• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.66-74
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• 1993

Potassium-Graphite Intercalation Compounds(K-GICs) have been prepared from purified natural graphite by transformed two-bulb method with variations of reaction temperature ($T_g:450^{\circ}C$, $400^{\circ}C$, $350^{\circ}C$, $300^{\circ}C$, $250^{\circ}C$).Prepared K-GICs were identified to stage transition process by X-ray diffraction data. At these results, d values of (00l) diffraction at 1 stage and 2 stage were corresponded to $5.35\AA$ and $8.73\AA$ respectively. The stage stability and energy states of K-GlCs were obtained by UV /VIS Spectrophotometric data. We found that the minimum value of reflectance was 2.67 eV(465nm) at $250^{\circ}C$and it's moved to higher energy than original graphite's. And X-ray diffraction and UV /VIS spectrophotometric datas suggest that K-GICs were formed lower stage and many charge carriers exist between C atoms of graphite. And then, these results also provide informations on the electrical and other physical properities of K-GICs.Especially, according to studied reports, d values differ from them of each author, but accurate values were established through this study.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.15-19
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• 2021

In this study, we studied a facile method for the synthesis of stable and nearly spherical gold nanoparticles using a tyrosine-rich peptide, Tyr-Tyr-Gly-Tyr-Tyr (YYGYY), as both the reducing and capping agent. The peptide coated spherical and polycrystalline gold nanoparticles with diameters from 3 to 15 nm were successfully synthesized by varying the concentration of the peptide and metal precursor under UV irradiation. The nanoparticles were then characterized by transmission electron microscopy (TEM), UV-Vis spectroscopy, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). Furthermore, the catalytic activity of gold nanoparticles was confirmed by the reduction of 4-nitrophenol to 4-aminophenol, in which the catalytic reaction rate constant was 7.3 × 10-3 s-1.

• Analytical Science and Technology
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• v.26 no.1
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• pp.19-26
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• 2013

Gibberllic acid ($GA_3$) is one of gibberellins (GAs) that are a class of plant growth hormones that exert profound and diverse effects on plant growth and development. $GA_3$ is essentially non-UV absorbing and is difficult to assay by UV-detector. For effective extraction of gibberellic acid from fruits by using liquid-liquid extraction, optimized pH and extraction solvent were established. The selective and sensitive derivative of $GA_3$ for HPLC/UV-vis was derivatized using phenacyl bromide, and the experimental factors, including reaction time, reaction temperature and amount of derivatizing reagent and base were investigated for the effective synthesis. The derivatized $GA_3$ with phenacyl bromide was effectively analyzed by HPLC/UV-vis. The structure of derivatized $GA_3$ was confirmed by HPLC/ESI-MS. For apple, LOD and LOQ were 0.008 mg/kg and 0.027 mg/kg, respectively. For pear, LOD and LOQ were 0.003 mg/kg, 0.012 mg/kg, respectively. The established method can be applied to more effective analysis of $GA_3$ from plant and food.

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.131-136
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• 1995

Ultra-thin films of hexyltriphenylphosphonium-TCNQ(1:1) complex were formed on various substrates by Langmuir-Blodgett technique, where hexyltriphenylphosphonium-TCNQ(1:1) complex was synthesized by attaching hexyltriphenylphosphonium group to TCNQ. The reaction product was identified with FT-IR, and UV-Vis absorption spectroscopies. The formation of ultra-thin films of hexyltriphenylphosphonium-TCNQ(1:1) complex was confirmed also by FT-IR, and UV/Vis absorption spectroscopies.

• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.36-41
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• 2002

This study was carried out develope a ultrasonic transducer displacement generator through 26KHz and 38KHz of the frequency phase modulation on the ultrasonic transducer. This system was producted a power output generation such as 100W, 300W, 400W and 600W. Ultrasonic power output had a change of time. We made use of a Thiram hydration and detected it measurement by the ACAO method. It was to decide the result of ultrasonic power supply for time duration and the result of comparison in the 26KHz & 38KHz by UV/VIS spectrophotometer.

