• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1932-1936
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• 2008

A new analytical method using 1-(2-pyridylazo)-2-naphthol modified $SiO_2$ nanoparticles as solid-phase extractant has been developed for the preconcentration of trace amounts of mercury(II) in different water samples. Conditions of the analysis such as preconcentration time, effect of pH, sample volumes, shaking time, elution conditions and effects of interfering ions for the recovery of analyte were investigated. The adsorption capacity of nanometer $SiO_2$-PAN was found to be 260 ${\mu}molg^{-1}$ at optimum pH and the detection limit (3$\sigma$) was 0.48 ${\mu}gL^{-1}$. The extractant showed rapid kinetic sorption. The adsorption equilibrium of mercury(II) on nanometer $SiO_2$-PAN was achieved just in 5 mins. Adsorbed mercury(II) was easily eluted with 5 mL of 6 M hydrochloric acid. The maximum preconcentration factor was 50. The method was applied for the determination of trace amounts of mercury(II) in various water samples and industrial effluents.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.179-183
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• 2002

Resonance-enhanced multiphoton ionization with time-of-flight product imaging of the $N(^2D)$ atoms has been used to study the $N_2O$ photodissociation at 118.2 nm and the two-photon dissociation at 268.9 nm. These imaging experiments allowed the determination of the total kinetic energy distribution of the $NO(X^2{\prod})$ and $N(^2D_{5/2})$ products. The $NO(X^2{\prod})$ fragments resulting from the photodissociation processes are produced in highly vibrationally excited states. The two-photon photodissociation process yields a broad $NO(X^2{\prod})$ vibrational energy distribution, while the 118.2 nm dissociation appears to produce a vibrational distribution sharply peaked at $NO(X^2{\prod},\;{\nu}=14)$.

• BMB Reports
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• v.35 no.3
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• pp.302-305
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• 2002

Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at $27^{\circ}C$ using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to $140\;{\mu}M$ by the microcalorimetry method, which agrees well with the value of $143\;{\mu}M$ for the inhibition constant that was obtained from the spectroscopy method.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1243-1252
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• 2009

User-friendly software was developed to determine the shelf-life of perishable Korean seasoned side dishes in real time based on growth models of spoilage and pathogenic microorganisms. In the program algorithm, the primary spoilage and fastest-growing pathogenic organisms are selected according to the product characteristics, and their growth is simulated based on the previously monitored or recorded temperature history. To predict the growth of spoilage organisms with confidence limits, kinetic models for aerobic bacteria or molds/yeasts from published works are used. Growth models of pathogenic bacteria were obtained from the literature or derived with regression of their growth rate data estimated from established software packages. These models are also used to check whether the risk of pathogenic bacterial growth exceeds that of food spoilage organisms. Many example simulations showed that the shelf-lives of the examined foods are predominantly limited by the growth of spoilage organism rather than by pathogenic bacterial growth.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2003.11a
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• pp.46-46
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• 2003

Hypocholesterolemic peptide isolated from glycimin (11S protein) hydrolyzate by trypsin was purified and identified as LPYP and IAVPGEVA. To investigate the effects of phyiscal properties of side chains of the hypocholesterolemic activity, some of mutant peptides were designed and synthesized chemically. The structure related structures of each peptide were simulated and constructed and their conformations were observed by using spectropolarimeter. The hypocholesterolemic activities were monitored by assaying the inhibition of 3-hydroxy-3-methylglutaryl CoA reductase (HMG-CoA reductase) in vitro and by the determination of cholesterol content in mice serum. For LPYP derivatives, Hypocholesterolemic activity was lost when hydrophobic leucine residue at N-terminus was not so critical for maintaining hypocholesterolemic activity. For idealogical design of hypocholesterolemic peptides, the structure of HMG-CoA reductase are shown and inhibition mechanism of some peptides or inhibitors will be presented. For IAVPGEVA derivative inhibition of HMG-CoA reductase has been studied. For detail study of hypocholesterolemic activity, kinetic study of inhibition of peptides on HMG-CoA reductase and structural view of ligand binding should be investigated.

