• Korean Journal of Crystallography
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• v.16 no.2
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• pp.128-137
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• 2005

We report on the phase transitions of the perovskite nanostructures made by sol-gel template synthesis. The lead titanate ($PbTiO_{3}$) nanostructures were prepared with a chelate sol-gel of titanium tetrabutoxide ($Ti(O^{i}Pr){4}$) and lead acetate ($Pb(OAc)_{2}-3H_{2}O$). $Whatman^{\circledr}$ anodisc membranes (with about 200 nm pore size) served as the template. The template was dipped into the sol, allowed to air dry, and then calcined at $650^{\circ}C$. We have characterized the temperatures of the phase transitions in the $PbTiO_{3}$ nano-structures using DSC, DTA, and second harmonic generation (SHG).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.3
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• pp.193-200
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• 2017

Objectives: This study was performed to evaluate the neurototoxicity of the environmental pollutant lead acetate(LA) and the protective effect of the D-2-amino-5-phosphonovaleric acid(APV), N-methyl-D-aspartate(NMDA) receptor antagonist on LA-induced cytotoxicity in cultured C6 glioma cells. Materials and Methods: For this study, cell viability in cultured C6 glioma cells was assessed by XTT assay and antioxidative effect, such as lactate dehydrogenase(LDH) activity, by LDH detection kit. Results: LA significantly decreased cell viability in a dose-dependent manner, and the XTT50 value was determined to be 33.3 uM of LA. The cytotoxicity of LA was deemed highly toxic according to Borenfreund and Puerner's toxic criteria. The vitamin E antioxidant significantly increased cell viability damaged by LA-induced cytotoxicity in these cultures. For the protective effect of APV on LA-induced cytotoxicity, APV significantly increased not only cell viability, but also inhibition of LDH activity. From these results, it is suggested that oxidative stress is involved in the neurotoxicity of LA, and APV effectively protected against LA-induced cytotoxicity via an antioxidative effect as an inhibotory activity of LDH. Conclusions: Natural resources like APV may be putative therapeutic agents for the toxic diminution of environmental pollutants such as LA correlated with oxidative stress.

• Journal of Microbiology and Biotechnology
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• v.6 no.5
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• pp.315-320
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• 1996

The role of glyoxylate bypass in a lysine-producing Corynebacterium lactofermentum strain was analyzed. Unlike the wild type, the strain expressed enzymes of glyoxylate bypass during growth in the fermentation broth containing glucose as the carbon source. To evaluate the importance of glyoxylate bypass in the strain, we disrupted chromosomal aceA by using a cloned fragment of the gene. Site-specific disruption of aceA which codes for the isocitrate lyase, the first enzyme of the bypass, was confirmed by Southern blot analysis. The aceA mutant strain completely lost isocitrate lyase activity and ability to grow in a minimal medium containing acetate as the sole carbon source. The mutant strain was similar to its parental strain in growth characteristics and produced comparable amounts of lysine in shake flasks containing glucose as the carbon source. The amount of oxaloacetate accumulated in the fermentation medium was similar for both strains, suggesting that expression of glyoxylate bypass does not necessarily lead to the increase in intracellular oxaloacetate. These data clearly demonstrate that glyoxylate bypass does not function as one of the routes of carbon supply for lysine production in the strain. It appears that the leakiness of the glyoxylate bypass in the strain might be the result of a secondary mutation which arose during previous strain development by random mutagenesis.

• Journal of Oral Medicine and Pain
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• v.8 no.1
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• pp.33-41
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• 1983

