• Analytical Science and Technology
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• v.8 no.3
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• pp.229-236
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• 1995

Multiple-step gradient method was used for the analysis of free amino acids in physiological fluids by high-performance liquid chromatography with diode array detector on the Amino Quant $C_{18}$ column under the condition of pH 7.2 of buffer solutions. Plasma samples of normal Korean people and abnormal Korean people who have schizophrenia were subjected to derivatization with o-phthalaldehyde in the presence of 3-mercaptopropionic acid. Quantitative analysis of amino acids in physiological fluids by internal standard method gave highly reproducible results within a relative standard deviation of less than 2~6%. And amino acids amounts of physiological fluids of Korean people gave some different results from those of foreigners. There was large differences in tyrosine amount between normal and abnormal man.

• Membrane Journal
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• v.16 no.4
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• pp.276-285
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• 2006

Acid-doped sulfonated poly(aryl ether benzimidazole) (S-PAEBI) copolymers were synthesized by a direct polymerization technique and a doping with phosphoric acid as a dopant, and the polymer electrolyte membranes were fabricated from them by a solution casting method. To optimize the reaction condition, the degree of sulfonation and doping level were varied in the ranges of $0{\sim}60%\;and\;0.7{\sim}5.7$, respectively. Physiochemical properties of the doped membranes were investigated by AFM, TGA and the measurement of proton conductivity. It was found that proton conductivities depend on doping levels of membranes. Conductivity determined at the condition of $130^{\circ}C$ and no humidity was $7.3{\times}10^{-2}S/cm$ for the $H_3PO_4$-doped PAEBI membrane with a doping level of 5.7.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.623-623
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• 2013

그래핀(graphene)의 라만 스펙트럼은 전하밀도(charge density)와 기계적 변형(strain)에 민감하여 수많은 연구에 활용되고 있다. 그러나 실제 시료에서 관찰되는 두 물질량의 복잡한 변이를 정량 분석하기 위해서는 기계적 변형뿐만 아니라 전하밀도의 영향에 대한 신뢰도 높은 검정곡선이 필요하다. 본 연구에서는 기계적 박리법으로 만들어진 그래핀에서 나타나는 기계적 변형과 황산 수용액이 미치는 p-형 화학도핑(chemical doping)의 영향을 라만 분광법을 이용하여 연구하였다. 농도 변화에 따른 G와 2D 피크의 진동수 변화는 정전기적 방법을 이용하여 보고된 결과보다 높은 재현성을 보여 검정곡선으로 활용되기에 적합함을 알 수 있었다. 본 연구에서는 514 nm 이외에도 널리 활용되는 몇 가지 파장에서 "전하밀도-변형" 검정곡선을 제시하고자한다.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.423-428
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• 2015

(1S)-(+)-10-camphorsulfonic acid (CSA) and HCl were used together as a binary dopant in the electrodeposition of polyaniline (PAni). (+)-CSA and HCl were added in different mole ratios (9:1 and 6:4). (+)-CSA-doped and binary-doped PAni exhibited markedly different ultraviolet-visible and circular dichroism spectral characteristics due to differences in their conformations. Distinct helical structures are observed in the scanning electron microscopy images of (+)-CSA-doped PAni. The X-ray diffraction pattern of (+)-CSA-doped PAni exhibited remarkably higher crystallinity than that of HCl-doped PAni which is associated with the helical ordering along the polymer chains. The conformational changes due to the binary doping in chiral PAni had a significant effect on its chiroptical and electrochemical properties, morphology, and crystallinity, thus determined its conductivity.

• Bulletin of the Korean Chemical Society
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• v.27 no.6
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• pp.821-829
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• 2006

A series of catalysts, $NiO/La_2O_3-ZrO_2/WO_3$, for acid catalysis was prepared by the precipitation and impregnation methods. For the $NiO/La_2O_3-ZrO_2/WO_3$ samples, no diffraction lines of nickel oxide were observed, indicating good dispersion of nickel oxide on the catalyst surface. The catalyst was amorphous to X-ray diffraction up to 300 ${^{\circ}C}$ of calcination temperature, but the tetragonal phase of $ZrO_2$ and monoclinic phase of $WO_3$ by the calcination temperatures from 400 ${^{\circ}C}$ to 700 ${^{\circ}C}$ were observed. The role of $La_2O_3$ in the catalyst was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity. The high acid strength and high acidity were responsible for the W=O bond nature of complex formed by the modification of $ZrO_2$ with $WO_3$. For 2-propanol dehydration the catalyst calcined at 400 ${^{\circ}C}$ exhibited the highest catalytic activity, while for cumene dealkylation the catalyst calcined at 600 ${^{\circ}C}$ showed the highest catalytic activity. 25-$NiO/5-La_2O_3-ZrO_2/15-WO_3$ exhibited maximum catalytic activities for two reactions due to the effects of $WO_3$ modifying and $La_2O_3$ doping.

