• Applied Biological Chemistry
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• v.25 no.3
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• pp.135-141
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• 1982

Two rice cultivars, Jinju and Iri 348, were used to compare the changes in the contents of some organic metabolites and ions and in some enzyme levels under water-and salt-stressed conditions. The water loss and proline accumulation under water and salt stresses were accelerated more in the salt-sensitive cultivar Iri 348 than in the salt-tolerant Jinju. The contents of crude protein, total free amino acids, proline and polyphenols increased under water-or salt-stressed rice, but that of reducing sugar increased under water stress only. The water-and salt-stresses induced the high ratio of low molecular organic solutes to crude protein in Jinju but not in Iri 348. The ratio of total free amino acids to crude protein increased under the stressed conditions was likely due to high protease activity. The contents of $Na^+$ and $Cl^-$ were higher in Iri 348 than in Jinju. Iri 348 had higher values of $Na^+/Ca^{2+}$ and monovalent/divalent of cations, but lower of $K^+/Na^+$ than Jinju Rice. The further studies should emphasize to set the correlations between these ratios and tolerance to water and salt stresses among rice cultivars.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.421-428
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• 1996

The occurrence, optical property, chemical composition, crystal structure and formation environments of the phillipsite within deep-sea manganese nodules were systematically investigated in this study. Phillipsite in manganese nodules occurs in nucleus of nodules along with consolidated bottom sediments, weathered volcanic debris, and interstitial grains in the each layer of manganese encrusts. Phillipsite is predominantly pseudomorphs of volcanic shards, and occurs as white to pale yellow in color lath-shaped and equant crystals. These show aggregations of prismatic, blocky, and bladed of 2 to $20{\mu}m$ long, and 2 to $5{\mu}m$ thick. The simplified average chemical formula of phillipsite is $({Ca_{0.1}Mg_{0.3}Na_{1.1}K_{1.5}})_3{(Fe_{0.3}Al_{4.2}Si_{11.8})O_{32}{\cdot}10H_2O}$ with a very siliceous and alkalic. The $Si/(Al+Fe^{+3})$ ratio is 2.37 to 2.78 and alkalis greatly exceed the divalent exchangeable cations, and Na/K ratio is 0.59 to 0.81. The phillipsite is monoclinic ($P2_l/m$) with the unit-cell parameters, $a=10.005{\AA}$, $b=14.129{\AA}$, $c=8.686{\AA}$, ${\beta}=124.35^{\circ}$, and $V=1013.6{\AA}^3$. Phillipsites in manganese nodules formed apparently authigenically at a temperature less than $10^{\circ}C$, and they crystallized at a pressure of less than 0.7 kb, and pH of about 8 in deep-sea environments.

• Journal of Life Science
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• v.14 no.4
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• pp.636-643
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• 2004

D-Xylose isomerase produced by Lactococcus sp. JK-8, isolated from kimchi, was purified 17-fold of homogeneity, and its physicochemical properties were determined. Although the N-terminal amino acid sequence of D-xylose isomerase was analysed to Ala-Tyr-Phe-Asn-Asp-Ile-Ala-Pro-Ile-Lys, it was not similar to that of Lactobacillus enzyme. The molecular weight of the purified enzyme was estimated to be 180 kDa by gel filtration, 45 kDa by SDS-PAGE and the enzyme was homotetramer. The optimum pH of the enzyme was around 7 and stable between pH 6 and 8. The optimum reaction temperature was 7$0^{\circ}C$ and stable up to 7$0^{\circ}C$ in the presence of 1 mM $Mn^{2+}$. Like other D-xylose isomerases, this enzyme required divalent cation, such as $Mg^{2+}$, $Co^{2+}$, or $Mn^{2+}$ for the activity and thermostability. $Mn^{2+}$was the best activator. Substrate specificity studies showed that this enzyme was highly active on D-xylose. The enzyme had an isoelectric point of 4.8, and fm values for D-xylose was 5.9 mM.

