• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.559-565
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• 2003

An analytical method the determination of benzo(a)pyrene (BaP) and its hydroxylated metabolites, 1-hydroxybenzo(a)pyrene (1-OHBaP), 3-hydroxybenzo(a)pyrene (3-OHBaP), benzo(a)pyrene-4,5-dihydrodiol (4,5-diolBaP) and benzo(a)pyrene-7,8-dihydrodiol (7,8-diolBaP), in rat urine and plasma has been developed by HPLC/FLD and GC/MS. The derivatization with alkyl iodide was employed to improve the resolution and the detection of two mono hydroxylated metabolites, 1-OHBaP and 3-OHBaP, in LC and GC. BaP and its four metabolites in spiked urine were successfully separated by gradient elution on reverse phase ODS $C_{18}$ column (4.6 mm I.D., 100 mm length, particle size 5 ㎛) using a binary mixture of MeOH/H₂O (85/15, v/v) as mobile phase after ethylation at 90 ℃ for 10 min. The extraction recoveries of BaP and its metabolites in spiked samples with liquid-liquid extraction, which was better than solid phase extraction, were in the range of 90.3- 101.6% in n-hexane for urine and 95.7-106.3% in acetone for plasma, respectively. The calibration curves has shown good linearity with the correlation coefficients (R²) varying from 0.992 to 1.000 for urine and from 0.996 to 1.000 for plasma, respectively. The detection limits of all analytes were obtained in the range of 0.01-0.1 ng/mL for urine and 0.1-0.4 ng/mL for plasma, respectively. The metabolites of BaP were excreted as mono hydroxy and dihydrodiol forms after intraperitoneal injection of 20 mg/kg of BaP to rats. The total amounts of BaP and four metabolites excreted in dosed rat urine were 3.79 ng over the 0-96 hr period from adminstration and the excretional recovery was less than 0.065% of the injection amounts of BaP. The proposed method was successfully applied to the determination of BaP and its hydroxylated metabolites in rat urine and plasma for the pharmacokinetic studies.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2760-2764
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• 2013

Geniposide is a biologically active ingredient of gardenia fruit. A liquid chromatography-tandem mass spectrometric method was developed and validated for the determination of geniposide in rat plasma. The plasma samples were pretreated by solid-phase extraction and introduced into a BDS Hypersil $C_{18}$ column ($50{\times}2.1mm$, $5{\mu}m$) for chromatographic separation. The mobile phase consisted of 0.1% formic acid and 0.1% formic acid in acetonitrile, and gradient elution was performed at a flow rate of 0.25 mL/min. For mass spectrometric detection, multiple reaction monitoring was performed via an electrospray ionization source in positive mode. The calibration curve for geniposide was linear ($r^2=0.997$) in the concentration range of $0.005-1{\mu}g/mL$. The intra- and inter-day accuracies and precisions fulfilled the required criteria (${\pm}15%$). The developed method was subsequently used for pharmacokinetic analysis of geniposide after oral administration to rats at a dose of 50 mg/kg. The mean maximum plasma concentration of geniposide was $0.68{\pm}0.29{\mu}g/mL$ at $0.44{\pm}0.13h$, and the mean area under the plasma concentration versus time curve was $1.46{\mu}g{\cdot}h/mL$.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.401.3-402
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• 2002

Enalapril (ENP) maleate is effective drug for the treatment of renivascular hypertension and heart failure. ENP acts as inhibitor of the enzyme angiotensin-convertase (ACE-inhibitor) and metabolized to enalaprilat (ENPT), which is the active metabolite that is really responsible for the therapeutic action. In the present study, a sensitive and rapid liquid chromatography/ electrospray ion trap tandem mass spectrometry (LC/MS/MS) method combined with high-throughput solid phase extraction (SPE) has been developed and validated for the simultaneous quantitative determination of ENP and ENPT in human plasma. (omitted)

• Journal of Powder Materials
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• v.14 no.6
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• pp.405-409
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• 2007

The Cu-based bulk metallic glass (BMG) composites containing Zr-based metallic glass phase have been consolidated by spark plasma sintering using the mixture of Cu-based and Zr-based metallic glass powders in their overlapped supercooled liquid region. The Zr-based metallic glass phases are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation process. The successful consolidation of BMG composites with dual amorphous phases was corresponding to the sound viscous flow of the two kinds of metallic glass powders in their overlapped supercooled liquid region.

