• 한국표면공학회지
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• 제25권1호
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• pp.1-7
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• 1992

The formation of manganese ferrite has been performed to investigate some properties according to the variation of compositions, pH, current density by electrolysis. It has been found that the amount of oxidized weight of anode were increased with increasing current density. The amount of oxidized weight of anode were most in pH 10. As the result of X-ray diffraction Mn Fe₂O₄ crystal composition in pH13. When the particles of Mn/sub x/ Fe/sub 3-x/O₄ were heated at 300℃, it has been shown typical Mn Fe₂O₄(JCPDS Card No. 10-319) in X=1 composition. As the result of SEM observation, the size of MnFe₂O₄ particles were about 0.1㎛, the shape of particles were spherical type. According to the above mentioned experimental condition, 0.1-0.5㎛ sub-micron particles of manganese ferrite were formed from the wasted manganese dry cell, through washing → reduction → electrloysis.

• 광물과 암석
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• 제34권4호
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• pp.241-253
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• 2021

유라시아 대륙 주변부 북극해의 천해에서도 태평양이나 인도양의 심해저에서와 같이 많은 망가니즈단괴가 발견되고 있지만, 이에 관한 자세한 연구는 많이 수행되고 있지 않다. 아라온호의 북극해 탐사를 통하여 동시베리아해에서 채취한 망가니즈단괴는 Mn/Fe 비가 매우 높아 Mn 자원으로서의 가능성이 매우 크다. 이번 연구에서는 북극 동시베리아해에서 산출되는 망가니즈단괴 중 약 7%를 차지하는 비구형 단괴를 외부형태에 따라 구분하고, 크기와 무게, 내부조직을 관찰하였으며, X선회절분석 그래프의 피크 면적비를 이용한 산화망가니즈광물의 반정량 분석과 지화학분석을 실시하여, 그 결과를 구형 단괴와 비교하였다. 비구형 망가니즈단괴는 외부형태에 따라 5가지로 구분되며, 타원체형, 판상형과 불규칙형이 대부분을 차지하며, 장경과 무게는 비례하는 경향이 있다. 비구형 단괴는 모두 핵을 가지며, 핵 성분은 이질 퇴적물이 주를 이룬다. 산화망 가니즈광물의 평균 함량은 버네사이트, 부서라이트, 토도로카이트 순으로 감소하며, 함량비는 외부형태, 내부조직이나 핵 성분과는 상관관계가 없지만, 단괴의 내부에서 외부로 갈수록 토도로카이트와 부서라이트는 감소하고, 버네사이트가 증가하는 경향이 있다. 북극해의 다른 천해는 물론 태평양이나 인도양의 심해저의 단괴에 비하여 Mn 함량이 많고, Mn/Fe 비가 높다. 비구형 단괴는 구형 단괴에 비하여 크기가 크고 무겁고, Mn 함량이 적고 Mn/Fe 비는 낮지만, 광물조성이나 내부조직에서는 큰 차이가 없다. 동시베리아해에서 채취된 모든 망간단괴는 Mn/Fe 비가 5 이상으로 높으므로 대부분 속성작용에 의하여 형성된 것으로 여겨진다.

• 대한의생명과학회지
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• 제24권4호
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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 Electrochemical Science and Technology
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• 제2권1호
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• pp.1-7
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• 2011

Nanocomposites of reduced graphene oxide and manganese (II,III) oxide can be synthesized by the freeze-drying process of the mixed colloidal suspension of graphene oxide and manganese oxide, and the subsequent heat-treatment. The calcined reduced graphene oxide-manganese (II,III) oxide nanocomposites are X-ray amorphous, suggesting the formation of homogeneous and disordered mixture without any phase separation. The reduction of graphene oxide to reduced graphene oxide upon the heat-treatment is evidenced by Fourier-transformed infrared spectroscopy. Field emission-scanning electronic microscopy and energy dispersive spectrometry clearly demonstrate the formation of porous structure by the house-of-cards type stacking of reduced graphene oxide nanosheets and the homogeneous distribution of manganese ions in the nanocomposites. According to Mn K-edge X-ray absorption spectroscopy, manganese ions in the calcined nanocomposites are stabilized in octahedral symmetry with mixed Mn oxidation state of Mn(II)/Mn(III). The present reduced graphene oxide-manganese oxide nanocomposites show characteristic pseudocapacitance behavior superior to the pristine manganese oxide, suggesting their applicability as electrode material for supercapacitors.

• 상하수도학회지
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• 제32권2호
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• pp.145-152
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• 2018

This study is focused on manganese (Mn(II)) removal by ozonation in surface water. Instant ozone demand for the water was 0.5 mg/L in the study. When 0.5 mg/L of Mn(II) is existed in water, the optimum ozone concentration was 1.25 mg/L with reaction time 10 minutes to meet the drinking water regulation. The ozone concentration to meet the drinking water regulation was much higher than the stoichiometric concentration. The reaction of soluble manganese removal was so fast that the reaction time does not affect the removal dramatically. When Mn(II) is existed with Fe, the removal of Mn(II) was not affected by Fe ion. However As(V) is existed as co-ion the removal of Mn(II) was decreased by 10%. Adding ozone to surface water has limited effect to remove dissolved organic matter. When ozone is used as oxidant to remove Mn(II) in the water, the existing co-ion should be evaluated to determine optimum concentration.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1067-1072
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• 2014

In this study, we report a new approach for $Mn_3O_4$-graphene nanocomposite by ex situ method. This nanocomposite shows two-dimensional aggregation of nanoparticle, and doping effect by decorated manganese oxide ($Mn_3O_4$), as well. The graphene film was made through micromechanical cleavage of graphite on the $SiO_2/Si$ wafer. Manganese oxide ($Mn_3O_4$) nanoparticle with uniform cubic shape and size (about $5.47{\pm}0.61$ nm sized) was synthesized through the thermal decomposition of manganese(II) acetate, in the presence of oleic acid and oleylamine. The nanocomposite was obtained by self-assembly of nanoparticles on graphene film, using hydrophobic interaction. After heat treatment, the decorated nanoparticles have island structure, with one-layer thickness by two-dimensional aggregations of particles, to minimize the surface potential of each particle. The doping effect of $Mn_3O_4$ nanoparticle was investigated with Raman spectra. Given the upshift in positions of G and 2D in raman peaks, we suggest that $Mn_3O_4$ nanoparticles induce p-doping of graphene film.

