• Journal of Nutrition and Health
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• 제26권8호
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• pp.925-932
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• 1993

To study the effects of dietary protein and magnesium level on serum lipid contents and enzyme activities, male Sprague-Dawley rats were divided into six groups. Six groups of animals were fed six experimental diets different with protein(8% and 20%) and magnesium levels (Mg-free, 400mg/kg diet and 800mg/kg diet). The serum lipid contents and enzyme activities of rats fed different dietary protein and magnesium levels were examined. Serum triglyceride contents was significantly decreased as the dietary magnesium level was increased. Serum phospholipid contents was significantly higher in magnesium deficient group than those in the other groups. Serum alkaline phosphatase activity was significantly decreased in magnesium dificient group compared with other groups, but serum glutamic oxaloacetic transaminase and glutamic pyruvic transaminase activities was significantly increased in magnesium dificient group than other groups. In conclusion, serum triglyceride contents in low protein level was remarkably decreased as the dietary magnesium level was increased.

• 한국주조공학회지
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• 제31권2호
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• pp.60-65
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• 2011

Molten magnesium alloys and magnesium products are easily oxidized and burned when they are exposed to high temperature for manufacturing process and by accident. In order to solve these problems, CaO addition in magnesium alloys has been developed. The ignition resistance of CaO added Mg-3Al, Mg-6Al, and Mg-9Al Eco-Mg alloys were investigated in comparison with those of magnesium alloys without CaO. The ignition resistance was examined by three methods : DTA, furnace chip ignition test, and torch ignition test. DTA was carried out for obtaining quantitative ignition temperature data with respect to specimen geometry and test environment; the furnace ignition test for burr and chip ignition temperature data; and the torch test for ignition temperature data for manufactured products. The ignition resistance of magnesium alloys under all conditions greatly increased by CaO addition.

• 한국세라믹학회지
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• 제20권4호
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• pp.305-314
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• 1983

In order to enhance the rate of th nitridation and to give the high density of reaction-bonded silicon nitride MgO powder as nitriding aid were added to silicon powders and the mixture was pressed isostatically into compacts which were nitrided in the furnace of 1, 35$0^{\circ}C$ where 95% $N_2$-5% $H_2$ gases were flowing. As the other nitriding aid $Mg(NO_3)_2 6H_2O$ was selected, A slip made of magnesium nitrate solution and fine silicon particles was spray-dried and then decomposed at 30$0^{\circ}C$. Magnesium oxide-coated silicon powders were formed into compacts prior to the nitridation on the same condition as the former. Magnesium nitrate (MgO, produced from the decomposition of magnesium nitrate) was more effective for the formation of the $\beta$-phase in the initial stage of the nitridation probably due to the easy formation of $MgO-SiO_2$-metal oxide eutectic melt. It has been confirmed that forsterite was formed as a result of the reaction between MgO and $SiO_2$ film of silicon surface. It was considered that MgO produced from magnesium nitrate may be finer more reactive and more uniformly distributed on the surface of silicon particles than original MgO. The higher the forming pressure was the more the $\beta$-phase was formed.

• Korean Chemical Engineering Research
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• 제58권1호
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• pp.84-91
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• 2020

