• Microbiology and Biotechnology Letters
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• v.8 no.3
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• pp.181-191
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• 1980

For the purpose of studies on the citric acid production, some experiments were carried out with isolated strains. The results obtained were as follows. 1) The optimal culture media of the strain M-80 in surface culture contained 140g of sucrose, 3.0g of (N $H_4$)$_2$S $O_4$, 1.5g of K $H_2$P $O_4$, 0.2g of MgS $O_4$.7$H_2O$, 3.0mg of F $e^{++}$, 1.0mg of Z $n^{++}$, 0.5N HCI to a pH of 5.0 and distilled water to 1.0 liter; and that of the strain M-315 in surface culture contained 140g of sucrose, 2.0g of N $H_4$N $O_3$, 1.0g of K $H_2$P $O_4$, 0.25g of MgS $O_4$. 7$H_2O$, 2.0mg of F $e^{++}$, 2.0mg of Z $n^{++}$, 0.05mg of C $u^{++}$, 0.5N HCI to a pH of 4.5 and distilled water to 1.0 liter. While that of the strain M-315 in submerged culture contained 140g of sucrose, 2.5g of N $H_4$N $O_3$, 1.5g of K $H_2$P $O_4$, 0.3g of MgS $O_4$. 7$H_2O$, 3.0mg of F $e^{++}$, 0.1mg of C $u^{++}$, 0.5N HCI to a pH of 4.5 and distilled water to 1.0 liter. The optimal temperature and size of inoculum were mostly 28-3$0^{\circ}C$, 10$^{7}$ -10$^{8}$ spores/50ml, respectively. 2) Through the course of citric acid production, the growth of strains had nearly been completed, pH value was rapidly decreased below 2.0 and the content of sugar was also reduced, while the accumulation of citric acid in media was remarkably begun in about 3-4 days. The yields of citric acid generally reached the maximum level in 8-10 days in surface or submerged fermentation process. 3) Methanol was effective citric acid production when they were added to fermentation media. In the case of surface culture, by addition of 2％ (strain M-80), 3％ (strain M-315), the yields of citric acid was increased 6.5％, 20.6%, respectively and 5.0% yield was increased by addition of 3% methanol in submerged culture media of the strain M-315. 4) Chromatography analysis of culture broth after fermentation under optimal culture conditions detected that the majority of acid in media was citric acid. 72.1mg/ml, 98.1mg/ml, of citric acid were determined in surface culture media by strains of M-80, M-315, and 59.8 mg/ml of citric acid was contained in the submerged culture media by the strain M-315. strain M-315.

• Korean Journal of Plant Resources
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• v.32 no.1
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• pp.53-62
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• 2019

The purpose of this study was to establish the in vitro propagation system by shoot tip culture of six Hosta species native to Korea (Hosta capitata (Koidz.) Nakai, H. clausa Nakai, H. jonesii M.G.Chung, H. minor (Baker) Nakai, H. venusta F.Maek., and H. yingeri S.B.Jones) for mass proliferation and a new cultivar development. The shoot tips of each Hosta species were cultured on MS medium containing eight combinations of 0.5, 1.0, 2.0, 4.0 mg/L BA with 0.1 mg/L NAA, 0.1, 0.5, 1.0, 2.0 mg/L TDZ with 0.1 mg/L NAA, and without any PGRs (control). They were investigated on callus, somatic embryo, crown bud, differentiation and growth of shoot and root, total fresh weight after 8 weeks of culture. In all six Hosta species, callus and somatic embryo induction rate and multiple shooting rate of the PGRs treatment group were higher than that of the control group. The highest number of differentiated shoots were obtained on medium supplemented with 2.0 ㎎/L TDZ in H. capitata (5.4), 1.0 mg/L TDZ in H. clausa and H. jonesii (3.3 and 5.8, respectively), 0.5 mg/L BA in H. minor (11.1), 1.0 mg/L BA and 0.1 mg/L TDZ in H. venusta (8.1), and 0.5 mg/L TDZ in H. yingeri (9.8). In somatic embryo formation, the PGRs treatment group of H. jonesii and H. yingeri were more effective than the control group, and the effects were relatively less in H. capitata, H. clausa Nakai, H. minor, H. venusta. Crown bud formation of four Hosta species (H.capitata, H. clausa, H. jonesiig, and H. yingeri) were also higher in the PGRs treatment group than in the control group. Crown bud formation of four Hosta species (H.capitata, H. clausa, H. jonesiig, and H. yingeri) were also higher in the PGRs treatment group than in the control group. H. clausa showed no significant effect on callus and shoot differentiation regardless of the type and concentration of cytokinin, but slightly increased in formation of crown bud in TDZ.

