• Clean Technology
• /
• v.29 no.3
• /
• pp.185-192
• /
• 2023

This study was conducted to obtain basic process simulation data before conducting pyrolysis experiments for the development of a thermochemical conversion system by recirculation of heat carrier and gases thereby. In this study, polypropylene (PP) was used as a pyrolysis sample material as an alternative to waste plastics, and fluid sand was used as a heat transfer medium in the system. Manganese (Mn) was chosen as the catalyst for the pyrolysis experiment, and the catalyst pyrolysis was performed by impregnating it in the sand. The basic properties of PP were analyzed using a thermogravimetric analyzer (TGA), and liquid oil was generated through catalytic pyrolysis under a nitrogen atmosphere at 600℃. The carbon number distribution of the generated liquid oil was confirmed by GC/MS analysis. In this study, the effects of the presence and the amount of Mn loading on the yield of liquid oil and the distribution of hydrocarbons in the oil were investigated. When Mn/sand was used, the residue decreased and the oil yield increased compared to pyrolysis using sand alone. In addition, as the Mn loading increased, the ratio of C₆~C₉ range gasoline in the liquid oil gradually increased, and the distribution of diesel and heavy oil with more carbon atoms than C₁₀ in the oil decreased. In conclusion, it was found that using Mn as a catalyst and changing the amount of Mn could increase the yield of liquid oil and increase the gasoline ratio in the product.

• 한국체육학회지인문사회과학편
• /
• v.51 no.3
• /
• pp.437-445
• /
• 2012

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and manganese superoxide dismutase (MnSOD) has been hypothesized as a mediator in the activation of multiple pathways implicated in the pathogenesis of diabetic disease. The objective of this study was to understand the mechanism that aerobic exercise activate GAPDH and MnSOD in pancreatic cells. To achieve the purpose of this study, thirty male Sprague-Dawley rats were assigned to control group, diabetic group and diabetic exercise group. 10 rats were forced to exercise according to exercise protocol for 8weeks and 20 rats were untrained for control and diabetic group. Pancreatic tissue were extracted from the each. Expressions of GAPDH and MnSOD in diabetic pancreatic tissues were significantly decreased compare to control group. However, swimming (trained diabetic group) significantly increased expressions of GAPDH and MnSOD compare to diabetic group, respectively. In hyperglycemia, GAPDH and MnSOD in pancreatic cells is activated by aerobic exercise, and this inactivates multiple pathways implicated in the pathogenesis of diabetic disease. In conclusion, these findings suggest that increased activity of GAPDH and MnSOD by exercise have beneficial effects on mitochondrial dysfunction and arresting the progression of diabetic disease.

• Korean Journal of Mineralogy and Petrology
• /
• v.36 no.1
• /
• pp.33-40
• /
• 2023

Todorokite is a manganese oxide mineral containing Mg²⁺ in a tunnel structure in which MnO₆ octahedra share corners. In order to investigate the suitability and efficiency of high temperature-treated todorokite as a material for adsorption and fixation of Cs, Cs was ion exchanged and the amount of leached Cs from todorokite was measured. The todorokite used in this study was synthesized by transforming Na-birnessite to Mg-buserite and used as a precursor. After high temperature treatment, Cs exchanged todorokite changed to birnessite and hausmannite as the temperature increased. The amount of leached Cs was investigated for Cs exchanged todorokite which was reacted with distilled water and 1 M NaCl solution at different reaction times. In general, for the samples reacted with 1 M NaCl solution, the fixation of Cs was quite effective, although the amount of leached Cs was greater due to the ion exchange reaction with Na. As the treatment temperature increased, the amount of leached Cs increased and then decreased again, which was related to the mineral phases formed at each temperature. As birnessite was formed, the amount of leached Cs increased, but as birnessite decreased, that decreased again. As the mineral phase changed to hausemanite, the amount of Cs decreased rapidly. The results of our study show that Cs exchanged todorokite can be used as a material that effectively fixes Cs and prevents its diffusion by high temperature treatment.

