• Journal of the Mineralogical Society of Korea
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• v.22 no.1
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• pp.23-34
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• 2009

The adsorption of iodide on untreated bentonite and bentonites modified with organic cation (i.e., hexadecylpyridinium chloride monohydrate ($HDP^+$)) was investigated, and the organobentonites were characterized using uptake measurements, ${\mu}$-XRD, and electrophoretic mobilities measurement. Uptake measurements indicate that bentonite has a high affinity for $HDP^+$. Our ${\mu}$-XRD study indicates that organobentonites significantly expanded in basal spacing and organic cations were substantially intercalated into the interlayer spaces of bentonite. The electrophoretic mobility indicates that organobentonite tht is modified with organic cations in excess of the CEC of bentonite is completely different from untreated bentonite in the surface charge distribution. We found significant differences in adsorption capacities of iodide depending on the bentonite properties as follows: iodide adsorption capacities were 439 mmol/kg for the bentonite modified with $HDP^+$ at an equivalent amount corresponding to 200% of the CEC of bentonite whereas no adsorption of iodide was observed for the untreated bentonite. The molecular environments of iodine adsorbed on organobentonites were further studied using I K-edge and $L_{III}$-edge x-ray absorption spectroscopy (XAS). The X-ray absorption near-edge structure (XANES) of iodine spectra from organobentonites was similar to that of KI reference solution. Linear combination fitting of EXAFS data suggests the fraction of iodine reacted with the organic compound increased with increasing loading of the organic compound on organobentonites. In this study, we observed significant differences in the adsorption environments of iodide depending on the modified property of bentonite and suggest that an organobentonite has potential as reactive barrier material around a nuclear waste repository containing anionic radioactive iodide.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.70-78
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• 2009

Remote sensing technique in agriculture can be used to identify chlorophyll content, biomass, and yield caused from N stress level. This study was conducted to evaluate biomass, N stress levels, and yield of tobacco (Nicotiana tabacum L.) under sand culture in a plastic film house using ground-based remote sensors. Nitrogen rates applied were 40, 60, 80, 100, 120, and 140 percent of N concentration in the Hoagland's nutrient solution. Sensor readings for reflectance indices were taken at 30, 35, 40, 45, 50 and 60 days after transplanting(DAT). Reflectance indices measured at 40th DAT were highly correlated with dry weight(DW) of tobacco leaves and N uptake by leaves. Especially, green normalized difference vegetation index(gNDVI) from spectroradiometer and aNDVI from Crop Circle passive sensor were able to explain 85% and 84% of DW variability and 85% and 92% of N uptake variability, respectively. All the reflectance indices measured at each sampling date during the growing season were significantly correlated with tobacco yield. Especially the gNDVI derived from spectroradiometer readings at the 40th DAT explained 72% of yield variability. N rates of tobacco were distinguished by sufficiency index calculated using the ratio of reflectance indices of stress to optimum plot of N treatment. Consequently results indicate that the reflectance indices by ground-based remote sensor can be used to predict tobacco yield and recommend the optimum application rate of N fertilizer for top dressing of tobacco.

• Analytical Science and Technology
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• v.7 no.1
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• pp.79-89
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• 1994

Interactions between the acetonitrile and other organic molecules such as furan, pyrrole, pyrrolidine, thiophene, tetrahydrothiophene and acetaldehyde was studied with the infrared absorption spectroscopy under matrix isolation conditions. Xe was used as a major matrix material. Acetonitrile showed strong interactions with pyrrole and thiophene, and little interactions with pyrrolidine and acetaldehyde.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.477-482
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• 1994

Structural changes of hydrous titania by heat-treatment was investigated with XRD, TEM, FT-IR, Rarnan spectral analyses. The hydrous titania was derived from a mixed solution of titanium tetrachloride and hydrogen peroxide at $30^{\circ}C$ and pH of 9.0. The precipitate was an anatase form of titania with less-developed crystalline structure. With increasing annealing temperature ranglng up to $700^{\circ}C$, the crystallinity of anatase increased, and the particles were grown at high temperature. The rutile form of titania was developed from the anatase at $700^{\circ}C$.

• The Journal of Information Technology
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• v.7 no.2
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• pp.1-5
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• 2004

The symmetric 9-phenyl-5,5'-diphenyl-3,3'-bis-(3-sulfopropyl)-benzoxazolo carbocyanine triethyl ammonium salt is of industrial importance as green-sensitizing dye in the spectral sensitization of emulsion microcrystals in negative film and positive paper-making. The stability on the solvents of benzoxazolo carbocyanine dye was measured by UV-Vis spectrophotometer, and then dye was stabilized in various solvents. The maximum absorption peak range in various solvents was 507nm~515nm. It was identified that the solvents can be used to photographic emulsion.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.201-205
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• 2010

X-ray magnetic circular dichroism (XMCD) has been used as an important tool of magnetics due to its unique abilities to measure element-specific magnetic properties and to separate the orbital and the spin magnetic moments. These abilities allow researchers to access the microscopic origin of the magnetic properties of transition metal and rare earth compounds. In this report, I explain the principle of XMCD and the experimental set-up. Recent a few research examples using XMCD will be also introduced.

• Korean Journal of Crystallography
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• v.7 no.2
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• pp.133-146
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• 1996

Morphology and infrared absorbing characteristics of Pt-black prepared by electroplating have been investigated with XRD, SEM, and IR spectrophotometer. The Pt later was coated on Au-coated alumina/glass substrates for 1-5 min at pH 1.0-1.5, where a solution of platinum chloride and lead acetate was used as the electrolyte. At the electrical current density of 20-50 mA/㎠, the Pt-black showed a dendritic growth which was characterized by a "tree" shape. Absorptivity of above 90% at IR radiation of 10 m was observed for the Pt absorbing layer with an area density of ≥1.3mg/㎠.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.198-202
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• 1998

We have studied $Al_xFe_{3-x}O_4$ produced by direct composition method using X-ray diffraction and Mssbauer spectroscopy. The cation distribution for $Al_xFe_{3-x}O_4$ was determined by the ratio of sub-spectra absorption area. The charge state of Fe atoms in octahedral site(B-site) is $Fe^{2.5+}$ based on electron hopping, $Fe^{2+}$ ↔ $(Fe^{3+},Al^{3+})$ without dependency of substituted Al amounts.

• Analytical Science and Technology
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• v.11 no.1
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• pp.20-28
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• 1998

Fluorimetric and absorption spectroscopic studies were performed to elucidate the photocurrent decay with time in the conversion process of solar energy into electrical energy using a photoelectrochemical cell containing rose bengal as a sensitizer, and allylthiourea as a supersensitizer. Spectra of dye solution before and after irradiation revealed a new photocatalytic dimerization reaction between sensitizer and supersensitizer. It was also found that the geometrical arrangement of the transition dipoles is oblique in the dimer of dye molecules.

• Applied Chemistry
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• v.16 no.1
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• pp.25-28
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• 2012

A determination method of cyanide ion (CN^-) using nickel complexation reaction by continuous monitoring system. The mechanical parameters and chemical conditions of the complexation reaction were investigated prior to application of continuous monitoring system for determination of cyanide. On the optimized conditions, the calibration curve was linear over the range from 5.0×10^-6 to 1.0×10^-4 M. In this range, 2.40% of the reproducibility (RSD, n=3) was obtained. The limit of detection (3σ/s) was calculated to be 1.8×10^-6 M.