• Title/Summary/Keyword: MN

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Effect of Fe, Mn Content on the Castability in Al-9wt%Si-Mg System Alloys for High Elongation (고신율 금형주조용 Al-9wt%Si-Mg계 합금의 주조특성에 미치는 Fe, Mn함량의 영향)

  • Kim, Heon-Joo;Jeong, Chang-Yeol
    • Journal of Korea Foundry Society
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    • v.33 no.6
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    • pp.233-241
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    • 2013
  • Effect of Fe and Mn contents on the castability of Al-9wt%Si-xMg-yFe-zMn alloy has been studied. The alloy was composed of ${\alpha}$-Al phase, Al+eutectic Si phase, ${\beta}$-Al5FeSi compound and chinese script ${\alpha}$-$Al_{15}(Mn,Fe)_3Si_2$ compound. ${\beta}$-$Al_5FeSi$ and ${\alpha}$-$Al_{15}(Mn,Fe)_3Si_2$ compounds assumed to effect the fluidity and shrinkage behaviors of the alloy during solidification due to the crystallization of ${\alpha}$-$Al_{15}(Fe,Mn)_3Si_2$ and ${\beta}$-$Al_5FeSi$ compounds above eutectic temperature. As Fe and Mn contents of Al-9wt%Si-0.3wt%Mg system alloy increased from 0.15wt% to 0.6wt% and from 0.3wt% to 0.7wt%, fluidity of the alloy decreased by 5.7% and 3.3%, respectively. And as Mg content of Al-9wt%Si-0.45wt%Fe-0.5wt%Mn system alloy increased from 0.3wt% to 0.4wt%, fluidity of the alloy decreased by 8.6%. When Fe content of the alloy increased from 0.15wt% to 0.6wt%, macro shrinkage ratio decreased from 6.1% to 4.1%, and micro shrinkage ratio increased from 0.04% to 0.24%. Similarly, Mn content of the alloy increased from 0.3wt% to 0.7wt%, macro shrinkage ratio decreased from 6.0% to 4.5% and micro shrinkage ratio increased from 0.12% to 0.18%. Judging from the castability of the alloy, Al-9wt%Si-0.3wt%Mg alloy with low content of Fe and Mn, 0.1wt% Fe and 0.3wt% Mn, is recommendable.

Photoluminescence Properties of Novel $Mg_{2}SnO_{4}:Mn$ Phosphor (새로운 $Mg_{2}SnO_{4}:Mn$ 형광체의 광 발광 특성)

  • Kim, Kyung-Nam;Jung, Ha-Kyun;Park, Hee-Dong;Kim, Do-Jin
    • Journal of the Korean Ceramic Society
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    • v.38 no.9
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    • pp.817-821
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    • 2001
  • A new $Mg_{2-x}MN_xSnO_4$ phosphor with an inverse spinel structure was synthesized by the solid-state reaction technique. The photoluminescence properties of the $Mg_2SnO_4$:Mn phosphors were investigated under 147nm -vacuum ultraviolet ray excitation. The Mn-doped $Mg_2SnO_4$ phosphor exhibited high emission intensity with the spectrum centered at 500nm wavelength. It was explained that the green emission in $Mg_2SnO_4$:Mn phosphor has originated from energy transfer from $^4T_1$ to $^6A_1$ of $Mn^{2+}$ ion at tetrahedral site of the spinel structure. The $Mn^{2+}$ ion concentration exhibiting the maximum emission intensity under the excitation of 147nm-vacuum ultraviolet ray was 0.25mol%. And the decay time of the phosphor was shorter than 10ms.

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Electrochemical Properties of LiMnO2-organic Composite Cathodes with High Capacity for Lithium Ion Polymer Battery (리튬 이온 폴리머 전지용 고용량 LiMnO2-organic Composite 정극의 전기화학적 특성)

  • 김종욱;조영재;구할본
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.2
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    • pp.162-168
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    • 2002
  • The purpose of this study is to research and develop LiMnO$_2$-organic and Li$_{0.3}$MnO$_{2}$-organic composite with high energy density for Lithium ion polymer battery. This paper describes cyclic voltammetry, impedance sepctroscopy, electrochemical properties of LiMnO$_2$-organic and Li$_{0.3}$MnO$_{2}$-organic composite with polymer electrolyte as a function of a mixed ratio. The first discharge capacity of LiMnO$_2$-PAn with 3 wt.% PAn was 83mHA/g, while that of Li$_{0.3}$MnO$_{2}$-PPy composite was 136 mAh/g. The Ah efficiency was above 98% after the 2nd cycle. The LiMnO$_2$-PAn with DMcT 2 wt.% and Li$_{0.3}$MnO$_{2}$-PPy composites cathode with 5wt. PPy in PVDF-PC-EC-LiClO$_4$ electrolyte showed good capaity with cycling. The discharge capacity of LiMnO$_2$-PAn with wt.% DMcT was 80 and 130 mAh/g at 1st and 12th cycle, respectively. The capacity of LiMnO$_2$-PAn composite with 2 wt.% DMcT was higher than that of LiMnO$_2$-PAn composite.mposite.

