• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.720-726
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• 1992

Multivariate analysis such as factor analysis was applied to interpret multivariate data, which were obtained from the overlapped X-ray fluorescence spectra. X-ray fluorescence spectra of 11 reference samples were obtained by the wavelength dispersive spectrometer at a specified range of angle such as $33.50∼34.50^{\circ}$. The data matrix was made from the spectra of 8 samples. The results of abstract factor analysis gave three factors. By the target testing with 8 elements contained in the reference samples, the three factors were found to be Pb, As and Cu. The concentration of these elements in the test samples was determined by target transformation factor analysis regardless overlapping individual peaks.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.365-372
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• 2018

Wounds that heal with excessive scar formation result in poor functional and aesthetic outcomes. To address this, in our study, visible light cured glycol chitosan (GCH) hydrogels containing endothelial growth factor (EGF) and basic fibroblast growth factor (bFGF) were prepared (GCH-EGF, GCH-FGF and GCH-EGF/FGF) and evaluated their efficacies on the improvement of wound healing in vivo. In vitro release test showed that the growth factors were released in a sustained manner along with initial burst for 24 h. In vitro cell proliferation assay of L-929 mouse fibroblast cell line resulted in the superior ability of GCH-EGF/FGF on the rate. In vivo results demonstrated that the growth factor loaded GCHs further enhanced wound healing compared with GCH. In particular, GCH-EGF/EFG showed the most remarkable wound healing effect among the samples.

• Analytical Science and Technology
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• v.7 no.2
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• pp.201-204
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• 1994

Cation exchange column chromatography of lithium was carried out to investigate the lithium isotope separation in aqueous ion exchange system. A Pyrex glass column of $50cm{\times}6mm$ inner radius with a water jacket was used as the separation column in experiment. Upon column chromatography using hydrochloric and succinic acid mixtures as an elunent, single separation factor, ${\alpha}$, 1.0068 was obtained. From the experiment, it was found that $^6Li$ was enriched in the resin phase and $^7Li$ in the solution phase.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.465-470
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• 2010

Using interesting video clips corresponding to lesson subjects for students who favour visual representation is one of the good methods to enhance students' preference for science class. There are many moving picture web sites to get video clips easily via internet and 'YouTube' is very popular and one of the largest reservoir. In this study, every student in the 'Chemistry I' class, which is a class for 11th grade, was requested to search a video clip corresponding to lesson subjects and to make a presentation in the class. After 1st semester, students' response about the class using YouTube was examined by survey. As a result, students preferred and were interested in the class using YouTube than class centered on textbook. And students preferred YouTube clips showing unusual experiments that were related with contents of subject. In addition, experiments and watching their real phenomena were an interesting factor and helpful factor of learning chemistry in YouTube video clips, respectively. However, translation of English used in the video clips seemed to be a difficult part for students.

• Journal of Applied Biological Chemistry
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• v.63 no.3
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• pp.243-248
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• 2020

The long-chained perfluoroalkyl acids (PFAAs), perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are a potential exposure risk in the environment, specifically for humans due to high levels of bioaccumulation, persistence, and toxicity. In the current study, the plant uptake factors (PUFs) of spinach and Welsh onion were investigated on the three different concentration levels of PFOA and PFOS in soil. Spinach and Welsh onion were divided into three residue groups, a control group and two levels of PFOA and PFOS. The PFAAs spiked soils were aged for six months and the extractable residue of PFOS in the aged soil was reduced to 30-59% of the initial spiked concentrations for PFOS, while PFOA showed almost the same initial spiked concentrations. The PUFs for PFOA and PFOS were 0.111-2.821 and 0.047-3.175 for spinach, and 0.203-0.738 and 0.035-0.181 for Welsh onion, respectively. The highest PUF values in both vegetable were displayed when the residual concentration of PFAAs were part-per-billion (ppb) or sub-ppb in soil.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1323-1328
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• 2014

