• Journal of Korean Society for Atmospheric Environment
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• v.31 no.5
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• pp.437-448
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• 2015

The purpose of this study is to present the source contribution of the fine particles ($PM_{2.5}$) in Chungju area using the CMB (chemical mass balance) method throughout the four seasons in Korea. The Chungju's annual average level of $PM_{2.5}$ was $48.2{\mu}g/m^3$, which exceeded two times higher than standard air quality. Among these particles, the soluble ionic compounds represent 54.2% of fine particle mass. Additionally, the OC concentration in Chungju stayed similar to other domestic cities, while the EC concentration decreased significantly compared to other domestic/international cities. The concentration of sulfur represented the highest composition (8%) among the fine particle compounds. According to the CMB results, the general trend of the $PM_{2.5}$ mass contributors was the following: secondary aerosols (50.5%: ammonium sulfate 26.5% and ammonium nitrate 24.0%) > gasoline vehicle (18.3%) > biomass burning (11.0%) > industrial boiler (6.0%) > diesel vehicles (4.4%). The contribution of the secondary aerosols was the main cause than others. This impact is assumed to be emitted from air pollutants of urban cities or neighbor countries such as China.

• Journal of Life Science
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• v.25 no.10
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• pp.1169-1175
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• 2015

Although many studies have described the physiological effects of bee products, such as honey, propolis, pollen, and royal jelly, the health benefits of honeycomb remain incompletely characterized. We performed a comparative study of the antioxidant properties of honey and honeycomb extracts using two different solvents (water and 95% ethanol). The results showed that the total phenolic and flavonoid content of the honeycomb extract was higher than that of the honey extract. They also demonstrated that water was more effective than ethanol in extracting total phenols. The in vitro antioxidant properties of the water honeycomb extract were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO^•) radical scavenging assays and ferrous ion chelating and reducing power assays. The antioxidant activity of the honeycomb extract exhibited was higher than that of the honey extract. The 50% effective concentrations (EC₅₀) of the honeycomb extract were 7.3±0.26 mg/ml for scavenging DPPH radicals, 6.1±0.22 mg/ml for scavenging NO^• radicals, 6.9±0.44 mg/ml for chelating ferrous ions, and 8.2±0.11 mg/ml for reducing power. A correlation analysis revealed that the total phenolics and flavonoids of the honeycomb extract were the major contributors to the radical scavenging activity, ferrous ion chelating, and reducing power. The honeycomb extract was effective in protecting biological systems against various oxidative stresses in vitro. This is the first report on the antioxidant properties of honeycomb.

• Biomedical Science Letters
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• v.27 no.4
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• pp.277-282
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• 2021

Hydrocotyle is a genus of prostrate, perennial aquatic or semi-aquatic plants formerly classified in the family Apiaceae, now in the family Araliaceae. Lipoxygenases (LOX) are present in the human body and play an important role in the stimulation of inflammatory reactions. Ethanolic extracts of five Hydrocotyle species (H. ramiflora, H. maritima, H. nepalensis, H. sibthorpioides, and H. yabei) showed inhibition of 23.5~50.6% at 2.0 mg/mL. Their extracts showed LOX inhibition in half maximal effective concentration (EC₅₀) range 15.1~15.7 ㎍/mL. Hyaluronic acid is a glycosaminoglycan, a major component of the extracellular matrix Five extracts of these species inhibited less than 23.0% of Hyaluronidase (HAase) activity at a concentration of 2.0 mg/mL Xanthine oxidase (XO) is a form of xanthine oxidoreductase, a type of enzyme that generates reactive oxygen species. Five Hydrocotyle species were found to have inhibitory activity of XO at 2.0 mg/ml, with 65% having greater than 50% inhibition. H. ramiflora exhibited the highest activity with an inhibition of 80.0%. The results suggested that Lipoxygenases, Hyaluronidase, and Busan 47340, Republic of Korea from five Hydrocotyle species might be multifunctional and prevent the degradation of allergic reactions and inflammation.

• The Plant Pathology Journal
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• v.40 no.3
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• pp.261-271
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• 2024

