• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2021-2026
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• 2011

AgNPs (silver nanoparticles) has been widely used for the commercial products, which have antimicrobial agent, medical devices, food industry and cosmetics. Despite, AgNPs have been reported as toxic to the mammalian cell, lung, liver, brain and other organs and many researchers have investigated the toxicity of AgNPs. In this study, we investigated toxicity of the AgNPs to the liver cell using metabolomics based on HRMAS NMR (High Resolution Magic Angle Spinning Nuclear Magnetic Resonance) technics, which could apply to the intact tissues or cells, to avoid the sample destruction. Target profiling and multivariative statistical analysis were performed to analyze the 1D $^1H$ spectrum. The results show that the concentrations of many metabolites were affected by the AgNPs in the liver cell. The concentrations of glutathione (GSH), lactate, taurine, and glycine were decreased and most of amino acids, choline analogues, and pyruvate were increased by the AgNPs. Moreover, the levels of the metabolites were recovered upto similar level of metabolites in the normal cell by the pre-treatment of NAC, external antioxidant. The results suggest that the depletion of the GSH by the AgNPs might induce the conversion of lactate and taurine to the pyruvate.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1158-1164
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• 2011

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT), a psychoactive tryptamine derivative, is a hallucinogenic drug of abuse. In this study, 5-OH-DIPT and its metabolites were identified and the quantitative method was developed and validated by using hydrophilic interaction chromatography-tandem mass spectrometry (HILICMS/MS). Chromatographic separation was achieved on an Atlantis HILIC silica column ($5{\mu}m$, $100{\times}2.1\;mm$). The metabolites of 5-MeO-DIPT in rat urine were characterized via Q1 scanning and product ion scanning. As a consequence, 5-MeO-IPT, 5-OH-DIPT, 6-OH-5-MeO-DIPT and their glucuronide conjugates were detected and identified as the metabolites of 5-MeO-DIPT. Subsequently, a quantitative method for 5-MeO-DIPT and its major metabolites, 5-MeO-IPT and 5-OH-DIPT, was developed in multiple reactions monitoring (MRM) mode. The calibration curves for all analytes evidenced good linearity over the concentration range of 1-1000 ng/mL with linear correlation co-efficients ($r^2$) in excess of 0.99. The intra- and inter-day accuracy and precision were 92.2-110.2% and 1.5-9.9%, respectively.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1170-1178
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• 2011

In the present study, the approach of high accuracy mass measurements for phospholipid identifications was evaluated using a 7 T ESI-FTMS/linear ion trap MS/MS. Experiments were carried out for porcine brain, bovine liver, and soybean total lipid extracts in both positive and negative ion modes. In total, 59, 55, and 18 phospholipid species were characterized in the positive ion mode for porcine brain, bovine liver, and soybean lipid extracts, respectively. Assigned lipid classes were PC, PE, PEt, PS, and SM. In the negative ion mode, PG, PS, PA, PE, and PI classes were observed. In the negative ion mode, for porcine brain, bovine liver, and soybean lipid extracts, 28, 34, and 29 species were characterized, respectively. Comparison of our results with those obtained by other groups using derivatization-LC-APCI MS and nano-RP-LC-MS/MS showed that our approach can characterize PC species as effectively as those methods could. In conclusion, we demonstrated that high accuracy mass measurements of total lipid extracts using a high resolution FTMS, particularly, 7T FTMS, plus ion-trap MS/MS are very useful in profiling lipid compositions in biological samples.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2170-2174
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• 2010

The surfaces of $TiO_2$ and ZnO nanoparticles have been modified by gold (Au) nanoparticles by a reduction method in solution. Their interfacial electronic structures and optical absorptions have been studied by depth-profiling X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy, respectively. Upon Au-modification, UV-vis absorption spectra reveal a broad surface plasmon peak at around 500 nm. For the as-prepared Au-modified $TiO_2$ and ZnO, the Au $4f_{7/2}$ XPS peaks exhibit at 83.7 and 83.9 eV, respectively. These are due to a charge transfer effect from the metal oxide support to the Au. For $TiO_2$, the larger binding energy shift from that (84.0 eV) of bulk Au could indicate that Au-modification site of $TiO_2$ is different from that of ZnO. On the basis of the XPS data with sputtering depth, we conclude that cationic (1+ and 3+) Au species, plausibly $Au(OH)_x$ (x = 1-3), commonly form mainly at the Au-$TiO_2$ and Au-ZnO interfaces. With $Ar^+$ ion sputtering, the oxidation state of Ti dramatically changes from 4+ to 3+ and 2+ while that (2+) of Zn shows no discernible change based on the binding energy position and the full-width at half maximum (FWHM).