• Journal of Electrochemical Science and Technology
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• 제2권3호
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• pp.180-185
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• 2011

The layered lithium-manganese oxide ($Li_2MnO_3$) as a cathode material of lithium ion secondary batteries was prepared and characterized the physico-chemical and electrochemical properties. The morphological and structural changes of MnO(OH) and $Li_2MnO_3$ are closely connected to the changes of electrochemical properties. The crystallinity of $Li_2MnO_3$ is enhanced as the annealing temperature increase, but its capacity is reduced due to the easier structural changes of less crystalline $Li_2MnO_3$ than highly crystalline one. Moreover, the addition of buffer material such as MnO(OH) into cathode causes to reduce the morphological and structural changes of layered $Li_2MnO_3$ and increase the discharge capacity and cycleability.

• Applied Biological Chemistry
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• 제5권
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• pp.43-47
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• 1964

근년(近年) 우리나라의 과수생육(果樹生育)을 해(害)치는 Bark Necrosis의 원인(原因)을 구명(究明)하기 위한 엽(葉) 및 토양분석(土壤分析)의 결과(結果)는 다음과 같다. 망강은 본병유인(本病誘因)의 가장 중요(重要)한 인자(因子)의 하나이며 1962년(年) 필자(筆者)에 의(依)하여 얻어진 결과(結果)와 동일(同一)하다. 이병상(罹病狀)은 엽중(葉中) Mn 904 ppm에서 발생(發生)하였으며 평균(平均) 이병엽(罹病葉)의 Mn 함량(含量)은 건전엽(健全葉)(외관상(外觀上))의 4배(倍)이다. 이상(以上) 기술(記述)한 바와 같이 본(本) Bark necrosis는 Mn 과다흡수(過多吸收)에서오는 Mn-toxicity이며 Berg가 말한 "Internal Bark necrosis"이다. 본(本) Bark necrosis를 방지(防止)하기 위하여서는 토양(土壤) pH를 높이거나 혹은 다른 방법(方法)으로 과수(果樹)의 Mn 흡수(吸收)를 감소(減少) 시켜야 한다.

• Journal of Nutrition and Health
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• 제41권3호
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• pp.206-215
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• 2008

The purpose of this study was to investigate the effect of manganese (Mn) supplementation on bone status and calcium balance in ovariectomized rats according to the calcium intake levels. Total of 50 Sprague Dawley female rats (6 weeks) were divided into 5 groups and bred for 12 weeks: sham operated control group (SACa), OVX Ca deficiency group (OLCa) with Ca deficiency diet (0.1% Ca modified AIN-93N diet), OVX Ca deficiency & Mn supplement group (OLCaMn), OVX adequate Ca group (OACa; 0.5% Ca AIN-93N diet) and OVX adequate Ca & Mn supplement group (OACaMn). BMD (bone mineral density) of the femur was increased by Mn supplementation in OVX adequate Ca group. However, BMDs of spine, femur and tibia were lowered in OLCa compared to the OLCaMn group. Bone strength of tibia in OLCaMn group was significantly lower than OLCa group. Serum ALP (alkaline phosphatase) and CTx (C-telopeptide of collagen cross-links) levels were significantly higher in ovariectomized rats than those in the sham group, but they were not changed by Mn supplementation. Ca retention rate and Ca absorption rate did not differ among the experimental groups. Urinary Ca excretion was increased by Mn supplementation in Ca deficiency rats. In summary, Mn supplementation resulted in positive effects on bone mineral density ovariectomized rats with which intake adequate Ca. However, Mn supplementation on Ca deficiency ovariectomized rats resulted in decrement of BMO and bone strength by increasing Ca excretion. Therefore, it is encouraged to consider calcium intake levels in supplementation of manganese in order to prevent postmenopausal osteoporosis and to keep bone healthy. (KoreanJNutr2008; 41(3): 206~215)

• Korean Chemical Engineering Research
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• 제51권4호
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• pp.460-464
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• 2013

본 연구에서는 $LiMn_2O_4$ 제조에서 Mn 원료로 사용되는 CMD를 seed 첨가법을 사용하여 제조하고자 하였으며, Seed의 열처리 온도가 CMD 합성에 미치는 영향을 고찰하고, 그로부터 제조되는 $LiMn_2O_4$의 전기화학적 특성을 평가하고자 하였다. 제조한 시료의 물성평가는 X-선 회절 분석법(XRD), 주사전자현미경(SEM)을 통하여 실시하였다. 그 결과, $MnCO_3$를 $300^{\circ}C$ 이상의 온도에서 열처리하여 seed로 사용할 경우 ${\gamma}-MnO_2$ 상의 CMD가 얻어졌으며, 그 CMD를 LMO 제조에 사용할 경우 전기화학적 특성이 비교적 우수한 LMO가 얻어졌다.