• Journal of the Korean Chemical Society
• /
• v.30 no.5
• /
• pp.488-492
• /
• 1986

The $Ca^{++}$ and $Mg^{++}$ released during Ca, Mg-Na exchange on Kampo 78 montmorillonite which was treated with various concentrations of NaCl solution, were measured with EDTA titration metbod in the leaching solutions. Lanthanide montmorillonite was prepared with various neutral lanthanide ions from sodium montmorillonite in which the exchangeable ions are displaced from the exchanger, such as the displacement of $Na^+$ by $Ln^{3+}$ ions, Cation exchange capacity (CEC) is determined on remaining lanthanides in the leaching solutions with E. D. T. A titration method. As a results of this study, there were no difference of C. E. C in series of lanthanide contraction, but C. E. C depends on charge density of montmorillonite. When we conformed the structure of Ln-montmorillonite by X-ray diffraction. It was found that there was much difference of pattern between Na-montmorillonite and Ln-montmorillonite.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.8
• /
• pp.1207-1210
• /
• 2003

The effect of solvent structure on the slope in the plot of ln K vs. solute carbon number was examined. It was found that the free energy of methylene group transfer from the gas phase into a solvent was always negative and that the absolute magnitude of interaction free energy between the methylene group and the solvent was always larger than the absolute magnitude of cavity formation free energy of the methylene group in the solvent. Thus, the slope in the plot of ln K vs. solute carbon number was always positive and its value decreases with increase of solvent polarity since the cavity formation energy of the CH₂ unit increases with increase of solvent polarity while the dispersive interaction energy of the CH₂ unit is virtually invariant. We also examined the effect of sequential addition of CH₂ unit to a solvent molecule upon ln K for three homologous series of solvents: n-alkanes, n-alcohols, and n-nitriles. Characteristic trends in the plots of ln K vs. solvent carbon number were observed for individual solvent groups. A decrease of ln K with solvent carbon number was observed for n-alkanes. An abrupt increase in ln K followed by levelling off was observed for n-alcohols while a final slight decrease in ln K after an abrupt increase followed by rapid levelling off was noted for n-nitriles. All of theses phenomena were found related to variation in cavity formation energy. It was clearly shown that a structural change of a polar solvent by sequential addition of CH₂ units causes an abrupt polarity decrease initially, then gradual levelling off, and finally, conversion to a virtually nonpolar solvent if enough CH₂ units are added.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.5
• /
• pp.3183-3186
• /
• 2013

Purpose: The 7th edition of the American Joint Committee on Cancer Staging Manual for esophageal cancer (EC) categorizes N stage according to the number of metastatic lymph nodes (LNs), irrespective of the site. The aim of this study was to determine the prognostic value of subcarinal LN metastasis in patients undergoing esophagectomy for esophageal squamous cell carcinoma (ESCC). Methods: A retrospective analysis of 507 consecutive patients with ESCC was conducted. Potential clinicopathological factors that could influence subcarinal LN metastasis were statistically analyzed. Univariate and multivariate analyses were also performed to evaluate the prognostic parameters for survival. Results: The frequency of subcarinal LN metastasis was 22.9% (116/507). Logistic regression analysis showed that tumor length (>3cm vs ${\leq}3cm$; P=0.027), tumor location (lower vs upper/middle; P=0.009), vessel involvement (Yes vs No; P=0.001) and depth of invasion (T3-4a vs T1-2; P=0.012) were associated with 2.085-, 1.810-, 2.535- and 2.201- fold increases, respectively, for risk of subcarinal LN metastasis. Multivariate analyses showed that differentiation (poor vs well/moderate; P=0.001), subcarinal LN metastasis (yes vs no; P=0.033), depth of invasion (T3-4a vs T1-2; P=0.014) and N staging (N1-3 vs N0; P=0.001) were independent prognostic factors. In addition, patients with subcarinal LN metastasis had a significantly lower 5-year cumulative survival rate than those without (26.7% vs 60.9%; P<0.001). Conclusions: Subcarinal LN metastasis is a predictive factor for long-term survival in patients with ESCC.

