• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.113-118
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• 2014

We have investigated the combined pretreatment of electron beam irradiation (EBI) and water steam as a kenaf core pretreatment process. After each sample was exposed to electron beam dose ranging from 50 to 1,000 kGy, the irradiated sample was treated by water steam using an autoclave for 5-h at $120^{\circ}C$. The pretreated samples were characterized using FTIR-ATR and XRD. FTIR spectra and XRD analysis of nonpretreated and pretreated samples confirm that crystallinity changes were observed before and after the pretreatment. The crystallinity index (CrI) was increased from 50.6% for nonpretreated sample 55.0% for 500 kGy exposed sample. And then, we analyzed sugar yield that is the amount of produced mono-saccharides in pretreated sample by enzymatic hydrolysis; an enzyme activity rate was 70 FPU/mL and 40 CBU/mL, and the loading time was 24, 48 and 72-h. The highest sugar yield was 83.9% at 500 kGy after 72-h for enzymatic hydrolysis. The sugar yield of enzymatic hydrolysis for pretreatment samples was increased as doses are subsequently changed to 100, 200 and 300 kGy, allowing to give 50.8%, 58.6% and 67.9%, respectively.

• Journal of The Korean Association For Science Education
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• v.21 no.4
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• pp.658-667
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• 2001

In this study, the relationships among students' cognitive/affective variables, cognitive conflict induced by anomalous data, and conceptual change were investigated. Tests regarding background knowledge, field dependence-independence, learning strategy, logical thinking ability, goal orientation, self-efficacy on prior concept and ability, and control belief were administered. Tests of prior conceptions, responses to anomalous data, conception, and retention of conception were also administered. There were no significant correlations of cognitive conflict induced by anomalous data with students' cognitive and affective variables. However, prior knowledge on molecular motion, field dependence-independence, and learning strategy were significantly correlated with students' conception and retention of conception. Logical thinking ability was also correlated with their conception. Multiple regression analysis indicated that learning strategy significantly predicted students' conception and retention of conception. For the affective variables, self-efficacy on ability was significantly correlated with students' conception and retention of conception, and goal orientation was correlated with their conception. Self-efficacy on ability was a significant predictor on students' conception and retention of conception, and goal orientation on their conception.

• KSBB Journal
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• v.21 no.1 s.96
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• pp.20-27
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• 2006

The fibrinolytic activities of soluble proteins extracted from seeds of Coix lacryma-jobi L., Carthamus tinctorius L. and Malva venicillata L. were studied. Fibrinolytic activity of extract from C. lacryma-jobi L. showed 1.3 times higher than plasmin used as positive control. The fibrinolytic enzyme was confirmed and extracted directly from seed of C. lacryma-jobi L. by a fibrin zymography. The protein was composed of a single polypeptide and its apparent molecular weight was found to be 7.8 kDa, as judged by SDS-polyacrylamide gel electrophoresis. The effect of temperature for the proteolytic enzyme activity were stabilized above $50^{\circ}C$ and then dramatically decreased. Also, the enzyme activity was clearly inhibited by APMSF, PMSF and TPCK, suggesting that it is a member of the chymotrypsin-like serine pretense. In addition, effects of gamma-irradiated on seed of each plants were revealed that 8 Gy and 64 Gy were higher than others. This result shown that gamma-irradiation of seeds were capable to increase the fibrinolytic activity. All these results suggest the pretense is a fibrinolytic enzyme belong to a family of chymotrypsin-like serine pretense.

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.411-418
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• 2004

Mercury, one of the most diffused and hazardous organ-specific environmental contaminants, exists in a wide variety of physical and chemical states. The murcury with the nature which evaporates easily can cause an acute or chronic mercury poisoning to workers at mercury-handling workplaces. Although many studies indicate that mercury induces a deleterious damage, little has been reported from the investigations of mercury effects at surrounding levels in living things. The purpose of this study was to evaluate the biological effects of mercury chloride and ionizing radiation. Prepubertal male F344 rats were administered mercury chloride in drinking water throughout the experimental period or were given wholebody irradiation with a dose of 6.5 Gy. The amount changed of body weight during the experimental period showed a 4.9% rise in the mercury-treated group and 14.4% decline in the irradiated group compared with the level of the control group. The results of hematological analysis (red blood cells, white blood cells, hemoglobin, and hematocrit) indicated the differential effects of mercury chloride and ionizing radiation. However the concentration of cortisol as assessed by radioimmunoassay increased in both of the groups. Relative expressions of mRNA related to mitochondrion-mediated apoptosis were investigated using semiquantitative reverse transcription polymerase chain reaction on gonad and urinary organs of the experimental groups. While the expression of Bcl-2 mRNA exhibited different patterns depending on the organs or the experimental groups, both of the experimental groups showed a conspicuous expressions of Bax mRNA. In conclusion, the target organ of mercury chloride seems to be a urinary organ and the pattern of damage induced by mercury chloride differs from that by ionizing radiation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.4
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• pp.397-410
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• 2018

