• Toxicological Research
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• v.31 no.4
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• pp.347-354
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• 2015

Excess manganese (Mn) is neurotoxic. Increased manganese stores in the brain are associated with a number of behavioral problems, including motor dysfunction, memory loss and psychiatric disorders. We previously showed that the transport and neurotoxicity of manganese after intranasal instillation of the metal are altered in Hfe-deficient mice, a mouse model of the iron overload disorder hereditary hemochromatosis (HH). However, it is not fully understood whether loss of Hfe function modifies Mn neurotoxicity after ingestion. To investigate the role of Hfe in oral Mn toxicity, we exposed Hfe-knockout ($Hfe^{-/-}$) and their control wild-type ($Hfe^{+/+}$) mice to $MnCl_2$ in drinking water (5 mg/mL) for 5 weeks. Motor coordination and spatial memory capacity were determined by the rotarod test and the Barnes maze test, respectively. Brain and liver metal levels were analyzed by inductively coupled plasma mass spectrometry. Compared with the water-drinking group, mice drinking Mn significantly increased Mn concentrations in the liver and brain of both genotypes. Mn exposure decreased iron levels in the liver, but not in the brain. Neither Mn nor Hfe deficiency altered tissue concentrations of copper or zinc. The rotarod test showed that Mn exposure decreased motor skills in $Hfe^{+/+}$ mice, but not in $Hfe^{-/-}$ mice (p = 0.023). In the Barns maze test, latency to find the target hole was not altered in Mn-exposed $Hfe^{+/+}$ compared with water-drinking $Hfe^{+/+}$ mice. However, Mn-exposed $Hfe^{-/-}$ mice spent more time to find the target hole than Mn-drinking $Hfe^{+/+}$ mice (p = 0.028). These data indicate that loss of Hfe function impairs spatial memory upon Mn exposure in drinking water. Our results suggest that individuals with hemochromatosis could be more vulnerable to memory deficits induced by Mn ingestion from our environment. The pathophysiological role of HFE in manganese neurotoxicity should be carefully examined in patients with HFE-associated hemochromatosis and other iron overload disorders.

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.389-400
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• 2009

Iron and manganese contents are usually over the limit of drinking water standard (0.3 mg/L) in unconsolidated aquifer of river bank filtration site in Nakdong river. Surge block and air surging techniques used in this study are useful tools to remove the slime within gravels and pebbles, to increase permeability of aquifer, to provide oxygen into aquifer, and to discharge iron and manganese oxides from a well. Surging activity brought about $5{\sim}8$ and $5{\sim}9$ times decreases in $Fe_{(total)}$ and $Fe^{2+}$ contents, and also 10 times decrease in $Mn^{2+}$ contents compared to non-surging condition, respectively. Additionally, iron oxide and manganese oxide increased up $1{\sim}1.2$ times after surging. This result shows that air injection into the aquifer can help iron and manganese content decreased and in-situ treatment technology needs to be introduced in river bank filtration project in South Korea.

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.141-145
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• 2005

• Nutrition Research and Practice
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• v.2 no.4
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• pp.317-321
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• 2008

Macrophages play a key role in iron metabolism by recycling iron through erythrophagocytosis. Ferroportin-l (FPN1) is a transporter protein that is known to mediate iron export from macrophages. Since divalent metals often interact with iron metabolism, we examined if divalent metals could regulate the expression of FPN1 in macrophages. J774 macrophage cells were treated with copper, manganese, zinc, or cobalt at 10, 50, or $100\;{\mu}M$ for 16 to 24 h. Then, FPN1 mRNA and protein levels were determined by quantitative real-time PCR and Western blot analyses, respectively. In addition, effects of divalent metals on FPN1 promoter activity were examined by luciferase reporter assays. Results showed that copper significantly increased FPN1 mRNA levels in a dose-dependent manner. The copper-induced expression of FPN1 mRNA was associated with a corresponding increase in FPN1 protein levels. Also, copper directly stimulated the activity of FPN1 promoter-driven reporter construct. In contrast, manganese and zinc had no effect on the FPN1 gene expression in J774 cells. Interestingly, cobalt treatment in J774 cells decreased FPN1 protein levels without affecting FPN1 mRNA levels. In conclusion, our study results demonstrate that divalent metals differentially regulate FPN1 expression in macrophages and indicate a potential interaction of divalent metals with the FPN1-mediated iron export in macrophages.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.207-220
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• 1995

