• Title, Summary, Keyword: Chemical Analyses

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The Chemical COmposition Analysis by AES and XPS of PbTiO$_3$ Thin Films Fabricated by CVD (화학증착법에 의해 제조된 PbTiO$_3$ 박막의 AES와 XPS에 의한 조성분석)

  • Soon Gil Yoon;Ho Gi Kim
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.83-86
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    • 1989
  • Lead titanate thin films with a perovskite structure were successfully structure were successfully fabricated on titanium substrate by Chemical Vapour Deposition(CVD). Analyses of Auger Electron Spectroscopy(AES) and X-ray Photoelectron Spectroscopy (XPS) have been performed in order to find a chemical composition of lead titanate films. The analysis of chemical composition by AES and XPS was investigated for variations of deposition temperature and Ti(C$_2$H$_{5}$O)$_4$ fractions. The chemical composition of PbTiO$_3$by XPS analysis was almost constant regardless of deposition parameters and the comparison of chemical composition by AES and XPS was performed.d.

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Verlamelin, an Antifungal Compound Produced by a Mycoparasite, Acremonium strictum

  • Kim, Jin-Cheol;Park, Gyung-Ja;Kim, Hyun-Ju;Kim, Heung-Tae;Ahn, Jong-Woong;Cho, Kwang-Yun
    • The Plant Pathology Journal
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    • v.18 no.2
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    • pp.102-105
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    • 2002
  • A strain of Acremonium strictum, the mycoparasite of Botrytis cinerea, showed strong antifungal activities both in vitro and in vivo against several phytopathogenic fungi. An antifungal substance was purified from the liquid cultures of A. strictum and identified as verlamelin by instrumental analyses. Verlamelin exhibited in vitro antifungal activity against some phytopathogenic fungi such as Magnaporthe grisea, Bipolaris maydis, and Botrytis cinerea, while it was net active against all the bacteria tested. In viva, verlamelin exhibited strong protective and curative activities, particularly against barley powdery mildew. At 100 μg/ml, it inhibited the development of barley powdery mildew with control values of more than 90% in 7-day protective and 2-day curative applications. This is the first report on the production of verlamelin by Acremonium species.

Hydroxyhibiscone A, a Novel Human Neutrophil Elastase Inhibitor from Hibiscus syriacus

  • Ryoo, In-Ja;Yun, Bong-Sik;Lee, In-Kyoung;Kim, Young-Hee;Lee, Ik-Soo;Ahn, Jong-Seok;Bae, Ki-Hwan;Yoo, Ick-Dong
    • Journal of Microbiology and Biotechnology
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    • v.20 no.8
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    • pp.1189-1191
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    • 2010
  • In an ongoing investigation of compounds from natural products that exhibit anti-aging properties, hydroxyhibiscone A (1), a new furanosesquiterpenoid, together with hibiscone D (2), was isolated from the root bark of Hibiscus syriacus. Utilizing UV, IR, NMR, and MS spectroscopic analyses, these chemical structures were revealed. Compounds 1 and 2 were found to posses significant anti-aging properties on the human neutrophil elastase (HNE) assay, exhibiting HNE inhibitory activities with $IC_{50}$ values of 5.2 and 4.6 ${\mu}M$, respectively.

Characterization for Pyrolysis of Thermoplastic Polyurethane by Thermal Analyses

  • Kang Suk-Hwan;Ku Dong-Cheol;Lim Jung-Hun;Yang Yun-Kyu;Kwak Noh-Seok;Hwang Taek-Sung
    • Macromolecular Research
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    • v.13 no.3
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    • pp.212-217
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    • 2005
  • The pyrolysis kinetics of polyurethanes synthesized from polycaprolactone diol (PCL) and diisocyanate (HDI, $H_{12}MDI$) using catalysts such as dibutyltin dilaurate (DBTDL) were studied by a thermogravimetric (TG) technique, which involved heating the sample at the rates of 10, 20 and $30^{\circ}C$/min. The effect of the kind of diisocyanate and the hard segment contents on the activation energy and reaction order were examined at conversions ranging from 1 to $100\%$. The activation energies at first increased slowly with increasing conversion. Also, differential scanning calorimetry (DSC) was used to investigate the structural differences in each polyurethane. DSC can reveal the melting behavior, in terms of the glass transition temperature ($T_g$), which is known to vary as a function of the stoichiometry and processing conditions.

