• Journal of Photoscience
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• v.8 no.1
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• pp.33-37
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• 2001

Picosecond absorption spectroscopy has been employed in the study of the solvent dynamics of 1, 2, 4, 5-tetracyanobenzene/biphenyl derivative radical ion pairs, and the resulting rates of radical ion pair separation are faster in acetonitrile than in dichloromethane. In an effort to account quantitatively for such solvent effect on the rate of radical ion pair separation, an equation for the rate of radical ion pair separation is introduced, in which the rate depends exponentially on the electrostatic interaction energy in the radical ion pair. In our analysis of the types of electrostatic interaction energy based on the conducting spheres in dielectric continuum was chosen, and the rate equation employing this electrostatic energy provided information on the distance on the distance of radical ion pair separation and solvation energy of the radical ion pair, thereby providing quantitative explanation for the observed solvent effect on the rate of radical ion pair sepaaration.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.432-436
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• 2003

• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.539-540
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• 2008

• Journal of the Korean Chemical Society
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• v.27 no.4
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• pp.287-293
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• 1983

Free radical-initiated copolymerizations of diethyl ${\alpha}$-phenylvinyl phospbate (DEPVP) with acrylonitrile (AN) and maleic anhydride (MAnh) were studied. The monomer reactivity ratios for AN/DEPVP pair, determined at $70^{\circ}C$ in bulk using benzoyl peroxide as an initiator, were;$ r_1(AN) = 0.77, r_2(DEPVP) = 0.002$. The values of the Alfrey-Price constants, Q and e, for DEPVP were calculated to be 0.012 and -1.35, respectively. Free radical-initiated copolymerization of MAnh/DEPVP pair in chloroform at $70^{\circ}C$ produced 1 : 1 alternating copolymers regardless monomer feed composition with the highest copolymerization rate at the molar ratio of MAnh : DEPVP = 7 : 3. The equilibrium constant of a charge-transfer complex between DEPVP and MAnh in deutrated chloroform, determinated at room temperature by transformed Benesi-Hildebrand NMR method, was 0.085 l/mol. The reduced viscosity of copolymers of AN/DEPVP pair decreased as the content of DEPVP units increased, while that of MAnh/DEPVP pair remained more or less constant.

• Archives of Pharmacal Research
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• v.24 no.1
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• pp.39-43
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• 2001

4'-Bromoacetophenone analogs, which are able to generate monophenyl radicals capable of hydrogen atom abstraction, were investigated as possible photoinducible DNA cleaving agents. The potential of 4'-Bromoacetophenone as a possible new DNA cleaver is explored. Pyrrolecarboxatmid conjugated 4'-Bromoacetophenone, in particular, DNA cleaving activity and sequence-selectivity on the contiguous AT base pair sites.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.77-78
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• 1990

• Journal of Photoscience
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• v.9 no.2
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• pp.379-381
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• 2002

The major electron transfer cofactors in photosystem II have been studied by pulsed EPR, pulsed electron electron double resonance (PELDOR) and laser excited spin polarized electron spin echo envelope modulation (ESEEM) methods, in non-oriented and oriented photosystem II membranes. Distances between radical pairs were determined trom the observed dipole interaction constants to be 27.3 A for P680-QA, 30 A, etc. with the error within 1 A. Angles between the distance vector and membrane normal was determined by orientation dependence of oriented membranes with the accuracy of 5˚ The results were compared with the recent structural data by X-ray analysis.

• Journal of Nutrition and Health
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• v.29 no.7
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• pp.721-728
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• 1996

The level of oxidative tissue damage caused by free radicals generated from ethanol oxidation was determined in the myocardium of chronic ethanol fed-rats and the protective action of various radical scavenging enzymes was monitored, also. Adult male Sprague-Dawley rats were given ethanol in an amount of 36% of total calories via Lieber-DeCarli liquid diet for 6 weeks. Control group was pair-fed with the diet containing isocaloric amount of dextrin-maltose instead of ethanol. Chronic ethanol administration resulted in the increased amount of myocardial thiobarbituric acid reactive substance(TBARS), th parameter of lipid peroxidation, under our experimental condition. Chronic ethanol ingestion did not cause any change in activities of either glutathione peroxidase or glutathione reductase and glucose-6-phosphate dehydrogenase were decreased after ethanol treatment. Therefore, chronic ethanol administration seemed to cause considerble changes in cellular defense function against oxidative tissue damage in rat myocardium through glutathione utilizing system and radical generation system. However the ultimate net result of chronic ethanol inestion on the myocardium of rat was the oxidative tissue damage revealed by increased TBARS content.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.1
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• pp.1-6
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• 2017

Enhancements in NMR sensitivity have been the main driving force to extend the boundaries of NMR applications. Recently, techniques to shift the thermally populated nuclear spin states are employed to gain high NMR signals. Here, we introduce a technique called photochemically induced dynamic nuclear polarization (photo-CIDNP) and discuss its progresses in enhancing the solution-state NMR sensitivity.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.1
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• pp.88-95
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• 1998

The Electron/Hole Pair is generated when the Activation Energy produces by Ultraviolet Ray illumination to the Semiconductor. And $OH^-$ ion produces by Water Photo-Cleavage reacts with Positive Hole. As a result, OH Radical acting as strong oxidant is generated and then Photocatalytic Oxidation Reaction occurs. The Photocatalytic Oxidation can oxidize the chlorophenol to Chloride and Carbon Dioxide easier, safer and shorter than conventional Water Treatment Process With the same degree of chlorination, the $Cl^-$ ion at para (C4) position is most easily replaced by the OH radical. And then, the blocking effect of $OH^-$ ion between the $Cl^-$ ions and $Cl^-$ ions at symmetrical location is easily replaced by the OH radical. For mono-, di-, tri-chlorophenols, there is no obvious difference in decomposition rate, decomposition efficiency and completeness of the decomposition reaction except for 2,3-dichloropheno, 2,4,5-, 2,3,4-trichlorophenol. The decomposition efficiency is higher than 75% and completeness of the decomposition reaction is higher than 70%. Therefore, continuous flow photocatalytic reactor is promising process to remove the chlorinated aromatic compounds which is more toxic than non-chlorinated aromatic compound.