• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1671-1678
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• 1996

In external chemical vapor deposition processes including VAD and OVD the distribution of flame-synthesized silica particles is determined by heat and mass transfer limitations to particle formation. Combustion gas flow velocities are such that the particle diffusion time scale is longer than that of gas flow convection in the zone of particle formation. The consequence of these effects is that the particles formed tend to remain along straight smooth flow stream lines. Silica particles are formed due to oxidation and hydrolysis. In the hydrolysis, the particles are formed in diffuse bands and particle formation thus requires the diffusion of SiCl$\_$4/ toward CH$\_$4//O$\_$2/ combustion zone to react with H$\_$2/O diffusing away from these same zones on the torch face. The conversion kinetics of hydrolysis is fast compared to diffusion and the rate of conversion is thus diffusion-limited. In the language of combustion, the hydrolysis occurs as a Burke-Schumann process. In selected conditions, reaction zone shape and temperature distributions predicted by the Burke-Schumann analysis are introduced and compared with experimental data available. The calculated centerline temperatures inside the reaction zone agree well with the data, but the calculated values outside the reaction zone are a little higher than the data since the analysis does not consider diffusion in the axial direction and mixing of the combustion products with ambient air. The temperatures along the radial direction agree with the data near the centerline, but gradually diverge from the data as the distance is away from the centerline. This is caused by the convection in the radial direction, which is not considered in the analysis. Spatial distribution of silica particles are affected by convection and diffusion, resulting in a Gaussian form in the radial direction.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7055-7059
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• 2014

Artemisia, as one of the largest genera in the tribe Anthemideae of the Asteraceae comprises an important part of Iranian flora. While cytotoxic and apoptotic properties have already been reported for some species of the genus there is not any report on cytotoxic effects of A. ciniformis. Petroleum ether (40-60), dichloromethane, ethyl acetate, ethanol and ethanol-water (50:50) extracts of the aerial parts of A. cinformis were subjected to cytotoxic and apoptotic evaluations on two cancer human cell lines (K562 and HL-60) and on J774 normal cells. Among multiple extracts evaluated for cytotoxicity, dichloromethane ($CH_2Cl_2$) and petroleum ether (PE) extracts were shown to possess the highest anti-proliferative effects on HL-60 and K562 cells with $IC_{50}$ values of 31.3 and $25.5{\mu}g/ml$ respectively. Apoptosis induction verified by sub-G1 peaks was seen in flow cytometry histograms. Increase in the amount of Bax protein, formation of DNA fragments, and cleavage of PARP to 24 and 89kDa sub units all confirmed induction of apoptosis by A. cinformis extracts. Taken together according to the result of the present study some extracts of A. cinformis could be considered as sources for natural cytotoxic compounds and further mechanistic and phytochemical studies are recommended to fully understand the underlying mechanisms of cnacer cell death as well as identification of responsible phytochemicals.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.11
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• pp.1408-1414
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• 2008

The anticancer properties of Scolopendra subspinipes mutilans extract were investigated. The extract from S. subspinipes mutilans by 80% EtOH was fractionated with n-hexane, dichloromethan ($CH_2Cl_2$), ethylacetate (EtOAc), and butanol (BuOH) in order. The EtOAc fraction showed the highest inhibitory activity (about 80%) against human leukemia (HL-60) cell growth at $50\;{\mu}g/mL$. To explore the mechanism of cytotoxicity, we used several measures of apoptosis to determine whether these processes were involved in EtOAc fraction-induced HL-60 cell death. Our results showed EtOAc fraction induced cell shrinkage, cell membrane blebbing, apoptotic body, and DNA fragmentation. The EtOAc fraction gradually decreased the expression of anti-apoptotic Bcl-xL and led to the activation of caspase-3, -9 and cleavage of PARP. These findings suggest that S. subspinipes mutilans exhibits potential anticancer properties.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.367-373
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• 2014