The authors observed the ultrastructure of oral leukoplakia simplex of gingiva, buccal mucosa, tongue and alveolar ridge. For the purpose of clearly defining the lesions under investigation in this study, leukoplakias were cinsidered to be any white patches on the oral mucous membranes that could not be removed by rubbing and could not be classified clinically or microscopically as another diagnosable disease. The tissue to be examined were embedded in paraffin for light microscopic study. The tissue to be examined under the electronomicroscope were fixed in 2.5% glutaraldehyde in 0.1M cacodylate buffer and 1% osmic acid in 0.1M cacodylate buffer, dehydrated with guaded alchol, and treated with propylene oxide, and embedded in Epon.Ultrathin sections were obtained by LKB III ultrotome, stained with uranyl acetate/lead citrate, and examined with Corinth 500EM. The results were as follows : 1. Epithelium of leukoplakia consisted of stratum basale, stratum spinosum, stratum granulosum and stratum corneum. 2. There was hyperorthokerotosis or hyperparakeratosis. 3. Granular cells contained a lot number of membrane coating granule showing lamellar structure, clearing ot codensation, and a lot of keratohyaline granule varied in size. 4. An increased concentration of tonofilaments and an increased number of desmosomes were found in the stratum spinosum. 5. Basal lamina generally showed its continuity, but in some locatoins, its interreption and multiplication appeared.

• Archives of Pharmacal Research
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• v.29 no.9
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• pp.746-751
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• 2006

Amentoflavone is a plant biflavonoid that was isolated from an ethyl acetate extract of the whole plant of Selaginella tamariscina (Beauv.) spring. 1D and 2D NMR spectroscopy including DEPT, HMQC, and HMBC were used to determine its structure. Amentoflavone exhibited potent antifungal activity against several pathogenic fungal strains but had a very low hemolytic effect on human erythrocytes. In particular, amentoflavone induced the accumulation of intracellular trehalose on C. albicans as a stress response to the drug, and disrupted the dimorphic transition that forms pseudo-hyphae during pathogenesis. In conclusion, amentoflavone has great potential to be a lead compound for the development of antifungal agents.

• Journal of the Korean Ceramic Society
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• v.30 no.9
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• pp.695-700
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• 1993

In this study, we prepared Pb-Ti stock solution by sol-gel processing and deposited PbTiO3 thin film on a Pt coated SiO2/Si wafer by spin coating using the stock solution. We used lead acetate trihydrate and titanium isopropoxide. The stock solution was partially hydrolized and finally a 0.25M coating solution was prepared. We achieved spin coating at 4000rpm for 30 seconds and heated the thin film at 375$^{\circ}C$ for 5 minutes and at $600^{\circ}C$ for 5 minutes successively, first and second heating state. And the thin film was finally sintered at 90$0^{\circ}C$ for 1 hour in the air. The upper electrode of the thin film was made by gold sputtering and was cricle shape with radius 0.4mm. Measured dielectric constant, dissipation factor and phase transition temperature(Cuire Temp.) were about 275, 0.02 and 521$^{\circ}C$ respectively. To observe ferroelectric characteristics we calculated Pr(remnant polarization) and Ec(coercive field) byhysteresis curve. Ec was 72kV/cm and Pr was 11.46$\mu$C/$\textrm{cm}^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.20-20
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• 2010

The effect of excimer laser annealing on the structural and dielectric behaviors of $PbZr_{0.52}Ti_{0.48}O_3$ (PZT) thin films has been investigated. The amorphous PZT thin films were prepared on Pt/Ti/$SiO_2$/Si substrates by a sol-gel method. The PZT precursor was prepared from lead acetate, zirconium acetylacetonate, and titanium isopropoxide. The starting materials were dissolved in n-propanol and 1,3-propanediol. After, the amorphous PZT thin films were laser-annealed (using KrF excimer laser) as a function of the laser energy density and the number of laser pulse. Structural properties of PZT thin films are characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric characterization was done on a RT66A test system and a Agilent 4294A impedance analyzer. The PZT thin films show that excimer laser irradiation drastically improved the crystallization and dielectric properties of the PZT thin films, depending on the energy density and the pulse number.