• Journal of Ginseng Research
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• v.40 no.4
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• pp.344-350
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• 2016

Background: Mountain-cultivated ginseng (MCG) and cultivated ginseng (CG) both belong to Panax ginseng and have similar ingredients. However, their pharmacological activities are different due to their significantly different growth environments. Methods: An ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS)-based approach was developed to distinguish MCG and CG. Multivariate statistical methods, such as principal component analysis and supervised orthogonal partial-least-squares discrimination analysis were used to select the influential components. Results: Under optimized UPLC-QTOF-MS/MS conditions, 40 ginsenosides in both MCG and CG were unambiguously identified and tentatively assigned. The results showed that the characteristic components of CG and MCG included ginsenoside Ra3/isomer, gypenoside XVII, quinquenoside R1, ginsenoside Ra7, notoginsenoside Fe, ginsenoside Ra2, ginsenoside Rs6/Rs7, malonyl ginsenoside Rc, malonyl ginsenoside Rb1, malonyl ginsenoside Rb2, palmitoleic acid, and ethyl linoleate. The malony ginsenosides are abundant in CG, but higher levels of the minor ginsenosides were detected in MCG. Conclusion: This is the first time that the differences between CG and MCG have been observed systematically at the chemical level. Our results suggested that using the identified characteristic components as chemical markers to identify different ginseng products is effective and viable.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.38.1-38.1
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• 2009

Plasma etching is an essential process for electronic device industries and the particulate contamination during plasma etching has been interested as a big issue for the yield of productivity. The oxynitride glasses have a merit to prevent particulate contamination due to their amorphous structure and plasma etching resistance. The YSiAlON oxynitride glasses with increasing nitrogen content were manufactured. Each oxynitride glasses were fluorine-plasma etched and their plasma etching rate and surface roughness were compared with reference materials such as sapphire, alumina and quartz. The reinforcement mechanism of plasma etching resistance of the YSiAlON glasses studied by depth profiling at plasma etched surface using electron spectroscopy for chemical analysis. The plasma etching rate decreased with nitrogen content and there was no selective etching at the plasma etched surface of the oxynitride glasses. The concentration of silicon was very low due to the generation of SiF4 very volatile byproduct and the concentration of aluminum and yttrium was relatively constant. The elimination of silicon atoms during plasma etching was reduced with increasing nitrogen content because the content of the nitrogen was constant. And besides, the concentration of oxygen was very low on the plasma etched surface. From the study, the plasma etching resistance of the glasses may be improved by the generation of nitrogen related structural groups and those are proved by chemical composition analysis at plasma etched surface of the YSiAlON oxynitride glasses.

• Journal of the Korean Wood Science and Technology
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• v.48 no.5
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• pp.591-607
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• 2020

This study was aimed to investigate the changes of chemical composition of the volatile organic compounds (VOCs) emitted from red pine needles in the process of needle abscission or senescence. The VOCs in intact, senescent, and litter red pine needle samples were analyzed by headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS). And then, multivariate statistical interpretation of the processed data sets was conducted to investigate similarities and dissimilarities of the needle samples. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to investigate the dataset structure and discrimination between samples, respectively. From the data preview, the levels of major components of VOCs from needles were not significantly different between needle samples. By PCA investigation, the data reduction according to classification based on the chlorophyll a / chlorophyll b (Ca/Cb) ratio were found to be ideal for differentiating intact, senescent, and litter needles. The following OPLS-DA taking Ca/Cb ratio as y-variables showed that needle samples were well grouped on score plot and had the significant discriminant compounds, respectively. Several compounds had significantly correlated with Ca/Cb ratio in a bivariate correlation analysis. Notably, the litter needles had a higher content of oxidized compounds than the intact needles. In summary, we found that chemical compositions of VOCs between intact, senescent, and litter needles are different each other and several compounds reflect characteristic of needle.

