• Korean Journal of Ecology and Environment
• /
• v.35 no.4 s.100
• /
• pp.257-265
• /
• 2002

The current study was performed to elucidate the relationship between the anatoxin -a produced by cyanobacteria and aquatic environmental factors, Algal and water samples were collected from the Daechung Reservoir from June to November 2001. The physical factors of the water quality were measured in sifu, while the biological and chemical factors were examined in the laboratory. The concentrations of anatoxin-a in the algal and water samples were analyzed by HPLC using a fluorescence detector, and ranged from $0.61-8.68\;{\mu}g/g$ dw in the algal samples and $0.01-0.08\;{\mu}g/L$ in the water samples. The suggested maximum concentration of anatoxin-a for safe drinking water is $1\;{\mu}g/L$. The concentrations of anatoxin-a in the algal and water samples were highest in July. The relationships between tile aquatic environmental factors and the anatoxin-a concentration were also analyzed to identify the crucial elements for toxin production. The anatoxin-a concentrations in the algal samples exhibited a high correlation with nitrate, the TN/TP ratio, TDN (P<0.05), and TPN/TPP ratio (P<0.01), whereas the anatoxin-a concentrations in the water samples were highly related to the water temperature, conductivity (P<0.01) , pH, phycocyanin, and phycocyanin/chlorophyll a ratio (P<0.05).

• Korean Journal of Food Science and Technology
• /
• v.40 no.2
• /
• pp.220-227
• /
• 2008

In this study, polysaccharides were isolated from Korean persimmon vinegar to characterize the polysaccharides existing as soluble forms within traditional Korean fermented beverages, and their immuno-stimulating activities were examined. Three successive chromatographies were used to purify the main polysaccharide in the persimmon vinegar, PV-1b-I, to homogeneity from the crude polysaccharide (PV-0). The molecular mass of PV-1b-I was estimated as 110 kDa and it contained significant proportions of mannose (46.8%), galactose (28.5%) and arabinose (19.1%). PV-1b-I strongly reacted with ${\beta}$-glucosyl Yariv reagent, suggesting the presence of an arabino-3,6-galactan moiety. PV-1b-I also induced high levels of macrophage activation and mitogenicity on murine splenocytes in vitro. The intravenous administration of PV-1b-I significantly augmented NK cytotoxicity against YAC-1 tumor cells. PV-1b-I also showed potent anticomplementary activity in a dose-dependent manner. Finally, C3 activation products were identified by crossed immunoelectrophoresis using anti-human C3 and the anti-complementary activity of PV-1b-I under $Ca^{2+}$-free conditions, suggesting that this PV-1b-I causes complementary activations via both alternative and classical pathways. From these results, one can conclude that Korean persimmon vinegar contains select polysaccharides in addition to healthy components, and these polysaccharides appear to provide immuno-stimulating activities beneficial to human health.

• Journal of Food Hygiene and Safety
• /
• v.34 no.5
• /
• pp.431-437
• /
• 2019

This study was conducted to develop a simultaneous analysis method for ferulic acid, caffeic acid, catechin and taxifolin from Health Functional Food (HFF) Pinus Pinaster bark extract. The simultaneous analytical method for ferulic acid, caffeic acid, catechin and taxifolin is carried out using UPLC-MS/MS. The method validation was performed to determine selectivity, linearity, accuracy, limit of detection (LOD), limit of quantification (LOQ) and precision for ferulic acid, caffeic acid, catechin and taxifolin. LC-MS/MS method was established using an Acquity UPLC BEH $C_{18}$ Column and was applied for these 4 compounds. Product-ion traces, at m/z $194.2{\rightarrow}133$, $180.2{\rightarrow}135$, $290.3{\rightarrow}245$, $304.3{\rightarrow}248$, were used for quantitative analysis of ferulic acid, caffeic acid, catechin and taxifolin, respectively. Excellent linearity ($r^2=0.999$) was observed for ferulic acid, caffeic acid, catechin and taxifolin in the concentration range (50-2500 mg/L). The observed recoveries of these 4 compounds were found to be between 84.9 and 104.9%, while precision was between 1.20 and 4.43% relative standard deviation (% RSD).

