• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.438-444
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• 2011

Magnesium is one of the abundant natural resources in the earth crust and seawater, which is directly related to various organisms activities interconnecting with water-rock system. In aqueous system, magnesium is known to predominantly exist in the form of $Mg^{2+}$ ion which is verified in its $E_h-pH$ diagram. When it is at equilibrium in aqueous system, temperature takes an essential role to complete equilibrium states. This study represents the change of the stable region of magnesium ion according to temperature, and how the consequences would affect aquatic organisms. It was revealed that there is a noticeable tendency shrinking the stable region of magnesium ion in a diagram as temperature increases, and as a result, aquatic bio-species presumably have difficulties to absorb the nutrient. Also, it was considered that the water system would be acidified by decreasing alkalinity.

• Clinical and Experimental Reproductive Medicine
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• v.28 no.3
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• pp.199-207
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• 2001

Objective: The present study was undertaken to examine the effects of magnesium ion in the culture medium on the development of mouse fertilized oocytes either before or after pronuclear formation, and to investigate whether the effect of magnesium ion is related with the redistributional change of mitochondria. Methods : Fertilized oocytes obtained from the oviducts of mice at 15 hr after hCG injection before pronuclear formation (pre-PN) or 21 hr after hCG injection after pronuclear formation (post-PN) were used. The embryos were cultured for 3 days with basic T6 medium-magnesium free and various concentrations of magnesium ion, 0.0, 0.5, 1.0, 2.0, 4.0 or 8.0 mM, respectively. After culture, the developmental stages of embryos and the number of nuclei were evaluated. To observe the effects of magnesium ion on the mitochondrial distribution, fertilized oocytes were collected at 21 hr after hCG injection and cultured for 6 hr with various concentration of magnesium ion. As a control, fertilized oocytes with pronuclei at 27 hr after hCG injection were used. Results: The concentration of magnesium ion to accelerate the in vitro development of mouse fertilized oocytes appeared to be at 2.0 mM for the pre-PN and the post-PN stage embryos. In the mitochondrial redistribution patterns, the embryos cultured in 2.0 mM concentration of magnesium ion showed the highest percentage (22.6%) of distinct perinuclear clustering pattern comparing to other experimental group. Conclusion: The effect of magnesium ion may be related to the cytoplasmic redistribution of mitochondria. This relationship seems to connect the developmental competence of preimplantation mouse embryos in vitro. These results can suggest that higher concentration of magnesium ion (2.0 mM) than those of conventional culture medium ($0.2{\sim}1.2\;mM$) is more suitable for in vitro culture of preimplantation mouse embryos.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4696-4703
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• 2011

Tetraazamacrocyclic ion-exchangers, 1,4,8,11-tetraazacyclotetradecane bonded Merrifield peptide resin(TDM), 1,4,8,12-tetraazacyclopentadecane bonded Merrifield peptide resin(TPM) were prepared, and the ion-exchange capacity of these TDM and TPM were characterized. The distribution coefficients in various conc. of NH4Cl for magnesium with ion exchangers were determined by using the batch method. We found the isotope separation factors on new prepared tetraazamacrocyclic ion-exchangers bonded Merrifield peptide resin(TDM, TPM). The isotope separation of magnesium was determined by using of breakthrough method of column chromatography.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.285-286
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• 2006

Magnesium is the lightest of all the structural metals having density of 1.74. It is approximately 2/3 lighter than aluminium, l/4 lighter than titanium alloy and 1/5 lighter than iron. Among the light-weight alloys, magnesium and its alloys show a good possibility for high performance aerospace and automotive applications, however the widespread use of magnesium alloys has been limited mainly by its poor oxidation and corrosion resistance. In this work, corrosion-resistive thin films were prepared onto the magnesium alloy substrate(AZ91D) by environmental friendly coating technique, ion plating method. And their corrosion protection mechanism were analyzed.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.406-412
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• 1994