• Journal of Pharmacopuncture
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• v.25 no.2
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• pp.121-129
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• 2022

Objectives: The chemical composition of cactus pear seed oil (Opuntia ficus-indica [L.] Mill.) was analyzed in terms of its fatty acid composition, tocopherol content, phenolic identification, and the oil's phenolic-rich fraction antioxidant power was determined. Methods: Fatty acid profiling was performed by gas chromatography coupled to an FI detector. Tocopherols and phenolic compounds were analyzed by LC-FLD/UV, and the oil's phenolic-rich fraction antioxidant power was determined by phosphomolybdenum, DPPH assay and β-carotene bleaching test. Results: Fatty acid composition was marked by a high unsaturation level (83.22 ± 0.34%). The predominant fatty acid was linoleic acid (66.79 ± 0.78%), followed by oleic acid (15.16 ± 0.42%) and palmitic acid (12.70 ± 0.03%). The main tocopherol was γ-tocopherol (172.59 ± 7.59 mg/kg. In addition, Tyrosol, vanillic acid, vanillin, ferulic acid, pinoresinol, and cinnamic acid were identified as phenolic compounds in the analyzed seed oil. Moreover, the oil's phenolics-rich fraction showed a significant total antioxidant activity, scavenged DPPH up to 97.85%, and effectively protected β-carotene against bleaching (97.56%). Conclusion: The results support the potential use of cactus pear seed oil as a functional food.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.431-431
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• 2016

Typical Cu(In,Ga)Se2 (CIGS)-based solar cells have a buffer layer between CIGS absorber layer and transparent ZnO front electrode, which plays an important role in improving the cell performance. Among various buffer materials, chemical bath deposition (CBD)-ZnS is being steadily studied to alternative to conventional CdS and the efficiency of CBD-ZnS/CIGS solar cell shows the comparable values with that of CdS/CIGS solar cell. The intriguing thing is that reversible changes occur after exposure to illumination due to the metastable defect states in completed ZnS/CIGS solar cell, which induces an improvement of solar cell performance. Thus, it implies that the understanding of metastable defects in CBD-ZnS/CIGS solar cell is important issue. In this study, we fabricate the ITO/i-ZnO/CBD-ZnS/CIGS/Mo/SLG solar cells by controlling the NH4OH mole concentration (from 2 M to 3.5 M) of CBD-ZnS buffer layer and observe their conversion efficiency with and without light soaking for 1 hr. From the results, NH4OH mole concentration and light exposure can significantly affect the CBD-ZnS/CIGS solar cell performance. In order to investigate that which layer can contain metastable defect states to influence on solar cell performance, impedance spectroscopy and capacitance profiling technique with exposure to illumination have been applied to CBD-ZnS/CIGS solar cell. These techniques give a very useful information on the density of states within the bandgap of CIGS, free carriers density, and light-induced metastable effects. Here, we present the rearranged charge distribution after exposure to illumination and suggest the origin of the metastable defect states in CBD-ZnS/CIGS solar cell.

• Analytical Science and Technology
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• v.30 no.6
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• pp.355-378
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• 2017

Because neurochemicals are related to homeostasis and cognitive and behavioral functions in human body and because they enable the diagnosis of numerous neurodegenerative disorders, there has been increasing interest in the development of analytical platforms for neurochemical profiling in biological samples. In particular, mass spectrometry (MS)-based analytical methods combined with chromatographic separation have been widely used to profile neurochemicals in metabolic pathways. However, development of delicate sample preparation procedures and highly sensitive instrumental detection is necessary considering the trace levels and chemical instabilities of neurochemicals in biological samples. Therefore, in this review, analytical trends in MS-based metabolomics approaches to neurochemicals in multiple biological samples, such as urine, blood, CSF, and biological tissues, are discussed. This paper is expected to contribute to the development of an analytical platform to discover biomarkers that will aid diagnosis, prognosis, and treatment of neurodegenerative disorders.