• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.171.1-171
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.11a
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• pp.25-25
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• 2001

• Korean Journal of Materials Research
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• v.25 no.12
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• pp.659-665
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• 2015

The self-propagating high temperature synthesis approach was applied to synthesize amorphous boron nano-powders in argon atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in the $B_2O_3+{\alpha}Mg$ system(${\alpha}=1.0-8.0$) in an argon atmospheres. In this study, the exothermic nature of the $B_2O_3-Mg$ reaction was investigated using thermodynamic calculations. Experimental study was conducted based on the calculation data and the SHS products consisting of crystalline boron and other compounds were obtained starting with a different initial molar ratio of Mg. It was found that the $B_2O_3$ and Mg reaction system produced a high combustion temperature with a rapid combustion reaction. In order to regulate the combustion reaction, NaCl, $Na_2B_4O_7$ and $H_3BO_3$ additives were investigated as diluents. In an experimental study, it was found that all diluents effectively stabilized the reaction regime. The final product of the $B_2O_3+{\alpha}Mg$ system with 0.5 mole $Na_2B_4O_7$ was identified to be amorphous boron nano-powders(< 100 nm).

• Korean Journal of Materials Research
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• v.24 no.5
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• pp.255-258
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• 2014

Zirconium boride is an artificial or which is rarely found in the nature. $ZrB_2$ is popular in the hard material industry because it has a high melting point, excellent mechanical properties and chemical stability. There are two known methods to synthesize $ZrB_2$. The first involves direct reaction between Zr and B, and the second is by reduction of the metal halogen. However, these two methods are known to be unsuitable for mass production. SHS(Self-propagating High-temperature Synthesis) is an efficient and economic method for synthesizing hard materials because it uses exothermic reactions. In this study, $ZrB_2$ was successfully synthesized by subjecting $ZrO_2$, Mg and $B_2O_3$ to SHS. Because of the high combustion temperature and rapid combustion, in conjunction with the stoichiometric ratio of $ZrO_2$, Mg and $B_2O_3$; single phase $ZrB_2$ was not synthesized. In order to solve the temperature problem, Mg and NaCl additives were investigated as diluents. From the experiments it was found that both diluents effectively stabilized the reaction and combustion regime. The final product, made under optimum conditions, was single-phase $ZrB_2$ of $0.1-0.9{\mu}m$ particle size.

• YAKHAK HOEJI
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• v.35 no.5
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• pp.368-371
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• 1991

For the development of new antiulcer agents 5, 6-dihydroimidazo[2, 1-b]- thiazoles substituted at the 3-position are sythesized. Thus, the reaction of 3-chloromethyl-5, 6-dihydroimidazo[2, 1-b]thiazole(2) with thiourea and subsequently with 3-chloro-propionitrile gives 3-[3-[5, 6-dihydroimidazo[2, 1-b]thiazolyl]methylthio]propionitrile(4), which by partial alcoholysis with methanol is converted into methyl-3-[3-[5, 6-dihydro-imidazo[2, 1-b]thiazoyl]methylthio]propionimidate(5) . This compound(5) is treated finally with sulfamide or sulfonamides. 3-[3-[5, 6-dihydroimidazo[2, 1-b]thiazoyl]methylthiol-N$^{2}$-sulfamoyl-propionamidine(6) inhibited gastric acid secretion (45%) when administered intraduodenally (100 mg/kg) to pylorus-ligated rats.

• Journal of the Korean Ceramic Society
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• v.50 no.3
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• pp.195-200
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• 2013

Here, we report preparation of cyan ceramic nano-pigment for inkjet printing and the Ni substitutional effects on the cyan color. $MgAl_2O_4$ was selected as the crystalline host network for the synthesis of nickel-based cyan ceramic nano-pigments. Various compositions of $Ni_xMg_{1-x}Al_2O_4$ ($0{\leq}x{\leq}1$) powders were prepared using the polymerized complex method. The powder was then preheated at $400^{\circ}C$ for 5 h and finally calcined at $1000^{\circ}C$ for 5 h. XRD patterns of $Ni_xMg_{1-x}Al_2O_4$ showed a single phase of the spinel structure in all the compositions. The particle sizes ranged from 20 to 50 nm in TEM observations. The characteristics of the color tones of $Ni_xMg_{1-x}Al_2O_4$ were analyzed by UV-Visible spectroscopy and CIE $L^*a^*b^*$ measurement. CIE $L^*a^*b^*$ measurement results indicate that the pigment color changes from light cyan to deep cyan due to the decrease of the $a^*$ and $b^*$ values with an increase of an Ni substitutional amount. In addition, the thermal stability and the binding nature of $Ni_xMg_{1-x}Al_2O_4$ are also discussed using TG-DSC and FT-IR results respectively.

