• Food Science and Preservation
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• v.30 no.1
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• pp.109-121
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• 2023

This study was conducted to evaluate vitamin D intake of Koreans in a total diet study (TDS) and to determine the effect of irradiation on vitamin D synthesis in mushrooms. For analysis, sample were saponified and extracted with hexane, and vitamin D was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on the validation results, the recovery of the National Institute of Standards and Technology (NIST) standard reference sample (SRM) 1849a was 96.7% and the z-score of -1.6 was obtained by the Food Analysis Performance Assessment Scheme (FAPAS) proficiency test (PT) 21115. Vitamin D₂ was not detected in any samples, and the highest level of vitamin D₃ was detected in mackerel and anchovies ranging from 24.2 to 120.2 ㎍/kg. The mean daily intake of vitamin D was 0.99 ㎍/day, as estimated from the vitamin D contents of the analyzed foods and their corresponding intake. The adequate intake (AI) of vitamin D based on the Dietary reference intakes for Koreans provided by the Ministry of Health and Welfare is 5-15 ㎍/day for Koreans aged 6 to 75 years. Compared with this AI, vitamin D intake of Koreans estimated in this study was inadequate. For that, the increased vitamin D content in ultraviolet (UV)/sun light irradiated mushrooms warrants further research to increase vitamin D intake of Koreans through diet.

• Applied Biological Chemistry
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• v.18 no.4
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• pp.194-202
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• 1975

This study was conducted to study the properties of the water-soluble natural chelating agents from garbage compost and activated sewage sludge responsible for Fe chelation, which is closely associated with the effectiveness in correcting iron chlorosis in plant. The water-soluble fraction of these materials was fractionated by menas of Sephadex gel filtration and the fractions of Fe chehates were traced by radioactive $^{59}Fe$. The fractions were examined by ultraviolet and infrared. spectroscopy and stability constants for Fe. The water-soluble fraction from garbage compost was separated by Sephadex G-25 into approximately four fractions. Most of the added $^{59}Fe$ was associated with fraction I, which appeared at the void volume. Further fractionation by Sephadex G-50 indicated that the molecular weight of water-soluble chelating agents is in the approximate range of 5000 to 10,000. The water-soluble fraction from activated sewage sludge gave six fractions by Sephadex G-25. Most of the added $^{59}Fe$ was found in the fraction I,II, and III, The molecular weights of most chelating agents associated with $^{59}Fe$ appeared to be less than 5,000 and those of fraction I that appeared at the void volume was in the range of 5,000 to 1,000. Discrepancy between radio activity count and UV absorption indicated the heterogeneity of the fractions obtained by Sephadex gel filtration. Ultraviolet absorption spectra of all fractions separated by Sephadex G-25 and containing chelating agents showed no differences. Fraction IV and V of sewage extract showed absorption maxima and shifting similar to nucleic acid components suggesting the presence of decomposition products of nucleic acid. Similarity fraction VI contained phenolic type amino acid groups. Fraction I of compost extract contained most of the added $^{59}Fe$ and showed weak but extra definite absorption in the 1230, and $1270cm^{-1}$ region, suggesting that extra oxygen groups in polyphenolic structure were probably involved in Fe chelation. In sewage extract, fraction I,II, and III in which most of the $^{59}Fe$ was found, showed strong definite polypeptide absorption in the region of $1540cm^{-1}$ due to NH deformation and C-N stretching of amide groups in the peptidebond. These extra functional groups in fraction I, II, and III appeared to be associated with Fe chelation. The other fractions, not associated with $^{59}Fe$, still have carboxyl and hydroxyl groups, suggesting that these functional groups in these water extracts may not independently form the Fe chelates. Precipitation of ferric hydroxide precluded measuring the stability constants for Fe-chelates. However, the formation constants for Zn chelates as log K values for compost extract and sewage extract at pH 4.0 from which the strength of chelation with Fe could be presumed, were 8.23, and 9.75, respectively, indicating strong complexation with metals. The chelating capacity of compost extract containing 6.5 g organic matter per liter was 0.82 mM, and that of sewage extract containing 5.3 g per liter was 0. 64 mM.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.311-318
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• 2015

This work investigated the plasma treatment of aqueous bisphenol A (BPA) solution and mineralization pathways. For the effective contact between plasmatic gas and aqueous BPA solution, the plasma was created inside a porous ceramic tube, which was uniformly dispersed into the aqueous solution through micro-pores of the ceramic tube. Effects of the gas flow rate, applied voltage and treatment time on the decomposition of BPA were examined, and analyses using ultraviolet (UV) spectroscopy, ion chromatography and gas chromatography-mass spectrometry were also performed to elucidate mineralization mechanisms. The appropriate gas flow rate was around $1.0L\;min^{-1}$; when the gas flow rate was too high or too low, the BPA decomposition performance at a given electric power decreased. The increase in the voltage improves the BPA decomposition due to the increased electric power, but the energy required to remove BPA was similar, regardless of the voltage. Under the condition of $1.0L\;min^{-1}$ and 20.8 kV, BPA at an initial concentration of $10L\;min^{-1}$ (volume : 1 L) was successfully treated within 30 min. The intermediates produced by the attack of ozone and hydroxyl radicals on BPA were further oxidized to stable compounds such as acetate, formate and oxalate.