• 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 $Mn_3Ga$.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1286-1293
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• 1998

${SO_4}^{2-}$ ions present in industrial waste water if combined with other metal ions in the water can cause serious scale problem in a transporting pipe. In this study therefore ${SO_4}^{2-}$ ions in an acidic solution have been removed by using surface active glasses. Glasses with various compositions of $SiO_2-Na_2O-B_2O_3-RO$ (R=Mg, Ca, Sr, Ba) system were reacted in a ${SO_4}^{2-}$ ion-containing solution with various pHs ranging from 1 to 4 for various time the reacted glass surfaces were analyzed by XRD and SEM and all ions in the reacted solution were also measured ${SO_4}^{2-}$ ions in the solution were combined with divalent ions leached out of glass and precipitated on the glass surface as sulfate crystals. In this was the surface ion could be removed from the acidic solution. The sulfate ion removal capacity is closely related to the solubility product con-stants of the newly formed sulfate crystals. Almost no sulfate crystal was formed on the MgO-containing glass while sulfate crystals were easily formed on the glass containing either SrO or BaO This indicates that those glasses have strong removal efficiency of ${SO_4}^{2-}$ ions from the solution.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.520-525
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• 1998

The optical properties with chemical composition change in BaO- MgO-$AI_2O_3$, system activated by divalent Eu ion were investigated under 254nm ultraviolet(UV) and 147nm vacuum ultraviolet(VUV). These phosphors emitted a blue light at a dominant wavelength of $\lambda$=445nm under UV and VUV irradiations. It was found that the brightness of $BaMgAI_{14}O_{23}$ phosphor increased with Eu concentration up to 10% under UV but it showed a maximum emitting intensity at 5% Eu for VUV. The emitting intensity of blue color of $BaMgAl_{10}O_{l7}$ phosphor was higher than that of $BaMgAI_{14}O_{23}$for both excitation. A further improvement in brightness was obtained for $Ba_{o.9}Ca_{0.1}MaAl_{14}O_{23}$ and $Ba_{0.9}Sr_{0.1}MgAl_{10}O_{17}$ phosphor synthesized by the substition of $Ba^{+2}$ ion with O.lmole of $Ca^{+2}$ or $Sr^{+2}$ ions in $BaMgAl_{IO}O_{17}$: Eu phosphor.

• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.29-42
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• 1998

$Mg^{2+}$ is one of the most abundant divalent cations in mammalian body(0.2~1.0mM) and the important physiological roles are : first, the cofactor of many enzyme activities, second, the regulator of glycolysis and DNA synthesis, third, the important role of bioenergetics by regulating of phosphorylation, fourth, the influence of cardiac metabolism and function. In this work we have investigated the regulation of the $Mg^{2+}$ induced by ${\alpha}_1-adrenoceptor$ stimulation in perfused guinea pig hearts and isolated myocytes. The $Mg^{2+}$ content of the perfusate or the supernatant was measured by atomic absorbance spectrophotometry. The elimination of $Mg^{2+}$ in the medium increased the force of contraction of right ventricular papillary muscles, and the left ventricular pressure. Phenylephrine also enhanced the force of contraction in the presence of $Mg^{2+}-free$ medium. ${\alpha}_1-Agonists$ such as phenylephrine and methoxamine were found to induce $Mg^{2+}$ efflux in both perfused hearts and myocytes. These effects were blocked by prazosin, an ${\alpha}_1-adrenoceptor$ antagonist. The $Mg^{2+}$ influx could also be induced by phenylephrine and R59022, a diacylglycerol kinase inhibitor. In the presence of protein kinase C(PKC) inhibitors, phenylephrine produced an increase in $Mg^{2+}$ efflux from perfused hearts. Furthermore, $Mg^{2+}$ efflux by phenylephrine was amplified by phorbol 12-myristate 13-acetate(PMA). This enhancement of $Mg^{2+}$ efflux by PMA was blocked by prazosin in perfused hearts. By contrast, the $Mg^{2+}$ influx could be induced by verapamil, nifedipine, ryanodine in perfused hearts, but not in myocytes. $W^7$, a $Ca^{2+}$/calmodulin antagonist, completely blocked the phenylephrine-induced $Mg^{2+}$ efflux in perfused hearts. In conclusion, $Mg^{2+}$ is responsible for the cardiac activity associated with ${\alpha}_1-adrenoceptor$ stimulation. The mobilization of $Mg^{2+}$ is decreased or increased by ${\alpha}_1-adrenoceptor$ stimulation in guinea pig hearts. These responses may be related specifically to the respective pathways of signal transduction. A decrease in $Mg^{2+}$ efflux by ${\alpha}_1-adrenoceptor$ stimulation in hearts can be through PKC dependent and intracellular $Ca^{2+}$ levels.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.235-242
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• 2010

