• Analytical Science and Technology
• /
• v.15 no.1
• /
• pp.67-71
• /
• 2002

The residual analysis and half-life time of imidazole fungicide prochloraz in soils (silty clay) were investigated by gas chromatography equipped electron capture detector (GC-ECD). The soil samples were extracted acetone/hexane(1:1) solvent and analyzed after separated by $LC-NH_2$ Sep-Pak solid column. Linear sensitivity of standard calibration curve was Y = 268.8600X + 0.0664, $R^2=0.9998$ between 0.05~1.00 ng. The detection limit was 0.02 mg/L and the average recoveries were 94.5~97.3% from the standard additional experiments with 0.10 and 0.40 mg/L. The half-life time was 24.4 days in room laboratory and 7.6 days in the field test soil.

• Korean Journal of Crystallography
• /
• v.12 no.4
• /
• pp.212-215
• /
• 2001

The hydrothermal reaction between manganese nitrate (Mn(NO₃)₂·H₂O ) and midzole-4,5-dicarboxylic acid(IDCH₂) in the presence of sodium acetate (NaOAC·3H₂O) gave a two-dimensional manganese-imidazoledicarboxylate coordination polymer with an empirical formula of [Mn(IDC)(H₂O)](1) Compound 1 was characterized by spectroscopy (IR) and X-ray diffraction. Crystal-lographic date for 1: orthorhombic space group, Pbca, a=7.257(5) Å b=13.687(5)Å, c=14.332(6)Å Z=8, R(wR₂)=0.0498(0.0999).

• Textile Coloration and Finishing
• /
• v.3 no.3
• /
• pp.1-5
• /
• 1991

Cationic azo dyes were synthesized by coupling aniline and its derivatives with 2,4-dimethyl imidazole as a coupler, and their photochromic behavior was investigated. The dyes exhibited little photochromism on wool, but to a considerable degree on Dacron T92(anionic modified polyester), the photochromism being prominent for the dye with electron-releasing substituent on diazo component. Little photochromism on wool can be attributed to a decreased mobility of dye by the various interactions between the dye and wool molecules, which interferes the cis-trans isomeriation of dye. On Dacron T92 there can not be any obstacle for the cis-trans isomerization of dye, hence reversible color change may occur. The electron-releasing substituent on diazo component may be helpful for the photochromism of dye by increasing the n-electron density of phenyl ring, which can stabilize the cis-form of the dye by the interaction with the positive charge of imidazole ring.

• BMB Reports
• /
• v.42 no.3
• /
• pp.142-147
• /
• 2009

Small-molecule inhibitors of protein kinases have contributed immensely to our understanding of biological signaling path-ways and have been exploited therapeutically for the treatment of cancers and other disease states. The pyridinyl imidazole compounds SB 203580 and SB 202190 were identified as ATP competitive antagonists of the p38 stress-activated protein kinases and have been widely used to elucidate p38-dependent cellular processes. Here, we identify SB 203580 and SB 202190 as potent inhibitors of stress-induced CREB phosphorylation on Serine 111 (Ser-111) in intact cells. Unexpectedly, we found that the inhibitory activity of SB 203580 and SB 202190 on CREB phosphorylation was independent of p38, but instead correlated with inhibition of casein kinase 1 (CK1) in vitro. The inhibition of CK1-mediated CREB phosphorylation by concentrations of pyridinyl imidazoles commonly employed to suppress p38, suggests that in some cases conclusions of p38-dependence derived solely from the use of these inhibitors may be invalid.

• Journal of Welding and Joining
• /
• v.29 no.4
• /
• pp.54-60
• /
• 2011

Adhesive bonding is one of the most promising joining methods which may substitute for conventional metallurgical joining processes, such as welding, brazing and soldering. Curing behavior and mechanical properties of adhesive joint are largely dependent on the curing agent including hardener and catalyst. In this study, effects of curing system on the curing behavior and single-lap shear strength of epoxy adhesive joint are investigated. Dihydrazide, anhydride and dicyandiamide(DICY) were chosen as hardener and imidazole and triphenylphosphine(TPP) were chosen as catalyst. In curing behavior, TPP showed the delay of the curing rate for DICY and ADH at $160^{\circ}C$, compared to imidazole catalyst due to the high curing onset/peak temperature. DICY seemed to be most beneficial in the joint strength for both steel and Al adherends, although the type of adherends affected the shear strength of epoxy adhesive joint.