• Research in Plant Disease
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• v.18 no.4
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• pp.354-360
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• 2012

This study tested the antifungal compound obtained from a medicinal plant, Dioscorea quinqueloba Thunb., in order to search the possibility of practical application of this product in agriculture through evaluating its activity using the citrus fruits. The extract of D. quinqueloba Thunb., which has the strongest antifungal activity, was selected as a candidate among 101 plant extracts. Based on this examination concerning antifungal activity of the product on Penicillium digitatum in vitro, it was confirmed its effect of mycelial growth inhibition showed over 87% at 0.5 mg/ml concentration. This natural product showed the stability of the substance, as it was not significantly influenced by pH, temperature, or ultraviolet radiation. While citrus fruits were stored at room temperature, P. digitatum was inoculated into them in order to prepare a similar environmental conditions with epidemic occurrence of the mold. As the result of our investigation, the disease preventive effects of the active antifungal substance evidenced a 100% at 0.5 mg/ml. When the phytotoxicity of the selected natural product on citrus at 2 mg/ml was assessed, we noted no toxic effects. Based on the superior preventive effects from this natural product extracted from the plant, it is presumed to be very useful in agricultural applications for the control of green mold, P. digitatum, which has been occurred often the biggest problem in the storage of citrus fruits.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.3
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• pp.263-273
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• 2012

Recent studies have uncovered attractive properties of para-coumaric acid (PCA) as a potential skin hywhitening agent. The purpose of the current study was to examine its UVB-shielding effects. Effects of PCA on the viability of HaCaT cells exposed to UVB were assessed in vitro in comparison with other aromatic amino acid metabolites that have similar UV absorption spectra. For in vivo test, PCA cream (1.5 %) and cream base were topically applied to the dorsal skin of SKH-1 hairless mice and the inflammatory responses due to UVB exposure were monitored by changes in skin color (erythema) and thickness (edema). The cream application-UVB exposure regimen was repeated every other day for a total of 12 sessions. When HaCaT cells were irradiated with UVB, there was a dose-dependent decline in cell viability. The cell viability decline due to UVB exposure (10 mJ $cm^{-2}$) was significantly prevented by 100 ${\mu}M$ PCA, cinnamic acid, urocanic acid, or indole acrylic acid by 39, 27, 39, or 31 %, respectively. Topical application of PCA cream onto the dorsal skin of hairless mice (10 ${\mu}g\;cm^{-2}$) attenuated the changes of color parameters, $L^*$, $a^*$, $b^*$ values, and thickness of the UVB (150 mJ $cm^{-2}$)-exposed skin by 59, 50, 58, and 53 %, respectively. The current study, together with the previous studies that demonstrated the antimelanogenic effects of PCA, suggested that PCA may prevent not only dyspigmentation but also inflammatory reactions in the UVB-exposed skin.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.87-87
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• 2010

Photoelectrochemical (PEC) systems are promising methods of producing H2 gas using solar energy in an aqueous solution. The photoelectrochemical properties of numerous metal oxides have been studied. Among them, the PEC systems based on TiO2 have been extensively studied. However, the drawback of a PEC system with TiO2 is that only ultraviolet (UV) light can be absorbed because of its large band gap (3.2 - 3.4 eV). Two approaches have been introduced in order to use PEC cells in the visible light region. The first method includes doping impurities, such as nitrogen, into TiO2, and this technique has been extensively studied in an attempt to narrow the band gap. In comparison, research on the second method, which includes visible light water splitting in molecular photosystems, has been slow. Mallouk et al. recently developed electrochemical water-splitting cells using the Ru(II) complex as the visible light photosensitizer. the dye-sensitized PEC cell consisted of a dye-sensitized TiO2 layer, a Pt counter electrode, and an aqueous solution between them. Under a visible light (< 3 eV) illumination, only the dye molecule absorbed the light and became excited because TiO2 had the wide band gap. The light absorption of the dye was followed by the transfer of an electron from the excited state (S*) of the dye to the conduction band (CB) of TiO2 and its subsequent transfer to the transparent conducting oxide (TCO). The electrons moved through the wire to the Pt, where the water reduction (or H2 evolution) occurred. The oxidized dye molecules caused the water oxidation because their HOMO level was below the H2O/O2 level. Organic dyes have been developed as metal-free alternatives to the Ru(II) complexes because of their tunable optical and electronic properties and low-cost manufacturing. Recently, organic dye molecules containing multi-branched, multi-anchoring groups have received a great deal of interest. In this work, tri-branched tri-anchoring organic dyes (Dye 2) were designed and applied to visible light water-splitting cells based on dye-sensitized TiO2 electrodes. Dye 2 had a molecular structure containing one donor (D) and three acceptor (A) groups, and each ended with an anchoring functionality. In comparison, mono-anchoring dyes (Dye 1) were also synthesized. The PEC response of the Dye 2-sensitized TiO2 film was much better than the Dye 1-sensitized or unsensitized TiO2 films.