• Progress in Superconductivity
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• v.14 no.2
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• pp.116-121
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• 2012

Effect of mixed gas and additional Mg powder in an annealing process of the $MgB_2$ is investigated. Four different type of samples were prepared, each in different annealing environment of Ar, $Ar+4%H_2$, Ar with Mg powder and $Ar+4%H_2$ with Mg powder. Different annealing environment did not affect the electron-phonon interaction which is reflected from the same superconducting transition of 36.6 K for all samples. The reducing effect of hydrogen is clearly depicted from the presence of excess Mg in sample synthesized in $Ar+4%H_2$ gas implying the reduced rate of reaction between Mg and B. This has manifested itself in terms of slightly increased high-field critical current density of the sample. In contrast, the sample synthesized in $Ar+4%H_2$ with Mg powder, has shown overall enhancement in the superconducting properties as presented by higher diamagnetic saturation and critical current density.

• Korean Journal of Metals and Materials
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• v.50 no.10
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• pp.769-774
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• 2012

Mg-x wt% $Fe_2O_3-y$ wt% Ni samples were prepared by reactive mechanical grinding in a planetary ball mill, and their hydrogen-storage properties were investigated and compared. Activations of $Mg-5Fe_2O_3-5Ni$ was completed after one hydriding (under 12 bar $H_2$) - dehydriding (in vacuum) cycle at 593 K. At n = 2, $Mg-5Fe_2O_3-5Ni$ absorbed 3.43 wt% H for 5 min, 3.57 wt% H for 10 min, 3.76 wt% H for 20 min, and 3.98 wt% H for 60 min. Activated $Mg-10Fe_2O_3$ had the highest hydriding rate, absorbing 2.99 wt% H for 2.5 min, 4.86 wt% H for 10 min, and 5.54 wt% H for 60 min at 593 K under 12 bar $H_2$. Activated $Mg-10Fe_2O_3-5Ni$ had the highest dehydriding rate, desorbing 1.31 wt% H for 10 min, 2.91 wt% H for 30 min, and 3.83 wt% H for 60 min at 593 K under 1.0 bar $H_2$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.521-525
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• 2001

Screening tests of different fucoidan fractions from Sporophylls of Undazia pinnatifida, Laminaria religiosa, Hizikia fusiforme and Sagassum fulvellum revealed that the highest biosorptive Pb and Cd uptake fraction was Undaria finnatifida Fr-3.0 prepared by dissolving the precipitated complex (crude fucoidan and cetylpyridinum chloride) with 3.0 M $CaCl_2$ solution, The Pb and Cd uptake by Undaria finnatifida Fr-3.0 was quantitatively evaluated using sorption isotherms and Langmuir sorption model. The Pb and Cd uptake by Undaria finnatifida Fr-3.0 increased with increasing pH values at high equilibrium residual concentration. The highest experimentally observed Pb and Cd uptake value in the sorption isotherm for pH 5.5 were 94 mg/g (at $C_f=164\;mg/L$) and 64 mg/g (at $C_f=197\;mg/L$) respectively, and $q_{max}$ of Pb and Cd calculated by Langmuir sorption model were 178 mg/g and 122 mg/g, respectively. In the low equilibrium concentration range, up to 20 mg/L, the Pb uptake remained unchanged in the presence of Cd, but decreased at higher equilibrium concentration range.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.51-55
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• 2003

To develop environment-friendly biofertilizer solubilizing insoluble phosphates, a bacterium possessing a high ability to solubilize $Ca_{3}(PO_{4})_{2}$) was isolated from the rhizosphere of peas. On the basis of its morphological, cultural, physiological characteristics, and Vitek analysis, this bacterium was identified as Pantoea agglomerans. The optimal medium composition and cultural conditions for the solubilization of insoluble phosphate by P. agglomerans R-38 were 3% of glucose.0.1% of TEX>$NH_{4}NO_{3}$, 0.02% of $MgSO_{4}\cdot\7H_{2}O$, and 0.06% of $CaCl_{2}\cdot\2H_{2}O$ along with initial pH 7.5 at $30^{\circ}C$. The highest soluble phosphate production under optimum condition was 898 mg/L after 5 days of cultivation. The solubilization of insoluble phosphate was associated with a drop in the pH of the culture medium. The strain produced soluble phosphate to the culture broth with the concentrations of 698 mg/L against CaHPO$_4$, 912 mg/L against hydroxyapatite, 28 mg/L against $FePO_{4}\cdot\4H_{2}O$, and 19 mg/L against $AIPO_{4}$, respectively.

