• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.2
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• pp.69-79
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• 2020

In this study, the anti-inflammatory and cytotoxic effects of hot-water extracts from 10 kinds of macroalgae in Korea were investigated. It was selected materials in consideration of biological activity and industrial potential as follows: Caulerpa okamurae; Codium fragile; Ulva australis; Ishige foliacea; Saccharina japonica; Sargassum horneri; Undaria pinnatifida; Gloiopeltis tenax; Gracilaria verrucosa; Porphyra tenera. Results showed that S. japonica and G. tenax significantly decreased NO productionn in LPS-stimulated Raw 264.7 cells at concentrations of 100, 1000 ㎍/mL and 1000 ㎍/mL, respectively. However, most of the other macroalgae used in the experiment did not affect NO production. It was observed that all macroalgae extracts except for the highest concentration (1000 ㎍/mL) treatment group of P. tenera did not affect the viability in Raw 264.7 cells. In addition, there was not significant decrease in cell viability by macroalgae extracts treatment in HINAE cells. These results suggest that S. japonica and G. tenax could be used as potential safe natural anti-inflammatory agents for food and feed additives. Also, the results of this study are expected to be used as basic data for the development of functional materials for 10 kinds of macroalgae resources in Korea.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.709-716
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• 2021

In this study, an adsorbent prepared by natural drying of iron hydroxide-based sludge collected from settling basin at a mine drainage treatment facility located in Gangneung, Gangwon-do was used to remove fluoride in an artificial fluoride solution and mine drainage, and the adsorption characteristics of the adsorbent were investigated. As a result of analyzing the chemical composition, mineralogical properties, and specific surface area of the adsorbent used in the experiment, iron oxide (Fe₂O₃) occupies 79.2 wt.% as the main constituent, and a peak related to calcite (CaCO₃) in the crystal structure analysis was analyzed. It was also identified that an irregular surface and a specific surface area of 216.78 m²·g^-1. In the indoor batch-type experiment, the effect of changes in reaction time, pH, initial fluoride concentration and temperature on the change in adsorption amount was analyzed. The adsorption of fluoride showed an adsorption amount of 3.85 mg·g^-1 16 hours after the start of the reaction, and the increase rate of the adsorption amount gradually decreased. Also, as the pH increased, the amount of fluoride adsorption decreased, and in particular, the amount of fluoride adsorption decreased rapidly around pH 5.5, the point of zero charge at which the surface charge of the adsorbent changes. Meanwhile, the results of the isotherm adsorption experiment were applied to the Langmuir and Freundlich isotherm adsorption models to infer the fluoride adsorption mechanism of the used adsorbent. To understand the thermodynamic properties of the adsorbent using the Van't Hoff equation, thermodynamic constants 𝚫H° and 𝚫G° were calculated using the adsorption amount information obtained by increasing the temperature from 25℃ to 65℃ to determine the adsorption characteristics of the adsorbent. Finally, the adsorbent was applied to the mine drainage having a fluoride concentration of about 12.8 mg·L^-1, and the fluoride removal rate was about 50%.

• Conservation Science in Museum
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• v.29
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• pp.133-152
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• 2023

This study references preceding studies to examine the history of paint application techniques using various paints in the past, with the aim to contribute to the long-term preservation of large military cultural heritage assets situated outdoors. To this end, the study compared the findings of preceding research with the findings of an analysis conducted on a H-13 helicopter housed at the War Memorial of Korea. Upon collecting and analyzing samples from three grounded WWII aircraft from above-ground by preceding studies, it was confirmed from each sample that the various chemical properties of chrome ensured the effectiveness of the protective coating. The compound was first tested as a corrosion-inhibiting pigment in the early 1940s and proved its excellent moisture-resistant properties over the course of 80 years, despite the deterioration of the paint layer and long-term exposure to the natural environment. For this reason, it has been widely used as a corrosion inhibitor for aluminum alloys in the aviation industry. In other word, the most widely-used material for preventing corrosion was an organic primer containing chromate. In this study, based on the paint analysis of a H-13 helicopter operated in the Korean War, it was shown that the second layer, consisting of the primer, contains chromium oxide (Cr₂O₃). In addition, it was estimated that red lead tetraoxide (Pb₃O₄) was used for the vehicle. Analysis results and data from previous studies can help to confirm the continued effectiveness of corrosion prevention function provided by chromate. Meanwhile, the result of infrared spectroscopy analysis confirmed the use of alkyd resin. In the future, comparisons with a more diverse range of artifacts will allow the identification of changes in the manufacturing technology of paints used to protect alloys from corrosion.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.301-310
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• 2023

