• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.37-44
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• 1995

A coprecipitation method was used for preparing Ca and Pt doped $SnO_{2}$-based material. Crystallite size and specific surface area were investigated by TEM, XRD and BET analysis. $SnO_{2}(Ca)/Pt$ based thick film devices were prepared by a screen printing technique for hydrocarbon gas detecting. Then the electrical and sensing characteristics of devices were investigated. As Ca and Pt addition, the crystal growth of $SnO_{2}$ was suppressed during calcining and sintering, and the sensitivity of $SnO_{2}(Ca)/Pt$ thick film to gas was enhanced. Also any difference in the sensing properties has to be attributed to the Pt and Au electrode. For the 2000 ppm $CH_{4}$, the sensitivity of $SnO_{2}(Ca)/Pt$ thick film devices were about 83% at an operating temperature of $400^{\circ}C$.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.1
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• pp.15-23
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• 2016

Acetaminophen (APAP) overdose is one of the most common causes of acute liver failure. The study aimed to investigate the protective effect of carnosic acid (CA) on APAP-induced acute hepatotoxicity and its underlying mechanism in mice. To induce hepatotoxicity, APAP solution (400 mg/kg) was administered into mice by intraperitoneal injection. Histological analysis revealed that CA treatment significantly ameliorated APAP-induced hepatic necrosis. The levels of both alanine aminotransferase (ALT) and aspartate transaminase (AST) in serum were reduced by CA treatment. Moreover, CA treatment significantly inhibited APAP-induced hepatocytes necrosis and lactate dehydrogenase (LDH) releasing. Western blot analysis showed that CA abrogated APAP-induced cleaved caspase-3, Bax and phosphorylated JNK protein expression. Further results showed that CA treatment markedly inhibited APAP-induced pro-inflammatory cytokines TNF-${\alpha}$, IL-$1{\beta}$, IL-6 and MCP-1 mRNA expression and the levels of phosphorylated $I{\kappa}B{\alpha}$ and p65 protein in the liver. In addition, CA treatment reduced APAP- induced hepatic malondialdehyde (MDA) contents and reactive oxygen species (ROS) accumulation. Conversely, hepatic glutathione (GSH) level was increased by administration of CA in APAP-treated mice. Mechanistically, CA facilitated Nrf2 translocation into nuclear through blocking the interaction between Nrf2 and Keap1, which, in turn, upregulated anti-oxidant genes mRNA expression. Taken together, our results indicate that CA facilitates Nrf2 nuclear translocation, causing induction of Nrf2-dependent genes, which contributes to protection from acetaminophen hepatotoxicity.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.855-860
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• 1993

In the presence of SDS(sodium dodecyl sulfate), effect of $Ca^{2+}$on the interaction of NP-40EO[nonylphenol-(ethylene oxide)40] with iodine in aqueous solution were investigated by UV-visible spectrophotometer. In the presence of SDS, the intensity of interaction peaks were decreased and markedly increased by the addition of $Ca^{2+}$. Decrease of interaction peaks is caused by decrease of EO number to be interact with iodine per unit surface area of mixed micelle to the insertion of SDS and increase is attributed to the compactness of micelle in the presence of $Ca^{2+}$. These phenomena may be explained by the fact that the linear EO (ethylene oxide) chains, to be free in aqueous solution, could form a pseudo-crown ether structures of forming with $Ca^{2+}$ion.