• Journal of the Korean Chemical Society
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• v.13 no.4
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• pp.281-287
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• 1969

Rate constans for the chloride exchange of some arylmethylchloride in dry acetone have been determined, and activation parameters have been evaluated. The reactivities of substates are explained with perturbational molecular orbital (PMO) method and HSAB principle. It was found that carbon-chlorine resonance integral at the transition state is a out 67% of ${\beta}$, the carbon-carbon resonance integral.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1269-1275
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• 2003

The quaternary carbon-containing alcohols (1-6) were resolved enantioselectively by various lipases such as PFL (Pseudomonas fluorescens lipase), LAK (Pseudomonas fluorescens lipase), CRL (Candida rugosa lipase) and PCL (Pseudomonas cepacia lipase). The enzymatic resolution of racemic alcohol $({\pm})-2$ gave the excellent enantioselectivity in favor of (S)-2d in 99% ee, while those of the racemic alcohols (1, 3, 4, 5 and 6) gave the resolved alcohols with moderate to good enantioselectivity. Also, their absolute configurations were determined by chemical transformation to the known compounds.

• Toxicological Research
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• v.14 no.4
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• pp.557-562
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• 1998

Allyl alcohol is metabolized in the liver through two steps, first to reactive acrolein by alcohol dehydrogenase (ADH), subsequently to acrylic acid by aldehyde dehydrogenase (ALDH). Since ethanol could compete the same enzymes to be metabolized in the liver, we have determined the plasma concentrations of allyl alcohol and ethanol followed by combined treatment. Pretreatment of rats with 2g/kg ethanol followed by ip administration of 40mg/kg allyl alcohol increased the lethality significantly. Determination of in vivo blood concentrations revealed that ethanol pretreatment caused the apparent decrease in allyl alcohol clearance, whereas acetaldehyde level in blood increased significantly by allyl alcohol treatment, as determined by head space GC analysis. Treatment of 4-methylpyrazole, an inhibitor of ADH, delayed allyl alcohol elimination significantly and reduced its lethality. Collectively, these findings suggested that reduction of allyl alcohol clearance in the presence oj ethanol was mediated through ADH competitive inhibition.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.107-112
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• 2014

Using a chlorosulphonated polyethylene rubber solution for a binder of graphite powder and ferrocene for a mediator, a rose leaf tissue-embedded biosensor was built. Linearity on the Hanes-Woolf plot showed the reduction of the substrate was attained through the catalytic power of the rose peroxidase in the experimental range of electrode potential. Furthermore, 10 or more electrochemical parameters demonstrated that the electrode exerts its sensing ability quantitatively. The foregoing gave the full conviction that rose tissue can be used in place of the currently marketed enzyme for the practical use of enzyme electrode.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.734-745
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• 2016

This review article described the electrochemical Frumkin, Langmuir, and Temkin adsorption isotherms of over-potentially deposited hydrogen (OPD H) and deuterium (OPD D) for the cathodic $H_2$ and $D_2$ evolution reactions (HER, DER) at Pt, Ir, Pt-Ir alloy, Pd, Au, and Re/normal ($H_2O$) and heavy water ($D_2O$) solution interfaces. The Frumkin, Langmuir, and Temkin adsorption isotherms of intermediates (OPD H, OPD D, etc.) for sequential reactions (HER, DER, etc.) at electrode/solution interfaces are determined using the phase-shift method and correlation constants, which have been suggested and developed by Chun et al. The basic procedure of the phase-shift method, the Frumkin, Langmuir, and Temkin adsorption isotherms of OPD H and OPD D and related electrode kinetic and thermodynamic parameters, i.e., the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. potential (E) behavior (${\theta}$ vs. E), equilibrium constant (K), interaction parameter (g), standard Gibbs energy (${\Delta}G_{\theta}{^{\circ}}$) of adsorption, and rate (r) of change of ${\Delta}G_{\theta}{^{\circ}}$ with ${\theta}$ ($0{\leq}{\theta}{\leq}1$), at the interfaces are briefly interpreted and summarized. The phase-shift method and correlation constants are useful and effective techniques to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and related electrode kinetic and thermodynamic parameters (${\theta}$ vs. E, K, g, ${\Delta}G_{\theta}{^{\circ}}$, r) at electrode/solution interfaces.