A Study on the exchange anisotropy and the giant magnetoresistance of Mn-Ir/Ni-Fe/buffer/Si with various buffer layers (Mn-Ir/Ni-Fe/buffer/Si 다층박막에서 하지층에 따른 교환이방성 및 거대자기저항에 대한 연구)

  • 윤성용;노재철;전동민;박준혁;서수정;이확주
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.5
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    • pp.486-492
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    • 1999
  • The purpose of this research was to find out what is the dominant factor determining the $H_{ex}$ and the $H_C$ of Mn-Ir/Ni-Fe multilayers with different buffer layers. Regardless of (111) texture of Mn-Ir layer, all samples showed over the $H_{ex}$ of 155 Oe. We found out the $H_{ex}$ and the $H_C$ of Mn-Ir/Ni-Fe multilayers depend on interface morphology and grain size of Mn-Ir layer at the interface between Mn-Ir and Ni-Fe layers. The dependence of magnetroesistance ratio and coupling field on the thickness of ferromagnetic layer, thickness of Cu layer and different buffer layers have been studied. Maximum magnetoresistance ratio appeared for the sample Ta(5 nm)/Mn-Ir(10 nm)/Ni-Fe(7.5 nm)/Cu(2 nm)/Ni-Fe(6 nm)/Ta(5 nm)/Si. Magnetoresistance ratio may be related to grain of ferromagnetic layer. Coupling field may be related to the roughness and the grain size of ferromagnetic layer in the spin-valve multilayers.

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The Extraction of Manganese from the Medium-Low Carbon Ferromanganese dust with Nitric acid and Charcoal (페로망간제조 분진에서 질산과 활성탄에 의한 망간의 침출)

  • 이계승;김형석;송영준;신강호;김윤채;조동성
    • Resources Recycling
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    • v.9 no.4
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    • pp.44-49
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    • 2000
  • Among dusts which were generated in AOD process producing a medium-low carbon ferromanganese, the dust collected in bag filter contained manganese about 63% and its phase was $Mn_3$$O_4$. the maximum extraction of Mn by nitric acid is about 67% because of remaining amorphous $MnO_2$. Therefore this research investigated reducibility of the activated charcoal in Mn extraction from the dust. Addition of charcoal over 10% of pulp density made possible Mn extraction of 90% at $70^{\circ}C$, 0.5N $HNO_3$. To convert $Mn_3$$O_4$ to MnO by reducing roasting, the minimum mixture ratio of activated charcoal was 5% in $750^{\circ}C$, 1 hour. Extraction of Mn from the reduced dust was over 99% with nitric acid at $25^{\circ}C$, 6N $HNO_3$, pulp density 150 g/l§.

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Protective Effect of Celastrus orbiculatus Thunb Extract on Cultured Neuroglial Cells Damaged by Manganese Dioxide, a Parkinsonism Inducer (파킨슨유발제인 이산화망간으로 손상된 배양 대뇌 신경아교세포에 대한 노박덩굴 추출물의 보호)

  • Seo, Young-Mi
    • 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.

Relationships Between Organic Carbon and $COD_{Mn}$ in a Deep Reservoir, Lake Soyang, Korea (소양호에서 유기탄소와 $COD_{Mn}$과의 상관관계)

  • Choi, Kwang-soon;Kim, Bom-chul;Kim, Hyung-Bong;Sa, Seung-Hwan
    • Korean Journal of Ecology and Environment
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    • v.33 no.4 s.92
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    • pp.328-335
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    • 2000
  • Seasonal and vertical variations of organic carbon and chemical oxygen demand (COD$_{Mn}$ were investigated to estimate a suitability of COD$_{Mn}$ methods as an index of the quantity of organic matter in Lake Soyang. Organic matter in the lake may be composed matters resistant to oxidation by COD$_{Mn}$ method, especially in de데 layers. Rations of COD$_{Mn}$ to TOC varied with season and depth layer in Lake Soyang. In the inflowing river, the ratios after summer monsoon were very low and significantly different compared with other seasons (p<0.0001 between after summer monsoon and other seasons by unpaired sample t-test). At the dam site the ratio was low in the deep layer. The ratios in deep layer were significantly different compared with those of upper and middle layers (p<0.0001 by paired sample t-test). In Lake Soyang COD$_{Mn}$ yielded only 40$ of TOC and the oxidation rate of COD$_{Mn}$ varied largely with season and depth. These results implied that the COD$_{Mn}$ does not seem to be an index or organic matter in lakes.

