• Journal of the Mineralogical Society of Korea
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• v.15 no.3
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• pp.195-204
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• 2002

Mineralogy and the exposed surface area are two of the most important factors controlling dissolution and weathering rates of soils. The mixture of inorganic and organic materials of various size distributions and structures that constitute soils makes the calculation of weathering rates difficult. The surface area of soil minerals plays an important role in most of programs for calculating the weathering rates and critical loads. The Brunauer-Emmett-Teller (BET) measurement is recommended for the measurement of specific surface area. However, BET values measured without organic matter removal are in fact those far all the N2-adsorbed surface areas, including the surfaces covered and aggregated with organisms. Surfaces occupied by organisms are assumed to be more reactive to weathering by organic activities. Therefore, the BET surface area difference before and after organic removal depicts the area occupied by organisms. The present study shows that the BET values after organic matter removal using $H_2$O$_2$ are larger than those without removal by 1.68~4.87 $m^2$/g. This implies that BET measurement without organic removal excludes the reactive area occupied by organisms and that the area occupied by organisms in soils is much larger than expected. It is suggested that specific surface area measurement for calculating weathering rates of mineral soils should be made before and after organic matter removal. The results of a column experiment are presented to demonstrate the potential retarding influence that this organic matter may have on mineral dissolution and weathering.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.3
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• pp.125-129
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• 2009

The preparation and characterization of niobium carbide crystallites were investigated in this study, and in particular, the effect of preparation conditions were studied on the synthesis of niobium carbides crystallites. For this purpose, various characterization techniques including x-ray diffraction, BET surface area, and oxygen uptake measurements were employed to characterize the synthesized niobium carbide crystallites. The niobium carbide crystallites were prepared using niobium oxide and methane gas or methane-hydrogen mixture. Using x-ray diffraction a lattice parameter of $4.45{\AA}$ and a crystallite size ranging from $52{\AA}$ to $580{\AA}$ was found. BET surface areas ranged from $3.2\;m^2/g$ to $16.6\;m^2/g$ and oxygen uptake values varied from $0.5{\mu}mol/g$ to $6.1{\mu}mol/g$. It was observed that niobium carbide crystallites were active for ammonia decomposition reaction. While the BET surface area increased with increasing the oxygen uptake, the conversion of ammonia decomposition reaction decreased. These results indicated that the ammonia decomposition over these materials was considered to be structure-sensitive.

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.318-324
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• 2018

In this study, PAN (polyacrylonitrile) based activated carbon fibers were prepared by water vapor activation method which is a physical activation method. Activation was performed with temperature and time as parameters. When the activation temperature reached 700, 750 and $800^{\circ}C$, the activation was carried out under the condition of a water vapor flow rate of 200 ml/min. In order to analyze the pore structure of activated carbon fibers, the specific surface area ($S_{BET}$) was measured by the adsorption/desorption isotherm of nitrogen gas and AFM analysis was performed for the surface analysis. Tensile tests were also conducted to investigate the effect of the pore structure on mechanical properties of fibers. As a result, the $S_{BET}$ of fibers after the activation showed a value of $448{\sim}902m^2/g$, the tensile strength decreased 58.16~84.92% and the tensile modulus decreased to 69.81~83.89%.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.456-459
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• 2011

Among the various activated carbons available in the market, an optimum mixing method of two kind activated carbons with different adsorbability was investigated in this study. The representative adsorption behaviors of the activated carbon are the adsorption isotherm plots obtained by the BET-Analysis which suggests also basic information of adsorption filter design. So we have tested three cases with certifications, the one was the extreme case of coal cokes based activated carbon with highest BET-model and coconut-shell based activated carbon with the lowest Langmuir-model, the other middle and cross case were applied this method to two kinds of activated carbons with higher and lower specific surface areas which are not available but supplied as research samples by an authority of an Korean Research Institute.

• Analytical Science and Technology
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• v.13 no.3
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• pp.332-337
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• 2000

The study on the nitrogen adsorption, surface properties and water adsorption capacity of the carbonaceous desiccants derived from phenolic resin was carried out. In the nitrogen adsorption study on the carbonaceous desiccants, Type II isotherm for each sample was obtained. Furthermore, the adsorbed volume decrease with water washing of the desiccant. The $S_{BET}$ of the carbonaceous desiccants was $648.7m^2/g$ before washing and $189.3m^2/g$ after washing, respectively. The morphology of needlelike formation before washing and spherical particle after washing with water were observed from SEM micrographs. Finally, from the water adsorption effects, the percentage of the water loading capacity was 25-63%, and the capacity was good at relatively low humidity.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3046-3054
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• 2013

Synthesis of Carbon Nanotube bundles has been achieved by simple and economical solvothermal procedure at very low temperature of $180^{\circ}C$. The product yield obtained was about 70-75%. The optimization of reaction conditions for an efficient synthesis of CNTs has been presented. The CNTs are obtained by reduction of hexachlorobenzene in the presence of Na/Ni in cyclohexane. The X-ray diffraction, Fourier transform infrared and Raman spectral studies have inferred us the graphene structure of the products. The CNTs formed as the bundles were viewed on scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. These are the multiwalled CNTs with outer diameter of 5-10 nm, the inner diameter 2-4 nm and cross sectional diameter up to 5 nm. Brunauer-Emmett-Teller (BET) based $N_2$ gas adsorption studies have been made to obtain BET surface area and $H_2$ storage capacity. Effect of the experimental variables such as reaction temperature, amount of catalyst and the amount of carbon source were investigated. It is found that they affect significantly on the product nature and yield.