• Journal of Life Science
• /
• v.29 no.11
• /
• pp.1294-1303
• /
• 2019

Perchlorate is an anionic pollutant that is very soluble and stable in water. It has been detected not only in soil/ground water but also in surface water, drinking water, food, fish, and crops. Perchlorate inhibits iodine uptake by the thyroid gland and reduces production of thyroid hormones that are primarily responsible for regulation of metabolism. Although various technologies have been developed to remove perchlorate from the environment, biodegradation is the method of choice since it is economical and environmentally friendly. However there is limited information on perchlorate biodegradation in salt environment such as salt water. Therefore this paper reviews biodegradation of perchlorate in salt water and related microorganisms. Most biodegradation research has employed heterotrophic perchlorate removal using organic compounds such as acetate as electron donors. Biodegradation research has focused on perchlorate removal from spent brine generated by ion exchange technology that is primarily employed to clean up perchlorate-contaminated ground water. Continuous removal of perchlorate at up to 10% NaCl was shown when bioreactors were inoculated with enriched salt-tolerant perchlorate-reducing bacteria. However the reactors did not show long-term stable removal of perchlorate. Microorganisms belonging to ${\beta}$- and ${\gamma}$-Proteobacteria were dominant in bioreactors used to remove perchlorate from salt water. This review will help our understanding of perchlorate removal from salt water to develop a decent biotechnology for the process.

• Food Science and Preservation
• /
• v.19 no.4
• /
• pp.554-559
• /
• 2012

To evaluate the effect of aging on solar salts produced in Korea, the chemical compositions of the solar salts, including their heavy metal contents, were analyzed after they were aged for one-year (OA) and for three years (TA). The average contents of the components were: sodium chloride; 81.4% (OA) and 90.9% (TA), chloride; 57.7% (OA) and 65.0% (TA), moisture content; 4.7% (TA) and 12.0% (OA), insoluble solids; 0.03% (OA) and 0.04% (TA), and $SO_4$ ions; and 0.57% (TA) and 0.85% (OA). No significant difference was found, however, in the heavy metal contents. Heavy metals such as As, Pb, and Hg were detected with values far below the maximum permissible limit, and Cd was not detected in the salts. The TA solar salts showed higher values of sodium chloride, chloride, and insoluble solids than the OA solar salts, but the TA solar salts had lower moisture and $SO_4$ values. These results clearly indicate that the levels of heavy metals in the OA and TA solar salts that are produced in Korea are safe.

• Journal of Sericultural and Entomological Science
• /
• v.50 no.2
• /
• pp.145-149
• /
• 2012

Cecropin is a well-studied antimicrobial peptide that play important role as key factor in insect humoral immunity. In this study, cecropin-like antimicrobial peptide was isolated and purified from the larval haemolymph of immune-challenged japanese oak silkworm, Antheraea yamamai. To isolate antimicrobial peptide, we separated and compared acidic extracted hemolymph protein bends between control and immune-challenged larvae using SDS-PAGE analysis. In the immune hemolymph extract, but not of non-immune hemolymph, we detected differential expressed peptide band with molecular mass 4,223.01 Da. To understand this peptide better, we successfully purified this peptide using cation exchange chromatography and gel permeation chromatography. Its N-terminal amino acid sequence obtained by Edman degradation evidenced a significant degree of identity with other lepidopteran cecropins. The purified A. yamamai cecropin-like peptide showed a broad spectrum of activity against fungi, Gram-negative and Gram-positive bacteria.

• Fire Science and Engineering
• /
• v.33 no.2
• /
• pp.30-38
• /
• 2019

Tracking, which is one of the main causes of electrical fires, is perceived as a physical phenomenon of electrical discharge. Hence tracking should be explained based on electric field analysis, conduction path by electron generation, and gas discharge physics. However, few papers have considered these details. This paper proposes a tracking mechanism including their effects on tracking progress. In order to prove this mechanism, a tracking experiment, an electric field analysis for the carbonization evolution model, and an explanation of the tracking process by gas discharge physics were conducted. From the tracking experiment, the current waveforms were measured at each stage of the tracking progress from corona discharge to tracking breakdown. The electric field analysis was carried out in order to determine the electric field on the surface of a dry-band and the high electric field region for electron generation during the generation and progress of carbonization. In this paper, the proposed tracking mechanism consisted of six stages including electron avalanche by corona discharge, accumulation of positive ions, expansion of electron avalanche, secondary electron emission avalanche, streamer, and tracking by conductive path. The pulse current waveforms measured in the tracking experiment can be explained by the proposed tracking mechanism. The results of this study will be used as the technical data to detect tracking phenomenon, which is the cause of electric fire, and to improve the proof tracking index.

