• 전기화학회지
• /
• 제19권2호
• /
• pp.45-49
• /
• 2016

양이온 교환막 연료전지 운전 중에 발생하는 하이드록시 라디칼에 의한 전해질 막의 산화분해를 효과적으로 방지하기 위해 유기물 라디칼냐��쳐를 도입하였다. 술폰화 폴리아릴렌에테르술폰 고분자를 이용하여 폴리페놀 화합물의 일종인 루틴을 도입하여 복합막을 제조하였고, 제조된 고분자 전해질 복합막은 함수율 및 이온전도도의 측정을 통하여 루틴이 전해질 막의 물리화학적 성질에 미치는 영향에 대해서 조사하였다. 실제 연료전지 운전과 유사한 조건을 구현할 수 있는 과산화수소 폭로 가속화 평가장치를 이용하여 전해질 복합막의 산화안정성을 평가하였다. 루틴을 함유한 고분자 전해질 복합막은 이온전도도가 유지되면서 산화안정성이 향상된 결과를 보여주었다.

• 통합자연과학논문집
• /
• 제15권3호
• /
• pp.123-129
• /
• 2022

Schwann cells play a critical role for myelination in peripheral nerve system. It also plays an important role in nerve protection and regeneration. In peripheral nerve damage, regeneration is induced by the migration and proliferation of Schwann cells which were promoted by suppressing the oxidative stress. In this study, Human placental extract was prepared by homogenization and estimated its efficacy in RSC96 cells. Placental extract exhibited a protective effect against hydrogen peroxide-induced oxidative stress in RSC96 cells, confirmed by MTT assay. Furthermore, placental extract decreased intracellular ROS against oxidative stress, confirmed by DCFH-DA assay. Autophagy was visualized with Cyto-ID staining to confirm the autophagy activity of placental extracts. The activity of autophagy was confirmed by immunoblot analysis of autophagy flux-associated proteins such as LC3 conversion and SQSTM1 degradation. Thus, we confirmed the antioxidant effect of placental extract to protect RSC96 cells from oxidative stress, and observed that it activated autophagy and restored autophagy flux.

• Macromolecular Research
• /
• 제16권5호
• /
• pp.473-480
• /
• 2008

In this study we investigated bacterial and cell adhesion to poly(propylene carbonate) (PPC) films, that had been synthesized by the copolymerization of carbon dioxide (a global warming chemical) with propylene oxide. We also assessed the biocompatibility and biodegradability of the films in vivo, and their oxidative degradation in vitro. The bacteria adhered to the smooth, hydrophobic PPC surface after 4 h incubation. Pseudomonas aeruginosa and Enterococcus faecalis had the highest levels of adhesion, Escherichia coli and Staphylococcus aureus had the lowest levels, and Staphylococcus epidermidis was intermediate. In contrast, there was no adhesion of human cells (cell line HEp-2) to the PPC films, due to the hydrophobicity and dimensional instability of the surface. On the other hand, the PPC films exhibited good biocompatibility in the mouse subcutaneous environment. Moreover, contrary to expectation the PPC films degraded in the mouse subcutaneous environment. This is the first experimental confirmation that PPC can undergo surface erosion biodegradation in vivo. The observed biodegradability of PPC may have resulted from enzymatic hydrolysis and oxidative degradation processes. In contrast, the PPC films showed resistance to oxidative degradation in vitro. Overall, PPC revealed high affinity to bioorganisms and also good bio-degradability.