Froth flotation using the residual water in the end of flotation process has been performed through controlling of pH. IEP (isoelectric point) of molybdenite and quartz in distilled water was below pH 3 and pH 2.7, respectively and the stabilized range was pH 5~10. In case of a suspension in reusing water, zeta potential of molybdenite decreased to below -10 mV or less at over pH 4 due to residual flocculants. As result of pH control, flotation efficiency in the alkaline conditions was deteriorated by flocculation, resulting from expanded polymer chain, ion bridge of the divalent metal cations ($Ca^{2+}$), and hydrophobic interactions between the nonpolar site of polymer/the hydrophobic areas of the particle surfaces. However, the weak acid conditions (pH 5.5~6) improved the efficiency of flotation as hydrogen ions neutralize polymer chains and then weakened its function. In cleans after rougher flotation, the Mo grade of 52.7% and recovery of 90.1% could be successfully obtained under the conditions of 20 g/t kerosene, 50 g/t AF65, 300 g/t $Na_2SiO_3$, pH 5.5 and 2 cleaning times. Hence, we developed a technique which can continuously supply waste water filtered from tailings into the grinding-rougher-cleaning processes.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.577-582
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• 2004

The azacrown compounds, 1,4-dioxa-7,10,13-triazacyclopentadecane-N,N',N''-triacetic acid, $N-ac_3[15]aneN_3O_2(II_a)$ and 1,4-dioxa-7,10,13-triazacyclopentadecane-N,N',N''-tripropioc acid, $N-pr_3[15]aneN_3O_2(II_b)$ were synthesized by modified methods. Potentiometry was used to determine the protonation constant of the $N-ac_3[15]aneN_3O_2\;and\;N-pr_3[15]aneN_3O_2$. The stability constants of complexes of the trivalent metal ions of $Ce^{3+},\;Eu^{3+},Gd^{3+},and\;Yb^{3+}$ and divalent metal ions of $Co^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Zn^{2+}$ with the ligands $N-ac_3[15]aneN_3O_2\;and\;N-pr_3[15]aneN_3O_2$ have been determined at $25{\pm}0.1^{\circ}C$ in 0.1 M $NaClO_4$ solution by potentiometric methods. The metal ion affinities of the two triazamacrocyclic ligands with three pendant acetate or propionate groups are compared to those obtained for the similar ligands, 1,7-dioxa-4,10,13-triazacyclopentadecane-N,N',N''-triacetic acid, and 1,7-dioxa-4,10,13- triazacyclopentadecane-N,N',N''-tripropioc acid. The trends in stability of complexes for different metal ions due to changes in the nitrogen position of the donor atoms of the ligand are discussed.

• Progress in Medical Physics
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• v.15 no.4
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• pp.220-227
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• 2004

In N-type $Ca^{2＋}$ channels, the mechanism of inactivation - decline of inward current during a depolarizing voltage step- is still controversial between voltage-dependent inactivation and $Ca^{2＋}$ -dependent inactivation. In the previous paper we demonstrated that fast component of inactivation of N-type calcium channels does not involve classic $Ca^{2＋}$ -dependent mechanism and the slowly inactivating component could result from a $Ca^{2＋}$ -dependent process. However, there should be signal transduction pathway which enhances inactivation no matter what the inactivation mechanism is. We have investigated the effect of phosphorylation on calcium channels of rat sympathetic neurons. Intracellular dialysis with the phosphatase inhibitors okadaic acid markedly enhanced the inactivation. The rapidly inactivating component is N-type calcium current, which is blocked by $\omega$-conotoxin GVIA. Staurosporine, a nonselective protein kinase inhibitor, prevented the action of okadaic acid, suggesting that protein phosphorylation is involved. More specifically lavendustin C, inhibitor of CaM kinase II, prevented the action of okadaic acid, suggesting that calmodulin dependent pathway is involved in inactivation process. It is not certain to this point whether phosphorylation process is inactivation itself. Molecular biological research regarding binding site should be followed to address the question of how the divalent cation binding site is related to phoshorylation process.