• Journal of the Korean Ceramic Society
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• v.52 no.2
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• pp.154-158
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• 2015

This paper investigates the reaction rates of $CO_2$ that stores carbonation through comparing the carbonation behavior between $Ca(OH)_2$ and fly ash with circulating fluidized bed combustion (CFBC) containing a large amount of free CaO. Because fly ash with CFBC contains abundant free CaO, it cannot be used as a raw material for concrete admixtures; hence, its usage is limited. Thus, it has been buried until now. In order to consider its reuse, we conduct carbonation reactions and investigate its rates. X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA), and X-ray fluorescence (XRF) are conducted for the physical and chemical analyses of the raw materials. Furthermore, we use a PH meter and thermometer to verify the carbonization rates. We set the content of the fly ash of CFBC, $Ca(OH)_2$, $CO_2$ flow rate, and water to 100 ~ 400 g, 30 ~ 120 g, 700 cc/min, and 300 ~ 1200 g, respectively, based on the content of the free CaO determined through the TG/DTA analyses. As a result, the carbonization rate of the fly ash with CFBC is the same as that of $Ca(OH)_2$, and it tends to increase linearly. Based on these results, we investigate the carbonization behavior as a function of the free CaO content contained in the raw material.

• Journal of the Korean Chemical Society
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• v.29 no.6
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• pp.629-636
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• 1985

The rates of solvolysis of trans-$[Co(AA)_2Cl_2]^+$ in which AA indicates ethylenediamine(en), N-ethylethylenediamine (N-eten), N-methylethylenediamino (N-meen) and trimethylenediamine(tn) respectively have been investigated using conductometric and spectrophotometric methods at various pressure up to 2,000 bar in acetone-water mixture. The activation volumes (${\Delta}V^{\neq}) obtained from the pressure effect on rate constants were -0.2∼0.9 $cm^3mole^{-1}$ for en, -0.2∼0.6 $cm^3mole^{-1}$ for N-eten, -0.8∼6.0 $cm^3mole^{-1}$ for N-meen and 0.7∼7.0$cm^3mole^{-1}$ for tn. The rates of solvolysis of these complexes were analyzed by comparing with the results obtained from excess free energy ($G^E$) and free energy cycle. It was found that $S_N1$ character was increased with decreasing the pressure and increasing the content of acetone in the mixture solvent. In addition to that, the effect of charge separation on the mechanism of solvolysis was discussed.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.170-173
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• 2002

Electron spin resonance (ESR) spectroscopy was used to detect free radicals in irradiated wheat flour and glutinous rice flour. They were irradiated with doses of 0, 0.1, 0.5, 1 and 2 kGy at room temperature using a Co-60 irradiator. Free radicals detected for irradiated wheat flour and glutinous rice flour were higher than those of unirradiated ones. Since concentration of free radicals linearly increased with applied doses $(0.1{\sim}2\;kGy)$, highly positive correlation coefficients $(R^2=0.9995{\sim}0.9998)$ were obtained between irradiation doses and free radical concentrations right after irradiation. Although concentration of free radicals slowly decreased with storage time, the characteristic ESR signals of free radical in irradiated samples were observed even after 4 weeks of storage at room temperature.

• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.913-922
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• 2019

Magnetic $Ni_{0.7}Co_{0.3}Fe_2O_4$ nanoparticles that were prepared via the rapid combustion process were functionalized and modified to obtain magnetic $Ni_{0.7}Co_{0.3}Fe_2O_4@SiO_2-CHO$ nanocomposites, on which penicillin G acylase (PGA) was covalently immobilized. Selections of immobilization concentration and time of fixation were explored. Catalytic performance of immobilized PGA was characterized. The free PGA had greatest activity at pH 8.0 and $45^{\circ}C$ while immobilized PGA's activities peaked at pH 7.5 and $45^{\circ}C$. Immobilized PGA had better thermal stability than free PGA at the range of $30-50^{\circ}C$ for different time intervals. The activity of free PGA would be 0 and that of immobilized PGA still retained some activities at $60^{\circ}C$ after 2 h. $V_{max}$ and $K_m$ of immobilized PGA were 1.55 mol/min and 0.15 mol/l, respectively. Free PGA's $V_{max}$ and $K_m$ separately were 0.74 mol/min and 0.028 mol/l. Immobilized PGA displayed more than 50% activity after 10 successive cycles. We concluded that immobilized PGA with magnetic $Ni_{0.7}Co_{0.3}Fe_2O_4@SiO_2-CHO$ nanocomposites could become a novel example for the immobilization of other amidohydrolases.