• Resources Recycling
• /
• v.32 no.1
• /
• pp.21-32
• /
• 2023

Because the application of lithium has gradually increased for the production of lithium ion batteries (LIBs), more research studies about recycling using solvent extraction (SX) should focus on Li⁺ recovery from the waste solution obtained after the removal of the valuable metals nickel, cobalt and manganese (NCM). The raffinate obtained after the removal of NCM metal contains lithium ions and other impurities such as Na ions. In this study, we optimized a selective SX system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and tri-n-butyl phosphate (TBP) as a modifier in kerosene for the recovery of lithium from a waste solution containing lithium and a high concentration of sodium (Li⁺ = 0.5 ~ 1 wt%, Na⁺ = 3 ~6.5 wt%). The extraction of lithium was tested in different solvent compositions and the most effective extraction occurred in the solution composed of 20% D2EHPA + 20% TBP + and 60% kerosene. In this SX system with added NaOH for saponification, more than 95% lithium was selectively extracted in four extraction steps using an organic to aqueous ratio of 5:1 and an equilibrium pH of 4 ~ 4.5. Additionally, most of the Na⁺ (92% by weight) remained in the raffinate. The extracted lithium is stripped using 8 wt% HCl to yield pure lithium chloride with negligible Na content. The lithium chloride is subsequently treated with high purity ammonium bicarbonate to afford lithium carbonate powder. Finally the lithium carbonate is washed with an adequate amount of water to remove trace amounts of sodium resulting in highly pure lithium carbonate powder (purity > 99.2%).

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.95-95
• /
• 2022

Maize is one of the world's three largest crops and has a long cultivation history, and is an important crop used for various purposes such as food, feed, and industrial raw materials. Recently, the agricultural environment is changing, in which the limit of cultivation of crops is shifted to the north due to the rise in temperature due to climate change. This study was conducted in experimental field of Suwon in 2022 by setting a seeding period earlier than the sowing time to establish the North Korean agricultural climatic zone and meteorological conditions. The test cultivars were silage cultivars, Kwangpyeongok and Dacheongok. As a priming test method, it was used to directly plant seeds in the field through immersion using 4mM zinc (Zn) and 2.5mM manganese (Mn), which are trace elements for seeds. The planting season was early on March 15th, April 1st, and April 15th. The number of days from sowing to silk stage of the two cultivars sown on March 15, April 1, and April 15 was 107, 93, and 85 days for Kwangpyeongok and 109, 95, and 87 days for Dacheongok, respectively. The seed priming test did not show any difference from the control group in the growth survey up to the middle stage of growth. In another test, low-temperature recovery was confirmed through nitrogen (2-5%) foliar fertilization after 3 days, 5 days, and 7 days in refrigeration (0 degrees), a selective low temperature treatment for com in the third leaf stage. As a result of this study, it was confirmed that the low-temperature damaged com treated at 0℃ showed the same growth as that of the untreated com through nitrogen foliar fertilization. These results suggest that urea foliar fertilization for low-temperature damage reduction of corn for silage in high-latitude climates will be helpful. In addition, through the results of the study, additional studies are needed on the recovery mechanism and field application through urea foliar fertilization.

• Restorative Dentistry and Endodontics
• /
• v.48 no.4
• /
• pp.39.1-39.23
• /
• 2023