In this study, the reducing agent hydrazine and precipitator NaOH were used with $NiCl_2$ as a starting material in order to compound Ni-based material with spherical nano characteristics; resulting material was used as an anode for SOFC. Synthetic temperature, pH, and solvent amounts were experimentally optimized and the synthesis conditions were confirmed. Also, a 0 ~ 0.15 mole ratio of metal(Co, Fe) was alloyed in order to increase the catalyst activation performance of Ni and finally, spherical nano $Ni_{(1-x)}-M_{(x=0{\sim}0.15)}$(M = Co, Fe) alloy materials were compounded. In order to evaluate the catalyst activation for hydrocarbon fuel, fuel gas(10%/$CH_4$+10%/Air) was added and the responding gas was analyzed with GC(Gas Chromatography). Catalyst activation improvement was confirmed from the 3% hydrogen selectivity and 2.4% methane conversion rate in $Ni_{0.95}-Co_{0.05}$ alloy; those values were 4.4% and 19%, respectively, in $Ni_{0.95}-Fe_{0.05}$ alloy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.3
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• pp.193-202
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• 1991

Antimicrobial substances were screened by paper disk plate method in marine sponges, Halichondria okadai, Halichendria sp., H iaponica and Haliclona Pemollis, collected from the south coast of Korea. Antibacterial components were detected in two species, H okadai and Halichondria sp.. Three components such as benzoic acid, okadaic acid(OA) and dinophysistoxin-1(DTX1) were identified from these sponges as the antimicrobial compounds by MS and NMR spectral data. OA$(550{\~}600{\mu}g/kg)$ and $(400{\~}490{\mu}g/kg)$ were determined from the wet H okadai and Halichondria sp., respectively, by using fluorometric HPLC analysis with 9-anthryldiazomethane(ADAM) as fluorescent labelling reagent.

• Archives of Pharmacal Research
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• v.27 no.10
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• pp.1043-1047
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• 2004

Thirteen compounds were isolated from the $CH_2Cl_2$ fraction of Machilus thunbergii as phospholipase $C{\Upsilon}1\;(PLC{\Upsilon}1)$ inhibitors. These compounds were identified as nine lignans, two neolignans, and two flavans by spectroscopic analysis. Of these, 5,7-di-O-methyl-3',4'-methylenated (-)-epicatechin (12) and 5,7,3'-tri-O-methyl (-)-epicatechin (13) have not been reported previously in this plant. In addition, seven compounds, machilin A (1), (-)-sesamin (3), machilin G (5), (+)-galbacin (9), licarin A (10), (-)-acuminatin (11) and compound 12 showed dose-dependent potent inhibitory activities against $PLC{\Upsilon}1$ in vitro with $IC_{50}$ values ranging from 8.8 to 26.0 ${\mu}M$. These lignans, neolignans, and flavans are presented as a new class of $PLC{\Upsilon}1$ inhibitors. The brief study of the structure activity relationship of these compounds suggested that the benzene ring with the methylene dioxy group is responsible for the expression of inhibitory activities against $PLC{\Upsilon}1$. Moreover, it is suggested that inhibition of $PLC{\Upsilon}1$ may be an important mechanism for an antiproliferative effect on the human cancer cells. Therefore, these inhibitors may be utilized as cancer chemotherapeutic and chemopreventive agents.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.328-334
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• 1984

A series of phenyl N-benzenesulfonylchloroformimidate derivatives (p-H, p-Cl, p-CH3 & p-OCH3) were prepared and the hydrolysis of these compounds were studied kinetically at various pH by UV spectrophotometry in 1 ; 4 dioxane-water at $25^{\circ}C$. Hammett ${\rho}$ values measured at pH 5.0 (${\rho}$ = -0.45) and pH 10.0 (${\rho}$ = 0.40) indicate that the reaction proceeds via an azocarbonium ion intermediate in the acidic medium, whereas, it involves direct attack by hydroxide ion on the azomethine carbon atom occurs under the basic medium. The formation of stabilized azocarbonium ion species at pH 5.0 is also consistent with the large solvent effect(m = 1.3-1.5 & n = 5.0-5.5). On the basis of these findings, we may concluded that the hydrolysis of phenyl N-benzenesulfonylchloroformimidate derivatives proceeds by $SN_1$ below pH 8.0, however, above pH 10.0, the hydrolysis proceeds through $SN_2$ and in the range of pH 8.0-10.0, these two reactions occur competitively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.796-801
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• 2000

