• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.323-327
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• 1984

Nicotine was reacted with an equimolar amount of ozone in methylene chloride and distilled water. The reaction mixture was separated by column chromatography or thin layer chromatography and then purified by vacuum distillation. The six compounds obtained from this reaction were characterized by NMR, IR and Mass spectrometry. These were identified as unchanged nicotine, nornicotine, anabasine, ${\beta}$-nicotyrine, cotinine and nicotine-N-oxide. From these results, reaction mechanism for the ozonolysis ofon nicotine was proposed; the pyrrolidine ring is attacked by ozone at the 1'-position followed by further transformation.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.695-701
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• 1993

Rate constants of solvolysis of 2-thiophenesulfonyl chloride were determined in aqueous binary mixtures with methanol, ethanol, acetone in water and in methanol. These data are interpreted using the equation of Grunwald-Winstein and Kivinen relationship. Also, kinetic solvent isotope effects in water and in methanol and product selectivities in alcohol-water mixtures were determined. Kinetic solvent isotope effect for hydrolysis of 2-thiopenesulfonyl chloride was 2.24 and 1.47 for methanol and water, respectively. Selectivity values for formation of ester relative to acid in ethanol-water mixtures show maximum S value. From kinetic solvent isotope effect in methanol and water, selectivity data in aqueous alcoholic solvents and solvent effects, it is proposed that the reaction channel favoured in low polarity solvents is general-base catalysis and/or is possibly addition elimination (S$_A$N) reaction pathway and in high polarity solvents iS S$_N$2 reaction mechanism.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1997-2002
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• 2011

The nucleophilic substitution reactions of dicyclohexyl phosphinic chloride [3; $cHex_2$P(=O)Cl] with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at 60.0 $^{\circ}C$. The anilinolysis rate is too slow to be rationalized by the stereoelectronic effects. The rate is contrary to expectations for the electronic influence of the two ligands and exhibits exceptionally great negative deviation from the Taft's eq. The deuterium kinetic isotope effects (DKIEs) involving deuterated anilines invariably change from primary normal ($k_H/k_D$ > 1; max $k_H/k_D$ = 1.10 with X = 4-MeO) with the strongly basic anilines (X = 4-MeO, 4-Me, 3-Me) to secondary inverse ($k_H/k_D$ < 1; min $k_H/k_D$ = 0.673 with X = 3-Cl) with the weakly basic anilines (X = H, 4-F, 4-Cl, 3-Cl). A concerted $S_N2$ mechanism is proposed on the basis of both secondary inverse and primary normal DKIEs. The obtained DKIEs imply that the fraction of a frontside attack increases as the aniline becomes more basic. A hydrogen-bonded, four-center-type transition state is suggested for a frontside attack, while the trigonal bipyramidal pentacoordinate transition state is suggested for a backside attack.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.745-750
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• 2000

The (S $r_{0.85}$C $a_{0.15}$) Ti $O_3$(SCT) thin films are deposited on Pt-coated electrode (Pt/TiN/ $SiO_2$/Si) using RF sputtering method at various deposition temperature. The crystallinity of SCT thin films were increased with increase of deposition temperature in the temperature range of 200~500[$^{\circ}C$]. Also, the composition of SCT thin films were closed to stoichiometry (1.080~1.111 in A/B ratio). V-I characteristics of SCT thin films show the increasing leakage current with the increases of deposition temperature. The conduction mechanism of the SCT thin films observed in the temperature range of 25~100[$^{\circ}C$] can be divided into four regions with different mechanism by the increasing current. The region I below 0.8[MV/cm]shows the ohmic conduction. The region II between 0.9~2[MV/cm] is in proportion to J∝ $E^{1.5}$ , the region III between 2~4[MV/cm] can be explained by the Child’s law, and the region IV above 4[MV/cm]is dominated by the tunneling effect.ect.

• Journal of the Korean Chemical Society
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• v.18 no.1
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• pp.8-11
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• 1974

The solvolysis of p-substituted benzenesulfonyl chlorides $(substituents:p-H, p-Br, p-NO_2, p-OCH_3)$ in acetonitrile-water mixtures below 50 % of water content has been studied kinetically. Results show that Hammett plots give concaved curves but the mechanism is predominantly $S_N2$ and water acts both as nucleophile and general-base.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.147-147
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• 2002

In this study, a mechanism by which glucose level modulates glucose transport in Jurkat cells was investigated. Glucose uptake was more efficient in the cells cultivated in low glucose (2.5 mM) medium than that grown in high glucose (20 $\mu$M) medium. Vmax (0.74 n㏖/10$^6$ cells$\cdot$min) of glucose uptake measured with the cells grown in the low glucose medium was higher than the one (1.06 n㏖/10$^6$ cells$\cdot$min) in the high glucose medium while Km was almost consistent through the change of glucose levels, indicating the increase of glucose transporter number.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.81-84
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• 2005