염기성 폴리올 및 식용유 정제에 사용하는 합성 규산마그네슘의 효율성은 정제능력과 여과속도를 통해 평가되며, 규산마그네슘의 입도 및 표면적에 따라 영향을 받는다. 본 연구에서는 합성변수인 반응온도, 주입속도, 주입순서(Si, Mg), Mg/Si의 반응몰비가 규산마그네슘의 입도에 미치는 영향을 조사하였다. 합성된 규산마그네슘은 합성공정, 분쇄공정, 정제공정으로 비교 분석되었다. 합성공정에서 반응 온도와 주입 속도는 규산마그네슘의 평균입도 변화에 영향을 주지않는 반면, Mg/Si의 반응몰비와 주입 순서는 평균입도 변화에 주된 요인으로 작용하였다. 합성 후 규산마그네슘의 평균입도는 반응몰비가 0.125에서 0.500로 증가할 때 Mg 주입 시 약 54.4 ㎛에서 63.1 ㎛로 약 8.7 ㎛ 증가하였고, Si 주입 시 47.3 ㎛에서 52.1 ㎛로 약 4.8 ㎛ 증가하였다. 주입 순서 별 평균입도를 비교해보면 Mg 주입 시 59.1 ㎛, Si 주입 시 48.4 ㎛로 약 10.7 ㎛의 평균입도 차이를 보였으며 Mg을 주입하는 조건에서 약 2배 빠른 수세여과속도가 관찰되었다. 즉, 입도가 증가함에 따라 여과 시간이 단축되고 수세여과속도 증가로 생산성 향상에 기여할 수 있었다. 여과 후 분리된 cake형태의 규산마그네슘은 건조과정을 통해 단단한 고형체가 되고 분쇄공정을 통해 분말형태의 흡착제로 사용된다. 건조된 규산마그네슘의 물리적 강도가 감소함에 따라 분말의 평균입도가 감소하고, 이 강도는 반응몰비에 영향을 받는 것을 확인하였다. Mg주입 시 Mg/Si의 반응몰비가 증가함에 따라 규산마그네슘의 물리적 강도가 감소하여 분쇄 후 평균입도가 합성 후 평균입도에 비해 약 40% 감소하는 것을 관찰하였다. 이러한 강도감소는 평균입도 감소와 분쇄 후 미분량의 증가로 정제능력의 향상을 가져왔지만 정제여과속도 감소를 가져왔다. Mg 주입 시 반응몰비가 0.125에서 0.5로 증가할 동안 정제능력은 약 1.3 배가 증가하였으나 정제여과속도는 약 1.5 배가 감소하였다. 따라서 규산마그네슘의 생산성 향상을 위해서는 Mg/Si의 반응몰비를 증가시켜야 하지만, 폴리올의 정제여과속도를 증가시키기 위해선 반응몰비를 감소시켜야 한다. 규산마그네슘의 합성변수 중 주입순서와 Mg/Si의 반응몰비는 합성 후 평균입도와 분쇄 후 평균입도 및 미분량 변화에 영향을 주는 주요인자로 생산성 및 정제능력을 결정짓는 중요한 합성변수이다.

• 한국산학기술학회논문지
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• 제14권4호
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• pp.2049-2054
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• 2013

최근 수산화마그네슘은 비독성, 비부식성 및 열적 안정성 같은 우수한 특성에 의해 다양한 분야에 적용된다. 본 연구는 황산마그네슘과 염화마그네슘 그리고 질산마그네슘을 전구체로 하고, 수산화나트륨과 암모니아수를 알카리원으로 하여 상온에서 침전법을 통해 플라워 그리고 플레이크 형의 수산화마그네슘을 합성하였다. 전구체의 종류 및 합성 변수에 따른 수산화마그네슘의 형태와 크기 영향 확인하였다. 수산화마그네슘의 형상은 마그네슘전구체와 알칼리원에 의존한다. 생성된 플라워형 입자의 평균 크기는 대략 $1{\mu}m$ 그리고 플레이크형의 입자는 20 ~ 50 nm의 크기를 갖는 것을 확인하였다. 합성된 수산화마그네슘의 특성은 XRD, FE-SEM, FT-IR, EDS, PSA 그리고 TG를 통해 확인하였다.

• 동력기계공학회지
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• 제18권4호
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• pp.66-71
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• 2014

In this study, effect of heat treatment on the microstructure and damping capacity of hot rolled magnesium alloys was investigated. The microstructure of hot rolled magnesium consisted of dendrite structure and $Mg_{17}Al_{12}$ compounds precipitated along the grain boundry. The dendrite structure was dissipated and $Mg_{17}Al_{12}$ compounds was decomposed by annealing treatment, and then they dissolved in ${\alpha}-Mg$. With an increasing the annealing temperature and time, damping capacity was slowly increased by the growth of grain size and decreasing of defects induced by hot rolling. Two kinds of magnesium alloys AZ 31 and AZ 61 after annealing showed no difference in damping capacity.