• Conservation Science in Museum
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• v.12
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• pp.9-17
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• 2011

This study examined non-destructive UV-Vis spectrophotometry as well as 3-D fluorescence spectrophotometry of textile that made use of red dye such as Sappan wood, madder, Safflower, Gromwell. The authors produced two textile specimen that were dyed by not only two kinds of textile (cotton and silk) but also three kinds of mordanting (no-mordanting, alumen and iron), and they investigated effects of each dye material upon investigation results. At analysis with UV-Vis spectrophotometry of dyed textile specimen, dyeing made by sappan wood, madder and gromwell had significant difference depending upon mardant regardless of kinds of textile, and safflower had no significant difference depending upon textile and mordant. At analysis with 3D-fluorescence spectrophotometry, specimen dyed with sappan wood had difference with mordants, and with madder, there were difference with textiles, and safflower had inherent fluorescence spectrum regardless of textiles and mordants, while gromwell had no fluorescence spectrum.

• Analytical Science and Technology
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• v.15 no.1
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• pp.72-79
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• 2002

Di-(2-ethylhexyl)phthalate (DEHP) may be released from plasticized poly(vinyl chloride) (PVC) articles. In the cases of various methods for the quantitative analysis of migrating DEHP, there are much differences in migrating quantity according to the experimental methods. It is therefore important to make the comparison and analysis between these two results. A study of DEHP migration from blood and infusion bags has been carried out in different methods to evaluate the amount of DEHP migration using gas chromatograph and UV-vis spectrophotometry. Five PVC bags were cut into plane sheets in size of $40{\times}10{\times}0.4mm$, then were immersed in extraction solvent for an hour to release DEHP. It was determined by a gas chromatograph that $23.2{\sim}70.9{\mu}g/mL$ of DEHP was extracted. While extraction solvent was injected into PVC bags which were then placed for an hour to leach DEHP out. It was checked by a UV-vis spectrophotometer that the concentration of DEHP in extraction solvent was $24.8{\sim}41.3{\mu}g/mL$. Two results show different values according to the extraction conditions and experimental methods and the gas chromatographic results were converted into UV-vis spectroscopic results on condition that DEHP would be extracted equally per unit time and unit contact area. It was concluded that DEHP migrating amounts are approximately equal in two analytical methods.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.437-448
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• 1997

The substitution of vanadium atoms into the zeolite framework structure could be applied to the large pore zeolites by means of modified treatments as well as direct hydrothermal synthesis. The incorporation of V into the zeolite framework was demonstrated by instrumental analysis techniques. The result of X-ray diffraction analysis showed that the unit cell parameters increased after incorporation of vanadium into the zeolitic lattice, indicating that the replacement of Si by the larger V atoms could cause a slight expansion in the unit cell. In addition, the results of FTIR, Uv-Vis and Si-MAS-NMR spectra strongly support the incorporation of V into the zeolite framework. Acid leaching of aluminum in zeolites can provide a vacant position in the lattice for the insertion of vansdium by secondary hydrothermal treatment.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.730-734
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• 1993

The electrochemical reduction behavior or Biliverdin (BV) in N,N-dimethylformamide solvent was studied by DC polarography, cyclic voltammetry and the controlled potential coulometry. The reduced product was indentified by UV-Vis spectroscopy. In DC polarogram, two reduction waves of BV were founded. The half wave potentials of two reduction waves were -0.71 and -0.91 V vs. Ag/Ag$^+$ respectively. The current type of the 1st reduction wave was diffusion-controlled and the 2nd was diffusion current containing a little kinetic current. The 1st electrochemical reduction process was irreversible and BV reduced to Bilirubin.

• Polymer(Korea)
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• v.29 no.3
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• pp.308-313
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• 2005

The effects of molecular environments on photoisomerization of an azobenzene group were investigated using In-situ UV/Vis spectroscopy and optical anisotropy measurement technique. The reversible and repeatable photoisomeritation reactions of azobenzene were observed by irradiating the film containing 4-hydroxyazobenzene and by measuring absorption intensities of the characteristic bands of trans and cis isomers simultaneously. When the self-assembled monolayer with azobenzene groups was used as an alignment layer for a liquid crystal cell, the homeotropic alignment was induced due to their compact packing structures of azobenfene groups along the vertical direction of the substrate. By irradiating UV light on this cell, the trans-azobenzene groups change to cis-isomers through the photoisonlerieation and then resulting in the planar alignment of liquid crystal molecules.