• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.251-260
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• 2023

The construction of free-form structures with intricate curved exteriors necessitates the use of bespoke molds. To fulfill this requirement, a blend of Phase Change Material(PCM) and Ultra-High Performance Concrete(UHPC) is utilized. PCM endows the solution with recyclability, while UHPC facilitates the effortless execution of curvature in the mold fabrication process. However, it's worth mentioning that the melting point of PCM hovers around 58-64℃, and the heat emanating from UHPC's hydration process can potentially jeopardize the integrity of the PCM mold. Hence, experimental validation of the mold shape is a prerequisite. In the conducted experiment, UHPC was poured into two distinct mold types: one that incorporated a 3mm silicone sheet mounted on the fabricated PCM mold(Panel A), and the other devoid of the silicone sheet(Panel B). The experimental outcomes revealed that Panel A possessed a thickness of 3.793mm, while Panel B exhibited a thickness of 5.72mm. This suggests that the mold lacking the silicone sheet(Panel B) was more susceptible to the thermal effects of hydration. These investigations furnish invaluable fundamental data for the manufacturing of ultra-high strength irregular panels and PCM molds. They contribute substantially to the enrichment of comprehension and application of these materials within the realm of construction.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1529-1535
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• 1999

This study was done for the extraction of carotenoid from Phaffia rhodozyma in combination with PEF and other methods. PEF treatment conditions were $30{\sim}80\;kV/cm,\;100{\sim}1000\;Hz\;and\;100{\sim}1000\;{\mu}s$. In order to increase permeability of yeast cell wall, various methods such as freezing-thawing, mechanical treatment, solvents, permeabilizing agents, and yeast cell wall lytic enzyme were used before PEF treatment. The combination of PEF $(50\;kV/cm,\;300\;Hz,\;1000\;{\mu}s)$ and conventional methods such as solvent and freezing-thawing pre-treatment had no effects on the extraction of carotenoid pigments. The extent of extracted carotenoid by the PEF $treatment(50\;kV/cm,\;300\;Hz,\;1000\;{\mu}s)$ combined with yeast cell wall lytic enzyme and mechanical pre-treatment increased 52% and 69.8% more than the sum of that by each treatment, respectively. Permeabilizing agents, especially Tween 20 and capric acid, enhanced the extraction efficiency of carotenoid pigments from P. rhodozyma cells. These results indicated the feasibility for the continuous extracting carotenoid pigments from P. rhodozyma by PEF combined with other permeabilizing methods.

• Tuberculosis and Respiratory Diseases
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• v.40 no.3
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• pp.236-249
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• 1993

Background: Among the injurious agents to which the lung airspaces are constantly exposed are reactive species of oxygen. It has been widely believed that reactive oxygen species may be implicated in the etiology of lung injuries. In order to elucidated how this oxidant causes lung cell injury, we investigated the effects of exogenous $H_2O_2$ on alveolar epithelial barrier characteristics. Methods: Rat type II alveolar epithelial cells were plated onto tissue culture-treated polycarbonate membrane filters. The resulting confluent monolayers on days 3 and 4 were mounted in a modified Ussing chamber and bathed on both sides with HEPES-buffered Ringer solution. The changes in short-circuit current (Isc) and monolayer resistance (R) in response to the exogenous hydroperoxide were measured. To determine the degree of cellular catalase participation in protection against $H_2O_2$ injury to the barrier, experiments were repeated in the presence of 20 mM aminotriazole (ATAZ, an inhibitor of catalase) in the same bathing fluid as the hydroperoxide. Results: These monolayers have a high transepithelial resistance (>2000 ohm-$cm^2$) and actively transport $Na^+$ from apical fluid. $H_2O_2$(0-100 mM) was then delivered to either apical or basolateral fluid. Resulting indicated that $H_2O_2$ decreased Isc and R gradually in dose-dependent manner. The effective concentration of apical $H_2O_2$ at which Isc (or R) was decreased by 50% at one hour ($ED_{50}$) was about 4 mM. However, basolateral $H_2O_2$ exposure led to $ED_{50}$ for Isc (and R) of about 0.04 mM. Inhibition of cellular catalase yielded $ED_{50}$ for Isc (and R) of about 0.4 mM when $H_2O_2$ was given apically, while $ED_{50}$ for basolateral exposure to $H_2O_2$ did not change in the presence of ATAZ. The rate of $H_2O_2$ consumption in apical and basolateral bathing fluids was the same, while cellualr catalase activity rose gradually with time in culture. Conclusion: Our data suggest that basolateral $H_2O_2$ may affect directly membrane component (e.g., $Na^+,\;K^+$-ATPase) located on the basolateral cell surface. Apical $H_2O_2$, on the other hand, may be largely degraded by catalase as it passes through the cells before reaching these membrane components. We conclude that alveolar epithelial barrier integrity as measured by Isc and R are compromised by $H_2O_2$ being relatively sensitive to basolateral (and insensitive to apical) $H_2O_2$.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.627-635
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• 2019