• 대한수의학회지
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• 제41권3호
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• pp.311-317
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• 2001

In this work we have investigated the physiological effects of $MgCl_2$ in isolated atrium, papillary muscle, perfused heart and anesthesized guinea pig, The addition or infusion of $MgCl_2$ (0~20 mM or mg/kg) to perfused hearts and to anesthesized guinea pigs induced a marked and dose-dependent negative chronotropic effect. The sinoatrial node automaticity could also be reduced by $MgCl_2$. The addition of $MgCl_2$to isolated atria and to papillary muscles induced a marked and dose-dependent negative inotropic effect. The threshold voltage could be increased by $MgCl_2$in papillary muscle. Increasing $MgCl_2$ shortened the action potential duration (APD) in dose-dependent manner at 30% ($APD_{30}$) and 90% repolarization ($APD_{90}$) measured with conventional microelectrode technique in papillary muscle. In anesthesized guinea pig, the magnesium infusion resulted in a dose-dependent drop in blood pressure. These results suggested that magnesium is closely associated with cardiac physiological condition and exerts antiarrhythmic activities.

• Carbon letters
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• 제14권4호
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• pp.206-209
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• 2013

Nanocomposites comprised of graphene oxide (GO) nanosheets and magnesium oxide (MgO) nanoparticles were synthesized by a sol-gel process. The synthesized samples were studied by X-ray powder diffraction, atomic force microscopy, transmission electron microscopy, and energy-dispersive X-ray analysis. The results show that the MgO nanoparticles, with an average diameter of 70 nm, are decorated uniformly on the surface of the GOs. By controlling the concentration of the MgO precursors and reaction cycles, it was possible to control the loading density and the size of the resulting MgO particles. Because the MgO particles are robustly anchored on the GO structure, the MgO/GOs nanocomposites will have future applications in the fields of adsorption and chemical sensing.

• Bulletin of the Korean Chemical Society
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• 제22권6호
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• pp.570-574
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• 2001

Magnesium isotope separation was investigated by chemical ion exchange with the 1-aza-12-crown-4 bonded Merrifield peptide resin using an elution chromatographic technique. The capacity of the novel azacrown ion exchanger was 1.0 meq/g dry resin. The heavier isotopes of magnesium were enriched in the resin phase, while the lighter isotopes were enriched in the solution phase. The single stage separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assys. The separation factors of $^{24}Mg^{2+}$-$^{25}Mg^{2+}$, $^{24}Mg^{2+}$-$^{26}Mg^{2+}$, and $^{25}Mg^{2+}$-$^{26}Mg^{2+}$ were 1.008, 1.019, and 1.006, respectively.

• 한국가스학회지
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• 제16권6호
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• pp.1-6
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• 2012

Mg-Al합금 분진의 마그네슘 성분 비율이 분진폭발특성에 미치는 영향을 알기 위하여 Siwek 20 L 구형 분진폭발시험장치를 사용하여 농도를 변화시키면서 실험적으로 조사하였다. 이를 위하여 체적평균입경이 $151{\sim}160{\mu}m$의 Mg-Al합금 분진을 사용하였다. 그 결과 Mg-Al합금에서의 Mg성분의 증가는 폭발하한농도의 감소와 최대폭발압력의 증가로 나타났다. 또한 Mg-Al합금의 최대폭발압력과 최대폭발압력상승속도는 주로 분진 농도에 의존하였다. 그러나 Mg-Al (40:60 wt%), Mg-Al (50:50 wt%) 및 Mg-Al (60:40 wt%)의 폭발지수(Kst)에 있어서, 마그네슘 성분의 증가에 따라서 폭발지수가 증가함을 알 수 있었다.