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.471-476
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• 2007

The hydration mechanism of the $3CaO{\cdot}Al_2O_3-CaSO_4{\cdot}2H_2O$ system in the presence of alkali sulfates has been investigated. The early hydration rate of $3CaO{\cdot}Al_2O_3$ was accelerated by the addition of $Na_2SO_4$ and $K_2SO_4$. This is closely related to the formation of syngenite $(CaSO_4{\cdot}K_2SO_4{\cdot}H_2O)$, and the U-phase added $K_2SO_4$ and $Na_SO_4$ in the $3CaO{\cdot}Al_2O_3-CaSO_4{\cdot}2H_2O$ system, respectively. The formation of the rigid syngenite and U-phase structure led to rapid setting and decreases the sulfate content in the liquid phase of the hydrating cement to the extent that it cannot adequately retard the hydration of $3CaO{\cdot}Al_2O_3$. In case of the alkali sulfate not added to the $3CaO{\cdot}Al_2O_3-CaSO_4{\cdot}2H_2O$ system, the ettringite was transformed to monosulfoaluminate immediately after the consumption of gypsum. However, when the alkali sulfates were added to this system, the ettringite did not transform to monosulfoaluminate immediately even though the gypsum was completely consumed. There was a stagnation period to transform to the monosufoaluminate after the consumption of gypsum because the syngenite and U-phase remained as the sulfate source.

• Journal of the Korean Ceramic Society
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• v.36 no.8
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• pp.813-819
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• 1999

Inner crack-like pores with controlled amount of Ca impurity level in the high purity alumina single crystal sapphire had been created by micro-fabrication technique which includes ion implantation photo-lithography Ar ion milling and hot press technique. The morphological change and the healing of crack-like pore in the Ca doped high purity single crystal alumina during high temperature heat treatment in vacuum were observed using optical microscopy. The hexagonal bridging ligaments were developed and the size of hexagonal bridging ligaments had been increased with temperature and Ca amount and had grown to their corner rounded. It appeared that the hexagonal bridging ligaments would have an equilbrium size with temperature and the amount of Ca addition. Three kinds of crack-like pore healing type were observed. Edge regression and ligament growth were observed from relatively low temperature in the crack-like pore. Edge regression were found in almost all of the crack-like pore but the ligament growth were found only in the several crack-like pores accelerating heating very fast. Flow type healing was observed above $1800^{\circ}C$ and It healed the crack-like pore very slowly.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.4
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• pp.375-379
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• 2018

In the present study, we have investigated whether methylated marliolide could induce NRF2 thereby exerting anti-oxidant effects. MTT assay showed that methylated marliolide did not exhibit cytotoxicity on HaCaT cells. Methylated marliolide induced a higher ARE-dependent luciferase activation in HaCaT ARE-GFP-luciferase cells, compared with resveratrol. In addition, exposure of methylated marliolide to HaCaT cells significantly induced NRF2 and transcriptionally activated HO-1 and NQO1, both of which are target genes of NRF2. Finally, methylated marliolide protected HaCaT cells against TPA-induced oxidative damages on nucleotides and lipids. Together, results shows that methylated marliolide could suppress oxidative damages through induction of NRF2 which implies that methylated marliolide might serve as a good candidate for novel cosmetic ingredient with anti-oxidant effects.

• The Korea Journal of Herbology
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• v.32 no.3
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• pp.55-61
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• 2017

Objectives : The aim of this research was to determine the diverse effects of Lithospermi Radix Water Extract (LR) on human keratinocyte HaCaT cells, and to examine whether those effects could be applied to the human skin. Methods : We examined effect of LR on the cell viability of using the MTS assay in human keratinocyte HaCaT cells. The antioxidation effect of LR was analyzed relative to the well-known antioxidant resveratrol, using an ABTS assay. Quantitative RT-PCR analysis revealed that, in HaCaT cells, LR influenced the mRNA expression of tight-junction genes associated with skin moisturization. Furthermore, a wound-healing assay demonstrated altered cell migration in LR-treated HaCaT cells. Result : The cytotoxicity was confirmed to be higher in LR at a concentration of $800{\mu}g/m{\ell}$ using the MTS assay in HaCaT cells. In comparison to $100{\mu}M$ resveratrol, $1,600{\mu}g/m{\ell}$ LR showed either a similar or superior antioxidation effect. LR treatment in HaCaT cells reduced the mRNA expression levels of claudin 3, claudin 4, claudin 6, claudin 8, and ZO-2 to less than 0.80-fold, whereas JAM-A and Tricellulin mRNA expression level increased more than 1.33-fold. In addition, HaCaT cells migration was decreased to 83.9% by LR treatment. Conclusions : LR of antioxidation activity will have an anti-aging effect on the skin by reducing oxidative stress. Further studies are required to address the implications for human skin, given LR's effects of altering mRNA expression of tight junction-related gene and decreasing cell migration of HaCaT cells.