Kimchi is the Korean traditional food which is fermented properly from salted Korean cabbage of raddish with other various supplements. Kimchi therefore can be the major sources for various kinds of nutrients and other biological substances. The fermentation process accompanies with complicated reaction mechanism which bacteria, fungi and yeast are involved and they produced aroma, taste and bioactive components. To identify nucleoside, this study was conducted with freeze-dried mustard leaf, mustard leaf kimchi and fermented mustard leaf kimchi. Hexane, CH$_2$Cl$_2$, EtOAc and BuOH was used in order to extract their components. The isolated compounds I and II from mustard leaf and mustard leaf kimchi were identified as adenosine and uracil using UV, $^{1}H$-NMR, $^{13}C$-NMR and LC-MS, respectively. Compound I, II and nucleosides are the first report of its occurrence from mustard leaf and their kimchi, the standardized ratios of ingredients for kimchi were 10 of anchovy juice, 8 of red pepper powder, 3 of garlic, 1.5 of ginger, 6 of paste of glutinous rice. The nucleoside of mustard leaf and their kimchi was determined and compared. The order of nucleosides contents of mustard leaf was uridine>cytosine>uracil>adenine>guanosine>guanin, that of fresh mustard leaf kimchi was uridine>uracil>cytosine>guanine>adenosine>adenin>guanosine and that of fermented mustard leaf kimchi (5days at 15$^{\circ}C$) was guanine>adenine>adenosine>guanosine. The differences of nucleoside contents from those were due to various supplements and fermentation process.

• Composites Research
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• v.31 no.2
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• pp.43-50
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• 2018

The effects of deposition temperature on chemical vapor deposited silicon carbide (CVD-SiC) were studied to obtain high deposition rates and excellent bending strength characteristics. Silicon carbide prepared at $1250{\sim}1400^{\circ}C$ using methyltrichlorosilane(MTS : $CH_3SiCl_3$) by hot-wall CVD showed deposition rates of $95.7{\sim}117.2{\mu}m/hr$. The rate-limiting reaction showed the surface reaction at less than $1300^{\circ}C$, and the mass transfer dominant region at higher temperature. The activation energies calculated by Arrhenius plot were 11.26 kcal/mole and 4.47 kcal/mole, respectively. The surface morphology by the deposition temperature changed from $1250^{\circ}C$ pebble to $1300^{\circ}C$ facet structure and multi-facet structure at above $1350^{\circ}C$. The cross sectional microstructures were columnar at below $1300^{\circ}C$ and isometric at above $1350^{\circ}C$. The crystal phases were all identified as ${\beta}$-SiC, but (220) peak was observed from $1300^{\circ}C$ or higher at $1250^{\circ}C$ (111) and completely changed to (220) at $1400^{\circ}C$. The bending strength showed the maximum value at $1350^{\circ}C$ as densification increased at high temperatures and the microstructure changed from columnar to isometric. On the other hand, at $1400^{\circ}C$, the increasing of grain size and the direction of crystal growth were completely changed from (111) to (220), which is the closest packing face, so the bending strength value seems to have decreased.

• The Korea Journal of Herbology
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• v.35 no.3
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• pp.17-24
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• 2020

Objectives : The objective of this study was to evaluate the gastric protective effect of Curcuma Longae Rhizoma (CLR) in 150 mM HCl/60% ethanol induced gastric ulcer (GU) in mice. Methods : Forty ICR mice were divided into five groups (n=8/Group): Nor group; Normal, Veh group; GU control, SC group; GU + sucralfate 10 mg/kg, CL; GU + CLR 30% ethanol extract 100 mg/kg, CH group; GU + CLR 30% ethanol extract 200 mg/kg. Then, mice were orally administered with 150 mM HCl/60% ethanol and caused GU. After 1 hr, mice were sacrificed, and blood and stomach tissue were collected. Results : CLR showed significance scavenging effects in 1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) radical scavenging activities (DPPH IC₅₀; 78.18 ± 0.60 ㎍/㎖, ABTS IC₅₀; 55.91 ± 1.86 ㎍/㎖). CLR significance reduce inflammatory-related factors such as cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin-6 (IL-6) via nuclear factor kappa B (NF-κB) inactivation. In addition, the activation of nuclear factor erythroid2-related factor 2 (Nrf2) significantly led to up-regulation of anti-oxidant enzymes including factors heme oxygenase-1 (HO-1), super oxide dismutase (SOD), and glutathione peroxidase-1/2 (GPx-1/2). Conclusions : Our discovery provides that CLR possesses anti-oxidant and anti-inflammatory effects. Hence, CLR may ameliorate the development of gastric ulcer though the inhibition of NF-κB inflammatory pathway and the elevation of Nrf2 anti-oxidant pathway.