• Resources Recycling
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• v.18 no.6
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• pp.24-29
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• 2009

Since cerium carbonate becomes porous cerium oxide by releasing carbon dioxide and vapour steam during calcination of cerium carbonate, nano size cerium oxide can be obtained by milling calcined cerium carbonate. Therefore cerium carbonate [$Ce_2(CO_3)3{\cdot}XH_2O$] is used generally for the preparation of nano size cerium oxide. In order to obtain nano size cerium oxide from cerium carbonate prepared by reactive crystallization of cerium chloride solution and ammonium bicarnonate solution, the effects of experimental variables in the milling and calcination of cerium carbonate, such as calcination temperature, milling time, rpm of planetary mill, amount of dispersant and ball size for milling on the size of cerium oxide was investigated in this study. Cerium oxide prepared with the conditions of calcination temperature of $700^{\circ}C$, milling time of 5 hour was 160nm mean particle size.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3259-3264
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• 2010

A label-free amperometric immunosensor has been proposed for the detection of myeloperoxidase (MPO) in human serum. To fabricate such an immunosensor, a composite film consisting of N,N-dimethylformamide (DMF), multiwall carbon nanotubes (MWCNTs) and 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMIMBF_4$) suspension was initially formed on a glassy carbon electrode (GCE). Then cerium dioxide ($CeO_2$) dispersed by chitosan was coated on the GCE. After that, MPO antibodies (anti-MPO) were attached onto the nano$CeO_2$ surface. With a noncompetitive immunoassay format, the antibody-antigen complex formed between the immobilized anti-MPO and MPO in sample solution. The immunosensor was characterized by cyclic voltammetry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The factors influencing the performance of the immunosensor were studied in detail. Under optimal conditions, the current change before and after the immunoreaction was proportional to MPO concentration in the range of 5 to $300\;ng\;mL^{-1}$ with a detection limit of $0.2\;ng\;mL^{-1}$.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.104-104
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• 1999

Cerium dioxide 박막의 포토루미네슨에 관해서는 Cerium 4f band에서 oxygen 2p band로의 transition에 의한 발광(400nm) 현상이 보고되었다. 또한 Indium Oxide 박막의 발광(637nm0 현상이 보고되었다. 본 연구에서는 3족인 Indium을 Si/In/CeO2/Si 구조와 CeO2/Si 구조에 도핑하여 포토루미네슨스 현상을 관찰하였다. E-beam evaporator를 사용하여 Silicon(111) 기판에 Cerium dioxcide 박막을 성장시킨 경우의 두가지 시료를 분석하였다. 포토루미네슨스 관찰을 위해서 Ge-Cd laser (325nm)가 사용되었으며 Indium의 도핑양과 분포 상태를 알기 위해 SIMS와 ADP를 이용하여 분석하였다. Indium양에 대한 포토루미네슨스 변화와 열처리 후의 indium의 분포의 변화에 의한 포토루미네슨스 변화를 관찰하였다. 상온에서 In/CeO2/Si 시료와 Si/In/CeO2/Si 시료에 대한 포토루미네슨스 현상을 관찰한 결과 Si/In/CeO2/Si 시료에서만 500nm(2.5eV)에서 발광 현상이 관찰되었다. 도핑된 indium은 ADP에서는 검출되지 않고 SIMS에서만 검출되어 ADP의 detection range(1-0.1%) 이하의 양이 도핑된 것으로 추측된다. 도핑된 Indium의 양이 증가할수록 포토루미네슨스의 Intensity가 증가하였다. 또한 열처리(110$0^{\circ}C$, 1min) 후 포토루미네슨스의 peak위치가 390nm(3.18eV)로 변화하였다. Si/In/CeO2/Si에서 포토루미네슨스 현상이 관측되고 Intensity가 indium의 양에 의존하므로 완전하지 못한 Cerium dioxide의 CeOx 구조와 indium과의 결합이 포토루미네슨스의 원인으로 추측된다. 열처리 후 SIMS의 분석결과 indium의 분포가 변화하였으며 이는 포토루미네슨스의 변화의 원인으로 판단된다.

• Korean Journal of Materials Research
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• v.24 no.1
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• pp.33-36
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• 2014

This study was aimed at synthesizing and characterizing cerium-doped titania. Cerium-doped anatase titania powders were prepared by sol-gel process, with ammonium (IV) nitrate and titanium (IV) butoxide as the raw materials. The characteristics of pure $TiO_2$ and cerium-doped $TiO_2$ were investigated by XRD, TG/DTA, FE-SEM, and UV-vis spectroscopy. The results of this study show that anatase type of $TiO_2$ was obtained in as-prepared and calcined $TiO_2$ and Ce-$TiO_2$ powder. A DTA curve was also observed as the crystallization temperature decreased with increasing cerium contents. We found that the crystallite size of the obtained anatase particles decreased from 55 nm to 25 nm and the particle size decreased with increasing cerium contents. Moreover, UV-vis spectra showed that anatase titania powders with various cerium contents effectively extend the light absorption properties to the visible region.

