• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.371-378
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• 2019

Graphene nanoplatelet (GnP)/reused phenolic foam (re-PF)/wood composite boards were fabricated with different GnP content as 5, 10 and 20 w/w% to investigate the effect of GnP on thermal- and flame retardant properties of wood-based composite boards. The thermal- and flame retardant properties of fabricated composite boards were investigated by thermogravimetric analysis (TGA) and limiting oxygen index (LOI), respectively. The thermal stability of the composite boards increased proportionally with respect to the amount of GnP, and the char yield of these boards increased up to 22% compared to that of the pure wood board. The LOI values of composite boards were about 4.8~7.8% higher than those of using pure wood boards. It was also confirmed that the flame retardant properties of composite boards were remarkably improved by the addition of re-PF and GnP. These results were because of the fact that the re-PF and GnP with a high thermal stability delayed the initial thermal degradation temperature of composite boards and made their char layers denser and thicker which led the overall combustion delay effect of the composite board. Especially, GnP as a carbon-based material, facilitated the char layer formation and increased remarkedly the char yield, which showed higher effect on flame retardant properties than those of the re-PF.

• Journal of Life Science
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• v.31 no.1
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• pp.59-65
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• 2021

Prunus mume Sieb. et Zucc is distributed throughout Asia and has traditionally been used as medicine and food. P. mume is known to contain large amounts of various organic acids, minerals, and phenol components. To date, the trend of P. mume research has focused only on the effects of antioxidant, anticancer and antibacterial, with only a few studies have focused on angiogenesis. Angiogenesis is a common characteristic of metastatic cancer through which oxygen and nutrients are delivered to the cells and tissues. In the present study, angiogenesis-inhibiting activity was investigated by evaluating the total polyphenol and flavonoid contents of the P. mume butanol fraction (PBF) and their ability to inhibit VEGF-induced human umbilical vein endothelial cells (HUVECs) proliferation, migration, invasion, and capillary formation. The polyphenols (12.81 mg GAE/g) and flavonoids (28.4 mg QE/g) of the PBF exhibited high antioxidant activity. The results of this study showed that PBF did not inhibit the proliferation of HUVECs at concentrations of 25-200 ㎍/ml and did not exhibit toxicity to normal cells. However, PBF inhibited the VEGF-induced mobility, invasion, and capillary formation of HUVECs. These results show that PBF inhibits the angiogenesis of HUVECs induced by VEGF. Therefore, PBF could serve as a therapeutic agent for the inhibition of angiogenesis.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.147-154
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• 2022

The Mongolian lingonberry and blueberry are two essential food sources found in Mongolia. This study investigated the antioxidant and anti-inflammatory effects of methanol extracts from Mongolian lingonberry (LBE) and blueberry (BBE). Compared to the LBE, the BBE showed higher total phenolic, flavonoid, and anthocyanin contents, as well as antioxidant capacities. The LBE and BBE inhibited the mRNA expression of pro-inflammatory genes, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and cyclooxygenase (COX-2) in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. In addition, the LBE and BBE inhibited NADPH oxidase-2 (Nox2) mRNA expression, indicating that they have cellular antioxidant capacities. Anthocyanin derivatives of the LBE and BBE were analyzed using LC-QTOF/MS. Six anthocyanins were identified in the BBE, while one was detected in the LBE. Our findings demonstrate that the anthocyanin-rich LBE and BBE could be used as functional food sources in Mongolia.

• Korean Journal of Food Science and Technology
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• v.54 no.3
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• pp.306-312
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• 2022

To test bee pollen as an ingredient for heat-processed foods, bee pollen was puffed under heat at various pressures and examined for its physicochemical properties and antioxidant activities. As the puffing intensity increased, the browning index, total reducing capacity, and DPPH radical scavenging activity of the bee pollen increased significantly (p<0.001). This was attributed to the formation of Maillard reaction products during the puffing process. The wheat flour-puff yeot-gangjeong added with puffed bee pollen showed significantly (p<0.01) higher antioxidant activities than its counterpart with raw bee pollen. In addition, the gangjeong retained the physicochemical characteristics of the puffed bee pollen such as color, soluble solids, titratable acidity, and pH. The results showed that the puffed bee pollen could potentially be used as an ingredient in thermally processed foods and retain its superior antioxidant properties.