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.121-122
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• 2002

• Biomolecules & Therapeutics
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• v.7 no.2
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• pp.121-126
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• 1999

In an attempt to define the effects of hyperbaric oxygen treatment on the lipid peroxidation and oxygen free radical reactions in rats exposed to carbon monoxide, we studied malondialdehyde (MDA) level and activities of catalase and superoxide dismutase in the kidney of the rats exposed to carbon monoxide. Male Sprague-Dawley albino rats weighing 240 to 260 gm were used. Experimental groups consist of Control group (=breathing with air), HBO group (=exposed to hyperbaric oxygen 〔HBO, 3ATA, 100%〕 after air breath), CO group (=exposed to CO〔3,970 ppm〕after air breath), CO-Air group (=exposed to CO after air breath followed by air breath) and CO-HBO group (=exposed to CO after air breath followed HBO treatment). The CO group showed significantly higher MDA level, catalase activity and SOD activity as compared to that of control group. The CO-HBO group showed significantly lower MDA level as compared to that of CO group, and did not show significantly lower catalase activity and SOD activity as compared to that of CO group. These results suggest that the excessive oxygen free radicals is an important determinant in pathogenesis of CO-induced nephrotoxicity and HBO inhibits the lipid peroxidation caused by excessive oxygen free radicals in the kidney of the rats exposed to carbon monoxide.

• Journal of Nutrition and Health
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• v.36 no.4
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• pp.376-381
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• 2003

Acyl-CoA synthetase 4 (ACS4) is an arachidonate-preferring enzyme abundant in steroidogenic tissues. We examined ACS4 in rat liver, which contains a variety of pathways that use acyl-CoAs, in order to determine subcellular locations. We demonstrate that ACS4 protein was present most abundantly in the mitochondria and to a much lesser extent in the peroxisomes and microsomes. To determined the dietary effects on the level of ACS4 mRNA, northern blotting was carried out using total RNA from the livers of adult male rats fed various diets. Fasting, high fat diet, and fat-free high sucrose diet increased the hepatic level of ACS4 mRNA approximately 2-fold. Furthermore, the levels of ACS4 mRNA were induced by DEHP[Di- (2-ethylhexyl) phthalate]. These data suggest that ACS4 expression in the liver is regulated with a variety of pathways, including $\beta$-oxidation, hormone, and insulin.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.279.2-279
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• 2001

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.445-452
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• 2015

A tubular packed bed reactor for the steam-$CO_2$ combined reforming of natural gas to produce the synthesis gas of a target $H_2/CO$ ratio 2.0 was simulated. The effects of the reactor dimension, the feed gas composition, and the gas feeding temperature upon the possibility of coke formation across the catalyst bed were investigated. For this purpose, 2-dimensional heterogeneous reactor model was used to determine the local gas concentrations and temperatures over the catalyst bed. The thermodynamic potential distribution of coke formation was determined by comparing the extent of reaction with the equilibrium constant given by the reaction, $CH_4+2CO{\Leftrightarrow}3C+2H_2O$. The simulation showed that catalysts packed in the central region nearer the entrance of the reactor were more prone to coking because of the regional characteristics of lower temperature, lower concentration of $H_2O$, and higher concentration of CO. With the higher feeding temperature, the feed gas composition of the increased $H_2O$ and correspondingly decreased $CO_2$, or the decrease in the reactor diameter, the volume fraction of the catalyst bed subsequent to coking could be diminished. Throughout the simulation, reactor dimension and reaction condition for coking-free operation were suggested.

• Journal of the Korean institute of surface engineering
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• v.51 no.4
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• pp.243-248
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• 2018

All solid state thin film batteries with two types of cell structure, Pt / $LiCoO_2$ / LiPON / Cu and Pt / $LiCoO_2$ / LiPON / $LiCoO_2$ / Cu, are prepared and their electrochemical performances are investigated to evaluate the effect of $LiCoO_2$ interlayer at the interface of LiPON / Cu. The crystallinity of the deposited $LiCoO_2$ thin films is confirmed by XRD and Raman analysis. The crystalline $LiCoO_2$ cathode thin film is obtained and $LiCoO_2$ as the interlayer appears to be amorphous. The surface morphology of Cu current collector after cycling of the batteries is observed by AFM. The presence of a 10 nm-thick layer of $LiCoO_2$ at the interface of LiPON / Cu enhances the interfacial adhesion and reduces the interfacial resistance. As a result, Li plating / stripping at the interface of LiPON / Cu during charge/discharge reaction takes place more uniformly on Cu current collector, while without the interlayer of $LiCoO_2$ at the interface of LiPON / Cu, the Li plating / stripping is localized on current collector. The thin film batteries with the interlayer of $LiCoO_2$ at the interface of LiPON / Cu exhibits enhanced initial coulombic efficiency, reversible capacity and cycling stability. The thickness of the anode current collector Cu also appears to be crucial for electrochemical performances of all solid state thin film batteries.