• Clean Technology
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• v.20 no.3
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• pp.269-276
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• 2014

This study was aimed to develop catalytic system for the dry-based reduction of oxidized mercury ($Hg^{2+}$) to elemental mercury ($Hg^0$) which is one of the most important components comprising mercury continuous emission monitoring system (Hg-CEMS). Based on the standard potential in oxidation-reduction reaction, transition metals including Fe, Cu, Ni and Co were selected as possible candidates for catalyst proceeding spontaneous reduction of $Hg^{2+}$ into $Hg^0$. These transition metal catalysts revealed high activity for reduction of $Hg^{2+}$ into $Hg^0$ in the absence of oxygen in reactant gases. However, their activities were greatly decreased in the presence of oxygen, which was attributed to the transformation of transition metals by oxygen to the corresponding transition metal oxides with less catalytic activity for the reduction of oxidized mercury. Hydrogen supplied to the reactant gases significantly enhanced $Hg^{2+}$ reduction activity even in the presence of oxygen. It might be due to occurrence of combustion reaction between $H_2$ and $O_2$ causing the consumption of $O_2$ at such high reaction temperature at which oxidized mercury reduction reaction took place. Because the system showed high activity for $Hg^{2+}$ reduction to $Hg^0$, which was compatible to that of wet-chemistry technology using $SnCl_2$ solution, the catalytic reduction system of Fe catalyst with the supply of $H_2$ could be employed as a commercial system for the reduction of oxidized mercury to elemental mercury.

• Journal of the korean veterinary medical association
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• v.27 no.4
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• pp.193-196
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• 1991

• Bulletin of Food Technology
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• v.18 no.4
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• pp.158-174
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• 2005

• River and Culture
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• v.8 no.1
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• pp.66-70
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• 2012

• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.12-18
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• 2012

The prohibitively high cost of Pt catalyst might be the biggest barrier for the commercialization of proton exchange membrane fuel cells (PEMFC) of which wide application is expected. Worldwide research efforts for the development of alternative to Pt oxygen reduction reaction (ORR) catalyst are made recently. One of the important considerations in the catalyst development is durability issue as well as economic aspect. From this point of view, platinum group metals (PGM) except Pt can be a candidate for replacing Pt catalyst because the material properties and the catalytic activity of PGM are expected to be similar to Pt. In contrast to Ir, Rh and Os to which not so much attention has been paid as an ORR catalyst, Pd that is most similar to Pt in terms of material properties and catalytic activity and Ru that is in the form of chalcogenide have been studied intensively. Activity comparison between non-Pt and Pt oxygen reduction catalysts by half cell test using RDE (rotating disk electrode) or PEMFC MEA (membrane electrode assembly) operation indicates that Pd-based catalysts show the most similar activity to Pt. In this paper we analyze the composition of PGM ORR catalyst in literature to promote the development of non-Pt ORR catalyst.

• Neonatal Medicine
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• v.17 no.1
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• pp.44-52
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• 2010

Purpose : The aim of this study was to develop a model for necrotizing enterocolitis (NEC) in the neonatal rat using endotoxin and hypoxia, a plausible insult in a neonatal intensive care and to investigate the role of apoptosis as the underlying mechanism. Methods : Newborn rats were given oral endotoxin and intermittent 8% hypoxia$\pm$caspase inhibitor. The intestinal histology was evaluated using hematoxylin-eosin staining. Apoptosis was analyzed with TUNEL staining and by measuring the caspase 3 activity in the intestinal lysates. IEC-6 cells were assessed for apoptosis and the expression of Bax, Bcl-2, Fas and FasL was measured after treatment with endotoxin and hypoxia. Results : Oral endotoxin (5 mg/kg) and exposure to 8% hypoxia of 60-min duration twice induced human NEC-like lesions in the rat intestine. Intestinal tissue revealed increased apoptosis and caspase-3 activity. After caspase inhibitor treatment, the grades of both apoptosis and NEC were significantly reduced. IEC-6 cells exhibited increased apoptosis and caspase 3 activity after endotoxin and hypoxia treatment and significantly increased Bax/Bcl- 2 ratio compared to control cells. Conclusion : This neonatal rat model of NEC which was induced by oral endotoxin and intermittent hypoxia showed increased apoptosis of intestinal epithelial cells that was mediated by caspase 3 activation. Our model has a advantage in the study of NEC because the use of much more clinically plausible insults may provide a suitable model for the investigation of its pathophysiology and therapeutic trials.