Sulfur is one of the inorganic elements used by plants to develop and produce phytoalexin to resist certain diseases. This study reported a method for preparing a material for plant disease resistance. Sulfur nanoparticles (SNPs) stabilized in the chitosan-Cu²⁺ (CS-Cu²⁺) complex were synthesized by hydrolysis of Na₂S₂O₃ in an acidic medium. The obtained SNPs/CS-Cu²⁺ complex consisting of 0.32% S, 4% CS, and 0.7% Cu (w/v), contained SNPs with an average size of ~28 nm as measured by transmission electron microscopy images. The X-ray diffraction pattern of the SNPs/CS-Cu²⁺ complex showed that SNPs had orthorhombic crystal structures. Interaction between SNPs and the CS-Cu²⁺ complex was also investigated by ultraviolet-visible. Results in vitro nematicidal effect of materials against Meloidogyne incognita showed that SNPs/CS-Cu²⁺ complex was more effective in killing second-stage juveniles (J2) nematodes and inhibiting egg hatching than that of CS and CS-Cu²⁺ complex. The values of LC₅₀ in killing J2 nematodes and EC₅₀ in inhibiting egg hatching of SNPs/CS-Cu²⁺ complex were 75 and 51 mg/l, respectively. These values were lower than those of CS and the CS-Cu²⁺ complex. The test results on the nematicidal effect against M. incognita on coffee pots showed that the SNPs/CS-Cu²⁺ complex was 100% effective at a concentration of 150 mg/l. Therefore, the SNPs/CS-Cu²⁺ complex could be considered as a biochemical material with potential for agricultural applications to control root-knot nematodes.

• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.58-67
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• 2015

The effects of electrolyte additives, lithium bis(oxalate)borate (LiBOB), fluoroethylene carbonate (FEC), vinylene carbonate (VC), 2-(triphenylphosphoranylidene) succinic anhydride (TPSA), on high-temperature storage properties of $Li(Ni_{1/3}Co_{1/3}Mn_{1/3})O_2$/graphite are investigated with coin-type full cells. The 1 wt.% LiBOB-containing electrolyte showed the highest capacity retention after high temperature ($60^{\circ}C$) storage for 20 days, 86.7%, which is about 5% higher than the reference electrolyte, 1.15M lithium hexafluorophosphate ($LiPF_6$) in ethylene carbonate/ethyl methyl carbonate (EC/EMC, 3/7 by volume). This enhancement is closely related to the formation of semi-carbonate compounds originated from $BOB^-$ anions, thereby resulting in lower SEI thickness and interfacial resistance after storage. In addition, the 1 wt.% LiBOB-containing electrolyte also exhibited better cycle performance at 25 and $60^{\circ}C$ than the reference electrolyte, which indicates that LiBOB is an effective additive for high-temperature performance of $Li(Ni_{1/3}Co_{1/3}Mn_{1/3})O_2$/graphite chemistry.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.207-215
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• 2020

Toxic assessment of antifouling agents (diuron and irgarol) was conducted using the fertilization and the normal embryogenesis rates of the sea urchin, Mesocentrotus nudus. Bioassessment began with male and female reproductive cell induction. White or cream-colored male gametes(sperm) and yellow or orange-colored female gametes (eggs) were acquired and fully washed, separately. Then, the fertilization and normal embryogenesis rates were measured after 10 min and 48 h of exposure to the toxicants, respectively. The fertilization and embryo development rates were greater than 90% in the control, validating the suitability of both endpoints. The normal embryogenesis rates were significantly decreased with increasing concentrations of diuron and irgarol, but no changes in the fertilization rates were observed in concentrations ranging from 0 to 40 mg L^-1. The EC₅₀ values of diuron and irgarol for the normal embryogenesis rates were 20.07 mg L^-1 and 22.45 mg L^-1, respectively. The no observed effect concentrations (NOEC) were <1.25 mg L^-1 and the lowest observed effect concentrations (LOEC) were 1.25 mg L^-1 and 2.5 mg L^-1, respectively. From these results, concentrations of diuron and irgarol over 1.25 mg L^-1 and 2.5 mg L^-1, respectively, can be considered to have toxic effects on invertebrates, including M. nudus. The ecotoxicological bioassay in this study using the noted fertilization and normal embryogenesis rates of M. nudus can be used as baseline data for the continued establishment of environmental quality standards for the effects of antifouling agents(especially diuron and irgarol) in a marine environment.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.518-527
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• 2020

The aim of this study was to define the toxic effects of diuron and irgarol, which are new-antifouling agents, on the fertilization rate and normal embryogenesis rate in the sea urchin, Hemicentrotus pulcherrimus. In addition, the study was intended to confirm the hindrance of development in sea urchins. The fertilization rate of H. pulcherrimus was not decreased by the tested concentrations. However, the normal embryogenesis rate was decreased in a concentration-dependent manner. The 50% effective concentrations (EC₅₀) of normal embryogenesis rate were 7.12 mg L^-1 and 2.31 mg L^-1, respectively. As the embryos developed into pluteus larvae, after 18 h of exposure to diuron and irgarol at EC₅₀, development of the early gastrula stage was delayed, and significant developmental delays were observed after 24 h. After this, continuous developmental delays were observed in the process leading to the early gastrular, gastrular, early pluteus, and pluteus stages. Therefore, the toxic effects of diuron and irgarol on sea urchins were attributed to the delay in the developmental processes in the early life stages. Diuron and irgarol are highly persistent in the environment and have known-well toxic effects on various marine organisms including invertebrates, as shown in this study. Therefore, it is urgent to establish an environmental protection strategy to prevent the pollution of and preserve the marine environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.359-362
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• 2000