• Journal of dental hygiene science
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• v.7 no.1
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• pp.9-12
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• 2007

Streptococcus mutans is the major causative factor in dental caries and has been known to induce dental caries by the process of initial attachment proliferation and acid production. The pH of Streptococcus mutans(S. mutans) media and glucosyltransferase(GTase) activity were determined to evaluate the anticariogenic activity of Dioscorea batatas and Prunella vulgaris hexane fraction. In the experiment of hexane fraction of Dioscorea batatas, the relative growth ratio(RGR) against Streptococcus mutans (S. mutans) was determined as 93% in concentration of 0.125 mg/ml, 100% in 0.25 mg/ml. The hexane fraction of Prunella vulgaris revealed relative growth ratio(RGR) against Streptococcus mutans (S. mutans) as 86% in concentration of 0.25 mg/ml, 100% in 0.5 mg/ml. The relative growth ratio(RGR) against of hexane fraction were determined as 92% in concentration of 0.25 mg/ml, 100% in 0.5 mg/ml. The acidities were pH 7.2 on Dioscorea batatas and 7.0 on Prunella vulgaris in 2.0 mg/ml in contrast to pH 5.6 on Dioscorea batatas and 5.2 on Prunella vulgaris in control. The inhibitory effect to activity revealed 35% on Dioscorea batatas and 25% on Prunella vulgaris in 2.0 mg/ml. The inhibitory effect of Dioscorea batatas was more potent than Prunella vulgaris.

• Progress in Superconductivity and Cryogenics
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• v.22 no.4
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• pp.20-23
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• 2020

Among many variables in processing the high performance MgB2 bulk superconductors, simple and important approach is to optimize the size dependence of the Mg & B raw powders. The present study is dedicated towards the variation in superconducting properties of MgB2 depending upon the various combination of Mg & B powders with the two different particle sizes respectively. From morphological investigation of the MgB2 samples, narrow and long pores are observed when the larger Mg powders are used, whereas it is rather like the oval shapes with the smaller Mg powders. Also, it can be seen that the connectivity of the MgB2 samples is much enhanced with the smaller size of the B powders. Jc-H properties of the MgB2 samples also indicate that the highest Jc can be obtained when using the smaller size of the B powder with the combination of the smaller Mg powders than that of the larger Mg powders. If the cases with the larger B powers, it is more favorable to select the larger Mg powders with the better Jc-H properties considering shorter diffusion length of Mg and more homogeneous mixture between the Mg & B powders.

• Journal of Korean Biological Nursing Science
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• v.7 no.1
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• pp.47-56
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• 2005

nm23-H1 gene expression has been inversely correlated with tumor metastatic potential in certain tumors including melanomas, breast carcinomas, and hepatocellular carcinomas. However, its role with respect to the invasive behavior of central nervous system tumors has scarcely been addressed Because cell motility and invasion plays an essential role in metastatic dissemination, we have studied whether motile human glioma cell(U87MG) transfected with nm23-H1 complementary DNA have any alterations in their ability to migrate and invade. There was no significant changes in the shape and size of the cells following nm23-H1 transfection. The role of nm23-H1 in glioma migration and invasion have been evaluated by in vitro simple scratch technique and brain slice invasion model Basal migration ability of nm23-H1 transfectants cell(U87MG-pEGFP-nm23) were lesser than U87MG. Accordingly, U87MG-pEGFP-nm23 didn't migrate away apparently from the tumors implanted site comparing U87MG in brain slice invasion model. These results suggest that nm23-H1 may play an important role in suppressing the human glioma migration and invasion.

• Resources Recycling
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• v.6 no.4
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• pp.31-37
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• 1997

The Mg-ferrite powders were recovered from acid leaching Mg waste by hydrothermal method. Recovering conditions ofMg-Ferrite were investigated m this system and the powders prepared were characterized, using X-ray analysis, chemicalanalysis, SEM. TEM, and VSM. In this study, pH of solution and the kind of neutralizer wcre important factors on thecharacteristics of the product. The optimum condition of recovering MgPenite was the mole ratio of Fe" : Mg"=2'1, reactiontemperature : ZOWC, reaction time.lhr, at pH=lZ, and Oi partial pressure af 2000 psi. And the powders ~ccovered have amonodispersed and spherelike shapes with the narrow sue distribulion.ow sue distribulion.