• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.556-566
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• 2010

A new kinetic spectrophotometric method is developed for the measurement of Mn(II) in natural water samples. The method is based on the catalytic effect of Mn(II) with the oxidation of Gallocyanin by $KIO_4$ using nitrilotriacetic acid (NTA) as an activation reagent at 620 nm. The optimum conditions obtained are $4.00{\times}1^{-5}\;M$ Gallocyanin, $KIO_4$, $1.00{\times}10^{-4}\;M$ NTA, 0.1 M HAc/NaAc buffer of pH = 3.50, the reaction time of 5 min and the temperature of $30^{\circ}C$. Under the optimum conditions, the proposed method allows the measurement of Mn(II) in a range of $0.1\;-\;4.0\;ng\;mL^{-1}$ and with a detection limit of down to $0.025\;ng\;mL^{-1}$. The recovery efficiency in measuring the standard Mn(II) solution is in a range of 98.5 - 102%, and the RSD is in a range of 0.76 - 1.25%. The newly developed kinetic method has been successfully applied to the measurement of Mn(II) in both some environmental water samples and certified standard reference river water sample, JAC-0031 with satisfying results. Moreover, few cations and anions interfere with the measurement of Mn(II). Compared with the other catalytic-kinetic methods and instrumental methods, the proposed kinetic method shows fairly good selectivity and sensitivity, low cost, cheapness, low detection limit and rapidity. It can easily and successfully be applied to the real water samples with relatively low salt content and complex matrices such as bottled drinking water, cold and hot spring waters, lake water, river water samples.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.267-273
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• 2018

Horse fat was extracted from fatty horse meat at $70^{\circ}C$ under vacuum conditions. The oxidative stability of horse fat was investigated by the addition of 0, 30, 60, and 150 mg/kg of ${\alpha}$-, ${\gamma}$-, or ${\delta}$-tocopherol during storage of 14 days at $65^{\circ}C$ in the dark. Changes of tocopherol concentration and fatty acid composition, peroxide value, and 2-thiobarbituric acid (TBA) value were analyzed during storage. The levels of the added tocopherols were found to decrease during storage. Unsaturated fatty acids contents of horse fat without tocopherol decreased from 60.87% to 57.22% after 14 days. The peroxide value and TBA value increased as storage time increased. The peroxide values of horse fat after addition of 0, 30, 60, and 150 mg/kg of ${\gamma}$-tocopherol were 43.75, 25.17, 20.87, and 15.41 meq/kg, respectively, and the TBA values were 7.87, 5.64, 4.43, and 4.23 mg malonaldehyde (MA)/kg, respectively, after 14 days. At the concentration of 150 mg/kg, both ${\gamma}$- and ${\delta}$-tocopherol impeded the oxidation of horse fat during storage.

• Food Science of Animal Resources
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• v.30 no.2
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• pp.269-276
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• 2010

The objective of this study was to determine the effects of residual nitrite contents, chitosan with different molecular weight and nitrite addition on emulsified sausage during cold storage. Six types of sausages were evaluated: control, 0.5% 50 kDa chitosan (T1), 0.5% 200 kDa chitosan (T2), 150 ppm nitrite (T3), 0.5% 50 kDa chitosan+150 ppm nitrite (T4), and 0.5% 200 kDa chitosan+150 ppm nitrite (T5). Each type of sausage was tested in triplicate and assigned to one of four storage periods: 0, 10, 20 and 30 days. As the storage time increased, the presence of chitosan and nitrite resulted in decreased residual nitrite value and increased pH (in control and T2), TBARS (thiobarbituric acid reactive substance) values, and total plate counts (TPC). Values for pH, TBARS, residual nitrite and total plate counts decreased significantly in response to the addition of chitosan and nitrite relative to the control (p<0.05). T5 was redder than the control (higher CIE$a^*$) at 30 d; however, no difference in the CIE $L^*$ and $b^*$ values was observed. T5 was significantly (p<0.05) more effective at delaying lipid oxidation when compared to the other treatment groups. T5 presented TPC that was significantly lower (p<0.05) than the other groups after three days of storage. In addition, the use of chitosan and nitrite in combination had much better antioxidant and antimicrobial effectiveness than other treatment groups. In conclusion, this study demonstrates that the addition of 0.5% 200 kDa chitosan and 150 ppm nitrite in combination with emulsified sausages tended to improve antioxidative and antimicrobial effects during storage when compared to other treatment groups.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.238-245
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• 2000