Topological Study of the Behavior of Inorganic Fine Powers and a Nanovesicle Hybridized Coating

  • Seo, Dong-Sung;Kim, Dong-Pyo;Jin, Fan-Long;Park, Soo-Jin
    • Bulletin of the Korean Chemical Society
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    • v.30 no.2
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    • pp.343-347
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    • 2009
  • In this study, the surface of inorganic fine powders is hybridized with nanovesicles containing tocopheryl acetate prepared with hydrogenated lecithin via a coating process. From AFM and SEM analyses it is found that the surface of the nanovesicle-coated fine powders lost their traditional topology and improved in terms of their roughness, skewness, and kurtosis. In addition, TEM observations revealed the formation of a 5 nm thick coating layer on the surface of the fine powders. These hybridized powders, in which bioactive materials such as tocopheryl acetate can be embedded, can be employed as a part of a drug delivery system due to their special ability to control release rate and temperature selectivity. Physical properties of the powders, i.e., the different angle and friction coefficient, were excellent.

Kinetically Controlled Growth of Gold Nanoplates and Nanorods via a One-Step Seed-Mediated Method

  • Hong, Soonchang;Acapulco, Jesus A.I. Jr.;Jang, Hee-Jeong;Kulkarni, Akshay S.;Park, Sungho
    • Bulletin of the Korean Chemical Society
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    • v.35 no.6
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    • pp.1737-1742
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    • 2014
  • In this research, we further developed the one-step seed mediated method to synthesize gold nanoparticles (GNPs) and control their resulting shapes to obtain hexagonal, triangular, rod-shaped, and spherical gold nanostructures. Our method reveals that the reaction kinetics of formation of GNPs with different shapes can be controlled by the rate of addition of ascorbic acid, because this is the critical factor that dictates the energy barrier that needs to be overcome. This in turn affects the growth mechanism process, which involves the adsorption of growth species to gold nanoseeds. There were also observable trends in the dimensions of the GNPs according to different rates of addition of ascorbic acid. We performed further analyses to investigate and confirm the characteristics of the synthesized GNPs.

Synthesis of Alumina-Grafted Manganese Oxide Particles Using Surfactants through Coprecipitation Method and Their Thermal Properties

  • Kwon, Boseong;Park, Jun-Hwan;Jang, Seong-Cheol;Oh, Seong-Geun
    • Bulletin of the Korean Chemical Society
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    • v.34 no.12
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    • pp.3559-3564
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    • 2013
  • Alumina particles were grafted onto the surface of manganese oxide particles via the coprecipitation process using surfactant and cosurfactant. The phase of Mn/Al salts (Phase I) and the phase of precipitation agent (Phase II) were prepared in aqueous surfactant solution, separately. Phase II was added into Phase I and the reaction was performed to form the precursors of composites through hydrogen bonding between $Mn(OH)_2$ and $Al(OH)_3$ prepared by the reaction of Mn/Al salts with the precipitation agent. The alumina-grafted manganese oxide particles were obtained as a final product after calcination. The concentrations of Al salt and surfactant were varied to investigate their effects on the formation and the crystallinity of composites. In addition, the crystal structure of products could be controlled by changing the calcination temperature. Through thermal analyses, it was found that the thermal stability of manganese oxide was improved by the introduction of alumina on its surface.

Development and Application of the Backward-tracking Model Analyzer to Track Physical and Chemical Processes of Air Parcels during the Transport (대기오염물질의 이동경로상 물리화학적 변화 추적을 위한 Backward-tracking Model Analyzer 방법론 마련)

