• 자원환경지질
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• 제32권1호
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• pp.101-111
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• 1999

Sedimentary organic matter, exposed to continental surficial environment, reacts with oxygen supplied from the atmosphee and forms carbon-containing oxidation products. Knowledge of the rate and mechanisms of sedimentary organic matter weathering is important because it is one of the major controls on atmospheric oxygen level through geologic time. Under the abiological conditions, the oxidation rate of coal organic matter by molecular oxygen is enhanced by the increase of oxygen concentration and temperature. At ambient temperature and pressure, aqueous coal oxidation results in the formation of dissolved $CO_2$ dissolved organic carbon and solid oxidation products which are all quantitatively significant reaction products. The effects of pH, ultraviolet light, and microbial activity on the weathering of sedimentary organic matter are poorly contrained. Based on the results of geochmical and environmental studies, it is believed that the photochemical reaction should play an important role in the decomposition and oxidation of sedimentary organic matter removed from the weathering profile. At higher pH conditions, the production rate of DOC can be accelerated due to base catalysis. These high molecular weight oranic matter can react with man-made pollutants such as heavy metal ions via adsorption/desorption or ion exchange reactions. The effect of microbial activity on the oxidative weathering of sedimentary organic matter is poorly understood and remains to be studied.

• 한국축산식품학회지
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• 제34권3호
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• pp.273-279
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• 2014

The objective of this study was to investigate the effects of the packaging method on the lipid and protein oxidation, and color in aged top round from Hanwoo (Korean native cattle) for 14 d at $4^{\circ}C$. Catalase activity was the highest (p<0.05) in vacuum packaging (VP) treatment during storage, and was higher (p<0.05) in 50% Ox-MAP and 50% Ox-MAP+vacuum skin packaging (VSP) treatments than in other treatments at d 14. Superoxide dismutase activity was higher (p<0.05) in VP, 50% Ox-MAP, and 50% Ox-MAP+VSP treatments than in other treatments at d 14. During storage, total antioxidant activity was the highest (p<0.05) in VP treatment and was higher (p<0.05) in 50% Ox-MAP+VSP treatment than in 80% Ox-MAP treatment. TBARS value was the lowest (p<0.05) in VP treatment during storage and was lower (p<0.05) in 50% Ox-MAP and Ox-MAP+VSP treatments than in 80% Ox-MAP and Ox-MAP treatments, respectively. Carbonyl content was the lowest (p<0.05) in VP treatment from 10 d. From 7 d, the $a^*$ value was the highest (p<0.05) in VP treatment and was higher (p<0.05) in 50% Ox-MAP and 50% Ox-MAP+VSP treatments than in other treatments. The $b^*$ value was the highest (p<0.05) in VP treatment from 3 d, and was higher (p<0.05) in 80% Ox-MAP+VSP, 50% Ox-MAP, and 50% Ox-MAP+ VSP treatments than in 80% Ox-MAP treatment at d 14. Therefore, VP improved the oxidation and red color stabilities in stored-aged top round compared with Ox-MAP. In addition, 50% Ox-MAP improved the lipid oxidation and red color stabilities compared with 80% Ox-MAP, and its inhibitory effect on lipid oxidation was enhanced by combination with VSP.

• 한국식품영양과학회지
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• 제20권2호
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• pp.148-155
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• 1991

Lipid oxidation and browning during fermentation of domestic Meju and Doenjang were examined in order to elucidate the antioxidative effects of browning products and phenol compounds from Meju and Doenjang. Peroxide values of lipids from Meju were detectable and slightly increased until 3 weeks of fermentation, but started to be decreased after 3 weeks of fermentation and notdetectable after 6 weeks. Peroxides were not detected in Doenjang during the whole fermentation, but started to be decreased after 3 weeks of period of 22 weeks fermentation. Carbonyl value were increased during the whole period of Meju fermentation, but started to be decreased at the early stage of Doenjang fermentation. Hydrophilic fraction of browning products from Meju was much higher than lipophilic fraction and the former fraction was dramatically increased at the early stage of the fermentation. But the both fractions maintained high values during Doenjang fermentation. Hydrophilic browning products and phenol and phenol compound in Meju showed strong antioxidative against linoleic acid.

• Nuclear Engineering and Technology
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• 제32권5호
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• pp.514-520
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• 2000

The mechanism of corrosion behavior has to be understood clearly to select an optimum material for handling molten salts to be used in the oxide reduction process of PWR spent fuel. In this study, the oxidation states of corrosion products on the surface of Inconel 600 and 800H as well as their chemical compositions and structural informations were determined by using XPS, ICP-AES, AAS, EPMA and XRD after the corrosion experiment with lithium molten salts at 75$0^{\circ}C$ for 25 hours. Nickel and oxygen were detected from the corrosion products on the surface of Inconel plates and chromium was found to be dissolved out into lithium molten salts leaving cracks on the surface. The corrosion products were identified as metal oxides such as Fe$_2$O$_3$, Cr$_2$O$_3$, NiO, NiFe$_2$O$_4$and MnO by using XPS and XRD.

