• 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 Ceramic Society
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• v.37 no.10
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• pp.981-986
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• 2000

Er(NO$_3$)$_3$.5$H_2O$, Mn($CH_3$$CO_2$)$_2$.4$H_2O$를 출발원료로 사용하여 졸-겔법으로 제조한 ErMnO$_3$박막의 열처리 온도 및 기판 배향성에 따른 박막 배향성과 누설 전류 특성에 관하여 연구하였다. ErMnO$_3$박막은 75$0^{\circ}C$ 이하의 온도에서 1시간 열처리 시비정질상태였으나, 78$0^{\circ}C$ 이상의 온도에서 hexagonal pahse인 ErMnO$_3$로 결정화되었다. 열처리 온도가 증가할수록 기판 배향성과 무관하게 모든 방향으로 결정이 성장함을 알 수 있었다. 결정화 정도와 결정 성장 축에 따라 누설 전류 값이 변화함을 알 수 있었고, 80$0^{\circ}C$에서 열처리한 시편에서는 누설 전류 변화가 비선형적인 경향으로 증가하였으며, $10^{-5}$ A/$ extrm{cm}^2$ 이하로 유지되었다.

• Journal of the Korean Magnetics Society
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• v.9 no.3
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• pp.131-135
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• 1999

The electronic structures and properties of layered perovskite $LaSrMnO_4$ and $SR^2MnO_4$ have been determined using the local-density full potential Imearized augmented plane wave method. The total energy calculations show that the antiterromagnetic state has lower energy than the ferromagnetic state in $LaSrMnO_4$. The jahn-Teller distortion of Mn-O octahedron produces the energy gap and the $3z^2-r^2$ orbital ordering, which stabilizes 2 dimensional antiferromagnetis state.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.29.1-29.1
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• 2011

The selective catalytic reduction (SCR) of $MnO_x$ with $NH_3$ is an effective method for the removal of $MnO_x$ from stationary system. The typical catalyst for this method is $V_2O_5-WO_3(MoO_3)/TiO_2$, caused by the high activity and stability. However, This catalyst is active within $300{\sim}400^{\circ}C$ and occurs the pore plugging from the deposition of ammonium sulfate salts on the catalysts surface. It needs to locate the SCR unit after the desulfurizer and electrostatic precipitator without reheating of the flue gas as well as deposition of dust on the catalyst. The manganese oxides supported on titania catalysts have attracted interest because of its high SCR activity at low temperature. The catalytic activity of $MnO_x/TiO_2$ SCR catalyst with different manganese precursors have investigated for low-temperature SCR in terms of structural, morphological, and physico-chemical analyses. The $MnO_x/TiO_2$ were prepared from three different precursors such as manganese nitrate, manganese acetate (II), and manganese acetate (III) by the sol-gel method and then it calcinated at $500^{\circ}C$ for 2 hr. The structural analysis was carried out to identify the phase transition and the change intensity of catalytic activity by various manganese precursors was analyzed by FT-IR and Raman spectroscopy. These different precursors also led to various surface Mn concentrations indicated by SEM. The Mn acetate (III) tends to be more suppressive the crystalline phase (rutile), and it has not only smaller particle size, but also better distributed than the others. It was confirmed that the catalytic activity of MA (III)-$MnO_x/TiO_2$ was the highest among them.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.172-180
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• 2012

The $LiMn_2O_4$ cathodes for lithium ion battery were synthesized from various precursors of manganese oxides and manganese hydroxides. As the first step, nanosized precursors such as ${\alpha}-MnO_2$ (nano-sticks), ${\beta}-MnO_2$ (nano-rods), $Mn_3O_4$ (nano-octahedra), amorphous $MnO_2$(nano-spheres), and $Mn(OH)_2$ (nano-plates) were prepared by a hydrothermal or a precipitation method. Spinel $LiMn_2O_4$ with various sizes and shapes were finally synthesized by a solid-state reaction method from the manganese precursors and LiOH. Nano-sized (500 nm) octahedron $LiMn_2O_4$ showed high capacities of 107 mAh $g^{-1}$ and 99 mAh $g^{-1}$ at 1 C- and 50 C-rate, respectively. Three dimensional octahedral crystallites exhibit superior electrochemical characteristics to the other one-dimensional and two-dimensional shaped $LiMn_2O_4$ nanoparticles. After 500 consecutive charge discharge battery cycles at 10 C-rate with the nano-octahedron $LiMn_2O_4$ cathode, the capacity retention of 95% was observed, which is far better than any other morphologies studied in this work.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.133-137
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• 1994