• Journal of Mushroom
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• v.19 no.3
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• pp.150-159
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• 2021

Anti-melanogenesis and skin anti-wrinkle effects of methanol (ME) and hot water (HE) extracts from the fruiting bodies of Ganoderma applanatum were investigated in this study. The total phenolic contents of the ME and HE of the mushroom were 11.68 and 3.15 ㎍ GAEs/mg, respectively, whereas the total flavonoid contents of the ME and HE were 21.82 and 2.69 ㎍ QEs/mg, respectively. The survival rate of B16-F10 murine melanoma cells treated with 750 ㎍ ME and HE were 83.46% and 85.54%, respectively, thereby suggesting that mushroom extracts were slightly cytotoxic at the tested concentration. The in vitro tyrosinase inhibition by ME (83.15%) and HE (83.44%) was significantly lower than that of kojic acid (99.61%), the positive control, at 2.0 mg/mL. Although the inhibition of cellular melanin synthesis in B16-F10 melanoma cells by 2.0 mg/mL of ME (50.24%) and HE (51.24%) was lower than that of arbutin (64.84%), the inhibition by both ME and HE was higher than 50%. Collagenase inhibition by HE was comparable to 2.0 mg/mL epigallocatechin (EGCG), the positive control; however, elastase inhibition by ME and HE was lower than that of EGCG at the concentration tested. The results showed that the fruiting bodies of G. applanatum had good anti-tyrosinase, good anti-collagenase, and moderate anti-elastase activities, which might be useful for developing novel skin-whitening and anti-wrinkle agents.

• Progress in Superconductivity and Cryogenics
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• v.7 no.1
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• pp.1-4
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• 2005

Nano- sized spherical $MgB_2$ Powders were synthesized by spray Pyrolysis method. The Influence of solution concentration and furnace reaction temperature on morphology and average particle size were investigated. For adequate preparation conditions, it has mostly spherical, solid and narrow particle size distribution. Average particle size$(X_{50})$ distribution was below 100 nm. The critical temperature for the synthesized $MgB_2$ was around 36K.

• BMB Reports
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• v.32 no.2
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• pp.196-202
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• 1999

The existence of the Ras-independent signal transduction pathway of insulin leading to DNA synthesis was investigated in Rat-1 fibroblasts overexpressing human insulin receptor (HIRc-B) using the single-cell microinjection technique. Microinjection of a dominant-negative mutant $Ras^{N17}$ protein into quiescent HIRc-B cells inhibited the DNA synthesis stimulated by insulin. Microinjection of oncogenic H-$Ras^{V12}$ protein ($H-Ras^{V12}$) (0.1 mg/ml) induced DNA synthesis by 35%, whereas that of control-injected IgG was induced by 20%. When the marginal amount of oncogenic H-$Ras^{V12}$ protein was coinjected with a dominant-negative mutant of the H-Ras protein ($Ras^{N17}$), DNA synthesis was 35% and 74% in the absence and presence of insulin, respectively. This full recovery of DNA synthesis by insulin suggests the existence of the Ras-independent pathway. The same recovery was observed in the cells coinjected with either H-$Ras^{V12}$ plus H-$Ras^{N17}$ plus SH2 domain of the p85 subunit of PI3-kinase ($p85^{SH2-N}$) or H-$Ras^{V12}$ plus H-$Ras^{N17}$ plus interfering anti-Shc antibody. When co-injected with a dominant-negative H-$Ras^{N17}$, the DNA synthesis induced by the Ras-independent pathway was blocked. These results indicate that the Ras-independent pathway of insulin leading to DNA synthesis exists, bypassing the p85 of PI3-kinase and Shc protein, and requires Rac1 protein.

• Journal of the Korean Ceramic Society
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• v.45 no.7
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• pp.418-422
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• 2008

The preparation of FeB by SHS in $B_2O_3-Mg-Fe-Fe_3O_4$ system was investigated in this study. In the preparation of FeB, the effects of the initial pressure of inert gas in reactor, the content of Mg and $Fe_3O_4$ in mixture on the reactivity and reaction products was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 25 atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 25 atm, the optimum composition for the preparation of pure FeB was $1.5B_2O_3$+3.43Mg+ 1.7Fe+$0.1Fe_3O_4$. The FeB synthesized in this condition had an irregular shape and the particle size of $5\;{\mu}m$.