• Journal of Food Hygiene and Safety
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• v.37 no.5
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• pp.297-305
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• 2022

Antioxidants are food additives that extend the shelf life of food products by preventing lipid rancidity caused by active oxygen. They can either be naturally-derived or manufactured synthetically via chemical synthesis. In this study, method validation of five synthetic antioxidants, namely butylated hydroxyanisole, butylated hydroxytoluene, tertiary butylhydroquinone, propyl gallate, and disodium ethylenediaminetetraacetic acid, was performed using a high performance liquid chromatography-ultraviolet visible detector, and the method applicability was evaluated by analyzing foods containing antioxidants. The coefficient of determination (R²) average was 0.9997, while the limit of detection and limit of quantification were 0.02-0.53 and 0.07-1.61 mg/kg, respectively. The intra and inter-day accuracies and precisions were 83.2±0.7%-98.7±2.1% and 0.1%-5.7% RSD, respectively. Inter-laboratory validation for accuracy and precision was conducted using the Food Analysis Performance Assessment Scheme quality control material. The results satisfied the guidelines presented by the AOAC International. In addition, the expanded uncertainty was less than 16%, as recommended by CODEX. Consequently, to enhance public health safety, the results of this study can be used as basis data for evaluating the intake of synthetic antioxidants and assessing their risks in Korea.

• Membrane Journal
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• v.34 no.1
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• pp.38-49
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• 2024

Wastewater treatment using membrane bioreactors has been extensively used to alleviate water shortage and pollution by improving the quality of the treated water discharged into the environment. However, membrane biofouling persistently holds back an MBR process by reducing the process efficiency. Herein, we synthesized carbon nanospheres (CNSs) with many hydrophilic oxygen groups and utilized them as an additive to prepare high-performance ultrafiltration (UF) membranes with hydrophilicity and porous pore structure. CNSs were found to form crescent-shaped pores on the membrane surface, increasing the mean surface pore size by about 40% without causing significant defects larger than bubble points, as the CNS content increased by 4.6 wt%. In addition, the porous pore structure of CNS composite membranes was also attributable to the CNS's isotropic morphologies and relatively low particle number density because the aforementioned properties contributed to preventing the polymer solution viscosity from soaring with the loading of CNS. However, too porous structure compromised the mechanical properties, such that CNS2.3 was the best from a comprehensive consideration including the pore structure and mechanical properties. As a result, CNS2.3 showed not only 2 times higher water permeability than CNS0 but also 5 times longer operation duration until membrane cleaning was required.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.349-358
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• 2007

In order to understand biogeochemical cycles of organic carbon in the permeable intertidal sandy sediments of the Nakdong estuary, we estimated the organic carbon production and consumption rates both in situ and in the laboratory. The Chl-a content of the sediment and the nutrient concentrations in below surface pore water in the sandy sediment were lower than in the muddy sediment. The sediment oxygen consumption rates were relatively high, especially when compared with rates reported from other coastal muddy sediments with higher organic carbon contents. This implied that both the organic carbon degradation and material transport in the sandy sediment were enhanced by advection-related process. The simple mass balance estimation of organic carbon fluxes showed that the major sources of carbon in the sediment would originate from benthic microalgae and detrital organic carbon derived from salt marsh. The daily natural biocatalzed filtration, extrapolated from filtration rates and the total area of the Nakdong estuary, was one order higher than the maximum capability of sewage plants in Busan metropolitan city. This implies that the sandy sediment contributes greatly to biogeochemical purification in the area, and is important for the re-distribution of materials in the coastal environment.

• The Journal of Engineering Geology
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• v.19 no.4
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• pp.529-541
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• 2009

Hydrochemical, stable isotopic ($\delta^{18}O$ and dD) and noble gas isotopic analyses of seven hot spring water samples, eleven groundwater samples and six surface water samples collected from the Icheon and Pocheon area were carried out to find out hydrochemical characteristics, and to interpret the source of noble gases and the geochemical evolution of the hot spring waters. The hot spring waters show low temperature type ranging from 21.5 to $31.4^{\circ}C$ and the pH value between 6.69 and 9.21. Electrical conductivity of hot spring waters has the range from 310 to $735\;{\mu}S/cm$. Whereas the hot spring water in the Icheon area shows the geochemical characteristics of neutral pH, the $Ca-HCO_3$(or $Ca(Na)-HCO_3$) chemical type and a high uranium content, the hot spring water in the Pocheon area shows the characteristics of alkaline pH, the $Na-HCO_3$ chemical type and a high fluorine content. These characteristics indicate that the hot spring water in the Icheon area is under the early stage in the geochemical evolution, and that the hot spring water in the Pocheon area has been geochemically evolved. The $\delta^{18}O$ and ${\delta}D$ values of hot spring waters show the range of $-10.1{\sim}-8.69%o$ and from $-72.2{\sim}-60.8%o$, respectively, and these values supply the information of the recharge area of hot spring waters. The $^3He/^4He$ ratios of the hot spring waters range from $0.09\;{\times}\;10^{-6}$ to $0.65\;{\times}\;10^{-6}$ which are plotted above the mixing line between air and crustal components. Whereas the helium gas in the Icheon hot spring water was mainly provided from the atmospheric source mixing with the mantle(or magma) origin, the origin of helium gas in the Pocheon hot spring water shows a dominant crustal source. $^{40}Ar/^{36}Ar$ ratios of hot spring water are in the range of an atmosphere source.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.273-280
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• 2003

