• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.905-911
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• 2011

The possible minimum structures of $C_{60}(CH_2)_nOH$ (n=0~2) and $C_{60}(OH)_2$have been optimized using density functional theory (DFT) with the 6-311G (d,f) basis set. The harmonic vibrational frequencies and IR intensities are also determined to confirm that all the optimized geometries are true minima. Also zero-point vibrational energies (ZPVE) have been considered to predict the binding energies. The predicted binding energy of $C_{60}CH_2OH$ is about 10 kcal/mol more stable than the binding energy of $C_{60}OH$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.589-593
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• 2011

[ $SnO_2$ ]nano powders were prepared by solution reduction method using tin chloride($SnCl_2{\cdot}2H_2O$), hydrazine($N_2H_4$) and NaOH. The $SnO_2$ thick films for gas sensors were fabricated by screen printing method on alumina substrates and annealed at $300^{\circ}C$ in air, respectively. XRD patterns of the $SnO_2$ nano powders showed the tetragonal structure with (110) dominant orientation. The particle size of $SnO_2$ nano powders at the ratio of $SnCl_2:N_2H_4$+NaOH= 1:6 was about 60 nm. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a test box. Sensitivity of $SnO_2$ gas sensor to 5 ppm $CH_4$gas and 5 ppm $CH_3CH_2CH_3$ gas was investigated for various $SnCl_2:N_2H_4$+NaOH proportion. The highest sensitivity to $CH_4$ gas and $CH_3CH_2CH_3$ gas of $SnO_2$ sensors was observed at the $SnCl_2:N_2H_4$+NaOH= 1:8 and $SnCl_2:N_2H_4$+NaOH= 1:6, respectively. Response and recovery times of $SnO_2$ gas sensors prepared by $SnCl_2:N_2H_4$+NaOH= 1:6 was about 40 s and 30 s, respectively.

• Journal of Life Science
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• v.24 no.3
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• pp.234-241
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• 2014

To identify and isolate anticancer active compounds from Solanum nigrum, S. nigrum was extracted with MeOH and then fractionated with various organic solvents ($CH_2Cl_2$, EtOAc, n-BuOH, and $H_2O$). The cytotoxic effects of the MeOH extracts from S. nigrum and its organic solvent-soluble fractions were also tested in HT29 cells. All the MeOH extracts of S. nigrum and its organic-solvent extracts induced cytotoxicity in the HT29 cells. Among the extracts, $H_2O$ was the most effective. The $H_2O$ extract was purified further by repeated silica gel, Sephadex LH-20, Diaion HP- 20, and RP-18 column chromatography. An active anticancer compound, Des-N-26-methylene-dihydrotomatidine, was isolated with a molecular weight of 416 and a molecular formula of $C_{28}H_{48}O_2$. Analysis of the cytotoxic effects of Des-N-26-methylene-dihydrotomatidine on the HT29 cells compared to those of tomatine and tomatidine are similar in its structure, is higher than tomatidine above the 40 ${\mu}g/ml$ concentration, but lower than tomatine. This is the first study to describe the anticancer activity of Des-N-26-methylene-dihydrotomatidin, isolated from S. nigrum. Des-N-26- methylene-dihydrotomatidine seems to have potential as a natural bioactive compound.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.6
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• pp.487-490
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• 2010

This paper describes the elecrtical and optical characteristics of $N_2$ doped porous 3C-SiC films. Polycrystalline 3C-SiC thin films are anodized by $HF+C_2H_5OH$ solution with UV-LED exposure. The growth of in-situ doped 3C-SiC thin films on p-type Si (100) wafers is carried out by using APCVD (atmospheric pressure chemical vapor deposition) with a single-precursor of HMDS (hexamethyildisilane: $Si_2(CH_3)_6)$. 0 ~ 40 sccm $N_2$ was used for doping. After the growth of doped 3C-SiC, porous 3C-SiC is formed by anodization with $7.1\;mA/cm^2$ current density for anodization time of 60 sec. The average pore diameter is about 30 nm, and etched area is increased with $N_2$ doping rate. These results are attributed to the decrease of crystallinity by $N_2$ doping. Mobility is dramatically decreased in porous 3C-SiC. The band gaps of polycrystalline 3C-SiC films and doped porous 3C-SiC are 2.5 eV and 2.7 eV, respectively.

• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.1041-1045
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• 2004

Kinetic studies of the pyridinolysis $(XC_5H_4N)$ of aryl dithiomethylacetates $(CH_3CH_2C(=S)SC_6H_4Z,\;1)$ are carried out in acetonitrile at $60.0^{\circ}C$. A biphasic Bronsted plot is obtained with a change in slope from a large $({\beta}X\;{\cong}\;0.8)$ to a small $({\beta}X\;{\cong}\;0.2)$ value at $pK_a^{\circ}$ = 5.2, which is attributed to a change in the rate limiting step from breakdown to formation of a zwitterionic tetrahedral intermediate, $T^{\pm}$, in reaction path as the basicity of the pyridine nucleophile increases. This mechanism is supported by the change of the cross-interaction constant ${\rho}xz$ from a large positive ( ${\rho}xz$ = +1.36) for the weakly basic pyridines to a small negative ( ${\rho}_xz$ = -0.22) value for the strongly basic pyridines. The magnitudes of ${\rho}z$ and activation parameters are also consistent with the proposed mechanism.

• Journal of the Korean Applied Science and Technology
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• v.8 no.2
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• pp.105-114
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• 1991

In relation to the preparation of Langmuir-Blodgett thin film, four kinds of N-alkylpyridiniurn bromide were synthesized. The values of surface tensions of these materials, measured with a Traube stalagmometer, gave the relationship between the critical micells hydrophobic radical and between CMC and temperature. Values of thermodynamic properties(${\Delta}H^0_m,\;{\Delta}S^0_m,\;{\Delta}G^0_m,$) for the formatoin of micelle were also obtained. Experiments gave the following results; at the temperature range between 40 and 60$^{\circ}C, CMC of Hexadecyl-, Octadecyl-, Eicosyl-, and Docosyl-Pyridinium Bromide were $7.64{\times}10^{-4}{\sim}9.13{\times}10^{-4},\;3.85{\times}10^{-4}{\sim}4.60{\times}10^{-4},\;2.00{\times}10^{-4}{\sim}2.39{\times}10^{-4},\;and\;1.07{\times}10^{-4}{\sim}1.28{\times}10^{-4}$ mol/l, respectively. Surface tension, ${\Gamma}_{CMC}$, of those were 33.49${\sim}$36.00, 34.78${\sim}$37.61, 35.49${\sim}$37.61 and 38.76${\sim}$55.80 dyne/cm, respectively, The relationship between CMC and the mumber of carbon atoms in the hydrophobic radical, N was expressed as follows : Log(CMC)=A-BN where A and B are constants. At the temperature range between 40 and 60$^{\circ}C$, the change of Gibbs evergy (${\Delta}G_m$) for one methylene group ($-CH_2-$) were -0.65RT, respectively, The minus values of enthalpy change (${\Delta}H_m$) suggest that the formation of micelle is exothermic. Additionally, the overall increase in the entropy change (${\Delta}S_m$) with respect to the temperature increase suggests that the formation of micelle is attained by a exothermic enthalpy directed process.