Infrared radiator of Cordierite system were manufactured using Cordierite(2Mgo$.$2Al$_2$O$_3$$.$5SiO$_2$) and Clay 30wt% as main materials and addition of MnO$_2$ from 0. 1 to 2 5wt% of Dry pressing and slip casting The effects of MnO$_2$ additives on the thermal properties of infrared radiator of Cordierite system. The more the thermal expansion could be lowered the more the amount (wt%) of additives MnO$_2$is increased in the below 4.5$\mu\textrm{m}$. The high efficiency Infrared radiator of Cordierite system using dry pressing method when the amount of additives MnO$_2$is 2.0 wt%

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.442-445
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• 2001

In this study, microstructural and dielectric properties of P $b_{0.83}$(L $a_{0.2}$C $e_{0.8}$)$_{0.08}$Ti $O_3$PCT ceramics as a function of Mn $O_2$ addition were investigated for 30MHz ceramic resonator application. Grain size was gradually increased according to the increase of Mn $O_2$ addition amount and showed the highest value of 1.502${\mu}{\textrm}{m}$ at the 0.9wt% Mn $O_2$. Moreover, density showed the highest value of 7.582 g/$\textrm{cm}^2$ at the 0.7wt% Mn $O_2$. All the composition ceramics, curie temperature was nearly constant around 33$0^{\circ}C$.EX>.>.>.

• Journal of the Korean Ceramic Society
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• v.28 no.1
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• pp.79-85
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• 1991

The effects of MnO2 on the microstructure and dielectric properties of Pb(Fe1/2Nb1/2)O3 ceramics prepared by KCl-NaCl molten salt synthesis(MSS) method have been investigated. As the amount of MnO2 increased up to 0.25wt%, the density increased and the grain size decreased, while above 0.25wt%, the density decreased with the grain growth. Dielectric constant increased with increasing the amount of MnO2, and dielectric loss decreased up to 0.25wt% and then increased. This is due to the compensation effect by the substitution of Mn4+ to Fe3+ and the appearance of the second phase.

• Journal of Environmental Science International
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• v.18 no.4
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• pp.445-450
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• 2009

In this study, the fundamental experiments were performed for catalytic oxidation of NO (50 ppm) on $MnO_2$ in the presence of ozone. The experiments were carried out at various catalytic temperatures ($30-120^{\circ}C$) and ozone concentrations (50-150 ppm) to investigate the behavior of NO oxidation. The honeycomb type $MnO_2$ catalyst was rectangular with a cell density of 300 cells per square inch. Due to $O_3$ injection, NO reacted with $O_3$ to form $NO_2$, which was adsorbed at the $MnO_2$ surface. The excessive ozone was decomposed to $O^*$ onto the $MnO_2$ catalyst bed, and then that $O^*$ was reacted with $NO_2$ to form $NO_3^-$. It was found that the optimal $O_3$/NO ratio for catalytic oxidation of NO on $MnO_2$ was 2.0, and the NO removal efficiency on $MnO_2$ was 83% at $30^{\circ}C$. As a result, NO was converted mainly to $NO_3^-$.

• Journal of Environmental Science International
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• v.13 no.6
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• pp.537-542
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• 2004

$V_{2}O_{5}/TiO_{2}$ catalysts promoted with Mn were prepared and tested for selective catalytic reduction of NOx in $NH_3.$ The effects of promoter content, degree of catalyst loading were investigated for NOx activity while changing temperatures, mole ratio, space velocity and $O_2$ concentration. Among the various $V-{2}O_{5}$ catalysts having different metal loadings, $V-{2}O_{5}$(1 wt.%) catalyst showed the highest activity(98%) under wide temperature range of $200-250^{\circ}C.$ When the $V-{2}O_{5}$ catalyst was further modified with 5 wt.% Mn as a promoter, the highest activity(90-47%) was obtained over the low temperature windows of $100-200^{\circ}C.$ From Mn-$V_{2}O_{5}/TiO_{2}$, it was found that by addition of 5 wt.% Mn on $V_{2}O_{5}/TiO_{2}$ catalyst, reduction activity of catalyst was improved, which resulted in the increase of catalytic activity and NOx reduction. According to the results, NOx removal decreased for 10%, but the reaction temperature down to $100^{\circ}C.$