The purpose of this study is to research and develop graphene composite for lithium polymer battery. VO(graphene) composite is one of the promising material as a electrode active material for lithium polymer battery(LPB). We investigated AC impedance response and charge/discharge cycling of VO(graphene)/SPE/Li cells. The first discharge capacity of VO(graphene) cathode with 50wt.% V$_2$O$\sub$5/ was 150mAh/g, while that of VO(graphene) cathode with 85wt.% V$_2$O$\sub$5/ was 248mAh/g. The Ah efficiency was above 98% after the 2nd cycle. The discharge capacity of VO(graphene) anode with 3wt.% V$_2$O$\sub$5/ was 718 and 266mAh/g at cycle 1 and 10 at room temperature, respectively. The VO(graphene) anode with 3wt.% V$_2$O$\sub$5/ in PVDF-PAN-PC-EC-LiC1O$_4$ electrolyte showed good capacity with cycling.

• Journal of Ginseng Research
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• v.46 no.4
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• pp.536-542
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• 2022

Background: In aged skin, reactive oxygen species (ROS) induces degradation of the extracellular matrix (ECM), leading to visible aging signs. Collagens in the ECM are cleaved by matrix metalloproteinases (MMPs). Syringaresinol (SYR), isolated from Panax ginseng berry, has various physiological activities, including anti-inflammatory action. However, the anti-aging effects of SYR via antioxidant and autophagy regulation have not been elucidated. Methods: The preventive effect of SYR on skin aging was investigated in human HaCaT keratinocytes in the presence of H₂O₂, and the keratinocyte cells were treated with SYR (0-200 ㎍/mL). mRNA and protein levels of MMP-2 and -9 were determined by real-time PCR and Western blotting, respectively. Radical scavenging activity was researched by 2,2 diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. LC3B level was assessed by Western blotting and confocal microscopy. Results: SYR significantly reduced gene expression and protein levels of MMP-9 and -2 in both H₂O₂-treated and untreated HaCaT cells. SYR did not show cytotoxicity to HaCaT cells. SYR exhibited DPPH and ABTS radical scavenging activities with an EC₅₀ value of 10.77 and 10.35 ㎍/mL, respectively. SYR elevated total levels of endogenous and exogenous LC3B in H₂O₂-stimulated HaCaT cells. 3-Methyladenine (3-MA), an autophagy inhibitor, counteracted the inhibitory effect of SYR on MMP-2 expression. Conclusion: SYR showed antioxidant activity and up-regulated autophagy activity in H₂O₂-stimulated HaCaT cells, lowering the expression of MMP-2 and MMP-9 associated with skin aging. Our results suggest that SYR has potential value as a cosmetic additive for prevention of skin aging.

• Journal of Environmental Health Sciences
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• v.49 no.2
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• pp.89-98
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• 2023

Background: Organophosphorus flame retardants (OPFRs) are a group of chemical substances used in building materials and plastic products to suppress or mitigate the combustion of materials. Although OPFRs are generally used in mixed form, information on their mixture toxicity is quite scarce. Objectives: This study aims to elucidate the toxicity and determine the types of interaction (e.g., synergistic, additive, and antagonistic effect) of OPFRs mixtures. Methods: Nine organophosphorus flame retardants, including TEHP (tris(2-ethylhexyl) phosphate) and TDCPP (tris(1,3-dichloro-2-propyl) phosphate), were selected based on indoor dust measurement data in South Korea. Nine OPFRs were exposed to the luminescent bacteria Aliivibrio fischeri for 30 minutes and the human hepatocyte cell line HepG2 for 48 hours. Chemicals with significant toxicity were only used for mixture toxicity tests in HepG2. In addition, the observed EC_x values were compared with the predicted toxicity values in the CA (concentration addition) prediction model, and the MDR (model deviation ratio) was calculated to determine the type of interaction. Results: Only four chemicals showed significant toxicity in the luminescent bacteria assays. However, EC₅₀ values were derived for seven out of nine OPFRs in the HepG2 assays. In the HepG2 assays, the highest to lowest EC₅₀ were in the order of the molecular weight of the target chemicals. In the further mixture tests, most binary mixtures show additive interactions except for the two combinations that have TPhP (triphenyl phosphate), i.e., TPhP and TDCPP, and TPhP and TBOEP (tris(2-butoxyethyl) phosphate). Conclusions: Our data shows OPFR mixtures usually have additivity; however, more research is needed to find out the reason for the synergistic effect of TPhP. Also, the mixture experimental dataset can be used as a training and validation set for developing the mixture toxicity prediction model as a further step.