• Korean Journal of Microbiology
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• v.11 no.2
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• pp.69-78
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• 1973

In order to investigate the distribution of an iron-oxidizing bacterium, Ferrobacillus ferrooxidans in Korea, the authors had carried out the chemical and microbiological analysis of mine water. The results obtained were as follows : 1. Ferrobacillus ferrooxidans concerned to leaching was isolated from 10 copper mine water out of 46 sites in Korea. 2. As the results of bacterial oxidation, the contents of sulfuric acid, ferric sulphate and copper in the bacteria-bearing solutions were higher than those in bacteria-free solutions.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1113-1116
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• 1998

A new graphite intercalation compound (GIC), n-octylammonium tetrachlorofeffate(Ⅲ)-graphite, has been derived from well-known ferric chloride graphite intercalation compound. X-ray diffration study shows that the basal spacing of this new GIC is 20.8 Å. In order to investigate the local geometry around the iron atom in the graphite layers, X-ray absorption spectroscopy experiments were performed. The first discharge capacity of its exfoliated form is found to be 862 mAh/g, which is more than double the value of pristine graphite (384 mAh/g). Such a drastic increase implies that the exfoliated graphite is a promising electrode material.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.86-91
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• 2008

Dicamba(3,6-dichloro-2-methoxybenzoic acid) is used to control for pre and post-emergence of annual and perennial broad-leaf weeds. It is very soluble in water and highly mobile, acidic herbicide. So it is easily moved and detected in groundwater. Zerovalent iron(ZVI) has been used for the reductive degradation of certain compounds through amination of nitro-substituted compounds and dechlorination of chloro-substituted compounds. In this study, we investigated the potential of ZVI for the oxidative degradation of dicamba in water. The degradation rate of dicamba by ZVI was more rapidly increased in pH 3.0 than pH 5.0 solution. The degradation percentage of dicamba was increased with increasing amount of ZVI from 0.05% to 1.0%(w/v) and reached above 90% within 3 hours of reaction. As a result of identification by GC-MS after derivatization with diazomethane, we obtained three degradation products of dicamba by ZVI. They were identified 4-hydroxy dicamba or 5-hydroxy dicamba, 4,5-dihydroxy dicamba and 3,6-dichloro-2-methoxyphenol. 4-Hydroxy dicamba or 5-hydroxy dicamba and 4,5-dihydroxy dicamba are hydroxylation products of dicamba. 3,6-dichloro-2-methoxyphenol is hydroxyl group substituted compound instead of carboxyl group in dicamba. We also confirmed the same degradation products of dicamba in the Fenton reaction which is one of oxidation processes using ferric sulfate and hydrogen peroxide. But we could not find out the dechlorinated degradation products of dicamba by ZVI.

• Resources Recycling
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• v.17 no.5
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• pp.37-43
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• 2008

Stripping experiments of iron from the loaded Alamine336 by sulfurous, chloric and sulfuric acid solutions have been performed by varying the concentration of acid and stripping conditions. The stripping percentage of iron decreased with the increase of HCl and $H_{2}SO_4$ concentration, while that increased with the increase of $H_{2}SO_3$ concentration up to 3 M. Stripping temperature had adverse effect on the stripping percentage of iron in the stripping by $H_{2}SO_3$ solution, while the stripping percentage of iron by HCl solution increased with the increase of temperature. Stripping isotherm of iron by 0.1 M HCl and 0.1 M $H_{2}SO_4$ solution indicated that three and four stripping stages could result in a solution containing 0.05 M iron at an O/A ratio of 1/10 from the loaded Alamine336 phase where iron concentration was 0.5 M.

• Korean Journal of Microbiology
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• v.11 no.4
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• pp.189-195
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• 1973

With the gradual expansion of copper demands, the utilization of enormous tonnages of waste copper mineral containig up to 0.5% copper becomes available. In order to investigate the possibilities on the application of bacterial leaching method to waste dumps or abandoned mines, the authors had carried out microbial leaching of copper minerals by F.ferrooxidans isolated from the Dalsung copper mine water. The results obtained were as follows : 1. The copper extraction rate from the Dalsung chalcopyrite has been a little accerelated by using flasks in place of percolators. 2. The percentage of copper extracted from the Dalsung chalcopyrite sample was 100% in 30 days in the presence of iron-oxidizing bacteria F.ferrooxidans while 9.27% in the absence of bacteria. 3. F.ferroxidans was capable of producing sufficient quantities of ferric sulfate and sulfuric acid from ferrous iron to bring about the dissolution of 100% of copper from the Dalsung chalcopyrite.