Cement-asbestos slate is the main asbestos containing material. It is a product made by combining 10~20% of asbestos and cement components. Man- and weathering-induced degradation of the cement-asbestos slates makes them a source of dispersion of asbestos fibres and represents a priority cause of concern. When the asbestos enters the human body, it causes cellular damage or deformation, and is not discharged well in vitro, and has been proven to cause diseases such as lung cancer, asbestos, malignant mesothelioma and pleural thickening. The International Agency for Research on Cancer (IARC) has designated asbestos as a group 1 carcinogen. Currently, most of these slats are disposed in a designated landfill, but the landfill capacity is approaching its limit, and there is a potential risk of exposure to the external environment even if it is land-filled. Therefore, this study aimed to exam the possibility of detoxification of asbestos-containing slate by using exothermic reaction and heat treatment. Cement-asbestos slate from the asbestos removal site was used for this experiment. Exothermic catalysts such as calcium chloride(CaCl₂), magnesium chloride(MgCl₂), sodium hydroxide(NaOH), sodium silicate(Na₂SiO₃), kaolin[Al₂Si₂O₅(OH)₄)], and talc[Mg₃Si₄O₁₀(OH)₂] were used. Six catalysts were applied to the cement-asbestos slate, respectively and then analyzed using TG-DTA. Based on the TG-DTA results, the heat treatment temperature for cement-asbestos slate transformation was determined at 750℃. XRD, SEM-EDS and TEM-EDS analyses were performed on the samples after the six catalysts applied to the slate and heat-treated at 750℃ for 2 hours. It was confirmed that chrysotile[Mg₃Si₂O₅(OH₅)] in the cement-asbestos slate was transformed into forsterite (Mg₂SiO₄) by catalysts and heat treatment. In addition, the change in the shape of minerals was observed by applying a physical force to the slate and the heat treated slate after coating catalysts. As a result, the chrysotile in the cement-asbestos slate maintained fibrous form, but the cement-asbestos slate after heat treatment of applying catalyst was broken into non-fibrous form. Therefore, this study shows the possibility to safely verify the complete transformation of asbestos minerals in this catalyst- and temperature-induced process.

• Journal of Life Science
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• v.16 no.5
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• pp.840-849
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• 2006

Severe brain injuries induced by toxin pose one of the most important problems on our health care because of their high morbidity and mortality, are implicated to leucocyte infiltration more premature or immature brain than mature brain. Chemokines are the induction meditators for infiltration of inflammatory cells to the inflammation sites. In order to study the mechanism of leucocyte infiltration, the expression of several chemokines, MCP-1, $MIP-1{\alpha}$ and MIP-2 was studied in lipopolysaccharide(LPS)-stimulated neonatal and adult brain. One week old Sprague-Dawley rats or adult male rats weighing 300-350 g were used for the experiment. After anesthetization, $1\;{\mu}l$ LPS (0.5 mg/ml) subsequently was injected in the right caudate nucleus of the brain with stereotaxic frame. Animals were sacrificed at 6 hours, 24 hours, and 72 hours after injection. The present study was carried out using RT-PCR for the mRNA and immunohistochemistry for the expression of the proteins. In the neonatal rat brain, prominent interstitial edema with significant accumulation of leukocytes was detected at 24 and 72 hours after LPS injection. A semiquantitative analysis of RT-PCR revealed that the MCP-1, $MIP-1{\alpha}$, and MIP-2 mRNA expression peaked at 24 hours in neonatal and adult rat brain. Neonatal rats showed about 2.6, 1.4, and 1.2 times more expression of the MCP-1, $MIP-1{\alpha}$, and MIP-2 than that of the adult rats in the brain tissue. Immunohistochemical analysis also showed that MCP-1 immunoreactivity was paralleled with the RT-PCR results. MCP-1 protein was significantly detected at 24 and 72 hours in the brain parenchyma. $MIP-1{\alpha}$protein was highly expressed at 24 hours. The results of leukocyte infiltration in H&E stain was parallelled with that of the immunohistochemistry. Chemokine proteins were markedly detected at 24 hours after injection of LPS and neutrophil influx into intraparenchymal was prominent at 24 hours. These results suggest that the leukocyte infiltration in the intracranial infection may be controlled by mechanisms influenced by chemokine producing cells in the central nervous system such as microglia, astrocyte and endothelial cell.