Molecular structures of the various conformational stereoisomers of 2,8,14,20-cyanophenyl pyrogallol[4]arenes 1 were optimized using the mPW1PW91 (hybrid Hartree-Fock density functional) calculation method. The total electronic and Gibbs free energies and the normal vibrational frequencies of the different structures from three major conformations (CHAIR, TABLE, and 1,2-Alternate) of the four stereoisomers [1(rccc), 1(rcct), 1(rctt), and 1(rtct)] were analyzed. The mPW1PW91/6-31G(d,p) calculations suggested that $1(rcct)_{1,2-A}$, 1(rctt)CHAIR, and $1(rtct)_{CHAIR}$ were the more stable conformations of the respective stereoisomers. Hydrogen bonding is the primary factor for the relative stabilities of the various conformational isomers, and maximizing the ${\pi}-{\pi}$ interaction between the cyanophenyl rings is the secondary factor. The calculated IR spectra of the more stable conformers [$1(rctt)_{CHAIR}$, $1(rcct)_{1,2-A}$, $1(rtct)_{CHAIR}$] were compared with the experimental IR spectrum of $1(rtct)_{CHAIR}$.

• Journal of the Korean Chemical Society
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• v.30 no.3
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• pp.312-319
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• 1986

Dodecyltrimethylammonium bromide (DTAB) was examined as a counter-ion in the investigation of capacity factor and separation of aromatic carboxylic acids on alkyl-modified silica (ODS) column as a stationary phase by ion-pair chromatography on reversed-phase system. The capacity factor of samples was influenced by the several factors such as a concentration of counter-ion as well as kinds and concentration of electrolyte, concentration of methanol in mobile phase and kinds and position of functional group in sample molecule. Some mixtures of samples were able to be separated under optimum condition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.450-452
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• 2004

Using factor analysis and bivariate comparisons of major components in ground water, three geochemical processes were identified as controlling factors of ground water chemistry; 1) natural mineralization by water rock interactions, 2) effect of seawater which includes salinization by seawater near seashores and deposition of sea salt, and 3) nitrate contamination by N fertilization. Contribution of rainfall was also estimated from the measured composition of wet deposition. The geochemical processes were separated using total alkalinity as an indicator for natural mineralization, Cl for effect of seawater, and nitrate for N fertilization. Relatively high correlation of major components with nitrate suggests that nitrification of nitrogenous fertilizers significantly affects ground water chemistry. Total cations derived from nitrate sources have good linearity for nitrate in equivalent basis with a slope of 1.8, which is a mean of proton production coefficients in nitrification of two major compounds in nitrogenous fertilizers, ammonium and urea. Contribution of nitrate sources to base cations, Cl, and SO$_4$ in ground water was determined considering maximum contribution of natural mineralization to estimate a threshold of the effect of N fertilization for ground water chemistry, which shows W fertilization has a greatest effect than any other processes in ground water with nitrate concentration greater than 50 mg/L for Ca, Mg, Na and with concentration greater than 30 mg/L for Cl and SO$_4$.

• Applied Biological Chemistry
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• v.18 no.2
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• pp.56-60
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• 1975

A rapid method for the measurement of the absolute activity of carbon-14 in cotyledons and root of etiolated pea seedlings has been developed. Fresh tissue was frozen in liquid air, ground and suspended in gel phosphor and subjected to measurement for its radioactivity by liquid scintillation counter. Apparent activity of the suspended tissue sample calculated by counting efficiency value obtained by internal standardisation, was found to be related to absolute activity of the tissue, determined by flask combustion technique, by a constant factor. Once this factor is determined experimentally, analysis of C-14 lebelled tissue involves only fairly simple suspension counting by liquid scintillation counter. Present method appears to be applicable to other tissues tagged with C-14.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.405-408
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• 2009

In this work multiwalled carbon nanotube (MWCNT)/fibrin hybrid structures were synthesized via the transglutaminase- catalyzed polymerization of fibrinogen (FBG). Specifically, FBG was tethered onto oxidized MWCNTs by amide coupling, and the in situ polymerization of FBG to fibrin was performed by plasma transglutaminase (Factor XIIIa) in the presence of thrombin. The attached FBG was found to be biologically active and was polymerized to fibrin by thrombin and Factor XIIIa. MWCNT-FBG and MWCNT-Fibrin structures were characterized by FT-IR spectroscopy, transmission electron microscopy, and energy-dispersive X-ray (EDX) spectroscopy.