• Environmental Engineering Research
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• v.11 no.6
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• pp.293-302
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• 2006

The reaction of ozone with NOM (Natural Organic Matter) can occur by two different pathways: that involving molecular ozone and by way of reactions with hydroxyl radicals which are produced from the decomposition of molecular ozone. As such, the formation of ketoacids and Assimilable Organic Carbon (AOC) can be controlled by controlling the pathway by which ozone reacts with NOM. The ratios of $[OH{\cdot}]/[O_3]$ ($R_{CT}$ values) were determined under the various ozonation conditions. The $R_{CT}$ values increased with increasing initial ozone concentration. The $R_{CT}$ values (ranges from 10 to $35^{\circ}C$) increased linearly as temperature increased (within the range from 10 to $35^{\circ}C$). However, $R_{CT}$ was independent of hydraulic retention time (HRT). Operational conditions were found to affect the formation of AOC. The conditions where the molecular ozone reaction predominated resulted in an increase in the formation of AOC.

• BMB Reports
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• v.37 no.3
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• pp.325-329
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• 2004

Oxidation of catecholamines may contribute to the pathogenesis of Parkinson's disease (PD). The effect of the oxidized products of catecholamines on the modification of Cu,Zn-superoxide dismutase (SOD) was investigated. When Cu,Zn-SOD was incubated with the oxidized 3,4-dihydroxyphenylalanine (DOPA) or dopamine, the protein was induced to be aggregated. The deoxyribose assay showed that hydroxyl radicals were generated during the oxidation of catecholamines in the presence of copper ion. Radical scavengers, azide, N-acetylcysteine, and catalase inhibited the oxidized catecholamine-mediated Cu,Zn-SOD aggregation. Therefore, the results indicate that free radicals may play a role in the aggregation of Cu,Zn-SOD. When Cu,Zn-SOD that had been exposed to catecholamines was subsequently analyzed by an amino acid analysis, the glycine and histidine residues were particularly sensitive. These results suggest that the modification of Cu,Zn-SOD by oxidized catecholamines might induce the perturbation of cellular antioxidant systems and led to a deleterious cell condition.

• Journal of Pharmaceutical Investigation
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• v.25 no.4
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• pp.313-322
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• 1995

The covalent conjugation of human recombinant superoxide dismutase (hrSOD) with trichloros-triazine activated polyethylene glycol (PEG) 5000 formed soluble conjugates with molecular weight of 92KD, which retained $90{\sim}98%$ of original activity with a markedly prolonged plasma half-life of enzyme activity. The effect of hrSOD-PEG conjugates on acetaminophen (ACP)-induced hepatotoxicity was tested in male rats which were pretreated with 3-methylcholanthrene. HrSOD-PEG conjugates inhibited the hepatotoxicity produced by ACP, on the other hand, native hrSOD had no protective effect. The above results indicated that oxygen radicals might participate in the mechanism of the ACP-induced hepatotoxicity and that polymer conjugated-protein drugs with prolonged half-lives could be employed as an effective therapeutic agent.

• Journal of Integrative Natural Science
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• v.6 no.2
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• pp.71-75
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• 2013

$Bu_3Sn$-endded poly(vinyl)s with biological activity were obtained by the radical polymerization of vinyl monomers using thianthrene cation radical/$^nBu_3H$. Thianthrene cation and stannyl radicals promoted the homopolymerization and copolymerization of styrene and ethyl vinyl ether having number average molecular weights of 2000-3100. Tributyltin hydride functions as a chain transfer agent. Such polymereization by cationic thianthrene and stannyl radicals could provide some clues for the biological reaction in living animals. Plausible polymerization mechanisms were suggested.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.25-25
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• 2010

The spectroscopy over a region from 3 to 17 ${\mu}m$ based on the tuneable diode lasers (TDLAS) is the most powerful technique for in situ studies of the diagnostics of small molecules. The increasing interest in small molecules especially containing carbon, oxygen, hydrogen, and fluorine containing ones can be fulfilled by TDLAS at 0.0001 cm-1 resolution, because most of these compounds are infrared active. TDLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which can be employed for the time dependent studies in sub micro second scale. Information about gas temperature and population densities can also be derived from TDLAS measurements. Collisional energy transfer between the small molecules can be studied with TDLAS. Also, a variety of free radicals and molecular ions have been detected by TDLAS. Since plasmas with molecular feed gases are used in many applications, there are new applications in industrial field. Recently, the development of quantum cascade lasers (QCLs) offers an attractive new option for TDLAS.