This study was investigated to compare the changes of flavors in sesame oil with roasting temperature $(110^{\circ}C{\sim}230^{\circ}C)$. In the results of analyzing the volatile flavor compounds of sesame oil with GC and GC/MS, 26 pyrazines, 11 pyridines, 9 thiazoles, 6 furans, 8 pyrroles, 5 phenols, 8 aldehydes, 8 hydrocarbons, 7 alcohols, 2 indoles, 3 ketones, 10 acids, 4 nitriles, 7 esters, and 5 others were isolated, identified, and quantified. The total amount of flavor compounds was increased with roasting temperature. Detected flavors could be devided into top(peak No. $1{\sim}91$), middle$(92{\sim}197)$ and last note$(198{\sim}224)$ by rentention time. The top notes(initial content 19.87 ppm) which contain pyrazines and provide representative roasted flavors were increased significantly with roasting temperature. Initial content of middle note(17.72 ppm) was increased to 36.71 ppm at $170^{\circ}C$, to 95.61 ppm at $220^{\circ}C$, and to 138.62 ppm at $230^{\circ}C$. Last note was almost unchanged up to $170^{\circ}C$ and increased at $190^{\circ}C$, whereas it indicated a tendency to decrease at $230^{\circ}C$. Pyrazines such as methylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine which indicate the major components among volatile flavors were increased slightly up to $150^{\circ}C$ and revealed the higher increase than any other components above $170^{\circ}C$. This tendency was also similar to pyridines, thiazoles, and furans. Most of these compounds are assumed to be developed by thermochemical reactions of sesame components by roasting above $170^{\circ}C$. It seemed that a lot of increase in phenols above $210^{\circ}C$ resulted from the production of guaiacol. Acids were almost unchanged up to $190^{\circ}C$, increased at $210^{\circ}C$, and then decreased above $220^{\circ}C$. It seemed to be resulted from pyrolysis of free fatty acids formed from thermal oxidation of oil.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.594-598
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• 1998

In this study oxidative deterioration of dried sea mussel and baby clam stored at $4{\pm}2^{\circ}C$ and $25{\pm}2^{\circ}C$ were investigated. Acid value of samples were higher at $25^{\circ}C$ than those at $4^{\circ}C$ throughout the storage period. And it was higher in dried baby clam than in sea mussel regardless of storage temperatures. Peroxide value of dried sea mussel and baby clam stored at $25^{\circ}C$ tended to decrease after 30 and 60 days, respectively. Thiobarbituric acid and carbonyl value of samples stored at $4^{\circ}C$ were higher than those stored at $25^{\circ}C$ throughout the storage period. In case of sea mussel, However they were lower stored at $4^{\circ}C$ than at $25^{\circ}C$ in 30 days. Amino nitrogen increased until 60 days and then decreased in all samples. Fluorescence intensity associated with interaction between carbonyl compound and amino compound was increased with storage temperature and time but it decreased slowly after 60 days.

• Food Science and Preservation
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• v.25 no.1
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• pp.36-43
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• 2018

