• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.397-406
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• 2015

ZnO, II-VI group inorganic compound semi-conductor, has been receiving much attention due to its wide applications in various fields. Since the ZnO has 3.37 eV of a wide band gap and 60 meV of big excitation binding energy, it is well-known material for various uses such the optical property, a semi-conductor, magnetism, antibiosis, photocatalyst, etc. When applied in the field of photocatalyst, many research studies have been actively conducted regarding magnetic materials and the core-shell structure to take on the need of recycling used materials. In this paper, magnetic core-shell ZnFe₂O₄@SiO₂ nanoparticles (NPs) have been successfully synthesized through three steps. In order to analyze the structural characteristics of the synthesized substances, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) were used. The spinel structure of ZnFe₂O₄ and the wurtzite structure of ZnO were confirmed by XRD, and ZnO production rate was confirmed through the analysis of different concentrations of the precursors. The surface change of the synthesized materials was confirmed by SEM. The formation of SiO₂ layer and the synthesis of ZnFe₂O₄@ZnO@SiO₂ NPs were finally verified through the bond of Fe-O, Zn-O and Si-O-Si by FT-IR. The magnetic property of the synthesized materials was analyzed through the vibrating sample magnetometer (VSM). The increase and decrease in the magnetism were respectively confirmed by the results of the formed ZnO and SiO₂ layer. The photocatalysis effect of the synthesized ZnFe₂O₄ @ZnO@SiO₂ NPs was experimented in a black box (dark room) using methylene blue (MB) under UV irradiation.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.172-182
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• 2006

This study was designed to assess molinate fate in the lysimeter by measuring the total radioactivity in the leachate, evolved $^{14}CO_2$, and $^{14}C$-residues in soil and rice plant. The amounts of applied $^{14}C$ in the leachate from the lysimeter for 20 weeks were 1.05% in 2.31 pore volume (217,465 mL) at the first and 0.34% in the second year, respectively. The amount of $^{14}CO_2$ evolved from the lysimeter accounted for 6.47% and 0.03% of applied $^{14}C$ in the first and second year. The $^{14}C$-activities in the soil layer of the lysimeter were distributed 18.0% (1st) and 13.3%(2nd) in the depth of 0 to 10 cm, 4.3 (1st) and 1.1% (2nd) in the depth of 10 to 20 cm. Most of the applied $^{14}C$ was detected in the top 20 cm soil layer. Total $^{14}C$ in rice plants grown at lysimeter were detected 11.46% of applied $^{14}C$. 11.11% in straw, 0.24% in brown rice grain, 0.08% in chaff and 0.03% in ears were distributed in the first year. Consequently, environmental fate of molinate using lysimeter simulating a paddy rice field were investigated 25.24% in soil, 11.64% in rice plant, 1.05% in leachate, 6.74% in evolved $^{14}CO_2$ and 0.02% in volatilized organic chemicals in the first year.

• Journal of Life Science
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• v.25 no.5
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• pp.496-506
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• 2015

This study explored adequate water temperature ranges for maintaining stable water quality in a biofloc- based zero-water exchange culture system. Five experimental tanks with the following temperatures were set up: 10℃, 15℃, 20℃, 25℃, and 30℃. First, a biofloc-based culture system was developed in the experimental tanks; then, the tanks were stocked with goldfish and went without a water exchange for 60 days. Conditions for developing a biofloc-based culture system and stable water quality in low concentrations of inorganic nitrogen compounds at 10℃, 15℃, 20℃, 25℃, and 30℃ were maintained after 17, 26, 43, 68, and 78 days, respectively. Beginning from when the goldfish were stocked in the biofloc-based culture tanks, concentrations of $NH_4{^+}-N$ remained constant and at low levels at 10℃ and 15℃, but they showed a gradual increase at 20℃, 25℃, and 30℃. Concentrations of $NO_2{^-}-N$ and $NO_3{^-}-N$ at 10℃ and 15℃ did not remain at low levels and immediately increased. While $NO_2{^-}-N$ concentrations at above 20℃ remained constant and stable at relatively low levels, $NO_3{^-}-N$ concentrations showed a gradual increase. Conditions of 15℃ and below could not maintain low and stable concentrations of $NO_2{^-}-N$. In the pH range of 4.0 to 6.0, $NH_4{^+}-N$ concentration decreased as the pH rose. However, there was no correlation between pH and $NH_4{^+}-N$ concentration in the pH range of 6.0 to 8.0. These results indicate that pH levels should be kept at pH 6.0 and above to maintain a low and stable concentration of $NH_4{^+}-N$ at above 20℃.

