• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.466-468
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• 1999

• Microbiology and Biotechnology Letters
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• v.19 no.1
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• pp.100-108
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• 1991

Molecular characteristics and improving methods for thermal stability of enzyme have been considered. Intrinsic and extrinsic stabilizing mechanisms are two governing principles for enhanced thermal stability of enzyme in molecular basis. Factors contributing to the former and the latter mechanisms may be involved in the enhanced thermal stability of enzyme complementarily. Also, the methods for improving thermal stability of enzyme which comprise reaction in organic solvent system, chemical modification, immobilization, sequential unfolding and refolding, gene manipulation techniques and enzyme-antibody complexing are reviewed.

• Advances in Traditional Medicine
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• v.1 no.1
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• pp.1-7
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• 2000

Although Oriental medicines have long been used effectively in treating many diseases throughout the world, the pharmacological mechanisms of most Oriental medicines used have not been defined. As part of our continuing search for biologically active antiallergic drugs from natural sources, Oriental medicines were analyzed. Some Oriental medicines have been used against various allergic diseases for generations, and still occupies an important place in traditional medicine in Korea. It is also still unclear how Oriental medicine prevents allergic disease in experimental animal models. Some Korean folk medicines inhibited the mast cell-mediated allergic reaction. This review summarizes the effective folk medicine in experimental effect of allergic reaction. Potential antiallergic folk medicines include: Poncirus trifoliata; Siegesbeckia glabrescence; Solanum lyratum; Aquilaria agallocha; Ulmi radicis; Polygonum tinctorium; Hwanglyun-Haedok-Tang; Rehmannia glutinosa; Kum- Hwag-San; Syzygium aromaticm; Spirulina platensis; Sosiho-Tang; Sinomenium acutum; Schizonepta tenuifolia; Shini-San; Magnoliae flos; Sochungryoung-Tang; Oryza sativa; Cryptotympana atrata; Salviae radix; Rosa davurica; Asiasari radix; Chung-Dae-San; and Cichorium intybus. Understanding the mechanisms of action for these Oriental medicines can permit drug development and laying of the ground-work for evaluating potential synergistic effects by addition and subtraction of prescriptions.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.250-257
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• 1987

The electrical conductances for the thorium (IV) complexes with crown ethers have been measured in DMSO, and water solvents, and the oxidation-reduction reaction mechanisms, electron number and diffusion coefficients in the reversible reduction process have been examined by polarography and cyclic voltammography. The dissociation mole ratio of $Th^{4+}$ and nitrate ion are 1:1 and in aprotic solvent, and 1:4 in protic solvent like as water. The limiting molar conductances of all complexes in aprotic solvent have been found to be in the range of $92.2{\times}159$ $ohm^{-1}cm^2mol^{-1}$. In aprotic solvent, DMSO, the reduction of each complex is reversible by one electron reduction of one step, and the range of diffusion coefficients is obserbed to be $5.83\;10^{-6}{\sim}6.90{\times}10^{-6}$. The complexes which have reduction step were hydrolyzed above at 1.8volt with reference saturated calomel electrode, generating the hydrogen gas. The reaction mechanisms of thorium (IV)-crown ether complexes appear as follows. ${Th_m(IV)L_n(H_2O)_x(NO_3)_{4y}}_=^{DMSO} {\overline{{Th_m(IV)L_n(H_2O)_x(NO_3)_{4y-1}}}^+ + NO_3-$

• Natural Product Sciences
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• v.15 no.3
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• pp.139-143
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• 2009

The anaphylactic allergic reaction is involved in many allergic diseases such as asthma and allergic rhinitis. In this report, I investigated the effect of ripe fruits of Rubus coreanus Miq. (Rosaceae) (RFRC) on the anaphylactic allergic reaction and studied its possible mechanisms of action. RFRC inhibited compound 48/80-induced systemic anaphylactic reaction in mice. RFRC dose-dependently decreased the IgE-mediated passive cutaneous anaphylaxis. In addition, RFRC decreased the gene expression and production of tumor necrosis factor-$\alpha$ (TNF-$\alpha$) and interleukin (IL)-6 in phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187 (A23187)-stimulated human mast cells. These findings provide evidence that RFRC could be a candidate as an anti-allergic agent.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.655-661
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• 1999