Objectives: This study aimed to investigate the effectiveness of different topical/systemic agents in reducing the damage caused by bleaching gel to pulp tissue or cells. Materials and Methods: Electronic searches were performed in July 2023. In vivo and in vitro studies evaluating the effects of different topical or systemic agents on pulp inflammation or cytotoxicity after exposure to bleaching agents were included. The risk of bias was assessed. Results: Out of 1,112 articles, 27 were included. Nine animal studies evaluated remineralizing/anti-inflammatories agents in rat molars subjected to bleaching with 35%-38% hydrogen peroxide (HP). Five of these studies demonstrated a significant reduction in inflammation caused by HP when combined with bioglass or MI Paste Plus (GC America), or following KF-desensitizing or Otosporin treatment (n = 3). However, orally administered drugs did not reduce pulp inflammation (n = 4). Cytotoxicity (n = 17) was primarily assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human dental pulp cells and mouse dental papilla Cell-23 cells. Certain substances, including sodium ascorbate, butein, manganese chloride, and peroxidase, were found to reduce cytotoxicity, particularly when applied prior to bleaching. The risk of bias was high in animal studies and low in laboratory studies. Conclusions: Few in vivo studies have evaluated agents to reduce the damage caused by bleaching gel to pulp tissue. Within the limitations of these studies, it was found that topical agents were effective in reducing pulp inflammation in animals and cytotoxicity. Further analyses with human pulp are required to substantiate these findings.

• Animal Bioscience
• /
• v.36 no.11
• /
• pp.1709-1717
• /
• 2023

Objective: A pivotal study was designed to investigate the effect of Hydroxy (HYC) Cu, Zn, and Mn on egg quality and laying performance of chickens under tropical conditions. Methods: A total of 1,260 Babcock White laying hens (20-wk-old) were randomly assigned to one of 4 treatments with 15 replicates of 21 hens each in a Randomized Complete Block Design. The birds were reared for 16 weeks and were fed the corn-soybean meal diets supplemented with one of the following mineral treatments: T1, inorganic (INO, 15 ppm CuSO4, 80ppm MnSO4 and 80 ppm ZnO); T2, Hydroxy-nutritional level (HYC-Nut, 15 ppm Cu, 80 ppm Mn, 80 ppm Zn from Hydroxy); T3, Hydroxy-Low (HYC-Low, 15 ppm Cu, 60 ppm Mn, 60 ppm Zn from Hydroxy); T4, Hydroxy plus inorganic (HYC+INO, 7.5 ppm HYC Cu+7.5 ppm CuSO4, 40 ppm HYC ZnO+40 ppm ZnSO4, 40 ppm HYC Mn+40 ppm MnSO4). The egg production was recorded daily, while the feed consumption, feed conversion ratio (FCR) and egg mass were determined at the end of each laying period. The egg quality parameters were assayed in eggs collected over 48 h in each laying period. Results: Overall, no significant effect of treatments was observed on percent egg production, egg weight and FCR (p>0.05). Feed intake was significantly lower in birds fed Hydroxy plus inorganic (p<0.05) diet. The supplementation of HYC-Low significantly increased the egg mass compared to the other treatments (p<0.05). HYC supplementation alone or in combination with INO elicited a positive effect on shell thickness, shell weight, shell weight per unit surface area, yolk colour, albumen and yolk index for a certain period (p<0.05), but not throughout the whole laying period. Conclusion: Dietary supplementation of HYC-Low (15-60-60 mg/kg) showed similar effects on production performance and egg quality characteristics in laying hens as compared to 15-80-80 mg/kg of Cu-Zn-Mn from inorganic sources. This indicates that sulphate based inorganic trace minerals can effectively be substituted by lower concentration of hydroxyl minerals.