• New & Renewable Energy
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• v.19 no.1
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• pp.1-11
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• 2023

A large amount of carbon monoxide (CO) is generated in circulating fluidized bed combustion, the process whereby a hot cyclone separates unburned fuel. However, calcium sulfate (CaSO₄), when combined with a high CO content, can cause fouling on the surface of the steam tube installed inside the integrated recycle heat exchangers (INTREX). In this study, CaSO₄ decomposition was investigated using 0.2-3.2 vol.% CO and 1-3 vol.% oxygen (O₂) at 850℃ for 20 min in a lab-scale fluidized bed reactor. The results show that CaSO₄ decomposes into CaS and CaO when CO gas is supplied, and SO₂ emissions increase from 135 ppm to 1021 ppm with increasing CO concentration. However, the O₂ supply delayed SO₂ emissions because the reaction between CO and O₂ is faster than that of CaSO₄; nevertheless, when supplied with CaCO₃, the intermediate product, SO₂ was significantly released, regardless of the CO and O₂ supply. In addition, agglomerated solids and yellow sulfur power were observed after solid recovery, and the reactor distributor was corroded. Consequently, a sufficient O₂ supply is important and can prevent fouling formation on the INTREX surface by suppressing CaSO₄ degradation.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.51-53
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• 1999

The crystallization mechanism of an amorphous $Bi_{2}$$Sr_{2}$$Ca_{2 x}$$Cd_{x}$$Cu_{3}$$O_{y}$ phase were studied from the relations between crystallization and volume changes by dilatometry. Further, the effect of addition of CdO on the crystallization mechanism and superconductivity was discussed. The shrinkage of the amorphous $Bi_{2}$$Sr_{2}$$Ca_{2 x}$$Cd_{x}$$Cu_{3}$$O_{y}$ occurred with the crystallization of $Bi_{2}$$Sr_{2}$Cu$O_{6}$ phase decrease with increasing CdO content with a minimum at x=0.4. Better superconductivity was obtained in the specimens formation less amount of the$Bi_{2}$$Sr_{2}$Cu$O_{6}$ phase during the crystallization process.

• Journal of the Korean Ceramic Society
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• v.28 no.4
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• pp.289-296
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• 1991

Hydroxyapatite (HAp)-zirconia bioceramics, which have excellent biocompatibility with tissue of bone and tooth and good mechanical properties, were synthesized, and their properties and biocompatibility were investigated. HAp powders were synthesized with Ca/P=1.67 and pH 11 by precipitation method. A fine spherical monodispersed ZrO2 powders were prepared by metal alkoxide method, and then they were partially stabilized with 10 mol% CaO by solid state reaction at 1300℃. HAp-zirconia composites were prepared by sintering of these HAp mixed with various amount CaO-partially stabillized zirconia (PSZ). When HAp containing 15 wt% PSZ with 10 mol% CaO (PSZ(10C)) were sintered at 1250℃, it was prevented to decompose into TCP and ZrO2 was uniformly dispersed at HAp matrix. Mechanical strength of these sintered bodies were increased by addition of 15 wt% PSZ(10C), the bending strength of compacts fired at 1250℃ was 165 MPa. HAp-PSZ composites chemically bonded each other in Ringer's solution and the component of bonded layer was HAp. These composites did not prevent cell-growing and exhibit any cytotoxic effects.