• Food Science and Preservation
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• v.20 no.4
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• pp.524-531
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• 2013

We investigated the quality characteristics of the Korean and American blueberry. There was a similarity between the general composition and sugar content of the Korean and American values. The pH values showed a low of 3.46 in American blueberries to a high of 4.49 in Korean blueberries. The L (lightness), a (redness), and b (yellowness) value scores of the American blueberry were higher than the Korean blueberry. The levels of total phenol content and DPPH radical scavenging abilities were 205 mg%, 93.48% in the Korean blueberry and 182 mg%, 84.32% in the American blueberry, respectively. The free sugar levels showed fructose 2,514 mg%, glucose 2,315 mg%, and sucrose 69 mg% in the Korean blueberry, while the free sugar levels of the American blueberry showed fructose 2,106 mg%, glucose 1,825 mg%. The contents of organic acid were lactic acid and tartaric acid in the Korean blueberry, while the organic acid in the American blueberry contained tartaric acid, succinic acid, oxalic acid, and lactic acid. The Korean blueberry has 12 kinds of free amino acids, while the American blueberry has 9 kinds of free amino acids. Furthermore, the Korean blueberry contains 390 mg% of total amino acids, which was higher than 32% in the American blueberry with 295 mg% of total amino acids. The fatty acid contents of the American blueberry (2,897 mg%) was higher than that of the Korean blueberry (2,783 mg%) as well as in the oleic acid, linoleic acid, and palmitic acid. The mineral contents of all the samples were P>K>Ca>Mg, respectively. Given the above results, the Korean blueberry bioactive chemicals or properties were thought to be somewhat higher than the American blueberry.

• Journal of Applied Biological Chemistry
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• v.65 no.3
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• pp.129-142
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• 2022

Ginseng sprouts, which can be eaten from leaves to roots, has the advantage of not having to use pesticides without being affected by the season by using smart farms. The optimal cultivation timing of sprout ginseng was checked and the nutritional content and antioxidant activity were compared and analyzed. The values of total fatty acids and total minerals were no significant changes during the growth periods. The contents of total amino acids were slightly decreased to 45 days and after increased to 65 days. When the growth period was 65 days, arginine had the highest content of 3309.11 mg/100 g. The total phenolic contents were high at 3.73 GAE mg/g on the 45 days, and the total flavonoid contents were also the highest at 9.04 RE mg/g on the 45 days. The contents of total ginsenoside was not noticeable for the growth periods (29.83 on 25 days→32.77 on 45 days→26.02 mg/g on 65 days). The ginsenoside Rg2 (0.62 mg/g), Re (8.69 mg/g), Rb1 (4.75 mg/g) and Rd (3.47 mg/g) had highest contents on 45 days during growth. The values of phenolic acids and flavonols were gradually increased to 45 days (338.6 and 1277.14 ㎍/g) and then decreased to 65 days. The major compounds of phenolic acids and flavonols were confirmed to benzoic acid (99.03-142.33 ㎍/g) and epigallocatechin (416.03-554.64 ㎍/g), respectively. The values of 2,2-diphenyl-1-picrylhydrazyl (44.27%), 2,4,6-azino-bis (3-ethylbenzothiazoline-6-sulphnoic acid) diammonium salt (75.16%), and hydroxyl (63.29%) radical scavenging activities and ferric reducing/antioxidant power (1.573) showed the highest activity on the 45 days as well as results of total phenolic and total flavonoid contents.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.4
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• pp.177-188
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• 1989