In this study, we investigated the inhibition effect of various herbs on the rancidity of soybean oil. The antioxidant activity of herb-infused oils was evaluated by examining their total phenolic contents and DPPH radical scavenging abilities. The total phenolic contents were found to increase with addition of herbs to the soybean oil. Rosemary-infused oil (RO) exhibited the highest total phenolic contents ($77.28{\mu}g\;GE/mL$), followed by the lemon-balm-infused oil (LO), green-tea-infused oil (GO), and soybean oil (SO) alone (36.82, 36.66, and $21.24{\mu}g\;GE/mL$, respectively). Similary, the DPPH radical scavenging activity of the herb infused oil also increased. Moreover, measurements on the total polar compound (TPC) contents, acid value, and p-anisidine value were carried out in order to confirm the changes in the rancidity of the oils during frying. The time for the TPC content to reach 25% was confirmed to be delayed from 62 h for SO to 68 h, 74 h, and 80 h for GO, RO, LO, respectively. Even though there were some differences between the p-anisidine and acid values, it was confirmed that the addition of herbs inhibited the rancidity of soybean oil. Therefore, the results in this study show that adding herbs to soybean oil could positively contribute to the inhibition of oxidation and rancidity.

• Journal of Soil and Groundwater Environment
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• v.14 no.4
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• pp.33-44
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• 2009

Water curtain of an underground LPG storage cavern is a facility to prevent leakage of high pressure gases, for which groundwater should flow freely towards the cavern and groundwater level also must be stably maintained. In this study, in order to evaluate qualities of seepage water and surrounding groundwater of an underground LPG storage cavern in Yeosu, 4 rounds of samplings, field measurements and laboratory analyses (February, May, August, October of 2007) were conducted. According to field measurements, pH was weak acidic to neutral but it gradually increased with time. Electrical conductivity (EC) of groundwater near a salt stack showed very high values between 10.47 and 38.50 mS/cm. Dissolved oxygen (DO) showed a very wide range of 0.20~8.74 mg/L and a mean of oxidation-reduction potential (ORP) was 159 mV, which indicated an oxidized condition. Levels of $Fe^{2+}$ and $Mn^{2+}$ were mostly less than 3 mg/L. All of seepage waters showed a Na-Cl type while only groundwater near the salt stack showed a Na-Cl type with a high total dissolved solid. The other groundwaters exhibited typical $Ca-HCO_3$ types. Levels of aerobic bacteria were mostly very high (573-39,520 CFU/mL). Based on the analyses of these hydrochemistry and biological characteristics, it is concluded that there are no particular problems in groundwater and seepage water, which not causing a trouble in the cavern operation. However, both for control of bio-clogging and for sustainable operation of the water curtain system, a regular hydrochemical and microbiological monitoring is required for the seepage water and surrounding groundwater.

• Journal of Nutrition and Health
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• v.55 no.2
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• pp.227-239
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• 2022

Purpose: This study investigated the effects of water-soluble mulberry leaf extract (ME) on hepatic lipid accumulation in high-fat diet-fed rats via the regulation of hepatic microRNA (miR)-221/222 and inflammation. Methods: Male Sprague-Dawley rats (4 weeks old) were randomly divided into 3 groups (n = 7 each) and fed with 10 kcal% low-fat diet (LF), 45 kcal% high-fat diet (HF), or HF + 0.8% ME for 14 weeks. Lipid profiles and cytokine levels of the liver and serum were measured using commercial enzymatic colorimetric and enzyme-linked immunosorbent assay, respectively. The messenger RNA (mRNA) and miR levels in liver tissue were assayed by real-time quantitative reverse-transcription polymerase chain reaction. Results: Supplementation of ME reduces body weight and improves the liver and serum lipid profiles as compared to the HF group. The mRNA levels of hepatic peroxisome proliferator-activated receptor-gamma, sterol regulatory element binding protein-1c, fatty acid synthase, and fatty acid translocase, which are genes involved in lipid metabolism, were significantly downregulated in the ME group compared to the HF group. In contrast, the mRNA level of hepatic carnitine palmitoyl transferase-1 (involved in fatty acid oxidation) was upregulated by ME supplementation. Furthermore, administration of ME significantly downregulated the mRNA levels of inflammatory mediators such as hepatic tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), monocyte chemoattractant protein-1, and inducible nitric oxide synthase. The serum levels of TNF-α, IL-6, and nitric oxide were also significantly reduced in ME group compared to the HF group. Expression of hepatic miR-221 and miR-222, which increase in the inflammatory state of the liver, were also significantly inhibited in the ME group compared to the HF group. Conclusion: These results indicate that ME has the potential to improve hepatic lipid accumulation in high-fat diet-fed rats via modulation of inflammatory mediators and hepatic miR-221/222 expressions.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.421-433
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• 2023