• Journal of Life Science
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• v.23 no.10
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• pp.1223-1229
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• 2013

Ursolic acid (UA) a bio-active ingredient found in a variety of fruits and vegetables, and it has potent antioxidant activity. However, the role of UA in mouse embryonic stem (ES) cells is poorly understood. This study investigated the functional role of UA in regulating the development of mouse ES cells under hypoxia. Hypoxia did not exert a significant effect on the undifferentiated state of mouse ES cells. However, it induced reactive oxygen species (ROS) generation and increased the level of lactate dehydrogenase (LDH) production at 48 h of hypoxic exposure. Conversely, oxidative stress induced by hypoxia was significantly inhibited by UA ($30{\mu}M$) pretreatment. Hypoxia significantly decreased cell survival and the level of [$^3H$] thymidine incorporation, both of which recovered following pretreatment of UA. In addition, UA decreased the apoptotic effect of hypoxia by attenuating caspase-3 cleavage or by recovering cellular inhibition of the apoptotic protein (cIAP)-2 and Bcl-2 expression. We further found that UA decreased senescence-associated beta-galactosidase activity. We suggest that UA is a natural antioxidant and one of the functional modulators of hypoxia-induced survival, apoptosis, proliferation, and aging in mouse ES cells.

• Korean journal of applied entomology
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• v.55 no.3
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• pp.267-275
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• 2016

Chlorine dioxide has an insecticidal activity via its production of reactive oxygen species (ROS). Its cytotoxic activity has been regarded as a main cause of the insecticidal activity. This study tested a hypothesis that cytotoxicity of chlorine dioxide is resulted from its induction of apoptosis against target cells using ROS. Injection of chlorine dioxide significantly reduced total hemocyte counts of Plodia interpunctella larvae and subsequently killed the larvae. To analyze the cytotoxicity with respect to apoptosis, terminal deoxyribonucleotidyl transferase nick end translation (TUNEL) assay was performed. An insect cell line (Sf9) cells were exposed to different concentrations of chlorine dioxide. TUNEL assay showed that chlorine dioxide induced significant apoptosis of Sf9 cells in a dose-dependent manner. When different concentrations of chlorine dioxide were injected to larvae of P. interpunctella, it showed a dose-dependent induction of apoptosis against hemocytes. However, addition of vitamin E significantly suppressed the apoptosis induction and insecticidal activity of chlorine dioxide in a dose-dependent manner. These results suggest that cytotoxicity of chlorine dioxide is resulted from its induction of apoptosis against insect cells using ROS.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.757-762
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• 2010

The purposes of this study were to examine the effects of aerobic exercise capacity on free oxygen radicals in blood(FORB) during submaximal exercise in rowing ergometer and as for study purposes, a set of experiments were conducted using one group of 6 rowing players(RP) and the other group of 6 non rowing players(NRP) at the maximum heart rate reserve(HRR) 85~90% exercise intensity. Oxygen free radical was sampled 5 times including a rest period(ARP), immediate after exercise(IAE), 10 minutes after exercise(10MAE), 20 minutes after exercise(20MAE) and 30 minutes after exercise(30MAE). Accordingly, following findings were derived from current study. The effects of interaction between groups and times were significant in oxygen free radical(p<.05) and post hoc tests revealed that significant differences occurred between 10MAE and 20MAE and between 20MAE and 30MAE. In conclusion, the aerobic exercise capacity excellence RP group had more positive recovery pattern than that in the NRP group from FORB of negative influence to the human body

• Korean Journal of Food Science and Technology
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• v.19 no.4
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• pp.311-316
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• 1987

The present paper was carried out to investigate the effects of active oxygen radicals on the DNA damage by linoleic acid peroxidation by using active oxygen scavengers in a linoleic acid-DNA system. DNA was greatly damaged by linoleic acid peroxidation, and the DNA damage was inhibited by the addition of active oxygen scavengers. Among active oxygen scavengers tested, ${\alpha}-tocopherol$ and superoxide dismutase greatly inhibited the DNA damage, but catalase and tris (hydroxymethyl) aminomethane didn't show such effects. Accordingly, singlet oxygen and superoxide anion greatly affected to the DNA damage occurring during linoleic acid peroxidation, and hydrogen peroxide was shown to participate in DNA damage in the early stage of peroxidation. And, the DNA damage by active oxygen radicals was mainly induced in the early stage of linoleic acid peroxidation.