• Journal of Environmental Health Sciences
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• v.17 no.1
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• pp.129-135
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• 1991

To investigate on the trace element content of twelve edible mushrooms and Aloe arborescens, i. e., Lentinus edodes, Ganoderma lucidum (culturing in wood and soil), Tricholoma matsutake, Agaricus bisporus, Cyrophora esculenta, Auricularia auricula-Jude (produced in Korea and China), Sarcodon asparatus, Pleurotus ostreatus, Coriolus versicolor, Smilax rotundifolia and Aloe arborescerts were analyzed by Atomic absorption spectrometer. The obtained results were summerized as follows: 1. Potassium, sodium, magnesium and iron content for the most part samples were in large quantities, especially phosphorus content of those was highest ammount for the all samples. 2. Sodium content was much ammount in the Lentinus edodes (39mg) and Ganoderma lucidurn (20 mg), Culturing in wood and soil, while potassium was very high ammount in the Aloe arborescens and other samples. Mush ammount of magnesium as compared with others was Lentinus edodes (144mg), Ganoderma lucidurn (128mg), Aloe arborescerts (50mg) and pleurotus ostreatus (60mg). Phosphorus content of Ganoderma lucidurn, Lentinus edodes, Gyrophora esculenta, Auricularia polytricha and Agaricus bisporus was much ammount while iron content of all samples equality higher ammount. Sodium content of Aloe arborescens was not analyzed out for almost all, its potassium (82mg), magnesium (50mg) and iron (18rng) content comparatively higher quentity than others minerals and phosphorus volume (4.9mg) as compared with others, was conspicuously lower detect. 4. Cadimium and lead content of harmful metal element were detected on trace quentity for the most part samples 5. Organic acids of samples i.e., Legtinus edodes, Agaricus bisporus, Pleurotus ostreatus and Ganoderma lucidum were Citrate, Malate, Fumalate, Succinate, Oxalate, Acetate, Lactate, and Tartarate and Citrate, Malate and Fumarate contents were higher amount remarkbly than other organic acids. Tartarate content was trace amount.

• Biomedical Science Letters
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• v.26 no.3
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• pp.164-169
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• 2020

Atherosclerosis is a cardiovascular disease in which plaque builds up inside of an artery and can lead to various complications such as myocardial infarction, stroke, and thrombosis. Recently, hypertriglyceridemia has attracted significant attention as contributors to development of atherosclerosis. However, molecular mechanism of its contribution to atherosclerosis is poorly understood. Here we proposed a potential link between triglyceride (TG) and atherosclerosis. TG treatment promoted downregulation of certain scavenger receptor, macrophage scavenger receptor-1 (MSR-1) in phorbol myristate acetate (PMA)-derived human macrophages. TG treatment caused reduction of MSR-1 mRNA expression in a time- and dose-dependent manner. Using chemical inhibitors, we found that inhibition of signaling pathways associated with PI3K and PLC enhances TG-induced reduction of MSR-1 expression in THP-1 macrophages implying that PI3K and PLC is implicated in the expression of MSR-1 in macrophages. Since MSR-1 is associated with uptake and clearance of atherogenic lipoprotein, oxidized low density lipoprotein (oxi-LDL), our data suggest that increase of oxi-LDL due to TG-mediated reduction of its receptor MSR-1 can promote atherosclerosis.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.86-86
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• 2001

Based on the potential inhibitors of cyclooxygenase-2 (COX-2) as anti-inflammatory or cancer chemopreventive agents, we have evaluated the active principles of COX-2 inhibition from natural products. The methanol extract of the cortex of Eugenia caryoplyllata (Myrtaceae) showed the potent inhibition of prostaglandin E$_2$(PGE$_2$) production in lipopolysaccharide (LPS)-activated RAW 264.7 cells (98.3% inhibition at the test concentration of 10 $\mu\textrm{g}$/$m\ell$) Further, hexane-soluble layer was the most active partition compared to ethyl acetate, n-butanol, and water -soluble parts. By bioassay-guided fractionation of hexane-soluble layer, eugenol was isolated and exhibited a significant suppression of PGE$_2$ production (IC$\_$50/=0.06$\mu\textrm{g}$/$m\ell$). In addition, eugenol suppressed the COX-2 gene expression in LPS-stimulated mouse macrop-hage cells. Therfore, eugenol might be a plausible lead candidate for further developing the COX-2 inhibitor as an anti-inflammatory or cancer chemopreventive agent.