• YAKHAK HOEJI
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• v.36 no.3
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• pp.230-240
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• 1992

The metabolic profile of doxylamine, N,N-dimethyl-2-[1-phenyl-1-(2-pyridinyl)ethoxy] ethanamine, was determined in the human urine. The free fractions of extracts were obtained without hydrolysis, and the conjugated fractions of extracts were obtained with enzyme hydrolysis using ${\beta}-glucuronidase/arylsulfatase$ from Helix pomatia. The mixture of acetic anhydride/pyridine (10 : 1, v : v) was used to derivatize the urinary extracts and then analyzed by gas chromatography and mass selective detector. N-desmethyldoxylamine, doxylamine carboxylic acid, desaminohydroxydoxylamine, N, N-didesmethyldoxylamine, N-acetyl conjugates of N-desmethyl and N, N-didesmethyldoxylamine, quarternary ammonium N-glucuronide of doxylamine, N-desmethyldoxylamine N-glucuronide and unchanged doxylamine were detected in the human urine obtained after oral treatment with doxylamine succinate. $N-methyl-{\alpha}-hydroxy-2-[1-phenyl-1-(2-pyridinyl)$ ethoxy] ethanamine, which can be a key intermediate of this metabolism, was tentatively identified by the interpretation of its mass spectrum. In this study, we proposed the metabolic pathway of doxylamine in the human on the basis of our data of the identified metabolites of doxylamine.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1067-1072
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• 2014

In this study, we report a new approach for $Mn_3O_4$-graphene nanocomposite by ex situ method. This nanocomposite shows two-dimensional aggregation of nanoparticle, and doping effect by decorated manganese oxide ($Mn_3O_4$), as well. The graphene film was made through micromechanical cleavage of graphite on the $SiO_2/Si$ wafer. Manganese oxide ($Mn_3O_4$) nanoparticle with uniform cubic shape and size (about $5.47{\pm}0.61$ nm sized) was synthesized through the thermal decomposition of manganese(II) acetate, in the presence of oleic acid and oleylamine. The nanocomposite was obtained by self-assembly of nanoparticles on graphene film, using hydrophobic interaction. After heat treatment, the decorated nanoparticles have island structure, with one-layer thickness by two-dimensional aggregations of particles, to minimize the surface potential of each particle. The doping effect of $Mn_3O_4$ nanoparticle was investigated with Raman spectra. Given the upshift in positions of G and 2D in raman peaks, we suggest that $Mn_3O_4$ nanoparticles induce p-doping of graphene film.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1996.12a
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• pp.63-63
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• 1996

We performed chromosomal aberration assay in Chinese Hamster Lung (CHL) cells in vitro to evaluate theclastogenicity of 11 synthetic chemicals which were listed in Toxicity Evaluation Program of Ministry of Environment of Republic of Korea in 1996. All of the chemicals were carried out MTT assay to determine the 50% cell growth inhibition concentration. All compounds were tested with and without metabolic activation system. Benzoyl chloride revealed positive result at $43\;\mu\textrm{g}/m{\ell}$ in the presence of metabolic activation system, and at 30.8, 61.5 and $123\;\mu\textrm{g}/m{\ell}$ in the absence of metabolic activation system. And p-phenoxy ethanol was observed as positive with the metabolic activation system, but negative without metabolic activation system. Especially 2-propyn-l-ol showed high frequency of pulverization and showed critical difference of cytotoxicity between with and without S9 mixture. Pulverizatiuon is not included in the frequency of structural aberration in our criteria. Dicyclopentadiene, methacrylic acid, aa-dimethylbenzyl hydroperoxide, benzylbutyl phthalate, and p-chlorophenal were revealed negative results.esults.

• Analytical Science and Technology
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• v.13 no.4
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• pp.504-510
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• 2000

The impurity profiles from the raw materials of glycyrrhizin were performed by the high performance liquid chromatography (HPLC)/electrospray ionization (ESI)- mass spectrometry (MS). For the HPLC experiment, a $C_{18}$($3.9{\times}300mm$, $10{\mu}m$) column was used and the mobile phase was acetic acid/$H_2O$ (1:10):acetonitrile=3:2 with a flow rate of 0.8 ml/min. The effluent was splitted into the ratio of 50:1 and went into the ESI-MS. Three to six impurities were found and informed of the identification of the structure of the impurities by ESI-MS. And the structures of impurities were suggested to a hydroxy-glycyrrhizin which is added with hydroxy group (-OH) in the glycyrrhetic acid moiety and a reduced-glycyrrhizin which the position of 12 of the glycyrrhetic acid moiety is reduced. The purities of the standard materials were about 90%.

• Journal of the Korean Electrochemical Society
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• v.6 no.2
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• pp.134-140
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• 2003

Stretchable Polypyrrole films(Ppy-DBSA, Ppy-mixed dopants) using functionalized doping agents dodecyl-benzensulfonic acid (DBSA) and mixed dopants{DBSA with $LIClO_4$, NSA (2-naphthalenesulfonic acid), DEHSA [di(2-ethylhexyl)sulfosuccinic acid]}, were synthesized by electrochemical method. Electrochemically prepared Polypyrrole films were stretch-oriented $(L/L_0=1.0-2.5)$ by a Bone drawing method and their electrical conductivities were measured. As the drawing ratio was increased, the electrical conductivities were increased. This results might be due to the increase in crystallinity through the incresase in draw ratio. The results of temperature dependence of electrical conductivity showed that power raw $(L/L_0=1.0-2.5)$ gave the best fit to the data for stretched Ppy-DBSA and Ppy-mixed dopants films.