• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.606-609
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• 2000

We describe the preparation of a manganese oxide polymorph in which the solid-pore architecture of the material is controllably varied. All MnO$_2$ gels derived from a KMnO$\_$4/-based sol-gel synthesis. The mesoporous structure of the initial gel is maintained by removingore fluid under conditions where the capillary forces that result fro extraction are either low or no existent. are either low or noexistent. Controlling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.2
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• pp.150-157
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• 2020

The protective effects of a Celastrus orbiculatus Thunb (CO) extract against manganese dioxide (MnO₂)-induced cytotoxicity in cultured C6 glioma cells were examined. This study assessed the antioxidative effects, including the suppressive ability of lipid peroxidation (LP), the inhibitory ability of xanthine oxidase (XO), and the cell viability. MnO₂ decreased the cell viability remarkably in a dose-dependent manner. The XTT₅₀ value was determined to be 146.7 μM in these cultures. The cytotoxicity of MnO₂ was calculated to be mid-toxic using Borenfreund and Puerner's toxic criteria. Kaempferol (KAE) increased the cell viability damaged by MnO₂-induced cytotoxicity significantly. Regarding the protective effects of the CO extract on MnO₂-induced cytotoxicity, the CO extract increased cell viability significantly compared to the MnO₂-treated group. The CO extract also had inhibitory abilities against lipid peroxidation (LP) and xanthine oxidase (XO). From these findings, oxidative stress is involved in the cytotoxicity of MnO₂. The CO extract effectively blocked the cytotoxicity induced by MnO₂ via its antioxidative effects. Conclusively, natural resources, such as the CO extract, might be a useful agent for the diminution or improvement of the heavy metal cytotoxicity correlated with disease through oxidative stress, such as MnO₂, a Parkinsonism inducer.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.541-542
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• 2009

• Journal of the Korean Professional Engineers Association
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• v.18 no.3
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• pp.45-54
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• 1985

이산화망간 건전지에 실사용되고 있는 전해액 ZnCl$_2$-$H_2O$의 조성 변화에 따른 건전지의 특성변화를 비교 검토하여, 건전지성능향상의 기본인자 및 그 변화정도를 조사코자 하였다. ZnCl$_2$ 주사용 전지계는 특히 중부하연속방전이 우수하였으며 그 이유로는 농도분극현상이 적음에 기인되며 이는 $Zn^{++}$이 본계에서는 쉽게 이동함에 있다고 간주되며 그 $Zn^{++}$ 이온의 바른 이동은 이론치보다도 다량사용하게 되는 물의 역할에 기인되고 방전에 직접 필요한 수분량과, 기타의 목적 즉 반응 침전물의 재용해, ion carrier 등으로서 이용되는 수분량은, MnO$_2$와의 비율 및 방전 부하크기에 따라 다르다.

• Journal of the Korean Chemical Society
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• v.5 no.1
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• pp.18-21
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• 1961

The hydroxydation of the saturated fatty acids in order to prepare hydroxy fatty acids in the presence of catalysts was reported by several workers. The considering commercial applications of this reaction, authors studied on the hydroxydation of natural fats composed of nonhydroxy saturated fatty acids. Tallow and stearic acid were tested with manganese dioxide as catalyst, $110 {\pm}3^{\circ}C,$ and under atmospheric oxygen. The highest hydroxyl values were obtained at 20 hours for tallow, 107.6 and at 14 hours for stearic add, 116.0.

• Biomedical Science Letters
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• v.24 no.4
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• pp.357-364
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• 2018

Manganese (Mn) is used as main materials in various chemical processes of industry, but it suggested that Mn brings about its toxicant by fume or dust through respiratory system and skin barrier. Mn toxicant induces the loss of mental health and life quality by cerebrovascular and skin diseases. Nevertheless, it lefts much unknown on the mechanism and the effectively therapeutic methods about Mn toxicant. Therefore, this study was evaluated the cytotoxicity induced by manganese dioxide ($MnO_2$) in cultured NIH3T3 fibroblasts, and also, the correlation between $MnO_2$-induced cytotoxicity and oxidative stress was examined. While, the effect of Eclipta prostrata L. (EP) extract belong to Compositae was assessed against $MnO_2$-induced cytotoxicity in the view of antioxidative effect for searching the natural resources mitigating or preventing the $MnO_2$-induced cytotoxicity. In this study, $MnO_2$-induced cytotoxicity was revealed as mid-toxic by Borenfreud and Puerner's toxic criteria, and catalase (CAT), an antioxidant prevented $MnO_2$-induced cytotoxicity by the remarkable increase of cell viability in these cultures. While, in the protective effect of EP extract on $MnO_2$-induced cytotoxicity, EP extract effectively prevented the cytotoxicity induced by $MnO_2$ via antioxidative effects such as xanthine oxidase (XO) inhibitory ability and DPPH-radical scavenging ability. From the above results, EP extract showed the effective prevention against $MnO_2$-induced cytotoxicity correlated with oxidative stress by antioxidative effects. Conclusively, this study may be useful to research or development the alternatively therapeutic agent from natural resources like EP extract for the treatment of diseases resulted in oxidative stress.