We suggest flux quantum-based mechanism for force realization in the sub-pico-Newton range. By controlling the number of flux quantum in a superconducting ring, a force can be created as an integer multiple of a constant force step. For a 50 nm-thick Nb ring with the inner and outer radii of $5{\mu}m\;and\;10{\mu}m$, respectively, the force step is estimated to be 165 fN, assuming the magnetic field gradient of 10 T/m. We also estimated a maximum force limit to be $1\sim2$ pN.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.636-642
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• 1994

Essential amino acids involving in the catalytic mechanism of the $\beta$-D-xylosidase of Bacillus stearothermophilus were determined by chemical modification studies. Among various che- mical modifiers tested N-bromosuccinimide (NBS), $\rho$-hydroxymercurybenzoate (PHMB), N-ethylma- leimide, 1-[3-(di-ethylamino)-propyl]$-3-ethylcarbodi-imide (EDC), and Woodward's Reagent K(WRK)inactivated the enzyme, resulting in the residual activity of less than 20%. WRK reduced the enzyme activity by modifying carboxylic amino acids, and the inactivation reacion proceeded in the form of pseudo-first-order kinetics. The double-lagarithmic plot of the observed pseudo-first- order rate constant against the modifier concentration yielded a reaction order of 2, indicating that two carboxylic amino acids were essential for the enzyme activity. The $\beta$-D-xylosidase was also inactivated by N-ethylmaleimide which specifically modified a cysteine residue with a reaction order of 1, implying that one cysteine residue was important for the enzyme activity. Xylobiose protected the enzyme against inactivation by WRK and N-ethylmaleimide, revealing that carboxylic amino acids and a cysteine residue were present at the substrate-binding site of the enzyme molecule.

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.88-97
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• 1985

1-Anthracenesulfonyl chloride used as a substrate has been prepared from anthra-quinone, and its melting point ($124^{circ}C$) was confirmed to be considerably different from the literature value ($90^{circ}C$). Rates of nucleophilic substitution reactions of this substrate with some p-substituted anilines in dry acetone were determined by electroconductometric method, and their mechanism has been discussed. As a result, it has been found that these reactions proceed in parallel catalyzed by anilines together with noncatalyzed process, and that their catalytic activities are electrophilic. Judging from $Br{\phi}nsted\;{\beta}$ (0.77), Hammett ${\rho}$(-3.2), and activation parameters which were determined from the temperature dependence of noncatalyzed second order rate constants, it appears most appropriate that their mechanism should be discussed in terms of an associative $S_N2$ involving sulfonylammonium intermediate.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.75-81
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• 2010

The reaction of N,N-diethyl carbamates of 1H-[1,2,3]triazolo[4,5-b]pyridin-1-ol (4-HOAt) 7, 3H-[1,2,3]triazolo[4,5-b]pyridin-3-ol (7-HOAt) 8, 1H-benzo[d][1,2,3]triazol-1-ol (HOBt) 9, 6-chloro-1H-benzo[d][1,2,3]triazol-1-ol (Cl-HOBt) 10, 6-(trifluoromethyl)-1H-benzo[d][1,2,3]triazol-1-ol ($CF_3$-HOBt) 11, and 6-nitro-1H-benzo[d][1,2,3]triazol-1-ol ($NO_2$-HOBt) 12 with morpholine and piperidine in $CH_3CN$ underwent acyl nucleophilic substitution to give the corresponding carboxamide derivatives. The reactants and products were identified by elemental analysis, IR and NMR. We measured the kinetics of these reactions spectrophotometrically in $CH_3CN$ at a range of temperatures. The rates of morpholinolysis and piperidinolysis were found to fit the Hammett equation and correlated with $\sigma$-Hammett values. The values were 1.44 - 1.21 for morpholinolysis and 1.95 - 1.72 for piperidinolysis depending on the temperature. The $Br{\phi}$nsted-type plot was linear with a $\beta_lg = -0.49 \pm 0.02$ and $-0.67 \pm 0.03$. The kinetic data and structure-reactivity relationships indicate that the reaction of 9-12 with amines proceeds by a concerted mechanism. The deviation from linearity of the correlation ${\Delta}H^#$ vs. ${\Delta}S^#$ and plot of $logk_{pip}$ vs. $logk_{morph}$ and $Br{\phi}$nsted-type correlation indicate that the reactions of amines with carbamates 7 and 8 is attributed to the electronic nature of their leaving groups.