• Elastomers and Composites
• /
• v.44 no.2
• /
• pp.143-149
• /
• 2009

In this study, asphalt emulsion was manufactured by phase inversion emulsification method with nonionic surfactants(Span 80, Span 60, Tween 80, and Tween 60), anionic surfactant(SLS) and cationic surfactant(Imidazole) in different feeding ratio to make up for the week points of asphalt. Its stabilization was carefully investigated with respect to droplet size, viscosity, zeta potential, and water-proofing property. When the surfactants mixed with nonionic and anionic surfactant were used into the asphalt, a stabilization of the asphalt emulsion was good. As the amount of the mixed surfactant was increased, the droplet size of asphalt emulsion were decreased, while the viscosity and zeta potential were increased. When the surfactants mixed with nonionic and anionic surfactant were used into the asphalt, a stabilization of asphalt emulsion was good.

• Bulletin of the Korean Chemical Society
• /
• v.10 no.2
• /
• pp.172-177
• /
• 1989

Stereoselective solvolyses of optically active activated esters in the aggregate system of optically active polymeric surfactants containing imidazole and benzene moieties were performed. The catalyst polymers employed were copolymers of N-methacryloyl-L-histidine methyl ester (MHis) with N,N-dimethyl-N-hexadecyl-N-[10-(p-methacryloylo xyphenoxycarbonyl)-decyl]ammonium bromide(DEMAB). In the solvolyses of N-carbobenzoxy-D- and L-phenylalanine p-nitrophenyl esters (D-NBP and L-NBP) by polymeric catalysts, copoly(MHis-DEMAB) exhibited not only increased catalytic activity but also enhanced enantioselectivity as the mole ${\%}$ of surfactant monomers in the copolymers increased. The polymeric catalysts showed noticeable enantioselective solvolyses toward D- and L-NBP of the substrates employed. As the reaction temperature was lowered for the solvolyses of D- and L-NBP with the catalyst polymer containing 3.5 mole ${\%}$ of MHis, the increased reaction rate and enhanced enantioselectivity were observed. The coaggregative systems of the polymer and monomeric surfactants were also investigated. In the case of coaggregate system consisted of 70 mole ${\%}$ of cetyldimethylethylammonium bromide with polymeric catalyst showed maximum enantioselective catalysis, viz., $k_{cat}(L)/k_{cat}(D)$ = 2.85. The catalyst polymers in the sonicated solvolytic solutions were confirmed to form large aggregate structure by electron microscopic observation.

• Journal of the Korean Chemical Society
• /
• v.33 no.1
• /
• pp.3-10
• /
• 1989

In order to obtain a clue in understanding enzymatic hydrolysis in which the His-Cys moieties of papain protease is involved, we prepared cationic peptide-sufactants bearing histidyl, cysteinyl, and both histydyl and cysteinyl residues. Their catalytic efficiency toward the hydrolysis of PNPL were investigated in comicellar phases formed with $N^{+}C_{2}CysC_{12}$, $N^{+}C_{2}HisC_{12}$, $N^{+}C_{2}HisCysC_{12}$ increased markedly in the same order compared with that of $N^{+}C_{2}AlaC_{12}$. The markedly increased catalytic effects are attributed to the imidazole groups of $N^{+}C_{2}HisC_{12}$ and the thiol groups of $N^{+}C_{2}CysC_{12}$, and the large catalytic efficiency of $N^{+}C_{2}HisCysC_{12}$, is considered due to the interaction of the imidazole and the thiol groups. In order to investigate catalytic activities, rate constants for the functional groups, km* and dissociation constants, pKa have been determined. The results showed that $k^{\ast}_m$ and pKa of the imidazole groups were $7.91{\times}10^{-4}S^{-1}$ and 6.49, and those of the thiol groups were $6.00{\times}10^{-4}S^{-1}$ and 10.50. The catalytic effects of comicellar systems on the hydrolysis of p-nitrophenyl esters has increased according to the increasing size of the alkyl carbon number. Therefore, the catalytic effects have been increasing by the interaction of micellar hydrophobic parts and substrates as well as action of the functional groups.

• Elastomers and Composites
• /
• v.38 no.3
• /
• pp.213-226
• /
• 2003

The cure and rheological behavior of diglycidyl ether of bisphenol F/nadic methyl anhydride resin system with the kinds of imidazole were studied using a differential scanning calorimeter (DSC) and a rotational rheometer. The isothermal traces were employed to analyze cure reaction. The DGEBF/ anhydride conversion profiles showed autocatalyzed reaction characterized by maximum conversion rate at $20{\sim}40 %$ of the reaction. The rate constants ($k_1,\;k_2$) showed temperature dependance, but reaction order did not. The reaction order (m+n) was calculated to be close to 3. There are two reaction mechanisms with the kinds oi catalyst. The gel time was determined by using G'-G" crossover method, and the activation energy was obtained from this results. From measurement of rheological properties it was found that the logarithmic 1:elation time of fused silica filled DBEBF epoxy compounds linearly increased with the content of filler and decreased with temperature. The highly filled epoxy compounds showed typical pseudoplastic behavior, and the viscosity of those decreased with increasing maximum packing ratio.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.6
• /
• pp.1864-1866
• /
• 2013