• Journal of the Korean Chemical Society
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• v.15 no.5
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• pp.236-241
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• 1971

Various modifications of manganese dioxide have been discussed in terms of the chemical analysis by differential heating curve. The transformation temperatures of the modifications were observed as follows; ${\alpha}-\;and\;{\beta}-MnO_2$ are both $580^{\circ}C∼650^{\circ}C$, ${\gamma}-MnO_2$is is $405^{\circ}C~605^{\circ}C$ and ${\delta}-MnO_2$is $860^{\circ}C~875^{\circ}C$, respectively. Endothermic peaks appeared at the transformation temperatures mentioned above. The restoration temperatures of transformation is completed depending on the amounts of the given samples, but the temperatures of the top of endothermic peaks are nearly constant. The curves of ${\alpha}-,{\beta}-MnO_2$and ${\delta}-MnO_2$ show small peaks while that of ${\gamma}-MnO_2$ shows a sharp and broad peak.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.142-149
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• 2008

This paper proposes an effective decomposition method of trichloroethylene using pellet packed-bed non-thermal plasma reactor and catalyst. For that, two types of reactors filled with manganese dioxide and alumina pellets are designed. When $MnO_2$ packed reactor is used, TCE decomposition rate is high due to the generation of oxygen atom radicals at the surface of catalyst during ozone decomposition. In addition, When $Al_2O_3$ packed reactor is used, TCE is oxidized into DCAC and it did not decomposed into small molecules such as COx and $Cl_2$. However, the plasma processed gas using $Al_2O_3$ packed reactor is passed through the $MnO_2$ catalyst reactor, which is placed at the downstream of plasma reactor, the decomposition rate increased as well due to oxygen atom radicals through ozone decomposition. Therefore, the adequate use of $MnO_2$ catalyst in the plasma process is very promising way to increase the decomposition efficiency.

• Korean Journal of Materials Research
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• v.33 no.7
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• pp.315-322
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• 2023

In the present work, we address the new route for the green synthesis of manganese dioxide (MnO₂) by an innovative method named the solution plasma process (SPP). The reaction mechanism of both colloidal and nanostructured MnO₂ was investigated. Firstly, colloidal MnO₂ was synthesized by plasma discharging in KMnO₄ aqueous solution without any additives such as reducing agents, acids, or base chemicals. As a function of the discharge time, the purple color solution of MnO₄^- (oxidation state +7) was changed to the brown color of MnO₂ (oxidation state +4) and then light yellow of Mn²⁺ (oxidation state +2). Based on the UV-vis analysis we found the optimal discharging time for the synthesis of stable colloidal MnO₂ and also reaction mechanism was verified by optical emission spectroscopy (OES) analysis. Secondly, MnO₂ nanoparticles were synthesized by SPP with a small amount of reducing sugar. The precipitation of brown color was observed after 8 min of plasma discharge and then completely separated into colorless solution and precipitation. It was confirmed layered type of nanoporous birnessite-MnO₂ by X-ray powder diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), and electron microscopes. The most important merits of this approach are environmentally friendly process within a short time compared to the conventional method. Moreover, the morphology and the microstructure could be controllable by discharge conditions for the appropriate potential applications, such as secondary batteries, supercapacitors, adsorbents, and catalysts.

• Korean Journal of Soil Science and Fertilizer
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• v.3 no.1
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• pp.23-28
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• 1970

The effect of wollastonite and manganese dioxide on the growth of rice on an acid sulfate soil were investigated in pot experiment. 1. Since aluminum content in the leachate of soil was reduced with increasing the pH and these chemical changes in the leachate were more pronounced by applying wollastonite, aluminum toxicity in flooded paddy rice was overcome by applying wollastonite, or flooding. 2. Poor growth of rice with iron toxicity-like symptoms on the untreated acid sulfate soil may be caused by excess iron and sulfur. Plants applied wollastonite, however, grew normally and did not show any symptoms. Iron and sulfur contents in the plant was reduced by applying wollastonite. 3. Because of the iron content in the both leachate and plant can be lowered by applying wollastonite, iron-toxicity was averted by applying the wollastonite. 4. Application of manganese dioxide in combination with wollastonite did not counteracted iron content in the plant as compared with the wollastonite treatment. 5. The application of wollastonite increased the dry weight of straw and grain yield. Manganese dioxide with wollastonite caused the increase of number of spickelets per panicles and ripened grains as compared with wollastonite. 6. From these results it can be concluded that the major cause of the poor growth of rice on acid sulfate soil is iron toxicity and the Fe-toxicity can be reduced by application of wollastonite.