• Korean Journal of Environmental Agriculture
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• v.12 no.2
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• pp.169-175
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• 1993

O-Ethyl S-methyl ethylphosphonothioate was studied for chemical and metabolic oxidation using $^{31}P-NMR$ analyses. The chemical shifts of O-ethyl ethylphosphonic acid (2) which is one of major metabolites were changed with the variation of oxidation systems. $^{31}P-NMR$ chemical shifts of 2 were observed at 40.15ppm from oxidaton by MCPBA, 30.98 ppm by MMPP, 29.31 ppm from in vitro rat liver microsomal oxidation, and 29.10 ppm from in vivo metabolism in houseflies. $^{31}P-NMR$ chemical shift of 2 in two different solvents such as deutero-chloroform and deuterium oxide were observed at 30.70 ppm and 40.15 ppm, respectively. And those of the metabolites were also observed at around 30 ppm under the conditions of pH 3, 5.6 and 14 and 47.91 ppm under pH 1 which is a strong acidic condition. It could be explained that the ionized form of 2 should have greater shielding effect on phosphorus atom and hence shows upfield chemical shift in polar solvents and alkaline conditions. On the other hand, a protonated form under organic solvents and the strong acidic condition should have less shielding effect than its ionized form, shifting the peak downfield.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.2
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• pp.57-60
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• 2005

Semiconductor carbon nanotube was grown on oxided silicon wafer with atmosphere pressure chemical vapor deposition (APCVD) method and investigated the electrical property after thermal oxidation at $300^{\circ}C$ in air. The electrical property was measured at room temperature in air after thermal oxidation at $300^{\circ}C$ for various times in air. Semiconductor carbon nanotube was steadily changed to metallic carbon nanotube as increasing of thermal oxidation times at $300^{\circ}C$ in air. Some removed area of carbon nanotube surface was shown with transmission electron microscopy (TEM) after thermal oxidation for 6 hours at $300^{\circ}C$ in air.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1543-1550
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• 2010

This work presents oxidation of formic acid on Bi-modified Pt nanoparticles of various sizes. The sizes of the studied Pt nanoparticles range from 1.5 to 5.6 nm (detailed in Rhee, C. K.; Kim, B.-J.; Ham, C.; Kim, Y.-J.; Song, K.; Kwon, K. Langmuir 2009, 25, 7140-7147), and the surfaces of the Pt nanoparticles are modified with irreversibly adsorbed Bi. The investigated coverages of Bi on the Pt nanoparticles are 0.12 and 0.25 as determined by coulometry of the oxidation of adsorbed hydrogen and Bi, and X-ray photoelectron spectroscopy. The cyclic voltammetric behavior of formic acid oxidation reveals that the adsorbed Bi enhances the catalytic activity of Pt nanoparticles by impeding a poison-forming dehydration path with a concomitant promotion of a dehydrogenation path. The chronoamperometric results indicate that elemental Bi and partially oxidized Bi are responsible for the catalytic enhancement, when the Bi coverages on Pt nanoparticles are 0.12 and 0.25, respectively. The size effect of Bi-modified Pt nanoparticles in formic acid oxidation is discussed in terms of specific activity (current per unit surface area) and mass activity (current per unit mass).

• Bulletin of the Korean Chemical Society
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• v.32 no.10
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• pp.3660-3665
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• 2011

CO-tolerant PtMo/C alloy electrocatalyst was prepared by a colloidal method, and its electrocatalytic activity toward CO oxidation was investigated. Electrochemical study revealed that the alloy catalyst significantly enhanced catalytic activity toward the electro-oxidation of CO compared to Pt/C counterpart. Cyclic voltammetry suggested that Mo plays an important role in promoting CO electro-oxidation by facilitating the formation of active oxygen species. The effect of Mo on the electronic structure of Pt was investigated using X-ray absorption spectroscopy to elucidate the synergetic effect of alloying. Our in-depth spectroscopic analysis revealed that CO is less strongly adsorbed on PtMo/C catalyst than on Pt/C catalyst due to the modulation of the electronic structure of Pt d-band. Our investigation shows that the enhanced CO electrooxidation in PtMo alloy electrocatalyst is originated from two factors; one comes from the facile formation of active oxygen species, and the other from the weak interaction between Pt and CO.