When considering the long-term safety assessment of spent-nuclear fuel management, americium is one of the most radio-toxic actinides. Although spectroscopic methods are widely used for the study of actinide chemistry, application of those methods to americium chemistry has been limited. Herein, we purified $^{241}Am$ to obtain a highly pure stock solution required for spectroscopic studies. Quantitative and qualitative analyses of purified $^{241}Am$ were carried out using liquid scintillation counting, and gamma and alpha radiation spectrometry. Highly sensitive absorption spectrometry coupled with a liquid waveguide capillary cell and time-resolved laser fluorescence spectroscopy were employed for the study of Am(III) hydrolysis and oxalate (Ox) complexation. $Am^{3+}$ ions under acidic conditions exhibit maximum absorbance at 503 nm, with a molar absorption coefficient of $424{\pm}8cm^{-1}{\cdot}M^{-1}$. $Am(OH)_3(s)$ colloidal particles formed under near neutral pH conditions were identified by monitoring the absorbance at around 506-507 nm. The formation of ${Am(Ox)_3}^{3-}$ was detected by red-shifts of the absorption and luminescence spectra of 4 and 5 nm, respectively. In addition, considerable enhancements of the luminescence intensities were observed. The luminescence lifetime of ${Am(Ox)_3}^{3-}$ increased from 23 to 56 ns, which indicates that approximately six water molecules are replaced by carboxylate ligands in the inner-sphere of the Am(III). These results suggest that ${Am(Ox)_3}^{3-}$ is formed through the bidentate coordination of the oxalate ligands.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.565-573
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• 2021

Isotherms, kinetics and thermodynamic properties for adsorption of Brilliant Green(BG), Quinoline Yellow(QY) dyes by activated carbon were carried out using variables such as dose of adsorbent, pH, initial concentration, contact time, temperature and competitive. BG showed the highest adsorption rate of 92.4% at pH 11, and QY was adsorbed at 90.9% at pH 3. BG was in good agreement with the Freundlich isothermal model, and QY was well matched with Langmuir model. The separation coefficients of isotherm model indicated that these dyes could be effectively treated by activated carbon. Estimated adsorption energy by Temkin isotherm model indicated that the adsorption of BG and QY by activated carbon is a physical adsorption. The kinetic experimental results showed that the pseudo second order model had a better fit than the pseudo first order model with a smaller in the equilibrium adsorption amount. It was confirmed that surface diffusion was a rate controlling step by the intraparticle diffusion model. The activation energy and enthalpy change of the adsorption process indicated that the adsorption process was a relatively easy endothermic reaction. The entropy change indicated that the disorder of the adsorption system increased as the adsorption of BG and QY dyes to activated carbon proceeded. Gibbs free energy was found that the adsorption reaction became more spontaneous with increasing temperature. As a result of competitive adsorption of the mixed solution, it was found that QY was disturbed by BG and the adsorption reduced.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.221-232
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• 2023

Carbon neutrality requires carbon dioxide reduction technology and alternative green energy sources. Palygorskite is a clay mineral with a ribbon structure and possess a large surface area due to the nanoscale pore size. The clay mineral has been proposed as a potential material to capture carbon dioxide (CO₂) and possibly to store eco-friendly hydrogen gas (H2). We report our preliminary results of grand canonical Monte Carlo (GCMC) simulations that investigated the adsorption isotherms and mechanisms of CO₂ and H₂ into palygorskite nanopores at room temperature. As the chemical potential of gas increased, the adsorbed amount of CO₂ or H₂ within the palygorskite nanopores increased. Compared to CO₂, injection of H₂ into palygorskite required higher energy. The mean squared displacement within palygorskite nanopores was much higher for H₂ than for CO₂, which is consistent with experiments. Our simulations found that CO₂ molecules were arranged in a row in the nanopores, while H₂ molecules showed highly disordered arrangement. This simulation method is promising for finding Earth materials suitable for CO₂ capture and H₂ storage and also expected to contribute to fundamental understanding of fluid-mineral interactions in the geological underground.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.4
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• pp.135-139
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• 2004

The layered organic-inorganic hybrid compounds($C_6H_5CH_2NH_3)_2CuCl_4$ and ($NH_3C_6/H_4C_2H_4_6/H_4NH_3)CuCl_4$ have been directly synthesized. From the X-ray diffraction data and the organic guest size, the orientation of the intercalated organic amine was determined. The inorganic sheets consist of $CuCl_4^{2-}$layers of comer-sharing octahedra copper chloride. The protonated organic amine was intercalated into the $CuCl_4^{2-}$layers with bilayer structure for ($C_6H_5CH_2NH_3)_2CuCl_4$ and monolayer structure for ($NH_3C_6/H_4C_2H_4_6/H_4NH_3)CuCl_4$.

• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.23-32
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• 2012

This study was conducted to monitor microbial species dynamics within the aquifer due to long term operation of geothermal heat pump system. The species were identified by molecular biological methods of 16S rDNA. Groundwater sample was collected from both open (S region) and closed geothermal recovery system (J region) along with the control. J measured and control as well as S measured found Ralstonia pickettii as dominant species at year 2010. In contrast, Rhodoferax ferrireducens was dominantly observed for the control of S. In 2011, Sediminibacterium sp. was universely identified as the dominant species regardless of the monitoring places and type of sample, i.e., measured or control. The difference in the dynamics between the measured and the control was not critically observed, but annual variation was more strikingly found. It reveals that possible environmental changes (e.g. ORP and DO) due to the operation of geothermal heat recovery system in aquifer could be more exceedingly preceded to differentiate annual variation of microbial species rather than positional differences.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.36-42
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• 2020

In order to investigate the effect of the oxidation process on thermal properties of the pitch, the oxidized pitch was prepared by changing the oxidation temperature. Thermal properties of the pitch were analyzed using thermogravimetric analysis (TGA), and it divided into three sections as A (25~100 ℃), B (250~550 ℃) and C (550~800 ℃) by derivative thermogravimetry (DTG) graph behavior. In the A section, the was reduced because the moisture contained in the pitch was removed. In the B section, as the oxidation temperature increased, the thermal stability of the pitch is improved. Because the degree of aromaticity and molecular weight of the pitch increased with increasing oxidation temperature. In contrast, the results of the C section were shown opposite of B section. Because the introduced C-OH, C-O-C, and C=O bonds were decomposed, and the resulting oxygen compounds induced the combustion reaction of the pitch.