Ferrihydrite is an iron oxide mineral that is easily found in the natural environment, including acid mine drainage, and has a low crystallinity and high specific surface area, resulting in high reactivity with other ions, and can remove environmentally hazardous substances. However, because ferrihydrite is a metastable mineral, there is a possibility of releasing adsorbed ions by phase transformation to other minerals having low surface area and high crystallinity. In this study, the adsorption characteristics of arsenate, chromate, and selenate on ferrihydrite and the oxyanion removal efficiency of ferrihydrite were studied considering mineral phase transformation. At both pH 4 and 8, the adsorption of oxyanions used in the study were in good agreement with both Langmuir and Freundlich adsorption models except for selenate at pH 8. Due to the difference in surface charge according to pH, at pH 4 a higher amount of ions were adsorbed than at pH 8. The adsorption amount were in the order of arsenate, chromate, and selenate. These different adsorption models and adsorption amounts were due to different adsorption mechanisms for each oxyanions on the surface of ferrihydrite. These adsorption characteristics were closely related to changes in the mineral phase. At pH 4, a phase transformation to goethite or hematite was observed, but only a phase transformation to hematite was observed at pH 8. Among the oxyanion species on ferrihydrite, arsenate showed the highest adsorption capacity and hardly caused phase transformation during the experimental period after adsorption. Contrary to this, chromate and selenate showed faster mineral phase transformation than arsenate, and selenate had the lowest retardation effect among the three oxyanions. Ferrihydrite can effectively remove arsenate due to its high adsorption capacity and low phase transformation rate. However, the removal efficiency for other two oxyanions were low by the low adsorption amount and additional mineral phase transformation. For chromate, the efficient removal is expected only at low concentrations in low pH environments.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.313-321
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• 2023

Numerous studies have investigated the adsorptive sequestration of radioactive cesium in the natural environment. Among these studies, adsorption onto minerals and high-temperature treatment stand out as highly effective, as demonstrated by the use of zeolite. In this study, cesium was ion-exchanged with birnessite and subsequently underwent high-temperature treatment up to 1100℃ to investigate both mineral phase transformation and the leaching characteristics of cesium. Birnessite has a layered structure consisting of MnO₆ octahedrons that share edges, demonstrating excellent cation adsorption capacity. The high-temperature treatment of cesium-ion-exchanged birnessite resulted in changes in the mineral phase, progressing from cryptomelane, bixbyite, birnessite to hausmannite as the temperature increased. This differs from the phase transformation observed in the tunneled manganese oxide mineral todorokite ion-exchanged with cesium, which shows phase transformation only to birnessite and hausmannite. The leaching of cesium from cesium-ion-exchanged birnessite was estimated by varying the reaction time using both distilled water and a 1 M NaCl solution. The leaching quantity changed according to the treatment temperature, reaction time, and type of reaction solution. Specifically, the cesium leaching was higher in the sample reacted with 1 M NaCl compared to the sample with distilled water and also increased with longer reaction time. For the samples reacted with distilled water, the cesium leaching initially increased and then decreased, while in the NaCl solution, the leaching decreased, increased again, and finally nearly stopped like the sample in the distilled water for the sample treated at 1100℃. These changes in leaching are closely associated with the mineral phases formed at different temperatures. The phase transformation to cryptomelane and birnessite enhanced cesium leaching, whereas bixbyite and hausmannite hindered leaching. Notably, hausmannite, the most stable phase occurring at the highest temperature, demonstrated the greatest ability to inhibit cesium leaching. This results strongly suggest that high-temperature treatment of cesium-ion-exchanged birnessite effectively immobilizes and sequesters cesium.

• Journal of Food Hygiene and Safety
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• v.39 no.1
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• pp.44-53
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• 2024

Global interest in natural functional materials to strengthen human immunity is increasing due to the increase in immune-related diseases associated with COVID-19 and the aging population. In this study, we determined the potential therapeutic effect of Eleutherococcus senticosus stems on immune enhancement according to the cultivation region. The contents of eleutheroside B and E, which are chemical components of E. senticosus stems, were analyzed. We showed that the eleutheroside B content of E. senticosus stems in different cultivation regions ranged from 2.96±0.11 to 6.24±0.05 mg/g and from 1.11±0.05 to 2.11±0.03 mg/g in 70% ethanol and hot water extracts, respectively. The eleutheroside E content ranged from 4.93±0.20 to 10.79±0.03 mg/g and 1.75±0.14 to 3.64±0.05 mg/g in 70% ethanol and hot water extracts, respectively. In addition, the immunomodulatory effect of E. senticosus stems was evaluated using RAW 264.7 macrophages. The 70% ethanol extract of E. senticosus stems showed no cytotoxicity up to 200 ㎍/mL, and the hot water extract showed no cytotoxicity up to 500 ㎍/mL. Additionally, the E. senticosus stem extract significantly increased the production of nitric oxide and cytokines (TNF-α, IL-6, and IL-1β) compared to their production in the control group. These results suggest that E. senticosus stem extracts are a potential functional food material and ingredient to enhance the immune response.