• Toxicological Research
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• v.25 no.4
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• pp.195-201
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• 2009

Recent publications showed that metal nanoparticles which are made from $TiO_2,\;CeO_2,\;Al_2O_3,\;CuCl_2,\;AgNO_3$ and $ZnO_2$ induced oxidative stress and pro-inflammatory effects in cultured cells and the responses seemed to be common toxic pathway of metal nanoparticles to the ultimate toxicity in animals as well as cellular level. In this study, we compared the gene expression induced by two different types of metal oxide nanoparticles, titanium dioxide nanoparticles (TNP) and cerium dioxide nanoparticles (CNP) using microarray analysis. About 50 genes including interleukin 6, interleukin 1, platelet-derived growth factor $\beta$, and leukemia inhibitory factor were induced in cultured BEAS2B cells treated with TNP 40 ppm. When we compared the induction levels of genes in TNP-treated cells to those in CNP-treated cells, the induction levels were very correlated in various gene categories (r=0.645). This may suggest a possible common toxic mechanism of metal oxide nanoparticles.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.425-431
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• 2018

Composite particles of porous silica and cerium oxide nanoparticles blocking UV/blue light were prepared through a dry coating process. Various composite particles were prepared by varying conditions such as the mixing ratio of cerium oxide and silica, and the chamber rotating speed of mechano fusion system. The surface morphology of the composite particles was observed with SEM and the composition was analyzed using X-ray fluorescence (XRF). When the cerium oxide/silica composite particles were dispersed in water, the transparency and dispersion stability of the colloidal solution were improved. In addition, the fluidity and spreadability of the particle powder were enhanced by making composite particles. These results show that cerium oxide/silica composite particles can be used as functional cosmetic ingredients for UV/blue light protection.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.123-128
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• 2011

It has been stand high in estimation to converse from Carbon dioxide to Dimethyl Ether in new alternative fuel energy division in 21C, especially Using of DME in point of view of transportation fuel has been discussed of a new clean energy which is very lower of exhaust gas than gasoline and diesel energy. In this paper it is used ZSM-5 and I developed new catalyst by addition of cerium to control acidity. The new catalyst was proved high conversion rate, when it was conversed from methanol to DME, there wasn't any additional material except DME and water, and I overlooked reaction temperature, reaction time, amount of catalyst, amount of added cerium, effect of water content in methanol, reaction temperature by making change of reaction time. I have conclude that conversion rate to DME was increased as increased of catalyst amounts. The best catalyst condition of without additional product was treated poisoning from ZSM-5 to 5% cerium and new catalyst was not effected in purity of fuel methanol.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.369-373
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• 2002

The liquid phase oxidation of p-xylene has been carried out with oxygen-enriched gas, and the manganese component was precipitated probably via over-oxidation to $Mn^{4+}$. The precipitation increased with rising oxygen concentration in the reaction gas and occurred mainly in the later part of the oxidation. The activity of the reaction decreased, and the blackening of the product and side reactions to carbon dioxide increased with the degree of precipitation. Precipitation can be decreased with the addition of metal ions, such as cerium, chromium and iron.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2349-2356
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• 2014

The recycling technology by the catalytic conversion is one of the most promising techniques for the $CO_2$ treatment of coal burning power plant flue gases. The conversion of $CO_2$ to valuable product of $CH_4$ can be used as a fuel to run the turbine for electricity generation. Through this technique, the amount of coal needed for the combustion in a gas turbine can be reduced as well as $CO_2$ emissions. Therefore, a series of catalysts based on cerium oxide doped with copper, nickel and manganese were prepared by impregnation method. From the characterization analysis, it showed that the prepared catalysts calcined at $400^{\circ}C$ were amorphous in structure with small particle size in the range below 100 nm. Meanwhile, the catalyst particles were aggregated and agglomerated with higher surface area of $286.70m^2g^{-1}$. By increasing the calcination temperature of catalysts to $1000^{\circ}C$, the particle sizes were getting bigger (> 100 nm) and having moderate crystallinity with lower surface area ($67.90m^2g^{-1}$). From the catalytic testing among all the prepared catalysts, Mn/Ce-75/$Al_2O_3$ calcined at $400^{\circ}C$ was assigned as the most potential catalyst which gave 49.05% and 56.79% $CO_2$ conversion at reaction temperature of $100^{\circ}C$ and $200^{\circ}C$, respectively.

• Steel and Composite Structures
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• v.24 no.1
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• pp.15-22
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• 2017

A green biosynthesis method is described for the preparation of Polyaniline (PANI)-cerium dioxide ($CeO_2$) nanocomposites in different media via in-situ oxidative polymerization procedure. The effect of various media including use of HCl, Lemon Juice, Beverage, White Vinegar, Verjuice and Apple vinegar extracts on the particles size, morphology as well as the conductivity of $PANI-CeO_2$ nanocomposites was investigated. The electron-withdrawing feature of $CeO_2$ increases doping level of PANI and enhances electron delocalization. These cause a significantly blue shift of C = C stretching band of quinoid from $1570cm^{-1}$ to $1585cm^{-1}$. The optical properties of the pure material and polymeric nanocomposites as well as their interfacial interaction in nanocomposite structures analyzed by UV-visible spectroscopy. The DC electrical conductivity (${\sigma}$) of as-prepared HCl doped PANI and a $PANI-CeO_2$ nanocomposite measured by a four-probe method at room temperature was studied.