• Journal of Applied Biological Chemistry
• /
• 제49권4호
• /
• pp.157-161
• /
• 2006

The performance of abiotic degradation of oxadiazon was investigated by applying zerovalent iron(ZVI), potassium permanganate($KMnO_4$) and titanium dioxide($TiO_2$) in the contaminated water. Experimental conditions allowed the disappearance of oxadiazon in the abiotic system. The degradation of this herbicide was monitored in buffer solutions having pH 3, 5 and 7 in the presence of iron powder in which the maximum degradation rate was achieved at acidic condition(pH 3) by 2% of ZVI treatment. The oxidative degradation of oxadiazon was observed in aqueous solution by $KMnO_4$ at pH 3, 7 and 10 in which the highest disappearance rate was found at neutral pH when treated with 2% of $KMnO_4$. The catalytic degradation of oxadiazon in $TiO_2$ suspension was obtained under dark and UV irradiation conditions. UV irradiation enhanced the degradation of oxadiazon in aquatic system in the presence of $TiO_2$. Conclusively, the remediation strategy using these abiotic reagents could be applied to remove oxadiazon from the contaminated water.

• Biomolecules & Therapeutics
• /
• 제6권2호
• /
• pp.111-118
• /
• 1998

Ambroxol is thought to have antioxidant ability and some antiinflammatory effect. Effect of ambroxol on the oxidative damages of lipid, collagen and hyaluronic acid was examined. F $e_{2+}$(10 $\mu$M) and 100$\mu$Mascorbate-induced lipid peroxidation of liver microsomes was inhibited by 10 and 100$\mu$M ambroxol, 30$\mu$g/ml catalase and 10 mM DABCO but was not affected by 30$\mu$g/ml SOD and 10 mM DMSO. A 10 and 100$\mu$M ambroxol and 10 mM DABCO inhibited the peroxidative action of 10$\mu$M F $e_{3+}$, 160$\mu$M ADP and 100$\mu$M NADPH on microsomal lipids, whereas inhibitory effects of 30$\mu$g/ml SOD,30$\mu$g/ml catalase and 10 mM DMSO were not detected. The degradation of hyaluronic acid caused by 107M Fe2\\`,5007M H2O2 and 100$\mu$M ascorbate was inhibited by 10 and 100$\mu$M ambroxol,30$\mu$g/ml catalase,10 mM DMSO and 10 mM DABCO, while 30$\mu$g/ml SOD did not show any effect. The cartilage collagen degradation caused by 307$\mu$ F $e_{2+}$,500$\mu$M $H_2O$$_2$ and 200$\mu$M ascorbate was prevented by 100$\mu$M ambroxol. $H_2O$$_2$ and OH . were scavenged by ambroxol, whereas $O_2$, was not removed by it. Ambroxol (100$\mu$M) and 1 mM cysteine reduced DPPH to 1,1-diphenyl-2-picrylhydrazine. In conclusion, ambroxol may inhibit the oxidative damages of lipid, hyaluronic acid and collagen by its scavenging action on oxidants, such as OH . and probably iron-oxygen complexes and exert antioxidant ability.

• Mass Spectrometry Letters
• /
• 제6권2호
• /
• pp.38-42
• /
• 2015

Roflumilast analogs are a group of drugs which act as selective photodiesterase (PDE-4) inhibitor for the treatment severe chronic pulmonary disease associated with chronic brochnonities. Structural identification of degradation products using high resolution mass spectrometry and theoretical investigation by density functional theory have been successfully carried out on roflumilast to identify four degradation products namely, 3,5-dichloropyridin-4-amine, N-(3,5-dichloropyridin-4-yl)-4-(difluoromethoxy)-3-hydroxy benzamide, N-(3,5-dichloropyridin-4-yl)-3-(cyclopropylmethoxy)-4-(difluoromethoxy) benzamide and 3-(cyclopropylmethoxy)-N-(3,5-dichloro-1-oxidopyridin-4-yl)-4-(difluoro methoxy) benzamide, generated in alkali, acidic and oxidative conditions.