• Journal of the Korean Chemical Society
• /
• v.33 no.5
• /
• pp.496-503
• /
• 1989

The chemical behavior of trivalent lanthanide (Pr(III) and Yb(III)) and 2, 2, 6, 6-tetramethyl-3, 5-heptanedione(dipivaloylmethane) complexes was investigated by the use of direct current, differential pulse polarography and cyclic voltammetry. In this study, it was founded that the reduction of trivalent lanthanide complexes was observed by one electron transfer process at Epc = -0. 13 V and -0.80 V of Pr(III), and -0.02 V of Yb(III) vs. Ag-AgCl electrode. Also, it was founded that the treatment of DP and CV to the case of a first-order chemical equilibrium reaction preceding a reversible and irreversible one electron transfer reaction, (a >0. 5) the socalled ErCr electrode process. The equilibrium constant (lnK) obtained, of various solvents, these constant were founded to be increases with decreasing dielectric constant of the solvents. Plots of lnK for these reaction against ln(l/D) for the solvents was fairly straight lines, and the behavior of the heavier lanthanides was decreased equilibrium constant with increasing atomic number.

• Journal of the Korean Solar Energy Society
• /
• v.38 no.5
• /
• pp.11-25
• /
• 2018

The Ln-least method is commonly used to estimate the Weibull parameters from the observed wind speed data. In previous studies, the bin method has been used to calculate the cumulative frequency distribution for the Ln-least method. The purpose of this study is to obtain better performance in the Ln-least method by applying probability plotting position(PPP) instead of the bin method. Two types of the wind speed data were used for the analysis. One was the observed wind speed data taken from three sites with different topographical conditions. The other was the virtual wind speed data which were statistically generated by a random variable with known Weibull parameters. Also, ten types of PPP formulas were applied which were Hazen, California, Weibull, Blom, Gringorten, Chegodayev, Cunnane, Tukey, Beard and Median. In addition, in order to suggest the most suitable PPP formula for estimating Weibull parameters, two accuracy tests, the root mean square error(RMSE) and $R^2$ tests, were performed. As a result, all of PPPs showed better performances than the bin method and the best PPP was the Hazen formula. In the RMSE test, compared with the bin method, the Hazen formula increased estimation performance by 38.2% for the observed wind speed data and by 37.0% for the virtual wind speed data. For the $R^2$ test, the Hazen formula improved the performance by 1.2% and 2.7%, respectively. In addition, the performance of the PPP depended on the frequency of low wind speeds and wind speed variability.

• Advances in nano research
• /
• v.16 no.1
• /
• pp.41-52
• /
• 2024

In this study, rare-earth orthoferrites LnFeO₃ were synthesized using a facile hydrothermal reaction and their visible-light-induced photo-Fenton degradation of organics was optimized through Ln variation (Ln = La, Pr, or Gd). The morphological, structural, and chemical characteristics of as-prepared samples were examined in detail by using different methods, including XRD, SEM, TEM, XPS, etc. On the other side, under visible light illumination, the photo-Fenton-like catalytic activities of LnFeO₃ were assessed in terms of the removal of selected organic models, i.e., pharmaceuticals (ketoprofen and tetracycline) and dyes (rhodamine B and methyl orange). As compared with PrFeO₃ or GdFeO₃, the sample of LaFeO₃ displayed more structural distortion, larger specific surface area, and narrower band gap, resulting in its higher photo-Fenton-like catalytic activity toward the degradation of organics. In organic-containing solution, in which the initial solution pH = 5, catalyst dosage = 1 g/L and H₂O₂ concentration = 10 mM, 98.2% of rhodamine B, 31.1% of methyl orange, 67.7% of ketoprofen, or 96.4% of tetracycline was removed after 90-min exposure to simulated visible light. Our findings revealed that variation of Ln site on rare-earth orthoferrites was an effective strategy for optimizing their organic removal via visible-light-induced photo-Fenton reaction.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2001.05a
• /
• pp.347.1-347
• /
• 2001

• Proceedings of the Korean Nuclear Society Conference
• /
• 2001.10a
• /
• pp.262.2-262
• /
• 2001

• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.10a
• /
• pp.226-226
• /
• 2002

• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.10a
• /
• pp.281.2-281
• /
• 2002