The purpose of this study was to investigate the detoxifying effect on PSP-infested sea mussel, Mytilus edulis, by heating treatment and correlation between the PSP toxicity and the environmental conditions of shellfish culture area such as temperature, pH, salinity, density of Protogonyaulax sp. and concentration of inorganic nutrients such as $NH_4-N,\;NO_3-N,\;NO_2-N\;and\;PO_4-P$. This experiment was carried out at $Suj\u{o}ng$ in Masan, Yangdo in Jindong, $Hach\u{o}ng\;in\;K\u{o}jedo\;and\;Gamch\u{o}n$ bay in Pusan from February to June in $1987\~1989$. It was observed that the detection ratio and toxicity of PSP in sea mussel were different by the year even same collected area. The PSP was often detected when the temperature of sea water about $8.0\~14.0^{\circ}C$. Sometimes the PSP fox of sea mussel was closely related to density of Protogonyaulax sp. at $Gamch\u{o}n$ bay in Pusan from March to April in 1989, but no relationship was observed except above duration during the study period. The concentration of inorganic nutrients effects on the growth of Protogonyaulax sp., then effects of $NO_3-N$ was the strongest among them. When the PSP-infested sea mussel homogenate was heated at various temperature, the PSP toxicity was not changed significantly at below $70^{\circ}C$ for 60 min. but it was proper-tionaly decreased as the heating temperature was increased. For example, when the sea mussel homogenate was heated at $100^{\circ}C,\;121^{\circ}C$ for 10 min., the toxicity was decreased about $67\%\;and\;90\%$, respectively. On the other hand, when shellstock sea mussel contained PSP of $150{\mu}g/100g$ was boiled at $100^{\circ}C$ for 30 min. with tap water, the toxicity was not detected by mouse assay, but that of PSP of $5400{\mu}g/100g$ was reduced to $57{\mu}g/100g$ even after boiling for 120 min.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.3
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• pp.117-124
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• 1979

The present work was carried out to study the fate of applied phosphorus labelled with $^{32}P$ and its availability to plants in soils subjected to different management practices. The results can be summarized as follows (Table 3): 1. The applied phosphorus was transformed into different phosphorus compounds in the soils depending upon the management practices and soil characteristics. 2. In the flooded paddy soil (pH 5.8) added P after one week of incubation was transformed into various fractions, the order of abundance being: Al-P> Ca-P$${\sim_\sim}$$Fe-P> Org.-P. After two weeks the order changed to: Fe-P> Al-P> Ca-P> Org.-P. The amounts of the Fe-P and Al-P fractions were found to increase from the second week of incubation whereas a decrease in Ca-P was noticed with the organic-P remaining constant. The amount of available P decreased from the first to the third week of incubation, but increased thereafter. 3. In the volcanic ash soil a major proportion of the applied phosphorus was found in the Fe-P fraction during the whole experimental period. The interconversions of the $^{32}P$ among the different phosphate fractions was not as evident as in the case of flooded rice soil. The recovery of applied P was low and remained constant throughout the incubation period. 4. In the upland soils relatively more of the applied phosphorus was found in the Ca-P fraction as compared with those of the other soils. As in the flooded paddy soil $^{32}P$ in the Ca-P fraction decreased with increasing incubation time, whereas in the Fe-P fraction it increased with time. The recovery of added phosphate as available P followed different patterns for the cultivated and the uncultivated soils. In the cultivated soils lit was relatively high and remained nearly constant during the whole incubation period. In the uncultivated soil on the other hand, it was high at the earlier time of incubation, but decreased with incubation time.