In order to study on the long-term change of water quality, water analysis was conducted at 16 sites surrounding the Kumho river system for 11 times from September 1990 to August 1993. Analytical items for the study of water Quality are as follows; water temperature, pH, COD, BOD, DO, SS, electrical conductivity, $NH_3-N$, $NO_2^-N$, NO_3^-N$, $PO_4^{3-}-P$, total-P, hardness, oil and grease, ABS, phenol, zinc, chromium, cadmium, manganese, iron, lead and color. The long-term change of water quality in the Kumho river for the period studied was found that the values of water temperature, electrical conductivity, phenol, $NO_2^-N$ and $NH_3-N$ were increasing and those of COD, BOD, SS, oil and grease, ABS, NO_3^-N$, $PO_4^{3-}-P$, copper, zinc, chromium, cadmium, manganese and lead were decreasing, while those of pH, hardness, iron and manganese were steady.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.917-920
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• 2001

Effects of addition of manganese and final reduction on segregation behavior of sulfur and final mangetic induction during final annealing have been investigated in the 300 ppm sulfur-contained 3% silicon-iron alloy strips with or without manganese. At the same concentration of sulfur, lower final reduction is favorable for final Goss texture. This is because the probability that the initial Goss grains survive under the highly segregated sulfur atmosphere and grow selectively within the segregated sulfur-free time range becomes higher. In the case of 3% silicon-iron with manganese, much lower magnetic induction was obtained, although the weak final reduction of 30% is given to the alloy, comparative to the 40%. This is because MnS particles acted as an reducer in the primary grain size.

• Korean Journal of Community Nutrition
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• v.2 no.2
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• pp.133-140
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• 1997

The serum concentrations of the major minerals(calcium, phosphorus, magnesium, sodium, potassium) and trace elements(iron, Zinc, copper manganese)were datermined in 23 breast fed infants living in Eumsung, Choong-buk region. The results obtained are summarized as follows: 1)The mean levels of calcium, phosphorus, magnesium, sodium and potassium of the serum of total subjects were 8.15$\pm$0.33mg/dI, 11.06$\pm$0.16mg/dI, 2.00$\pm$0.14mg/dI, 3.4476$\pm$17.99mg/dI and 9.06$\pm$2.04mg/dI respectively. 2)The serum concentrations of iron, zinc, copper and manganese in total subjects averaged 95.83$\pm$0.33mg/dI, 93.79$\pm$7.06$\mu$g/dI and 98.57$\pm$7.06 $\mu$g/dI and 4.93$\pm$0.62$\mu$g/dI respecitively. 3)Breast fed infants had significantly higher serum calcim, magnesium, sodium and iron concentrations than the formula fed groups. Otherwise, serum potassium, copper and manganese levels in breast milk fed infants were significantly lower than those in formula fed infants. 4) In formula fed infants, serum potassium and copper levels increased increased significantly with months after birth.

• Tribology and Lubricants
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• v.36 no.2
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• pp.88-95
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• 2020

In this study, we investigate the mechanical properties of high manganese steel, and the friction and wear characteristics of brake friction material containing this steel, for passenger car application, with the aim of replacing copper and copper alloys whose usage is expected to be restricted in the future. These steels are prepared using a vacuum induction melting furnace to produce binary and ternary alloys. The hardness and tensile strength of the high manganese steel decrease and the elongation increases with increase in manganese content. This material exhibits high values of hardness, tensile strength, and elongation; these properties are similar to those of 7-3 brass used in conventional friction materials. We fabricate high manganese steel fibers to prepare test pad specimens, and evaluate the friction and wear characteristics by simulating various braking conditions using a 1/5 scale dynamometer. The brake pad material is found to have excellent friction stability in comparison with conventional friction materials that use 7-3 brass fibers; particularly, the friction stability at high temperature is significantly improved. Additionally, we evaluate the wear using a wear test method that simulates the braking conditions in Europe. It is found that the amount of wear of the brake pad is the same as that in the case of the conventional friction material, and that the amount of wear of the cast iron disc is reduced by approximately 10. The high manganese steel is expected to be useful in the development of eco-friendly, copper-free friction material.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.34-63
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• 2003

Idiopathic Parkinson's disease (IPD) represents a common neurodegenerative disorder. While epidemiological studies have suggested a number of risk factors including age, gender, race, and inherited disorder, the cumulative evidence supports the view that environmental or occupational exposure to certain chemicals may contribute to the initiation and progress of Parkinsonism.(omitted)

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.369-373
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• 2002

The liquid phase oxidation of p-xylene has been carried out with oxygen-enriched gas, and the manganese component was precipitated probably via over-oxidation to $Mn^{4+}$. The precipitation increased with rising oxygen concentration in the reaction gas and occurred mainly in the later part of the oxidation. The activity of the reaction decreased, and the blackening of the product and side reactions to carbon dioxide increased with the degree of precipitation. Precipitation can be decreased with the addition of metal ions, such as cerium, chromium and iron.