The ion-exchange properties of $Ca^{2+}$ and $Mg^{2+}$ ions have been studied in ${\delta}-Na_2Si_2O_5$ synthesized from water glass. Results show that optimum temperature for synthesis of ${\delta}-Na_2Si_2O_5$ was $725^{\circ}C$. Ion-exchange isotherms for $Ca^{2+}$ and $Mg^{2+}$ exchange for $Na^+$ in the synthetic ${\delta}-Na_2Si_2O_5$ show that the ion-exchange capacity of magnesium is better than that of calcium, and the ion-exchange of magnesium is less sensitive for temperature than that of calcium. When initial pH of solution is increased between 2 and 6, the ion-exchange capacities of magnesium and calcium decrease a little. However, they are almost constant above pH 6 because of alkali buffer effect of ${\delta}-Na_2Si_2O_5$. In the thermodynamic studies, it was found that Gibbs free energies of reaction of calcium ion-exchange are larger than those of magnesium ion-exchange with inverse order of selectivity. The standard enthalpy and entropy of reaction of calcium ion-exchange are larger than those of magnesium ion-exchange.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.5
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• pp.103-113
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• 1996

The properties of the deposited film depend on the deposition condition and these, in turn depend critically on the morphology and crystal orientation of the films. Therefore, it is important to clarify the nucleation occurrence and growth stage of the morphology and orientation of the film affected by deposition parameters, e.g. the gas pressure and bias voltage etc. In this work, magnesium thin flims were prepared on cold-rolled steel substrates by a thermo-eletron activation ion plating technique. The influence of nitrogen gas pressure and substrate bias voltage on their crystal orientation and morphology of the coated films were investigated by scanning electron microscopy (SEM) and X-ray diffraction, respectively. The diffraction peaks of magnesium film became less sharp and broadened with the increase of nitrogen gas pressure. With an increase in nitrogen gas pressure, flim morphology changed from colum nar to granular structure, and surface crystal grain-size decreased. The morphology of films depended not only on gas pressure but also on bias voltage, i.e., the effect of increasing bias voltage was similar to that of decreasing gas pressure. The effect of crystal orientation and morphology of magnesium films on corrosion behaviors was estimated by measuring anodic polarization curves in deaerated 3%NaCl solution. Magnesium, in general, has not a good corrosion resistance in all environments. However, these magnesium films prepared by changing nitrogen gas pressure showed good corrosion resistance. Among the films, magnesium films which exhibited granular structure had the highest corrosion resistance. The above phenomena can be explained by applying the effects of adsorption, occlusion and ion sputter of nitrogen gas.

• The Korean Journal of Mycology
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• v.21 no.3
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• pp.157-164
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• 1993

The effects of the iron ions on the light-induced mitochondrial $F_1-ATPase$ in Lentinus edodes was studied. This enzyme activity was stimulated by each of the ferric, ferrous and magnesium ion. Especially, the activity of the enzyme by 5.0 mM ferric ion increased up to 107% in comparision with control group(100%). In the presence of magnesium ion, each of ferric and ferrous ion increased the activity of the enzyme, particulary, coexistence of 0.1 mM magnesium and 5.0 mM ferric ion increased the activity up to 270% with magnesium ion dependence. The activity of the enzyme was stimulated up to 268% by 5.0 mM ferric ion in the presence of 0.1 mM magnesium and 0.1 mM ferrous ion. Therefore, the coexistence of ferrous ion did not affect the activity. From the above, we propose that light-induced mitochondrial $F_1-ATPase$ in Lentinus edodes is a $Mg^{2+}{\cdot}Fe^{3+}{\;}F_1-ATPase.$ The optimal pH and temperature for the enzyme were 7.5 and $66^{\circ}C$ respectively.

• Journal of Pharmaceutical Investigation
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• v.14 no.3
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• pp.131-135
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• 1984

The effect of pH and magnesium ion on the hydrolysis of dicyclomine HCl was investigated by comparing the rate constant and activation energy. The hydrolysis of dicyclomine HCl was acid-base catalytic reaction and the most stable range of pH was $3{\sim}5$. The magnesium ion accelerated the hydrolysis of dicyclomine HCl in aqueous solution.

• Journal of the Korean institute of surface engineering
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• v.44 no.6
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• pp.233-238
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• 2011

The friction and wear characteristics of CrN and TiN coatings on SKD61 which is mold material using for extrusion of AZ80 magnesium alloy were investigated. The coatings were deposited by the arc ion-plating method, and the thickness were about $3.59{\mu}m$ and $3.28{\mu}m$, respectively. Reciprocating friction wear tests were conducted by varying pin load and temperature of counter substrate at un-lubricated condition. The pin loads were 11, 15 and 19 kgf, and the substrate temperatures were room temperature and $120^{\circ}C$. CrN coating which has a lower friction coefficient and a smaller adhesive wear with AZ80 magnesium alloy showed better wear resistance than TiN coating.

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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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.