The final disposal of spent nuclear fuel(SNF) from nuclear power plants takes place in a deep geological repository. The metal canister encasing the SNF is made of cast iron and copper, and is engineered to effectively isolate radioactive isotopes for a long period of time. The SNF is further shielded by a multi-barrier disposal system comprising both engineering and natural barriers. The deep disposal environment gradually changes to an anaerobic reducing environment. In this environment, sulfide is one of the most probable substances to induce corrosion of copper canister. Stress-corrosion cracking(SCC) triggered by sulfide can carry substantial implications for the integrity of the copper canister, potentially posing a significant threat to the long-term safety of the deep disposal repository. Sulfate can exist in various forms within the deep disposal environment or be introduced from the geosphere. Sulfate has the potential to be transformed into sulfide by sulfate-reducing bacteria(SRB), and this converted sulfide can contribute to the corrosion of the copper canister. Bentonite, which is considered as a potential material for buffering and backfilling, contains oxidized sulfate minerals such as gypsum(CaSO4). If there is sufficient space for microorganisms to thrive in the deep disposal environment and if electron donors such as organic carbon are adequately supplied, sulfate can be converted to sulfide through microbial activity. However, the majority of the sulfides generated in the deep disposal system or introduced from the geosphere will be intercepted by the buffer, with only a small amount reaching the metal canister. Pyrite, one of the potential sulfide minerals present in the deep disposal environment, can generate sulfates during the dissolution process, thereby contributing to the corrosion of the copper canister. However, the quantity of oxidation byproducts from pyrite is anticipated to be minimal due to its extremely low solubility. Moreover, the migration of these oxidized byproducts to the metal canister will be restricted by the low hydraulic conductivity of saturated bentonite. We have comprehensively analyzed and summarized key research cases related to the presence of sulfates, reduction processes, and the formation and behavior characteristics of sulfides and pyrite in the deep disposal environment. Our objective was to gain an understanding of the impact of sulfates and sulfides on the long-term safety of high-level radioactive waste disposal repository.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.727-736
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• 2022

Ice wedges are subsurface ice mass structures that formed mainly by freezing precipitation with airborne dust and surrounding soil particles flowed through the active layer into the cracks growing by repeating thermal contractions in the deeper permafrost layer over time. These ice masses characteristically contain high concentrations of solutes and solids. Because of their unique properties and distribution, the possibility of harnessing ice wedges as an alternative archive for reconstructing paleoclimate and paleoenvironment has been recently suggested despite limited studies. It is imperative to preserve the physicochemical properties of the ice wedge (e.g., solute concentration, mineral particles) without any potential alteration to use it as a proxy for reconstructing the paleo-information. Thawing the ice wedge samples is prerequisite for the assessment of their physicochemical properties, during which the paleo-information could be unintentionally altered by any methodological artifact. This study examined the effect of thawing conditions and procedures on the physicochemical properties of solutes and solid particles in ice wedge samples collected from Cyuie, East Siberia. Four different thawing conditions with varying temperatures (4 and 23℃) and oxygen exposures (oxic and anoxic) for the ice wedge sample treatment were examined. Ice wedge samples thawed at 4℃ under anoxic conditions, wherein biological activity and oxidation were kept to a minimum, were set as the standard thawing conditions to which the effects of temperature and oxygen were compared. The results indicate that temperature and oxygen exposure have negligible effects on the physicochemical characteristics of the solid particles. However, the chemical features of the solution (e.g., pH, electric conductivity, alkalinity, and concentration of major cations and trace elements) at 4℃ under oxic conditions were considerably altered, compared to those measured under the standard thawing conditions. This study shows that the thawing condition of ice wedge samples can affect their chemical features and thereby the geochemical information therein for the reconstruction of the paleoclimate and/or paleoenvironment.