  • Bae, Minah;Kim, Hyun Cheol;Kim, Byeong-Uk;Kim, Soontae
    • Journal of Korean Society for Atmospheric Environment
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    • v.33 no.3
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    • pp.217-232
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    • 2017
  • An Eulerian-Lagrangian hybrid modeling system to analyze physical and chemical processes during the transport of air parcels was developed. The Backward-tracking Model Analyzer (BMA) was designed to take advantages of both Eulerian and Lagrangian modeling approaches. Simulated trajectories from the National Oceanic and Atmospheric Administration HYSPLIT model were combined with the US Environmental Protection Agency Community Multi-scale Air Quality (CMAQ)-simulated concentrations and additional diagnostic analyses. In this study, we first introduced a generalized methodology to seamlessly match polylines (HYSPLIT) and threedimensional polygons (CMAQ), which enables mass-conservative analyses of physio-chemical processes of transporting air parcels. Two applications of the BMA were conducted: (1) a long-range transport case of pollutant plume across the Yellow Sea using CMAQ Integrated Process Rate analyses, and (2) a domestic circulation of pollutants within (and near) the South Korea based on the sulfate tracking analyzer. The first episode demonstrated a secondary formation of nitrate and ammonium during the transport over the Yellow Sea while sulfate is mostly transported after being formed over the China, and the second episode demonstrated a dominant impact of boundary condition with active sulfate formation from gas-phase oxidation near the Seoul Metropolitan Area.

Ecotoxicological Evaluation of Sewage Sludge Using Bioluminescent Marine Bacteria and Rotifer

  • Park, Gyung-Soo;Chung, Chang-Soo;Lee, Sang-Hee;Hong, Gi-Hoon;Kirn, Suk-Hyun;Park, Soung-Yun;Yoon, Seong-Jin;Lee!, Seung-Min
    • Ocean Science Journal
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    • v.40 no.2
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    • pp.91-100
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    • 2005
  • Bioassay using the marine bacteria, Vibrio fischeri and rotifer, Brachionus plicatilis, and chemical analyses were conducted to assess the toxicity of the various sewage sludges, one of the major ocean dumped materials in the Yellow Sea of Korea. Sludge elutriates extracted by filtered seawater were used to estimate the ecotoxicity of the sludge. Chemical characterization included the analyses of organic contents, heavy metals, and persistent organic pollutants in sludge. Bacterial bioluminescent inhibition (15 min), rotifer mortality (24 hr) and rotifer population growth inhibition (48 hr) assay were conducted to estimate the sludge toxicity. EC50 15 min (inhibition concentration of bioluminescence after 15 minutes exposed) values by Microtox(R) bioassay clearly revealed different toxicity levels depending on the sludge sources. Highest toxicity for the bacteria was found with the sludge extract from dyeing waste and followed by industrial waste, livestock waste, and leather processing waste. Clear toxic effects on the bacteria were not found in the sludge extract from filtration bed sludge and rural sewage sludge. Consistent with Microtox(R) results, rotifer neonate mortality and population growth inhibition test also showed highest toxicity in dyeing waste and low in filtration bed and rural sewage sludge. High concentrations of persistent organic pollutants (POPs) and heavy metals were measured in the samples from the industrial wastes, leather processing plant waste sludge, and urban sewage sludge. However, there was no significant correlation between pollutant concentration levels and the toxicity values of the sludge. This suggests that the ecotoxicity in addition to the chemical analyses of various sludge samples must be estimated before release of potential harmful waste in the natural environment as part of an ecological risk assessment.

Economic Evaluations of DCL/ICL Processes (직·간접석탄액화공정의 경제성 평가)

  • Park, Joo-Won;Bae, Jong-Soo;Kweon, Yeong-jin;Kim, Hak-Joo;Jung, Heon;Han, Choon
    • Korean Chemical Engineering Research
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    • v.47 no.6
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    • pp.781-787
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    • 2009
  • This report investigates the economic proprieties of commercial 50,000 barrel per day direct/indirect coal liquefaction(DCL/ICL) plants to produce commercial-grade diesel and naphtha liquids. The scope of the study includes capital and operating cost estimates, sensitivity analyses and a comparative financial analyses. Based on plant capacity of 50,000BPD, employing Illinois #6 bituminous coal as feed coal, the total capital cost appeared $3,994,858,000(DCL) and $4,962,263,000(ICL). Also, the internal rate of return of DCL/ICL appeared 13.27% and 12.68% on the base condition respectively. In this case, coal price and sale price of products were the most influence factors. And ICL's payback period(6.8 years) was longer than DCL's(6.6 years). According to sensitivity analyses, the important factors on both DCL/ICL processes were product sale price, feed coal price and the capital cost in order.