${\beta}$-SiC formation mechanism in Si melt-C-SiC system with varying in size of carbon source was investigated. A continuous reaction sintering process using Si melt infiltration method was adopted to control the reaction sintering time effectively. It was found that ${\beta}$-SiC formation mechanism in Si melt-C-SiC system was directly affected by the size of carbon source. In the Si melt-C-SiC system with large carbon source ${\beta}$-SiC formation mechanism could be divided into two stages depending on the reaction sintering time: in early stage of reaction sintering carbon dissolution in Si melt and precipitation of ${\beta}$-SiC was occurred preferentially and then SIC nucleation and growth was controlled by diffusion of carbon throughy the ${\beta}$-SiC layer formed on graphite particle. Furthmore a dissolution rate of graphite particles in Si melt could be accelerated by the infiltration of Si melt through basal plane of graphite crystalline.

• Fibers and Polymers
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• v.5 no.3
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• pp.234-238
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• 2004

Tyrosinase oxidizes the tyrosyl residues in silk fibroin (SF) with oxygen, resulting in the production of ο-quinone residues. Subsequently, the inter-or intramolecular crosslinks are formed by reaction with amino groups in through nonenzymatic process. The measurement of oxygen consumption proved that the tyrosyl residues in SF were mostly oxidized to quinone residues by tyrosinase. The reaction mechanisms were proposed in this study and the crosslinking reaction of ο-quinone residues and the enzymatic oxidation of tyrosyl residues could be confirmed by the measurements of UV, $^1$H-NMR and GFC.

• Analytical Science and Technology
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• v.8 no.4
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• pp.649-654
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• 1995

The reactivity of superoxide ion($O{_2}^{-.}$) with halogenated substrates is investigated by cyclic voltammetry and rotated ring-disk electrode method in aprotic solvents. The more positive the reduction potential of the substituted nitrile, the more facile is nucleophilic displacement by $O{_2}^{-.}$. The reaction rates of halogenonitriles with $O{_2}^{-.}$ vary according to the leaving-group propensity of halide (Br>Cl>F). The relative reaction rates of other substituted nitriles are in the order of electron-withdrawing propensity of the substituent group (CN> $C(O)NH_2$ >Ph, $CH_2CN$). The reaction of $O{_2}^{-.}$ with dihalocarbons indicates that five-membered rings can be rapidly formed by the cyclization of substrate and $O{_2}^{-.}$, and the relative rates of cyclization depend on the number of methylenic carbons {$Br(CH_2)_nBr$, [n=1<2<3>4>5]}. Mechanisms are proposed for the reaction of $O{_2}^{-.}$ with halogenated substrates.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_3
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• pp.127-137
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• 2001

The sonochemical Process has been applied as a treatment method and was investigated its effect on the decomposition of humic substances(HS). The reaction kinetics and mechanisms in the Process of sonochemical treatment for humic substances(HS) in wastewater have also been discussed. It was observed that the metal ions such as Fe(II) and Mn(II) showed catalytic effects, while Al(III), Ca(II), and Mg(II) had inhibitory effects on the decomposition of humic substances in sonochemical reaction with hydrogen peroxide. Experimental results also showed factors such as hydrogen peroxide dose affected the formation of disinfection by-products. Two trihalomethanes, chloroform and dichlorobromomethane were formed as major disinfection by-products during chlorination. The mechanism of radical reaction is controlled by an oxidation process. The radicals are so reactive that most of them are consumed by HS radicals and hydroxyl radicals can be acted on organic solutes by hydroxyl addition, hydrogen abstraction, and electron transfer. The depolymerization and the radical reaction of HS radicals appear to occur simultaneously. The final steps of the reaction are the conversion of organic acids to carbon dioxide.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.1
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• pp.46-52
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• 2009

The oxidation of surrogate mixtures for gasoline fuel was studied numerically in perfectly stirred reactor(PSR) to develope the needed detailed reaction mechanism. The reaction mechanism was assembled with the mechanisms for the oxidation of iso-octane or kerosene. It was shown that the reaction model predicted reasonably well the concentration profiles of fuel and major species reported in the literature. As the addition of kerosene into iso-octane as fuel was increased, the concentrations of $C_2H_2$ and benzene became high. Especially benzene known as a carcinogen appeared at a very high concentration in the flue gases.