• Journal of Powder Materials
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• v.18 no.2
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• pp.112-121
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• 2011

This study investigated the effect of solvent on the fabrication of Ni-free Fe-based alloy nano powders by employing the PWE (pulsed wire evaporation) in liquid and compared the alloy particles fabricated by three different methods (PWE in liquid, PWE in Ar, plasma arc discharge), for high temperature oxidation-resistant metallic porous body for high temperature soot filter system. Three different solvents (ethanol, acetone, distilled water) of liquid were adapted in PWE in liquid process, while X-ray diffraction (XRD), field emission scanning microscope (FE-SEM), and transmission electron microscope (TEM) were used to investigate the characteristics of the Fe-Cr-Al nano powders. The alloy powder synthesized by PWE in ethanol has good particle size and no surface oxidation compared to that of distilled water. Since the Fe-based alloy powders, which were fabricated by PWE in Ar and PAD process, showed surface oxidation by TEM analysis, the PWE in ethanol is the best way to fabricate Fe-based alloy nano powder.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1900-1902
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• 2004

The degradation systems of non degradable waste water consist of the arc plasma torch, power supply, a feeder of liquid waste and reactors. Output of stable plasma torch, suitable air flux, microscopic atomizing state of waste water and long reaction section must be to degrade waste water more efficiently. In this paper, we are designed the stable power system, the microscopic atomizing state of waste water and the efficient reactors to satisfy various conditions. Non degradable wast water used in this work was $Na_2$EDTA of 1.0 mol. The concentration of $CO_2$ and EDTA was analyzed using GC (Gas Chromatography) and HPLC (High Performance Liquid Chromatography). In the result show that $CO_2$ concentration was about 96% and EDTA was degraded approximately 96%.

• Journal of Powder Materials
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• v.20 no.1
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• pp.33-36
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• 2013

A bulk metallic glass-forming alloy, $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ metallic glass powders was used for good commercial availability and good formability in supercooled liquid region. In this study, the Ni-based metallic glass was synthesized using by high pressure gas atomized metallic glass powders. In order to create a bulk metallic glass sample, the $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ metallic glass powders with ball-milled Ni-based amorphous powder with 40%vol brass powder and Cu powder for 20 hours. The composite specimens were prepared by Spark Plasma Sintering for the precursor. The SPS was performed at supercooled liquid region of Ni-based metallic glass. The amorphous structure of the final sample was characterized by SEM, X-ray diffraction and DSC analysis.

• Journal of the Korean institute of surface engineering
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• v.53 no.3
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• pp.87-94
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• 2020

Herein, sulfonated carbon nanotubes (CNT) have been prepared in dilute sulfuric acid (H₂SO₄) via a novel sulfonation approach based on gas-liquid interfacial plasma (GLIP) at room temperature. The sulfonic acid groups and total acid groups densities of CNT after GLIP treatment in 2 M H₂SO₄ for 45 min can reach to 0.53 mmol/g and 3.64 mmol/g, which is higher than that of sulfonated CNT prepared under 0.5 M / 1 M H₂SO₄. The plasma sulfonated CNT has been applied as catalysts for the conversion of microcrystalline cellulose to glucose. The effect of hydrolysis temperature and hydrolysis time on the conversion rate and product distribution have been discussed. It demonstrates that the total conversion rate of cellulose increasing with hydrolysis temperature and hydrolysis time. Furthermore, the GLIP sulfonated CNT prepared in 2 M H₂SO₄ for 45 min has shown high catalytic stability of 85.73 % after three cycle use.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.3035-3040
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• 2014

A new efficient catalytic method for aza/thia-Michael addition reactions of amines/thiols with higher product yields has been developed. Combining single-walled carbon nanotubes (SWCNT) with triethylammonium hydrogen phosphate (TEAP) ionic liquid (IL) can work as a catalyst. We utilized Raman spectroscopy to gain insight into the interactions between IL and SWCNT. The interactions between SWCNT with TEAP were confirmed by the increasing intensity ratios and spectral shift in wavelength of the Raman D and G bands of SWCNT. Further, the morphology of the resulting composite materials of TEAP and SWCNT was determined by using scanning electron microscopy (SEM). Higher product yield in reduced reaction time is the key advantage of using bucky gel as a catalyst for Michael reaction.

• Journal of Environmental Health Sciences
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• v.38 no.3
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• pp.251-260
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• 2012

Objectives: The purpose of this study was evaluating the applicability of the circulation dielectric barrier plasma process (DBD) for efficiently treating non-biodegradable wastewater, such as phenol. Methods: The DBD plasma reactor system in this study consisted of a plasma reactor (discharge, ground electrode and quartz dielectric tube, external tube), high voltage source, air supply and reservoir. Effects of the operating parameters on the degradation of phenol and $UV_{254}$ absorbance such as first voltage (60-180 V), oxygen supply rate (0.5-3 l/min), liquid circulation rate (1.5-7 l/min), pH (3.02-11.06) and initial phenol concentration (12.5-100 mg/l) were investigated. Results: Experimental results showed that optimum first voltage, oxygen supply rate, and liquid circulation rate on phenol degradation were 160 V, 1 l/min, and 4.5 l/min, respectively. The removal efficiency of phenol increased with the increase in the initial pH of the phenol solution. To obtain a removal efficiency of phenol and COD of phenol of over 97% (initial phenol concentration, 50.0 mg/l), 15 min and 180 minutes was needed, respectively. Conclusions: It was considered that the absorbance of $UV_{254}$ for phenol degradation can be used as an indirect indicator of change in non-biodegradable organic compounds. Mineralization of the phenol solution may take a relatively longer time than that required for phenol degradation.