• Journal of Radiation Industry
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• v.7 no.1
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• pp.51-54
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• 2013

Chitosan is a useful natural polymer material in many application fields such as biomaterials, water-treatment, agriculture, medication, and food science. However, the poor solubility limits its application. In this study, the effects of radiation on chitosan were investigated using gamma ray and electron beam irradiation. The chemical structure and molecular weight analysis show similar degradation effects of chitosan powder in both gamma ray and electron beam irradiation. However, the radiation irradiated chitosan in $H_2O$ has a lower molecular weight, since the hydroxyl radicals attack the glycosidic bonds. This effect is more clearly shown in the electron beam irradiation results.

• Plant Biotechnology Reports
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• v.5 no.1
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• pp.89-103
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• 2011

Two rice varieties, viz. Nonabokra and Pokkali, have been evaluated for their responses to salinity in terms of some physiological and biochemical attributes. During the exposure to salinity (200 mM concentration of sodium chloride for 24, 48, and 72 h), a significant increase in sodium was recorded which was also concomitant with the changes of other metabolic profiles like proline, phenol, polyamine, etc. The protein oxidation was significantly increased and also varied between the two cultivars. The changes in activities of anti-oxidative enzymes under stress were significantly different to the control. The detrimental effects of salinity were also evident in terms of lipid peroxidation, chlorophyll content, protein profiles, and generation of free radicals; and these were more pronounced in Pokkali than in Nonabokra. The assessment and analysis of these physiological characters under salinity could unravel the mechanism of salt responses revealed in this present study and thus might be useful for selection of tolerant plant types under the above conditions of salinity.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3618-3624
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• 2012

Photodissociation dynamics of propiolic acid ($HC{\equiv}C-COOH$) at 212 nm in the gas phase was investigated by measuring rotationally resolved laser-induced fluorescence spectra of OH ($^2{\Pi}$) radicals exclusively produced in the ground electronic state. From the spectra, internal energies of OH and total translational energy of products were determined. The electronic transition at 212 nm responsible for OH dissociation was assigned as the ${\pi}_{C{\equiv}C}{\rightarrow}{\pi}^*{_{C=O}}$ transition by time-dependent density functional theory calculations. Potential energy surfaces of both the ground and electronically excited states were obtained employing quantum chemical calculations. It was suggested that the dissociation of OH from propiolic acid excited at 212 nm should take place along the $S_1/T_1$ potential energy surfaces after internal conversion and/or intersystem crossing from the initially populated $S_2$ state based upon the potential energy calculations and model calculations for energy partitioning of the available energy among products.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.230-230
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• 2004

Polyamines, namely putrescine, spermidine, and spermine, are biogenic low-molecular-weight aliphatic amines. Polyamines play important roles in DNA stabilization, RNA and protein synthesis, membrane stabilization, modulation of ion channels, and protection against oxygen radicals and are essential for cell homeostasis, cell growth, and tumorigenesis. (omitted)

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.34-34
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• 2010

Absolute electron-impact cross sections for molecular targets including their radicals are important in developing plasma reactors and testing various plasma processing gases. However, low-energy electron collision data for these gases are sparse and only the limited cross section data are available. In this presentation, the methods and the status of measurements of, mainly, absolute elastic cross sections for electron-polyatomic molecule collisions will be discussed with recent results from Chungnam National University. Elastic cross sections are essential for the absolute scale conversion of inelastic cross sections, as well as for testing computational methods.