• Journal of Microbiology and Biotechnology
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• v.21 no.10
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• pp.1021-1025
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• 2011

A Bacillus subtilis strain was isolated from the intestine of Sebastiscus marmoratus (scorpion fish) that was identified as Bacillus subtilis CH2 by morphological, biochemical, and genetic analyses. The chitosanase of Bacillus subtilis CH2 was best induced by fructose and not induced with chitosan, unlike other chitosanases. The strain was incubated in LB broth, and the chitosanase secreted into the medium was concentrated with ammonium sulfate precipitation and purified by gel permeation chromatography. The molecular mass of the purified chitosanase was detected as 29 kDa. The optimum pH and temperature of the purified chitosanase were 5.5 and $60^{\circ}C$, respectively. The purified chitosanase was continuously thermostable at $40^{\circ}C$. The specific acitivity of the purified chitosanase was 161 units/mg. The N-terminal amino acid sequence was analyzed for future study.

• Microbiology and Biotechnology Letters
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• v.29 no.2
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• pp.84-89
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• 2001

Isolation and Characterization of Cathepsin B inhibitor Produced by Streptomyces luteogriseus KT-IO. Han, Kil~Hwan and Sang~Dal Kim*. Department of Applied Microbiology, Yeungnam Universit}/t Kyongsan 712749, Korea - The cathepsin B inhibitor produced by Streptomyces luteogriseus KT-IO was very stable in heat, acidic and alkaline conditions. The cathepsin B inhibitor was isolated from the extracted fraction of culture broth with butanol, methanol and chloroform subsequently, the inhibitor was purified with following several column chromatography sLlch as DEAE-Sephadex A-25, Sephadex G-15, silica gel 60, Sephadex LH-20, and preparative HPLC. The cathepsin B inhibitor showed positively to detective reaction of ninhydrine, 5% H2S04, iodine, but negatively to the reaction of Ehrlich's reagent, DNS, aniline. The molecular formular of cathepsin B inhibitor was elucidated by JR, lH and 13C-NMR, FAB mass and elemental analyzer. Consequently, it was identified as C4HlI04N6. The cathepsin B inhibitor had the mode of competitive inhibition with the reaction of cathepsin B.

• Journal of the Korean institute of surface engineering
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• v.46 no.3
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• pp.105-110
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• 2013

ZnS thin films were prepared on glass substrate by using chemical bath deposition method. The influence of ammonia ($NH_4OH$) and $Na_2EDTA$ ($Na_2C_{10}H_{16}N_2O_8$) as complexing agents on structural and optical properties of ZnS thin films were investigated. Zinc acetate dihydrate ($Zn(CH_3COO)_2{\cdot}2H_2O$) and thiourea ($H_2NCSNH_2$) were used as a starting materials and distilled water was used as a solvent. All ZnS thin films, regardless of a kind of complexing agents, had the hexagonal structure (${\alpha}$-ZnS) and had a preferred <101> orientation. ZnS thin films, with 4 M ammonia and with 4 M ammonia and 0.1 M $Na_2EDTA$, had the highest <101> peak intensity. In addition, their average particle size are 280 nm and 220 nm, respectively. The average optical transmittances of all films were higher than 60% in the visible range. The optical direct band gap values of films were about 3.6~3.8 eV.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.73-82
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• 1990

Rosin-maleic anhydride adduct (RMA) was synthesized from rosin and maleic anhydride. The polyamideimides were obtained by reacting the adduct with two aromatic diisocyanates using sodium methoxide as catalyst. The yield and the inherent viscosity of polymers obtained by the reaction in NMP solvent were low because of the possible reaction of NMP solvent with diisocyanate monomer. The polymers were synthesized in solvent mixture of NMP and cosolvents such as xylene, acetophenone, benzonitrile, and nitrobenzene in order to minimize the side reaction of NMP with diisocyanates. The yield of polymer obtained by the reaction in NMP-nonpolar cosolvent mixtures was about 70% and that obtained by the reaction in NMP-polar cosolvent mixtures was over 90%, respectively. The polymers were either amorphous or poorly cystalline, and soluble only in highly polar solvents. The inherent viscosity of polymers ranges from 0.12-0.26dl/g. The results of thermal analysis showed that the polymer had good thermal stability with initial decomposition temperature over $330^{\circ}C$.