• Journal of Microbiology and Biotechnology
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• v.22 no.1
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• pp.46-49
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• 2012

The Vibrio vulnificus vuuA gene, of which expression is repressed by a complex of iron and ferric uptake regulator (Fur), was characterized to localize the Fur-binding site in its upstream regulatory region. In silico analysis suggested the presence of two possible Fur-binding sites; one is a classical Fur-box and the other is a previously reported distinct Fur-binding site. Site-directed mutagenesis and DNase I protection assays revealed the binding site for the iron-Fur complex, which includes an extended inverted repeat containing a homologous sequence to the classical Fur-box.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.57-62
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• 1998

We hypothesized the primary effect of ginseng was to protect cell membrane fatty acids from decomposition caused by free radicals. To confirm the antioxidant effect of ginseng, we measured the inhibitory effect on the formation of thiobarbituric acid-reactive substances, an indicator of lipid peroxidation, and evaluated the free radical scavenging effect of ginseng by electron spin resonance spectrometer, and gas chromatography. The results showed that thiobarbituric acid-reactive substances formed and the loss of arachidonic acid during lipid peroxidation, and that hydroxyl (-like) radical peak formed by the iron complex (ferric nitrilotriacetate, an known free radical generator in vitro) were completely inhibited by ginseng extract. This antioxidant effect of ginseng may be responsible for its wide pharmacological actions in clinical practice. As the free radical reactions in general are rapid and non-specific, ginseng seems to act as a normalizer, rather than a general tonic, at the stages of acute or chronic active phase of the various diseases.

• Archives of Pharmacal Research
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• v.18 no.3
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• pp.159-163
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• 1995

Previously, we have reported that methylene blue (MB) induces cytotoxicity in human brain tumor cells through the generation of free radicals. In this study the effect of deferoxamine (DFO), an iron chelator, on MB-induced cytotoxicity was investigated using SK-N-MC human neuroblastoma and U-373 MG human astrocytoma cells as model cellular systems. The cytotoxic effect of MB was potentiated by DFO. The potentiation effect of DFO was significantly blocked by either stoichiometric amounts of ferric ion, various antioxidants, hydroxyl radical scavengers or intracellular $Ca^{2+}$ release blockers. These results suggest that hydroxyl radical and intracellular $Ca^{2+}$ may act as important mediators of the enhanced cytotoxicity by MB and DFO. These results further suggest that the combined treatment with MB and DFO may be useful for the therapeutical applications of human brain tumors.

• Advances in nano research
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• v.10 no.1
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• pp.71-76
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• 2021

Synthesis of nanoparticles using green technology using plants is gaining significant attention as it is an environmentally friendly substitute to conventional physical and chemical methods. The present study was focused on the chemical and green synthesis of Iron Oxide nanoparticles from ferric chloride. The green synthesis was achieved by utilizing the bio components of Hibiscus rosa-sinensis. The Fe3O4 nanoparticles with the size range of 87-400 nm were synthesized by wet chemical reduction technique which are unstable, prone to aggregation while in green synthesis the phytochemicals present in the leaf extract acts as the capping as well as the reducing agent thus the green synthesized iron (III) oxide nanoparticles were naturally stabilized, spherical shaped and are in the size range of 2-80 nm. The results of both the protocols are compared and presented briefly.

• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1357-1363
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• 2008

The $P_{entC}$ promoter of the entCERA operon encoding enzymes for enterobactin biosynthesis in Escherichia coli is tightly regulated by the availability of iron in the culture medium. In iron-rich conditions, the $P_{entC}$ promoter activity is strongly repressed by the global transcription regulator Fur (ferric uptake regulator), which complexes with ferrous ions and binds to the Fur box 19-bp inverted repeat. In this study, we have constructed the expression vector pOS2 containing the $P_{entC}$ promoter and characterized its repression, induction, and modulation by quantifying the expression of the lacZ reporter gene encoding $\beta$-galactosidase. $\beta$-Galactosidase activities of E. coli transformants harboring pOS2-lacZ were highly induced in the presence of divalent metal ion chelators such as 2,2'-dipyridyl and EDTA, and were strongly repressed in the presence of excess iron. It was also shown that the basal level $\beta$-galactosidase expression by the $P_{entC}$ promoter was drastically decreased by incorporating the fur gene into the expression vector. Since the newly developed iron chelator-inducible expression system is efficient and cost-effective, it has wide applications in recombinant protein production.