• Korean Journal of Medicinal Crop Science
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• v.17 no.4
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• pp.273-279
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• 2009

GATA-binding protein-3 (GATA-3) and T-box expressed in T-cells (T-bet) are now considered as master transcription factors involving Th cell differentiation, but the roles of these factors are still uncertain in vivo. This study was conducted to investigate the expression of these transcription factors in the liver damage induced by carbon tetrachloride ($CCl_4$) in rats. In this study, liver damage were induced with Scutellaria baicalensis Georgi water extracts (SBW) and followed for 4 weeks. The expression of GATA-3 and T-bet protein in liver damage induced by $CCl_4$ and the serum levels of immunoglobulin A (IgA), IgE were studied after 4 weeks of treatment. We found that effect of SBW on IFN-$\gamma$, STAT1, pSTAT1 and T-bet was decreased in vivo. Several genes were demonstrated to be IL-4 inducible prior to the discovery of STAT6. $CCl_4$+SBW group was significantly lower than $CCl_4$ group in IL-4, STAT6, pSTAT6 and GATA-3. Our data indicate that cytokine protein production were increased in $CCl_4$ group and $CCl_4$+SBW group. From these results, water extracts obtained from Scutellaria baicalensis Georgi may have an immunoregulatory effect in the liver induced by $CCl_4$ of rats.

• Clean Technology
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• v.15 no.1
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• pp.31-37
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• 2009

This study deals with the production process of activated carbons from the sewage sludge char by chemical activation reaction. KOH and NaOH were used as activating agents, which react well with carbon. From the experiments, it was found that activated carbons made with KOH treatment had better physicochemical properties in terms of iodine number and BET value than those made with NaOH treatment. It was also found that the optimal deposition ratio of an activating agent to the sewage sludge char was 75 wt% of KOH and 50 wt% of NaOH. Activated carbons were washed out by distilled water after neutralization with 5 M hydrochloric acid solution. The activated carbons that were produced from a sewage sludge char at this optimal conditions have BET surface areas of approximately $600m^2/g$.

• The Journal of Internal Korean Medicine
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• v.27 no.1
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• pp.40-54
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• 2006

Objective: This study aimed to identify the different effects of GMCSBHT water-extract and ethanol-extract on Th1/Th2 differentiation by monitoring Th1/Th2 specific cytokine secretion patterns and the transcriptional activities of T-bet, GATA-3, c-maf, $INF{\gamma}$ and IL-4. Materials and Methods: Spleen cells from eight week-old BALB/c mice were cultured in GMCSBHT extracts containing medium without activation for 24 hours and with activation for 48 hours. CD4+ T cells were isolated and mRNA expression levels of $INF{\gamma}$, IL-4, T-bet, GATA-3, c-maf by RT-PCR and secretion cytokines levels of $IFN{\gamma}$, IL-4 by ELISA were analyzed. Results: GMCSBHT extracts didn't have mitogenic effects on the unstimulated CD4+ T cells. In Th1 skewed condition, GMCSBAHT water extract had no significant effects on mRNA expression levels of $IFN{\gamma}$, T-bet and c-maf, but inhibited mRNA expression levels of IL-4, GATA-3. It showed significantly increased secretion cytokine levels of $IFN{\gamma}$, but had no significant effect on secretion cytokine levels of IL-4. In Th2 skewed condition, GMCSBHT ethanol extract inhibited mRNA expression levels of $INF{\gamma}$, IL-4, GATA-3 and c-maf significantly, but had no significant effects on mRNA expression levels of T-bet. It had no significant effects on secretion cytokine levels of $INF{\gamma}$, but showed remarkable inhibitory effects on secretion cytokine levels of IL-4. Conclusion: Results suggest that on Th1/Th2 deviation, GMCSBHT water extract has both amplifying effects on Th1 differentiation and inhibitory effects on Th2, but GMCSBHT ethanol extract has stronger inhibitory effects on Th2 differentiation than on Th1.

• Journal of Animal Science and Technology
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• v.48 no.6
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• pp.777-784
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• 2006

This study was designed to investigate between the semen characteristics and sperm chromatin structure in boar with different farrowing rates and relationship between fertility by AI and results of sperm chromatin structure assay (SCSA). The CASA (computer-aided sperm analysis) and SCSA were performed with liquid semen in boars. The all SCSA parameters based on the farrowing rates by AI were significantly differ (P<0.05). The significant negative correlations (P<0.05) were observed between all SCSA parameters and farrowing rate obtained by AI in the field. In conclusion, these results suggest that the sperm parameters evaluated in these studies may be useful indicators to predict the fertility by AI.