• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.131-137
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• 2012

Polyaniline (PANI) and polypyrrole (Ppy) hollow sphere structures with controlled shell thicknesses can be easily synthesized than those of using a layer-by-layer method for cathode active material of lithium-ion batteries. Polystyrene (PS) core was synthesized by emulsion polymerization using an anion surfactant. The shell thicknesses of PANI and Ppy were controlled by amounts of aniline and pyrrole monomers. PS was removed by an organic solution. This structure increased in contact with an electrolyte and a specific capacity in lithium-ion batteries. But polymers have disadvantages such as the difficult control of molecular weights and low densities. These disadvantages were completed by controlled shell thicknesses. The amount of aniline monomer increased from 1.2, 2.4, 3.6, 4.8 to 6.0 mL, and the shell thicknesses were 30.2, 38.0, 42.2, 48.2, and 52.4 nm, respectively. And the amount of pyrrole monomer was 0.6, 1.2, 2.4 and 3.6 mL, the shell thicknesses were 16.0, 22.0, 27.0 and 34.0 nm, respectively. In the cathode materials with controlled shell thicknesses, shell thicknesses of the PANI hollow spheres were 30.2, 42.2, and 52.4 nm, and discharge specific capacities of after 10 cycle were ~18, ~29, and ~62 mAh/g, respectively. The shell thicknesses of the Ppy hollow spheres were 16.0, 22.0, 27.0 and 34.0 nm, and discharge specific capacities of after 15 cycle were ~15, ~36, ~56, and ~77 mAh/g, respectively. Thus, shell thicknesses of PANI and Ppy increased, the specific capacities increased.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.152-159
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• 2008

The purpose of this study was to determine the accurate quantification of vitamin A in infant formula by comparing two different standard stock solutions as well as various sample weights using high performance liquid chromatography. The sources of uncertainty in measurement, such as sample weight, final smaple vloume, and the instrumental results, were identified and used as parameters to determine the combined standard uncertainty based on GUM(guide to the expression of uncertainty in measurement) and the Draft EURACHEM/CITAC Guide. The uncertainty components in measuring were identified as standard weight, purity, molecular weight, dilution of the standard solution, calibration curve, recovery, reproducibility, sample weight, and final sample volume. Each uncertainty component was evaluated for type A and type B and included to calculate the combined uncertainty. The analytical results and combined standard uncertainties of vitamin A according to the two different methods of stock solution preparation were 627 ${\pm}$ 33 ${\mu}$g R.E./100 g for 1,000 mg/L of stock solution, and 627 ${\pm}$ 49 ${\mu}$g R.E./100 g for 100 mg/L of stock solution. The analytical results and combined standard uncertainties of vitamin A according to the various sample weighs were 622 ${\pm}$ 48 ${\mu}$g R.E./100 g, 627 ${\pm}$ 33 ${\mu}$g R.E./100 g, and 491 ${\pm}$ 23 ${\mu}$g R.E./100 g for 1 g, 2 g, and 5 g of sampling, respectively. These data indicate that the preparation method of standard stock solution and the smaple amount were main sources of uncertainty in the analysis results for vitamin A. Preparing 1,000 mg/L of stock solution for standard material sampling rather than 100 mg, and sampling not more than 2 g of infant formula, would be effective for reducing differences in the results as well as uncertainty.

• Journal of Life Science
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• v.29 no.11
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• pp.1173-1178
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• 2019

The purpose of this study was to isolate an agar-degrading marine bacterium and characterize its agarase. Bacterium BK-1, from Gwanganri Beach at Busan, Korea, was isolated on Marine 2216 agar medium and identified as Agarivorans sp. BK-1 by 16S rRNA gene sequencing. The extracellular agarase, characterized after dialysis of culture broth, showed maximum activity at pH 6.0 and $50^{\circ}C$ in 20 mM Tris-HCl buffer. Relative activities at 20, 30, 40, 50, 60, and $70^{\circ}C$ were 67, 93, 97, 100, 58, and 52%, respectively. Relative activities at pH 5, 6, 7, and 8 were 59, 100, 95, and 91%, respectively. More than 90% of the activity remained after a 2 hr exposure to 20, 30, or $40^{\circ}C$; about 60% of the activity remained after a 2 hr exposure to $50^{\circ}C$. Almost all activity was lost after exposure to 60 or $70^{\circ}C$ for 30 min. Zymography revealed three agarases with molecular weights of 110, 90, and 55 kDa. Agarose was degraded to neoagarobiose (46.8%), neoagarotetraose (39.7%), and neoagarohexaose (13.5%), confirming the agarase of Agarivorans sp. BK-1 as a ${\beta}$-agarase. The neoagarooligosaccharides generated by this agarase could be used for moisturizing, bacterial growth inhibition, skin whitening, food treatments, cosmetics, and delaying starch degradation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.2
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• pp.211-219
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• 1989

Tobacco and ginseng plants differed in responses to varied light intensities. Tobacco showed high in CO$_2$ uptake and RuBPCase activity at 1900 ${\mu}$ E m/sup-2/ sec$\^$-1/, being high by 3.7 times and 2.7 times than ginseng respectively. Close positive relationships existed between CO$_2$ uptake and RuBPCase activity in tobacco. However, ginseng showed negative correlation. The activity of glycolate oxidase and malate dehydrogenase in tobacco was high at 1900 ${\mu}$ E m/sup-2/ sec$\^$-1/, but those of ginseng was high at 1000 ${\mu}$ E m/sup-2/ sec$\^$-1/. Nitrate reductase activity of tobacco at 1900 ${\mu}$ E m/sup-2/ sec$\^$-1/ was 2 times higher than that at 500 ${\mu}$ E m/sup-2/ sec$\^$-1/, while that of ginseng was no detected in all plots. The content of protein and chlorophyll in tobacco was 2.2 times and 1.5 times higher than in ginseng at the most efficient light intensity. The ratio of chlorophyll a/b in tobacco was low at 500 ${\mu}$ E m/sup-2/ sec$\^$-1/, while that of ginseng was low at 1000 ${\mu}$ E m/sup-2/ sec$\^$-1/. The relationships between protein and chlorophyll was high positive correlation. However, on 5 days after treatment, ginseng showed negative correlation at 500 ${\mu}$ E m/sup-2/ sec$\^$-1/. Tobacco and ginseng showed different leaf soluble protein patterns on SDS-gel electrophoresis. The molecular weights of two major band were 50 KD and 15 KD in both plants. The major bands in tobacco were thinned at 500 ${\mu}$ E m/sup-2/ sec$\^$-1/, while those in ginseng thinned at 1000 ${\mu}$ E m/sup-2/ sec$\^$-1/ from 15days after treatment. Disappeared band was 45 KD at 500 ${\mu}$ E m/sup-2/ sec$\^$-1/ in tobacco, but that of ginseng was 47 KD at 1000 ${\mu}$ E m/sup-2/ sec$\^$-1/.