• International Journal of Safety
• /
• 제7권1호
• /
• pp.10-14
• /
• 2008

For evaluating the radiation degradation of cross-linked polyethylene (XLPE) cable insulation due to the irradiated oxidation, XLPE was irradiated with ${\gamma}$-ray. For each irradiated samples, TGA, DSC, FT-IR, and tensile tests were carried out. Regarding radiation degradation, oxidative process was predominant. TGA, DSC and FT-IR can be useful tools for evaluating the radiation degradation due to the irradiated oxidation because these analyses need only small amount of samples. The results of TGA, DSC and FTIR analyses showed the similar tendency for irradiated degradation. They can be useful tools for evaluating the oxidation of insulating material by non-destructive testing.

• Bulletin of the Korean Chemical Society
• /
• 제33권3호
• /
• pp.833-838
• /
• 2012

The thermal degradation products of polytrimethylene terephthalate (PTT) obtained by heating the sample in the temperature range of $250-360^{\circ}C$ under non-oxidative conditions was characterized using MALDI-TOF (matrix assisted laser desorption/ionization) mass spectrometry. The structures of the degradation products were determined and the relative compositions were estimated. The MALDI-TOF mass spectra of the thermally degraded PTT sample showed three main series of oligomer products with different end groups, which were carboxyl/carboxyl, carboxyl/allyl, and allyl/allyl. In contrast to the thermal degradation of polyethylene terephthalate (PET), the oligomers containing terephthalic anhydrides were not detected, whereas the formation of oligomers containing the unsaturated allyl ester group was confirmed by mass assignment. From these results, it was concluded that the thermal degradation of PTT proceeds exclusively through the ${\beta}$-CH hydrogen transfer mechanism, which is in accordance with the proposed reaction mechanism for the thermal degradation of polybutylene terephthalate (PBT).

• 한국식품영양과학회지
• /
• 제24권2호
• /
• pp.234-241
• /
• 1995

Effect of microwave heating on the oxidative stability of the soybean oil, sesame oil, butter and margarine were investigated by mearsuring fatty acids amout and tocopherol losses. The index for chemical properteis, free fatty acid, peroxide value, anisidine value, carbonyl value, conjugated diene and triene levels were also mearsured in the oil samples for 5, 10, 15 and 20 min of heating in a microwave oven. No significant difference was observed on the fatty acids composition in the fats and oils before and after microwave heating. During microwave treatment, the oxidative degradation of the tocopherols in the samples became greater with increasing heating time. The amount of tocopherols in the soild fats, butter and margarine, dropped drastically after 5 min of heating and reduced to 95% of their original levels after 20min heating ${\gamma}$-tocopherol in butter showed the most unstable states and completely destroyed during microwave treatment for 20min. On the other hand, 80% of tocopherols in the liquid oils were still remained after 5min of heating except $\delta$-tocopherol in sesame oil.

• 한국환경과학회지
• /
• 제22권12호
• /
• pp.1561-1569
• /
• 2013

This study carried out a laboratory scale plasma reactor about the characteristics of chemically oxidative species (${\cdot}OH$, $H_2O_2$ and $O_3$) produced in dielectric barrier discharge plasma. It was studied the influence of various parameters such as gas type, $1^{st}$ voltage, oxygen flow rate, electric conductivity and pH of solution for the generation of the oxidant. $H_2O_2$ and $O_3$.) $H_2O_2$ and $O_3$ was measured by direct assay using absorption spectrophotometry. OH radical was measured indirectly by measuring the degradation of the RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical). The experimental results showed that the effect of influent gases on RNO degradation was ranked in the following order: oxygen > air >> argon. The optimum $1^{st}$ voltage for RNO degradation were 90 V. As the increased of $1^{st}$ voltage, generated $H_2O_2$ and $O_3$ concentration were increased. The intensity of the UV light emitted from oxygen-plasma discharge was lower than that of the sun light. The generated hydrogen peroxide concentration and ozone concentration was not high. Therefore it is suggested that the main mechanism of oxidation of the oxygen-plasma process is OH radical. The conductivity of the solution did not affected the generation of oxidative species. The higher pH, the lower $H_2O_2$ and $O_3$ generation were observed. However, RNO degradation was not varied with the change of the solution pH.