• Journal of Energy Engineering
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• v.7 no.1
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• pp.35-43
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• 1998

Electrodes using for the anode electrode of direct methanol fuel cell with Pt/C and Pt/Ru/C catalyst were prepared and characterized by SEM, TEM, thermal analysis and electrochemical analysis. The half cell tests were carried out with 1 M $H_2SO_4$ electrolyte and 1 M $CH_3OH$ in order to evaluate the electrode performance. The employed electrochemical methods were cyclic vol-tammetry and potentiodynamic polarization experiments. It was found that 20 w% polytetrafluoroethylene (PTFE) content in catalyst showed the best performance due to the best platinum utilization on PTFE-containing catalyst layer. It was found that Pt/Ru/C binary catalyst inhibited the poisoning of anode electrode showing improved performance compared to the Pt/C catalyst by the adsorption of oxygen containing species on the electrode surface at same time. The apparent activation energy for methanol oxidation on the Pt/Ru/C and Pt/C catalyst layer was 11.60 kJ/mol and 26.85 kJ/mol, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.135-141
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• 2005

Nitric oxide(NO) reduction by methanol was investigated over $La_2O_3$ catalysts in the presence and absence of oxygen. In the absence of $O_2$, $CH_3OH$ reduced NO to both $N_2$ and $N_2O$, with selectivity to $N_2$ formation decreasing from 81-88% at 623K to 47-71% at 723 K. With 1.2% $O_2$ in the feed, the rates were 4-8 times higher, but the selectivity to $N_2$ dropped from 50% at 623 K to 9% at 723 K. The specific activities with $La_2O_3$ for this reaction were higher than those for other reductants; for example, at 773 K with hydrogen a specific activity of $34\;{\mu}mol\;NO/sec{\cdot}m^2$ was obtained whereas that for methanol was $638\;{\mu}mol\;NO/sec{\cdot}m^2$. The Arrhenius plots were linear under differential reaction conditions, and the apparant activation energy was consistantly near 15 kcal/mol with $CH_3OH$. Linear partial pressure dependencies based on a power rate law were obtained and showed a near-zero order in $CH_3OH$ and a near-first order in $H_2$.

• Journal of the Korean Institute of Gas
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• v.27 no.1
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• pp.78-85
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• 2023

Fixed-bed reactor Computational Fluid Dynamics (CFD) simulation of methanol steam reforming reaction was performed using the intrinsic kinetic data of the copper-impregnated hydrotalcite catalyst. The activation energy of the copper hydrotalcite catalyst obtained from the previous study results was 97.4 kJ/mol, and the pre-exponential was 5.904 × 10¹⁰. Process simulation was performed using the calculated values and showed a similar tendency to the experimental results. And the conversion rate according to the change of the reaction temperature (200 - 450 ℃) and the molar ratio of methanol and water was observed using the intrinsic kinetic data. In addition, mass and heat transfer phenomena analysis of a commercial reactor (I.D. 0.05 - 0.1m, Length 1m) was predicted through axial 2D Symmetry simulation using the power law model of the above kinetic constants.

• Natural Product Sciences
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• v.14 no.3
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• pp.182-186
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• 2008

Scutellaria baicalensis Georgi (SBG) is traditionally used medicinal herb that has anti-oxidant, anticancer and anti-inflammatory effects. In this study, we investigated whether the extracts of SBG have the inhibitory activity in the osteoclast differentiation by using mouse monocytes RAW264.7 cells and primary mouse bone marrow-derived macrophages (BMMs). Methanol extract (ME) from SBG was successively fractionated into methylene chloride (MF), ethylacetate (EF) and n-butanol fraction (BF). The activity assay for tartrateresistant acid phosphatase (TRAP) and Western blot analysis were employed to evaluate the osteoclasts differentiation and the activation of mitogen-activated protein (MAP) kinases, respectively. ME, MF, EF and BF significantly and dose-dependently inhibited osteoclast differentiation without the decrease of cell viability at the concentrations used in this study. In addition, ME significantly inhibited the activation of c-jun-N-terminal kinase (JNK). In conclusion, this study firstly demonstrated that ME of SBG has the potential to inhibit the osteoclast differentiation through the suppression of JNK activation partially.

• The Korea Journal of Herbology
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• v.21 no.4
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• pp.93-101
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• 2006

Objectives : Increasing evidence has linked chronic inflammation to a number of neurodegenerative disorders including Alzheimer's disease(AD), Parkinson's disease(PD) and Huntington's disease(HD) in the inflammatory process. Uncontrolled activation of microglia may directly toxic to neurons by releasing various substances such as inflammatory cytokines ($TNF-{\alpha}$, $IL-1{\beta}$ and IL-6), NO, PEG2 and superoxide. In this study, the immunomodulatory effects of the herbal extract Panax notoginseng on cultured BV2 microglial cells and primary microglia were investigated to address potential therapeutic or toxic effects. Notoginseng radix extracts extracted from the root of the plant using Methanol. Methods : Cells were stimulated with LPS and treated with notoginseng at different concentrations. Results : Notoginseng significantly decreased LPS-induced production of $TNF-{\alpha}$ and IL-6 by the cultured microglial cells in a dose-dependent manner. The activation of iNOS mRNA and secretion of nitric oxide(NO) in microglial cells were inhibited in microglial cells in a dose-dependent manner by notoginseng. Conclusion : These results indicate that notoginseng inhibits LPS-induced activation of microglial cells and demonstrates notoginseng possess anti-inflammatory and immunosuppressive properties in vitro.