• Korean Journal of Mineralogy and Petrology
• /
• v.33 no.4
• /
• pp.391-405
• /
• 2020

Leaching chracteristics of Andong-dam sediment was conducted for heavy metal and nutrients. Five mixed sediment samples were prepared and leaching was conducted under aerobic and anaerobic condition for 60 days. Cd, Cu, Pb, Cr, Zn, Hg, As, Fe, Mn, phosphorus, and nitrogen were analyzed at each sampling time. The leaching rate of phosphorus was higher in anaerobic condition comparing with that of under aerobic condition. Some samples showed higher than the water-quality level IV. In case of As and Cd which showed highest contamination level in the sediment, leached concentration were 0.028 mg/L and 0.003 mg/L in maximum, respectively. The leached concentration is below than the lake water quality standard of Korea. Other heavy metals including Cu, Pb, and Cr also showed similar trend. Five step sequential extraction showed that easily extractable 1-2 step portion such as ion-exchangeable and adsorbed one was less than 10% and the most of the portion was residual. For As and Cd, the residual portion were 80% and 95% respectively indicating the risk by the heavy metal leaching into the lake for a short period was not high in comparing with the contamination levels.

• Journal of the Korean earth science society
• /
• v.42 no.1
• /
• pp.1-10
• /
• 2021

Silicon (Si) is the second most abundant element in the crust and consists of three stable isotopes, 28Si (92.23%), 29Si (4.67%), and 30Si (3.10%). Si isotopes are widely studied worldwide as a proxy for the biogeochemical cycle of Si to reconstruct the paleoenvironment and paleoclimate. However, in Korea, there have been no studies on biogenic silica using Si isotopes. In this study, we carried out Si isotope measurements of giant diatoms, summarizing the previously reported alkali fusion methods and establishing the best Si separation method for biogenic silica. Samples were completely digested using alkali fusion at high temperatures, effectively separating Si using an AG® 50W-X8 cation exchange resin. To evaluate the precision and accuracy of our measurements, Si isotope standard material (NBS-28) and USGS reference materials (AGV-2, GSP-2, BHVO-2) were analyzed. The results are in excellent agreement with the reported values within the acceptable error. The Si isotope measurement method developed in this study is expected to help in understanding the paleoclimate and paleoenvironment by tracing the Si cycle.

• Analytical Science and Technology
• /
• v.35 no.3
• /
• pp.116-123
• /
• 2022

Polymer bags, metallic canisters, and glass bottles have been used as containers for analyzing the volatile organic compounds (VOCs) in air. In this study, various sampling containers were compared to investigate the short-term stability of VOCs, that is, from the time they are sampled to the time they are analyzed. Polyvinyl fluoride (PVF), polypropylene (PP), polyester aluminum (PE-Al) bags, canisters, and glass bottles were used as sample containers. A 100 nmol/mol standard gas mixture of benzene, toluene, ethylbenzene, m-xylene, styrene, and o-xylene was used for the VOC comparison. Changes in the concentrations of samples stored for 10~20 day in each container were measured using a thermal desorption-gas chromatograph-flame ionization detector (TD-GC-FID). As a result, VOCs stored in a canister and two kinds of amber glass bottles have shown immaterial decreases in concentration in one week, and more than 80 % of the initial concentration was maintained for two weeks. In the case of polymer bags, the concentration of all VOCs, except benzene and toluene, were remarkably decreased below 70% of the initial concentration in one day. Particularly, ethylbenzene, xylene, and styrene have shown dramatic decreases in concentration below 30 % of the initial concentration in all polymer bags in one day.