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Low Temperature Selective Catalytic Reduction of NO with $NH_3$ over Mn/$CeO_2$ and Mn/$ZrO_2$ (Mn/$CeO_2$와 Mn/$ZrO_2$ 촉매 상에서 $NH_3$를 사용한 NO의 선택적 촉매 산화 반응)

  • Ko, Jeong Huy;Park, Sung Hoon;Jeon, Jong-Ki;Sohn, Jung Min;Lee, See-Hoon;Park, Young-Kwon
    • Applied Chemistry for Engineering
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    • v.23 no.1
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    • pp.105-111
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    • 2012
  • Manganese (Mn) catalysts were generated using $CeO_2$ and $ZrO_2$supports synthesized by the supercritical hydrothermal method and two different Mn precursors, aimed at an application for a low-temperature selective catalytic reduction process. Manganese acetate (MA) and manganese nitrate (MA) were used as Mn precursors. Effects of the kind and the concentration of the Mn precursor used for catalyst generation on the NOx removal efficiency were investigated. The characteristics of the generated catalysts were analyzed using $N_2$ adsorption-desorption, thermo-gravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. De-NOx experiments were carried out to measure NOx removal efficiencies of the catalysts. NOx removal efficiencies of the catalysts generated using MA were superior to those of the catalysts generated using MN at every temperature tested. Analyses of the catalyst characteristics indicated that the higher NOx removal efficiencies of the MA-derived catalysts stemmed from the higher oxygen mobility and the stronger interaction with support material of $Mn_2O_3$ produced from MA than those of $MnO_2$ produced from MN.

Soft X-ray Synchrotron-Radiation Spectroscopy Study of Half-metallic Mn3Ga Heusler Alloy (반쪽 금속 호이슬러 화합물 Mn3Ga의 연 X선 방사광 분광 연구)

  • Seong, Seungho;Lee, Eunsook;Kim, Hyun Woo;Kim, D.H.;Kang, J.S.;Venkatesan, M.;Coey, J.M.D.
    • Journal of the Korean Magnetics Society
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    • v.26 no.6
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    • pp.185-189
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    • 2016
  • By employing photoemission spectroscopy (PES) and soft X-ray absorption spectroscopy (XAS), the electronic structure of the candidate half-metallic antiferromagnet of $Mn_3Ga$ Heusler compound has been investigated. We have studied two ball-milled $Mn_3Ga$ powder samples, one after annealing and the other without annealing, respectively. Based on the Mn 2p XAS study, we have found that Mn ions are nearly divalent in $Mn_3Ga$ and that the Mn ions having the locally octahedral symmetry and those having the locally tetrahedral symmetry are both present in $Mn_3Ga$. We have found relatively good agreement between the measured valence-band PES spectrum of $Mn_3Ga$ and the calculated density of states, which is in agreement with the half-metallic electronic structure of $Mn_3Ga$.

Electrochemical Properties of Using MnO2-HCS Composite for Supercapacitor (MnO2-HCS 복합체를 이용한 슈퍼커패시터의 전기화학적 특성)

  • Jin, En Mei;Jeong, Sang Mun
    • Clean Technology
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    • v.24 no.3
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    • pp.183-189
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    • 2018
  • Hollow carbon spheres (HCS) and carbon spheres (CS) were prepared by a hydrothermal reaction and they were introduced as a substrate for the deposition of $MnO_2$ nanoparticles. The $MnO_2$ nanoparticles were deposited on the carbon surface by a chemical redox deposition method. After deposition, the $MnO_2$ nanoparticles were uniformally distributed on the carbon surface in a slit-shape, and sparse $MnO_2$ slits appeared on the HCS surface. The $MnO_2-HCS$ showed an initial specific capacitance of $164.1F\;g^{-1}$ at scan rate of $20mv\;s^{-1}$, and after 1,000 cycles, the specific capacitance was maintained to $141.3F\;g^{-1}$. The capacity retention of $MnO_2-HCS$ and $MnO_2-CS$ were calculated to 86% and 78% in the cycle performance test up to 1,000 cycles, respectively. $MnO_2-HCS$ showed a good cycle stability due to the mesoporous hollow structure which can cause a faster diffusion of the electrolyte and can easily adsorb and desorb $Na^+$ ions on the surface of the electrode.