• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1753-1755
• /
• 1999

$LaCoO_3$ thick-film sensors were fabricated on alumina substrate by screen printing method. The sensitivity for gases was investigated by varying the heat treatment temperature of the films. X-Ray Diffractions and SEM photographs were used to examine their structural properties. The sensitivity of $LaCoO_3$ thick-film for CO gas was much better than for $C_4H_{10}$, $NH_3$ and NO gases. The best condition of heat treatment was $800^{\circ}C$ and the optimal operating temperature of $LaCoO_3$ thick-film for the highest sensitivity was $150^{\circ}C$. Sensitivities of the $LaCoO_3$ thick-film at 500ppm and l000ppm for CO gas were 72% and 95%, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.19 no.2
• /
• pp.66-69
• /
• 2009

The compositional dependence of bismuth iron oxides and effect of La-substitutions in the structure of $BiFeO_3$ compounds were investigated, which compounds were synthesized by conventional ceramic processing. It is shown that some of bismuth iron oxides including $BiFeO_3$ show the narrow single phase region. The effect of La-doping in $BiFeO_3$ was presented as disappearance of many impurity phases of Bi-Fe-O compounds. The lower electrical resistivity was obtained as those compositions of Fe deficient region and La-doped $BiFeO_3$. The saturation magnetization of La-doped $BiFeO_3$ was increased with La content. The dielectric dispersion was also observed for those Bi-Fe-O compounds with Fe deficient and La-doped $BiFeO_3$ at low frequencies under 1 kHz.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.21 no.2
• /
• pp.97-107
• /
• 2008

Purpose: This study is to examine antioxidant activities of Dioscoreae Rhizoma on HeLa cell Methods: Aqueous extract was used to treat HeLa cell with different concentrations treated with water or MeOH extract of Dioscoreae batatas (0, x10, x20, x40, x80). The MTT reduction assay and flow cytometric analysis was employed to quantify the differences in cell activity and viability. Results: Co-treatment with $H_2O_2$ and Dioscoreae batatas extracts reduced apoptosis of HeLa cells by decreasing G2/M arrest. Dioscoreae batatas extracts increased the survival rate of cells treated with cisplatin and Scutellaria barbata. Conclusion: Our results suggest that Dioscoreae Rhizoma extracts induce cell protective effect by antioxidant activities.

• Journal of the Korean Ceramic Society
• /
• v.45 no.12
• /
• pp.796-801
• /
• 2008

$LaGaO_3$ thin film was prepared on Ni-Fe metal porous substrate by Pulsed Laser Deposition method. By the thermal reduction, the dense $NiO-{Fe_3}{O_4}$ substrate is changed to a porous Ni-Fe metal substrate. The volumetric shrinkage and porosity of the substrate are controlled by the reduction temperature. It was found that a thermal expansion property of the Ni-Fe porous metal substrate is almost the same with that of $LaGaO_3$ based oxide. $LaGaO_3$ based electrolyte films are prepared by the pulsed laser deposition (PLD) method. The film composition is sensitively affected by the deposition temperature. The obtained film is amorphous state after deposition. After post annealing at 1073K in air, the single phase of $LaGaO_3$ perovskite was obtained. Since the thermal expansion coefficient of the film is almost the same with that of LSGM film, the obtained metal support LSGM film cell shows the high tolerance against a thermal shock and after 6 min startup from room temperature, the cell shows the almost theoretical open circuit potential.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.352-355
• /
• 2003

[ $Bi_{3.25}La_{0.75}Ti_3O_{12}$ ] (BLT) thin films were prepared by using metal organic decomposition method onto the LaNiO3 (LNO) bottom electrode. Both the structure and morphology of the films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). Even at low temperatures ranging from 450 to $650^{\circ}C$, the BLT thin films were successfully deposited on LNO bottom electrode and exhibited (117) orientation. The BLT thin films annealed as low as $600^{\circ}C$ showed excellent ferroelectricity, higher remanent polarization and no significant degradation of switching charge at least up to $5{\times}10^9$ switching cycles at a frequency of 100 kHz and 5 V. For the annealing temperature of $600^{\circ}C$, the remanent polarization $P_r$ and coercive field were $23.5\;{\mu}C/cm^2$ and 120 kV/cm, respectively.

