DPPH radical-scavenging activity, FRAP and reducing its power. In the case of the samples treated with heat for 15 minutes at $200^{\circ}C$ in the DPPH radical scavenging ability, it increased about twice more than the 45.17% control plot at 85.40%, and the reducing power and FRAP were increased to approximately two or three times more than the control group. According to the results for sensory test of fermented C. lanceolata tea according to heating temperature and time, the preference was confirmed as high by heat treatment due to increased temperature and time. Heat treatment process of C. lanceolata during the process is determined by the conditions required for high value-added products through the improvements of the taste and functionality of C. lanceolata.

• Korean Journal of Microbiology
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• v.25 no.2
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• pp.129-136
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• 1987

Nitrogen fixing activity associated with 40 varieties of rice was assayed at heading stage by an in situ acetylene reduction method. The in situ acetylene reduction activity and population of nitrogen fixing bacteria obtained on nitrogen-free malate medium for Azospirillum spp. enrichment showed positive correlation. Six Azospirillum spp. with high nitrogenase activity were isolated from the rice roots, from which five spp. were identified as A. lipoferum and one was A. brasilense. The physiological characteristics of the six Azospirillum isolates, that is, carbon source utilization, biotin requirement, antibiotic resistance, indole acetic acid excretion, plasmid profile and protein patterns were compared.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.680-685
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• 2015

Phytochemicals in Codonopsis lanceolata leaves were saponins, triterpenes, tannins, and flavonoids, not alkaloids. The levels of total polyphenols and flavonoids in Codonopsis lanceolata leaves were measured to evaluate the antioxidant activity. C. lanceolata leaves showed strong 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and potent reducing power. In addition, C. lanceolata leaf extracts inhibited production of nitric oxide (NO) in lipopolysaccharide (LPS)-activated RAW 264.7 cells. To examine active phytochemical for antioxidant activity, aglycone fraction of C. lanceolata leaves was analyzed by high performance liquid chromatography (HPLC). Luteolin was identified as a main component of aglycone fraction and showed potent antioxidant activity as determined by a DPPH radical scavenging assay and reducing power test. These results suggest that C. lanceolata leaves are a good source of antioxidants.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.477-477
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• 2012

미생물 연료전지는 정부가 추진하고 있는 신성장 동력사업의 녹색성장 정책에 부합하는 환경융합 신기술로써 일상생활에서 배출되는 하 폐수와 같은 유기물질을 전자공여체로 이용하여 전기에너지를 생산 할 수 있다는 점에서 각광받고 있다. 미생물 연료전지는 산화전극부의 미생물이 공급된 유기물질 을 분해하여 전자와 수소이온을 생성시키며 이들은 산소가 존재하는 환원전극부로 이동하여 물로 환원 됨 으로써 전기를 생성한다. 전기 화학적 성능의 향상을 위해 미생물 연료전지에서는 환원전극부에 서의 산소와 전자 및 수소이온의 빠른 환원반응을 유도해 주는 Pt촉매를 이용한다. 하지만 고가의 Pt 촉매는 미생물 연료전지의 현장적용을 위한 규모확장 시 초기비용이 증가되는 문제점을 초래한다. 이에 미생물 연료전지의 대체촉매 개발에 대한 많은 연구가 진행되고 있다. 화학적 연료전지에 관한 논문에서 연료전지의 촉매로 산소 환원반응에 높은 성능을 보이는 Co-N/C 형태의 Cobalt poly-pyrrole carbon가 제시 되었다. 이는 가격적인 측면에서는 Pt촉매의 약1/10배 정도 수준이지만 셀 성능은 Pt촉매의 95%정도의 효율을 보인다는 측면에서 향후 Pt 대체촉매로 가능성을 보여주는 새로운 비금속 촉매물질이다. Cobalt poly-pyrrole carbon이 Pt-catalsyt 셀 전압 성능 대비 약 66 %의 효율을 보였고 내부저항과 최대전력 밀도에 있어서도 촉매를 사용하지 않은 경우와 비금속 촉매의 성능보다 높음을 알 수 있었다. 본 연구는 Pt-catalsyt를 대체할 수 있는 저가의 산소환원 촉매물질 발굴을 위해 미생물연료전지에서 사용된 전례가 없으며 현재 화학전지의 촉매로 널리 쓰이고 있는 Cobalt poly-pyrrole carbon의 산소환원 촉매로써의 이용가능성을 평가하기 위해 실시되었으며, 평가한 결과는 첫 번째로 Cobalt poly-pyrrole carbon을 사용한 경우가 촉매를 사용하지 않은 경우와 비금속 촉매보다 환원 전극부에서의 원활한 환원작용이 진행되고 있음을 추측할 수 있으며 Pt-catalyst와 비교하였을 때 성능 대비 저렴한 가격으로 가격 경쟁력에 있어서 우월하다고 판단되었고 두 번째로 전기화학적 성능평가 및 EIS를 이용한 환원전극부의 내부저항 평가를 실시한 결과 셀 전압에 있어서 가장 많은 도말량 ($2.0mg/cm^2$)이 높은 성능을 보이고 있음을 알 수 있었다.