Saline conditions invoke oxidative stress attributed to the overproduction of reactive oxygen species (ROS). Changes in quantum efficiency and antioxidative enzyme activity upon salt treatment were examined in a salt-tolerant plant, Atriplex gmelini, to test the hypothesis that salt tolerance of A. gmelini is due to the increased activity of antioxidative enzymes. A. gmelini showed optimum growth at 100 mM NaCl producing 116% of the shoot dry weight over control plants in 0 mM NaCl treatment. Healthy growth persisted up to 300 mM NaCl treatment maintaining normal internal water content and dry weight. No photochemical stress or damages on antioxidative defense system was obvious in plants of 2 and 4 day salt treatment which was indicated by increased quantum efficiency (Fv/Fm value), decreased stress index (Fo/Fm value), and increased activity of antioxidative enzymes such as SOD, APX, GR. However, the plants treated with 400 mM NaCl showed decrease in growth and in antioxidative enzyme activity although the enzyme activity was still higher than that of the 0 mM NaCl treated plants (l31%, 114%, and 134% of the SOD, APX, and GR activity, respectively). Interestingly, another important antioridative enzyme that scavenges H₂O₂ in plant cells, CAT, showed rapid decrease in its activity as salt concentration increased; 38%, 22%, 15% of the 0 mM NaCl treated plants at 200, 300, 400 mM NaCl treatments, respectively. It appears that the enzymes in ascorbate-glutathione cycle such as APX and GR play the major roles in scavenging ROS produced by salt stress in A. gmelini. After 6 days of salt treatment, the damage in photochemical and antioxidative defense system was indicated by decreased Fv/Fm value and increased Fo/Fm value. A. gmelini appears to cope with short term salt treatment by enhanced activity of the antioxidative defense system, whereas long term stress invoke oxidative stress by increased ROS due to the damages in photochemical and antioxidative system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.931-938
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• 2002

The growth of enterobacteria, Bifidobacterium infantis KCTC 3270, was promoted by natural products bearing antioxidative capacity and mixed combinations of two, three and four kinds of them. B. infantis was expressed a good growth by Aurantii nobilis pericarpium majus L., Astragali radix, Epimedii herba, alone, and two mixed combinations of Epimedii herba and Theae folium, Epimedii herba and Crataegi fructus, Epimedii herba and Eucommiae cortex, and three mixed combinations of Theae folium, Epimedii herba and Chelidonium majus L., Theae folium, Epimedii herba and Aurantii nobilis pericarpium, Theae folium, Chelidonium majus L. and Auantii nobilis pericar pium, Theae folium, Chelidonium majus L. and Astragali radix, Theae folium, Aurantii nobilis pericarpium and puerariae radix, Epimedii herba, Chelidonium majus L. and Aurantii nobilis pericarpium, and four mixed com-binations of Theae folium, Chelidonium majus L., Astragali radix and Epimedii herba, and Theae folium, Chelidonium majus L., Astragali radix and Puerariae readix, and Theae folium, Epimedii herba, Aurantii nobilis pericarpium and Puerariae radix, and Theae folium, Chelidonium majus L., Aurantii nobilis pericarpium and Puerariae radix. The best four mixed combination ofr the growth of B. infantis was Theae folium, Chelidonium majus L. Astragali radix and Epimedii herba, which promoted 2.1 times than that of control, and its antioxidative capacity was also 5 times higher, and the ratio of elimination of hydroxyl radical was more than 80% in each dilution rate. As these combinations of natural products might activate some parts of body, they could be applied to pharmaceutical applications, functional foods, antiaging tea, also expected to promote useful bacterial growth for fermentative beverage bearing multifunction.