• 한국축산식품학회지
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• 제32권4호
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• pp.491-496
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• 2012

본 연구는 비육기간이 홀스타인육 패티의 산화안정성에 미치는 영향에 관해 구명하고자 실시하였다. 18, 21 및 24개월령 홀스타인 거세우 등심(M. longissimus dorsi) 패티를 $4^{\circ}C$에서 12일간 저장하면서 지방산화, 단백질산화, 육색소산화 및 육색을 분석하였다. 일반성분 중 지방 함량은 24개월령이 18개월령보다 높았다(p<0.05). 저장 중 TBARS 함량과 metmyoglobin 농도는 8일째부터 24개월령이 높았다(p<0.05). Conjugated dienes 함량은 저장 4일째부터 21과 24개월령이 높았으며(p<0.05), carbonyl 함량은 12일째에 24개월령이 높았다(p<0.05). 표면육색 중 명도($L^*$)는 저장 4일째부터 21과 24개월령이 낮은 경향을 보였다. 적색도($a^*$)는 24개월령이 저장기간 동안 가장 빨리 감소하였으나 (p<0.05), 황색도($b^*$)는 가장 높은 값을 유지하였다. 따라서 비육기간이 높을수록 홀스타인육 패티의 지방산화, 단백질산화, 육색소 산화가 촉진되었다. 특히 24개월령의 산화안정성이 가장 낮았다.

• 한국세라믹학회지
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• 제26권3호
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• pp.341-346
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• 1989

In order to evaluate the oxidation behavior of $\beta$-Sialon, $\beta$-Sialon ceramics was prepared from Si3N4, Al2O3, AlN and Y2O3 system. The specimens were oxidized in an oxygen atmosphere at 1, 20$0^{\circ}C$ for 9days. Oxidation behavior was evaluated by weight gain oxidation process, surface roughness. Microscopy, EDX and X-ray diffraction analysis were also used for the evaluation. The weight and surface roughness ofoxidized specimens were increased with increasing the oxidation time. Oxidized products were mullite, $\alpha$-cristobalite, yttrium aluminum oxide and yttrium silicate oxide.

• 한국식품위생안전성학회지
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• 제9권4호
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• pp.199-203
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• 1994

The oxidation of cholesterol in tallow heated at three frying temperatures, 130, 150 and 18$0^{\circ}C$ was studied by assaying cholesterol oxidation products(COP)by GC-MS. The correlation between levels of COP and changes of physicochemical parameters (peroxide value, polymer, polar components and dielectric constant) in tallow heated were studied. As temperature increased, the amount of cholesterol was decreased proportionally with heating time. However, the levels of COP did not increase considerably with increased frying temperature. The rate of cholesterol disappearance was the greatest at 18$0^{\circ}C$ and the smallest at 13$0^{\circ}C$. Larger amounts of COP formed were found at 15$0^{\circ}C$ than at 18$0^{\circ}C$. The levels of COP formed in tallow heated showed highly correlation with(r=0.94, n=30, p<0.01) polymer, polar components and dielectric constant, respectively.

• 한국표면공학회지
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• 제27권2호
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• pp.91-98
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• 1994

For the plasma sprayed as well as the EB-PVD thermal barrier coatings, the fracture paths within the oxidation products developed at the interface between the partially stabilized zirconia ceramic coating and NiCoCrAlY bond coat during cyclic thermal oxidation has been investigated. It was observed that the fracture in the oxidation products primarily took place within the oxide such as $Ni_{1-x}Co_3(Al_,Cr)_2O_4$ or at the interface between the oxide and $Al_2O_3$. It was found that Al2O3 developed first, followed by the Ni/Co/Cr rich oxides such as ,,$Ni_{1-x}Co_x(Al_,Cr)_2O_4$ $Cr_2O_3$and NiO at the interface between the ceramic coating and the bond coat in a cyclic high temperature environment. It was therfore concluded that the formation of the oxide containing Ni, Cr and Co was a life-limiting event for thermal barrier coatings during cyclic thermal oxidation.

• Journal of the Korean Wood Science and Technology
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• 제31권3호
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• pp.11-16
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• 2003

On nitrobenzene oxidation of aspen, spruce, and knauf wood meals gave rise to vanilline, syrigaldehyde, p-hydroxybenzoaldehyde, vanillic acid, and other minor oxidation products. The phenolic aldehydes (p-hydroxybenzaldehyde, vanilline, and syringaldehyde) are derived from oxidative degradation of the corresponding 4-hydroxyphenylpropane units and their ethers. The lignin content of knauf wood meals was different as the concentration of NaOH solution and cooking temperature. The lignin contents of aspen, spruce, and knauf wood meals were decreased as laccase treatment. The laccase caused C-oxidation, demethylation, cleavage in phenolic groups and C-C cleavage in syrigyl structures.

• Asian-Australasian Journal of Animal Sciences
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• 제29권5호
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• pp.695-701
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• 2016

This study was conducted to observe antioxidant enzyme activity, iron content and lipid oxidation of Korean native chickens and other poultry. The breast and thigh meat of three Korean native chicken breeds including Woorimatdak, Hyunin black and Yeonsan ogye, and three commercial poultry breeds including the broiler, White Leghorn and Pekin duck (Anasplatyrhyncos domesticus) were studied. The analyses of the antioxidant enzymes activity, iron content and lipid oxidation were performed in raw and cooked samples. The activity of catalase (CAT) in the thigh meat was higher than that of the breast meat of three Korean native chickens and the broiler, respectively. The activity of glutathione peroxidase (GPx) in the uncooked thigh meat of three Korean native chickens was higher than that of the breasts. The breast meat of Woorimatdak and Pekin duck had higher superoxide dismutase (SOD) activity than the others, while only the thigh meat of Pekin duck had the highest activity. Cooking inactivated CAT and decreased the activity of GPx and SOD. The thigh meat of Woorimatdak, White Leghorn, Yeonsan ogye and Hyunin black contained more total iron than the breast meat of those breeds. The heme-iron lost during cooking ranged from 3.2% to 14.8%. It is noted that the thigh meat had higher thiobarbituric acid reactive substances values than the breast in all chicken breeds. Though Woorimatdak showed higher antioxidant enzyme activity and lower released-iron percentage among Korean native chickens, no differences were found on lipid oxidation. We confirm that the dark meat of poultry exhibited higher antioxidant enzyme activity and contained more iron than the white meat.