• Resources Recycling
• /
• v.32 no.6
• /
• pp.67-78
• /
• 2023

The rare metals used as raw materials in high-tech industries undergo changes in demand structures and supply chains following domestic industrial structural shifts and technological advancements, exhibiting high price volatility. Therefore, it is necessary to periodically analyze changes in the demand structures of rare metals. Since domestic demand for most rare metals relies on imports in Korea, the changes in domestic demand for rare metals can be identified by analyzing changes in their trade structure. In the present study, we analyze the changes in trade volume, trade growth rate, trade rankings, and trading countries from 2000 to 2022 for 35 rare metals, categorized into five types-ores, metals, alloys, compounds, and scrap. The trade of the raw materials of rare metals in Korea has generally increased since the 2000s, except for a significant decline in 2009 and 2016. The total trade volume, encompassing both exports and imports, has increased by approximately tenfold in 2022 compared to 2001. Until the mid-2010s, the trade of the raw materials of rare metals was primarily focused on those used in steel-manufacturing such as silicon, nickel, chrome, molybdenum, manganese, and others. However, after that period, there has been an increase in the trade of platinum group metals like palladium, rhodium, platinum, and the raw materials of rare metals for secondary battery-manufacturing such as lithium and cobalt. Particularly in 2022, lithium has become the largest share in trade of the raw materials of rare metals in Korea, due to the price surge and increase in demand.

• Resources Recycling
• /
• v.33 no.1
• /
• pp.58-68
• /
• 2024

Critical minerals such as nickel, cobalt and lithium, are known as materials for cathodic active materials of lithium ion batteries. The consumption of the minerals is expected to grow with increasing the demands of electric vehicles, resulting from carbon neutrality. Especially, the demand for LIB (lithium ion battery) recycling is expected to increase to meet the supply of nickel, cobalt and lithium for LIB. The recycling of EOL (end-of-life) LIB can be achieved by leaching EOL LIB using inorganic acid such as HCl, HNO₃ and H₂SO₄, which are regarded as hazardous materials. In the present study, the potential use of MSA (Methanesulfonic acid), as an alternative lixiviant replacing sulfuric acid was investigated. In addition, leaching behaviors of NCM black mass leaching with MSA was also investigated by studying various leaching factors such as chemical concentration, leaching time, pulp density (P/D) and temperatures. The leaching efficiency of nickel (Ni), cobalt (Co), lithium (Li), and manganese (Mn) from LIB was enhanced by increasing concentration of lixiviant and reductant, leaching time and temperature. The maximum leaching of the metals was above 99% at 80℃. In addition, MSA can replace sulfuric acid to recover Ni, Co, Li, Mn from NCM black mass.

• Biomolecules & Therapeutics
• /
• v.32 no.3
• /
• pp.329-340
• /
• 2024

Mangiferin is a kind of natural xanthone glycosides and is known to have various pharmacological activities. However, since the beneficial efficacy of this compound has not been reported in retinal pigment epithelial (RPE) cells, this study aimed to evaluate whether mangiferin could protect human RPE ARPE-19 cells from oxidative injury mimicked by hydrogen peroxide (H₂O₂). The results showed that mangiferin attenuated H₂O₂-induced cell viability reduction and DNA damage, while inhibiting reactive oxygen species (ROS) production and preserving diminished glutathione (GSH). Mangiferin also antagonized H₂O₂-induced inhibition of the expression and activity of antioxidant enzymes such as manganese superoxide dismutase and GSH peroxidase, which was associated with inhibition of mitochondrial ROS production. In addition, mangiferin protected ARPE-19 cells from H₂O₂-induced apoptosis by increasing the Bcl-2/Bax ratio, decreasing caspase-3 activation, and blocking poly(ADP-ribose) polymerase cleavage. Moreover, mangiferin suppressed the release of cytochrome c into the cytosol, which was achieved by interfering with mitochondrial membrane disruption. Furthermore, mangiferin increased the expression and activity of heme oxygenase-1 (HO-1) and nuclear factor-erythroid-2 related factor 2 (Nrf2). However, the inhibition of ROS production, cytoprotective and anti-apoptotic effects of mangiferin were significantly attenuated by the HO-1 inhibitor, indicating that mangiferin promoted Nrf2-mediated HO-1 activity to prevent ARPE-19 cells from oxidative injury. The results of this study suggest that mangiferin, as an Nrf2 activator, has potent ROS scavenging activity and may have the potential to protect oxidative stress-mediated ocular diseases.