• Journal of the Korean Ceramic Society
• /
• v.31 no.5
• /
• pp.513-519
• /
• 1994

Alumina composite was fabricated by introducing tetragonal ZrO2 in alumina composite of $\alpha$-alumina reinforced with in-situ formed La-$\beta$-aluminate (LaAl11O18). The powder mixture of composition (100-x)[88 Al2O3+(La2O3+11 Al2O3)]+x vol% ZrO2 was prepared with x from 0 to 40. Dense composites fabricated by hot-pressing exhibited bending strength up to 1200 MPa. The gain growth inhibiting effect of ZrO2 grains and La-$\beta$-aluminate platelets, and possibly the stress-induced phase transformation of ZrO2 have resulted in the high bending strength. The fracture toughness of the composite also increased up to 8.5 MPa.m1/2. The enhancement in toughness can be explained by transformation and microcrack toughening of ZrO2 and by crack deflection and bridging of La-$\beta$-aluminate platelets and ZrO2.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.43 no.3
• /
• pp.239-245
• /
• 2017

Aging is a physiological and irreversible, progressive process involving changes in the ability to maintain cellular functionality. It affects tissues, organs and the whole organism and thus finally cause to death. Oxidative stress has been postulated to contribute significantly to the accelerated accumulation of advanced glycation endproducts (AGEs) in collagen, which is implicated in the process of skin aging. In the present study, glycation inhibitory activity of methoxy PEG-45 thioctate (LA-PEG), and its inhibitory effect of cellular oxidation and senescence was investigated. Treatment of LA-PEG significantly showed lower fluorescent intensity induced by AGEs. In addition, LA-PEG was significantly reduced the formation of ROS induced by AGEs. High antioxidant and anti-glycation activities of LA-PEG in glycated collagen model indicated its contribution to anti-aging process. Cellular senescence leads to an increase in senescence-associated ${\beta}$-galactosidase ($SA-{\beta}-gal$) activity, which can be used as a biomarker to identify senescent cells. Treatment with LA-PEG showed a dose-dependent, statistically significant decreased in $SA-{\beta}-gal$ indicating reduced senescence. These results suggest that LA-PEG may have potent anti-aging effects and can be used as new functional materials against cellular accumulation of AGEs.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1031-1033
• /
• 1995

The microwave dielectric properties of (1-x)$LaAlO_3-xCaTiO_3$ system were investigated. As the amount of $LaAlO_3$ increased, the value of the unloaded Q increased, but the dielectric constant(${\varepsilon}_r$) decreased. The temperature coefficient of resonant frequency(${\tau}_f$) of $5ppm/^{\circ}C$ was obtained from the composition of $0.35LaAlO_3-0.65CaTiO_3$ in which the values of ${\varepsilon}_r$ and $Q{\cdot}f_o$ were 42 and 32,500, respectively.

• Biomedical Science Letters
• /
• v.21 no.2
• /
• pp.77-83
• /
• 2015

Soy proteins have been extensively studied because of its multiple health benefits. However, the effects of soy proteins on human cervical cancer cells are still unclear. Therefore, this study investigated the effects of soy proteins on HeLa cells and human fibroblasts by using soybean peptides (SPs). SPs selectively increased the generation of reactive oxygen species and apoptosis in HeLa cells but not in fibroblasts. In addition, SPs suppressed the migration of HeLa cells. Although the molecular mechanisms underlying the effects of SPs on human cervical cancer cells need to be investigated further, our findings provide insights on the therapeutic effects of soy protein on cervical cancer.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.1
• /
• pp.25-31
• /
• 2018

To apply Sievert's type apparatus to thermal analysis of hydrogen absorption materials, the dehydrogenation of $LaNi_5$ system was investigated. As the initial wt% of hydrogen was increased from 0.44 to 1.24 wt%, the peak temperature of evolution rate shifted to higher temperature. However, with the initial wt% of hydrogen higher than 0.95 wt%, the peak temperature of evolution rate did not change. As the heating rate was increased, the peak temperature increased; the peak temperatures for heating rates 0.5, 1.0 and 1.5 K/min were 262.2, 264.1, and 265.9 K respectively. The Sievert's type automatic apparatus can be successively applied to the thermal analysis of $LaNi_5$ hydride.