• Journal of the Korean Chemical Society
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• v.10 no.4
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• pp.153-157
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• 1966

The measurement of Oxidation of nickel has been investigated using vacuum quartz microbalance in the temperature range of $500^{\circ}{\sim}800^{\circ}C$ at various oxygen pressure. The rate constants of nickel-oxidation were evaluated according to the parabolic rate law. From the Arrhenius equation, the activation energy in the range of experimental temperatures were found that $E_{act}$= 35.4 Kcal/mole. It was also found that the parabolic rate constants varied approximately as the one fifth power of the oxygen pressure for nickel-oxidation. The mechanism for the oxidation of this metal were seemed to be via cation vacancy produced by excess of oxygen dissolved in the oxide film.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.79-84
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• 2024

Methane is an abundant and renewable hydrocarbon, but it causes global warming as a greenhouse gas. Therefore, methods to convert methane into useful chemicals or energy sources are needed. Methanol is a simple and abundant chemical that can be synthesized by the partial oxidation of methane. Methanol can be used as a chemical feedstock or a transportation fuel, as well as a fuel for low-temperature fuel cells. However, the electrochemical oxidation of methanol is a complex and multi-step reaction. To understand and optimize this reaction, new electrocatalysts and reaction mechanisms are required. This review discusses the methanol oxidation reaction mechanism, recent research trends, and future research directions.

• Membrane and Water Treatment
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• v.3 no.3
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• pp.181-200
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• 2012

At present water crisis is not an issue of scarcity, but of access. There is a growing recognition of the need for increased access to clean water (drinkable, agricultural, industrial use). An encouraging number of innovative technologies, systems, components, processes are emerging for water-treatment, including new filtration and disinfectant technologies, and removal of organics from water. In the past decade many methods have been developed. The most important membrane-based water technologies include reverse osmosis (RO), ultrafiltration (UF), microfiltration (MF), and nanofiltration. Beside membrane based water-treatment processes, other techniques such as advanced oxidation process (AOP) have also been developed. Some unconventional water treatment technology such as magnetic treatment is also being developed.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.229-232
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• 2009

We prepared gold nanoparticles (Au NPs) by reduction-oxidation reaction between $HAuCl_4$ and trisodium citrate and measured the size and morphology of Au NPs by TEM for various molar ratios of $HAuCl_4$ to citrate and for various concentrations of $HAuCl_4$. UV-vis spectroscopy was used to characterize the optical properties of Au NPs. Au NPs in the size range from 14.3 nm to 20.3 nm were prepared with monodisperse distribution.

• BMB Reports
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• v.33 no.1
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• pp.37-42
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• 2000

Based on the study by Leatham and Stabmann concerned with the rates (v) of amines and phenolic compounds oxidation catalyzed by laccase of basidiomycete Lentinus edodes (Berk.) Sing., as well as on the results of semiempirical quantum chemical computations using the PM3 method, the linear correlations of v and lnv values with first vertical ionization potentials of the substrates molecules and radicals derived from them, spin densities on N and O atoms of the above radicals, and with the radicals reorganization energies have been found.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.188-191
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• 2003

In this wort. the effect of anodic oxidation on surface characteristics of high strength PAN-based carbon fibers is investigated in terms of surface and mechanical interfacial properties of the composites. As a result, the acidity of carbon fiber surfaces is increased, due to the development of oxygen functional groups in the presence of anodic oxidation. Also. it is found that the critical stress intensity factor ($K_{IC}$) is improved in the oxidized fibers-reinforced composites. which can be attributed to the good wettability between fibers and epoxy resin matrix.