• Environmental Mutagens and Carcinogens
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• v.18 no.2
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• pp.116-122
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• 1998

The present investigation has been performed to elucidate the effect of pretreatment with low dose of ultraviolet radiation (UV), ethyl methansulfonate (EMS), and bleomycin (BLM) on cell survival and lectin-binding glycoconjugates of plasma membrane in HeLa cells treated with mutagen. The percentage of survival of cells pretreated with 1 mM EMS following treatment with 10 mM EMS was higher than that of cells treated with 10 mM EMS alone. Wheat germ agglutinin (WGA) staining intensity of cells pretreated with 1 mM EMS and subsequently treated with 10 mM EMS was stronger than that of cells treated with 10 mM EMS alone. But, succinylated wheat germ agglutinin (sWGA) staining intensity of cells pretreated with 1 mM EMS and subsequently treated with 10 mM EMS was similar to that of cells treated with 10 mM EMS alone. These results suggest that the acquired resistance to EMS is related to the glycoconjugates containing sialic acid of plasma membrane involved in multidrug resistance or adaptive response in HeLa cells.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.2 s.344
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• pp.8-12
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• 2006

We have fabricated ZnO thin film on $Pt/TiO-2/SiO_2/Si$ substrate by the sol-gel method and have investigated the effect of annealing temperature on the structural morphology and optical properties of ZnO thin films. The ZnO thin film annealed at $600^{\circ}C$ exhibits the highest c-axis orientation and its FWHM of X-ray peak is $0.4360^{\circ}C$. In the results of surface morphology investigation of ZnO thin film by using Am it is observed that ZnO thin film annealed at $600^{\circ}C$ exhibits the largest UV (ultraviolet) exciton emission at around 378nm and the smallest visible emission at around 510nm among these of ZnO thin films annealed at various temperatures. It is deduced that the ZnO thim film annealed at $600^{\circ}C$ is formed most stoichiometrically since the visible emission at around 510nm comes from oxygen vacancy or impurities.

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.336-341
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• 2018

In general, the synthesis of poly(3-hexylthiophene)(P3HT)-based block copolymers requires at least a 4-5 step process. To control the molecular weight, molecular weight distribution, and block ratio, the reaction conversion and time should be monitored. In addition, the reaction scale usually limited to several mg to g was difficult to increase due to the limitations of living radical polymerizations. In this study, we synthesized P3HT-b-poly(4-vinylprydine) (P3HT-b-P4VP) with a final product quantity of > 19 g via a 2-step synthetic method with an anionic polymerization. In this method, the molecular weight and molecular weight distribution of P3HT-b-P4VP can be well controlled without monitoring the reaction conversion. We also studied physical properties of P3HT-b-P4VP depending on different solvent systems, which were investigated by UV-vis spectroscopy, atomic force microscopy, and ultraviolet photoelectron spectroscopy.

• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.481-494
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• 2018

The accurate radiative transfer model simulation is essential for an accurate ozone profile retrieval using optimal estimation from backscattered ultraviolet (BUV) measurement. The input parameters of the radiative transfer model are the main factors that determine the model accuracy. In particular, meteorological parameters such as temperature and surface pressure have a direct effect on simulating radiation spectrum as a component for calculating ozone absorption cross section and Rayleigh scattering. Hence, a sensitivity of UV ozone profile retrievals to these parameters has been investigated using radiative transfer model. The surface pressure shows an average error within 100 hPa in the daily / monthly climatological data based on the numerical weather prediction model, and the calculated ozone retrieval error is less than 0.2 DU for each layer. On the other hand, the temperature shows an error of 1-7K depending on the observation station and altitude for the same daily / monthly climatological data, and the calculated ozone retrieval error is about 4 DU for each layer. These results can help to understand the obtained vertical ozone information from satellite. In addition, they are expected to be used effectively in selecting the meteorological input data and establishing the system design direction in the process of applying the algorithm to satellite operation.