• BMB Reports
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• v.47 no.7
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• pp.382-387
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• 2014

Corn silk (CS) has long been consumed as a traditional herb in Korea. Maysin is a major flavonoid of CS. The effects of maysin on macrophage activation were evaluated, using the murine macrophage RAW 264.7 cells. Maysin was isolated from CS by methanol extraction, and preparative $C_{18}$ reverse phase column chromatography. Maysin was nontoxic up to $100{\mu}g/ml$, and dose-dependently increased TNF-${\alpha}$ secretion and iNOS production by 11.2- and 4.2-fold, respectively, compared to untreated control. The activation and subsequent nuclear translocation of NF-${\kappa}B$ was substantially enhanced upon treatment with maysin ($1-100{\mu}g/ml$). Maysin also stimulated the phosphorylation of Akt and MAPKs (ERK, JNK). These results indicated that maysin activates macrophages to secrete TNF-${\alpha}$ and induce iNOS expression, via the activation of the Akt, NF-${\kappa}B$ and MAPKs signaling pathways. These results suggest for the first time that maysin can be a new immunomodulator, enhancing the early innate immunity.

• Korean Journal of Pharmacognosy
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• v.51 no.4
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• pp.317-324
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• 2020

Mast cells play a key role in IgE-mediated allergic response. We investigated whether Swertia pseudochinensis Hara extract (SPE) inhibits IgE-mediated allergic response in mast cells and an allergic animal model. Additionally, we explored SPE's mechanism of action in mast cells. Our results showed that SPE inhibited both antigen-stimulated degranulation and the production of TNF-α and IL-4 in bone marrow-derived mast cells (BMMCs) and rat basophilic leukemia (RBL)-2H3 cells. SPE also suppressed allergic response in IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. As for the mechanism of action of SPE in mast cells, it inhibited the activation of Syk kinase, a critical signaling protein in the FcεRI-mediated signaling pathway, and also the activation of LAT, a downstream adaptor protein of Syk. We further observed the reduced activation of mitogen-activated protein (MAP) kinases (P38, ERK1/2, and JNK) and Akt in mast cells. Our results described for the first time that SPE has an anti-allergic effect by suppressing mast cells through the inhibition of Syk kinase. Therefore, SPE may be useful for the treatment of type I allergic diseases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.11
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• pp.745-753
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• 2016

Micro methanol-steam reformer for fuel cell can effectively produce hydrogen as reforming response to steam takes place in low temperature (less than $250^{\circ}C$). This study conducted numerical research on this reformer. First, study set wall temperature of the reformer at 100, 140, 180 and $220^{\circ}C$ while methanol conversion efficiency was set in 0, 0.072, 3.83 and 46.51% respectively. Then, porosity of catalyst was set in 0.1, 0.35, 0.6 and 0.85 and although there was no significant difference in methanol conversion efficiency, values of pressure drop were 4645.97, 59.50, 5.12 and 0.45 kPa respectively. This study verified that methanol-steam reformer rarely responds under the temperature of $180^{\circ}C$ and porosity does not have much effect on methanol conversion efficiency if the fluid flowing through reformer lowers activation energy by sufficiently contacting reformer.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.637-642
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• 2004

Effects of defatted sesame and perilla methanol extracts on cognitive function and antioxidant activity of learning- and memory-impaired animal model SAMP8 mice. Animals were divided into 4 groups and fed with diets containing 0.3%(w/w) defatted sesame (S) or defatted perilla methanol extracts (P) for 12 weeks. Step through latency of SAMP8 control group was significantly higher than that of SAM R1 normal group, whereas significantly increased in S and P groups compared with SAMP8 control on passive avoidance test (p<0.001). Acetylcholinesterase activity of brain in SAMP8 increased compared with SAMR1 but no difference between SAMP8 control group and sample-treated group. Brain TBARS contents of SAMP8 control significantly increased compared with SAMR1 and were lowered significantly by supplementation of defatted sesame and perilla methanol extracts. Defatted sesame and perilla methanol extracts attenuated increased brain superoxide dismutase and glutathione peroxidase activities in SAMP8. These results suggest defatted sesame and perilla methanol extracts could attenuate cognitive deficits induced by aging possibly through activation of antioxidant activity of defatted sesame and perilla methanol extracts.

• Journal of the Korean Chemical Society
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• v.37 no.6
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• pp.555-561
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• 1993

Ultraviolet spectrophotometric investigation has been carried out on the system of iododestannylation iodine and tetramethyltin in methanol. The transient CT absorption spectrum can be observed and the subsequent disappearance of CT absorption spectrum was accompained by the cleavage of tetramethyltin with iodine. From there, the rate constants for the iododestannylation were determined at 10, 25 and 35$^{\circ}C$ up to 1600 bar and the reaction rates were increased with increasing temperature and pressure. From these rate constants, the values of the activation parameters (${\Delta}V^\neq,\;{\Delta}{\beta}^{\neq},\;{\Delta}H^{\neq},\;{\Delta}S^{\neq}\;and\;{\Delta}G^{\neq}$) were obtained. The activation volumes and activation compressibility coefficients were both negativity. The activation enthalpies were positive and activation entropies had large negative values. From these values discussed in terms of solvent structure variation of transition state and mechanism. From these results, it was found that the reaction is followed with $S_E2$ mechaenism and weakened $S_E2$ mechanism nature by increasing pressure.